AKR7A2

AKR7A2 Full Name

aldo-keto reductase family 7, member A2 (aflatoxin aldehyde reductase)

AKR7A2 Introduction

AKR7A2 (also known as AFAR2, aflatoxin B1 aldehyde reductase member 2) is a member of the aldo-keto reductase (AKR) superfamily, primarily involved in the detoxification of reactive aldehydes derived from lipid peroxidation and xenobiotic metabolism. The enzyme catalyzes the NADPH-dependent reduction of succinic semialdehyde to 纬-hydroxybutyrate (GHB) and plays a critical role in the metabolism of aflatoxin B1-8,9-dialdehyde, a toxic and carcinogenic metabolite of the mycotoxin aflatoxin B1. Unlike many other aldo-keto reductases that are highly expressed in the liver, AKR7A2 is ubiquitously expressed with the highest levels in the brain, where it is a major succinic semialdehyde reductase. This unique dual function places AKR7A2 at the crossroads of neurobiology and chemical carcinogenesis.

Figure 1. Schematic structure of AKR7A2.

Tissue Distribution and Cellular Localization

AKR7A2 mRNA and protein are detected in virtually all human tissues, but expression levels vary considerably. Highest expression is observed in the brain (particularly cerebellum, cerebral cortex, and hippocampus), followed by the liver, kidney, adrenal gland, and small intestine. Immunohistochemical studies localize AKR7A2 primarily to the cytosol, with some punctate perinuclear distribution. In the brain, AKR7A2 is enriched in neurons rather than glia, consistent with its role in neurotransmitter metabolism. Notably, AKR7A2 expression is induced by antioxidants and chemoprotective agents (e.g., oltipraz, sulforaphane) via the Nrf2/ARE signaling pathway, further supporting its cytoprotective function.

Expression and Biochemical Characteristics
AKR7A2 exhibits widespread expression across various tissues, with highest levels in the liver, kidneys, and gastrointestinal tract—tissues directly involved in detoxification and metabolite processing. The enzyme functions in an NADPH-dependent manner, utilizing the coenzyme to drive the reduction of its substrates with high stereospecificity. Multiple transcript variants of AKR7A2 have been identified, allowing for tissue-specific regulation of its expression and catalytic activity. Its biochemical structure is optimized for substrate binding and catalysis, with a conserved active site that enables recognition of diverse aldehyde and ketone substrates, underscoring its role as a versatile detoxifying enzyme.

Alternate Names for AKR7A2

AKR7A2; aldo-keto reductase family 7, member A2 (aflatoxin aldehyde reductase); aflatoxin B1 aldehyde reductase member 2; AFAR; AFB1-AR 1; SSA reductase; aldoketoreductase 7; AFB1 aldehyde reductase 1; succinic semialdehyde reductase; aflatoxin beta1 aldehyde reductase; AKR7; AFAR1; AFB1-AR1;