Project Details

Description

The human gonadotropin-releasing hormone gene (hGnRH) is synthesized in the
hypothalamus, and to a lesser extent in the placenta, gonads, and the
lactating mammary glands, and plays a key role in the control of
reproduction through its release of pituitary gonadotropins. However, the
molecular mechanisms responsible for hGnRH expression and regulation in man
are largely unknown. Thus, the purpose of the proposed studies will be to
elucidate several important aspects of hGnRH expression and regulation.
First, the molecular mechanisms responsible for cell-specific hGnRH
expression will be defined in vitro using DNA transfection studies of a
GnRH-secreting hypothalamic cell line, (GN, developed in our laboratory),
and a human placental cell line, JEG-3 as well as DNase I footprinting
studies of the hGnRH gene utilizing nuclear extracts from these cell lines.
Second, a direct role for estradiol regulation of the hGnRH gene will be
studied in vitro by transfecting chimeric hGnRH gene constructs, containing
a putative estrogen DNA response element (ERE), into placental and
hypothalamic cell lines. The effect of various concentrations of the
estrogen receptor (ER) in mediating this response will also be evaluated by
co-transfecting an expression vector containing a viral promoter driving
the expression of the human ER cDNA. Third, in animals and presumably man,
the hGNRH neuron migrates from the olfactory placode to the hypothalamus.
A chimeric construct containing the 1.1 kb of the hGnRH promoter driving
the expression of the protein coding region of the simian virus 40 T
antigen was used to neoplastically transform the GNRH neuron in transgenic
mice. Neoplastic transformation of the GnRH neuron has interfered with its
developmental migration from the olfactory placode. The cell line derived
from the neoplastic transformation, GN, will be used to study cell-specific
expression and estradiol regulation in vitro. Further studies to define
cis-acting elements responsible for neuronal and placental-specific
expression in vivo are planned utilizing 5'deletions of the hGnRH promoter
fused to the luciferase reporter gene. Thus, these studies will provide
new insights into the Molecular mechanisms of GNRH expression in the
hypothalamus and placenta, as well as evidence that estrogen directly
regulates GNRH gene expression in the hypothalamus. In addition, these
studies will begin to define cis-acting elements and trans-acting factors
that mediate neuronal and placental-specific expression of the hGnRH gene
in man.
StatusFinished
Effective start/end date7/1/926/30/97

Funding

  • National Institutes of Health
  • National Institutes of Health: $107,100.00
  • National Institutes of Health
  • National Institutes of Health
  • National Institutes of Health: $99,644.00
  • National Institutes of Health
  • National Institutes of Health: $103,478.00

ASJC

  • Medicine(all)

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