The pulsatile release of GnRH in a small subset of hypothalamic neurons is a driving force for reproductive function in mammals. This secretion appears to be dependent on oscillations in intracellular free calcium that are derived from intermittent calcium influx through voltage- operated membrane calcium channels. Recent evidence also suggests changes in GnRH expression occur in an episodic manner. In order to gain a mechanistic understanding of these dynamic fluctuations, new cellular and molecular strategies corresponding more closely to """"""""real-time"""""""" cellular events are required. The PI and his colleagues have developed strategies to make multiple measurements of GnRH gene expression (via luciferase reporter gene activity imaging), GnRH release (by changes in membrane dye uptake and recycling), calcium oscillations (Fura-2 imaging), and combinations of these in living GT-1 cells. Using these tools, the specific aims are to: 1) elucidate the molecular dynamics of GnRH gene expression in living GT-1 cells are representatives of immortalized GnRH neurons; 2) explore the cellular basis for secretory pulsatility in individual GnRH neurons; and 3) establish possible relationships among GnRH secretion, gene expression, and calcium dynamics in the same, living cells.

Agency
National Institute of Health (NIH)
Institute
Eunice Kennedy Shriver National Institute of Child Health & Human Development (NICHD)
Type
Research Project (R01)
Project #
1R01HD037657-01
Application #
2851814
Study Section
Reproductive Biology Study Section (REB)
Program Officer
De Paolo, Louis V
Project Start
1999-01-05
Project End
2003-03-31
Budget Start
1999-01-05
Budget End
2000-03-31
Support Year
1
Fiscal Year
1999
Total Cost
Indirect Cost
Name
Medical University of South Carolina
Department
Anatomy/Cell Biology
Type
Schools of Medicine
DUNS #
183710748
City
Charleston
State
SC
Country
United States
Zip Code
29425
Bose, Sudeep; Leclerc, Gilles M; Vasquez-Martinez, Rafael et al. (2010) Administration of connexin43 siRNA abolishes secretory pulse synchronization in GnRH clonal cell populations. Mol Cell Endocrinol 314:75-83
Leclerc, Gilles M; Bose, Sudeep K; Boockfor, Fredric R (2008) Specific GATA-binding elements in the GnRH promoter are required for gene expression pulse activity: role of GATA-4 and GATA-5 in this intermittent process. Neuroendocrinology 88:1-16
Leclerc, Gilles M; Boockfor, Fredric R (2007) Calcium influx and DREAM protein are required for GnRH gene expression pulse activity. Mol Cell Endocrinol 267:70-9
Leclerc, Gilles M; Boockfor, Fredric R (2005) Identification of a novel OCT1 binding site that is necessary for the elaboration of pulses of rat GnRH promoter activity. Mol Cell Endocrinol 245:86-92
Vazquez-Martinez, Rafael; Leclerc, Gilles M; Wierman, Margaret E et al. (2002) Episodic activation of the rat GnRH promoter: role of the homeoprotein oct-1. Mol Endocrinol 16:2093-100
Vazquez-Martinez, R; Shorte, S L; Boockfor, F R et al. (2001) Synchronized exocytotic bursts from gonadotropin-releasing hormone-expressing cells: dual control by intrinsic cellular pulsatility and gap junctional communication. Endocrinology 142:2095-101
Vazquez-Martinez, R; Shorte, S L; Faught, W J et al. (2001) Pulsatile exocytosis is functionally associated with GnRH gene expression in immortalized GnRH-expressing cells. Endocrinology 142:5364-70
Nunez, L; Villalobos, C; Boockfor, F R et al. (2000) The relationship between pulsatile secretion and calcium dynamics in single, living gonadotropin-releasing hormone neurons. Endocrinology 141:2012-7