bluuebunny/crossref_metadata_2025_split huggingface dataset:
Retinoids regulate expression of the retinol‐binding protein gene in hepatoma cells in culture
Authors: Mourey Marie Sophie , Quadro Loredana , Panariello Luigi , Colantuoni Vittorio 
Published: February 2005

AbstractThe expression of the gene coding for retinol‐binding protein has been studied in a system of cultured human hepatoma cells exposed to retinoids. We report that the gene is positively modulated by retinol and retinoic acid in a time‐ and dose‐dependent fashion. The stimulation at the mRNA level is paralleled by an increase of the corresponding protein that is secreted in the presence of the physiological ligand. An RBP‐CAT chimeric gene, introduced by transfection, is also responsive to the treatment, showing the gene dose‐dependency as the endogenous gene. These results demonstrate that retinoids up‐regulate the RBP gene and that the control takes place at transcriptional level. © 1994 Wiley‐Liss, Inc.
Tumor cells secrete an Angiogenic factor that stimulates basic fibroblast growth factor and Urokinase expression in Vascular Endothelial cells
Authors: Peverali Fiorenzo A. , Mandriota Stefano J. , Ciana Paolo , Marelli Rosaria , Quax Paul , Rifkin Daniel B. , Valle Giuliano Della , Mignatti Paolo 
Published: February 2005

AbstractCulture medium conditioned by human SK‐Hep1 hepatoma cells or mouse S180 sarcoma cells rapidly up‐regulates endothelial cell expression of basic fibroblast growth factor (bFGF) and induces formation of a capillary‐like structures by vascular endothelial cells grown on three‐dimensional fibrin gels (in vitro angiogenesis). Incubation of endothelial cells with the tumor cell‐conditioned media also results in increased expression of urokinase plasminogen activator (uPA), a key component of the proteolytic system required for cell invasion and capillary formation. Although the tumor cell‐conditioned media contain no bFGF, addition of anti‐recombinant bFGF IgG abolishes the up‐regulation of uPA and blocks in vitro angiogenesis. This indicates that both the increase in uPA production and formation of capillary‐like structures are mediated by endogenous bFGF expressed by the endothelial cells. Both the bFGF/uPA‐inducing activity and the angiogenic activity of SK‐Hep1 cell‐conditioned medium copurify with a relatively acid‐resistant peptide that has moderate affinity for heparin and Mr < 18 kDa > 3.5 kDa. Known cytokines with similar biochemical features do not possess the same biological activity. These findings indicate that angiogenesis can be mediated by endothelial cell bFGF through an autocrine mechanism and that the bFGF‐inducing peptide may represent a novel tumor‐derived angiogenic factor that modulates in endothelial cells the concerted expression of cytokines and proteolytic enzymes required for capillary formation. © 1994 Wiley‐Liss, Inc.
Dog platelets accumulate intracellular Fibrinogen as they age
Authors: Heilmann E. , Hynes L. A. , Friese P. , George J. N. , Burstein S. A. , Dale G. L. 
Published: February 2005

AbstractThe alpha granules of circulating platelets are dynamic structures that acquire endogenous and exogenous components by synthesis and uptake, respectively. The uptake of exogenous components is a result of either receptor‐mediated endocytosis or fluid‐phase pinocytosis. Despite many detailed studies on the function and content of α‐granules, little is known of the impact of platelet age on these organelles. In this report, we describe the use of platelet biotinylation to identify and isolate aged platelets for the analysis of α‐granule contents. When aged platelets were permeabilized and examined by flow cytometry utilizing fluorescently labeled antibodies, two exogenously acquired proteins, fibrinogen and immunoglobulin G, were found to increase significantly with platelet age. The levels of intracellular fibrinogen were found to be elevated relative to control, 114 ± 2% and 119 ± 5% on days 4 and 5 postbiotinylation, respectively; the life span of dog platelets is 6.0 days. Intracellular immunoglobulin G content increased similarly. Levels of two endogenously synthesized proteins, thrombosponding and P‐selectin, were not elevated in aged platelets. Confirmation of the flow cytometric data was obtained by isolating aged, biotinylated platelets by fluorescence‐activated cell sorting and quantitating the fibrinogen levels with an ELISA assay. For platelets averaging 4.6 days of age, the fibrinogen level was elevated to 128 ± 23% of the level for the entire platelet population. These data demonstrate that age‐dependent changes in exogenously acquired α‐granule proteins do occur and that the uptake mechanism for these proteins is active through out the platelet life span. © 1994 Wiley‐Liss, Inc.
cAMP modulates stress protein synthesis in human Monocytes‐Macrophages
Authors: Pizurki Lara , Polla Barbara S. 
Published: February 2005

AbstractThe synthesis of heat‐shock proteins (HSPs) and other stress proteins, including heme oxygenase (HO) and ferritin, is differentially induced by heat and oxidizing agents. In order to determine what role cAMP plays in those inductions in human monocytes‐macrophages (mϕ), we used cAMP activators or analogues alone or in combination with various stressful conditions. A stimulation in cAMP production did not per se affect stress proteins synthesis in mϕ but modulated their induction in a differential way according to the stimulus. cAMP increased the synthesis of HSPs after heat shock. During erythrophagocytosis, whereas cAMP depressed the phagocytic process and the associated generation of superoxide anions, it enhanced the synthesis of HSPs, while inhibiting that of HO and ferritin. These results indicate that cAMP has a direct enhancing effect on the expression of stress proteins controlled by a classic heat‐shock promoter, while decreasing their expression when induced by oxidative stress. © 1994 Wiley‐Liss, Inc.
Identification and distribution of insulin receptors on cultured bovine brain microvessel endothelial cells: Possible function in insulin processing in the blood–brain barrier
Authors: Miller Donald W. , Keller Bradley T. , Borchardt Ronald T. 
Published: February 2005

AbstractThe binding of 125 I‐insulin to primary cultures of bovine brain microvessel endothlial cells was examined. Insulin binding was both time and temperature dependent and inhibited by excess unlabeled insulin. Furthermore, the specific binding of insulin was polarized to the apical side of the cell monolayers. Upon binding, the labeled insulin was internalized, with approximately 70% resistant to acid wash over a 90‐min period. The inhibition of insulin internalization observed with cell monolayers exposed to either phenylarsine oxide or unlabeled insulin suggests a receptor‐mediated endocytic process. Furthermore, the ability of chloroquine to reduce the metabolism of insulin indicates a significant portion of the peptide iis processed through a lysosomal pathway. In contrast to the fluid‐phase endocytosis marker, Lucifer yellow, as much as 65% of internalized insulin undergoes apical to basolateral trancytosis in brain microvessel endothelial cells. While most of the effluxed insulin was degraded, as assessed by trichloroacetic acid precipitation, the results of the present study suggest insulin receptors within the brain microvasculature may be involved in the processing and transport of bloodborne insulin. © 1994 Wiley‐Liss, Inc.
Ornithine decarboxylase gene expression is aberrantly regulated via the cAMP signal transduction pathway in malignant H‐ras transformed cell lines
Authors: Hurta Robert A. R. , Wright Jim A. 
Published: February 2005

AbstractWe have tested the hypothesis that H‐ras transformed cells contain alterations in signal pathways important in controlling the expression of ornithine decarboxylase (ODC), the highly regulated rate‐limiting activity in the biosynthesis polyamines. Mouse 10 T 1/2 fibroblasts and a series of 10 T 1/2 H‐ras transformed cell lines were treated with stimulators of cAMP synthesis (forskolin and cholera toxin), a biologically stable analogue of cAMP (8‐bromo‐cAMP), and an inhibitor of cAMP degradation (3‐isobutyl‐1‐methylxanthine). Elevations in ODC gene expression were noted in H‐ras transformed cells that were not observed in parental 10 T 1/2 fibroblasts. The forskolin‐mediated effects were not detected with 1,9‐dideoxyforskolin, a compound structurally related to forskolin, which does not activate adenyl cyclase. The effects observed with cholera toxin were not detected when cells were treated with the purified subunits of this compound, indicating that the toxin‐induced effects were cAMP‐specific. Actinomycin D treatment prior to forskolin exposure reduced the elevation observed in ODC gene expression indicating the involvement of the transcriptional process. Furthermore, we observed that cycloheximide treatment of malignant but not benign H‐ras transformed cells significantly elevated ODC message level. Treatment of malignant cells with both cycloheximide and forskolin together resulted in a further additive elevation in ODC message, but a similar treatment of benign tumor cells reduced the forskolin‐mediated increase in ODC message. In addition, treatment of H‐ras transformed cell with the tumor promoter, 12‐0‐tetradecanoylphorbol‐13‐acetate (TPA) led to an elevation in ODC mRNA levels not observed in parental 10 T 1/2 fibroblasts. Cells treated with a combination of TPA and forskolin. Exposure of H‐ras transformed cells to TPA and forskolin together led to further pronounced increases in ODC message when compared to treatment with TPA or forskolin alone. These results demonstrate aberrant regulation of signal pathways involved in controlling ODC gene expression in H‐ras transformed cells and provide further insight into the altered growth regulatory program associated with malignant transformation. © 1994 Wiley‐Liss, Inc.
Glandular‐like morphogenesis and secretory activity of human tracheal gland cells in a three‐dimensional collagen gel matrix
Authors: Jacquot Jacky , Spilmont Christophe , Burlet Henriette , Fuchey Claudette , Buisson Anne Cecile , Tournier Jean Marie , Gaillard Dominique , Puchelle Edith 
Published: February 2005

AbstractThe extracellular matrix has been demonstrated to affect the differentiation of epithelial cells. We present evidence that in a three‐dimensional (3‐D) type I collagen gel matrix, isolated human adult tracheal gland (HTG) cells are capable of reconstructing new functional gland‐like tubules in vitro. During the first two weeks in culture, HTG cells developed globular epithelial cell aggregates in which lumina is absent. By the third week in culture, the tubulogenesis and the formation of branching structures became evident with a polarized morphology, which in many aspects resembles the in vivo morphology. A central lumen was lined by polarized secretory epithelial cells exhibiting well‐developed microvilli and apical secretory granules. Furthermore, we showed that the capacity of in vitro tracheal gland differentiation was associated with the basal deposition of laminin and type IV collagen around the gland‐like tubules. A cell‐associated 72 kDa type IV collagenase was expressed in developing tubule cells, as shown by immunocytochemistry. The secretion of the antileucoprotease (ALP), a protein marker of tracheal gland serous cells, was bidirectional in gland‐like tubules, since up to 65% of released ALP was in the basolateral direction. Taken together, these observations indicate that isolated HTG cells in a 3‐D collagen matrix form functional tracheal gland‐like tubules and suggest that similar new tracheobronchial gland formations may occur during the human normal gland development and remodeling. © 1994 Wiley‐Liss, Inc.
Development of dexamethasone‐inducible tyrosine aminotransferase activity in WB‐F344 rat liver epithelial stemlike cells cultured in the presence of sodium butyrate
Authors: Coleman William B. , Smith Gary J. , Grisham Joe W. 
Published: February 2005

AbstractSodium butyrate acts as a differentiation‐promoting agent for a wide variety of cell types, including some tumor cell lines. In this study, we examined the effects of sodium butyrate (SB) on the functional differentiation of cultured WB‐F344 rat liver epithelial stemlike cells. Treatment of WB‐F344 cells with 3.75 mM SB resulted in an inhibition of cellular proliferation, alterations to normal cellular morphology (increased cell size and decreased nuclear/cytoplasmic ratio), and significant increases in cellular protein synthesis. The SB‐mediated changes in cell morphology, proliferative status, and protein catabolism were accompanied by development of dexamethasone‐inducible tyrosine aminotransferase (TAT) enzyme activity. Culture of WB‐F344 cells in growth medium containing SB and dexamethasone (DEX; 1 × 10‐6 M) resulted in greater than sevenfold increase in the basal TAT activity compared with control cultures. An additional sixfold increase in TAT activity was observed when cells cultured in medium containing SB and DEX were exposed to 1 × 10‐7 M DEX during the last 24 hours of culture. The DEX‐inducible TAT activity developed by SB‐treated WB‐F344 cells responded to the modulating effects of insulin and L‐tyrosine in a manner that closely resembled that reported for cultured hepatocytes and hepatoma cell lines. These studies show that treatment of WB‐F344 rat liver epithelial stemlike cells with the differentiation‐promoting agent SB in vitro leads to expression of the differentiation‐specific hepatocyte enzyme TAT. © 1994 Wiley‐Liss, Inc.
Control of AKR fibroblast phenotype by fibronectin: Regulation of cell‐surface fibronectin binding receptor by fibronectin
Authors: Huang Shuang , Varani James , Chakrabarty Subhas 
Published: February 2005

AbstractResults of previous studies show that the expression of fibronectin and its cell‐surface fibronectin binding receptor is coregulated in 3‐methylchloranthrene transformation of normal AKR‐2B cells to form AKR‐MCA cells and in N, N,‐dimethylformamide (DMF) induction of differentiation of transformed AKR‐MCA cells (1990, J. Cell. Physiol., 143:445). In this study, we tested the corgulation hypothesis by transfection experiments using an antisense fibronectin expression vector. We determined the effect of antisense fibronectin RNA expression on untransformed AKR‐2B cells, and on the responses of transformed AKR‐MCA cells to DMF treatment. Expression of antisense fibronectin RNA in AKR‐2B cells down‐modulated fibronectin production, reduced adhesion to extracellular fibronectin, and altered cellular morphology Saturation binding and Scatchard analyses using radiolabelled fibronectin revealed a concurrent down‐modulation of cell‐surface fibronectin binding sites, but the binding affinity of the receptor for the ligand was not affected. Immunoblotting and immunostaining revealed down‐modulation of the expression of α5β1 integrins. Expression of antisense fibronectin RNA in AKR‐MCA cells down‐modulated the ability of DMF to restore normal fibronectin production, cell‐surface fibronectin binding receptor, adhesion to extracellular fibronectin, and cellular morphology. These studies show that both fibronectin and its cell‐surface fibronectin binding receptor were tightly regulated during transformation and induction of differentiation in these cells, that the ligand and its cell‐surface fibronectin binding receptor worked together to bring about phenotypic changes, and that fibronectin production regulated the expression of its cell‐surface fibronectin binding receptor. © 1994 Wiley‐Liss, Inc.
Inhibition of mechanical strain‐induced fetal rat lung cell proliferation by gadolinium, a stretch‐activated channel blocker
Authors: Liu Mingyao , Xu Jing , Tanswell A. Keith , Post Martin 
Published: February 2005

AbstractNormal growth of the fetal lung is dependent upon fetal breathing movements. We have previously demonsrated that mechanical strain, simulating fetal breathing movements, stimulated DNA synthesis and cell division by reaggregated alveolar‐like structures of fetal rat lung cells. Herein, we report that both intracellular and extracellular calcium modulate strain‐induced proliferative activity. Strain‐induced cell proliferation was inhibited by BAPTA/AM, an intracellular calcium chelator. The intracellular calcium modulators, cyclopiazonic acid and 2,5‐di‐(tert‐butyl)‐1, 4‐benzohydroquinone, increased DNA synthesis of unstrained cultures and partially reduced strain‐induced cell growth activity. A similar effect was noted with the calcium ionophore A23187. Extracellular Ca2+ increased DNA synthesis in unstrained cultures in a concentration‐dependent fashion. The stimulatory effect of strain on DNA synthesis was also dependent on the calcium concentration in the medium. Furthermore, strain‐enhanced DNA synthesis was inhibited by the presence of a divalent ion chelator, EGTA, in the medium. Mechanical strain increased 45Ca2+ influx within 1 min after the onset strain. This rapid entry of calcium was not affected by calcium channel blockers, such as verapamil or Ni2+. Calcium channel blockers verapamil, nifedipine, Ni2+, Co2+, or La3+ also did not inhibit strain‐induced cell growth activity. In contrast, gadolinium, a stretch‐activated channel blocker, inhibited strain‐induced 45Ca2+ influx and suppressed strain‐enhanced DNA synthesis. We conclude that the entry of calcium into cells through stretch‐activated ion channels plays a critical role in strain‐induced fetal lung cell proliferation. © 1994 Wiley‐Liss, Inc.
Differential effects of cytotactin/tenascin fusion proteins on intracellular pH and cell morphology
Authors: Krushel Leslie A. , Prieto Anne L. , Edelman Gerald M. , Crossin Kathryn L. 
Published: February 2005

AbstractCytotactin/tenascin is a multidomain extracellular matrix protein that inhibits both cell spreading and intracellular alkalinization. The protein has multiple different domains which are homologous to regions in epidermal growth factor, fibronectin, and fibrinogen. In previous studies, we produced nonoverlapping fusion proteins corresponding to these domains and examined their effects on cell attachment and spreading. Based on their ability either to promote or to inhibit cell attachment, two of these fusion proteins were shown to be adhesive and two were shown to be counteradhesive. To determine how the adhesive and counteradhesive activities of different cytotactin/tenascin domains alter intracellular pH (designated pHi), we have measured pHi in NIH3T3 and U251MG cells in the presence of the cytotactin/tenascin fusion proteins and intact cytototactin/tenascin, as well as fibronectin. Cells incubated in the presence of intact cytotactin/tenascin or of the counteradhesive fusion proteins had a pHi lower than control cells. In contrast, the presence of the adhesive fusion proteins or of fibronectin caused cells to have higher pHi values than control cells. When two fragments were simultaneously presented, one of which alone increased pHi and the other of which alone decreased pHi, the predominant effect was that of lowered pHi. Incubation with an RGD‐containing peptide derived from the cytotactin/tenascin sequence inhibited alkalinization promoted by the adhesive fragment containing the second through sixth fibronectin type III repeats that was known to bind to integrins. Incubation of the cells with heparinase I or III inhibited the intracellular alkalinization of cells plated in the presence of the other adhesive fusion protein containing the fibrinogen domain, suggesting that heparan sulfate proteoglycans were involved in these pHi changes. The activity of protein kinase C appeared to be important for the changes in pHi mediated by all of the proteins. The protein kinase C inhibitor Calphostin C blocked the rise in pHi elicited by the adhesive fusion proteins and by fibronectin. Moreover, activation of protein kinase C by the addition of phorbol esters increased the pHi in cells plated on cytotactin/tenascin or counteradhesive fusion proteins and reversed their effects. The results of this study support the hypothesis that cytotactin/tenascin can bind to multiple cell surface receptors and thereby elicit different physiological responses. Decreases in pHi are correlated with the phenomenon of counteradhesion whereas the ability to increase pHi is associated with cell attachment via at least two different types of cell surface receptors. The data raise the possibility that binding of cytotactin/tenascin may influence primary cellular processes such as migration and proliferation through the differential regulation of pHi. © 1994 Wiley‐Liss, Inc.
Overexpression of plasminogen activator inhibitor type‐1 in senescent fibroblasts from normal subjects and those with Werner syndrome
Authors: Goldstein Samuel , Moerman Elena J. , Fujii Satoshi , Sobel Burton E. 
Published: February 2005

AbstractWe previously reported that plasminogen activator inhibitor type‐1 (PAI‐1) mRNA was present at higher steady‐state levels in prematurely senescent fibroblasts derived from a subject with Werner syndrome (WS) compared to early passage (EP) fibroblasts from an age‐matched normal subject (Murano et al., 1991, Mol. Cell. Biol. 11:3905–3914). To explore the generality of this phenomenon with respect to chronological age of donor (in vivo aging) and the late‐passage (LP) or senescent phase of the fibroblast replicative lifespan, we assayed PAI‐1 mRNA in cells and PAI‐1 antigen in medium conditioned by 20 normal fibroblast strains at EP and LP and six WS strains during their curtailed replicative lifespans. The lowest accumulations of PAI‐1 were found in medium conditioned by fetal and newborn cells with a shallow but progressive rise seen in postnatal cells from normal donors of increasing chronological age. With few exceptions, normal LP fibroblasts showed increased PAI‐1 accumulations in medium compared to their EP counterparts. Conditioned medium from four of the six WS strains showed PAI‐1 accumulations that were significantly higher than the media of any normal controls at EP and LP. PAI‐1 mRNA levels were generally commensurate with the cumulative amount of PAI‐1 in the medium but the frequent exceptions indicate that translational and post‐translational mechanisms also regulate PAI‐1 output. The augmentation in PAI‐1 output of fibroblasts as a direct function of chronological age and during in vitro senescence suggests that PAI‐1 may play an important role in the reduced capacity for wound healing and the increasing tendency to thrombogenesis and atherogenesis seen during biological aging and in particular in persons with Werner syndrome. © 1994 Wiley‐Liss, Inc.