Caveolin-enriched membrane signaling complexes in human and murine osteoblasts.
Osteoblasts receive regulatory signals from hormones, growth factors, calcium, extracellular matrix, and other cells through a variety of receptors that utilize an array of signaling pathways and cytoplasmic messengers. This article addresses the nonuniform distribution of important signaling molecules (platelet-derived growth factor receptors [PDGFRs], nonreceptor tyrosine kinases, tyrosine kinase adaptor proteins, G proteins, and nitric oxide synthases [NOSs]) in the surface membranes of human and murine osteoblasts. We show that particular inner leaflet signaling molecules (e.g., heterotrimeric G proteins and Src family tyrosine kinases) are clustered and concentrated in Triton X-100-insoluble membranes that are enriched in caveolin, the major structural component of caveolae (50- to 100-nm flask-shaped invaginations of the plasma membrane that apparently are organized by oligomers of the protein caveolin). In addition, we show that a subset of highly ligand-responsive PDGFRs and mitogen-activated protein (MAP) kinase pathway effectors are present in the caveolin-enriched membrane fraction of osteoblasts.
Solomon
K R
KR
Department of Orthopedic Surgery, Children's Hospital, Boston, Massachusetts 02115, USA.
Danciu
T E
TE
Adolphson
L D
LD
Hecht
L E
LE
Hauschka
P V
PV
D000818:Animals; D021941:Caveolae / Q000378:metabolism*; D051242:Caveolin 1; D022461:Caveolins / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D019204:GTP-Binding Proteins / Q000378:metabolism*; D006801:Humans; D015151:Immunoblotting; D051379:Mice; D019001:Nitric Oxide Synthase / Q000378:metabolism*; D010006:Osteoblasts / Q000378:metabolism*; D010766:Phosphorylation; D011233:Precipitin Tests; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D051381:Rats; D017479:Receptors, Platelet-Derived Growth Factor / Q000378:metabolism*; D015398:Signal Transduction; D014443:Tyrosine / Q000378:metabolism
C495540:CAV1 protein, human; C495541:Cav1 protein, mouse; C495537:Cav1 protein, rat; D051242:Caveolin 1; D022461:Caveolins; D014443:Tyrosine; D019001:Nitric Oxide Synthase; D011505:Protein-Tyrosine Kinases; D017479:Receptors, Platelet-Derived Growth Factor; D019204:GTP-Binding Proteins