title: Identification and characterization of hic-5/ARA55 as an hsp27 binding protein.
abstract: hsp27 has been reported to participate in a wide variety of activities, including resistance to thermal and metabolic stress, regulation of growth and differentiation, and acting as a molecular chaperone or a regulator of actin polymerization. We hypothesized that these diverse functions are regulated in a cell- or tissue-specific manner via interaction with various binding proteins. To investigate this hypothesis, we used hsp27 as a "bait" to screen a yeast two-hybrid cDNA library from rat kidney glomeruli and identified a novel hsp27 binding protein, hic-5 (also known as ARA55), a focal adhesion protein and steroid receptor co-activator. Biochemical interaction between hsp27 and hic-5 was confirmed by co-immunoprecipitation, and critical protein.protein interaction regions were mapped to the hic-5 LIM domains and the hsp27 C-terminal domain. Initial analysis of the functional role of hsp27.hic-5 interaction revealed that hic-5 significantly inhibited the protection against heat-induced cell death conferred by hsp27 overexpression in co-transfected 293T cells. In contrast, when a non-hsp27-interacting hic-5 truncation mutant (hic-5/DeltaLIM4) was co-expressed with hsp27, the hic-5 inhibition of hsp27 protection was absent. We conclude that hic-5 is a true hsp27 binding protein and inhibits the ability of hsp27 to provide protection against heat shock in an interaction-dependent manner.
authors.affiliation: Cellular and Molecular Biology Program, Department of Pediatrics, University of Michigan, Ann Arbor, MI 48109, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Jia
authors.forename: R F
authors.initials: RF
authors.lastname: Ransom
authors.forename: M
authors.initials: M
authors.lastname: Shibanuma
authors.forename: C
authors.initials: C
authors.lastname: Liu
authors.forename: M J
authors.initials: MJ
authors.lastname: Welsh
authors.forename: W E
authors.initials: WE
authors.lastname: Smoyer
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D003598:Cytoskeletal Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D055551:HSP27 Heat-Shock Proteins; D006360:Heat-Shock Proteins / Q000378:metabolism*; D018869:Heat-Shock Response / Q000502:physiology; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D007668:Kidney / Q000166:cytology / Q000378:metabolism; D060588:LIM Domain Proteins; D008297:Male; D018832:Molecular Chaperones; D008969:Molecular Sequence Data; D009154:Mutation; D009363:Neoplasm Proteins / Q000235:genetics / Q000378:metabolism*; D051419:Paxillin; D010446:Peptide Fragments / Q000378:metabolism; D010750:Phosphoproteins / Q000302:isolation & purification; D011485:Protein Binding; D051381:Rats; D017207:Rats, Sprague-Dawley; D011944:Receptors, Androgen / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D014018:Tissue Distribution; D015534:Trans-Activators / Q000378:metabolism*
chemical_list: D003598:Cytoskeletal Proteins; D004268:DNA-Binding Proteins; D055551:HSP27 Heat-Shock Proteins; C057725:HSPB1 protein, human; D006360:Heat-Shock Proteins; C486114:Hspb1 protein, rat; D047908:Intracellular Signaling Peptides and Proteins; D060588:LIM Domain Proteins; D018832:Molecular Chaperones; D009363:Neoplasm Proteins; C496061:PXN protein, human; D051419:Paxillin; D010446:Peptide Fragments; D010750:Phosphoproteins; C496063:Pxn protein, rat; D011944:Receptors, Androgen; C490351:TGFB1I1 protein, human; C490352:Tgfb1i1 protein, rat; D015534:Trans-Activators