细胞色素C与植物细胞编程性死亡

Cytochrome c and the programmed cell death in plants

目前普遍认为:细胞色素C(Cyt c)从植物线粒体内向胞浆的释放与植物细胞编程性死亡(PCD)关系密切。与动物PCD过程相似,植物线粒体内Cyt c的释放通过线粒体通透性转换孔(MPTP)或直接通过线粒体外膜的孔蛋白——电位依赖型阴离子通道进行。活性氧(ROS)诱导MPTP的形成,释放Cyt c,导致呼吸电子传递链阻断,ATP合成解偶联,产生ROS,ROS反过来再刺激Cyt c的释放;细胞浆内高水平的Ca2+会触发MPTP的形成以及Cytc的释放。作为植物PCD的早期事件,Cyt c的释放激活了特异性半胱氨酸蛋白酶类的信号级联放大途径,最后产生以核小体DNA长度为基数的DNA片段。在植物中,已经鉴定了几个具有与动物细胞凋亡蛋白酶活化因子-1相同序列的植物基因产物;Cyt c的释放对PCD的激活作为细胞凋亡的古老机制,从多细胞生物的单细胞祖先继承并进化而来。

It has been generally believed that （ 1 ） the release of mitochondrial cytochrome c （ Cyt c） into cytosol is closely associated with the programmed cell death （PCD） in plants; （2） like the PCD in animals, the release of mitochondrial Cyt c is committed via either mitochondrial permeability transition pore （MPTP） or voltage-dependent anion channel （VDAC） ; （ 3 ） reactive oxygen species （ROS） and cytosolic Ca^2 ＋ at high levels trigger the formation of MPTP and the release of mito- chondrial Cyt c, which blocks the normal respiratory electron transport chain, inducing the uncoupling of ATP bio - chemical synthesis, and generating ROS; （4） as an early event, the release of mitochondrial Cyt c activates caspases cascade pathway, with DNA fragmentation as a result of the process; （5） in plants, several gene products that share sequence ho- mology with apoptosis protease activating factor-1 （ Apaf-1 ） have already been identified; （6） Cyt c release and activation of PCD is an ancient effector of cell death, which evolved in a unicellular ancestor of multi - cellular organisms.