Non-muscle Myosin Ⅱ-A调节斑马鱼胚胎发育过程中肠内分泌细胞的极化

Non-muscle Myosin Ⅱ-A Is Required for the Polarization of Developing Enteroendocrine Cells in Zebrafish Embryos

胃肠道上皮由包括肠内分泌细胞在内的多种细胞类型组成,其中肠内分泌细胞占胃肠道上皮细胞总量的1%左右。在哺乳动物胚胎发育过程中,肠内分泌细胞位于深层组织,因此很难观察和研究。到目前为止,参与调节肠内分泌细胞形成和更新的分子调控机制仍然很不清楚。Tg（nkx2.2a：m EGFP）转基因斑马鱼品系中GFP表达在发育过程中的肠内分泌细胞,并且在胚胎期斑马鱼通体透明,因此Tg（nkx2.2a：m EGFP）为研究胚胎发育过程中肠内分泌细胞的形成过程及其分子调控提供了良好的模型。该研究发现,斑马鱼肠内分泌细胞形成的关键阶段为受精后48-72 h（hour past fertilization,hpf）,而极化的关键时期为60-72 hpf。斑马鱼中Non-muscle Myosin II-A（NM II-A）对应的两个基因myh9a和myh9b在肠内分泌细胞极化关键阶段的肠上皮表达。在60-70 hpf,利用不同浓度的NM II功能特异性的抑制剂blebbistatin处理Tg（nkx2.2a：m EGFP）斑马鱼胚胎,结果显示：blebbistatin可抑制肠内分泌细胞的极化,并呈现剂量依赖性,随着blebbistatin浓度的增加极化细胞的比例越来越低;提示NM II-A调节斑马鱼胚胎发育过程中肠内分泌细胞的极化。

The epithelium of the gastrointestinal tract comprises multiple cell types, including the enteroendocrine cells, which constitute 1% of the total epithelial cell population. Intestinal enteroendocrine cells are not clustered together but spread as single cell throughout the intestinal tract. The deep internal position of the developing digestive system has made morphological analysis of this organ relatively difficult, particularly at early stages of development. Up to date, the regulation of enteroendocrine cells polarization remains poorly understood. In Tg（nkx2.2a：m EGFP） line, the regulatory elements of the nkx2.2a gene drive strong GFP expression in enteroendocrine cells. Additionally, zebrafish embryos are transparent. Therefore, this line appears to be a good model for study of intestinal enteroendocrine cell development. Here we found that 48-72 h past fertilization（hpf） is an important stage for enteroendocrine cells formation, and 60-72 hpf is an important stage for its polarization. Non-muscle Myosin II-A（NM II-A） gene myh9 a and myh9 b were expressed in intestinal epithelium during a time window encompassing enteroendocrine cells polarization. Blocking the function of NM II-A by blebbistatin impaired polarization of enteroendocrine cells at a dose-dependent manner. This result suggests that NM II-A is required for the polarization of developing enteroendocrine cells in zebrafish embryos