Cytokeratin 18-mediated disorganization of intermediate filaments is induced by degradation of plectin in human liver cells |
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Authors: | Yi-Hsiang Liu Chin-Chin Ho Chiung-Chi Cheng Wei-Ting Chao Ren-Jeng Pei Yung-Hsiang Hsu Yih-Shyong Lai |
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Institution: | aDepartment of Pathology, Chang Bing Show Chwan Memorial Hospital, Changhua, Taiwan;bDepartment of Pathology, Tzu Chi University, Hualien, Taiwan;cDepartment of Nursing, Central Taiwan University of Science and Technology, Taichung, Taiwan;dDepartment of Medical Research, Chang Bing Show Chwan Memorial Hospital, Changhua, Taiwan;eDepartment of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX, USA;fYongsin Pathological Center, Taichung, Taiwan |
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Abstract: | Plectin is a cross-linking protein that organizes the cytoskeleton into a stable meshwork that helps maintain the uniform size and shape of cells. As cells of hepatocellular carcinoma are morphologically different from healthy human hepatocytes, we hypothesized that plectin deficiency and cytoskeletal disorganization underlies this pleomorphic transformation. To test this hypothesis we induced apoptosis as the most accessible pathway for creating plectin deficiency status in vivo. We analyzed expression levels and organization of plectin and other cytoskeletal elements, including intermediate filaments, microfilaments, and microtubules, after staurosporine-induced apoptosis in human Chang liver cells. The results revealed the expression of plectin and cytokeratin 18 were downregulated in hepatocellular carcinoma tissues in vivo. The expression of actin and tubulin, however, were not altered. In vitro analysis indicated that plectin and cytokeratin 18 were cleaved following staurosporine-treatment of human Chang liver cells. Time course experiments revealed that plectin was cleaved 2 h earlier than cytokeratin 18. The organization of plectin and cytokeratin 18 networks collapsed after staurosporine-treatment. Conclusively, degradation of plectin induced by staurosporine-treatment in liver cells resulted in cytoskeleton disruption and induced morphological changes in these cells by affecting the expression and organization of cytokeratin 18. |
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Keywords: | Abbreviations: MT microtubule MF microfilament IF intermediate filament CK cytokeratin IFAP intermediate filament associated protein HCC hepatocellular carcinoma HRP horseradish peroxidase DMEM Dulbecco&rsquo s minimum essential medium FBS fetal bovine serum siRNA small interfering RNA PBS phosphate-buffered saline FITC fluorescein-conjugated isothiocyanate SDS sodium dodecyl sulfate PVDF polyvinylidene fluoride STS staurosporine DMSO dimethyl sulfoxide BSA bovine serum albumin SDS&ndash PAGE sodium dodecyl sulfate&ndash polyacrylamide gel electrophoresis |
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