Human and rodent aldo–keto reductases from the AKR1B subfamily and their specificity with retinaldehyde

Abstract

NADP(H)-dependent cytosolic aldo-keto reductases (AKR) are mostly monomeric enzymes which fold into a typical (α/β)8-barrel structure. Substrate specificity and inhibitor selectivity are determined by interaction with residues located in three highly variable loops (A, B, and C). Based on sequence identity, AKR have been grouped into families, namely AKR1–AKR15, containing multiple subfamilies. Two human enzymes from the AKR1B subfamily (AKR1B1 and AKR1B10) are of special interest. AKR1B1 (aldose reductase) is related to secondary diabetic complications, while AKR1B10 is induced in cancer cells and is highly active with all-trans-retinaldehyde. Residues interacting with all-trans-retinaldehyde and differing between AKR1B1 and AKR1B10 are Leu125Lys and Val131Ala (loop A), Leu301Val, Ser303Gln, and Cys304Ser (loop C). Recently, we demonstrated the importance of Lys125 as a determinant of AKR1B10 specificity for retinoids. Residues 301 and 304 are also involved in interactions with substrates or inhibitors, and thus we checked their contribution to retinoid specificity. We also extended our study with retinoids to rodent members of the AKR1B subfamily: AKR1B3 (aldose reductase), AKR1B7 (mouse vas deferens protein), AKR1B8 (fibroblast-growth factor 1-regulated protein), and AKR1B9 (Chinese hamster ovary reductase), which were tested against all-trans isomers of retinaldehyde and retinol. All enzymes were active with retinaldehyde, but with kcat values (0.02–0.52 min−1) much lower than that of AKR1B10 (27 min−1). None of the enzymes showed oxidizing activity with retinol. Since these enzymes (except AKR1B3) have Lys125, other residues should account for retinaldehyde specificity. Here, by using site-directed mutagenesis and molecular modeling, we further delineate the contribution of residues 301 and 304. We demonstrate that besides Lys125, Ser304 is a major structural determinant for all-trans-retinaldehyde specificity of AKR1B10.

RNA-Seq reveals common and unique PXR- and CAR-target gene signatures in the mouse liver transcriptome

“…Specifically, both PCN and TCPOBOP markedly up-regulated multiple glutathione S -transferases, which are important for glutathione conjugation of substrates and chemical detoxification (Parkinson et al, 2013). Regarding retinoid metabolism, both PCN and TCPOBOP markedly up-regulated Akr1b7, which is important in the metabolism of retinaldehyde (Ruiz et al, 2011) and the detoxification of lipid peroxidation byproducts (Liu et al, 2009); PCN and TCPOBOP also up-regulated Cyp26a1, which is important in the elimination of active retinoids (Topletz et al, 2015). In addition, Abcd2, which is an Abc transporter of which the promoter activity of is induced by 9-cis-retinoic acid (Pujol et al, 2000), was up-regulated by PCN and TCPOBOP.…”

Characterization of AKR1B16, a novel mouse aldo-keto reductase

“…Notably, a region located between amino acid residues 80 and 100, showing high sequence differences and forming an α-helix and a turn, is found to be located close to the conserved catalytic residue Lys78. As noted by Ruiz et al [6], all the human and murine proteins of the aldose reductase type (AKR1B1, AKR1B3 and AKR1B4) share a common Leu125, whereas all the other enzymes share a common Lys125, with the exception of AKR1B16 and AKR1B17 having a Thr at that position. A Lys at position 125 appeared to be an important determinant for all-trans-retinaldehyde specificity of AKR1B10 [43].…”

“…It is expressed in numerous tissues and a recent study determined a 20-fold prevalence in brain as compared to other tissues [1]. AKR1B3 acts as an aldose reductase, showing a similar K m value for glucose (82 mM [13]) and catalytic efficiency with D,Lglyceraldehyde as the human ortholog AKR1B1, and also exhibits low activity with retinaldehyde [6]. Mouse AKR1B3 has been widely studied in in vivo models due to the crucial role of human AKR1B1 in the development of diabetic complications [17].…”

“…The AKR1 family is the largest, comprising the AKR1A (aldehyde reductase), AKR1B (aldose reductase), AKR1C (hydroxysteroid reductase), AKR1D (ketosteroid reductase) and AKR1E subfamilies [5]. Among these are important key enzymes in the metabolism of hormones, including steroids, prostaglandins and retinoids [1,6,7]. The AKR1B family is responsible for the reduction of toxic aldehydes generated during lipid peroxidation and steroidogenesis, and also has prostaglandin F 2α (PGF 2α ) synthase and retinaldehyde reductase activities [3,8].…”

Statil suppresses cancer cell growth and proliferation by the inhibition of tumor marker AKR1B10

“…AKR1B10 is also active to alltrans-retinal, a precursor of the signaling molecule retinoic acid that regulates cell proliferation and differentiation, and to polycyclic aromatic hydrocarbon, an environmental procarcinogen [7][8][9][10][11][12]. Recent studies from our and other laboratories have shown that AKR1B10 can reduce the C-13 ketonic group in daunorubicin and idarubicin, leading to chemoresistance of cancer cells to these cytostatic agents [13][14][15], suggesting that AKR1B10 is an important carbonyl reductase involved in cell growth and proliferation and in drug resistance.…”