title: Phosphorylation of LC3 by the Hippo kinases STK3/STK4 is essential for autophagy.
abstract: The protein LC3 is indispensible for the cellular recycling process of autophagy and plays critical roles during cargo recruitment, autophagosome biogenesis, and completion. Here, we report that LC3 is phosphorylated at threonine 50 (Thr(50)) by the mammalian Sterile-20 kinases STK3 and STK4. Loss of phosphorylation at this site blocks autophagy by impairing fusion of autophagosomes with lysosomes, and compromises the ability of cells to clear intracellular bacteria, an established cargo for autophagy. Strikingly, mutation of LC3 mimicking constitutive phosphorylation at Thr(50) reverses the autophagy block in STK3/STK4-deficient cells and restores their capacity to clear bacteria. Loss of STK3/STK4 impairs autophagy in diverse species, indicating that these kinases are conserved autophagy regulators. We conclude that phosphorylation of LC3 by STK3/STK4 is an essential step in the autophagy process. Since several pathological conditions, including bacterial infections, display aberrant autophagy, we propose that pharmacological agents targeting this regulatory circuit hold therapeutic potential.
authors.affiliation: Sanford-Burnham Medical Research Institute, Development, Aging, and Regeneration Program, La Jolla, CA 92037, USA.
authors.forename: Deepti S
authors.initials: DS
authors.lastname: Wilkinson
authors.affiliation: Sanford-Burnham Medical Research Institute, Development, Aging, and Regeneration Program, La Jolla, CA 92037, USA.
authors.forename: Jinel S
authors.initials: JS
authors.lastname: Jariwala
authors.affiliation: Department of Pediatrics, School of Medicine and Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, CA 92093, USA.
authors.forename: Ericka
authors.initials: E
authors.lastname: Anderson
authors.affiliation: Department of Medicine, University of California, San Diego, La Jolla, CA 92093, USA.
authors.forename: Koyel
authors.initials: K
authors.lastname: Mitra
authors.affiliation: Salk Institute for Biological Studies, La Jolla, CA 92037, USA.
authors.forename: Jill
authors.initials: J
authors.lastname: Meisenhelder
authors.affiliation: Sanford-Burnham Medical Research Institute, Development, Aging, and Regeneration Program, La Jolla, CA 92037, USA.
authors.forename: Jessica T
authors.initials: JT
authors.lastname: Chang
authors.affiliation: Department of Medicine, University of California, San Diego, La Jolla, CA 92093, USA.
authors.forename: Trey
authors.initials: T
authors.lastname: Ideker
authors.affiliation: Salk Institute for Biological Studies, La Jolla, CA 92037, USA.
authors.forename: Tony
authors.initials: T
authors.lastname: Hunter
authors.affiliation: Department of Pediatrics, School of Medicine and Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, CA 92093, USA.
authors.forename: Victor
authors.initials: V
authors.lastname: Nizet
authors.affiliation: The Howard Hughes Medical Institute, University of California, Berkeley, CA 94720, USA.
authors.forename: Andrew
authors.initials: A
authors.lastname: Dillin
authors.affiliation: Sanford-Burnham Medical Research Institute, Development, Aging, and Regeneration Program, La Jolla, CA 92037, USA. Electronic address: mhansen@sanfordburnham.org.
authors.forename: Malene
authors.initials: M
authors.lastname: Hansen
mesh_terms: D000818:Animals; D001343:Autophagy / Q000235:genetics*; D017173:Caenorhabditis elegans / Q000235:genetics / Q000378:metabolism; D002478:Cells, Cultured; D004622:Embryo, Mammalian; D005347:Fibroblasts / Q000378:metabolism* / Q000382:microbiology; D005786:Gene Expression Regulation; D006801:Humans; D008247:Lysosomes / Q000378:metabolism; D008561:Membrane Fusion; D051379:Mice; D018345:Mice, Knockout; D008869:Microtubule-Associated Proteins / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D010446:Peptide Fragments / Q000737:chemistry; D010588:Phagosomes / Q000378:metabolism; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000172:deficiency / Q000235:genetics*; D000090742:Serine-Threonine Kinase 3; D015398:Signal Transduction; D013297:Streptococcus pyogenes / Q000472:pathogenicity / Q000502:physiology; D013912:Threonine / Q000378:metabolism; D000099317:Hippo Kinases
chemical_list: D008869:Microtubule-Associated Proteins; D010446:Peptide Fragments; D017346:Protein Serine-Threonine Kinases; D000090742:Serine-Threonine Kinase 3; D013912:Threonine; C480860:Map1lc3b protein, mouse; C490660:Stk4 protein, mouse; D000099317:Hippo Kinases; C490818:Stk3 protein, mouse