OBJECTIVE To identify the mechanisms by which the formyl peptide receptor 2(FPR2)mediates both inflammatory and anti-inflammatory signaling in an agonist-dependent manner.METHODS Cells expressing FPR2 were incubated w...OBJECTIVE To identify the mechanisms by which the formyl peptide receptor 2(FPR2)mediates both inflammatory and anti-inflammatory signaling in an agonist-dependent manner.METHODS Cells expressing FPR2 were incubated with weak agonists,Aβ42 and Ac2-26,before stimulation with a strong agonist,WKYMVm.Calcium mobilization,c AMP inhibition and MAP kinase activation were measured.Intramolecular FRET were determined using FPR2 constructs with an ECFP attached to the C-terminus and a Fl As H binding motif embedded in the first or third intracellular loop(IL1 or IL3,respectively).RESULTS Aβ42 did not induce significant Ca^(2+) mobilization,but positively modulated WKYMVm-induced Ca^(2+) mobilization and c AMP reduction in a dose-variable manner within a narrow range of ligand concentrations.Treating FPR2-expressing cells with Ac2-26,a peptide with anti-inflammatory activity,negatively modulated WKYMVm-induced Ca^(2+) mobilization and c AMP reduction.Intramolecular FRET assay showed that stimulation of the receptor constructs with Aβ42 brought the C-terminal domain closer to IL1 but away from IL3.An opposite conformational change was induced by Ac2-26.The FPR2 conformation induced by Aβ42 corresponded to enhanced ERK phosphorylation and attenuated p38 MAPK phosphorylation,whereas Ac2-26 induced FPR2 conformational change corresponding to elevated p38 MAPK phosphorylation and reduced ERK phosphorylation.CONCLUSION Aβ42 and Ac2-26 induce different conformational changes in FPR2.These findings provide a structural basis for FPR2 mediation of inflammatory vs anti-inflammatory functions and identify a type of receptor modulation that differs from the classic positive and negative allosteric modulation.展开更多
AIM: To elucidate the mechanisms of mesenteric vasodilation in portal hypertension (PHT), with a focus on endothelin signaling. METHODS: PHT was induced in rats by common bile duct ligation (CBDL). Portal pressure (PP...AIM: To elucidate the mechanisms of mesenteric vasodilation in portal hypertension (PHT), with a focus on endothelin signaling. METHODS: PHT was induced in rats by common bile duct ligation (CBDL). Portal pressure (PP) was measured directly via catheters placed in the portal vein tract. The level of endothelin-1 (ET-1) in the mesenteric circulation was determined by radioimmunoassay, and the expression of the endothelin A receptor (ETAR) and endothelin B receptor (ETBR) was assessed by immunofluorescence and Western blot. Additionally, expression of G protein coupled kinase-2 (GRK2) and β-arrestin 2, which influence endothelin receptor sensitivity, were also studied by Western blot. RESULTS: PP of CBDL rats increased significantly (11.89 ± 1.38 mmHg vs 16.34 ± 1.63 mmHg). ET-1 expression decreased in the mesenteric circulation 2 and 4 wk after CBDL. ET-1 levels in the systemic circulation of CBDL rats were increased at 2 wk and decreased at 4 wk. There was no change in ETAR expression in response to CBDL; however, increased expression of ETBR in the endothelial cells of mesenteric arterioles and capillaries was observed. In sham-operated rats, ETBR was mainly expressed in the CD31+ endothelial cells of the arterioles. With development of PHT, in addition to the endothelial cells, ETBR expression was noticeably detectable in the SMA+ smooth muscle cells of arterioles and in the CD31+ capillaries. Following CBDL, increased expression of GRK2 was also found in mesenteric tissue, though there was no change in the level of β-arrestin 2. CONCLUSION: Decreased levels of ET-1 and increased ETBR expression in the mesenteric circulation following CBDL in rats may underlie mesenteric vasodilation in individuals with PHT. Mechanistically, increased GRK2 expression may lead to desensitization of ETAR, as well as other vasoconstrictors, promoting this vasodilatory effect.展开更多
BACKGROUND: The increased β-arrestin-2 and its combination with G-protein-coupled receptors (GPCRs) lead to GPCRs desensitization. The latter may be responsible for decreased contractile reactivity in the mesenteric ...BACKGROUND: The increased β-arrestin-2 and its combination with G-protein-coupled receptors (GPCRs) lead to GPCRs desensitization. The latter may be responsible for decreased contractile reactivity in the mesenteric arteries of cirrhotic patients and rats. The present study is to investigate the machinery changes of α-adrenergic receptors and G proteins and their roles in the contractility of mesenteric arteries of cirrhotic patients and animal models. METHODS: Patients with cirrhosis due to hepatitis B and cirrhotic rats induced by CCl 4 were studied. Mesenteric artery contractility in response to norepinephrine was determined by a vessel perfusion system. The contractile effect of G protein-coupled receptor kinase-2 (GRK-2) inhibitor on the mesenteric artery was evaluated. The protein expression of the α 1 adrenergic receptor, G proteins, β-arrestin-2, GRK-2 as well as the activity of Rho associated coiled-coil forming protein kinase-1 (ROCK-1) were measured by Western blot. In addition, the interaction of α 1 adrenergic receptor with β-arrestin-2 was assessed by co-immunoprecipitation. RESULTS: The portal vein pressure of cirrhotic patients and rats was significantly higher than that of controls. The doseresponse curve to norepinephrine in mesenteric arteriole was shifted to the right, and EC 50 was significantly increased in cirrhotic patients and rats. There were no significant differences in the expressions of the α 1 adrenergic receptor and G proteins in the cirrhotic group compared with the controls. However, the protein expressions of GRK-2 and β-arrestin-2 were significantly elevated in cirrhotic patients and rats compared with those of the controls. The interaction of the α 1 adrenergic receptor and β-arrestin-2 was significantly aggravated. This interaction was significantly reversed by GRK-2 inhibitor. Both the protein expression and activity of ROCK-1 were significantly decreased in the mesenteric artery in patients with cirrhosis compared with those of the controls, and this phenomenon was not shown in the cirrhotic rats. Norepinephrine significantly increased the activity of ROCK-1 in normal rats but not in cirrhotic ones. Norepinephrine significantly increased ROCK-1 activity in cirrhotic rats when GRK-2 inhibitor was used. CONCLUSIONS: β-arrestin-2 expression and its interaction with GPCRs are significantly upregulated in the mesenteric arteries in patients and rats with cirrhosis. These upregulations result in GPCR desensitization, G-protein dysfunction and ROCK inhibition. These may explain the decreased contractility of the mesenteric artery in response to vasoconstrictors.展开更多
BACKGROUND： Organophosphorus insecticides may promote the accumulation of acetylcholine at synapses and the neuromuscular junction by inhibiting acetylcholinesterase activity to cause disturbance of neural signal con...BACKGROUND： Organophosphorus insecticides may promote the accumulation of acetylcholine at synapses and the neuromuscular junction by inhibiting acetylcholinesterase activity to cause disturbance of neural signal conduction and induce a toxic reaction. Organophosphorus insecticides may act on M2 muscarinic acetylcholine receptors, whose combination with G proteins is regulated by phosphorylation of G protein-coupled receptor kinase 2. OBJECTIVE： To investigate the effects of organophosphorus insecticides on the phosphorylation of G protein-coupled receptor kinase 2-mediated M2 muscarinic acetylcholine receptors and to reveal other possible actions of organophosphorus insecticides. DESIGN, TIME AND SETTING： An observational study, which was performed in the Central Laboratory of Shenyang Medical College, and Department of Physiological Sciences, College of Veterinary Medicine, Oklahoma State University from June 2002 to December 2004. MATERIALS： Paraoxon, parathion, chlorpyrifos, and chlorpyrifos oxon were provided by Chem Service Company, USA, [γ -p^32] ATP and [^35S]GTP γ S by New England Nuclear Life Science Products, and recombinant β 2-adrenergic receptor membrane protein by Sigma Company, USA. METHODS： The M2 muscarinic acetylcholine receptor was extracted and purified from pig brain using affinity chromatography. Subsequently, the purified M2 muscarinic acetylcholine receptor, G protein-coupled receptor kinase 2, and [γ -p^32] ATP were incubated with different concentrations of paraoxon and chlorpyrifos oxon together. The mixture then underwent polyacrylamide gel electrophoresis, and the gel film was dried and radioactively autographed to detect phosphorylation of the M2 muscarinic acetylcholine receptor. Finally, the radio-labeled phosphorylated M2 receptor protein band was excised for counting with an isotope liquid scintillation counter. MAIN OUTCOME MEASURES： Effects of chlorpyrifos oxon, paraoxon, chlorpyrifos, and parathion in different concentrations on the phosphorylation of the M2 muscarinic acetylcholine receptor; effects of chlorpyrifos oxon on the phosphorylation of the β -adrenergic receptor. RESULTS： Chlorpyrifos oxon could completely inhibit the phosphorylation of the M2 muscarinic acetylcholine receptor, and its IC50 was 70 μ mol/L. Chlorpyrifos could also inhibit the phosphorylation of the M2 muscarinic acetylcholine receptor. However, paraoxon and parathion could not inhibit the phosphorylation of the M2 muscarinic acetylcholine receptor. Chlorpyrifos oxon in different concentrations could also not inhibit the phosphorylation of the β 2-adrenergic receptor catalyzed by G protein-coupled receptor kinase 2. CONCLUSION： Different kinds of organophosphorus insecticides have different effects on the phosphorylation of the G protein-coupled receptor kinase 2-mediated M2 muscarinic acetylcholine receptor. Organophosphorus insecticides possibly have different toxic effects.展开更多
目的分析75岁以上老年急性非ST段抬高型心肌梗死(NSTEMI)患者外周血淋巴细胞G蛋白偶联受体激酶2(GRK2)与血清可溶性ST2(sST2)水平在心力衰竭(心衰)预警中的意义。方法选取75岁以上老年男性急性NSTEMI患者80例作为急性心肌梗死(AMI)组,...目的分析75岁以上老年急性非ST段抬高型心肌梗死(NSTEMI)患者外周血淋巴细胞G蛋白偶联受体激酶2(GRK2)与血清可溶性ST2(sST2)水平在心力衰竭(心衰)预警中的意义。方法选取75岁以上老年男性急性NSTEMI患者80例作为急性心肌梗死(AMI)组,平均年龄(85.4±3.2)岁;选取同期体检的健康老年男性30例作为对照组,平均年龄(84.8±2.9)岁。测定2组患者GRK2、血清sST2水平,并行超声心动图检测LVEF、左心室收缩末期容积(LVESV)、左心室舒张末期容积(LVEDV)。AMI组患者在发病后3、6、12、24个月时进行随访。结果AMI组患者GRK2的表达、血清sST2水平均高于对照组[3.60 vs 0.72,(30.63±1.36)μg/L vs (26.87±0.55)μg/L,P<0.01],LVEF低于对照组[(50.87±4.58)%vs (55.15±5.87)%,P<0.01]。AMI组GRK2在发病后3、6、12、24个月随访时逐渐增高(P<0.05,P<0.01),sST2水平在发病后6、12、24个月随访时显著增高(P<0.05),LVEF在发病后6、12、24个月随访时显著降低(P<0.01)。结论 75岁以上老年男性急性NSTEMI患者GRK2对AMI后心衰的预警作用优于sST2。展开更多
目的观察美托洛尔对老年男性心肌梗死病人外周血淋巴细胞G蛋白偶联受体激酶2(GRK2)表达的影响。方法选取65岁以上急性非ST段抬高型心肌梗死病人80例,分为对照组和美托洛尔组。对照组行常规治疗,美托洛尔组在常规治疗基础上应用美托洛尔...目的观察美托洛尔对老年男性心肌梗死病人外周血淋巴细胞G蛋白偶联受体激酶2(GRK2)表达的影响。方法选取65岁以上急性非ST段抬高型心肌梗死病人80例,分为对照组和美托洛尔组。对照组行常规治疗,美托洛尔组在常规治疗基础上应用美托洛尔,随访2年。分别于发病24 h内和治疗3、6、12、24个月时行心脏超声检查,并分别抽取外周血2 m L,分离淋巴细胞,提取RNA及蛋白,检测GRK2 mRNA和蛋白的表达水平。结果治疗前2组心脏超声各项指标、外周血淋巴细胞GRK2的表达无明显差异;治疗后,美托洛尔组GRK2表达逐渐降低,治疗12个月后GRK2表达水平明显低于对照组,而心脏射血分数则显著高于对照组。结论老年急性非ST段抬高型心肌梗死病人经美托洛尔治疗后,外周血淋巴细胞GRK2表达水平明显降低,心脏射血分数等指标无明显变化。随着疗程的增加,治疗效果越显著。展开更多
基金supported by National Natural Science Foundation of China(31470856 to RDY)the Science and Technology Development Fund of Macao(FDCT 072/2015/A2)the University of Macao(SRG2015-00047-ICMS-QRCM)
文摘OBJECTIVE To identify the mechanisms by which the formyl peptide receptor 2(FPR2)mediates both inflammatory and anti-inflammatory signaling in an agonist-dependent manner.METHODS Cells expressing FPR2 were incubated with weak agonists,Aβ42 and Ac2-26,before stimulation with a strong agonist,WKYMVm.Calcium mobilization,c AMP inhibition and MAP kinase activation were measured.Intramolecular FRET were determined using FPR2 constructs with an ECFP attached to the C-terminus and a Fl As H binding motif embedded in the first or third intracellular loop(IL1 or IL3,respectively).RESULTS Aβ42 did not induce significant Ca^(2+) mobilization,but positively modulated WKYMVm-induced Ca^(2+) mobilization and c AMP reduction in a dose-variable manner within a narrow range of ligand concentrations.Treating FPR2-expressing cells with Ac2-26,a peptide with anti-inflammatory activity,negatively modulated WKYMVm-induced Ca^(2+) mobilization and c AMP reduction.Intramolecular FRET assay showed that stimulation of the receptor constructs with Aβ42 brought the C-terminal domain closer to IL1 but away from IL3.An opposite conformational change was induced by Ac2-26.The FPR2 conformation induced by Aβ42 corresponded to enhanced ERK phosphorylation and attenuated p38 MAPK phosphorylation,whereas Ac2-26 induced FPR2 conformational change corresponding to elevated p38 MAPK phosphorylation and reduced ERK phosphorylation.CONCLUSION Aβ42 and Ac2-26 induce different conformational changes in FPR2.These findings provide a structural basis for FPR2 mediation of inflammatory vs anti-inflammatory functions and identify a type of receptor modulation that differs from the classic positive and negative allosteric modulation.
基金Supported by Grant from National Key New Drug Creation Project of China, No. 2009ZX09102
文摘AIM: To elucidate the mechanisms of mesenteric vasodilation in portal hypertension (PHT), with a focus on endothelin signaling. METHODS: PHT was induced in rats by common bile duct ligation (CBDL). Portal pressure (PP) was measured directly via catheters placed in the portal vein tract. The level of endothelin-1 (ET-1) in the mesenteric circulation was determined by radioimmunoassay, and the expression of the endothelin A receptor (ETAR) and endothelin B receptor (ETBR) was assessed by immunofluorescence and Western blot. Additionally, expression of G protein coupled kinase-2 (GRK2) and β-arrestin 2, which influence endothelin receptor sensitivity, were also studied by Western blot. RESULTS: PP of CBDL rats increased significantly (11.89 ± 1.38 mmHg vs 16.34 ± 1.63 mmHg). ET-1 expression decreased in the mesenteric circulation 2 and 4 wk after CBDL. ET-1 levels in the systemic circulation of CBDL rats were increased at 2 wk and decreased at 4 wk. There was no change in ETAR expression in response to CBDL; however, increased expression of ETBR in the endothelial cells of mesenteric arterioles and capillaries was observed. In sham-operated rats, ETBR was mainly expressed in the CD31+ endothelial cells of the arterioles. With development of PHT, in addition to the endothelial cells, ETBR expression was noticeably detectable in the SMA+ smooth muscle cells of arterioles and in the CD31+ capillaries. Following CBDL, increased expression of GRK2 was also found in mesenteric tissue, though there was no change in the level of β-arrestin 2. CONCLUSION: Decreased levels of ET-1 and increased ETBR expression in the mesenteric circulation following CBDL in rats may underlie mesenteric vasodilation in individuals with PHT. Mechanistically, increased GRK2 expression may lead to desensitization of ETAR, as well as other vasoconstrictors, promoting this vasodilatory effect.
基金supported by a grant from the National Natural Science Foundation of China (30972920)
文摘BACKGROUND: The increased β-arrestin-2 and its combination with G-protein-coupled receptors (GPCRs) lead to GPCRs desensitization. The latter may be responsible for decreased contractile reactivity in the mesenteric arteries of cirrhotic patients and rats. The present study is to investigate the machinery changes of α-adrenergic receptors and G proteins and their roles in the contractility of mesenteric arteries of cirrhotic patients and animal models. METHODS: Patients with cirrhosis due to hepatitis B and cirrhotic rats induced by CCl 4 were studied. Mesenteric artery contractility in response to norepinephrine was determined by a vessel perfusion system. The contractile effect of G protein-coupled receptor kinase-2 (GRK-2) inhibitor on the mesenteric artery was evaluated. The protein expression of the α 1 adrenergic receptor, G proteins, β-arrestin-2, GRK-2 as well as the activity of Rho associated coiled-coil forming protein kinase-1 (ROCK-1) were measured by Western blot. In addition, the interaction of α 1 adrenergic receptor with β-arrestin-2 was assessed by co-immunoprecipitation. RESULTS: The portal vein pressure of cirrhotic patients and rats was significantly higher than that of controls. The doseresponse curve to norepinephrine in mesenteric arteriole was shifted to the right, and EC 50 was significantly increased in cirrhotic patients and rats. There were no significant differences in the expressions of the α 1 adrenergic receptor and G proteins in the cirrhotic group compared with the controls. However, the protein expressions of GRK-2 and β-arrestin-2 were significantly elevated in cirrhotic patients and rats compared with those of the controls. The interaction of the α 1 adrenergic receptor and β-arrestin-2 was significantly aggravated. This interaction was significantly reversed by GRK-2 inhibitor. Both the protein expression and activity of ROCK-1 were significantly decreased in the mesenteric artery in patients with cirrhosis compared with those of the controls, and this phenomenon was not shown in the cirrhotic rats. Norepinephrine significantly increased the activity of ROCK-1 in normal rats but not in cirrhotic ones. Norepinephrine significantly increased ROCK-1 activity in cirrhotic rats when GRK-2 inhibitor was used. CONCLUSIONS: β-arrestin-2 expression and its interaction with GPCRs are significantly upregulated in the mesenteric arteries in patients and rats with cirrhosis. These upregulations result in GPCR desensitization, G-protein dysfunction and ROCK inhibition. These may explain the decreased contractility of the mesenteric artery in response to vasoconstrictors.
文摘BACKGROUND： Organophosphorus insecticides may promote the accumulation of acetylcholine at synapses and the neuromuscular junction by inhibiting acetylcholinesterase activity to cause disturbance of neural signal conduction and induce a toxic reaction. Organophosphorus insecticides may act on M2 muscarinic acetylcholine receptors, whose combination with G proteins is regulated by phosphorylation of G protein-coupled receptor kinase 2. OBJECTIVE： To investigate the effects of organophosphorus insecticides on the phosphorylation of G protein-coupled receptor kinase 2-mediated M2 muscarinic acetylcholine receptors and to reveal other possible actions of organophosphorus insecticides. DESIGN, TIME AND SETTING： An observational study, which was performed in the Central Laboratory of Shenyang Medical College, and Department of Physiological Sciences, College of Veterinary Medicine, Oklahoma State University from June 2002 to December 2004. MATERIALS： Paraoxon, parathion, chlorpyrifos, and chlorpyrifos oxon were provided by Chem Service Company, USA, [γ -p^32] ATP and [^35S]GTP γ S by New England Nuclear Life Science Products, and recombinant β 2-adrenergic receptor membrane protein by Sigma Company, USA. METHODS： The M2 muscarinic acetylcholine receptor was extracted and purified from pig brain using affinity chromatography. Subsequently, the purified M2 muscarinic acetylcholine receptor, G protein-coupled receptor kinase 2, and [γ -p^32] ATP were incubated with different concentrations of paraoxon and chlorpyrifos oxon together. The mixture then underwent polyacrylamide gel electrophoresis, and the gel film was dried and radioactively autographed to detect phosphorylation of the M2 muscarinic acetylcholine receptor. Finally, the radio-labeled phosphorylated M2 receptor protein band was excised for counting with an isotope liquid scintillation counter. MAIN OUTCOME MEASURES： Effects of chlorpyrifos oxon, paraoxon, chlorpyrifos, and parathion in different concentrations on the phosphorylation of the M2 muscarinic acetylcholine receptor; effects of chlorpyrifos oxon on the phosphorylation of the β -adrenergic receptor. RESULTS： Chlorpyrifos oxon could completely inhibit the phosphorylation of the M2 muscarinic acetylcholine receptor, and its IC50 was 70 μ mol/L. Chlorpyrifos could also inhibit the phosphorylation of the M2 muscarinic acetylcholine receptor. However, paraoxon and parathion could not inhibit the phosphorylation of the M2 muscarinic acetylcholine receptor. Chlorpyrifos oxon in different concentrations could also not inhibit the phosphorylation of the β 2-adrenergic receptor catalyzed by G protein-coupled receptor kinase 2. CONCLUSION： Different kinds of organophosphorus insecticides have different effects on the phosphorylation of the G protein-coupled receptor kinase 2-mediated M2 muscarinic acetylcholine receptor. Organophosphorus insecticides possibly have different toxic effects.
文摘目的分析75岁以上老年急性非ST段抬高型心肌梗死(NSTEMI)患者外周血淋巴细胞G蛋白偶联受体激酶2(GRK2)与血清可溶性ST2(sST2)水平在心力衰竭(心衰)预警中的意义。方法选取75岁以上老年男性急性NSTEMI患者80例作为急性心肌梗死(AMI)组,平均年龄(85.4±3.2)岁;选取同期体检的健康老年男性30例作为对照组,平均年龄(84.8±2.9)岁。测定2组患者GRK2、血清sST2水平,并行超声心动图检测LVEF、左心室收缩末期容积(LVESV)、左心室舒张末期容积(LVEDV)。AMI组患者在发病后3、6、12、24个月时进行随访。结果AMI组患者GRK2的表达、血清sST2水平均高于对照组[3.60 vs 0.72,(30.63±1.36)μg/L vs (26.87±0.55)μg/L,P<0.01],LVEF低于对照组[(50.87±4.58)%vs (55.15±5.87)%,P<0.01]。AMI组GRK2在发病后3、6、12、24个月随访时逐渐增高(P<0.05,P<0.01),sST2水平在发病后6、12、24个月随访时显著增高(P<0.05),LVEF在发病后6、12、24个月随访时显著降低(P<0.01)。结论 75岁以上老年男性急性NSTEMI患者GRK2对AMI后心衰的预警作用优于sST2。
文摘目的观察美托洛尔对老年男性心肌梗死病人外周血淋巴细胞G蛋白偶联受体激酶2(GRK2)表达的影响。方法选取65岁以上急性非ST段抬高型心肌梗死病人80例,分为对照组和美托洛尔组。对照组行常规治疗,美托洛尔组在常规治疗基础上应用美托洛尔,随访2年。分别于发病24 h内和治疗3、6、12、24个月时行心脏超声检查,并分别抽取外周血2 m L,分离淋巴细胞,提取RNA及蛋白,检测GRK2 mRNA和蛋白的表达水平。结果治疗前2组心脏超声各项指标、外周血淋巴细胞GRK2的表达无明显差异;治疗后,美托洛尔组GRK2表达逐渐降低,治疗12个月后GRK2表达水平明显低于对照组,而心脏射血分数则显著高于对照组。结论老年急性非ST段抬高型心肌梗死病人经美托洛尔治疗后,外周血淋巴细胞GRK2表达水平明显降低,心脏射血分数等指标无明显变化。随着疗程的增加,治疗效果越显著。
