INVESTIGADORES
ZARATE Sandra Cristina
congresos y reuniones científicas
Título:
Estradiol induces the rapid trafficking of membrane-associated ERá isoforms in pituitary cells
Autor/es:
ZÁRATE SANDRA; JAITA GABRIELA; FERRARIS JIMENA; EIJO GUADALUPE; MAGRI LAURA; PISERA DANIEL; SEILICOVICH ADRIANA
Lugar:
Florencia
Reunión:
Congreso; ICE-ECE 2012; 2012
Resumen:
In the pituitary, estrogens regulate several cell functions via the activation of membrane-associated estrogen receptors (mERs). We have previously reported that both 17â-estradiol (E2) and membrane-impermeable E2-BSA induce rapid apoptotic actions in anterior pituitary (AP) cells, lactotropes and somatotropes through the activation of mERs. In the present study, we investigated the involvement of mERa in the apoptotic action of E2 in lactotropes. We also studied the expression of mERa variants in AP cells during the estrous cycle and the regulation of this receptor expression by E2. Cultured anterior pituitary cells from ovariectomized (OVX) Wistar rats were incubated with E2-BSA (10-9M) in the presence of an ERa selective antagonist, MPP (10-7 M), for 120 min. Apoptotic lactotropes were identified by TUNEL and immunocytochemistry for prolactin. The expression of mERa isoforms was studied in AP cells from rats at proestrus (P) or diestrus I (D) by surface biotinylation and Western Blot. The expression of mERa was also studied in AP cells from OVX rats incubated with E2 (10-9M) for 0-120 min. E2-BSA increased the percentage of TUNEL-positive lactotropes (p<0.001, c2) but failed to induce apoptosis in lactotropes coincubated with MPP. Three mERa isoforms of 66, 39 and 20-24 kDa were detected in AP cells. mERa66 expression was higher at P vs D (p<0.05), whereas mERa20-24 was lower (p<0.05). E2 increased the expression of mERa66 and mERa39 (p<0.05, ANOVA) but not of mERa20-24 at 30 min. Intracellular ERa isoforms remained unchanged during the estrous cycle or after E2 incubation. Our results suggest that E2 induces the rapid trafficking of mERa isoforms to the plasma membrane of AP cells. At proestrus, the high circulating E2 levels could participate in the transient expression of mERa66, which may be involved in the apoptotic action of E2 in the pituitary at this stage of the estrous cycle.