Cleavage of βcatenin and plakoglobin and shedding of VE-cadherin during endothelial apoptosis:: Evidence for a role for caspases and metalloproteinases
Cleavage of βcatenin and plakoglobin and shedding of VE-cadherin during endothelial apoptosis:: Evidence for a role for caspases and metalloproteinases
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DOI：
10.1091/mbc.9.6.1589
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发表时间：
1998-06-01
影响因子：
3.3
通讯作者：
Ross, R
中科院分区：
文献类型：
--
作者：
Herren, B;Levkau, B;Ross, R
内皮细胞的生长因子剥夺诱导凋亡，其特征在于膜起泡、细胞变圆以及随后的细胞-基质和细胞-细胞接触的丧失。在这项研究中，我们发现，内皮细胞凋亡的启动与粘附连接的细胞内和细胞外成分的裂解和分解相关。β-连环蛋白和斑珠蛋白在凋亡细胞中被切割，它们在粘附连接中形成血管内皮钙粘蛋白（VE-钙粘蛋白）和肌动蛋白结合α-连环蛋白之间的细胞内连接。细胞裂解物和免疫沉淀物与重组半胱天冬酶的体外孵育表明，CPP 32和Mch 2参与，可能是通过启动蛋白水解加工。来自凋亡细胞裂解物的切割的β-连环蛋白不与内源性α-连环蛋白结合，而斑珠蛋白保留其结合能力。在细胞凋亡过程中，粘附连接的细胞外部分也发生了变化，因为介导内皮细胞-细胞相互作用的VE-钙粘蛋白在细胞表面上显著减少。在条件培养基中可以检测到VE-钙粘蛋白的细胞外片段，并且VE-钙粘蛋白的这种“脱落”可以被金属蛋白酶的抑制剂阻断。因此，β-连环蛋白和斑珠蛋白的切割以及VE-钙粘蛋白的脱落可能共同作用，破坏粘附连接的结构和信号传导特性，并可能主动中断内皮细胞存活所需的细胞外信号。
Growth factor deprivation of endothelial cells induces apoptosis, which is characterized by membrane blebbing, cell rounding, and subsequent loss of cell-matrix and cell-cell contacts. In this study, we show that initiation of endothelial apoptosis correlates with cleavage and disassembly of intracellular and extracellular components of adherens junctions. beta-Catenin and plakoglobin, which form intracellular links between vascular endothelial cadherin (VE-cadherin) and actin-binding alpha-catenin in adherens junctions, are cleaved in apoptotic cells. In vitro incubations of cell lysates and immunoprecipitates with recombinant caspases indicate that CPP32 and Mch2 are involved, possibly by initiating proteolytic processing. Cleaved beta-catenin from lysates of apoptotic cells does not bind to endogenous alpha-catenin, whereas plakoglobin retains its binding capacity. The extracellular portion of the adherens junctions is also altered during apoptosis because VE-cadherin, which mediates endothelial cell-cell interactions, dramatically decreases on the surface of cells. An extracellular fragment of VE-cadherin can be detected in the conditioned medium, and this "shedding" of VE-cadherin can be blocked by an inhibitor of metalloproteinases. Thus, cleavage of beta-catenin and plakoglobin and shedding of VE-cadherin may act in concert to disrupt structural and signaling properties of adherens junctions and may actively interrupt extracellular signals required for endothelial cell survival.