STRUCTURE AND ASSEMBLY OF DESMOSOME JUNCTIONS - BIOSYNTHESIS AND TURNOVER OF THE MAJOR DESMOSOME COMPONENTS OF MADIN-DARBY CANINE KIDNEY-CELLS IN LOW CALCIUM MEDIUM
STRUCTURE AND ASSEMBLY OF DESMOSOME JUNCTIONS - BIOSYNTHESIS AND TURNOVER OF THE MAJOR DESMOSOME COMPONENTS OF MADIN-DARBY CANINE KIDNEY-CELLS IN LOW CALCIUM MEDIUM
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DOI：
10.1083/jcb.105.5.2327
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发表时间：
1987-11-01
影响因子：
7.8
通讯作者：
REES, DA
中科院分区：
文献类型：
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作者：
PENN, EJ;BURDETT, IDJ;REES, DA
在低钙培养基（LCM; < 0.1 mM）中，分层（原代角质形成细胞）和简单（Madin-Darby犬肾[MDCK]）以及Madin-Darby牛肾[MDBK]上皮细胞类型均不形成桥粒，但可通过将钙水平升高至生理浓度（标准钙培养基[SCM]，2 mM）来诱导它们形成桥粒。我们已经使用了多克隆抗血清的主要牛表皮桥粒成分（> 100 kD）在一个敏感的测定涉及免疫沉淀的成分代谢标记的MDCK细胞单层研究钙诱导的桥粒形成的机制。MDCK细胞，无论是在LCM或SCM中培养，被发现合成桥粒蛋白，DPI和桥粒糖蛋白DGI和DGII/III具有相同的电泳迁移率，并且在相关的情况下，具有相似的碳水化合物添加/加工和蛋白水解加工。这些事件的时间和DGI运输到细胞表面的时间在低钙和高钙中是相似的。虽然各种桥粒成分的合成速率在两种条件下也是相似的，但在LCM中培养的细胞中糖蛋白周转率显著增加。DGI和DGII/III的半衰期分别降低了约7倍和12倍，与此一致，在SCM中标记48小时的MDCK细胞的DGI和DGII/III的量分别是LCM中标记48小时的细胞的3倍和6倍。人员更替率和新闻部的水平也朝同一方向变化，但变化程度要小得多。根据这一新的证据，Ca 2+依赖的控制桥粒形成的可能机制进行了讨论。
Neither stratifying (primary keratinocytes) nor simple (Madin-Darby canine kidney [MDCK]) and Madin-Darby bovine kidney [MDBK] epithelial cell types form desmosomes in low calcium medium (LCM; < 0.1 mM), but they can be induced to do so by raising the calcium level to physiological concentrations (standard calcium medium [SCM], 2 mM). We have used polyclonal antisera to the major bovine epidermal desmosome components (> 100 kD) in a sensitive assay involving immunoprecipitation of the components from metabolically labeled MDCK cell monolayers to investigate the mechanism of calcium-induced desmosome formation. MDCK cells, whether cultured in LCM or SCM, were found to synthesize the desmosome protein, DPI and desmosome glycoproteins DGI and DGII/III with identical electrophoretic mobility, and also, where relevant, with similar carbohydrate addition/processing and proteolytic processing. The timings of these events and of transport of DGI to the cell surface were similar in low and high calcium. Although the rates of synthesis of the various desmosome components were also similar under both conditions, the glycoprotein turnover rates increased dramatically in cells cultured in LCM. The half-lives decreased by a factor of about 7 for DGI and 12 for DGII/III and, consistent with this, MDCK cells labeled for 48 h in SCM had three and six times the amount of DGI and DGII/III, respectively, as cells labeled for 48 h in LCM. The rate of turnover and the levels of DPI were changed in the same direction, but to much lesser extents. Possible mechanisms for the Ca2+-dependent control of desmosome formation are discussed in the light of this new evidence.