Deoxycholic acid derived from the gut microbiota involved in the regulation of adaptive thermogenesis in response to dietary protein restriction in plateau pika.

BACKGROUND: Most winter-active mammals experience protein restriction. Gut microbiota is a key regulator of host energy homeostasis during nutrient deficiency, yet cross talk between microbiota and factors (e.g., hormones, signaling molecules) that regulate host energy metabolism in a low-protein (LP) context has not been studied sufficiently. RESULT: The LP diet triggered the hepatic FGF21 adaptive metabolic pathway, which increased thermogenesis and reduced body weight, and this adaptive response was dependent on the composition and function of gut microbiota. Specifically, the LP diet induced a reshaping of the gut microbiota, altering its metabolic profile to increase deoxycholic acid levels and thereby increasing UCP1-induced thermogenesis of brown adipose tissue in an FGF21-dependent manner. Fecal transplantation with LP-associated microbiota increased thermogenesis through activation of GCN2-eIF2α-FGF21 signaling. Supplementation of the LP diet with yak fecal bacteria in plateau pika reduced UCP1-associated thermogenesis by altering the gut microbiome, decreasing deoxycholic acid production, suppressing activation of GCN2-eIF2α-FGF21 signaling, and alleviating LP-induced weight loss. CONCLUSIONS: Our study reveals an association between the gut microbiota and LP diet-associated regulation of FGF21 signaling and thermogenesis and further demonstrates that this relationship is influenced by interspecies microbial transfer, indicating a critical mechanism whereby horizontal microbial exchange between sympatric species enhances host energy homeostasis. These findings provide novel insights into our understanding of the adaptations of mammals to high-elevation environments. Video Abstract.