Genetic Variation in the Platelet Endothelial Aggregation Receptor 1 Gene Results in Endothelial Dysfunction

Integrative analysis of drug response and clinical outcome in acute myeloid leukemia

Acute myeloid leukemia (AML) is a cancer of myeloid-lineage cells with limited therapeutic options. We previously combined ex vivo drug sensitivity with genomic, transcriptomic, and clinical annotations for a large cohort of AML patients, which facilitated discovery of functional genomic correlates. Here, we present a dataset that has been harmonized with our initial report to yield a cumulative cohort of 805 patients (942 specimens). We show strong cross-cohort concordance and identify features of drug response. Further, deconvoluting transcriptomic data shows that drug sensitivity is governed broadly by AML cell differentiation state, sometimes conditionally affecting other correlates of response. Finally, modeling of clinical outcome reveals a single gene, PEAR1, to be among the strongest predictors of patient survival, especially for young patients. Collectively, this report expands a large functional genomic resource, offers avenues for mechanistic exploration and drug development, and reveals tools for predicting outcome in AML.

Oklahoma Nathan Shock Aging Center - assessing the basic biology of aging from genetics to protein and function

The Oklahoma Shock Nathan Shock Center is designed to deliver unique, innovative services that are not currently available at most institutions. The focus of the Center is on geroscience and the development of careers of young investigators. Pilot grants are provided through the Research Development Core to junior investigators studying aging/geroscience throughout the USA. However, the services of our Center are available to the entire research community studying aging and geroscience. The Oklahoma Nathan Shock Center provides researchers with unique services through four research cores. The Multiplexing Protein Analysis Core uses the latest mass spectrometry technology to simultaneously measure the levels, synthesis, and turnover of hundreds of proteins associated with pathways of importance to aging, e.g., metabolism, antioxidant defense system, proteostasis, and mitochondria function. The Genomic Sciences Core uses novel next-generation sequencing that allows investigators to study the effect of age, or anti-aging manipulations, on DNA methylation, mitochondrial genome heteroplasmy, and the transcriptome of single cells. The Geroscience Redox Biology Core provides investigators with a comprehensive state-of-the-art assessment of the oxidative stress status of a cell, e.g., measures of oxidative damage and redox couples, which are important in aging as well as many major age-related diseases as well as assays of mitochondrial function. The GeroInformatics Core provides investigators assistance with data analysis, which includes both statistical support as well as analysis of large datasets. The Core also has developed number of unique software packages to help with interpretation of results and discovery of new leads relevant to aging. In addition, the Geropathology Research Resource in the Program Enhancement Core provides investigators with pathological assessments of mice using the recently developed Geropathology Grading Platform.

PEAR1 polymorphisms as a prognostic factor in hemostasis and cardiovascular diseases

Platelet Endothelial Aggregation Receptor (PEAR1), as a platelet receptor, plays a vital role in hemostasis. This receptor, by its extracellular part, causes platelet adhesion and consequently initiates platelet aggregation. Dysfunction of PEAR1 can disrupt platelet aggregation in patients with cardiovascular diseases (CVDs). The content used in this paper has been taken from English language articles (2005-2020) retrieved from Pubmed database and Google scholar search engine using "Cardiovascular Disease", "PEAR1", "Polymorphism", and "Platelet Aggregation" keywords. Some PEAR1 polymorphisms can disrupt homeostasis and interfere with the function mechanism of cardiac drugs. Since polymorphisms in this gene affect platelet function and the platelet aggregation process, PEAR1 could be further studied in the future as an essential factor in controlling the treatment process of patients with cardiovascular diseases. PEAR1 polymorphisms through disruption of the platelet aggregation process can be a risk factor in patients with CVDs. Therefore, controlling patients through genetic testing and the evaluation of PEAR1 polymorphisms can help improve the treatment process of patients. According to the studies on the PEAR1 gene and the effect of different polymorphisms on some crucial issues in CVDs patients (changes in platelet activity), it is clear that if there is a significant relationship between polymorphisms and CVDs, they can be used as prognostic and diagnostic markers. This study aims to evaluate the prognosis and drug treatment of the PEAR1 gene in CVDs patients.

Impact of Platelet Endothelial Aggregation Receptor-1 Genotypes on Platelet Reactivity and Early Cardiovascular Outcomes in Patients Undergoing Percutaneous Coronary Intervention and Treated With Aspirin and Clopidogrel

BACKGROUND

The genetic determinants of response to clopidogrel and aspirin are incompletely characterized. Recently, PEAR1 (platelet endothelial aggregation receptor-1) rs12041331 polymorphism has been shown to influence the platelet reactivity, but its impact on cardiovascular outcomes remains unclear in patients treated with antiplatelet agents.

METHODS AND RESULTS

In this prospective cohort study, 2439 Chinese patients with acute coronary syndrome or stable coronary artery disease undergoing coronary stent implantation and receiving clopidogrel and aspirin were consecutively recruited. Their platelet reactivity was determined by light transmission aggregometry at 5 and 30 days after coronary intervention. Genotyping was performed using an improved multiplex ligation detection reaction technique. All patients completed a 30-day follow-up for clinical outcomes. Genotyping for PEAR1 showed 768 (38.3%) GG homozygotes, 941 (46.9%) GA heterozygotes, and 298 (14.8%) AA homozygotes. The 30-day incidence of major adverse cardiovascular events, the composite of cardiovascular death, nonfatal myocardial infarction, and ischemic stroke were significantly higher in AA homozygotes than in non-AA homozygotes (adjusted hazard ratio, 2.78; 95% CI, 1.13-6.82; P=0.026), irrespective of CYP2C19*2 loss-of-function polymorphism and known outcome predictors including age, sex, smoking, and diabetes mellitus. The ADP-induced platelet aggregation was significantly lower in AA homozygotes than that in GG homozygotes at both time points, although no significant difference was found for the arachidonic acid-induced platelet aggregation among the 3 groups.

CONCLUSIONS

About 15% of Chinese patients undergoing coronary stent implantation were AA homozygotes for PEAR1 rs12041331. These patients had ≈3-fold increase in short-term major adverse cardiovascular events risk compared with non-AA homozygotes, and the adverse clinical outcome is unlikely to be mediated by suboptimal pharmacological response to aspirin or clopidogrel.

CLINICAL TRIAL REGISTRATION

URL: https://www.clinicaltrials.gov . Unique identifier: NCT01968499.

Jedi-1 deficiency increases sensory neuron excitability through a non-cell autonomous mechanism

The dorsal root ganglia (DRG) house the primary afferent neurons responsible for somatosensation, including pain. We previously identified Jedi-1 (PEAR1/MEGF12) as a phagocytic receptor expressed by satellite glia in the DRG involved in clearing apoptotic neurons during development. Here, we further investigated the function of this receptor in vivo using Jedi-1 null mice. In addition to satellite glia, we found Jedi-1 expression in perineurial glia and endothelial cells, but not in sensory neurons. We did not detect any morphological or functional changes in the glial cells or vasculature of Jedi-1 knockout mice. Surprisingly, we did observe changes in DRG neuron activity. In neurons from Jedi-1 knockout (KO) mice, there was an increase in the fraction of capsaicin-sensitive cells relative to wild type (WT) controls. Patch-clamp electrophysiology revealed an increase in excitability, with a shift from phasic to tonic action potential firing patterns in KO neurons. We also found alterations in the properties of voltage-gated sodium channel currents in Jedi-1 null neurons. These results provide new insight into the expression pattern of Jedi-1 in the peripheral nervous system and indicate that loss of Jedi-1 alters DRG neuron activity indirectly through an intercellular interaction between non-neuronal cells and sensory neurons.

PEAR1 suppresses the proliferation of pulmonary microvascular endothelial cells via PI3K/AKT pathway in ALI model

BACKGROUND

Activation of the proliferation of pulmonary microvascular endothelial cells (PMVECs) is a key step in the recovery of the integrity of endothelial monolayer, which helps to alleviate acute lung injury (ALI). Platelet endothelial aggregation receptor-1 (PEAR1), expressed on endothelial cells, was reported to inhibit the proliferation of vascular endothelial cells and angiogenesis. However, little is known about its role and mechanism in vascular endothelial disorders in ALI.

OBJECTIVE

The aim of this study was to investigate the impact of PEAR1 on the proliferation of pulmonary microvascular endothelial cells in ALI.

METHODS

We tested the expression level of PEAR1 in the lungs of WT mice in ALI model induced by intestinal IR. Primary human pulmonary microvascular endothelial cells (HPMECs) were stimulated by 1 mg/L LPS in vitro. We synthesized siPEAR1 and Flag-PEAR1 plasmid to verify the role of PEAR1 on regulating the proliferation of HPMECs under LPS condition and to explore related signaling pathways.

RESULTS

The expression level of PEAR1 significantly increased in ALI induced by intestinal IR. PEAR1 knockdown enhanced the proliferation level of HPMECs, which, however, was inhibited by PEAR1 overexpression. PEAR1 knockdown activated PI3K/AKT pathway both in steady state and under LPS condition. PI3K inhibitor, LY294002, reversed the increasing proliferation level and cell progression of HPMECs induced by PEAR1 knockdown after LPS challenge.

CONCLUSIONS

PEAR1 acts as a negative regulator in the proliferation of HPMECs in ALI model via the PI3K/AKT pathway.

Variation of PEAR1 DNA methylation influences platelet and leukocyte function

BACKGROUND

Platelet-endothelial aggregation receptor 1 (PEAR-1) is a transmembrane receptor involved in platelet activation and megakaryopoiesis whose expression is driven by DNA methylation. PEAR1 variants were associated with differential platelet response to activation and cardiovascular outcomes. We aimed at investigating the link between PEAR1 methylation and platelet and leukocyte function markers in a family-based population.

RESULTS

We measured PEAR1 methylation in 605 Moli-family participants with available blood counts, plasma P-selectin and C-reactive protein, whole blood platelet P-selectin, and platelet-leukocyte mixed conjugate measurements. We performed principal component analysis (PCA) to identify groups of highly correlated CpG sites. We used linear mixed regression models (using age, gender, BMI, smoking, alcohol drinking, being a proband for family recruitment, being a member of myocardial infarction (MI) family as fixed effects, and family as a random effect) to evaluate associations between PEAR1 methylation and phenotypes. PEAR1 methylation Factor2, characterized by the previously identified megakaryocyte-specific CpG sites, was inversely associated with platelet-monocyte conjugates, P-selectin, and WBC counts, while positively associated with the platelet distribution width (PDW) and with leukocyte CD11b and L-selectin. Moreover, PEAR1 Factor2 methylation was negatively associated with INFLAscore, a low-grade inflammation score. The latter was partially mediated by the PEAR1 methylation effect on platelet variables. PEAR1 methylation association with WBC measurements and INFLAscore was confirmed in the independent cohort FLEMENGHO.

CONCLUSIONS

We report a significant link between epigenetic signatures in a platelet functional gene and inflammation-dependent platelet function variability measured in two independent cohorts.

Effect of 106PEAR1 and 168PTGS1 genetic polymorphisms on recurrent ischemic stroke in Chinese patient

The impact of genetic polymorphisms on the occurrence of recurrent ischemic stroke (RIS) is not fully understood. This study was aimed to examine the relationships among the 106PEAR1 and 168PTGS1 polymorphisms and RIS.This was a single-center, retrospective, case-control study of patients seen in consultation between March 2016 and December 2016 at the Shandong Provincial Hospital. The 106PEAR1 (G>A) and 168PTGS1 (-842A>G) polymorphisms were determined by fluorescence in situ hybridization.There were 56 patients with RIS and 137 with initial stroke. Compared with the initial group, the RIS group showed lower LDL-C levels (P = .04). 168PTGS1 (-842A>G) did not meet the Hardy-Weinberg equilibrium. The AA genotype of the 106PEAR1 (G>A) polymorphism was more frequent in the RIS group (17.9% vs 5.8%, P = .009). The A allele also showed a higher frequency than the G allele in the RIS group (P = .02). The multivariable logistic regression analysis showed that 106PEAR1 (G>A) (OR = 3.24, 95%CI: 1.04-10.14, P = .04) and lipid-lowering agents (OR = 9.18, 95%CI: 4.48-18.84, P < .001) were independently associated with RIS.The polymorphism at 106PEAR1 (G>A) was independently associated with RIS in Chinese patients. The assessment of genetic polymorphisms in the prediction of RIS warrants further investigation in order to improve patient management and prognosis after a first ischemic stroke.

Pharmacogenomic considerations for antiplatelet agents: the era of precision medicine in stroke prevention and neurointerventional practice

Antiplatelet drugs are widely utilized in the setting of primary stroke prevention, secondary stroke prevention, and neuroendovascular device-related stroke prevention. These medications are effective in general, although significant variability in drug activity exists between patients. Although this variation may be related in part to a multitude of factors, a growing body of evidence suggests that individual genotypes are a main contributor. The PharmGKB database was mined to prioritize genetic variants with potential clinical relevance for response to aspirin, clopidogrel, prasugrel, and ticagrelor. Although variants were reported for all drugs, the highest level of evidence was found in cytochrome P450 (CYP450) genotype variation related to clopidogrel response. Individual genetic influences have an impact on the pharmacodynamics of antiplatelet agents. Current clinical practice for stroke prevention is primarily empiric or guided by functional assays; however, there now exists a third potential pathway to base treatment decisions: genotype-guided treatment.

A PEAR1 polymorphism (rs12041331) is associated with risk of coronary artery aneurysm in Kawasaki disease

Kawasaki disease (KD) is an acute systemic vasculitis that is most seriously complicated by coronary artery aneurysm (CAA). The polymorphisms of platelet endothelial aggregation receptor 1 (PEAR1), notably rs12041331 and rs12566888, were found to be closely related to cardiac disease. However, little is known regarding the connection between PEAR1 and KD. In this study, we genotyped PEAR1 rs12566888 and rs12041331 in 637 healthy infants and 694 KD patients (74 with CAA). Subsequently, odds ratio (OR) and 95% confidence interval (CI) were calculated to assess the strength of their relationships. No significant differences in the frequency of rs12566888 or rs12041331 in PEAR1 were observed between KD and healthy controls. However, regardless of the statistical combination of rs12566888 genotype, the rs12041331 recessive inheritance model was associated with an increased risk of CAA after Bonferroni correction (for rs12041331, AA vs. GG/GA: adjusted OR = 2.37, 95% CI = 1.41-4.01, P = 0.009; combination of two recessive genotypes vs. combination of 0-1 recessive genotypes: adjusted OR = 2.39, 95% CI = 1.42-4.04, P = 0.009). This study suggests for the first time that PEAR1 polymorphisms did not indicate susceptibility for KD occurrence but the rs12041331 polymorphism was associated with increased risk of CAA formation in KD, and the functions of the gene warrant further research.

Tetraspanin-enriched microdomains regulate digitation junctions

Tetraspanins co-emerged with multi-cellular organisms during evolution and are typically localized at the cell–cell interface, [corrected] and form tetraspanin-enriched microdomains (TEMs) by associating with each other and other membrane molecules. Tetraspanins affect various biological functions, but how tetraspanins engage in multi-faceted functions at the cellular level is largely unknown. When cells interact, the membrane microextrusions at the cell-cell interfaces form dynamic, digit-like structures between cells, which we term digitation junctions (DJs). We found that (1) tetraspanins CD9, CD81, and CD82 and (2) TEM-associated molecules integrin α3β1, CD44, EWI2/PGRL, and PI-4P are present in DJs of epithelial, endothelial, and cancer cells. Tetraspanins and their associated molecules also regulate the formation and development of DJs. Moreover, (1) actin cytoskeleton, RhoA, and actomyosin activities and (2) growth factor receptor-Src-MAP kinase signaling, but not PI-3 kinase, regulate DJs. Finally, we showed that DJs consist of various forms in different cells. Thus, DJs are common, interactive structures between cells, and likely affect cell adhesion, migration, and communication. TEMs probably modulate various cell functions through DJs. Our findings highlight that DJ morphogenesis reflects the transition between cell-matrix adhesion and cell-cell adhesion and involves both cell-cell and cell-matrix adhesion molecules.

Variants of PEAR1 Are Associated With Outcome in Patients With ACS and Stable CAD Undergoing PCI

Introduction: Platelet endothelial aggregation receptor 1 (PEAR1) triggers platelet aggregation and is expressed in platelets and endothelial cells. Genome-wide association studies (GWAS) showed an association between platelet function and single-nucleotide polymorphisms (SNPs) in PEAR1.

Methods: In 582 consecutive patients with stable coronary artery disease (CAD) or acute coronary syndrome (ACS) scheduled for PCI and treated with ASA and Clopidogrel, Prasugrel, or Ticagrelor, SNP analysis for rs12566888, rs2768759, rs41273215, rs3737224, and rs822442 was performed. During a follow-up period of 365 days after initial PCI, all patients were tracked for a primary endpoint, defined as a combined endpoint consisting of either time to death, myocardial infarction (MI) or ischemic stroke. All cause mortality, MI and ischemic stroke were defined as secondary endpoints.

Results: Multivariable Cox model analysis for the primary endpoint revealed a significantly increased risk in homozygous PEAR1 rs2768759 minor allele carriers (hazard ratio, 3.16; 95% confidence interval, 1.4–7.13, p = 0.006). Moreover, PEAR1 rs12566888 minor allele carriers also showed an increased risk in all patients (hazard ratio, 1.69; 95% confidence interval, 0.87–3.27, p = 0.122), which was marginally significant in male patients (hazard ratio, 2.12; 95% confidence interval, 1.02–4.43, p = 0.045; n = 425).

Conclusions: To the best of our knowledge, this is the first study showing that distinct genetic variants of PEAR1 are associated with cardiovascular prognosis in high risk patients undergoing PCI and treated with dual anti platelet therapy.

Cell-Specific PEAR1 Methylation Studies Reveal a Locus that Coordinates Expression of Multiple Genes

Chromosomal interactions connect distant enhancers and promoters on the same chromosome, activating or repressing gene expression. PEAR1 encodes the Platelet-Endothelial Aggregation Receptor 1, a contact receptor involved in platelet function and megakaryocyte and endothelial cell proliferation. PEAR1 expression during megakaryocyte differentiation is controlled by DNA methylation at its first CpG island. We identified a PEAR1 cell-specific methylation sensitive region in endothelial cells and megakaryocytes that showed strong chromosomal interactions with ISGL20L2, RRNAD1, MRLP24, HDGF and PRCC, using available promoter capture Hi-C datasets. These genes are involved in ribosome processing, protein synthesis, cell cycle and cell proliferation. We next studied the methylation and expression profile of these five genes in Human Umbilical Vein Endothelial Cells (HUVECs) and megakaryocyte precursors. While cell-specific PEAR1 methylation corresponded to variability in expression for four out of five genes, no methylation change was observed in their promoter regions across cell types. Our data suggest that PEAR1 cell-type specific methylation changes may control long distance interactions with other genes. Further studies are needed to show whether such interaction data might be relevant for the genome-wide association data that showed a role for non-coding PEAR1 variants in the same region and platelet function, platelet count and cardiovascular risk.

GTSE1 regulates spindle microtubule dynamics to control Aurora B kinase and Kif4A chromokinesin on chromosome arms

In mitosis, the dynamic assembly and disassembly of microtubules are critical for normal chromosome movement and segregation. Microtubule turnover varies among different mitotic spindle microtubules, dictated by their spatial distribution within the spindle. How turnover among the various classes of spindle microtubules is differentially regulated and the resulting significance of differential turnover for chromosome movement remains a mystery. As a new tactic, we used global microarray meta-analysis (GAMMA), a bioinformatic method, to identify novel regulators of mitosis, and in this study, we describe G2- and S phase-expressed protein 1 (GTSE1). GTSE1 is expressed exclusively in late G2 and M phase. From nuclear envelope breakdown until anaphase onset, GTSE1 binds preferentially to the most stable mitotic spindle microtubules and promotes their turnover. Cells depleted of GTSE1 show defects in chromosome alignment at the metaphase plate and in spindle pole integrity. These defects are coupled with an increase in the proportion of stable mitotic spindle microtubules. A consequence of this reduced microtubule turnover is diminished recruitment and activity of Aurora B kinase on chromosome arms. This decrease in Aurora B results in diminished binding of the chromokinesin Kif4A to chromosome arms.

PEAR1 is not a major susceptibility gene for cardiovascular disease in a Flemish population

Background

Platelet Endothelial Aggregation Receptor 1 (PEAR1), a membrane protein highly expressed in platelets and endothelial cells, plays a role in platelet contact-induced activation, sustained platelet aggregation and endothelial function. Previous reports implicate PEAR1 rs12041331 as a variant influencing risk in patients with coronary heart disease. We investigated whether genetic variation in PEAR1 predicts cardiovascular outcome in a white population.

Methods

In 1938 participants enrolled in the Flemish Study on Environment, Genes and Health Outcomes (51.3% women; mean age 43.6 years), we genotyped 9 tagging SNPs in PEAR1, measured baseline cardiovascular risk factors, and recorded Cardiovascular disease incidence. For SNPs, we contrasted cardiovascular disease incidence of minor-allele heterozygotes and homozygotes (variant) vs. major-allele homozygotes (reference) and for haplotypes carriers vs. non-carriers. In adjusted analyses, we accounted for family clusters and baseline covariables, including sex, age, body mass index, mean arterial pressure, the total-to-HDL cholesterol ratio, smoking and drinking, antihypertensive drug treatment, and history of cardiovascular disease and diabetes mellitus.

Results

Over a median follow-up of 15.3 years, 238 died and 181 experienced a major cardiovascular endpoint. The multivariable-adjusted hazard ratios of eight PEAR1 SNPs, including rs12566888, ranged from 0.87 to 1.07 (P ≥0.35) and from 0.78 to 1.30 (P ≥0.15), respectively. The hazard ratios of three haplotypes with frequency ≥10% ranged from 0.93 to 1.11 (P ≥0.49) for mortality and from 0.84 to 1.03 (P ≥0.29) for a cardiovascular complications. These results were not influenced by intake of antiplatelet drugs, nonsteroidal anti-inflammatory drugs, or both (P-values for interaction ≥ 0.056).

Conclusions

In a White population, we could not replicate previous reports from experimental studies or obtained in patients suggesting that PEAR1 might be a susceptibility gene for cardiovascular complications.

Electronic supplementary material

The online version of this article (doi:10.1186/s12881-017-0411-x) contains supplementary material, which is available to authorized users.

Association of PEAR1 rs12041331 polymorphism and pharmacodynamics of ticagrelor in healthy Chinese volunteers

1. Genetic polymorphisms in platelet endothelial aggregation receptor 1 (PEAR1) were associated with responsiveness to aspirin and P2Y12 receptor antagonists. This study aimed to investigate whether PEAR1 polymorphism is associated with ticagrelor pharmacodynamics in healthy Chinese subjects. 2. The in vitro inhibition of platelet aggregation (IPA) was evaluated before and after ticagrelor incubated with platelet-rich plasma from 196 healthy Chinese male subjects. Eight polymorphisms at PEAR1 locus were genotyped. Eighteen volunteers (six in each rs12041331 genotype group) were randomly selected. After a single oral 180 mg dose of ticagrelor, plasma levels of ticagrelor and the active metabolite AR-C124910XX were measured and pharmacodynamics parameters including IPA and VASP-platelet reactivity index (PRI) were assessed. 3. No significant difference in ticagrelor pharmacokinetics among rs12041331 genotype was observed. As compared with rs12041331 G allele carriers, AA homozygotes exhibited increased IPA after 15 μM ticagrelor incubation (p < 0.01), increased area under the time-effect curve of IPA and lower PRI at 2 h after ticagrelor administration (p < 0.05, respectively). Rs4661012 GG homozygotes showed increased IPA after 50 μM ticagrelor incubation as compared to T allele carriers (p < 0.01). 4. PEAR1 polymorphism may influence ticagrelor pharmacodynamics in healthy Chinese subjects.

Prospective Evaluation of Genetic Variation in Platelet Endothelial Aggregation Receptor 1 Reveals Aspirin-Dependent Effects on Platelet Aggregation Pathways

Genetic variation in the platelet endothelial aggregation receptor 1 (PEAR1) gene, most notably rs12041331, is implicated in altered on‐aspirin platelet aggregation and increased cardiovascular event risk. We prospectively tested the effects of aspirin administration at commonly prescribed doses (81, 162, and 324 mg/day) on agonist‐induced platelet aggregation by rs12041331 genotype in 67 healthy individuals. Prior to aspirin administration, rs12041331 minor allele carriers had significantly reduced adenosine diphosphate (ADP)‐induced platelet aggregation compared with noncarriers (P = 0.03) but was not associated with other platelet pathways. In contrast, rs12041331 was significantly associated with on‐aspirin platelet aggregation when collagen and epinephrine were used to stimulate platelet aggregation (P < 0.05 for all associations), but not ADP. The influence of PEAR1 rs12041331 on platelet aggregation is pathway‐specific and is altered by aspirin at therapeutic doses, but not in a dose‐dependent manner. Additional studies are needed to determine the impact of PEAR1 on cardiovascular events in aspirin‐treated patients.

PEAR1 gene polymorphism in a Chinese pedigree with pulmonary thromboembolism

To explore the correlation between platelet endothelial aggregation receptor-1 (PEAR1) genetic polymorphism and pulmonary thromboembolism (PTE).Variant loci of the PEAR1 gene were screened in a PTE pedigree, followed by verification using Sanger sequencing. These polymorphic loci were validated in 101 PTE patients and 132 matched normal patients using MassARRAY single nucleotide polymorphism (SNP) genotyping methods. The frequency differences between the allele and genotypes were compared using the Hardy-Weinberg equilibrium test and Chi-square test. The correlation between the PEAR1 gene SNP and PTE was analyzed by comparing the between-group variance differences using the χ test.Three SNPs were identified in the PTE pedigree. There was a heterozygous transition of T>C in rs1952294, and a transition of C>T in rs778026543 in 2 members in the pedigree; however, the rs778026543 was not identified in the 101 PTE patients and 132 healthy controls. The genotype and allele frequencies of rs822442 did not differ significantly between PTE patients and healthy controls (P > 0.05). The variance difference at rs778026543 between pedigree members and healthy controls was significant (P < 0.001), supporting its potential heredity.The PEAR1 polymorphism, rs778026543, but not rs1952294 and rs822442, may be a susceptibility SNP for PTE.

Genetic Regulation of Endothelial Vasomotor Function

The endothelium plays an important role in the regulation of vasomotor tone and the maintenance of vascular integrity. Endothelial dysfunction, i.e., impaired endothelial dependent dilation, is a fundamental component of the pathogenesis of cardiovascular disease. Although endothelial dysfunction is associated with a number of cardiovascular disease risk factors, those risk factors are not the only determinants of endothelial dysfunction. Despite knowing many molecules involved in endothelial signaling pathways, the genetic contribution to endothelial function has yet to be fully elucidated. This mini-review summarizes current evidence supporting the genetic contribution to endothelial vasomotor function. Findings from population-based studies, association studies for candidate genes, and unbiased large genomic scale studies in humans and rodent models are discussed. A brief synopsis of the current studies addressing the genetic regulation of endothelial responses to exercise training is also included.

Allele-specific DNA methylation reinforces PEAR1 enhancer activity

Genetic variation in the PEAR1 locus is linked to platelet reactivity and cardiovascular disease. The major G allele of rs12041331, an intronic cytosine guanine dinucleotide-single-nucleotide polymorphism (CpG-SNP), is associated with higher PEAR1 expression in platelets and endothelial cells than the minor A allele. The molecular mechanism underlying this difference remains elusive. We have characterized the histone modification profiles of the intronic region surrounding rs12041331 and identified H3K4Me1 enhancer-specific enrichment for the region that covers the CpG-SNP. Interestingly, methylation studies revealed that the CpG site is fully methylated in leukocytes of GG carriers. Nuclear protein extracts from megakaryocytes, endothelial cells, vs control HEK-293 cells show a 3-fold higher affinity for the methylated G allele compared with nonmethylated G or A alleles in a gel electrophoretic mobility shift assay. To understand the positive relationship between methylation and gene expression, we studied DNA methylation at 4 different loci of PEAR1 during in vitro megakaryopoiesis. During differentiation, the CpG-SNP remained fully methylated, while we observed rapid methylation increases at the CpG-island overlapping the first 5'-untranslated region exon, paralleling the increased PEAR1 expression. In the same region, A-allele carriers of rs12041331 showed significantly lower DNA methylation at CGI1 compared with GG homozygote. This CpG-island contains binding sites for the methylation-sensitive transcription factor CTCF, whose binding is known to play a role in enhancer activation and/or repression. In conclusion, we report the molecular characterization of the first platelet function-related CpG-SNP, a genetic predisposition that reinforces PEAR1 enhancer activity through allele-specific DNA methylation.