PtdIns(4,5)P2 signaling regulates ATG14 and autophagy.

Autophagy is a regulated self-digestion pathway with fundamental roles in cell homeostasis and diseases. Autophagy is regulated by coordinated actions of a series of autophagy-related (ATG) proteins. The Barkor/ATG14(L)-VPS34 (a class III phosphatidylinositol 3-kinase) complex and its product phosphatidylinositol 3-phosphate [PtdIns(3)P] play key roles in autophagy initiation. ATG14 contains a ...
C-terminal Barkor/ATG14(L) autophagosome-targeting sequence (BATS) domain that senses the curvature of PtdIns(3)P-containing membrane. The BATS domain also strongly binds PtdIns(4,5)P2, but the functional significance has been unclear. Here we show that ATG14 specifically interacts with type I? PIP kinase isoform 5 (PIPKI?i5), an enzyme that generates PtdIns(4,5)P2 in mammalian cells. Autophagosomes have associated PIPKI?i5 and PtdIns(4,5)P2 that are colocalized with late endosomes and the endoplasmic reticulum. PtdIns(4,5)P2 generation at these sites requires PIPKI?i5. Loss of PIPKI?i5 results in a loss of ATG14, UV irradiation resistance-associated gene, and Beclin 1 and a block of autophagy. PtdIns(4,5)P2 binding to the ATG14-BATS domain regulates ATG14 interaction with VPS34 and Beclin 1, and thus plays a key role in ATG14 complex assembly and autophagy initiation. This study identifies an unexpected role for PtdIns(4,5)P2 signaling in the regulation of ATG14 complex and autophagy.
Mesh Terms:
Adaptor Proteins, Vesicular Transport, Autophagy, Autophagy-Related Protein 5, Autophagy-Related Proteins, Beclin-1, Carrier Proteins, Cell Line, Endoplasmic Reticulum, Endosomes, Gene Knockdown Techniques, Humans, Mutation, Phosphatidylinositol 4,5-Diphosphate, Phosphotransferases (Alcohol Group Acceptor), Protein Binding, Protein Domains, Signal Transduction, Subcellular Fractions
Proc. Natl. Acad. Sci. U.S.A.
Date: Dec. 27, 2015
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