Antimicrobial protein REG3A regulates glucose homeostasis and insulin resistance in obese diabetic mice

Antimicrobial protein REG3A improved insulin sensitivity by combating oxidative stress and activating AMPK in skeletal muscle in HFD-induced obese mice overexpressing human REG3A in the liver. Innate immune mediators of pathogen clearance, including the secreted C-type lectins REG3 of the antimicrobial peptide (AMP) family, are known to be involved in the regulation of tissue repair and homeostasis. Their role in metabolic homeostasis remains unknown. Here we show that an increase in human REG3A improves glucose and lipid homeostasis in nutritional and genetic mouse models of obesity and type 2 diabetes. Mice overexpressing REG3A in the liver show improved glucose homeostasis, which is reflected in better insulin sensitivity in normal weight and obese states. Delivery of recombinant REG3A protein to leptin-deficient ob/ob mice or wild-type mice on a high-fat diet also improves glucose homeostasis. This is accompanied by reduced oxidative protein damage, increased AMPK phosphorylation and insulin-stimulated glucose uptake in skeletal muscle tissue. Oxidative damage in differentiated C2C12 myotubes is greatly attenuated by REG3A, as is the increase in gp130-mediated AMPK activation. In contrast, Akt-mediated insulin action, which is impaired by oxidative stress, is not restored by REG3A. These data highlight the importance of REG3A in controlling oxidative protein damage involved in energy and metabolic pathways during obesity and diabetes, and provide additional insight into the dual function of host-immune defense and metabolic regulation for AMP.

Automated summary

Antimicrobial protein REG3A improves glucose and lipid homeostasis in mouse models of obesity and type 2 diabetes by combating oxidative stress, increasing AMPK phosphorylation, and enhancing insulin-stimulated glucose uptake in skeletal muscle tissue. This study sheds light on the dual function of REG3A in host-immune defense and metabolic regulation and highlights its importance in controlling oxidative protein damage during obesity and diabetes.