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Tyrosine phosphorylation of caveolin-1 in the endothelium

T Aoki1, R Nomura, T Fujimoto

  • 1Department of Anatomy and Cell Biology, Gunma University School of Medicine, 3-39-22 Showa-machi, Maebashi, 371-8511, Japan.

Experimental Cell Research
|December 10, 1999
PubMed

Insights

Tyrosine phosphorylation of caveolin-1 occurs in rat endothelium, particularly under oxidative stress. This phosphorylation event is linked to changes in caveolae structure, suggesting a role in caveolar vesiculation and fusion.

Area of Science:

  • Cell Biology
  • Biochemistry
  • Vascular Biology

Background:

  • Caveolin-1 is a key scaffolding protein in caveolae.
  • Src kinases phosphorylate caveolin-1 on tyrosine residues.
  • A specific antibody (PY14) targets caveolin-1 phosphorylated at tyrosine-14.

Purpose of the Study:

  • To investigate the in vivo localization of tyrosine-phosphorylated caveolin-1 in rat tissues.
  • To examine the conditions inducing tyrosine phosphorylation of caveolin-1 in cultured endothelial cells.
  • To elucidate the relationship between caveolin-1 phosphorylation and caveolae morphology.

Main Methods:

  • Immunohistochemistry using the PY14 antibody on normal rat tissue sections.
  • Culture of endothelial cells and exposure to oxidative stress and/or tyrosine phosphatase inhibitors.
  • Treatment with kinase inhibitors (herbimycin A, genistein) and vasoactive agents.

Main Results:

  • Tyrosine phosphorylation of caveolin-1 was detected in the endothelium of capillaries and small venules.
  • Phosphorylation was induced in cultured endothelial cells by oxidative stress or phosphatase inhibitors, but not by vasoactive reagents.
  • Inhibition of Src kinases (herbimycin A) or general tyrosine phosphorylation (genistein) blocked the reaction.
  • Increased phosphorylation correlated with decreased invaginated caveolae and increased cytoplasmic vesicles containing caveolin-1.

Conclusions:

  • Tyrosine phosphorylation of caveolin-1 at tyrosine-14 occurs in normal rat endothelium in vivo.
  • Oxidative stress and altered phosphatase activity can trigger caveolin-1 tyrosine phosphorylation in endothelial cells.
  • Caveolin-1 tyrosine phosphorylation may induce caveolar vesiculation and/or fusion, impacting endothelial cell function.

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