Stomach-specific calpain, nCL-2, localizes in mucus cells and proteolyzes the β-subunit of coatomer complex, β-COP
Stomach-specific calpain, nCL-2, localizes in mucus cells and proteolyzes the β-subunit of coatomer complex, β-COP
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DOI：
10.1074/jbc.m509244200
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发表时间：
2006-04-21
影响因子：
4.8
通讯作者：
Sorimachi, H
中科院分区：
文献类型：
--
作者：
Hata, S;Koyama, S;Sorimachi, H
Calpain 是一种 Ca2+ 调节的胞质蛋白酶。哺乳动物有 14 个钙蛋白酶基因，其中一半主要在特定器官中表达；其余的表达无处不在。钙蛋白酶的缺陷会导致致命性/致病性，表明它们的生理学不可或缺性。 nCL-2/calpain-8a被鉴定为胃特异性钙蛋白酶，其生理功能尚不清楚。为了阐明这些，我们详细描述了 nCL-2。出乎意料的是，nCL-2 严格定位于胃上皮表面粘液细胞和十二指肠中分泌粘液的杯状细胞。酵母双杂交筛选鉴定出几种 nCL-2 诱导分子。其中，外套异构体复合物的 β 亚基 (β-COP) 存在于胃凹细胞中，并在体外被 nCL-2 蛋白水解。此外，β-COP 和 nCL-2 在共定位于高尔基体的 COS7 细胞中共表达，Ca2+-离子载体刺激导致连接区附近的 β-COP 蛋白水解，导致 β-COP 从高尔基体解离。这些结果强烈表明 nCL-2 的新功能涉及通过与外壳蛋白相互作用进行粘液细胞的膜运输。
Calpain is a Ca2+-regulated cytosolic protease. Mammals have 14 calpain genes, half of which are predominantly expressed in specific organ(s); the rest are expressed ubiquitously. A defect in calpains causes lethality/pathogenicity, indicating their physiological indispensability. nCL-2/calpain-8a was identified as a stomach-specific calpain, whose physiological functions are unclear. To elucidate these, we characterized nCL-2 in detail. Unexpectedly, nCL-2 was localized strictly to the surface mucus cells in the gastric epithelium and the mucus-secreting goblet cells in the duodenum. Yeast two-hybrid screening identified several nCL-2-intracting molecules. Of these, the beta-subunit of coatomer complex (beta-COP) occurs in the stomach pit cells and is proteolyzed by nCL-2 in vitro. Furthermore, beta-COP and nCL-2 co-expressed in COS7 cells co-localized in the Golgi, and Ca2+-ionophore stimulation caused the proteolysis of beta-COP near the linker region, resulting in the dissociation of beta-COP from the Golgi. These results strongly suggest novel functions for nCL-2 that involve the membrane trafficking of mucus cells via interactions with coat protein.