title: Huntingtin-associated protein 1 (HAP1) interacts with the p150Glued subunit of dynactin.
abstract: Huntington's disease (HD) is an inherited neurodegenerative disease caused by expansion of a polyglutamine repeat in the HD protein huntingtin. Huntingtin's localization within the cell includes an association with cytoskeletal elements and vesicles. We previously identified a protein (HAP1) which binds to huntingtin in a glutamine repeat length-dependent manner. We now report that HAP1 interacts with cytoskeletal proteins, namely the p150 Glued subunit of dynactin and the pericentriolar protein PCM-1. Structural predictions indicate that both HAP1 and the interacting proteins have a high probability of forming coiled coils. We examined the interaction of HAP1 with p150 Glued . Binding of HAP1 to p150 Glued (amino acids 879-1150) was confirmed in vitro by binding of p150 Glued to a HAP1-GST fusion protein immobilized on glutathione-Sepharose beads. Also, HAP1 co-immunoprecipitated with p150 Glued from brain extracts, indicating that the interaction occurs in vivo . Like HAP1, p150 Glued is highly expressed in neurons in brain and both proteins are enriched in a nerve terminal vesicle-rich fraction. Double label immunofluorescence experiments in NGF-treated PC12 cells using confocal microscopy revealed that HAP1 and p150 Glued partially co-localize. These results suggest that HAP1 might function as an adaptor protein using coiled coils to mediate interactions among cytoskeletal, vesicular and motor proteins. Thus, HAP1 and huntingtin may play a role in vesicle trafficking within the cell and disruption of this function could contribute to the neuronal dysfunction and death seen in HD.
authors.affiliation: Department of Psychiatry, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
authors.forename: S
authors.initials: S
authors.lastname: Engelender
authors.forename: A H
authors.initials: AH
authors.lastname: Sharp
authors.forename: V
authors.initials: V
authors.lastname: Colomer
authors.forename: M K
authors.initials: MK
authors.lastname: Tokito
authors.forename: A
authors.initials: A
authors.lastname: Lanahan
authors.forename: P
authors.initials: P
authors.lastname: Worley
authors.forename: E L
authors.initials: EL
authors.lastname: Holzbaur
authors.forename: C A
authors.initials: CA
authors.lastname: Ross
mesh_terms: D000818:Animals; D001324:Autoantigens / Q000378:metabolism; D001483:Base Sequence; D001923:Brain Chemistry; D019757:Carbon-Oxygen Lyases; D018797:Cell Cycle Proteins; D002460:Cell Line; D002846:Chromatography, Affinity; D003599:Cytoskeleton / Q000378:metabolism / Q000648:ultrastructure; D018076:DNA, Complementary / Q000235:genetics; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase; D000072159:Dynactin Complex; D006801:Humans; D016547:Kinesins / Q000235:genetics; D046911:Macromolecular Substances; D018613:Microscopy, Confocal; D008869:Microtubule-Associated Proteins / Q000737:chemistry / Q000378:metabolism*; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000737:chemistry / Q000378:metabolism*; D016716:PC12 Cells; D011485:Protein Binding; D011487:Protein Conformation; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012441:Saccharomyces cerevisiae; D029701:Saccharomyces cerevisiae Proteins
chemical_list: D001324:Autoantigens; D018797:Cell Cycle Proteins; C000606360:DCTN1 protein, human; D018076:DNA, Complementary; D000072159:Dynactin Complex; D046911:Macromolecular Substances; D008869:Microtubule-Associated Proteins; C000606366:NIP100 protein, S cerevisiae; D009687:Nuclear Proteins; C086074:PCM1 protein, human; D011993:Recombinant Fusion Proteins; D029701:Saccharomyces cerevisiae Proteins; D016547:Kinesins; D019757:Carbon-Oxygen Lyases; C085108:APEX1 protein, human; C470319:Apex1 protein, rat; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase