Thrombospondin modulates alpha v beta 3 function through integrin-associated protein.
Thrombospondin modulates alpha v beta 3 function through integrin-associated protein.
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DOI：
10.1083/jcb.135.2.533
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发表时间：
1996-10
期刊：
影响因子：
--
通讯作者：
Frazier WA
中科院分区：
文献类型：
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作者：
Gao AG;Lindberg FP;Dimitry JM;Brown EJ;Frazier WA
整合素相关蛋白（IAP）是血小板反应蛋白1（TS 1）的羧基末端“细胞结合结构域”（CBD）的受体。IAP与α v β 3整联蛋白结合，针对IAP的mAb抑制某些整联蛋白功能。在这里，我们研究了TS 1 CBD和4 N1 K（KRFYVVMWKK），一种来自它的细胞结合肽，对表达IAP，α v β 3和α v β 5的C32人黑色素瘤细胞的玻连蛋白（VN）的粘附和扩散的影响。细胞通过α v β 5粘附到低表面密度的VN上，并且扩散非常缓慢，而粘附到较高密度的VN上涉及α v β 5和α v β 3两者，并且导致快速扩散。通过可溶性TS 1、重组CBD和4 N1 K的存在显著增强了细胞在稀疏VN涂层上的扩散，但没有粘附，但不能结合IAP的“突变”肽4 NGG、KRFYGGMWKK没有增强。这种增强的扩散被抗α v β 3的mAb LM 609和抗IAP mAb B6 H12完全阻断。与这种增强的扩散相关的是粘着斑激酶（FAK）、桩蛋白和ca. 90 kD。由TS 1和4 N1 K诱导的增强的铺展和在较高密度VN上的组成性铺展都被calphostin C（100 nM）、渥曼青霉素（10 nM）和酪氨酸激酶抑制剂阻断。相比之下，百日咳毒素特异性地仅阻断TS 1刺激的在低密度VN上的扩散，表明IAP通过异源三聚体Gi蛋白对信号转导发挥作用，所述异源三聚体Gi蛋白作用于包括PI-3激酶、PKC和酪氨酸激酶的常见细胞扩散途径的上游。
Integrin-associated protein (IAP) is a receptor for the carboxyl- terminal "cell-binding domain" (CBD) of thrombospondin 1 (TS1). IAP associates with alpha v beta 3 integrin and mAbs against IAP inhibit certain integrin functions. Here we examine the effects of the TS1 CBD and 4N1K (KRFYVVMWKK), a cell-binding peptide derived from it, on the adhesion and spreading on vitronectin (VN) of C32 human melanoma cells which express IAP, alpha v beta 3, and alpha v beta 5. Cells adhere to VN at low surface densities via alpha v beta 5 and spread very slowly while adhesion to higher density VN involves both alpha v beta 5 and alpha v beta 3 and results in rapid spreading. Spreading of the cells, but not adhesion, on sparse VN coatings is markedly enhanced by the presence of soluble TS1, the recombinant CBD and 4N1K, but not the "mutant" peptide 4NGG, KRFYGGMWKK, which fails to bind IAP. This enhanced spreading is completely blocked by mAb LM609 against alpha v beta 3 and the anti-IAP mAb B6H12. Correlated with this enhanced spreading is increased tyrosine phosphorylation of focal adhesion kinase (FAK), paxillin, and a protein of ca. 90 kD. The enhanced spreading induced by TS1 and 4N1K and the constitutive spreading on higher density VN are both blocked by calphostin C (100 nM), wortmannin (10 nM), and tyrosine kinase inhibitors. In contrast, pertussis toxin specifically blocks only the TS1 stimulated spreading on low density VN, indicating that IAP exerts its effects on signal transduction via a heterotrimeric Gi protein acting upstream of a common cell spreading pathway which includes PI-3 kinase, PKC, and tyrosine kinases.