Mitochondrial-derived humanin peptides: New citoprotective factors for ovarian cells?

MARVALDI, CAROLINA; MARTÍN, DANIEL; GOTTARDO, MARIA FLORENCIA ; PIDRE, MATIAS; IMSEN, MERCEDES; ROMANOWSKI, VICTOR; SEILICOVICH, ADRIANA; JAITA, GABRIELA

Washington DC

Congreso; 50th Annual Meeting of the Society for the Study of Reproduction; 2017

Society for the Study or Reproduction

Along folliculogenesis, the fate of each follicle is controlled not only by endocrine but also by several paracrine factors. Humanin (HN) and Rattin (rHN, rat homologous peptide) have cytoprotective action in several cell types such as neurons, spermatogonias and Leydig cells. Also, it was reported that HN could be secreted from cells. In the ovary, HN mRNA was shown to be expressed in luteal cells. However, protein expression of HN peptides and their action in the ovary have not been described yet. 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 rHN in ovarian sections from untreated prepuberal rats (rich in preantral follicles), or treated either with DES (rich in early antral follicles) or PMSG (rich in preovulatory follicles). Immunohistochemical (IHC) staining showed rHN expression in granulose and theca cells, and also in oocytes. In PMSG-treated rats, rHN was mainly expressed in theca cells. In ovarian sections from cycling rats the pattern of rHN expression was similar to that of treated prepuberal rats but rHN was also expressed in luteal cells. In addition, KGN cells expressed HN. Also, we analyzed the effect of HN on the 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, means ± SEM of quintuplicate samples from one experiment representative of two. p < 0.01 vs control. ANOVA). In addition, we studied the effect of endogenous HN inhibition using a shRNA plasmid on the apoptosis of KGN cells. HNr shRNA plasmid increased the percentage of apoptotic cells (plcontrol: 42%; plshRNA: 81%. p < 0.01, n=750-800, 2).Our results show that HNr is present in all follicular cells, including oocytes and luteal cells. Considering that the inhibition of endogenous HN increases the apoptosis and exogenous HN increases the viability of KGN cells, our results suggest that HN peptides may play a cytoprotective role in ovarian cells.