Plant hormone abscisic acid （ABA） serves as an integrator of environmental stresses such as drought to trig-ger stomatal closure by regulating specific ion channels in guard cells. We previously reported that SLAC1,...Plant hormone abscisic acid （ABA） serves as an integrator of environmental stresses such as drought to trig-ger stomatal closure by regulating specific ion channels in guard cells. We previously reported that SLAC1, an outward anion channel required for stomatal closure, was regulated via reversible protein phosphorylation events involving ABA signaling components, including protein phosphatase 2C members and a SnRK2-type kinase （OST1）. In this study, we reconstituted the ABA signaling pathway as a protein-protein interaction relay from the PYL/RCAR-type receptors, to the PP2C-SnRK2 phosphatase-kinase pairs, to the ion channel SLAC1. The ABA receptors interacted with and inhibited PP2C phosphatase activity against the SnRK2-type kinase, releasing active SnRK2 kinase to phosphorylate, and activate the SLAC1 channel, leading to reduced guard cell turgor and stomatal closure. Both yeast two-hybrid and bimolecular fluorescence complementation assays were used to verify the interactions among the components in the pathway. These biochemical assays demonstrated activity modifications of phosphatases and kinases by their interaction partners. The SLAC1 channel activity was used as an endpoint readout for the strength of the signaling pathway, depending on the presence of different combinations of signaling components. Further study using transgenic plants overexpressing one of the ABA receptors demonstrated that changing the relative level of interacting partners would change ABA sensitivity.展开更多
目的观察磷脂酰肌醇-3激酶(PI3K)-蛋白质丝氨酸/苏氨酸激酶(AKt)-内皮型一氧化氮合酶(e NOS)信号转导通路在硫化氢(H2S)抑制内皮素-1(endothelin-1,ET-1)诱导心肌肥大过程中的作用。方法体外培养原代心肌细胞,将其随机分为6组,每组4孔,...目的观察磷脂酰肌醇-3激酶(PI3K)-蛋白质丝氨酸/苏氨酸激酶(AKt)-内皮型一氧化氮合酶(e NOS)信号转导通路在硫化氢(H2S)抑制内皮素-1(endothelin-1,ET-1)诱导心肌肥大过程中的作用。方法体外培养原代心肌细胞,将其随机分为6组,每组4孔,1对照组:加入等体积无血清的DMEM培养基;2肥大(ET-1)组:加入终浓度为10-8 mol/L的ET-1;剩余4组为实验组,各组分别加入不同终浓度的H2S供体-Na HS:310-15 M Na HS组:加入10-15 mol/L Na HS+10-8 mol/l ET-1;410-14 M Na HS组:加入10-14 mol/L Na HS+10-8 mol/L ET-1;510-13 M Na HS组:加入10-13 mol/L Na HS+10-8 mol/L ET-1;610-12 M Na HS组:加入10-12 mol/L Na HS+10-8 mol/L ET-1。上述各组药物分别刺激24 h后测定心肌细胞表面积、细胞总蛋白含量、培养液NO含量,RT-PCR检测心肌细胞心房利钠肽(atrial natriuretic peptide,ANP)、脑钠肽(B-type natriuretic peptide,BNP)、磷脂酰肌醇-3激酶(phosphatidylinositol-3-kinase,PI3K)、蛋白激酶B(protein kinase B,PKB/AKt)、e NOS m RNA水平,Western Blot技术检测总AKt和磷酸化AKt蛋白表达含量。结果肥大(ET-1)组的心肌细胞表面积(1933.80±143.06)和细胞总蛋白含量(367.51±25.9)均高于对照组(787.27±107.66,218.55±21.28,P<0.05),ANP及BNP m RNA的表达量也明显增加(P<0.05),但PI3K、AKt、e NOS m RNA表达水平,磷酸化AKt程度和NO的释放量(4.60±0.73)低于对照组(8.63±0.30,P<0.05),各实验组给予不同浓度Na HS刺激后能够浓度依赖性的抑制这种肥大效应(P<0.05),同时上调了PI3K/AKt/e NOS通路各信号分子的表达量(P<0.05)。结论 H2S对ET-1诱导的心肌肥大有一定的抑制作用,这种作用可能与激活PI3K-AKt-e NOS信号通路有关。展开更多
基金a grant from the Biogreen21 Program (PJ008222) Rural Development Administration and the Research Foundation of Korea (NFR) grant funded by the Korea government (No.2011-0007600)，the US National Science Foundation and Korean WCU Program of National Research Foundation (to S.L.).No conflict of interest declared
文摘Plant hormone abscisic acid （ABA） serves as an integrator of environmental stresses such as drought to trig-ger stomatal closure by regulating specific ion channels in guard cells. We previously reported that SLAC1, an outward anion channel required for stomatal closure, was regulated via reversible protein phosphorylation events involving ABA signaling components, including protein phosphatase 2C members and a SnRK2-type kinase （OST1）. In this study, we reconstituted the ABA signaling pathway as a protein-protein interaction relay from the PYL/RCAR-type receptors, to the PP2C-SnRK2 phosphatase-kinase pairs, to the ion channel SLAC1. The ABA receptors interacted with and inhibited PP2C phosphatase activity against the SnRK2-type kinase, releasing active SnRK2 kinase to phosphorylate, and activate the SLAC1 channel, leading to reduced guard cell turgor and stomatal closure. Both yeast two-hybrid and bimolecular fluorescence complementation assays were used to verify the interactions among the components in the pathway. These biochemical assays demonstrated activity modifications of phosphatases and kinases by their interaction partners. The SLAC1 channel activity was used as an endpoint readout for the strength of the signaling pathway, depending on the presence of different combinations of signaling components. Further study using transgenic plants overexpressing one of the ABA receptors demonstrated that changing the relative level of interacting partners would change ABA sensitivity.
文摘目的观察磷脂酰肌醇-3激酶(PI3K)-蛋白质丝氨酸/苏氨酸激酶(AKt)-内皮型一氧化氮合酶(e NOS)信号转导通路在硫化氢(H2S)抑制内皮素-1(endothelin-1,ET-1)诱导心肌肥大过程中的作用。方法体外培养原代心肌细胞,将其随机分为6组,每组4孔,1对照组:加入等体积无血清的DMEM培养基;2肥大(ET-1)组:加入终浓度为10-8 mol/L的ET-1;剩余4组为实验组,各组分别加入不同终浓度的H2S供体-Na HS:310-15 M Na HS组:加入10-15 mol/L Na HS+10-8 mol/l ET-1;410-14 M Na HS组:加入10-14 mol/L Na HS+10-8 mol/L ET-1;510-13 M Na HS组:加入10-13 mol/L Na HS+10-8 mol/L ET-1;610-12 M Na HS组:加入10-12 mol/L Na HS+10-8 mol/L ET-1。上述各组药物分别刺激24 h后测定心肌细胞表面积、细胞总蛋白含量、培养液NO含量,RT-PCR检测心肌细胞心房利钠肽(atrial natriuretic peptide,ANP)、脑钠肽(B-type natriuretic peptide,BNP)、磷脂酰肌醇-3激酶(phosphatidylinositol-3-kinase,PI3K)、蛋白激酶B(protein kinase B,PKB/AKt)、e NOS m RNA水平,Western Blot技术检测总AKt和磷酸化AKt蛋白表达含量。结果肥大(ET-1)组的心肌细胞表面积(1933.80±143.06)和细胞总蛋白含量(367.51±25.9)均高于对照组(787.27±107.66,218.55±21.28,P<0.05),ANP及BNP m RNA的表达量也明显增加(P<0.05),但PI3K、AKt、e NOS m RNA表达水平,磷酸化AKt程度和NO的释放量(4.60±0.73)低于对照组(8.63±0.30,P<0.05),各实验组给予不同浓度Na HS刺激后能够浓度依赖性的抑制这种肥大效应(P<0.05),同时上调了PI3K/AKt/e NOS通路各信号分子的表达量(P<0.05)。结论 H2S对ET-1诱导的心肌肥大有一定的抑制作用,这种作用可能与激活PI3K-AKt-e NOS信号通路有关。
