Twist基因在虾夷扇贝肌肉生长发育中的时空表达模式及调控机制研究

The weight of adductor muscle is an importantly economic indicator in scallops. Previous researches about muscle growth mainly focused on several candidate genes. However, regulatory pathways of myogenesis and muscle growth are not very clear. Twist gene is a key initiation transcription factor in mesoderm formation and myogenesis in invertebrates, which is expressed in muscle precursors of adult muscle. Recently we found that in Yesso scallop, the expressional level of Twist gene was specifically high in striated muscle of adult individuals, compared with other adult organs, which indicated that Twist gene was related of muscle growth of scallops. Based on this previously interesting result, our project will characterize spatio-temporal expression pattern of Twist gene during embryo developmental process and in the adult organs of Yesso scallop, study its interacting genes and gene coexpression network related with muscle growth, and analyze regulatory function of Twist gene related with scallop muscle growth. The results of our project will be helpful to improve our understanding in genetic mechanism of invertebrate muscle growth regulation and also benefit the molecular breeding of scallop aiming to growth improvement.

闭壳肌重量是扇贝重要的经济指标，已有关于扇贝闭壳肌生长的研究主要集中在肌肉生长相关个别基因，对于贝类肌肉发生及生长的整体调控通路目前尚不清晰。Twist基因是无脊椎动物胚胎中胚层分化和肌肉原基形成的关键起始转录因子，并对维持成体肌肉干细胞的存在起重要作用。我们在前期研究中发现Twist基因在扇贝成体横纹肌中特异高表达，暗示Twist基因与扇贝肌肉生长发育相关，但是有关Twist基因参与的调控通路目前在扇贝中还不明确。本项目将在此基础上开展虾夷扇贝Twist基因在胚胎发育和成体生长中的时空表达特征分析，构建Twist相关基因共表达网络并筛查与其互作的蛋白，初步揭示Twist基因在扇贝肌肉生长中的调控作用。项目将解析虾夷扇贝Twist基因的时空表达模式及其在肌肉生长中的调控网络，以期深入理解无脊椎动物的肌肉发生、生长调控机理，为Twist基因在高产扇贝育种中的应用价值提供理论参考。

本项目查明了Twist及其下游调控基因在虾夷扇贝肌肉发生及生长过程中的时空表达模式，确定了Twist基因在虾夷扇贝肌肉发生及生长过程中的主导调控作用；开展了Twist和Mef2基因在虾夷扇贝胚胎发育过程中的细胞学表达定位，证实了扇贝胚胎发育过程肌肉发生时Twist、Mef2的先后级联表达关系，为解析贝类肌肉发生的基因表达调控提供了更直接的证据；构建了虾夷扇贝成体器官的基因共表达调控网络，鉴别到了虾夷扇贝肌肉生长相关的显著模块，确定了Twist、NFX1、Elk1、Jun、HMBOX1等生长相关转录因子在调控网络中关键作用，在肌肉生长相关显著模块中富集到了MAPK信号通路；开展了虾夷扇贝活体肌肉损伤及修复实验，跟踪了肌肉损伤修复过程中Twist和Mef2基因的动态表达情况，初步证明了在扇贝肌肉损伤修复及生长中Twist和Mef2基因的关键调控作用；监测了虾夷扇贝肌肉损伤修复过程中的细胞增殖情况，证实了Twist及其调控基因在扇贝肌肉损伤修复中对细胞增殖、分化的关键作用。项目明确了Twist及其调控基因在扇贝肌肉发生及生长调控中的关键作用，为深入理解贝类肌肉生长调控的遗传基础提供了重要线索，对贝类分子育种具有重要的指导意义。