Mammalian spermatogenesis is supported by a robust stem cell system that exquisitely balances self renewal with differentiation. Spermatogonial stem cells (SSCs) and their progenitors lie on the basal side of the Sertoli cell tight junctions and therefore outside the blood-testis barrier making them readily accessible targets for contraceptive intervention. Cells that manifest stem cell properties reside within a population of cells referred to as undifferentiated spermatogonia (Aundiff)- Different cells within the Aundiff population contribute to the stem cell pool during steady state spermatogenesis than during regeneration. Our proposed studies address the regulation of local signaling within the stem cell niche as well as germ cell intrinsic factors that regulate stem cell self-renewal, proliferation and differentiation. We propose that heparin sulfate proteoglycans (HSPGs) within the extracellular matrix (ECM) and on the surface of SSCs regulate the bioavailability of glial cell line-derived neurotrophic factor (GDNF), a critical signaling molecule expressed by Sertoli cells that is required for stem cell self-renewal. Using a combination of live cell imaging of fluorescently labeled SSCs in seminiferous tubule explants, germ cell transplantation and gerietic analysis in vivo, we will test the hypothesis that GDNF regulates SSC self-renewal by acting as a chemoattractant to sequester SSCs from inductive differentiation signals. In preliminary studies we have established a critical role for LIN28A, a highly-conserved RNA binding protein and regulator of the let-7 class of miRNAs that is expressed in Aundif1 in regulating the size of the Aundiff compartment. We propose experiments to distinguish between a role for LIN28A in proliferation and differentiation of Aund/Yf spermatogonia. Lastly, to discover additional regulators of SSC self-renewal, we will use high-throughput sequencing of RNA (RNAseq) isolated from polysomes of SSCs, Sertoli cells and peritubular myoid cells obtained from testis that are blocked in the transition from Aal to A1 spermatogonia under conditions of steady-state and regenerative SSC self-renewal.

Public Health Relevance

There is an unmet need throughout the world for more contraceptive options for men. This proposal is focused on discovering the basic mechanisms used to regulate spermatogonial stem cell self-renewal and differentiation. We seek to discover both extrinsic and intrinsic regulators of SSCs with the belief that these will lead to novel targets of contraceptive intervention and a better understanding of the consequences of contraceptive regimens currently under consideration.

Agency
National Institute of Health (NIH)
Institute
Eunice Kennedy Shriver National Institute of Child Health & Human Development (NICHD)
Type
Specialized Center--Cooperative Agreements (U54)
Project #
5U54HD042454-12
Application #
8546435
Study Section
Special Emphasis Panel (ZHD1-DRG-H)
Project Start
Project End
Budget Start
2013-07-01
Budget End
2014-06-30
Support Year
12
Fiscal Year
2013
Total Cost
$377,826
Indirect Cost
$97,411
Name
University of Washington
Department
Type
DUNS #
605799469
City
Seattle
State
WA
Country
United States
Zip Code
98195
Cooper, Lori A; Page, Stephanie T (2014) Androgens and prostate disease. Asian J Androl 16:248-55
Surampudi, P; Page, S T; Swerdloff, R S et al. (2014) Single, escalating dose pharmacokinetics, safety and food effects of a new oral androgen dimethandrolone undecanoate in man: a prototype oral male hormonal contraceptive. Andrology 2:579-87
Chao, Jing; Page, Stephanie T; Anderson, Richard A (2014) Male contraception. Best Pract Res Clin Obstet Gynaecol 28:845-57
Amory, John K; Hong, SungWoo; Yu, Xiaozhong et al. (2014) Melphalan, alone or conjugated to an FSH-? peptide, kills murine testicular cells in vitro and transiently suppresses murine spermatogenesis in vivo. Theriogenology 82:152-9
Chakraborty, Papia; Buaas, F William; Sharma, Manju et al. (2014) LIN28A marks the spermatogonial progenitor population and regulates its cyclic expansion. Stem Cells 32:860-73
Amory, John K; Arnold, Samuel; Lardone, MarĂ­a C et al. (2014) Levels of the retinoic acid synthesizing enzyme aldehyde dehydrogenase-1A2 are lower in testicular tissue from men with infertility. Fertil Steril 101:960-6
Paik, Jisun; Haenisch, Michael; Muller, Charles H et al. (2014) Inhibition of retinoic acid biosynthesis by the bisdichloroacetyldiamine WIN 18,446 markedly suppresses spermatogenesis and alters retinoid metabolism in mice. J Biol Chem 289:15104-17
Roth, Mara Y; Shih, Grace; Ilani, Niloufar et al. (2014) Acceptability of a transdermal gel-based male hormonal contraceptive in a randomized controlled trial. Contraception 90:407-12
Anawalt, Bradley D (2013) Approach to male infertility and induction of spermatogenesis. J Clin Endocrinol Metab 98:3532-42
Roth, M Y; Nya-Ngatchou, J J S; Lin, K et al. (2013) Androgen synthesis in the gonadotropin-suppressed human testes can be markedly suppressed by ketoconazole. J Clin Endocrinol Metab 98:1198-206

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