PAX8 (Paired Box Protein PAX8) The paired box (PAX) genes code for a family of transcription factors containing a paired box domain, an octapeptide, and a paired-type homeodomain. PAX proteins are essential for the formation of several tissues from all germ layers in the mammalian embryo. Pax8 is a member of this family with a crucial role in the morphogenesis of the thyroid gland. It also has an important organogenetic role for the kidney, Müllerian system and inner ear. In the thyroid, Pax8 is a master gene that regulates maintenance of the differentiated thyroid follicular cell phenotype. As such it controls and activates the transcription and thyroid specific expression of the main proteins responsible for the functional activity of follicular cells such as TG (thyroglobulin), TPO (thyroperoxidase) and NIS (sodium/iodide symporter). In the developing Kidney PAX8 is important for renal vescicle formation and regulates the expression of the WT1 gene. L'intero contributo trasferito in MSWord occupa 14 pagine.