T-Box Protein 18 (TBX18)

Several related genes, members of the T-box gene family, encode a similar N-terminal DNA-binding domain, the T-box, and play critical roles in human embryonic development. Mutations in human TBX5 and TBX3 , for example, cause the developmental disorders Holt-Oram syndrome and ulnar-mammary syndrome, respectively. The T-box sequence in the TBX18 protein is most similar to that in mouse Tbx15/Tbx8, having 95% amino acid similarity and 92% identity.These progenitor cells, which express the T-box transcription factor Tbx18, migrate onto the outer cardiac surface to form the epicardium, and then make a substantial contribution to myocytes in the ventricular septum and the atrial and ventricular walls. Tbx18-expressing cardiac progenitors also give rise to cardiac fibroblasts and coronary smooth muscle cells.