Gąsiorowski Ludwik, Chai Chew, Rozanski Andrei, Purandare Gargi, Ficze Fruzsina, Mizi Athanasia, Wang Bo, Rink Jochen C
Department of Tissue Dynamics and Regeneration, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany.
Department of Bioengineering, Stanford University, Stanford, USA.
bioRxiv. 2024 May 28:2024.05.24.595708. doi: 10.1101/2024.05.24.595708.
The remarkable regenerative abilities of flatworms are closely linked to neoblasts - adult pluripotent stem cells that are the only division-competent cell type outside of the reproductive system. Although the presence of neoblast-like cells and whole-body regeneration in other animals has led to the idea that these features may represent the ancestral metazoan state, the evolutionary origin of both remains unclear. Here we show that the catenulid , a member of the earliest-branching flatworm lineage, lacks conventional neoblasts despite being capable of whole-body regeneration and asexual reproduction. Using a combination of single-nuclei transcriptomics, in situ gene expression analysis, and functional experiments, we find that cell divisions are not restricted to a single cell type and are associated with multiple fully differentiated somatic tissues. Furthermore, the cohort of germline multipotency genes, which are considered canonical neoblast markers, are not expressed in dividing cells, but in the germline instead, and we experimentally show that they are neither necessary for proliferation nor regeneration. Overall, our results challenge the notion that canonical neoblasts are necessary for flatworm regeneration and open up the possibility that neoblast-like cells may have evolved convergently in different animals, independent of their regenerative capacity.
扁形虫卓越的再生能力与新细胞密切相关，新细胞是成体多能干细胞，是生殖系统之外唯一具有分裂能力的细胞类型。尽管其他动物中存在类似新细胞的细胞和全身再生现象，这使得人们认为这些特征可能代表后生动物的原始状态，但两者的进化起源仍不清楚。在这里，我们表明，最早分支的扁形虫谱系成员链涡虫，尽管能够进行全身再生和无性繁殖，但却缺乏传统的新细胞。通过结合单核转录组学、原位基因表达分析和功能实验，我们发现细胞分裂并不局限于单一细胞类型，而是与多种完全分化的体细胞组织相关。此外，被认为是典型新细胞标志物的生殖系多能性基因群，并非在分裂细胞中表达，而是在生殖系中表达，并且我们通过实验表明它们对于增殖和再生既非必要条件。总体而言，我们的结果挑战了典型新细胞是扁形虫再生所必需的这一观念，并开启了类似新细胞可能在不同动物中独立于其再生能力而趋同进化的可能性。
