title: PI(5)P regulates autophagosome biogenesis.
abstract: Phosphatidylinositol 3-phosphate (PI(3)P), the product of class III PI3K VPS34, recruits specific autophagic effectors, like WIPI2, during the initial steps of autophagosome biogenesis and thereby regulates canonical autophagy. However, mammalian cells can produce autophagosomes through enigmatic noncanonical VPS34-independent pathways. Here we show that PI(5)P can regulate autophagy via PI(3)P effectors and thereby identify a mechanistic explanation for forms of noncanonical autophagy. PI(5)P synthesis by the phosphatidylinositol 5-kinase PIKfyve was required for autophagosome biogenesis, and it increased levels of PI(5)P, stimulated autophagy, and reduced the levels of autophagic substrates. Inactivation of VPS34 impaired recruitment of WIPI2 and DFCP1 to autophagic precursors, reduced ATG5-ATG12 conjugation, and compromised autophagosome formation. However, these phenotypes were rescued by PI(5)P in VPS34-inactivated cells. These findings provide a mechanistic framework for alternative VPS34-independent autophagy-initiating pathways, like glucose starvation, and unravel a cytoplasmic function for PI(5)P, which previously has been linked predominantly to nuclear roles.
authors.affiliation: Department of Medical Genetics, Cambridge Institute for Medical Research, Wellcome/MRC Building, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0XY, UK.
authors.forename: Mariella
authors.initials: M
authors.lastname: Vicinanza
authors.affiliation: Department of Medical Genetics, Cambridge Institute for Medical Research, Wellcome/MRC Building, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0XY, UK.
authors.forename: Viktor I
authors.initials: VI
authors.lastname: Korolchuk
authors.affiliation: Department of Medical Genetics, Cambridge Institute for Medical Research, Wellcome/MRC Building, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0XY, UK.
authors.forename: Avraham
authors.initials: A
authors.lastname: Ashkenazi
authors.affiliation: Department of Medical Genetics, Cambridge Institute for Medical Research, Wellcome/MRC Building, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0XY, UK.
authors.forename: Claudia
authors.initials: C
authors.lastname: Puri
authors.affiliation: Department of Medical Genetics, Cambridge Institute for Medical Research, Wellcome/MRC Building, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0XY, UK.
authors.forename: Fiona M
authors.initials: FM
authors.lastname: Menzies
authors.affiliation: Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1PD, UK.
authors.forename: Jonathan H
authors.initials: JH
authors.lastname: Clarke
authors.affiliation: Department of Medical Genetics, Cambridge Institute for Medical Research, Wellcome/MRC Building, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0XY, UK. Electronic address: dcr1000@cam.ac.uk.
authors.forename: David C
authors.initials: DC
authors.lastname: Rubinsztein
mesh_terms: D000818:Animals; D001343:Autophagy; D000071183:Autophagy-Related Proteins; D002352:Carrier Proteins / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D064799:Hypoxia-Inducible Factor-Proline Dioxygenases / Q000378:metabolism; D051379:Mice; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D010588:Phagosomes / Q000502:physiology*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D018129:Phosphatidylinositol Phosphates / Q000502:physiology*
chemical_list: D000071183:Autophagy-Related Proteins; D002352:Carrier Proteins; D064799:Hypoxia-Inducible Factor-Proline Dioxygenases; D008869:Microtubule-Associated Proteins; D019869:Phosphatidylinositol 3-Kinases; D018129:Phosphatidylinositol Phosphates; C518959:ATG16L1 protein, human; C477012:MAP1LC3A protein, human; C055525:phosphatidylinositol 3-phosphate; C113567:phosphatidylinositol 5-phosphate; C488894:EGLN3 protein, human; C492139:PIKFYVE protein, human