Pharmacological and genetic manipulation of adipose cell differentiation and metabolism

Sammanfattning: Adipose tissue dysfunction has a pivotal role in the development of obesity and related metabolic complications, such as insulin resistance, cardiovascular disease, and diabetes. The overall aim was to study the consequences of adipose exposure to pharmacological agents, as well as dysregulations in the expression of genes, potentially involved in adipose tissue dysfunction and related metabolic impairments. In Paper I, CRISPR/Cas9 gene knockout method in human primary preadipocytes was established and used to study the role of FKBP51 (FK506 Binding Protein 5) in mediating glucocorticoid action in adipocytes. FKBP51 ablation did not affect preadipocyte differentiation; however, it inhibited dexamethasone's negative effect on glucose uptake. In Paper II, CDKN2C (Cyclin-Dependent Kinase Inhibitor 2C) was shown to be down-regulated in subjects with T2D and obesity and was negatively associated with markers of insulin resistance and central adiposity. However, CDKN2C deficiency did not affect preadipocyte differentiation or adipocyte glucose uptake.In Paper III, we demonstrated that supra-therapeutic concentration of aripiprazole inhibited preadipocyte differentiation, while therapeutic concentrations increased the expression of lipid oxidation markers and leptin. Aripiprazole dose-dependently reduced adipocyte glucose uptake. Except for up-regulating leptin gene expression, olanzapine had no direct effects on adipocytes. In Paper IV, we observed that dopamine receptor (DR) D2 gene and/or protein expression was increased in subjects with prediabetes, T2D and obesity, and protein expression was positively associated with markers of hyperglycemia, independently of obesity status. DRD1 gene expression was increased in subjects with obesity, with a tendency to be increased in T2D, and positively correlated with markers of obesity and insulin resistance. However, the DRD1 protein levels did not follow the gene expression data. Dopamine at physiological concentrations did not affect adipocyte glucose uptake or lipolysis ex vivo. In conclusion, a simple and highly efficient CRISPR/Cas9 method was developed. FKBP51 and CDKN2C are dispensable for adipogenesis, but might be important for adipocyte metabolism and function. Aripiprazole, but not olanzapine, might have direct implications for adipocyte development and energy metabolism. Furthermore, the expression of DRD2 in SAT seems to be increased with hyperglycemia, which could have implications for dopamine signaling in subjects with prediabetes and diabetes.