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1.
Protein kinase C activators inhibit receptor-mediated potocytosis by preventing internalization of caveolae 总被引:25,自引:14,他引:11 下载免费PDF全文
《The Journal of cell biology》1994,124(3):307-313
Potocytosis is an endocytic pathway that utilizes glycosylphosphatidylinositol-anchored membrane proteins and caveolae to concentrate and internalize small molecules. We now report that activators of protein kinase C are potent inhibitors of potocytosis. Activators such as phorbol-12-myristate-13-acetate (PMA) inhibit the internalization of receptors for 5-methyltetrahydrofolate but allow the internal receptor pool to return to the cell surface. PMA does not affect the clustering of the folate receptor but instead markedly reduces the number of caveolae. Exposure to PMA totally blocks the intracellular accumulation of 5-methyltetrahydrofolate without affecting receptor-independent uptake or the formation of polyglutamylated species of 5-methyltetrahydrofolate in the cytoplasm. These data suggest that PMA inhibits uptake by inactivating caveolae internalization. 相似文献
2.
Vascular endothelial growth factor (VEGF) is essential for many angiogenic processes both in normal conditions and in pathological conditions. However, the signaling pathways involved in VEGF-induced angiogenesis are not well defined. Protein kinase D (PKD), a newly described serine/threonine protein kinase, has been implicated in many signal transduction pathways and in cell proliferation. We hypothesized that PKD would mediate VEGF signaling and function in endothelial cells. Here we found that VEGF rapidly and strongly stimulated PKD phosphorylation and activation in endothelial cells via VEGF receptor 2 (VEGFR2). The pharmacological inhibitors for phospholipase Cgamma (PLCgamma) and protein kinase C (PKC) significantly inhibited VEGF-induced PKD activation, suggesting the involvement of the PLCgamma/PKC pathway. In particular, PKCalpha was critical for VEGF-induced PKD activation since both overexpression of adenovirus PKCalpha dominant negative mutant and reduction of PKCalpha expression by small interfering RNA markedly inhibited VEGF-induced PKD activation. Importantly, we found that small interfering RNA knockdown of PKD and PKCalpha expression significantly attenuated ERK activation and DNA synthesis in endothelial cells by VEGF. Taken together, our results demonstrated for the first time that VEGF activates PKD via the VEGFR2/PLCgamma/PKCalpha pathway and revealed a critical role of PKD in VEGF-induced ERK signaling and endothelial cell proliferation. 相似文献
3.
Protein kinase C mediates induced secretion of vascular endothelial growth factor by human glioma cells 总被引:6,自引:0,他引:6
Tsai JC Teng LJ Chen CT Hong TM Goldman CK Gillespie GY 《Biochemical and biophysical research communications》2003,309(4):952-960
To understand how vascular endothelial growth factor (VEGF) production is activated in malignant glioma cells, we employed protein tyrosine kinase (PTK) and protein kinase C (PKC) inhibitors to evaluate the extent to which these protein kinases were involved in signal transduction leading to VEGF production. PTK inhibitors blocked glioma proliferation and epidermal growth factor (EGF)-induced VEGF secretion, while H-7, a PKC inhibitor, inhibited both EGF-induced and baseline VEGF secretion. Phorbol 12-myristate 13-acetate (PMA), a non-specific activator of PKC, induced VEGF secretion by glioma cells, which was enhanced by calcium ionophore A23187, but completely blocked after prolonged treatment of cells with 1 microM PMA, by presumably depleting PKC. All inhibitors (genistein, AG18, AG213, H-7, prolonged PMA treatment) which inhibited EGF-induced VEGF secretion in glioma cells also inhibited cell proliferation at similar concentrations. However, PKC inhibition only blocked 50% of the VEGF secretion induced by growth factors (EGF, platelet-derived growth factor-BB, or basic fibroblast growth factor). This reserve capacity could be ascribed to a PKC-independent effect, or to PKC isoenzymes not down-regulated by PMA. These findings extend our previous assertion that VEGF secretion is tightly coupled with proliferation by suggesting that activation of convergent growth factor signaling pathways will lead to increased glioma VEGF secretion. Understanding of signal transduction of growth factor-induced VEGF secretion should provide a rational basis for the development of novel strategies for therapy. 相似文献
4.
Protein kinase C subtypes in endothelial cells 总被引:2,自引:0,他引:2
P Mattila 《FEBS letters》1991,289(1):86-90
Activation of protein kinase C (PKC) has been linked to the regulation of class II expression on endothelial cells by interferon-gamma (IFN-gamma). PKC subtypes in endothelial cells were analyzed using three different approaches, the immunoperoxidase staining of native and IFN-gamma stimulated cells cultured on chamber slides as well as immuno- and Northern blotting. All approaches revealed that of the conventional subtypes, alpha is the predominant form of PKC in endothelial cells. Even though IFN-gamma is able to induce PKC translocation to particulate fractions, no translocation was detected in histological stainings. Western blot studies as well as mRNA studies revealed that IFN-gamma is unable to increase the total amount of PKC in endothelial cells. 相似文献
5.
Activation of the enzyme protein kinase C (PKC) plays an important role in T cell activation. We investigated the phosphorylation of CD2, CD3, CD4, CD5, CD7, CD8, CD28 (Tp44), CD43 (sialophorin, gp115), and LFA-1 after incubation of human PBMC with the (PKC) activator PMA. These proteins were chosen for their role in transmembrane signal transduction (CD2, CD3, CD5, CD28, CD43), cell-cell interaction and adhesion (CD2, CD4, CD8, and LFA-1), or involvement in immunodeficiency states (CD43, CD7). CD5, CD7, CD43, and the alpha-chain of LFA-1 were found to be constitutively phosphorylated. PMA induced rapid hyperphosphorylation of CD5, CD7, and CD43, but not of the LFA-1 alpha-chain, and induced the phosphorylation of CD3, CD4, CD8 and of the LFA-1 beta-chain. PMA did not cause the phosphorylation of CD2 and CD28. PMA-induced phosphorylation was partially inhibited by the PKC inhibitor 1-(5-isoquinolinylsulfonyl)-2-methylpiperazine dihydrochloride. Finally, the T cell activator Con A, which binds to the CD3/TCR complex was shown to induce a profile of protein phosphorylation similar to that observed with PMA. We conclude that PKC-mediated phosphorylation of T cell Ag may represent an important regulatory mechanism that governs the process of T cell activation. 相似文献
6.
Micropatterning technology holds significant promise in the development of micro/nanomedical devices. The precise control of cell position and migration is important in several applications. For example, the optimal design of implantable devices depends on the implant material's micro-and nano-texture, which influences the response of nearby tissue, including the microvessels. Therefore, we were interested in endothelial cell positioning and colonization on specific surface domains in the size range of microvasculature. To this end, endothelial cells were seeded in microfabricated grooves and exposed to vascular endothelial growth factor (VEGF), which plays a key role in the angiogenic response. Patterned silicon wafers with grooves of 50 microm width and depth and 150 microm groove spacing were used. Each patterned region had two semicircular ports at either end, one of which was used to seed human retinal endothelial cells (HREC) and the other to house VEGF embedded in Matrigel. After 1 week, cells were fixed and analyzed by laser scanning cytometry (LSC). Our results shows that we can control HREC seeding and positioning in surface grooves and that the speed of colonization of the grooves can be manipulated by local VEGF application. We were able to quantify this effect, showing that HREC relocate inside the grooves twice as fast in response to VEGF stimulation, compared to control conditions, at a speed of 3.14 +/- 0.01 and 1.55 +/- 0.01 microm/min, respectively. Our approach could be used towards the fabrication of "designer" substrates or devices that not only allow patterned cell growth, but also permit dynamic cell repositioning. 相似文献
7.
蛋白激酶C与细胞周期 总被引:6,自引:0,他引:6
近年的研究表明,PKC涉及到细胞的周期调节。在酵母细胞和哺乳动物细胞均发现PKC参与细胞周期调控,从而提示PKC可能在进化上是一种保守的细胞周期调节子。一般认为PKC在两个点上对细胞周期起作用,即G1期和G2期到M期的过渡期(G2/M)。在G1期,PKC分别在早G1期和晚G1期作用有所不同,主要作用表现在使细胞停留在G1期的中末阶段,这一过程,主要涉及到抑制肿瘤抑制因子-成视网膜细胞瘤(Rb)蛋白的磷酸化。PKC的主要作用是降低周期素依赖激酶CDK2的活性、降低周期素E和A的表达和增加周期素依赖的周期抑制蛋白p21^WAF1和p27^KIP1的表达;在G2/M期,PKC对细胞周期的调节主要与Cdc2(CDK1)的活性抑制有关。 相似文献
8.
Vascular smooth muscle Notch signals regulate endothelial cell sensitivity to angiogenic stimulation
The evolutionarily conserved Notch signaling pathway is required for normal vascular development and function, and genetic associations link select Notch receptors and ligands to human clinical syndromes featuring blood vessel abnormalities and stroke susceptibility. A previously described mouse model engineered to suppress canonical Notch signaling in vascular smooth muscle cells (vSMCs) revealed surprising anatomical defects in arterial patterning and vessel maturation, suggesting that vSMCs have the functional capacity to influence blood vessel formation in a Notch signaling-dependent manner. In further analyses using this model system, we now show that explanted aortic ring tissue and Matrigel implants from the smooth muscle Notch signaling-deficient mice yield markedly diminished responses to angiogenic stimuli. Furthermore, cultured Notch signaling-deficient primary vSMCs have reduced proliferation and migration capacities and reveal diminished expression of PDGF receptor β and JAGGED1 ligand. These observations prompted a series of endothelial cell (EC)-vSMC co-culture experiments that revealed a requirement for intact vSMC Notch signals via JAGGED1 for efficient EC Notch1 receptor activation and EC proliferation. Taken together, these studies suggest a heterotypic model wherein Notch signaling in vSMCs provides early instructive cues to neighboring ECs important for optimal postnatal angiogenesis. 相似文献
9.
Recent studies have indicated that endothelial cell function includes elaboration of growth factors and regulation of coagulation. In this paper we demonstrate that activated coagulation Factor X (Factor Xa), a product of the coagulation mechanism generated before thrombin, induces enhanced release of endothelial cell mitogens, linking these two functions. Mitogenic activity generated by cultured bovine aortic endothelial cells in response to Factor Xa included platelet-derived growth-factor-like molecules based on a radioreceptor assay. Effective induction of mitogens by Factor Xa required the integrity of the enzyme's active center and the presence of the gamma-carboxyglutamic acid-containing domain of the molecule. Factor Xa-induced release of mitogens from endothelium occurred in serum-free medium and was not altered by hirudin or antibody to Factor V, indicating that it was a direct effect of Factor Xa and was not mediated by thrombin. Elaboration of mitogenic activity required only brief contact between Factor Xa and endothelium, and occurred in a time-dependent manner. Generation of enhanced mitogenic activity in response to Factor Xa was unaffected by the presence of actinomycin D and was not associated with increased hybridization of RNA from treated cells to a v-sis probe. Release of mitogenic activity was dependent on the dose of Factor Xa, being half-maximal at 0.5 nM and reaching a maximum by 5 nM. Radioligand binding studies demonstrated a class of endothelial cell sites half-maximally occupied at a Factor Xa concentration of 0.8 nM. The close correspondence between the parameters of Factor Xa-induced mitogen release and Factor Xa binding suggests these sites may be related. When Factor X was activated on the endothelial cell surface by Factors IXa and VIII, the Factor Xa formed resulted in the induction of enhanced release of mitogenic activity. These data suggest a mechanism by which the coagulation system can locally regulate endothelial cell function and vessel wall biology before thrombin-induced release of growth factors from platelets. 相似文献
10.
Stimulation of motility in cultured bovine capillary endothelial cells by angiogenic preparations 总被引:5,自引:0,他引:5
Several angiogenic preparations that have been shown to stimulate plasminogen activator (PA) and collagenase production by cultured bovine capillary endothelial (BCE) cells were tested for their ability to stimulate BCE cell motility in the phagokinetic track assay. Bovine retinal extract, medium conditioned by 3T3-F442A differentiated mouse adipocytes, SK HEP-1 human hepatoma cell lysate, mouse sarcoma 180 cell lysate, and medium conditioned by mouse sarcoma 180 cells stimulated motility 68.7%, 48.5%, 140.9%, 56.5%, and 102.1%, respectively, relative to untreated cells. The motility-stimulating activity of these preparations was dose dependent and linear over the 16-h assay period. Several hormones and growth factors were tested for BCE cell motility-stimulating activity, including insulin, vasopressin, fibroblast growth factor, and a partially purified preparation of sarcoma growth factor, and were found to be ineffective. 12-0-tetradecanoyl-phorbol-acetate (TPA), a potent stimulator of both PA and collagenase activities in BCE cells, also did not stimulate motility, indicating that protease production is not sufficient to stimulate BCE cell motility in this assay. Neither SK HEP-1 hepatoma cell lysate nor TPA was effective in stimulating motility in bovine aortic endothelial (BAE) cells. The inability of SK HEP-1 hepatoma cell lysate to stimulate movement in BAE cells is consistent with the observation that angiogenesis occurs by sprouting of capillaries, not large vessels. 相似文献
11.
Lipid activators of protein kinase C 总被引:2,自引:0,他引:2
Among the many reported lipid activators of protein kinase C only those of high affinity can be considered true physiological effectors, at present the tumor promoters, e.g., phorbol esters; 1,2-diacyl-sn-glycerols; and phosphatidylinositol 4,5-bisphosphate. Many other compounds (including arachidonic acid) are activators at high, unphysiological concentrations only, and they seem to be sterically unsuited for bonding to the enzyme. Such pseudo-activators possibly act by scrambling the structure of the regulatory moiety of the kinase. 相似文献
12.
Inhibition of capillary endothelial cell growth by pericytes and smooth muscle cells 总被引:47,自引:7,他引:47 下载免费PDF全文
Morphological studies of developing capillaries and observations of alterations in capillaries associated with pathologic neovascularization indicate that pericytes may act as suppressors of endothelial cell (EC) growth. We have developed systems that enable us to investigate this possibility in vitro. Two models were used: a co-culture system that allowed direct contact between pericytes and ECs and a co-culture system that prevented physical contact but allowed diffusion of soluble factors. For these studies, co-cultures were established between bovine capillary ECs and the following growth-arrested cells (hereafter referred to as modulating cells): pericytes, smooth muscle cells (SMCs), fibroblasts, epithelial cells, and 3T3 cells. The modulating cell type was growth arrested by treatment with mitomycin C before co-culture with ECs. In experiments where cells were co-cultured directly, the effect of co-culture on EC growth was determined by comparing the mean number of cells in the co-cultures to the mean for each cell type (EC and modulating cell) cultured separately. Since pericytes and other modulating cells were growth arrested, any cell number change in co-cultures was due to EC growth. In the co-cultures, pericytes inhibited all EC proliferation throughout the 14-d time course; similar levels of EC inhibition were observed in SMC-EC co-cultures. Co-culture of ECs with fibroblasts, epithelial cells, and 3T3 cells significantly stimulated EC growth over the same time course (30-192% as compared to EC cultured alone). To determine if cell contact was required for inhibition, cells were co-cultured using Millicell chambers (Millipore Corp., Bedford, MA), which separated the cell types by 1-2 mm but allowed the exchange of diffusible materials. There was no inhibition of EC proliferation by pericytes or SMCs in this co-culture system. The influence of the cell ratios on observed inhibition was assessed by co-culturing the cells at EC/pericyte ratios of 1:1, 2:1, 5:1, 10:1, and 20:1. Comparable levels of EC inhibition were observed at ratios from 1:1 to 10:1. When the cells were co-cultured at a ratio of 20 ECs to 1 pericyte, inhibition of EC growth at 3 d was similar to that observed at other ratios. However, at higher ratios, the inhibition diminished so that by the end of the time course the co-cultured ECs were growing at the same rate as the controls. These results suggest that pericytes and SMCs can modulate EC growth by a mechanism that requires contact or proximity. We postulate that similar interactions may operate to modulate vascular growth in vivo. 相似文献
13.
14.
Hantaviruses predominantly infect human endothelial cells and, in the absence of cell lysis, cause two diseases resulting from increased vascular permeability. Andes virus (ANDV) causes a highly lethal acute pulmonary edema termed hantavirus pulmonary syndrome (HPS). ANDV infection enhances the permeability of endothelial cells in response to vascular endothelial growth factor (VEGF) by increasing signaling responses directed by the VEGFR2-Src-VE-cadherin pathway, which directs adherens junction (AJ) disassembly. Here we demonstrate that inhibiting pathway-specific VEGFR2 and Src family kinases (SFKs) blocks ANDV-induced endothelial cell permeability. Small interfering RNA (siRNA) knockdown of Src within ANDV-infected endothelial cells resulted in an ~70% decrease in endothelial cell permeability compared to that for siRNA controls. This finding suggested that existing FDA-approved small-molecule kinase inhibitors might similarly block ANDV-induced permeability. The VEGFR2 kinase inhibitor pazopanib as well as SFK inhibitors dasatinib, PP1, bosutinib, and Src inhibitor 1 dramatically inhibited ANDV-induced endothelial cell permeability. Consistent with their kinase-inhibitory concentrations, dasatinib, PP1, and pazopanib inhibited ANDV-induced permeability at 1, 10, and 100 nanomolar 50% inhibitory concentrations (IC(50)s), respectively. We further demonstrated that dasatinib and pazopanib blocked VE-cadherin dissociation from the AJs of ANDV-infected endothelial cells by >90%. These findings indicate that VEGFR2 and Src kinases are potential targets for therapeutically reducing ANDV-induced endothelial cell permeability and, as a result, capillary permeability during HPS. Since the functions of VEGFR2 and SFK inhibitors are already well defined and FDA approved for clinical use, these findings rationalize their therapeutic evaluation for efficacy in reducing HPS disease. Endothelial cell barrier functions are disrupted by a number of viruses that cause hemorrhagic, edematous, or neurologic disease, and as a result, our findings suggest that VEGFR2 and SFK inhibitors should be considered for regulating endothelial cell barrier functions altered by additional viral pathogens. 相似文献
15.
New functions of epidermal growth factor: stimulation of capillary endothelial cell migration and matrix dependent proliferation 总被引:3,自引:0,他引:3
The proliferative response of bovine retinal capillary endothelial cells to EGF is dependent upon attaching the cells to a matrix of fibronectin. Bovine capillary endothelial cells are also stimulated to actively migrate when exposed to EGF in vitro. These activities provide an explanation for the angiogenic properties of EGF in vivo. Capillary cell migration and proliferation are proposed as sensitive quantifiable bioassays to explore the functional domains of the EGF molecule. Studies on the inactivation of these properties of EGF by specific cleavage of the molecule with CNBr or proteases suggest that an intact loop composed in part by amino acid residues 20 to 31 is essential for at least some functions. 相似文献
16.
W Beil W Mannschedel K F Sewing 《Biochemical and biophysical research communications》1987,149(2):720-728
Ca2+-phospholipid dependent protein kinase activity and the effect of 12-O-tetradecanoylphorbol-13-acetate (TPA) on H+ secretion was studied in guinea-pig parietal cells. In resting parietal cells PK-C activity was distributed almost equally in both the cytosolic and particulate cell fraction. Exposure of the cells to TPA resulted in a loss of cytosolic PK-C activity which was not accompanied by a concomitant increase of particulate activity. Furthermore TPA inhibits the K+/H+-ATPase and dissipates H+ gradient in intact gastric vesicles by a protonophoric action. The role of these biochemical events for the antisecretory action of TPA found in the intact parietal cell are discussed. 相似文献
17.
Birukova AA Liu F Garcia JG Verin AD 《American journal of physiology. Lung cellular and molecular physiology》2004,287(1):L86-L93
Cross talk between the actin cytoskeleton and the microtubule (MT) network plays a critical role in regulation of endothelial permeability. We have previously demonstrated that MT disruption by nocodazole results in increases in MLC phosphorylation, actomyosin contraction, cell retraction, and paracellular gap formation, cardinal features of endothelial barrier dysfunction (Verin AD, Birukova A, Wang P, Liu F, Becker P, Birukov K, and Garcia JG. Am J Physiol Lung Cell Mol Physiol 281: L565-L574, 2001; Birukova AA, Smurova K, Birukov KG, Usatyuk P, Liu F, Kaibuchi K, Ricks-Cord A, Natarajan V, Alieva A, Garcia JG, and Verin AD. J Cell Physiol. In press.). Although activation of PKA opposes barrier-disrupting effects of edemagenic agents on confluent EC monolayers, information about the molecular mechanisms of PKA-mediated EC barrier protection is limited. Our results suggest that MT disassembly alters neither intracellular cAMP levels nor PKA enzymatic activity; however, elevation of cAMP levels and PKA activation by either cholera toxin or forskolin dramatically attenuates the decline in transendothelial electrical resistance induced by nocodazole in human pulmonary EC. Barrier-protective effects of PKA on EC were associated with PKA-mediated inhibition of nocodazole-induced stress fiber formation, Rho activation, phosphorylation of myosin phosphatase regulatory subunit at Thr696, and decreased MLC phosphorylation. In addition, forskolin pretreatment attenuated MT disassembly induced by nocodazole. These results suggest a critical role for PKA activity in stabilization of MT cytoskeleton and provide a novel mechanism for cAMP-mediated regulation of Rho-induced actin cytoskeletal remodeling, actomyosin contraction, and EC barrier dysfunction induced by MT disassembly. 相似文献
18.
Wu LW Mayo LD Dunbar JD Kessler KM Baerwald MR Jaffe EA Wang D Warren RS Donner DB 《The Journal of biological chemistry》2000,275(7):5096-5103
This study was initiated to identify signaling proteins used by the receptors for vascular endothelial cell growth factor KDR/Flk1, and Flt1. Two-hybrid cloning and immunoprecipitation from human umbilical vein endothelial cells (HUVEC) showed that KDR binds to and promotes the tyrosine phosphorylation of phospholipase Cgamma (PLCgamma). Neither placental growth factor, which activates Flt1, epidermal growth factor (EGF), or fibroblast growth factor (FGF) induced tyrosine phosphorylation of PLCgamma, indicating that KDR is uniquely important to PLCgamma activation in HUVEC. By signaling through KDR, VEGF promoted the tyrosine phosphorylation of focal adhesion kinase, induced activation of Akt, protein kinase Cepsilon (PKCepsilon), mitogen-activated protein kinase (MAPK), and promoted thymidine incorporation into DNA. VEGF activates PLCgamma, PKCepsilon, and phosphatidylinositol 3-kinase independently of one another. MEK, PLCgamma, and to a lesser extent PKC, are in the pathway through which KDR activates MAPK. PLCgamma or PKC inhibitors did not affect FGF- or EGF-mediated MAPK activation. MAPK/ERK kinase inhibition diminished VEGF-, FGF-, and EGF-promoted thymidine incorporation into DNA. However, blockade of PKC diminished thymidine incorporation into DNA induced by VEGF but not FGF or EGF. Signaling through KDR/Flk1 activates signaling pathways not utilized by other mitogens to induce proliferation of HUVEC. 相似文献
19.
Protein kinase C and T cell activation 总被引:16,自引:0,他引:16
Understanding the intracellular mechanisms by which binding of ligands, such as hormones and growth factors, to their specific receptors elicits the appropriate cellular response has long been a topic of great interest. Considerable excitement was generated when it was recognised that several receptor-ligand interactions operate via the hydrolysis of inositol phospholipids. This yields, at least, two 'second messengers', namely, inositol 1,4,5-trisphosphate [Ins(1,4,5)P3], which causes the release of Ca2+ from intracellular stores, and 1,2-diacylglycerol (ac2Gro), which activates the serine/threonine-specific enzyme, protein kinase C(PKC), reviewed in [1] and [2]. The pertinent question that follows is, how do PKC activation and elevation of the intracellular Ca2+ concentration evoke cell responses? In this review, attention has been focused on PKC, and the consequences of its activation in resting human T cells. Evidence that PKC activity is, at least partially, responsible for activation of resting human T cells will be examined, and some of the more recent research investigating how PKC activation elicits this cell response will be described. 相似文献
20.
PPAR activators inhibit endothelial cell migration by targeting Akt 总被引:12,自引:0,他引:12
Goetze S Eilers F Bungenstock A Kintscher U Stawowy P Blaschke F Graf K Law RE Fleck E Gräfe M 《Biochemical and biophysical research communications》2002,293(5):1431-1437
Peroxisome proliferator-activated receptors (PPARs) regulate lipid and glucose metabolism and exert several vascular effects that may provide a dual benefit of these receptors on metabolic disorders and atherosclerotic vascular disease. Endothelial cell migration is a key event in the pathogenesis of atherosclerosis. We therefore investigated the effects of lipid-lowering PPARalpha-activators (fenofibrate, WY14643) and antidiabetic PPARgamma-activators (troglitazone, ciglitazone) on this endothelial cell function. Both PPARalpha- and PPARgamma-activators significantly inhibited VEGF-induced migration of human umbilical vein endothelial cells (EC) in a concentration-dependent manner. Chemotactic signaling in EC is known to require activation of two signaling pathways: the phosphatidylinositol-3-kinase (PI3K)-->Akt- and the ERK1/2 mitogen-activated protein kinase (ERK MAPK) pathway. Using the pharmacological PI3K-inhibitor wortmannin and the ERK MAPK-pathway inhibitor PD98059, we observed a complete inhibition of VEGF-induced EC migration. VEGF-induced Akt phosphorylation was significantly inhibited by both PPARalpha- and gamma-activators. In contrast, VEGF-stimulated ERK MAPK-activation was not affected by any of the PPAR-activators, indicating that they inhibit migration either downstream of ERK MAPK or independent from this pathway. These results provide first evidence for the antimigratory effects of PPAR-activators in EC. By inhibiting EC migration PPAR-activators may protect the vasculature from pathological alterations associated with metabolic disorders. 相似文献