title: CD36 signals to the actin cytoskeleton and regulates microglial migration via a p130Cas complex.
abstract: The pattern recognition receptor CD36 initiates a signaling cascade that promotes microglial activation and recruitment to beta-amyloid deposits in the brain. In the present study we identify the focal adhesion-associated proteins p130Cas, Pyk2, and paxillin as novel members of the tyrosine kinase signaling pathway downstream of CD36 and show that assembly of this complex is essential for microglial migration. In primary microglia and macrophages exposed to beta-amyloid, the scaffolding protein p130Cas is rapidly tyrosine-phosphorylated and co-localizes with CD36 to membrane ruffles contemporaneous with F-actin polymerization. These beta-amyloid-stimulated events are not detected in CD36 null cells and are dependent on CD36 activation of Src family tyrosine kinases. Fyn, a Src kinase known to interact with CD36, co-precipitates with p130Cas and is an essential upstream intermediate in the signaling pathways leading to phosphorylation of the p130Cas substrate domain. Furthermore, the p130Cas-interacting kinase Pyk2 and the cytoskeletal adapter protein paxillin also demonstrate CD36-dependent phosphorylation, identifying these focal adhesion molecules as additional members of this beta-amyloid signaling cascade. Disruption of this p130Cas complex by small interfering RNA silencing inhibits p44/42 mitogen-activated protein kinase phosphorylation and microglial migration, illustrating the importance of this pathway in microglial activation and recruitment. Together, these data are the first to identify the signaling cascade that directly links CD36 to the actin cytoskeleton and, thus, implicates it in diverse processes such as cellular migration, adhesion, and phagocytosis.
authors.affiliation: Developmental Immunology/Department of Pediatrics, the Department of Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02114 and; University of Edinburgh Centre for Inflammation Research, Edinburgh EH16 4TJ, United Kingdom.
authors.forename: Lynda M
authors.initials: LM
authors.lastname: Stuart
authors.affiliation: Lipid Metabolism Unit, and Department of Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02114 and.
authors.forename: Susan A
authors.initials: SA
authors.lastname: Bell
authors.affiliation: Lipid Metabolism Unit, and Department of Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02114 and.
authors.forename: Cameron R
authors.initials: CR
authors.lastname: Stewart
authors.affiliation: Lipid Metabolism Unit, and Department of Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02114 and.
authors.forename: Jessica M
authors.initials: JM
authors.lastname: Silver
authors.affiliation: Lipid Metabolism Unit, and Department of Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02114 and.
authors.forename: James
authors.initials: J
authors.lastname: Richard
authors.affiliation: Lipid Metabolism Unit, and Department of Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02114 and.
authors.forename: Julie L
authors.initials: JL
authors.lastname: Goss
authors.affiliation: Lipid Metabolism Unit, and Department of Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02114 and.
authors.forename: Anita A
authors.initials: AA
authors.lastname: Tseng
authors.affiliation: University of Edinburgh Centre for Inflammation Research, Edinburgh EH16 4TJ, United Kingdom.
authors.forename: Ailiang
authors.initials: A
authors.lastname: Zhang
authors.affiliation: Division of Rheumatology, Allergy, and Immunology, Department of Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02114 and.
authors.forename: Joseph B El
authors.initials: JBE
authors.lastname: Khoury
authors.affiliation: Lipid Metabolism Unit, and Department of Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02114 and. Electronic address: kmoore@molbio.mgh.harvard.edu.
authors.forename: Kathryn J
authors.initials: KJ
authors.lastname: Moore
mesh_terms: D000199:Actins / Q000378:metabolism*; D016229:Amyloid beta-Peptides / Q000378:metabolism; D000818:Animals; D018955:CD36 Antigens / Q000502:physiology*; D002465:Cell Movement; D050719:Crk-Associated Substrate Protein / Q000037:antagonists & inhibitors / Q000235:genetics / Q000502:physiology*; D003599:Cytoskeleton / Q000378:metabolism*; D051418:Focal Adhesion Kinase 2 / Q000378:metabolism; D020935:MAP Kinase Signaling System; D051379:Mice; D008810:Mice, Inbred C57BL; D017628:Microglia / Q000502:physiology*; D051419:Paxillin / Q000378:metabolism; D010766:Phosphorylation; D015398:Signal Transduction; D051193:Toll-Like Receptors / Q000502:physiology; D014443:Tyrosine / Q000378:metabolism
chemical_list: D000199:Actins; D016229:Amyloid beta-Peptides; C493842:Bcar1 protein, mouse; D018955:CD36 Antigens; D050719:Crk-Associated Substrate Protein; D051419:Paxillin; D051193:Toll-Like Receptors; D014443:Tyrosine; D051418:Focal Adhesion Kinase 2; C496053:Ptk2b protein, mouse