Abstract
The transcription factor-encoding gene,
Sox4, is expressed in a wide range of tissues and has been shown to be functionally involved in heart, B-cell and reproductive system development.
Sox4 shows a high degree of sequence homology with another group C
Sox gene,
Sox11, which is predominantly expressed in the CNS. Since the expression of
Sox4 in the CNS has not been described we have carried out such a study.
Sox4 and
Sox11 expression increased simultaneously in the same early differentiating cells of the developing CNS except in the external granule layer of the cerebellum where
Sox11 expression preceded that of
Sox4. As development proceeded, their expression always appeared to relate to the maturational stage of the cell population, with
Sox11 expression more transient than
Sox4, except in the spinal cord where the reverse was true.
Sox4 knock-out mice have been shown to die of a heart defect half way through gestation with no observable CNS phenotype. Our more detailed analysis showed no abnormality in the spatial restriction of expression of
Sox2,
Sox11,
Mash1,
neurogenin1 or
neurogenin2, although the level of expression of
Sox11 and
Mash1 appeared a little different from the wild-type, implying that
Sox4 might indeed have a functional role in CNS development. However, since
Sox4 and
Sox11 expression is so similar, we propose that
Sox11 might compensate for the loss of
Sox4 function in the CNS such that the phenotype is extremely mild in the
Sox4 null mutant.