Project 3: MANIPULATION OF GENE EXPRESSION WITH SMALL MOLECULES

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The goal of this project is to create cell permeable synthetic molecules capable of activating the expression of specific genes. The "synthetic transcription factor mimics" would be capable of localizing to a specific promoter region and recruiting the transcriptional machinery to a nearby gene, thus mimicking a basic function of native transactivator proteins. These molecules would be tools of outstanding utility in biomedical research and could potentially be elaborated into a new class of therapeutic agents. It is envisioned that a synthetic activator could be created by fusing together a DMA-binding molecule, specifically a hairpin polyamide with the appropriate DMA recognition characteristics, with a molecule capable of binding the RNA polymerase II holoenzyme, thus recruiting it to the target promoter. There is considerable evidence from our laboratory and others that this is a valid approach, but while synthetic activators capable of functioning in nuclear extracts have been reported, the goal of molecules that function in living cells remains elusive. We have recently made an exciting breakthrough with the discovery of a cell permeable peptoid that functions as an activation domain equivalent in living cells. This is the first observation of such activity. We plan to link this peptoid and improved derivatives to hairpin polyamides with appropriate sequence recognition properties to create cell permeable synthetic activators. These compounds will be employed to manipulate metabolism in cell lines and human islets. In particular, we will attempt to activate the Nkx6.1 gene and the cytosolic, NADPH-dependent isocitrate dehydrogenase gene in islets and determine the effect of this stimulation of the metabolism of the cell. These studies will be in collaboration with the Newgard laboratory. Following the lead of recent results in the Newgard laboratory, we also plan to use genome-wide chromatin immunoprecipitation assays to help to identify direct Nkx6.1 target genes and will also then design synthetic molecules to turn on these genes as well. Throughout the course of this project, consistent efforts will be made to develop ever more potent synthetic activators. To do so, we will take advantage of a novel cell-based screen that we have developed which allows synthetic combinatorial libraries to be screened for activation domain mimics directly. Furthermore, we will also set up cellular assays to optimize polyamides for binding to the desired promoters.