THE CHICKEN NKX2.8 HOMEOBOX GENE - A NOVEL MEMBER OF THE NK-2 GENE FAMILY

We have isolated the chicken homeobox gene NKX2.8, which represents a novel member of the NK-2 gene family. Besides the homeodomain, the NKX 2.8 protein contains two other conserved sequences, a TN and an NK2 do main. NKX2.8 is expressed in the ventral foregut, the developing heart , in the epithelial layers of the branchial arches and in the dorsal m esocardium. Thus, its expression overlaps partially, but also differs significantly from another chicken tinman orthologue, the NKX2.5 gene. It is suggestive that NKX2.8 and NKX2.5 play a cooperative role in ea rly heart development.