INTERVENTIONS TO MIMIC THE EFFECTS OF CALORIE RESTRICTION

Abstract: Long term calorie restriction has the benefit of increasing life span. Methods to screen interventions that mimic the effects of calorie restriction are disclosed. Extensive analysis of genes for which expression is statistically different between control and calorie restricted animals has demonstrated that specific genes are preferentially expressed during calorie restriction. Screening for interventions which produce the same expression profile will provide interventions that increase life span. In a further aspect, it has been discovered that test animals on a calorie restricted diet for a relatively short time have a similar gene expression profile to test animals which have been on a long term calorie restricted diet.

Description: INTERVENTIONS TO MIMIC THE EFFECTS OF CALORIE RESTRICTION Background of the Invention Field of the Invention For years, researchers have attempted to identify biomarkers of aging to facilitate the identification of interventions that might slow or reverse the aging process. Dietary calorie restriction (CR) is the only well- documented method for extending life span in homeothermic vertebrates, and is the most effective means known for reducing cancer incidence. Although many of the physiological consequences of CR were described 65 years ago, there is no consensus regarding its mode of action. Consequently, there has been no practical method of identifying interventions that might mimic such calorie-restriction effects. Rather, a researcher would have to wait the test animal's lifetime to determine whether a particular intervention impacted life- span and/or cancer incidence. Description of the Related Art Mammals seem to share a common set of genes, and yet they have widely differing life spans. It is impossible to know at present whether the differences in life spans are due to differences in the sequence of specific genes, or to differences in their expression. However, it is clear from many years of study in dozens of laboratories that long term reduction m r dietary calorie consumption (CR) delays most age-related physiological changes, and extends life span in all species tested, provided malnutrition is avoided (Weindruch, et al. The Retardation of Aging and Disease by Dietary Restriction (Charles C. Thomas, Springfield, II, 1988)). These studies also have shown that CR is the most effective means now known for reducing cancer incidence and increasing the mean age of onset of age-related diseases and tumors in homeothermic vertebrates (Weindruch et al. (1982) Science 215: 1415). Thus, it seems clear that life spans can be extended through a relatively simple dietary regimen. However, there are no studies on the effects of short term calorie restriction on metabolism and gene expression. One report has been published of gene expression profiling in muscle (Lee et al. (1999) Science 285: 1390) In these studies, many age related changes in muscle gene expression appeared to be prevented or reversed by CR. The expression profiles of 6500 genes were compared among old, long-term CR and control mice, and young control mice. Some age-related changes in muscle gene expression appeared to be wholly or partially prevented by CR. Summary of the Invention The present invention contemplates a method of identifying interventions within a short time frame that mimic the effects of calorie restriction. Such interventions will lead to increased life span, reduce cancer incidence, and/or increase the age of onset of age-related diseases and tumors. In a preferred embodiment a method of identifying an intervention that mimics the effects of caloric restriction in cells is disclosed, comprising the steps of : obtaining a biological sample; waiting a specified period of time; assessing changes in gene expression levels, levels of RNA, protein, or protein activity levels related to one or more biomarkers of aging; and identifying said intervention as one that mimics the effects of caloric restriction if one or more changes in said levels also occurs in caloric restriction. The biological sample may be either in vitro or in vivo. In a preferred embodiment, the biological sample comprises cells. In a more preferred embodiment, the cells are obtained from a mammal. In an even more preferred embodiment, the mammal is a mouse. In one embodiment, the change in gene expression levels, levels of RNA, protein, or protein activity levels corresponds to a change in gene expression for a gene encoding a chaperone protein. In a preferred embodiment, the chaperone protein is GRP78. In one embodiment, said biomarker of agingis apoptosis. In another preferred embodiment, said biomarker is aging. In another preferred embodiment, the biomarker of aging is a production of cancer cells. In another preferred embodiment, the biomarker of aging is production of stress proteins and chaperones. In another preferred embodiment, the biomarker of aging includes genes for the inflammation response. In another preferred embodiment, the biomarker of aging includes transmembrane channels/transporter proteins. In another preferred embodiment, the biomarker of aging includes genes for transcription factors. In another preferred embodiment, the biomarker of aging is amylase 2. In a preferred embodiment, the changes in said gene expression level, levels of RNA, protein, or protein activity levels related to one or more biomarkers of aging occur in 6 weeks or less. In a more preferred embodiment, the changes in said gene expression levels, levels of RNA, protein, or protein activity levels related to one or more biomarkers of aging occur in four weeks or less. In an even more preferred embodiment, the changes in said gene expression levels, levels of RNA, protein, or protein activity levels related to one or more biomarkers of aging occur in two weeks or less. In a most preferred embodiment, the changes in said gene expression levels, levels of RNA, protein, or protein activity levels related to one or more biomarkers of aging occur in about two days or less. In a one embodiment, changes in gene expression are evaluated using a gene chip. In a preferred embodiment, the gene chip contains genes for stress proteins and chaperones. In another preferred embodiment, the gene chip contains genes for the inflammation response. In another preferred embodiment, the gene chip contains genes associated with apoptosis. In another preferred embodiment, the gene chip contains genes for transmembrane channels/transporter proteins. In another preferred embodiment, the gene chip contains genes for transcription factors. In another preferred embodiment, the gene chip contains genes for amylase 2. In an alternate embodiment, the biological sample is a test animal. In a preferred embodiment the disclosed method additionally comprises determining changes in said levels in a reference animal, wherein the embodiment, the test animal is a test animal having identifying characteristics of a long-term calorie- restricted animal wherein the reference animal is an older test animal that has been on a calorie restricted diet for less than about 6 weeks and wherein said changes are used in said identifying said intervention as one that mimics the effects of calorie restriction. In a more preferred embodiment, the reference animal has been on a calorie restricted diet for less than about 4 weeks. In an even more preferred embodiment, the reference animal has been on a calorie restricted diet for less than about 2 weeks. In a preferred embodiment, the test animal is a mouse. In a preferred embodiment, changes in gene expression are assessed in the test animal. In a more preferred embodiment, the disclosed method further comprises: obtaining a gene expression profile from a calorie-restricted reference animal; comparing changes in gene expression for the test animal to the gene expression profile of the calorie-restricted reference animal; and identifying said intervention as one that mimics the effects of calorie restriction if the gene expression profile of the test animal is statistically similar to the gene expression profile of the calorie restricted animal. In a more preferred embodiment, the gene expression profile of the test animal is determined to be statistically similar to the gene expression of the calorie restricted animal by oneway ANOVA followed by Fisher's test ψ< 0.05). In another aspect of the invention, a system is disclosed for identifying an intervention that mimics the effects of calorie restriction in a test animal comprising a test animal and a gene chip comprising genes known to have altered expression during calorie restriction. In a preferred embodiment, the gene chip comprises genes selected from the group consisting of genes for stress proteins/chaperones, apoptosis, inflammation response, transmembrane channels/transporter proteins, transcription factors and amylase 2. . For purposes of summarizing the invention and the advantages achieved over the prior art, certain objects and advantages of the invention have been described above. Of course, it is to be understood that not necessarily all such objects or advantages may be achieved in accordance with any particular embodiment of the invention. Thus, for example, those skilled in the art will recognize that the invention may be embodied or carried out in a manner that achieves or optimizes one advantage or group of advantages as taught herein without necessarily achieving other objects or advantages as may be taught or suggested herein. - Further aspects, features and advantages of this invention will become apparent from the detailed description of the preferred embodiments which follow. Brief Description of the Drawings These and other feature of this invention will now be described with reference to the drawings of preferred embodiments which are intended to illustrate and not to limit the invention. feeding, 5 mice from each dietary group were killed. Their weights after 24 h of fasting were 22.96 ± 1.49 for CR and 37.12 + 1.19 g for control mice. GRP78 mRNA (A) and ERp72 mRNA (B) from control (closed circle) and CR (open circle) mice were quantified using dot-blots. RNA loading and transfer were normalized using data obtained from serial probings for 18S ribosomai RNA and S-ll mRNA. Similar results were obtained with both control probes. CR and control mice, fed once daily for 30 days, were fasted for 24 hours and killed (π= 5, 0 time point) or refed and killed at the times specified (n= 5 for each time point). + represents P < 0.01 significance of difference between CR and control at each time point. * represents P < 0.01 significance of difference from the 0 time point within each dietary group. The 0 and 24 hour times points are the same data set. FIG. 2. The gene and tissue specificity of the chaperone feeding response. A, The domain of chaperone genes responsive to feeding was determined by quantifying hepatic chaperone mRNA abundance using RNA from mice fasted for 48 hours (n=6; open bars) or from mice fasted 48 hours, refed and killed 1.5 h later (n=6; filled bars). The mR As were quantified by dot-blotting and Northern blotting. There was no significant difference in the results obtained with either technique. The dot-blotting results are shown. B, Liver, kidney, and muscle GRP78 mRNA from 24-hour fasted mice (n=4), and from 24-hour fasted mice 1.5 hours after feeding (n=5). These data were from different mice than used in panel A. The statistical significance of the results are indicated (*, P< 0.05; **, P< 0.01; ***, P< 0.001). FIG. 3. Effects of CR on hepatic pre-mRNA and GRP78 mRNA abundance. A, RNase protection of pre-mRNA and mRNA in CR and control mice. Hepatic RNA was purified from control and CR mice and hybridized with an RNA probe for transcripts spanning the third intron and fourth exon boundary of the GRP78 gene. The precursor mRNA protected a 223 base region of the probe, labeled GRP78 pre-mRNA, while the GRP78 mRNA protected a 1 13 base fragment, so labeled in the figure. A probe for S-ll mRNA coding sequences was included in each reaction as an internal control. It protected a 185 base fragment labeled S-II mRNA in the figure. Lane 1 shows the protected fragments produced by the GRP78 probe and mouse liver RNA. Lane 2 shows the fragments produced by the S-ll probe hybridized to yeast total RNA. Lane 3 shows the results produced by the S-ll probe hybridized to mouse liver RNA. Lanes 4, 6, and 8 show the results produced by hepatic RNA from control mice. Lanes 5, 7, and 9 show the results with RNA from CR mice. Quantification of the abundance of the protected fragments representing the GRP78 mRNA (B) and pre-mRNA (C). Studies such as those shown above were conducted using hepatic RNA from 6 CR and 6 control mice. The intensity of the protected fragments was quantified with a phosphorimager. The intensities of the pre-mRNA and mRNA fragments were normalized to the intensity of the protected fragment representing S-ll mRNA. Statistical significance is indicated as in the legend to Fig. 2. Fig. 4. Effects of feeding on hepatic GRP78 mRNA and pre-mRNA abundance. A, RNase protection of probes for hepatic GRP78 pre-mRNA and mRNA in mice after 48 hours of fasting (n=5), or 1.5 h after feeding of 48-hour fasted mice (n= 5). RNA purified from liver was hybridized either to a probe for primary protected fragment (labeled S-ll + GRP78; lanes 7-12), or to a probe for primary transcripts spanning the exon 7 and intron 7 boundary, which protected a 200 nucleotide fragment (labeled S-ll + tGRP78, lanes 13- 18), as indicated in the figure. GRP78 mRNA produced a 143 nucleotide fragment representing GRP78 mRNA, as indicated in the figure. A probe for S-ll mRNA coding sequences was included in each reaction as an internal control. With this probe, S-ll mRNA protected a 277 nucleotide fragment, labeled S-ll mRNA in the figure. Lane 1, RNA markers. Lanes 2-6, hybridization of the indicated probes with yeast tRNA. Lanes 7-12, hybridization of the GRP78 and S-II probes with RNA from fasted (lanes 7-9) and refed (lanes 10-12) mice. Lanes 13-18, hybridization of tGRP78 and S-ll probes with RNA from fasted (lanes 13-15) and refed (lanes 16-18) mice. Quantification of the abundance of the protected fragments representing the GRP78 mRNA (B) and pre-mRNA (C). Studies such as those shown above were conducted using hepatic RNA from 6 CR and 6 control mice. The intensity of the protected fragments was quantified and normalized as described in Fig. 3 above. Statistical significance is indicated as in the legend to Fig. 2. FIG. 5. Effects of protein synthesis inhibitors on the feeding response of GRP78 (A) and PEPCK (B) mRNA. Mice fasted for 48 h were injected i.p. with vehicle and after 1 hour injected a second time i.p with vehicle (Refed + Sham; n-6). Mice fasted for 48 hours were injected i.p. with vehicle 30 min before and 30 min after feeding (Refed +Sham, n=6). Mice fasted for 48 h were injected i.p. with cycloheximide and after 1 hour injected a second time i.p with cycloheximide (Fasted + Cycloheximide; n=6). Mice fasted for 48 h were injected i.p. with cycloheximide 30 min before and 30 min after feeding (Refed + Cycloheximide; n=6). Mice fasted for 48 h were injected i.p. with puromycin and after 1 hour injected a second time i.p with puromycin (Fasted + Puromycin; n=6). Mice fasted for 48 h were injected i.p. with puromycin 30 min before and 30 min after feeding (Refed + Puromycin; n=6). GRP78 and PEPCK mRNA abundance were determined using purified hepatic RNA. Bars without common superscripts are significantly different {P< 0.005). FIG. 6. Regulation of the fasting-feeding response by insulin, dibutyryl-cAMP, glucagon, and ingestion of mineral oil and cellulose. A, Groups of six mice were fasted for 48 h and treated as follows: Fasted + Sham mice were injected with vehicle and 1 h later vehicle injected a second time; Fed + Sham mice were sham injected with vehicle 30 min before and 30 min after feeding; Fed+cAMP mice were injected with dibutyryl-cAMP and theophylline 30 min before and 30 min after feeding; Fed + glucagon mice were injected with glucagon 30 min before and 30 min after feeding; Fasted Diabetic-. Sham mice, previously rendered diabetic with STZ, were vehicle injected and 1 h later vehicle injected a second time; Fed Diabetic+Sham, STZ-diabetic mice were sham injected with vehicle 30 min before and 30 min after feeding; Fed Diabetic+cAMP, diabetic mice were injected with dibutyryl-cAMP and theophylline 30 min before and 30 min after feeding. All mice were killed 1 h after their last injection. Total RNA was isolated from the liver and subjected to dot-blot analysis. Bars with no common superscripts are significantly different {P< 0.005). B, Effects of mineral oil and cellulose ingestion on liver GRP78 mRNA abundance. Groups of six mice were fasted for 48 h and treated as follows: Fasted, mice were fasted for 48 h and killed; Fed, mice were fasted and mineral oil, and killed 1.5 h later. Significance is indicated as in the legend to Fig. 5. FIG. 7. Effects of adrenalectomy and dexamethasone administration on the expression and regulation of hepatic GRP78 mRNA. Groups of six mice were fasted for 48 h and treated as follows: Fasted + Sham, sham-operated mice were injected with vehicle IP 7.5 h and 1.5 h before they were killed; Fed + Sham, sham-operated mice were injected with vehicle IP 6 hours before and 30 min after feeding, and mice were killed 1 h after the last injection; Adx Fasted + Sham, adrenalectomized mice were injected with vehicle IP 7.5 h and 1.5 h before they were killed; Adx Fed+ Sham, adrenalectomized mice were injected with vehicle IP 6 hours before and 30 min after feeding, and the mice killed 1 h later; Adx Fasted + Dex, adrenalectomized mice were injected IP with dexamethasone 7.5 h and 1.5 h before they were killed; Adx Fed + Dex, adrenalectomized mice were injected IP with dexamethasone 6 hours before and 30 min after feeding, and killed 1 h later. Significance is indicated as in the legend to Fig. 5. FIG. 8. Effects on CR on the 22 genes which increased with age. The upper line represents the 7 genes which were not affected by LT-CR . The middle line represents the 9 genes which decreased in old by LT-CR. The bottom line represents the 6 genes which decreased in young and old by LT-CR. FIG. 9. Effects on CR on the 26 genes which decreased with age. The upper line represents the 3 genes which increased in young and old by LT-CR . The middle line represents the 10 genes which increased in old by LT-CR. The bottom line represents the 13 genes which were not affected by LT-CR. FIG. 10. Effects of CR on 36 genes which did not change with age. The top line represents the 5 genes which increased in young and old by LT-CR. The second from top line represents the 8 genes which increased in old by LT-CR. The third from top line represents the 10 genes that decreased in old by LT-CR. The bottom line represents the 13 genes that decreased in young and old by LT-CR. Fig. 11. Average of pairwise comparison of the global gene expression correlation coefficient for each possible pair of mice. FIG. 12. Average of pairwise comparison of the global gene expression correlation coefficient for each possible pair of mice. Detailed Description of the Preferred Embodiment While the described embodiment represents the preferred embodiment of the present invention, it is to be understood that modifications will occur to those skilled in the art without departing from the spirit of the invention. The scope of the invention is therefore to be determined solely by the appended claims. The effects of long term calorie restriction include increases in the rate of clearance of serum proteins, including glucose damaged serum proteins, from the blood as well as changes in gene expression. For example, long term calorie restriction affects expression of stress proteins/ chaperones, genes involved in apoptosis, the inflammation response, transmembrane channels and transporter proteins, transcription factors and others. Many of the chaperone genes are stress inducible. Subsets of chaperones are induced by different physiological stressors. For example, the majority of the known endoplasmic chaperones are induced by stresses that produce malfolded or improperly glycosylated proteins in the ER. This unfolded protein response pathway also may adjust the level of protein trafficking through the ER to the level of ER chaperones. Other chaperones, such as the abundant cytoplasmic chaperone HSC70 are normally thought of as constitutively expressed. The present invention is based in part on the finding that certain chaperone genes are down regulated by calorie restriction (such regulation is thought to be mediated through the insulin and glucagon pathways). The expression of Erp72, Erp57, GRP 170, GRP78, GRP94, HSC70, Calnexin, and Calreticulin are particularly affected by calorie restriction. The fasting mRNA and protein levels of nearly every ER chaperone studied were found to be significantly and consistently reduced in the livers of CR mice chronically fed a low calorie diet. In the case of GRP78, levels decreased by approximately 66%. Further, the reduction in chaperone mRNA levels was proportional to the reduction in calorie consumption. The fewer calories consumed, the lower the level of chaperone mRNA. We subsequently found that fasting chaperone mRNA levels changed over the course of 2 weeks in response to different levels of chronic calorie consumption. The more calories consumed per week, the higher the chaperone levels. Chaperone mRNA levels respond more rapidly to calorie consumption. mRNA for most ER chaperones, and for the major cytoplasmic chaperone, HSC70, are dynamically responsive (within 1.5 h) to each meal, and to the number of calories consumed. Features of this induction distinguish it from the unfolded protein response. The feeding induction was observed in kidney and muscle tissue, as well as in the liver. Postprandial changes in glucagon, in conjunction with insulin, were found to be the key mediators of this induction. Chaperone mRNA abundance responds within 1.5 h to caloric intake. Insulin and glucagon may be important for the response. This feeding response is rapid. By 1.5 hours after feeding, ER chaperone mRNAs were at or near their maximum level of induction. This feeding-related induction is not limited to one strain of mouse or to one species. Further, the response is found in tissues other than liver. Thus, it is a response which is generally important to the physiology of a variety of cell types in vivo. Because many chaperones are relatively stable proteins, their protein levels change more slowly in response to caloric intake than their mRNAs. For example, GRP78 protein has a half-life of over 24 hours in cultured cells. We found that GRP78 protein levels change only over a span of several days in response to changes in average daily calorie consumption. In this way, many chaperones may effectively integrate the rapid mRNA responses to feeding into longer term changes in chaperone protein levels. Long term differences in average calorie consumption do lead to differences in the hepatic levels of both ER and some cytoplasmic chaperones. feeding. Similar RNase protection results were obtained with hepatic RNA from chronically CR mice. Thus, both feeding and CR transcriptionally alter the expression of the chaperone genes. Puromycin led to partial induction of GRP78 mRNA. It is unlikely that induction of the mRNA by cycloheximide is due to stabilization of the transcript by polysome aggregation. While cycloheximide protects some mRNAs from inactivation and degradation in this way, puromycin does not. Rather, it inhibits translation by polysome dissociation. Thus, maintenance of low hepatic GRP78 mRNA levels most likely requires the action of an unstable repressor of GRP78 gene expression in fasted mice. In the presence of inhibitors of translation, this repressor may decay, releasing the gene from repression. Second, there was no augmentation of GRP78 mRNA induction when feeding and inhibition of translation were combined. While partial induction of the mRNA was found in puromycin treated mice, feeding induced the mRNA to the same level found in the absence of the inhibitor. Further, cycloheximide induced the mRNA to the same extent. Without being bound to any particular mechanism, it is suggested that the inhibitors and feeding may induce the gene through a common pathway. Third, since feeding fully induced GRP78 mRNA in puromycin treated mice, de novo protein synthesis is not required for the feeding response. Preexisting signaling and regulatory factors mediate the response. Fourth, the feeding response cannot result from a postprandial increase in protein trafficking through the ER. Enhanced ER de novo protein trafficking can induce chaperone mRNA. However, no such increase could have occurred in the presence of puromycin. Fifth, the unfolded protein and growth factor responses are not involved in the induction of chaperones by feeding. Cycloheximide blocks the unfolded protein and growth factor responses. We are aware of only one manipulation besides feeding capable of inducing ER chaperone mRNA in the presence of cycloheximide. GRP mRNAs are induced by cellular hypoxia in culture, and this induction is independent of cycloheximide treatment. Whether the feeding and hypoxia response share common molecular pathways is unknown at present. Feeding is well-known to decrease glucagon and increase insulin levels. Both glucagon and dibutyryl-cAMP blunted the feeding induction of GRP78 mRNA. Thus, glucagon is a negative regulator of GRP78 expression in vivo. The feeding induction of GRP78 mRNA was significantly reduced in STZ-diabetic mice. Without being bound to any particular mechanism, this result and the absence of a feeding response in STZ-diabetic, dibutyryl-cAMP-treated mice indicate that the action of both hormones is required for the response. Other effectors which are known to respond to feeding were also examined. Luminal stimuli can promote the release of gastrointestinal hormones. For this reason, we determined whether luminal filling with a non-digestible mixture of mineral oil and cellulose could stimulate chaperone expression. A small but significant response was found. However, insulin and glucagon have a much stronger effect on chaperone mRNAs, indicating they are the signals primarily responsible for the feeding response. adrenal hormones, perhaps catecholamines, may partially blunt the chaperone mRNA response to feeding. However, the mechanism by which these hormones stimulate the feeding response is unknown at present. Overall, feeding rapidly and strongly induced the mRNA for the major cytoplasmic chaperone, HSC70, and most ER chaperones examined. Feeding also induced ER chaperone mRNAs in at least three different tissues. Feeding and CR regulated chaperone mRNA abundance at the transcriptional level. Without being bound to any particular mechanism, feeding appeared to release chaperone gene expression from the effects of an unstable inhibitor. Insulin was required, and glucagon and cAMP mediated the feeding response. Postprandial changes in glucagon levels may be the primary mediator of the response. Gastrointestinal and adrenal hormones, but not glucocorticoids also have a role in the feeding response. Surprisingly, changes in gene expression are also observed with short-term calorie restriction. These changes in gene expression are similar to the changes observed in long-term CR. Short-term calorie restriction occurs when switching a mature test animal to a diet which is about 50% less than a control diet for about 2-6 weeks. In a preferred embodiment, the test animal is a mature mouse and the mature mouse is switched to a calorie-restricted diet at about 31 months. Preferably, an intermediate diet which is about 20- 40% less than a control diet is employed for about two weeks before switching to a CR diet for an additional two weeks. Both long term and short-term CR produces its profound effects on mammalian physiology by affecting the expression of genes. To identify as broadly as possible the effects of caloric restriction on global patterns of gene expression, gene chip technology was utilized to characterize the effects of long and short term CR on the expression of approximately 11,000 mouse genes in the liver. Liver is an attractive organ for study, since it contains a number of cell types, allowing assessment of the effects of CR on hepatocytes, which are primarily responsible for the regulation of metabolism and blood sugar, neurons of the enteric nervous system, immune system cells in the blood, and vascular smooth muscle cells, among others. The methods of the present invention include the identification of interventions that mimic the effects of calorie restriction. Particularly contemplated by the invention are methods of identifying interventions that have an effect on life span, aging, and/or the development of age-related diseases and cancer. In certain embodiments, such methods comprise obtaining cells, exposing them to an intervention, and observing whether the intervention affects the gene expression profile, levels of RNA, protein, or protein activity related to one or more biomarkers of aging. Preferably, such changes in gene expression, RNA, protein, or protein activity levels would occur within four weeks of the intervention. More preferably, such changes would occur within two weeks of the intervention, and most preferably, such changes occur within two days of the intervention. Such methods permit the identification of pharmacological or other means of achieving a metabolic state similar to the profile observed with long and short-term CR. as well as animal assays. Preferably, however, the methods are carried out in live mammals. For example, transgenic mice having enhanced chaperone expression may be used to measure an intervention's ability to reduce cancer, apoptosis, and/or life span. Alternatively, the present methods may be used to identify interventions that mimic calorie restriction simply by measuring the intervention's ability to alter gene expression for a particular gene or set of genes in live mammals. Such methods allow identification of effective interventions in a short period of time. Interventions identified by the methods of the present invention may be pharmacological, surgical or otherwise. Combinatorial chemistry may also be used in order to screen a large number of pharmacological compounds. In general, the interventions identified by the present invention should be effective in the treatment of cancer, diabetes, age-related diseases and/or the extension of life span. While the described embodiment represents the preferred embodiment of the present invention, it is to be understood that modifications will occur to those skilled in the art without departing from the spirit of the invention. The scope of the invention is therefore to be determined solely by the appended claims. EXAMPLES Example 1 Long Term Calorie Restricted (LTCR) Animals and Treatments for Chaperone Studies Female, 28-month old mice of the long-lived F, hybrid strain C3B10RF, have been described previously. Mice were weaned at 28 d, housed individually and subjected to one of two diets. The control diet consisted of casein (high protein), 207.0 g/kg, DL-methionine, 4.0 g/kg, dextrose monohydrate, 301.8 g/kg, corn starch, 290.0 g/kg, cellulose, 702. g/kg, brewer's yeast, 8.0 g/kg, Harlan Teklad Vitamin Mix #40060, 10.0 g/kg, Harlan Teklad AIN-76 Mineral Mix #170915, 35.0 g/kg, calcium carbonate (CaC0 3 ), 3.0 g/kg, magnesium oxide (MgO), 1.0 g/kg, sodium fluoride (NaF), 2.3 mg/kg, sodium molybdate (Na2MoO-2H 2 0), 0.5 mg/kg. The 50% restricted diet consisted of casein (high protein), 362.0 g/kg, DL-methionine, 7.0 g/kg, dextrose monohydrate, 172.03 g/kg, corn starch, 153.1 g/kg, cellulose, 83.6 g/kg, brewer's yeast, 14.0 g/kg, Harlan Teklad Vitamin Mix #40060, 17.5 g/kg, harlan Teklad AIN-76 Mineral Mix #170915, 61.25 g/kg, calcium carbonate (CaC0 3 ), 5.25 g/kg, magnesium oxide (MgO), 1.75 g/kg, sodium fluoride (NaF), 3.0 mg/kg, sodium molybdate (Na2MoO-2H 2 0), 0.9 mg/kg. From weaning, control mice were fed 4.8 g of the control diet on Monday through Thursday. On Friday they were fed 13.8 g of control diet. This feeding regimen provided 450 kJ/wk. From weaning, the 50% calorie restricted (CR) mice were fed 4.6 g of the restricted diet on Monday and Wednesday, and 6.9 g on Friday. This regimen provided 225 kJ/wk. Each dietary group received approximately equal amounts of protein, corn oil, minerals and vitamins per gram body weight. The amount of carbohydrates consumed varied between groups. Beginning 30 d before these studies, the control mice were fed 4.1 g (54.44 kJ) control diet daily at 0900 h. The 50% restricted mice were fed 2.3 g of restricted diet and 50% less dietary energy than normally thought to be required for a typical mouse {Subcommittee on Laboratory Animal Nutrition & Committee on Animal Nutrition 1978 ID: 5480} All food was routinely consumed within 30 min. Retired male Swiss-Webster breeder mice were purchased from Jackson Laboratories. Beginning 30 days before the studies, the mice were fed Monday and Wednesday 11 g and Friday 16.6 g of the control diet daily at 0900 h. In fasting-feeding studies, mice were deprived of food for 48 h, fed 5.5 g of the control diet at 0900 h, and killed 90 min later. The food was consumed within 30 min. Diabetes was induced by three weekly intraperitoneal injections of streptozotocin [10 mg/100 g body weight (b.w.)] in 50 mM sodium citrate, pH 4.5. Mice were diabetic one week after the last injection. Only mice with blood glucose level higher than 3 mg/ml were used. Mice injected with equivalent volumes of sodium citrate served as controls for the STZ- diabetic mice. Adrenalectomized and sham-operated mice were purchased from Jackson Laboratories. Dibutyryl cAMP (Sigma; 18 mg.100 g b.w.), and theophylline (Sigma; 3 mg/100 g b.w), glucagon (Sigma; 300 μg/100 g b.w.), dexamethasone (Sigma; 125 μg/100 g b.w), cycloheximide (Sigma; 4 mg.100 g b.w.), and puromycin (Sigma; 10 mg.100 g b.w.), were administered intraperitonealy to mice as specified in the figure legends. Mice received two doses of each drug or drug combination. The first injection was administered 30 min before feeding, and the second injection was administered 30 min after feeding. Mice were killed 1.5 h after the start of feeding. Drug-injected mice consumed similar amounts of food as control animals during the feeding period. All animal use protocols were approved by the institutional animal use committee of the University of California, Riverside. Example 2 RNA Isolation and Quantification for Chaperone Studies Mice were killed and the livers, kidneys, and muscle were removed. Muscle from the hind legs and back was removed and pooled for each animal. Tissues were flash frozen in liquid nitrogen. Approximately 0.2 g of frozen tissue was homogenized for 40 s in 4 ml of TRI Reagent (Molecular Research Center, Cincinnati, OH) using a Tekmar Tissuemizer (Tekmar, Ciπcinnait, OH) at a setting of 55. RNA was isolated as described by the TRI Reagent supplier. RNA was resuspended in FORMAzol (Molecular Research Center) and Northern and dot blots were performed using 20 and 10 μg of RNA respectively. The RNA was analyzed using Northern blots to verify its integrity. Dot blots were used to quantify mRNA levels (24; 27). Specific mRNA levels were normalized to the level of total RNA and/or mRNA present in each sample using hybridization with radiolabeled complementary DNA to 18S rRNA and/or transcription factor S-ll, as indicated in the figure legends (12; 27). The murine ERp72 2.5 kb cDNA was excised with _?_røHI from pcD72-1 (19). The 1235 bp murine GRP75 coding fragment was excised with Hind\\\ from pG7z-PBP1.8 (6). A 1.5 kb coding fragment of GRP78 cDNA was produced by digestion of p3C5 with fcoRI and Pst\ (15). A 1.4 kb hamster GRP94 coding fragment was produced by f.oRI and Sa/ digestion of p4A3 (15). A 664 bp coding 2.4 kb cDNA of murine PDI was excised from pGEM59.4 with <___. and Bamti\ (19). A 1 kb coding fragment of hamster GRP170 cDNA was excised with EcoR\ and Xho\ from pCRtmll (16). The 1.9 kb cDNA of murine ERp57 was excised with Hind\\\ and Sst\ from pERp61 (18). The 1 kb cDNA of murine HSC70 was excised with Pst\ from phsc1.5 (9). The 1.3 kb PEPCK coding fragment was produced by Sphl followed by Sal\ digestions of pGEM5ZEP (a gift from Dr. Ganner D.K. Vanderbilt University School of Medicine, Nashville, TN). The fragments were isolated by agarose gel electrophoresis and radioactively labeled using a "QuickPrime Kit (Pharmacia) according to the manufacturer's instructions. Example 3 RNase Protection Assays for Chaperone Studies A 223 base pair (bp) DNA fragment made up of 110 bases of intron 3 and all 113 bases of exon 4 of the mouse GRP78 gene was synthesized by PCR using genomic DNA as template and inserted into pT7/T3 (Ambion, Austin, Texas). Two probes of the junction region of intron 7 and exon 7 of the GRP78 gene were produced by PCR using mouse genomic DNA as template. A 257-base fragment including all of exon 7 and the first 1 13 bases of intron 7 was produced. A 200-base fragment including all of exon 7 and the first 56 bases of intron 7 also was produced. The T7 RNA polymerase promoter was ligated to these PCR fragments using a Lig'nScribe kit as described by the supplier (Ambion). These constructs were used as template for the synthesis of [ 32 P]-labeled antisense RNA probes using a MAXIScript kit as described by the supplier (Ambion). RNase protection assays were performed using an RPA II kit as described by the supplier (Ambion). Hybridization of the 257-base RNA probe with GRP78 pre-mRNA protected all 257-bases corresponding to exon 7 and the first 1 13 bases of intron 7. Hybridization of the 200-base RNA probe to pre-mRNA protected 200-bases corresponding to all of exon 7 and the first 56 bases of intron 7. Hybridization of either probe to GRP78 mRNA protects the 143-bases complementary to exon 7. A 185- and a 277-bp cDNA fragment of S-ll cDNA was synthesized and subcloned into pT7/T3 (12). [ 32 P]-labeled RNA probes for the sense and antisense transcripts were synthesized in vitro and RNase protection assays performed. Hybridization with S-ll mRNA protected the entire 185- or 277-base region of the probes. Protection of only the sense strand probes was detected. Quantitation of the hybridized fragments was determined with ImageQuaNT (Molecular Dynamics, Sunnyvale, CA). Example 4 Plasma Glucose and Insulin for Chaperone Studies Plasma glucose, insulin, and glucagon concentrations were determined using Glucose [HK] 10 (Sigma, St. Louis, MO), Rat Insulin RIA and Glucagon RIA kits (Linco Research, St. Charles, MO), as described by the suppliers. Statistical Analysis for Chaperone Studies The data shown in Figure 1 are expressed as means + SD for 5 mice at each time point. The effects of food deprivation and subsequent feeding on mice of each dietary group were analyzed using a one- way ANOVA followed by Fisher's test. The analysis determined whether individual time point means differed from time 0 means within each dietary group. It also determined the differences between the means of the control and CR groups at each time point. Differences of P < 0.05 were considered significant. Values are expressed as means + SD. Significance was determined with either Student's unpaired t-test [P< 0.95) or a one-way ANOVA followed by Fisher's or Tukey's tests { '< 0.01). All statistical analyses were performed with Minitab Statistical Software (Minitab, State College, PA). Example 6 Chronic and Acute Effects of Calorie Consumption on Hepatic Chaperone mRNA Feeding of the fasted mice rapidly induced the abundance of GRP78 and ERp72 mRNA (Figures IA and 1 B). A large increase in chaperone mRNA was detected by 1.5 h after feeding, the first time point studied. The 24-h fasting levels (0 time) of GRP78 and ERp72 mRNA were lower in the CR mice. The response to feeding was kinetically different in control and CR mice. Thus, the amount of food consumed affects the kinetics of the response. The integrated level of GRP78 and ERp72 mRNA over the entire 24-hour period was also less in the CR than in control mice. Similar results were obtained when the effects of feeding on HSC70, ERp57, and calreticulin mRNA were determined (data not shown). Thus, this represents a common response of chaperone gene expression to feeding. Example 7 Fasting-Feeding Induced Multiple Chaperone mRNAs in Multiple Tissues Mice were fasted for 48 hours and refed for 1.5 hours. Hepatic GRP78 mRNA was induced approximately 3-fold after this time (Figure 2A). The mRNA for the other ER chaperones investigated, ERp57, ERp72, GRP94, GRP170, PDI, and calreticulin, and for the most abundant cytoplasmic chaperone, HSC70, also were induced by feeding (Figure 2A). HSC70 was induced by nearly 3-fold. No changes in the mitochondrial chaperone GRP75 was detected in this study. By examining chaperone levels in other tissues of fasted and fed mice, we found that the feeding-related chaperone induction extends to at least kidney and muscle (Figure 2B). GRP78 mRNA induction is shown in the figure (Figure 2B). HSC70 mRNA was also induced in these tissues (data not shown). In studies not shown, we have found that a similar induction of hepatic chaperone mRNAs occurs in rat. Thus, the response is shared by other species. CR Reduces the Abundance of the GRP78 Primary Transcript RNase protection studies were used to investigate the responsiveness of the GRP78 mRNA and primary transcript to chronic differences in dietary calorie consumption. A probe was utilized for these studies designed so that the GRP78 primary transcript protected a 223 base RNA fragment representing the third intron-fourth exon boundary of the transcript (Figure 3A lane 1, upper band). The mRNA protected a 113 base fragment of the probe which represents the fourth exon of the gene (Figure 3A, lane 1, lower band). Much less of the 223 and 1 13 base GRP78 precursor and mRNA probes were protected by RNA from CR mice (Figure 3A, lanes 4-9). A probe for 185 bases of S-ll mRNA was included in each sample as an internal control (Figure 3A, lane 3). S-ll mRNA is unresponsive to CR or fasting-feeding (25). The unlabeled bands in Figure 3 represent RNase-resistant artifacts of the S-ll probe (Figure 3A, lane 2). When the amount of protected probe was quantified and normalized to the signal obtained from the S-ll probe, it became clear that the abundance of the chaperone precursor and mRNA were decreased to the same extent in the CR mice (Figure 3B). The same conclusion was reached using a probe for the boundary regions of intron 7 and exon 7. Consequently, CR decreases either the rate of GRP78 gene transcription or the stability of the GRP78 primary transcript. The data are not consistent with blocked or paused GRP78 gene transcription or changes in the stability of the mRNA in CR mice. Example 9 Fasting-feeding induction of the GRP78 primary transcript RNase protection studies also were used to investigate the fasting-feeding response. RNA isolated 1.5 h after feeding protected much more of a 257 base fragment representing the exon 7-intron 7 boundary of the primary transcript than RNA isolated from fasted mice (compare Fig. 4A, lanes 10-12 to lanes 7-9). Similar results were obtained with a probe in which 200 bases representing the exon 7-intron 7 boundary were protected (compare Fig. 4A, lanes 16-18 to lanes 13-15). In each case, RNA from refed mice also protected more of the 143 base fragment representing the exon 7 region of the mRNA (Fig. 4A). A probe for 277 bp of the S-II mRNA was present in each assay for use as an internal control. Quantification of these data, and normalization of the S-ll internal control demonstrated that the mRNA and the precursor RNA were induced by feeding to essentially the same extent (Fig. 4B and 4C). Similar results were obtained using the probe described earlier for the third intron-fourth exon boundary of the gene (data not shown). Without being bound to a specific mechanism, these data suggest the same molecular step is responsible for regulating the genetic responsiveness of chaperones to both acute and chronic changes in calorie consumption. This mechanism appears to involve changes in either the transcription or the stability of the primary transcript. Inhibitors of protein synthesis To investigate the physiological basis for the fasting-feeding response, studies were performed using inhibitors of protein synthesis. Fasted mice were treated with a dose of cycloheximide or puromycin sufficient to inhibit greater than 95% of protein synthesis in the liver. Treatment with cycloheximide strongly induced GRP78 mRNA in fasted mice (Fig. 5A). GRP78 mRNA also was strongly induced in cycloheximide- treated, refed mice. Puromycin treatment modestly induced GRP78 mRNA in fasted mice (Fig. 5A). Feeding of puromycin treated mice fully induced the mRNA. Thus, induction by feeding does not appear to require de novo protein synthesis. Further, these results suggest that the lower chaperone mRNA levels in fasted mice may involve the action of a rapidly turning over factor. The effects of the protein synthesis inhibitors on PEPCK mRNA also was determined as a positive control. The effects of fasting-feeding and cycloheximide treatment on this mRNA are well known. Fasting induced, and feeding repressed PEPCK mRNA, as expected (Fig. 5B). Also, as expected from published data, cycloheximide increased PEPCK mRNA in both fasted and refed mice through its effects on PEPCK mRNA stability. The effects of the inhibitors on PEPCK mRNA levels indicate the inhibitors were efficacious in these studies. Example 11 Pancreatic hormones and glucose The physiological hallmarks of the fasting-feeding transition are increased circulating insulin and decreased circulating glucagon. In the studies shown in Fig. 6, fasted and refed sham-injected mice had serum glucose concentrations of 84.4 ± 5.1 and 121.1 + 8.0 mg/dl, serum insulin concentrations of 0.491 ± 0.203 and 1.3 ± 0.256 pmol/ml, and serum glucagon concentrations of 143 + 22.4 and 81.4 + 13.2 pg/ml, respectively. To investigate whether these hormones are involved in the postprandial induction of GRP78 mRNA, the effects of cAMP, glucagon, and STZ-induced diabetes on the response were examined. Administration of either dibutyryl cAMP or glucagon reduced the response of GRP78 mRNA to feeding (Fig. 6A). Vehicle alone had no effect. Likewise, STZ-induced diabetes resulted in a blunted response to feeding although it did not modify the fasting level of GRP78 mRNA. When STZ-induced diabetes was combined with cAMP administration, the postprandial induction of GRP78 mRNA was obliterated. The mRNA remained at fasting levels Without being bound to any particular mechanism, these results suggest that glucagon, acting to increase intracellular cAMP levels, suppresses chaperone gene transcription, or possibly GRP78 pre-RNA stability. Further, they suggest that insulin is required for full responsiveness of the chaperone genes to decreased intracellular cAMP. Luminal filling Luminal filling can lead to the release of some gastrointestinal polypeptides. For this reason, we investigated the role of luminal stimuli on the chaperone mRNA response. Fasted mice were refed a nonnutritive paste of cellulose (a normal component of their regular diet) and mineral oil. The mice initially consumed the mixture enthusiastically. Stomach filling was confirmed for each mouse by postmortem examination. Cellulose-mineral oil consumption produced a minor but significant increase in GRP78 mRNA (Fig. 6B), without producing a change in plasma glucose, insulin, or glucagon concentrations. Example 13 Adrenal hormones To investigate the role of adrenal hormones in the postprandial induction of GRP78 mRNA, we examined the effects of feeding in adrenalectomized mice (Fig. 7). Neither adrenalectomy nor sham surgery had any effect on the fasting levels of GRP78 mRNA. However, adrenalectomy increased the magnitude of the postprandial induction of the mRNA by approximately 2-fold over that found in refed, sham-operated mice. The feeding response of GRP94, ERp72, and GRP170 were also enhanced in the adrenalectomized mice (data not shown). Thus, the increase is a generalized ER chaperone response. Administration of dexamethasone to adrenalectomized mice increased the basal level of GRP78 mRNA during starvation, although not significantly (Fig. 7). However, dexamethasone administration had no effect on the feeding induction of the gene, suggesting its absence from adrenalectomized mice is not responsible for the enhancement of the feeding response. Example 14 Preparation of test groups for short-term CR studies Three groups of 30 month old mice were utilized for these studies. Male B6C3F, mice were maintained as described (Dhahbi et al. (1998) J. Gerontol 53A: B180). Mice were weaned at 28 days and housed individually. The composition of the defined diets used have been described. They are formulated so that only the amount of carbohydrate consumed varied between the CR and control mice. A group of control mice was fed a purified, semi-defined diet from 6 weeks of age. Control mice consumed approximately 105 kcal per week from weaning. This is approximately 10% less than the amount of food thought to support optimal growth, fertility and fecundity in mice {Subcommittee on Laboratory Animal Nutrition & Committee on Animal Nutrition 1978 ID: 5480}. Subjectively, these mice appeared neither fat nor lean. A group of calorically restricted mice (CR mice) were fed a diet reduced in dietary carbohydrate such that the mice consumed approximately 40% fewer calories than control mice. The long term CR mice consumed approximately 55 kcal per week from weaning. The short term CR mice were fed 105 kcal until the age of 29 months. They were then fed 80 kcal of control diet for 2 weeks, followed by 55 kcal of CR diet for two fed a normal allotment of food Monday morning, and all the food was eaten within 45 minutes. They were fasted for 24 hours, and killed on Tuesday morning. At the time of use, the long term CR, short term CR and control mice weighed 22.8 ± 1.4, 25.2 ± 0.3 and 37.2 ± 2.4 g, respectively. The mice were approximately 30 months old when killed. Mice were killed by cervical dislocation and the liver rapidly removed and flash frozen in liquid nitrogen. Approximately 0.2 g of frozen liver was homogenized for 40 s in 4 ml of TRI Reagent (Molecular Research Center, Inc., Cincinnati, OH) using a Tekmar Tissuemizer (Tekmar Co., Cincinnati, OH) at a setting of 55. RNA was isolated as described by the supplier. GeneChip oligonucleotide-based high-density array RNA expression assays were performed according to the standard Affy etrix protocol. The biotinylated, fragmented cRNA was hybridized to the Mu1 I KsubA and Mu1 I KsubB GeneChip arrays (Affymetrix, Santa Clara, CA), which contain targets for more than 11,000 known mouse genes and ESTs. The arrays were washed, stained and scanned. Scanned image analysis and data quantification were performed using the Affymetrix GeneChip analysis suite v3.2 at default parameter settings. Resultant data were normalized by global scaling, allowing comparisons between any two experiments. The fold change analysis between all pairwise comparisons were performed by Affymetrix software. Since the average difference of a transcript is directly related to its expression level, an estimate of the fold change of the transcript between any two samples can be calculated. Fold change is an indication of the gene expression difference between any two given samples. To determine the effect of age, each 7-month-old mouse (n= 3) was compared to each 30-month-old mouse (n=3) in the same dietary group (control, LT-CR), generating a total of nine pairwise comparisons. The average of the all nine possible pairwise comparisons determines the fold change for the effect of age. Only fold change greater or equal to 1.8 (or less than or equal to -1.8) were retained. To determine the effect of LT-CR, each control mouse (n=3) was compared to each LT-CR mice (n=3) in the same age group (young, old). The average of the all nine possible pairwise comparisons determined the fold change for the effect of diet. Only fold change greater or equal to 1.8 (or less than or equal to -1.8) were retained. To determine the effect of ST-CR at old age in 2 or 4 weeks, each old control mouse (n=3) was compared to each ST-CR mouse (n=3), and to each ST-CR mouse (n=3). The average of each nine possible pairwise comparisons determines the effect of ST-CR in 2 or 4 weeks. Only fold change greater or equal to 1.8 (or less than or equal to -1.8) were retained. Effects of aging and calorie restriction on liver gene expression microarray profiles AGING EFFECTS We conducted microarray analysis of the hepatic expression of more than 11,000 genes in young and old (7 and 30 months) mice subjected to long-term CR (LT-CR). Our study also included a group of old control mice that were subjected to a very short-term (2 or 4 weeks; ST-CR). We found that of the 1 1,000 genes monitored, only 48 (0.5%) showed expression levels that are changed with aging in the control mice. 1. 46% of the genes that were altered by age showed an increase in gene expression (Table 1). Of the 48 genes that changed expression during aging (increased or decreased), the expression levels of 22 (46%) increased with age in control mice. These genes can be grouped into 6 classes (Table 1 ). The increase in expression of several members of the Stress Protein / Chaperone group (27%) indicates a marked stress response during aging in the livers of old control mice. The second group is composed of genes involved in inflammation processes. It represents 36% of all the genes for which expression increased with age. Key regulators of apoptosis also increased, suggesting that disregulation of apoptosis is associated with aging. TABLE 1 GROUPS OF GENES WHICH INCREASED EXPRESSION WITH AGE (more than 1.8 fold). LONG AND SHORT TERM CR (LT-CR AND ST-CR) EITHER OPPOSD OR HAD NO EFFECT ON THIS INCREASE. ("Early decrease" means that CR decreased expression at young age. "Late decrease" means that CR at old age) ] The italicized letter in parenthesis preceding the gene name indicates the gene group designation from Fig. 1. 2. 54% of the genes that changed during aging showed a decrease in gene expression (Table 2). Of the 48 genes that changed expression during aging, the expression of 26 (54%) decreased with age in control mice. One of the functional groups of genes that decreased involved cellular defense against - adverse redox conditions (glutathione-S-transferase like) and the oxidative metabolism of xenobiotics (cytochrome P450, 1a2). The decrease observed in the expression of genes involved in DNA replication and the cell cycle suggests a decrease in hepatocyte proliferative capacity during aging. A number of major urinary proteins also were decreased during aging. TABLE 2 GROUPS OF GENES WHICH DECREASED EXPRESSION WITH AGE (more than 1.8 fold). LONG- AND SHORT-TERM CR EITHER OPPOSE OR HAVE NO EFFECT ON THE AGE-RELAETD DECREASE IN GENE EXPRESSION. ("Early increase" means that CR effects were manifested at young age, and "Late increase" at old age) Ul -4 The italicized letter in parenthesis preceding the gene name indicates the gene group designation from Fig. 2. Example 16 CR Effects LT-CR and ST-CR had diverse effects on the 48 genes which changed expression with age. 1. LT-CR opposed the effects of aging on the expression of 58% (28 of 48) of the genes that changed expression with age For 28 out of 48 (58%) genes that increased or decreased with age, LT-CR opposed the change (Figs. 8 and 9). Of these 28 genes, 15 are genes that were decreased by LT-CR (Fig. 1) and 13 are genes that were increased by LT-CR (Fig. 2). Because these gene respond to both age and CR, there expression may be linked to factors which are determined by physiological age, not chronological age. Genes that are regulated by mechanisms related to physiological age are linked to life span and may serve as biomarkers of aging. ST-CR reproduced the effects of LT-CR on 19 of the 28 genes (68%) for which the age-related alterations were opposed by LT-CR. In this set of 19 genes, where the patterns of gene expression were highly homologous in the ST- and LT-CR groups, CR does not maintain a youthful gene expression profile, but rapidly induces a "slow-aging" profile. CR rapidly altered genes associated with stress response, inflammation, and the division and apoptosis of cells. Thus, expression profiling of these genes should prove useful in rapidly identifying CR mimetic drugs and treatments. 2. LT-CR did not affect the expression of 42% (20 of 48) of the genes that changed expression with age For the remaining 20 of the 48 genes (42%) that increased or decreased with age, gene expression was not altered by LT-CR (Figs. 8 and 9). Of these 20 genes, 7 increased with age but were not affected by LT-CR (Fig. 8), and 13 decreased with age but also were not affected by LT-CR (Fig.9). These results suggest that the expression levels of these genes, being independent of CR, do not depend on the rate of biological aging, but on the passage of time (chronological age). ST-CR actually influenced the expression of 12 of the 20 genes which seem to be responsive only to chronological age. More than half the 12 genes that respond to ST-CR are molecular chaperones and stress response proteins, or genes involved in DNA replication. Both of these groups are known to be nutritionally regulated and rapidly respond to metabolic alterations. 3. The expression of 36 genes was unchanged during aging but was responsive to ST-CR and/or LT-CR (Table 3) As reported above, only 0.50% of the 11,000 screened genes were differ__Mlγ expressed during aging in the liver of control mice. Thus, expression of the vast majority of the genes remain unchanged during aging. However, LT-CR differentially altered the expression of 36 of these genes in old and young mice (Fig. 10). The 36 genes include those for key metabolic enzymes, stress response proteins, and genes involved in immune and inflammatory responses. The age-independent effects of CR on these diverse groups of genes may be involved in mediating the life- and health-span extending effects of LT-CR. ST-CR reproduced the effects of LT-CR on 14 of the 36 (39%) genes (Fig. 10). Thus, 39% of these genes mimic the effects of LT-CR after only 4 weeks of ST-CR. These results indicate that a significant portion of the genetic reprogramming induced by LT-CR in this class of genes is reproduced rapidly. TABLE 3 GROUPS OF GENES FOR WHICH EXPRESSION WAS UNCHANGED BY AGING (less than .8 fold). LONG- AND SHORT-TERM CR EITHER INCREASE OR DECREASE THEIR GENE EXPRESSION. ("Early increase or decrease" means that CR effects were manifested at young age, and "Late increase or decrease" at old age) Ul The italicized letter in parenthesis preceding the gene name indicates the gene group designation from Fig. 3. 4. ST-CR Reproduced the majority of the effects of LT-CR on Gene Expression Of the genes which are commonly thought to be most important in the effects of CR, those that change expression with age, ST-CR reproduced the effects of 31 of the 48 changes induced by LT-CR (65%). Thus, in this important class of genes, ST-CR rapidly reproduced the effects of LT-CR. Of all the genes, including those that did not change expression with age, 45 of 84 (54%) of the genes were responsive to both LT-CR and ST-CR in the same way and to the same degree. These results indicate that the majority of the effects which might be attributed to the long term effects of diet on changes in gene expression are rapidly reproduced by very short-term CR. 5. ST-CR altered the expression of 60 genes that did not change with LT-CR or aging. Of the 60 genes that responded only to ST-CR, 33 were increased (Table 4) and 27 were decreased (Table 5). These genes encode stress proteins, metabolic enzymes, and cell growth mediators. Each of these classes of genes are known to rapidly respond to caloric intake. The liver plays a critical role in the adaptive response to environmental stimuli that alter energy requirements of the organism as a whole. This hepatic response to ST-CR may involve the modulation of diverse liver functions required for adaptation to the newly decreased nutritional intake. Although these genes may not be important in the extension of life-span by CR, they may be crucial to the successful physiological transition from one feeding status (control) to the calorically restricted status, a transition which appears to include a stress response in the liver. TABLE 4 GROUPS OF GENES WHICH INCREASED EXPRESSION WITH ST-CR (more than 1.8 fold). AGING AND LT-CR HAD NO EFFECT ON THE EXPRESSION OF THESE GENES. TABLE S GROUPS OF GENES WHICH DECREASED EXPRESSION WITH ST-CR (more than 1.8 fold). AGING AND LT-CR HAD NO EFFECT ON THE EXPRESSION OF THESE GENES. 6. LT-CR exclusively altered the expression of 30 genes at either young or old age, hut not at both ages. There were 30 genes that responded to CR in either young or old mice, but not in both age groups. For these genes, LT-CR increased the expression of 19 (Table 6), and decreased the expression of 11 (Table 7). This group of genes is unique and interesting because it is the only group in which LT-CR induced changes in expression (increases or decreases) in young mice were not observed in old mice. These effects of CR are in contrast to those observed for the other 3 groups of genes discussed above (Figs. 8-10). In these groups, the effect of LT-CR observed in young mice were always found in the old mice. ST-CR reproduced similar effects on 7 of 12 genes (58%) of the genes which changed expression in old LT-CR mice. Of these, 6 of 8 genes (75%) increased expression (Table 6) and 1 of 4 (25%) decreased expression (Table 7). Thus, ST-CR also reproduced the majority of these changes in old mice. OVERALL COI-CLUSIOI- Overall, only 2- to 4-weeks of ST-CR reproduced nearly 65% of the changes induced by LT-CR in old mice. These results strongly indicate that ST-CR can be used to rapidly evaluate the effects of drugs and treatments on the majority of the gene expression changes induced by LT-CR. GENES WHICH INCREASED EXPRESSION WITH LT-CR (more than 1.8 fold) EITHER IN YOUNG (EARLY INCREASE) OR OLD MICE (L INCREASE) ONLY. Ul © GENES WHICH DECREASED EXPRESSION WITH LT-CR (more than 1.8 fold) EITHER IN YOUNG (EARLY DECREASE) OR OLD MI (LATE DECREASE) ONLY. Streptozotocin (STZ) induces diabetes. Mice receiving three treatments with STZ were diabetic for about 4 weeks. Diabetes reduces insulin levels to almost zero. CR has a similar effect in that it lowers insulin levels, although not as low as in STZ-treated animals. Also, while CR lengthens life span, STZ has the opposite effect and shortens life span. Figure 11 shows pairwise comparison of global gene expression correlation coefficients for each possible mouse pair. The results indicate that hepatic gene expression is very different between young CR, young control and STZ-diabetic mice. In conclusion, lowering insulin in the pathological way found in serious diabetes is insufficient to produce the gene expression profile or the life-span effects observed with CR. Example 18 Gene expression in aminoguanidine treated mice Aminoguanidine is believed to retard aging by preventing cross-linking of protein initiated by the aldehyde form of glucose. However, mice fed aminoguanidine exhibited little or no effect on life span. However, a large effect on gene expression was observed (Figure 12). Gene expression for aminoguanidine- treated mice did not correlate with either old CR or old control. In conclusion, although aminoguanidine has little effect on aging in mice, major differences in gene expression are observed. These effects are not like those of CR, and this is consistent with the absence of a strong effect on the life-span of mice. Example 19 To determine whether certain interventions mimic calorie restriction in mice, the following groups of mice are prepared. Group 1: Controls Group 2: Troglitazone (synthetic proposed calorie restriction mimetic drug that lowers insulin levels in rats and mice, lowers blood pressure and triglycerides, inhibits free radicals, increases mitochondrial mass, and doesn't seem to change food intake in rodents): treatment starts at 10 months Group 3: 1GF-1 (natural proposed calorie restriction mimetic hormone that lowers both insulin and glucose levels and which may be directly involved in the basic mechanisms of aging; has rejuvenating effects on immune, muscular, and other systems): treatment starts at 12 months Group 4: ALT-711 (or other AGE breaking agent: proposed calorie restriction mimetic that acts by reversing the effects of elevated glucose levels as they occur or after they occur, rather than by reducing glucose levels): treatment starts at 18 months. Animals in all groups will receive the same, known amount of food throughout the study. Troglitazone and IGF-1 doses will be chosen to set glucose and insulin levels in the range for young or preferably calorie-restricted animals. Glucose and insulin will be measured but not controlled in the control ALT-711 is used that will remain constant over time. It is assumed that IGF-1 will be supplied by injection (3 times per week, minimum) unless a continuous delivery method can be arranged. The preferred dosage method is implantation of non-dividing IGF-1 -secreting cells, to attain steady IGF-1 levels, and if possible, this will be done. If this is not possible, IGF-1 will be obtained as a gift from Genentech or another manufacturer. Other possible alternatives to injection are: osmotic minipump; injection of IGF-1 into subcutaneous slow-release reservoirs; infusion by means of minipumps used by Celtrix; use of skin patches that allow slow-release to the body. There will be 60 animals in each longevity-testing group (LTG). Each LTG will be accompanied by another set of, on average, 40 similarly-treated animals, which will be set aside for sacrifice to permit biochemical assays and histological documentation of the condition of the animals at fixed ages (sacrifice group, SG). In the case of the IGF-1 and troglitazone groups, some animals will be earmarked for pilot dose- finding experiments in a manner that will allow the average SG size to remain at 40, as described below. The groups earmarked for dose-verification will be referred to as the pilot dose groups, or PDGs. For troglitazone, about a 2-month supply of each of three troglitazone diets (containing 0.1%, 0.2%, or 0.3% troglitazone) will be initially ordered. The main 0.2% troglitazone dose will be tested on a small pilot mouse population before committing the troglitazone group proper to this dose. If 0.2% troglitazone is not found to yield the expected changes in circulating insulin after 2 weeks on the 0.2% troglitazone, the diet will be changed to the more appropriate dose diet at that time and verified on a second small pilot mouse population. Similarly, some animals will be used for IGF-1 injection pilot experiments to determine the proper starting dose. At age 12 months: Sacrifice 3 animals/SG to obtain common baseline group of 12 animals to be compared to all subsequent results. This is the middle-aged universal control group. All subsequent data can be compared to the results for this pooled group. At age 12.5 months: Begin the IGF-1 PDG with 7 mice given the best estimated dose of IGF-1. Sacrifice two weeks later for determination of insulin and glucose levels. Begin a verification/second trial dose of IGF-1 at 13 months, 1 week of age, and sacrifice this second PDG at 13 months, 3 weeks of age. Assuming the assays for insulin and glucose can be completed in 1 week, this regimen will allow the final dose for the LTG to be determined prior to age 14 months. Similarly, at 12.5 months, place 7 mice on the 0.2% troglitazone diet. Two weeks later, sacrifice and assay for insulin and glucose. Begin adjusted-dose or verification dose group at 13 months, 1 week and sacrifice after two weeks. At age 14 months: Begin troglitazone and IGF-1 at the experimentally-determined or estimated optimal doses for each. in the LTG and the untapped portion of the IGF-1 SG) and/or order diet with a modified troglitazone content. Sacrifice three animals each from the SGs for the controls and the ALT- 11 groups and pool to create a common group of six animals for comparison to the IGF-1 and troglitazone groups. At age 18 months: same as at 15 months, but use 7 mice/SG for IGF-1 and troglitazone and 4 mice/SG for the control and for the ALT-711 group. Begin the ALT-711 groups on ALT-711 immediately after this sampling. At around 27 months ( " 24-30 months): Sample all remaining surviving SG mice. If the total initial numbers of mice in the sacrifice groups for treatments 1 , 2, 3, and 4 are 30, 50, 50, and 30, respectively, then if there were no mortality in any of these groups, there would be 20 animals left in each SG at the time of final sampling. But if we assume that only 1/3 of this number will be alive, then about 7 animals will remain to be sampled at the final sample time, or about the minimum required for statistical significance. If the mean survival rate at 27 month is over 73%, the 27 month end point may be postponed to a greater age. In addition to other biochemical markers, assays may include: heart and thymus volume and histology; autoantibody titer; T and B cell characteristics; protein or albumin concentration in bladder urine at sacrifice; molecular glycation indices; protein carbonyl content or other free radical/oxidation indices; and incidence of neoplasia, esp. of prostate and breast.

Claims: cells, comprising: obtaining a biological sample; exposing said biological sample to an intervention; waiting a specified period of time; assessing changes in gene expression levels, levels of RNA, protein, or protein activity levels related to one or more biomarkers of aging; and identifying said intervention as one that mimics the effects of caloric restriction if one or more changes in said levels also occurs in caloric restriction. 2. The method of claim 1, wherein said biological sample comprises cells. 3. The method of Claim 2, wherein said cells are obtained from a mammal. 4. The method of claim 3, wherein said mammal is a mouse. 5. The method of Claim 1, wherein said change in gene expression levels, levels of RNA, protein, or protein activity levels corresponds to a change in gene expression for a gene encoding a chaperone protein. 6. The method of Claim 5, wherein said gene encoding a chaperone protein is GRP78. 7. The method of Claim 1, wherein said biomarker is apoptosis. 8. The method of Claim 1, wherein said biomarker is aging. 9. The method of Claim 8, wherein said biomarker of aging is a production of cancer cells. 10. The method of Claim 1, wherein said changes in said gene expression level, levels of RNA, protein, or protein activity levels related to one or more biomarkers of aging occur in 6 weeks or less. 11. The method of Claim 10, wherein said changes in said gene expression levels, levels of RNA, protein, or protein activity levels related to one or more biomarkers of aging occur in four weeks or less. 12. The method of Claim 11, wherein said changes in said gene expression levels, levels of RNA, protein, or protein activity levels related to one or more biomarkers of aging occur in two weeks or less. 13. The method of Claim 12, wherein said changes in said gene expression levels, levels of RNA, protein, or protein activity levels related to one or more biomarkers of aging occur in about two days or less. 14. A method according to claim 1 wherein changes in gene expression are evaluated using a gene chip. 15. The method of Claim 14, wherein the gene chip contains genes for stress proteins. 16. The method of Claim 14, wherein the gene chip contains genes associated with inflammation response. 17. The method of Claim 14, wherein the gene chip contains genes associated with apoptosis. 19. The method of claim 1, wherein said biological sample is a test animal. 20. The method of Claim 19 additionally comprising determining changes in said levels in a reference animal having identifying characteristics of a long-term calorie-restricted animal wherein the reference animal has been on a calorie restricted diet for less than about 6 weeks and wherein said changes are used in said identifying said intervention as one that mimics the effects of calorie restriction. 21. The method of Claim 20, wherein the reference animal has been on a calorie restricted diet for less than about 4 weeks. 22. The method of Claim 24, wherein the reference animal has been on a calorie restricted diet for less than about 2 weeks. 23. The method of Claim 19, wherein said test animal is a mouse. 24. The method of Claim 19, wherein changes in gene expression are assessed in said test animal. 25. The method of claim 19 which further comprises: obtaining a gene expression profile from a calorie-restricted reference animal; comparing changes in gene expression for the test animal to the gene expression profile of the calorie-restricted reference animal; and identifying said intervention as one that mimics the effects of calorie restriction if the gene expression profile of the test animal is statistically similar to the gene expression profile of the calorie restricted animal. 26. The method of Claim 28, wherein the gene expression profile of the test animal is determined to be statistically similar to the gene expression of the calorie restricted animal by one-way ANOVA followed by Fisher's test (P< 0.05). 27. A system for identifying an intervention that mimics the effects of calorie restriction in a test animal comprising a test animal and a gene chip comprising genes known to have altered expression during calorie restriction. 28. The system of claim 27, wherein the gene chip comprises genes selected from the group consisting of genes for stress proteins, inflammation response, apoptosis, chaperone proteins, transcription factors, transmembrane channel proteins and transporter proteins.

Inventors: SPINDLER STEPHEN R, SPINDLER, STEPHEN, R.
Applicants: SPINDLER STEPHEN R, UNIV CALIFORNIA, SPINDLER, STEPHEN, R., THE REGENTS OF THE UNIVERSITY OF CALIFORNIA
Application year: 2000
Main classification: A61K49
IPC codes: A61K45, A61P3, A61P35, C12M1, C12N15, C12Q1, G01N33, G01N37