Carmichael Ruth E, Richards David M, Fahimi H Dariush, Schrader Michael
Department of Biosciences, Faculty of Health and Life Sciences, University of Exeter, Exeter EX4 4QD, UK.
Living Systems Institute, University of Exeter, Exeter EX4 4QD, UK.
Biology (Basel). 2023 Apr 27;12(5):664. doi: 10.3390/biology12050664.
Organelles within eukaryotic cells are not isolated static compartments, instead being morphologically diverse and highly dynamic in order to respond to cellular needs and carry out their diverse and cooperative functions. One phenomenon exemplifying this plasticity, and increasingly gaining attention, is the extension and retraction of thin tubules from organelle membranes. While these protrusions have been observed in morphological studies for decades, their formation, properties and functions are only beginning to be understood. In this review, we provide an overview of what is known and still to be discovered about organelle membrane protrusions in mammalian cells, focusing on the best-characterised examples of these membrane extensions arising from peroxisomes (ubiquitous organelles involved in lipid metabolism and reactive oxygen species homeostasis) and mitochondria. We summarise the current knowledge on the diversity of peroxisomal/mitochondrial membrane extensions, as well as the molecular mechanisms by which they extend and retract, necessitating dynamic membrane remodelling, pulling forces and lipid flow. We also propose broad cellular functions for these membrane extensions in inter-organelle communication, organelle biogenesis, metabolism and protection, and finally present a mathematical model that suggests that extending protrusions is the most efficient way for an organelle to explore its surroundings.
真核细胞内的细胞器并非孤立的静态区室，相反，它们形态多样且高度动态，以响应细胞需求并执行其多样且协同的功能。体现这种可塑性且日益受到关注的一种现象是细胞器膜上细管的延伸和回缩。尽管这些突起在形态学研究中已被观察到数十年，但它们的形成、特性和功能才刚刚开始被了解。在这篇综述中，我们概述了关于哺乳动物细胞中细胞器膜突起已知的和仍有待发现的内容，重点关注源自过氧化物酶体（参与脂质代谢和活性氧稳态的普遍存在的细胞器）和线粒体的这些膜延伸的最具特征的例子。我们总结了关于过氧化物酶体/线粒体膜延伸多样性的当前知识，以及它们延伸和回缩所必需的动态膜重塑、拉力和脂质流动的分子机制。我们还提出了这些膜延伸在细胞器间通讯、细胞器生物发生、代谢和保护方面的广泛细胞功能，最后提出了一个数学模型，该模型表明延伸突起是细胞器探索其周围环境的最有效方式。
