title: Leukocyte integrin α4β7 associates with heat shock protein 70.
abstract: The leukocyte integrin cell adhesion molecules α4β7 and αEβ7 mediate the homing and retention of lymphocytes to the gut, and sites of inflammation. Here we have identified heat shock protein 70 (HSP70) as a major protein that associates with the cytoplasmic domain of the integrin β7 subunit. HSPs are molecular chaperones that protect cells from stress but more recently have been reported to also regulate cell adhesion and invasion via modulation of β1, β2, and β3 integrins and integrin-associated signalling molecules. Several HSP70 isoforms including HSP70-3, HSP70-1L, HSP70-8, and HSP70-9 were specifically precipitated from T cells by a bead-conjugated β7 subunit cytoplasmic domain peptide and subsequently identified by high-resolution liquid chromatography-tandem mass spectrometry. In confirmation, the β7 subunit was co-immunoprecipitated from a T cell lysate by an anti-HSP70 antibody. Further, recombinant human HSP70-1a was precipitated by β7 cytoplasmic domain-coupled beads. The HSP70 inhibitor KNK437 decreased the expression of HSP70 without affecting the expression of the β7 integrin. It significantly inhibited α4β7-mediated adhesion of T cells to mucosal addressin cell adhesion molecule 1 (MAdCAM-1), suggesting HSP70 is critical for maintaining β7 integrin signalling function. The functional implications of the association of β7 integrins with the different isoforms of HSP70 warrants further investigation.
authors.affiliation: Department of Molecular Medicine & Pathology, Faculty of Medical and Health Sciences, University of Auckland, 85 Park Road, Grafton, Auckland, New Zealand.
authors.forename: Yih-Chih
authors.initials: YC
authors.lastname: Chan
authors.affiliation: Faculty of Science, School of Biological Sciences, University of Auckland, Auckland, New Zealand.
authors.forename: David R
authors.initials: DR
authors.lastname: Greenwood
authors.affiliation: Department of Molecular Medicine & Pathology, Faculty of Medical and Health Sciences, University of Auckland, 85 Park Road, Grafton, Auckland, New Zealand.
authors.forename: Yi
authors.initials: Y
authors.lastname: Yang
authors.affiliation: Department of Molecular Medicine & Pathology, Faculty of Medical and Health Sciences, University of Auckland, 85 Park Road, Grafton, Auckland, New Zealand.
authors.forename: Euphemia
authors.initials: E
authors.lastname: Leung
authors.affiliation: Department of Molecular Medicine & Pathology, Faculty of Medical and Health Sciences, University of Auckland, 85 Park Road, Grafton, Auckland, New Zealand. gw.krissansen@auckland.ac.nz.
authors.forename: Geoffrey W
authors.initials: GW
authors.lastname: Krissansen
mesh_terms: D000818:Animals; D015703:Antigens, CD / Q000378:metabolism; D001559:Benzhydryl Compounds / Q000494:pharmacology; D002448:Cell Adhesion / Q000502:physiology*; D015815:Cell Adhesion Molecules / Q000378:metabolism; D045744:Cell Line, Tumor; D018840:HSP70 Heat-Shock Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D006801:Humans; D007074:Immunoglobulin G / Q000276:immunology; D039001:Integrin alpha Chains / Q000378:metabolism; D016023:Integrins / Q000378:metabolism*; D051379:Mice; D009088:Mucoproteins; D017434:Protein Structure, Tertiary; D011760:Pyrrolidinones / Q000494:pharmacology; D013601:T-Lymphocytes / Q000276:immunology
chemical_list: D015703:Antigens, CD; D001559:Benzhydryl Compounds; D015815:Cell Adhesion Molecules; D018840:HSP70 Heat-Shock Proteins; C483693:Hspa14 protein, human; D007074:Immunoglobulin G; D039001:Integrin alpha Chains; D016023:Integrins; C410027:KNK 437; C489082:Madcam1 protein, mouse; D009088:Mucoproteins; D011760:Pyrrolidinones; C091367:alpha E integrins; C071777:integrin alpha4beta7
keywords: Cytoplasmic domain; Heat shock protein 70; Immunoprecipitation; Integrin α4β7; Mass spectrometry