AP-2.2, a novel gene related to AP-2, is expressed in the forebrain, limbs and face during mouse embryogenesis

Using a differential subtractive hybridization cloning procedure we have recently identified the AP-2.2 gene as a novel early retinoic acid-induced gene in murine P19 embryonal carcinoma cells. We have also shown that the AP-2.2 protein, which is highly related to the AP-2 transcription factor, can activate transcription when bound to an AP-2 consensus binding site [Oulad-Abdelghani et al. (1995) Mel. Cell. Biol., submitted]. We report here the in situ hybridization pattern of expression of AP-2.2 transcripts during mouse embryogenesis. At 7.5 days post-coitum, AP-2.2 transcripts were detected in the boundary region between neural plate and surface ectoderm, as well as in extra-embryonic tissues. By 8.0-8.5 gestational days, AP-2.2 transcripts appeared to be expressed in premigratory and migrating neural crest cells. Over the following days, the AP-2.2 gene displayed region-restricted expression in the facial mesenchyme, especially around the embryonic mouth cavity and the nasal cavities, as well as in the surface ectoderm, nasal and oral epithelia. AP-2.2 RNA was also specifically expressed in the presumptive cortical region of the forebrain vesicles. AP-2.2 transcripts were restricted to the distal mitotic area (the 'progress zone') of the limb buds and of the genital bud. AP-2.2 expression also appeared to be specific for primordial germ cells in the genital ridges. Thus, the AP-2.2 gene is expressed in several embryonic areas whose development can be affected by retinoids, such as the forebrain, face and limb buds.