The long-term goal of this research is to define specific paracrine mechanisms that regulate spermatogenic cell development. Although FSH and testosterone are required to establish and maintain spermatogenesis, this endocrine regulation is indirect and mediated mainly through Sertoli cells, undoubtedly through multiple paracrine mechanisms. Our studies show that the insulin-like II growth factor/mannose 6-phosphate (IGF-II/M6P) receptor is abundant on the surface of spermatogonia, and that specific binding of Sertoli cell ligands to this receptor elevates germ cell c-fos mRNA and ribosomal RNA levels. This is t he first direct demonstration that insulin-like growth factor II (IGF-II) and mannose 6-phosphate-bearing glycoproteins (M6P-glycoproteins) secreted by Sertoli cells modulate the expression of a specific germ cell gene. We hypothesize that these ligands secreted by Sertoli cells activate receptor-mediated signal transduction pathways in spermatogonia, modulating gene expression and DNA synthesis required for differentiation.
The specific aims of this proposal are to: 1) Identify specific ligands secreted by Sertoli cells that stimulate gene expression when they bind to IGF-II/M6P receptors on the surface of spermatogonia. These studies will fractionate Sertoli M6P-glycoproteins and identify specific proteins in the active fractions by immunoblotting and microsequencing. In addition, the baseline level of IGF-II secreted by Sertoli cells in culture will be quantitated by radioimmunoassay. 2) Determine signal transduction pathways in spermatogonia that are activated by ligand binding to cell surface IGF-II/M6P receptors. These studies will determine if Sertoli cell ligands for the IGF-II/M6P receptor activate phospholipase C and stimulate an influx of calcium, as shown for this receptor in other cell types, and determine if proteins are subsequently phosphorylated via protein kinase C activation. 3) Determine the effects of IGF-II/M6P receptor activation on gene expression and DNA synthesis and the expression of other genes in spermatogonia. These studies will determine if Sertoli cell ligands for this receptor modulate DNA synthesis in spermatogonia or the expression of other genes identified by mRNA differential display. These studies will define the pathway and effects of a specific receptor- mediated mechanism for paracrine regulation of spermatogonia by Sertoli cells, providing fundamental knowledge about the regulation of spermatogenesis applicable to the clinical management of infertility and the development of new contraceptive strategies.

Agency
National Institute of Health (NIH)
Institute
Eunice Kennedy Shriver National Institute of Child Health & Human Development (NICHD)
Type
Research Project (R01)
Project #
5R01HD026485-06
Application #
2673607
Study Section
Reproductive Biology Study Section (REB)
Project Start
1991-05-01
Project End
2000-07-31
Budget Start
1998-08-01
Budget End
2000-07-31
Support Year
6
Fiscal Year
1998
Total Cost
Indirect Cost
Name
University of North Carolina Chapel Hill
Department
Pediatrics
Type
Schools of Medicine
DUNS #
078861598
City
Chapel Hill
State
NC
Country
United States
Zip Code
27599
Tsuruta, J K; Eddy, E M; O'Brien, D A (2000) Insulin-like growth factor-II/cation-independent mannose 6-phosphate receptor mediates paracrine interactions during spermatogonial development. Biol Reprod 63:1006-13
Franklin, D S; Godfrey, V L; O'Brien, D A et al. (2000) Functional collaboration between different cyclin-dependent kinase inhibitors suppresses tumor growth with distinct tissue specificity. Mol Cell Biol 20:6147-58
Pace, A J; Lee, E; Athirakul, K et al. (2000) Failure of spermatogenesis in mouse lines deficient in the Na(+)-K(+)-2Cl(-) cotransporter. J Clin Invest 105:441-50
McCarrey, J R; O'Brien, D A; Skinner, M K (1999) Construction and preliminary characterization of a series of mouse and rat testis cDNA libraries. J Androl 20:635-9
Eddy, E M; O'Brien, D A (1998) Gene expression during mammalian meiosis. Curr Top Dev Biol 37:141-200
Joseph, D R; O'Brien, D A; Sullivan, P M et al. (1997) Overexpression of androgen-binding protein/sex hormone-binding globulin in male transgenic mice: tissue distribution and phenotypic disorders. Biol Reprod 56:21-32
O'Brien, D A; Welch, J E; Goulding, E H et al. (1996) Boar proacrosin expressed in spermatids of transgenic mice does not reach the acrosome and disrupts spermatogenesis. Mol Reprod Dev 43:236-47
Raburn, D J; Hamil, K G; Tsuruta, J K et al. (1995) Stage-specific expression of B cell translocation gene 1 in rat testis. Endocrinology 136:5769-77
Fulcher, K D; Welch, J E; Klapper, D G et al. (1995) Identification of a unique mu-class glutathione S-transferase in mouse spermatogenic cells. Mol Reprod Dev 42:415-24
Welch, J E; Brown, P R; O'Brien, D A et al. (1995) Genomic organization of a mouse glyceraldehyde 3-phosphate dehydrogenase gene (Gapd-s) expressed in post-meiotic spermatogenic cells. Dev Genet 16:179-89

Showing the most recent 10 out of 22 publications