Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands; MRC, LMCB, University College London, Gower Street, London WC1E 6BT, UK.
Department of Cell Biology and Infection, Institut Pasteur, Université Paris Cité, 25 rue du Dr. Roux, 75015 Paris, France.
Curr Biol. 2022 Apr 25;32(8):R385-R397. doi: 10.1016/j.cub.2022.03.021.
The textbook view of cell division terminates with the final separation of the two daughter cells in the process called abscission. However, in contrast to this classical view, a variety of cell types in multicellular organisms are connected through cytoplasmic bridges, which most often form by incomplete abscission or - more rarely - by local fusion of plasma membranes. In this review, we survey the distribution, function, and formation of cytoplasmic bridges across the eukaryotic tree of life. We find that cytoplasmic bridges are widespread, and were likely ancestrally present, in almost all lineages of eukaryotes with clonal multicellularity - including the five 'complex multicellular' lineages: animals, fungi, land plants, red algae, and brown algae. In animals, cytoplasmic bridges resulting from incomplete abscission are ubiquitous in the germline and common in pluripotent cell types. Although cytoplasmic bridges have been less studied than other structural mediators of multicellularity (such as adhesion proteins and extracellular matrix), we propose that they have played a pivotal role in the repeated evolution of eukaryotic clonal multicellularity - possibly by first performing a structural role and later by allowing exchange of nutrients and/or intercellular communication, which notably buffered cell-cell competition by averaging gene expression. Bridges were eventually lost from many animal tissues in concert with the evolution of spatial cell differentiation, cell motility within the organism, and other mechanisms for intercellular distribution of signals and metabolites. Finally, we discuss the molecular basis for the evolution of incomplete abscission and examine the alternative hypotheses of single or multiple origins.
教科书上对细胞分裂的描述以两个子细胞在称为胞质分离的过程中的最终分离而结束。然而，与这种经典观点相反，多细胞生物中的各种细胞类型通过细胞质桥连接，这些细胞质桥通常通过不完全的胞质分离形成，或者更罕见的是通过质膜的局部融合形成。在这篇综述中，我们调查了细胞质桥在真核生物树中的分布、功能和形成。我们发现，细胞质桥广泛存在，并且在具有克隆多细胞性的几乎所有真核生物谱系中都可能是祖先存在的 - 包括五个“复杂多细胞”谱系：动物、真菌、陆地植物、红藻和褐藻。在动物中，由于不完全胞质分离而形成的细胞质桥在生殖系中普遍存在，并且在多能细胞类型中也很常见。尽管细胞质桥的研究不如其他结构介导的多细胞性（如粘附蛋白和细胞外基质）那么多，但我们提出，它们在真核克隆多细胞性的反复进化中发挥了关键作用 - 可能首先发挥结构作用，然后允许营养物质和/或细胞间通讯的交换，这显著通过平均基因表达缓冲细胞-细胞竞争。随着空间细胞分化、生物体内部细胞运动以及信号和代谢物的其他细胞间分布机制的进化，桥最终从许多动物组织中丢失。最后，我们讨论了不完全胞质分离进化的分子基础，并检验了单一或多个起源的替代假说。
