The gonadotropins follicle stimulating hormone (FSH) and luteinizing hormone (LH) are heterodimeric pituitary glycoprotein hormones that directly regulate gametogenesis and gonadal steroid hormone biosynthesis in the testis and ovary. Transcription of the gonadotropin subunit genes, and biosynthesis, assembly, and secretion of the biologically active hormones are precisely controlled by the hypothalamic neuropeptide gonadotropin releasing hormone (GnRH), and gonadal steroid hormones and peptides. Altered regulation of gonadotropin production is a major cause of infertility. Conversely, the selective control of gonadotropin production has implications for both the treatment of infertility disorders and the development of effective novel contraceptives. The major goal of this project is to understand at the molecular level the DNA components and transcription factors that are responsible for the gonadotroph-specific expression and hormonal regulation of the FSHbeta subunit gene. DNA elements will be coarsely mapped initially by a deletional and mutational analysis of the human and mouse FSHbeta genes expressed in the pituitary glands of transgenic mice. Gonadotroph-specific expression will be confirmed by histological techniques and the hormonal regulation of the transgenes will be studied by analysis of FSHbeta mRNA levels with species' specific probes and by radioimmunoassay of the expressed FSH. Standard reproductive endocrinological experiments will be performed using transgenic mice and hpg hypogonadal mice genetically crossed with the hpg mice. A comparison of functionally important sequences conserved between human and mouse will direct future fine scale mapping of the core DNA regulatory elements. The mechanism of androgen inhibition of the human FSHbeta subunit gene at the pituitary level will be studied by a combination of in vivo nuclear run on studies and in vitro DNA-protein binding reactions using purified androgen receptor and competition experiments with known positively regulated androgen response elements. Inhibin and activin regulation of hFSHbeta will be studied using perfused columns of primary pituitary cell cultures derived from transgenic mice. Finally, we will attempt to derive a continuous, well differentiated gonadotroph cell line from pituitary tumors induced in transgenic mice with a temperature sensitive simian virus 40 large T antigen oncogene. Alternatively we will attempt to immortalize gonadotrophs using a powerful papilloma virus oncogene carried in a retroviral vector or by the expression of other oncogenes in the gonadotrophs of transgenic mice. A beta-subunit expressing gonadotroph cell line would be invaluable for further functional analysis of regulatory elements in the gonadotropin subunit genes, to characterize gonadotroph-specific transcription factors, and to explore the physiological mechanisms underlying the coordinated regulation of gonadotropin gene expression and the cell biology of gonadotropin biosynthesis and secretion.

Agency
National Institute of Health (NIH)
Institute
Eunice Kennedy Shriver National Institute of Child Health & Human Development (NICHD)
Type
Research Project (R01)
Project #
2R01HD028367-04
Application #
2201029
Study Section
Biochemical Endocrinology Study Section (BCE)
Project Start
1991-07-16
Project End
1998-04-30
Budget Start
1994-07-15
Budget End
1995-04-30
Support Year
4
Fiscal Year
1994
Total Cost
Indirect Cost
Name
Oregon Health and Science University
Department
Type
Organized Research Units
DUNS #
009584210
City
Portland
State
OR
Country
United States
Zip Code
97239
Kumar, T Rajendra; Schuff, Kathryn G; Nusser, Kevin D et al. (2006) Gonadotroph-specific expression of the human follicle stimulating hormone beta gene in transgenic mice. Mol Cell Endocrinol 247:103-15
Grewal, A; Bradshaw, S L; Schuller, A G et al. (1999) Expression of IGF system genes during T-antigen driven pituitary tumorigenesis. Horm Metab Res 31:155-60
Kumar, T R; Graham, K E; Asa, S L et al. (1998) Simian virus 40 T antigen-induced gonadotroph adenomas: a model of human null cell adenomas. Endocrinology 139:3342-51
Kumar, T R; Low, M J; Matzuk, M M (1998) Genetic rescue of follicle-stimulating hormone beta-deficient mice. Endocrinology 139:3289-95
Kumar, T R; Low, M J (1995) Hormonal regulation of human follicle-stimulating hormone-beta subunit gene expression: GnRH stimulation and GnRH-independent androgen inhibition. Neuroendocrinology 61:628-37
Japon, M A; Rubinstein, M; Low, M J (1994) In situ hybridization analysis of anterior pituitary hormone gene expression during fetal mouse development. J Histochem Cytochem 42:1117-25
Kumar, T R; Low, M J (1993) Gonadal steroid hormone regulation of human and mouse follicle stimulating hormone beta-subunit gene expression in vivo. Mol Endocrinol 7:898-906