Impact of CREBRF and its obesity-risk variant on hypothalamic glucocorticoid and neuroendocrine output using molecular, cellular, and physiological approaches.

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PROJECT SUMMARY Strong evidence links central hypothalamic neuroendocrine output to complex biological processes and behaviors that control energy and metabolic homeostasis. Dr. Kershaw’s collaborative research group recently identified a novel obesity-risk variant in a putative transcriptional regulator, CREBRF, that is highly expressed in the hypothalamus. Although virtually nothing in know about CREBRF, it has been linked to glucocorticoid signaling, raising that possibility that its energy and metabolic effects in humans is mediated, in part, by influencing hypothalamic glucocorticoid and/or neuroendocrine output. The overarching goal of this proposal is to determine how CREBRF and its obesity-risk variant contribute to the central regulation of energy homeostasis and the stress response. The overall objective, which is the next step in the pursuit of this goal, is to characterize the role of this gene/variant in central hypothalamic glucocorticoid and neuroendocrine output. The central hypothesis is that CREBRF is expressed and regulated in key hypothalamic neurons and that the loss of CREBRF or expression of its missense CrebrfR457Q will differentially impact the metabolic control transcriptome and the chromatin landscape within the hypothalamus, thereby influences behavioral and metabolic outcomes. This hypothesis is based on the following: 1) endogenous CREBRF is highly expressed in the central nervous systems including the hypothalamus where it co-localizes with the glucocorticoid receptor (GR); 2) ectopic expression of CREBRF in cells influences subnuclear GR targeting and stability; 3) global CrebrfKO mice have dysregulated glucocorticoid signaling and abnormal postpartum maternal behavior; and 4) global CrebrfKO mice have reduced body weight. The above hypothesis will be tested using molecular, cellular, and physiological approaches with the following specific aims: 1) To characterize the impact of CREBRF and its obesity risk variant (CREBRFR458Q) on hypothalamic output in vivo using murine models; and 2) to determine the function of CREBRF and its obesity risk variant (CREBRFR458Q) on chromatin accessibility and cell-specific transcriptome using murine models. This research is innovative because 1) it examines obesity in a murine model without the complications of diabetes, 2) examine the mechanisms for the phenotype observed in Samoans and 3) will lay the foundation for numerous avenues to pursue the potential therapeutic benefits of targeting central CREBRF. This contribution will be significant because it will identify CREBRF expression, regulation, and function in specific hypothalamic neuropeptide-containing neurons and HPA-axis output during defined stress conditions and determine the impact of CREBRF and its obesity-linked variant on the genome-wide chromatin landscape and single cell transcriptomes within the hypothalamus. Such findings are expected to have a broad translational impact by improving strategies for prevention and/or treatment of obesity and associated metabolic diseases. Finally, at the completion of this proposal, Dr. Frahm will be well poised to lead her own independent research program in the field of neuroendocrinology.