title: Phosphorylation of mutant huntingtin at serine 116 modulates neuronal toxicity.
abstract: Phosphorylation has been shown to have a significant impact on expanded huntingtin-mediated cellular toxicity. Several phosphorylation sites have been identified on the huntingtin (Htt) protein. To find new potential therapeutic targets for Huntington's Disease (HD), we used mass spectrometry to identify novel phosphorylation sites on N-terminal Htt, expressed in HEK293 cells. Using site-directed mutagenesis we introduced alterations of phosphorylation sites in a N586 Htt construct containing 82 polyglutamine repeats. The effects of these alterations on expanded Htt toxicity were evaluated in primary neurons using a nuclear condensation assay and a direct time-lapse imaging of neuronal death. As a result of these studies, we identified several novel phosphorylation sites, validated several known sites, and discovered one phospho-null alteration, S116A, that had a protective effect against expanded polyglutamine-mediated cellular toxicity. The results suggest that S116 is a potential therapeutic target, and indicate that our screening method is useful for identifying candidate phosphorylation sites.
authors: Division of Neurobiology, Department of Psychiatry, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America.
authors: Erin E
authors: EE
authors: Watkin
authors: Division of Neurobiology, Department of Psychiatry, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America.
authors: Nicolas
authors: N
authors: Arbez
authors: Division of Neurobiology, Department of Psychiatry, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America.
authors: Elaine
authors: E
authors: Waldron-Roby
authors: Mass Spectrometry and Proteomics Facility, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America.
authors: Robert
authors: R
authors: O'Meally
authors: Division of Neurobiology, Department of Psychiatry, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America.
authors: Tamara
authors: T
authors: Ratovitski
authors: Mass Spectrometry and Proteomics Facility, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America.
authors: Robert N
authors: RN
authors: Cole
authors: Division of Neurobiology, Department of Psychiatry, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America ; Departments of Neurology, Pharmacology and Neuroscience and Program in Cellular and Molecular Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America.
authors: Christopher A
authors: CA
authors: Ross
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D016923:Cell Death; D002478:Cells, Cultured; D057809:HEK293 Cells; D006801:Humans; D000071058:Huntingtin Protein; D006816:Huntington Disease / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D051379:Mice; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D009474:Neurons / Q000378:metabolism / Q000473:pathology; D010455:Peptides / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation; D017354:Point Mutation; D012694:Serine / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism
chemical_list: C086055:HTT protein, human; D000071058:Huntingtin Protein; D009419:Nerve Tissue Proteins; D010455:Peptides; C097188:polyglutamine; D012694:Serine