Androgens and Notch signaling cooperate in seminiferous epithelium to regulate genes related to germ cell development and apoptosis

Abstract

It was reported previously that in adult males disruption of both androgen and Notch signaling impairs spermatid development and germ cell survival in rodent seminiferous epithelium. To explain the molecular mechanisms of these effects, we focused on the interaction between Notch signaling and androgen receptor (AR) in Sertoli cells and investigate its role in the control of proteins involved in apical ectoplasmic specializations, actin remodeling during spermiogenesis, and induction of germ cell apoptosis. First, it was revealed that in rat testicular explants ex vivo both testosterone and Notch signaling modulate AR expression and cooperate in the regulation of spermiogenesis-related genes (Nectin2, Afdn, Arp2, Eps8) and apoptosis-related genes (Fasl, Fas, Bax, Bcl2). Further, altered expression of these genes was found following exposure of Sertoli cells (TM4 cell line) and germ cells (GC-2 cell line) to ligands for Notch receptors (Delta-like1, Delta-like4, and Jagged1) and/or Notch pathway inhibition. Finally, direct interactions of Notch effector, Hairy/enhancer-of-split related with YRPW motif protein 1, and the promoter of Ar gene or AR protein were revealed in TM4 Sertoli cells. In conclusion, Notch pathway activity in Sertoli and germ cells regulates genes related to germ cell development and apoptosis acting both directly and indirectly by influencing androgen signaling in Sertoli cells.

Keywords: Androgens; Apoptosis; Notch pathway; Seminiferous epithelium; Sertoli cells; Spermiogenesis.