UCP1 and metabolic dysfunction-associated steatotic liver disease: For example, succinate can be absorbed by brown/beige adipose tissues to increase the expression of the thermogenic gene UCP1, promoting thermogenesis.122 Studies on nonalcoholic fatty liver disease (NAFLD) further found that M1 macrophage expression and succinate levels were increased in the livers of mice lacking UCP1 expression, which is also seen in NAFLD.