Chorionic gonadotropin (CG) is a placental hormone that stimulates gonadal steroidogenesis and is important for maintenance of the corpus luteum of pregnancy. After implantation of the fertilized ovum, CG levels increase through the first trimester, after which they gradually decline. CG is also produced ectopically by a variety of neoplasms. The long-term goal of this proposal is to understand the cellular mechanisms that regulate CG biosynthesis at the level of gene expression. CG is a heterodimer consisting of nonidentical alpha and beta subunits that are encoded by separate genes. The alpha-subunit is encoded by a single copy gene, whereas the beta-subunit genes comprise a multigenic family that includes six CG beta genes and a single copy of the structurally-related LH beta gene. This project will address: 1) Determination of the DNA regulatory sequences of the alpha, CG beta, and LH beta genes using deletion mutagenesis and analyses of gene expression in transfected cells. These studies will focus on the cis-acting DNA sequences that confer cell-specific expression and hormone-responsiveness as well as the regulatory elements that result in coordinant expression of alpha and beta subunit genes. In addition, the regulatory DNA sequences of the recently diverged LH beta/CG beta gene pair will be exchanged onto the heterologous beta-subunit promoter to examine the mechanisms that regulate placental-specific expression of the CG beta gene and pituitary-specific expression of the LH beta gene. Similarly, the gene regulatory elements involved in ectopic gene expression will be sought by defining the DNA sequences that confer the capacity to express the CG alpha and beta genes in ectopic hormone-producing cell lines. 2) The trans-acting cellular factors that interact specifically with the alpha and beta gene regulatory elements will be examined using gel-retardation assays and DNA footprinting studies. These assays will also provide a means to monitor the purification of these DNA binding proteins during a series of isolation steps. Competition assays in transfected cells will be used to examine the cellular factors that interact with DNA regulatory elements. These studies will include experiments to assess interactions of alpha and beta regulatory sequences with shared regulatory factors that may mediate coordinant gene expression. 3) In parallel with the studies of transfected fusion genes, expression of the endogenous gonadotropin alpha and beta subunit genes will be examined in pituitary and placental cell lines as well as in pituitary tumors. These studies will focus on coordinant expression of the alpha and beta subunits, and characterization of defects in biosynthesis and secretion that occur in pituitary tumors.

Agency
National Institute of Health (NIH)
Institute
Eunice Kennedy Shriver National Institute of Child Health & Human Development (NICHD)
Type
Research Project (R01)
Project #
5R01HD023519-04
Application #
3323743
Study Section
Endocrinology Study Section (END)
Project Start
1988-08-01
Project End
1993-04-30
Budget Start
1991-05-01
Budget End
1992-04-30
Support Year
4
Fiscal Year
1991
Total Cost
Indirect Cost
Name
Massachusetts General Hospital
Department
Type
DUNS #
City
Boston
State
MA
Country
United States
Zip Code
02199
Johnson, W; Jameson, J L (2000) Role of Ets2 in cyclic AMP regulation of the human chorionic gonadotropin beta promoter. Mol Cell Endocrinol 165:17-24
Johnson, W; Jameson, J L (1999) AP-2 (activating protein 2) and Sp1 (selective promoter factor 1) regulatory elements play distinct roles in the control of basal activity and cyclic adenosine 3',5'-monophosphate responsiveness of the human chorionic gonadotropin-beta promoter. Mol Endocrinol 13:1963-75
Johnson, W; Albanese, C; Handwerger, S et al. (1997) Regulation of the human chorionic gonadotropin alpha- and beta-subunit promoters by AP-2. J Biol Chem 272:15405-12
Pestell, R G; Albanese, C; Lee, R J et al. (1996) A potential role for cell cycle control proteins in regulation of the cyclic adenosine 5'-monophosphate-responsive glycoprotein hormone alpha subunit gene. Cell Growth Differ 7:1337-44
Pestell, R G; Albanese, C; Watanabe, G et al. (1996) Stimulation of the P-450 side chain cleavage enzyme (CYP11A1) promoter through ras- and Ets-2-signaling pathways. Mol Endocrinol 10:1084-94
Albanese, C; Colin, I M; Crowley, W F et al. (1996) The gonadotropin genes: evolution of distinct mechanisms for hormonal control. Recent Prog Horm Res 51:23-58;discussion 59-61
Pestell, R G; Albanese, C; Watanabe, G et al. (1995) Epidermal growth factor and c-Jun act via a common DNA regulatory element to stimulate transcription of the ovine P-450 cholesterol side chain cleavage (CYP11A1) promoter. J Biol Chem 270:18301-8
Pestell, R G; Hollenberg, A N; Albanese, C et al. (1994) c-Jun represses transcription of the human chorionic gonadotropin alpha and beta genes through distinct types of CREs. J Biol Chem 269:31090-6
Hollenberg, A N; Pestell, R G; Albanese, C et al. (1994) Multiple promoter elements in the human chorionic gonadotropin beta subunit genes distinguish their expression from the luteinizing hormone beta gene. Mol Cell Endocrinol 106:111-9
Jameson, J L; Hollenberg, A N (1993) Regulation of chorionic gonadotropin gene expression. Endocr Rev 14:203-21

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