Spread Forex Single En 1 Ghrelin receptor gene polymorphisms are associated with female metabolic syndrome in Chinese population
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for 10 minutes at room temperature, and plasma and ※buffy-coat§ were separated and stored in 1.5 ml EP tube at 每70∼C. Serum total cholesterol, HDL-C, triglycerides, glucose and potassium concentration were analyzed using an automatic analyzer (Hitachi 7060, Hitachi, Tokyo, Japan).
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According to SNP database of National Center for Biotechnology Information (NCBI) (SNP/) and HapMap (cgi- perl/gbrowse/hapmap20_B35), only two SNPs (rs2922126 and rs572169) within the promoter met the criteria of minor allele frequency (MAF) >10% and resulted in the binding change of transcription factors. SNPs rs509035 in intron has been reported to be associated with obesity.9 Therefore, these three polymorphisms were selected for the investigation of their association with either metabolic syndrome or its components.
Genotype
Genomic DNA was extracted from ※buffy-coat§ as described previously.14 All three SNPs were genotyped by polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) technique. PCR was carried out in 10 µl of reaction mixture containing 50 ng of genomic DNA (2 µl), 5 µl 2℅Taq PCR Master MIX (TIANWEI-biotech com, Beijing, China), 1 µl (5 pmol/L) of each primer, 1 µl ddH2O. The primers were designed using Oligo6.0 software. All assays were performed in duplicate. The length of PCR products and restriction fragments is list in Table 1.
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Table 1. Primers, length of PCR product and restriction fragments, and restriction enzymes
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Statistical analysis
Numerical distributions are presented by means ㊣ standard deviation (SD). Statistical analysis was performed with the SPSS 13.0 package. Chi-square test was used to analyze binomial variables, genotype frequencies, and Hardy-Weinberg equilibrium of the polymorphisms. Student's t test was used for comparison of quantitative variables; and odds ratios (OR) and their 95% confidence intervals (CI) were estimated by the multivariable Logistic regression of the contribution of gene variants to metabolic syndrome and to its components. Age, smoking status, and alcohol consumption were included in the models as confounding variables. A value of P <0.05 was considered significant.
RESULTS
Characteristics of the subjects
Demographic and clinical characteristics of all the subjects are shown in Table 2. Male patients were slightly older than male controls. The average age of female patients and controls were statistically equivalent. As expected, all five components of the metabolic syndrome were more prevalent in patients with metabolic syndrome than in controls. The prevalence of smoking status and alcohol consumption was higher in men with metabolic syndrome than those in the corresponding controls.
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Table 2. Demographic and clinical characteristics of patients and controls |
Association of genotype with phenotype
The genotypes of all three SNPs were in agreement with Hardy-Weinberg equilibrium in either cases or controls. The OR and 95%CI of the genotype rs2922126 with phenotype are shown in Table 3. The rs2922126 A/A genotype was associated with metabolic syndrome (OR 1.41, 95%CI 1.03每1.94); waist circumference (OR 1.75, 95% CI 1.26每2.42) and fast blood glucose (OR 1.49, 95% CI 1.07每2.06) in women, but not in men after adjusted for age, smoking status and alcohol consumption.
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Table 3.﹛The association of the rs2922126 genotypes with phenotype |
The genotype rs509035 was not significantly different between the patients with metabolic syndrome and controls in both men and women. The frequency of the rs509035A/A genotype was higher in women with lower HDL than that in controls (30.0% vs 24.1%, P<0.05), and the rs509030 A/A genotype was associated with lower HDL (adjusted OR 1.37, 95% CI 1.02每1.84) in women.
No significant difference was identified for the genotypes rs572169 between the patients and the controls. We further categorized the subjects by components of the metabolic syndrome and did not find any association between genotypes and these clinical components.
DISCUSSION
In the present study, we demonstrated that the SNP rs2922126 within GHSR was associated with obesity, high fast blood glucose and metabolic syndrome in women. The rs509030 A/A genotype variant contributed to a low level of high density lipoprotein in women. No association with metabolic syndrome was found in men. Our results are consistent with the previous study,9 which revealed that genotype variant rs 509030A/A was a risk factor for obesity in Caucasian population.
Two major etiological factors (insulin resistance and obesity) underlying the metabolic syndrome are influenced by gender15,16 and the diagnostic criteria of metabolic syndrome for men and women are different, so we conducted our analyses separately by sex. GHSR was identified to have two transcripts, one encoding the full-length G-protein-coupled receptor (GHSR1a) and the other encoding a truncated receptor (GHSR1b). Only GHSR1a can be activated by ghrelin, and the function of GHSR1b remains unknown.17
The boundary of the promoter region is defined according to Petersenn's suggestion.18 According to dbSNP and HapMap, only four SNPs in promoter region meet the criteria of minor allele frequency (>10%). Linkage disequilibrium analysis revealed that the four SNPs are not linked each other. Among the four SNPs, only two (rs2922126 and rs572169) could result in the loss/gain of transcription factor binding sites by analysis using Alibaba program. Therefore, we suspect that rs2922126 plays a role in metabolic syndrome by changing the transcriptional activity of GHSR. Future work is needed to elucidate their functional roles.
Gonadal hormone may affect the function of GHSR. Estrogen has been shown to inhibit the function of ARH NPY/AgRP neurons and strengthen the anorexigenic signals.19 However, testosterone increases ARH/NPY expression and counteracts the anorexigenic signals.20 Zigman and his colleagues21 found that female GHSR-null mice exhibited much leaner phenotype compared with wild-type females when maintained on either standard or high-fat chow. However, male GHSR每/每 mice were indistinguishable from wild-type mice when maintained on a standard chow diet. The gender difference in basal body weight phenotype is consistent with the findings of other investigators who have independently generated their own GHSR每/每 mice.22 These might partially explain that the association of GHSR gene with metabolic syndrome observed in our study is gender-dependent.
The present study has certain limitations that need to be taken into account when considering its contributions. The major limitation is that the different geographical and racial background of the individuals might affect the results of the association study. Therefore, our results need to be confirmed in other cohorts.
In summary, our results indicate that Chinese women who carry genotype variants of rs2922126 A/A or rs 509030 A/A within the ghrelin receptor gene might have increased risk of metabolic syndrome.
REFERENCES
1. Smith RG, Van der Ploeg LH, Howard AD, Feighner SD, Cheng K, Hickey GJ, et al. Peptidomimetic regulation of growth hormone secretion. Endocr Rev 1997; 18: 621-645.
2. Tschop M, Smiley DL, Heiman ML. Ghrelin induces adiposity in rodents. Nature 2000; 407: 908-913.
3. Kojima M, Hosoda H, Date Y, Nakazato M, Matsuo H, Kangawa K. Ghrelin is a growth-hormone-releasing acylated peptide from stomach. Nature 1999; 402: 656-660.
4. Nakazato M, Murakami N, Date Y, Kojima M, Matsuo H, Kangawa K, et al. A role for ghrelin in the central regulation of feeding. Nature 2001; 409: 194-198.
5. Chen HY, Trumbauer ME, Chen AS, Weingarth DT, Adams JR, Frazier EG, et al. Orexigenic action of peripheral ghrelin is mediated by neuropeptide Y and agouti-related protein. Endocrinology 2004; 145: 2607-2612.
6. Dezaki K, Sone H, Koizumi M, Nakata M, Kakei M, Nagai H, et al. Blockade of pancreatic islet-derived ghrelin enhances insulin secretion to prevent high-fat diet-induced glucose intolerance. Diabetes 2006; 55: 3486-3493.
7. Katsuki A, Urakawa H, Gabazza EC, Murashima S, Nakatani K, Togashi K, et al. Circulating levels of active ghrelin is associated with abdominal adiposity, hyperinsulinemia and insulin resistance in patients with type 2 diabetes mellitus. Eur J Endocrinol 2004; 151: 573-577.
8. Hu R, Ma CS, Nie SP, Lu Q, Kang JP, Du X, et al. Effect of metabolic syndrome on prognosis and clinical characteristics of revascularization in patients with coronary artery disease. Chin Med J 2006; 119: 1871-1876.
9. Baessler A, Hasinoff MJ, Fischer M, Reinhard W, Sonnenberg GE, Olivier M, et al. Genetic linkage and association of the growth hormone secretagogue receptor (ghrelin receptor) gene in human obesity. Diabetes 2005; 54: 259-267.
10. Baessler A, Kwitek AE, Fischer M, Koehler M, Reinhard W, Erdmann J, et al. Association of the Ghrelin receptor gene region with left ventricular hypertrophy in the general population: results of the MONICA/KORA Augsburg Echocardiographic Substudy. Hypertension 2006; 47: 920-927.
11. Baessler A, Fischer M, Mayer B, Koehler M, Wiedmann S, Stark K, et al. Epistatic interaction between haplotypes of the ghrelin ligand and receptor genes influence susceptibility to myocardial infarction and coronary artery disease. Hum Mol Genet 2007; 16: 887-899.
12. Alberti KG, Zimmet P, Shaw J. The metabolic syndrome每a new worldwide definition. Lancet 2005; 366: 1059-1062.
13. Chobanian AV, Bakris GL, Black HR, Cushman WC, Green LA, Izzo JL Jr, et al. Seventh report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure. Hypertension 2003; 42: 1206-1252.
14. Leadon SA, Cerutti PA. A rapid and mild procedure for the isolation of DNA from mammalian cells. Anal Biochem 1982; 120: 282-288.
15. Corry DB. Sex-related differences in the insulin resistance syndrome. Curr Hypertens Rep 2001; 3: 124-128.
16. Ko TC, Chan J, Chan A, Wong P, Hui S, Chow F, et al. Doubling over ten years of central obesity in Hong Kong Chinese working men. Chin Med J 2007; 120: 1151-1154.
17. Howard AD, Feighner SD, Cully DF, Arena JP, Liberator PA, Rosenblum CI, et al. A receptor in pituitary and hypothalamus that functions in growth hormone release. Science 1996; 273: 974-977.
18. Petersenn S, Rasch AC, Penshorn M, Beil FU, Schulte HM. Genomic structure and transcriptional regulation of the human growth hormone secretagogue receptor. Endocrinology 2001; 142: 2649-2659.
19. Eckel LA. Estradiol: a rhythmic, inhibitory, indirect control of meal size. Physiol Behav 2004; 82: 35-41.
20. Nunez AA, Grundman M. Testosterone affects food intake and body weight of weanling male rats. Pharmacol Biochem Behav 1982; 16: 933-936.
21. Zigman JM, Nakano Y, Coppari R, Balthasar N, Marcus JN, Lee CE, et al. Mice lacking ghrelin receptors resist the development of diet-induced obesity. J Clin Invest 2005; 115: 3564-3572.
22. Wortley KE, del Rincon JP, Murray JD, Garcia K, Iida K, Thorner MO, et al. Absence of ghrelin protects against early-onset obesity. J Clin Invest 2005; 115: 3573-3578.
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