Neurohypophysial peptides stimulate the phosphorylation of pre-T cell focal adhesion kinases.
Thymic oxytocin (OT) behaves as a cryptocrine signal targeted at the outer surface of thymic epithelial cell plasma membrane from where OT is able to interact with neurohypophysial peptide receptors expressed by pre-T cells. Immature T cells bear a receptor of the V1 subtype, while OT receptors are predominantly expressed by cytotoxic CD8+ lymphocytes. In both T cell types, neurohypophysial peptide receptors transduce OT via the phosphoinositide pathway. Protein tyrosine phosphorylation is an early event of T cell activation. Western blots of murine pre-T cells (RL12-NP line) proteins probed with anti-phosphotyrosine (PY-20) revealed a great number of proteins the phosphorylation of which increased either with OT or vasopressin treatment. Two were immunoprecipitated with anti-focal adhesion kinase (FAK) mAb 2A7 and were identified one as p125FAK and the other as a coprecipitating 130-kDa protein. The p125FAK is connected to the Ras/MAPK pathway and is also implicated in TCR/CD3 signalling in T cell. Another protein phosphorylated by OT in RL12-NP was identified as paxillin, a 68-kDa protein localised at focal adhesion sites and associated with p 125FAK. These results indicate that phosphorylation of focal adhesion kinase may be induced in pre-T cell by thymic OT.
Martens
H
H
Laboratory of Radio-Immunology and Neuroendocrine-Immunology, Institute of Pathology CHU-B23, University of Liège, Liège-Sart Tilman, Belgium. hmartens@ulg.ac.be
Kecha
O
O
Charlet-Renard
C
C
Defresne
M P
MP
Geenen
V
V
D000818:Animals; D015815:Cell Adhesion Molecules / Q000378:metabolism*; D002460:Cell Line; D003598:Cytoskeletal Proteins / Q000378:metabolism; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; D051379:Mice; D051419:Paxillin; D010455:Peptides / Q000378:metabolism*; D010750:Phosphoproteins / Q000378:metabolism; D010766:Phosphorylation; D010904:Pituitary Gland, Posterior / Q000378:metabolism*; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D013234:Stem Cells / Q000201:enzymology*; D013268:Stimulation, Chemical; D013601:T-Lymphocytes / Q000166:cytology / Q000201:enzymology*
D015815:Cell Adhesion Molecules; D003598:Cytoskeletal Proteins; D051419:Paxillin; D010455:Peptides; D010750:Phosphoproteins; C496062:Pxn protein, mouse; D011505:Protein-Tyrosine Kinases; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; C496051:Ptk2 protein, mouse