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Comparative Evaluation of Aldose Reductase Inhibition in Polycystic Ovarian Syndrome-Induced Rats. Reprod Sci 2023; 30:622-632. [PMID: 35930177 DOI: 10.1007/s43032-022-01039-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Accepted: 07/12/2022] [Indexed: 10/16/2022]
Abstract
Polycystic ovary syndrome (PCOS) represents a spectrum of disorders, associated with hyperandrogenism, oligoanovulation, and polycystic ovaries. Aldose reductase (AR), a rate-limiting enzyme of polyol pathway, is responsible for maintenance of intracellular osmotic balance, facilitation of oocyte development, and organization of the granulosa cells in the ovary. Cyclic changes in the aldose reductase level were found during the 4-5 days estrus cycle in rat, which is regulated by gonadotropin-releasing hormone (GnRH). Irregular GnRH secretion in PCOS patients may lead to altered aldose reductase expression and ovarian dysfunction. Treatment with a novel AR inhibitor, fidarestat, has been reported to improve erythrocyte sorbitol content in diabetic patients. Hence, the potential role AR in pathogenesis of PCOS was investigated by inhibiting AR with fidarestat in PCOS-induced rats. Pre-pubertal female Sprague-Dawley rats were divided into five groups. PCOS is induced either by administering letrozole or by feeding high-fat diet for 90 days. After induction of PCOS, fidarestat treatment was given for 28 days and various parameters were measured. In PCOS-induced rats, parameters like food intake, body weight, insulin, OGTT, triglycerides, cholesterol, prolonged diestrus phase, ovary weight, and immunohistological localization AR were found to be significantly altered. Fidarestat treatment significantly improved ovary weight, ovarian aldose reductase localization in PCOS-induced rats. Improvement in all these parameters suggest involvement of aldose reductase in the pathogenesis of PCOS.
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Wang YC, Ma YD, Liu H, Cui ZH, Zhao D, Zhang XQ, Zhang LX, Guo WJ, Long Y, Tu SS, Yuan DZ, Zhang JH, Wang BK, Xu LZ, Shen QY, Wang Y, Nie L, Yue LM. Hyperandrogen-induced polyol pathway flux increase affects ovarian function in polycystic ovary syndrome via excessive oxidative stress. Life Sci 2023; 313:121224. [PMID: 36435224 DOI: 10.1016/j.lfs.2022.121224] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Revised: 11/10/2022] [Accepted: 11/21/2022] [Indexed: 11/25/2022]
Abstract
AIMS Polycystic ovary syndrome (PCOS) is a common endocrine disorder in the women of childbearing age. It is characterized by hyperandrogenism and abnormal follicular growth and ovulation. The polyol pathway is a glucose metabolism bypass pathway initiated by aldose reductase (ADR). Androgen induces the expression of ADR in the male reproductive tract, which has a general physiological significance for male reproductive function. Here we investigate whether hyperandrogenemia in PCOS leads to increased flux of the polyol pathway in ovarian tissue, which in turn affects follicular maturation and ovulation through oxidative stress. MAIN METHODS We used clinical epidemiological methods to collect serum and granulosa cells from clinical subjects for a clinical case-control study. At the same time, cell biology and molecular biology techniques were used to conduct animal and cell experiments to further explore the mechanism of hyperandrogen-induced ovarian polyol pathway hyperactivity and damage to ovarian function. KEY FINDINGS Here, we find that hyperandrogenism of PCOS can induce the expression of ovarian aldose reductase, which leads to the increase of the polyol pathway flux, and affects ovarian function through excessive oxidative stress. SIGNIFICANCE Our research has enriched the pathological mechanism of PCOS and may provide a new clue for the clinical treatment of PCOS.
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Affiliation(s)
- Yi-Cheng Wang
- Department of Physiology, West China School of Basic Medical Sciences and Forensic Medicine, Sichuan University, Chengdu 610041, Sichuan, China; Department of Reproductive Health and Infertility, Chengdu Women's and Children's Central Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu 611731, Sichuan, China
| | - Yong-Dan Ma
- Department of Physiology, West China School of Basic Medical Sciences and Forensic Medicine, Sichuan University, Chengdu 610041, Sichuan, China
| | - Huan Liu
- Department of Physiology, West China School of Basic Medical Sciences and Forensic Medicine, Sichuan University, Chengdu 610041, Sichuan, China
| | - Zhi-Hui Cui
- Department of Physiology, West China School of Basic Medical Sciences and Forensic Medicine, Sichuan University, Chengdu 610041, Sichuan, China
| | - Dan Zhao
- Department of Physiology, West China School of Basic Medical Sciences and Forensic Medicine, Sichuan University, Chengdu 610041, Sichuan, China
| | - Xue-Qin Zhang
- Department of Physiology, West China School of Basic Medical Sciences and Forensic Medicine, Sichuan University, Chengdu 610041, Sichuan, China
| | - Li-Xue Zhang
- Department of Physiology, West China School of Basic Medical Sciences and Forensic Medicine, Sichuan University, Chengdu 610041, Sichuan, China
| | - Wen-Jing Guo
- Department of Physiology, West China School of Basic Medical Sciences and Forensic Medicine, Sichuan University, Chengdu 610041, Sichuan, China
| | - Yun Long
- Department of Physiology, West China School of Basic Medical Sciences and Forensic Medicine, Sichuan University, Chengdu 610041, Sichuan, China
| | - Sha-Sha Tu
- Department of Physiology, West China School of Basic Medical Sciences and Forensic Medicine, Sichuan University, Chengdu 610041, Sichuan, China
| | - Dong-Zhi Yuan
- Department of Physiology, West China School of Basic Medical Sciences and Forensic Medicine, Sichuan University, Chengdu 610041, Sichuan, China; Reproductive Endocrinology and Regulation Joint Laboratory, West China Second Hospital, Sichuan University, Chengdu 610041, Sichuan, China
| | - Jin-Hu Zhang
- Department of Physiology, West China School of Basic Medical Sciences and Forensic Medicine, Sichuan University, Chengdu 610041, Sichuan, China; Reproductive Endocrinology and Regulation Joint Laboratory, West China Second Hospital, Sichuan University, Chengdu 610041, Sichuan, China
| | - Bing-Kun Wang
- Reproductive Endocrinology and Regulation Joint Laboratory, West China Second Hospital, Sichuan University, Chengdu 610041, Sichuan, China
| | - Liang-Zhi Xu
- Reproductive Endocrinology and Regulation Joint Laboratory, West China Second Hospital, Sichuan University, Chengdu 610041, Sichuan, China
| | - Qiong-Yan Shen
- Reproductive Medicine Center, West China Second Hospital, Sichuan University, Chengdu 610041, Sichuan, China
| | - Yan Wang
- Reproductive Medicine Center, West China Second Hospital, Sichuan University, Chengdu 610041, Sichuan, China
| | - Li Nie
- Department of Physiology, West China School of Basic Medical Sciences and Forensic Medicine, Sichuan University, Chengdu 610041, Sichuan, China; Reproductive Endocrinology and Regulation Joint Laboratory, West China Second Hospital, Sichuan University, Chengdu 610041, Sichuan, China.
| | - Li-Min Yue
- Department of Physiology, West China School of Basic Medical Sciences and Forensic Medicine, Sichuan University, Chengdu 610041, Sichuan, China; Reproductive Endocrinology and Regulation Joint Laboratory, West China Second Hospital, Sichuan University, Chengdu 610041, Sichuan, China.
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Tao J, Zhao G, Zhao X, Li F, Wu X, Hu J, Zhang Y. Proteomic analysis of the follicular fluid of Tianzhu white yak during diestrus. Int J Mol Sci 2014; 15:4481-91. [PMID: 24633201 PMCID: PMC3975409 DOI: 10.3390/ijms15034481] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2014] [Revised: 02/28/2014] [Accepted: 03/10/2014] [Indexed: 12/23/2022] Open
Abstract
The aim of this study was to identify differentially expressed proteins in the follicular fluid of Tianzhu white yak during diestrus. Follicles obtained from female yak were divided into four groups according to their diameter: 0–2, 2–4, 4–6 mm, and greater than 6 mm. The follicular fluid was directly aspirated from the follicles and mixed according to follicular size, and two-dimensional gel electrophoresis was carried out on the crude follicular fluid samples. Thirty-four differentially expressed spots were generated from these four sizes of follicles. Fourteen of these spots were analyzed by MALDI-TOF/TOF-MS and identified as: AS3MT, VDP, ANKRD6, C10orf107 protein, MRP4, MAPKAP1, AGO3, profilin-β-actin, SPT2 homolog, AGP, AR, RNF20, obscurin-like-1, and one unnamed protein. These proteins were first reported in follicular fluid, in addition to VDP and AGP. Based on existing knowledge of their function and patterns of expression, we hypothesize that most of these differentially expressed proteins play a role in ovarian follicular growth and development, dominant follicle selection, or follicular atresia and development of oocytes; however, the function of the other differentially expressed proteins in reproduction remains ambiguous.
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Affiliation(s)
- Jinzhong Tao
- Agricultural College, Ningxia University, Yinchuan 750021, China.
| | - Guoshun Zhao
- College of Veterinary Medicine, Gansu Agricultural University, Lanzhou 730070, China.
| | - Xingxu Zhao
- College of Veterinary Medicine, Gansu Agricultural University, Lanzhou 730070, China.
| | - Fadi Li
- College of Animal Science and Technology, Gansu Agricultural University, Lanzhou 730070, China.
| | - Xiaohu Wu
- College of Veterinary Medicine, Gansu Agricultural University, Lanzhou 730070, China.
| | - Junjie Hu
- College of Veterinary Medicine, Gansu Agricultural University, Lanzhou 730070, China.
| | - Yong Zhang
- College of Veterinary Medicine, Gansu Agricultural University, Lanzhou 730070, China.
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Józwik M, Józwik M, Teng C, Battaglia FC. Concentrations of monosaccharides and their amino and alcohol derivatives in human preovulatory follicular fluid. Mol Hum Reprod 2007; 13:791-6. [PMID: 17766681 DOI: 10.1093/molehr/gam060] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The study purpose was to compare sugar and polyol concentrations in preovulatory ovarian follicular fluid (FF) with those in the circulation. Samples of FF and peripheral venous blood were obtained after an overnight fast from 14 women attending an IVF program. High performance liquid chromatography measurements of seven polyols, two aminohexoses and four hexoses were the main outcome measures. Glucose concentrations in FF and plasma were 2781.26 +/- 205.64 and 4431.25 +/- 65.17 microM, respectively (P < 0.001). Mannose concentration in FF was 38.99 +/- 3.33 microM, significantly lower than plasma concentration (55.38 +/- 2.29 microM; P < 0.001). A concentration gradient from plasma to FF was also significant for glycerol (99.41 +/- 8.47 versus 74.32 +/- 6.54 microM; P < 0.002), galactose (31.69 +/- 1.58 versus 26.73 +/- 1.93 microM; P < 0.01) and galactosamine (11.49 +/- 0.69 versus 6.38 +/- 0.59 microM; P < 0.001). The plasma-to-FF concentration difference was greatest for glucose (1649.99 +/- 204.09 microM). There was a significant correlation between plasma and FF concentrations for galactose and glycerol. This study supports a substantial utilization of glucose by the oocyte/granulosa cells complex, and documents a significant concentration gradient from plasma to FF for glycerol, mannose, galactose and galactosamine. These plasma-FF differences may reflect both utilization of these carbohydrates by the cells of the preovulatory ovarian follicle and/or transport characteristics of these cells.
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Affiliation(s)
- Maciej Józwik
- Department of Gynecology, Medical University of Bialystok, Sklodowskiej 24 A, 15-276 Bialystok, Poland.
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Lee J, Chung BC. Simultaneous measurement of urinary polyols using gas chromatography/mass spectrometry. J Chromatogr B Analyt Technol Biomed Life Sci 2006; 831:126-31. [PMID: 16356788 DOI: 10.1016/j.jchromb.2005.11.043] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2005] [Revised: 11/24/2005] [Accepted: 11/29/2005] [Indexed: 10/25/2022]
Abstract
In the present study, we simultaneously measured several polyols, such as adonitol, arabitol, dulcitol, glucose, myo-inositol, mannitol, sorbitol, and xylitol, in urine by gas chromatography/mass spectrometry-positive chemical ionization. We also examined possible relationship between the levels of these metabolites and age in normal individuals. In order to proceed to its quantification by GC/MS, 200 microL of a urine sample were diluted with 3 ml of distilled water, lyophilized, acetylated, and then analyzed them. Using this method, we were able to quantify as little as 0.5-1.0 ng/microL, and we made the calibration curves to be linear from 0.25 to 250 ng/microL (r(2)>0.991). Analytical recoveries were over 89.4%, and the inter-day and intra-day variability for accuracy and reproducibility was less than 20%. In the normal urine sample, the levels of polyols were gender-differentiated and age-related. This simple GC/MS method is sensitive and allows the measurement of wide ranges of polyols using small amounts of urine. We conclude that the quantitation of urinary polyols using GC/MS appears to be a clinically useful method for assessing polyol-pathway activity.
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Affiliation(s)
- Jeongae Lee
- Bioanalysis and Biotransformation Research Center, Korea Institute of Science and Technology, Haweolgok-Dong 39-1, Sungbuk-Ku, Seoul 136-791, Republic of Korea
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Fujii J, Iuchi Y, Okada F. Fundamental roles of reactive oxygen species and protective mechanisms in the female reproductive system. Reprod Biol Endocrinol 2005; 3:43. [PMID: 16137335 PMCID: PMC1224869 DOI: 10.1186/1477-7827-3-43] [Citation(s) in RCA: 176] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/28/2005] [Accepted: 09/02/2005] [Indexed: 01/21/2023] Open
Abstract
Controlled oxidation, such as disulfide bond formation in sperm nuclei and during ovulation, plays a fundamental role in mammalian reproduction. Excess oxidation, however, causes oxidative stress, resulting in the dysfunction of the reproductive process. Antioxidation reactions that reduce the levels of reactive oxygen species are of prime importance in reproductive systems in maintaining the quality of gametes and support reproduction. While anti-oxidative enzymes, such as superoxide dismutase and peroxidase, play a central role in eliminating oxidative stress, reduction-oxidation (redox) systems, comprised of mainly glutathione and thioredoxin, function to reduce the levels of oxidized molecules. Aldo-keto reductase, using NADPH as an electron donor, detoxifies carbonyl compounds resulting from the oxidation of lipids and proteins. Thus, many antioxidative and redox enzyme genes are expressed and aggressively protect gametes and embryos in reproductive systems.
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Affiliation(s)
- Junichi Fujii
- Department of Biomolecular Function, Yamagata University Graduate School of Medicine, 2-2-2 Iidanishi, Yamagata 990-9585, Japan
| | - Yoshihito Iuchi
- Department of Biomolecular Function, Yamagata University Graduate School of Medicine, 2-2-2 Iidanishi, Yamagata 990-9585, Japan
| | - Futoshi Okada
- Department of Biomolecular Function, Yamagata University Graduate School of Medicine, 2-2-2 Iidanishi, Yamagata 990-9585, Japan
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Colton SA, Downs SM. Potential role for the sorbitol pathway in the meiotic dysfunction exhibited by oocytes from diabetic mice. ACTA ACUST UNITED AC 2004; 301:439-48. [PMID: 15114651 DOI: 10.1002/jez.a.20070] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Complications common to type I diabetes, such as cataracts and cardiovascular disorders, have been associated with activation of the polyol pathway, which converts glucose to fructose via the intermediate, sorbitol. Under normal glycemic conditions, glucose is typically targeted for glycolysis or the pentose phosphate pathway through phosphorylation by hexokinase. When glucose levels are elevated under diabetic conditions, hexokinase becomes saturated, and the excess glucose is then shunted to aldose reductase, which converts glucose to sorbitol. In the present study, we examined the potential effects of this pathway on the maturation process in mouse oocytes. Increasing concentrations of sorbitol suppressed FSH-induced maturation in oocytes from control mice. Culturing oocytes from diabetic mice in the presence of inhibitors of aldose reductase reversed the suppression of FSH-induced meiotic maturation. When oocytes from control mice were cultured with activators of aldose reductase, FSH-induced maturation was compromised. In addition, treatment with sorbitol or activators of the polyol pathway led to reduced cell-cell communication between the oocyte and the cumulus cells, as well as compromised FSH-mediated cAMP production and de novo purine synthesis. These data indicate that the suppression of FSH-induced meiotic maturation observed in oocytes from diabetic mice may result from a shunting of glucose through the polyol pathway.
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Affiliation(s)
- Shannondoah A Colton
- Department of Biological Sciences, Marquette University, Milwaukee, Wisconsin 53201-1881, USA
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8
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Kaneko T, Iuchi Y, Takahashi M, Fujii J. Colocalization of polyol-metabolizing enzymes and immunological detection of fructated proteins in the female reproductive system of the rat. Histochem Cell Biol 2003; 119:309-15. [PMID: 12684816 DOI: 10.1007/s00418-003-0516-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/11/2003] [Indexed: 10/25/2022]
Abstract
The expression of aldose reductase (AR) and sorbitol dehydrogenase (SDH), which, in concert, catalyze the conversion of glucose to fructose via sorbitol, in the rat ovary, oviduct, and uterus, was investigated by immunohistochemical and biochemical analyses. The activities and protein levels of AR and SDH were higher in the ovary than in the oviduct and uterus. A strong immunoreactivity to the anti-AR antibody was observed in granulosa cells and epithelia of the oviduct, endometrium, and endometrial glands, and virtually the same tissues were strongly stained with the anti-SDH antibody. The application of an anti-fructated lysine antibody, which detects an adduct of fructose with the epsilon-amino group of lysine in proteins, in this study detected marked staining mainly in the egg and luminal surface of the oviductal epithelia. Collectively, these data indicate that fructose is produced by coordinately expressed AR and SDH in the egg and epithelia of the oviduct and suggest that the resulting sorbitol and fructose can be used as energy sources for spermatozoa motility during the fertilization process. The abundance of AR compared with SDH suggests that it also plays an additional role in the reproductive system, which might include a source of reducing power and protection against toxic carbonyl compounds.
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Affiliation(s)
- Tomoko Kaneko
- Department of Biochemistry, Yamagata University School of Medicine, 2-2-2 Iidanishi, 990-9585 Yamagata, Japan
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9
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Abstract
Puberty accelerates microvascular complications of diabetes mellitus, including nephropathy. Animal studies confirm a different renal hypertrophic response to diabetes before and after puberty, probably due to differences in the production of transforming growth factor-beta (TGF-beta). Many of the complex physiological changes during puberty could affect potentially pathogenic mechanisms of diabetic kidney disease. Increased blood pressure, activation of the growth hormone-insulin-like growth factor I axis, and production of sex steroids could all play a role in pubertal susceptibility to diabetic renal hypertrophy and nephropathy. These factors may influence the effects of hyperglycemia and several systems that ultimately control TGF-beta production, including the renin-angiotensin system, cellular redox systems, the polyol pathway, and protein kinase C. These phenomena may also explain gender differences in kidney function and incidence of end-stage renal disease. Normal changes during puberty, when coupled with diabetes and superimposed on a genetically susceptible milieu, are capable of accelerating diabetic hypertrophy and microvascular lesions. A better understanding of these processes may lead to new treatments to prevent renal failure in diabetes mellitus.
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Affiliation(s)
- Pascale H Lane
- Department of Pediatrics, University of Nebraska Medical Center, Omaha 68198-2169, USA.
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Svanberg B, Ling C, Svensson PA, Johnson M, Carlsson B, Billig H. Isolation of differentially expressed aldose reductase in ovaries after estrogen withdrawal from hypophysectomized diethylstilbestrol treated rats: increased expression during apoptosis. Mol Cell Endocrinol 2000; 164:183-90. [PMID: 11026569 DOI: 10.1016/s0303-7207(00)00230-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
More than 99% of the follicles are eliminated by apoptosis before reaching ovulation. Several growth factors and hormones inhibit apoptosis in the ovary, including estrogen. Using differential display of mRNA, aldose reductase was shown to increase in the ovary of diethylstilbestrol treated hypophysectomized rats after estrogen withdrawal, inducing apoptosis. The aldose reductase mRNA expression was confirmed to be 2.2 +/- 0.2-fold higher after estrogen withdrawal using northern blot analysis. In addition, untreated immature rats showed a 1.7 +/- 0.3-fold higher expression of ovarian aldose reductase mRNA compared to ovaries 24 h after pregnant mare's serum gonadotropin treatment, decreasing apoptosis in the ovary. In the prostate, the level of aldose reductase was increased 3.1 +/- 1.1-fold 2 days after castration induced apoptosis. Although the physiological role of aldose reductase in the ovary is not known, these data suggest that aldose reductase may be part of a hormonally regulated apoptotic pathway in the ovary and prostate.
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Affiliation(s)
- B Svanberg
- Department of Physiology and Pharmacology, Göteborg University, Sweden.
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11
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Kawamura M, Eisenhofer G, Kopin IJ, Kador PF, Lee YS, Tsai JY, Fujisawa S, Lizak MJ, Sinz A, Sato S. Aldose reductase, a key enzyme in the oxidative deamination of norepinephrine in rats. Biochem Pharmacol 1999; 58:517-24. [PMID: 10424772 DOI: 10.1016/s0006-2952(99)00121-5] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
The sympathoneural neurotransmitter norepinephrine (NE) is deaminated to 3,4-dihydroxymandelaldehyde (DHMAL) and subsequently converted to either 3,4-dihydroxymandelic acid (DHMA) or 3,4-dihydroxyphenylglycol (DHPG). In this study, we investigated the relative importance of aldose reductase versus aldehyde reductase in the formation of DHPG from DHMAL. The in vitro incubation of NE with aldose reductase in the presence of monoamine oxidase (MAO) resulted in the formation of DHPG, which was confirmed by mass spectrometry. Although aldehyde reductase also generated DHPG, its activity was much lower than that of aldose reductase. With northern blotting, the expression of both aldose reductase and aldehyde reductase was detected in rat superior cervical ganglia. However, with western blotting, only aldose reductase was immunologically detectable. Treatment of rats with aldose reductase inhibitors for 3 days increased the plasma level of DHMA. There was no correlation between the selectivity of inhibitors and effects on NE metabolite levels. A significant decrease in DHPG, however, was obtained only with an extremely high dose (9 mg/kg/day) of the nonselective inhibitor AL 1576. The present study confirmed that aldose reductase generates DHPG from NE in the presence of MAO. In rat sympathetic neurons, aldose reductase appears to be more important than aldehyde reductase for the formation of DHPG. However, when aldose reductase is inhibited, it appears that aldehyde reductase can compensate for the conversion of DHMAL to DHPG, indicating redundancy in the reduction pathway.
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Affiliation(s)
- M Kawamura
- Clinical Neuroscience Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA
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Abstract
Kinetic studies on the aldose reductase protein (AR2) have shown that it does not behave as a classical enzyme in relation to ring aldose sugars. These results have been confirmed by X-ray crystallography studies, which have pinpointed binding sites for pharmacological "aklose reductase inhibitors" (ARIs). As with non-enzymic glycation reactions, there is probably a free-radical element involved derived from monosaccharide autoxidation. In the case of AR2, there is free radical oxidation of NADPH by autoxidising monosaccharides, enhanced in the presence of the NADPH-binding protein. Whatever the behaviour of AR2, many studies have showed that sorbitol production is not an initiating aetiological factor in the development of diabetic complications in humans. Vitamin E (alpha-tocopherol), other antioxidants and high fat diets can delay or prevent cataract in diabetic animals even though sorbitol and fructose levels are not modified; vitamin C acts as an AR1 in humans. Protein post-translational modification by glyc-oxidation or other events is probably the key factor in the aetiology of diabetic complications. There is now no need to invoke AR2 in xylitol biosynthesis. Xylitol can be produced in the lens from glucose, via a pathway involving the enzymes myo-inositol-oxygen oxidoreductase, D-glucuronate reductase. L-gulonate NAD(+)-3-oxidoreductase and L-iditol-NAD(+)-5-oxidoreductase, all of which have recently been found in bovine and rat lens. This chapter investigates the molecular events underlying AR2 and its binding and kinetics. Induction of the protein by osmotic response elements is discussed, with detailed analysis of recent in vitro and in vivo experiments on numerous ARIs. These have a number of actions in the cell which are not specific, and which do not involve them binding to AR2. These include peroxy-radical scavenging and recently discovered effects of metal ion chelation. In controlled experiments, it has been found that incubation of rat lens homogenate with glucose and the copper chelator o-phenanthroline abolishes production of sorbitol. Taken together, these results suggest AR2 is a vestigial NADPH-binding protein, perhaps similar in function to a number of non-mammalian crystallins which have been recruited into the lens. There is mounting evidence for the binding of reactive aldehyde moieties to the protein, and the involvement of AR2 either as a 'housekeeping' protein, or in a free-radial-mediated 'catalytic' role. Interfering with the NADPH binding and flux levels--possibly involving free radicals and metal ions--has a deleterious effect. We have yet to determine whether aldose reductase is the black sheep of the aldehyde reductase family, or whether it is a skeleton in the cupboard, waiting to be clothed in the flesh of new revelations in the interactions between proteins, metal ions and redox metabolites.
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Affiliation(s)
- M J Crabbe
- Wolfson Laboratory, Division of Cell and Molecular Biology, School of Animal and Microbial Sciences, University of Reading, Whiteknights, Berks, UK.
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Hyndman DJ, Takenoshita R, Vera NL, Pang SC, Flynn TG. Cloning, sequencing, and enzymatic activity of an inducible aldo-keto reductase from Chinese hamster ovary cells. J Biol Chem 1997; 272:13286-91. [PMID: 9148949 DOI: 10.1074/jbc.272.20.13286] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Treatment of Chinese hamster ovary (CHO) cells by the aldehyde containing calpain inhibitor I resulted in the induction of a 35-kDa protein that was partially sequenced and shown to be a member of the aldo-keto reductase superfamily (Inoue, S., Sharma, R. C., Schimke, R. T., and Simoni, R. D. (1993) J. Biol. Chem. 268, 5894-5898). Using rapid amplification of cDNA ends polymerase chain reaction, we have sequenced the cDNA for this protein (CHO reductase). This enzyme is a new member of the aldo-keto reductase superfamily and shows greatest amino acid sequence identity to mouse fibroblast growth factor-regulated protein and mouse vas deferens protein (92 and 80% sequence identity, respectively). The enzyme exhibits about 70% sequence identity with the aldose reductases (ALR2; EC 1.1.1.21) and about 47% with the aldehyde reductases (ALR1; EC 1.1.1.2). Northern analysis showed that it is induced in preference to either ALR1 or ALR2 and RNase protection assays showed gene expression in bladder, testis, jejunum, and ovary in descending order of expression. The cDNA for this inducible reductase was cloned into the pET16b vector and expressed in BL21(DE3) cells. Expressed CHO reductase showed kinetic properties distinct from either ALR1 or ALR2 including the ability to metabolize ketones. This protein joins a growing number of inducible aldo-keto reductases that may play a role in cellular regulation and protection.
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Affiliation(s)
- D J Hyndman
- Department of Biochemistry, Queen's University, Kingston, Ontario, K7L 3N6 Canada
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