Novel targets to regulate NF-kB & SREBP activity: an approach to combat diabetes

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DESCRIPTION (provided by applicant): Diabetes has become an increasingly serious epidemic in recent years, with CDC estimates of 24 million people directly affected in the United States alone. There are two interconnected pathways that are critical in the onset of diabetes. They are the nutritionally-derived metabolic pathway, and the pro-inflammatory pathway. Aberrant activation of both the above pathways is commonly found to be associated with the pathological progression of diabetes. We have identified two novel transcription activator-Mediator interactions that control and regulate the metabolic and inflammatory pathway. The two transcription activators, NF-:B (Nuclear Factor- :B) and SREBP (Sterol Regulatory Element-Binding Protein), play significant roles in the onset and progression of diabetes. Both these factors have been shown to functionally interact with a co-activator known as the Activator Recruited Co-factor(ARC)/Mediator Complex. NF-:B and SREBP are critical in regulating the expression of a number of genes involved in the onset of diabetes. We propose to target the activator-Mediator interaction of these two transcription factors (SREBP and NF-:B) with small molecular effectors, thus inhibiting gene activation. The activator-Mediator interactions of SREBP and NF-:B represent novel targets because their inhibition would affect the most downstream element in their activation pathways. We will determine the structure of the minimal elements that constitute the interaction (i.e. the complex of KIX domain in the Mediator with the transactivation domain (TAD) of the activator) by solution state NMR. We will identify small molecule inhibitors for each of the activator-Mediator interactions by high-throughput screening and validate them in an in vitro transcription assay. We will subsequently study the effect of these inhibitors on gene transcription and adipocyte differentiation, in vivo (cell culture), in 3T3-L1 pre-adipocyte cells. This will form the basis for future studies wherein the inhibitors identified and characterized here, will be tested in C.elegans and diabetic murine models. In addition, we seek to elucidate a novel mechanism of regulation of SREBP target genes orchestrated by let-7 micro-RNA. Micro-RNAs are known to modulate mRNA levels of a set of genes, thus synergistically regulating an entire pathway. We hypothesize let-7 modulates levels of PGC-1 co-activators, which in turn regulates SREBP target genes, and is expected to have profound implications in lipogenesis and mitochondrial biogenesis. PUBLIC HEALTH RELEVANCE: Diabetes has become an increasingly serious epidemic in recent years. The nutritionally-derived metabolic pathway and the pro-inflammatory pathways are critical in the onset of diabetes and we have identified two novel transcription activator-Mediator interactions that control and regulate these pathway. We intend to target gene activation in these pathways by identifying small molecule inhibitors for the activator-Mediator interactions and understand endogenous gene regulation by micro-RNAs in these pathways.