MYBPH inhibits NM IIA assembly via direct interaction with NMHC IIA and reduces cell motility
MYBPH inhibits NM IIA assembly via direct interaction with NMHC IIA and reduces cell motility
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DOI：
10.1016/j.bbrc.2012.10.036
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发表时间：
2012-11-09
影响因子：
3.1
通讯作者：
Takahashi, Takashi
中科院分区：
文献类型：
--
作者：
HosonoA, Yasuyuki;Usukura, Jiro;Takahashi, Takashi
肌动球蛋白丝组装是肿瘤细胞迁移的关键步骤。我们以前发现，肌球蛋白结合蛋白H（MYBPH）是直接反式激活的TTF-1谱系生存癌基因在肺腺癌和抑制磷酸化的肌球蛋白调节轻链（RLC）的非肌肉肌球蛋白IIA（NM IIA）通过直接相互作用与Rho激酶1（ROCK 1）。在这里，我们报告说，MYBPH还直接与一个额外的分子，非肌肉肌球蛋白重链IIA（NMHC IIA），这是发现发生在MYBPH和杆部分的NMHC IIA之间的相互作用。MYBPH抑制NMHC IIA组装并降低细胞运动性。相反，siMYBPH诱导的运动性增加被blebbistatin（一种非肌肉肌球蛋白II抑制剂）部分但显著抑制，而siROCK 1和blebbistatin联合治疗则获得了更深远的影响。电子显微镜观察显示，良好的有序的准晶体的NMHC IIA反映了组装状态，这是显着不太常见的MYBPH的存在下观察。此外，体外沉降测定显示，在MYBPH存在下，更大量的NMHC IIA处于未组装状态。有趣的是，用ROCK抑制剂处理，损害NM IIA从组装不胜任状态到组装胜任状态的转变，降低了MYBPH和NMHC IIA之间的相互作用，表明MYBPH对组装胜任的NM IIA具有更高的亲和力。这些结果表明，MYBPH抑制RLC和NMHC IIA，独立组件的NM IIA，并负调节肌动球蛋白组织在2个不同的步骤，导致坚定的抑制NM IIA大会。(C)2012 Elsevier Inc. All rights reserved.
Actomyosin filament assembly is a critical step in tumor cell migration. We previously found that myosin binding protein H (MYBPH) is directly transactivated by the TTF-1 lineage-survival oncogene in lung adenocarcinomas and inhibits phosphorylation of the myosin regulatory light chain (RLC) of non-muscle myosin IIA (NM IIA) via direct interaction with Rho kinase 1 (ROCK1). Here, we report that MYBPH also directly interacts with an additional molecule, non-muscle myosin heavy chain IIA (NMHC IIA), which was found to occur between MYBPH and the rod portion of NMHC IIA. MYBPH inhibited NMHC IIA assembly and reduced cell motility. Conversely, siMYBPH-induced increased motility was partially, yet significantly, suppressed by blebbistatin, a non-muscle myosin II inhibitor, while more profound effects were attained by combined treatment with siROCK1 and blebbistatin. Electron microscopy observations showed well-ordered paracrystals of NMHC IIA reflecting an assembled state, which were significantly less frequently observed in the presence of MYBPH. Furthermore, an in vitro sedimentation assay showed that a greater amount of NMHC IIA was in an unassembled state in the presence of MYBPH. Interestingly, treatment with a ROCK inhibitor that impairs transition of NM IIA from an assembly-incompetent to assembly-competent state reduced the interaction between MYBPH and NMHC IIA, suggesting that MYBPH has higher affinity to assembly-competent NM IIA. These results suggest that MYBPH inhibits RLC and NMHC IIA, independent components of NM IIA, and negatively regulates actomyosin organization at 2 distinct steps, resulting in firm inhibition of NM IIA assembly. (C) 2012 Elsevier Inc. All rights reserved.