Structure and expression pattern of the murine Hox-3.2 gene.

The murine homeobox-containing gene Hox-3.2 is the most 5' member of the Hox-3 complex on chromosome 15 isolated to date. Conceptual translation of the longest ORF gives a protein of 260 amino acids lacking the conserved hexapeptide found in most homeobox genes. Northern analysis detects three transcripts of 1.5, 1.9 and 3.2 kb in day 9 to 15 p.c. embryos. As early as day 8.5 p.c., transcripts can be detected in the posterior part of the embryo by in situ hybridization. At this developmental stage no or only very weak expression is visible in the neural plate. At day 10.5 Hox-3.2 is detected in the ventral part of the neural tube with a sharp anterior boundary at the level of the third thoracic prevertebra. This anterior boundary remains at day 12.5 and day 14.5. In contrast to Hox-3.1, Hox-3.2 is not expressed in the dorsal horns containing the sensory neurons at day 14.5 p.c. Hox-3.2 transcripts are also detected in the posterior prevertebrae, the hindlimb buds and the cortex of the developing kidney. Unlike Hox-1.4 and Hox-1.3 and their paralogs, Hox-3.2, -2.5 and -4.4 (5.2) show strikingly different anterior boundaries of expression in the CNS and prevertebrae.