Tyrosine phosphorylation of caveolin-1 in the endothelium.
Caveolin-1, a scaffolding protein of caveolae, is known to be tyrosine-phosphorylated by Src kinases. Recently we generated a specific antibody to caveolin-1 phosphorylated at tyrosine-14 (PY14) (R. Nomura and T. Fujimoto, 1999, Mol. Biol. Cell 10, 975-986). In the present study, by applying PY14 to sections of normal rat tissues, we found that tyrosine phosphorylation of caveolin-1 occurred in limited locations, including the endothelium of the continuous capillaries and small venules. Cultured endothelial cells were not labeled by PY14 under a standard culture condition, but became positively labeled when exposed to oxidative stresses and/or tyrosine phosphatase inhibitors. The reaction was prohibited by pretreating the cells with herbimycin A or genistein. Vasoactive reagents or physical stimuli did not cause the phosphorylation. Concomitant with the tyrosine phosphorylation, the number of invaginated caveolae decreased drastically, and vesicles labeled intensely for caveolin-1 appeared in the cytoplasm; the average diameter of the vesicles was larger than that of caveolae. The result implies that tyrosine phosphorylation of caveolin-1 occurs at tyrosine-14 in the normal rat endothelium in vivo and may induce caveolar vesiculation and/or fusion.
Aoki
T
T
Department of Anatomy and Cell Biology, Gunma University School of Medicine, 3-39-22 Showa-machi, Maebashi, 371-8511, Japan.
Nomura
R
R
Fujimoto
T
T
D000818:Animals; D001011:Aorta / Q000166:cytology; D002417:Cattle; D051242:Caveolin 1; D022461:Caveolins; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000737:chemistry / Q000166:cytology / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D007425:Intracellular Membranes / Q000737:chemistry / Q000378:metabolism / Q000648:ultrastructure; D008565:Membrane Proteins / Q000032:analysis / Q000378:metabolism*; D016253:Microscopy, Immunoelectron; D018384:Oxidative Stress / Q000187:drug effects / Q000502:physiology; D010766:Phosphorylation; D051381:Rats; D014443:Tyrosine / Q000378:metabolism*; D014471:Umbilical Veins / Q000166:cytology; D014638:Vanadates / Q000494:pharmacology
C495540:CAV1 protein, human; C495537:Cav1 protein, rat; D051242:Caveolin 1; D022461:Caveolins; D004791:Enzyme Inhibitors; D008565:Membrane Proteins; C076715:pervanadate; D014638:Vanadates; D014443:Tyrosine