Genetic variations of Mrf-2/ARID5B confer risk of coronary atherosclerosis in the Japanese population

Multi-ancestry genome-wide study identifies effector genes and druggable pathways for coronary artery calcification

Coronary artery calcification (CAC), a measure of subclinical atherosclerosis, predicts future symptomatic coronary artery disease (CAD). Identifying genetic risk factors for CAC may point to new therapeutic avenues for prevention. Currently, there are only four known risk loci for CAC identified from genome-wide association studies (GWAS) in the general population. Here we conducted the largest multi-ancestry GWAS meta-analysis of CAC to date, which comprised 26,909 individuals of European ancestry and 8,867 individuals of African ancestry. We identified 11 independent risk loci, of which eight were new for CAC and five had not been reported for CAD. These new CAC loci are related to bone mineralization, phosphate catabolism and hormone metabolic pathways. Several new loci harbor candidate causal genes supported by multiple lines of functional evidence and are regulators of smooth muscle cell-mediated calcification ex vivo and in vitro. Together, these findings help refine the genetic architecture of CAC and extend our understanding of the biological and potential druggable pathways underlying CAC.

ARID5B rs10821936 and rs10994982 gene polymorphism and susceptibility to juvenile systemic lupus erythematosus and lupus nephritis

BACKGROUND

The prevalence of SLE and the spectrum of clinical manifestations vary widely in different races and geographical populations.

OBJECTIVE

To investigate the possible role of ARID5B rs10821936 and rs10994982 polymorphism as a risk factor for the development of SLE in children (jSLE) and to evaluate their role in relation to clinical manifestations especially lupus nephritis (LN).

METHODS

DNA extraction and Real-time PCR genotyping of ARID5B rs10821936 and rs10994982 were done for 104 jSLE and 282 healthy controls.

RESULTS

The C allele and C containing genotypes (CC, CT and CC+CT) of ARID5B rs10821936 were higher in children with SLE (p = 0.009, OR = 1.56, 0.037, OR = 2.35, 0.016, OR = 1.81 and 0.008 OR = 1.88 respectively). ARID5B rs10994982 alleles, genotypes and haplotypes are not associated with jSLE (p > 0.05). The ARID5B rs10821936 and rs10994982 genotypes showed non-significant associations with LN, proliferative versus non proliferative and biopsy grades (p > 0.05).

CONCLUSION

ARID5B rs10821936 SNP may be a susceptibility risk factor for juvenile SLE in the studied cohort of Egyptian children.

Relationship between Modulator Recognition Factor 2/AT-rich Interaction Domain 5B Gene Variations and Type 2 Diabetes Mellitus or Lipid Metabolism in a Northern Chinese Population

Background:

Four single nucleotide polymorphisms (SNPs) in the modulator recognition factor 2/AT-rich interaction domain 5B (MRF2/ARID5B) gene located at chromosome 10q21.2 have been shown to be associated with both type 2 diabetes mellitus (T2DM) and coronary artery disease in a Japanese cohort. This study aimed to investigate the relationship between these SNPs (rs2893880, rs10740055, rs7087507, rs10761600) and new-onset T2DM and lipid metabolism in a Northern Chinese population.

Methods:

This was a case-control study. The rs2893880, rs10740055, rs7087507, and rs10761600 genetic variants were genotyped by SNPscan and analyzed in relation to T2DM susceptibility in 2000 individuals (999 with newly diagnosed T2DM and 1001 controls without diabetes mellitus). Associations between the MRF2/ARID5B genetic models and T2DM were determined by multivariate logistic regression.

Results:

Regarding the rs10740055 SNP, AA was associated with a higher risk of T2DM compared with codominant-type CC (adjusted by sex, age, and body mass index [BMI], P = 0.041, odds ratio [OR] = 1.421, 95% confidence interval [CI] 1.014–1.991). Meanwhile, AA individuals were at increased risk of presenting with T2DM compared with individuals with CC or a single C (adjusted by sex, age, and BMI, P = 0.034, OR = 1.366, 95% CI 1.023–1.824). With respect to rs10761600, AT contributed to a higher risk of T2DM compared with AA (adjusted by sex, age, and BMI, P = 0.013, OR = 1.585, 95% CI 1.101–2.282), while TT also increased the risk of presenting with T2DM compared with AA or A (adjusted by sex, age, and BMI, P = 0.004, OR = 1.632, 95% CI 1.166–2.284). High-density lipoprotein cholesterol (HDL-C) levels were significantly different among the three genotypes of rs7087507 in the controls (P = 0.048) (GG>GA).

Conclusions:

The present results identified MRF2/ARID5B as a potential susceptibility gene for new-onset T2DM in a Northern Chinese population, while the rs7087507 SNP was associated with HDL-C levels. Further larger studies are required to validate these findings.

Knockdown of AT-rich interaction domain (ARID) 5B gene expression induced AMPKα2 activation in cardiac myocytes

This study demonstrated that ARID5B mRNA is present in mouse cardiomyocyte HL-1 cells, and that ARID5B siRNA constantly knocked down ARID5B gene expression to the 40% level of control. AMPKα2 protein was elevated in such ARID5B knockdown HL-1 cells, and this was accompanied by an increase in the level of phosphorylated AMPKα. Since AMPKα2 mRNA levels did not change in ARID5B knockdown cells, the stability of AMPKα2 protein was investigated using inhibitors for protein synthesis and proteasomal degradation. Treatment of HL-1 cells with either cycloheximide or MG132 caused an appreciable increase in the amount of AMPKα2 protein in ARID5B knockdown cells, which suggests that knockdown of ARID5B mRNA extends the half-life of AMPKα2 protein in HL-1 cells via yet unidentified mechanisms. As for the expected downstream consequences of AMPKα2 activation, we found thus far that glucose uptake, fatty acid uptake, or fatty acid oxidation remained unchanged in HL-1 cells after knockdown of ARID5B. Further studies are required to understand the mechanisms for ARID5B knockdown and resulting AMPKα2 activation, and also to identify which metabolic pathways are affected by AMPKα2 activation in these cells. In summary, this study provided the foundation for an in vitro cell culture system to study possible roles of ARID5B in cardiomyocytes.

In vitro effects of low-level aldehyde exposures on human umbilical vein endothelial cells

Aldehydes cause gene expression changes for genes associated with cardiovascular disease. Exposure to aldehydes from tobacco smoke needs to be controlled.

Age-related variations in the methylome associated with gene expression in human monocytes and T cells

Age-related variations in DNA methylation have been reported; however, the functional relevance of these differentially methylated sites (age-dMS) are unclear. Here we report potentially functional age-dMS, defined as age- and cis-gene expression-associated methylation sites (age-eMS), identified by integrating genome-wide CpG methylation and gene expression profiles collected ex vivo from circulating T cells (227 CD4+ samples) and monocytes (1,264 CD14+ samples, age range: 55–94 years). None of the age-eMS detected in 227 T cell samples are detectable in 1,264 monocyte samples, in contrast to the majority of age-dMS detected in T cells that replicated in monocytes. Age-eMS tend to be hypomethylated with older age, located in predicted enhancers, and preferentially linked to expression of antigen processing and presentation genes. These results identify and characterize potentially functional age-related methylation in human T cells and monocytes, and provide novel insights into the role age-dMS may play in the aging process.

Neonatal genome-wide methylation patterns in relation to birth weight in the Norwegian Mother and Child Cohort

Although epigenetic regulation plays a critical role in embryonic development, few studies have examined the relationship of epigenome-wide methylation with fetal growth. Using the Infinium HumanMethylation450 BeadChip (Illumina, Inc., San Diego, California) in a substudy of 1,046 infants from the Norwegian Mother and Child Cohort Study (MoBa) enrolled between 1999 and 2008, we examined epigenome-wide cord blood DNA methylation in relation to birth weight. In multivariable-adjusted robust linear regression models, we identified differential methylation at 19 cytosine-guanine dinucleotides (CpGs) associated with either decreased (AT-rich interactive domain 5B (MRF1-like) (ARID5B), 2 CpGs) or increased (x-ray repair complementing defective repair in Chinese hamster cells 3 (XRCC3), 4 CpGs) birth weight. ARID5B knockout mice have less adipose tissue and significantly lower weight in the postnatal period. XRCC3 plays a key role in the maintenance of chromosome stability and the repair of DNA damage. Although there are fewer data on the other implicated genes, many of these genes have been shown to have roles in developmental processes. This constitutes the largest and most robust study of birth weight using an epigenome-wide methylation platform and offers potential insights into epigenetic mechanisms of fetal growth.