异源三聚体G蛋白由Gα、Gβ和Gγ 3个亚基组成,是普遍存在于真核细胞中的跨膜信号转导因子。植物细胞通过定位于细胞质膜的G蛋白信号调节子RGS蛋白(regulator of G protein signaling),调控异源三聚体G蛋白的活性,进而参与生长发育、激...异源三聚体G蛋白由Gα、Gβ和Gγ 3个亚基组成,是普遍存在于真核细胞中的跨膜信号转导因子。植物细胞通过定位于细胞质膜的G蛋白信号调节子RGS蛋白(regulator of G protein signaling),调控异源三聚体G蛋白的活性,进而参与生长发育、激素和糖信号转导以及抗病反应等多个重要生物学过程。膜蛋白可通过胞吞循环调控其在细胞质膜上的数量,以响应外界环境因子和自身发育信号。近年来,研究表明多种外界信号诱导拟南芥AtRGS1蛋白的胞吞,进而促进其与Gα亚基的解离,游离的Gα-GTP、Gβγ亚基和定位于内含体的AtRGS1蛋白均可能调控下游信号转导,进而影响相应生物学过程。本文综述了AtRGS1通过胞吞作用调控G蛋白参与的生长发育和抗性反应的分子细胞学机制研究进展,以期为深入理解G蛋白信号调节子影响植物发育进程和抗性反应的作用机制提供理论参考,为植物膜蛋白胞吞调控信号转导提供新的视角。展开更多
Pertussis toxin （FIX） inhibits the activation of the α-subunit of the inhibitory heterotrimeric G-proteins （Cαi/o） and modulates voltage-gated sodium channels, which may be one of the primary targets of pyrethro...Pertussis toxin （FIX） inhibits the activation of the α-subunit of the inhibitory heterotrimeric G-proteins （Cαi/o） and modulates voltage-gated sodium channels, which may be one of the primary targets of pyrethroids. To investigate the potential mechanisms of agricultural pests resistance to pyrethroid insecticides, we examined the modulations by PTX on sodium channels in the central neurons of the 3rd-4th instar larvae of cyhalothrin-resistant （Cy-R） and cyhaiothrin-susceptible （Cy-S） Helicoverpa armigera by the whole-cell patch-clamp technique. The isolated neurons were cultured for 12-16 h in an improved L15 insect culture medium with or without PTX （400 ng/mL）. The results showed that both the Cy-R and Cy-S sodium channels exhibited fast kinetics and tetrodotoxin （TTX） sensitivity. The Cy-R sodium channels exhibited not only altered gating properties, including a 8.88-mV right shift in voltage-dependent activation （V0.5act） and a 6.54-mV right shift in voltage-dependent inactivation （V0.5inact）, but also a reduced peak in sodium channel density （Ⅰdensity） （55.2% of that in Cy-S neurons）. Cy-R sodium channels also showed low excitability, as evidenced by right shift of activation potential （Ⅴacti） by 5-10 mV and peak potential （Ⅴpcak） by 20 mV. FIX exerted significant effects on Cy-S sodium channels, reducing sodium channel density by 70.04%, right shifting V0.5act by 14.41 mV and V0.5inact by 9. 38 mV. It did not cause any significant changes of the parameters mentioned above in the Cy-R sodium channels. The activation time （Tpeak） from latency to peak at peak voltage and the fast inactivation time constant （τinact） in both Cy-S and Cy-R neurons were not affected. The results suggest that cotton bollworm resistant to pyrethroid insecticides involves not only mutations and allosteric alterations of voltage-gated sodium channels, but also might implicate perturbation of PTX-sensitive Gαi/o-COupled signaling Wansduction pathways.展开更多
Ethanol (EtOH) enhances glycinergic currents in the central nervous system (CNS). Because evidence for an interaction between the α1 subunit of the glycine receptor (α1GlyR) and the G protein Gβγ subunit exists in...Ethanol (EtOH) enhances glycinergic currents in the central nervous system (CNS). Because evidence for an interaction between the α1 subunit of the glycine receptor (α1GlyR) and the G protein Gβγ subunit exists in vitro and because cAMP levels are known to increase in response to EtOH, we wanted to investigate the interaction between Gβγ and α1GlyR in response to EtOH treatment in HEK293 cells and to explore the possible sites of interaction between EtOH and the Gαs subunit. His pull-down assays in GlyR-His6-transfected HEK293 cells incubated with ethanol or propofol revealed that only EtOH treatment increased the binding of Gβγ heterodimers to α1GlyR. Using molecular modelling (protein structure prediction), was modelled the hGαs protein for the first time and validated this model by site-directed mutagenesis. By molecular docking, we identified some potential regions of interaction between hGαs and EtOH that are located on the SIII and SI regions of the Gαs. Therefore, we conclude that ethanol increases the interaction between α1GlyR and Gβγ in HEK293 cells, an effect that might be attributed to the interaction between EtOH and hGαs, which consequently stimulates hGαs.展开更多
Changes in the functional activity and levels of Gsa and Gia in heart failure have been studied predominantly in the end-stage failing heart.The objective of this study was to determine if levels and function of Gsa a...Changes in the functional activity and levels of Gsa and Gia in heart failure have been studied predominantly in the end-stage failing heart.The objective of this study was to determine if levels and function of Gsa and Gia2 in rat hearts change over time following acute myocar(lial infarction (MI) and if so,whether the changes in G proteins are associated with changes in heart function.As compared with sham-operated controls, Giα2, level of MI rats did not change at day l,increased by 64% at day 3 (P<0.01) and 55% at day 9 (P< 0.05)accompanied by reduced adenylyl cyclase activity,and returned to control by day 21. By contrast,Gsa level did not change at any time. Cardiac function in MI animals was markedly impaired at days 1,3 and 9 as evidenced by substantial elevation in LVEDP and reduction in +and -dp/dtmax,and partially restored at day 21. The increased Gia2level in MI rats at days 3 and 9 correlated positively to LVEDP(P< 0.05), and negatively to +and -dp/dtmax (p < 0. 01).The results show a three phase dynamic pattern in Gia2 level following acute MI:a lag phase, an increased expression phase associated with marked impairment of heart function,and a late phase in which the expression retums to control level accompanied by partially restored cardlac function.The results suggest that ② in G protein-mediated pathways,cardiac myocytes respond to MI Via regulating the gene expression of the inhibitory pathway, and ② up-regulation of Gia2 levels is related to the severity of impairment in cardiac function.展开更多
Magnesium(Mg) is crucial for the function of G proteins which play important roles in mediating the inotropic effects of β adrenergic agonists in the heart and are alteredin heart failure.This study was performed to ...Magnesium(Mg) is crucial for the function of G proteins which play important roles in mediating the inotropic effects of β adrenergic agonists in the heart and are alteredin heart failure.This study was performed to determine whether or not dietary Mg deficiency alters functional activity and levels of the two major ventricular G proteins, Gia and Gsa in the heart after myocardial infarction(MI).Six week old rats were fed a Mg adequate or deficient diet for 6 weeks.At the end of week 3,MI was induced by coronary artery ligation.A sham operation was performed as control.After surgery,surviving animals were maintained on their assigned diets for another 3 weeks.Then,cardiac function was measured.Severe hypomagnesemia and increased plasma catecholamine level were observed in all animals fed the Mg deficient diet.A significant reduction of ruyocardial Mg concentration accompanied by elevated plasma and myocardial calcium concentrations was observed in MI animals with existing Mg deficiency vs.animals fed the Mg adequate diet.Cardiac function was impaired in MI rats and further reduced in MI rats with existing Mg deficiency. Gia level was not altered by either Mg deficiency or MI alone,but was dramatically elevated in animals with combined Mg deficiency and MI (9. 9±0.7 arbitrary unit.mg-1 protein) as compared to MI alone (5.8±0. 6,P<0.05 )and Mg deficiency alone(6.1± 0.8,P<0.05 ). Gsa level did not differ between groups.Bacal,GppNHp-and forskolin-but not fluoride-, stimulated adenylyl cyclase activity was signifcantly reduced in MI animals with existing Mg deficiency indicating increased functional activity of Gia.The findings suggest that dietary Mg deficiency increases the expression and functional ac tivity of Gia in the heart after MI, while levels and function of Gsa are not compromised during dietary Mg deficiency either with or without MI.展开更多
文摘异源三聚体G蛋白由Gα、Gβ和Gγ 3个亚基组成,是普遍存在于真核细胞中的跨膜信号转导因子。植物细胞通过定位于细胞质膜的G蛋白信号调节子RGS蛋白(regulator of G protein signaling),调控异源三聚体G蛋白的活性,进而参与生长发育、激素和糖信号转导以及抗病反应等多个重要生物学过程。膜蛋白可通过胞吞循环调控其在细胞质膜上的数量,以响应外界环境因子和自身发育信号。近年来,研究表明多种外界信号诱导拟南芥AtRGS1蛋白的胞吞,进而促进其与Gα亚基的解离,游离的Gα-GTP、Gβγ亚基和定位于内含体的AtRGS1蛋白均可能调控下游信号转导,进而影响相应生物学过程。本文综述了AtRGS1通过胞吞作用调控G蛋白参与的生长发育和抗性反应的分子细胞学机制研究进展,以期为深入理解G蛋白信号调节子影响植物发育进程和抗性反应的作用机制提供理论参考,为植物膜蛋白胞吞调控信号转导提供新的视角。
基金Acknowledgments This work was supported by a grant from The National Natural Science Foundation of China （30270884）. We greatly thank Dr Lai-Hua Xie （University of California at Los Angeles） for critical reading of the early draft of the manuscript. We are grateful to Dr Chang-Hui Rui （Institute of Plant Protection, CAAS） for technical assistance and suggestions.
文摘Pertussis toxin （FIX） inhibits the activation of the α-subunit of the inhibitory heterotrimeric G-proteins （Cαi/o） and modulates voltage-gated sodium channels, which may be one of the primary targets of pyrethroids. To investigate the potential mechanisms of agricultural pests resistance to pyrethroid insecticides, we examined the modulations by PTX on sodium channels in the central neurons of the 3rd-4th instar larvae of cyhalothrin-resistant （Cy-R） and cyhaiothrin-susceptible （Cy-S） Helicoverpa armigera by the whole-cell patch-clamp technique. The isolated neurons were cultured for 12-16 h in an improved L15 insect culture medium with or without PTX （400 ng/mL）. The results showed that both the Cy-R and Cy-S sodium channels exhibited fast kinetics and tetrodotoxin （TTX） sensitivity. The Cy-R sodium channels exhibited not only altered gating properties, including a 8.88-mV right shift in voltage-dependent activation （V0.5act） and a 6.54-mV right shift in voltage-dependent inactivation （V0.5inact）, but also a reduced peak in sodium channel density （Ⅰdensity） （55.2% of that in Cy-S neurons）. Cy-R sodium channels also showed low excitability, as evidenced by right shift of activation potential （Ⅴacti） by 5-10 mV and peak potential （Ⅴpcak） by 20 mV. FIX exerted significant effects on Cy-S sodium channels, reducing sodium channel density by 70.04%, right shifting V0.5act by 14.41 mV and V0.5inact by 9. 38 mV. It did not cause any significant changes of the parameters mentioned above in the Cy-R sodium channels. The activation time （Tpeak） from latency to peak at peak voltage and the fast inactivation time constant （τinact） in both Cy-S and Cy-R neurons were not affected. The results suggest that cotton bollworm resistant to pyrethroid insecticides involves not only mutations and allosteric alterations of voltage-gated sodium channels, but also might implicate perturbation of PTX-sensitive Gαi/o-COupled signaling Wansduction pathways.
文摘Ethanol (EtOH) enhances glycinergic currents in the central nervous system (CNS). Because evidence for an interaction between the α1 subunit of the glycine receptor (α1GlyR) and the G protein Gβγ subunit exists in vitro and because cAMP levels are known to increase in response to EtOH, we wanted to investigate the interaction between Gβγ and α1GlyR in response to EtOH treatment in HEK293 cells and to explore the possible sites of interaction between EtOH and the Gαs subunit. His pull-down assays in GlyR-His6-transfected HEK293 cells incubated with ethanol or propofol revealed that only EtOH treatment increased the binding of Gβγ heterodimers to α1GlyR. Using molecular modelling (protein structure prediction), was modelled the hGαs protein for the first time and validated this model by site-directed mutagenesis. By molecular docking, we identified some potential regions of interaction between hGαs and EtOH that are located on the SIII and SI regions of the Gαs. Therefore, we conclude that ethanol increases the interaction between α1GlyR and Gβγ in HEK293 cells, an effect that might be attributed to the interaction between EtOH and hGαs, which consequently stimulates hGαs.
文摘Changes in the functional activity and levels of Gsa and Gia in heart failure have been studied predominantly in the end-stage failing heart.The objective of this study was to determine if levels and function of Gsa and Gia2 in rat hearts change over time following acute myocar(lial infarction (MI) and if so,whether the changes in G proteins are associated with changes in heart function.As compared with sham-operated controls, Giα2, level of MI rats did not change at day l,increased by 64% at day 3 (P<0.01) and 55% at day 9 (P< 0.05)accompanied by reduced adenylyl cyclase activity,and returned to control by day 21. By contrast,Gsa level did not change at any time. Cardiac function in MI animals was markedly impaired at days 1,3 and 9 as evidenced by substantial elevation in LVEDP and reduction in +and -dp/dtmax,and partially restored at day 21. The increased Gia2level in MI rats at days 3 and 9 correlated positively to LVEDP(P< 0.05), and negatively to +and -dp/dtmax (p < 0. 01).The results show a three phase dynamic pattern in Gia2 level following acute MI:a lag phase, an increased expression phase associated with marked impairment of heart function,and a late phase in which the expression retums to control level accompanied by partially restored cardlac function.The results suggest that ② in G protein-mediated pathways,cardiac myocytes respond to MI Via regulating the gene expression of the inhibitory pathway, and ② up-regulation of Gia2 levels is related to the severity of impairment in cardiac function.
文摘Magnesium(Mg) is crucial for the function of G proteins which play important roles in mediating the inotropic effects of β adrenergic agonists in the heart and are alteredin heart failure.This study was performed to determine whether or not dietary Mg deficiency alters functional activity and levels of the two major ventricular G proteins, Gia and Gsa in the heart after myocardial infarction(MI).Six week old rats were fed a Mg adequate or deficient diet for 6 weeks.At the end of week 3,MI was induced by coronary artery ligation.A sham operation was performed as control.After surgery,surviving animals were maintained on their assigned diets for another 3 weeks.Then,cardiac function was measured.Severe hypomagnesemia and increased plasma catecholamine level were observed in all animals fed the Mg deficient diet.A significant reduction of ruyocardial Mg concentration accompanied by elevated plasma and myocardial calcium concentrations was observed in MI animals with existing Mg deficiency vs.animals fed the Mg adequate diet.Cardiac function was impaired in MI rats and further reduced in MI rats with existing Mg deficiency. Gia level was not altered by either Mg deficiency or MI alone,but was dramatically elevated in animals with combined Mg deficiency and MI (9. 9±0.7 arbitrary unit.mg-1 protein) as compared to MI alone (5.8±0. 6,P<0.05 )and Mg deficiency alone(6.1± 0.8,P<0.05 ). Gsa level did not differ between groups.Bacal,GppNHp-and forskolin-but not fluoride-, stimulated adenylyl cyclase activity was signifcantly reduced in MI animals with existing Mg deficiency indicating increased functional activity of Gia.The findings suggest that dietary Mg deficiency increases the expression and functional ac tivity of Gia in the heart after MI, while levels and function of Gsa are not compromised during dietary Mg deficiency either with or without MI.
