Institute of Botany, Plant Physiology, Leibniz University Hannover, Herrenhäuser Straße 2, 30419 Hannover, Germany.
School of Biological Sciences, University of Southampton, Southampton SO17 1BJ, UK.
Philos Trans R Soc Lond B Biol Sci. 2020 Jun 22;375(1801):20190396. doi: 10.1098/rstb.2019.0396. Epub 2020 May 4.
Endosymbiotic organelles of eukaryotic cells, the plastids, including chloroplasts and mitochondria, are highly integrated into cellular signalling networks. In both heterotrophic and autotrophic organisms, plastids and/or mitochondria require extensive organelle-to-nucleus communication in order to establish a coordinated expression of their own genomes with the nuclear genome, which encodes the majority of the components of these organelles. This goal is achieved by the use of a variety of signals that inform the cell nucleus about the number and developmental status of the organelles and their reaction to changing external environments. Such signals have been identified in both photosynthetic and non-photosynthetic eukaryotes (known as retrograde signalling and retrograde response, respectively) and, therefore, appear to be universal mechanisms acting in eukaryotes of all kingdoms. In particular, chloroplasts and mitochondria both harbour crucial redox reactions that are the basis of eukaryotic life and are, therefore, especially susceptible to stress from the environment, which they signal to the rest of the cell. These signals are crucial for cell survival, lifespan and environmental adjustment, and regulate quality control and targeted degradation of dysfunctional organelles, metabolic adjustments, and developmental signalling, as well as induction of apoptosis. The functional similarities between retrograde signalling pathways in autotrophic and non-autotrophic organisms are striking, suggesting the existence of common principles in signalling mechanisms or similarities in their evolution. Here, we provide a survey for the newcomers to this field of research and discuss the importance of retrograde signalling in the context of eukaryotic evolution. Furthermore, we discuss commonalities and differences in retrograde signalling mechanisms and propose retrograde signalling as a general signalling mechanism in eukaryotic cells that will be also of interest for the specialist. This article is part of the theme issue 'Retrograde signalling from endosymbiotic organelles'.
真核细胞的内共生细胞器，如质体（包括叶绿体和线粒体），高度整合到细胞信号网络中。在异养和自养生物中，质体和/或线粒体需要与细胞核进行广泛的细胞器-细胞核通讯，以便协调它们自身基因组与核基因组的表达，核基因组编码这些细胞器的大多数组件。这一目标是通过使用各种信号来实现的，这些信号可以向细胞核提供细胞器的数量和发育状态的信息，并反映它们对不断变化的外部环境的反应。这些信号在光合和非光合真核生物中都已被识别（分别称为逆行信号和逆行反应），因此，似乎是所有生物界真核生物中普遍存在的机制。特别是，叶绿体和线粒体都拥有关键的氧化还原反应，这是真核生物生命的基础，因此特别容易受到环境压力的影响，它们会将这些信号传递给细胞的其他部分。这些信号对于细胞的存活、寿命和环境适应至关重要，调节功能失调细胞器的质量控制和靶向降解、代谢调节以及发育信号，以及诱导细胞凋亡。自养和非自养生物中逆行信号通路之间的功能相似性令人瞩目，这表明信号机制中存在共同的原则，或者它们的进化存在相似性。在这里，我们为这个研究领域的新手提供了一个概述，并讨论了逆行信号在真核生物进化背景下的重要性。此外，我们还讨论了逆行信号机制的共性和差异，并提出逆行信号是真核细胞中一种通用的信号机制，这也将引起专家的兴趣。本文是“内共生细胞器的逆行信号”主题专刊的一部分。
