G protein-coupled receptor 37(GPR37) emerges as an important modulator of adenosinergic transmission in the striatum

G protein-coupled receptor 37 (GPR37), also known as parkin associated endothelin-like (Pael) receptor, is an orphan G protein- coupled receptor, which suffers a defective parking ubiquitination in autosomal recessive Parkinson’s disease promoting its endoplasmic reticulum aggregation and stress, neurotoxicity and neuronal death (Takahashi and Imai, 2003). Interestingly, we have demonstrated previously that GPR37 heteromerizes with adenosine A2A receptor (A2AR) in the striatum (Morato et al., 2017;Sokolina et al., 2017).

转录因子GRHL3调控GPR108基因表达及其作用机制

目的研究转录因子果蝇头状因子(grainyhead-like,GRHL)3调控G蛋白偶联受体108(G protein-coupled receptor 108,GPR108)表达的分子机制。方法利用生物信息学分析在各种癌症组织的肿瘤细胞中,GRHL3和GPR108的表达水平以及相互关系;运用反转录定量聚合酶链反应(reverse transcription quantitative polymerase chain reaction,RT-qPCR)检测GRHL3和GPR108基因在人皮肤鳞癌细胞系(A-431)、人肝癌细胞系(Hep G2)以及人神经母细胞瘤细胞系(SH-SY5Y)的表达;采用分子克隆技术构建含有GPR108基因启动子和突变型GPR108基因启动子的荧光素酶报告基因表达载体;通过双荧光素酶报告基因检测系统,观察GRHL3对GPR108基因启动子的调控作用;通过染色质免疫共沉淀(chromatin immunoprecipitation assay,ChIP)分析GRHL3和GPR108启动子结合位点之间的关系。结果生物信息学分析在各种组织的肿瘤细胞中,GRHL3的表达较低,而GPR108的表达较高。利用分子克隆技术成功构建了GPR108基因启动子和突变型GPR108基因启动子荧光素酶报告基因表达载体;GRHL3对荧光素酶报告基因GPR108的启动子具有明显的抑制作用。将GPR108启动子上的结合位点删除突变后,GRHL3对GPR108基因启动子的负调控作用减弱;ChIP结果显示GRHL3能与GPR108启动子结合位点结合。结论转录因子GRHL3通过结合GPR108启动子上的保守序列5′-AACCGGTG-3′抑制GPR108表达。

GPR108缺失对脂多糖诱发脓毒症小鼠的炎症反应

目的探究G蛋白偶联受体108(GPR108)的缺失对脂多糖(LPS)诱导的脓毒症小鼠所产生全身性炎症反应的影响。方法雄性C57BL/6小鼠和GPR108基因敲除鼠随机分为4组:WT组、WT-LPS组、KO组、KO-LPS组。观察不同组小鼠的生理特征,肝脏、肺组织的形态变化。提取骨髓来源的巨噬细胞流式检测其M1极化情况,同时检测其肝脏、肺组织、巨噬细胞及血清的白细胞介素-6(IL-6)的表达水平。结果KO-LPS组小鼠肝脏、肺组织损伤表现明显,KO-LPS组小鼠较WT-LPS组小鼠骨髓源性巨噬细胞向M1极化的数量明显多;同时,KO-LPS组小鼠在组织水平、细胞水平、血清水平检测IL-6的表达均明显高于WT-LPS组小鼠(P<0.05)。结论在LPS诱导的脓毒症小鼠全身性炎症感染时,GPR108缺失加重全身炎症反应。GPR108对LPS诱导的脓毒症小鼠的炎症反应具有抑制作用。

Sphingosine 1-phosphate acts as an activator for the porcine Gpr3 of constitutively active G protein-coupled receptors

We cloned the complete coding sequences of porcine Gpr3, Gpr6, and Gpr12 genes. Further, on the basis of their high levels of sequence similarity, these genes are identified as a subfamily of G protein-coupled receptors. These putative protein sequences also showed high sequence identity with other mammalian orthologs, including several highly conserved motifs. A wide expression of the Gpr3 gene in pigs was observed through tissue distribution analysis by reverse transcriptase-polymerase chain reaction （RT-PCR） and real-time PCR, specially in the brain, pituitary, fat, liver and oocyte, where its strong expression was observed. The Gpr3 gene was found to be located on chromosome 6 and a single exon coded for the entire open reading frame. Expression of porcine Gpr3 in HEK293 cells resulted in constitutive activation of adenylate cyclase （AC） similar in amplitude to that produced by fully stimulated Gs coupled receptors. Moreover, sphingosine 1-phosphate （S1P） could increase AC activation via the constitutively active Gpr3 receptor. When a Gpr3-green fluorescent protein （GFP） construct was expressed in HEK293 cells, GFP-labeled Gpr3 protein was shown to be localized in the plasmalemma and subcellular membranes. After S1P treatment, agonist-mediated internalization could be visualized by confocal microscopy. In short, our findings suggest the porcine Gpr3, Gpr6, and Gpr12 genes as a subfamily of G protein-coupled receptors, and porcine Gpr3 was a constitutively active G protein-coupled receptor. Constitutive activation of AG and agonist-mediated internalization of Gpr3 receptor could be modulated by the S1 P, suggesting that S1P might act as an activator for porcine Gpr3 receptor.

Structure,ligands,and roles of GPR126/ADGRG6 in the development and diseases

Adhesion G protein-coupled receptors(aGPCRs)are the second largest diverse group within the GPCR superfamily,which play critical roles in many physiological and patho-logical processes through cell-cell and cell-extracellular matrix interactions.The adhesion GPCR Adgrg6,also known as GPR126,is one of the better-characterized aGPCRs.GPR126 was previously found to have critical developmental roles in Schwann cell maturation and its mediated myelination in the peripheral nervous system in both zebrafish and mammals.Current studies have extended our understanding of GPR126-mediated roles during develop-ment and in human diseases.In this review,we highlighted these recent advances in GPR126 in expression profile,molecular structure,ligand-receptor interactions,and associated physiological and pathological functions in development and diseases.

Molecular Mechanism of Action of GPR91 Agonists and Antagonists:Insights from Molecular Dynamics Simulation

G protein-coupled receptor 91(GPR91)has garnered widespread attention as a prospective therapeutic target for metabolic diseases.However,no structural data for human GPR91(hGPR91);detailed molecular mechanism of action(MOA)of GPR91 have been reported,with reported compounds targeting GPR91 limited.In this study,hGPR91 structures were constructed through homology modeling.High-affinity agonist compound 31 and antagonist NF-58-EJ40 were selected for investigation.By molecular dynamics(MD)simulations,we have elucidated MOA of GPR91 agonists and antagonists for the first time.We identified the crucial role of the D174FASSG sequence,the L652.46SVSD2.50 sequence and the N642.45-W1474.50 in maintaining GPR91’s inactive state conformation.Agonist binding disrupted constraints mediated by the aforementioned sequence,which led to significant outward movements of transmembrane helixes(TMs);repositioning of intracellular loop2(ICL2);ICL3,thereby forming an expanded cavity for G proteins binding.Furthermore,the pivotal role of the dicarboxylic acid structure of agonists in initiating signal transduction was confirmed.In contrast,antagonist binding stabilized these conformational constraints,resulting in relatively minor movements of TMs that were insufficient to generate a binding cavity large enough to accommodate the G protein.Clarifying MOA of GPR91 agonists and antagonists is crucial for guiding the design of relevant drugs.