Angiotensin II mediates Tyr-dephosphorylation in rat fetal kidney membranes.
Angiotensin II (Ang II) elicits a variety of physiological effects through specific Ang II receptors in numerous tissues. In addition, Ang II is a modulator of cellular growth and exerts a positive or negative effect on cell growth depending on which receptor subtype is activated. Expression of the intrarenal AT2 receptors occurs at its highest levels in the fetal kidney, with a rapid decline after birth. In the present paper, we performed a study on the signaling mechanism of Ang II receptors in rat fetal (E20) kidney, a rich source of AT2 receptors, where both Ang II receptor subtypes are present. Ang II induces Tyr-dephosphorylation of proteins in rat fetal kidney membranes. The response is dose-dependent, with a reduction of 20% with respect to the control (100%), signal that is completely reversed by Ang IIAT2 competitor PD123319. Orthovanadate, the inhibitor of phospho-Tyr-phosphatases (PTPase), reverts Ang II effect, suggesting the involvement of a protein tyrosine phosphatase. The peptide analog of Ang II, CGP42112, exhibits an agonist effect, which is dose-dependent. Thus, in rat fetal (E20) kidney, the Ang-induced protein Tyr-dephosphorylation of several proteins is mediated by AT2 receptors, mechanism that involves an orthovanadate sensitive PTPase.
Alvarez
Sergio E
SE
Bioquímica Avanzada, Depto. Bioquímica y Cs. Biológicas, Facultad de Química, Bioquímica y Farmacia, Universidad Nacional de San Luis, San Luis, Argentina.
Fuentes
Lucia B
LB
Ciuffo
Gladys M
GM
D000804:Angiotensin II / Q000378:metabolism / Q000502:physiology*; D000818:Animals; D015153:Blotting, Western; D002462:Cell Membrane / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004591:Electrophoresis, Polyacrylamide Gel; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D007093:Imidazoles / Q000494:pharmacology; D015151:Immunoblotting; D007668:Kidney / Q000196:embryology*; D009842:Oligopeptides / Q000494:pharmacology; D010766:Phosphorylation; D019000:Phosphotyrosine / Q000737:chemistry; D011725:Pyridines / Q000494:pharmacology; D051381:Rats; D011921:Rats, Inbred WKY; D015398:Signal Transduction; D014443:Tyrosine / Q000737:chemistry*; D014638:Vanadates / Q000494:pharmacology
D004791:Enzyme Inhibitors; D007093:Imidazoles; D009842:Oligopeptides; D011725:Pyridines; D000804:Angiotensin II; C060894:CGP 42112A; C073402:PD 123319; D019000:Phosphotyrosine; D014638:Vanadates; D014443:Tyrosine