SAT039 Chronic Glucocorticoid Exposure Induced A S1PR2-Rorc Axis To Enhance Hepatic Gluconeogenesis

Abstract

Abstract Disclosure: R.A. Lee: None. M. Chang: None. A. Tsay: None. Y. Lee: None. D. Li: None. N. Yiv: None. S. Tian: None. J. Wang: None. Glucocorticoids are steroid hormones whose circulating levels are elevated in response to stress to maintain metabolic homeostasis. Glucocorticoids are also used to treat inflammatory and autoimmune diseases due to their potent anti-inflammatory and immunomodulatory activities. However, chronic glucocorticoid treatment causes various metabolic disorders, such as hyperglycemia and insulin resistance. Glucocorticoids convey their functions through an intracellular glucocorticoid receptor (GR) which is a transcriptional regulator. While GR stimulates hepatic gluconeogenic gene transcription, additional mechanisms activated specifically by chronic glucocorticoid exposure can further enhance hyperglycemia. We found that chronic glucocorticoid exposure elevated hepatic production of sphingosine-1-phosphate (S1P) and hepatic knockdown of sphingosine-1-phosphate receptor 2 (S1PR2) attenuated chronic glucocorticoid-induced glucose intolerance and hepatic gluconeogenesis while having no effect on insulin signaling. Hepatic S1PR2 knockdown reduced GR occupancy on glucocorticoid response elements (GREs) of gluconeogenic genes, such as phosphoenolpyruvate carboxykinase (Pck1) and the catalytic subunit of glucose 6 phosphatase (G6pc), thus reducing their expressions. Interestingly, RAR-related orphan receptor C (Rorc) expression was reduced in the liver of glucocorticoid treated hepatic S1PR2 knockdown mice. We found that Rorc was also recruited to the promoter of Pck1 upon glucocorticoid treatment and reducing Rorc activity decreased the GR occupancy at the GRE of Pck1. In contrast, overexpressing Rorc in the liver of hepatic S1PR2 knockdown mice restored glucocorticoid-induced glucose intolerance, GR recruitment to GREs of gluconeogenic genes, and gluconeogenic gene expression. Overall, we propose that chronic glucocorticoid exposure induces a novel S1PR2-Rorc axis to promote the transcription of gluconeogenic genes to enhance hyperglycemia. Presentation: Saturday, June 17, 2023