Diabetes and Obesity Center, School of Medicine, University of Louisville, Louisville, KY 40202, United States.
Chem Biol Interact. 2011 May 30;191(1-3):177-84. doi: 10.1016/j.cbi.2011.01.020. Epub 2011 Jan 27.
The Aldo Keto Reductases (AKRs) are a superfamily of enzymes that catalyze the reduction of biogenic and xenobiotic aldehydes and ketones. AKR1B family has 2 known members in humans and 3 in rodents. Two novel gene loci, hereafter referred to as AKR1B15 in human and Akr1b16 in mouse have been predicted to exist within the AKR1B clusters. AKR1B15 displays 91% and 67% sequence identity with human genes AKR1B10 and AKR1B1, respectively while Akr1b16 shares 82-84% identity with murine Akr1b8 and Akr1b7. We tested the hypothesis that AKR1B15 and Akr1b16 genes are expressed as functional proteins in human and murine tissues, respectively. Using whole tissue mRNA, we were able to clone the full-length open reading frames for AKR1B15 from human eye and testes, and Akr1b16 from murine spleen, demonstrating that these genes are transcriptionally active. The corresponding cDNAs were cloned into pET28a and pIRES-hrGFP-1α vectors for bacterial and mammalian expression, respectively. Both genes were expressed as 36kDa proteins found in the insoluble fraction of bacterial cell lysate. These proteins, expressed in bacteria showed no enzymatic activity. However, lysates from COS-7 cells transfected with AKR1B15 showed a 4.8-fold (with p-nitrobenzaldehyde) and 3.3-fold (with dl-glyceraldehyde) increase in enzyme activity compared with untransfected COS-7 cells. The Akr1b16 transcript was shown to be ubiquitously expressed in murine tissues. Highest levels of transcript were found in heart, spleen, and lung. From these observations we conclude that the predicted AKR1B15 and 1b16 genes are expressed in several murine and human tissues. Further studies are required to elucidate their physiological roles.
醛酮还原酶（AKR）是一个超家族的酶，能够催化生物和异源醛酮的还原。AKR1B 家族在人类中有 2 个已知成员，在啮齿动物中有 3 个。两个新的基因座，以下分别称为人类的 AKR1B15 和小鼠的 Akr1b16，被预测存在于 AKR1B 簇内。AKR1B15 与人类基因 AKR1B10 和 AKR1B1 分别具有 91%和 67%的序列同一性，而 Akr1b16 与鼠类 Akr1b8 和 Akr1b7 具有 82-84%的同一性。我们测试了以下假设：AKR1B15 和 Akr1b16 基因分别在人类和鼠类组织中表达为功能性蛋白质。使用全组织 mRNA，我们能够从人眼和睾丸中克隆 AKR1B15 的全长开放阅读框，并从鼠脾中克隆出 Akr1b16，证明这些基因是转录活跃的。相应的 cDNA 被克隆到 pET28a 和 pIRES-hrGFP-1α 载体中，分别用于细菌和哺乳动物的表达。这两个基因都被表达为 36kDa 的蛋白质，存在于细菌细胞裂解物的不溶性部分中。这些在细菌中表达的蛋白质没有酶活性。然而，用 AKR1B15 转染的 COS-7 细胞的裂解物与未转染的 COS-7 细胞相比，酶活性分别增加了 4.8 倍（用对硝基苯甲醛）和 3.3 倍（用 dl-甘油醛）。Akr1b16 的转录本在鼠组织中广泛表达。在心脏、脾脏和肺中发现的转录本水平最高。从这些观察结果中，我们得出结论，预测的 AKR1B15 和 1b16 基因在几种人类和鼠类组织中表达。需要进一步的研究来阐明它们的生理作用。
