脊椎骨是脊椎动物的最主要特征。新转录因子VRTN是申请人前期通过遗传和分子手段鉴别到的控制猪和小鼠胸椎数量的基因。在猪中，增加VRTN表达量的因果突变导致猪增加一根胸椎；VRTN基因敲除小鼠胚胎致死、胸部体节分节异常，杂合子小鼠缺少一根胸椎或最后一根胸椎缺少单侧肋骨。基于上述结果，项目组拟将VRTN敲除鼠作为研究脊椎动物胸部体节分节的模型。通过原位杂交技术，确定VRTN在敲除、杂合和野生型胚胎中的时空表达情况。通过ChIP-seq和RNA-seq鉴别敲除、杂合和野生型鼠胚在胸部体节发育期的差异基因，确定VRTN的靶基因及调节的信号通路。进一步通过分子手段，检测VRTN下游与分节相关基因的表达情况，最终揭示VRTN参与胸部体节分节和分化的机理。预期结果将丰富现有胸椎分节理论，同时为人类先天性脊柱畸形的遗传诊断和利用基因修饰技术增加家畜的脊椎数提供重要理论依据。

The vertebral column is the defining characteristic of vertebrates. Through genetic and molecular assays, we firstly identified that a novel transcription factor, VRTN, controls the number of thoracic vertebrae in pigs and mice. The mutant pigs with higher VRTN expression have one more thoracic segment. VRTN- mice are embryonically lethal with fewer somites than their wild-type and heterozygous littermates at the late thoracic somite stages. Among heterozygous animals, one third has one less thoracic vertebra and others exhibit abnormal phenotypes on last thoracic element. Based on these results, we planned to study the segment of thoracic vertebrae using the existed VRTN knockout mice as follows. To identify the target genes of VRTN and the involved signal pathway, we planned to measure gene expression profiles with RNA-seq and identify the target gene with ChIP-seq for whole embryos of mice with knockout, heterozygous and wild-type genotypes from mates between VRTN+/- mice. Through in situ hybridization assays, we might identify the different expression of VRTN and the above critical gene in whole embryos with three genotypes. We aim to give a hypothesis how to VRTN control the number of thoracic vertebrae.The findings would provide important insights into the existing mechisms on the segment of thoracic vertebra, and provide necessary theoretical evidences to genetic diagnosis of human congenital vertebra deformity and to add the number of thoracic vertebrae in livestock using gene manipulation technique.