Mastoparan rapidly activates plant MAP kinase signaling independent of heterotrimeric G proteins
Mastoparan rapidly activates plant MAP kinase signaling independent of heterotrimeric G proteins
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DOI：
10.1104/pp.103.037275
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发表时间：
2004-04-01
期刊：
影响因子：
7.4
通讯作者：
Ellis, BE
中科院分区：
文献类型：
--
作者：
Miles, GP;Samuel, MA;Ellis, BE
从黄蜂毒液中分离得到的阳离子、两亲性十四肽--马斯多兰(MP)，能够通过与G蛋白偶联受体类似的机制，直接刺激动物异源三聚体G蛋白α亚基的鸟嘌呤核苷酸交换反应。这导致了无数的下游事件，包括丝裂原激活的蛋白激酶(MAPK)的激活。在这里，我们证明了MP对植物MAPK信号的诱导不需要植物异源三聚体G蛋白的GA-或Gb-亚基的参与，而是依赖于活性氧物种(ROS)、同源MAPKK和细胞外钙离子的内流。虽然这并不排除异三聚体G蛋白在MAPK信号转导中的作用，但它引起了人们对已发表的使用MP的实验得出的结论的担忧。GA-、GB-和GG-同源物已经在拟南芥和其他植物中被确定(Ma等人，1990；Gotor等人，1996；Lee和Assmann，1999；Saalbach等人，1999；Mason和Boella，2000)。在拟南芥中，只有一个原型GA-(拟南芥G蛋白，Alpha SubBun1[GPA1])和一个原型Gb-(拟南芥G蛋白，βSubBun1[AGB1])亚基，以及潜在的两个GG亚基(拟南芥G蛋白，Gamma亚基1[AGG1和AGG2])。拟南芥GG-和GB-亚基之间的相互作用已经被检测到(Mason和Botea，2000；综述，参见Jones，2002)，并且已经获得了GPA1和GB在体外和体内相互作用的证据(J.-G.Chen，JS Leung，和AM Jones，未发表的数据)。突变和药理学研究表明，植物异源三聚体G蛋白亚基参与许多生理过程和表型变化，包括生长素和赤霉素信号、K+通道调节、钙调节、细胞分裂和气孔功能(Aharon等人，1998；Jones等人，1998；Saalbach等人，1999；Ullah等人，2001；Wang等人，2001)。MP已被广泛用于在植物和动物中涉及G蛋白调节过程(Higashijima等人，1988；Legendre等人，1992；Legendre等人，1993；Wise等人，1993；Höler等人，1999)。例如，已报道的植物对MP处理的短期反应包括增加细胞内的钙离子，诱导氧化爆发，刺激1，4，5-肌醇三磷酸的周转，以及激活磷脂酶C、磷脂酶D2和髓鞘碱性蛋白(MBP)激酶(Scherer，1992；Kauss和Jeblick，1996；Chahdi等人，1998；Takahashi等人，1998；Chahdi等人，2003)。虽然通常认为这些反应是由异三聚体G蛋白的初始激活所介导的，但对此的直接证据有限，特别是在植物中。
It has long been known that mastoparan (MP), a cationic, amphiphilic tetradecapeptide isolated from wasp venom, is capable of directly stimulating the guanine nucleotide exchange reaction of the a-subunit of animal heterotrimeric G proteins via a mechanism analogous to that of G protein coupled receptors. This leads to a myriad of downstream events including the activation of mitogen-activated protein kinases (MAPKs). Here, we show that MP induction of plant MAPK signaling does not require the participation of either the Ga-or Gb-subunits of the plant heterotrimeric G proteins, but is reliant on reactive oxygen species (ROS), a cognate MAPKK, and influx of extracellular Ca2+ ions. While this does not preclude a role for a heterotrimeric G protein in MAPK signaling, it raises concern about the conclusions drawn from published experiments using MP. Ga-, Gb-, and Gg-homologs have been identified in Arabidopsis and other plant species (Ma et al., 1990; Gotor et al., 1996; Lee and Assmann, 1999; Saalbach, et al., 1999; Mason and Botella, 2000). In Arabidopsis, a single prototypical Ga-(Arabidopsis G PROTEIN, ALPHA SUBUNIT1 [GPA1]) and one prototypical Gb-(Arabidopsis G PROTEIN, BETA SUBUNIT1 [AGB1]) subunit and potentially, two Gg-subunits (Arabidopsis G PROTEIN, GAMMA SUBUNIT1 [AGG1 and AGG2]), are found. Interaction has been detected between the Arabidopsis Gg-and Gb-subunits (Mason and Botella, 2000; for review, see Jones, 2002), and evidence has been obtained for in vitro and in vivo interaction of GPA1 and Gb (J.-G. Chen, JS Liang, and AM Jones, unpublished data). Mutational and pharmacological studies have implicated plant heterotrimeric G protein subunits in numerous physiological processes and phenotypic changes, including auxin and gibberellin signaling, K+ channel regulation, Ca2+ regulation, cell division, and stomatal function (Aharon et al., 1998; Jones et al., 1998; Saalbach et al., 1999; Ullah et al., 2001; Wang et al., 2001).MP has been widely used to implicate G protein regulated processes in both plants and animals (Higashijima et al., 1988; Legendre et al., 1992; Legendre et al., 1993; Wise et al., 1993; Höller et al., 1999). For example, short-term responses to MP treatment reported for plants include increases in cellular Ca2+ ions, induction of an oxidative burst, stimulation of 1, 4, 5-inositol triphosphate turnover, and activation of phospholipase C, phospholipase D2, and myelin basic protein (MBP) kinases (Scherer, 1992; Kauss and Jeblick, 1996; Chahdi et al., 1998; Takahashi et al., 1998; Chahdi et al., 2003). Although it is generally assumed that these responses are mediated by the initial activation of heterotrimeric G proteins, there is limited direct evidence for this, particularly in plants.