title: Beclin 1 is required for neuron viability and regulates endosome pathways via the UVRAG-VPS34 complex.
abstract: Deficiency of autophagy protein beclin 1 is implicated in tumorigenesis and neurodegenerative diseases, but the molecular mechanism remains elusive. Previous studies showed that Beclin 1 coordinates the assembly of multiple VPS34 complexes whose distinct phosphatidylinositol 3-kinase III (PI3K-III) lipid kinase activities regulate autophagy at different steps. Recent evidence suggests a function of beclin 1 in regulating multiple VPS34-mediated trafficking pathways beyond autophagy; however, the precise role of beclin 1 in autophagy-independent cellular functions remains poorly understood. Herein we report that beclin 1 regulates endocytosis, in addition to autophagy, and is required for neuron viability in vivo. We find that neuronal beclin 1 associates with endosomes and regulates EEA1/early endosome localization and late endosome formation. Beclin 1 maintains proper cellular phosphatidylinositol 3-phosphate (PI(3)P) distribution and total levels, and loss of beclin 1 causes a disruption of active Rab5 GTPase-associated endosome formation and impairment of endosome maturation, likely due to a failure of Rab5 to recruit VPS34. Furthermore, we find that Beclin 1 deficiency causes complete loss of the UVRAG-VPS34 complex and associated lipid kinase activity. Interestingly, beclin 1 deficiency impairs p40phox-linked endosome formation, which is rescued by overexpressed UVRAG or beclin 1, but not by a coiled-coil domain-truncated beclin 1 (a UVRAG-binding mutant), Atg14L or RUBICON. Thus, our study reveals the essential role for beclin 1 in neuron survival involving multiple membrane trafficking pathways including endocytosis and autophagy, and suggests that the UVRAG-beclin 1 interaction underlies beclin 1's function in endocytosis.
authors.affiliation: Department of Neurology and Neuroscience, Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America.
authors.forename: Nicole C
authors.initials: NC
authors.lastname: McKnight
authors.affiliation: Department of Neurology and Neuroscience, Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America.
authors.forename: Yun
authors.initials: Y
authors.lastname: Zhong
authors.affiliation: Department of Neurology and Neuroscience, Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America.
authors.forename: Mitchell S
authors.initials: MS
authors.lastname: Wold
authors.affiliation: Laboratory of Molecular Biology, Howard Hughes Medical Institute, Rockefeller University, New York, New York, United States of America.
authors.forename: Shiaoching
authors.initials: S
authors.lastname: Gong
authors.affiliation: Department of Neurology and Neuroscience, Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America.
authors.forename: Greg R
authors.initials: GR
authors.lastname: Phillips
authors.affiliation: Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, New York, United States of America.
authors.forename: Zhixun
authors.initials: Z
authors.lastname: Dou
authors.affiliation: Department of Applied Biology and Chemical Technology, State Key Laboratory of Chirosciences, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China.
authors.forename: Yanxiang
authors.initials: Y
authors.lastname: Zhao
authors.affiliation: Laboratory of Molecular Biology, Howard Hughes Medical Institute, Rockefeller University, New York, New York, United States of America.
authors.forename: Nathaniel
authors.initials: N
authors.lastname: Heintz
authors.affiliation: Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, New York, United States of America.
authors.forename: Wei-Xing
authors.initials: WX
authors.lastname: Zong
authors.affiliation: Department of Neurology and Neuroscience, Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America.
authors.forename: Zhenyu
authors.initials: Z
authors.lastname: Yue
mesh_terms: D000818:Animals; D051017:Apoptosis Regulatory Proteins / Q000235:genetics / Q000378:metabolism*; D001343:Autophagy / Q000235:genetics; D000071186:Beclin-1; D058546:Class III Phosphatidylinositol 3-Kinases / Q000235:genetics / Q000378:metabolism*; D004705:Endocytosis / Q000235:genetics; D011992:Endosomes / Q000378:metabolism*; D066246:ErbB Receptors / Q000378:metabolism; D006367:HeLa Cells / Q000378:metabolism; D006801:Humans; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008822:Mice, Transgenic; D046912:Multiprotein Complexes / Q000235:genetics / Q000378:metabolism; D019636:Neurodegenerative Diseases / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D009474:Neurons / Q000378:metabolism* / Q000473:pathology; D018129:Phosphatidylinositol Phosphates / Q000378:metabolism; D025521:Tumor Suppressor Proteins / Q000235:genetics / Q000378:metabolism*; D020696:rab5 GTP-Binding Proteins / Q000378:metabolism
chemical_list: D051017:Apoptosis Regulatory Proteins; C491997:BECN1 protein, human; D000071186:Beclin-1; C115010:Becn1 protein, mouse; D008565:Membrane Proteins; D046912:Multiprotein Complexes; D018129:Phosphatidylinositol Phosphates; D025521:Tumor Suppressor Proteins; C408122:UVRAG protein, human; C512859:UVRAG protein, mouse; C055525:phosphatidylinositol 3-phosphate; D058546:Class III Phosphatidylinositol 3-Kinases; C541485:EGFR protein, mouse; D066246:ErbB Receptors; D020696:rab5 GTP-Binding Proteins