Atg1-mediated myosin II activation regulates autophagosome formation during starvation-induced autophagy.
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Tang HW, Wang YB, Wang SL, Wu MH, Lin SY, Chen GC
Atg1-mediated myosin II activation regulates autophagosome formation during starvation-induced autophagy.
EMBO J. 2011 Feb 16;30(4):636-51. doi: 10.1038/emboj.2010.338. Epub 2010 Dec 17.
- PubMed ID
- 21169990 [ View in PubMed]
- Abstract
Autophagy is a membrane-mediated degradation process of macromolecule recycling. Although the formation of double-membrane degradation vesicles (autophagosomes) is known to have a central role in autophagy, the mechanism underlying this process remains elusive. The serine/threonine kinase Atg1 has a key role in the induction of autophagy. In this study, we show that overexpression of Drosophila Atg1 promotes the phosphorylation-dependent activation of the actin-associated motor protein myosin II. A novel myosin light chain kinase (MLCK)-like protein, Spaghetti-squash activator (Sqa), was identified as a link between Atg1 and actomyosin activation. Sqa interacts with Atg1 through its kinase domain and is a substrate of Atg1. Significantly, myosin II inhibition or depletion of Sqa compromised the formation of autophagosomes under starvation conditions. In mammalian cells, we found that the Sqa mammalian homologue zipper-interacting protein kinase (ZIPK) and myosin II had a critical role in the regulation of starvation-induced autophagy and mammalian Atg9 (mAtg9) trafficking when cells were deprived of nutrients. Our findings provide evidence of a link between Atg1 and the control of Atg9-mediated autophagosome formation through the myosin II motor protein.