Alcohol Exposure Causes Overexpression of Heart Development-Related Genes by Affecting the Histone H3 Acetylation via BMP Signaling Pathway in Cardiomyoblast Cells

Non-Smad, BMP-dependent signaling protects against the effects of acute ethanol toxicity

This study explores the effect of acute Ethanol (EtOH) exposure on Bone Morphogenetic Protein (BMP)-evoked intracellular signaling, and the concomitant morphological changes induced by EtOH in C2C12 cells and DRG (Dorsal root ganglion) neurons in an in vitro model related to Fetal Alcohol Syndrome Disorder (FASD). All assays were performed within 30 min of BMP stimulation to specifically investigate the earliest events occurring in BMP-evoked intracellular signaling pathways. We show that Smad phosphorylation and nuclear translocation stimulated by BMPs was not altered following acute exposure to EtOH. In contrast, acute EtOH exposure alone caused a striking concentration-dependent decrease in Akt phosphorylation, as well as a loss of adhesion in C2C12 cells. The addition of BMPs before exposure to EtOH was associated with maintenance of Akt phosphorylation, greater cell adhesion in C2C12 cells, and preservation of growth cone complexity in DRG neurons. Thus, for both C2C12 cells and DRG neurons, BMPs, acting through non-canonical BMP signaling pathways, appear to impart some protection against the profound effects of acute EtOH exposure on cellular adhesion and structure.

Acetylation in cardiovascular diseases: Molecular mechanisms and clinical implications

Acetylation belongs to a class of post-translational modification (PTM) processes that epigenetically regulate gene expression and gene transcriptional activity. Reversible histone acetylation on lysine residues governs the interactions between DNA and histones to mediate chromatin remodeling and gene transcription. Non-histone protein acetylation complicates cellular function whereas acetylation of key mitochondrial enzymes regulates bioenergetic metabolism. Acetylation and deacetylation of functional proteins are essential to the delicated homeostatic regulation of embryonic development, postnatal maturation, cardiomyocyte differentiation, cardiac remodeling and onset of various cardiovascular diseases including obesity, diabetes mellitus, cardiometabolic diseases, ischemia-reperfusion injury, cardiac remodeling, hypertension, and arrhythmias. Histone acetyltransferase (HATs) and histone deacetylases (HDACs) are essential enzymes mainly responsible for the regulation of lysine acetylation levels, thus providing possible drugable targets for therapeutic interventions in the management of cardiovascular diseases.

Novel Ethanol-Sensitive Mutants Identified in an F3 Forward Genetic Screen

Background

Fetal alcohol spectrum disorders (FASD) collectively refer to all deleterious outcomes due to prenatal alcohol exposures. Alterations to the face are common phenotypes in FASD. While alcohol exposure is the underlying cause of FASD, many variables modify the outcomes of such exposures. Genetic risk is one such variable, yet we still have a limited understanding of the nature of the genetic loci mediating susceptibility to FASD.

Methods

We employed ENU‐based random mutagenesis in zebrafish to identify mutations that enhanced the teratogenicity of ethanol (EtOH). F3 embryos obtained from 126 inbred F2 families were exposed to 1% EtOH in the medium (approximately 41 mM tissue levels). Zebrafish stained with Alcian Blue and Alizarin Red were screened for qualitative alterations to the craniofacial skeleton between 4 and 7 days postfertilization (dpf).

Results

In all, we recovered 6 EtOH‐sensitive mutants, 5 from the genetic screen itself and one as a background mutation in one of our wild‐type lines. Each mutant has a unique EtOH‐induced phenotype relative to the other mutant lines. All but 1 mutation appears to be recessive in nature, and only 1 mutant, au29, has apparent craniofacial defects in the absence of EtOH. To validate the genetic screen, we genetically mapped au29 and found that it carries a mutation in a previously uncharacterized gene, si:dkey‐88l16.3.

Conclusions

The phenotypes of these EtOH‐sensitive mutants differ from those in previous characterizations of gene–EtOH interactions. Thus, each mutant is likely to provide novel insights into EtOH teratogenesis. Given that most of these mutants only have craniofacial defects in the presence of EtOH and our mapping of au29, it is also likely that many of the mutants will be previously uncharacterized. Collectively, our findings point to the importance of unbiased genetic screens in the identification, and eventual characterization, of risk alleles for FASD.

G9α-dependent histone H3K9me3 hypomethylation promotes overexpression of cardiomyogenesis-related genes in foetal mice

Alcohol consumption during pregnancy can cause foetal alcohol syndrome and congenital heart disease. Nonetheless, the underlying mechanism of alcohol‐induced cardiac dysplasia remains unknown. We previously reported that alcohol exposure during pregnancy can cause abnormal expression of cardiomyogenesis‐related genes, and histone H3K9me3 hypomethylation was observed in alcohol‐treated foetal mouse heart. Hence, an imbalance in histone methylation may be involved in alcohol‐induced cardiac dysplasia. In this study, we investigated the involvement of G9α histone methyltransferase in alcohol‐induced cardiac dysplasia in vivo and in vitro using heart tissues of foetal mice and primary cardiomyocytes of neonatal mice. Western blotting revealed that alcohol caused histone H3K9me3 hypomethylation by altering G9α histone methyltransferase expression in cardiomyocytes. Moreover, overexpression of cardiomyogenesis‐related genes (MEF2C, Cx43, ANP and β‐MHC) was observed in alcohol‐exposed foetal mouse heart. Additionally, we demonstrated that G9α histone methyltransferase directly interacted with histone H3K9me3 and altered its methylation. Notably, alcohol did not down‐regulate H3K9me3 methylation after G9α suppression by short hairpin RNA in primary mouse cardiomyocytes, preventing MEF2C, Cx43, ANP and β‐MHC overexpression. These findings suggest that G9α histone methyltransferase‐mediated imbalance in histone H3K9me3 methylation plays a critical role in alcohol‐induced abnormal expression cardiomyogenesis‐related genes during pregnancy. Therefore, G9α histone methyltransferase may be an intervention target for congenital heart disease.

Parental alcohol consumption and the risk of congenital heart diseases in offspring: An updated systematic review and meta-analysis

OBJECTIVE

The aim of this study was to provide updated evidence to assess the association between parental alcohol consumption and the risk of total congenital heart diseases (CHDs) and specific CHD phenotypes in offspring, and explore the possible dose-response pattern.

METHODS

PubMed, Embase and Chinese databases were searched with an end-date parameter of July 24, 2019 to identify studies meeting pre-stated inclusion criteria. A random-effects model was used to calculate the overall combined risk estimates. A meta-analysis of the dose-response relationship was performed. Subgroup analysis, sensitivity analysis, and Galbraith plot were conducted to explore potential heterogeneity moderators.

RESULTS

A total of 55 studies involving 41,747 CHD cases and 297,587 controls were identified. Overall, both maternal (odds ratio (OR) = 1.16; 95% confidence interval (CI): 1.05-1.27) and paternal (OR = 1.44; 95% CI: 1.19-1.74) alcohol exposures were significantly associated with risk of total CHDs in offspring. Additionally, a nonlinear dose-response relationship between parental alcohol exposure and risk of total CHDs was observed. With an increase in parental alcohol consumption, the risk of total CHDs in offspring also gradually increases. For specific CHD phenotypes, a statistically significant association was found between maternal alcohol consumption and risk of tetralogy of fallot (OR = 1.20; 95% CI: 1.08-1.33). Relevant heterogeneity moderators have been identified by subgroup analysis, and sensitivity analysis yielded consistent results.

CONCLUSIONS

Although the role of potential bias and evidence of heterogeneity should be carefully evaluated, our review indicates that parental alcohol exposures are significantly associated with the risk of CHDs in offspring, which highlights the necessity of improving health awareness to prevent alcohol exposure during preconception and conception periods.

Molecular mechanism of FSHR expression induced by BMP15 in human granulosa cells

PURPOSE

Follicle-stimulating hormone receptor (FSHR) expression in granulosa cells is critical in enabling follicles to achieve accelerated growth. Although FSHR expression has been reported to be epigenetically regulated, the mechanism is unclear. Cooperation between oocytes and granulosa cells is also essential for normal follicular growth. Among oocyte-derived factors, bone morphogenetic protein 15 (BMP15) promotes follicular growth and is suggested to have epigenetic effects. We examined the role of BMP15 in the acquirement of FSHR in human granulosa cells.

METHODS

Immortalized non-luteinized human granulosa (HGrC1) cells were stimulated with trichostatin A (TSA) or BMP15 to analyze FSHR expression, histone modifications, and USF1/2 binding at the FSHR promoter region. Histone acetyl transferase (HAT) activity and phosphorylation of Smad 1/5/8 and p38 MAPK were examined with or without BMP15, SB203580, and LDN193189. CYP19A1 expression and estradiol production were also studied.

RESULTS

TSA and BMP15 induced FSHR mRNA expression in a dose-dependent manner and histone modifications were observed with increased binding of USF1/2. BMP15 increased FSHR protein expression, which was suppressed by LDN193189. BMP15 increased phosphorylation of Smad 1/5/8 and significantly increased HAT activity, which was inhibited by LDN193189, but not by SB203580. BMP15 increased phosphorylation of p38 MAPK and USF1. LDN193189 suppressed BMP15-induced phosphorylation of both p38 MAPK and USF1, whereas SB203580 suppressed the phosphorylation of USF1. BMP15 increased CYP19A1 mRNA expression and estradiol production.

CONCLUSION

BMP15 induced FSHR expression in human granulosa cells through Smad and non-Smad pathways. This mechanism of FSHR induction by BMP15 may be utilized for controlling follicular growth.

Genetic evaluation of patients with congenital heart disease

PURPOSE OF REVIEW

The aim of this study is to review genetics of congenital heart disease (CHD) with a focus on clinical applications, genetic testing and clinical challenges.

RECENT FINDINGS

With improved clinical care, there is a rapidly expanding population of adults, especially women, with CHD who have not undergone contemporary genetic assessment and do not understand their risk for having a child with CHD. Many patients have never undergone assessment or had genetic testing. A major barrier is medical geneticist availability, resulting in this burden of care shifting to providers outside of genetics. Even with current understanding, the cause for the majority of cases of CHD is still not known. There are significant gaps in knowledge in the realms of more complex causes such as noncoding variants, multigenic contribution and small structural chromosomal anomalies.

SUMMARY

Standard assessment of patients with CHD, including adult survivors, is indicated. The best first-line genetic assessment for most patients with CHD is a chromosomal microarray, and this will soon evolve to be genomic sequencing with copy number variant analysis. Due to lack of medical geneticists, creative solutions to maximize the number of patients with CHD who undergo assessment with standard protocols and plans for support with result interpretation need to be explored.

The role of histone modification and a regulatory single-nucleotide polymorphism (rs2071166) in the Cx43 promoter in patients with TOF

Abnormal level of Cx43 expression could result in CHD. Epigenetic modification and disease-associated, non-coding SNPs might influence gene transcription and expression. Our study aimed to determine the role of histone modification and an rSNP (rs2071166) in the Cx43 promoter in patients with TOF. Our results indicate that H3K18ac bind to Cx43 promoter and that their levels are reduced in TOF patients relative to controls. The relationship between the non-coding SNP in the Cx43 gene and TOF patients was evaluated in 158 patients and 300 controls. The C allele of rs2071166 was confirmed to result in an increased risk of TOF (OR = 1.586, 95%CI 1.149–2.189). Individuals with the CC genotype at rs2071166 also showed a significant susceptibility to TOF (OR = 2.961, 95%CI 1.452–6.038). The mRNA level in TOF who were CC genotype was lower than that in patients with the AA/AC genotype. Functional analysis in cells and transgenic zebrafish models showed that rs2071166 decreased the activity of the promoter and could block the interaction between RXRα and RARE. This is the first study to illustrate that epigenetic modification and an rSNP in the Cx43 promoter region play a critical role in TOF by impacting the transcriptional activity and expression level of Cx43.