Expression and function of Humanin peptides in ovarian cells

MARVALDI CAROLINA; JAITA G; MARTIN DANIEL; SEILICOVICH A; IMSEN M

Buenos Aires

Jornada; XVIII Jornada Anual de la Sociedad Argentina de Biología; 2016

Humanin (HN) and Rattin (HNr, rat homologous peptide) have cytoprotective action in several cell types such as neurons, spermatogonias and Leydig cells. However, little is known about the expression of these peptides in the ovary. We aimed to explore the expression and function of HN peptides in the ovary from prepuberal rats, cycling adult rats and in a human granulosa-like tumor cell line (KGN). We investigated the expression of HNr in ovarian sections from untreated prepuberal rats (rich in preantral follicles), or treated with DES (rich in early antral follicles) or PMSG (rich in preovulatory follicles). Immunohistochemical staining showed HNr expression in granulose and theca cells, and also in oocytes. The HNr expression pattern was similar among follicles of the same type in untreated or treated prepubertal rats. In PMSG-treated rats, HNr was mainly expressed in theca cells. In ovarian sections from cycling rats the pattern of HNr expression was similar to that of treated prepuberal rats but HNr was also expressed in luteal cells. To study the role of HNr in the ovary, we colocalized TUNEL+ cells and HNr+ cells in ovarian sections from prepuberal PMSG-treated rats. HNr+ cells were TUNEL-negative. Cultures of KGN cells showed HN expression. We analyzed the effect of HN on viability of KGN cells by MTT assay. HN increased the viability of KGN cells (C: 0.24 ± 0.02, HN 0.25 µM: 0.40 ± 0.02, HN 0.5 µM: 0.36 ± 0.02, HN 1µM: 0.41 ± 0.01, p < 0.01 vs control). Our results showed that HNr is present in all follicular cells, including oocytes, with strong intensity in luteal cells. Considering that HNr is absent in apoptotic ovarian cells and that HN increases the viability of KGN cells, our results suggest that HNr/HN may play a cytoprotective action in ovarian cells.