An Androgen Response‐Like Element Half‐Site Is Essential For Androgen Regulation Of Gonadotropin Regulated Testicular RNA Helicase (GRTH/DDX25) Transcription

Abstract

GRTH is a testis‐specific member of the DEAD‐box family of RNA helicases which is present in Leydig and germ cells and is essential for spermatogenesis. It is the only known RNA helicase to be hormonally regulated. GRTH is transcriptionally up‐regulated by hCG via cAMP‐induced androgen (A) in Leydig cells. To gain insights into the mechanism of androgen regulation, immortalized rat hypothalamic GnRH neurons that express GRTH mRNA were used to generate a stable cell line expressing the A receptor (GT1‐7AR). The significantly A‐induced GRTH expression (mRNA/protein) in GT1‐7AR was prevented by the AR antagonist Nilutamide. Two putative ARE atypical half sites were present at −800 (ARE2) and −200 bp (ARE1) of GRTH gene. Functional analysis of sequential deleted GRTH 5' flanking sequence in GT1‐7AR treated with dihydrotestosterone (DHT) and/or Nilutamide revealed an active AR response region at −1085/−500 bp. Point mutation of ARE2 prevented A‐induced up‐regulation of GRTH transcription. ChIP using AR antibody in GT1‐7AR cells treated with DHT revealed AR recruitment to GRTH (−980/−702 bp) containing ARE2 compared to control. No binding activity was associated with ARE1. We conclude that ARE2 plays a key role in the androgen regulation of the GRTH gene transcription. Our findings provide valuable insights for future elucidation of androgen regulated GRTH function during germ cell development. Supported‐IRP, NICHD