Albright Ashley R, Yan Connie, Angeles-Albores David, Makushok Tatyana, Allen-Henderson Jamarc, Marshall Wallace F
Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA, USA.
Center for Cellular Construction, University of California, San Francisco, San Francisco, CA, USA.
bioRxiv. 2024 Oct 8:2023.01.09.523364. doi: 10.1101/2023.01.09.523364.
Cells have complex and beautiful structures that are important for their function. However, understanding the molecular mechanisms that produce these structures is a challenging problem due to the gap in size scales between molecular interactions and cellular structures. The giant ciliate is a unicellular model organism whose large size, reproducible structure, and ability to heal wounds and regenerate have historically allowed the formation of structure in a single cell to be addressed using methods of experimental embryology. Such studies have shown that specific cellular structures, such as the membranellar band, always form in particular regions of the cell, which raises the question: what is the source of positional information within this organism? By analogy with embryonic development, in which regionalized mRNA is often used to mark position, we asked whether specific regionalized mRNAs might mark position along the anterior-posterior axis of . By physically bisecting cells and conducting bulk RNA sequencing, we were able to identify sets of messages enriched in either the anterior or posterior half. We then conducted half-cell RNA-sequencing in paired anteriors and posteriors of cells in which the microtubule cytoskeleton was disrupted by RNAi of β-tubulin or dynein intermediate chains. We found that many messages either lost their regionalized distribution or switched to an opposite distribution, such that anterior-enriched messages in control became posterior-enriched in the RNAi cells, or vice versa. This study indicates that mRNA can be regionalized within a single giant cell and that microtubules may play a role, possibly by serving as tracks for the movement of the messages.
细胞具有复杂而精妙的结构，这些结构对其功能至关重要。然而，由于分子相互作用与细胞结构在尺寸尺度上存在差距，理解产生这些结构的分子机制是一个具有挑战性的问题。大型纤毛虫是一种单细胞模式生物，其体积大、结构可重复，且具有伤口愈合和再生能力，这使得利用实验胚胎学方法来研究单细胞中结构的形成成为可能。此类研究表明，特定的细胞结构，如膜带，总是在细胞的特定区域形成，这就引出了一个问题：该生物体中位置信息的来源是什么？类比胚胎发育过程中区域化mRNA常被用于标记位置的情况，我们不禁要问，特定的区域化mRNA是否可能沿大型纤毛虫的前后轴标记位置。通过对细胞进行物理二等分并进行大量RNA测序，我们得以识别出在前半部分或后半部分富集的信息集。然后，我们在成对的细胞前半部分和后半部分进行了半细胞RNA测序，这些细胞中的微管细胞骨架通过β -微管蛋白或动力蛋白中间链的RNA干扰而被破坏。我们发现，许多信息要么失去了其区域化分布，要么切换到相反的分布，以至于在对照中前半部分富集的信息在RNA干扰细胞中变成了后半部分富集，反之亦然。这项研究表明，mRNA可以在单个大型细胞内区域化，并且微管可能发挥作用，可能是作为信息移动的轨道。
