植物中解密Ca^(2+)信号转导特异性的机制

Ca^(2+)信号介导植物对外界信号的刺激反应,并调节多种生理过程。CBL是一种在植物中发现的Ca2+结合蛋白,其靶蛋白为CIPK,现对CBL-CIPK信号转导系统及其如何解密Ca2+信号转导特异性进行综述。

ABP1参与BY2细胞生长素响应的Ca^(2+)信号转导过程

将Ca^(2+)响应实时荧光报告系统引入雌二醇诱导生长素结合蛋白(ABP1)调控表达的BY2细胞中,获得了ABP1过表达(ABP1-ox)、抑制表达(ABP1-anti)同时对Ca^(2+)标记的几个BY2细胞株。对这些细胞株进行雌二醇诱导调控其ABP1过表达或抑制表达后,分析ABP1的表达量,并通过在细胞外添加IAA处理,实时观察ABP1调控表达后细胞的Ca^(2+)信号变化。结果表明:ABP1-ox细胞在雌二醇诱导后细胞内ABP1表达量显著提高,细胞经IAA处理后,细胞膜内、核膜周围均有迅速而强烈的荧光信号,说明ABP1过表达后细胞能快速响应胞外的IAA作用,将信号转导到细胞内,使细胞质内Ca^(2+)信号迅速增强;而ABP1-anti细胞经雌二醇诱导后,细胞内ABP1表达显著下调,细胞经IAA处理后,相对于对照,细胞内的荧光信号微弱且呈点状,细胞核附近的荧光不明显,说明细胞内Ca^(2+)信号的转导受到抑制。这证明BY2细胞中ABP1参与生长素信号与细胞内Ca^(2+)响应的信号转导过程。

Relationship Between Ca^(2+) and Plant Ethylene Response

The relationship between Ca 2+ and ethylene response was investigated through analyzing the effect of Ca 2+ on the response to ethylene in etiolated tomato (Lycopersicon esculentum Mill cv. Lichun) seedling grown in darkness. When the etiolated tomato seedlings were treated with different concentrations of Ca 2+, the 'triple response' phenotype, ethylene production, the expression of ethylene receptor gene NEVER-RIPE (NR) and the content of cytosolic CaM were determined. With the concentration of Ca 2+ in the culture medium increasing from 0 mmol/L to 3.8 mmol/L, the 'triple response' phenotype of etiolated tomato seedling was correspondingly strengthened; meanwhile the ethylene production, the amount of NR gene expression and the concentration of CaM increased respectively. However, when the concentration of Ca 2+ was increased from 3.8 mmol/L to 10 mmol/L, the phenotype of 'triple response', ethylene production, NR gene expression, and the CaM content didn't increase further, but decreased consequently. The results indicated that the effect of Ca 2+ on the ethylene triple response in etiolated tomato seedling was relevant to ethylene biosynthesis and ethylene receptor gene expression which were influenced by applied Ca 2+, and these effects might be mediated through the change of CaM concentration in plant cell.

CBL/CIPK信号系统在植物细胞中的研究进展

从CBL蛋白家族,CBL蛋白下游靶蛋白CIPK以及CBL/CIPK在逆境胁迫中的表达模式等多个方面,介绍了CBL/CIPK信号系统在植物细胞中的一些研究进展。

钙信号在调节干细胞迁移中的作用及机制研究现状

钙离子(calcium ion,Ca^2+)作为第二信使,在调节包括干细胞迁移在内的许多生理过程中发挥重要作用。各种细胞外因子触发细胞内Ca2+水平升高,激活下游Ca2+依赖性信号分子调节细胞迁移。近年来荧光细胞钙成像技术使我们得以了解干细胞如何在细胞前缘发出Ca^2+脉冲,从细胞背面到正面保持胞内Ca^2+的浓度梯度,及如何恢复Ca2+耗竭等细胞爬行机制。另外,关于细胞外因子触发研究中,有关胞外腺嘌呤核苷三磷酸(adenosine triphosphate,ATP)的研究认为,ATP可以激活细胞膜上的G蛋白偶联受体P2受体,可因与Gα亚基和下游信号通路耦合,从而激活Ga,q-PLC-IP3R信号通路,(PIP2)转换成(IP3)和(DAG),IP3受体活化进而从内质网中释放Ca2+,激活PKC-ERK1/2信号通路等。对局部钙信号、Ca^2+转运蛋白的相互作用等干细胞迁移调控机制的认识,可能为治疗有关疾病提供新的方向。

Ca^(2+)对水杨酸诱发的丹参幼苗丹酚酸B生物合成的影响

为研究Ca2+在水杨酸诱导丹参幼苗丹酚酸B生物合成过程中的作用,分别用激光共聚焦显微镜和高效液相色谱仪检测胞外Ca2+通道抑制剂Vp和LaCl3,胞内Ca2+通道抑制剂LiCl以及胞内钙调素拮抗剂TFP处理前、后水杨酸诱导丹参叶片保卫细胞内Ca2+荧光强度和丹酚酸B含量的变化。结果表明,水杨酸(SA)处理后6 min即可诱发丹参幼苗叶片保卫细胞内Ca2+迸发,持续时间为2~3 min,丹参幼苗丹酚酸B生物合成量亦显著增加,且丹酚酸B合成量的增加发生在Ca2+迸发之后。胞外Ca2+通道抑制剂、胞内Ca2+通道抑制剂以及胞内钙调素拮抗剂均可抑制水杨酸诱导的Ca2+迸发和丹酚酸B的生物合成。结果表明水杨酸诱发的Ca2+对丹参幼苗丹酚酸B生物合成具有重要的调控作用。