Department of Medicine/ Cardiology, Deutsches Herzzentrum Berlin, Berlin, Germany.
Thromb Haemost. 2010 Mar;103(3):556-63. doi: 10.1160/TH09-07-0478. Epub 2010 Jan 13.
Integrins link the cytoskeleton to the extracellular matrix, providing outside-in/inside-out signalling essential for vascular smooth muscle cell (VSMC) migration in atherosclerosis. The integrin av subunit is synthesised from its precursor via furin-dependent endoproteolytic cleavage. Furin is a proprotein convertase (PC) highly expressed in VSMCs and in human atherosclerotic lesions. Inhibition of av processing inhibits binding to vitronectin and migration. However, the precise role of furin-dependent av cleavage on integrin bidirectional signalling and subsequent VSMC functions is unknown. Our present study demonstrates that the furin-like PC inhibitor decanoyl-RVKR-chloromethylketone (dec-CMK) inhibited av cleavage. This reduced vitronectin-induced (outside-in) focal adhesion kinase (FAK)- and paxillin-phosphorylation, and VSMC motility. Inside-out-stimulated, integrin- mediated VSMC adhesion/migration relied on integrin-adaptor protein activation following protein kinase C (PKC) and ERK1/2 phosphorylation. In contrast to outside-in signalling, PKC-dependent phosphorylation of FAK and paxillin was unaffected by the status of integrin cleavage. Still, cytoskeleton and focal adhesion site rearrangements were modulated by the inhibition of furin-dependent integrin cleavage, thereby lessening inside-out dependent migration. Hence, we find that integrin bidirectional signalling is critically controlled by furin. Furin- dependent integrin processing modulates rapid adaptive integrin/cytoskeleton changes, essential to VSMC motility, which represents a crucial component in atherosclerosis and restenosis.
整合素将细胞骨架与细胞外基质连接起来，提供了血管平滑肌细胞（VSMC）在动脉粥样硬化中迁移所必需的内外信号。整合素 av 亚基通过依赖弗林蛋白酶的内切蛋白水解从其前体合成。弗林蛋白酶是一种脯氨酸转换酶（PC），在 VSMC 和人类动脉粥样硬化病变中高度表达。av 加工的抑制抑制与 vitronectin 的结合和迁移。然而，弗林蛋白酶依赖性 av 切割对整合素双向信号传递和随后的 VSMC 功能的确切作用尚不清楚。我们目前的研究表明，弗林蛋白酶样 PC 抑制剂癸酰基-RVKR-氯甲基酮（dec-CMK）抑制了 av 切割。这减少了 vitronectin 诱导的（外向）焦点黏附激酶（FAK）和桩蛋白磷酸化，以及 VSMC 迁移。内向刺激的整合素介导的 VSMC 黏附和迁移依赖于整合素衔接蛋白激活，随后是蛋白激酶 C（PKC）和 ERK1/2 磷酸化。与外向信号相反，FAK 和桩蛋白的 PKC 依赖性磷酸化不受整合素切割状态的影响。尽管如此，细胞骨架和焦点黏附位点的重排受到依赖弗林蛋白酶的整合素切割抑制的调节，从而减少内向依赖的迁移。因此，我们发现整合素双向信号传递受到弗林蛋白酶的严格控制。依赖弗林蛋白酶的整合素加工调节快速适应的整合素/细胞骨架变化，这对 VSMC 迁移至关重要，它是动脉粥样硬化和再狭窄的关键组成部分。
