Bloomfield Gareth, Pears Catherine
Biochemistry Department, Oxford University, South Parks Road, Oxford OX1 3QU, UK.
J Cell Sci. 2003 Aug 15;116(Pt 16):3387-97. doi: 10.1242/jcs.00649. Epub 2003 Jul 2.
Reactive oxygen species are known to have a signalling role in many organisms. In bacteria and yeast various response systems have evolved to combat oxidative stress which are triggered by reactive oxygen species. Mammals and plants are known to actively generate reactive oxygen species such as superoxide during signalling responses to a variety of extracellular factors. We report here the generation of superoxide as a signalling molecule in early development of Dictyostelium discoideum. Dictyostelium grows as single amoebae but, on starvation, the single cells aggregate to form a multicellular organism. Superoxide is generated in response to a secreted factor during the transition to the multicellular phase of development. Scavenging superoxide, either pharmacologically or by overexpressing the enzyme superoxide dismutase, inhibits the formation of the aggregate. This report of the use of superoxide as a signalling molecule in a lower eukaryote as it switches to a multicellular phase suggests that this signalling mechanism arose early in the evolution of multicellular organisms, perhaps as a necessary consequence of the need to diversify the number and type of signalling pathways available to facilitate intercellular communication.
已知活性氧在许多生物体中具有信号传导作用。在细菌和酵母中，已经进化出各种应对系统来对抗由活性氧引发的氧化应激。已知哺乳动物和植物在对多种细胞外因子的信号反应过程中会主动产生活性氧，如超氧化物。我们在此报告在盘基网柄菌早期发育过程中超氧化物作为信号分子的产生。盘基网柄菌以单个变形虫的形式生长，但在饥饿时，单个细胞聚集形成多细胞生物体。在向发育的多细胞阶段转变过程中，超氧化物是对一种分泌因子作出反应而产生的。通过药理学方法或通过过表达超氧化物歧化酶来清除超氧化物，会抑制聚集体的形成。这篇关于超氧化物在一种低等真核生物转变为多细胞阶段时作为信号分子的报道表明，这种信号传导机制在多细胞生物进化的早期就已出现，这可能是为了增加可用于促进细胞间通讯的信号通路的数量和类型的必然结果。
