UCLA

Brown adipocytes are thermogenic cells activated during cold exposure. When activated, they generate heat through uncoupling the mitochondrial electron transport chain. Brown adipose tissue (BAT) activity is associated with a decreased risk of developing type 2 diabetes and other cardiometabolic diseases. Upon activation, pyruvate, and tricarboxylic acid (TCA) cycle intermediates increase, therefore, glucose oxidation may serve an essential role in BAT activation. Glucose is stored in glycogen through glycogen synthase (GYS1), a central enzyme that controls cytosolic glucose levels. Preliminary findings suggest that GYS1 protein expression is upregulated during thermogenesis. However, this upregulation is not due to an increase in transcription levels. Thus, we hypothesized post-translational regulation may be driving the elevated levels of GYS1 in BAT in response to thermogenesis. To test our hypothesis, brown pre-adipocytes were isolated and immortalized from male C57BL/6L mitochondrial pyruvate carrier (MPC1) floxed mice, generating two cell lines: pBABE (control) and HA-TurboID-GYS1. These cell lines were then treated with and without CL-316, 243, a beta-3-adrenergic agonist. As a result, we expected to see an upregulation in GYS1 protein expression in both the pBABE and HA-TurboID-GYS1when treated with CL-316, 243. In the end, we found GYS1 protein expression increased under CL-316, 243, insulin, and insulin in combination with essential amino acids, suggesting GYS1 may also play a role in acute thermogenesis and the mTOR signaling pathway.