title: Proteomics of Huntington's disease-affected human embryonic stem cells reveals an evolving pathology involving mitochondrial dysfunction and metabolic disturbances.
abstract: Huntington's disease (HD) is an autosomal dominant neurodegenerative disorder caused by a mutation in the Huntingtin gene, where excessive (≥ 36) CAG repeats encode for glutamine expansion in the huntingtin protein. Research using mouse models and human pathological material has indicated dysfunctions in a myriad of systems, including mitochondrial and ubiquitin/proteasome complexes, cytoskeletal transport, signaling, and transcriptional regulation. Here, we examined the earliest biochemical and pathways involved in HD pathology. We conducted a proteomics study combined with immunocytochemical analysis of undifferentiated HD-affected and unaffected human embryonic stem cells (hESC). Analysis of 1883 identifications derived from membrane and cytosolic enriched fractions revealed mitochondria as the primary dysfunctional organ in HD-affected pluripotent cells in the absence of significant differences in huntingtin protein. Furthermore, on the basis of analysis of 645 proteins found in neurodifferentiated hESC, we show a shift to transcriptional dysregulation and cytoskeletal abnormalities as the primary pathologies in HD-affected cells differentiating along neural lineages in vitro. We also show this is concomitant with an up-regulation in expression of huntingtin protein in HD-affected cells. This study demonstrates the utility of a model that recapitulates HD pathology and offers insights into disease initiation, etiology, progression, and potential therapeutic intervention.
authors.affiliation: Australian Proteome Analysis Facility, §Australian School of Advanced Medicine, Macquarie University , Sydney, New South Wales 2109, Australia.
authors.forename: Leon R
authors.initials: LR
authors.lastname: McQuade
authors.forename: Anushree
authors.initials: A
authors.lastname: Balachandran
authors.forename: Heather A
authors.initials: HA
authors.lastname: Scott
authors.forename: Simer
authors.initials: S
authors.lastname: Khaira
authors.forename: Mark S
authors.initials: MS
authors.lastname: Baker
authors.forename: Uli
authors.initials: U
authors.lastname: Schmidt
mesh_terms: D002454:Cell Differentiation; D002460:Cell Line; D002478:Cells, Cultured; D053595:Embryonic Stem Cells / Q000378:metabolism*; D005260:Female; D006801:Humans; D000071058:Huntingtin Protein; D006816:Huntington Disease / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D008297:Male; D008928:Mitochondria / Q000378:metabolism*; D009154:Mutation; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism; D009474:Neurons / Q000378:metabolism; D020543:Proteome / Q000032:analysis* / Q000378:metabolism; D040901:Proteomics / Q000379:methods*
chemical_list: C086055:HTT protein, human; D000071058:Huntingtin Protein; D009419:Nerve Tissue Proteins; D020543:Proteome
keywords: Huntington’s disease; IPG-IEF; LC−MS/MS; human embryonic stem cells; immunocytochemistry; neurodifferentiation; shotgun proteomics