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Platelet-derived Growth Factor (platelet-derived + growth_factor)
Terms modified by Platelet-derived Growth Factor Selected AbstractsPlatelet-derived growth factor receptors expressed in response to injury of differentiated vascular smooth muscle in vitro: effects on Ca2+ and growth signalsACTA PHYSIOLOGICA, Issue 2 2001A. Lindqvist Vascular smooth muscle cells (VSMCs) in the intact vascular wall are differentiated for contraction, whereas the response to vascular injury involves transition towards a synthetic phenotype, with increased tendency for proliferation. Platelet-derived growth factor (PDGF) is thought to be important for this process. We investigated expression and functional coupling of PDGF receptors (PDGFRs) , and , in rat tail arterial rings kept in organ culture, in order to capture early events in the phenotypic transition. In freshly dissected rings no PDGFR immunoreactivity was found in medial VSMCs, whereas PDGFR , was detected in nerve fibres. After organ culture for 1,4 days PDGFR , and , as well as phospholipase C,2 (PLC,2), known to couple to PDGFR, were expressed in VSMCs within 100 ,m of the cut ends. Calponin, a marker for the contractile phenotype, was decreased near the injured area, suggesting that cells were in transition towards synthetic phenotype. In these cells, which showed functional Ca2+ -release from the sarcoplasmic reticulum, PDGF-AB (100 ng mL,1) had no effect on [Ca2+]i, whereas cultured VSMCs obtained from explants of rat tail arterial rings responded to PDGF-AB with an increase in [Ca2+]i. However, PDGFR within the cultured rings coupled to growth signalling pathways, as PDGF-AB caused a tyrphostin AG1295-sensitive activation of extracellular signal-regulated kinases 1 and 2 and of [3H]-thymidine incorporation. Thus, early expression of PDGFR in VSMC adjacent to sites of vascular injury coincides with signs of dedifferentiation. These receptors couple to growth signalling, but do not activate intracellular Ca2+ release. [source] Platelet-derived growth factor is involved in the differentiation of second heart field-derived cardiac structures in chicken embryosDEVELOPMENTAL DYNAMICS, Issue 10 2009Noortje A.M. Bax Abstract For the establishment of a fully functional septated heart, addition of myocardium from second heart field-derived structures is important. Platelet-derived growth factors (PDGFs) are known for their role in cardiovascular development. In this study, we aim to elucidate this role of PDGF-A, PDGF-C, and their receptor PDGFR-,. We analyzed the expression patterns of PDGF-A, -C, and their receptor PDGFR-, during avian heart development. A spatiotemporal pattern of ligands was seen with colocalization of the PDGFR-,. This was found in second heart field-derived myocardium as well as the proepicardial organ (PEO) and epicardium. Mechanical inhibition of epicardial outgrowth as well as chemical disturbance of PDGFR-, support a functional role of the ligands and the receptor in cardiac development. Developmental Dynamics 238:2658,2669, 2009. © 2009 Wiley-Liss, Inc. [source] Platelet-derived growth factor (PDGF) in human acute myelogenous leukemia: PDGF receptor expression, endogenous PDGF release and responsiveness to exogenous PDGF isoforms by in vitro cultured acute myelogenous leukemia blastsEUROPEAN JOURNAL OF HAEMATOLOGY, Issue 6 2001Brynjar Foss Abstract: We investigated effects of Platelet-derived growth factor (PDGF) and Platelet factor 4 (PF-4) on the functional characteristics of native, human acute myelogenous leukemia (AML) blasts. AML blast expression of the PDGF-receptor ,-chain was detected for a subset of patients (45%), whereas PDGF-receptor ,-chain expression was detected for most patients (90%). Constitutive AML blast release of the PDGF-AB isoform (the major form also derived from normal platelets) was detected for 43% of patients, whereas PDGF-BB release was not detected for any patient. The PDGF isoforms AA, AB and BB had dose-dependent and divergent effects on spontaneous and cytokine-dependent AML blast proliferation, whereas for constitutive cytokine secretion (IL-1,, IL-6, TNF-,) inhibitory effects were rare and all three isoforms usually had no effect or enhanced the constitutive secretion. The PDGF effects were caused by a direct effect on the AML blasts and were not dependent on the presence of serum. The PDGF effects could also be detected after in vitro culture of AML cells in the presence of IL-4+granulocyte-macrophage colony stimulating factor. PF-4 had divergent effects on proliferation and cytokine secretion by native AML blasts. Our results suggest that exogenous (e.g. platelet-secreted) PDGF and PF-4 can function as regulators of leukemic hematopoiesis and possibly also modulate the function of residual AML cells in peripheral blood stem cell grafts. On the other hand, endogenous release of PDGF-AB by native blasts may modulate the function of normal cells in the bone marrow microenvironment (e.g. bone marrow stromal cells). [source] PDGF stimulates the massive expansion of glial progenitors in the neonatal forebrainGLIA, Issue 16 2009M. C. Assanah Abstract Platelet-derived growth factor (PDGF) plays a major role in regulating migration, proliferation, and differentiation of glial progenitors during normal brain development and in the abnormal proliferation and dispersion that drives the formation of malignant gliomas. To further explore the relationship between PDGF's effects on normal glial progenitors and its role in the formation of gliomas, we infected progenitor cells in the subventricular zone (SVZ) of the lateral ventricle of neonatal rat pups with a retrovirus that expresses PDGF and green fluorescent protein (GFP). At 3 days post-injection (dpi), a proliferation of PDGFR,+ progenitors was seen in the SVZ and white matter around the injection site and by 10 dpi the animals had large diffusely infiltrating tumors that resembled glioblastomas. The tumors contained a massive proliferation of both infected and uninfected PDGFR,+ progenitors, suggesting that PDGF was driving tumor formation via both autocrine and paracrine signaling. Rats co-injected with two retroviruses (one that expresses PDGF-IRES-DSRED and one that expresses only GFP) formed tumors that contained a mixture of DSRED+ cells (PDGF producers) and GFP+ cells (recruited progenitors). Time-lapse microscopy of slice cultures confirmed that both DSRED+ and GFP+ cells were highly migratory and proliferative. Furthermore, adding exogenous PDGF to slice cultures generated from nontumor-bearing brains (injected with control GFP retrovirus only) stimulated the migration and proliferation of GFP+ progenitors. These findings reveal the inherent growth factor responsiveness and tumorigenic potential of PDGFR,+ progenitors and highlight the importance of paracrine signaling in stimulating glioma growth and infiltration. © 2009 Wiley-Liss, Inc. [source] Different mechanisms influencing permeation of PDGF-AA and PDGF-BB across the blood,brain barrierJOURNAL OF NEUROCHEMISTRY, Issue 1 2003Abba J. Kastin Abstract Platelet-derived growth factor (PDGF) exerts neurotrophic and neuromodulatory effects on the CNS. To determine the permeability of the blood,brain barrier (BBB) to PDGF, we examined the blood-to-brain influx of radioactively labeled PDGF isoforms (PDGF-AA and PDGF-BB) by multiple-time regression analysis after intravenous (i.v.) injection and by in-situ perfusion, and also determined the physicochemical characteristics which affect their permeation across the BBB, including lipophilicity (measured by octanol:buffer partition coefficient), hydrogen bonding (measured by differences in octanol : buffer and isooctane : buffer partition coefficients), serum protein binding (measured by capillary electrophoresis), and stability of PDGF in blood 10 min after i.v. injection (measured by HPLC). After i.v. bolus injection, neither 125I-PDGF-AA nor 125I-PDGF-BB crossed the BBB, their influx rates being similar to that of the vascular marker 99mTc-albumin. 125I-PDGF-AA degraded significantly faster in blood than 125I-PDGF-BB. PDGF-BB, however, was completely bound to a large protein in serum whereas PDGF-AA showed no binding. Thus, degradation might explain the poor blood-to-brain influx of PDGF-AA, whereas protein binding could explain the poor influx of circulating PDGF-BB. Despite their lack of permeation in the intact mouse, both 125I-PDGF-AA and 125I-PDGF-BB entered the brain by perfusion in blood-free buffer, and the significantly faster rate of 125I-PDGF-AA than 125I-PDGF-BB may be explained by the lower hydrogen bonding potential of 125I-PDGF-AA. Thus, the lack of significant distribution of PDGF from blood to brain is not because of the intrinsic barrier function of the BBB but probably because of degradation and protein binding. Information from these studies could be useful in the design of analogues for delivery of PDGF as a therapeutic agent. [source] Activation of human platelet-rich plasmas: effect on growth factors release, cell division and in vivo bone formationCLINICAL ORAL IMPLANTS RESEARCH, Issue 5 2007Yanik Roussy Abstract Objectives: Aims of this controlled study were to determine the effects of activated human platelet-rich plasmas (PRPs) on early and mature bone formation in vivo, and to characterize the effect of PRP activation on growth factors release and endothelial cell division in vitro. Material and methods: PRPs were prepared from four volunteers with the platelet concentrate collector system (PCCS) system and activated with three concentrations of calcium and thrombin. Platelet-derived growth factor (PDGF)-BB, vascular endothelial growth factor (VEGF), transforming growth factor , (TGF-,) and interleukin-1, (IL-1,) levels released in supernatants were measured by ELISA, at time 0, 1h, 24h and 6 days following PRP activation. Mitogenic potential of PRP supernatants were tested on endothelial cells in vitro, and the effects of activated human PRPs on bone formation in vivo were measured in athymic rats by micro-CT analyses. Results: Activation of PRPs with calcium and thrombin triggered an immediate release of VEGF, PDGF-BB and TGF-, and a delayed release of IL-1, in PRP supernatants. Higher endothelial cell division was observed with supernatants from activated PRPs than from non-activated PRPs. Positive correlations were observed between VEGF levels and endothelial cell division and bone formation. A negative correlation was also found between PDGF-BB concentration and bone formation. However, early and mature bone formations with activated PRPs did not significantly differ from the ones obtained in the control group. Conclusions: Activation of PRPs with calcium and thrombin regulates growth factors release and endothelial cell division in vitro. However, activated PRPs does not improve the early or mature bone formations in vivo in this athymic rat model. [source] Platelet-derived growth factor is involved in the differentiation of second heart field-derived cardiac structures in chicken embryosDEVELOPMENTAL DYNAMICS, Issue 10 2009Noortje A.M. Bax Abstract For the establishment of a fully functional septated heart, addition of myocardium from second heart field-derived structures is important. Platelet-derived growth factors (PDGFs) are known for their role in cardiovascular development. In this study, we aim to elucidate this role of PDGF-A, PDGF-C, and their receptor PDGFR-,. We analyzed the expression patterns of PDGF-A, -C, and their receptor PDGFR-, during avian heart development. A spatiotemporal pattern of ligands was seen with colocalization of the PDGFR-,. This was found in second heart field-derived myocardium as well as the proepicardial organ (PEO) and epicardium. Mechanical inhibition of epicardial outgrowth as well as chemical disturbance of PDGFR-, support a functional role of the ligands and the receptor in cardiac development. Developmental Dynamics 238:2658,2669, 2009. © 2009 Wiley-Liss, Inc. [source] Platelet-derived growth factors in the developing avian heart and maturating coronary vasculatureDEVELOPMENTAL DYNAMICS, Issue 4 2005Nynke M.S. Abstract Platelet-derived growth factors (PDGFs) are important in embryonic development. To elucidate their role in avian heart and coronary development, we investigated protein expression patterns of PDGF-A, PDGF-B, and the receptors PDGFR-, and PDGFR-, using immunohistochemistry on sections of pro-epicardial quail,chicken chimeras of Hamburger and Hamilton (HH) 28,HH35. PDGF-A and PDGFR-, were expressed in the atrial septum, sinus venosus, and throughout the myocardium, with PDGFR-, retreating to the trabeculae at later stages. Additionally, PDGF-A and PDGFR-, were present in outflow tract cushion mesenchyme and myocardium, respectively. Small cardiac nerves and (sub)epicardial cells expressed PDGF-B and PDGFR-,. Furthermore, endothelial cells expressed PDGF-B, while vascular smooth muscle cells and interstitial epicardium-derived cells expressed PDGFR-,, indicating a role in coronary maturation. PDGF-B is also present in ventricular septal development, in the absence of any PDGFR. Epicardium-derived cells in the atrioventricular cushions expressed PDGFR-,. We conclude that all four proteins are involved in myocardial development, whereas PDGF-B and PDGFR-, are specifically important in coronary maturation. Developmental Dynamics 233:1579,1588, 2005. © 2005 Wiley-Liss, Inc. [source] Keratinocyte growth factor and scatter factor expression by regionally defined oral fibroblastsEUROPEAN JOURNAL OF ORAL SCIENCES, Issue 1 2003Scott Thomas William McKeown Keratinocyte growth factor (KGF) and hepatocyte growth factor/scatter factor (SF) are two signalling molecules thought to play important roles in regulating epithelial,mesenchymal interactions. Expression of both factors by fibroblasts in subepithelial connective tissue may play a role in maintaining epithelial integrity in health and in the apical migration of junctional epithelium in periodontitis. The aims of this study were (a) to compare expression levels of KGF and SF by periodontal ligament (PDL) and gingival fibroblasts; and (ii) to determine the effects of interleukin (IL)-1,, transforming growth factor (TGF)-,1, platelet-derived growth factor (PDGF)-BB and epidermal growth factor (EGF) on KGF/SF expression by these cell populations. Three paired PDL and gingival fibroblast strains were developed. The KGF and SF protein levels were analysed by enzyme-linked immunosorbent assay. Relative levels of KGF and SF mRNA in cytokine-treated cultures were determined using semiquantitative reverse transcriptase polymerase chain reaction. No differences in the levels of KGF and SF produced by PDL and gingival (SOG) populations were found. In both cell types IL-1, stimulated KGF and SF expression, while TGF-,1 significantly inhibited expression at both the mRNA and protein levels. Epidermal growth factor and PDGF-BB induced differing effects on expression, stimulating SF protein production but inhibiting KGF output in both fibroblast populations. Differences in response to EGF and PDGF were also seen between paired PDL and gingival fibroblasts. [source] Quantitative analysis of the synthesis and secretion of type VII collagen in cultured human dermal fibroblasts with a sensitive sandwich enzyme-linked immunoassayEXPERIMENTAL DERMATOLOGY, Issue 2 2007Satoshi Amano Abstract:, Type VII collagen is the major component of anchoring fibrils in the epidermal basement membrane. Its expression has been analyzed by immunostaining or Northern blotting, but rarely at the protein level. In this study, we have quantitatively examined the effects of ascorbic acid and various cytokines/growth factors on the protein synthesis and secretion of type VII collagen by human dermal fibroblasts in culture, using a developed, highly sensitive sandwich enzyme-linked immunoassay with two kinds of specific monoclonal antibodies against the non-collagenous domain-1. Ascorbic acid and its derivative induced a twofold increase in type VII collagen synthesis, and markedly increased the secretion of type VII collagen into the medium when compared with the control culture. This effect was not influenced by the presence of transforming growth factor- ,1 (TGF- ,1). The synthesis of type VII collagen was elevated by TGF- ,1, platelet-derived growth factor, tumor necrosis factor- ,, and interleukin-1,, but not by TGF- ,. Thus, our data indicate that the synthesis and secretion of type VII collagen in human dermal fibroblasts are regulated by ascorbate and the enhancement of type VII collagen gene expression by cytokines/growth factors is accompanied with elevated production of type VII collagen at the protein level. [source] An FGF-responsive astrocyte precursor isolated from the neonatal forebrainGLIA, Issue 6 2009Grace Lin Abstract Gliogenesis in the mammalian CNS continues after birth, with astrocytes being generated well into the first two postnatal weeks. In this study, we have isolated an A2B5+ astrocyte precursor (APC) from the postnatal rat forebrain, which is capable of differentiating into mature astrocytes in serum-free medium without further trophic support. Exposure to basic fibroblast growth factor (bFGF) selectively induces the APCs to proliferate, forming clusters of vimentin+ cells, which, within 2 weeks, differentiate into GFAP+ astrocytes. While bFGF functions as a potent mitogen, neither is it necessary to induce or maintain astrocyte differentiation, nor is it capable of maintaining the precursors in an immature, proliferative state. APCs exit the cell cycle and differentiate, even in the continued presence of fibroblast growth factor alone or in combination with other mitogenic factors such as platelet-derived growth factor. Under the culture conditions used, it was not possible to cause the astrocytes to re-enter cell cycle. After transplantation into the neonatal forebrain, APCs differentiated exclusively into astrocytes, regardless of brain region. Initially distributed widely within the forebrain, the precursors are most greatly concentrated within the subventricular zone (SVZ) and subcortical white matter, where they are maintained throughout postnatal development. APCs can be isolated from the SVZ and white matter of animals as late as 4 weeks after birth. © 2008 Wiley-Liss, Inc. [source] Cell adhesion regulates platelet-derived growth factor,induced MAP kinase and PI-3 kinase activation in stellate cellsHEPATOLOGY, Issue 3 2002Vinicio Carloni The biologic effects of growth factors are dependent on cell adhesion, and a cross talk occurs between growth factors and adhesion complexes. The aim of the present study was to evaluate the influence of cell adhesion on the major intracellular signaling pathways elicited by platelet-derived growth factor (PDGF) in hepatic stellate cells (HSC). PDGF signaling was investigated in an experimental condition characterized by lack of cell adhesion for different intervals of time. Basal and PDGF-induced focal adhesion kinase (FAK) tyrosine phosphorylation was maintained in a condition of cell suspension for 2, 4, and 6 hours, whereas it was completely lost after 12 and 24 hours. We examined MAP kinase activity at 2 and 24 hours, corresponding to the higher and lower levels of FAK phosphorylation. In these experiments, MAP kinase activity correlated with FAK phosphorylation. Stimulation with PDGF was able to cause Ras-GTP loading only in adherent cells. The ability of PDGF to induce phosphatidylinositol 3-kinase (PI 3-K) activity was abrogated in cells maintained in suspension. The Ser473 phosphorylation of Akt was only marginally affected by the lack of cell adhesion. We then evaluated the association of FAK with c-Src. This association was found to be cell adhesion dependent, and it did not appear to be dependent from phosphorylated FAK. These changes in PDGF-induced intracellular signaling were associated with a remarkable reduction of PDGF-proliferative potential in nonadherent cells, although no marked differences in the apoptotic rate were observed. In conclusion, these results suggest that cell adhesion differentially regulates major signaling pathways activated by PDGF in HSC. [source] Inhibition of hepatic stellate cell proliferation and activation by the semisynthetic analogue of fumagillin TNP-470 in ratsHEPATOLOGY, Issue 5 2000Yan Qing Wang Proliferation and activation of hepatic stellate cells (HSCs) are critical steps for the development of postnecrotic fibrosis in the liver. The present study aimed to reveal the inhibitory effect of the semisynthetic analogue of fumagillin TNP-470 on these events for its possible use as an antifibrogenic agent. Rat models of carbon tetrachloride (CCl4)- and dimethylnitrosamine-induced hepatic fibrosis were used for an in vivo study. In both models, the fibrotic area was considerably decreased by concurrent repetitive subcutaneous injections of 30 mg/kg body weight of TNP-470. In CCl4 -induced fibrosis, factor VIII-related antigen-positive blood vessels, desmin-, or ,-smooth muscle actin (,SMA)-positive mesenchymal cells, bromodeoxyuridine (BrdU)-positive mesenchymal cells also decreased in number by treatment with TNP-470. In in vitro experiments, a supplement of 1,000 ng/mL TNP-470 suppressed BrdU incorporation and cyclins D1, D2, and E expression by cultured HSCs in the absence and/or presence of platelet-derived growth factor (PDGF). Expression of HSC activation markers, i.e., ,SMA and PDGF receptor ,, was also suppressed. The present results indicate that TNP-470 inhibits HSC proliferation by blocking the cell-cycle transition from G1 to S and HSC activation, and, as the consequence, prevents the progression of hepatic fibrosis, probably being coupled with its antiangiogenic effect. [source] Hypoxia-inducible factor-dependent production of profibrotic mediators by hypoxic Kupffer cellsHEPATOLOGY RESEARCH, Issue 5 2010Bryan L. Copple Aim:, Liver fibrosis develops when chronic liver injury stimulates cells in the liver to produce mediators that activate hepatic stellate cells and stimulate them to secrete collagen. Recent studies suggest that the hypoxia-regulated transcription factor, hypoxia-inducible factor-1,, is essential for upregulation of profibrotic mediators, such as platelet-derived growth factor, in the liver during the development of liver fibrosis. What remains unknown, however, is the cell type-specific regulation of profibrotic mediators by hypoxia-inducible factors. Accordingly, in the present study the hypothesis tested was that hypoxia-inducible factors regulate production of profibrotic mediators by hypoxic Kupffer cells. Methods:, Kupffer cells were isolated from control mice and hypoxia-inducible factor-1,-deficient mice and exposed to room air or 1% oxygen (i.e. hypoxia). Levels of profibrotic mediators were quantified by real-time polymerase chain reaction. Results:, Exposure of Kupffer cells isolated from control mice to 1% oxygen activated hypoxia-inducible factor-1,, and increased mRNA levels of platelet-derived growth factor-B, vascular endothelial growth factor, angiopoietin-1 and monocyte chemotactic protein-1. Upregulation of all of these mediators by hypoxia was prevented in Kupffer cells isolated from hypoxia-inducible factor-1,-deficient mice. Conclusion:, Results from these studies suggest that hypoxia-inducible factors are critical regulators of profibrotic mediator production by hypoxic Kupffer cells. [source] Stromal MCP-1 in mammary tumors induces tumor-associated macrophage infiltration and contributes to tumor progressionINTERNATIONAL JOURNAL OF CANCER, Issue 6 2009Hiroshi Fujimoto Abstract There is growing evidence that tumor-associated macrophages (TAMs) promote tumor growth and dissemination. Many individual reports have focused on the protumor function of molecules linked to the recruitment of macrophages, but little is known about which factor has the strongest impact on recruitment of macrophages in breast cancer. To elucidate this question, we performed RT-PCR using species-specific primers and evaluated tumoral and stromal mRNA expression of macrophage chemoattractants separately in human breast tumor xenografts. The correlation between the tumoral or stromal chemoattractant mRNA expression including monocyte chemoattractant protein-1 (MCP-1) (CCL2), MIP-1, (CCL3), RANTES (CCL5), colony-stimulating factor 1, tumor necrosis factor ,, platelet-derived growth factor (PDGF)-BB and macrophage infiltration were compared. There was significant positive correlation between stromal MCP-1 expression and macrophage number (r = 0.63), and negative correlation between tumoral RANTES expression and macrophage number (r = ,0.75). However, no significant correlation was found for the other tumoral and stromal factors. The interaction between the tumor cells and macrophages was also investigated. Tumor cell,macrophage interactions augmented macrophage-derived MCP-1 mRNA expression and macrophage chemotactic activity in vitro. Treatment of immunodeficient mice bearing human breast cancer cells with a neutralizing antibody to MCP-1 resulted in significant decrease of macrophage infiltration, angiogenetic activity and tumor growth. Furthermore, immunohistochemical analysis of human breast cancer tissue showed stromal MCP-1 had a significant correlation with relapse free survival (p = 0.029), but tumoral MCP-1 did not (p = 0.105). These findings indicate that stromal MCP-1 produced as a result of tumor,stromal interactions may be important for the progression of human breast cancer and macrophages may play an important role in this tumor,stroma interaction. © 2009 UICC. [source] Growth factors in periodontal regenerationINTERNATIONAL JOURNAL OF DENTAL HYGIENE, Issue 2 2009S Raja Abstract:, Inflammatory periodontal disease is an almost ubiquitous disorder in the adult population. Cases or sites with moderate to advanced disease often continue to show signs of inflammation after non-surgical approach. Our current understanding of periodontal healing is based on a hypothesis by Melcher who proposed that the cell type that repopulates the exposed root surface at the periodontal repair site will define the nature of the attachment/repair that take place. If mesenchymal cells from periodontal ligament/perivascular region of the bone proliferate and colonize the root surface, regeneration occurs. Growth factors are natural cell products that are released or activated when cell division is needed. This action typically occurs during such events as wound healing or tissue regeneration. Activated platelets at the wound margins release several growth factors such as platelet-derived growth factor (PDGF), transforming growth factor (TGF)-,, epidermal growth factor etc. Cells adjacent to the injured site also are induced to release growth factors such as insulin-like growth factor-I, PDGF, TGF-, and TGF-, within a few hours after injury. In periodontal regeneration, the coronal re-establishment of the periodontal ligament (PDL) is required together with corresponding cementum and supporting alveolar bone. Thus, agents which promote periodontal ligament fibroblast (PLF) proliferation and migration as well as collagen biosynthesis would appear to be mediators for enhancing new PDL formation. When combinations or cocktails of different factors are used, greater repair is achieved than when individual factors are applied. [source] Differential upregulation of Nox homologues of NADPH oxidase by tumor necrosis factor-, in human aortic smooth muscle and embryonic kidney cellsJOURNAL OF CELLULAR AND MOLECULAR MEDICINE, Issue 1 2006K. T. Moe Abstract NADPH oxidases are important sources of vascular superoxide, which has been linked to the pathogenesis of atherosclerosis. Previously we demonstrated that the Nox4 subunit of NADPH oxidase is a critical catalytic component for superoxide production in quiescent vascular smooth muscle cells. In this study we sought to determine the role of Nox4 in superoxide production in human aortic smooth muscle cells (AoSMC) and embryonic kidney (HEK293) cells under proinflammatory conditions. Incubation with tumor necrosis factor-, (TNF-,, 10 ng/ml) for 12h increased superoxide production in both cell types, whereas angiotensin II, platelet-derived growth factor or interleukin-1, had little effects. Superoxide production was completely abolished by the NADPH oxidase inhibitors diphenyline iodonium and apocynin, but not by inhibitors of xanthine oxidase, nitric oxide synthase or mitochondrial electron transport. TNF-, upregulated the expression of Nox4 in AoSMC at both message and protein levels, while Nox1 and Nox2 were unchanged. In contrast, upregulation of Nox2 appeared to mediate the enhanced superoxide production by TNF-, in HEK293 cells. We suggest that Nox4 may be involved in increased superoxide generation in vascular smooth muscle cells under proinflammatory conditions. [source] To go or not to go: Migration of human mesenchymal progenitor cells stimulated by isoforms of PDGFJOURNAL OF CELLULAR BIOCHEMISTRY, Issue 5 2004Jörg Fiedler Abstract The recruitment of mesenchymal progenitor cells (MPCs) and their subsequent differentiation to osteoblasts is mandatory for bone development, remodeling, and repair. To study the possible involvement of platelet-derived growth factor (PDGF) isoforms, primary human MPCs and osteogenic differentiated progenitor cells (dOB) were examined for chemotaxic response to homodimeric human platelet-derived growth factor AA, -BB, and heterodimeric PDGF-AB. The role of PDGF receptors was addressed by preincubation with PDGF receptor alpha and beta chain specific antibodies. Migration of MPCs, dOB, and primary osteoblasts (OB) was stimulated by the addition of rhPDGF-AA, rhPDGF-BB, and rhPDGF-AB. The effect was highest in MPCs and for rhPDGF-BB, and declining with osteogenic differentiation. Preincubation with the receptor alpha specific antibody decreased the CI to borderline values while pretreatment with the receptor beta specific antibody led to a complete loss of chemotactic response to PDGF isoforms. In control experiments, basal migration values and rhBMP-2 as well as rxBMP-4 induced chemotaxis of MPC were not influenced by the addition of receptor alpha or beta antibodies. Interestingly, without preincubation the parallel exposure of MPC to rhTGF-,1 instantaneously leads to a selective loss of migratory stimulation by rhPDGF-AA. The chemotactic effect of PDGF isoforms for primary human MPCs and the influence of osteogenic differentiation suggest a functional role for recruitment of MPCs during bone development and remodeling. Moreover, these observations may be useful for novel approaches towards guided tissue regeneration or tissue engineering of bone. © 2004 Wiley-Liss, Inc. [source] Differential regulation of platelet-derived growth factor stimulated migration and proliferation in osteoblastic cells,JOURNAL OF CELLULAR BIOCHEMISTRY, Issue 4 2004Meenal Mehrotra Abstract Osteoblastic migration and proliferation in response to growth factors are essential for skeletal development, bone remodeling, and fracture repair, as well as pathologic processes, such as metastasis. We studied migration in response to platelet-derived growth factor (PDGF, 10 ng/ml) in a wounding model. PDGF stimulated a twofold increase in migration of osteoblastic MC3T3-E1 cells and murine calvarial osteoblasts over 24,48 h. PDGF also stimulated a tenfold increase in 3H-thymidine (3H-TdR) incorporation in MC3T3-E1 cells. Migration and DNA replication, as measured by BrdU incorporation, could be stimulated in the same cell. Blocking DNA replication with aphidicolin did not reduce the distance migrated. To examine the role of mitogen-activated protein (MAP) kinases in migration and proliferation, we used specific inhibitors of p38 MAP kinase, extracellular signal regulated kinase (ERK), and c-Jun N-terminal kinase (JNK). For these signaling studies, proliferation was measured by carboxyfluorescein diacetate succinimidyl ester (CFSE) using flow cytometry. Inhibition of the p38 MAP kinase pathway by SB203580 and SB202190 blocked PDGF-stimulated migration but had no effect on proliferation. Inhibition of the ERK pathway by PD98059 and U0126 inhibited proliferation but did not inhibit migration. Inhibition of JNK activity by SP600125 inhibited both migration and proliferation. Hence, the stimulation of migration and proliferation by PDGF occurred by both overlapping and independent pathways. The JNK pathway was involved in both migration and proliferation, whereas the p38 pathway was predominantly involved in migration and the ERK pathway predominantly involved in proliferation. © 2004 Wiley-Liss, Inc. [source] Emerging targets and novel strategies in the treatment of AIDS-related Kaposi's sarcoma: Bidirectional translational scienceJOURNAL OF CELLULAR PHYSIOLOGY, Issue 3 2006Bruce J. Dezube Through the mentorship process, Dr. Arthur Pardee emphasized the critical importance of bidirectional translational research,not only advancing drug development from bench to bedside, but also bringing back precious clinical material to the laboratory to assess the biologic effects of therapeutic agents on their targets. This mini-review focuses on the signal transduction pathways of Kaposi's sarcoma (KS) and on how the knowledge of such pathways has led to the rational development of molecularly targeted pathogenesis-driven therapies. Acquired immune deficiency syndrome (AIDS) related-KS results from co-infection with human immunodeficiency virus and KS herpesvirus/human herpesvirus-8 (KSHV/HHV8), which leads to the development of an angiogenic-inflammatory state that is critical in the pathogenesis of KS. KS is driven by KSHV/HHV8-specific pathways, which include viral G protein-coupled receptor (vGPCR), viral interleukin-6 (vIL-6), and viral chemokine homologues. In addition, cellular growth/angiogenic pathways, such as vascular endothelial growth factor (VEGF), insulin-like growth factor, platelet-derived growth factor (PDGF), angiopoietin and matrix metalloproteinases (MMPs) are "pirated" by KSHV/HHV8. As a very tangible example of how translational research has led to a marked improvement in patient outcome, the signal transduction inhibitor imatinib (a tyrosine kinase inhibitor of c-kit and PDGF) was administered to patients with KS whose tumors were serially biopsied. Not only did the patients' tumors regress, but also the regression was correlated with the inhibition of PDGF receptor (PDGFR) in the biopsy samples. Recent and future clinical trials of molecularly targeted therapy for the treatment of KS are a prelude to a shift in the paradigm of how KS is managed. J. Cell. Physiol. 209: 659,662, 2006. © 2006 Wiley-Liss, Inc. [source] Effects of lipopolysaccharide on platelet-derived growth factor isoform and receptor expression in cultured rat common bile duct fibroblasts and cholangiocytesJOURNAL OF GASTROENTEROLOGY AND HEPATOLOGY, Issue 7 2009Tae-Hyeon Kim Abstract Background and Aim:, Little is known about the role of platelet-derived growth factor (PDGF) in biliary fibrosis in the setting of bacterial colonization of the biliary tree. We therefore sought to investigate whether exposure to bacterial lipopolysaccharide (LPS) alters PDGF isoform and receptor expression in cultured rat common bile duct fibroblasts (CBDF) and normal rat cholangiocytes (NRC). Methods:, Collagen content in cells and media was assessed by colorimetric assay and gel electrophoresis. mRNA levels of PDGF-A and -B, and PDGF-Receptors (PDGF-R) , and , were measured by relative quantitative real-time PCR. Protein levels of PDGF-AA, AB and BB were measured by ELISA, and PDGF-R, and PDGF-R, by Western blot. Results:, In CBDF, LPS increased total soluble collagen synthesis and secretion. PDGF-R, and , mRNA and protein were also increased by LPS treatment in CBDF. Lipopolysaccharide treatment elicited an increase in PDGF-A and -B mRNA levels in CBDF. In NRC, levels of PDGF-A mRNA increased in a dose-dependent fashion following LPS treatment, whereas PDGF-B mRNA showed no response. PDGF-AA secretion was higher by CBDF than by NRC. PDGF-BB levels were also higher in CBDF than in NRC. While PDGF-BB levels did not respond to LPS treatment in CBDF, there was a dose-dependent response of this isoform to LPS in NRC. Intracellular and secreted PDGF-AB increased with LPS treatment in NRC. Conclusions:, These results support a model in which chronic bacterial colonization of the biliary tree induces fibrosis through PDGF-dependent mechanisms. [source] Calcium channel upregulation in response to activation of neurotrophin and surrogate neurotrophin receptor tyrosine kinasesJOURNAL OF NEUROSCIENCE RESEARCH, Issue 1 2003Melony J. Black Abstract Modulation of calcium channel expression and function in the context of neurotrophin induced neuronal differentiation remains incompletely understood at a mechanistic level. We addressed this issue in the PC12 model neuronal system using patch clamp electrophysiology combined with ectopic expression of the human , platelet-derived growth factor (,PDGF) receptor as a surrogate neurotrophin receptor system. PC12 cells ectopically expressing the human ,PDGF receptor were treated with PDGF or nerve growth factor (NGF) for up to 7 days, and Ca2+ channel subtype expression was analyzed using selective pharmacological agents in both whole-cell and cell-attached single channel patch clamp configurations. PDGF-induced upregulation of N- and P/Q-type Ca2+ channel currents completely mimicked upregulation of these currents caused by NGF stimulation of the endogenous TrkA receptor tyrosine kinase (RTK). Neither PDGF nor NGF significantly altered L- or R-type currents. Single channel recordings together with immunocytochemistry implied that growth factor-induced increases in whole-cell Ca2+ currents were a result of synthesis of new channels, and that whereas increased N channel density was apparent in the soma, additional P/Q channels distributed preferentially to extrasomal locations, most likely the proximal neurites. Finally, specific signaling-deficient mutant forms of the ,PDGF receptor were used to show that activation of Src, PI3-kinase, RasGAP, PLC, or SHP-2 (some of which are implicated in certain other aspects of PC12 cell differentiation) by RTKs is not required for growth factor-induced Ca2+ channel upregulation. In contrast, activation of the Ras-related G-protein Rap1 was found critical to this process. © 2003 Wiley-Liss, Inc. [source] Immunohistochemical detection of insulin-like growth factors, platelet-derived growth factor, and their receptors in ameloblastic tumorsJOURNAL OF ORAL PATHOLOGY & MEDICINE, Issue 4 2007H. Kumamoto Background:, To evaluate the roles of growth factors in oncogenesis and cytodifferentiation of odontogenic tumors, expression of insulin-like growth factors (IGFs), platelet-derived growth factor (PDGF), and their receptors was analyzed in ameloblastic tumors as well as in tooth germs. Methods:, Tissue specimens of 10 tooth germs, 47 ameloblastomas, and five malignant ameloblastic tumors were examined immunohistochemically with the use of antibodies against IGF-I, IGF-II, IGF-I receptor (IGF-IR), PDGF A-chain, PDGF B-chain, PDGF , -receptor, and PDGF , -receptor. Results:, Immunohistochemical reactivity for IGFs, PDGF chains, and their receptors was detected predominantly in odontogenic epithelial cells near the basement membrane in tooth germs and in benign and malignant ameloblastic tumors. The expression levels of IGF-II and PDGF chains were significantly higher in ameloblastic tumors than in tooth germs. Malignant ameloblastic tumors showed higher reactivity for PDGF chains than benign ameloblastomas and higher reactivity for platelet-derived growth factor receptors than tooth germs. The expression levels of PDGF chains were significantly higher in follicular ameloblastomas than in plexiform ameloblastomas. Desmoplastic ameloblastomas showed higher expression of IGFs and IGF-IR when compared with other ameloblastoma subtypes. Conclusion:, Expression of IGFs, PDGF, and their receptors in tooth germs and ameloblastic tumors suggests that these growth factor signals contribute to cell proliferation or survival in both normal and neoplastic odontogenic tissues. Expression of these molecules in odontogenic tissues possibly affects interactions with the bone microenvironment during tooth development and intraosseous progression of ameloblastic tumors. Altered expression of the ligands and receptors in ameloblastic tumors may be involved in oncogenesis, malignant potential, and tumor cell differentiation. [source] Effect of varying osmotic conditions on the response of bovine nucleus pulposus cells to growth factors and the activation of the ERK and Akt pathwaysJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 10 2010Eleni Mavrogonatou Abstract Intervertebral disc and especially nucleus pulposus is characterized by low cellularity. Additionally, extreme variations in osmolality are observed in this tissue, as a result of its specific physicochemical environment, daily activities, or degeneration. In this study, we investigated the role of osmotic fluctuations in the proliferative response of nucleus pulposus cells to exogenous growth factors. In particular, we examined the effect of platelet-derived growth factor (PDGF) and insulin-like growth factor-I (IGF-I) on the proliferation of bovine nucleus pulposus cells and on the activation of the MEK/ERK and PI-3-K/Akt pathways under varying osmotic conditions, in an effort to understand the mechanisms regulating cell proliferation in the intact and the degenerated intervertebral disc. Exposure of cells to high osmolality restrained novel DNA synthesis induced by PDGF or IGF-I in a dose-dependent manner and reduced ERK and Akt activation stimulated by serum or isolated growth factors. Our findings indicate that hyperosmolality imposes a strict control in intervertebral disc cells' proliferation, while hypo-osmotic conditions prevailing in degenerated discs may offer a more permissive environment for cellular proliferation. Published by Wiley Periodicals, Inc. J Orthop Res 28:1276,1282, 2010 [source] Recombinant human platelet-derived growth factor BB (rhPDGF-BB) and beta-tricalcium phosphate/collagen matrix enhance fracture healing in a diabetic rat modelJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 8 2009Loay Al-Zube Abstract Diabetes mellitus is a common systemic disease that has been associated with poor fracture healing outcomes. The mechanism through which diabetes impairs bone regeneration is unknown. One possible mechanism may be related to either decreased or uncoordinated release of local growth factors at the fracture site. Indeed, previous studies have found reduced platelet-derived growth factor (PDGF) levels in the fracture callus of diabetic rats, suggesting that local application of PDGF may overcome the negative effects of diabetes and promote fracture healing. To test this hypothesis, low (22 µg) and high (75 ug) doses of recombinant human PDGF-BB (rhPDGF-BB) were applied directly to femur fracture sites in BB Wistar diabetic rats that were then compared to untreated or vehicle-treated animals. rhPDGF-BB treatment significantly increased early callus cell proliferation compared to that in control specimens. Low dose rhPDGF-BB treatment significantly increased callus peak torque values (p,<,0.05) at 8 weeks after fracture as compared to controls. High dose rhPDGF-BB treatment increased callus bone area at 12 weeks postfracture. These data indicate that rhPDGF-BB treatment ameliorates the effects of diabetes on fracture healing by promoting early cellular proliferation that ultimately leads to more bone formation. Local application of rhPDGF-BB may be a new therapeutic approach to treat diabetes-impaired fracture healing. © 2009 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 27: 1074,1081, 2009 [source] Increased accumulation of superficial zone protein (SZP) in articular cartilage in response to bone morphogenetic protein-7 and growth factorsJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 3 2007Afshin Khalafi Abstract The purpose of this study was to investigate the role of bone morphogenetic proteins (BMPs), such as BMP-7, growth factors, and cytokines, in the accumulation of superficial zone protein (SZP) in bovine articular cartilage. Calf superficial articular cartilage discs and chondrocytes were obtained for explant and monolayer culture systems, respectively. Dose- and time-dependent actions of BMP-7 on SZP accumulation were investigated in both explant and monolayer culture systems. In addition, actions of various morphogens and growth factors [BMP-2, BMP-4, fibroblast growth factor 2 (FGF-2), insulin-like growth factor 1 (IGF-1), platelet-derived growth factor (PDGF), and transforming growth factor , (TGF-,1)], and cytokines [interleukin (IL)-1,, IL-1,, and tumor necrosis factor (TNF-,)] alone, and in combination with BMP-7, on SZP accumulation were investigated in monolayer culture systems. SZP accumulation was quantified in both the cartilage and the medium using SDS-PAGE and subsequent immunoblotting. In both explant and monolayer cultures, BMP-7 increased SZP accumulation in a dose- and time-dependent fashion (p,<,0.05). Furthermore, SZP accumulation was significantly increased in monolayer cultures by FGF-2, IGF-1, PDGF, and TGF-,1 (p,<,0.05). Both IL-1, and TNF-, significantly reduced SZP accumulation (p,<,0.05). The inhibition of SZP accumulation by TNF-, was partially alleviated by concurrent treatment with BMP-7. The results of this investigation provide novel insights into the role of morphogens, especially BMP-7, growth factors, and cytokines in the accumulation of SZP in articular cartilage. This information has clinical implications because stimulation of SZP may ameliorate the pathology of joint function in arthritis. Furthermore, tissue engineering approaches to articular cartilage may depend on the optimal synthesis and assembly of SZP in the superficial zone to ensure functional tissue architecture. © 2006 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 2007 [source] Retinoic acid is a potential negative regulator for differentiation of human periodontal ligament cellsJOURNAL OF PERIODONTAL RESEARCH, Issue 6 2005Natsuko Shibuya Background and objectives:, Retinoic acid (RA) exerts a wide variety of effects on development, cellular differentiation and homeostasis in various tissues. However, little is known about the effects of RA on the differentiation of periodontal ligament cells. In this study, we investigated whether RA can affect the dexamethasone-induced differentiation of periodontal ligament cells. Methods and results:, Human periodontal ligament cells were differentiated via culturing in the presence of dexamethasone, ascorbic acid, and ,-glycerophosphate for mineralized nodule formation, as characterized by von Kossa staining. Continuous treatment with all- trans -RA inhibited the mineralization in a dose-dependent manner, with complete inhibition over 1 µm RA. Other RA analogs, 9- cis -RA and 13- cis -RA, were also effective. Furthermore, addition of RA for just the first 4 days completely inhibited the mineralization; however, as RA was added at later stages of culture, the inhibitory effect was diminished, suggesting that RA had a phase-dependent inhibition of mineralization. RA receptor (RAR)-, agonist (AM-580), but not retinoid X receptor agonist (methoprene acid), inhibited the mineralization, and reverse transcription,polymerase chain reaction analysis revealed that RAR-, was expressed on the cells, suggesting that RAR-, was involved in the inhibitory mechanism. This inhibition was accompanied by inhibition of alkaline phosphatase activity; however, neither expression of platelet-derived growth factor (PDGF) receptor-,, PDGF receptor-,, or epidermal growth factor (EGF) receptor, nor phosphorylation of extracellular signal-regulated kinases triggered by PDGF-ascorbic acid or PDGF-BB was changed, as assessed by flow cytometry or western blot analyses. Conclusions:, These findings suggest that RA is a potential negative regulator for differentiation of human periodontal ligament cells. [source] Superoxide anions and hydrogen peroxide inhibit proliferation of activated rat stellate cells and induce different modes of cell deathLIVER INTERNATIONAL, Issue 6 2009Sandra Dunning Abstract Background: In chronic liver injury, hepatic stellate cells (HSCs) proliferate and produce excessive amounts of connective tissue causing liver fibrosis and cirrhosis. Oxidative stress has been implicated as a driving force of HSC activation and proliferation, although contradictory results have been described. Aim: To determine the effects of oxidative stress on activated HSC proliferation, survival and signalling pathways. Methods: Serum-starved culture-activated rat HSCs were exposed to the superoxide anion donor menadione (5,25 ,mol/L) or hydrogen peroxide (0.2,5 mmol/L). Haem oxygenase-1 mRNA expression, glutathione status, cell death, phosphorylation of mitogen-activated protein (MAP) kinases and proliferation were investigated. Results: Menadione induced apoptosis in a dose- and time-dependent, but caspase-independent manner. Hydrogen peroxide induced necrosis only at extremely high concentrations. Both menadione and hydrogen peroxide activated Jun N-terminal kinase (JNK) and p38. Hydrogen peroxide also activated extracellular signal-regulated protein. Menadione, but not hydrogen peroxide, reduced cellular glutathione levels. Inhibition of JNK or supplementation of glutathione reduced menadione-induced apoptosis. Non-toxic concentrations of menadione or hydrogen peroxide inhibited platelet-derived growth factor- or/and serum-induced proliferation. Conclusion: Reactive oxygen species (ROS) inhibit HSC proliferation and promote HSC cell death in vitro. Different ROS induce different modes of cell death. Superoxide anion-induced HSC apoptosis is dependent on JNK activation and glutathione status. [source] Promising tumor-associated antigens for future prostate cancer therapyMEDICINAL RESEARCH REVIEWS, Issue 1 2010Yong Li Abstract Prostate cancer (CaP) is one of the most prevalent malignant diseases among men in Western countries. There is currently no cure for metastatic castrate-resistant CaP, and median survival for these patients is about 18 months; the high mortality rate seen is associated with widespread metastases. Progression of CaP from primary to metastatic disease is associated with several molecular and genetic changes that can affect the expression of specific tumor-associated antigens (TAAs) or receptors on the cell surface. Targeting TAAs is emerging as an area of promise for controlling late-stage and recurrent CaP. Several reviews have summarized the progress made in targeting signaling pathways for CaP but will not be discussed here. We describe some important CaP TAAs. These include prostate stem-cell antigen, prostate-specific membrane antigen, MUC1, epidermal growth factor receptor, platelet-derived growth factor and its receptor, urokinase plasminogen activator and its receptor, and extracellular matrix metalloproteinase inducer. We summarize recent advancements in our understanding of their role in CaP metastasis, as well as potential therapeutic options for targeting CaP TAAs. We also discuss the origin, identification, and characterization of prostate cancer stem cells (CSCs) and the potential benefits of targeting prostate CSCs to overcome chemoresistance and CaP recurrence. © 2009 Wiley Periodicals, Inc. Med Res Rev, 30, No. 1, 67,101, 2010 [source] The role of platelet-derived growth factor in a murine model of crescentic nephritisNEPHROLOGY, Issue 3 2000La Haseley SUMMARY Platelet-derived growth factor (PDGF) is a major mesenchymal cell mitogen, with an established role in the pathogenesis of experimental mesangial proliferative nephritis. The role of PDGF in experimental models of crescentic glomerulonephritis is not well defined. To study the role of PDGF in glomerular crescent formation, we induced a model of crescentic glomerulonephritis in transgenic mice expressing high concentrations of the soluble external domain of the PDGF, receptor (PDGF-R,). Crescentic nephritis was induced by the intraperitoneal injection of antibody to whole rabbit glomeruli. At day 7 of disease, biopsies of transgenic and wild-type mice were evaluated for crescent frequency, crescent area, and thickness of crescent cell layer. In situ hybridization was performed to evaluate the expression of both PDGF B-chain and PDGFR, mRNA within crescents. Delivery of soluble receptor to the urinary space was evaluated by Western blotting. Crescent frequency did not differ between wild type and transgenic mice. However, crescent area quantified by computer image analysis was significantly reduced in transgenic mice (P < 0.015). Transgenic biopsies displayed predominantly crescents composed of two cell layers (P = 0.03 compared with wild type), whereas wild-type biopsies had significantly more crescents composed of four or more cell layers (P = 0.04). Both PDGF B-chain and PDGF-R, mRNA were detected within crescents in a heterogeneous fashion. Soluble receptor was detectable in the urine of all transgenic diseased mice. We conclude that PDGF plays a role in modulating crescent size and development in our murine model of crescentic nephritis. [source] | ||||||||||||||||||||||||||||||||||