The long-term goal of this project remains to determine the molecular and cellular mechanisms by which testosterone regulates spermatogenesis. Testosterone is essential for fertility and targets Sertoli cells in the mammalian testis through the androgen receptor (AR) to produce factors and provide an environment required for germ cell survival and development. Numerous critical Sertoli cell activities have been found to be dependent on testosterone including 1) the formation of tight junctions between Sertoli cells that form the essential blood-testis barrier, 2) the remodeling of Sertoli cell-round spermatid attachments and the retention of round spermatids, 3) the release of mature spermatozoa. Although testosterone had been known to be required for these functions, the mechanisms by which testosterone acts are not well understood. We recently characterized an alternative, rapid (<1 min) and sustained mechanism of testosterone action (the non-classical pathway) that causes the phosphorylation and activation of the Src and ERK kinases, the epidermal growth factor receptor and the CREB transcription factor. We will test the overall hypothesis that critical spermatogenesis supporting functions of testosterone are mediated via the non-classical pathway.
Aim 1 is to determine whether non-classical signaling by testosterone regulates Sertoli-Sertoli and Sertoli-germ cell adhesion in culture. We will test the hypothesis that non-classical testosterone actions are required for Sertoli-germ cell attachment. We will determine whether the non-classical pathway regulates mRNA expression, protein levels or the phosphorylation status of factors known to maintain Sertoli-Sertoli adhesion and Sertoli-germ cell attachment.
Aim 2 is to determine whether non-classical testosterone actions are required to release mature spermatozoa from seminiferous tubules. We will determine whether testosterone activates Src and ERK kinases in cultured seminiferous tubules. We will quantify spermatozoa release from cultured seminiferous tubule fragments in the presence and absence of testosterone and inhibitors of the non-classical testosterone signaling pathway. This study will determine mechanisms by which testosterone supports spermatogenesis and identify new drug targets that may be used to regulate male fertility.

Public Health Relevance

This proposal will identify the mechanisms by which testosterone regulates processes critical for the production of spermatozoa and thus male fertility. The data obtained from this study will identify new targets for contraceptive drugs and reveal mechanisms to enhance male fertility.

Agency
National Institute of Health (NIH)
Institute
Eunice Kennedy Shriver National Institute of Child Health & Human Development (NICHD)
Type
Research Project (R01)
Project #
2R01HD043143-06A1
Application #
7524006
Study Section
Cellular, Molecular and Integrative Reproduction Study Section (CMIR)
Program Officer
Moss, Stuart B
Project Start
2002-12-01
Project End
2011-07-31
Budget Start
2009-08-01
Budget End
2010-07-31
Support Year
6
Fiscal Year
2009
Total Cost
$336,871
Indirect Cost
Name
University of Pittsburgh
Department
Physiology
Type
Schools of Medicine
DUNS #
004514360
City
Pittsburgh
State
PA
Country
United States
Zip Code
15213
Toocheck, Corey; Clister, Terri; Shupe, John et al. (2016) Mouse Spermatogenesis Requires Classical and Nonclassical Testosterone Signaling. Biol Reprod 94:11
Smith, Lee B; Walker, William H (2014) The regulation of spermatogenesis by androgens. Semin Cell Dev Biol 30:2-13
Shupe, John; Cheng, Jing; Puri, Pawan et al. (2011) Regulation of Sertoli-germ cell adhesion and sperm release by FSH and nonclassical testosterone signaling. Mol Endocrinol 25:238-52
Walker, William H (2011) Testosterone signaling and the regulation of spermatogenesis. Spermatogenesis 1:116-120
Walker, William H (2010) Non-classical actions of testosterone and spermatogenesis. Philos Trans R Soc Lond B Biol Sci 365:1557-69
Walker, William H (2009) Molecular mechanisms of testosterone action in spermatogenesis. Steroids 74:602-7
Cheng, Jing; Watkins, Simon C; Walker, William H (2007) Testosterone activates mitogen-activated protein kinase via Src kinase and the epidermal growth factor receptor in sertoli cells. Endocrinology 148:2066-74
Walker, William H; Cheng, Jing (2005) FSH and testosterone signaling in Sertoli cells. Reproduction 130:15-28
Fix, Charity; Jordan, Cynthia; Cano, Patricia et al. (2004) Testosterone activates mitogen-activated protein kinase and the cAMP response element binding protein transcription factor in Sertoli cells. Proc Natl Acad Sci U S A 101:10919-24