Figure 5.

Lactate induces beiging as a way to dissipate redox pressure. Following its import through MCT1, lactate is converted into pyruvate. This conversion is associated with the reduction of NAD⁺ into NADH,H⁺. The increased NADH, H⁺/NAD⁺ ratio triggers UCP1 expression. Due to the properties of UCP1 and its effects on the respiratory chain, UCP1-dependent uncoupling accelerates oxidation of NADH,H⁺ into NAD⁺. Thus, UCP1-dependent uncoupling, in addition to its involvement in non-shivering thermogenesis, may also play an active role in redox homeostasis. Of note, MCT1 is expressed at the cell surface of the subpopulation of adipocytes that will express UCP1 after cold exposure, highlighting it as a marker of inducible beige adipocytes (Carriere et al., 2014; Jeanson et al., 2015; Lagarde et al., 2020).