• Roberts, James (PI)

Project: Research project

Project Details


The basic objective is to elucidate the molecular mechanisms involved in
the regulation of expression of the proopiomelanocortin (POMC) gene in
pituitary and hypothalamic tissues. Using a series of rat POMC-specific
cDNAs and gene clones, we propose to further characterize the
transcriptional regulation of the POMC gene by steroids, peptides, and
catacholamines, both singlely and in combination. Some studies will be
done in the intact animal; however, certain studies will be done in primary
cultures of pituitary cells and in AtT20 tumor cells to preclude indirect
effects on POMC gene expression. The exact sites in the POMC gene involved
with regulation by specific hormones of gene expression will be mapped by
deletion analysis and site directed mutagenesis. We have already
constructed a rat POMC promoter/rat Prolactin coding region construct to
aid in these studies. Using protein/DNA binding studies using the regions
identified in the previous studies and a reinitiating nuclear transcription
assay, we will begin to identify and characterize the transacting factors
which mediate the peptide hormone, neurotransmitter, and steroid mediated
modulation of POMC gene expression. In related studies, we will
characterize the induction of the glucocorticoid receptor encoding gene
after culturing of the intermediate lobe cells. In addition to
understanding how expression of the glucocorticoid receptor gene is
suppressed in the intact animal, these studies will allow us to develop a
relatively homogeneous primary culture system in which we can study the
glucocorticoid/CRF regulatory interactions. We will further characterize
the regulation of the POMC gene system in the periarcuate region of the
hypothalamus using several reproductive paradigms. Studies will be
performed both by solution hybridization assays as well as in situ
hybridization assays, coupled with several anatomical techniques to
functionally subdivide the POMC neurons. We will further develop the use
of POMC gene intervening sequence specific DNA probes in solution and in
situ hybridization as an indirect method for analyzing transcriptional
rates in small amounts of tissues and individual cells, respectively.
These studies should yield a great deal of understanding of the complex
interaction of various types of hormonal substances in the regulation of a
specific gene in a complex but normal physiological situation.
Effective start/end date8/1/806/30/96


  • National Institutes of Health


  • Medicine(all)


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