Integrated analysis of probability of type 2 diabetes mellitus with polymorphisms and methylation of KCNQ1 gene: A nested case-control study

BACKGROUND

To estimate the associations between single-nucleotide polymorphisms (SNPs) and methylation of KCNQ1 gene and type 2 diabetes mellitus (T2DM) risk and the interactions among SNPs, methylation, and environmental factors on T2DM risk.

METHODS

We genotyped five SNPs and tested methylation at 39 CpG loci of KCNQ1 in 290 T2DM cases and 290 matched controls nested in the Rural Chinese Cohort Study. Conditional logistic regression model was used to estimate the associations between SNPs and KCNQ1 methylation and T2DM risk. Multifactor dimensionality reduction (MDR) analysis was used to estimate the effect of the interactions SNPs-SNPs, SNPs-methylation, methylation-methylation and SNPs, and methylation-environment on T2DM risk.

RESULTS

Probability of T2DM was decreased with rs2283228 of KCNQ1 (CA vs AA, odds ratio [OR] = 0.65, 95% confidence interval [CI] 0.42-0.99). T2DM probability was significantly increased with rs2237895 combined with hypertriglyceridemia (OR_eg  = 2.76, 95% CI 1.35-5.62), with hypertension (OR_eg  = 2.23, 95% CI 1.25-3.98), and with body mass index (BMI; OR_eg  = 1.93, 95% CI 1.12-3.34). T2DM probability was associated with methylation of CG11 and CG41 (OR = 1.89, 95% CI 1.23-2.89, P = .003). It was significantly associated with the interaction between BMI, hypertriglyceridemia, and CG5 methylation (P = .028 and .028), and the combined effects of CG11 with hypertriglyceridemia and hypertension. On MDR analysis, no significant interaction was observed.

CONCLUSION

T2DM probability was reduced 35% with rs2283228 polymorphism. It was associated with rs2237895 combined with hypertension, with BMI and with hypertriglyceridemia. The methylation at two CpG loci of KCNQ1 significantly increased T2DM risk by 89%.

[Role of hypomethylation of suppressor of cytokine signaling in T helper 17 cell/regulatory T cell imbalance in children with Henoch-Schönlein purpura]

OBJECTIVE

To investigate the association between suppressor of cytokine signaling (SOCS) hypomethylation and T helper 17 (Th17) cell/regulatory T (Treg) cell imbalance in children with Henoch-Schönlein purpura (HSP) and the immune pathogenesis of HSP.

METHODS

A total of 32 children in the acute stage of HSP who were hospitalized from May 2014 to January 2015 were enrolled as subjects, and 28 children who underwent physical examination were enrolled as normal control group. ELISA was used to measure the plasma level of interleukin-6 (IL-6). Flow cytometry was used to measure the percentages of CD4⁺ IL-17A⁺ T cells (Th17 cells) and CD4⁺CD25⁺ Treg cells (Treg cells) in peripheral blood and mean fluorescence intensity (MFI) for phosphorylated-STAT3 (pSTAT3) protein in CD4⁺ T cells. Quantitative real-time PCR was used to measure the mRNA expression of suppressor of cytokine signaling-1 (SOCS1) and suppressor of cytokine signaling-3 (SOCS3) in CD4⁺ T cells. High-resolution melting (HRM) was used to evaluate the methylation level of the CpG islands in SOCS1 exon 2 and the CpG islands of the potential bind sites for STAT3 in the 5'-untranslated region (5'-UTR) of SOCS3 in peripheral blood mononucleated cells.

RESULTS

Compared with the normal control group, the HSP group had significant increases in plasma IL-6 concentration and MFI for pSTAT3 in CD4⁺ T cells, as well as a significant increase in the percentage of Th17 cells and a significant reduction in the percentage of Treg cells (P<0.05). The HSP group had significantly higher mRNA expression of SOCS1 and SOCS3 in peripheral blood mononucleated cells than the normal control group (P<0.05). In the HSP group, the mRNA expression of SOCS1 and SOCS3 was negatively correlated with Th17/Treg ratio (P<0.05). The HSP group had hypomethylation of the CpG islands in SOCS1 exon 2 and the potential binding site for STAT3 in SOCS3 5'-UTR, while the normal control group had complete demethylation.

CONCLUSIONS

Low relative expression of SOCS1 and SOCS3 caused by hypomethylation may be a factor for Th17/Treg imbalance in children with HSP.

[Interactive regulatory effect of histone H3K9ac acetylation and histone H3K9me3 methylation on cardiomyogenesis in mice]

OBJECTIVE

To study the interactive regulatory effect of histone acetylation and methylation on cardiomyogenesis, and to provide a theoretical basis for the prevention and treatment of congenital heart disease.

METHODS

A total of 24 Kunming mice were randomly divided into embryo day 14.5 (ED 14.5) group, embryo day 16.5 (ED 16.5) group, postnatal day 0.5 (PND 0.5) group, and postnatal day 7 (PND 7) group, with 6 mice in each group, and the heart tissue of fetal and neonatal mice was collected. Colorimetry was used to measure the activities of histone acetylases (HATs) and histone methyltransferases (HMTs) in the myocardium. Western blot was used to measure the expression of H3K9ac and H3K9me3 in the myocardium.

RESULTS

Colorimetry showed that the activities of HATs and HMTs were higher before birth and were lower after birth. There was a significant difference in the activity of HATs in the myocardium between the PND 0.5 and PND 7 groups and the ED 14.5 group (P<0.05), as well as between the PND 7 group and the ED 16.5 group (P<0.05). There was also a significant difference in the activity of HMTs in the myocardium between the PND 7 group and the ED 14.5 and ED 16.5 groups (P<0.05). Western blot showed higher expression of H3K9ac and H3K9me3 before birth and lower expression of H3K9ac and H3K9me3 after birth, and there were significant differences in the expression H3K9ac and H3K9me3 in the myocardium between the PND 0.5 and PND 7 groups and the ED 14.5 and ED 16.5 groups (P<0.05).

CONCLUSIONS

The dynamic expression of HATs, HMTs, H3K9ac, and H3K9me3 is observed during cardiomyogenesis, suggesting that histone H3K9ac acetylation and histone H3K9me3 methylation mediated by HATs and HMTs may play a role in interactive regulation during cardiomyogenesis.

蛋白修饰与炎症性肠病

近年来炎症性肠病(inflammatory bowel disease, IBD)的发病率明显呈持续上升趋势, 越来越多的证据表明, 肠道内蛋白质的异常表达或蛋白修饰的异常与IBD的发病有关. 蛋白修饰是指蛋白质通过翻译后修饰改变自身的空间构象、活性、稳定性及与其他分子相互作用等方面的性能, 从而参与调节机体多样化的生命过程. 虽然蛋白修饰不会改变DNA的序列, 但可以影响相关基因的表达. 研究显示, 蛋白修饰可能通过患者的饮食、环境及肠道微生物等多方面影响基因表型从而参与IBD的发病过程. 本文就蛋白修饰在IBD发病过程中所起的作用做一综述.

[Promoter methylation and expression of death-associated protein kinase gene in acute leukemia]

OBJECTIVE

To study the clinical implications of death-associated protein kinase (DAPK) promoter methylation and DAPK gene expression in untreated patients with acute leukemia.

METHODS

Methylation-specific PCR and RT-PCR were employed to detect the DAPK gene methylation and mRNA expression in the bone marrow of 60 patients with acute myeloid leukemia (AML), 55 patients with acute lymphocytic leukemia (ALL), and 17 normal subjects.

RESULTS

The positivity rate of DAPK methylation was significantly higher in ALL patients (29.1%) than in AML patients group (5%) and normal subjects (0%) (P<0.01). No correlation was found between DAPK gene methylation and the clinical features in ALL patients (P>0.05). DAPK mRNA expression level differed significantly among the 3 groups (P=0.000), and was the highest in normal subjects and the lowest in ALL patients. In ALL patients, the expression level of DAPK mRNA showed a significant inverse correlation with DAPK promoter methylation (P<0.05).

CONCLUSION

The methylation rate of DAPK gene is higher in untreated ALL patients than in AML patients and normal subjects. DAPK gene methylation is not correlated with the clinical features of ALL patients but is probably related with the low gene expression level of DAPK in these patients.

[Gene promoter methylation in glucose-6-phosphate dehydrogenase deficiency]

OBJECTIVE

To investigate the features of methylation in the promoter region of glucose-6-phosphate dehydrogenase (G6PD) gene and the association between gene promoter methylation and G6PD deficiency.

METHODS

Fluorescent quantitative PCR was used to measure the mRNA expression of G6PD in 130 children with G6PD deficiency. Sixty-five children without G6PD deficiency served as the control group. The methylation-sensitive high-resolution melting curve analysis and bisulfite PCR sequencing were used to analyze gene promoter methylation in 22 children with G6PD deficiency and low G6PD mRNA expression. The G6PD gene promoter methylation was analyzed in 44 girls with normal G6PD mRNA expression (7 from G6PD deficiency group and 37 from control group).

RESULTS

Twenty-two (16.9%) children with G6PD deficiency had relatively low mRNA expression of G6PD; among whom, 16 boys showed no methylation, and 6 girls showed partial methylation. Among the 44 girls with normal G6PD mRNA expression, 40 showed partial methylation, and 4 showed no methylation (1 case in the G6PD group and 3 cases in the control group).

CONCLUSIONS

Gene promoter methylation is not associated with G6PD deficiency in boys. Girls have partial methylation or no methylation in the G6PD gene, suggesting that the methylation may be related to G6PD deficiency in girls.

[Effects of gossypol acetic acid on the proliferation and methylation level of the human MutL homologue 1 gene in human tongue carcinoma cell line Tca8113]

OBJECTIVE

This paper aims to study the effects of gossypol acetic acid (GAA) on proliferation and methylation level of human MutL homologue 1 (hMLH1) gene in human tongue cancer cell line Tca8113.

METHODS

The MTT assay was used to determine the effects of the acid on the proliferation inhibition in Tca8113 cells treated with different GAA concentrations. Nested methylation-specific polymerase chain reaction (nMSP) was used to detect the change in the methylation level of hMLH1 after 48 and 72 h with 30 and 15 micro mol L(-1) GAA treatment.

RESULTS

MTT assay results showed the growth and proliferation inhibition of Tca8113 cells in the experimental GAA group after 24 h to 72 h of GAA treatment. The nMSP results indicated that the average optical density of hMLH1 in the Tca8113 cells significantly changed after the GAA treatment (30 micro mol L(-1) GAA for 48 h and 15 micro mol L(-1) for 72 h) (P<0.05) compared with that of the control group.

CONCLUSION

GAA does not only inhibit Tca8113 proliferation but also has a demethylation effect on the hMLH1 gene. These phenomena may be part of an underlying tumor-suppression mechanism of GAA.