共查询到20条相似文献,搜索用时 31 毫秒
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2.
Goyal A Pal N Concannon M Paul M Doran M Poluzzi C Sekiguchi K Whitelock JM Neill T Iozzo RV 《The Journal of biological chemistry》2011,286(29):25947-25962
3.
Le BV Kim H Choi J Kim JH Hahn MJ Lee C Kim KK Hwang HY 《Journal of molecular biology》2011,414(2):231-242
Endorepellin, the C-terminal region of perlecan, inhibits angiogenesis by disrupting actin cytoskeleton and focal adhesions. The C-terminal laminin-like globular domain (LG3) of endorepellin directs most of this antiangiogenic activity. To investigate the angiostatic mechanism and to identify structural determinants, we have solved crystal structures of the LG3 domain in both apo- and calcium-bound forms at resolutions of 1.5 Å and 2.8 Å, respectively. The conserved core has the jellyroll fold characteristic of LG domains. The calcium-induced structural changes seem very restricted, and the calcium binding site appears to be preformed, suggesting that the bound calcium ion, rather than structural rearrangements, contributes to antiangiogenesis. We have identified H4268 on the EF loop as a key residue for the biochemical function of LG3, since its mutation abolishes antiangiogenic activity, and mutant LG3 can no longer form a direct interaction with integrin. Taken together, we propose that these two distinct structural elements contribute to the angiostatic effect of endorepellin. 相似文献
4.
Woodall BP Nyström A Iozzo RA Eble JA Niland S Krieg T Eckes B Pozzi A Iozzo RV 《The Journal of biological chemistry》2008,283(4):2335-2343
Endorepellin, the C-terminal module of perlecan, has angiostatic activity. Here we provide definitive genetic and biochemical evidence that the functional endorepellin receptor is the alpha2beta1 integrin. Notably, the specific endorepellin binding to the receptor was cation-independent and was mediated by the alpha2 I domain. We show that the anti-angiogenic effects of endorepellin cannot occur in the absence of alpha2beta1. Microvascular endothelial cells from alpha2beta1(-/-) mice, but not those isolated from either wild-type or alpha1beta1(-/-) mice, did not respond to endorepellin. Moreover, syngeneic Lewis lung carcinoma xenografts in alpha2beta1(-/-) mice failed to respond to systemic delivery of endorepellin. In contrast, endorepellin inhibited tumor growth and angiogenesis in the wild-type mice expressing integrin alpha2beta1. We conclude that the angiostatic effects of endorepellin in vivo are mediated by a specific interaction of endorepellin with the alpha2beta1 integrin receptor. 相似文献
5.
Gonzalez EM Reed CC Bix G Fu J Zhang Y Gopalakrishnan B Greenspan DS Iozzo RV 《The Journal of biological chemistry》2005,280(8):7080-7087
Endorepellin, the C-terminal domain of the heparan sulfate proteoglycan perlecan, possesses angiostatic activity. The terminal laminin-like globular (LG3) domain of endorepellin appears to possess most of the biological activity on endothelial cells. LG3 protein has been detected in the urine of patients with end-stage renal disease and in the amniotic fluid of pregnant women with premature rupture of fetal membranes. These findings suggest that proteolytic processing of endorepellin and the generation of LG3 might have biological significance. In this study, we have identified specific enzymes of the bone morphogenetic protein-1 (BMP-1)/Tolloid family of metalloproteases that cleave LG3 from recombinant endorepellin at the physiologically relevant site and that cleave LG3 from endogenous perlecan in cultured mouse and human cells. The BMP-1/Tolloid family of metalloproteases is thereby implicated in the processing of a major basement membrane proteoglycan and in the liberation of an anti-angiogenic factor. Using molecular modeling, site-directed mutagenesis and angiogenic assays, we further demonstrate that LG3 activity requires specific amino acids involved in Ca(2+) coordination. 相似文献
6.
Sònia Tugues Satoshi Honjo Christian K?nig Narendra Padhan Jeffrey Kroon Laura Gualandi Xiujuan Li Irmeli Barkefors Victor L. Thijssen Arjan W. Griffioen Lena Claesson-Welsh 《The Journal of biological chemistry》2013,288(26):19060-19071
CD63 is a member of the transmembrane-4 glycoprotein superfamily (tetraspanins) implicated in the regulation of membrane protein trafficking, leukocyte recruitment, and adhesion processes. We have investigated the involvement of CD63 in endothelial cell (EC) signaling downstream of β1 integrin and VEGF. We report that silencing of CD63 in primary ECs arrested capillary sprouting and tube formation in vitro because of impaired adhesion and migration of ECs. Mechanistically, CD63 associated with both β1 integrin and the main VEGF receptor on ECs, VEGFR2. Our data suggest that CD63 serves to bridge between β1 integrin and VEGFR2 because CD63 silencing disrupted VEGFR2-β1 integrin complex formation identified using proximity ligation assays. Signaling downstream of β1 integrin and VEGFR2 was attenuated in CD63-silenced cells, although their cell surface expression levels remained unaffected. CD63 was furthermore required for efficient internalization of VEGFR2 in response to VEGF. Importantly, systemic delivery of VEGF failed to potently induce VEGFR2 phosphorylation and downstream signaling in CD63-deficient mouse lungs. Taken together, our findings demonstrate a previously unrecognized role for CD63 in coordinated integrin and receptor tyrosine kinase signaling in vitro and in vivo. 相似文献
7.
Rika Tanaka Yutaka Seki Yohei Saito Sadahiro Kamiya Motomichi Fujita Hiroaki Okutsu Takuya Iyoda Tatsuya Takai Toshiyuki Owaki Hirofumi Yajima Junichi Taira Ryo Hayashi Hiroaki Kodama Takuya Matsunaga Fumio Fukai 《The Journal of biological chemistry》2014,289(25):17699-17708
Tenascin-C is an adhesion modulatory matrix protein that is highly expressed in tumors; however, its biochemical activity involved in tumorigenesis is not fully understood. On the other hand, increasing evidence indicates the importance of integrin α5β1 in cancer development. We previously demonstrated that tenascin-C harbors a functional site that can be released as a proadhesive peptide such as TNIIIA2. Peptide TNIIIA2 is capable of inducing activation of β1-integrins including α5β1 via syndecan-4. In this study the proadhesive effect of TNIIIA2 was characterized by potentiated and sustained activation of integrin α5β1. Based on this effect, TNIIIA2 rendered nontransformed fibroblasts (NIH3T3) resistant to serum deprivation-elicited anoikis through activation of the Akt/Bcl-2 pathway. Moreover, TNIIIA2 hyperstimulated PDGF-dependent proliferation of NIH3T3 by activating integrin α5β1. Tenascin-C, a parental protein of TNIIIA2, also stimulated PDGF-dependent proliferation, which was blocked by a matrix metalloproteinase-2/9 inhibitor and an anti-TNIIIA2 function-blocking antibody, suggesting proteolytic exposure of the proadhesive effect of TNIIIA2. Mechanistic analyses revealed that TNIIIA2 induced a lateral association of PDGF receptor β with the molecular complex of activated integrin α5β1 and syndecan-4 in the membrane microdomains enriched with cholesterol/caveolin-1, resulting in prolonged activation of PDGF receptor β and the subsequent Ras/mitogen-activated protein kinase pathway in a PDGF-dependent manner. Of note, TNIIIA2 induced continuous proliferation in NIH3T3 in an integrin α5β1-dependent manner even after they formed a confluent monolayer. Thus, it was proposed that tenascin-C might be involved in deregulated cell growth through potentiated and sustained activation of integrin α5β1 after exposure of the proadhesive effect of TNIIIA2. 相似文献
8.
Background
Tetracycline exerts neuroprotection via suppressing the local inflammation induced by cerebral ischemia. However, the underlying mechanism is not completely clear.Methodology/Principal Findings
The mRNA and protein expressions of tumor necrosis factor α and interleukin 6 and the number of activated microglia were measured to detect the inflammatory process in the ischemic hemisphere. The key proteins of nuclear factor kappa B pathway and the binding activity of nuclear factor kappa B were also measured. Two key components of autophagy, Beclin 1 and LC3, were detected by western blotting. Pretreatment with tetracycline inhibited the mRNA and protein expressions of tumor necrosis factor α and interleukin 6 and decreased the numbers of activated and phagocytotic microglia. Tetracycline down regulated the total and phosphorylated expressions of IKK, IκB and p65 (P<0.05). The autophagy inhibitor, 3-methyladenine, inhibited inflammation and activation of nuclear factor kappa B pathway. The levels of Beclin 1 and LC3 were decreased by 3-methyladenine and tetracycline.Conclusions/Significance
Our data suggested that pretreatment of tetracycline may inhibit autophagy in the ischemic stroke brain and then suppress the inflammatory process via inhibiting the activation of nuclear factor kappa B pathway. 相似文献9.
Pearl Lee Daniel V. Bax Marcela M. M. Bilek Anthony S. Weiss 《The Journal of biological chemistry》2014,289(3):1467-1477
Tropoelastin protein monomers assemble to form elastin. Cellular integrin αVβ3 binds RKRK at the C-terminal tail of tropoelastin. We probed cell interactions with tropoelastin by deleting the RKRK sequence to identify other cell-binding interactions within tropoelastin. We found a novel human dermal fibroblast attachment and spreading site on tropoelastin that is located centrally in the molecule. Inhibition studies demonstrated that this cell adhesion was not mediated by either elastin-binding protein or glycosaminoglycans. Cell interactions were divalent cation-dependent, indicating integrin dependence. Function-blocking monoclonal antibodies revealed that αV integrin(s) and integrin αVβ5 specifically were critical for cell adhesion to this part of tropoelastin. These data reveal a common αV integrin-binding theme for tropoelastin: αVβ3 at the C terminus and αVβ5 at the central region of tropoelastin. Each αV region contributes to fibroblast attachment and spreading, but they differ in their effects on cytoskeletal assembly. 相似文献
10.
Anna Valeria Samarelli Elena Riccitelli Laura Bizzozero Tatiana Nunes Silveira Giorgio Seano Margherita Pergolizzi Grazia Vitagliano Ilaria Cascone Gilles Carpentier Alessia Bottos Luca Primo Federico Bussolino Marco Arese 《The Journal of biological chemistry》2014,289(28):19466-19476
The synaptic protein Neuroligin 1 (NLGN1), a cell adhesion molecule, is critical for the formation and consolidation of synaptic connectivity and is involved in vascular development. The mechanism through which NLGN1 acts, especially in vascular cells, is unknown. Here, we aimed at deepening our knowledge on the cellular activities and molecular pathways exploited by endothelial NLGN1 both in vitro and in vivo. We analyzed the phenotypic consequences of NLGN1 expression modulation in endothelial cells through in vitro angiogenesis assays and the mouse postnatal retinal angiogenesis model. We demonstrate that NLGN1, whereas not affecting endothelial cell proliferation or migration, modulates cell adhesion to the vessel stabilizing protein laminin through cooperation with the α6 integrin, a specific laminin receptor. Finally, we show that in vivo, NLGN1 and α6 integrin preferentially colocalize in the mature retinal vessels, whereas NLGN1 deletion causes an aberrant VE-cadherin, laminin and α6 integrin distribution in vessels, along with significant structural defects in the vascular tree. 相似文献
11.
Peroxisome proliferator-activated receptor-γ (PPAR-γ) has recently emerged as potential therapeutic agents for cerebral ischemia-reperfusion (I/R) injury because of anti-neuronal apoptotic actions. However, whether PPAR-γ activation mediates neuronal autophagy in such conditions remains unclear. Therefore, in this study, we investigated the role of PPAR-γ agonist 15-PGJ2 on neuronal autophagy induced by I/R. The expression of autophagic-related protein in ischemic cortex such as LC3-II, Beclin 1, cathepsin-B and LAMP1 increased significantly after cerebral I/R injury. Furthermore, increased punctate LC3 labeling and cathepsin-B staining occurred in neurons. Treatment with PPAR-γ agonist 15d-PGJ2 decreased not only autophagic-related protein expression in ischemic cortex, but also immunoreactivity of LC3 and cathepsin-B in neurons. Autophagic inhibitor 3-methyladenine (3-MA) decreased LC3-II levels, reduced the infarct volume, and mimicked some protective effect of 15d-PGJ2 against cerebral I/R injury. These results indicate that PPAR-γ agonist 15d-PGJ2 exerts neuroprotection by inhibiting neuronal autophagy after cerebral I/R injury. Although the molecular mechanisms underlying PPAR-γ agonist in mediating neuronal autophagy remain to be determined, neuronal autophagy may be a new target for PPAR-γ agonist treatment in cerebral I/R injury. 相似文献
12.
Andrew S. Cutting Yvette Del Rosario Rong Mu Anthony Rodriguez Andreas Till Suresh Subramani Roberta A. Gottlieb Kelly S. Doran 《The Journal of biological chemistry》2014,289(52):35711-35723
Bacterial meningitis occurs when bloodborne pathogens invade and penetrate the blood-brain barrier (BBB), provoking inflammation and disease. Group B Streptococcus (GBS), the leading cause of neonatal meningitis, can enter human brain microvascular endothelial cells (hBMECs), but the host response to intracellular GBS has not been characterized. Here we sought to determine whether antibacterial autophagy, which involves selective recognition of intracellular organisms and their targeting to autophagosomes for degradation, is activated in BBB endothelium during bacterial infection. GBS infection resulted in increased punctate distribution of GFP-microtubule-associated protein 1 light chain 3 (LC3) and increased levels of endogenous LC3-II and p62 turnover, two hallmark indicators of active autophagic flux. Infection with GBS mutants revealed that bacterial invasion and the GBS pore-forming β-hemolysin/cytolysin (β-h/c) trigger autophagic activation. Cell-free bacterial extracts containing β-h/c activity induced LC3-II conversion, identifying this toxin as a principal provocative factor for autophagy activation. These results were confirmed in vivo using a mouse model of GBS meningitis as infection with WT GBS induced autophagy in brain tissue more frequently than a β-h/c-deficient mutant. Elimination of autophagy using Atg5-deficient fibroblasts or siRNA-mediated impairment of autophagy in hBMECs led to increased recovery of intracellular GBS. However, electron microscopy revealed that GBS was rarely found within double membrane autophagic structures even though we observed GBS-LC3 co-localization. These results suggest that although autophagy may act as a BBB cellular defense mechanism in response to invading and toxin-producing bacteria, GBS may actively thwart the autophagic pathway. 相似文献
13.
Guang Yuan Shao-Feng Yan Hao Xue Ping Zhang Jin-Tang Sun Gang Li 《The Journal of biological chemistry》2014,289(15):10607-10619
There is an urgent need for new therapeutic avenues to improve the outcome of patients with glioblastoma multiforme (GBM). Current studies have suggested that cucurbitacin I, a natural selective inhibitor of JAK2/STAT3, has a potent anticancer effect on a variety of cancer cell types. This study showed that autophagy and apoptosis were induced by cucurbitacin I. Exposure of GBM cells to cucurbitacin I resulted in pronounced apoptotic cell death through activating bcl-2 family proteins. Cells treatment with cucurbitacin I up-regulated Beclin 1 and triggered autophagosome formation and accumulation as well as conversion of LC3I to LC3II. Activation of the AMP-activated protein kinase/mammalian target of rapamycin/p70S6K pathway, but not the PI3K/AKT pathway, occurred in autophagy induced by cucurbitacin I, which was accompanied by decreased hypoxia-inducible factor 1α. Stable overexpression of hypoxia-inducible factor 1α induced by FG-4497 prevented cucurbitacin I-induced autophagy and down-regulation of bcl-2. Knockdown of beclin 1 or treatment with the autophagy inhibitor 3-methyladenine also inhibited autophagy induced by cucurbitacin I. A coimmunoprecipitation assay showed that the interaction of Bcl-2 and Beclin 1/hVps34 decreased markedly in cells treated with cucurbitacin I. Furthermore, knockdown of beclin 1 or treatment with the lysosome inhibitor chloroquine sensitized cancer cells to cucurbitacin I-induced apoptosis. Finally, a xenograft model provided additional evidence for the occurrence of cucurbitacin I-induced apoptosis and autophagy in vitro. Our findings provide new insights into the molecular mechanisms underlying cucurbitacin I-mediated GBM cell death and may provide an efficacious therapy for patients harboring GBM. 相似文献
14.
Rui Sheng Tong-Tong Zhang Valeria D. Felice Tao Qin Zheng-Hong Qin Charles D. Smith Ellen Sapp Marian Difiglia Christian Waeber 《The Journal of biological chemistry》2014,289(30):20845-20857
Sphingosine kinase 2 (SPK2) and autophagy are both involved in brain preconditioning, but whether preconditioning-induced SPK2 up-regulation and autophagy activation are linked mechanistically remains to be elucidated. In this study, we used in vitro and in vivo models to explore the role of SPK2-mediated autophagy in isoflurane and hypoxic preconditioning. In primary mouse cortical neurons, both isoflurane and hypoxic preconditioning induced autophagy. Isoflurane and hypoxic preconditioning protected against subsequent oxygen glucose deprivation or glutamate injury, whereas pretreatment with autophagy inhibitors (3-methyladenine or KU55933) abolished preconditioning-induced tolerance. Pretreatment with SPK2 inhibitors (ABC294640 and SKI-II) or SPK2 knockdown prevented preconditioning-induced autophagy. Isoflurane also induced autophagy in mouse in vivo as shown by Western blots for LC3 and p62, LC3 immunostaining, and electron microscopy. Isoflurane-induced autophagy in mice lacking the SPK1 isoform (SPK1−/−), but not in SPK2−/− mice. Sphingosine 1-phosphate and the sphingosine 1-phosphate receptor agonist FTY720 did not protect against oxygen glucose deprivation in cultured neurons and did not alter the expression of LC3 and p62, suggesting that SPK2-mediated autophagy and protections are not S1P-dependent. Beclin 1 knockdown abolished preconditioning-induced autophagy, and SPK2 inhibitors abolished isoflurane-induced disruption of the Beclin 1/Bcl-2 association. These results strongly indicate that autophagy is involved in isoflurane preconditioning both in vivo and in vitro and that SPK2 contributes to preconditioning-induced autophagy, possibly by disrupting the Beclin 1/Bcl-2 interaction. 相似文献
15.
Diabetes impairs physiological angiogenesis by molecular mechanisms that are not fully understood. Methylglyoxal (MGO), a metabolite of glycolysis, is increased in patients with diabetes. This study defined the role of MGO in angiogenesis impairment and tested the mechanism in diabetic animals. Endothelial cells and mouse aortas were subjected to Western blot analysis of vascular endothelial growth factor receptor 2 (VEGFR2) protein levels and angiogenesis evaluation by endothelial cell tube formation/migration and aortic ring assays. Incubation with MGO reduced VEGFR2 protein, but not mRNA, levels in a time and dose dependent manner. Genetic knockdown of the receptor for advanced glycation endproducts (RAGE) attenuated the reduction of VEGFR2. Overexpression of Glyoxalase 1, the enzyme that detoxifies MGO, reduced the MGO-protein adducts and prevented VEGFR2 reduction. The VEGFR2 reduction was associated with impaired angiogenesis. Suppression of autophagy either by inhibitors or siRNA, but not of the proteasome and caspase, normalized both the VEGFR2 protein levels and angiogenesis. Conversely, induction of autophagy either by rapamycin or overexpression of LC3 and Beclin-1 reduced VEGFR2 and angiogenesis. MGO increased endothelial LC3B and Beclin-1, markers of autophagy, which were accompanied by an increase of both autophagic flux (LC3 punctae) and co-immunoprecipitation of VEGFR2 with LC3. Pharmacological or genetic suppression of peroxynitrite (ONOO−) generation not only blocked the autophagy but also reversed the reduction of VEGFR2 and angiogenesis. Like MGO-treated aortas from normglycemic C57BL/6J mice, aortas from diabetic db/db and Akita mice presented reductions of angiogenesis or VEGFR2. Administration of either autophagy inhibitor ex vivo or superoxide scavenger in vivo abolished the reductions. Taken together, MGO reduces endothelial angiogenesis through RAGE-mediated, ONOO–dependent and autophagy-induced VEGFR2 degradation, which may represent a new mechanism for diabetic angiogenesis impairment. 相似文献
16.
Carmine Fedele Amrita Singh Brad J. Zerlanko Renato V. Iozzo Lucia R. Languino 《The Journal of biological chemistry》2015,290(8):4545-4551
Exosomes, cell-derived vesicles of endosomal origin, are continuously released in the extracellular environment and play a key role in intercellular crosstalk. In this study, we have investigated whether transfer of integrins through exosomes between prostate cancer (PrCa) cells occurs and whether transferred integrins promote cell adhesion and migration. Among others, we have focused on the αvβ6 integrin, which is not detectable in normal human prostate but is highly expressed in human primary PrCa as well as murine PrCa in Ptenpc−/− mice. After confirming the fidelity of the exosome preparations by electron microscopy, density gradient, and immunoblotting, we determined that the αvβ6 integrin is actively packaged into exosomes isolated from PC3 and RWPE PrCa cell lines. We also demonstrate that αvβ6 is efficiently transferred via exosomes from a donor cell to an αvβ6-negative recipient cell and localizes to the cell surface. De novo αvβ6 expression in an αvβ6-negative recipient cell is not a result of a change in mRNA levels but is a consequence of exosome-mediated transfer of this integrin between different PrCa cells. Recipient cells incubated with exosomes containing αvβ6 migrate on an αvβ6 specific substrate, latency-associated peptide-TGFβ, to a greater extent than cells treated with exosomes in which αvβ6 is stably or transiently down-regulated by shRNA or siRNA, respectively. Overall, this study shows that exosomes from PrCa cells may contribute to a horizontal propagation of integrin-associated phenotypes, which would promote cell migration, and consequently, metastasis in a paracrine fashion. 相似文献
17.
Dimitra Kalamida Ilias V. Karagounis Alexandra Giatromanolaki Michael I. Koukourakis 《PloS one》2014,9(7)
Objectives
Vasculature damage is an important contributor to the side-effects of radiotherapy. The aim of this study is to provide insights into the radiobiology of the autophagic response of endothelial cells.Methods and Materials
Human umbilical vascular endothelial cells (HUVEC) were exposed to 2 Gy of ionizing radiation (IR) and studied using confocal microscopy and western blot analysis, at 4 and 8 days post-irradiation. The role of autophagy flux in HUVEC radio-sensitivity was also examined.Results
IR-induced accumulation of LC3A+, LC3B+ and p62 cytoplasmic vacuoles, while in double immunostaining with lysosomal markers (LAMP2a and CathepsinD) repression of the autophagolysosomal flux was evident. Autophagy-related proteins (ATF4, HIF1α., HIF2α, Beclin1) were, however, induced excluding an eventual repressive effect of radiation on autophagy initiating protein expression. Exposure of HUVEC to SMER28, an mTOR-independent inducer of autophagy, enhanced proLC3 and LC3A, B-I protein expression and accelerated the autophagic flux. Pre-treatment of HUVEC with SMER28 protected against the blockage of autophagic flux induced by IR and conferred radio-resistance. Suppression of LC3A/LC3B proteins with siRNAs resulted in radio-sensitization.Conclusions
The current data provide a rationale for the development of novel radioprotection policies targeting the autophagic pathway. 相似文献18.
Stephen D. Robinson Louise E. Reynolds Vassiliki Kostourou Andrew R. Reynolds Rita Gra?a da Silva Bernardo Tavora Marianne Baker John F. Marshall Kairbaan M. Hodivala-Dilke 《The Journal of biological chemistry》2009,284(49):33966-33981
Both vascular endothelial growth factor receptors (VEGFR) and integrins are major regulators of VEGF-induced angiogenesis. Previous work has shown that β3 integrin can regulate negatively VEGFR2 expression. Here we show that β3 integrin can regulate negatively VEGF-mediated angiogenesis by limiting the interaction of the co-receptor NRP1 (neuropilin-1) with VEGFR2. In the presence of αvβ3 integrin, NRP1 contributed minimally to VEGF-induced angiogenic processes in vivo, ex vivo, and in vitro. Conversely, when β3 integrin expression is absent or low or its function is blocked with RGD-mimetic inhibitors, VEGF-mediated responses became NRP1-dependent. Indeed, combined inhibition of β3 integrin and NRP1 decreased VEGF-mediated angiogenic responses further than individual inhibition of these receptors. We also show that αvβ3 integrin can associate with NRP1 in a VEGF-dependent fashion. Our data suggest that β3 integrin may, in part, negatively regulate VEGF signaling by sequestering NRP1 and preventing it from interacting with VEGFR2. 相似文献
19.
Zhilun Li Hongquan Zhang Lars Lundin Minna Thullberg Yajuan Liu Yunling Wang Lena Claesson-Welsh Staffan Str?mblad 《The Journal of biological chemistry》2010,285(31):23699-23710
Modulation of integrin αvβ5 regulates vascular permeability, angiogenesis, and tumor dissemination. In addition, we previously found a role for p21-activated kinase 4 (PAK4) in selective regulation of integrin αvβ5-mediated cell motility (Zhang, H., Li, Z., Viklund, E. K., and Strömblad, S. (2002) J. Cell Biol. 158, 1287–1297). This report focuses on the molecular mechanisms of this regulation. We here identified a unique PAK4-binding membrane-proximal integrin β5-SERS-motif involved in controlling cell attachment and migration. We also mapped the integrin β5-binding site within PAK4. We found that PAK4 binding to integrin β5 was not sufficient to promote cell migration, but that PAK4 kinase activity was required for PAK4 promotion of cell motility. Importantly, PAK4 specifically phosphorylated the integrin β5 subunit at Ser-759 and Ser-762 within the β5-SERS-motif. Point mutation of these two serine residues abolished the PAK4-induced cell migration, indicating a functional role for these phosphorylations in migration. Our results may give important leads to the functional regulation of integrin αvβ5, with implications for vascular permeability, angiogenesis, and cancer dissemination. 相似文献