title: Two different PDGF beta-receptor cohorts in human pericytes mediate distinct biological endpoints.
abstract: How activation of a specific growth factor receptor selectively results in either cell proliferation or cytoskeletal reorganization is of central importance to the field of pathophysiology. In this study, we report on a novel mechanism that explains how this process is accomplished. Our current investigation demonstrates that soluble platelet derived growth factor- (PDGF)-BB activates a cohort of PDGF-beta receptors primarily confined to the lipid raft component of the cell membrane, specifically caveolae. In contrast, cell-bound PDGF-BB delivered via cell-cell contact results in activation and the subsequent up-regulation of a cohort of PDGF beta-receptors primarily confined to the non-lipid raft component of the cell membrane. Individual activation of these two receptor cohorts results in distinct biological endpoints, cytoskeletal reorganization or cell proliferation. Mechanistically, our evidence suggests that PDGF-BB-bearing cells preferentially stimulate the non-lipid raft receptor cohort through interleukin 1beta-mediated inhibition of the lipid raft cohort of receptors, leaving the non-raft receptor cohort operational and preferentially stimulated. In human skin injected with PDGF-BB and in tissue reparative processes PDGF beta-receptors colocalize with the caveolae/lipid raft marker caveolin-1. In contrast, in human skin injected with PDGF-BB-bearing tumor cells and in colorectal adenocarcinoma, activated PDGF beta-receptors do not colocalize with caveolin-1. Thus, growth factor receptors are segregated into specific cell membrane compartments that are preferentially activated through different mechanisms of ligand delivery, resulting in distinct biological endpoints.
authors.affiliation: Department of Orthopaedic Surgery, Children's' Hospital, Boston, Massachusetts 02115, USA.
authors.forename: Christian
authors.initials: C
authors.lastname: Sundberg
authors.forename: Tomas
authors.initials: T
authors.lastname: Friman
authors.forename: Leah E
authors.initials: LE
authors.lastname: Hecht
authors.forename: Christine
authors.initials: C
authors.lastname: Kuhl
authors.forename: Keith R
authors.initials: KR
authors.lastname: Solomon
mesh_terms: D000077214:Becaplermin; D021941:Caveolae / Q000378:metabolism*; D051242:Caveolin 1 / Q000378:metabolism; D002450:Cell Communication / Q000502:physiology; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D049109:Cell Proliferation; D018920:Coculture Techniques; D003599:Cytoskeleton / Q000378:metabolism*; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D015151:Immunoblotting; D047468:Immunoprecipitation; D053583:Interleukin-1beta / Q000378:metabolism; D021962:Membrane Microdomains / Q000378:metabolism; D018613:Microscopy, Confocal; D046529:Microscopy, Electron, Transmission; D020286:Pericytes / Q000378:metabolism*; D010982:Platelet-Derived Growth Factor / Q000378:metabolism; D020574:Proto-Oncogene Proteins c-sis; D020797:Receptor, Platelet-Derived Growth Factor beta / Q000378:metabolism*; D015854:Up-Regulation
chemical_list: D051242:Caveolin 1; D053583:Interleukin-1beta; D010982:Platelet-Derived Growth Factor; D020574:Proto-Oncogene Proteins c-sis; D000077214:Becaplermin; D020797:Receptor, Platelet-Derived Growth Factor beta