Several factors have been implicated in obesity-related hypertension, but the genesis of the hypertension is largely unknown. In this study, we found a significantly upregulated expression of CPI-17(C-kinasepotentiate...Several factors have been implicated in obesity-related hypertension, but the genesis of the hypertension is largely unknown. In this study, we found a significantly upregulated expression of CPI-17(C-kinasepotentiated protein phosphatase 1 inhibitor of 17 kDa) and protein kinase C(PKC) isoforms in the vascular smooth muscles of high-fat diet(HFD)-fed obese mice. The obese wild-type mice showed a significant elevation of blood pressure and enhanced calcium-sensitized contraction of vascular smooth muscles. However, the obese CPI-17-deficient mice showed a normotensive blood pressure, and the calcium-sensitized contraction was consistently reduced. In addition, the mutant muscle displayed an abolished responsive force to a PKC activator and a 30%-50% reduction in both the initial peak force and sustained force in response to various G protein-coupled receptor(GPCR) agonists. Our observations showed that CPI-17-mediated calcium sensitization is mediated through a GPCR/PKC/CPI-17/MLCP/RLC signaling pathway. We therefore propose that the upregulation of CPI-17-mediated calcium-sensitized vasocontraction by obesity contributes to the development of obesity-related hypertension.展开更多
As a critical guanine nucleotide exchange factor(GEF) regulating neurite outgrowth, Trio coordinates multiple processes of cytoskeletal dynamics through activating Rac1, Cdc42 and RhoA small GTPases by two GEF domains...As a critical guanine nucleotide exchange factor(GEF) regulating neurite outgrowth, Trio coordinates multiple processes of cytoskeletal dynamics through activating Rac1, Cdc42 and RhoA small GTPases by two GEF domains, but the in vivo roles of these GEF domains and corresponding downstream effectors have not been determined yet. We established multiple lines of knockout mice and assessed the respective roles of Trio GEF domains and Rac1 in axon outgrowth. Knockout of total Trio in cerebellar granule neurons(CGNs) led to an impaired F-actin rearrangement of growth cone and hence a retarded neurite outgrowth. Such a retardation was reproduced by inhibition of GEF1 domain or knockdown of Cdc42 and restored apparently by introduction of active Cdc42. As Rac1 deficiency did not affect the neurite outgrowth of CGNs, we suggested that Trio GEF1-mediated Cdc42 activation was required for neurite outgrowth. We established a GEF2-knockout line with deletion of all Trio isoforms except a cerebella-specific Trio8, a short isoform of Trio without GEF2 domain, and used this line as a GEF2-deficient animal model. The GEF2-deficient CGNs had a normal neurite outgrowth but abolished Netrin-1-promoted growth, without affecting Netrin-1 induced Rac1 activation. We thus suggested that Trio GEF1-mediated Cdc42 activation rather than Rac1 activation drives the F-actin dynamics necessary for neurite outgrowth, while GEF2 functions in Netrin-1-promoted neurite elongation. Our results delineated the distinct roles of Trio GEF domains in neurite outgrowth, which is instructive to understand the pathogenesis of clinical Trio-related neurodevelopmental disorders.展开更多
Airway smooth muscle(ASM)has developed a mechanical adaption mechanism by which it transduces force and responds to environmental forces,which is essential for periodic breathing.Cytoskeletal reorganization has been i...Airway smooth muscle(ASM)has developed a mechanical adaption mechanism by which it transduces force and responds to environmental forces,which is essential for periodic breathing.Cytoskeletal reorganization has been implicated in this process,but the regulatory mechanism remains to be determined.We here observe that ASM abundantly expresses cytoskeleton regulators Limk1 and Limk2,and their expression levels are further upregulated in chronic obstructive pulmonary disease(COPD)animals.By establishing mouse lines with deletions of Limk1 or Limk2,we analyse the length-sensitive contraction,F/Gactin dynamics,and F-actin pool of mutant ASM cells.As LIMK1 phosphorylation does not respond to the contractile stimulation,LIMK1-deficient ASM develops normal maximal force,while LIMK2 or LIMK1/LIMK2 deficient ASMs show approximately 30%inhibition.LIMK2 deletion causes a significant decrease in cofilin phosphorylation along with a reduced F/G-actin ratio.As LIMK2 functions independently of cross-bridge movement,this observation indicates that LIMK2 is necessary for F-actin dynamics and hence force transduction.Moreover,LIMK2-deficient ASMs display abolishes stretching-induced suppression of 5-hydroxytryptamine(5-HT)but not acetylcholine-evoks force,which is due to the differential contraction mechanisms adopted by the agonists.We propose that LIMK2-mediated cofilin phosphorylation is required for membrane cytoskeleton reorganization that is necessary for ASM mechanical adaption including the 5-HT-evoked length-sensitive effect.展开更多
Dystocia is a serious problem for pregnant women, and it increases the cesarean section rate. Although uterine dysfunction has an unknown etiology, it is responsible for cesarean delivery and clinical dystocia, result...Dystocia is a serious problem for pregnant women, and it increases the cesarean section rate. Although uterine dysfunction has an unknown etiology, it is responsible for cesarean delivery and clinical dystocia, resulting in neonatal morbidity and mortality;thus, there is an urgent need for novel therapeutic agents. Previous studies indicated that statins, which inhibit the mevalonate (MVA) pathway of cholesterol synthesis, can reduce the incidence of preterm birth, but the safety of statins for pregnant women has not been thoroughly evaluated. Therefore, to unambiguously examine the function of the MVA pathway in pregnancy and delivery, we employed a genetic approach by using myometrial cell-specific deletion of geranylgeranyl pyrophosphate synthase (Ggps1) mice. We found that Ggps1 deficiency in myometrial cells caused impaired uterine contractions, resulting in disrupted embryonic placing and dystocia. Studies of the underlying mechanism suggested that Ggps1 is required for uterine contractions to ensure successful parturition by regulating RhoA prenylation to activate the RhoA/Rock2/p-MLC pathway. Our work indicates that perturbing the MVA pathway might result in problems during delivery for pregnant females, but modifying protein prenylation with supplementary farnesyl pyrophosphate or geranylgeranyl pyrophosphate might be a strategy to avoid side effects.展开更多
Speaking of asthma,one is immediately reminded of incessant coughing and wheezing,and the unsightly scene of phlegm-spitting.A wide range of remedies have been tried,ranging from ancient folklore belief of smelling ho...Speaking of asthma,one is immediately reminded of incessant coughing and wheezing,and the unsightly scene of phlegm-spitting.A wide range of remedies have been tried,ranging from ancient folklore belief of smelling honey to modern inhaling β2-adrenoceptor agonists,but none proves to have long-lasting effect for this common chronic pulmonary disease.As a Chinese proverb says,a good medicine always tastes bitter.展开更多
基金supported by the National Natural Science Funding of China (31272311 and 31330034 to M.S.Z.)
文摘Several factors have been implicated in obesity-related hypertension, but the genesis of the hypertension is largely unknown. In this study, we found a significantly upregulated expression of CPI-17(C-kinasepotentiated protein phosphatase 1 inhibitor of 17 kDa) and protein kinase C(PKC) isoforms in the vascular smooth muscles of high-fat diet(HFD)-fed obese mice. The obese wild-type mice showed a significant elevation of blood pressure and enhanced calcium-sensitized contraction of vascular smooth muscles. However, the obese CPI-17-deficient mice showed a normotensive blood pressure, and the calcium-sensitized contraction was consistently reduced. In addition, the mutant muscle displayed an abolished responsive force to a PKC activator and a 30%-50% reduction in both the initial peak force and sustained force in response to various G protein-coupled receptor(GPCR) agonists. Our observations showed that CPI-17-mediated calcium sensitization is mediated through a GPCR/PKC/CPI-17/MLCP/RLC signaling pathway. We therefore propose that the upregulation of CPI-17-mediated calcium-sensitized vasocontraction by obesity contributes to the development of obesity-related hypertension.
基金supported by grants from the National Natural Science Foundation of China (31272311 and 31330034) to M.S.Z.
文摘As a critical guanine nucleotide exchange factor(GEF) regulating neurite outgrowth, Trio coordinates multiple processes of cytoskeletal dynamics through activating Rac1, Cdc42 and RhoA small GTPases by two GEF domains, but the in vivo roles of these GEF domains and corresponding downstream effectors have not been determined yet. We established multiple lines of knockout mice and assessed the respective roles of Trio GEF domains and Rac1 in axon outgrowth. Knockout of total Trio in cerebellar granule neurons(CGNs) led to an impaired F-actin rearrangement of growth cone and hence a retarded neurite outgrowth. Such a retardation was reproduced by inhibition of GEF1 domain or knockdown of Cdc42 and restored apparently by introduction of active Cdc42. As Rac1 deficiency did not affect the neurite outgrowth of CGNs, we suggested that Trio GEF1-mediated Cdc42 activation was required for neurite outgrowth. We established a GEF2-knockout line with deletion of all Trio isoforms except a cerebella-specific Trio8, a short isoform of Trio without GEF2 domain, and used this line as a GEF2-deficient animal model. The GEF2-deficient CGNs had a normal neurite outgrowth but abolished Netrin-1-promoted growth, without affecting Netrin-1 induced Rac1 activation. We thus suggested that Trio GEF1-mediated Cdc42 activation rather than Rac1 activation drives the F-actin dynamics necessary for neurite outgrowth, while GEF2 functions in Netrin-1-promoted neurite elongation. Our results delineated the distinct roles of Trio GEF domains in neurite outgrowth, which is instructive to understand the pathogenesis of clinical Trio-related neurodevelopmental disorders.
基金supported by the National Natural Science Funding of China(31272711,31330034,9184910039and 3207090129 to M.S.Z)。
文摘Airway smooth muscle(ASM)has developed a mechanical adaption mechanism by which it transduces force and responds to environmental forces,which is essential for periodic breathing.Cytoskeletal reorganization has been implicated in this process,but the regulatory mechanism remains to be determined.We here observe that ASM abundantly expresses cytoskeleton regulators Limk1 and Limk2,and their expression levels are further upregulated in chronic obstructive pulmonary disease(COPD)animals.By establishing mouse lines with deletions of Limk1 or Limk2,we analyse the length-sensitive contraction,F/Gactin dynamics,and F-actin pool of mutant ASM cells.As LIMK1 phosphorylation does not respond to the contractile stimulation,LIMK1-deficient ASM develops normal maximal force,while LIMK2 or LIMK1/LIMK2 deficient ASMs show approximately 30%inhibition.LIMK2 deletion causes a significant decrease in cofilin phosphorylation along with a reduced F/G-actin ratio.As LIMK2 functions independently of cross-bridge movement,this observation indicates that LIMK2 is necessary for F-actin dynamics and hence force transduction.Moreover,LIMK2-deficient ASMs display abolishes stretching-induced suppression of 5-hydroxytryptamine(5-HT)but not acetylcholine-evoks force,which is due to the differential contraction mechanisms adopted by the agonists.We propose that LIMK2-mediated cofilin phosphorylation is required for membrane cytoskeleton reorganization that is necessary for ASM mechanical adaption including the 5-HT-evoked length-sensitive effect.
基金This work was supported by the National Natural Science Foundation of China(31530046)the National Science and Technology Major Project(SQ2018YFC100242).
文摘Dystocia is a serious problem for pregnant women, and it increases the cesarean section rate. Although uterine dysfunction has an unknown etiology, it is responsible for cesarean delivery and clinical dystocia, resulting in neonatal morbidity and mortality;thus, there is an urgent need for novel therapeutic agents. Previous studies indicated that statins, which inhibit the mevalonate (MVA) pathway of cholesterol synthesis, can reduce the incidence of preterm birth, but the safety of statins for pregnant women has not been thoroughly evaluated. Therefore, to unambiguously examine the function of the MVA pathway in pregnancy and delivery, we employed a genetic approach by using myometrial cell-specific deletion of geranylgeranyl pyrophosphate synthase (Ggps1) mice. We found that Ggps1 deficiency in myometrial cells caused impaired uterine contractions, resulting in disrupted embryonic placing and dystocia. Studies of the underlying mechanism suggested that Ggps1 is required for uterine contractions to ensure successful parturition by regulating RhoA prenylation to activate the RhoA/Rock2/p-MLC pathway. Our work indicates that perturbing the MVA pathway might result in problems during delivery for pregnant females, but modifying protein prenylation with supplementary farnesyl pyrophosphate or geranylgeranyl pyrophosphate might be a strategy to avoid side effects.
文摘Speaking of asthma,one is immediately reminded of incessant coughing and wheezing,and the unsightly scene of phlegm-spitting.A wide range of remedies have been tried,ranging from ancient folklore belief of smelling honey to modern inhaling β2-adrenoceptor agonists,but none proves to have long-lasting effect for this common chronic pulmonary disease.As a Chinese proverb says,a good medicine always tastes bitter.
