Many G protein-coupled receptors （GPCRs） are reported to be involved in the pathogenesis of multiple sclerosis （MS）, and -40% of all identified GPCRs rely on the Gaq/11 G protein family to stimulate inositol lipid...Many G protein-coupled receptors （GPCRs） are reported to be involved in the pathogenesis of multiple sclerosis （MS）, and -40% of all identified GPCRs rely on the Gaq/11 G protein family to stimulate inositol lipid signaling. However, the function of Ga subunits in MS pathogenesis is still unknown. In this study, we attempted to determine the role of Gaq in the pathogenesis of experimental autoimmune encephalomyelitis （EAE）, a well-known mouse model of MS. We discovered that compared with wild-type mice, Gaq-knockout mice exhibited less severe EAE symptoms, with lower clinical scores, reduced leukocyte infiltration and less extensive demyelination. Moreover, a significantly lower percentage of Th17 cells, one of the key players in MS pathogenesis, was observed in Gaq-knockout EAE mice. Studies in vitro demonstrated that deficiency of Gaq in CD4＋ T cells directly impaired Th17 differentiation. In addition, deficiency of Gaq significantly impaired DC-derived IL-6 production, thus inhibiting Th17 differentiation and the Gaq-PLCβ-PKC and Gaq-MAPKs signaling pathways involved in the reduced IL-6 production by DCs. In summary, our data highlighted the critical role of Gaq in regulating Th17 differentiation and MS oathogenesis.展开更多
mobilization of body fat is essential for energy homeostasis in animals. In insects, the adipokinetic hormone （Akh） systemically controls body fat mobilization. Biochemical evidence supports that Akh signals via a G...mobilization of body fat is essential for energy homeostasis in animals. In insects, the adipokinetic hormone （Akh） systemically controls body fat mobilization. Biochemical evidence supports that Akh signals via a G protein-coupled receptor （GPCR） called Akh receptor （AkhR） using cyclic-AMP （cAMP） and Ca2＋ second messengers to induce storage lipid release from fat body cells. Recently, we provided genetic evidence that the intracellular calcium （iCa2＋） level in fat storage cells controls adiposity in the fruit fly Drosophila melanogaster. However, little is known about the genes, which mediate Akh signalling downstream of the AkhR to regulate changes in iCa2＋. Here, we used thermogenetics to provide in vivo evidence that the GPCR signal transducers G protein α q subunit （Gαq）, G protein γ1 （Gγ1） and Phospholipase C at 21C （Plc21C） control cellular and organismal fat storage in Drosophila. Transgenic modulation of Gαq, Gγ1 and Plc21C affected the iCa2＋ of fat body cells and the expression profile of the lipid metabolism effector genes midway and brummer, which results in severely obese or lean flies. Moreover, functional impairment of Gαq, Gγ1 and Plc21C antagonised Akh-induced fat depletion. This study characterizes Gαq, Gγ1 and Plc21C as anti-obesity genes and supports the model that Akh employs the Gαq/Gγ1/Plc21C module of iCa2＋ control to regulate lipid mobilization in adult Drosophila.展开更多
RGS(regulators of G protein signaling)是G蛋白偶联信号通路中一类重要的调节蛋白,通过加速Gα结合的GTP水解,即GAP(GTPase activating protein)活性,来中止G蛋白信号通路。RGS4是RGS蛋白家族中的重要成员之一,它能有效中止Gαq介导...RGS(regulators of G protein signaling)是G蛋白偶联信号通路中一类重要的调节蛋白,通过加速Gα结合的GTP水解,即GAP(GTPase activating protein)活性,来中止G蛋白信号通路。RGS4是RGS蛋白家族中的重要成员之一,它能有效中止Gαq介导的信号通路。作者研究了Gαq蛋白对RGS4蛋白的表达调控。当在HEK293细胞中共转染这两个蛋白时,持续性激活的Gαq能特异性地显著增加RGS4蛋白的表达。蛋白降解实验结果证明这种增强作用与RGS4的降解被抑制无关,而与RGS4 mRNA表达增强有关。进一步克隆RGS4蛋白的启动子区域并研究其与RGS4表达相互关系的实验结果又表明,持续性激活的Gαq能够显著增强RGS4启动子区的转录活性,且具有时间和浓度效应。同时,转录因子结合区突变体实验证明,ICE(inverted CCAAT box element)转录因子结合区的突变显著影响RGS4基因的转录活性。以上结果表明Gαq可能通过RGS4的启动子区调控其基因的表达,促进RGS4蛋白表达。展开更多
Objectives To investigate the effect of Gαq/11 signaling pathway and ATP-sensitive potassium channel ( KATP channel ) on ischemic preconditioning (IPC) protection in rat hearts. Methods Two series of experiments were...Objectives To investigate the effect of Gαq/11 signaling pathway and ATP-sensitive potassium channel ( KATP channel ) on ischemic preconditioning (IPC) protection in rat hearts. Methods Two series of experiments were performed in Wistar rat hearts. In the first series of experiment, ischemic preconditioning was induced by left anterior descending occlusion (three, 5 min episodes separated by 5 min of reperfusion), ischemia-reperfusion injury was induced by 30 min coronary artery occlusion followed by 90 min reperfusion. Hemodynamics, infarct size and scores of ventricular arrhythmias were measured. The expression of Gαq/11 protein in the heart was measured by Western blot analysis in the second series. Results Ischemic preconditioning rats showed decreased infarct size and scores of ventricular arrhythmia vs non-IP control rats. The effect of IPC was significantly attenuated by glibenclamide (1 mg/kg, ip), a nonselective KATP channel inhibitor. IPC caused a significant increase in the expression of Gαq/11 protein. Conclusions Activations of Gαq/11 signal pathway and KATP channel played significant roles in the classical cardioprotection of ischemic precon-ditioning rat heart and might be an important mechanism of signal transduction pathway during the ischemic preconditioning.展开更多
基金This work was supported by grants from the Ministry of Science and Technology of China （2014CB541903, 2012CB910404）, the National Natural Science Foundation of China （31171348, 31371414）, the Shanghai Municipal Education Commission （14zz042）, the State Key Laboratory of Drug Research （SIMM1302KF-09） and the Fundamental Research Funds for the Central Universities.
文摘Many G protein-coupled receptors （GPCRs） are reported to be involved in the pathogenesis of multiple sclerosis （MS）, and -40% of all identified GPCRs rely on the Gaq/11 G protein family to stimulate inositol lipid signaling. However, the function of Ga subunits in MS pathogenesis is still unknown. In this study, we attempted to determine the role of Gaq in the pathogenesis of experimental autoimmune encephalomyelitis （EAE）, a well-known mouse model of MS. We discovered that compared with wild-type mice, Gaq-knockout mice exhibited less severe EAE symptoms, with lower clinical scores, reduced leukocyte infiltration and less extensive demyelination. Moreover, a significantly lower percentage of Th17 cells, one of the key players in MS pathogenesis, was observed in Gaq-knockout EAE mice. Studies in vitro demonstrated that deficiency of Gaq in CD4＋ T cells directly impaired Th17 differentiation. In addition, deficiency of Gaq significantly impaired DC-derived IL-6 production, thus inhibiting Th17 differentiation and the Gaq-PLCβ-PKC and Gaq-MAPKs signaling pathways involved in the reduced IL-6 production by DCs. In summary, our data highlighted the critical role of Gaq in regulating Th17 differentiation and MS oathogenesis.
基金supported by the Max Planck Society and by the German research foundation(No.DFG KU 2866/1-1 toR.P.K.)
文摘mobilization of body fat is essential for energy homeostasis in animals. In insects, the adipokinetic hormone （Akh） systemically controls body fat mobilization. Biochemical evidence supports that Akh signals via a G protein-coupled receptor （GPCR） called Akh receptor （AkhR） using cyclic-AMP （cAMP） and Ca2＋ second messengers to induce storage lipid release from fat body cells. Recently, we provided genetic evidence that the intracellular calcium （iCa2＋） level in fat storage cells controls adiposity in the fruit fly Drosophila melanogaster. However, little is known about the genes, which mediate Akh signalling downstream of the AkhR to regulate changes in iCa2＋. Here, we used thermogenetics to provide in vivo evidence that the GPCR signal transducers G protein α q subunit （Gαq）, G protein γ1 （Gγ1） and Phospholipase C at 21C （Plc21C） control cellular and organismal fat storage in Drosophila. Transgenic modulation of Gαq, Gγ1 and Plc21C affected the iCa2＋ of fat body cells and the expression profile of the lipid metabolism effector genes midway and brummer, which results in severely obese or lean flies. Moreover, functional impairment of Gαq, Gγ1 and Plc21C antagonised Akh-induced fat depletion. This study characterizes Gαq, Gγ1 and Plc21C as anti-obesity genes and supports the model that Akh employs the Gαq/Gγ1/Plc21C module of iCa2＋ control to regulate lipid mobilization in adult Drosophila.
文摘RGS(regulators of G protein signaling)是G蛋白偶联信号通路中一类重要的调节蛋白,通过加速Gα结合的GTP水解,即GAP(GTPase activating protein)活性,来中止G蛋白信号通路。RGS4是RGS蛋白家族中的重要成员之一,它能有效中止Gαq介导的信号通路。作者研究了Gαq蛋白对RGS4蛋白的表达调控。当在HEK293细胞中共转染这两个蛋白时,持续性激活的Gαq能特异性地显著增加RGS4蛋白的表达。蛋白降解实验结果证明这种增强作用与RGS4的降解被抑制无关,而与RGS4 mRNA表达增强有关。进一步克隆RGS4蛋白的启动子区域并研究其与RGS4表达相互关系的实验结果又表明,持续性激活的Gαq能够显著增强RGS4启动子区的转录活性,且具有时间和浓度效应。同时,转录因子结合区突变体实验证明,ICE(inverted CCAAT box element)转录因子结合区的突变显著影响RGS4基因的转录活性。以上结果表明Gαq可能通过RGS4的启动子区调控其基因的表达,促进RGS4蛋白表达。
文摘Objectives To investigate the effect of Gαq/11 signaling pathway and ATP-sensitive potassium channel ( KATP channel ) on ischemic preconditioning (IPC) protection in rat hearts. Methods Two series of experiments were performed in Wistar rat hearts. In the first series of experiment, ischemic preconditioning was induced by left anterior descending occlusion (three, 5 min episodes separated by 5 min of reperfusion), ischemia-reperfusion injury was induced by 30 min coronary artery occlusion followed by 90 min reperfusion. Hemodynamics, infarct size and scores of ventricular arrhythmias were measured. The expression of Gαq/11 protein in the heart was measured by Western blot analysis in the second series. Results Ischemic preconditioning rats showed decreased infarct size and scores of ventricular arrhythmia vs non-IP control rats. The effect of IPC was significantly attenuated by glibenclamide (1 mg/kg, ip), a nonselective KATP channel inhibitor. IPC caused a significant increase in the expression of Gαq/11 protein. Conclusions Activations of Gαq/11 signal pathway and KATP channel played significant roles in the classical cardioprotection of ischemic precon-ditioning rat heart and might be an important mechanism of signal transduction pathway during the ischemic preconditioning.
