A functional polymorphism of PON1 interferes with microRNA binding to increase the risk of ischemic stroke and carotid atherosclerosis

Association of genetic variations of 3'-UTR in clopidogrel pharmacokinetic-relevant genes with clopidogrel response in Han Chinese patients with coronary artery disease

Dual antiplatelet therapy with aspirin and clopidogrel has reduced ischemic vascular events significantly. Genetic influence, especially those in clopidogrel pharmacokinetic-relevant genes partially accounts for interindividual pharmacodynamic variability of clopidogrel. However, most studies have concentrated on the genetic variations in introns, exons, or promoters of the candidate genes, and the association between genetic variations in 3'-UTR in clopidogrel pharmacokinetic-relevant genes and clopidogrel response is unknown. In our study, ten different algorithms were applied to pick potential miRNAs targeting the clopidogrel pharmacokinetic-relevant genes. Furthermore, the correlation between miRNA expression profiles and mRNA expression of corresponding clopidogrel pharmacokinetic-relevant genes was analyzed. Through comprehensive analysis, including bioinformatics prediction and correlation analysis of miRNA and mRNA expression profiles, miR-218-5p and miR-506-5p were supposed to regulate the expression of PON1 via binding with its 3'-UTR. Moreover, PON1 rs854551 and rs854552 were located in miRNA recognizing sequences and may serve as potential miRSNPs possibly affecting PON1 expression. The rs854552 polymorphism was genotyped and platelet reactivity index (PRI) indicative of clopidogrel response was measured in 341 Chinese coronary artery disease (CAD) patients 24 h after administration of 300 mg clopidogrel. Our results showed that PON1 rs854552 had a significant influence on PRI in CAD patients, especially in patients with CYP2C19 extensive metabolic phenotype. In conclusion, PON1 rs854552 polymorphisms may affect clopidogrel response. Bioinformatics prediction followed by functional validation could aid in decoding the contribution of unexplained variations in the 3'-UTR in drug-metabolizing enzymes on clopidogrel response.

Pleiotropic functions and clinical importance of circulating HDL-PON1 complex

High density lipoprotein (HDL) functions are mostly mediated through a complex proteome, particularly its enzymes. HDL can provide a scaffold for the assembly of several proteins that affect each other's function. HDL particles, particularly small, dense HDL3, are rich in paraoxonase 1 (PON1), which is an important enzyme in the functionality of HDL, so the antioxidant and antiatherogenic properties of HDL are largely attributed to this enzyme. There is an increasing need to represent a valid, reproducible, and reliable method to assay HDL function in routine clinical laboratories. In this context, HDL-associated proteins may be key players; notably PON1 activity (its arylesterase activity) may be a proper candidate because its decreased activity can be considered an important risk factor for HDL dysfunctionality. Of note, automated methods have been developed for the measurement of serum PON1 activity that facilitates its assay in large sample numbers. Arylesterase activity is proposed as a preferred activity among the different activities of PON1 for its assay in epidemiological studies. The binding of PON1 to HDL is critical for the maintenance of its activity and it appears apolipoprotein A-I plays an important role in HDL-PON1 interaction as well as in the biochemical and enzymatic properties of PON1. The interrelationships between HDL, PON1, and HDL's other components are complex and incompletely understood. The purpose of this review is to discuss biochemical and clinical evidence considering the interactions of PON1 with HDL and the role of this enzyme as an appropriate biomarker for HDL function as well as a potential therapeutic target.

H2S-mediated inhibition of RhoA/ROCK pathway and noncoding RNAs in ischemic stroke

Ischemic stroke is one of major causes of disability. In the pathological process of ischemic stroke, the up-regulation of Ras homolog gene family, member A (RhoA) and its downstream effector, Ras homolog gene family (Rho)-associated coiled coil-containing kinase (ROCK), contribute to the neuroinflammation, blood-brain barrier (BBB) dysfunction, neuronal apoptosis, axon growth inhibition and astrogliosis. Accumulating evidences have revealed that hydrogen sulphide (H₂S) could reduce brain injury in animal model of ischemic stroke via inhibiting the RhoA/ROCK pathway. Recently, noncoding RNAs (ncRNAs) such as circular RNAs (circRNAs), long noncoding RNAs (lncRNAs) and microRNAs (miRNAs) have attracted much attention because of their essential role in adjusting gene expression both in physiological and pathological conditions. Numerous studies have uncovered the role of RhoA/ROCK pathway and ncRNAs in ischemic stroke. In this review, we focused on the role of H₂S, RhoA/ROCK pathway and ncRNAs in ischemic stroke and aimed to reveal new strategies for preventing and treating this devastating disease.

[Interaction between ischemic stroke risk loci identified by genome-wide association studies and sleep habits]

OBJECTIVE

To explore the relationship between sleep habits (sleep duration, sleep efficiency, sleep onset timing) and ischemic stroke, and whether there is an interaction between sleep habits and ischemic stroke susceptibility gene loci.

METHODS

A questionnaire survey, physical examination, blood biochemical testing and genotyping were conducted among rural residents in Beijing, and the gene loci of ischemic stroke suggested by previous genome-wide association studies (GWAS) were screened. Multivariable generalized linear model was used to analyze the correlation between sleep habits, sleep-gene interaction and ischemic stroke.

RESULTS

A total of 4 648 subjects with an average age of (58.5±8.7) years were enrolled, including 1 316 patients with ischemic stroke. Compared with non-stroke patients, stroke patients with sleep duration ≥9 hours, sleep efficiency < 80%, and sleep onset timing earlier than 22:00 accounted for a higher proportion (P < 0.05). There was no significant association between sleep duration and risk of ischemic stroke (OR=1.04, 95%CI: 0.99-1.10, P=0.085). Sleep efficiency was inversely associated with the risk of ischemic stroke (OR=0.18, 95%CI: 0.06-0.53, P=0.002). The risk of ischemic stroke in the subjects with sleep efficiency < 80% was 1.47-fold (95%CI: 1.03-2.10, P=0.033) of that in the subjects with sleep efficiency ≥80%. Falling asleep earlier than 22:00 was associated with 1.26 times greater risk of stroke than falling asleep between 22:00 and 22:59 (95%CI: 1.04-1.52, P=0.017). Multifactorial adjustment model showed that rs579459 on ABO gene had an interaction with sleep time (P for interaction =0.040). When there were two T alleles for rs579459 on the ABO gene, those who fell asleep before 22:00 had 1.56 times (95%CI: 1.20-2.04, P=0.001) the risk of stroke compared with those who fell asleep between 22:00 and 22:59, and there was no significant difference when the number of pathogenic alleles was 0 or 1. In the model adjusted only for gender, age and family structure, sleep duration and the number of T allele rs2634074 on PITX2 gene had an interaction with ischemic stroke (P for interaction=0.033).

CONCLUSION

Decreased sleep efficiency is associated with increased risk of ischemic stroke, and falling asleep earlier than 22:00 is associated with higher risk of ischemic stroke. Sleep onset timing interacted with rs579459 in ABO gene and the risk of ischemic stroke. Sleep duration and PITX2 rs2634074 may have a potential interaction with ischemic stroke risk.

The Relationship between Cancer and Paraoxonase 1

Extensive research has been carried out to understand and elucidate the mechanisms of paraoxonase 1 (PON1) in the development of diseases including cancer, cardiovascular diseases, neurological diseases, and inflammatory diseases. This review focuses on the relationship between PON1 and cancer. The data suggest that PON1, oxidative stress, chronic inflammation, and cancer are closely linked. Certainly, the gene expression of PON1 will remain challenging to study. Therefore, targeting PON1, redox-sensitive pathways, and transcription factors promise prevention and therapy in the development of several diseases, including cancer.

Proteomics-Based Approach to Identify Novel Blood Biomarker Candidates for Differentiating Intracerebral Hemorrhage From Ischemic Stroke-A Pilot Study

Background: A reliable distinction between ischemic stroke (IS) and intracerebral hemorrhage (ICH) is required for diagnosis-specific treatment and effective secondary prevention in patients with stroke. However, in resource-limited settings brain imaging, which is the current diagnostic gold standard for this purpose, is not always available in time. Hence, an easily accessible and broadly applicable blood biomarker-based diagnostic test differing stroke subtypes would be desirable. Using an explorative proteomics approach, this pilot study aimed to identify novel blood biomarker candidates for distinguishing IS from ICH.

Material and Methods: Plasma samples from patients with IS and ICH were drawn during hospitalization and were analyzed by using liquid chromatography/mass spectrometry. Proteins were identified using the human reference proteome database UniProtKB, and label-free quantification (LFQ) data were further analyzed using bioinformatic tools.

Results: Plasma specimens of three patients with IS and four patients with ICH with a median National Institute of Health Stroke Scale (NIHSS) of 12 [interquartile range (IQR) 10.5–18.5] as well as serum samples from two healthy volunteers were analyzed. Among 495 identified protein groups, a total of 368 protein groups exhibited enough data points to be entered into quantitative analysis. Of the remaining 22 top-listed proteins, a significant difference between IS and ICH was found for Carboxypeptidase N subunit 2 (CPN2), Coagulation factor XII (FXII), Plasminogen, Mannan-binding lectin serine protease 1, Serum amyloid P-component, Paraoxonase 1, Carbonic anhydrase 1, Fibulin-1, and Granulins.

Discussion: In this exploratory proteomics-based pilot study, nine candidate biomarkers for differentiation of IS and ICH were identified. The proteins belong to the immune system, the coagulation cascade, and the apoptosis system, respectively. Further investigations in larger cohorts of patients with stroke using additional biochemical analysis methods, such as ELISA or Western Blotting are now necessary to validate these markers, and to characterize diagnostic accuracy with regard to the development of a point-of-care-system for use in resource-limited areas.

Influence of the rs6736 Polymorphism on Ischemic Stroke Susceptibility in Han Chinese Individuals via the Disruption of miR-7-1 Binding to the C14orf119 Gene

This study investigates the association between the C14orf119 gene rs6736 polymorphism and ischemic stroke (IS) susceptibility, and explores the influence of the rs6736 polymorphism on the binding between miR-7-1 and the C14orf119 gene. mRNA expression levels were determined in 45 IS patients and 45 matched controls via real-time quantitative PCR. A total of 774 IS patients and 793 matched controls were recruited from a Han Chinese population for genotyping, performed with the Sequenom MassARRAY iPLEX platform. A dual-luciferase reporter assay was used for the analysis of miRNA-mRNA binding. The results showed that the mRNA expression of C14orf119 differed significantly between IS patients and controls (t =  -2.235, P = 0.030). Significant associations were noted between the C14orf119 gene rs6736 polymorphism and IS susceptibility in Han Chinese individuals under the additive model [OR_adj (95% CI) = 0.87 (0.76-1.00) P_adj = 0.048] and dominant model [OR_adj (95% CI) = 0.76 (0.61-0.94), P_adj = 0.014], with adjustment for age and sex. Mutations in the rs6736 polymorphism disrupted the binding of miR-7-1 and the C14orf119 gene. The results of this study show that the rs6736 polymorphism in the 3'-untranslated region of the C14orf119 gene not only is associated with IS but also modifies the binding between miR-7-1 and the C14orf119 gene. The C14orf119 gene may participate in the relationship between IS and miR-7-1.

Paraoxonase-1 (PON1) Status Analysis Using Non-Organophosphate Substrates

Human paraoxonase-1 (PON1) is a high-density lipoprotein-associated enzyme with antioxidant, anti-inflammatory, and antiapoptotic roles. The ability of PON1 to hydrolyze specific organophosphate (OP) compounds and prevent accumulation of oxidized lipids in lipoproteins has prompted a large number of studies investigating PON1's role in modulating toxicity and disease. Most of these studies, however, have only focused on PON1 single nucleotide polymorphism analyses and have ignored PON1 activity levels, arguably the most important parameter in determining protection against exposure and disease. We developed a two-substrate activity assay termed "PON1 status" that reveals both the functional PON1₁₉₂ genotype and plasma PON1 activity levels. While our previous studies with PON1 status demonstrated that both PON1₁₉₂ functional genotype and enzymatic activity levels obtained exclusively by determining PON1 status are required for a proper evaluation of PON1's role in modulating OP exposures and risk of disease, the original PON1 status assay requires the use of highly toxic OP metabolites. As many laboratories are not prepared to handle such toxic compounds and the associated waste generated, determination of PON1 status has been limited to rather few studies. Here, we describe a PON1 status protocol that uses non-OP substrates with a resolution equivalent to that of the original PON1 status approach. We have also included useful suggestions to ensure the assays can easily be carried out in any laboratory. The protocols described here will enable a proper examination of the risk of exposure or susceptibility to disease in PON1 epidemiological studies without the need to handle highly toxic substrates. © 2021 Wiley Periodicals LLC. Basic Protocol: Determining PON1 status using non-organophosphate substrates Support Protocol 1: Experimental pathlength determination Support Protocol 2: PON1 DNA genotyping for the Q192R (rs662) polymorphism.

Apoptosis in HUVECs induced by microRNA-616-3p via X-linked inhibitor of apoptosis protein targeting

Atherosclerosis causes stroke and coronary heart disease and is associated with a high mortality rate worldwide. However, the pathogenesis of atherosclerosis remains unclear. Endothelial cell apoptosis is one of the early changes observed in atherosclerosis. Previous studies have found that microRNA (miR)-616-3p may be involved in the development of atherosclerosis, but the specific mechanism is not clear. The present study aimed to investigate whether miR-616-3p is involved in endothelial cell apoptosis and its underlying mechanism. The present study demonstrated that compared with normal HUVECs, HUVECs treated with oxidized low-density lipoprotein expressed higher miR-616-3p and lower X-linked inhibitor of apoptosis protein (XIAP) levels. In the present study, HUVECs were transfected with miR-616-3p mimic and Cell Counting Kit-8 (CCK-8), flow cytometry and TUNEL staining assays demonstrated that compared with miR-616-3p mimic control, the miR-616-3p mimic promoted HUVEC apoptosis. In addition, using StarBase 3.0 for bioinformatics analysis it was predicted that miR-616-3p may bind to the 3'untranslated region (UTR) of XIAP mRNA. The present study performed the CCK-8, flow cytometry, TUNEL staining and dual-luciferase reporter assays and demonstrated that miR-616-3p binds to the 3'UTR of the XIAP mRNA and inhibits its expression and that this further promotes apoptosis in HUVECs. In addition, western blotting demonstrated that compared with miR-616-3p mimic control, the miR-616-3p mimic increases the level of cleaved caspase-3 in HUVECs. In summary, the present study demonstrated that miR-616-3p can directly inhibit the expression of XIAP mRNA by targeting its 3'UTR which promoted apoptosis in HUVECs. miR-616-3p and XIAP may be used as therapeutic targets of atherosclerosis in the future.

A 3' Untranslated Region Polymorphism of CTNNB1 (Rs2953) Alters MiR-3161 Binding and Affects the Risk of Ischemic Stroke and Coronary Artery Disease in Chinese Han Population

BACKGROUND

CTNNB1 is reported to be related to the pathological process of ischemic stroke (IS) and coronary artery disease (CAD). Polymorphism located in the 3' untranslated region (3'UTR) of a gene might affect gene expression by modifying binding sites for microRNAs (miRNAs). This study aimed to analyze the association between polymorphism rs2953, which locates in the 3'UTR of CTNNB1, and the risk of IS and CAD.

METHODS

The CTNNB1 messenger RNA (mRNA) expression level in peripheral venous blood was measured. In total, 533 patients with IS, 500 patients with CAD, and 531 healthy individuals were genotyped by Sequenom Mass-Array technology. The binding of miR-3161 to CTNNB1 was determined by dual-luciferase reporter assay.

RESULTS

The CTNNB1 mRNA expression level for the IS group was significantly lower than that for the control group. Rs2953 was significantly associated with both IS risk and CAD risk. Significant association was also found between polymorphism rs2953 and many conventional factors, such as serum lipid level, blood coagulation markers, blood glucose level, and homocysteine level in patients. Rs2953 T allele introduced a binding site to miRNA-3161 and thus decreased luciferase activity.

CONCLUSION

Polymorphism rs2953 is associated with the risk of both IS and CAD. Moreover, polymorphism rs2953 (T) introduces a binding site to miRNA-3161 and thus decreases luciferase activity in cell lines.

The Relevance of Noncoding DNA Variations of Paraoxonase Gene Cluster in Atherosclerosis-Related Diseases

The human paraoxonase (PON) gene cluster is comprised of three contiguous genes (PON1, PON2 and PON3) of presumably common origin coding three lactonases of highly similar structure and substrate specificity. The catalytic activity of PON proteins is directed toward artificial organophosphates and in physiological conditions toward thiolactones and oxidized phospholipids. Consequently, PON enzymes are regarded as an effective defense against oxidative stress and, as a result, against atherosclerosis development. Additionally, both PON's serum activity and its concentration are influenced by several polymorphic variations in coding and noncoding DNA regions of the PON gene cluster remaining in linkage disequilibrium. Hence, the genetic polymorphism of the PON gene cluster may contribute to atherosclerotic process progression or deceleration. In this review the authors analyzed the relevance of noncoding DNA polymorphic variations of PON genes in atherosclerosis-related diseases involving coronary and peripheral artery disease, stroke, diabetes mellitus, dementia and renal disease and concluded that the effect of PON gene cluster' polymorphism has a considerable impact on the course and outcome in these conditions. The following PON genetic variations may serve as additional predictors of the risk of atherosclerosis in selected populations and individuals.

Network and Pathway-Based Integrated Analysis Identified a Novel "rs28457673-miR-15/16/195/424/497 Family-IGF1R-MAPK Signaling Pathway" Axis Associated With Post-stroke Depression

Single-nucleotide polymorphisms (SNPs) of microRNA (miRNA) (miRSNP) are SNPs located on miRNA genes or miRNA target sites, which have been supposed to be involved in the development of central nervous system diseases by interfering with miRNA-mediated regulatory functions. However, the association of miRSNP with post-stroke depression (PSD) has not been well-investigated. In this study, we collected 54 PSD risk genes via manual literature-mining and integrated PSD-related risk pathways based on multiple public databases. Furthermore, we systematically screened candidate functional miRSNPs for PSD and integrated a miRSNP-based PSD-associated pathway network, which included 99 miRNAs that target 12 PSD risk pathways. We also reviewed the association between three risk pathways and PSD pathogenetic mechanism thoroughly. Combining literature mining and network analysis, our results proposed an underlying mechanism of "miRSNP → miRNA → risk gene → pathway" axis effects on PSD pathogenesis, especially for rs28457673 (miR-15/16/195/424/497 family) → IGF1R → hsa04010 (MAPK signaling pathway). Our studies revealed a functional role in genetic modifier at the system level in the pathogenesis of PSD, which might provide further information for the miRSNP studies in PSD.

Susceptibility of PON1/PON2 Genetic Variations to Ischemic Stroke Risk in a Chinese Han Population

Background

Paraoxonases (PONs) are a family of orphan enzymes with multiple functions, including anti-inflammatory, antioxidative, antiatherogenic activities. Studies have suggested that genetic variations in PON1 and PON2 are associated with ischemic stroke (IS) risk; however, the conclusion remains unclear in the Chinese population.

Methods

To investigate the susceptibility of genetic variations in PON1 and PON2 to risk of IS and its subtypes, this case–control study was carried out on a Chinese population comprising 300 IS patients and 300 healthy controls. Genotypes of six genetic variations in PON1 and PON2 were identified with an improved multiplex ligase detection–reaction technique.

Results

PON1 rs662 was associated with increased risk of IS (CT vs. TT — OR_adjusted 1.79, 95% CI 1.08–2.97; p=0.025). Stratified analysis for patients by sex revealed that the significant association of PON1 rs662 with IS risk was maintained in the male cohort (CT vs. TT — OR_adjusted 2.59, 95% CI 1.29–5.21 [p=0.009]; CT/CC vs. TT — OR_adjusted 2.03, 95% CI 1.05–3.93 [p=0.036]), but not in the female cohort. Analysis according to IS subtype revealed that PON1 rs662 genetic variation was an increased risk in the subcohort of patients with large-artery atherosclerosis (CT/CC vs. TT — OR_adjusted 2.31, 95% CI 1.09–4.91; p=0.029), but not in patients with other types of IS.

Conclusion

This study suggested that PON1 rs662 presented a potential risk of IS, especially for males, and this association was more obvious for large-artery atherosclerosis.

Epigenetics of paraoxonases

PURPOSE OF REVIEW

Studies have shown the three-member paraoxonase (PON) multigene family to be involved in the development of a large variety of diseases with an inflammatory component. Environmental factors such as lifestyle-related factors differ widely between populations and it is important to consider that their impacts may be exerted through the epigenetic mechanisms, which connect genes, the environment and disease development and are a potential therapeutic avenue.

RECENT FINDINGS

In the review period, very little was published on epigenetics of PON2 or PON3, mostly on their diagnostic value in cancer by measuring methylation levels of these genes. However, the picture is more promising with PON1. Here, several studies have linked the epigenetic regulation of PON1 to various metabolic processes and particularly to the development of several diseases, including stroke, heart disease, aortic valve stenosis and chronic obstructive pulmonary disease.

SUMMARY

Studies into the epigenetic regulation of the PON family are in their infancy. However, recent studies linking epigenetic regulation of PON1 to disease development will encourage further research and open up the possibility for new potential therapeutic interventions.

The effects of oxidative stress on the development of atherosclerosis

Atherosclerosis is a cardiovascular disease (CVD) known widely world wide. Several hypothesizes are suggested to be involved in the narrowing of arteries during process of atherogenesis. The oxidative modification hypothesis is related to oxidative and anti-oxidative imbalance and is the most investigated. The aim of this study was to review the role of oxidative stress in atherosclerosis. Furthermore, it describes the roles of oxidative/anti-oxidative enzymes and compounds in the macromolecular and lipoprotein modifications and in triggering inflammatory events. The reactive oxygen (ROS) and reactive nitrogen species (RNS) are the most important endogenous sources produced by non-enzymatic and enzymatic [myeloperoxidase (MPO), nicotinamide adenine dinucleotide phosphate (NADH) oxidase and lipoxygenase (LO)] reactions that may be balanced with anti-oxidative compounds [glutathione (GSH), polyphenols and vitamins] and enzymes [glutathione peroxidase (Gpx), peroxiredoxins (Prdx), superoxide dismutase (SOD) and paraoxonase (PON)]. However, the oxidative and anti-oxidative imbalance causes the involvement of cellular proliferation and migration signaling pathways and macrophage polarization leads to the formation of atherogenic plaques. On the other hand, the immune occurrences and the changes in extra cellular matrix remodeling can develop atherosclerosis process.

The Effects of Anthocyanins and Their Microbial Metabolites on the Expression and Enzyme Activities of Paraoxonase 1, an Important Marker of HDL Function

High circulating HDL concentrations and measures of various HDL functions are inversely associated with cardiovascular disease (CVD) risk. Paraoxonase 1 (PON1) contributes to many of the athero-protective functions of HDL, such as promoting the reverse cholesterol transport process and reducing the levels of oxidized LDL. PON1 activities are influenced by several factors, the most important being diet and genetic polymorphisms. Reported data from randomized controlled trials have shown that anthocyanin consumption increased PON1 activity. However, the underlying molecular mechanisms by which anthocyanins increase PON1 activity are not understood. Therefore, the aim of this research was to investigate the ability of anthocyanins and their metabolites to increase PON1 gene expression and/or enzyme activities as potential mechanisms. The effect of the two predominant dietary anthocyanins and 18 of their recently identified microbial metabolites including their phase-II conjugates on PON1 gene expression was studied using a PON1-Huh7 stably-transfected cell line and reporter gene assay. The effects of these compounds on PON1 arylesterase and lactonase activities were investigated using two isoforms of the PON1 enzyme that are the phenotypes of the 192Q/R polymorphism. None of the compounds caused even modest changes in PON1 promoter activity (p ≥ 0.05). Further, none of the compounds at physiological concentrations caused any significant changes in the arylesterase or lactonase activity of either of the iso-enzymes. Cyanidin reduced the lactonase activity of the PON1-R192R enzyme at high concentrations (−22%, p < 0.001), but not at physiologically achievable concentrations. In conclusion, none of the data reported here support the notion that anthocyanins or their metabolites affect PON1 transactivation or enzyme activities.

The epigenetic regulation of paraoxonase 1 (PON1) as an important enzyme in HDL function: The missing link between environmental and genetic regulation

BACKGROUND

Paraoxonase 1 (PON1) is an important antiatherogenic and antioxidant enzyme in the circulation that has been associated with adverse health outcomes particularly cardiovascular disease (CVD) and other metabolic disorders. PON1 is a highly promiscuous enzyme and can hydrolyse a large variety of substrates, however, detailed structure/function studies have concluded that the natural substrates for PON1 are lipophilic lactones. The interindividual variability in PON1 activity has been mainly attributed to genetic determinants; however, it appears that the contribution of epigenetics has been ignored as a result of the lack of adequate research.

CONTENT

Epigenetic processes, including the histone modifications in the PON1 gene, the methylation of CpG sites in the promoter region of the PON1 gene and the microRNA modulation of PON1 expression can be responsible for the under researched gap between the environmental and genetic regulation of PON1. Environmental factors, including diet, pollution and lifestyle-related factors widely differ between individuals and populations and can cause large differences in the distribution of PON1 and it is important to note that their effects may be exerted through the epigenetic processes. This review discusses and emphasizes the importance of the epigenetic regulation of PON1 as a less-studied subject to highlight future research landscapes.

SUMMARY

Epigenetic regulation is known as an important contributor to the pathogenesis of human diseases, particularly multifactorial diseases such as CVD, which is life-threatening. Due to the importance of PON1 in the functionality of high-density lipoprotein (HDL) and its association with CVD, further explorations of its epigenetic regulation using advanced methods such as Methyl-Seq may lead to the identification of new epigenetic contributors that in turn may lead to targeted therapies.

MiR-21 binding site SNP within ITGAM associated with psoriasis susceptibility in women

BACKGROUND

Great progress has been made in the understanding of inflammatory processes in psoriasis. However, clarifying the role of genetic variability in processes regulating inflammation, including post-transcriptional regulation by microRNA (miRNA), remains a challenge.

OBJECTIVES

We therefore investigated single nucleotide polymorphisms (SNPs) with a predicted change in the miRNA/mRNA interaction of genes involved in the psoriasis inflammatory processes.

METHODS

Studied SNPs rs2910164 C/G-miR-146a, rs4597342 T/C-ITGAM, rs1368439 G/T-IL12B, rs1468488 C/T-IL17RA were selected using a bioinformatics analysis of psoriasis inflammation-associated genes. These SNPs were then genotyped using a large cohort of women with psoriasis (n = 241) and healthy controls (n = 516).

RESULTS

No significant association with psoriasis was observed for rs2910164, rs1368439, and rs1468488 genotypes. However, the major allele T of rs4597342 -ITGAM was associated with approximately 28% higher risk for psoriasis in comparison to the patients with the C allele (OR = 1.28, 95% CI 1.01-1.61, p = 0.037). In case of genotypes, the effect of the T allele indicates the dominant model of disease penetrance as the CT and TT genotypes increase the chance of psoriasis up to 42% in comparison to CC homozygotes of rs4597342 (OR = 1.42, 95% CI = 1.05-1.94, p = 0.025).

CONCLUSION

SNP rs4597342 in 3'UTR of ITGAM influencing miR-21 binding may be considered a risk factor for psoriasis development. Upregulated miR-21 in psoriasis is likely to inhibit CD11b production in the case of the rs4597342 T allele which may lead to Mac-1 dysfunction, resulting in an aberrant function of innate immune cells and leading to the production of cytokines involved in psoriasis pathogenesis.

MicroRNA binding mediated Functional sequence variant in 3'-UTR of DNA repair Gene XPC in Age-related Cataract

DNA oxidative damage repair is strongly involved in the pathogenesis of age-related cataract (ARC). The sequence variants of in coding region of DNA repair genes have been shown to be associated with ARC. It is known that single nucleotide polymorphisms (SNPs) in the 3′-terminal untranslated region (3′-UTR) can alter the gene expression by binding with microRNAs (miRNAs). We hypothesize that SNP(s) in miRNA binding site of certain DNA oxidative damage repair genes might associate with ARC risk. We examined 10 miRNA binding SNPs in 3′-UTR of 7 oxidative damage genes and revealed the XPC- rs2229090 C allele was associated with nuclear type of ARC (ARNC) risk in Chinese population. The individuals with the variant G allele (CG and GG) of XPC- rs2229090 had higher XPC mRNA expression compared to individuals carrying CC genotype. The in vitro assay showed that luciferase reporter gene expression can be down regulated by hsa-miR-589-5p in cells transfected with rs2229090 C allele compared to G allele. These results suggested that the C allele of XPC-2229090 increase the risk with ARNC. The mechanism underlying might be due to the stronger interation of the C allele with hsa-miR-589-5p, resulting in lower XPC expression and DNA repair capability than the individuals carring G allele in lens.

Antioxidants in the Fight Against Atherosclerosis: Is This a Dead End?

PURPOSE OF REVIEW

The purpose of this review is to focus on the outcome of recent antioxidant interventions using synthetic and naturally occurring molecules established as adjuvant strategies to lipid-lowering or anti-inflammatory therapies designed to reduce the risk of cardiovascular disease.

RECENT FINDINGS

To date, accumulated evidence regarding oxidation as a pro-atherogenic factor indicates that redox biochemical events involved in atherogenesis are indeed a very attractive target for the management of cardiovascular disease in the clinic. Nevertheless, although evidence indicates that redox reactions are important in the initiation and progression of atherosclerosis, oxidation with a pro-atherogenic context does not eliminate the fact that oxidation participates in many cases as an essential messenger of important cellular signaling pathways. Therefore, disease management and therapeutic goals require not only high-precision and high-sensitivity methods to detect in plasma very low amounts of reducing and oxidizing molecules but also a much better understanding of the normal processes and metabolic pathways influenced and/or controlled by oxidative stress. As several methodologies have been specifically described for the quantification of the total antioxidant capacity and the oxidation state of diverse biological systems, a successful way to carefully study how redox reactions influence atherosclerosis can be achieved. Since there is still a lack of standardization with many of these methods, clinical trials studying antioxidant capacity have been difficult to compare and therefore difficult to use in order to reach a conclusion. We believe a comprehensive analysis of new knowledge and its relationship with the presence of plasma antioxidants and their reducing capacity will undoubtedly open new ways to understand and develop new therapeutic pathways in the fight not only against atherosclerosis but also against other degenerative diseases.

Cholesterol reduction and macrophage function: role of paraoxonases

PURPOSE OF REVIEW

Unregulated uptake of oxidized LDL by macrophages to form foam cells is the hallmark for atherosclerosis. The paraoxonase (PON) family of enzymes plays a critical role in attenuating atherosclerotic lesion formation by hydrolyzing lipid peroxides (LOOHs) and preventing the oxidation of LDL particles and by enhancing HDL-mediated cholesterol efflux. Findings in recent years suggest novel mechanisms by which PON isoforms interact with macrophages to regulate cholesterol metabolism and cellular function.

RECENT FINDINGS

The association of PON with HDL particles facilitates binding of the particle to macrophages and ABCA1-dependent cholesterol efflux. The hydrolysis of membrane phospholipids by PON generates lysophosphatidylcholine which is shown to regulate expression of cholesterol transport proteins. The PON family also regulates multiple aspects of macrophage function. PON attenuates inflammation and prevents induction of apoptosis via activation of a scavenger receptor class B type-1-dependent signaling mechanism. PON limits macrophage-dependent oxidant formation by preventing the activation of the membrane-associated NADPH oxidase and by stabilizing mitochondria. PON also promotes the differentiation of macrophages to an anti-inflammatory phenotype. This function appears to be independent of PON enzymatic activity and, rather, is dependent on the ability of endogenous sulfhydryls to neutralize pro-inflammatory peroxides.

SUMMARY

In recent years, the therapeutic efficacy of HDL-based therapies has been subject to dispute. Pharmacological approaches that target an increase in the expression and/or activity of PON may facilitate macrophage cholesterol metabolism and attenuate inflammatory injury.

Association of carotid atherosclerosis and recurrent cerebral infarction in the Chinese population: a meta-analysis

Stroke, when poor blood flow to the brain results in cell death, is the third leading cause of disability and mortality worldwide, and appears as an unequal distribution in the global population. The cumulative risk of recurrence varies greatly up to 10 years after the first stroke. Carotid atherosclerosis is a major risk factor for stroke. The aim of this study was to investigate and estimate the relationship between carotid atherosclerosis and risk of stroke recurrence in the Chinese population. We performed a systematic review and meta-analysis of randomized controlled trials published from 2000 to 2013, using the following databases: PubMed, Embase, Medline, Wanfang, and the China National Knowledge Infrastructure. The odds ratios with 95% confidence intervals were calculated to examine this strength. A total of 22 studies, including 3,912 patients, 2,506 first-ever cases, and 1,406 recurrent cases, were pooled in this meta-analysis. Our results showed that the frequency of carotid atherosclerosis is higher in recurrent cases than that in the first-ever controls (78.88% vs 59.38%), and the statistical analysis demonstrated significant positive association between carotid atherosclerosis and recurrent cerebral infarction (odds ratio: 2.87; 95% confidence interval: 2.42-3.37; P<0.00001) in a fixed-effect model. No significant heterogeneity was observed across all studies. In conclusion, our results showed that carotid atherosclerosis was associated with increased risk of recurrent stroke. However, further well-designed research with large sample sizes is still needed to identify the clear mechanism.

Functional SNP in 3'-UTR MicroRNA-Binding Site of ZNF350 Confers Risk for Age-Related Cataract

Many studies have suggested that individual susceptibility to age-related cataract (ARC) may be associated with DNA sequence polymorphisms affecting gene regulation. As DNA repair is implicated in ARC pathogenesis and single-nucleotide polymorphisms (SNPs) in the 3'-terminal untranslated region (3'-UTR) targeted by microRNAs (miRNAs) can alter the gene function, we hypothesize that the miRNA-binding SNPs (miRSNPs) in DNA double-strand break repair (DSBR) and nucleotide excision repair (NER) pathways might associate with ARC risk. We genotyped nine miRSNPs of eight genes in DSBR and NER pathways in Chinese population and found that ZNF350- rs2278414:G>A was significantly associated with ARC risk. Even though the Comet assay of cellular DNA damage indicated that all the subtypes of ARC patients had more DNA breaks in peripheral lymphocytes than the controls independent of rs2278414 genotypes, individuals carrying the variant A allele (AA and AG) had lower ZNF350 mRNA levels compared with individuals with GG genotype. Moreover, the in vitro experiment indicated that miR-21-3p and miR-150-5p specifically downregulated luciferase reporter expression in the cell lines transfected with rs2278414 A allele compared with rs2278414 G. These results suggested that the association of SNP rs2278414 with ARC might involve an altered miRNA regulation of ZNF350.

Dysfunctional HDL in acute stroke

BACKGROUND AND AIMS

HDL-cholesterol concentration is a reliable negative risk factor for acute cerebral infarction (ACI). Beyond quantitative aspects, our aim was to determine whether lipoprotein profiles and HDL functionality were altered at the acute phase of ischemic stroke.

METHODS

Blood was taken from ACI patients within 4.5 h of symptom onset. Lipoproteins were separated by electrophoresis for determination of particle size. HDLs were isolated from plasma of patients (n = 10) and controls (n = 10) by ultracentrifugation. The relative amounts of paraoxonase 1 (PON1), α1antitrypsin (AAT) and myeloperoxidase (MPO) were determined by Western blot. HDL functional assays were performed on human-brain endothelial cells stimulated with TNFα.

RESULTS

Stroke patients had higher proportion of large HDL particles relative to controls (37.8 ± 11.8 vs. 28.4 ± 6.6, p = 0.04). HDLs from patients contained significantly less ApoA1 (1.63 ± 0.42 vs. 2.54 ± 0.71 mg/mL, p = 0.0026) and PON1 (4598 ± 1921 vs. 6598 ± 1127 AU, p = 0.01) than those from controls, whereas MPO and AAT were more abundant in HDLs isolated from ACI patients (respectively 3657 ± 1457 vs. 2012 ± 1234 and 3347 ± 917 vs. 2472 ± 470 AU, p = 0.014 and p = 0.015). HDLs reduced the expression of VCAM1, MCP1 and MMP3 mRNA induced by TNFα in blood-brain barrier endothelial cells. HDLs from patients were less effective in inhibiting TNFα-induced transcription of these genes (respectively 38.6 vs. 55.6% for VCAM1, p = 0.047, 44 vs. 48.1% for MCP1, p = 0.015 and 70 vs. 74% for MMP3, p = 0.024).

CONCLUSIONS

ACI may be associated with a modified distribution of HDL particles (increased proportion of large particles) and HDL-binding proteins, resulting in an inappropriate protection of endothelial cells under ischemic conditions.

Insulin-like growth factors and their potential role in cardiac epigenetics

Cardiovascular disease (CVD) constitutes a major public health threat worldwide, accounting for 17.3 million deaths annually. Heart disease and stroke account for the majority of healthcare costs in the developed world. While much has been accomplished in understanding the pathophysiology, molecular biology and genetics underlying the diagnosis and treatment of CVD, we know less about the role of epigenetics and their molecular determinants. The impact of environmental changes and epigenetics in CVD is now emerging as critically important in understanding the origin of disease and the development of new therapeutic approaches to prevention and treatment. This review focuses on the emerging role of epigenetics mediated by insulin like-growth factors-I and -II in major CVDs such as heart failure, cardiac hypertrophy and diabetes.

Prenatal pesticide exposure and PON1 genotype associated with adolescent body fat distribution evaluated by dual X-ray absorptiometry (DXA)

Many modern pesticides have endocrine disrupting abilities and early-life exposure may affect growth and disease risk later in life. Previously, we reported associations between prenatal pesticide exposure and higher childhood body fat content measured by anthropometry. The associations were affected by child PON1 Q192R genotype. We aimed to study whether prenatal pesticide exposure was still associated with body fat content and distribution in the children at puberty and the potential impact of both maternal and child PON1 Q192R genotype. In this prospective cohort study of 247 children born by occupationally exposed or unexposed women (greenhouse workers and controls) two follow-up examinations (age 10-15 and 11-16 years) including simple anthropometry, skinfold measurements, pubertal staging and blood sampling were performed. Total and regional fat% was determined by dual X-ray absorptiometry (DXA) at age 10-15. Prenatal pesticide exposure was associated with increased total, android, and gynoid fat percentage (DXA) at age 10-15 years after adjustment for sex, socioeconomic status, and puberty (all β = 0.5 standard deviation score (SDS) p < 0.05). Stratified by sex, the associations were significant in girls (total fat: β = 0.7 SDS, android-gynoid ratio: β = 0.1, both p < 0.05), but not in boys. Carrying the R-allele (child or mother, separately, or both) augmented the differences between exposed and unexposed children (total fat: β = 1.0 SDS, β = 0.8 SDS, p < 0.05, respectively, and β = 1.2 SDS, p < 0.01). No exposure-related differences were found if either the child or mother had the QQ wild-type. At age 11-16, exposed children tended to have a higher total fat% estimated by skinfolds than unexposed children (p = 0.06). No significant associations between prenatal exposure and body mass index or waist circumference were found. Prenatal pesticide exposure was associated with higher adolescent body fat content, including android fat deposition, independent of puberty. Girls appeared more susceptible than boys. Furthermore, the association depended on maternal and child PON1 Q192R genotype.

Paraoxonases-1, -2 and -3: What are their functions?

Paraoxonase-1 (PON1), an esterase/lactonase primarily associated with plasma high-density lipoprotein (HDL), was the first member of this family of enzymes to be characterized. Its name was derived from its ability to hydrolyze paraoxon, the toxic metabolite of the insecticide parathion. Related enzymes PON2 and PON3 were named from their evolutionary relationship with PON1. Mice with each PON gene knocked out were generated at UCLA and have been key for elucidating their roles in organophosphorus (OP) metabolism, cardiovascular disease, innate immunity, obesity, and cancer. PON1 status, determined with two-substrate analyses, reveals an individual's functional Q192R genotype and activity levels. The three-dimensional structure for a chimeric PON1 has been useful for understanding the structural properties of PON1 and for engineering PON1 as a catalytic scavenger of OP compounds. All three PONs hydrolyze microbial N-acyl homoserine lactone quorum sensing factors, quenching Pseudomonas aeruginosa's pathogenesis. All three PONs modulate oxidative stress and inflammation. PON2 is localized in the mitochondria and endoplasmic reticulum. PON2 has potent antioxidant properties and is found at 3- to 4-fold higher levels in females than males, providing increased protection against oxidative stress, as observed in primary cultures of neurons and astrocytes from female mice compared with male mice. The higher levels of PON2 in females may explain the lower frequency of neurological and cardiovascular diseases in females and the ability to identify males but not females with Parkinson's disease using a special PON1 status assay. Less is known about PON3; however, recent experiments with PON3 knockout mice show them to be susceptible to obesity, gallstone formation and atherosclerosis. Like PONs 1 and 2, PON3 also appears to modulate oxidative stress. It is localized in the endoplasmic reticulum, mitochondria and on HDL. Both PON2 and PON3 are upregulated in cancer, favoring tumor progression through mitochondrial protection against oxidative stress and apoptosis.

Association of polymorphisms at the microRNA binding site of the caprine KITLG 3'-UTR with litter size

This study identified three novel single nucleotide polymorphisms (SNPs) (c.1389C > T, c.1457A > C and c.1520G > A) in the caprine KITLG 3'-UTR through DNA sequencing. The three SNP loci were closely linked in Guanzhong dairy (GD) goats. Two alleles of the c.1457A > C SNP introduced two miRNA sites (chi-miR-204-5p and chi-miR-211). Individuals with combined genotype TT-CC-AA had a higher litter size compared with those with combined genotypes CC-AA-GG, TC-CC-GA and CC-AC-GG (P < 0.05). Luciferase assays showed that chi-miR-204-5p and chi-miR-211 suppressed luciferase expression in the presence of allele 1457A compared with negative control (NC) and allele 1457C (P < 0.05). Western blot revealed that KITLG significantly decreased in the granulosa cells (GCs) of genotype AA compared with that in the GCs of genotype CC and NC (P < 0.05). The KITLG mRNA levels of the CC-AA-GG carriers significantly decreased compared with those of the TT-CC-AA, TC-CC-GA and CC-AC-GG carriers. In addition, cell proliferation was reduced in haplotype C-A-G GCs compared with that in haplotype T-C-A GCs. These results suggest that SNPs c.1389C > T, c.1457A > C and c.1520G > A account for differences in the litter size of GD goats because chi-miR-204-5p and chi-miR-211 could change the expression levels of the KITLG gene and reduce GC proliferation.

Association between insulin receptor substrate-1 polymorphisms and high platelet reactivity with clopidogrel therapy in coronary artery disease patients with type 2 diabetes mellitus

BACKGROUND

The mechanisms leading to the high on-treatment platelet reactivity in diabetes patients are not fully elucidated. The genetic factors may be associated with the diminished antiplatelet efficacy of dual antiplatelet therapy. We investigated the possible association between insulin receptor substrate-1 (IRS-1) polymorphisms and high platelet reactivity in coronary artery disease (CAD) patients with type 2 diabetes mellitus (T2DM).

METHODS

A total of 674 CAD patients with T2DM were enrolled in this study. Platelet aggregation and platelet activation were assessed with light transmission aggregometry and flow cytometry analysis, respectively. Participants were divided into high platelet reactivity (HPR) group and non-HPR group according to their maximal platelet aggregation. Genotypes were identified by polymerase chain reaction and direct sequencing of genomic DNA. The association between IRS-1 genetic variants and platelet function was assessed.

RESULTS

There were 233 participants in the HPR group and 441 participants in the non-HPR group. G allele frequencies of rs13431554 were 27.7 % for the HPR group and 18.6 % for the non-HPR group (p < 0.001). Adenosine diphosphate and arachidonic acid induced platelet aggregation were significantly higher in G allele carriers compared with non-carriers (56.8 ± 16.2 vs 52.0 ± 17.9 %, p < 0.01, 28.9 ± 18.6 vs 25.2 ± 17.8 %, p < 0.01, respectively). We observed that P-selectin expression and PAC-1 binding were higher in G allele carriers compared with non-carriers (40.8 ± 12.4 vs 36.2 ± 13.8, p = 0.01; 43.7 ± 15.9 vs 38.7 ± 19.9, p = 0.03, respectively).

CONCLUSION

The G allele of rs13431554 in the IRS-1 gene was associated with a hyperreactive platelet phenotype in the CAD patients with T2DM.

The Emerging Role of Epigenetics in Cerebral Ischemia

Despite great progresses in the treatment and prevention of ischemic stroke, it is still among the leading causes of death and serious long-term disability all over the world, indicating that innovative neural regenerative and neuroprotective agents are urgently needed for the development of therapeutic approaches with greater efficacy for ischemic stroke. More and more evidence suggests that a spectrum of epigenetic processes play an important role in the pathophysiology of cerebral ischemia. In the present review, we first discuss recent developments in epigenetic mechanisms, especially their roles in the pathophysiology of cerebral ischemia. Specifically, we focus on DNA methylation, histone deacetylase, histone methylation, and microRNAs (miRNAs) in the regulation of vascular and neuronal regeneration after cerebral ischemia. Additionally, we highlight epigenetic strategies for ischemic stroke treatments, including the inhibition of histone deacetylase enzyme and DNA methyltransferase activities, and miRNAs. These therapeutic strategies are far from clinic use, but preliminary data indicate that neuroprotective agents targeting these pathways can modulate neural cell regeneration and promote brain repair and functional recovery after cerebral ischemia. A better understanding of how epigenetics influences the process and progress of cerebral ischemia will pave the way for discovering more sensitive and specific biomarkers and new targets and therapeutics for ischemic stroke.

miRNAs and High-Density Lipoprotein metabolism

Altered lipoprotein metabolism plays a key role during atherogenesis. For over 50years, epidemiological data have fueled the proposal that HDL-cholesterol (HDL-c) in circulation is inversely correlated to cardiovascular risk. However, the atheroprotective role of HDL is currently the focus of much debate and remains an active field of research. The emerging picture from research in the past decade suggests that HDL function, rather than HDL-c content, is important in disease. Recent developments demonstrate that miRNAs play an important role in fine-tuning the expression of key genes involved in HDL biogenesis, lipidation, and clearance, as well as in determining the amounts of HDL-c in circulation. Thus, it has been proposed that miRNAs that affect HDL metabolism might be exploited therapeutically in patients. Whether HDL-based therapies, alone or in combination with LDL-based treatments (e.g. statins), provide superior outcomes in patients has been recently questioned by human genetics studies and clinical trials. The switch in focus from "HDL-cholesterol" to "HDL function" opens a new paradigm to understand the physiology and therapeutic potential of HDL, and to find novel modulators of cardiovascular risk. In this review we summarize the current knowledge on the regulation of HDL metabolism and function by miRNAs. This article is part of a Special Issue entitled: MicroRNAs and lipid/energy metabolism and related diseases edited by Carlos Fernández-Hernando and Yajaira Suárez.

Time-dependent flow velocity measurement using two-dimensional color Doppler flow imaging and evaluation by Hagen-Poiseuille equation

This paper aims to develop a technique to assess velocity flow profile and wall shear stress (WSS) spatial distribution across a vessel phantom representing an artery. Upon confirming the reliability of the technique, it was then used on a set of carotid arteries from a cohort of human subjects. We implemented color Doppler flow imaging (CDFI) for measurement of velocity profile in the artery cross section. Two dimensional instantaneous and time-dependent flow velocity and WSS vector fields were measured and their waveforms of peak velocities based on the technique were compared with WSS values generated by Hagen-Poiseuille equation. Seventy-five patients with intima-media thickening were prospectively enrolled and were divided into an IMT group. At the same time, another 75 healthy volunteers were enrolled as the control group. All the subjects were scanned and the DICOM files were imported into our in-house program. Next, we determine the velocity profile of carotid arteries in a set of 150 human subjects and compared them again. The peak velocities by the CDFI and Hagen-Poiseuille equation techniques were compared and statistically evaluated. The amounts of deviation for the two measured WSS profiles were performed and we demonstrated that they are not significantly different. At two different flow settings with peak flow velocity of 0.1, 0.5 (×10(-11)) m/s, the obtained WSS were 0.021 ± 0.04, 0.038 ± 0.05 m/s, respectively. For the patient population study, the mean WSS value calculated by Hagen-Poiseuille equation was 2.98 ± 0.15 dyne/cm(2), while it was 2.31 ± 0.14 dyne/cm(2) by our CDFI analysis program. The difference was not statistically significant (t = -1.057, P = 0.259). Similar to the Hagen-Poiseuille equation, a negative linear correlation was also found between the calculated WSS and intima-media thickness (P = 0.000). Using CDFI analysis, we found that the WSS distribution at the middle of the proximal plaque shoulder was larger than the top of the shoulder. CDFI can assess the velocity and WSS profile accurately and efficiently and may be used for clinical diagnosis of cardiovascular conditions.

MicroRNA-765 influences arterial stiffness through modulating apelin expression

The present study aims to discover single nucleotide polymorphisms (SNPs) at the apelin gene (APLN) in relation to arterial stiffness, and to explore its molecular mechanisms. A two-step genetic association study was conducted using 799 and 937 subjects in the screening and validation data, respectively. Four tagging SNPs of APLN were tested. SNP rs3115757 was significantly associated with stiffness parameters (β, Ep and PWV) in women, but not in men. The function of rs3115757 was tagged by rs3115758 which is located in miR-765 binding site in the 3' untranslated region of APLN. The reporter assay confirmed that different alleles of rs3115758 interfered with miR-765 binding and then modified APLN expression. Over-expression of miR-765 in endothelial cells decreased mRNA and protein levels of APLN, which further inhibited the phosphorylation of eNOS and ERK/Akt/AMPK signaling. Collectively, our data showed that rs3115758 accounts for the susceptibility of arterial stiffening through miR-765-induced APLN repression.

Two Mutations in the Caprine MTHFR 3'UTR Regulated by MicroRNAs Are Associated with Milk Production Traits

BACKGROUND

5,10-Methylenetetrahydrofolate reductase (MTHFR) plays a central role in folate metabolism by irreversibly converting 5,10-methylenetetrahydrofolate to 5-methylenetetrahydrofolate, a predominant circulating form of folate. Folate is reportedly important for milk protein synthesis, and MTHFR may be a key regulatory point of folate metabolism for milk protein synthesis in mammary epithelial cells. Prior to this study, polymorphisms of the MTHFR gene were not associated with milk production traits from a breeding perspective. Single nucleotide polymorphisms (SNPs) at microRNA (miRNA) binding sites (miR-SNPs) can affect gene expression. This study aimed to identify the effects of miR-SNPs (g.2244A>G and g.2264A>G) in the caprine MTHFR 3' UTR on the milk production traits of dairy goats.

RESULTS

Guanzhong dairy (GD, n = 325) goats were used to detect SNPs in the caprine MTHFR 3' UTR by DNA sequencing. Two novel SNPs (g.2244A>G and g.2264A>G) were identified in the said region. The homozygous haplotype A-G of the SNPs g.2244A>G and g.2264A>G was significantly associated with milk yield and milk protein levels in GD goats (P < 0.05). Functional assays indicated that the MTHFR 2244 A → G substitution could increase the binding activity of hsa-miR-1266 with the MTHFR 3' UTR. The MTHFR 2264 A → G substitution could decrease the binding activity of hsa-miR-616 with the MTHFR 3' UTR. In addition, we observed a significant increase in the MTHFR mRNA levels of homozygous haplotype A-G carriers relative to those of homozygous haplotype G-A carriers. These results indicated that both SNPs altered the MTHFR mRNA levels. These altered levels of MTHFR mRNA may account for the association of SNPs with milk production traits.

CONCLUSIONS

This study is the first to report that the g.2244A>G and g.2264A>G polymorphisms were associated with milk production traits in GD goats. Further investigations should explore the underlying miRNA-mediated mechanisms that are modified by the g.2244A>G and g.2264A>G SNPs. The current study evaluated these SNPs as potential genetic markers in goats, with potential applications in breeding programs.

Human paraoxonase-1 (PON1): Gene structure and expression, promiscuous activities and multiple physiological roles

Human PON1 is a HDL-associated lipolactonase capable of preventing LDL and cell membrane oxidation and is therefore considered to be atheroprotective. PON1 contributes to the antioxidative function of HDL and reductions in HDL-PON1 activity, prevalent in a wide variety of diseases with an inflammatory component, are believed to lead to dysfunctional HDL which can promote inflammation and atherosclerosis. However, PON1 is multifunctional and may contribute to other HDL functions such as in innate immunity, preventing infection by quorum sensing gram negative bacteria by destroying acyl lactone mediators of quorum sensing, and putative new roles in cancer development and the promotion of healthy ageing. In this review we explore the physiological roles of PON1 in disease development, as well as PON1 gene and protein structure, promiscuous activities and the roles of SNPs and ethnicity in determining PON1 activity.

Recent progress in the genetics and epigenetics of paraoxonase: why it is relevant to children's environmental health

PURPOSE OF REVIEW

Children are more susceptible to exposures in utero and during early childhood that may result in developmental problems and chronic diseases. Novel discoveries in the field of molecular epidemiology that can help explain susceptibility to exposures and disease will be demonstrated using the multifunctional enzyme paraoxonase 1 (PON1) as an example.

RECENT FINDINGS

The broad PON1 variability in humans, partly due to differences in genetics and age, can confer differential susceptibility because this enzyme can detoxify organophosphate pesticides and has antioxidant properties. Epigenetics plays a significant role in the mediation of the effects of environmental exposure on human health and is hypothesized to be a major contributing factor to the early-life origins of adult disease. Studies highlighted in this review demonstrate the relationship of PON1 polymorphisms with microRNA binding in addition to a link between DNA methylation in the transcriptional regulatory region with changes in PON1 enzyme levels. Other important methodologies such as ancestry informative markers and lactonase activity can enhance studies involving PON1.

SUMMARY

This PON1 model demonstrates that integrating genetic and epigenetic factors, as well as other novel methodologies, can improve our understanding of important susceptibility factors linked to pediatric disease.

Interaction effects between Paraoxonase 1 variants and cigarette smoking on risk of coronary heart disease in a Singaporean Chinese population

OBJECTIVE

Paraoxonase 1 (PON1) plays an important role in reducing the risk of coronary heart disease (CHD). Smoking is known to reduce PON1 activity. We aimed to investigate the effects of interactions between PON1 variants and smoking on CHD in the Singaporean Chinese population.

METHODS

In a case-control study nested within Singapore Chinese Health Study (N=1914), subjects with and without CHD were classified into never-smokers and ever-smokers (ever smoked at least one cigarette a day for 1 year or longer). Associations at four independent SNPs at the PON1 locus (rs3735590, rs3917550, rs662, rs3917481) with CHD were evaluated using logistic regression, before/after stratification on smoking status. Interactions between smoking and PON1 variants were analyzed with likelihood ratio tests, by including the SNP*smoking interaction term in regression analyses.

RESULTS

The T allele at the coding SNP, rs662, was associated with higher risk of CHD in ever-smokers only (OR=1.35, 95% CI 1.08-1.68; adjusted P=0.036). At the miR-SNP, rs3735590, carrying at least one copy of minor allele T was associated with increased risk of CHD in a dominant manner in never-smokers only (OR=1.53, 95% CI 1.11-2.11; adjusted P=0.036). Significant interactions between two PON1 SNPs and smoking in relation to CHD risk were identified (adjusted P=0.012 for rs662; adjusted P=0.044 for rs3735590). These associations remained significant after adjustment for known CHD risk factors and upon correction for multiple tests.

CONCLUSIONS

Two PON1 SNPs, rs662 and rs3735590, were found to significantly interact with cigarette smoking to modulate the risk of CHD in the Singaporean Chinese population.

PON1 as a model for integration of genetic, epigenetic, and expression data on candidate susceptibility genes

Recent genome- and epigenome-wide studies demonstrate that the DNA methylation is controlled in part by genetics, highlighting the importance of integrating genetic and epigenetic data. To better understand molecular mechanisms affecting gene expression, we used the candidate susceptibility gene paraoxonase 1 (PON1) as a model to assess associations of PON1 genetic polymorphisms with DNA methylation and arylesterase activity, a marker of PON1 expression. PON1 has been associated with susceptibility to obesity, cardiovascular disease, and pesticide exposure. In this study, we assessed DNA methylation in 18 CpG sites located along PON1 shores, shelves, and its CpG island in blood specimens collected from newborns and 9-year-old children participating (n = 449) in the CHAMACOS birth cohort study. The promoter polymorphism, PON1_-108 , was strongly associated with methylation, particularly for CpG sites located near the CpG island (P << 0.0005). Among newborns, these relationships were even more pronounced after adjusting for blood cell composition. We also observed significant decreases in arylesterase activity with increased methylation at the same nine CpG sites at both ages. Using causal mediation analysis, we found statistically significant indirect effects of methylation (β(95% confidence interval): 6.9(1.5, 12.4)) providing evidence that DNA methylation mediates the relationship between PON1_-108 genotype and PON1 expression. Our findings show that integration of genetic, epigenetic, and expression data can shed light on the functional mechanisms involving genetic and epigenetic regulation of candidate susceptibility genes like PON1.

Genetic and epigenetic regulation of gene expression in fetal and adult human livers

Background

The liver plays a central role in the maintenance of homeostasis and health in general. However, there is substantial inter-individual variation in hepatic gene expression, and although numerous genetic factors have been identified, less is known about the epigenetic factors.

Results

By analyzing the methylomes and transcriptomes of 14 fetal and 181 adult livers, we identified 657 differentially methylated genes with adult-specific expression, these genes were enriched for transcription factor binding sites of HNF1A and HNF4A. We also identified 1,000 genes specific to fetal liver, which were enriched for GATA1, STAT5A, STAT5B and YY1 binding sites. We saw strong liver-specific effects of single nucleotide polymorphisms on both methylation levels (28,447 unique CpG sites (meQTL)) and gene expression levels (526 unique genes (eQTL)), at a false discovery rate (FDR) < 0.05. Of the 526 unique eQTL associated genes, 293 correlated significantly not only with genetic variation but also with methylation levels. The tissue-specificities of these associations were analyzed in muscle, subcutaneous adipose tissue and visceral adipose tissue. We observed that meQTL were more stable between tissues than eQTL and a very strong tissue-specificity for the identified associations between CpG methylation and gene expression.

Conclusions

Our analyses generated a comprehensive resource of factors involved in the regulation of hepatic gene expression, and allowed us to estimate the proportion of variation in gene expression that could be attributed to genetic and epigenetic variation, both crucial to understanding differences in drug response and the etiology of liver diseases.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2164-15-860) contains supplementary material, which is available to authorized users.

The role of microRNAs in the control of innate immune response in cancer

Ligands for receptors of natural killer (NK) cells and CD8(+) cytotoxic T lymphocytes (CTL), such as the inhibitory nonclassical HLA-G, the activating stress-induced major histocompatibility complex class I-related antigens MICA and MICB, and/or the UL16-binding proteins (ULBPs), are often aberrantly expressed upon viral infection and neoplastic transformation, thereby preventing virus-infected or malignant-transformed cells from elimination by immune effector cells. Recently, it has been shown that ligands of both NK and CD8(+) T cells are regulated by a number of cellular and/or viral microRNAs (miRs). These miRs are involved in shaping the antiviral and/or antitumoral immune responses as well as neoplastic growth properties. This review summarizes the expression pattern and function of miRs directed against selected NK and T cell receptor ligands, their putative role in shaping immune surveillance and tumorigenicity, and their clinical relevance. In addition, the potential role of RNA-binding proteins in the post-transcriptional gene regulation of these ligands will be discussed.

MicroRNA-410 regulated lipoprotein lipase variant rs13702 is associated with stroke incidence and modulated by diet in the randomized controlled PREDIMED trial

BACKGROUND

MicroRNAs have emerged as important epigenetic regulators in cardiovascular diseases (CVDs). Using an observational meta-analysis design, we previously characterized a gain-of-function microRNA-410 target site polymorphism (rs13702T>C) in the 3'untranslated region of the lipoprotein lipase (LPL) gene. The C allele was associated with lower triglycerides, and this association was modulated by fat intake.

OBJECTIVES

We aimed to extend our findings by assessing the interaction between the rs13702 polymorphism and fat intake on triglycerides at baseline and longitudinally by using a dietary intervention design. We also examined as a primary outcome the association of this variant with CVD incidence and its modulation by the Mediterranean diet (MedDiet).

DESIGN

We studied 7187 participants in the PREDIMED (Prevención con Dieta Mediterránea) randomized trial that tested a MedDiet intervention compared with a control diet, with a median 4.8-y follow-up. LPL polymorphisms and triglycerides were determined and CVD assessed. Gene-diet interactions for triglycerides were analyzed at baseline (n = 6880) and after a 3-y intervention (n = 4131). Oxidative stress parameters were investigated in a subsample.

RESULTS

The rs13702T>C polymorphism was strongly associated with lower triglycerides in C allele carriers and interacted synergistically with dietary monounsaturated (P = 0.038) and unsaturated fat intake (P = 0.037), decreasing triglycerides at baseline. By 3 y, we observed a gene-diet interaction (P = 0.025) in which the C allele was associated with a greater reduction in triglycerides after intervention with MedDiet, high in unsaturated fat. Although the polymorphism was associated with lower stroke risk (HR: 0.74; 95% CI: 0.57, 0.97; P = 0.029 per C allele), this association reached statistical significance only in the MedDiet intervention (HR: 0.58; 95% CI: 0.37, 0.91; P = 0.019 in C compared with TT carriers), not in the control group (HR: 0.94; 95% CI: 0.55, 1.59; P = 0.805).

CONCLUSION

We report a novel association between a microRNA target site variant and stroke incidence, which is modulated by diet in terms of decreasing triglycerides and possibly stroke risk in rs13702 C allele carriers after a high-unsaturated fat MedDiet intervention.

Paraoxonase (PON)1 Q192R functional genotypes and PON1 Q192R genotype by smoking interactions are risk factors for the metabolic syndrome, but not overweight or obesity

Background The metabolic syndrome (MetS) is a complex of multiple risk factors that contribute to the onset of cardiovascular disorder, including lowered levels of high-density lipoprotein (HDL) and abdominal obesity. Smoking, mood disorders, and oxidative stress are associated with the MetS. Paraoxonase (PON)1 is an antioxidant bound to HDL, that is under genetic control by functional polymorphisms in the PON1 Q192R coding sequence. Aims and methods This study aimed to delineate the associations of the MetS with plasma PON1 activity, PON1 Q192R genotypes, smoking, and mood disorders (major depression and bipolar disorder), while adjusting for HDL cholesterol, body mass index, age, gender, and sociodemographic data. We measured plasma PON1 activity and serum HDL cholesterol and determined PON1 Q192R genotypes through functional analysis in 335 subjects, consisting of 97 with and 238 without MetS. The severity of nicotine dependence was measured using the Fagerström Nicotine Dependence Scale. Results PON1 Q192R functional genotypes and PON1 Q192R genotypes by smoking interactions were associated with the MetS. The QQ and QR genotypes were protective against MetS while smoking increased metabolic risk in QQ carriers only. There were no significant associations between PON1 Q192R genotypes and smoking by genotype interactions and obesity or overweight, while body mass index significantly increased MetS risk. Smoking and especially severe nicotine dependence are significantly associated with the MetS although these effects were no longer significant after considering the effects of the smoking by PON1 Q192R genotype interaction. The MetS was not associated with mood disorders, major depression or bipolar disorder. Discussion PON1 Q192R genotypes and genotypes by smoking interactions are risk factors for the MetS that together with lowered HDL and increased body mass and age contribute to the MetS.