A commonly occurring polymorphism upstream of the estrogen receptor alpha alters transcription and is associated with increased HDL

17β-estradiol regulates the expression of apolipoprotein M through estrogen receptor α-specific binding motif in its promoter

Background

We have previously demonstrated that estrogen could significantly enhance expression of apolipoprotein M (apoM), whereas the molecular basis of its mechanism is not fully elucidated yet. To further investigate the mechanism behind the estrogen induced up-regulation of apoM expression.

Results

Our results demonstrated either free 17β-estradiol (E2) or membrane-impermeable bovine serum albumin-conjugated E2 (E2-BSA) could modulate human apoM gene expression via the estrogen receptor alpha (ER-α) pathway in the HepG2 cells. Moreover, experiments with the luciferase activity analysis of truncated apoM promoters could demonstrate that a regulatory region (from-1580 to −1575 bp (−GGTCA-)) upstream of the transcriptional start site of apoM gene was essential for the basal transcriptional activity that regulated by the ER-α. With the applications of an electrophoresis mobility shift assay and a chromatin immunoprecipitation assay, we could successfully identify a specific ER-α binding element in the apoM promoter region.

Conculsion

In summary, the present study indicates that 17β-estradiol induced up-regulation of apoM in HepG2 cells is through an ER-α-dependent pathway involving ER-α binding element in the promoter of the apoM gene.

Gene-Environment Interactions of Circadian-Related Genes for Cardiometabolic Traits

OBJECTIVE

Common circadian-related gene variants associate with increased risk for metabolic alterations including type 2 diabetes. However, little is known about whether diet and sleep could modify associations between circadian-related variants (CLOCK-rs1801260, CRY2-rs11605924, MTNR1B-rs1387153, MTNR1B-rs10830963, NR1D1-rs2314339) and cardiometabolic traits (fasting glucose [FG], HOMA-insulin resistance, BMI, waist circumference, and HDL-cholesterol) to facilitate personalized recommendations.

RESEARCH DESIGN AND METHODS

We conducted inverse-variance weighted, fixed-effect meta-analyses of results of adjusted associations and interactions between dietary intake/sleep duration and selected variants on cardiometabolic traits from 15 cohort studies including up to 28,190 participants of European descent from the Cohorts for Heart and Aging Research in Genomic Epidemiology (CHARGE) Consortium.

RESULTS

We observed significant associations between relative macronutrient intakes and glycemic traits and short sleep duration (<7 h) and higher FG and replicated known MTNR1B associations with glycemic traits. No interactions were evident after accounting for multiple comparisons. However, we observed nominally significant interactions (all P < 0.01) between carbohydrate intake and MTNR1B-rs1387153 for FG with a 0.003 mmol/L higher FG with each additional 1% carbohydrate intake in the presence of the T allele, between sleep duration and CRY2-rs11605924 for HDL-cholesterol with a 0.010 mmol/L higher HDL-cholesterol with each additional hour of sleep in the presence of the A allele, and between long sleep duration (≥9 h) and MTNR1B-rs1387153 for BMI with a 0.60 kg/m(2) higher BMI with long sleep duration in the presence of the T allele relative to normal sleep duration (≥7 to <9 h).

CONCLUSIONS

Our results suggest that lower carbohydrate intake and normal sleep duration may ameliorate cardiometabolic abnormalities conferred by common circadian-related genetic variants. Until further mechanistic examination of the nominally significant interactions is conducted, recommendations applicable to the general population regarding diet—specifically higher carbohydrate and lower fat composition—and normal sleep duration should continue to be emphasized among individuals with the investigated circadian-related gene variants.

No association of G-protein-coupled receptor kinase 5 or β-adrenergic receptor polymorphisms with Takotsubo cardiomyopathy in a large Australian cohort

AIMS

Takotsubo cardiomyopathy (TC) is an increasingly recognized syndrome in which patients present with chest pain and ST changes, and are observed to have reversible LV apical ballooning in the absence of angiographically significant coronary artery stenosis. Although the pathophysiology remains unclear, the syndrome occurs almost exclusively in women, and is often triggered by stress. Recent small studies have reported association of TC with functional variants in the G-protein-coupled receptor kinase 5 (GRK5) gene, as well as in the β1-adrenergic receptor (β1AR) and β2AR.

METHODS AND RESULTS

We tested these associations in a larger cohort of 92 TC patients. In addition we examined for the association of polymorphisms in the oestrogen receptor α (ERα) and catechol-O-methyl transferase (COMT) with the occurrence of TC, by comparing the allele frequency of these variants in the TC cohort with that in previously genotyped large Caucasian cohorts. Ninety-two patients with TC were recruited from four Australian centres; they had an age range of 41-90 years (mean ± SD = 66.3 ± 9) and 89/92 were female. There were no significant differences in allelic frequency in the TC group vs. the historic control database for any of the loci.

CONCLUSION

In the largest genotyped TC cohort in the literature, we have found no association of genetic variants in the ERα, β1AR, β2AR, or COMT genes, or with the previously implicated GRK5, with occurrence of the syndrome.

Associations between polymorphisms in sex steroid related genes and autistic-like traits

Sex differences in psychiatric disorders are common, which is particularly striking in autism spectrum disorders (ASDs) that are four times more prevalent in boys. High levels of testosterone during early development have been hypothesized to be a risk factor for ASDs, supported by several studies showing fetal testosterone levels, as well as indirect measures of prenatal androgenization, to be associated with ASDs and autistic-like traits (ALTs). Further, the importance of sex steroid related genes in ASDs is supported by studies reporting associations between polymorphisms in genes involved in sex steroid synthesis/metabolism and ASDs and ALTs. The aim of the present study was to investigate possible associations between 29 single nucleotide polymorphisms (SNPs) in eight genes related to sex steroids and autistic features. Individuals included in the study belong to a subset (n=1771) from The Child and Adolescent Twin Study in Sweden (CATSS), which are all assessed for ALTs. For two SNPs, rs2747648 located in the 3'-UTR of ESR1 encoding the estrogen receptor alpha and rs523349 (Leu89Val) located in SRD5A2 encoding 5-alpha-reductase, type 2, highly significant associations with ALTs were found in boys and girls, respectively. The results of the present study suggest that SNPs in sex steroid related genes, known to affect gene expression (rs2747648 in ESR1) and enzymatic activity (Leu89Val in SRD5A2), seem to be associated with ALTs in a general population. In conclusion, the current findings provide further support for a role of sex steroids in the pathophysiology of ASDs.