IDENTIFICATION OF THE VERTEBRATE IROQUOIS HOMEOBOX GENE FAMILY WITH OVERLAPPING EXPRESSION DURING EARLY DEVELOPMENT OF THE NERVOUS-SYSTEM

In Drosophila the decision processes between the neural and epidermal fate for equipotent ectodermal cells depend on the activity of proneur al genes. Members of the Drosophila Iroquois-Complex (Iro-C) positivel y regulate the activity of certain proneural AS-C genes during the for mation of external sensory organs. We have identified and characterize d three mouse Iroquois-related genes: Irxl, -2 and -3, which have a ho meodomain very similar to that of the Drosophila Iro-C genes. The sequ ence similarity implies that these three genes represent a separate ho meobox family. All three genes are expressed with distinct spatio/temp oral patterns during early mouse embryogenesis. These patterns implica te them in a number of embryonic developmental processes: the A/P and D/V patterning of specific regions of the central nervous system (CNS) , and regionalization of the otic vesicle, branchial epithelium and li mbs. (C) 1997 Elsevier Science Ireland Ltd.