Understanding the role of Hoxa3 in pharyngeal development

Abstract

Hoxa3 is required for the development of the third and fourth pharyngeal pouch-derived organs, formation of the cartilages of the throat and the hyoid bone, formation of the ninth and tenth cranial nerves, and in development of the soft palate. To determine when Hoxa3 is required in the formation of each of these structures, I used a globally expressed inducible Cre recombinase to temporally knock out Hoxa3 during development. To determine the role of Hoxa3 within the neural crest and endoderm, the two tissue types that give rise to all of the organs and structures affected in the Hoxa3 null mouse, as well as the parathyroid and thymus, I used tissue-specific Cre recombinases to knock out Hoxa3. Together, these experiments give us a good indication of when Hoxa3 function becomes necessary in the formation of the various pharyngeal structures, and of the role it plays in each.