Paired Box Gene 8 (PAX8)

PAX8 is a member of the paired box (PAX) family of transcription factors. Members of this gene family typically encode proteins which contain a paired box domain, an octapeptide, and a paired-type homeodomain. This nuclear protein is involved in thyroid follicular cell development and expression of thyroid-specific genes.

The cell system they used provided direct evidence for the ability of PAX8 to activate transcription of thyroid-specific genes at their chromosomal locus and strongly suggested a fundamental role of this transcription factor in the maintenance of functional differentiation in thyroid cells. Moreover, they showed that PAX8 and thyroid transcription factor-1 (TITF1), which is encoded by the NKX2-1 gene, cooperate in the activation of the thyroglobulin promoter.