Meta-analysis of the association between the rs7903146 polymorphism at the TCF7L2 locus and type 2 diabetes mellitus susceptibility

Type 2 diabetes mellitus (T2DM) is a chronic disease caused by genetic and environmental factors. T2DM has been associated with specific polymorphisms in the TCF7L2 gene. This study evaluates the relationship between the rs7903146 locus polymorphism of the TCF7L2 gene and T2DM susceptibility through meta-analysis; the overall aim is to provide a basis for evidence-based medicinal treatment of T2DM. Cohort and case-control studies from Medline, PubMed, EMBASE, CBM, CNKI, and academic conferences/dissertations that examined the correlation between T2DM and rs7903146 polymorphisms were evaluated. We determined whether the TCF7L2 rs7903146 locus was associated with T2DM susceptibility by comparing alleles and genotypes. The Stata 11.0 software was applied for meta-analysis, and a random-effects model was adopted for heterogeneity testing and odds ratio (OR) calculation. A fixed-effect model was used for quantitative analysis of the heterogeneity between different studies, and for calculating the percentage of variability I(2). A total of 10 studies related to the rs7903146 loci and T2DM susceptibility were enrolled; this included 3404 cases of T2DM patients and 6473 control cases. Meta-analysis showed that the T allele of rs7903146 was significantly correlated with the risk of T2DM, with both a dominant fixed-effect model (OR = 1.653, 95%CI = 1.416-1.653) and a co-dominant-fixed effect model (OR = 1.525, 95%CI = 1.350-1.723). Meta-analysis revealed that the T allele of rs7903146 was also correlated with T2DM susceptibility.

Valproic acid attenuates the suppression of acetyl histone H3 and CREB activity in an inducible cell model of Machado-Joseph disease

Machado-Joseph disease (MJD) is caused by a (CAG)n trinucleotide repeat expansion that is translated into an abnormally long polyglutamine tract. This disease is considered the most common form of spinocerebellar ataxia (SCA). In the present study, we developed stable inducible cell lines (PC12Tet-On-Ataxin-3-Q28/84) expressing ataxin-3 with either normal or abnormal CAG repeats under doxycycline control. The expression of acetyl histone H3 and the induction of c-Fos in response to cAMP were strongly suppressed in cells expressing the protein with the expanded polyglutamine tract. Treatment with valproic acid, a histone deacetylase inhibitor (HDACi), attenuated mutant ataxin-3-induced cell toxicity and suppression of acetyl histone H3, phosphorylated cAMP-responsive element binding protein (p-CREB) as well as c-Fos expression. These results indicate that VPA can stimulate the up-regulation of gene transcription through hyperacetylation. Thus, VPA might have a therapeutic effect on MJD.