Signaling pathways involved in the antiapoptotic effect of Humanin in pituitary cells

S. ZARATE; D. PISERA; G. JAITA; F.GOTTARDO; J.FERRARIS; V.ROMANOWSKI; A. SEILICOVICH; M. MORENO AYALA; M.PIDRE; M. CANDOLFI

Boston

Congreso; 97º Annual Meeting of the Endocrine Society; 2016

Humanin (HN) is a 24-amino acid peptide originally isolated from a cDNA library of surviving neurons of familial Alzheimer´s disease. HN has a cytoprotective action in several cell types such as neurons, lymphocytes and testicular germ cells. Rattin (HNr), a homologous peptide of HN in the rat, has also a cytoprotective action. Previously, we have shown that HNr is expressed in normal and tumor pituitary cells in which it inhibited the apoptotic affect of TNF-α. The aim of the present study was to identify the signaling pathways that mediate the anti-apoptotic effect of HN in GH3 cells, a somatolactotrope cell line. HN has been shown to interact with two classes of receptors. It binds to the formylpeptide receptor-like-1 (FPRL-1) receptor, and also to a receptor complex with three subunits consisting of WSX-1 (IL-27 receptor), ciliary neurotrophic factor receptor α (CNTFR), and glycoprotein 130 (gp130), a subunit ofinterleukin-6 receptor. After binding to its specific receptor, HN Mediates its protective effect through activation of STAT3, JNK and tyrosine kinases. In order to study the mechanisms involved in HN action,GH3 cells were incubated with HN (0.05 μM) and TNF-α (50 ng/ml) in the presence of inhibitors of STAT3, AKT, MEK, JNK and p38, and apoptosis was determined by TUNEL. Inhibition of STAT3 with JSI-124 blocked the anti-apoptotic effect of HN (TNF-α: 9.5%; TNF-α-HN: 4.3%; TNF-α-JSI-124: 10.2%; TNF-α-HN-JSI-124: 8.7%, p