Steroid-converting enzymes in human adipose tissues and fat deposition with a focus on AKR1C enzymes

Adipocytes express various enzymes, such as aldo-keto reductases (AKR1C), 11β-hydroxysteroid dehydrogenase (11β-HSD), aromatase, 5α-reductases, 3β-HSD, and 17β-HSDs involved in steroid hormone metabolism in adipose tissues. Increased activity of AKR1C enzymes and their expression in mature adipocytes might indicate the association of these enzymes with subcutaneous adipose tissue deposition. The inactivation of androgens by AKR1C enzymes increases adipogenesis and fat mass, particularly subcutaneous fat. AKR1C also causes reduction of estrone, a weak estrogen, to produce 17β-estradiol, a potent estrogen and, in addition, it plays a role in progesterone metabolism. Functional impairments of adipose tissue and imbalance of steroid biosynthesis could lead to metabolic disturbances. In this review, we will focus on the enzymes involved in steroid metabolism and fat tissue deposition.