bluuebunny/crossref_metadata_2025_split huggingface dataset:
Secretion of mutant leucine‐specific binding proteins with internal deletions in Escherichia coli
Authors: Adams Mark D. , Oxender Dale L. 
Published: May 2005

AbstractThe leucine‐specific binding protein, encoded by the livK gene, is located in the periplasm of E. coli. The present study is an attempt to identify intragenic regions that determine the efficiency of its secretion into the periplasm. C‐terminal deletions or fusions of the livK gene to trpA (encoding the α subunit of tryptophan synthetase) were secreted with little loss of efficiency [1]. A series of deletions was constructed at the unique Sphl site within livK, near the 5' end of the region coding for the mature protein. Between 16 and 113 amino acids were deleted in the amino‐terminal one‐third of the protein. A few of these deletions were located within a few amino acids of the signal sequence processing site. Deletions extending within thirteen residues of the processing site were processed and secreted more slowly than normal. Secondary structure predictions suggested that the α‐helical core region of the signal sequence extends into the mature protein in the case of the slow processing mutants, perhaps interfering with the recognition site for leader peptidase or other secretory components. These results suggest that the conformation around the signal processing site may be a critical factor in determining the efficiency of secretion. During the course of this study, it was found that the difference in molecular weight between precursor and mature forms of some binding protein mutants, as judged by SDS‐PAGE, was much greater than could be accounted for by processing of the signal sequence. This anomalous mobility on gels, however, could be eliminated by performing SDS‐PAGE in the presence of 6 M urea.
Regulation of expression of the growth‐state‐related genes 2F1 and 2A9 during entry of quiescent smooth muscle cells into the cell cycle
Authors: Kindy Mark S. , Brown Karen E. , Sonenshein Gail E. 
Published: May 2005

AbstractVascular smooth muscle cells (SMCs) play a key role in the development of major arteries. Furthermore, abnormal growth of vascular smooth muscle cells has been implicated in the progression of major diseases of the cardiovascular system. Here, we report detection in primary cultures of bovine vascular smooth muscle cells of mRNA for two growth‐state‐related genes, 2F1 and 2A9, which code for a mitochondrial ADP/ATP carrier and calcyclin, respectively, and on the characterization of their cell cycle expression. Cultures of exponentially growing smooth muscle cells were made quiescent by serum deprivation. Upon readdition of serum, cells entered the cell cycle synchronously; DNA synthesis began 12 h post‐serum addition. Levels of 2F1 and 2A9 RNA were low in quiescent cells and increased between 2 and 4 h post‐serum addition. No changes in the rates of transcription of the 2F1 or 2A9 genes were detected by nuclear run‐off assays during the time course. Thus the regulation of changes in expression of 2F1 and 2A9 in early G1 is mediated post‐transcriptionally.
Glucocorticoid regulation of rat liver urate oxidase
Authors: Raab Linda Symons , Decker Glenn L. , Jonas Adam J. , Kaetzel Marcia A. , Dedman John R. 
Published: May 2005

AbstractUrate oxidase, an enzyme involved in purine catabolism, comprises the crystalline core of rat liver peroxisomes. An affinity‐purified monospecific antibody was developed to study the expression of urate oxidase protein levels. Immunoreactive urate oxidase was not detectable in prenatal liver; however, it is present at low levels after birth until approximately day 15 (postnatal age); expression sharply increases just prior to day 20, after which the enzyme is maintained at adult levels. This pattern of expression was similar to that of another peroxisomal enzyme, catalase; these developmental increases reflect the increase in peroxisomal number. Administration of exogenous glucocorticoid hormone to 10‐day‐old rats resulted in a precocious rise (2.5‐fold) in urate oxidase levels. Adrenalectomy at 10 days of age did not cause decreased levels in the fourth week of life. In adult animals, while exogenous glucocorticoid administration did not influence urate oxidase levels, adrenalectomy at 60 days of age decreased urate oxidase levels to 40 percent of control levels. Subsequent administration of exogenous glucocorticoid hormone restored urate oxidase to normal levels. Parallel studies of catalase levels indicate that this glucocorticoid‐sensitive response is not generalized for all peroxisomal proteins. Our results suggest that peroxisomes proliferate during early postnatal development, but after this process is complete, the biogenesis of individual peroxisomal proteins may be independently regulated.
Co‐regulation of heme oxygenase and erythropoietin genes
Authors: Abraham N. G. , Levere R. D. , Lin J. H.‐C. , Beru N. , Hermine O. , Goldwasser E. 
Published: May 2005

AbstractThe mechanism responsible for the accumulation of heme oxygenase and erythropoietin (epo) transcripts due to cobalt chloride (CoCl2) administration was investigated in rat kidney using a rat heme oxygenase and mouse epo probes. We found an increase of heme oxygenase transcripts in kidney in response to CoCl2. Quantitative evaluation of the heme oxygenase mRNA changes, by scanning densitometry, indicated that the levels of mRNA encoding heme oxygenase were increased by about fiftyfold in rat kidney after administration of CoCl2. That the increase in heme oxygenase mRNA levels resulted from enhanced transcription of the heme oxygenase gene was confirmed by nuclear runoff using isolated rat kidney nuclei after CoCl2 administration. Transcription of the heme oxygenase gene is greatly increased in rat kidney within 1 hr of administration of CoCl2 as evidenced from the levels of 32P‐UTP incorporation into the specific transcript. Time course studies showed that stimulation of transcription was increased about fortyfold 3 hr after CoCl2 administration. This stimulation is the most rapid transcriptional response to heavy metals yet described. In addition, Northern blot analysis demonstrated that epo mRNA was first detected 4 hr following CoCl2 administration and reached a maximum at 5 hr. On the other hand, PCR analysis indicated that epo mRNA was increased as early as 1 hr following CoCl2 administration. The fact that CoCl2 caused increased transcription of both the epo and heme oxygenase genes suggests that a common mechanism may be involved in the regulation of these two genes by the heavy metal ion.
Induction of interleukin‐1β production in human dermal fibroblasts by interleukin‐1α and tumor necrosis factor‐α. Involvement of protein kinase‐dependent and adenylate cyclase‐dependent regulatory pathways
Authors: Mauviel Alain , Temime Nathalie , Charron Dominique , Loyau Gérard , Pujol Jean‐Pierre 
Published: May 2005

AbstractIt has previously been demonstrated that interleukin‐1 (IL‐1) is expressed in a variety of fibroblast cell lines. In this study, we investigated the mechanisms involved in the regulation of IL‐1β production by cultured human dermal fibroblasts. We have shown that IL‐1β is constitutively expressed as a cell‐associated form, with no soluble form detectable in control cell or in stimulated cell supernatants. IL‐1α and tumor necrosis factor‐α (TNF‐α) exerted a dose‐depdent stimulation on the production of the cell‐associated IL‐1β, as estimated using a specific enzyme linked immunosorbent assay (ELISA). As expected, this effect was accompanied by a huge release of prostaglandin E2 (PGE2) and a transient rise in intracellular cyclic AMP. Furthermore, IL‐1β production was elevated to a lesser extent by the addition of increasing concentrations of the protein kinase C activator phorbol myristate acetate or by low concentration (0.001 μg/ml) of PGE2. In contrast, higher concentrations (0.1 and 1. μg/ml) of PGE2, as well as exogenous dibutyryl‐cyclic AMP, were clearly inhibitory. H7, an inhibitor of protein kinases also reduced the stimulatory effect of IL‐1α and TNF‐α. Together with the results obtained with phorbol myristate acetate, these data suggest that protein kinase C may play a role in the upregulation of IL‐1β expression in normal skin fibroblasts. The addition of indomethacin not only suppressed prostaglandin synthesis, but also dramatically reduced cyclic AMP formation, probably because the PGE2‐induced stimulation of adenylate cyclase was abolished. This resulted in a strong potentiation of the stimulatory effect of IL‐1α and TNF‐α, supporting the role of both the cyclooxygenase and adenylate cyclase pathways in the endogenous downregulation of IL‐1β induction by the two cytokines studied.
Release of basic fibroblast growth factor, an angiogenic factor devoid of secretory signal sequence: A trivial phenomenon or a novel secretion mechanism?
Authors: Mignatti Paolo , Rifkin Daniel B. 
Published: May 2005

AbstractBasic fibroblast growth factor (bFGF), a potent angiogenesis inducer, lacks a signal sequence. Therefore, it has been proposed that bFGF is primarily released from dead or damaged cells. Other proteins devoid of secretion signals, interleukin 1β (IL‐1β) and the muscle lectin L‐14, have been shown to be released via exocytosis, a novel secretion pathway independent of the “classic” endoplasmic reticulum‐Golgi route. In the light of these findings and of our own recent results, we discuss evidence that bFGF can be released from single, uninjured cells and mediate functions is an autocrine manner. As is the case for IL‐1β and L‐14, externalization of bFGF may occur via exocytosis, a pathway utilized during development and differentiation.
A metalloproteinase inhibitor as an inhibitor of neovascularization
Authors: Moses Marsha A. , Langer Robert 
Published: May 2005

AbstractMetalloproteinases and their endogenous inhibitors are key components of an enzyme system which is important in a number of fundamental biochemical and cellular processes. Our recent work has focused on the role of a particular metalloproteinase, collagenase, and the role of an endogenous inhibitor of this enzyme in the control of neovascularization. The proteolytic degradation of extracellular matrix components by capillary endothelial cells (EC) has been shown to be one of the key prerequisites of the angiogenic process. As part of a study of the effect(s) of the inhibition of collagenase on neovascularization, we have recently reported the purification, characterization and partial NH2‐terminal sequence of a cartilage‐derived inhibitor (CDI) of angiogenesis in vivo and in vitro. Evidence is presented which suggests that one means of controlling deregualted vascular growth characteristic of a number of “angiogenic diseases” may be at the level of the control of metalloproteinase activity.
Interleukin 4 inhibits murine osteoclast formation in vitro
Authors: Shioi Atsushi , Teitelbaum Steven L. , Ross F. Patrick , Welgus Howard G. , Suzuki Hidenori , Ohara Junichi , Lacey David L. 
Published: May 2005

AbstractInterleukin 4 (IL‐4) is a product of activated T cells and mast cells with effects on immunologic and hematopoietic processes. We now report that IL‐4 inhibits the formation of osteoclasts from murine bone marrow cells cocultured with stromal cells. Numerous (3,000–4,000 cells/2 cm2) tartrate‐resistant acid‐phosphatase‐positive multinucleated cells with the capacity to generate cAMP in response to salmon calcitonin (ED50 = 10−10 M) developed within 10–12 days of culture. IL‐4 (ID50 = 10 U/ml) inhibited osteoclast generation in doses similar to those that induce proliferation of IL‐4‐responsive T cells. Additionally, the rat antimurine IL‐4 monoclonal antibody 11B11 antagonizes the IL‐4‐inhibitory effect on osteoclast formation. These results suggest that IL‐4 impedes agonist‐induced in vitro bone resorption by inhibiting osteoclastogenesis.
Protein/DNA interactions involving ATF/AP1‐, CCAAT‐, and HiNF‐D‐related factors in the human H3‐ST519 histone promoter: Cross‐competition with transcription regulatory sites in cell cycle controlled H4 and H1 histone genes
Authors: van Wijnen André J. , Lian Jane B. , Stein Janet L. , Stein Gary S. 
Published: May 2005

AbstractProtein/DNA interactions of the H3‐ST519 histone gene promoter were analyzed in vitro. Using several assays for sequence specificity, we established binding sites for ATF/AP1‐, CCAAT‐, and HiNF‐D related DNA binding proteins. These binding sites correlate with two genomic protein/DNA interaction domains previously established for this gene. We show that each of these protein/DNA interactions has a counterpart in other histone genes: H3‐ST519 and H4‐F0108 histone genes interact with ATF‐ and HiNF‐D related binding activities, whereas H3‐ST519 and H1‐FNC16 histone genes interact with the same CCAAT‐box binding activity. These factors may function in regulatory coupling of the expression of different histone gene classes. We discuss these results within the context of established and putative protein/DNA interaction sites in mammalian histone genes. This model suggests that heterogeneous permutations of protein/DNA interaction elements, which involve both general and cell cycle regulated DNA binding proteins, may govern the cellular competency to express and coordinately control multiple distinct histone genes.
The endocytic hyaluronan receptor in rat liver sinusoidal endothelial cells is Ca+2‐independent and distinct from a Ca+2‐dependent hyaluronan binding activity
Authors: Yannariello‐Brown Judith , McGary Carl T. , Weigel Paul H. 
Published: May 2005

AbstractIsolated and cultured rat liver sinusoidal endothelial cells (LECs) retain the ability to specifically bind 125I‐hyaluronan (HA) internalize it using a coated pit pathway [Biochem J, 257:875–884, 1989]. Here we have determined the effect of Ca+2 on the binding and endocytosis of HA by LECs. 125I‐HA binding to intact LECs at 4°C occurred both in the absence (10 mM EGTA) or the presence of physiologic concentrations of Ca+2 (1.8 mM). However, the specific binding of 125I‐HA to LECs increased linearly with increasing Ca+2 concentrations. After permeabilization with the nonionic detergent digitonin, the Ca+2‐independent HA binding activity increased ∼743%, while the Ca+2‐dependent binding activity was enhanced only ∼46%. Therefore, the Ca+2‐dependent HA binding activity appears not to be intracellular, whereas the Ca+2‐independent HA receptor is found both inside LECs and on the cell surface. When LECs were allowed to endocytose 125I‐HA at 37°C in 10 mM EGT A or in 1.8 mM Ca+2, no differences were seen in the extent or rate of endocytosis. When LECs were allowed to endocytose 125I‐HA in the presence of 10mM Ca125, the amount of cell‐associated radiocctivity increased appoximately 20–50‐fold. However, this additional cell‐associated 125I‐HA was not sensitive to hyperosmolarity and was removed by washing the cells in 10mM EGTA at 4°C. Therefore, the Ca+2‐dependent cell‐associated 125I‐HA had accumulated on the cell surface and had not been internalized. From these studies we conclude the LECs have at least two trypes of specfic HA binding sites. One, the previously characterized HA receptor, is Ca+2‐indepoendent, localized both extracellularly and intracellular, and medicates he efficient binding and subsequent endocytosis of HA using a coated pit pathway. The other newly recognized HA binding activity is Ca+2‐dependent, localized wxtracellularly, and is not responsible for the endocytosis of HA in rat LECs.
Characterization of the human myeloid cell nuclear differentiation antigen: Relationship to interferon‐inducible proteins
Authors: Burrus G. R. , Briggs J. A. , Briggs R. C. 
Published: May 2005

AbstractThe human myeloid cell nuclear differentiation antigen (MNDA) is expressed specifically in cells of the granulocyte/monocyte lineage. The MNDA has been isolated by using a monoclonal antibody affinity matrix and reversed‐phase high performance liquid chromatography. Its NH2‐terminal sequence has been obtained, as well as additional sequence information derived from peptides produced by cyanogen bromide and SV8 protease cleavages. Meaningful similarities were observed in extended regions between the MNDA and the reported β interferon‐inducible proteins, 202 and 204, from Ehrlich ascites mouse tumor cells. An amphipathic, basic α‐helical region, showing no similarity to the 202 and 204 proteins, exhibited close similarity to a region in the interferon response factor‐2, a protein which binds the interferon stimulated response element. The relatively high number of S(T)PXX motifs present in the partial amino acid sequence of the MNDA, described herein, suggests that the MNDA binds DNA and is a transcription factor.
Defective insulin secretion in niddm: Integral part of a multiplier hypothesis
Authors: Robertson R. Paul 
Published: May 2005

AbstractNon‐insulin dependent diabetes mellitus (NIDDM) is characterized by a specific defect in glucose recognition by the pancreatic islet beta cell. This is in clear distinction to patients with insulin dependent diabetes mellitus (IDDM) who undergo pancreatic islet beta cell death and no longer have the ability to synthesize, store, and release insulin. Defective glucose‐induced first phase insulin responses in patients with NIDDM can be partially restored by exogenous insulin treatment and by other pharmacologic therapy. These observations provide strength for the theory of glucose desensitization of the pancreatic beta cell as an important secondary defect in the pathogenesis of abnormal insulin secretion in NIDDM. However, even though defective insulin secretion is an essential part of the pathogenesis of NIDDM, in itself it is not sufficient. A multiplicative effect is required involving interaction between tissue resistance to insulin action and defective insulin secretion whose product is the syndrome of NIDDM.
Protein kinase C involved in zymosan‐induced release of arachidonic acid and superoxide but not in calcium ionophore‐elicited arachidonic acid release or formation of prostaglandin E2 from added arachidonate
Authors: Duyster Justus , Schulze‐Specking Agnes , Fitzke Edith , Dieter Peter 
Published: May 2005

AbstractZymosan and phorbol ester induced in liver macrophages the release of arachidonic acid, prostaglandin E2, and superoxide; the calcium ionophore A 23187 elicited a release of arachidonic acid and prostaglandin E2 but not of superoxide, and exogenously added arachidonic acid led to the formation of prostaglandin E2 only. The zymosan‐ and phorbol‐ester‐induced release of arachidonic acid, prostaglandin E2, and superoxide was dose‐dependently inhibited by staurosporine and K252a, two inhibitors of protein kinase C, and by pretreatment of the cells with phorbol ester which desensitized protein kinase C. The release of arachidonic acid or prostaglandin E2 following the addition of A 23187 or arachidonic acid was not affected by these treatments. Zymosan and phorbol ester but not A 23187 or arachidonic acid induced a translocation of protein kinase C from the cytosol to membranes in intact cells. These results demonstrate an involvement of protein kinase C in the zymosan‐ and phorbol‐ester‐induced release of arachidonic acid, prostaglandin E2, and superoxide; the release of arachidonic acid and prostaglandin E2 elicited by A 23187 and the formation of prostaglandin E2 from exogenously added arachidonic acid, however, is independent of an activation of protein kinase C.
1α,25‐Dihydroxyvitamin D3 modulation in lipid metabolism in established bone marrow‐derived stromal cells, MC3T3‐G2/PA6
Authors: Shionome Manabu , Shinki Toshimasa , Takahashi Naoyuki , Hasegawa Kohji , Suda Tatsuo 
Published: May 2005

AbstractMC3T3‐G2/PA6 (PA6) cells established from newborn mouse calvaria are preadipocytic stromal cells, which differentiate into adipocytes in response to glucocorticoids. We examined the effects of 1α,25‐dihydroxyvitamin D3[1α,25(OH)2D3] on adipogenesis in PA6 cells were cultured with 10−8 M dexamethasone, adipocytes containing oil red O‐positive droplets first appeared on day 7 (3 days after confluence was attained) and the maximal synthesis of neutral lipids occurred on day 12. Simultaneous addition of 1α,25(OH)2D3 at 10−9 M completely blocked this dexamethasone‐induced neutral lipid synthesis throughout the 14‐day culture period. Dose‐response studies of vitamin D3 derivatives showed that 1α,25(OH)2D3 was the most potent in inhibiting neutral lipid synthesis in PA6 cells, followed by 1α‐hydroxyvitamin D3, 25‐hydroxyvitamin D3 and 24R,25‐dihydroxyvitamin D3, in that order. Dexamethasone greatly enhanced incorporation of [14C]‐acetic acid into triacylglycerol in PA6 cells. The incorporation was markedly inhibited by the addition of 10−9 M 1α,25(OH)2D3 Instead, 1α,25(QH)2D3 greatly increased incorporation of [14C]‐acetic acid into phospholipids, such as phosphatidylcholine and phosphatidylethanolamine, irrespective of the presence or absence of dexamethasone. These results suggest that 1α,25(OH)2D3 modulation of lipid metabolism in bone marrow stromal cells is receptor mediated.
Modulation of cultured chicken growth plate chondrocytes by transforming growth factor‐β1 and basic fibroblast growth factor
Authors: Wu Licia N. Y. , Genge Brian R. , Ishikawa Yoshinori , Wuthier Roy E. 
Published: May 2005

AbstractExpression of several cellular and matrix proteins which increase significantly during the maturation of growth plate cartilage has been shown to be affected by various endocrine and autocrine factors. In the studies reported here, transforming growth factor‐β (TGF‐β1) and basic fibroblast growth factor (bFGF) were administered to primary cultures of avian growth plate chondrocytes at pre‐ or post‐confluent stages to study the interplay that occurs between these factors in modulating chondrocytic phenotype. Added continuously to pre‐confluent chondrocytes, TGF‐β1 stimulated the cells to produce abundant extracellular matrix and multilayered cell growth; cell morphology was altered to a more spherical configuration. These effects were generally mimicked by bFGF, but cell shape was not affected. Administered together with TGF‐β1, bFGF caused additive stimulation of protein synthesis, and alkaline phosphatase (AP) activity was markedly, but transiently enhanced. During this pre‐confluent stage, TGF‐β1 also increased fibronectin secretion into the culture medium. Added to post‐confluent cells, TGF‐β1 alone caused a dosage‐dependent suppression of AP activity, but bFGF alone did not. Under these conditions, TGF‐β1 and bFGF had little effect on general protein synthesis, but TGF‐β1 alone caused large, dosage‐dependent increases in synthesis of fibronectin, and to some extent type II and X collagens. Given together with bFGF, TGF‐β1 synergistically increased secretion of fibronectin. These findings reveal that regulation of phenotypic expression in maturing growth plate chondrocytes involves complex interactions between growth factors that are determined by timing, level, continuity, and length of exposure.
Teratocarcinoma F9 cells induced to differentiate with sodium butyrate produce both tissue‐type and urokinase‐type plasminogen activators
Authors: Takeda Masashi , Kosaka Mitsuko , Nishina Yukio , Sawada Ken , Matsumoto Keishi , Nishimune Yoshitake 
Published: May 2005

AbstractSodium butyrate (NaB) can induce teratocarcinoma cell differentiation as retinoic acid (RA). However, the function of these two agents seems to be a little different [Kosaka et al., Exp Cell Res, 192 : 46–51, 1991]. F9 cells treated with NaB synthesize both tissue‐type (tPA) and urokinase‐type (uPA) plasminogen activator, though RA induces only tPA production. Urokinase‐type PA is demonstrated to exist in association with membrane and to localize its activity to the close environment of the cell surface. This may cause the specific cell morphology and characteristics of differentiated F9 cells induced with NaB.