bluuebunny/crossref_metadata_2025_split huggingface dataset:
Proliferating cell nuclear antigen (PCNA) is expressed in activated rat skeletal muscle satellite cells
Authors: Johnson Sally E. , Allen Ronald E. 
Published: February 2005

AbstractSkeletal muscle satellite cells from uninjured muscle of adult animals are generally found to be in a quiescent state, and when cultured, they remain quiescent in vitro for a period of time which is directly related to the age of the donor animal. A technique for studying the activation of satellite cells in primary cultures has been developed and employs proliferating cell nuclear antigen (PCNA) as a marker for entrance into the S phase of the cell cycle. PCNA is a protein involved in DNA replication and is maximally expressed in S phase of the cell cycle. We monitored PCNA expression in satellite cells isolated from young (3 week) and adult (9 month) rats, and our results indicate that satellite cells begin to accumulate PCNA prior to changes in cell number in both age groups. Using ELISA techniques, we demonstrated that addition of an extract of crushed muscle (CME) activated satellite cells and significantly reduced the length of the lag phase in cells from both age groups. Addition of bFGF shortened the lag phase of PCNA synthesis in satellite cells from 3‐week‐old rats but had no effect on the kinetics of PCNA expression in cells from 9‐month‐old rats. Based on our experiments, PCNA expression can be used as a marker to follow the entry of satellite cells into the cell cycle in primary mass cultures. © 1993 Wiley‐Liss, Inc.
Suramin interrupts androgen‐inducible autocrine loop involving heparin binding growth factor in mouse mammary cancer (Shionogi carcinoma 115) cells
Authors: Kasayama Soji , Saito Hiroshi , Kouhara Haruhiko , Sumitani Satoru , Sato Bunzo 
Published: February 2005

AbstractThe androgen‐dependent clonal cell line SC‐3, derived from Shionogi carcinoma 115, secretes a fibroblast growth factor (FGF)‐autocrine growth factor in response to androgen, which is able to bind to FGF receptors. In SC‐3 cells, FGF receptor expression is upregulated by the SC‐3‐derived growth factor, providing a means of amplifying an autocrine loop of cell growth. In the present investigations, the effect of the polysulfonated naphthylurea suramin on this autocrine loop and its amplification in SC‐3 cells were studied. Suramin inhibited androgen‐dependent growth of SC‐3 cells in a concentration‐dependent fashion: ∼50% inhibition was observed at 25 μM. [3H]Thymidine incorporation into the cells stimulated with partially purified SC‐3‐derived growth factor was inhibited by suramin in a similar way. Additionally, suramin inhibited acidic (a) or basic (b) FGF‐induced cell proliferation, though relatively high concentrations were necessary to achieve the maximal inhibition. Pretreatment of SC‐3 cells with suramin decreased cell surface 125I‐bFGF binding without altering dissociation constant (Kd) of the binding sites. When the cells were incubated with 250 μM suramin for 24 h, the maximum binding (Bmax) decreased to almost 50% of the control. Treatment with suramin also decreased the levels of FGF receptor‐1 mRNA to a similar extent, whereas it appeared not to affect the levels of β‐actin mRNA. Moreover, suramin completely blocked androgen‐ or bFGF‐induced accumulation of FGF receptor‐1 mRNA. The inhibitory effects of suramin on FGF receptor expression were reversed by simultaneous addition of high concentrations of bFGF. These results indicate that suramin exerts its potent antiproliferative action on SC‐3 cells through inhibition of an androgen‐inducible autocrine loop involving SC‐3‐derived growth factor and FGF receptor. © 1993 Wiley‐Liss, Inc.
Effect of low extracellular Ca2+ on growth spreading area, cytoplasmic Ca2+ concentration, and intracellular pH in normal and transformed human fibroblasts
Authors: Yoshida Toshimichi , Takahashi Yasuo , Takashima Shiro 
Published: February 2005

AbstractThe transformation of certain cells reduces the requirement of extracellular Ca2+ for growth. The SV‐40 transformed human lung fibroblasts, WI‐38 VA13, require less Ca2+ than normal WI‐38 cells. Spreading area of normal cells decreases when cultured in 10 μM Ca2+ medium. Intracellular calcium concentration ([Ca2+]i), of the normal and transformed cells cultured in 10μM and 2 mM Ca2+ media was measured by the fluorescence microscope technique using fura‐2 as a probe. The [Ca2+], is measured in the resting state and during mobilization by serum or bradykinin stimulation. The lowering of extracellular calcium concentration results in a decrease in the resting state [Ca2+],i of both normal and transformed cells. Although the total decrease in [Ca2+]i is the same for both cell, the rate of decrease is much faster in normal cells than in transformed cells. Low extracellular Ca2+ reduces the number of cells responsive to the serum or bradykinin stimulation and decreases the peak [Ca2+]i value in both cells. In addition, we investigated, using BCECF as a fluorecent probe, the intracellular pH (pHi) of normal and transformed cells maintained at low and normal Ca2+. The low Ca2+ condition makes pHi acidic in normal cells but not in transformed cells. The acidification of the normal cell is accompanied by a decrease in the spreading area of the cells. The decrease of the cell attacment, followed by the reduced spreading area, induced the acidic pHi. These results suggest that the reduced Ca2+ requirement of transformed cells for growth is related to the mechanism of pHi regulation rather than Ca2+ homeostasis and, possibly, to the anchorage‐independent growth, which is a unique feature of transformed cells. © 1993 Wiley‐Liss, Inc.
Establishment of a hepatocytic epithelial cell line from the murine fetal liver capable of promoting hemopoietic cell proliferation
Authors: Hata Masahiro , Nanno Masanobu , Doi Hideyuki , Satomi Susumu , Sakata Tsuneaki , Suzuki Ryuji , Itoh Tsunetoshi 
Published: February 2005

AbstractAlthough the fetal liver has been thought to be the main hemopoietic organ in the embryonal period, whether or not hepatocytes play a major role in hemopoiesis remains obscure. We have established an epithelial cell line from the murine fetal liver, which can support hemopoiesis in vitro. The proliferation of the epithelial cells was promoted synergistically by both epidermal growth factor (EGF) and insulin. The cells were identified as epithelial cells by the presence of desmosomes and tight junctions. Cytoplasmic organelles including small mitochondria and dilated Golgi apparati as well as intercellular canalicular structures similar to bile canaliculus also helped in confirming the hepatic origin of the cell line (designated as FHC). The cells in the primary culture were positive for both α ‐fetoprotein and albumin, indicating the hepatocytic nature of the cell line. Cloned FHC cells were demonstrated to have the ability to maintain hemopoietic progenitors in fetal liver and adult bone marrow in the coculture, and among them, FHC‐4D2 clone displayed the greatest activity. Hemopoiesis‐supporting function could also be seen even when bone marrow cells were separated from FHC‐4D2 cells by nitrocellulose membrane. Column chromatography revealed three distinct peaks of hemopoietic activities with different molecular sizes in the supernatant of FHC‐4D2. Neutralization test with antibodies and proliferative response to interleukin‐3 (IL‐3)/granulocyte‐macrophage colony stimulating factor (GM‐CSF)‐IC2 cells demonstrated that the hemopoietic activities were attributed to GM‐CSF and macrophage colony stimulating factor (M‐CSF). Transcripts of GM‐CSF and M‐CSF were readily detectable in Northern blot analysis, whereas no messages for IL‐3, IL‐6, CSF for granulocytes (G‐CSF) or erythropoietin (EPO) were identified. Therefore, this is the first report on the fetal hepatocyte cell line capable of supporting hemopoiesis. © 1993 Wiley‐Liss, Inc.
Cytokine‐induced expression of mRNAs for chemotactic factors in human synovial cells and fibroblasts
Authors: Bédard Pierre‐André , Golds Elaine E. 
Published: February 2005

AbstractIn response to interleukin 1 or tumor necrosis factor, human synovial cells and fibroblasts expressed several genes encoding known chemotactic factors or related proteins. Transcripts for interleukin 8 (IL‐8), gro/MGSA, pAT 464, IP‐10, pAT 744 and Monocyte Chemotactic and Activating Factor (MCAF) accumulated rapidly in IL‐1 and TNF‐treated cells. The inhibition of protein synthesis led to the superinduction of IL‐8 and gro/MGSA mRNAs in IL‐1, but not in TNF‐treated cells. Thus, IL‐1 and TNF are likely to regulate the expression of these mRNAs by different mechanisms. Important cell‐specific differences in mRNA accumulation characterized the expression of chemotactic factor genes. Moreover, only a subset of the same genes was activated in quiescent cells stimulated by serum. Therefore, genes encoding closely related proteins each had a distinct pattern of expression. Continuous stimulation of fibroblasts and synovial cells with IL‐1 resulted in high and prolonged expression of IL‐8 and gro/MGSA mRNAs. These results extend the list of chemotactic factor genes expressed by mesenchymal cells in vitro and suggest a pivotal role for these cells in processes such as chronic inflammation. © 1993 Wiley‐Liss, Inc.
Extracellular matrix produced by cultured corneal and aortic endothelial cells contains active tissue‐type and urokinase‐type plasminogen activators
Authors: Korner Gil , Bjornsson Thorir D. , Vlodavsky Israel 
Published: February 2005

AbstractIncubation of plasminogen with the subendothelial extracellular matrix (ECM) synthesized by cultured bovine corneal and aortic endothelial cells resulted in generation of fibrinolytic activity, indicated by proteolysis of 125I‐fibrin in a time‐and dose‐dependent manner. Both tissue‐type plasminogen activator (t‐PA) and urokinase‐type plasminogen activator (u‐PA) were identified in the ECM by fibrin zymography, immunoblotting, and inhibition of plasminogen activation by anti‐u‐and anti‐t‐antibodies. Most of the ECM‐resident plasminogen activator (PA) activity did not originate from intracellular PA release occurring when the endothelial cells were lyzed and the ECM exposed, since a comparable amount of PA was associated with the ECM when the cells were lyzed with Triton X‐100 or removed intact by treatment with 2 M urea. Active u‐PA and t‐PA were released from ECM by treatment with heparanase (endo‐β‐D‐), indicating that some of the ECM‐resident PA activity is sequestered by heparan sulfate side chains. These results indicate that both u‐PA and t‐PA produced by endothelial cells are firmly sequestered in an active form by the subendothelial ECM. It is suggested that ECM‐resident plasminogen activators participate in sequential matrix degradation during cell invasion and tumor metastasis. PA activity may also function in release of ECM‐bound growth factors (i.e., basic fibroblast growth factor) and activation of proenzymes (i.e., prothrombin), resulting in modulation of the ECM growth‐promoting and thrombogenic properties. © 1993 Wiley‐Liss, Inc.
Elevated glutathione S‐transferase gene expression is an early event during steroid‐induced lymphocyte apoptosis
Authors: Flomerfelt Francis A. , Briehl Margaret M. , Dowd Diane R. , Dieken Ellen S. , Miesfeld Roger L. 
Published: February 2005

AbstractBased on the finding that glutathione S‐transferase Yb1 (GST) gene expression is elevated in the regressing prostate of androgen‐ablated rats, we analyzed GST transcript levels during steroid‐induced lymphocyte cell death. It was found that GST gene expression was induced in steroid‐sensitive cells within 4 hr of dexamethasone treatment, required functional glucocorticoid receptor, and was dose‐dependent with regard to hormone. GST expression was not induced in an apoptosis‐defective variant that contained normal levels of functional receptor, indicating that GST up‐regulation was the result of secondary events that occur during steroid‐mediated apoptosis. Using the calcium ionophore A23817 to induce lymphocyte cell death, GST RNA levels were increased in both steroid‐sensitive and steroid‐resistant cell lines, supporting the conclusion that elevated GST expression was the result of cellular processes associated with apoptosis, rather than a direct consequence of steroid‐mediated transcriptional control. The cells were also treated with dibutyryl cAMP to cause cell death; however, this mode of killing did not result in GST up‐regulation. Taken together, these results suggest that GST induction in dexamethasone‐treated T‐lymphocytes occurs early in the steroid‐regulated apoptotic pathway and that this may be a marker of calcium‐stimulated cell death. Based on the known function of GST as an antioxidant defense enzyme and its transcriptional regulation by reactive oxygen intermediates, we propose that the gene product of a primary GR target gene(s) directly or indirectly effects the redox state of the cell. Thus activation of GST gene expression in apoptotic lymphocytes is likely a indicator of oxidative stress, rather than a required step in the pathway. © 1993 Wiley‐Liss, Inc.
Fibroblast growth factor receptor deficiency in dystrophic retinal pigmented epithelium
Authors: Malecaze F. , Mascarelli F. , Bugra K. , Fuhrmann G. , Courtois Y. , Hicks D. 
Published: February 2005

AbstractThe retinal pigmented epithelium (RPE) is known to be site of the primary lesion in inherited retinal dystrophy in the Royal College of Surgeons (RCS) rat, a model for retinitis pigmentosa. Although the only functional defect so far detected in these cells is their failure to efficiently phagocytose shed photoreceptor outer segment debris, the actual cause of photoreceptor cell death is still unknown. Recently the possibility of “trophic factors” important in photoreceptor survival produced by normal RPE but not by dystrophic RPE has been suggested. Hence we decided to investigate the presence and abundance of two candidate diffusible factors, the acidic and basic fibroblast growth factors (aFGF and bFGF, respectively), as well as their high affinity cell surface receptors (FGF‐R). mRNA was isolated from primary cultures of purified normal and dystrophic RPE and analyzed by PCR amplification using specific oligonucleotide primers for aFGF and bFGF: the size and abundance of amplified fragments was similar for both cell types. Also, aFGF protein, detected by immunocytochemistry using specific antisera, appeared to be present in approximately equal amounts and distributed in a similar pattern. However, scatchard analysis of radio‐labelled bFGF binding to primary cultures of normal and dystrophic rat RPE revealed that dystrophic RPE possess only 29% the number of surface receptors compared to congenic normal cells. Furthermore, the level of expression of FGF‐R2 mRNA, but not that of FGF‐R1, was significantly different. Other parameters measured (receptor affinity, profile of ligand internalization and degradation, receptor molecular weight and mitogenic activity) did not show any significant differences between normal and dystrophic RPE. The precise role of FGF‐R deficiency in the etiology of the disease hence remains to be determined, but it indicates the importance of trophic factors in the normal functioning of the retina. © 1993 Wiley‐Liss, Inc.
Role of Ca2+ in stimulation of DNA synthesis by epidermal growth factor and tumor promoters in cultured rat hepatocytes
Authors: Petronijevic Tadija , Edwards Anthony M. 
Published: February 2005

AbstractThis study examines the effects of extracellular Ca2+ concentrations, [Ca2+]o, and of treatments known to modulate intracellular Ca2+ levels on the extent and timing of DNA synthesis in primary cultures of adult rat hepatocytes. In cultures exposed to insulin and EGF, the extent of DNA synthesis between 40 h and 70 h in culture was independent of [Ca2+]o in the range 25–1,800 μM, although the peak of DNA synthesis occurred 5–10 h earlier with 1.2 mM Ca2+ than with 25 μM Ca2+. Complete removal of extracellular Ca2+ using EGTA blocked DNA synthesis if Ca2+ was removed on the second day after EGF addition but not if Ca2+ was absent only on day 1. Treatment of cultures in 1.2 mM Ca2+‐containing media with Ca2+‐ionophore A23187 or with thapsigargin, agents expected to raise cytosolic [Ca2+], failed to augment the stimulation of DNA synthesis by EGF. These observations suggest that hepatocytes may have a permissive requirement for [Ca2+]o > 0 at least late in the sequence of events leading from growth factor stimulation to DNA synthesis. However, sustained elevation of cytosolic [Ca2+] does not appear to be important as an early signalling event either in mediating or augmenting EGF action in hepatocytes. The ability of liver tumor promoters α‐hexachlorocyclohexane or DDT to stimulate DNA synthesis in combination with EGF was independent of [Ca2+]o. By contrast, the skin tumor‐promoting phorbol ester, TPA, or liver tumor promoter, phenobarbital, were without effect or inhibitory at low [Ca2+]o but in combination with EGF, stimulated DNA synthesis at [Ca2+]o > 0.4 mM, suggesting that Ca2+ may have some role in mediating or modulating the stimulatory effects of these agents. © 1993 Wiley‐Liss, Inc.
Mechanical stimulation of skeletal muscle generates lipid‐related second messengers by phospholipase activation
Authors: Vandenburgh Herman H. , Shansky Janet , Karlisch Patricia , Solerssi Rosa Lopez 
Published: February 2005

AbstractRepetitive mechanical stimulation of cultured avian skeletal muscle increases the synthesis of prostaglandins (PG) E2 and F2α which regulate protein turnover rates and muscle cell growth. These stretch‐induced PG increases are reduced in low extracellular calcium medium and by specific phospholipase inhibitors. Mechanical stimulation increases the breakdown rate of 3H‐arachidonic acid labelled phospholipids, releasing free 3H‐arachidonic acid, the rate‐limiting precursor of PG synthesis. Mechanical stimulation also increases 3H‐arachidonic acid labelled diacylglycerol formation and intracellular levels of inositol phosphates from myo‐[2‐3H]inositol labelled phospholipids. Phospholipase A2 (PLA2), phosphatidylinositol‐specific phospholipase C (PLC), and phospholipase D (PLD) are all activated by stretch. The stretch‐induced increases in PG production, 3H‐arachidonic acid labelled phospholipid breakdown, and 3H‐arachidonic acid labelled diacylglycerol formation occur independently of cellular electrical activity (tetrodotoxin insensitve) whereas the formation of inositol phosphates from myo‐[2‐3H]inositol labelled phospholipids is dependent on cellular electrical activity. These results indicate that mechanical stimulation increases the lipid‐related second messengers arachidonic acid, diacylglycerol, and PG through activation of specific phospholipases such as PLA2 and PLD, but not by activation of phosphatidylinositol‐specific PLC. © 1993 Wiley‐Liss, Inc.
Proliferative and migratory responses of murine microvascular endothelial cells to granulocyte‐colony‐stimulating factor
Authors: Bocchietto Elena , Guglielmetti Antonella , Silvagno Francesca , Taraboletti Giulia , Pescarmona Gian Piero , Mantovani Alberto , Bussolino Federico 
Published: February 2005

AbstractMicrovascular murine endothelial cells lines transformed by middle T oncogene of polyoma virus maintain the biological characteristics of nontransformed microvascular endothelial cells (EC). By using cell lines originated from different anatomical districts (thymus, brain, heart, and skin), we demonstrated that murine granulocyte‐colony‐stimulating factor (G‐CSF) induces proliferation of murine microvascular endothelial cells at nanomolar concentrations without any cooperation with fetal calf serum. The proliferative effect on murine cells is less than that elicited by epidermal growth factor (EGF), used as standard for this function. G‐CSF also promotes the migration of tEnd.1 endothelial cell line assayed by Boyden chamber technique. The analysis of transcript for G‐CSF receptor (G‐CSFR) by Northern blot hybridization and by reverse‐transcriptase polymerase chain reaction (RT‐PCR) shows that these cell lines have specific mRNA, with the size of that present in myeloid cells. These results indicate that G‐CSF operates in the microvascular endothelial cells by a mechanism related to the presence of a specific receptor. © 1993 Wiley‐Liss, Inc.
Proteases are implicated in the changes in the Sertoli cell cytoskeleton elicited by follicle‐stimulating hormone or by dibutyryl cyclic AMP
Authors: Tung Pierre S. , Burdzy Krystyna , Fritz Irving B. 
Published: February 2005

AbstractFollicle‐stimulating hormone (FSH) or dibutyryl cyclic AMP (dbcAMP) elicits striking morphological changes in Sertoli cells in culture in serum‐free medium, resulting in a transition from an epithelial type of cell association pattern to that of an astrocytic or fibroblast‐like cell, with attenuated cytoplasmic extensions between cells, and with diminished F‐actin stained stress fibers. These responses of Sertoli cells do not occur in the presence of normal untreated serum, but they do take place in the presence of acid‐treated serum which is depleted of antiproteases. The addition of α2‐macroglobulin to serum‐free medium or to antiprotease‐depleted serum resulted in the blockage of morphological responses of Sertoli cells to FSH or to dbcAMP. Changes in pattern of arrangements of F‐actin in Sertoli cells in culture, which occur in response to FSH or to dbcAMP, were also prevented by the presence of α2‐macroglobulin. Thus, the diminution in bundles of F‐actin containing stress fibers, which otherwise takes place in Sertoli cells stimulated by FSH or by dbcAMP, did not occur in cells in culture in the presence of α2‐macroglobulin, in the presence or absence of acid‐treated serum. The inhibiting effects of dbcAMP on the migration of Sertoli cells in serum‐free medium became nondetectable in medium containing normal untreated serum, but remained evident in Sertoli cells in culture in medium containing acid‐treated serum depleted of antiproteases. Addition of α2‐macroglobulin blocked the inhibitory effects of dbcAMP on Sertoli cell migration. Similarly, the presence of α2‐macroglobulin prevented the inhibitory effects of dbcAMP on the contractility of TM4 cells which had been embedded in collagen type‐I and incubated in serum‐free medium. We discuss the possibility that cellular proteases may be implicated in the disintegration of microfilament bundles, either by favoring depolymerization of actin filaments; by facilitating breakage of the link of the transmembrane molecular assembly between cytoskeletal extracellular matrix components; or by catalyzing a disruption of the modular organization of one or more of the actin cross‐linking proteins. By inference, we postulate that morphological responses of Sertoli cells to FSH require the activation of cellular proteases for one or more of these reactions, and that α2‐macroglobulin blocks the Sertoli cell morphological responses to FSH by inhibiting the proteases involved. © 1993 Wiley‐Liss, Inc.