RiboTag analysis of actively translated mRNAs in Sertoli and Leydig cells in vivo

This work was supported in part by the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD)/National Institutes of Health (NIH) grant 1R21HD057790-01 (P.S.A.) and 2 R01 HD010808 (M.D.G); the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD)/NIH through cooperative agreement grant U54HD12629 as part of the Specialized Centers Program in Reproduction and Infertility Research (Project 3, G.S.M.); the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD)/NIH Contraception Center Research Grant U54 HD042454 (M.D.G.) and MH086386 to G.S.M. and P.S.A. E.S. and A.Q. were supported by the postdoctoral mobility program of the Spanish Ministry of Science and Innovation (MICINN). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Male spermatogenesis is a complex biological process that is regulated by hormonal signals from the hypothalamus (GnRH), the pituitary gonadotropins (LH and FSH) and the testis (androgens, inhibin). The two key somatic cell types of the testis, Leydig and Sertoli cells, respond to gonadotropins and androgens and regulate the development and maturation of fertilization competent spermatozoa. Although progress has been made in the identification of specific transcripts that are translated in Sertoli and Leydig cells and their response to hormones, efforts to expand these studies have been restricted by technical hurdles. In order to address this problem we have applied an in vivo ribosome tagging strategy (RiboTag) that allows a detailed and physiologically relevant characterization of the ''translatome'' (polysome-associated mRNAs) of Leydig or Sertoli cells in vivo. Our analysis identified all previously characterized Leydig and Sertoli cell-specific markers and identified in a comprehensive manner novel markers of Leydig and Sertoli cells; the translational response of these two cell types to gonadotropins or testosterone was also investigated. Modulation of a small subset of Sertoli cell genes occurred after FSH and testosterone stimulation. However, Leydig cells responded robustly to gonadotropin deprivation and LH restoration with acute changes in polysome-associated mRNAs. These studies identified the transcription factors that are induced by LH stimulation, uncovered novel potential regulators of LH signaling and steroidogenesis, and demonstrate the effects of LH on the translational machinery in vivo in the Leydig cell