Synthesis of testoreoneand its regulation; role of aldehyde oxidase and keto-reductase enzymes

Abstract

Retinoic acid (RA) is produced by the conversion of retinol to retinaldehyde by the enzyme aldehyde dehydrogenase. The mouse aldehyde oxidase AOX (aldehyde oxidase) is a molybdoflavoenzyme. Testosterone is a negative regulator of AOX in Harderian glands. Purified AOX oxidizes retinaldehyde into retinoic acid, while it is devoid of pyridoxal-oxidizing activity. In mice lacking the aldehyde oxidase, the first aldehyde oxidase knockout animals ever generated, are viable and fertile. In the rodents the Harderian gland's transcriptome of knockout demonstrates overall down regulation of direct retinoid-dependent genes as well as perturbations in pathways controlling lipid homeostasis and cellular secretion, particularly in sexually immature animals. Humans have been shown to have the AOX enzymes although little is known about their possible patho-physiological functions. This review article will discuss the role of aldehyde oxidase and aldehyde keto reductase enzymes in testosterone hormone synthesis and maintenance.

Keywords: AOX, aldehyde keto reductase enzymes