Queensland Brain Institute, The University of Queensland, Brisbane, Queensland 4072, Australia.
J Cell Biol. 2013 Feb 4;200(3):301-20. doi: 10.1083/jcb.201204092.
Before undergoing neuroexocytosis, secretory granules (SGs) are mobilized and tethered to the cortical actin network by an unknown mechanism. Using an SG pull-down assay and mass spectrometry, we found that myosin VI was recruited to SGs in a Ca(2+)-dependent manner. Interfering with myosin VI function in PC12 cells reduced the density of SGs near the plasma membrane without affecting their biogenesis. Myosin VI knockdown selectively impaired a late phase of exocytosis, consistent with a replenishment defect. This exocytic defect was selectively rescued by expression of the myosin VI small insert (SI) isoform, which efficiently tethered SGs to the cortical actin network. These myosin VI SI-specific effects were prevented by deletion of a c-Src kinase phosphorylation DYD motif, identified in silico. Myosin VI SI thus recruits SGs to the cortical actin network, potentially via c-Src phosphorylation, thereby maintaining an active pool of SGs near the plasma membrane.
在神经外排发生之前，分泌颗粒（SGs）通过未知机制被动员并与皮质肌动蛋白网络连接。使用 SG 下拉测定法和质谱法，我们发现肌球蛋白 VI 以 Ca2+依赖的方式被募集到 SG 上。在 PC12 细胞中干扰肌球蛋白 VI 功能会降低 SG 在质膜附近的密度，而不影响它们的发生。肌球蛋白 VI 敲低选择性地损害了胞吐作用的晚期阶段，这与补充缺陷一致。这种胞吐缺陷通过表达肌球蛋白 VI 小插入（SI）同工型得到了选择性挽救，该同工型有效地将 SG 与皮质肌动蛋白网络连接起来。肌球蛋白 VI SI 的这些特定效应通过在计算机中鉴定的 c-Src 激酶磷酸化 DYD 基序的缺失而被阻止。因此，肌球蛋白 VI SI 将 SG 招募到皮质肌动蛋白网络，可能通过 c-Src 磷酸化，从而维持质膜附近的活跃 SG 池。
Zotero 插件
