PEAR1 is a potential regulator of early hematopoiesis of human pluripotent stem cells.

Hemogenic endothelial (HE) cells are specialized endothelial cells to give rise to hematopoietic stem/progenitor cells during hematopoietic development. The underlying mechanisms that regulate endothelial-to-hematopoietic transition (EHT) of human HE cells are not fully understand. Here, we identified platelet endothelial aggregation receptor-1 (PEAR1) as a novel regulator of early hematopoietic development in human pluripotent stem cells (hPSCs). We found that the expression of PEAP1 was elevated during hematopoietic development. A subpopulation of PEAR1+ cells overlapped with CD34+ CD144+ CD184+ CD73- arterial-type HE cells. Transcriptome analysis by RNA sequencing indicated that TAL1/SCL, GATA2, MYB, RUNX1 and other key transcription factors for hematopoietic development were mainly expressed in PEAR1+ cells, whereas the genes encoding for niche-related signals, such as fibronectin, vitronectin, bone morphogenetic proteins and jagged1, were highly expressed in PEAR1- cells. The isolated PEAR1+ cells exhibited significantly greater EHT capacity on endothelial niche, compared with the PEAR1- cells. Colony-forming unit (CFU) assays demonstrated the multilineage hematopoietic potential of PEAR1+ -derived hematopoietic cells. Furthermore, PEAR1 knockout in hPSCs by CRISPR/Cas9 technology revealed that the hematopoietic differentiation was impaired, resulting in decreased EHT capacity, decreased expression of hematopoietic-related transcription factors, and increased expression of niche-related signals. In summary, this study revealed a novel role of PEAR1 in balancing intrinsic and extrinsic signals for early hematopoietic fate decision.

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.

Platelet activation by charged ligands and nanoparticles: platelet glycoprotein receptors as pattern recognition receptors.

Charge interactions play a critical role in the activation of the innate immune system by damage- and pathogen-associated molecular pattern receptors. The ability of these receptors to recognize a wide spectrum of ligands through a common mechanism is critical in host defense. In this article, we argue that platelet glycoprotein receptors that signal through conserved tyrosine-based motifs function as pattern recognition receptors (PRRs) for charged endogenous and exogenous ligands, including sulfated polysaccharides, charged proteins and nanoparticles. This is exemplified by GPVI, CLEC-2 and PEAR1 which are activated by a wide spectrum of endogenous and exogenous ligands, including diesel exhaust particles, sulfated polysaccharides and charged surfaces. We propose that this mechanism has evolved to drive rapid activation of platelets at sites of injury, but that under some conditions it can drive occlusive thrombosis, for example, when blood comes into contact with infectious agents or toxins. In this Opinion Article, we discuss mechanisms behind charge-mediated platelet activation and opportunities for designing nanoparticles and related agents such as dendrimers as novel antithrombotics.

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.

Platelet endothelial aggregation receptor-1 (PEAR1) is involved in C2C12 myoblast differentiation.

C2C12 murine myoblasts are a common model for studying muscle differentiation. Platelet endothelial aggregation receptor-1 (PEAR1), an epidermal growth factor repeat-containing transmembrane receptor, is known to participate in platelet contact-induced activation. In the present study, we demonstrated that PEAR1 is involved in the differentiation of C2C12 murine myoblasts. Western blotting and immunofluorescence staining were used to determine PEAR1 expression and localization during C2C12 cell differentiation. Subsequently, PEAR1 expression was activated and inhibited using clustered regularly interspaced short palindromic repeats-dCas9 technology to explore its effects on this process. PEAR1 expression was found to increase over the course of C2C12 cell differentiation. This protein was predominately localized on the membrane of these cells, where it clustered upon induction of differentiation. Expression of the myogenic markers Desmin, MYOG, and MYH2 revealed that PEAR1 positively regulated C2C12 cell differentiation. Moreover, induction of muscle injury by administration of bupivacaine to mice indicated that PEAR1 might play a role in muscle regeneration. In summary, our study confirmed the involvement of PEAR1 in C2C12 cell differentiation, contributing to our understanding of the molecular mechanisms underlying muscle development.

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.

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.

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.

Dextran sulfate triggers platelet aggregation via direct activation of PEAR1.

UNLABELLED: Dextran sulfate (DxS; Mr 500 kD) induces fibrinogen receptor (αIIbß3) activation via CLEC-2/Syk signaling and via a Syk-independent SFK/PI3K/Akt-dependent tyrosine kinase pathway in human and murine platelets. The platelet surface receptor, responsible for the DxS-induced Syk-independent Akt-activation, has hitherto not been identified. We found that DxS elicited a concentration-dependent aggregation of human platelets resulting from direct PEAR1 activation by DxS. Blocking the PEAR1 receptor, in combination with a selective Syk-inhibitor, completely abrogated the DxS-driven platelet aggregation. The DxS-induced Syk-phosphorylation was not affected in Pear1(-/-) platelets, but Akt-phosphorylation was largely abolished. As a result, the aggregation of Pear1(-/-) platelets was reduced and reversible, i.e. aggregates were less stable compared to wild-type platelet aggregates. Moreover, DxS-induced Pear1(-/-) platelet aggregation was fully abrogated by Syk inhibition, indicating that the remaining platelet aggregation of Pear1(-/-) platelets was Syk dependent. Hence, the Pear1/c-Src/PI3K/Akt- and CLEC-2/Syk-signaling pathways are independently and additively activated during platelet aggregation by DxS. CONCLUSION: The DxS-induced aggregation of human and murine platelets is the result of activation of PI3K/Akt through direct PEAR1 phosphorylation and parallel Syk-signaling through CLEC-2.

Genetic Polymorphisms of GP1BA, PEAR1, and PAI-1 may be Associated with Serum sIgE and Blood Eosinophil Levels in Chinese Patients with Allergic Diseases.

BACKGROUND: It has been suggested that genetic factors may be substantially linked to allergy disorders. OBJECTIVE: This study aims to investigate the relationship between the serum specific Immunoglobulin E (sIgE), blood eosinophil, and the polymorphisms of glycoprotein Ib alpha gene (GP1BA) rs6065, platelet endothelial aggregation receptor 1 gene (PEAR1) rs12041331, and plasminogen activator inhibitor 1 gene (PAI-1) rs1799762. METHODS: From the Peking Union Medical College Hospital, this study enrolled 60 healthy participants and 283 participants with allergic diseases. TaqMan-minor groove binder (MGB) quantitative polymerase chain reaction (qPCR) was used to examine the gene polymorphisms in each group. RESULTS: The TaqMan-MGB qPCR results were completely consistent with the DNA sequencing results, according to other studies in this medical center (Kappa =1, p <0.001). The GP1BA rs6065, PEAR1 rs12041331, and PAI-1 rs1799762 polymorphisms did not show different distribution between allergy patients and healthy individuals. Concerning allergy patients, the CT (n=33) genotype of GP1BA rs6065 had higher blood eosinophil level than the CC (n=250) genotype (0.59, IQR 0.32-0.72 vs 0.31, IQR 0.15-0.61, *109/L, p =0.005). The serum sIgE of AA (n=46) genotype of PEAR1 rs12041331 was lower (median 3.7, interquartile quartiles (IQR) 0.2-16.8, kU/L) than the GA (n=136) and GG (n=101) genotypes (GA median 16.3, IQR 3.1-46.3, kU/L, p = 0.002; GG median 12.9, IQR 3.0-46.9, kU/L, p =0.003). The GA genotypes of PEAR1 rs12041331were with higher blood eosinophil levels (median 0.42, IQR 0.17-0.74 *109/L) than the AA genotype (median 0.25, IQR 0.15-0.41*109/L, p =0.012). The sIgE of the 5G5G (n=44) genotype of PAI-1 rs1799762 was lower (median 5.0, IQR 0.1-22.8, kU/L) than the 4G5G (n=144) (median 17.3, IQR 3.7-46.0, kU/L, p = 0.012). CONCLUSION: The GP1BA rs6065, PEAR1 rs12041331, and PAI-1 rs1799762 polymorphisms may be associated with the genetic susceptibility of serum sIgE or blood eosinophil in Chinese allergic disease patients.

Using the PEAR1 Polymorphisms Rs12041331 and Rs2768759 as Potential Predictive Markers of 90-Day Bleeding Events in the Context of Minor Strokes and Transient Ischemic Attack.

In this study, we explored the relationship between the platelet endothelial aggregation receptor 1 (PEAR1) polymorphisms, platelet reactivity, and clinical outcomes in patients with minor stroke or transient ischemic attack (TIA). Randomized controlled trial subgroups were assessed, wherein patients received dual antiplatelet therapy for at least 21 days. Platelet reactivity was measured at different time intervals. Genotypes were categorized as wild-type, mutant heterozygous, and mutant homozygous. Clinical outcomes were evaluated after 90 days. The rs12041331 polymorphism predominantly influenced adenosine diphosphate channel platelet activity, with the AA genotype displaying significantly lower residual platelet activity to the P2Y12 response unit (p < 0.01). This effect was more evident after 7 days of dual antiplatelet treatment (p = 0.016). Mutant A allele carriers had decreased rates of recurrent stroke and complex endpoint events but were more prone to bleeding (p = 0.015). The rs2768759 polymorphism majorly impacted arachidonic acid (AA) channel platelet activity, which was particularly noticeable in the C allele carriers. Our regression analysis demonstrated that rs12041331 AA + GA and rs2768759 CA predicted 90-day post-stroke bleeding. In conclusion, the PEAR1 polymorphisms rs12041331 and rs2768759 interfere with platelet aggregation and the performance of antiplatelet drugs. These genetic variations may contribute to bleeding events associated with minor stroke and TIA.

Impact of the PEAR1 polymorphism on clinical outcomes in Chinese patients receiving dual antiplatelet therapy after percutaneous coronary intervention.

Background: Patients might still experience major adverse cardiovascular events even with dual antiplatelet therapy after percutaneous coronary intervention. Our study aimed to explore the impact of gene polymorphism on clinical outcomes in one-year follow-up. Methods: A total of 171 patients treated with dual antiplatelet therapy after percutaneous coronary intervention from April to December 2020 in the first hospital of Jilin University enrolled in this study. Results: PEAR1 genetic polymorphisms was associated with the arachidonic acid (AA) and adenosine diphosphate (ADP) platelet aggregation. Hyperglycemia was associated with the rate of major adverse cardiovascular events. PEAR1 GA+AA genetic genetic polymorphisms is associated with hyperglycemia. Conclusion:PEAR1 GG is a risk factor for AA and ADP platelet aggregation. Hyperglycemia can effect the one-year outcome. PEAR1 GA+AA genetic polymorphisms are associated with hyperglycemia.

Platelet Endothelial Aggregation Receptor 1 Polymorphism Is Associated With Functional Outcome in Small-Artery Occlusion Stroke Patients Treated With Aspirin.

Background: The role of genetic polymorphisms is important in defining the patient's prognosis and outcomes in coronary artery disease. The present study aimed to explore the association between platelet endothelial aggregation receptor 1 (PEAR1) rs12041331 polymorphism and the outcomes in patients with acute ischemic stroke treated with aspirin or dual antiplatelet therapy (DAPT) with clopidogrel. Methods: A total of 868 ischemic stroke patients admitted to our hospital from January 1, 2016 to December 30, 2018 were retrospectively studied. The Trial of Org 10172 in Acute Stroke Treatment (TOAST) classification defined stroke subtypes. These patients were treated with aspirin alone or DAPT. The genotype distribution of PEAR1 rs12041331 single-nucleotide polymorphism (AA, AC, and CC) between different TOAST subtypes and treatment groups was assessed, and the clinical impact of genetic variants on functional outcomes defined by the National Institutes of Health Stroke Scale, modified Rankin Scale, and Barthel Index was analyzed using univariate and multivariate logistic regression models. Results: Among the 868 stroke patients, the PEAR1 AA genotype was 16%, GA was 47%, and GG was 36%. Forty-four percent had aspirin alone, and 56% had DAPT. Overall, the distribution of PEAR single-nucleotide polymorphism was not significant among the two treatment groups or subtypes of TOAST. In contrast, in patients treated with aspirin alone, PEAR1 AA tended to be higher in the small-artery occlusion (SAO) subtype when compared with the no-lacunar subtype, including cardioembolism and large-artery atherosclerosis. PEAR1 AA genotype was significantly associated with favorable functional outcomes at day 7 and discharge only in SAO patients treated with aspirin alone compared with the GG genotype. Multivariate regression models further suggested that AA genotype was independently associated with favorable outcomes in this group after being adjusted for three common stroke risk factors such as age, hypertension history, and C-reactive protein level [odds ratio (OR) 0.23, 95% confidence interval (CI), 0.07-0.64, P = 0.02 for 7-day National Institutes of Health Stroke Scale; OR 0.2, 95% CI, 0.06-0.66, P = 0.03 for 7-day modified Rankin Scale, and OR 0.25, 95% CI, 0.08-0.72, P = 0.03 for 7-day Barthel Index, respectively]. Conclusion: The impact of PEAR1 rs12041331 polymorphism on aspirin depends on the TOAST subtype. PEAR1 AA carrier with SAO stroke is most sensitive to aspirin therapy. PEAR1 AA is an independent factor for the short-term functional outcomes in SAO patients treated with aspirin alone. Clinical Registration Number: 1800019911.

Impact of Platelet Endothelial Aggregation Receptor-1 Genotypes on Long-Term Cerebrovascular Outcomes in Patients With Minor Stroke or Transient Ischemic Attack.

Background: Platelet endothelial aggregation receptor-1 (PEAR1) rs12041331 has been reported to affect agonist-stimulated platelet aggregation, but it remains unclear whether this variant plays a role in recurrent stroke. Here we assess the clinical relevance of PEAR1 rs12041331 in acute minor ischemic stroke (AMIS) and transient ischemic attack (TIA) Chinese patients treated with dual antiplatelet therapy (DAPT). Methods: We recruited 273 consecutive minor stroke and TIA patients, and Cox proportional hazard regression was used to model the relationship between PEAR1 rs12041331 and thrombotic and bleeding events. Results: Genotyping for PEAR1 rs12041331 showed 49 (18.0%) AA homozygotes, 129 (47.3%) GA heterozygotes, and 95 (34.7%) GG homozygotes. No association was observed between PEAR1 rs12041331 genotype and stroke or composite clinical vascular event rates (ischemic stroke, hemorrhagic stroke, TIA, myocardial infarction, or vascular death) or bleeding events regardless if individuals carried one or two copies of the A allele. Our results suggested that rs12041331 genetic polymorphism was not an important contributor to clinical events in AMIS and TIA patients in the setting of secondary prevention. Conclusions: Our data do provide robust evidence that genetic variation in PEAR1 rs12041331 do not contribute to atherothrombotic or bleeding risk in minor stroke and TIA patients treated with DAPT.

Platelet endothelial aggregation receptor-1 regulates bovine muscle satellite cell migration and differentiation via integrin beta-1 and focal adhesion kinase.

PEAR1 is highly expressed at bovine MDSC differentiation. However, its biological function remains unclear. Western blotting results showed that PEAR1 increased between day 0 and day 2 of cell differentiation and decreased from day 3. Moreover, scratch test showed that wound healing rate increased after PEAR1 overexpression and decreased upon its suppression. Meanwhile, we found that, upon PEAR1 induction, both the expression of the focal adhesion-associated and MyoG, and the myotube fusion rate increased. However, when PEAR1 was suppressed, opposite results were obtained. Immunoprecipitation revealed an association between PEAR1 and ITGB1. Notably, inhibition of FAK and ITGB1 repressed cell differentiation. In conclusion, our study indicated that PEAR1 is involved in the regulation of bovine MDSC migration and differentiation.

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.

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.

Absence of Pear1 does not affect murine platelet function in vivo.

BACKGROUND: Platelet Endothelial Aggregation Receptor-1 (PEAR1) is a transmembrane platelet receptor that amplifies the activation of the platelet fibrinogen receptor (αIIbß3) during platelet aggregation. In man, Pear1 polymorphisms are associated with changes in platelet aggregability. In this report, we characterized Pear1 expression and function in murine platelets. METHODS: Pear1 phosphorylation and signaling, platelet aggregation, α-degranulation and clot retraction were studied in WT and Pear1-/- platelets. The function of Pear1 in haemostasis and thrombosis was studied in a mouse tail vein bleeding and ferric chloride-induced mesenteric thrombosis model. RESULTS: Mature murine platelets express Pear1 on their membrane and clustering of Pear1 by anti-Pear1 antibodies triggered platelet aggregation. Pear1 was weakly phosphorylated during collagen-induced murine platelet aggregation and was translocated to the cytoskeleton. Absence of murine Pear1 impaired dextran sulfate-induced platelet aggregation, but did not impact collagen-, AYPGK and ADP-induced platelet aggregation, coupled to a lower Pear1 expression in murine than in human platelets and to weaker Pear1-mediated downstream signaling. Neither clot retraction nor α-degranulation was affected in Pear1-/- mice. Likewise, in vivo tests like the tail vein bleeding time and thrombus formation in mesenteric veins were similar in WT and Pear1-/- mice. CONCLUSION: Murine platelet Pear1 shares a number of characteristics with human platelet PEAR1. Nevertheless, murine Pear1 contributes less to platelet function as does human PEAR1 and does not overtly impact haemostasis and thrombosis in mice.

Platelet endothelial aggregation receptor-1: a novel modifier of neoangiogenesis.

AIMS: Platelet endothelial aggregation receptor-1 (PEAR1) is a cell membrane protein, expressed on platelets and endothelial cells (ECs). PEAR1 sustains αIIbß3 activation in aggregating platelets and attenuates megakaryopoiesis via controlling the degree of Akt phosphorylation. Its role in EC biology is unknown. The aim of this study was to determine the expression of PEAR1 in the human endothelium of various tissues and to investigate its role in ECs in vitro and in angiogenesis, using Pear1(-/-) mice. METHODS AND RESULTS: PEAR1 is present on the membrane and on filo- and lamellipodia of human cultured ECs, and its expression coincides with CD31 in various tissues. PEAR1 expression is variable in ECs of different origin. Lentiviral knockdown of PEAR1 in cultured ECs doubled EC proliferation and significantly stimulated EC migration, in turn enhancing in vitro tube formation on matrigel through the Akt/PTEN-dependent p21/CDC2 pathway. Even when physiological blood vessel formation was unaffected in Pear1(-/-) mice, neoangiogenesis in these mice was significantly increased both in a hind limb ischaemia ligation model [4.7-fold increase in capillary density in the ligated limb of Pear1(-/-) mice compared with ligated limbs in wild-type (WT) mice] and in a skin wound-healing model, resulting in a two-fold faster wound closure in Pear1(-/-) mice compared with WT littermates. CONCLUSION: We established an inverse correlation between endothelial PEAR1 expression and vascular assembly both in vitro and in vivo. These findings identify PEAR1 as a novel modifier of neoangiogenesis.