title: Syk-mediated tyrosine phosphorylation is required for the association of hematopoietic lineage cell-specific protein 1 with lipid rafts and B cell antigen receptor signalosome complex.
abstract: Hematopoietic lineage cell-specific protein 1 (HS1) is an F-actin- and actin-related proteins 2 and 3 (Arp2/3)-binding protein that undergoes a rapid tyrosine phosphorylation upon B cell antigen receptor (BCR) activation. Density gradient centrifugation of Triton X-100 lysates from B lymphocytes demonstrated that HS1 was translocated in response to BCR cross-linking into lipid raft microdomain along with Arp2/3 complex and Wiskott-Aldrich syndrome protein. HS1-green fluorescent protein was localized in membrane patches enriched with GM1 gangliosides and BCR in the cells treated with anti-IgM antibody. Colocalization of HS1-green fluorescent protein with BCR was also correlated with tyrosine phosphorylation of HS1. Interestingly a murine HS1 mutant at the tyrosine residues Tyr388 and Tyr405 targeted by Syk failed to respond to BCR cross-linking for either translocation into lipid rafts or colocalization with BCR within cells. Furthermore HS1 was unable to translocate into lipid rafts in a chicken B cell line deficient in Syk. Reintroducing a Syk construct into the Syk knock-out cells recovered effectively both tyrosine phosphorylation and translocation of HS1 into lipid rafts. In contrast, translocation of HS1 into rafts was normal in a Lyn knock-out B cell line, and an HS1 mutant at the tyrosine residue Tyr222 targeted by Lyn maintained the ability to partition into rafts upon BCR cross-linking. These data indicate that Syk plays an important role in the translocation of HS1 into lipid rafts and may be responsible for actin assembly recruitment to rafts and subsequent antigen presentations.
authors.affiliation: Departments of Experimental Pathology and Immunology, Holland Laboratory, American Red Cross, Rockville, Maryland 20855, USA.
authors.forename: Jian-Jiang
authors.initials: JJ
authors.lastname: Hao
authors.forename: Gregory B
authors.initials: GB
authors.lastname: Carey
authors.forename: Xi
authors.initials: X
authors.lastname: Zhan
mesh_terms: D000199:Actins / Q000378:metabolism; D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D000906:Antibodies / Q000494:pharmacology; D001798:Blood Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002352:Carrier Proteins / Q000378:metabolism; D002460:Cell Line; D002462:Cell Membrane / Q000737:chemistry; D002645:Chickens; D003432:Cross-Linking Reagents; D003598:Cytoskeletal Proteins; D004792:Enzyme Precursors / Q000235:genetics / Q000378:metabolism*; D005677:G(M1) Ganglioside / Q000032:analysis; D049452:Green Fluorescent Proteins; D006801:Humans; D007075:Immunoglobulin M / Q000276:immunology; D047908:Intracellular Signaling Peptides and Proteins; D050356:Lipid Metabolism; D008164:Luminescent Proteins / Q000235:genetics; D051379:Mice; D010766:Phosphorylation; D011505:Protein-Tyrosine Kinases / Q000235:genetics / Q000378:metabolism*; D011947:Receptors, Antigen, B-Cell / Q000032:analysis / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000032:analysis; D013329:Structure-Activity Relationship; D000072377:Syk Kinase; D014443:Tyrosine / Q000378:metabolism*
chemical_list: D000199:Actins; D048868:Adaptor Proteins, Signal Transducing; D000906:Antibodies; D001798:Blood Proteins; D002352:Carrier Proteins; D003432:Cross-Linking Reagents; D003598:Cytoskeletal Proteins; D004792:Enzyme Precursors; C061909:HCLS1 protein, human; D007075:Immunoglobulin M; D047908:Intracellular Signaling Peptides and Proteins; D008164:Luminescent Proteins; D011947:Receptors, Antigen, B-Cell; D011993:Recombinant Fusion Proteins; C109903:WIPF1 protein, human; C491671:Waspip protein, mouse; D049452:Green Fluorescent Proteins; D005677:G(M1) Ganglioside; D014443:Tyrosine; D011505:Protein-Tyrosine Kinases; C000606896:SYK protein, human; D000072377:Syk Kinase; C000606897:Syk protein, mouse