bluuebunny/crossref_metadata_2025_split huggingface dataset:
Lipopolysaccharide inhibits activation of latent transforming growth factor‐β in bovine endothelial cells
Authors: Kojima Soichi , Vernooy Robert , Moscatelli David , Amanuma Hiroshi , Rifkin Daniel B. 
Published: February 2005

AbstractThe activation of latent transforming growth factor‐β (TGF‐β) by vascular endothelial cells (ECs) is regulated by cellular plasminogen activator (PA)/plasmin, transglutaminase (TGase), and latent TGF‐β levels. Because lipopolysaccharide (LPS) has been reported to reduce EC surface plasmin levels by increasing the production of the inhibitor of PA, PA inhibitor‐1 (PAI‐1), we have tested whether LPS might suppress latent TGF‐β activation in ECs using two different systems, namely, bovine aortic ECs (BAECs) cocultured with smooth muscle cells (SMCs) and BAECs treated with retinol. BAECs were either cocultured with SMCs after treatment with 15 ng/ml LPS or were treated with 2 μM retinol and/or 10 ng/ml LPS, and the expression of PA, surface plasmin, TGase, and the amounts of active and latent TGF‐β secreted into the culture modium were measured. The downregulation of surface PA/plasmin levels with LPS was accompanied by a profound decline of both TGase and latent TGF‐β expression as well as the suppression of surface activation of latent TGF‐β. The effect was dependent on the concentration of LPS and on treatment time. The formation of TGF‐β did not occur in cells maintained in LPS‐contaminated culture medium. © 1995 Wiley‐Liss, Inc.
Nuclear translocation of prolactin: Collaboration of tyrosine kinase and protein kinase C activation in rat Nb2 node lymphoma cells
Authors: Rao Yi‐Ping , Buckley Donna J. , Olson Mark D. , Buckley Arthur R. 
Published: February 2005

AbstractRecent evidence has suggested that prolactin (PRL), internalized by lactogen‐dependent Nb2 lymphoma cells, is actively translocated to the nucleus where it binds to PRL receptors. Moreover, the mitogenic action of PRL in these cells has been separately linked to protein tyrosyl phosphorylation and activation of protein kinase C (PKC). Therefore, the coupling of PRL internalization and nuclear translocation to the activation of these signal transduction pathways was investigated. Results from control experiments indicated that 30% of internalized and 5% total cell‐associated 125I‐rat PRL could be recovered within nuclei obtained from Nb2 cells previously incubated with the radiolabel for 3 h at 37°C. Furthermore, internalized PRL was found to be intact and not associated with any carrier proteins. Addition of tyrosine kinase (TK) antagonists, genistein or tyrphostin, significantly reduced cell surface binding, internalization, and nuclear translocation of 125I‐rat PRL. In contrast, neither the level of cell‐associated nor internalized hormone differed between cells treated with the PKC antagonists, staurosporine or calphostin C, and control cultures. Instead, PKC inhibition significantly reduced nuclear PRL translocation. The inhibitory effects of the TK and PKC antagonists on PRL internalization and nuclear translocation in intact Nb2 cells were verified by immunofluorescence microscopy in parallel experiments. In other experiments, each of the kinase inhibitors blocked PRL‐stimulated Nb2 cell proliferation in a concentration‐dependent manner. It is concluded that activated TK and PKC collaborate in the process of PRL internalization and translocation to the nucleus. TK activation may participate in PRL receptor binding or hormone internalization while activation of PKC appears to be required for its nuclear targeting. Since TK and PKC activation are required for lactogen‐stimulated Nb2 cell proliferation, we suggest that a component of the mitogenic pathway in these cells is a direct nuclear interaction of PRL. © 1995 Wiley‐Liss, Inc.
Regulation of endothelial cell gap formation and barrier dysfunction: Role of myosin light chain phosphorylation
Authors: Garcia Joe G. N. , Davis Harold W. , Patterson Carolyn E. 
Published: February 2005

AbstractEndothelial cell (EC) contraction results in intercellular gap formation and loss of the selective vascular barrier to circulating macromolecules. We tested the hypothesis that phosphorylation of regulatory myosin light chains (MLC) by Ca2+/calmodulin‐dependent myosin light chain kinase (MLCK) is critical to EC barrier dysfunction elicited by thrombin. Thrombin stimulated a rapid (<15 sec) increase in [Ca2+]i which preceded maximal MLC phosphorylation (60 sec) with a 6 to 8‐fold increase above constitutive levels of phosphorylated MLC. Dramatic cellular shape changes indicative of contraction and gap formation were observed at 5 min with maximal increases in albumin permeability occurring by 10 min. Neither the Ca2+ ionophore, A23187, nor phorbol myristate acetate (PMA), a direct activator of protein kinase C (PKC), alone or in combination, produced MLC phosphorylation. The combination was synergistic, however, in stimulating EC contraction/gap formation and barrier dysfunction (3 to 4‐fold increase). Down‐regulation or inhibition of PKC activity attenuated thrombin‐induced MLC phosphorylation (∼40% inhibition) and both thrombin‐ and PMA‐induced albumin clearance (∼50% inhibition). Agents which augmented [cAMP]i partially blocked thrombin‐induced MLC phosphorylation (∼50%) and completely inhibited both thrombin‐ and PMA‐induced EC permeability (100% inhibition). Furthermore, cAMP produced significant reduction in the basal levels of constitutive MLC phosphorylation. Finally, MLCK inhibition (with either ML‐7 or KT 5926) or Ca2+/calmodulin antagonism (with either trifluoperazine or W‐7) attenuated thrombin‐induced MLC phosphorylation and barrier dysfunction. These results suggest a model wherein EC contractile events, gap formation and barrier dysfunction occur via MLCK‐dependent and independent mechanisms and are significantly modulated by both PKC and cAMP‐dependent protein kinase A activities. © 1995 Wiley‐Liss, Inc.
Differential regulation of integrin‐mediated proplatelet formation and megakaryocyte spreading
Authors: Leven Robert M. 
Published: February 2005

AbstractGuinea pig bone marrow megakaryocytes were cultured on a type I rat tail collagen gel which stimulated proplatelet formation. Proplatelet formation was inhibited by monoclonal antibody LM609 to the alphav beta3 integrin (VnR), but not by monoclonal antibodies to the alpha5, alpha6, beta1, or IIb beta3(GPIIb–IIIa) integrin proteins. Megakaryocytes cultured on a plastic surface and stimulated with thrombin undergo a spreading and an adhesion reaction. This reaction is blocked in a dose‐dependent manner by the tetrapeptide RGDS and by the monoclonal antibody PG2 to the GPIIb–IIIa integrin, but not by the monoclonal antibody LM609 to the VnR. Immunoprecipitation and affinity chromatography experiments demonstrate that guinea pig megakaryocytes have distinct GPIIb–IIIa and VnR integrins with similar electrophoretic mobility. Spreading was significantly inhibited in a dose‐dependent fashion by drugs which elevate cellular cyclic AMP, including forskolin, dibutyryl cAMP, and isobutylmethylxanthine. In contrast to spreading, megakaryocyte proplatelet formation was stimulated by these agents in a dose‐dependent manner. Megakaryocyte spreading was stimulated by the protein kinase C (PKC) activator phorbol myristate acetate (PMA) and inhibited by the PKC inhibitors Calphostin C and K5720 in a dose‐dependent manner. PKC inhibitors did not inhibit megakaryocyte proplatelet formation. These results demonstrate that the closely related VnR and GPIIb‐IIIa integrins regulate different aspects of megakaryocyte morphological change and appear to be associated with different second messenger systems. © 1995 Wiley‐Liss, Inc.
Negative regulation of a special, double AP‐1 consensus element in the vimentin promoter: Interference by the retinoic acid receptor
Authors: Van De Klundert Francy A. J. M. , Jansen Hans J. , Bloemendal Hans 
Published: February 2005

AbstractThe growth‐regulated vimentin gene contains a functional double AP‐1 binding site formed by two nearly perfect inverted repeats. We present evidence for down‐regulation of vimentin expression by the retinoic acid receptor (RAR) in two mesodermally derived cell types. By mutation analysis we prove that the double consensus element is responsible for this negative regulation. From in vitro protein‐DNA interaction studies we conclude that AP‐1 binding is inhibited at RAR amounts required for occupation of the cognate RAR binding site in nuclear extracts from 3T3 cells and differentiated embryonal carcinoma cells. Furthermore, we show that, unlike in other cases, trans‐activation of the vimentin AP‐1 enhancer element can occur in undifferentiated embryonal carcinoma cells, despite the low amount of Jun and Fos proteins present in these cells. Here, however, down‐regulation by retinoic acid cannot be detected. © 1995 Wiley‐Liss, Inc.
Perturbation of the platelet‐derived growth factor receptor signaling by dibutyryl‐camp in human astrocytoma cells
Authors: Tsai Chon‐Haw , Hung Li‐Man , Chen Jan‐Kan 
Published: February 2005

AbstractIt has been shown that cAMP may perturb the polypeptide growth factor‐induced nuclear events. However, the possible interactions of the cAMP‐protein kinase A (cAMP‐PKA) and receptor tyrosine kinase pathways in the cytosol have not been fully elucidated. In this study, we use human astrocytoma cells as a model to investigate this issue. The results show that platelet‐derived growth factor (PDGF)‐induced receptor autophosphorylation in human astrocytoma cells is suppressed by dibutyryl‐cAMP pretreatment and such suppression is not due to changes in the ligand‐receptor binding properties. Further studies show that PDGF‐induced tyrosine phosphorylation of phospholipase C_γ1 (PLC_γ1) and phosphatidylinositol 3‐kinase (PI 3‐kinase) are also suppressed in dibutyryl‐cAMP‐pretreated cells. The suppression of PLC_γ1 tyrosine phosphorylation was accompanied by a decreased production of water soluble inositol phosphates. In contrast, similar treatment with normal human astrocytes potentiates the tyrosine phosphorylation of PLC_γ1 and PI 3‐kinase. The results indicate that cAMP can either negatively or positively modulate the PDGF receptor tyrosine kinase activity depending on the cell types examined. © 1995 Wiley‐Liss, Inc.
Thermotolerance and nuclear protein aggregation: Protection against initial damage or better recovery?
Authors: Stege G. J. J. , Brunsting J. F. , Kampinga H. H. , Konings A. W. T. 
Published: February 2005

AbstractHeat‐induced nuclear protein aggregation and subsequent disaggregation were measured in nonpreheated and preheated (thermotolerant) HeLa S3 cells. The effect of thermotolerance on the formation of and recovery from heat‐induced nuclear protein aggregates was related to the cellular levels of hsp27, hsp60, hsp70, hsc70, and hsp90. Cells heated at different time points after the thermotolerance trigger showed various levels of protection against heat‐induced nuclear protein aggregation. This protection, however, did not parallel the development and decay of thermotolerance on cell survival. The protection was maximal when the thermotolerance level already had started to decay. The level of protection against nuclear protein aggregation did however parallel the cellular level of hsp70 indicating that hsp70 may be involved in this process. At all stages during the development and decay, thermotolerant cells showed a more rapid recovery (disaggregation) from the heat‐induced nuclear protein aggregates than non‐thermotolerant cells. The rates of disaggregation during development and decay of thermotolerance paralleled the cellular levels of hsp27 suggesting that hsp27 is somehow involved in this recovery process from heat‐induced nuclear protein aggregates. The total cellular levels of none of the individual hsp's completely correlate with development and decay of thermotolerance, indicating that overexpression of any of these hsp's alone does not determine the level of thermotolerance. Clonogenic cell survival paralleled the rates of disaggregation, leading to the notion that recovery processes are the most important determinant for the thermotolerant state of HeLa S3 cells. The best corelation with clonogenic survival was found when both initial aggregation and subsequent disaggregation were taken into account, suggesting that the combined action of various hsp's in these two processes have to be included in thermotolerance development and decay. © 1995 Wiley‐Liss, Inc.
Identification of a chemotactic epitope in human transforming growth factor‐β1 spanning amino acid residues 368–374
Authors: Postlethwaite Arnold E. , Seyer Jerome M. 
Published: February 2005

AbstractTGF‐b̃1 plays a critical role in inflammatory and repair processes due in part to its ability to provide a potent chemotactic stimulus for inflammatory cells such as neutrophils and monocytes and for fibroblasts which initiate the fibrogenic response. In the present study, we have used synthetic oligopeptides representing the amino acid sequence of the 12.1 kDa monomer of human TGF‐b̃1 in an effort to identify a chemotactic epitope on the molecule. A seven residue peptide containing residues 368‐374, Val Tyr Tyr Val Gly Arg Lys, was demonstrated to be capable of inducing chemotactic migration of human peripheral blood neutrophils, monocytes, monocyte leukemia cell line THP‐1, and infant foreskin fibroblasts. Furthermore, larger peptides from the carboxy‐terminal portion of TGF‐b̃1 that contained residues 368–374 also induced migration of these cell types. None of the peptides representing the complete amino acid of TGF‐b̃1 monomer were able to compete with [125I]hrTGF‐b̃1 for binding to TGF‐b̃ cell surface receptors or fibroblasts or THP‐1 cells. Implications of these observations are discussed. © 1995 Wiley‐Liss, Inc.
Mast cells are potent regulators of endothelial cell adhesion molecule ICAM‐1 and VCAM‐1 expression
Authors: Meng Hong , Tonnesen Marcia G. , Marchese Mary J. , Clark Richard A. F. , Bahou Wadie F. , Gruber Barry L. 
Published: February 2005

AbstractTo investigate the possible role of mast cells (MC) in regulating leukocyte adhesion to vascular endothelial cells (EC), microvascular and macrovascular EC were exposed to activated MC or MC conditioned medium (MCCM). Expression of intercellular and vascular adhesion molecules (ICAM‐1 and VCAM‐1) on EC was monitored. Incubation of human dermal microvascular endothelial cells (HDMEC) and human umbilical vein endothelial cells (HUVEC) with activated MC or MCCM markedly increased ICAM‐1 and VCAM‐1 surface expression, noted as éarly as 4 hr. Maximal levels were observed at 16 hr followed by a general decline over 48 hr. A dose‐dependent response was noted using incremental dilutions of MCCM or by varying the number of MC in coculture with EC. At a ratio as low as 1:1,000 of MC:EC, increased ICAM‐1 was observed. The ICAM‐1 upregulation by MCCM was >90% neutralized by antibody to tumor necrosis factor alpha (TNF‐α), suggesting that MC release of this cytokine contributes significantly to inducing EC adhesiveness. VCAM‐1 expression enhanced by MCCM was partly neutralized (70%) by antibody to TNF‐α; thus other substances released by MC may contribute to VCAM‐1 expression. Northern blot analysis demonstrated MCCM upregulated ICAM‐1 and VCAM‐1 mRNA in both HDMEC and HUVEC. To evaluate the function of MCCM‐enhanced EC adhesion molecules, T cells isolated from normal human donors were used in a cell adhesion assay. T‐cell binding to EC was increased significantly after exposure of EC to MCCM, and inhibited by antibodies to ICAM‐1 or VCAM‐1. Intradermal injection of allergen in human atopic volunteers known to develop late‐phase allergic reactions led to marked expression of both ICAM‐1 and VCAM‐1 at 6 hr, as demonstrated by immunohistochemistry. These studies indicate that MC play a critical role in regulating the expression of EC adhesion molecules, ICAM‐1 and VCAM‐1, and thus augment inflammatory responses by upregulating leukocyte binding. © 1995 Wiley‐Liss Inc.
Inhibition of the arachidonic acid pathway prevents induction of IL‐8 mRNA by phorbol ester and changes the release of IL‐8 from HL 60 cells: Differential inhibition of induced expression of IL‐8, TNF‐α, IL‐1α, and IL‐1β
Authors: Meier R. W. , Niklaus G. , Dewald B. , Fey M. F. , Tobler A. 
Published: February 2005

AbstractThe promyelocytic HL 60 cell line can be used as an in vitro model system to study hematopoetic cell differentiation and inflammatory events. We studied the signal transduction pathway of induced interleukin (IL)‐8 expression and compared it with those of tumor necrosis factor alpha (TNF‐α), IL‐1α, and IL‐1β. The differentiation of HL 60 cells to macrophage‐like cells by PMA resulted in a rapid and marked induction of these inflammatory cytokines. The up‐regulation occurred in the absence of ongoing protein synthesis, but cycloneximide‐sensitive gene products modulated their induction kinetics. Staurosporine, a potent inhibitor of protein kinases, strongly inhibited their gene expression. Phosphorylation may not act directly on latent transcription factors, since bromophenacyl bromide, an inhibitor for the release of arachidonic acid from phorbol‐12 myristate 13‐acetate (PMA)‐stimulated HL 60 cells, markedly depressed the induced mRNAs for IL‐8, TNF‐α, and IL‐1α and ‐β. Similarly, 5,8,11,14 eicosatetraynoic acid (ETYA), another inhibitor of the arachidonic acid pathway, blocked the induction of transcripts for TNF‐α, and both IL‐1 genes in phorbol ester‐stimulated HL 60 cells. In contrast, ETYA increased the induced IL‐8 RNA levels and stimulated the release for IL‐8. Also, ketoconazole, an inhibitor of 5‐lipoxygenase and indomethacin, an inhibitor of cyclooxygenases did not block the induction of IL‐8 mRNA. However, the release of IL‐8 protein was regulated by indomethacin and ketoconazole. Our results indicate that arachidonic acid metabolites are mediators in the signal transduction pathway of IL‐8 expression and that the involved second messengers are different from those which are important for the induction of TNF‐α and IL‐1β expression. © 1995 Wiley‐Liss Inc.
Ca2+ influx, phosphoinositide hydrolysis, and histamine release induced by lysophosphatidylserine in mast cells
Authors: Lloret Sergio , Moreno Juan Jose 
Published: February 2005

AbstractWe have previously demonstrated that snake venom phospholipases A2 (PLA2s) and mammalian PLA2s induced inflammatory processes. This effect was correlated with the activity of the enzymes and the release of lipid mediators. We have now determined the role of lysophosphatidylserine (LysoPS) as an inflammatory lipid mediator. Thus, we have studied the possibility that intracellular calcium concentration, phosphoinositide hydrolysis, and the subsequent histamine release in mast cells is due to the action of lysophosphatidylserine. Lysophosphatidylserine‐stimulated release of histamine was significantly higher than release by other lysophospholipids. The contribution of increased phospholipase C activity and the intracellular Ca2+ influx were therefore examined. LysoPS increased mast cell calcium concentration, and this increment was associated with phospholipase C activation and release of inositol phosphates. The increase in intracellular calucium and histamine degranulation induced by LysoPS were inhibited by apomorphine. Pretreatment of mast cells with pertussis toxin decreased the secretagogic effect of LysoPS and compound 48/80 without modifying the effect of the ionophore A23187. These results suggest that pertussis toxinsensitive G‐protein might be involved in the mast cell degranulation produced by lysophosphatidylserine and allow the increase in phospholipase C activity, thus enhancing intracellular calcium concentration, which then induces exocytosis of histamine. © 1995 Wiley‐Liss Inc.
Effect of 1,25‐dihydroxyvitamin D3 on induction of scavenger receptor and differentiation of 12‐O‐tetradecanoylphorbol‐13‐acetate‐treated THP‐1 human monocyte like cells
Authors: Suematsu Yuji , Nishizawa Yoshiki , Shioi Atsushi , Hino Masayuki , Tahara Hideki , Inaba Masaaki , Morii Hirotoshi , Otani Shuzo 
Published: February 2005

AbstractWe investigated the effect of 1,25‐dihydroxyvitamin D3 (1,25(OH)2D3) on the expression of scavenger receptors in human monocytic cell line (THP‐1 cells) treated for 24 h with 12‐O‐tetradecanoylphorbol‐13‐acetate (TPA) which induces their differentiation into macrophages. The capacity to degrade 125I‐labeled acetyl low density lipoprotein (LDL) was developed in accordance with macrophage differentiation. The treatment with 10 nM 1,25(OH)2D3 for 72 h inhibited the degradation of acetyl LDL by THP‐1 macrophages in a dose‐dependent manner, suggesting that 1,25(OH)2D3 inhibits scavenging function in macrophages. In order to clarify the mechanism of its inhibitory effect on degradation of acetyl LDL, we performed the ligand binding assay using 125I‐labeled acetyl LDL. Scatchard analysis revealed that 1,25(OH)2D3 decreased the number of scavenger receptors without changing the affinity for acetyl LDL. We next examined the effect of 1,25(OH)2D3 on the expression of scavenger receptor mRNA. The mRNA of type I scavenger receptor was first detected in THP‐1 cells 4 days after the treatment with TPA, the mRNA level increased up to 6 days, and then decreased. The treatment with 1,25(OH)2D3 for 72 h dramatically decreased the mRNA levels after the acquisition of macrophage phenotypes as evidenced by nonspecific esterase staining. However, 1,25(OH)2D3 did not affect the activity of non‐specific esterase nor the induction of interleukin‐1β mRNA by lipopolysaccharide in THP‐1 macrophages. These findings suggest that 1,25(OH)2D3 exclusively decreases the expression of scavenger receptors in TPA‐induced THP‐1 macrophages without affecting the basic cellular functions as macrophages. © 1995 Wiley‐Liss Inc.
Differential gene expression in migrating renal epithelial cells after wounding
Authors: Pawar Shashi , Kartha Sreedharan , Toback F. Gary 
Published: February 2005

AbstractAn in vitro model of wound healing was used to study cell migration that is independent of proliferation during renal regeneration after acute tubular necrosis. Monolayer cultures of high‐density, quiescent renal epithelial cells of the BSC‐1 line were subjected to scrape wounding and then Northern blot analysis was employed to identify genes that mediate cell migration. After wounding the monolayer, there is maximal induction of the immediate‐early genes Egr‐1, c‐fos, NAK‐1, and gro at 1 hour, followed by peak induction of connective tissue growth factor (CTGF) and c‐myc at 4 hours. Message levels of urokinase‐type plasminogen activator (u‐PA) and its inhibitor (PAI‐1) and heat shock protein (HSP)‐70 are markedly raised 4–8 hours after wounding. Constitutive expression is repressed at 1 hour for transcripts that encode receptors for fibronectin (FN), epidermal growth factor, and hepatocyte growth factor (c‐met), and the secreted proteins FN and osteopontin. Expression of genes encoding transforming growth factor (TGF)‐β2, retinoic acid receptor α, int‐1, int‐2, and gap junction protein which can play a role in cell movement, appeared unchanged after wounding. Differential expression of genes was a function of cell location relative to the wound; NAK‐1, PAI‐1, and HSP‐70 were induced or stimulated only in cells at the wound edge, u‐PA was stimulated in cells away from the wound, and CTGF was induced in each of these populations suggesting that cell‐to‐cell communication may regulate gene expression after wounding. Adenosine diphosphate, a potent stimulator of cell migration which enhances expression of u‐PA and PAI‐1 in nonwounded cultures, additively stimulates these genes after wounding and may thereby potentiate wound healing. Thus scrape wounding of renal epithelial cells is followed by induction, stimulation, or repression of specific genes with distinct responses in different populations of cells. © 1995 Wiley‐Liss Inc.