Glucosamine induces hepatic FGF21 expression by activating the Akt/mTOR/p70S6K axis and driving PGC-1α activity

Glucosamine (GlcN) is a common supplement used to alleviate osteoarthritis, but it may dysregulate glucose tolerance and induce insulin resistance, thereby increasing metabolic burden. The liver is a vital organ that modulates the Akt/mTOR/p70S6K signaling pathway in response to growth and metabolism. Fibroblast growth factor 21 (FGF21) is a hepatokine involved in regulating glucose and lipid metabolism. Additionally, increased circulating FGF21 levels have been linked to the prediction of metabolic disorders and type 2 diabetes. However, the regulatory mechanism controlling FGF21 expression by GlcN remains unclear. In the present study, GlcN stimulation led to several outcomes, including an increase in cell content, secretion, and mRNA and protein levels of FGF21 in hepatocytes. Moreover, inhibition of the Akt/mTOR/p70S6K axis resulted in reduced FGF21 expression in response to GlcN. Importantly, GlcN-mediated expression of FGF21 relies on PGC-1α upregulation. These results suggest that GlcN increases FGF21 expression through the activation between Akt/mTOR/p70S6K pathway and PGC-1α dependent manner.