P-319 - Exploring the role of the bile acid receptor TGR5 in bile acid mediated obesity control: New insights from a CRISPR/Cas9 adipocyte model.

Bile acids have been known to be potent anti-obesity agents both in vitro and in vivo. While the mechanism in vivo appears to hinge on thermogenic dissipation of excess nutrients, the fact that they are also effective in vitro and in animals with low non-shivering thermogenic capacity points to the fact that the mechanisms in play are yet to be fully demonstrated. 3T3-L1 adipocytes were infected with a CRISPR/Cas9-carrying lentivirus, which specifically targeted the bile acid receptor TGR5, and several metabolic assays were conducted. The absence of TGR5 was insufficient to eliminate CDCA's effects. In fact, mitochondrial respiration measured with a Seahorse flux analyzer and metabolic screening by NMR clearly demonstrate that CDCA can act through other means. Gene expression and protein content all point to elevated mitochondrial activity, increased oxidative capacity of both glucose and triglycerides, an effect already known but not totally removed by the absence of TGR5. Our data supports our previous findings that thermogenic dissipation is far from the only way by which bile acids reduce obesity. Further studies will confirm if the other known bile acid receptor, FXR, is also involved and/ or if other mechanisms of energy waste are also in play. [ABSTRACT FROM AUTHOR]