Regulation of membrane trafficking by Coronins

摘要 冠状蛋白的广泛家族在调节肌动蛋白方面起着重要作用。 推动细胞迁移、极性、细胞形状和细胞内运输的网络，以及 从而促进了从先天免疫到 神经元信号。然而，这些职能和活动的特点是 经典的冠冕。与之形成鲜明对比的是，我们几乎对细胞 不同结构类串联蛋白的作用和肌动蛋白细胞骨架调节 Coronins，由Coronin7(Coro7)、POD-1和Corb组成。我们的初步数据 表明哺乳动物Coro7可以控制Arp2/3介导的成核，尽管 这种活动背后的机制仍然难以捉摸。此外，我们还证明了这个肌动蛋白- 调节活性可以调节NPF诱导的肌动蛋白网络，从而驱动细胞内 膜运输，包括自噬，这是细胞用来处理 不需要的细胞器，错误折叠的蛋白质和有毒的聚集体。使用多学科 包括最先进的生化、生物物理、遗传和活体成像的方法 我们在这里提出的技术是为了阐明1)Coro7如何在结构上与Arp2/3相互作用， 2)Coro7如何通过成核机制抑制Arp2/3介导的成核 促进因子，以及3)其他Arp2/3调节因子，以及4)这些肌动蛋白如何调节 Coro7的活动调节分支肌动蛋白网络的周转 自噬。

ABSTRACT The extensive family of the Coronins plays an important role in regulating the actin networks that drive cell migration, polarity, cell shape and intracellular trafficking, and thereby contribute to essential biological processes ranging from innate immunity to neuronal signaling. However, these functions and activities have been characterized for the canonical Coronins. In stark contrast, we know next to nothing about the cellular roles and actin cytoskeleton regulation of the structurally distinct class of the tandem Coronins, which comprises Coronin 7 (Coro7), POD-1, and CorB. Our preliminary data show that mammalian Coro7 can control Arp2/3-mediated nucleation, although the mechanism underlying this activity remains elusive. In addition, we show that this actin- regulatory activity can regulate NPF-induced actin networks that drive intracellular membrane transport, including autophagy, a process used by cells to dispose of unwanted organelles, misfolded proteins and toxic aggregates. Using a multidisciplinary approach comprising state-of-the-art biochemical, biophysical, genetic and live-imaging techniques we propose here to elucidate 1) how Coro7 structurally interacts with Arp2/3, 2) how Coro7 mechanistically inhibits Arp2/3-mediated nucleation by nucleation promoting factors, and 3) by other Arp2/3 regulators, and 4) how these actin-regulatory activities of Coro7 regulate the turnover of the branched actin networks that drive autophagy.