单细胞水平解析涡虫TSPAN1+成体多能干细胞调控机制

涡虫无限再生能力依赖于其体内具有分化成三胚层所有细胞类型的成体多能干细胞。我们前期工作鉴定并分离了这个细胞类群，并明确了其分子标记为TSPAN1。但是TSPAN-1+细胞的内外调控机制并不明确。通过细胞共定位实验，我们发现TSPAN-1+干细胞富集在涡虫肠道周围。单细胞数据挖掘结合RNA干扰筛选揭示肠道Itga1+细胞类群对TSPAN-1＋干细胞的维持是必需的。Itga1或TSPAN-1的敲低导致干细胞转录因子ZNF764的下调；而ZNF764对涡虫干细胞的维持及组织再生是必需的。基于前期研究，我们提出科学假说：Itga1+肠道细胞是TSPAN-1＋细胞的巢细胞，通过分泌生长因子进而稳定ZNF764的表达，在转录水平促进干细胞多能性，维持涡虫再生能力。本课题研究涡虫TSPAN1+成体多能干细胞的调控机制及其对再生的影响，将在单细胞水平上揭示成体多能干细胞的命运调控机制及其与再生的关系。

The infinite regeneration capacity of planarians relies on the existence of pluripotent stem cells, which has the ability to differentiate into all cell types from three germ-layers. Our previous work identified and isolated this cell population and defined its molecular marker as TSPAN1. However, the regulatory mechanism of TSPAN-1+ pluripotent stem cells is not clear. Co-localization analysis suggests that TSPAN-1+ stem cells were concentrated around the intestinal tract of planaria. Single-cell data mining combined with RNA interference screen revealed that the intestinal Itga1+ cell group is necessary for the maintenance of TSPAN-1+ stem cells. Knockdown of Itga1 or TSPAN-1 leads to the down-regulation of stem cell transcription factor ZNF764; ZNF764 is necessary for the maintenance of planarian stem cells and tissue regeneration. Based on previous studies, we propose a hypothesis: Itga1+ intestinal cells are niche cells for TSPAN-1+ cells, which stabilizes the expression of ZNF764 through secreting growth factors, and promotes the pluripotency of stem cells at the transcription level, and thus maintains the regenerative capability of planarians. This project studies the mechanism underlying TSPAN-1+ stem cell regulation, and its role in regeneration processes, which will reveal the mechanism of fate determination of adult pluripotent stem cells and its regulation during regeneration.