301
|
Skarydova L, Nobilis M, Wsól V. Role of carbonyl reducing enzymes in the phase I biotransformation of the non-steroidal anti-inflammatory drug nabumetone in vitro. Xenobiotica 2012; 43:346-54. [PMID: 23020786 DOI: 10.3109/00498254.2012.720048] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
1. Nabumetone is a clinically used non-steroidal anti-inflammatory drug, its biotransformation includes major active metabolite 6-methoxy-2-naphtylacetic acid and another three phase I as well as corresponding phase II metabolites which are regarded as inactive. One important biotransformation pathway is carbonyl reduction, which leads to the phase I metabolite, reduced nabumetone. 2. The aim of this study is the determination of the role of a particular human liver subcellular fraction in the nabumetone reduction and the identification of participating carbonyl reducing enzymes along with their stereospecificities. 3. Both subcellular fractions take part in the carbonyl reduction of nabumetone and the reduction is at least in vitro the main biotransformation pathway. The activities of eight cytosolic carbonyl reducing enzymes--CBR1, CBR3, AKR1B1, AKR1B10, AKR1C1-4--toward nabumetone were tested. Except for CBR3, all tested reductases transform nabumetone to its reduced metabolite. AKR1C4 and AKR1C3 have the highest intrinsic clearances. 4. The stereospecificity of the majority of the tested enzymes is shifted to the production of an (+)-enantiomer of reduced nabumetone; only AKR1C1 and AKR1C4 produce predominantly an (-)-enantiomer. This project provides for the first time evidence that seven specific carbonyl reducing enzymes participate in nabumetone metabolism.
Collapse
Affiliation(s)
- Lucie Skarydova
- Department of Biochemical Sciences, Faculty of Pharmacy in Hradec Králové, Charles University in Prague, Czech Republic
| | | | | |
Collapse
|
302
|
Gong J, Gan J, Masson E, Syed S, Xia YQ, Williams D, Pursley J, Jemal M, Humphreys WG, Iyer RA. Metabolic chiral inversion of brivanib and its relevance to safety and pharmacology. Drug Metab Dispos 2012; 40:2374-80. [PMID: 22983304 DOI: 10.1124/dmd.112.047340] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Brivanib alaninate is an orally administered alanine prodrug of brivanib, a dual inhibitor of the vascular endothelial growth factor (VEGF) and fibroblast growth factor (FGF) signaling pathways. It is currently in clinical trials for the treatment of hepatocellular carcinoma and colorectal cancer. Brivanib has a single asymmetric center derived from a secondary alcohol. The potential for chiral inversion was investigated in incubations with liver subcellular fractions and in animals and humans after oral doses of brivanib alaninate. Incubations of [¹⁴C]brivanib alaninate with liver microsomes and cytosols from rats, monkeys, and humans followed by chiral chromatography resulted in two radioactive peaks, corresponding to brivanib and its enantiomer. The percentage of the enantiomeric metabolite relative to brivanib in microsomal and cytosolic incubations of different species in the presence of NADPH ranged from 11.6 to 15.8 and 0.8 to 3.1%, respectively. The proposed mechanism of inversion involves the oxidation of brivanib to a ketone metabolite, which is subsequently reduced to brivanib and its enantiomer. After oral doses of brivanib alaninate to rats and monkeys, the enantiomeric metabolite was a prominent drug-related component in plasma, with the percentages of area under the curve (AUC) at 94.7 and 39.7%, respectively, relative to brivanib. In humans, the enantiomeric metabolite was a minor circulating component, with the AUC <3% of brivanib. Pharmacological studies indicated that brivanib and its enantiomer had similar potency toward the inhibition of VEGF receptor-2 and FGF receptor-1 kinases. Because of low plasma concentration in humans, the enantiomeric metabolite was not expected to contribute significantly to target-related pharmacology of brivanib. Moreover, adequate exposure in the toxicology species suggested no specific safety concerns with respect to exposure to the enantiomeric metabolite.
Collapse
Affiliation(s)
- Jiachang Gong
- Bristol-Myers Squibb, P.O. Box 4000, Princeton, NJ 08543, USA.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
303
|
Kaushal M, Mishra AK, Sharma J, Zomawia E, Kataki A, Kapur S, Saxena S. Genomic alterations in breast cancer patients in betel quid and non betel quid chewers. PLoS One 2012; 7:e43789. [PMID: 22937096 PMCID: PMC3427153 DOI: 10.1371/journal.pone.0043789] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2012] [Accepted: 07/24/2012] [Indexed: 01/12/2023] Open
Abstract
Betel Quid (BQ) chewing independently contributes to oral, hepatic and esophageal carcinomas. Strong association of breast cancer risk with BQ chewing in Northeast Indian population has been reported where this habit is prodigal. We investigated genomic alterations in breast cancer patients with and without BQ chewing exposure. Twenty six BQ chewers (BQC) and 17 non BQ chewer (NBQC) breast cancer patients from Northeast India were analyzed for genomic alterations and pathway networks using SNP array and IPA. BQC tumors showed significantly (P<0.01) higher total number of alterations, as compared with NBQC tumors, 48±17% versus 32±25 respectively. Incidence of gain in fragile sites in BQC tumors were significantly (P<0.001) higher as compared with NBQC tumors, 34 versus 23% respectively. Two chromosomal regions (7q33 and 21q22.13) were significantly (p<0.05) associated with BQC tumors while two regions (19p13.3–19p12 and 20q11.22) were significantly associated with NBQC tumors. GO terms oxidoreductase and aldo-keto reductase activity in BQC tumors in contrast to G-protein coupled receptor protein signaling pathway and cell surface receptor linked signal transduction in NBQC tumors were enriched in DAVID. One network “Drug Metabolism, Molecular Transport, Nucleic Acid Metabolism” including genes AKR1B1, AKR1B10, ETS2 etc in BQC and two networks “Molecular Transport, Nucleic Acid Metabolism, Small Molecule Biochemistry” and “Cellular Development, Embryonic Development, Organismal Development” including genes RPN2, EMR3, VAV1, NNAT and MUC16 etc were seen in NBQC. Common alterations (>30%) were seen in 27 regions. Three networks were significant in common regions with key roles of PTK2, RPN2, EMR3, VAV1, NNAT, MUC16, MYC and YWHAZ genes. These data show that breast cancer arising by environmental carcinogens exemplifies genetic alterations differing from those observed in the non exposed ones. A number of genetic changes are shared in both tumor groups considered as crucial in breast cancer progression.
Collapse
Affiliation(s)
- Mishi Kaushal
- National Institute of Pathology, ICMR, Safdarjung Hospital Campus, New Delhi, India
| | - Ashwani K. Mishra
- National Institute of Pathology, ICMR, Safdarjung Hospital Campus, New Delhi, India
| | | | | | - Amal Kataki
- Dr. B. Borrooah Cancer Institute, Guwahati, India
| | - Sujala Kapur
- National Institute of Pathology, ICMR, Safdarjung Hospital Campus, New Delhi, India
| | - Sunita Saxena
- National Institute of Pathology, ICMR, Safdarjung Hospital Campus, New Delhi, India
- * E-mail:
| |
Collapse
|
304
|
3-(3,4-Dihydroisoquinolin-2(1H)-ylsulfonyl)benzoic Acids: highly potent and selective inhibitors of the type 5 17-β-hydroxysteroid dehydrogenase AKR1C3. J Med Chem 2012; 55:7746-58. [PMID: 22877157 DOI: 10.1021/jm3007867] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
A high-throughput screen identified 3-(3,4-dihydroisoquinolin-2(1H)-ylsulfonyl)benzoic acid as a novel, highly potent (low nM), and isoform-selective (1500-fold) inhibitor of aldo-keto reductase AKR1C3: a target of interest in both breast and prostate cancer. Crystal structure studies showed that the carboxylate group occupies the oxyanion hole in the enzyme, while the sulfonamide provides the correct twist to allow the dihydroisoquinoline to bind in an adjacent hydrophobic pocket. SAR studies around this lead showed that the positioning of the carboxylate was critical, although it could be substituted by acid isosteres and amides. Small substituents on the dihydroisoquinoline gave improvements in potency. A set of "reverse sulfonamides" showed a 12-fold preference for the R stereoisomer. The compounds showed good cellular potency, as measured by inhibition of AKR1C3 metabolism of a known dinitrobenzamide substrate, with a broad rank order between enzymic and cellular activity, but amide analogues were more effective than predicted by the cellular assay.
Collapse
|
305
|
Zheng X, Zhang L, Chen W, Chen Y, Xie W, Hu X. Partial Inhibition of Aldose Reductase by Nitazoxanide and Its Molecular Basis. ChemMedChem 2012; 7:1921-3. [DOI: 10.1002/cmdc.201200333] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2012] [Indexed: 02/06/2023]
|
306
|
Pastel E, Pointud JC, Volat F, Martinez A, Lefrançois-Martinez AM. Aldo-Keto Reductases 1B in Endocrinology and Metabolism. Front Pharmacol 2012; 3:148. [PMID: 22876234 PMCID: PMC3410611 DOI: 10.3389/fphar.2012.00148] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2012] [Accepted: 07/11/2012] [Indexed: 01/10/2023] Open
Abstract
The aldose reductase (AR; human AKR1B1/mouse Akr1b3) has been the focus of many research because of its role in diabetic complications. The starting point of these alterations is the massive entry of glucose in polyol pathway where it is converted into sorbitol by this enzyme. However, the issue of AR function in non-diabetic condition remains unresolved. AR-like enzymes (AKR1B10, Akr1b7, and Akr1b8) are highly related isoforms often co-expressed with bona fide AR, making functional analysis of one or the other isoform a challenging task. AKR1B/Akr1b members share at least 65% protein identity and the general ability to reduce many redundant substrates such as aldehydes provided from lipid peroxidation, steroids and their by-products, and xenobiotics in vitro. Based on these properties, AKR1B/Akr1b are generally considered as detoxifying enzymes. Considering that divergences should be more informative than similarities to help understanding their physiological functions, we chose to review specific hallmarks of each human/mouse isoforms by focusing on tissue distribution and specific mechanisms of gene regulation. Indeed, although the AR shows ubiquitous expression, AR-like proteins exhibit tissue-specific patterns of expression. We focused on three organs where certain isoforms are enriched, the adrenal gland, enterohepatic, and adipose tissues and tried to connect recent enzymatic and regulation data with endocrine and metabolic functions of these organs. We presented recent mouse models showing unsuspected physiological functions in the regulation of glucido-lipidic metabolism and adipose tissue homeostasis. Beyond the widely accepted idea that AKR1B/Akr1b are detoxification enzymes, these recent reports provide growing evidences that they are able to modify or generate signal molecules. This conceptually shifts this class of enzymes from unenviable status of scavenger to upper class of messengers.
Collapse
Affiliation(s)
- Emilie Pastel
- CNRS, UMR6293/INSERM U1103, Génétique, Reproduction et Développement, Clermont Université Aubière, France
| | | | | | | | | |
Collapse
|
307
|
Cousido-Siah A, Petrova T, Hazemann I, Mitschler A, Ruiz FX, Howard E, Ginell S, Atmanene C, Van Dorsselaer A, Sanglier-Cianférani S, Joachimiak A, Podjarny A. Crystal packing modifies ligand binding affinity: the case of aldose reductase. Proteins 2012; 80:2552-61. [PMID: 22752989 DOI: 10.1002/prot.24136] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2012] [Revised: 06/05/2012] [Accepted: 06/13/2012] [Indexed: 01/06/2023]
Abstract
The relationship between the structures of protein-ligand complexes existing in the crystal and in solution, essential in the case of fragment-based screening by X-ray crystallography (FBS-X), has been often an object of controversy. To address this question, simultaneous co-crystallization and soaking of two inhibitors with different ratios, Fidarestat (FID; K(d) = 6.5 nM) and IDD594 (594; K(d) = 61 nM), which bind to h-aldose reductase (AR), have been performed. The subatomic resolution of the crystal structures allows the differentiation of both inhibitors, even when the structures are almost superposed. We have determined the occupation ratio in solution by mass spectrometry (MS) Occ(FID)/Occ(594) = 2.7 and by X-ray crystallography Occ(FID)/Occ(594) = 0.6. The occupancies in the crystal and in solution differ 4.6 times, implying that ligand binding potency is influenced by crystal contacts. A structural analysis shows that the Loop A (residues 122-130), which is exposed to the solvent, is flexible in solution, and is involved in packing contacts within the crystal. Furthermore, inhibitor 594 contacts the base of Loop A, stabilizing it, while inhibitor FID does not. This is shown by the difference in B-factors of the Loop A between the AR-594 and AR-FID complexes. A stable loop diminishes the entropic energy barrier to binding, favoring 594 versus FID. Therefore, the effect of the crystal environment should be taken into consideration in the X-ray diffraction analysis of ligand binding to proteins. This conclusion highlights the need for additional methodologies in the case of FBS-X to validate this powerful screening technique, which is widely used.
Collapse
Affiliation(s)
- Alexandra Cousido-Siah
- Department of Integrative Biology, IGBMC, CNRS, INSERM, Université de Strasbourg, Illkirch, France
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
308
|
N-Benzoyl anthranilic acid derivatives as selective inhibitors of aldo-keto reductase AKR1C3. Bioorg Med Chem Lett 2012; 22:5948-51. [PMID: 22897946 DOI: 10.1016/j.bmcl.2012.07.062] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2012] [Revised: 07/12/2012] [Accepted: 07/16/2012] [Indexed: 01/26/2023]
Abstract
Human aldo-keto reductases AKR1C1-AKR1C3 are involved in the biosynthesis and inactivation of steroid hormones and prostaglandins and thus represent attractive targets for the development of new drugs. We synthesized a series of N-benzoyl anthranilic acid derivatives and tested their inhibitory activity on AKR1C enzymes. Our data show that these derivatives inhibit AKR1C1-AKR1C3 isoforms with low micromolar potency. In addition, five selective inhibitors of AKR1C3 were identified. The most promising inhibitors were compounds 10 and 13, with IC(50) values of 0.31 μM and 0.35 μM for AKR1C3, respectively.
Collapse
|
309
|
Wu KC, Cui JY, Klaassen CD. Effect of graded Nrf2 activation on phase-I and -II drug metabolizing enzymes and transporters in mouse liver. PLoS One 2012; 7:e39006. [PMID: 22808024 PMCID: PMC3395627 DOI: 10.1371/journal.pone.0039006] [Citation(s) in RCA: 116] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2012] [Accepted: 05/16/2012] [Indexed: 02/07/2023] Open
Abstract
Nuclear factor erythroid 2-related factor 2 (Nrf2) is a transcription factor that induces a battery of cytoprotective genes in response to oxidative/electrophilic stress. Kelch-like ECH associating protein 1 (Keap1) sequesters Nrf2 in the cytosol. The purpose of this study was to investigate the role of Nrf2 in regulating the mRNA of genes encoding drug metabolizing enzymes and xenobiotic transporters. Microarray analysis was performed in livers of Nrf2-null, wild-type, Keap1-knockdown mice with increased Nrf2 activation, and Keap1-hepatocyte knockout mice with maximum Nrf2 activation. In general, Nrf2 did not have a marked effect on uptake transporters, but the mRNAs of organic anion transporting polypeptide 1a1, sodium taurocholate cotransporting polypeptide, and organic anion transporter 2 were decreased with Nrf2 activation. The effect of Nrf2 on cytochrome P450 (Cyp) genes was minimal, with only Cyp2a5, Cyp2c50, Cyp2c54, and Cyp2g1 increased, and Cyp2u1 decreased with enhanced Nrf2 activation. However, Nrf2 increased mRNA of many other phase-I enzymes, such as aldo-keto reductases, carbonyl reductases, and aldehyde dehydrogenase 1. Many genes involved in phase-II drug metabolism were induced by Nrf2, including glutathione S-transferases, UDP- glucuronosyltransferases, and UDP-glucuronic acid synthesis enzymes. Efflux transporters, such as multidrug resistance-associated proteins, breast cancer resistant protein, as well as ATP-binding cassette g5 and g8 were induced by Nrf2. In conclusion, Nrf2 markedly alters hepatic mRNA of a large number of drug metabolizing enzymes and xenobiotic transporters, and thus Nrf2 plays a central role in xenobiotic metabolism and detoxification.
Collapse
Affiliation(s)
- Kai Connie Wu
- Department of Pharmacology, Toxicology, and Therapeutics, University of Kansas Medical Center, Kansas City, Kansas, United States of America
| | - Julia Yue Cui
- Department of Pharmacology, Toxicology, and Therapeutics, University of Kansas Medical Center, Kansas City, Kansas, United States of America
| | - Curtis D. Klaassen
- Department of Pharmacology, Toxicology, and Therapeutics, University of Kansas Medical Center, Kansas City, Kansas, United States of America
- * E-mail:
| |
Collapse
|
310
|
Paramanik V, Thakur MK. Estrogen receptor β and its domains interact with casein kinase 2, phosphokinase C, and N-myristoylation sites of mitochondrial and nuclear proteins in mouse brain. J Biol Chem 2012; 287:22305-16. [PMID: 22566700 DOI: 10.1074/jbc.m112.351262] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The localization of estrogen receptor (ER)β in mitochondria suggests ERβ-dependent regulation of genes, which is poorly understood. Here, we analyzed the ERβ interacting mitochondrial as well as nuclear proteins in mouse brain using pull-down assay and matrix-assisted laser desorption ionization mass spectroscopy (MALDI-MS). In the case of mitochondria, ERβ interacted with six proteins of 35-152 kDa, its transactivation domain (TAD) interacted with four proteins of 37-172 kDa, and ligand binding domain (LBD) interacted with six proteins of 37-161 kDa. On the other hand, in nuclei, ERβ interacted with seven proteins of 30-203 kDa, TAD with ten proteins of 31-160 kDa, and LBD with fourteen proteins of 42-179 kDa. For further identification, these proteins were cleaved by trypsin into peptides and analyzed by MALDI-MS using mascot search engine, immunoprecipitation, immunoblotting, and far-Western blotting. To find the consensus binding motifs in interacting proteins, their unique tryptic peptides were analyzed by the motif scan software. All the interacting proteins were found to contain casein kinase (CK) 2, phosphokinase (PK)C phosphorylation, and N-myristoylation sites. These were further confirmed by peptide pull-down assays using specific mutations in the interacting sites. Thus, the present findings provide evidence for the interaction of ERβ with specific mitochondrial and nuclear proteins through consensus CK2, PKC phosphorylation, and N-myristoylation sites, and may represent an essential step toward designing selective ER modulators for regulating estrogen-mediated signaling.
Collapse
Affiliation(s)
- Vijay Paramanik
- Biochemistry and Molecular Biology Laboratory, Centre of Advanced Study, Department of Zoology, Banaras Hindu University, Varanasi-221 005, India
| | | |
Collapse
|
311
|
Endo S, Matsunaga T, Kanamori A, Otsuji Y, Nagai H, Sundaram K, El-Kabbani O, Toyooka N, Ohta S, Hara A. Selective inhibition of human type-5 17β-hydroxysteroid dehydrogenase (AKR1C3) by baccharin, a component of Brazilian propolis. JOURNAL OF NATURAL PRODUCTS 2012; 75:716-21. [PMID: 22506594 DOI: 10.1021/np201002x] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
The human aldo-keto reductase (AKR) 1C3, also known as type-5 17β-hydroxysteroid dehydrogenase and prostaglandin F synthase, has been suggested as a therapeutic target in the treatment of prostate and breast cancers. In this study, AKR1C3 inhibition was examined by Brazilian propolis-derived cinnamic acid derivatives that show potential antitumor activity, and it was found that baccharin (1) is a potent competitive inhibitor (K(i) 56 nM) with high selectivity, showing no significant inhibition toward other AKR1C isoforms (AKR1C1, AKR1C2, and AKR1C4). Molecular docking and site-directed mutagenesis studies suggested that the nonconserved residues Ser118, Met120, and Phe311 in AKR1C3 are important for determining the inhibitory potency and selectivity of 1. The AKR1C3-mediated metabolism of 17-ketosteroid and farnesal in cancer cells was inhibited by 1, which was effective from 0.2 μM with an IC(50) value of about 30 μM. Additionally, 1 suppressed the proliferation of PC3 prostatic cancer cells stimulated by AKR1C3 overexpression. This study is the first demonstration that 1 is a highly selective inhibitor of AKR1C3.
Collapse
Affiliation(s)
- Satoshi Endo
- Laboratory of Biochemistry, Gifu Pharmaceutical University, Gifu 501-1196, Japan.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
312
|
SINGLET OXYGEN RESISTANT 1 links reactive electrophile signaling to singlet oxygen acclimation in Chlamydomonas reinhardtii. Proc Natl Acad Sci U S A 2012; 109:E1302-11. [PMID: 22529359 DOI: 10.1073/pnas.1116843109] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Acclimation of Chlamydomonas reinhardtii cells to low levels of singlet oxygen, produced either by photoreactive chemicals or high light treatment, induces a specific genetic response that strongly increases the tolerance of the algae to subsequent exposure to normally lethal singlet oxygen-producing conditions. The genetic response includes the increased expression of various oxidative stress response and detoxification genes, like the glutathione peroxidase homologous gene GPXH/GPX5 and the σ-class glutathione-S-transferase gene GSTS1. To identify components involved in the signal transduction and activation of the singlet oxygen-mediated response, a mutant selection was performed. This selection led to the isolation of the singlet oxygen resistant 1 (sor1) mutant, which is more tolerant to singlet oxygen-producing chemicals and shows a constitutively higher expression of GPXH and GSTS1. Map-based cloning revealed that the SOR1 gene encodes a basic leucine zipper transcription factor, which controls its own expression and the expression of a large number of oxidative stress response and detoxification genes. In the promoter region of many of these genes, a highly conserved 8-bp palindromic sequence element was found to be enriched. This element was essential for GSTS1 induction by increased levels of lipophilic reactive electrophile species (RES), suggesting that it functions as an electrophile response element (ERE). Furthermore, GSTS1 overexpression in sor1 requires the ERE, although it is unknown whether it occurs through direct binding of SOR1 to the ERE. RES can be formed after singlet oxygen-induced lipid peroxidation, indicating that RES-stimulated and SOR1-mediated responses of detoxification genes are part of the singlet oxygen-induced acclimation process in C. reinhardtii.
Collapse
|
313
|
Ruiz FX, Porté S, Parés X, Farrés J. Biological role of aldo-keto reductases in retinoic Acid biosynthesis and signaling. Front Pharmacol 2012; 3:58. [PMID: 22529810 PMCID: PMC3328219 DOI: 10.3389/fphar.2012.00058] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2011] [Accepted: 03/19/2012] [Indexed: 12/12/2022] Open
Abstract
Several aldo-keto reductase (AKR) enzymes from subfamilies 1B and 1C show retinaldehyde reductase activity, having low K(m) and k(cat) values. Only AKR1B10 and 1B12, with all-trans-retinaldehyde, and AKR1C3, with 9-cis-retinaldehyde, display high catalytic efficiency. Major structural determinants for retinaldehyde isomer specificity are located in the external loops (A and C for AKR1B10, and B for AKR1C3), as assessed by site-directed mutagenesis and molecular dynamics. Cellular models have shown that AKR1B and 1C enzymes are well suited to work in vivo as retinaldehyde reductases and to regulate retinoic acid (RA) biosynthesis at hormone pre-receptor level. An additional physiological role for the retinaldehyde reductase activity of these enzymes, consistent with their tissue localization, is their participation in β-carotene absorption. Retinaldehyde metabolism may be subjected to subcellular compartmentalization, based on enzyme localization. While retinaldehyde oxidation to RA takes place in the cytosol, reduction to retinol could take place in the cytosol by AKRs or in the membranes of endoplasmic reticulum by microsomal retinaldehyde reductases. Upregulation of some AKR1 enzymes in different cancer types may be linked to their induction by oxidative stress and to their participation in different signaling pathways related to cell proliferation. AKR1B10 and AKR1C3, through their retinaldehyde reductase activity, trigger a decrease in the RA biosynthesis flow, resulting in RA deprivation and consequently lower differentiation, with an increased cancer risk in target tissues. Rational design of selective AKR inhibitors could lead to development of novel drugs for cancer treatment as well as reduction of chemotherapeutic drug resistance.
Collapse
Affiliation(s)
- F Xavier Ruiz
- Department of Biochemistry and Molecular Biology, Universitat Autònoma de Barcelona Barcelona, Spain
| | | | | | | |
Collapse
|
314
|
Epidermal growth factor induces tumour marker AKR1B10 expression through activator protein-1 signalling in hepatocellular carcinoma cells. Biochem J 2012; 442:273-82. [PMID: 22329800 DOI: 10.1042/bj20111322] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
AKR1B10 (aldo-keto reductase 1B10) is overexpressed in liver and lung cancer, and plays a critical role in tumour development and progression through promoting lipogenesis and eliminating cytotoxic carbonyls. AKR1B10 is a secretory protein and potential tumour marker; however, little is known about the regulatory mechanism of AKR1B10 expression. The present study showed that AKR1B10 is induced by mitogen EGF (epidermal growth factor) and insulin through the AP-1 (activator protein-1) signalling pathway. In human HCC (hepatocellular carcinoma) cells (HepG2 and Hep3B), EGF (50 ng/ml) and insulin (10 nM) stimulated endogenous AKR1B10 expression and promoter activity. In the AKR1B10 promoter, a putative AP-1 element was found at bp -222 to -212. Deletion or mutation of this AP-1 element abrogated the basal promoter activity and response to EGF and AP-1 proteins. This AP-1 element bound to nuclear proteins extracted from HepG2 cells, and this binding was stimulated by EGF and insulin in a dose-dependent manner. Chromatin immunoprecipitation showed that the AP-1 proteins c-Fos and c-Jun were the predominant factors bound to the AP-1 consensus sequence, followed by JunD and then JunB. The same order was followed in the stimulation of endogenous AKR1B10 expression by AP-1 proteins. Furthermore, c-Fos shRNA (short hairpin RNA) and AP-1 inhibitors/antagonists (U0126 and Tanshinone IIA) inhibited endogenous AKR1B10 expression and promoter activity in HepG2 cells cultured in vitro or inoculated subcutaneously in nude mice. U0126 also inhibited AKR1B10 expression induced by EGF. Taken together, these results suggest that AKR1B10 is up-regulated by EGF and insulin through AP-1 mitogenic signalling and may be implicated in hepatocarcinogenesis.
Collapse
|
315
|
Sundaram K, Endo S, Matsunaga T, Tanaka N, Hara A, El-Kabbani O. Structure of the His269Arg mutant of the rat aldose reductase-like protein AKR1B14 complexed with NADPH. Acta Crystallogr Sect F Struct Biol Cryst Commun 2012; 68:400-3. [PMID: 22505406 PMCID: PMC3325806 DOI: 10.1107/s1744309112008810] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2012] [Accepted: 02/27/2012] [Indexed: 11/11/2022]
Abstract
Rat aldose reductase-like protein (AKR1B14) is an orthologue of mouse vas deferens protein (AKR1B7) and plays roles in the detoxification of reactive aldehydes and synthesis of prostaglandin F(2α). Here, the 1.87 Å resolution crystal structure of the His269Arg mutant of AKR1B14 complexed with NADPH is described and shows that the negatively charged 2'-phosphate group of the coenzyme forms an ionic interaction with the positively charged guanidinium group of Arg269 that is also observed in the human aldose reductase (AKR1B1) structure. Previous experiments on the site-directed mutagenesis of His269 to Arg, Phe and Met revealed fourfold, sevenfold and 127-fold increases in the K(m) for NADPH, respectively, which are in agreement with the present molecular-modelling and X-ray crystallographic studies. This is the first tertiary structure of a mutant form of this AKR1B7 orthologue to be reported in order to investigate the structure-function relationship of the nonconserved His269 and its role in coenzyme binding.
Collapse
Affiliation(s)
- Krithika Sundaram
- Medicinal Chemistry and Drug Action, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, Victoria 3052, Australia
| | - Satoshi Endo
- Laboratory of Biochemistry, Gifu Pharmaceutical University, Daigaku-Nishi, Gifu 501-1196, Japan
| | - Toshiyuki Matsunaga
- Laboratory of Biochemistry, Gifu Pharmaceutical University, Daigaku-Nishi, Gifu 501-1196, Japan
| | - Nobutada Tanaka
- School of Pharmaceutical Sciences, Showa University, Shinagawa-ku, Tokyo 142-8555, Japan
| | - Akira Hara
- Laboratory of Biochemistry, Gifu Pharmaceutical University, Daigaku-Nishi, Gifu 501-1196, Japan
| | - Ossama El-Kabbani
- Medicinal Chemistry and Drug Action, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, Victoria 3052, Australia
| |
Collapse
|
316
|
Tipparaju SM, Li XP, Kilfoil PJ, Xue B, Uversky VN, Bhatnagar A, Barski OA. Interactions between the C-terminus of Kv1.5 and Kvβ regulate pyridine nucleotide-dependent changes in channel gating. Pflugers Arch 2012; 463:799-818. [PMID: 22426702 DOI: 10.1007/s00424-012-1093-z] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2011] [Revised: 02/21/2012] [Accepted: 02/22/2012] [Indexed: 12/19/2022]
Abstract
Voltage-gated potassium (Kv) channels are tetrameric assemblies of transmembrane Kv proteins with cytosolic N- and C-termini. The N-terminal domain of Kv1 proteins binds to β-subunits, but the role of the C-terminus is less clear. Therefore, we studied the role of the C-terminus in regulating Kv1.5 channel and its interactions with Kvβ-subunits. When expressed in COS-7 cells, deletion of the C-terminal domain of Kv1.5 did not affect channel gating or kinetics. Coexpression of Kv1.5 with Kvβ3 increased current inactivation, whereas Kvβ2 caused a hyperpolarizing shift in the voltage dependence of current activation. Inclusion of NADPH in the patch pipette solution accelerated the inactivation of Kv1.5-Kvβ3 currents. In contrast, NADP(+) decreased the rate and the extent of Kvβ3-induced inactivation and reversed the hyperpolarizing shift in the voltage dependence of activation induced by Kvβ2. Currents generated by Kv1.5ΔC+Kvβ3 or Kv1.5ΔC+Kvβ2 complexes did not respond to changes in intracellular pyridine nucleotide concentration, indicating that the C-terminus is required for pyridine nucleotide-dependent interactions between Kvβ and Kv1.5. A glutathione-S-transferase (GST) fusion protein containing the C-terminal peptide of Kv1.5 did not bind to apoKvβ2, but displayed higher affinity for Kvβ2:NADPH than Kvβ2:NADP(+). The GST fusion protein also precipitated Kvβ proteins from mouse brain lysates. Pull-down experiments, structural analysis and electrophysiological data indicated that a specific region of the C-terminus (Arg543-Val583) is required for Kvβ binding. These results suggest that the C-terminal domain of Kv1.5 interacts with β-subunits and that this interaction is essential for the differential regulation of Kv currents by oxidized and reduced nucleotides.
Collapse
Affiliation(s)
- Srinivas M Tipparaju
- Department of Pharmaceutical Sciences, College of Pharmacy, University of South Florida, Tampa, FL 33612, USA.
| | | | | | | | | | | | | |
Collapse
|
317
|
Rižner TL. Enzymes of the AKR1B and AKR1C Subfamilies and Uterine Diseases. Front Pharmacol 2012; 3:34. [PMID: 22419909 PMCID: PMC3301985 DOI: 10.3389/fphar.2012.00034] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2011] [Accepted: 02/19/2012] [Indexed: 12/31/2022] Open
Abstract
Endometrial and cervical cancers, uterine myoma, and endometriosis are very common uterine diseases. Worldwide, more than 800,000 women are affected annually by gynecological cancers, as a result of which, more than 360,000 die. During their reproductive age, about 70% of women develop uterine myomas and 10-15% suffer from endometriosis. Uterine diseases are associated with aberrant inflammatory responses and concomitant increased production of prostaglandins (PG). They are also related to decreased differentiation, due to low levels of protective progesterone and retinoic acid, and to enhanced proliferation, due to high local concentrations of estrogens. The pathogenesis of these diseases can thus be attributed to disturbed PG, estrogen, and retinoid metabolism and actions. Five human members of the aldo-keto reductase 1B (AKR1B) and 1C (AKR1C) superfamilies, i.e., AKR1B1, AKR1B10, AKR1C1, AKR1C2, and AKR1C3, have roles in these processes and can thus be implicated in uterine diseases. AKR1B1 and AKR1C3 catalyze the formation of PGF2α, which stimulates cell proliferation. AKR1C3 converts PGD2 to 9α,11β-PGF2, and thus counteracts the formation of 15-deoxy-PGJ2, which can activate pro-apoptotic peroxisome-proliferator-activated receptor γ. AKR1B10 catalyzes the reduction of retinal to retinol, and thus lessens the formation of retinoic acid, with potential pro-differentiating actions. The AKR1C1-AKR1C3 enzymes also act as 17-keto- and 20-ketosteroid reductases to varying extents, and are implicated in increased estradiol and decreased progesterone levels. This review comprises an introduction to uterine diseases and AKR1B and AKR1C enzymes, followed by an overview of the current literature on the AKR1B and AKR1C expression in the uterus and in uterine diseases. The potential implications of the AKR1B and AKR1C enzymes in the pathophysiologies are then discussed, followed by conclusions and future perspectives.
Collapse
Affiliation(s)
- Tea Lanišnik Rižner
- Faculty of Medicine, Institute of Biochemistry, University of Ljubljana Ljubljana, Slovenia
| |
Collapse
|
318
|
Chen WD, Zhang Y. Regulation of aldo-keto reductases in human diseases. Front Pharmacol 2012; 3:35. [PMID: 22408622 PMCID: PMC3297832 DOI: 10.3389/fphar.2012.00035] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2011] [Accepted: 02/20/2012] [Indexed: 01/20/2023] Open
Abstract
The aldo-keto reductases (AKRs) are a superfamily of NAD(P)H-linked oxidoreductases, which reduce aldehydes and ketones to their respective primary and secondary alcohols. AKR enzymes are increasingly being recognized to play an important role in the transformation and detoxification of aldehydes and ketones generated during drug detoxification and xenobiotic metabolism. Many transcription factors have been identified to regulate the expression of human AKR genes, which could have profound effects on the metabolism of endogenous mediators and detoxication of chemical carcinogens. This review summarizes the current knowledge on AKR regulation by transcription factors and other mediators in human diseases.
Collapse
Affiliation(s)
- Wei-Dong Chen
- Department of Integrative Medical Sciences, Northeast Ohio Medical University Rootstown, OH, USA
| | | |
Collapse
|
319
|
Directly acting antivirals for hepatitis C and antiretrovirals: potential for drug-drug interactions. Curr Opin HIV AIDS 2012; 6:514-26. [PMID: 22001895 DOI: 10.1097/coh.0b013e32834b54dc] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
PURPOSE OF REVIEW Boceprevir and telaprevir are directly acting antivirals (DAAs) that have recently been licensed for treatment of hepatitis C virus (HCV) infection. Data in both untreated and previously treated patients indicate a significantly increased sustained virological response (SVR) compared with that observed with conventional therapy. However, the advent of DAA therapy poses specific challenges for HCV treatment in terms of managing drug-drug interactions (DDIs). This review aims to provide a comprehensive summary of DDI with the recently licensed DAAs, including pharmacokinetic data and current recommendations made by the manufacturers and with particular reference to antiretrovirals. Potential for DDIs with the DAAs in clinical development and the mechanisms of interaction are also discussed. RECENT FINDINGS Targeted pharmacokinetic drug interaction studies have demonstrated that both boceprevir and telaprevir are potent inhibitors of the metabolic enzyme cytochrome P4503A4, making them perpetrators of interactions with co-administered medications which are metabolized by this enzyme. In addition, co-administered medications may affect plasma levels of boceprevir and telaprevir via various mechanisms, some of which remain to be fully elucidated. SUMMARY As a result of DDIs, the concomitant use of some medicines with DAA will be contraindicated, whereas other combinations may require caution, monitoring, or dose modification of the co-administered drug. Management of DDIs with these novel agents will pose a new challenge, and prescriber awareness of the potential for DDIs is fundamental for safe prescribing. Online resources are likely to play a key role in prescriber education and clinical decision-making.
Collapse
|
320
|
Matsunaga T, Wada Y, Endo S, Soda M, El-Kabbani O, Hara A. Aldo-Keto Reductase 1B10 and Its Role in Proliferation Capacity of Drug-Resistant Cancers. Front Pharmacol 2012; 3:5. [PMID: 22319498 PMCID: PMC3269042 DOI: 10.3389/fphar.2012.00005] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2011] [Accepted: 01/11/2012] [Indexed: 12/11/2022] Open
Abstract
The human aldo–keto reductase AKR1B10, originally identified as an aldose reductase-like protein and human small intestine aldose reductase, is a cytosolic NADPH-dependent reductase that metabolizes a variety of endogenous compounds, such as aromatic and aliphatic aldehydes and dicarbonyl compounds, and some drug ketones. The enzyme is highly expressed in solid tumors of several tissues including lung and liver, and as such has received considerable interest as a relevant biomarker for the development of those tumors. In addition, AKR1B10 has been recently reported to be significantly up-regulated in some cancer cell lines (medulloblastoma D341 and colon cancer HT29) acquiring resistance toward chemotherapeutic agents (cyclophosphamide and mitomycin c), suggesting the validity of the enzyme as a chemoresistance marker. Although the detailed information on the AKR1B10-mediated mechanisms leading to the drug resistance process is not well understood so far, the enzyme has been proposed to be involved in functional regulations of cell proliferation and metabolism of drugs and endogenous lipids during the development of chemoresistance. This article reviews the current literature focusing mainly on expression profile and roles of AKR1B10 in the drug resistance of cancer cells. Recent developments of AKR1B10 inhibitors and their usefulness in restoring sensitivity to anticancer drugs are also reviewed.
Collapse
|
321
|
9,10-Phenanthrenequinone promotes secretion of pulmonary aldo-keto reductases with surfactant. Cell Tissue Res 2012; 347:407-17. [DOI: 10.1007/s00441-011-1304-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2011] [Accepted: 12/12/2011] [Indexed: 11/26/2022]
|
322
|
Kaspera R, Sahele T, Lakatos K, Totah RA. Cytochrome P450BM-3 reduces aldehydes to alcohols through a direct hydride transfer. Biochem Biophys Res Commun 2012; 418:464-8. [PMID: 22281497 DOI: 10.1016/j.bbrc.2012.01.040] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2012] [Accepted: 01/09/2012] [Indexed: 12/15/2022]
Abstract
Cytochrome P450BM-3 catalyzed the reduction of lipophilic aldehydes to alcohols efficiently. A k(cat) of ∼25 min(-1) was obtained for the reduction of methoxy benzaldehyde with wild type P450BM-3 protein which was higher than in the isolated reductase domain (BMR) alone and increased in specific P450-domain variants. The reduction was caused by a direct hydride transfer from preferentially R-NADP(2)H to the carbonyl moiety of the substrate. Weak substrate-P450-binding of the aldehyde, turnover with the reductase domain alone, a deuterium incorporation in the product from NADP(2)H but not D(2)O, and no inhibition by imidazole suggests the reductase domain of P450BM-3 as the potential catalytic site. However, increased aldehyde reduction by P450 domain variants (P450BM-3 F87A T268A) may involve allosteric or redox mechanistic interactions between heme and reductase domains. This is a novel reduction of aldehydes by P450BM-3 involving a direct hydride transfer and could have implications for the metabolism of endogenous substrates or xenobiotics.
Collapse
Affiliation(s)
- Rüdiger Kaspera
- Department of Medicinal Chemistry, University of Washington, Box 357610, Seattle, WA 98195-7610, USA
| | | | | | | |
Collapse
|
323
|
Soda M, Hu D, Endo S, Takemura M, Li J, Wada R, Ifuku S, Zhao HT, El-Kabbani O, Ohta S, Yamamura K, Toyooka N, Hara A, Matsunaga T. Design, synthesis and evaluation of caffeic acid phenethyl ester-based inhibitors targeting a selectivity pocket in the active site of human aldo-keto reductase 1B10. Eur J Med Chem 2011; 48:321-9. [PMID: 22236472 DOI: 10.1016/j.ejmech.2011.12.034] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2011] [Revised: 12/20/2011] [Accepted: 12/22/2011] [Indexed: 01/28/2023]
Abstract
Inhibitors of a human aldo-keto reductase, AKR1B10, are regarded as promising therapeutics for the treatment of cancer, but those with both high potency and selectivity compared to the structurally similar aldose reductase (AKR1B1) have not been reported. In this study, we have found that, among honeybee propolis products, caffeic acid phenethyl ester (CAPE) inhibited AKR1B10 (IC(50) = 80 nM) with 7-fold selectivity over AKR1B1. Based on a model of docked CAPE in AKR1B10, its derivatives were designed, synthesized and evaluated for inhibitory potency. Among them, 3-(4-hydroxy-2-methoxyphenyl)acrylic acid 3-(3-hydroxyphenyl)propyl ester (10c) was the most potent competitive inhibitor (K(i) = 2.6 nM) with 790-fold selectivity for AKR1B10 over AKR1B1. Molecular docking of 10c and site-directed mutagenesis of AKR1B10 residues suggested that the interactions between the 2-methoxy and 3-hydroxy groups of 10c and the enzyme's Val301 and Gln114, respectively, are important for the inhibitor's selectivity. Additionally, the sub-μM concentration of 10c significantly suppressed the farnesal metabolism and cellular proliferation in AKR1B10-overexpressing cells.
Collapse
Affiliation(s)
- Midori Soda
- Gifu Pharmaceutical University, 1-25-4 Daigaku-nishi, Gifu 501-1196, Japan
| | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
324
|
Škarydová L, Wsól V. Human microsomal carbonyl reducing enzymes in the metabolism of xenobiotics: well-known and promising members of the SDR superfamily. Drug Metab Rev 2011; 44:173-91. [DOI: 10.3109/03602532.2011.638304] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
|
325
|
Perdomo AB, Ciccosanti F, Iacono OL, Angeletti C, Corazzari M, Daniele N, Testa A, Pisa R, Ippolito G, Antonucci G, Fimia GM, Piacentini M. Liver protein profiling in chronic hepatitis C: identification of potential predictive markers for interferon therapy outcome. J Proteome Res 2011; 11:717-27. [PMID: 22098443 DOI: 10.1021/pr2006445] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The current anti-hepatitis C virus (HCV) therapy, based on pegylated-interferon alpha and ribavirin, has limited success rate and is accompanied by several side effects. The aim of this study was to identify protein profiles in pretreatment liver biopsies of HCV patients correlating with the outcome of antiviral therapy. Cytosolic or membrane/organelle-enriched protein extracts from liver biopsies of eight HCV patients were analyzed by two-dimensional fluorescence difference gel electrophoresis and mass spectrometry. Overall, this analysis identified 21 proteins whose expression levels correlate with therapy response. These factors are involved in interferon-mediated antiviral activity, stress response, and energy metabolism. Moreover, we found that post-translational modifications of dihydroxyacetone kinase were also associated with therapy outcome. Differential expression of the five best performing markers (STAT1, Mx1, DD4, DAK, and PD-ECGF) was confirmed by immunoblotting assays in an independent group of HCV patients. Finally, we showed that a prediction model based on the expression levels of these markers classifies responder and nonresponder patients with an accuracy of 85.7%. These results provide evidence that the analysis of pretreatment liver protein profiles is valuable for discriminating between responder and nonresponder HCV patients, and may contribute to reduce the number of nonresponder patients exposed to therapy-associated risks.
Collapse
|
326
|
Brunskill EW, Sequeira-Lopez MLS, Pentz ES, Lin E, Yu J, Aronow BJ, Potter SS, Gomez RA. Genes that confer the identity of the renin cell. J Am Soc Nephrol 2011; 22:2213-25. [PMID: 22034642 DOI: 10.1681/asn.2011040401] [Citation(s) in RCA: 97] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Renin-expressing cells modulate BP, fluid-electrolyte homeostasis, and kidney development, but remarkably little is known regarding the genetic regulatory network that governs the identity of these cells. Here we compared the gene expression profiles of renin cells with most cells in the kidney at various stages of development as well as after a physiologic challenge known to induce the transformation of arteriolar smooth muscle cells into renin-expressing cells. At all stages, renin cells expressed a distinct set of genes characteristic of the renin phenotype, which was vastly different from other cell types in the kidney. For example, cells programmed to exhibit the renin phenotype expressed Akr1b7, and maturing cells expressed angiogenic factors necessary for the development of the kidney vasculature and RGS (regulator of G-protein signaling) genes, suggesting a potential relationship between renin cells and pericytes. Contrary to the plasticity of arteriolar smooth muscle cells upstream from the glomerulus, which can transiently acquire the embryonic phenotype in the adult under physiologic stress, the adult juxtaglomerular cell always possessed characteristics of both smooth muscle and renin cells. Taken together, these results identify the gene expression profile of renin-expressing cells at various stages of maturity, and suggest that juxtaglomerular cells maintain properties of both smooth muscle and renin-expressing cells, likely to allow the rapid control of body fluids and BP through both contractile and endocrine functions.
Collapse
Affiliation(s)
- Eric W Brunskill
- Harrison Distinguished Professor of Pediatrics and Biology, University of Virginia, 409 Lane Road, MR4 Building, Room 2001, Charlottesville, VA 22908, USA
| | | | | | | | | | | | | | | |
Collapse
|
327
|
Aldo-keto reductase family 1, member B10 is secreted through a lysosome-mediated non-classical pathway. Biochem J 2011; 438:71-80. [PMID: 21585341 DOI: 10.1042/bj20110111] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
AKR1B10 (aldo-keto reductase family 1, member B10) protein is primarily expressed in normal human small intestine and colon, but overexpressed in several types of human cancers and considered as a tumour marker. In the present study, we found that AKR1B10 protein is secreted from normal intestinal epithelium and cultured cancer cells, as detected by a newly developed sandwich ELISA and Western blotting. The secretion of AKR1B10 was not affected by the protein-synthesis inhibitor cycloheximide and the classical protein-secretion pathway inhibitor brefeldin A, but was stimulated by temperature, ATP, Ca(2+) and the Ca(2+) carrier ionomycin, lysosomotropic NH(4)Cl, the G-protein activator GTPγS and the G-protein coupling receptor N-formylmethionyl-leucyl-phenylalanine. The ADP-ribosylation factor inhibitor 2-(4-fluorobenzoylamino)-benzoic acid methyl ester and the phospholipase C inhibitor U73122 inhibited the secretion of AKR1B10. In cultured cells, AKR1B10 was present in lysosomes and was secreted with cathepsin D, a lysosomal marker. In the intestine, AKR1B10 was specifically expressed in mature epithelial cells and secreted into the lumen at 188.6-535.7 ng/ml of ileal fluids (mean=298.1 ng/ml, n=11). Taken together, our results demonstrate that AKR1B10 is a new secretory protein belonging to a lysosome-mediated non-classical protein-secretion pathway and is a potential serum marker.
Collapse
|
328
|
Jackson P, Hougaard KS, Vogel U, Wu D, Casavant L, Williams A, Wade M, Yauk CL, Wallin H, Halappanavar S. Exposure of pregnant mice to carbon black by intratracheal instillation: toxicogenomic effects in dams and offspring. Mutat Res 2011; 745:73-83. [PMID: 22001195 DOI: 10.1016/j.mrgentox.2011.09.018] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2011] [Accepted: 09/27/2011] [Indexed: 01/05/2023]
Abstract
Exposure to nanomaterials (NM) during sensitive developmental stages may predispose organisms to diseases later in life. However, direct translocation of NM from mother to fetus through the placenta is limited. The present study tests the hypothesis that pulmonary exposure to NM and NM-induced response, such as inflammation during gestation, leads to secondary effects in the fetus. Time-mated C57BL/6BomTac mice were exposed by intratracheal instillation to vehicle (Nanopure water) or one of three concentrations (2.75, 13.5 or 67 μg in 40 μl Nanopure water) of carbon black Printex 90 (CB) on gestational days 7, 10, 15 and 18, to final cumulative doses of 11, 54 or 268 μg/animal. Samples from a subset of male and female newborns were collected on postnatal day 2 (4 days after the last maternal exposure) and from dams 26 to 27 days post-exposure (post-weaning period). Histopathology, DNA microarrays, pathway-specific RT-PCR arrays, focussed RT-PCR, and tissue protein analysis were employed to characterize pulmonary response in dams exposed to CB during pregnancy. Hepatic gene expression in newborns was interpreted in light of the observed biological responses and gene expression changes arising in the lungs of dams following CB exposure. Although retention of CB particles was observed in dams from both the medium and the high dose groups, neutrophil-marked inflammation and altered expression of several cytokines and chemokines, both at the transcriptional and tissue protein levels, was significant only in the high dose group. Analysis of newborn livers by DNA microarrays revealed that female offspring were more sensitive to maternal exposure than male offspring. Cellular signalling, inflammation, cell cycle and lipid metabolism were among the biological pathways affected in female offspring. Males, however, responded with subtle changes in metabolism-related genes. Further investigation is required to determine the long-term health consequences of the gene expression changes in offspring and response to environmental stresses.
Collapse
Affiliation(s)
- Petra Jackson
- National Research Centre for the Working Environment, Copenhagen DK-2100, Denmark
| | | | | | | | | | | | | | | | | | | |
Collapse
|
329
|
Human aldo-keto reductase AKR7A2 protects against the cytotoxicity and mutagenicity of reactive aldehydes and lowers intracellular reactive oxygen species in hamster V79-4 cells. Chem Biol Interact 2011; 195:25-34. [PMID: 22001351 DOI: 10.1016/j.cbi.2011.09.007] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2011] [Revised: 09/26/2011] [Accepted: 09/27/2011] [Indexed: 12/16/2022]
Abstract
Aldo-keto reductase (AKR) enzymes are critical for the detoxication of endogenous and exogenous aldehydes. Previous studies have shown that the AKR7A2 enzyme is catalytically active toward aldehydes arising from lipid peroxidation, suggesting a potential role against the consequences of oxidative stress, and representing an important detoxication route in mammalian cells. The aim of this study was to determine the ability of AKR7A2 to protect cells against aldehyde cytotoxicity and genotoxicity and elucidate its potential role in providing resistance to oxidative stress. A transgenic mammalian cell model was developed in which AKR7A2 was overexpressed in V79-4 cells and used to evaluate the ability of AKR7A2 to provide resistance against toxic aldehydes. Results show that AKR7A2 provides increased resistance to the cytotoxicity of 4-hydroxynonenal (HNE) and modest resistance to the cytotoxicity of trans, trans-muconaldehyde (MUC) and methyglyoxal, but provided no protection against crotonaldehyde and acrolein. Cells expressing AKR7A2 were also found to be less susceptible to DNA damage, showing a decrease in mutation rate cause by 4-HNE compared to control cells. Furthermore, the role of the AKR7A2 enzyme on the cellular capability to cope with oxidative stress was assessed. V79 cells expressing AKR7A2 were more resistant to the redox-cycler menadione and were able to lower menadione-induced ROS levels in both a time and dose dependent manner. In addition, AKR7A2 was able to maintain intracellular GSH levels in the presence of menadione. Together these findings indicate that AKR7A2 is involved in cellular detoxication pathways and may play a defensive role against oxidative stress in vivo.
Collapse
|
330
|
Ahmed MME, Wang T, Luo Y, Ye S, Wu Q, Guo Z, Roebuck BD, Sutter TR, Yang JY. Aldo-keto reductase-7A protects liver cells and tissues from acetaminophen-induced oxidative stress and hepatotoxicity. Hepatology 2011; 54:1322-32. [PMID: 21688283 DOI: 10.1002/hep.24493] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/28/2010] [Accepted: 06/01/2011] [Indexed: 12/11/2022]
Abstract
UNLABELLED Aldo-keto reductase-7A (AKR7A) is an enzyme important for bioactivation and biodetoxification. Previous studies suggested that Akr7a might be transcriptionally regulated by oxidative stress-responsive transcription factor nuclear factor erythroid 2 p45-related factor 2 (Nrf2), a protein highly responsive to acetaminophen (APAP) or its intermediate metabolite, N-acetyl-p-benzoquinoneimine (NAPQI). This study was, therefore, carried out to investigate whether Akr7a is involved in the protection against APAP-induced oxidative stress and hepatotoxicity. We found that in response to APAP or NAPQI exposure, Akr7a3 mRNA and protein were significantly up-regulated in vitro in human HepG2 and LO2 cells. Similarly, strong induction was observed for Akr7a5 in mouse AML12 hepatocytes exposed to APAP. In vivo in wild-type rats, significant up-regulation of hepatic AKR7A1 protein was observed after administration of APAP. On the other hand, depletion of Nrf2 reduced the expression of Akr7a3, suggesting that Nrf2, indeed, contributes significantly to the induction of Akr7a. Moreover, loss of cell viability in Nrf2-depleted cells was significantly rescued by coexpression of AKR7A3. Furthermore, increased AKR7A3 in HepG2 cells was associated with the up-regulation of oxidative stress-related enzymes to enhance cellular antioxidant defense, which appeared to contribute significantly to protection against APAP-induced toxicity. In a line of transgenic rats overexpressing AKR7A1, increased AKR7A1 stimulated the expression of Nrf2 and other Nrf2-regulated genes, but did not better protect rats from APAP insults. In contrast, depletion of Akr7a5 in vitro in cultured AML12 cells or depletion of Akr7a1 in vivo in rat liver greatly increased APAP-induced hepatotoxicity. CONCLUSION AKR7A proteins are significantly up-regulated in response to APAP/NAPQI exposure to contribute significantly to protection against APAP-induced hepatotoxicity. AKR7A mediates this protection, in part, through enhancing hepatocellular antioxidant defense.
Collapse
Affiliation(s)
- Munzir M E Ahmed
- State Key Laboratory of Stress Cell Biology and Department of Biomedical Sciences, School of Life Sciences, Xiamen University, Xiamen, China
| | | | | | | | | | | | | | | | | |
Collapse
|
331
|
Watanabe K. Recent reports about enzymes related to the synthesis of prostaglandin (PG) F2 (PGF2 and 9 , 11 -PGF2). J Biochem 2011; 150:593-6. [DOI: 10.1093/jb/mvr116] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
|
332
|
Lee JS, Ward WO, Liu J, Ren H, Vallanat B, Delker D, Corton JC. Hepatic xenobiotic metabolizing enzyme and transporter gene expression through the life stages of the mouse. PLoS One 2011; 6:e24381. [PMID: 21931700 PMCID: PMC3169610 DOI: 10.1371/journal.pone.0024381] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2011] [Accepted: 08/09/2011] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Differences in responses to environmental chemicals and drugs between life stages are likely due in part to differences in the expression of xenobiotic metabolizing enzymes and transporters (XMETs). No comprehensive analysis of the mRNA expression of XMETs has been carried out through life stages in any species. RESULTS Using full-genome arrays, the mRNA expression of all XMETs and their regulatory proteins was examined during fetal (gestation day (GD) 19), neonatal (postnatal day (PND) 7), prepubescent (PND32), middle age (12 months), and old age (18 and 24 months) in the C57BL/6J (C57) mouse liver and compared to adults. Fetal and neonatal life stages exhibited dramatic differences in XMET mRNA expression compared to the relatively minor effects of old age. The total number of XMET probe sets that differed from adults was 636, 500, 84, 5, 43, and 102 for GD19, PND7, PND32, 12 months, 18 months and 24 months, respectively. At all life stages except PND32, under-expressed genes outnumbered over-expressed genes. The altered XMETs included those in all of the major metabolic and transport phases including introduction of reactive or polar groups (Phase I), conjugation (Phase II) and excretion (Phase III). In the fetus and neonate, parallel increases in expression were noted in the dioxin receptor, Nrf2 components and their regulated genes while nuclear receptors and regulated genes were generally down-regulated. Suppression of male-specific XMETs was observed at early (GD19, PND7) and to a lesser extent, later life stages (18 and 24 months). A number of female-specific XMETs exhibited a spike in expression centered at PND7. CONCLUSIONS The analysis revealed dramatic differences in the expression of the XMETs, especially in the fetus and neonate that are partially dependent on gender-dependent factors. XMET expression can be used to predict life stage-specific responses to environmental chemicals and drugs.
Collapse
Affiliation(s)
- Janice S Lee
- National Health and Environmental Effects Research Laboratory, United States Environmental Protection Agency, Research Triangle Park, North Carolina, United States of America.
| | | | | | | | | | | | | |
Collapse
|
333
|
Saito R, Yamamoto H, Makino A, Sugimoto T, Miyake C. Methylglyoxal functions as Hill oxidant and stimulates the photoreduction of O(2) at photosystem I: a symptom of plant diabetes. PLANT, CELL & ENVIRONMENT 2011; 34:1454-64. [PMID: 21535016 DOI: 10.1111/j.1365-3040.2011.02344.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
We elucidated the metabolism of methylglyoxal (MG) in chloroplasts of higher plants. Spinach chloroplasts showed MG-dependent NADPH oxidation because of aldo-keto reductase (AKR) activity. K(m) for MG and V(max) of AKR activity were 6.5 mm and 3.3 µmol NADPH (mg Chl)(-1) h(-1) , respectively. Addition of MG to illuminated chloroplasts induced photochemical quenching (Qp) of Chl fluorescence, indicating that MG stimulated photosynthetic electron transport (PET). Furthermore, MG enhanced the light-dependent uptake of O(2) into chloroplasts. After illumination of chloroplasts, accumulation of H(2) O(2) was observed. K(m) for MG and V(max) of O(2) uptake were about 100 µm and 200 µmol O(2) (mg Chl)(-1) h(-1) , respectively. MG-dependent O(2) uptake was inhibited by 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) and 2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone (DBMIB). Under anaerobic conditions, the Qp of Chl fluorescence was suppressed. These results indicate that MG was reduced as a Hill oxidant by the photosystem I (PSI), and that O(2) was reduced to O(2) (-) by the reduced MG. In other words, MG produced in chloroplasts is preferentially reduced by PSI rather than through AKR. This triggers a type of oxidative stress that may be referred to as 'plant diabetes', because it ultimately originates from a common metabolite of the primary pathways of sugar anabolism and catabolism.
Collapse
Affiliation(s)
- Ryota Saito
- Department of Biological and Environmental Science, Faculty of Agriculture, Graduate School of Agricultural Science, Kobe University, 1-1 Rokkodai, Nada, Kobe 657-8501, Japan
| | | | | | | | | |
Collapse
|
334
|
Weiss M. Functional characterization of drug uptake and metabolism in the heart. Expert Opin Drug Metab Toxicol 2011; 7:1295-306. [DOI: 10.1517/17425255.2011.614233] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
|
335
|
Endo S, Matsunaga T, Fujita A, Tajima K, El-Kabbani O, Hara A. Rat aldose reductase-like protein (AKR1B14) efficiently reduces the lipid peroxidation product 4-oxo-2-nonenal. Biol Pharm Bull 2011; 33:1886-90. [PMID: 21048316 DOI: 10.1248/bpb.33.1886] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In this study, we examined the substrate specificity, inhibitor sensitivity and kinetic mechanism of a rat aldose reductase-like protein, which is named AKR1B14 in the aldo-keto reductase (AKR) superfamily. AKR1B14 catalyzed the nicotinamide adenine dinucleotide phosphate reduced form (NADPH)-dependent reduction of carbonyl compounds (derived from lipid peroxidation and glycation), xenobiotic aromatic aldehydes and some aromatic ketones. 4-Oxo-2-nonenal, the best substrate showing a K(m) value of 0.16 µM, was reduced into less reactive 4-oxo-2-nonenol, and its cytotoxicity was attenuated by the overexpression of the enzyme in cultured cells. The enzyme also showed low K(m) values (0.9-10 µM) for medium-chain aliphatic aldehydes (such as 4-hydroxynonenal, 1-hexenal and farnesal) and 3-deoxyglucosone, although the K(m) values for short-chain substrates (such as isocaproaldehyde, acrolein and methylglyoxal) were high (16-600 µM). In the reverse reaction, aliphatic and aromatic alcohols were oxidized by AKR1B14 at low rates. AKR1B14 was inhibited by aldose reductase inhibitors such as tolrestat and epalrestat, and their inhibition patterns were noncompetitive versus the aldehyde substrate and competitive with respect to the alcohol substrate. Kinetic analyses of the oxidoreduction and dead-end inhibition suggest that the reaction follows an ordered sequential mechanism.
Collapse
Affiliation(s)
- Satoshi Endo
- Laboratory of Biochemistry, Gifu Pharmaceutical University, Daigaku-Nishi, Gifu 501–1196, Japan.
| | | | | | | | | | | |
Collapse
|
336
|
Sasagawa T, Yamada T, Nakagawa T, Tsujioka T, Takahashi Y, Kawakita N, Nonaka K, Nakamura A. In vitro metabolism of dexamethasone cipecilate, a novel synthetic corticosteroid, in human liver and nasal mucosa. Xenobiotica 2011; 41:874-84. [PMID: 21657966 DOI: 10.3109/00498254.2011.582894] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Dexamethasone cipecilate (DX-CP, 9-fluoro-11β,17,21-trihydroxy-16α-methylpregna-1,4-diene-3,20-dione 21-cyclohexanecarboxylate 17-cyclopropanecarboxylate) is a novel synthetic corticosteroid used to treat allergic rhinitis. The pharmacological effect of DX-CP is considered to be mainly due to its active de-esterified metabolite (DX-17-CPC). To investigate the in vitro metabolism of DX-CP in human liver, DX-CP was incubated with human liver microsomes and S9. In addition, a metabolism study of DX-CP with human nasal mucosa was carried out in order to elucidate whether DX-17-CPC is formed in nasal mucosa, the site of action of DX-CP. DX-17-CPC was the major metabolite in both liver microsomes and S9. Two new epoxide metabolites, UK1 and UK2, were detected in liver S9, while only UK1 was detected in liver microsomes. This suggests that cytosol enzymes are responsible for the formation of UK2. In human nasal mucosa, DX-CP was mainly transformed into DX-17-CPC. By using recombinant human carboxylesterases (CESs), the reaction was shown to be catalyzed by CES2. These results provide the evidence that the active metabolite DX-17-CPC is the main contributor to the pharmacological action after the intranasal administration of DX-CP to humans.
Collapse
Affiliation(s)
- Takahiro Sasagawa
- Discovery Research Laboratories, Nippon Shinyaku Co, Ltd, Nishinosho-Monguchi-Cho, Minami-ku, Kyoto, Japan.
| | | | | | | | | | | | | | | |
Collapse
|
337
|
Shen Y, Zhong L, Johnson S, Cao D. Human aldo-keto reductases 1B1 and 1B10: a comparative study on their enzyme activity toward electrophilic carbonyl compounds. Chem Biol Interact 2011; 191:192-8. [PMID: 21329684 PMCID: PMC3103604 DOI: 10.1016/j.cbi.2011.02.004] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2010] [Revised: 01/17/2011] [Accepted: 02/08/2011] [Indexed: 12/13/2022]
Abstract
Aldo-keto reductase family 1 member B1 (AKR1B1, 1B1 in brief) and aldo-keto reductase family 1 member B10 (AKR1B10, 1B10 in brief) are two proteins with high similarities in their amino acid sequences, stereo structures, and substrate specificity. However, these two proteins exhibit distinct tissue distributions; 1B10 is primarily expressed in the gastrointestinal tract and adrenal gland, whereas 1B1 is ubiquitously present in all tissues/organs, suggesting their difference in biological functions. This study evaluated in parallel the enzyme activity of 1B1 and 1B10 toward alpha, beta-unsaturated carbonyl compounds with cellular and dietary origins, including acrolein, crotonaldehyde, 4-hydroxynonenal, trans-2-hexenal, and trans-2,4-hexadienal. Our results showed that 1B10 had much better enzyme activity and turnover rates toward these chemicals than 1B1. By detecting the enzymatic products using high-performance liquid chromatography, we measured their activity to carbonyl compounds at low concentrations. Our data showed that 1B10 efficiently reduced the tested carbonyl compounds at physiological levels, but 1B1 was less effective. Ectopically expressed 1B10 in 293T cells effectively eliminated 4-hydroxynonenal at 5 μM by reducing to 1,4-dihydroxynonene, whereas endogenously expressed 1B1 did not. The 1B1 and 1B10 both showed enzyme activity to glutathione-conjugated carbonyl compounds, but 1B1 appeared more active in general. Together our data suggests that 1B10 is more effectual in eliminating free electrophilic carbonyl compounds, but 1B1 seems more important in the further detoxification of glutathione-conjugated carbonyl compounds.
Collapse
Affiliation(s)
- Yi Shen
- Department of Medical Microbiology, Immunology, & Cell Biology, Simmons Cancer Institute, Southern Illinois University School of Medicine. 913 N. Rutledge Street, Springfield, IL 62794
| | - Linlin Zhong
- Department of Medical Microbiology, Immunology, & Cell Biology, Simmons Cancer Institute, Southern Illinois University School of Medicine. 913 N. Rutledge Street, Springfield, IL 62794
| | - Stephen Johnson
- Carbon Dynamics Institute, LLC, 2835 via Verde Drive, Springfield, IL 62703-4325
| | - Deliang Cao
- Department of Medical Microbiology, Immunology, & Cell Biology, Simmons Cancer Institute, Southern Illinois University School of Medicine. 913 N. Rutledge Street, Springfield, IL 62794
| |
Collapse
|
338
|
Takemura M, Endo S, Matsunaga T, Soda M, Zhao HT, El-Kabbani O, Tajima K, Iinuma M, Hara A. Selective inhibition of the tumor marker aldo-keto reductase family member 1B10 by oleanolic acid. JOURNAL OF NATURAL PRODUCTS 2011; 74:1201-6. [PMID: 21561086 DOI: 10.1021/np200118q] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
A human member of the aldo-keto reductase (AKR) superfamily, AKR1B10, was recently suggested as a therapeutic target in the treatment of several types of cancer. Due to its high sequence identity with human aldose reductase (AKR1B1), selective inhibition of AKR1B10 compared with AKR1B1 is required for the development of anticancer agents. In this study, we have examined AKR1B10 inhibition by seven pentacyclic triterpenes (1-7) that show potential anticancer properties. Among them, oleanolic acid (1) was found to be the most potent competitive inhibitor (inhibition constant, 72 nM) with the highest AKR1B10/AKR1B1 selectivity ratio of 1370. Molecular docking of 1 with AKR1B10 and AKR1B1 and site-directed mutagenesis studies suggested that the nonconserved residues Val301 and Gln303 in AKR1B10 are important for determining its inhibitory potency and selectivity. Oleanolic acid (1) also inhibited the cellular metabolism by AKR1B10 (IC(50), 4 μM) and decreased mitomycin C tolerance of colon cancer HT29 cells. Thus, the selective and potent inhibition of AKR1B10 by 1 may be related to a possible cancer inhibitory role.
Collapse
Affiliation(s)
- Mayuko Takemura
- Laboratory of Biochemistry, Gifu Pharmaceutical University, Gifu 501-1196, Japan
| | | | | | | | | | | | | | | | | |
Collapse
|
339
|
Zhong L, Shen H, Huang C, Jing H, Cao D. AKR1B10 induces cell resistance to daunorubicin and idarubicin by reducing C13 ketonic group. Toxicol Appl Pharmacol 2011; 255:40-7. [PMID: 21640744 DOI: 10.1016/j.taap.2011.05.014] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2011] [Revised: 05/13/2011] [Accepted: 05/15/2011] [Indexed: 12/12/2022]
Abstract
Daunorubicin, idarubicin, doxorubicin and epirubicin are anthracyclines widely used for the treatment of lymphoma, leukemia, and breast, lung, and liver cancers, but tumor resistance limits their clinical success. Aldo-keto reductase family 1 B10 (AKR1B10) is an NADPH-dependent enzyme overexpressed in liver and lung carcinomas. This study was aimed to determine the role of AKR1B10 in tumor resistance to anthracyclines. AKR1B10 activity toward anthracyclines was measured using recombinant protein. Cell resistance to anthracycline was determined by ectopic expression of AKR1B10 or inhibition by epalrestat. Results showed that AKR1B10 reduces C13-ketonic group on side chain of daunorubicin and idarubicin to hydroxyl forms. In vitro, AKR1B10 converted daunorubicin to daunorubicinol at V(max) of 837.42±81.39nmol/mg/min, K(m) of 9.317±2.25mM and k(cat)/K(m) of 3.24. AKR1B10 showed better catalytic efficiency toward idarubicin with V(max) at 460.23±28.12nmol/mg/min, K(m) at 0.461±0.09mM and k(cat)/K(m) at 35.94. AKR1B10 was less active toward doxorubicin and epirubicin with a C14-hydroxyl group. In living cells, AKR1B10 efficiently catalyzed reduction of daunorubicin (50nM) and idarubicin (30nM) to corresponding alcohols. Within 24h, approximately 20±2.7% of daunorubicin (1μM) or 23±2.3% of idarubicin (1μM) was converted to daunorubicinol or idarubicinol in AKR1B10 expression cells compared to 7±0.9% and 5±1.5% in vector control. AKR1B10 expression led to cell resistance to daunorubicin and idarubicin, but inhibitor epalrestat showed a synergistic role with these agents. Together our data suggest that AKR1B10 participates in cellular metabolism of daunorubicin and idarubicin, resulting in drug resistance. These data are informative for the clinical use of idarubicin and daunorubicin.
Collapse
Affiliation(s)
- Linlin Zhong
- Department of Medical Microbiology, Immunology, & Cell Biology, Simmons Cancer Institute, Southern Illinois University School of Medicine, 913 N. Rutledge Street, Springfield, IL 62794-9626, USA
| | | | | | | | | |
Collapse
|
340
|
Endo S, Matsunaga T, Fujita A, Kuragano T, Soda M, Sundaram K, Dhagat U, Tajima K, El-Kabbani O, Hara A. Activation of aldo-keto reductase family member 1B14 (AKR1B14) by bile acids: Activation mechanism and bile acid-binding site. Biochimie 2011; 93:1476-86. [PMID: 21586312 DOI: 10.1016/j.biochi.2011.04.022] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2011] [Accepted: 04/29/2011] [Indexed: 11/30/2022]
Abstract
Aldo-keto reductase (AKR) 1B14, a rat ortholog of mouse androgen-dependent vas deferens protein (AKR1B7), is involved in the synthesis of prostaglandin F(2α) and detoxification of 4-oxononenal formed by lipid peroxidation. The NADPH-linked reductase activity of AKR1B14 was activated by various bile acids. Although the activation was increased by decreasing pH from 9.0 to 6.0, the concentrations giving maximum stimulation (2- to 18-fold) were 0.2-6.0 μM for bile acids at pH 7.4. Kinetic analyses of the activation by glycochenodeoxycholic acid in the forward and reverse reactions, together with fluorescence changes and protection against 4-oxononenal-induced inactivation by bile acid, indicate that the bile acid binds to the enzyme and its coenzyme binary complex as a non-essential activator. The bile acid binding to AKR1B14 mainly accelerates the NADP(+) dissociation, the rate-limited step of the enzyme reaction. AKR1B7 was also activated by bile acids, but the activation was low and independent of pH. The mutagenesis of His269 and Leu267 of AKR1B14 into the corresponding residues (Arg and Pro, respectively) of AKR1B7 resulted in low and pH-independent activation by bile acids. The results, together with the docking of the bile acid in the recently determined crystal structure of AKR1B14, identify the bile acid-binding site of which His269 plays a key role in significant activation through its electrostatic interaction with the carboxyl group of bile acid, facilitating the release of NADP(+).
Collapse
Affiliation(s)
- Satoshi Endo
- Laboratory of Biochemistry, Gifu Pharmaceutical University, 1-25-4 Daigaku-Nishi, Gifu 501-1196, Japan.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
341
|
El-Kabbani O, Dhagat U, Hara A. Inhibitors of human 20α-hydroxysteroid dehydrogenase (AKR1C1). J Steroid Biochem Mol Biol 2011; 125:105-11. [PMID: 21050889 DOI: 10.1016/j.jsbmb.2010.10.006] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/30/2010] [Revised: 10/11/2010] [Accepted: 10/23/2010] [Indexed: 12/13/2022]
Abstract
Human 20α-hydroxysteroid dehydrogenase (AKR1C1), a member of the aldo-keto reductase (AKR) superfamily, is one of four isoforms (with >84% amino acid sequence identity) existing in human tissues. AKR1C1 most efficiently reduces biologically active progesterone and 5α-pregnan-3α-ol-20-one into their corresponding 20α-hydroxysteroids among the isoforms. The enzyme also accepts endogenous and xenobiotic non-steroidal carbonyl compounds as the substrates. In addition to the up-regulation of the AKR1C1 gene in cancer cells, the enzyme's over-expression in the cells of lung, ovary, uterine cervix, skin and colon carcinomas was reported to be associated with resistance against several anticancer agents. Thus, AKR1C1 may be a marker of the above cancers and a target of poor prognosis in cancer therapy. The recently determined X-ray crystal structures of AKR1C1/NADP(+)/20α-hydroxyprogesterone and AKR1C1/NADP(+)/3,5-dichlorosalicylic acid ternary complexes have provided a strong foundation for structure-based design methods to improve inhibitor selectivity and potency. In this review we provide an overview of the different types of AKR1C1 inhibitors and an update on the design of potent and selective inhibitors based on the crystal structure of the enzyme-inhibitor complex. Article from the Special issue on Targeted Inhibitors.
Collapse
Affiliation(s)
- Ossama El-Kabbani
- Medicinal Chemistry and Drug Action, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, Victoria 3052, Australia.
| | | | | |
Collapse
|
342
|
Skarka A, Škarydová L, Štambergová H, Wsól V. Anthracyclines and their metabolism in human liver microsomes and the participation of the new microsomal carbonyl reductase. Chem Biol Interact 2011; 191:66-74. [DOI: 10.1016/j.cbi.2010.12.016] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2010] [Revised: 12/15/2010] [Accepted: 12/16/2010] [Indexed: 01/24/2023]
|
343
|
Ma J, Cao D. Human aldo-keto reductases: structure, substrate specificity and roles in tumorigenesis. Biomol Concepts 2011; 2:115-26. [PMID: 25962023 DOI: 10.1515/bmc.2011.010] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
The aldo-keto reductase (AKR) superfamily consists of over 150 protein members sharing similar structure and enzymatic activities. To date, 13 human AKRs have been identified, and they participate in xenobiotic detoxification, biosynthesis and metabolism. Increasing evidence suggests the involvement of human AKR proteins in cancer development, progression and treatment. Some proteins demonstrate multiple functional features in addition to being a reductase for carbonyl groups. This review article discusses the most recent progress made in the study of humans AKRs.
Collapse
|
344
|
Joshi A, Rajput S, Wang C, Ma J, Cao D. Murine aldo-keto reductase family 1 subfamily B: identification of AKR1B8 as an ortholog of human AKR1B10. Biol Chem 2011; 391:1371-8. [PMID: 21087085 DOI: 10.1515/bc.2010.144] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Aldo-keto reductase family 1 member B10 (AKR1B10), over-expressed in multiple human cancers, might be implicated in cancer development and progression via detoxifying cytotoxic carbonyls and regulating fatty acid synthesis. In the present study, we investigated the ortholog of AKR1B10 in mice, an ideal modeling organism greatly contributing to human disease investigations. In the mouse, there are three aldo-keto reductase family 1 subfamily B (AKR1B) members, i.e., AKR1B3, AKR1B7, and AKR1B8. Among them, AKR1B8 has the highest similarity to human AKR1B10 in terms of amino acid sequence, computer-modeled structures, substrate spectra and specificity, and tissue distribution. More importantly, similar to human AKR1B10, mouse AKR1B8 associates with murine acetyl-CoA carboxylase-α and mediates fatty acid synthesis in colon cancer cells. Taken together, our data suggest that murine AKR1B8 is the ortholog of human AKR1B10.
Collapse
Affiliation(s)
- Amit Joshi
- Department of Medical Microbiology, Immunology and Cell Biology, Simmons Cooper Cancer Institute, Southern Illinois University School of Medicine, Springfield, IL 62794, USA
| | | | | | | | | |
Collapse
|
345
|
Leclerc J, Courcot-Ngoubo Ngangue E, Cauffiez C, Allorge D, Pottier N, Lafitte JJ, Debaert M, Jaillard S, Broly F, Lo-Guidice JM. Xenobiotic metabolism and disposition in human lung: transcript profiling in non-tumoral and tumoral tissues. Biochimie 2011; 93:1012-27. [PMID: 21376776 DOI: 10.1016/j.biochi.2011.02.012] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2010] [Accepted: 02/22/2011] [Indexed: 11/30/2022]
Abstract
The lung is directly exposed to a wide variety of inhaled toxicants and carcinogens. In order to improve our knowledge of the cellular processing of these compounds in the respiratory tract, we investigated the mRNA expression level of 380 genes encoding xenobiotic-metabolizing enzymes (XME), transporters, nuclear receptors and transcription factors, in pulmonary parenchyma (PP), bronchial mucosa (BM) and tumoral lung tissues from 12 patients with non-small cell lung cancer (NSCLC). Using a high throughput quantitative real-time RT-PCR method, we found that ADH1B, CYP4B1, CES1 and GSTP1 are the major XME genes expressed both in BM and PP. Our results also documented the predominant role played by the xenosensor AhR in human lung. The gene expression profiles were different for BM and PP, with a tendency toward increased mRNA levels of phase I and phase II XME genes in BM, suggesting major differences in the initial stages of xenobiotic metabolism. Some of the significantly overexpressed genes in BM (i.e. CYP2F1, CYP2A13, CYP2W1, NQO1…) encode proteins involved in the bioactivation of procarcinogens, pointing out distinct susceptibility to xenobiotics and their toxic effects between these two tissue types. Additionally, interindividual differences in transcript levels observed for some genes may be of genetic origin and may contribute to the variability in response to environmental exposure and, consequently, in the risk of developing lung diseases. A global decrease in gene expression was observed in tumoral specimens. Some of the proteins are involved in the metabolism or transport of anti-cancer drugs and their influence in the response of tumors to chemotherapy should be considered. In conclusion, the present study provides an overview of the cellular response to toxicants and drugs in healthy and cancerous human lung tissues, and thus improves our understanding of the mechanisms of chemical carcinogenesis as well as cellular resistance to chemotherapy.
Collapse
Affiliation(s)
- Julie Leclerc
- Equipe d'accueil EA4483, Faculté de Médecine Pôle Recherche, Université Lille Nord de France, 1 Place de Verdun, 59045 Lille, France.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
346
|
Human and rodent aldo-keto reductases from the AKR1B subfamily and their specificity with retinaldehyde. Chem Biol Interact 2011; 191:199-205. [PMID: 21329680 DOI: 10.1016/j.cbi.2011.02.007] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2010] [Revised: 02/01/2011] [Accepted: 02/02/2011] [Indexed: 11/21/2022]
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 k(cat) 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.
Collapse
|
347
|
Xie Z, Barski OA, Cai J, Bhatnagar A, Tipparaju SM. Catalytic reduction of carbonyl groups in oxidized PAPC by Kvβ2 (AKR6). Chem Biol Interact 2011; 191:255-60. [PMID: 21296056 DOI: 10.1016/j.cbi.2011.01.032] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2010] [Revised: 01/28/2011] [Accepted: 01/28/2011] [Indexed: 11/15/2022]
Abstract
The β-subunits of the voltage-gated potassium channel (Kvβ) belong to the aldo-keto reductase superfamily. The Kvβ-subunits dock with the pore-forming Kv α-subunits and impart or accelerate the rate of inactivation in Kv channels. Inactivation of Kv currents by Kvβ is differentially regulated by oxidized and reduced pyridine nucleotides. In mammals, AKR6 family is comprised of 3 different genes Kvβ1-3. We have shown previously that Kvβ2 catalyzes the reduction of a broad range of carbonyls including aromatic carbonyls, electrophilic aldehydes and prostaglandins. However, the endogenous substrates for Kvβ have not been identified. To determine whether products of lipid oxidation are substrates of Kvβs, we tested the enzymatic activity of Kvβ2 with oxidized phospholipids generated during the oxidation of 1-palmitoyl-2-arachidonoyl-sn-glycero-3-phosphocholine (PAPC). Electrospray ionization mass spectrometric analysis showed that Kvβ2 catalyzed the NADPH-dependent reduction of several products of oxPAPC, including 1-palmitoyl-2-(5-oxovaleroyl)-sn-glycero-3-phosphorylcholine (POVPC), 1-palmitoyl-2-(epoxycyclopentenone)-sn-glycero-3-phosphorylcholine (PECPC), 1-palmitoyl-2-(5,6)- epoxyisoprostane E2-sn-glycero-3-phosphocholine (PEIPC). These results were validated using high resolution mass spectrometric analysis. Time course analysis revealed that the reduced products reached significant levels for ions at m/z 594/596 (POVPC/PHVPC), 810/812 (PECPC/2H-PECPC) and 828/830 (PEIPC/2H-PEIPC) in the oxPAPC+Kvβ2 mixture (p<0.01). These results suggest that Kvβ could serve as a sensor of lipid oxidation via its catalytic activity and thereby alter Kv currents under conditions of oxidative stress.
Collapse
Affiliation(s)
- Zhengzhi Xie
- Diabetes and Obesity Center, University of Louisville, Louisville, KY 40202, United States
| | | | | | | | | |
Collapse
|
348
|
Chatzopoulou M, Mamadou E, Juskova M, Koukoulitsa C, Nicolaou I, Stefek M, Demopoulos VJ. Structure–activity relations on [1-(3,5-difluoro-4-hydroxyphenyl)-1H-pyrrol-3-yl]phenylmethanone. The effect of methoxy substitution on aldose reductase inhibitory activity and selectivity. Bioorg Med Chem 2011; 19:1426-33. [DOI: 10.1016/j.bmc.2011.01.009] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2010] [Revised: 12/29/2010] [Accepted: 01/05/2011] [Indexed: 12/21/2022]
|
349
|
Salabei JK, Li XP, Petrash JM, Bhatnagar A, Barski OA. Functional expression of novel human and murine AKR1B genes. Chem Biol Interact 2011; 191:177-84. [PMID: 21276782 DOI: 10.1016/j.cbi.2011.01.020] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2010] [Revised: 01/12/2011] [Accepted: 01/19/2011] [Indexed: 02/05/2023]
Abstract
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.
Collapse
Affiliation(s)
- Joshua K Salabei
- Diabetes and Obesity Center, School of Medicine, University of Louisville, Louisville, KY 40202, United States
| | | | | | | | | |
Collapse
|
350
|
Alzeer S, Ellis EM. The role of aldehyde reductase AKR1A1 in the metabolism of γ-hydroxybutyrate in 1321N1 human astrocytoma cells. Chem Biol Interact 2011; 191:303-7. [PMID: 21276435 DOI: 10.1016/j.cbi.2011.01.018] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2010] [Revised: 01/18/2011] [Accepted: 01/19/2011] [Indexed: 12/18/2022]
Abstract
The role of the aldehyde reductase AKR1A1 in the biosynthesis of gamma-hydroxybutyrate (GHB) has been investigated in cell lines using a specific double stranded siRNA designed to knock down expression of the enzyme. This enzyme, along with the aldo-keto reductase AKR7A2, has been proposed previously to be one of the major succinic semialdehyde reductases in brain. The AKR1A1 siRNA was introduced into the human astrocytoma cell line (1321N1) and AKR1A1 expression was monitored using quantitative reverse-transcriptase PCR and Western blots. Results show an 88% reduction in mRNA levels and a 94% reduction in AKR1A1 protein expression 72 h after transfection with the siRNA. Aldehyde reductase activity was examined in silenced cells by following the aldehyde-dependent conversion of NADPH to NADP at 340 nm. This revealed a 30% decrease in pNBA reductase activity in cell extracts after AKR1A1 silencing. Succinic semialdehyde reductase activity was significantly lower in silenced cells when measured using high concentrations (1mM) of succinic semialdehyde, but not with low concentrations (10 μM). The effect of silencing on intracellular and extracellular GHB levels was measured using gas chromatography-mass spectrometry. Results show that AKR1A1 has little effect on the production of GHB, indicating that in this cell line alternative enzymes such as the AKR7A2 are likely to play a more significant role in GHB biosynthesis.
Collapse
Affiliation(s)
- Samar Alzeer
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, United Kingdom
| | | |
Collapse
|