FoxJ3, a novel mammalian forkhead gene expressed in neuroectoderm, neural crest, and myotome.

Forkhead transcription factors are important regulators of animal development. Here, we describe the embryonic expression pattern for one of the novel forkhead genes that were discovered as a result of the mouse and human genome projects. It is most closely related to FoxJ2 and has been assigned the name FoxJ3. The 100-kb, 13-exon mouse Foxj3 gene on chromosome 4 encodes a 623 amino acid (aa) protein from an mRNA of at least 4.8 kb (Human FOXJ3: Chr 1, 627 aa, 5.3-kb mRNA). During the stages of mouse development investigated (embryonic day [E] 8.5-E12.5) Foxj3 is expressed in neuroectoderm, in neural crest, and in many structures derived from neural crest cells, such as facioacoustic, trigeminal, and dorsal root ganglia. Stripes of expression appear at E10.5 in the location of myotomes and expand ventrally in a pattern similar to the developing body wall musculature. Developing limbs have a complex pattern of Foxj3 expression that at E12.5 colocalizes with the condensed mesenchyme of the skeletal primordia.