Nuclear Receptors, Testosterone, and Posttranslational Modifications in Human INSL3 Promoter Activity in Testicular Leydig Cells

Authors

  • Jacques J. Tremblay,

    1. Reproduction, Perinatal and Child Health, CHUQ Research Centre, Québec City, Québec, Canada
    2. Centre for Research in Biology of Reproduction, Department of Obstetrics and Gynecology, Faculty of Medicine, Université Laval, Québec City, Québec, Canada
    Search for more papers by this author
  • Nicholas M. Robert,

    1. Reproduction, Perinatal and Child Health, CHUQ Research Centre, Québec City, Québec, Canada
    Search for more papers by this author
  • Éric Laguë

    1. Reproduction, Perinatal and Child Health, CHUQ Research Centre, Québec City, Québec, Canada
    Search for more papers by this author

Address for correspondence: Dr. Jacques J. Tremblay, Reproduction, Perinatal and Child Health, CHUQ Research Centre, CHUL Room T1-49, 2705 Laurier Blvd., Québec City, Québec, Canada G1V 4G2. Voice: +418-525-4444 x 46254; fax: +418-654-2765. Jacques-J.Tremblay@crchul.ulaval.ca

Abstract

Insulin-like peptide 3 (INSL3) is a hormone produced by fetal and adult Leydig cells of the mammalian testis. During embryonic life INSL3 is required for testicular descent, whereas in adults it is involved in bone metabolism and male germ cell survival. Despite these important roles, the molecular mechanisms regulating INSL3 expression remain poorly understood. So far, two transcription factors have been implicated in INSL3 transcription: the nuclear receptors SF1 and NUR77. Circumstantial evidence also points to a role for androgens. Using transient transfections in MA-10 Leydig cells, we found that testosterone regulates in a time- and dose-dependent manner the human INSL3 promoter. The INSL3 promoter, however, does not contain a classical androgen-responsive element. Testosterone responsiveness was found to be mediated through an element located in the proximal INSL3 promoter, which also contains a NUR77-SF1-binding site. Furthermore, we found that posttranslational modifications, such as phosphorylation and acetylation, modulate transcription factor activity and therefore also contribute to INSL3 promoter activity in Leydig cells. All together, these data provide new insights into the molecular mechanisms regulating INSL3 expression in the mammalian testis.

Ancillary