Hsp70/CHIP/Nox4 NAD(P)H-oxidase INTERACTION IN THE OXIDATIVE EFFECT OF LOSARTAN ON PROXIMAL TUBULE CELLS (PTCs) FROM SPONTANEOUSLY HYPERTENSIVE RATS

GIL LORENZO ANDREA FERNANDA; BOCANEGRA VICTORIA; COSTANTINO VALERIA; BENARDON MARIA EUGENIA; CACCIAMANI VALERIA; GARRAMUÑO DE VALLES PATRICIA

Mendoza

Congreso; XXXI Reunión Científica Anual de la Sociedad de Biología de Cuyo; 2013

The chaperone Hsp70 regulates a diverse set of signaling pathways. CHIP (Carboxyl terminus of the Hsc70-Interacting Protein) is a E3 ubiquitin ligase that targets proteins for poly-ubiquitination and degradation. We investigated Hsp70/CHIP contribution to Nox4 regulation after AT1R receptor blockade in primary culture of PTCs. PTCs from 8-week SHR and WKY rats were stimulated with Angiotensin II (100 nmol/L, 15min) (AII), pretreated with Losartan (100 μmol/L, 90min) (L) and with Losartan 75min plus Angiotensin II 15min (L+AII). Losartan increased Caveolin-1 expression, increased Hsp70 and decreased Nox4 protein levels in SHR (L) membranes fraction. Decreased Hsp70 in SHR (L) vs SHR (AII) in cytosolic fraction confirm Hsp70 translocation to membranes. Increased levels of Hsp70/CHIP contrasts with the decreased immunoprecipitation of Nox4 in SHR (L) vs SHR (AII) membranes. Then, we silenced Hsp72 protein expression. Hsp72 depletion was associated with higher Nox4 expression and increased NAD(P)H oxidase activity in SHR (L+AII) vs SHR (L+AII) without transfection. After Hsp72 silencing of PTCs from SHR (AII), Losartan could not prevent AII-enhanced Nox 4 expression and NAD(P)H-oxidase activity. Membrane interaction of Hsp70/CHIP may induceNox4 protein degradation, involved in the cytoprotective effect of Losartan in PCTs from SHR.