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
Heart failure(HF), the number one cause of death in the western world, is caused by the insufficient performance of the heart leading to tissue underperfusion in response to an injury or insult. It comprises complex i...Heart failure(HF), the number one cause of death in the western world, is caused by the insufficient performance of the heart leading to tissue underperfusion in response to an injury or insult. It comprises complex interactions between important neurohormonal mechanisms that try but ultimately fail to sustain cardiac output. The most prominent such mechanism is the sympathetic(adrenergic) nervous system(SNS), whose activity and outflow are greatly elevated in HF. SNS hyperactivity confers significant toxicity to the failing heart and markedly increases HF morbidity and mortality via excessive activation of adrenergic receptors, which are G protein-coupled receptors. Thus, ligand binding induces their coupling to heterotrimeric G proteins that transduce intracellular signals. G protein signaling is turned-off by the agonist-bound receptor phosphorylation courtesy of G protein-coupled receptor kinases(GRKs), followed by βarrestin binding, which prevents the GRK-phosphorylated receptor from further interaction with the G proteins and simultaneously leads it inside the cell(receptor sequestration). Recent evidence indicates that adrenal GRK2 and βarrestins can regulate adrenal catecholamine secretion, thereby modulating SNS activity in HF. The present review gives an account of all these studies on adrenal GRKs and βarrestins in HF and discusses the exciting new therapeutic possibilities for chronic HF offered by targeting these proteins pharmacologically.展开更多
BACKGROUND Gastric cancer(GC)has become a serious threat to people's health.Accumulative evidence reveals that dysregulation of numerous microRNAs(miRNAs)has been found during malignant formation.So far,the role o...BACKGROUND Gastric cancer(GC)has become a serious threat to people's health.Accumulative evidence reveals that dysregulation of numerous microRNAs(miRNAs)has been found during malignant formation.So far,the role of microRNA-760(miR-760)in the development of GC is largely unknown.AIM To measure the expression level of miR-760 in GC and investigate its role in gastric tumorigenesis.METHODS Real-time quantitative polymerase chain reaction and Western blot analysis were used to measure the expression of miR-760 and G-protein-coupled receptor kinase interacting protein-1(GIT1).Cell growth was detected by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide(MTT)and cell colony formation assays.Apoptosis was assessed by flow cytometric analysis.The relationship between miR-760 and GIT1 was verified by luciferase reporter assay.RESULTS The results showed that the expression of miR-760 was decreased in GC and associated with poor clinical outcomes in GC patients.Furthermore,miR-760 restrained cell proliferation and cell colony formation and induced apoptosis in GC cells.In addition,miR-760 directly targeted GIT1 and negatively regulated its expression in GC.GIT1 was upregulated in GC and predicted a worse prognosis in GC patients.We also found that upregulation of GIT1 weakened the inhibitory CONCLUSION In conclusion,miR-760 targets GIT1 to inhibit cell growth and promote apoptosis in GC cells.Our data demonstrate that miR-760 may be a potential target for the treatment of GC.展开更多
G-protein-coupled receptor kinases (GRKs) interact with the agonist-activated form of G-protein-coupled receptor (GPCR) to affect receptor phosphorylation and to initiate profound impairment of receptor signaling, or ...G-protein-coupled receptor kinases (GRKs) interact with the agonist-activated form of G-protein-coupled receptor (GPCR) to affect receptor phosphorylation and to initiate profound impairment of receptor signaling, or desensitization. GPCR forms the largest family of cell surface receptors, and defects in GRK function have the potential consequence to affect GPCR-stimulated biological responses in many pathological situations.展开更多
Anti-microbial peptides are essential for the intestinal innate immunity that protects the intestinal epithelia from attacks by foreign pathogens. Human β-defensin (HBD) is one of the pivotal anti-microbial peptides ...Anti-microbial peptides are essential for the intestinal innate immunity that protects the intestinal epithelia from attacks by foreign pathogens. Human β-defensin (HBD) is one of the pivotal anti-microbial peptides that are expressed in the colonic epithelia. This study investigated the effect and the signaling mechanism of inducible β-defensin HBD2 by an essential amino acid, isoleucine (Ile) in colonic epithelial cells. Here we examined the expression level of HBD2 on induction of Ile in epithelial cells, and checked this pathway. HBD2 mRNA was induced by co-incubation with IL-1α and Ile in Caco2 cells, but not by Ile alone. An inhibitor of either ERK or Gi, a subunit of G-proteins, reduced the induction of HBD2 mRNA by Ile. The treatment with Ile also increased the intracellular calcium ion concentration, thus suggesting that the GPCR and ERK signaling pathway mediate the effects of Ile. These results indicate that an essential amino acid, Ile, enhances the expression of an inducible β-defensin, namely HBD2, by IL-1α through the activation of GPCRs and ERK signaling pathway. The administration of Ile may therefore represent a possible option to safely treat intestinal inflammation.展开更多
G protein-coupled receptors(GPCRs)are the largest protein superfamily in the body,expressed in various tissues and organs,and are currently one of the most important clinical drug targets.Recently,a class of GPCRs wit...G protein-coupled receptors(GPCRs)are the largest protein superfamily in the body,expressed in various tissues and organs,and are currently one of the most important clinical drug targets.Recently,a class of GPCRs without endogenous ligands(orphan GPCRs)have been discovered.They exhibit different physiological functions in the body and act extensively on the cardiovascular and cerebrovascular systems.Among them,G protein-coupled receptor 124(GPR124)is an orphaned member of the G protein coupled receptor adhesion family that has attracted much attention.It plays a key role in promoting cerebral angiogenesis and maintaining the stability of the blood-brain barrier.It also associated with cardiovascular and cerebrovascular diseases such as cerebral ischemia and atherosclerosis.However,the role of GPR124 in these diseases,the associated signaling pathways,and possible drug intervention targets are still unclear.This article summarizes the physiological effects,pharmacological effects and related signal pathways of GPR124 published in the field of cardiovascular and cerebrovascular diseases published in recent years,in order to provide a reference for the study of the role of GPR124 in the occurrence and development of diseases.展开更多
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
Inflammatory bowel disease(IBD)is a complex disease with multiple pathogenic factors.Although the pathogenesis of IBD is still unclear,a current hypothesis suggests that genetic susceptibility,environmental factors,a ...Inflammatory bowel disease(IBD)is a complex disease with multiple pathogenic factors.Although the pathogenesis of IBD is still unclear,a current hypothesis suggests that genetic susceptibility,environmental factors,a dysfunctional immune system,the microbiome,and the interactions of these factors substantially contribute to the occurrence and development of IBD.Although existing and emerging drugs have been proven to be effective in treating IBD,none can cure IBD permanently.G protein-coupled receptors(GPCRs)are critical signaling molecules implicated in the immune response,cell proliferation,inflammation regulation and intestinal barrier maintenance.Breakthroughs in the understanding of the structures and functions of GPCRs have provided a driving force for exploring the roles of GPCRs in the pathogenesis of diseases,thereby leading to the development of GPCR-targeted medication.To date,a number of GPCRs have been shown to be associated with IBD,significantly advancing the drug discovery process for IBD.The associations between GPCRs and disease activity,disease severity,and disease phenotypes have also paved new avenues for the precise management of patients with IBD.In this review,we mainly focus on the roles of the most studied proton-sensing GPCRs,cannabinoid receptors,and estrogen-related GPCRs in the pathogenesis of IBD and their potential clinical values in IBD and some other diseases.展开更多
Estrogens play important roles in the development and progression of multiple tumor types.Accumulating evidence points to the significance of estrogen action not only in tumors of hormonally regulated tissues such as ...Estrogens play important roles in the development and progression of multiple tumor types.Accumulating evidence points to the significance of estrogen action not only in tumors of hormonally regulated tissues such as the breast,endometrium and ovary,but also in the development of colorectal cancer(CRC).The effects of estrogens in physiological and pathophysiological conditions are mediated by the nuclear estrogen receptorsαandβ,as well as the membranebound G protein-coupled estrogen receptor(GPER).The roles of GPER in CRC development and progression,however,remain poorly understood.Studies on the functions of GPER in the colon have shown that this estrogen receptor regulates colonic motility as well as immune responses in CRC-associated diseases,such as Crohn’s disease and ulcerative colitis.GPER is also involved in cell cycle regulation,endoplasmic reticulum stress,proliferation,apoptosis,vascularization,cell migration,and the regulation of fatty acid and estrogen metabolism in CRC cells.Thus,multiple lines of evidence suggest that GPER may play an important role in colorectal carcinogenesis.In this review,we present the current state of knowledge regarding the contribution of GPER to colon function and CRC.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
Coronary heart disease(CHD) continues to be the greatest mortality risk factor in the developed world. Estrogens are recognized to have great therapeutic potential to treat CHD and other cardiovascular diseases; howev...Coronary heart disease(CHD) continues to be the greatest mortality risk factor in the developed world. Estrogens are recognized to have great therapeutic potential to treat CHD and other cardiovascular diseases; however,a significant array of potentially debilitating side effects continues to limit their use. Moreover,recent clinical trials have indicated that long-term postmenopausal estrogen therapy may actually be detrimental to cardiovascular health. An exciting new development is the finding that the more recently discovered G-protein-coupled estrogen receptor(GPER) is expressed in coronary arteries-both in coronary endothelium and in smooth muscle within the vascular wall. Accumulating evidence indicates that GPER activation dilates coronary arteries and can also inhibit the prolif-eration and migration of coronary smooth muscle cells. Thus,selective GPER activation has the potential to increase coronary blood flow and possibly limit the debilitating consequences of coronary atherosclerotic disease. This review will highlight what is currently known regarding the impact of GPER activation on coronary arteries and the potential signaling mechanisms stimulated by GPER agonists in these vessels. A thorough understanding of GPER function in coronary arteries may promote the development of new therapies that would help alleviate CHD,while limiting the potentially dangerous side effects of estrogen therapy.展开更多
The renal handling of Na^+ balance is a major determinant of the blood pressure(BP) level. The inability of the kidney to excrete the daily load of Na+ represents the primary cause of chronic hypertension. Among the d...The renal handling of Na^+ balance is a major determinant of the blood pressure(BP) level. The inability of the kidney to excrete the daily load of Na+ represents the primary cause of chronic hypertension. Among the different segments that constitute the nephron, those present in the distal part(i.e., the cortical thick ascending limb, the distal convoluted tubule, the connecting and collecting tubules) play a central role in the fine-tuning of renal Na^+ excretion and are the target of many different regulatory processes that modulate Na^+ retention more or less efficiently. G-protein coupled receptors(GPCRs) are crucially involved in this regulation and could represent efficient pharmacological targets to control BP levels. In this review, we describe both classical and novel GPCR-dependent regulatory systems that have been shown to modulate renal Na^+ absorption in the distal nephron. In addition to the multiplicity of the GPCR that regulate Na^+ excretion, this review also highlights the complexity of these different pathways, and the connections between them.展开更多
AIM To investigate the expression of G protein-coupled receptor 31 (GPR31) and its clinical significance in human colorectal cancer (CRC).METHODS To determine the association between the GPR31 expression and the progn...AIM To investigate the expression of G protein-coupled receptor 31 (GPR31) and its clinical significance in human colorectal cancer (CRC).METHODS To determine the association between the GPR31 expression and the prognosis of patients, we obtained paraffin-embedded pathological specimens from 466 CRC patients who underwent initial resection. A total of 321 patients from the First Affiliated Hospital of Sun Yat-sen University from January 1996 to December 2008 were included as a training cohort, whereas 145 patients from the Sixth Affiliated Hospital of Sun Yat-sen University from January 2007 to November 2008 were included as a validation cohort. We examined GPR31 expression levels in CRC tissues from two independent cohorts via immunohistochemical staining. All patients were categorized into either a GPR31 low expression group or a GPR31 high expression group. The clinicopathological factors and the prognosis of patients in the GPR31 low expression group and GPR31 high expression group were compared.RESULTS We compared the clinicopathological factors and the prognosis of patients in the GPR31 low expression group and GPR31 high expression group. Significant differences were observed in the number of patients in pM classification between patients in the GPR31 low expression group and GPR31 high expression group (P = 0.007). The five-year survival and tumor-free survival rates of patients were 84.3% and 82.2% in the GPR31 low expression group, respectively, and both rates were 59.7% in the GPR31 high expression group (P < 0.05). Results of the Cox proportional hazard regression model revealed that GPR31 upregulation was associated with shorter overall survival and tumor-free survival of patients with CRC (P < 0.05). Multivariate analysis identified GPR31 expression in colorectal cancer as an independent predictive factor of CRC patient survival (P < 0.05).CONCLUSION High GPR31 expression levels were found to be correlated with pM classification of CRC and to serve as an independent predictive factor of poor survival of CRC patients.展开更多
In the last few years, there have been important new insights into the structural biology of G-protein coupled receptors. It is now known that allosteric binding sites are involved in the affinity and selec- tivity of...In the last few years, there have been important new insights into the structural biology of G-protein coupled receptors. It is now known that allosteric binding sites are involved in the affinity and selec- tivity of ligands for G-protein coupled receptors, and that signaling by these receptors involves both G-protein dependent and independent pathways. The present review outlines the physiological and pharmacological implications of this perspective for the design of new drugs to treat disorders of the central nervous system. Specifically, new possibilities are explored in relation to allosteric and or- thosteric binding sites on dopamine receptors for the treatment of Parkinson＇s disease, and on muscarinic receptors for Alzheimer＇s disease. Future research can seek to identify ligands that can bind to more than one site on the same receptor, or simultaneously bind to two receptors and form a dimer. For example, the design of bivalent drugs that can reach homo/hetero-dimers of D2 dopa- mine receptor holds promise as a relevant therapeutic strategy for Parkinson＇s disease. Regarding the treatment of Alzheimer＇s disease, the design of dualsteric ligands for mono-oligomeric mus- carinic receptors could increase therapeutic effectiveness by generating potent compounds that could activate more than one signaling pathway.展开更多
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.
文摘Heart failure(HF), the number one cause of death in the western world, is caused by the insufficient performance of the heart leading to tissue underperfusion in response to an injury or insult. It comprises complex interactions between important neurohormonal mechanisms that try but ultimately fail to sustain cardiac output. The most prominent such mechanism is the sympathetic(adrenergic) nervous system(SNS), whose activity and outflow are greatly elevated in HF. SNS hyperactivity confers significant toxicity to the failing heart and markedly increases HF morbidity and mortality via excessive activation of adrenergic receptors, which are G protein-coupled receptors. Thus, ligand binding induces their coupling to heterotrimeric G proteins that transduce intracellular signals. G protein signaling is turned-off by the agonist-bound receptor phosphorylation courtesy of G protein-coupled receptor kinases(GRKs), followed by βarrestin binding, which prevents the GRK-phosphorylated receptor from further interaction with the G proteins and simultaneously leads it inside the cell(receptor sequestration). Recent evidence indicates that adrenal GRK2 and βarrestins can regulate adrenal catecholamine secretion, thereby modulating SNS activity in HF. The present review gives an account of all these studies on adrenal GRKs and βarrestins in HF and discusses the exciting new therapeutic possibilities for chronic HF offered by targeting these proteins pharmacologically.
文摘BACKGROUND Gastric cancer(GC)has become a serious threat to people's health.Accumulative evidence reveals that dysregulation of numerous microRNAs(miRNAs)has been found during malignant formation.So far,the role of microRNA-760(miR-760)in the development of GC is largely unknown.AIM To measure the expression level of miR-760 in GC and investigate its role in gastric tumorigenesis.METHODS Real-time quantitative polymerase chain reaction and Western blot analysis were used to measure the expression of miR-760 and G-protein-coupled receptor kinase interacting protein-1(GIT1).Cell growth was detected by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide(MTT)and cell colony formation assays.Apoptosis was assessed by flow cytometric analysis.The relationship between miR-760 and GIT1 was verified by luciferase reporter assay.RESULTS The results showed that the expression of miR-760 was decreased in GC and associated with poor clinical outcomes in GC patients.Furthermore,miR-760 restrained cell proliferation and cell colony formation and induced apoptosis in GC cells.In addition,miR-760 directly targeted GIT1 and negatively regulated its expression in GC.GIT1 was upregulated in GC and predicted a worse prognosis in GC patients.We also found that upregulation of GIT1 weakened the inhibitory CONCLUSION In conclusion,miR-760 targets GIT1 to inhibit cell growth and promote apoptosis in GC cells.Our data demonstrate that miR-760 may be a potential target for the treatment of GC.
基金Supported by the National Natural Science Foundation of China, No. 30300465 Scientific Research Fund of Medical College of Chinese People’s Armed Police Forces, No. WY2002-19
文摘G-protein-coupled receptor kinases (GRKs) interact with the agonist-activated form of G-protein-coupled receptor (GPCR) to affect receptor phosphorylation and to initiate profound impairment of receptor signaling, or desensitization. GPCR forms the largest family of cell surface receptors, and defects in GRK function have the potential consequence to affect GPCR-stimulated biological responses in many pathological situations.
文摘Anti-microbial peptides are essential for the intestinal innate immunity that protects the intestinal epithelia from attacks by foreign pathogens. Human β-defensin (HBD) is one of the pivotal anti-microbial peptides that are expressed in the colonic epithelia. This study investigated the effect and the signaling mechanism of inducible β-defensin HBD2 by an essential amino acid, isoleucine (Ile) in colonic epithelial cells. Here we examined the expression level of HBD2 on induction of Ile in epithelial cells, and checked this pathway. HBD2 mRNA was induced by co-incubation with IL-1α and Ile in Caco2 cells, but not by Ile alone. An inhibitor of either ERK or Gi, a subunit of G-proteins, reduced the induction of HBD2 mRNA by Ile. The treatment with Ile also increased the intracellular calcium ion concentration, thus suggesting that the GPCR and ERK signaling pathway mediate the effects of Ile. These results indicate that an essential amino acid, Ile, enhances the expression of an inducible β-defensin, namely HBD2, by IL-1α through the activation of GPCRs and ERK signaling pathway. The administration of Ile may therefore represent a possible option to safely treat intestinal inflammation.
基金Natural Science Foundation of China(No.81960663,81860640)Key Project of Education Department of Hainan Province(No.Hnky2019ZD-25)。
文摘G protein-coupled receptors(GPCRs)are the largest protein superfamily in the body,expressed in various tissues and organs,and are currently one of the most important clinical drug targets.Recently,a class of GPCRs without endogenous ligands(orphan GPCRs)have been discovered.They exhibit different physiological functions in the body and act extensively on the cardiovascular and cerebrovascular systems.Among them,G protein-coupled receptor 124(GPR124)is an orphaned member of the G protein coupled receptor adhesion family that has attracted much attention.It plays a key role in promoting cerebral angiogenesis and maintaining the stability of the blood-brain barrier.It also associated with cardiovascular and cerebrovascular diseases such as cerebral ischemia and atherosclerosis.However,the role of GPR124 in these diseases,the associated signaling pathways,and possible drug intervention targets are still unclear.This article summarizes the physiological effects,pharmacological effects and related signal pathways of GPR124 published in the field of cardiovascular and cerebrovascular diseases published in recent years,in order to provide a reference for the study of the role of GPR124 in the occurrence and development of diseases.
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National Natural Science Foundation of China,No.81570502the 1.3.5 Project for Disciplines of Excellence,West China Hospital,Sichuan University,No.ZYJC18037.
文摘Inflammatory bowel disease(IBD)is a complex disease with multiple pathogenic factors.Although the pathogenesis of IBD is still unclear,a current hypothesis suggests that genetic susceptibility,environmental factors,a dysfunctional immune system,the microbiome,and the interactions of these factors substantially contribute to the occurrence and development of IBD.Although existing and emerging drugs have been proven to be effective in treating IBD,none can cure IBD permanently.G protein-coupled receptors(GPCRs)are critical signaling molecules implicated in the immune response,cell proliferation,inflammation regulation and intestinal barrier maintenance.Breakthroughs in the understanding of the structures and functions of GPCRs have provided a driving force for exploring the roles of GPCRs in the pathogenesis of diseases,thereby leading to the development of GPCR-targeted medication.To date,a number of GPCRs have been shown to be associated with IBD,significantly advancing the drug discovery process for IBD.The associations between GPCRs and disease activity,disease severity,and disease phenotypes have also paved new avenues for the precise management of patients with IBD.In this review,we mainly focus on the roles of the most studied proton-sensing GPCRs,cannabinoid receptors,and estrogen-related GPCRs in the pathogenesis of IBD and their potential clinical values in IBD and some other diseases.
基金Supported by grants from the National Science Centre,Poland(2017/24/T/NZ5/00045 and2015/17/N/NZ5/00336 to Damian Jacenik)the U.S.National Institutes of Health(NIH R01CA163890 and CA194496 to Eric R.Prossnitz+3 种基金 R01 CA207051 to Ellen J.Beswick)the UNM Comprehensive Cancer Center(P30 CA118100)the Autophagy,Inflammation and Metabolism Center of Biomedical Research Excellence(P20 GM121176)Dialysis Clinic,Inc.(to Eric R.Prossnitz)
文摘Estrogens play important roles in the development and progression of multiple tumor types.Accumulating evidence points to the significance of estrogen action not only in tumors of hormonally regulated tissues such as the breast,endometrium and ovary,but also in the development of colorectal cancer(CRC).The effects of estrogens in physiological and pathophysiological conditions are mediated by the nuclear estrogen receptorsαandβ,as well as the membranebound G protein-coupled estrogen receptor(GPER).The roles of GPER in CRC development and progression,however,remain poorly understood.Studies on the functions of GPER in the colon have shown that this estrogen receptor regulates colonic motility as well as immune responses in CRC-associated diseases,such as Crohn’s disease and ulcerative colitis.GPER is also involved in cell cycle regulation,endoplasmic reticulum stress,proliferation,apoptosis,vascularization,cell migration,and the regulation of fatty acid and estrogen metabolism in CRC cells.Thus,multiple lines of evidence suggest that GPER may play an important role in colorectal carcinogenesis.In this review,we present the current state of knowledge regarding the contribution of GPER to colon function and CRC.
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.
基金Supported by The American Heart Association,Texas Affiliate,No.7370061the Center for Chronic Disorders of Aging,PCOM
文摘Coronary heart disease(CHD) continues to be the greatest mortality risk factor in the developed world. Estrogens are recognized to have great therapeutic potential to treat CHD and other cardiovascular diseases; however,a significant array of potentially debilitating side effects continues to limit their use. Moreover,recent clinical trials have indicated that long-term postmenopausal estrogen therapy may actually be detrimental to cardiovascular health. An exciting new development is the finding that the more recently discovered G-protein-coupled estrogen receptor(GPER) is expressed in coronary arteries-both in coronary endothelium and in smooth muscle within the vascular wall. Accumulating evidence indicates that GPER activation dilates coronary arteries and can also inhibit the prolif-eration and migration of coronary smooth muscle cells. Thus,selective GPER activation has the potential to increase coronary blood flow and possibly limit the debilitating consequences of coronary atherosclerotic disease. This review will highlight what is currently known regarding the impact of GPER activation on coronary arteries and the potential signaling mechanisms stimulated by GPER agonists in these vessels. A thorough understanding of GPER function in coronary arteries may promote the development of new therapies that would help alleviate CHD,while limiting the potentially dangerous side effects of estrogen therapy.
文摘The renal handling of Na^+ balance is a major determinant of the blood pressure(BP) level. The inability of the kidney to excrete the daily load of Na+ represents the primary cause of chronic hypertension. Among the different segments that constitute the nephron, those present in the distal part(i.e., the cortical thick ascending limb, the distal convoluted tubule, the connecting and collecting tubules) play a central role in the fine-tuning of renal Na^+ excretion and are the target of many different regulatory processes that modulate Na^+ retention more or less efficiently. G-protein coupled receptors(GPCRs) are crucially involved in this regulation and could represent efficient pharmacological targets to control BP levels. In this review, we describe both classical and novel GPCR-dependent regulatory systems that have been shown to modulate renal Na^+ absorption in the distal nephron. In addition to the multiplicity of the GPCR that regulate Na^+ excretion, this review also highlights the complexity of these different pathways, and the connections between them.
基金Supported by National Key Clinical Disciplineand the Medical Scientific Research Foundation of Guangdong Province,No.A2016198the Science and Technology Planning Project of Guangdong Province,No.20160916,No.2015B020229001 and No.2014SC111
文摘AIM To investigate the expression of G protein-coupled receptor 31 (GPR31) and its clinical significance in human colorectal cancer (CRC).METHODS To determine the association between the GPR31 expression and the prognosis of patients, we obtained paraffin-embedded pathological specimens from 466 CRC patients who underwent initial resection. A total of 321 patients from the First Affiliated Hospital of Sun Yat-sen University from January 1996 to December 2008 were included as a training cohort, whereas 145 patients from the Sixth Affiliated Hospital of Sun Yat-sen University from January 2007 to November 2008 were included as a validation cohort. We examined GPR31 expression levels in CRC tissues from two independent cohorts via immunohistochemical staining. All patients were categorized into either a GPR31 low expression group or a GPR31 high expression group. The clinicopathological factors and the prognosis of patients in the GPR31 low expression group and GPR31 high expression group were compared.RESULTS We compared the clinicopathological factors and the prognosis of patients in the GPR31 low expression group and GPR31 high expression group. Significant differences were observed in the number of patients in pM classification between patients in the GPR31 low expression group and GPR31 high expression group (P = 0.007). The five-year survival and tumor-free survival rates of patients were 84.3% and 82.2% in the GPR31 low expression group, respectively, and both rates were 59.7% in the GPR31 high expression group (P < 0.05). Results of the Cox proportional hazard regression model revealed that GPR31 upregulation was associated with shorter overall survival and tumor-free survival of patients with CRC (P < 0.05). Multivariate analysis identified GPR31 expression in colorectal cancer as an independent predictive factor of CRC patient survival (P < 0.05).CONCLUSION High GPR31 expression levels were found to be correlated with pM classification of CRC and to serve as an independent predictive factor of poor survival of CRC patients.
基金supported by SIP-IPN,CONACYT (CB-168116)FIS/IMSS (FIS/IMSS/PROT/G11-2/1013)
文摘In the last few years, there have been important new insights into the structural biology of G-protein coupled receptors. It is now known that allosteric binding sites are involved in the affinity and selec- tivity of ligands for G-protein coupled receptors, and that signaling by these receptors involves both G-protein dependent and independent pathways. The present review outlines the physiological and pharmacological implications of this perspective for the design of new drugs to treat disorders of the central nervous system. Specifically, new possibilities are explored in relation to allosteric and or- thosteric binding sites on dopamine receptors for the treatment of Parkinson＇s disease, and on muscarinic receptors for Alzheimer＇s disease. Future research can seek to identify ligands that can bind to more than one site on the same receptor, or simultaneously bind to two receptors and form a dimer. For example, the design of bivalent drugs that can reach homo/hetero-dimers of D2 dopa- mine receptor holds promise as a relevant therapeutic strategy for Parkinson＇s disease. Regarding the treatment of Alzheimer＇s disease, the design of dualsteric ligands for mono-oligomeric mus- carinic receptors could increase therapeutic effectiveness by generating potent compounds that could activate more than one signaling pathway.
