Abstract：
LIM domain binding 3 (LDB3) serves as a striated muscle-specific Z-band alternatively spliced protein that plays an important role in mammalian skeletal muscle development, but its regulatory role and molecular mechanism in avian muscle development are still unclear. In this study, we reanalyzed RNA sequencing data sets of 1415 samples from 21 chicken tissues published in the NCBI GEO database. First, three variants (LDB3-X, LDB3-XN1, and LDB3-XN2) generated by alternative splicing of the LDB3 gene were identified in chicken skeletal muscle, among which LDB3-XN1 and LDB3-XN2 are novel variants. LDB3-X and LDB3-XN1 are derived from exon skipping in chicken skeletal muscle at the E18-D7 stage and share three LIM domains, but LDB3-XN2 lacks a LIM domain. Our results preliminarily suggest that the formation of three variants of LDB3 is regulated by RBM20. The three splice isomers have divergent functions in skeletal muscle according to in vitro and in vivo assays. Finally, we identified the mechanism by which different variants play different roles through interactions with IGF2BP1 and MYHC, which promote the proliferation and differentiation of chicken myoblasts, in turn regulating chicken myogenesis. In conclusion, this study revealed the divergent roles of three LDB3 variants in chicken myogenesis and muscle remodeling and demonstrated their regulatory mechanism through protein-protein interactions.
摘要：
LIM结构域结合3（LDB3）作为横纹肌特异性Z带选择性剪接蛋白，在哺乳动物骨骼肌发育中起重要作用，但其在禽类肌肉发育中的调控作用和分子机制尚不清楚。在这项研究中,我们重新分析了NCBIGEO数据库中发表的来自21个鸡组织的1415个样本的RNA测序数据集.首先,三种变体(LDB3-X，LDB3-XN1和LDB3-XN2）通过LDB3基因的选择性剪接产生在鸡骨骼肌中，其中LDB3-XN1和LDB3-XN2是新的变体。LDB3-X和LDB3-XN1来源于鸡骨骼肌E18-D7阶段的外显子跳跃，共有三个LIM域，但LDB3-XN2缺乏LIM域。我们的结果初步表明，LDB3的三个变体的形成受RBM20调控。根据体外和体内测定，三种剪接异构体在骨骼肌中具有不同的功能。最后,我们确定了不同变体通过与IGF2BP1和MYHC相互作用发挥不同作用的机制，促进鸡成肌细胞的增殖和分化，反过来调节鸡的肌生成。总之,这项研究揭示了三种LDB3变体在鸡肌生成和肌肉重塑中的不同作用，并通过蛋白质-蛋白质相互作用证明了它们的调节机制。
