SOX7 transcription factor: sequence, chromosomal localisation, expression,transactivation and interference with Wnt signalling

The Sox gene family consists of several genes related by encoding a 79 amin o acid DNA-binding domain known as the HMG box. This box shares strong sequ ence similarity to that of the testis determining protein SRY. SOX proteins are transcription factors having critical roles in the regulation of diver se developmental processes in the animal kingdom. We have characterised the human SOX7 gene and compared it to its mouse orthologue. Chromosomal mappi ng analyses localised mouse Sox7 on band D of mouse chromosome 14, and assi gned human SOX7 in a region of shared synteny on human chromosome 8 (8p22). A detailed expression analysis was performed in both species. Sox7 mRNA wa s detected during embryonic development in many tissues, most abundantly in brain, heart, lung, kidney, prostate, colon and spleen, suggesting a role in their respective differentiation and development. In addition, mouse Sox 7 expression was shown to parallel mouse Sox18 mRNA localisation in diverse situations. Our studies also demonstrate the presence of a functional tran sactivation domain in SOX7 protein C-terminus, as well as the ability of SO X7 protein to significantly reduce Wnt/beta -catenin-stimulated transcripti on. In view of these and other findings, we suggest different modes of acti on for SOX7 inside the cell including repression of Wnt signalling.