title: Composition of Rosenthal Fibers, the Protein Aggregate Hallmark of Alexander Disease.
abstract: Alexander disease (AxD) is a neurodegenerative disorder characterized by astrocytic protein aggregates called Rosenthal fibers (RFs). We used mouse models of AxD to determine the protein composition of RFs to obtain information about disease mechanisms including the hypothesis that sequestration of proteins in RFs contributes to disease. A method was developed for RF enrichment, and analysis of the resulting fraction using isobaric tags for relative and absolute quantitation mass spectrometry identified 77 proteins not previously associated with RFs. Three of five proteins selected for follow-up were confirmed enriched in the RF fraction by immunobloting of both the AxD mouse models and human patients: receptor for activated protein C kinase 1 (RACK1), G1/S-specific cyclin D2, and ATP-dependent RNA helicase DDX3X. Immunohistochemistry validated cyclin D2 as a new RF component, but results for RACK1 and DDX3X were equivocal. None of these was decreased in the non-RF fractions compared to controls. A similar result was obtained for the previously known RF component, alphaB-crystallin, which had been a candidate for sequestration. Thus, no support was obtained for the sequestration hypothesis for AxD. Providing possible insight into disease progression, the association of several of the RF proteins with stress granules suggests a role for stress granules in the origin of RFs.
authors.forename: Michael R
authors.initials: MR
authors.lastname: Heaven
authors.forename: Daniel
authors.initials: D
authors.lastname: Flint
authors.affiliation: Keck Fourier Transform Mass Spectrometry Laboratory, Department of Chemistry, North Carolina State University , Raleigh, North Carolina 27695, United States.
authors.forename: Shan M
authors.initials: SM
authors.lastname: Randall
authors.forename: Alexander A
authors.initials: AA
authors.lastname: Sosunov
authors.forename: Landon
authors.initials: L
authors.lastname: Wilson
authors.forename: Stephen
authors.initials: S
authors.lastname: Barnes
authors.forename: James E
authors.initials: JE
authors.lastname: Goldman
authors.affiliation: Keck Fourier Transform Mass Spectrometry Laboratory, Department of Chemistry, North Carolina State University , Raleigh, North Carolina 27695, United States.
authors.forename: David C
authors.initials: DC
authors.lastname: Muddiman
authors.forename: Michael
authors.initials: M
authors.lastname: Brenner
mesh_terms: D038261:Alexander Disease; D000818:Animals; D001253:Astrocytes; D056742:Cyclin D2 / Q000032:analysis; D053487:DEAD-box RNA Helicases / Q000032:analysis; D019204:GTP-Binding Proteins / Q000032:analysis; D006801:Humans; D007150:Immunohistochemistry; D051379:Mice; D009363:Neoplasm Proteins / Q000032:analysis; D009479:Neuropeptides / Q000032:analysis; D066329:Protein Aggregates; D066263:Protein Aggregation, Pathological; D020543:Proteome / Q000032:analysis*; D020365:RNA Helicases / Q000032:analysis; D000075370:Receptors for Activated C Kinase; D011956:Receptors, Cell Surface / Q000032:analysis
chemical_list: D056742:Cyclin D2; D009363:Neoplasm Proteins; D009479:Neuropeptides; D066329:Protein Aggregates; D020543:Proteome; C419368:RACK1 protein, human; C090294:RACK1 protein, mouse; D000075370:Receptors for Activated C Kinase; D011956:Receptors, Cell Surface; C119332:DDX3X protein, human; D019204:GTP-Binding Proteins; D053487:DEAD-box RNA Helicases; C514697:Ddx3x protein, mouse; D020365:RNA Helicases
keywords: Alexander disease; Rosenthal fiber; astrocyte; mass spectrometry (MS); neurodegenerative disease; protein aggregates; proteomics; stress granules