title: Excess sphingomyelin disturbs ATG9A trafficking and autophagosome closure.
abstract: Sphingomyelin is an essential cellular lipid that traffics between plasma membrane and intracellular organelles until directed to lysosomes for SMPD1 (sphingomyelin phosphodiesterase 1)-mediated degradation. Inactivating mutations in the SMPD1 gene result in Niemann-Pick diseases type A and B characterized by sphingomyelin accumulation and severely disturbed tissue homeostasis. Here, we report that sphingomyelin overload disturbs the maturation and closure of autophagic membranes. Niemann-Pick type A patient fibroblasts and SMPD1-depleted cancer cells accumulate elongated and unclosed autophagic membranes as well as abnormally swollen autophagosomes in the absence of normal autophagosomes and autolysosomes. The immature autophagic membranes are rich in WIPI2, ATG16L1 and MAP1LC3B but display reduced association with ATG9A. Contrary to its normal trafficking between plasma membrane, intracellular organelles and autophagic membranes, ATG9A concentrates in transferrin receptor-positive juxtanuclear recycling endosomes in SMPD1-deficient cells. Supporting a causative role for ATG9A mistrafficking in the autophagy defect observed in SMPD1-deficient cells, ectopic ATG9A effectively reverts this phenotype. Exogenous C12-sphingomyelin induces a similar juxtanuclear accumulation of ATG9A and subsequent defect in the maturation of autophagic membranes in healthy cells while the main sphingomyelin metabolite, ceramide, fails to revert the autophagy defective phenotype in SMPD1-deficient cells. Juxtanuclear accumulation of ATG9A and defective autophagy are also evident in tissues of smpd1-deficient mice with a subsequent inability to cope with kidney ischemia-reperfusion stress. These data reveal sphingomyelin as an important regulator of ATG9A trafficking and maturation of early autophagic membranes.
authors.affiliation: a Cell Death and Metabolism, Center for Autophagy, Recycling and Disease, Danish Cancer Society Research Center , Copenhagen , Denmark.
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Corcelle-Termeau
authors.affiliation: a Cell Death and Metabolism, Center for Autophagy, Recycling and Disease, Danish Cancer Society Research Center , Copenhagen , Denmark.
authors.forename: Signe Diness
authors.initials: SD
authors.lastname: Vindeløv
authors.affiliation: a Cell Death and Metabolism, Center for Autophagy, Recycling and Disease, Danish Cancer Society Research Center , Copenhagen , Denmark.
authors.forename: Saara
authors.initials: S
authors.lastname: Hämälistö
authors.affiliation: b Institute of Research on Cancer and Ageing of Nice (IRCAN), Université de Nice-Sophia Antipolis, Centre Antoine Lacassagne , Nice , France.
authors.forename: Baharia
authors.initials: B
authors.lastname: Mograbi
authors.affiliation: a Cell Death and Metabolism, Center for Autophagy, Recycling and Disease, Danish Cancer Society Research Center , Copenhagen , Denmark.
authors.forename: Anne
authors.initials: A
authors.lastname: Keldsbo
authors.affiliation: c Institute for Pathology, Christian-Albrechts-University , Kiel , Germany.
authors.forename: Jan Hinrich
authors.initials: JH
authors.lastname: Bräsen
authors.affiliation: a Cell Death and Metabolism, Center for Autophagy, Recycling and Disease, Danish Cancer Society Research Center , Copenhagen , Denmark.
authors.forename: Elena
authors.initials: E
authors.lastname: Favaro
authors.affiliation: d Institute for Immunology, Christian-Albrechts-University , Kiel , Germany.
authors.forename: Dieter
authors.initials: D
authors.lastname: Adam
authors.affiliation: a Cell Death and Metabolism, Center for Autophagy, Recycling and Disease, Danish Cancer Society Research Center , Copenhagen , Denmark.
authors.forename: Piotr
authors.initials: P
authors.lastname: Szyniarowski
authors.affiliation: b Institute of Research on Cancer and Ageing of Nice (IRCAN), Université de Nice-Sophia Antipolis, Centre Antoine Lacassagne , Nice , France.|e Laboratory of Clinical and Experimental Pathology and Human Tissue Biobank/CRB INSERM , Pasteur Hospital and Faculty of Medicine , Nice , France.
authors.forename: Paul
authors.initials: P
authors.lastname: Hofman
authors.affiliation: f Division of Nephrology and Hypertension, Christian-Albrechts-University , Kiel , Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Krautwald
authors.affiliation: a Cell Death and Metabolism, Center for Autophagy, Recycling and Disease, Danish Cancer Society Research Center , Copenhagen , Denmark.
authors.forename: Thomas
authors.initials: T
authors.lastname: Farkas
authors.affiliation: a Cell Death and Metabolism, Center for Autophagy, Recycling and Disease, Danish Cancer Society Research Center , Copenhagen , Denmark.
authors.forename: Nikolaj H T
authors.initials: NH
authors.lastname: Petersen
authors.affiliation: a Cell Death and Metabolism, Center for Autophagy, Recycling and Disease, Danish Cancer Society Research Center , Copenhagen , Denmark.
authors.forename: Mikkel
authors.initials: M
authors.lastname: Rohde
authors.affiliation: f Division of Nephrology and Hypertension, Christian-Albrechts-University , Kiel , Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Linkermann
authors.affiliation: a Cell Death and Metabolism, Center for Autophagy, Recycling and Disease, Danish Cancer Society Research Center , Copenhagen , Denmark.
authors.forename: Marja
authors.initials: M
authors.lastname: Jäättelä
mesh_terms: D000818:Animals; D000071182:Autophagosomes / Q000378:metabolism* / Q000473:pathology; D001343:Autophagy / Q000502:physiology*; D000071183:Autophagy-Related Proteins / Q000378:metabolism*; D001943:Breast Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D002462:Cell Membrane / Q000378:metabolism; D011992:Endosomes / Q000378:metabolism; D005260:Female; D005347:Fibroblasts / Q000378:metabolism / Q000473:pathology; D006801:Humans; D061986:MCF-7 Cells; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism*; D051379:Mice; D057507:Mice, 129 Strain; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D052536:Niemann-Pick Disease, Type A / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D021381:Protein Transport; D034741:RNA, Small Interfering / Q000235:genetics; D011990:Receptors, Transferrin / Q000378:metabolism; D013108:Sphingomyelin Phosphodiesterase / Q000037:antagonists & inhibitors / Q000172:deficiency / Q000235:genetics; D013109:Sphingomyelins / Q000378:metabolism*; D033921:Vesicular Transport Proteins / Q000378:metabolism*
chemical_list: C574794:ATG9A protein, human; D000071183:Autophagy-Related Proteins; D008565:Membrane Proteins; D034741:RNA, Small Interfering; D011990:Receptors, Transferrin; D013109:Sphingomyelins; D033921:Vesicular Transport Proteins; C577975:ASMase, mouse; C543066:SMPD1 protein, human; D013108:Sphingomyelin Phosphodiesterase
keywords: ATG9A; Niemann Pick disease; acid sphingomyelinase; autophagy; ischemia-reperfusion injury; kidney; lysosome; sphingomyelin; trafficking