SOX genes

Sox genes are a family of transcription factors that bind to the minor groove in DNA, they belong to a super-family of genes characterised by a homologous sequence called the HMG (high mobility group) box. This HMG box is a DNA binding domain that is highly conserved in all eukaryotic species. HMG boxes can be very diverse in nature – with only a few amino acids being retained throughout all such sequences. They are conserved across species with homologues being identified in insects, nematodes, amphibians, reptiles, birds and a range of mammals.

Sox genes are specifically those that match the HMG box of a gene involved in sex determination called SRY (Sox stands for Sry bOX). Around 30 SOX genes highly related to SRY have been discovered. Almost all Sox genes show at least 50% amino acid similarity with the HMG box in Sry. The family is divided into subgroups according to homology in the HMG domain and outside the domain.

The Sox family has no singular function. Some Sox genes are involved in sex determination, while some are important in neuronal development. Sox2 and sox3 are involved in the transition between epithelial granule cells in the cerebellum to their migratory state. Granule cells then differentiate to granule neurons, and sox11 is involved in this process. It is thought that some Sox genes may be useful in the early diagnosis of childhood brain tumours due to this sequential expression in the cerebellum, making them a target for significant research.

Sox4 is a transcription factor in lymphocytes (B and T) and is required for B lymphocyte development.