Project Summary A major goal of this laboratory is to understand the molecular mechanisms by which nuclear receptors (NRs) regulate metabolism. Peroxisome proliferator-activated receptor γ (PPARγ) is the master regulator of adipocyte biology and the target of thiazolidinedione (TZD) drugs that uniquely reverse insulin resistance. Clinical use of TZDs has been hindered by side effects, making it critical to better understand the functions of PPARγ. There are two PPARγ isoforms, and a glaring unanswered question is whether they subserve different functions which could be harnessed to more specifically target insulin resistance. Specific Aim 1 is to elucidate the unique cistromes, interactomes, and physiological functions of PPARγ isoforms γ1 and γ2. Little is known about the two major isoforms of PPARγ. We hypothesize that PPARγ1 and γ2 have isoform-specific functions that differentially contribute to both therapeutic and adverse effects of PPARγ ligands. To test this, we generated novel mouse models of isoform-specific deletion, as well as mice with epitope tags knocked into the endogenous isoforms. Preliminary data reveal isoform-specific metabolic phenotypes, as well as differential genomic binding and transcriptomic regulation. The underlying mechanisms will be evaluated by determining isoform-specific interactomes in the basal state and upon TZD treatment. Molecular factors that mediate isoform-specific effects will be manipulated to specifically target the metabolic functions of PPARγ1 or γ2. Specific Aim 2 is to determine individual-specific functions of glucocorticoids in humans. The glucocorticoid receptor (GR) is another NR that is a major drug target with untoward side effects; glucocorticoids (GC) are widely prescribed for inflammatory conditions, but cause obesity, diabetes, and lipid disorders. There is presently no way to predict which patients will suffer from adverse effects of GCs, nor which will most benefit from therapy. We hypothesize that SNPs function in adipocytes to control GR binding and GC effects on metabolism and inflammation in a predictable, patient-specific manner. Preliminary data demonstrate individual-specific GR binding and GC effects on gene expression and metabolism in multiple patient stem cell-derived adipocytes and hepatocytes, which will be related to single nucleotide polymorphisms (SNPs) controlling the binding of GR. The mechanisms underlying the function of these SNPs will be determined, as will their effects on metabolic functions of the cells as well as predicting adverse metabolic effects of GC in patient populations. We also hypothesize that SNPs will control individual differences in anti-inflammatory potency due to individual differences in GR binding and function that will be tested in stem cell-derived macrophages from multiple patients. Together, our innovative genome-wide and systems approaches will provide fundamental insights into molecular mechanisms underlying tissue- and individual-specif...