title: TMEM199 Deficiency Is a Disorder of Golgi Homeostasis Characterized by Elevated Aminotransferases, Alkaline Phosphatase, and Cholesterol and Abnormal Glycosylation.
abstract: Congenital disorders of glycosylation (CDGs) form a genetically and clinically heterogeneous group of diseases with aberrant protein glycosylation as a hallmark. A subgroup of CDGs can be attributed to disturbed Golgi homeostasis. However, identification of pathogenic variants is seriously complicated by the large number of proteins involved. As part of a strategy to identify human homologs of yeast proteins that are known to be involved in Golgi homeostasis, we identified uncharacterized transmembrane protein 199 (TMEM199, previously called C17orf32) as a human homolog of yeast V-ATPase assembly factor Vph2p (also known as Vma12p). Subsequently, we analyzed raw exome-sequencing data from families affected by genetically unsolved CDGs and identified four individuals with different mutations in TMEM199. The adolescent individuals presented with a mild phenotype of hepatic steatosis, elevated aminotransferases and alkaline phosphatase, and hypercholesterolemia, as well as low serum ceruloplasmin. Affected individuals showed abnormal N- and mucin-type O-glycosylation, and mass spectrometry indicated reduced incorporation of galactose and sialic acid, as seen in other Golgi homeostasis defects. Metabolic labeling of sialic acids in fibroblasts confirmed deficient Golgi glycosylation, which was restored by lentiviral transduction with wild-type TMEM199. V5-tagged TMEM199 localized with ERGIC and COPI markers in HeLa cells, and electron microscopy of a liver biopsy showed dilated organelles suggestive of the endoplasmic reticulum and Golgi apparatus. In conclusion, we have identified TMEM199 as a protein involved in Golgi homeostasis and show that TMEM199 deficiency results in a hepatic phenotype with abnormal glycosylation.
authors.affiliation: Department of Gastroenterology and Hepatology, Radboud University Medical Center, 6525 GA Nijmegen, the Netherlands; Translational Metabolic Laboratory, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, 6525 GA Nijmegen, the Netherlands.
authors.forename: Jos C
authors.initials: JC
authors.lastname: Jansen
authors.affiliation: Translational Metabolic Laboratory, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, 6525 GA Nijmegen, the Netherlands; Department of Neurology, Donders Institute for Brain, Cognition and Behavior, Radboud University Medical Center, 6525 GA Nijmegen, the Netherlands.
authors.forename: Sharita
authors.initials: S
authors.lastname: Timal
authors.affiliation: Translational Metabolic Laboratory, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, 6525 GA Nijmegen, the Netherlands; Department of Neurology, Donders Institute for Brain, Cognition and Behavior, Radboud University Medical Center, 6525 GA Nijmegen, the Netherlands.
authors.forename: Monique
authors.initials: M
authors.lastname: van Scherpenzeel
authors.affiliation: Department of Enzymology and Cellular Function, Institute of Child Health, Athens 11526, Greece.
authors.forename: Helen
authors.initials: H
authors.lastname: Michelakakis
authors.affiliation: CNRS-UMR 8576, Structural and Functional Glycobiology Unit, Federation of Research Structural & Functional Biochemistry of Biomolecular Assemblies (FRABio), University of Lille, 59655 Villeneuve d'Ascq, France.
authors.forename: Dorothée
authors.initials: D
authors.lastname: Vicogne
authors.affiliation: Translational Metabolic Laboratory, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, 6525 GA Nijmegen, the Netherlands; Department of Neurology, Donders Institute for Brain, Cognition and Behavior, Radboud University Medical Center, 6525 GA Nijmegen, the Netherlands.
authors.forename: Angel
authors.initials: A
authors.lastname: Ashikov
authors.affiliation: Department of Enzymology and Cellular Function, Institute of Child Health, Athens 11526, Greece.
authors.forename: Marina
authors.initials: M
authors.lastname: Moraitou
authors.affiliation: Department of Human Genetics, Radboud University Medical Center, 6525 GA Nijmegen, the Netherlands.
authors.forename: Alexander
authors.initials: A
authors.lastname: Hoischen
authors.affiliation: Translational Metabolic Laboratory, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, 6525 GA Nijmegen, the Netherlands.
authors.forename: Karin
authors.initials: K
authors.lastname: Huijben
authors.affiliation: Translational Metabolic Laboratory, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, 6525 GA Nijmegen, the Netherlands.
authors.forename: Gerry
authors.initials: G
authors.lastname: Steenbergen
authors.affiliation: Department of Vascular Medicine, Academic Medical Center, 1105 AZ Amsterdam, the Netherlands.
authors.forename: Marjolein A W
authors.initials: MA
authors.lastname: van den Boogert
authors.affiliation: Department of Pediatrics, Azienda Ospedaliera Città della Salute e della Scienza, University of Torino, 10126 Torino, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Porta
authors.affiliation: Department of Pediatrics, Azienda Ospedaliera Città della Salute e della Scienza, University of Torino, 10126 Torino, Italy.
authors.forename: Pier Luigi
authors.initials: PL
authors.lastname: Calvo
authors.affiliation: 1(st) Department of Pediatrics, P. & A. Kyriakou Children's Hospital, Athens 11527, Greece.
authors.forename: Mersyni
authors.initials: M
authors.lastname: Mavrikou
authors.affiliation: Department of Biomedical and Neuromotor Sciences, Alma Mater Studiorum-University of Bologna, 40138 Bologna, Italy.
authors.forename: Giovanna
authors.initials: G
authors.lastname: Cenacchi
authors.affiliation: Department of Tumor Immunology, Radboud University Medical Center, 6525 GA Nijmegen, the Netherlands.
authors.forename: Geert
authors.initials: G
authors.lastname: van den Bogaart
authors.affiliation: Department of Gastroenterology and Hepatology, Radboud University Medical Center, 6525 GA Nijmegen, the Netherlands.
authors.forename: Jody
authors.initials: J
authors.lastname: Salomon
authors.affiliation: Department of Vascular Medicine, Academic Medical Center, 1105 AZ Amsterdam, the Netherlands.
authors.forename: Adriaan G
authors.initials: AG
authors.lastname: Holleboom
authors.affiliation: Translational Metabolic Laboratory, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, 6525 GA Nijmegen, the Netherlands; Nijmegen Centre for Mitochondrial Disorders, Department of Pediatrics, Radboud University Medical Center, 6525 GA Nijmegen, the Netherlands.
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Rodenburg
authors.affiliation: Department of Gastroenterology and Hepatology, Radboud University Medical Center, 6525 GA Nijmegen, the Netherlands.
authors.forename: Joost P H
authors.initials: JP
authors.lastname: Drenth
authors.affiliation: Centre for Molecular and Biomolecular Informatics, Radboud University Medical Center, 6525 GA Nijmegen, the Netherlands.
authors.forename: Martijn A
authors.initials: MA
authors.lastname: Huynen
authors.affiliation: Translational Metabolic Laboratory, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, 6525 GA Nijmegen, the Netherlands.
authors.forename: Ron A
authors.initials: RA
authors.lastname: Wevers
authors.affiliation: Department of Human Genetics, University of Leuven, 3000 Leuven, Belgium; Hayward Genetics Center, Department of Pediatrics, Tulane University Medical School, New Orleans, LA 70112, USA.
authors.forename: Eva
authors.initials: E
authors.lastname: Morava
authors.affiliation: CNRS-UMR 8576, Structural and Functional Glycobiology Unit, Federation of Research Structural & Functional Biochemistry of Biomolecular Assemblies (FRABio), University of Lille, 59655 Villeneuve d'Ascq, France.
authors.forename: François
authors.initials: F
authors.lastname: Foulquier
authors.affiliation: Department of Human Genetics, Radboud University Medical Center, 6525 GA Nijmegen, the Netherlands; Department of Clinical Genetics, Maastricht University Medical Centre, 6229 HX Maastricht, the Netherlands.
authors.forename: Joris A
authors.initials: JA
authors.lastname: Veltman
authors.affiliation: Translational Metabolic Laboratory, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, 6525 GA Nijmegen, the Netherlands; Department of Neurology, Donders Institute for Brain, Cognition and Behavior, Radboud University Medical Center, 6525 GA Nijmegen, the Netherlands. Electronic address: dirk.lefeber@radboudumc.nl.
authors.forename: Dirk J
authors.initials: DJ
authors.lastname: Lefeber
mesh_terms: D000328:Adult; D000469:Alkaline Phosphatase / Q000378:metabolism*; D000595:Amino Acid Sequence; D002570:Ceruloplasmin / Q000378:metabolism; D002784:Cholesterol / Q000378:metabolism*; D004721:Endoplasmic Reticulum / Q000378:metabolism; D059472:Exome; D005347:Fibroblasts / Q000378:metabolism; D005838:Genotype; D006031:Glycosylation; D006056:Golgi Apparatus / Q000235:genetics* / Q000378:metabolism; D006706:Homeostasis; D006801:Humans; D008297:Male; D008565:Membrane Proteins / Q000172:deficiency* / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation; D010641:Phenotype; D000637:Transaminases / Q000378:metabolism*; D055815:Young Adult
chemical_list: D008565:Membrane Proteins; D002784:Cholesterol; D002570:Ceruloplasmin; D000637:Transaminases; D000469:Alkaline Phosphatase
keywords: COPI vesicular transport; Congenital Disorders of Glycosylation; Golgi homeostasis; TMEM199 deficiency; V-ATPase assembly; Vph2p; alkaline phosphatase; elevated aminotransferases; hypercholesterolemia
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