bluuebunny/crossref_metadata_2025 huggingface dataset:
Lymphocyte apoptosis after exhaustive and moderate exercise
Authors: Mooren F. C. , Blöming D. , Lechtermann A. , Lerch M. M. , Völker K.
Published: March 2015

Apoptosis or programmed cell death is a process of fundamental importance for regulation of the immune response. Several reasons suggest that apoptosis is involved in exercise-induced alterations of the immune system such as postexercise lymphocytopenia. Healthy volunteers performed two treadmill exercise tests; the first was performed at 80% maximal oxygen uptake until exhaustion (exhaustive exercise) and the second 2 wk later at 60% maximal oxygen uptake with the identical running time (moderate exercise). Blood samples were taken before, immediately after, and 1 h after the test. Lymphocytes were analyzed for apoptotic and necrotic cells by using FITC-labeled annexin V-antibodies and nuclear propidium iodide uptake, respectively. In addition, apoptotic/necrotic cells were measured after a 24-h incubation of lymphocytes in the presence of camptothecin or phytohemagglutinin. Finally, plasma membrane expression of CD95-receptor and CD95-receptor ligand was investigated. Immediately after the exhaustive exercise, the percentage of apoptotic cells increased significantly, whereas it remained unchanged after the moderate exercise. Similar results were obtained after 24-h incubation of lymphocytes in medium alone or in the presence of camptothecin, but not with phytohemagglutinin. We found an upregulation of CD95-receptor expression after both exercise tests. However, only after exhaustive exercise a characteristic shift in CD95 expression profile toward cells with a high receptor density was observed. Expression of the CD95-receptor ligand remained unchanged after both exhaustive and moderate exercise. These results suggest that apoptosis may contribute to the regulation of the immune response after exhaustive exercise. Whether this mechanism can be regarded either as beneficial, i.e., deletion of autoreactive cells, or harmful, i.e., suppression of the immune response, awaits further investigations.
Enhanced plasma IL-6 and IL-1ra responses to repeated vs. single bouts of prolonged cycling in elite athletes
Authors: Ronsen Ola , Lea Tor , Bahr Roald , Pedersen Bente Klarlund
Published: March 2015

The impact of repeated bouts of exercise on plasma levels of interleukin (IL)-6 and IL-1 receptor antagonist (IL-1ra) was examined. Nine well-trained men participated in four different 24-h trials: Long [two bouts of exercise, at 0800–0915 and afternoon exercise (Ex-A), separated by 6 h]; Short (two bouts, at 1100–1215 and Ex-A, separated by 3 h); One (single bout performed at the same Ex-A as second bout in prior trials); and Rest (no exercise). All exercise bouts were performed on a cycle ergometer at 75% of maximal O2uptake and lasted 75 min. Peak IL-6 observed at the end of Ex-A was significantly higher in Short (8.8 ± 1.3 pg/ml) than One (5.2 ± 0.7 pg/ml) but not compared with Long (5.9 ± 1.2 pg/ml). Peak IL-1ra observed 1 h postexercise was significantly higher in Short (1,774 ± 373 pg/ml) than One (302 ± 53 pg/ml) but not compared with Long (1,276 ± 451 pg/ml). We conclude that, when a second bout of endurance exercise is performed after only 3 h of recovery, IL-6 and IL-1ra responses are elevated. This may be linked to muscle glycogen depletion.
Invited Review: Autocrine/paracrine IGF-I and skeletal muscle adaptation
Authors: Adams Gregory R.
Published: March 2015

This brief review presents the basic premises suggesting that insulin-like growth factor I (IGF-I), functioning in an autocrine/paracrine mode, is an important mediator of skeletal muscle adaptation. Key intracellular signaling mechanisms associated with ligation of the primary IGF-I receptor are highlighted to illustrate the mechanisms by which IGF-I may promote muscle hypertrophy. In addition, a number of recent findings are presented that highlight the potential for interactions between IGF-I-related signaling pathways and intracellular signaling mechanisms activated by cytokines or hormonal systems.
Molecular Motors: Force and Movement Generated by Single Myosin II Molecules
Authors: Rüegg Caspar , Veigel Claudia , Molloy Justin E. , Schmitz Stephan , Sparrow John C. , Fink Rainer H. A.
Published: March 2015

Muscle myosin II is an ATP-driven, actin-based molecular motor. Recent developments in optical tweezers technology have made it possible to study movement and force production on the single-molecule level and to find out how different myosin isoforms may have adapted to their specific physiological roles.
Cerebrospinal Fluid Transport: a Lymphatic Perspective
Authors: Johnston M. , Papaiconomou C.
Published: March 2015

The textbook view that projections of the arachnoid membrane into the cranial venous sinuses represent the primary cerebrospinal fluid (CSF) absorption sites seems incompatible with many clinical and experimental observations. On balance, there is more quantitative evidence suggesting a function for extracranial lymphatic vessels than exists to support a role for arachnoid villi and granulations in CSF transport.
Indexes of NO Bioavailability in Human Blood
Authors: Lauer Thomas , Kleinbongard Petra , Kelm Malte
Published: March 2015

Disturbances of nitric oxide (NO) bioavailability may play a key role in vascular dysfunction and in the development of atherosclerotic lesions. Thus assessment of a reduced NO bioavailability in human circulation is of particular interest. Here we summarize potential biomarkers of NO availability in human blood and critically discuss their respective significance and application fields.
CFTR and Bicarbonate Secretion to Epithelial Cells
Authors: Hug Martin J. , Tamada Tsutomu , Bridges Robert J.
Published: March 2015

Defective HCO3– and fluid secretion are hallmarks of the pathophysiology of the pancreas of cystic fibrosis patients. Recently, impaired HCO3– secretion has been shown in most tissues known to express the cystic fibrosis transmembrane conductance regulator (CFTR). New results suggest that CFTR plays an important role in the transcellular secretion of HCO3–.
Apical Entry Channels in Calcium-Transporting Epithelia
Authors: Peng Ji-Bin , Brown Edward M. , Hediger Matthias A.
Published: March 2015

The identification of the apical calcium channels CaT1 and ECaC revealed the key molecular mechanisms underlying apical calcium entry in calcium-transporting epithelia. These channels are regulated directly or indirectly by vitamin D and dietary calcium and undergo feedback control by intracellular calcium, suggesting their rate-limiting roles in transcellular calcium transport.
Found: Na+ and K+ Binding Sites of the Sodium Pump
Authors: Rakowski R. F. , Sagar S.
Published: March 2015

Homology modeling and valence mapping have been used to predict the location and structure of Na+ and K+ binding sites in the Na+-K+-ATPase on the basis of the known atomic resolution structure of SERCA. Additional sites are predicted that may be associated with intracellular access and extracellular egress pathways for Na+. The model predictions are in excellent agreement with previous structure-function and electrical studies.
Riding the Tides: K+ Concentration and Volume Regulation by Muscle Na+-K+-2Cl− Cotransport Activity
Authors: Gosmanov Aidar R. , Lindinger Michael I. , Thomason Donald B.
Published: March 2015

Until recently, the existence of a Na+-K+-2Cl− cotransporter (NKCC) in skeletal muscle was unclear. Recent evidence shows that the NKCC is strongly expressed and provides both K+ and water transport functions in resting and contracting skeletal muscle. The contribution of NKCC activity to K+ and volume regulation in skeletal muscle has potential consequences for muscle contractility and metabolism.
Cellular Redox: A Modulator of Intestinal Epithelial Cell Proliferation
Authors: Aw Tak Yee
Published: March 2015

Mucosal proliferation, together with differentiation and apoptosis, are a continuous homeostatic process in the intestinal epithelium. The glutathione/glutathione disulfide redox status plays a key role in intestinal growth control wherein a reduced redox potential maintains a proliferative state. An oxidative shift in this potential elicits growth arrest and cell transition to a differentiated or apoptotic phenotype.
Mitochondrial Regulation of Intracellular Ca2+ Signaling: More Than Just Simple Ca2+ Buffers
Authors: Parekh Anant B.
Published: March 2015

Mitochondrial Ca2+ uptake shapes the profile of intracellular Ca2+ signals, both spatially and temporally. In addition, such uptake controls the gating of Ca2+ release and store-operated Ca2+ entry channels, partitions cells into subcellular Ca2+ hotspots, and can result in the release of diffusible signals into the cytosol that subsequently regulate protein function.
Ghrelin: A Novel Player in the Gut-Brain Regulation of Growth Hormone and Energy Balance
Authors: St-Pierre David H. , Wang Lixin , Taché Yvette
Published: March 2015

Ghrelin is a newly discovered peptide hormone produced by the stomach that displays potent growth hormone-releasing activity and a stimulatory effect on food intake and digestive function while reducing energy expenditure. The isolation of ghrelin has led to new insights into how this gastric hormone links the endocrine control of nutritional homeostasis with growth hormone secretion and gastrointestinal motility through gut-brain interactions.
The Vanilloid Receptor Family of Calcium-Permeable Channels: Molecular Integrators of Microenvironmental Stimuli
Authors: O’Neil Roger G. , Brown Rachel C.
Published: March 2015

The TRPV subfamily of calcium-permeable channels is widely distributed in sensory and nonsensory cells from nematodes to mammals. These channels can be variably activated by a diverse range of stimuli (osmotic/mechanical stress, noxious chemicals and heat, endogenous mediators) that often converge on the same channel. Evidence is presented that TRPV channels function as novel “molecular integrators” of diverse microenvironmental stimuli.
QTL associated with blood pressure, heart rate, and heart weight in CBA/CaJ and BALB/cJ mice
Authors: Sugiyama Fumihiro , Churchill Gary A. , Li Renhua , Libby Laura J. M. , Carver Tonya , Yagami Ken-Ichi , John Simon W. M. , Paigen Beverly
Published: March 2015

To better understand the genetic basis of essential hypertension, we conducted a quantitative trait locus (QTL) analysis of a population of 207 (BALB/cJ × CBA/CaJ) F2male mice to identify genomic regions that regulate blood pressure, heart rate, and heart weight. We identified two loci, Bpq6 (blood pressure quantitative locus 6) on chromosome 15 (Chr 15; peak, 16 cM; 95% confidence interval, 0–25 cM) and Bpq7 on Chr 7 (peak, 42 cM; 95% confidence interval, 35–50 cM) that were significantly associated with blood pressure. We also identified two loci, Hrq1 (heart rate quantitative locus 1) and Hrq2, on D2Mit304 (peak, 72 cM; 95% confidence interval 60–80 cM) and D15Mit184 (peak, 25 cM; 95% confidence interval 20–35 cM), respectively, that were significantly associated with heart rate. A significant gene-gene interaction for heart rate was found between Hrq1 and D1Mit10 (peak, 57 cM; 95% confidence interval, 45–75 cM); the latter QTL was named Hrq3. We identified a significant locus for heart weight, Hwq1 (heart weight quantitative locus 1), at D14Mit67 (peak, 38 cM; 95% confidence interval, 20–43 cM). Identification of the genes for these QTL should lead to a better understanding of the causes of essential hypertension.
Neuron-specific expression of human angiotensinogen in brain causes increased salt appetite
Authors: Morimoto Satoshi , Cassell Martin D. , Sigmund Curt D.
Published: March 2015

The brain renin-angiotensin system (RAS) has an important role in the regulation of cardiovascular function. In the brain, angiotensinogen (AGT) is expressed mainly in astrocytes (glia) and in some neurons in regions controlling cardiovascular activities. Because of the inability to dissect the functional role of astrocyte- vs. neuron-derived AGT in vivo by pharmacological approaches, the exact role of neuron-derived AGT in the regulation of blood pressure (BP) and fluid and electrolyte balance remains unclear. Therefore, we generated a transgenic mouse model overexpressing human AGT under the control of a neuron-specific (synapsin I) promoter (SYN-hAGT). These mice exhibited high-level expression of human AGT mRNA in the brain, with lower expression in the kidney and heart. Human AGT was not detected in plasma, but in the brain it was expressed exclusively in neurons. Intracerebroventricular (30 ng) but not intravenous (500 ng) injection of purified human renin (hREN) caused a pressor response, which was prevented by intracerebroventricular preinjection of the angiotensin II type 1 receptor antagonist losartan, indicating an AT1receptor-dependent functional role of neuron-derived AGT in the regulation of BP in response to exogenous REN. Double transgenic mice expressing both the hREN gene and SYN-hAGT transgene exhibited normal BP and water intake but had an increased preference for salt. These data suggest that neuronal AGT may play an important role in regulating salt intake and salt appetite.
Gene expression changes during mouse skeletal myoblast differentiation revealed by transcriptional profiling
Authors: Moran Jennifer L. , Li Yizheng , Hill Andrew A. , Mounts William M. , Miller Christopher P.
Published: March 2015

Studies described here utilize high-density oligonucleotide arrays to characterize changes in global mRNA expression patterns during proliferation, cell cycle withdrawal, and terminal differentiation in mouse C2C12 myoblasts. Statistical analyses revealed 629 sequences differentially regulated between proliferating and differentiating myoblasts. These genes were clustered using self-organizing maps to identify sets of coregulated genes and were assigned to functional categories that were analyzed for distribution across expression clusters. Clusters were identified with statistically significant enrichment of functional categories including muscle contraction, cell adhesion, extracellular matrix function, cellular metabolism, mitochondrial transport, DNA replication, cell cycle control, mRNA transcription, and unexpectedly, immune regulation. In addition, functional category enrichment data can be used to predict gene function for numerous differentially regulated expressed sequence tags. The results provide new insight into how genes involved in these cellular processes may play a role in skeletal muscle growth and differentiation.
Functional mapping for quantitative trait loci governing growth rates: a parametric model
Authors: Wu Rongling , Ma Chang-Xing , Zhao Wei , Casella George
Published: March 2015

Are there-specific quantitative trait loci (QTL) governing growth rates in biology? This is emerging as an exciting but challenging question for contemporary developmental biology, evolutionary biology, and plant and animal breeding. In this article, we present a new statistical model for mapping QTL underlying age-specific growth rates. This model is based on the mechanistic relationship between growth rates and ages established by a variety of mathematical functions. A maximum likelihood approach, implemented with the EM algorithm, is developed to provide the estimates of QTL position, growth parameters characterized by QTL effects, and residual variances and covariances. Based on our model, a number of biologically important hypotheses can be formulated concerning the genetic basis of growth. We use forest trees as an example to demonstrate the power of our model, in which a QTL for stem growth diameter growth rates is successfully mapped to a linkage group constructed from polymorphic markers. The implications of the new model are discussed.
Proteinuria and glomerulosclerosis in the Sabra genetic rat model of salt susceptibility
Authors: Yagil Chana , Sapojnikov Marina , Katni Gurion , Ilan Zvi , Zangen Sarah Weksler , Rosenmann Eliezer , Yagil Yoram
Published: March 2015

In search of an experimental model that would simulate the association between proteinuria and salt sensitivity in humans, we studied protein excretion in the Sabra rat model of salt susceptibility. Monthly measurements of urinary protein excretion in animals fed standard rat chow revealed that normotensive salt-sensitive SBH/y developed proteinuria that averaged 65 ± 7 mg/day ( n = 10) at 9 mo, whereas proteinuria in normotensive salt-resistant SBN/y was 39 ± 4 mg/day ( n = 10) ( P < 0.01). Histopathological evaluation revealed focal and segmental glomerulosclerosis (FSGS) lesions grade 2 in SBH/y and normal histology in SBN/y. To amplify the differences between the strains, uninephrectomy was performed. At 9 mo, proteinuria in SBH/y with one kidney (SBH/y-1K) was 195 ± 12 mg/day ( n = 10) and in SBN/y was 128 ± 10 mg/day ( n = 10) ( P < 0.001); histopathology revealed FSGS grade 3 in SBH/y-1K and grade 1–2 in SBN/y-1K. To determine the effect of salt loading, animals were provided with 8% NaCl in chow, causing hypertension in SBH/y but not in SBN/y. Proteinuria markedly increased in both SBH/y with two kidneys (SBH/y-2K) and SBH/y-1K, but not in SBN/y; histopathology revealed FSGS grade 1–2 in SBH/y-2K, grade 2 in SBH/y-1K, no lesions in SBN/y-2K, and grade 0–1 in SBN/y-1K. We concluded that the SBH/y strain is more susceptible to develop proteinuria and glomerulosclerosis than SBN/y. In search for the genetic basis of this phenomenon, we investigated the role of candidate proteinuric gene loci. Consomic strains were constructed by introgressing chromosome 1 (which harbors the rf-1 and rf-2 proteinuric loci) or chromosome 17 (which harbors rf-5) from SBH/y onto the SBN/y genomic background. The resulting consomic strains developed marked proteinuria that was severalfold higher than in SBN/y-1K; histopathological evaluation, however, revealed FSGS lesions grade 1–2, similar to those found in SBN/y-1K and less severe than in SBH/y-1K. These results suggest a functional role of gene systems located on chromosomes 1 and 17 in inducing proteinuria in the salt-susceptible Sabra rat strain. These genetic loci do not appear to harbor major genes for glomerulosclerosis.
Pleiotropy of quantitative trait loci for organ weights and limb bone lengths in mice
Authors: Leamy Larry J. , Pomp Daniel , Eisen E. J. , Cheverud James M.
Published: March 2015

We investigated the genetic basis of several limb bone lengths and weights of organs in mice produced from a cross of the F1between CAST/Ei (wild strain) and M16i (selected for rapid growth rate) back to M16i. From previous correlation studies, we hypothesized that quantitative trait loci (QTLs) would exhibit greater pleiotropy within than between the limb length and organ weight character sets. Using interval mapping procedures and significance testing at the chromosome-wise level, we discovered 14 putative QTLs affecting weight of the liver, spleen, heart, and/or kidney, 9 of which affected more than one organ; and 12 QTLs for limb lengths, all of which affected the length of two or more of the limb bones in these mice. As was hypothesized, most QTLs affected either organ weights or limb lengths independently of each other, although five QTLs were found that affected both sets of characters. The direction of the effect of these QTLs was almost always consistent within and between characters, with little evidence for antagonistic pleiotropy.
Gene expression profiling and functional proteomic analysis reveal perturbed kinase-mediated signaling in genetic stroke susceptibility
Authors: Fornage Myriam , Swank Michael W. , Boerwinkle Eric , Doris Peter A.
Published: March 2015

The stroke-prone spontaneously hypertensive rat (SHRSP) is a model of heritable hypertension-associated cerebrovascular injury. This study sought to compare SHRSP to the stroke-resistant SHR strain to identify genes and protein pathways whose expression and/or function was significantly altered between the strains prior to the onset of stroke. Cerebral cortex gene expression profiles from male SHRSPs and matched SHRs were examined by Affymetrix microarray analysis. mRNAs encoding the brain-derived neurotrophic factor receptor (TrkB) and multiple kinases of the MAPK/AKT signaling pathways, including JNK2, AKT2, and PI3K, were differentially expressed between SHRSP and SHR. Because these data suggest altered function in pathways involving MAP and AKT kinase activity, we performed Western blot using phosphorylation state-specific antibodies to characterize activity of MAP kinase and PI3K/AKT pathways. Changes in the levels of the phosphorylated forms of these kinases paralleled the changes in transcript levels observed between the strains. Two-dimensional gel electrophoresis and peptide fragment mass fingerprinting were used to identify altered protein substrates of these kinases. Protein profiling of kinase substrates further supported the notion of perturbed kinase-mediated signaling in SHRSP and identified adenylyl cyclase associated protein 2, TOAD-64, propionyl CoA carboxylase, APG-1, and valosin-containing protein as kinase targets whose phosphorylation state is altered between these strains. Altered gene and protein expression patterns in SHRSP are consistent with increased vulnerability of this strain to cerebrovascular injury.
Genetic programs and responses of neural stem/progenitor cells during demyelination: potential insights into repair mechanisms in multiple sclerosis
Authors: Imitola Jaime , Snyder Evan Y. , Khoury Samia J.
Published: March 2015

In recent years, it has become evident that the adult mammalian CNS contains a population of neural stem cells (NSCs) described as immature, undifferentiated, multipotent cells, that may be called upon for repair in neurodegenerative and demyelinating diseases. NSCs may give rise to oligodendrocyte progenitor cells (OPCs) and other myelinating cells. This article reviews recent progress in elucidating the genetic programs and dynamics of NSC and OPC proliferation, differentiation, and apoptosis, including the response to demyelination. Emerging knowledge of the molecules that may be involved in such responses may help in the design of future stem cell-based treatment of demyelinating diseases such as multiple sclerosis.
Alterations of gene expression in failing myocardium following left ventricular assist device support
Authors: Chen YingJie , Park Soon , Li Yunfang , Missov Emil , Hou Mingxiao , Han Xinqiang , Hall Jennifer L. , Miller Leslie W. , Bache Robert J.
Published: March 2015

Chronic unloading of the failing heart with a left ventricular assist device (LVAD) can decrease cardiac mass and myocyte size and has the potential to improve contractile function. To study the effect of chronic ventricular unloading on myocardial gene expression, a microarray (U133A, Affymetrix) profiling gene expression was compared before and after LVAD support in seven patients with idiopathic dilated cardiomyopathy and end-stage heart failure. On average, 1,374 ± 155 genes were reported as “increased” and 1,629 ± 45 as “decreased” after LVAD support. A total of 130 gene transcripts achieved the strict criteria for upregulation and 49 gene transcripts for downregulation after LVAD support. Upregulated genes included a large proportion of transcription factors, genes related to cell growth/apoptosis/DNA repair, cell structure proteins, metabolism, and cell signaling/communication. LVAD support resulted in downregulation of genes for a group of cytokines. To validate the array data, 10 altered genes were confirmed by real-time RT-PCR. Further study showed that the phosphoinositide-3-kinase-forkhead protein pathway and proteins related to nitric oxide synthesis, including eNOS and dimethylarginine dimethylaminohydrolase isoform 1 (DDAH1, an enzyme regulating endogenous nitric oxide synthase activity), were significantly increased during the cardiac remodeling process. Increased eNOS and DDAH1 expression after LVAD support may contribute to improved endothelial function of the failing hearts.
Evolutionary changes in heat-inducible gene expression in lines ofEscherichia coliadapted to high temperature
Authors: Riehle Michelle M. , Bennett Albert F. , Lenski Richard E. , Long Anthony D.
Published: March 2015

The involvement of heat-inducible genes, including the heat-shock genes, in the acute response to temperature stress is well established. However, their importance in genetic adaptation to long-term temperature stress is less clear. Here we use high-density arrays to examine changes in expression for 35 heat-inducible genes in three independent lines of Escherichia coli that evolved at high temperature (41.5°C) for 2,000 generations. These lines exhibited significant changes in heat-inducible gene expression relative to their ancestor, including parallel changes in fkpA, gapA, and hslT. As a group, the heat-inducible genes were significantly more likely than noncandidate genes to have evolved changes in expression. Genes encoding molecular chaperones and ATP-dependent proteases, key components of the cytoplasmic stress response, exhibit relatively little expression change; whereas genes with periplasmic functions exhibit significant expression changes suggesting a key role for the extracytoplasmic stress response in the adaptation to high temperature. Following acclimation at 41.5°C, two of the three lines exhibited significantly improved survival at 50°C, indicating changes in inducible thermotolerance. Thus evolution at high temperature led to significant changes at the molecular level in heat-inducible gene expression and at the organismal level in inducible thermotolerance and fitness.
Genome-wide linkage scan for exercise stroke volume and cardiac output in the HERITAGE Family Study
Authors: Rankinen Tuomo , An Ping , Pérusse Louis , Rice Treva , Chagnon Yvon C. , Gagnon Jacques , Leon Arthur S. , Skinner James S. , Wilmore Jack H. , Rao D. C. , Bouchard Claude
Published: March 2015

A genome-wide linkage scan was performed for genes affecting submaximal exercise cardiac output (Q) and stroke volume (SV) in the sedentary state and their responses to a standardized 20-wk endurance training program. A total of 509 polymorphic markers were used, and 328 pairs of siblings from 99 white nuclear families and 102 sibling pairs from 105 black family units were available. Q and SV were measured in relative steady state during exercise at 50 W (Q50 and SV50, respectively). Baseline phenotypes were adjusted for age, sex, and body surface area (BSA), and the training responses (post-training − baseline, Δ) were adjusted for age, sex, baseline BSA, and baseline value of the phenotype. Three analytical strategies were used: a multipoint variance components linkage analysis using all the family data, and regression-based single- and multipoint linkage analyses using pairs of siblings. In whites, baseline SV50 and ΔSV50 showed promising linkages ( P < 0.0023) with markers on chromosomes 14q31.1 and 10p11.2, respectively. Suggestive evidence of linkage (0.01 > P > 0.0023) for ΔSV50 and Δ Q50 was detected on chromosome 2q31.1 and for baseline SV50 and Q50 on chromosome 9q32-q33. In blacks, markers on 18q11.2 showed promising linkages with baseline Q50. Suggestive evidence of linkage was found in three regions for baseline SV50 (1p21.3, 3q13.3, 12q13.2) and one for baseline SV50 and Q50 (10p14). All these chromosomal regions include several potential candidate genes and therefore warrant further studies in the HERITAGE cohort and other studies.
Functional characterization of WT1 binding sites within the human vitamin D receptor gene promoter
Authors: LEE TAE HO , PELLETIER JERRY
Published: March 2015

The Wilms’ tumor suppressor gene, wt1, encodes a zinc finger transcription factor that can regulate gene expression. It plays an essential role in tumorigenesis, kidney differentiation, and urogenital development. To identify WT1 downstream targets, gene expression profiling was conducted using a cDNA array hybridization approach. We confirm herein that the human vitamin D receptor (VDR), a ligand-activated transcription factor, is a WT1 downstream target. Nuclear run on experiments demonstrated that the effect of WT1 on VDR expression is at the transcriptional level. Transient transfection assays, deletion mutagenesis, electrophoretic mobility shift assays, and chromatin immunoprecipitation assays suggest that, although WT1 is presented with a possibility of three binding sites within the VDR promoter, activation of the human VDR gene appears to occur through a single site. This site differs from a previously identified WT1-responsive site in the murine VDR promoter (Maurer U, Jehan F, Englert C, Hübinger G, Weidmann E, DeLucas HF, and Bergmann L. J Biol Chem 276: 3727–3732, 2001). We also show that the products of a Denys-Drash syndrome allele of wt1 inhibit WT1-mediated transactivation of the human VDR promoter. Our results indicate that the human VDR gene is a downstream target of WT1 and may be regulated differently than its murine counterpart.
Dietary fat interacts with QTLs controlling induction ofPgc-1α andUcp1during conversion of white to brown fat
Authors: Coulter Ann Allen , Bearden Christie M. , Liu Xiaotuan , Koza Robert A. , Kozak Leslie P.
Published: March 2015

To identify novel regulatory factors controlling induction of the brown adipocyte-specific mitochondrial uncoupling protein ( Ucp1) mRNA in the retroperitoneal white fat depot, we previously mapped quantitative trait loci (QTLs) that control this trait to chromosomes 2, 3, 8, and 19. Since the peroxisome proliferator activator receptor-γ coactivator-1α (PGC-1α) regulates Ucp1 and other genes of energy metabolism, we have evaluated whether the QTLs controlling Ucp1 mRNA levels also modulate Pgc-1α mRNA levels by analysis of backcross progeny from the A/J and C57BL/6J strains of mice. The results indicate that a locus on chromosome 3 orchestrates expression of Pgc-1α and Ucp1 in retroperitoneal fat of mice fed a low-fat diet; however, the effect of this locus on Pgc-1α is lost, and a significant correlation between Ucp1 and Pgc-1α is severely reduced in mice fed a high-fat diet. An additional QTL located on chromosome 5 has also been identified for the selective regulation of Ucp1 mRNA levels. Similar to the effects of a high-fat diet on the chromosome 3 QTL, linkage of the chromosome 5 QTL is also lost in mice on a high-fat diet. Thus dietary fat has a profound influence on PGC-1α-regulated pathways controlling energy metabolism in white fat. The allelic variation observed in the regulation of Ucp1 and Pgc-1α expression in brown adipocytes of white fat but not interscapular brown fat suggests that fundamentally different regulatory mechanisms exist to control the thermogenic capacities of these tissues.
Replacement of α1-Na-K-ATPase of Dahl rats by Milan rats lowers blood pressure but does not affect its activity
Authors: ORLOV SERGEI N. , DUTIL JULIE , HAMET PAVEL , DENG ALAN Y.
Published: March 2015

Both linkage and use of congenic strains have shown that a chromosome region near the gene for the Na-K-ATPase α1-subunit ( Atp1a1) contained a quantitative trait locus (QTL) for blood pressure (BP). Currently, two congenic strains, designated S.M5 and S.M6, were made by replacing a segment of the Dahl salt-sensitive SS/Jr (S) rat by the homologous region of the Milan normotensive rat (MNS). In S.M5, the gene for Atp1a1 is from the MNS strain; whereas in S.M6, Atp1a1 is from the S strain. The baseline activity of the α1-Na-K-ATPase and its stoichiometry were evaluated by an assay of ouabain-sensitive inwardly and outwardly directed 86Rb and 22Na fluxes in erythrocytes. The two congenic strains showed a similar BP, but both had a BP lower than that of S rats ( P < 0.0001). Neither the α1-Na-K-ATPase activity nor its stoichiometry was affected by the substitution of the Atp1a1 alleles of S by those of MNS. Thus the BP-lowering effects observed in S.M5 and S.M6 could not be attributed to the α1-Na-K-ATPase activity or its stoichiometry. Atp1a1 is not supported as a candidate to be a BP QTL.
Inducible and selective transgene expression in murine vascular endothelium
Authors: Teng Peter I. , Dichiara Maria R. , Kömüves László G. , Abe Keith , Quertermous Thomas , Topper James N.
Published: March 2015

We have developed a system utilizing the murine Tie2 promoter/enhancer coupled with the “tetracycline-on” regulatory elements to create a model that allows regulated and selective expression of a β-galactosidase (βGal) reporter transgene in the adult murine vascular endothelium. Two independent lines of viable and fertile mice were characterized, and they exhibit minimal βGal expression under basal conditions. In response to exogenous doxycycline (Dox), selective expression of βGal was demonstrated in the vascular endothelium of all tissues examined. En face analyses of the aorta and its principle branches indicate that the vast majority of lumenal endothelial cells express the transgene. Inducible βGal expression also extends to the endocardium and the microvasculature of all organs. There is no evidence of specific transgene expression in nonendothelial cell types. Induction of the βGal was effectively achieved after 3 days of oral Dox treatment and persisted for over 3 mo with continuous administration. This model can now be widely applied to study the role of specific genes in the phenotype of adult murine vasculature.
Sequence variation in hypoxia-inducible factor 1α (HIF1A): association with maximal oxygen consumption
Authors: Prior Steven J. , Hagberg James M. , Phares Dana A. , Brown Michael D. , Fairfull Liane , Ferrell Robert E. , Roth Stephen M.
Published: March 2015

Hypoxia-inducible factor 1 (HIF1) is a DNA transcription factor composed of two subunits, one of which is regulated by hypoxia (HIF1α, encoded by HIF1A). Genes regulated by HIF1 are involved in the processes of angiogenesis, erythropoiesis, and metabolism, making HIF1A a candidate gene in establishing maximal oxygen consumption (V˙o2 max) before and after aerobic exercise training. The purpose of the present study was to screen HIF1A for sequence variation and determine whether such variation is associated with V˙o2 maxbefore and after aerobic exercise training. A total of 233 Caucasian and African-American subjects were available for screening of HIF1A and determination of allele frequencies, with 155 of those subjects used to study V˙o2 maxin relation to identified variants. We measured V˙o2 maxbefore and after 24 wk of aerobic exercise training. Screening revealed several rare and common polymorphisms in HIF1A with race-specific allele frequencies. African Americans with AT or TT genotype at the A−2500T locus exhibited significantly lower baseline V˙o2 maxcompared with those of AA genotype (21.9 ± 0.99 vs. 25.1 ± 1.0, P = 0.03). An age by P582S (C/T) genotype interaction was observed in Caucasian subjects, such that those of CT or TT genotype exhibited significantly lower change in V˙o2 maxafter training than those of CC genotype when compared at ages 65 and 60 yr, but not at age 55 yr. No other significant differences were noted among genotype groups at the A−2500T, P582S, or T+140C sites. Based on these findings, we conclude that HIF1A sequence variation is associated with V˙o2 maxbefore and after aerobic exercise training in older humans.
Quantitative trait loci for insulin-like growth factor I, leptin, thyroxine, and corticosterone in genetically heterogeneous mice
Authors: Harper James M. , Galecki Andrzej T. , Burke David T. , Pinkosky Stephen L. , Miller Richard A.
Published: March 2015

Genotype information was collected at 87 loci in a group of 1,108 UM-HET3 mice bred as the progeny of [BALB/cJ × C57BL/6J]F1mothers and [C3H/HeJ × DBA/2J]F1fathers, for which thyroxine (T4), insulin-like growth factor I (IGF-I), and leptin levels had been measured at 4 and 15 mo of age. The data provided significant evidence for quantitative trait loci (QTL) modulating IGF-I levels on chromosomes 1, 3, 8, 10, and 17; for loci affecting T4on chromosomes 4, 15, and 17; and for leptin on chromosome 3. Fecal levels of corticosterone at 17 mo of age were influenced by a QTL on chromosome 1. Nine other gene/hormone associations reached a nominal P < 0.01, providing suggestive but not statistical evidence for additional QTL. QTL with an influence on a given hormone were in nearly all cases additive, with little or no evidence for epistasis. Of the 12 strongest QTL, 5 had effects that were age dependent, having more effect in 15-mo-old than in 4-mo-old mice in all but one case; the other QTL had effects that were apparently age-independent. These results show that the genetic controls over late-life hormone levels are complex and dependent on effects of genes that act both early and late in the life course.
Liver gene expression in rats in response to the peroxisome proliferator-activated receptor-α agonist ciprofibrate
Authors: Yadetie Fekadu , Laegreid Astrid , Bakke Ingunn , Kusnierczyk Waclaw , Komorowski Jan , Waldum Helge L. , Sandvik Arne K.
Published: March 2015

Fibrate class hypolipidemic drugs such as ciprofibrate activate the peroxisome proliferator-activated receptor-α (PPARα), which is involved in processes including lipid metabolism and hepatocyte proliferation in rodents. We examined the effects of ciprofibrate (50 mg/kg body wt per day for 60 days) on liver gene expression in rats using cDNA microarrays. The 60-day dosing period was chosen to elucidate both the metabolic and proliferative actions of this substance, while avoiding confounding effects from the hepatic carcinogenesis seen during more long-term stimulation. Ciprofibrate changed the expression of many genes including previously known PPARα agonist-responsive genes involved in processes such as lipid metabolism and inflammatory responses. In addition, many novel candidate genes involved in sugar metabolism, transcription, signal transduction, cell proliferation, and stress responses appeared to be differentially regulated in ciprofibrate-dosed rats. Ciprofibrate also resulted in significant increases in liver weight and hepatocyte proliferation. The cDNA microarray results were confirmed by Northern blot analysis for selected genes. This study thus identifies many genes that appear to be differentially regulated in ciprofibrate-dosed rats, and some of these are potential targets of PPARα. The functional diversity of these candidate genes suggests that most of them are likely to be differentially regulated as indirect consequence of the many processes affected by ciprofibrate in rodent liver. Although caution is advisable in the interpretation of genome-wide expression data, the genes identified in the present study provide candidates for further studies that may give new insight into the mechanisms of action of peroxisome proliferators.
Blood pressure QTLs identified by genome-wide linkage analysis and dependence on associated phenotypes
Authors: HARRAP STEPHEN B. , WONG ZILLA Y. H. , STEBBING MARGARET , LAMANTIA ANGELA , BAHLO MELANIE
Published: March 2015

Understanding genetic factors that contribute to population-wide variation in blood pressure is likely to benefit prevention and treatment of cardiovascular disease. The aim of the Victorian Family Heart Study is to identify genes for cardiovascular risk in 783 volunteer adult families recruited from the general population. In this preliminary study we sought to identify quantitative trait loci (QTLs) using a genome-wide linkage analysis in 274 adult sibling pairs of average age 24 yr selected without respect to blood pressure. We compared multipoint linkage results for carefully measured systolic (SBP) and diastolic (DBP) pressures before and after statistical adjustment for covariation with sex, oral contraception, age, height, and weight. The average BP was 123/67 (SD: 12/11) mmHg in males ( n = 283) and 114/64 (SD: 10/9) mmHg in females ( n = 265). Nonparametric Z-scores from multipoint GeneHunter II analysis were “suggestive” (3.1 or more) at four QTLs for SBP (chromosomes 1, 4, 16, and X) but at no QTLs for DBP. Most Z-scores were affected little by adjustment for covariates. However, the SBP QTL on chromosome 16 was obvious only for unadjusted pressures. This population-based quantitative trait analysis has identified more QTLs than any of the eight previous genome-wide scans for blood pressure. Considerable discrepancies between different studies may reflect the presence of false-positive results or real biological differences between populations.
Elucidating the molecular mechanism of cardiac remodeling using a comparative genomic approach
Authors: Mirotsou Maria , Watanabe Coran M.H. , Schultz Peter G. , Pratt Richard E. , Dzau Victor J.
Published: March 2015

It is proposed that analysis of global gene expression would provide an understanding of the molecular mechanisms of cardiac remodeling. However, previous studies have only provided “snapshots” of differential gene expression. Furthermore, the differences in gene expression between regions of the heart that can result in sampling variability have not been characterized. In this study, we employed the Affymetrix GeneChip technology to evaluate the patterns of expression in two different in vivo models of cardiac remodeling and in two different regions (left ventricle free wall and intraventricular septum) of the heart. Mice underwent transverse aortic constriction (TAC), myocardial infarction (MI), or sham operation, and RNA from the left ventricle free wall and the septum was isolated 1 wk later. Histological analysis showed profound myocyte hypertrophy and fibrosis in both the septum and the left ventricle free wall of the TAC model, whereas, in the MI model, only the left ventricle exhibited hypertrophy. These differences were also reflected in the expression analysis. In conclusion, our analysis shows that regional differences in gene expression exist in the heart. Moreover, common pathways that are coregulated in both models exist, and these might be central to the hypertrophic phenotype regardless of the initial hypertrophic stimuli.
Exon truncation by alternative splicing of murine ICAM-1
Authors: Mizgerd Joseph P. , Spieker Matt R. , Lupa Michal M.
Published: March 2015

The murine gene for intercellular adhesion molecule-1 (ICAM-1) encodes multiple products, arising from alternative splicing. Full-length ICAM-1 contains five extracellular Ig domains, each encoded by a separate exon. Alternatively spliced forms have Ig domains 2, 3, and/or 4 excised as a result of exon skipping. We report here a novel splice variant of murine ICAM-1, resulting from exon truncation rather than exon skipping and affecting Ig domain 5. A 5′ splice donor site within exon 6 generates transcripts missing 69 nucleic acids from the 3′ terminus of the exon. This in-frame exon truncation is predicted to replace 24 amino acids within Ig domain 5 with a single aspartic acid residue, yielding a structure other than an Ig domain immediately external to the membrane. Expression of this alternatively spliced form is induced in mouse lungs, spleen, and kidneys during LPS-induced pulmonary inflammation. Since the affected region is critical for ICAM-1 presentation, dimerization, and solubilization, this alternative splice variant may have unique physiological functions.
Super models
Authors: Barr Maureen M.
Published: March 2015

Model organisms have been used over a century to understand basic, conserved biological processes. The study of these experimental systems began with genetics and development, moved into molecular and cellular biology, and most recently propelled into functional genomics and proteomics. The goal of this review is simple: to discuss the place of model organisms in “The Age of the Ome”: the genome, the transcriptome, and the proteome. This review will address the following questions. What exactly is a model organism? What characteristics make an excellent model system? Using the yeast Saccharomyces cerevisiae and the nematode Caenorhabditis elegans as examples, this review will discuss these issues with the aim of demonstrating how model organisms remain indispensable scientific tools for understanding complex biological pathways and human disease.
Large-scale, high-throughput screening for coagulation and hematologic phenotypes in mice*
Authors: Peters Luanne L. , Cheever Eleanor M. , Ellis Heather R. , Magnani Phyllis A. , Svenson Karen L. , Von Smith Randy , Bogue Molly A.
Published: March 2015

The Mouse Phenome Project is an international effort to systematically gather phenotypic data for a defined set of inbred mouse strains. For such large-scale projects the development of high-throughput screening protocols that allow multiple tests to be performed on a single mouse is essential. Here we report hematologic and coagulation data for more than 30 inbred strains. Complete blood counts were performed using an Advia 120 analyzer. For coagulation testing, we successfully adapted the Dade Behring BCS automated coagulation analyzer for use in mice by lowering sample and reagent volume requirements. Seven automated assay procedures were developed. Small sample volume requirements make it possible to perform multiple tests on a single animal without euthanasia, while reductions in reagent volume requirements reduce costs. The data show that considerable variation in many basic hematological and coagulation parameters exists among the inbred strains. These data, freely available on the World Wide Web, allow investigators to knowledgeably select the most appropriate strain(s) to meet their individual study designs and goals.
Transcriptional profiling of the transition from normal intestinal epithelia to adenomas and carcinomas in the APCMin/+ mouse
Authors: Paoni Nicholas F. , Feldman Matthew W. , Gutierrez Linda S. , Ploplis Victoria A. , Castellino Francis J.
Published: March 2015

Mutations in the adenomatous polyposis coli (APC) gene that result in excessive β-catenin-induced cell signaling are implicated in the risk of colon cancer. Although the mechanism of APC-mediated tumorigenesis is known, the pathways that translate β-catenin signaling into tumor growth in vivo are undefined. To address this, gene expression profiles of normal intestinal epithelial cells were compared with those from adenomas and carcinomas from APCMin/+ mice, a model of APC-related colorectal cancer. The gene expression profiles of adenomas and carcinomas were very similar, which is consistent with the theory that carcinomas progress from adenomas in this model system. Tumors had altered transcript abundance for members of several pathways that influence cell growth and proliferation including growth factors/receptors, molecules involved in apoptosis, and protein processing and catabolism enzymes. Comparison of gene expression between adenomas and carcinomas revealed nine differentially expressed transcripts. These included members of three growth-regulating pathways, and the results are consistent with the increased growth potential of carcinomas. SRY-box containing gene 17 (Sox 17), a negative regulator of β-catenin signaling, and calbindin-D9K, a factor that enhances calcium transport, were more highly expressed in adenomas than carcinomas (∼4-fold and 15- to 22-fold, respectively). Transcript abundance for insulin-like growth factor binding protein 5, which mediates insulin-like growth factor function, was 2.6-fold greater in carcinomas. Because the changes in gene expression observed in this study are directly associated with a deficiency in APC, the data provide new insights into how loss of this important tumor suppressor translates into benign and malignant tumor growth.