Diphosphorylated MRLC is required for organization of stress fibers in interphase cells and the contractile ring in dividing cells
Diphosphorylated MRLC is required for organization of stress fibers in interphase cells and the contractile ring in dividing cells
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DOI：
10.1247/csf.26.677
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发表时间：
2001-12-01
影响因子：
1.5
通讯作者：
Hosoya, H
中科院分区：
文献类型：
--
作者：
Iwasaki, T;Murata-Hori, M;Hosoya, H
非肌肉肌球蛋白 11 的活性受其调节轻链 (MRLC) 磷酸化的调节。在体外，与 MRLC 在 Ser19（单磷酸化）相比，MRLC 在 Thr18 和 Ser19 处的磷酸化（二磷酸化）会导致更高的 MgATPase 活性，并促进肌球蛋白 11 丝的组装。为了确定二磷酸化MRLC在体内的作用，我们转染了三种MRLC突变体，即非磷酸化、单磷酸化和二磷酸化形式（MRLC2（T18AS19A），Ser19和Thr18均被Ala取代；MRLC2（T18AS19D），Ser19被Asp取代，Thr18被Ala取代；以及MRLC2（T18DS19D） Ser19 和 Thr18 分别通过 Asp）进入 HeLa 细胞。过表达突变体MRLC2(T18DS19D)的细胞比过表达突变体MRLC2(T18AS19D)的细胞含有更多数量的肌动蛋白丝束。此外，过表达不可磷酸化突变体MRLC2（T18AS19A）的细胞显示肌动蛋白丝束数量减少。综上所述，我们的数据表明 MRLC 的二磷酸化在调节非肌肉细胞中肌动蛋白丝的组装和重组中发挥着重要作用。
Activity of nonmuscle myosin 11 is regulated by phosphorylation of its regulatory light chain (MRLC). Phosphoryration of MRLC at both Thr18 and Ser19 (diphosphorylation) results in higher MgATPase activity and in promotion of the assembly of myosin 11 filaments than does that of MRLC at Ser19 (monophosphorylation) in vitro. To determine the roles of the diphosphorylated MRLC in vivo, we transfected three kinds of MRLC mutants, unphosphorylated, monophosphorylated and diphosphorylated forms (MRLC2(T18AS19A), substitution of both Ser19 and Thr18 by Ala; MRLC2(T18AS19D), Ser19 by Asp and Thr18 by Ala; and MRLC2(T18DS19D) both Ser19 and Thr18 by Asp, respectively), into HeLa cells. Cells overexpressing the mutant MRLC2(T18DS19D) contained a larger number of actin filament bundles than did those overexpressing the mutant MRLC2(T18AS19D). Moreover, cells overexpressing the nonphosphorylatable mutant MRLC2(T18AS19A) showed a decrease in the number of actin filament bundles. Taken together, our data suggest that diphosphorylation of MRLC plays an important role in regulating actin filament assembly and reorganization in nonmuscle cells.