SIGNAL TRANSDUCTION PATHWAYS INVOLVED IN VASCULAR SMOOTH MUSCLE CELL MIGRATION

血管的迁移 平滑肌细胞（VSMCs）是一个关键事件的发病机制， 许多血管疾病。我们之前的研究表明， PDGF引导的VSMC迁移的分化状态， 碱性FGF（FGF-2）的可用性是通过其特异性介导的。 对钙/钙调素依赖蛋白激活的影响 激酶II（CamKII）。我们目前的工作重点是确定 CamKII的细胞内靶点、其上游调控及其 在β 3整合素介导的信号传导中的独特作用。我们已经表明 CamKII需要β 3整联蛋白复合物的占据 激活和VSMC迁移以及β 3 整合素通过FGF 2依赖性信号传导至CamKII 通路此外，我们已经证明， 血小板反应蛋白（TSP）和整合素相关蛋白（IAP）， 它是C-末端的主要细胞表面结合位点 TSP的结合结构域（CBD），也阻止了迁移， β 3整合素和CamK Ⅱ依赖性途径。CaMKII 信号传导和PDGF介导的迁移也缺乏IAP-/- 通过表达克服迁移缺陷的小鼠 CamKII的组成型活性突变体。这些研究表明 TSP、IAP和β 3整合素形成信号复合物， 通过激活CamKII整合细胞外信号。一 CamKII的重要细胞内靶点之一是肌球蛋白轻链 链激酶（MCLK），其活性被抑制 CamKII因此，MLCK的药理学抑制 在β 3整合素阻断的 VSMC和IAP-/-肺成纤维细胞。这些结果确定了一个独特的 VSMC中迁移的细胞内信号网络， 整合由化学引诱物识别触发的事件， 受生长状态、生长因子、细胞外 矩阵，和ECM-VSMC相互作用。

SUMMARY OF WORK The migration of vascular smooth muscle cells (VSMCs) is a key event in the pathogenesis of many vascular diseases. We previously showed that the regulation of PDGF-directed VSMC migration by differentiation status and basic FGF (FGF-2) availability is specifically mediated through their effects on the activation of calcium/calmodulin-dependent protein kinase II (CamKII). Our current work is focussed on identifyingthe intracellular targets for CamKII, its upstream regulation, and its unique role in beta3 integrin-mediated signaling. We have shown that occupancy of beta3 integrin complexes is required for CamKII activation and VSMC migration and that signaling from beta3 integrins to CamKII occurs through a FGF2-dependent signaling pathway. In addition, we have shown that antibodies against thrombospondin (TSP) and integrin-associated protein (IAP), which is the major cell surface binding site for the C-terminal binding domain (CBD) of TSP, also block migration though the beta3 integrin- and CamKII- dependent pathways. CamKII signaling and PDGF-directed migration are also deficient in IAP-/- mice with the deficiency in migration overcome through expression of a constitutively active mutant of CamKII. These studies show that TSP, IAP, and beta3 integrins form a signaling complex that integrates extracellular signals through activation of CamKII. One of the important intracellular targets of CamKII is myosin light chain kinase (MCLK), the activity of which is suppressed by CamKII. Accordingly, pharmacological inhibition of MLCK restores PDGF-directed migration in beta3 integrin-blocked VSMCs and IAP-/- lung fibroblasts. These results identify a unique intracellular signalling network for migration in VSMCs that integrates events triggered by chemoattractant recognition and modulated by growth status, growth factors, the extracellular matrix, and ECM-VSMC interactions.