Research description:
A major effort underway in the Thummel lab is to
define roles for nuclear hormone receptors in development, growth, and
metabolism, using the fruit fly Drosophila as a model system. The Drosophila
genome encodes 18 canonical nuclear receptors, with representatives of all
the major human classes, providing the smallest complete set of receptors
known in any genetic model system (King-Jones and Thummel, 2005). We have
determined the temporal profiles of expression for all detectable nuclear
receptor genes during the major steroid-triggered transitions in the life
cycle (Sullivan and Thummel, 2003). We are continuing our reverse genetic
characterization of this gene family, focusing on nuclear receptors that
have close mammalian homologs, in an effort to understand their functions
during development. We analyze the phenotypes associated with both
loss-of-function and gain-of-function mutations as a means of determining
gene function. By raising antibodies
against the encoded proteins we can determine their spatial patterns of
expression as well as identify potential direct transcriptional targets in
chromatin. We use microarrays to determine the effects of loss-of-function
and gain-of-function mutations on gene expression, and class if these
targets into functional groups by bioinformatics. Most recently, we have
used metabolic profiling by GC/MS to determine effects of nuclear receptor
mutations on specific metabolic pathways, linking these functions to key
target genes identified in our microarray studies as well as specific
developmental defects. Current work is focused on dERR, DHR38, DHR78, DHR96,
and dHNF4. We also use transgenic animals that carry the GAL4 DNA binding
domain fused to the ligand binding domains (LBDs) of nuclear receptors as a
means of determining when and where hormones or critical co-factors are
present in the animal. These studies have identified novel agonists for some
nuclear receptors, preferred sites of LBD activation in tissues associated with lipid metabolism, and
dynamic changes in activation indicative of novel hormones or cofactors that
regulate receptor function. Taken together, these studies should clarify the
roles of nuclear receptors in development, growth and metabolism, and
provide critical new insights into the regulation and function of their
human orthologs.
Does this research involve human subjects or animals? no
If yes, what is the protocol number?
10/20/06
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