The mechanisms of regulation, activation and signal transduction of the angiotensin II (Ang II) type 1 (AT1) receptor have been studied extensively in the decade after its cloning. The AT1 receptor is a major componen...The mechanisms of regulation, activation and signal transduction of the angiotensin II (Ang II) type 1 (AT1) receptor have been studied extensively in the decade after its cloning. The AT1 receptor is a major component of the renin-angiotensin system (RAS). It mediates the classical biological actions of Ang II. Among the structures required for regulation and activation of the receptor, its carboxyl- terminal region plays crucial roles in receptor internalization, desensitization and phosphorylation. The mechanisms involved in heterotrimeric G-protein coupling to the receptor, activation of the downstream signaling pathway by G proteins and the Ang II signal transduction pathways leading to specific cellular responses are discussed. In addition, recent work on the identification and characterization of novel proteins associated with carboxy1-terminus of the AT1 receptor is presented. These novel proteins will advance our understanding of how the receptor is internalized and recycled as they provide molecular mechanisms for the activation and regulation of G-protein-coupled receptors.展开更多
Participation of angiotensin II in chronic kidney diseases including diabetic nephropathy (DN) has been extensively described. Similarly, several studies support a protective role for angiotensin-(1-7). However, other...Participation of angiotensin II in chronic kidney diseases including diabetic nephropathy (DN) has been extensively described. Similarly, several studies support a protective role for angiotensin-(1-7). However, other studies suggest that some of the cellular effects of angiotensin-(1-7) may be deleterious. The objective of this study was to determine the role of exogenous angiotensin-(1-7) on renal hypertrophy development in rats with streptozotocin-induced diabetes. A control group and three groups of rats with streptozotocin-induced diabetes: untreated diabetic rats, diabetic rats treated with captopril, and diabetic rats treated with angiotensin-(1-7), were studied. After two weeks of treatment, the kidneys were removed under anesthesia with pentobarbital. The kidneys were weighed and the renal cortex was separated for analysis of AT<sub>1</sub>R, TGF-β<sub>1</sub>, MASR, and ACE2 expression by western blot. Rats in the three groups with diabetes had hyperglycemia, increased food and water consumption, and higher urinary volume than control rats. Treatment with captopril or angiotensin-(1-7) reversed streptozotocin-induced renal hypertrophy, measured by kidney weight, protein/DNA ratio in renal cortex, glomerular area, or proximal tubular cells area, proteinuria, and creatinine clearance reduction. AT<sub>1</sub>R, TGF-β<sub>1</sub>, and MAS receptor expression in renal cortex of diabetic rats increased significantly as compared to controls (p展开更多
Background:Macrophages are involved in the pathogenesis of idiopathic pulmonary fibrosis,partially by activating lung fibroblasts.However,how macrophages communicate with lung fibroblasts is largely unexplored.Exosome...Background:Macrophages are involved in the pathogenesis of idiopathic pulmonary fibrosis,partially by activating lung fibroblasts.However,how macrophages communicate with lung fibroblasts is largely unexplored.Exosomes can mediate intercellular communication,whereas its role in lung fibrogenesis is unclear.Here we aim to investigate whether exosomes can mediate the crosstalk between macrophages and lung fibroblasts and subsequently induce fibrosis.Methods:In vivo,bleomycin(BLM)-induced lung fibrosis model was established and macrophages infiltration was examined.The effects of GW4869,an exosomes inhibitor,on lung fibrosis were assessed.Moreover,macrophage exosomes were injected into mice to observe its pro-fibrotic effects.In vitro,exosomes derived from angiotensin Ⅱ(Ang Ⅱ)-stimulated macrophages were collected.Then,lung fibroblasts were treated with the exosomes.Twenty-four hours later,protein levels ofα-collagen I,angiotensin Ⅱ type 1 receptor(AT1R),transforming growth factor-β(TGF-β),and phospho-Smad2/3(p-Smad2/3)in lung fibroblasts were examined.The Student's t test or analysis of variance were used for statistical analysis.Results:In vivo,BLM-treated mice showed enhanced infiltration of macrophages,increased fibrotic alterations,and higher levels of Ang Ⅱ and AT1R.GW4869 attenuated BLM-induced pulmonary fibrosis.Mice with exosomes injection showed fibrotic features with higher levels of Ang Ⅱ and AT1R,which was reversed by irbesartan.In vitro,we found that macrophages secreted a great number of exosomes.The exosomes were taken by fibroblasts and resulted in higher levels of AT1R(0.22±0.02 vs.0.07±0.02,t=8.66,P=0.001),TGF-β(0.54±0.05 vs.0.09±0.06,t=10.00,P<0.001),p-Smad2/3(0.58±0.06 vs.0.07±0.03,t=12.86,P<0.001)andα-collagen I(0.27±0.02 vs.0.16±0.01,t=7.01,P=0.002),and increased Ang Ⅱ secretion(62.27±7.32 vs.9.56±1.68,t=12.16,P<0.001).Interestingly,Ang Ⅱ increased the number of macrophage exosomes,and the protein levels of Alix(1.45±0.15 vs.1.00±0.10,t=4.32,P=0.012),AT1R(4.05±0.64 vs.1.00±0.09,t=8.17,P=0.001),and glyceraldehyde-3-phosphate dehydrogenase(2.13±0.36 vs.1.00±0.10,t=5.28,P=0.006)were increased in exosomes secreted by the same number of macrophages,indicating a positive loop between Ang Ⅱ and exosomes production.Conclusions:Exosomes mediate intercellular communication between macrophages and fibroblasts plays an important role in BLM-induced pulmonary fibrosis.展开更多
文摘The mechanisms of regulation, activation and signal transduction of the angiotensin II (Ang II) type 1 (AT1) receptor have been studied extensively in the decade after its cloning. The AT1 receptor is a major component of the renin-angiotensin system (RAS). It mediates the classical biological actions of Ang II. Among the structures required for regulation and activation of the receptor, its carboxyl- terminal region plays crucial roles in receptor internalization, desensitization and phosphorylation. The mechanisms involved in heterotrimeric G-protein coupling to the receptor, activation of the downstream signaling pathway by G proteins and the Ang II signal transduction pathways leading to specific cellular responses are discussed. In addition, recent work on the identification and characterization of novel proteins associated with carboxy1-terminus of the AT1 receptor is presented. These novel proteins will advance our understanding of how the receptor is internalized and recycled as they provide molecular mechanisms for the activation and regulation of G-protein-coupled receptors.
文摘Participation of angiotensin II in chronic kidney diseases including diabetic nephropathy (DN) has been extensively described. Similarly, several studies support a protective role for angiotensin-(1-7). However, other studies suggest that some of the cellular effects of angiotensin-(1-7) may be deleterious. The objective of this study was to determine the role of exogenous angiotensin-(1-7) on renal hypertrophy development in rats with streptozotocin-induced diabetes. A control group and three groups of rats with streptozotocin-induced diabetes: untreated diabetic rats, diabetic rats treated with captopril, and diabetic rats treated with angiotensin-(1-7), were studied. After two weeks of treatment, the kidneys were removed under anesthesia with pentobarbital. The kidneys were weighed and the renal cortex was separated for analysis of AT<sub>1</sub>R, TGF-β<sub>1</sub>, MASR, and ACE2 expression by western blot. Rats in the three groups with diabetes had hyperglycemia, increased food and water consumption, and higher urinary volume than control rats. Treatment with captopril or angiotensin-(1-7) reversed streptozotocin-induced renal hypertrophy, measured by kidney weight, protein/DNA ratio in renal cortex, glomerular area, or proximal tubular cells area, proteinuria, and creatinine clearance reduction. AT<sub>1</sub>R, TGF-β<sub>1</sub>, and MAS receptor expression in renal cortex of diabetic rats increased significantly as compared to controls (p
基金supported by the Science and Technology Project in Guangzhou(No.201904010482)the National Natural Science Foundation of China(Nos.81570064,81870068,and 82070063).
文摘Background:Macrophages are involved in the pathogenesis of idiopathic pulmonary fibrosis,partially by activating lung fibroblasts.However,how macrophages communicate with lung fibroblasts is largely unexplored.Exosomes can mediate intercellular communication,whereas its role in lung fibrogenesis is unclear.Here we aim to investigate whether exosomes can mediate the crosstalk between macrophages and lung fibroblasts and subsequently induce fibrosis.Methods:In vivo,bleomycin(BLM)-induced lung fibrosis model was established and macrophages infiltration was examined.The effects of GW4869,an exosomes inhibitor,on lung fibrosis were assessed.Moreover,macrophage exosomes were injected into mice to observe its pro-fibrotic effects.In vitro,exosomes derived from angiotensin Ⅱ(Ang Ⅱ)-stimulated macrophages were collected.Then,lung fibroblasts were treated with the exosomes.Twenty-four hours later,protein levels ofα-collagen I,angiotensin Ⅱ type 1 receptor(AT1R),transforming growth factor-β(TGF-β),and phospho-Smad2/3(p-Smad2/3)in lung fibroblasts were examined.The Student's t test or analysis of variance were used for statistical analysis.Results:In vivo,BLM-treated mice showed enhanced infiltration of macrophages,increased fibrotic alterations,and higher levels of Ang Ⅱ and AT1R.GW4869 attenuated BLM-induced pulmonary fibrosis.Mice with exosomes injection showed fibrotic features with higher levels of Ang Ⅱ and AT1R,which was reversed by irbesartan.In vitro,we found that macrophages secreted a great number of exosomes.The exosomes were taken by fibroblasts and resulted in higher levels of AT1R(0.22±0.02 vs.0.07±0.02,t=8.66,P=0.001),TGF-β(0.54±0.05 vs.0.09±0.06,t=10.00,P<0.001),p-Smad2/3(0.58±0.06 vs.0.07±0.03,t=12.86,P<0.001)andα-collagen I(0.27±0.02 vs.0.16±0.01,t=7.01,P=0.002),and increased Ang Ⅱ secretion(62.27±7.32 vs.9.56±1.68,t=12.16,P<0.001).Interestingly,Ang Ⅱ increased the number of macrophage exosomes,and the protein levels of Alix(1.45±0.15 vs.1.00±0.10,t=4.32,P=0.012),AT1R(4.05±0.64 vs.1.00±0.09,t=8.17,P=0.001),and glyceraldehyde-3-phosphate dehydrogenase(2.13±0.36 vs.1.00±0.10,t=5.28,P=0.006)were increased in exosomes secreted by the same number of macrophages,indicating a positive loop between Ang Ⅱ and exosomes production.Conclusions:Exosomes mediate intercellular communication between macrophages and fibroblasts plays an important role in BLM-induced pulmonary fibrosis.
