Feimin activates adaptive thermogenesis by linking AMPK to PGC1α in adipose tissue

Adaptive thermogenesis, the process of heat production to maintain body temperature, is a crucial mechanism for energy dissipation and a defense against obesity. Despite its importance, the precise molecular pathways coupling cellular energy sensing to transcriptional control of thermogenic genes remain incompletely understood. Current strategies for boosting energy expenditure often lack specificity or encounter side effects. Understanding novel regulators like Feimin that integrate metabolic signals with gene expression could unlock more effective and targeted interventions for metabolic disorders.

Researchers investigated the role of Feimin in adaptive thermogenesis, primarily utilizing mouse models. They explored its phosphorylation status and subcellular localization in response to cold exposure. The study employed genetic manipulation, specifically generating adipose-specific Feimin knockout mice to assess its necessity for cold-induced thermogenesis and its impact on diet-induced obesity. Furthermore, they tested a nuclear localization-defective Feimin mutant to delineate the functional importance of its nuclear translocation. Biochemical assays likely included immunoprecipitation and western blotting to confirm protein interactions and phosphorylation, and qPCR to measure thermogenic gene expression.

Feimin was identified as a critical activator of adaptive thermogenesis, bridging AMPK signaling with nuclear transcriptional regulation within adipose tissue. Upon exposure to cold, AMPK directly phosphorylated Feimin, which subsequently promoted its translocation into the nucleus. Once in the nucleus, Feimin directly interacted with PGC1α, a master regulator of mitochondrial biogenesis and thermogenesis, thereby driving the expression of thermogenic genes. Conversely, conditions of obesity were found to attenuate Feimin phosphorylation and its nuclear localization, leading to a significant impairment in thermogenic capacity. The functional importance of Feimin was further underscored by genetic studies: > Adipose-specific Feimin knockout mice completely abolished cold-induced thermogenesis and exacerbated diet-induced obesity. These severe phenotypes could not be rescued by a Feimin mutant lacking the ability to translocate into the nucleus, highlighting the essential role of nuclear Feimin in thermogenic regulation. These findings collectively establish a novel AMPK-Feimin-PGC1α signaling axis as fundamental for controlling thermogenesis.