Eriksson J E, Brautigan D L, Vallee R, Olmsted J, Fujiki H, Goldman R D
Department of Cell, Molecular, and Structural Biology, Northwestern University Medical School, Chicago, IL 60611-3008.
Proc Natl Acad Sci U S A. 1992 Nov 15;89(22):11093-7. doi: 10.1073/pnas.89.22.11093.
Phosphorylation by protein kinases has been established as a key factor in the regulation of cytoskeletal structure. However, little is known about the role of protein phosphatases in cytoskeletal regulation. To assess the possible functions of protein phosphatases in this respect, we studied the effects of the phosphatase inhibitors calyculin A, okadaic acid, and dinophysistoxin 1 (35-methylokadaic acid) on BHK-21 fibroblasts. Within minutes of incubation with these inhibitors, changes are seen in the structural organization of intermediate filaments, followed by a loss of microtubules, as assayed by immunofluorescence. These changes in cytoskeletal structure are accompanied by a rapid and selective increase in vimentin phosphorylation on interphase-specific sites, and they are fully reversible after removal of calyculin A. The results indicate that there is a rapid phosphate turnover on cytoskeletal intermediate filaments and further suggest that protein phosphatases are essential for the maintenance and structural integrity of two major cytoskeletal components.
蛋白激酶的磷酸化作用已被确认为调节细胞骨架结构的关键因素。然而，关于蛋白磷酸酶在细胞骨架调节中的作用却知之甚少。为了评估蛋白磷酸酶在这方面的可能功能，我们研究了磷酸酶抑制剂花萼海绵诱癌素A、冈田酸和鳍藻毒素1（35-甲基冈田酸）对BHK-21成纤维细胞的影响。在用这些抑制剂孵育几分钟内，通过免疫荧光检测发现中间丝的结构组织发生变化，随后微管丢失。细胞骨架结构的这些变化伴随着波形蛋白在间期特异性位点磷酸化的快速和选择性增加，并且在去除花萼海绵诱癌素A后这些变化是完全可逆的。结果表明细胞骨架中间丝上存在快速的磷酸盐周转，并且进一步表明蛋白磷酸酶对于两种主要细胞骨架成分的维持和结构完整性至关重要。
