FIP200, a ULK-interacting protein, is required for autophagosome formation in mammalian cells

FIP200, a ULK-interacting protein, is required for autophagosome formation in mammalian cells Autophagy is a membrane-mediated intracellular degradation system. The serine/threonine kinase Atg1 plays an essential role in autophagosome formation. However, the role of the mammalian Atg1 homologues UNC-51–like kinase (ULK) 1 and 2 are not yet well understood. We found that murine ULK1 and 2 localized to autophagic isolation membrane under starvation conditions. Kinase-dead alleles of ULK1 and 2 exerted a dominant-negative effect on autophagosome formation, suggesting that ULK kinase activity is important for autophagy. We next screened for ULK binding proteins and identified the focal adhesion kinase family interacting protein of 200 kD (FIP200), which regulates diverse cellular functions such as cell size, proliferation, and migration. We found that FIP200 was redistributed from the cytoplasm to the isolation membrane under starvation conditions. In FIP200-deficient cells, autophagy induction by various treatments was abolished, and both stability and phosphorylation of ULK1 were impaired. These results suggest that FIP200 is a novel mammalian autophagy factor that functions together with ULKs. Footnotes Abbreviations used in this paper: Cvt, cytoplasm-to-vacuole targeting; E, embryonic day; FIP200, FAK family–interacting protein of 200 kD; MEF, mouse embryonic fibroblast; mTOR, mammalian target of rapamycin; PAS, preautophagosomal structure; PE, phosphatidylethanolamine; ULK, UNC-51–like kinase. © 2008 Hara et al. This article is distributed under the terms of an Attribution–Noncommercial–Share Alike–No Mirror Sites license for the first six months after the publication date (see http://www.jcb.org/misc/terms.shtml ). After six months it is available under a Creative Commons License (Attribution–Noncommercial–Share Alike 3.0 Unported license, as described at http://creativecommons.org/licenses/by-nc-sa/3.0/ ). Submitted: 12 December 2007 Accepted: 2 April 2008 http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png The Journal of Cell Biology Rockefeller University Press

FIP200, a ULK-interacting protein, is required for autophagosome formation in mammalian cells

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Publisher
Rockefeller University Press
Copyright
© 2008 Hara et al.
ISSN
0021-9525
eISSN
1540-8140
D.O.I.
10.1083/jcb.200712064
Publisher site
See Article on Publisher Site

Abstract

Autophagy is a membrane-mediated intracellular degradation system. The serine/threonine kinase Atg1 plays an essential role in autophagosome formation. However, the role of the mammalian Atg1 homologues UNC-51–like kinase (ULK) 1 and 2 are not yet well understood. We found that murine ULK1 and 2 localized to autophagic isolation membrane under starvation conditions. Kinase-dead alleles of ULK1 and 2 exerted a dominant-negative effect on autophagosome formation, suggesting that ULK kinase activity is important for autophagy. We next screened for ULK binding proteins and identified the focal adhesion kinase family interacting protein of 200 kD (FIP200), which regulates diverse cellular functions such as cell size, proliferation, and migration. We found that FIP200 was redistributed from the cytoplasm to the isolation membrane under starvation conditions. In FIP200-deficient cells, autophagy induction by various treatments was abolished, and both stability and phosphorylation of ULK1 were impaired. These results suggest that FIP200 is a novel mammalian autophagy factor that functions together with ULKs. Footnotes Abbreviations used in this paper: Cvt, cytoplasm-to-vacuole targeting; E, embryonic day; FIP200, FAK family–interacting protein of 200 kD; MEF, mouse embryonic fibroblast; mTOR, mammalian target of rapamycin; PAS, preautophagosomal structure; PE, phosphatidylethanolamine; ULK, UNC-51–like kinase. © 2008 Hara et al. This article is distributed under the terms of an Attribution–Noncommercial–Share Alike–No Mirror Sites license for the first six months after the publication date (see http://www.jcb.org/misc/terms.shtml ). After six months it is available under a Creative Commons License (Attribution–Noncommercial–Share Alike 3.0 Unported license, as described at http://creativecommons.org/licenses/by-nc-sa/3.0/ ). Submitted: 12 December 2007 Accepted: 2 April 2008

Journal

The Journal of Cell BiologyRockefeller University Press

Published: May 5, 2008

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