Characterization of signal transduction pathways in human bone marrow endothelial cells.
Human bone marrow endothelial cells immortalized with the T antigen of SV40 (TrHBMEC) have previously been characterized by us with regard to their properties that are similar to primary marrow endothelial cells and their utility as a model system. We now report that TrHBMEC express a recently discovered signal transduction molecule termed RAFTK (related adhesion focal tyrosine kinase), also called Pyk2 or CAK-beta. RAFTK, the second member of the focal adhesion kinase (FAK) family, is known to be activated in response to calcium flux in neuronal cells and integrin stimulation in megakaryocytes and B cells. We have studied the effects of cytokines on RAFTK activation in TrHBMEC. Treatment of TrHBMEC with the vascular endothelial growth factor (VEGF), as well as the VEGF-related protein (VRP), the recently identified ligand for the FLT-4 receptor, resulted in enhanced tyrosine phosphorylation of RAFTK. Similar changes in RAFTK phosphorylation were observed upon stimulation of TrHBMEC with basic fibroblast growth factor (bFGF) or oncostatin M (OSM). Stimulation of these cells with growth factors also resulted in an increase in RAFTK activity and the c-Jun NH2-terminal kinase (JNK). RAFTK coimmunoprecipitated with the cytoskeletal protein paxillin through its C-terminal proline-rich domain in TrHBMEC. These results suggest that, in marrow endothelium, activation of RAFTK by VEGF, VRP, OSM, and bFGF represents a new element in the signal transduction pathways used by these growth factors and likely acts to coordinate signaling from their surface receptors to the cytoskeleton, thereby modulating cell growth and function.
Liu
Z Y
ZY
Division of Experimental Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02115, USA.
Ganju
R K
RK
Wang
J F
JF
Schweitzer
K
K
Weksler
B
B
Avraham
S
S
Groopman
J E
JE
D001853:Bone Marrow / Q000502:physiology*; D001854:Bone Marrow Cells; D002352:Carrier Proteins / Q000494:pharmacology; D003598:Cytoskeletal Proteins / Q000378:metabolism; D016228:Endothelial Growth Factors / Q000494:pharmacology; D004727:Endothelium / Q000502:physiology*; D004789:Enzyme Activation; D016222:Fibroblast Growth Factor 2 / Q000494:pharmacology; D019084:Fluorescent Antibody Technique, Indirect; D051418:Focal Adhesion Kinase 2; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases; D008222:Lymphokines / Q000494:pharmacology; D048670:MAP Kinase Kinase 4; D020929:Mitogen-Activated Protein Kinase Kinases; D053683:Oncostatin M; D051419:Paxillin; D010455:Peptides / Q000494:pharmacology; D010750:Phosphoproteins / Q000378:metabolism; D010766:Phosphorylation; D019000:Phosphotyrosine / Q000378:metabolism; D011494:Protein Kinases / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D020794:Receptor Protein-Tyrosine Kinases / Q000378:metabolism*; D011956:Receptors, Cell Surface / Q000378:metabolism*; D017978:Receptors, Growth Factor / Q000378:metabolism*; D040262:Receptors, Vascular Endothelial Growth Factor; D015398:Signal Transduction; D042461:Vascular Endothelial Growth Factor A; D042561:Vascular Endothelial Growth Factor B; D040321:Vascular Endothelial Growth Factor Receptor-3; D042442:Vascular Endothelial Growth Factors
D002352:Carrier Proteins; D003598:Cytoskeletal Proteins; D016228:Endothelial Growth Factors; D008222:Lymphokines; C508351:OSM protein, human; C496061:PXN protein, human; D051419:Paxillin; D010455:Peptides; D010750:Phosphoproteins; D011956:Receptors, Cell Surface; D017978:Receptors, Growth Factor; D042461:Vascular Endothelial Growth Factor A; D042561:Vascular Endothelial Growth Factor B; D042442:Vascular Endothelial Growth Factors; D016222:Fibroblast Growth Factor 2; D053683:Oncostatin M; D019000:Phosphotyrosine; D011494:Protein Kinases; D011505:Protein-Tyrosine Kinases; D020794:Receptor Protein-Tyrosine Kinases; D040262:Receptors, Vascular Endothelial Growth Factor; D040321:Vascular Endothelial Growth Factor Receptor-3; D051418:Focal Adhesion Kinase 2; D048031:JNK Mitogen-Activated Protein Kinases; D048670:MAP Kinase Kinase 4; D020929:Mitogen-Activated Protein Kinase Kinases