A NOVEL NK-RELATED MOUSE HOMEOBOX GENE - EXPRESSION IN CENTRAL AND PERIPHERAL NERVOUS STRUCTURES DURING EMBRYONIC-DEVELOPMENT

We have identified three novel mouse homeobox genes that are related t o the Drosophila NK gene family. Two genes without direct homologues i n Drosophila were designated Nkx-5.1 and Nkx-5.2; the third gene Nkx-1 .1 constitutes the mouse homologue to NK1.Nkx-5.1 and Nkx-5.2 are clos ely linked on mouse chromosome 7, whereas Nkx-1.1 is located on a diff erent chromosome. Here, we report the spatiotemporal expression patter n of Nkx-5.1 during prenatal mouse development. Nkx-5.1 gene activity begins at Embryonic Day 10.5 in the developing ear, the neural tube, a nd dorsal root ganglia. It continues to be active throughout prenatal life in discrete regions of the brain with an anterior border in the v entral diencephalon at the optic chiasma and expression domains in mes encephalon, metencephalon, and myelencephalon. At midgestation, Nkx-5. 1 is also expressed in mesenchyme of the head and branchial arches, an d in some cranial ganglia, as well as in derivatives of neural crest, such as the truncus sympathicus and myenteric ganglia. The time patter n of Nkx-5.1 expression and its confinement to primarily postmitotic c ells of the central and peripheral nervous system suggest that Nkx-5.1 may play a role in the specification of neuronal cell types. (C) 1994 Academic Press, Inc.