G-protein-coupled Receptor 15 Research Articles

The fifth epidermal growth factor like region of thrombomodulin alleviates LPS-induced sepsis through interacting with GPR15.

Thrombomodulin (TM) exerts cytoprotection via the fifth region of epidermal growth factor (EGF)-like domain of TM (TME5) by interacting with G-protein coupled receptor 15 (GPR15) expressed on cell surface of vascular endothelial cells. TM is also implied to mediate anti-inflammatory functions by unknown mechanism. By applying a lipopolysaccharide (LPS)-induced murine sepsis model, we assessed the role of TME5 in septic inflammation and coagulation. We found that TME5 treatment protected mice in association with ameliorating inflammation and coagulopathy in LPS-induced sepsis. Further study confirmed that TME5 bound GPR15 in vitro. Knock out of GPR15 abolished protective role of TME5 in sepsis model. GPR15 mediated anti-inflammatory function of TME5 through suppression of phosphorylation of IκBα, nuclear translocation of NF-κB and release of pro-inflammatory cytokines in macrophages (Macs). Knock out of GPR15 resulted in dysregulated immune response of Macs, characterised by excessive expression of pro-inflammatory genes and failing to limit immune response. This study indicates that TME5 exerts anti-inflammatory function through inhibition of NF-κB in a GPR15-dependent manner. The use of TME5 may be a potential therapeutic option for treatment of sepsis.

Abstract 416: G Protein-coupled Receptor 15 is Associated with Inflammation, Smoking and Ischemia

Introduction: The mechanisms leading to myocardial infarction (MI) are still not fully understood. As the orphan G protein-coupled receptor 15 ( GPR15 ) gene has recently been shown to be hypomethylated in smokers as well as to be involved in inflammation, it poses a new candidate gene for cardiovascular disease. Hypothesis: We hypothesized that GPR15 influences the development of MI via smoking and inflammation. Methods: To investigate the effect of smoking and changes in expression over time, monocytic GPR15 mRNA expression was measured in smokers (n = 273), ex-smokers (n = 533) and never-smokers (n = 687) from the Gutenberg Health Study (GHS) via qPCR. In order to assess GPR15 expression after MI, mRNA expression in peripheral blood mononuclear cells was compared between 112 young MI cases (< 50 years) and 112 controls from the GHS using the Affymetrix Exon ST1.0 GeneChip Array. Subsequently, cardiac GPR15 expression in mouse models of MI (n = 8), myocarditis (n = 8), hypertrophy (n = 6) and untreated controls was measured via qPCR. Results: GPR15 expression was significantly increased in smokers compared to never-smokers (16.0 ± 2.4-fold, p < 0.001). Ex-smokers still had significantly elevated GPR15 expression levels compared to never-smokers up to ten years after quitting (3.9 ± 0.9-fold, p < 0.001). Furthermore, GPR15 expression was 1.43-fold higher in young MI patients compared to controls (± 0.09-fold, p = 1.9*10 -7 ). Likewise, mouse Gpr15 expression was significantly elevated in infarcted hearts (6.3 ± 1.1 fold, p < 0.05) and in inflamed hearts (10.2 ± 2.5 fold, p < 0.01) but not in the hypertrophic hearts (1.0 ± 0.3) compared to controls. Conclusion: Consistent with literature on GPR15 methylation, GPR15 expression was increased in smokers, but also after inflammation and ischemia, independently of smoking. In conclusion, GPR15 might play a role in the development of myocardial infarction via smoking and inflammatory mechanisms.

Epigenomic association analysis identifies smoking-related DNA methylation sites in African Americans.

Cigarette smoking is an environmental risk factor for many chronic diseases, and disease risk can often be managed by smoking control. Smoking can induce cellular and molecular changes, including epigenetic modification, but the short- and long-term epigenetic modifications caused by cigarette smoking at the gene level have not been well understood. Recent studies have identified smoking-related DNA methylation (DNAm) sites in Caucasians. To determine whether the same DNAm sites associate with smoking in African Americans, and to identify novel smoking-related DNAm sites, we conducted a methylome-wide association study of cigarette smoking using a discovery sample of 972 African Americans, and a replication sample of 239 African Americans with two array-based methods. Among 15 DNAm sites significantly associated with smoking after correction for multiple testing in our discovery sample, 5 DNAm sites are replicated in an independent cohort, and 14 sites in the replication sample have effects in the same direction as in the discovery sample. The top two smoking-related DNAm sites in F2RL3 (factor II receptor-like 3) and GPR15 (G-protein-coupled receptor 15) observed in African Americans are consistent with previous findings in Caucasians. The associations between the replicated DNAm sites and smoking remain significant after adjusting for genetic background. Despite the distinct genetic background between African Americans and Caucasians, the DNAm from the two ethnic groups shares common associations with cigarette smoking, which suggests a common molecular mechanism of epigenetic modification influenced by environmental exposure.

Cigarette smoking behaviors and time since quitting are associated with differential DNA methylation across the human genome

The impact of cigarette smoking can persist for extended periods following smoking cessation and may involve epigenetic reprogramming. Changes in DNA methylation associated with smoking may help to identify molecular pathways that contribute to the latency between exposure and disease onset. Cross-sectional cohort data from subjects in the International COPD Genetics Network (n = 1085) and the Boston Early-Onset COPD study (n = 369) were analyzed as the discovery and replication cohorts, respectively. Genome-wide methylation data on 27 578 CpG sites in 14 475 genes were obtained on DNA from peripheral blood leukocytes using the Illumina HumanMethylation27K Beadchip in both cohorts. We identified 15 sites significantly associated with current smoking, 2 sites associated with cumulative smoke exposure, and, within the subset of former smokers, 3 sites associated with time since quitting cigarettes. Two loci, factor II receptor-like 3 (F2RL3) and G-protein-coupled receptor 15 (GPR15), were significantly associated in all three analyses and were validated by pyrosequencing. These findings (i) identify a novel locus (GPR15) associated with cigarette smoking and (ii) suggest the existence of dynamic, site-specific methylation changes in response to smoking which may contribute to the extended risks associated with cigarette smoking that persist after cessation.