Vrtn, or vertnin, is a gene with significant importance in mammalian development, especially in relation to thoracic vertebrae development. It functions as a novel DNA-binding transcription factor, localizing in the nucleus, binding to DNA genome-wide, and regulating the transcription of genes with VRTN binding motifs. It is also involved in somite segmentation via the Notch signaling pathway [1].

In mice, Vrtn-null embryos display somitogenesis defects with failed axial rotation and fewer somites at the thoracic somite stage. Half of Vrtn heterozygous mice show abnormal spinal development with fewer thoracic vertebrae and ribs compared to wild-type littermates. This reveals that Vrtn is essential for the development of thoracic vertebrae [1].

In conclusion, Vrtn is crucial for the development of thoracic vertebrae in mammals. The gene knockout models in mice have been instrumental in uncovering its role in somitogenesis and spinal development. Understanding Vrtn's function can potentially contribute to improving pork production by selecting alleles that increase the number of thoracic vertebrae and ribs [1].

References:

1. Duan, Yanyu, Zhang, Hui, Zhang, Zhen, Ren, Jun, Huang, Lusheng. 2018. VRTN is Required for the Development of Thoracic Vertebrae in Mammals. In International journal of biological sciences, 14, 667-681. doi:10.7150/ijbs.23815. https://pubmed.ncbi.nlm.nih.gov/29904281/