AKR1B1

AKR1B1 Full Name

aldo-keto reductase family 1, member B1 (aldose reductase)

AKR1B1 Introduction

Aldo-Keto Reductase Family 1 Member B1 is a protein-coding gene that encodes an enzyme belonging to the aldo-keto reductase superfamily. It is widely expressed across various tissues, with notable presence in organs involved in metabolism and detoxification. As a key metabolic enzyme, it catalyzes the reduction of various aldehydes and ketones to their corresponding alcohols, relying on a specific coenzyme for its activity. Its role in modulating metabolic processes and protecting cells from toxic substances makes it an integral part of cellular homeostasis and overall organismal health.Aldo-Keto Reductase Family 1 Member B1 plays a critical role in cellular metabolism and detoxification. It participates in glucose metabolism and osmoregulation, helping to maintain cellular balance. It also protects cells from damage by reducing toxic aldehydes derived from lipid peroxidation and other metabolic processes. Additionally, it is involved in steroidogenesis and retinoid metabolic processes, supporting the normal function of various tissues. Proper function of this enzyme is essential for maintaining metabolic homeostasis and protecting cells from oxidative stress.

Figure 1. Schematic structure of AKR1B1.

Role in Oxidative Stress and Inflammation
In addition to its role in the polyol pathway, AKR1B1 participates in the detoxification of reactive aldehydes generated by lipid peroxidation and oxidative stress. The enzyme efficiently reduces 4-hydroxynonenal, a highly reactive aldehyde that forms covalent adducts with proteins and DNA, to the less toxic alcohol. By reducing 4-hydroxynonenal and other aldehyde products of lipid peroxidation, AKR1B1 protects cells from oxidative damage. In animal models of ischemia-reperfusion injury, AKR1B1 is upregulated, and its inhibition exacerbates tissue damage, indicating that AKR1B1 plays a protective role under conditions of acute oxidative stress. However, under chronic hyperglycemic conditions, the protective role of AKR1B1 may be overwhelmed by the deleterious effects of sorbitol accumulation and NADPH depletion. AKR1B1 also influences inflammation by regulating the production of pro-inflammatory cytokines. In macrophages, AKR1B1 is induced by inflammatory stimuli, and its activity promotes the production of tumor necrosis factor alpha and interleukin 6 through a mechanism involving the transcription factor NF-kappa B. AKR1B1 inhibitors reduce cytokine production and inflammation in animal models of colitis and arthritis, suggesting that AKR1B1 may be a therapeutic target for inflammatory diseases as well as for diabetic complications.

AKR1B1 as a Therapeutic Target
AKR1B1 has been an intensively studied therapeutic target for the prevention and treatment of diabetic complications. Several potent and selective AKR1B1 inhibitors have been developed, and one of them, epalrestat, is approved for clinical use in several countries, including Japan and China, for the treatment of diabetic neuropathy. Epalrestat has been shown to improve nerve conduction velocity, reduce neuropathic pain, and slow the progression of diabetic neuropathy in clinical trials. However, the efficacy of epalrestat is modest, and it has not been approved for use in the United States or Europe. Other AKR1B1 inhibitors that have entered clinical development include zenarestat, fidarestat, and ranirestat, but these have shown limited efficacy or safety concerns in clinical trials. The reasons for the disappointing clinical results of AKR1B1 inhibitors include the multifactorial nature of diabetic complications, the need for earlier intervention before irreversible damage occurs, and the possibility that AKR1B1 inhibitors may not penetrate sufficiently into target tissues. In addition to diabetic complications, AKR1B1 inhibitors are being explored for the treatment of inflammatory diseases and as chemosensitizers for cancer therapy. Novel AKR1B1 inhibitors with improved potency and tissue distribution are in preclinical development, as are proteolysis-targeting chimeras that degrade AKR1B1 rather than simply inhibiting its activity.

Alternate Names for AKR1B1

AKR1B1; aldo-keto reductase family 1, member B1 (aldose reductase); AR; ADR; ALR2; ALDR1; aldose reductase; aldehyde reductase 1; low Km aldose reductase; Lii5-2 CTCL tumor antigen; aldo-keto reductase family 1 member B1;