Cloning and characterization of the Xenopus laevis p8 gene.

The p8 gene encodes a transcription factor with a basic helix-loop-helix motif and has been cloned in rat, mouse and human. It is upregulated in acute pancreatitis. In the present study, the Xenopus laevis homolog of p8 (Xp8) was isolated by PCR. The full-length Xp8 cDNA consists of 677 bp and encodes 82 amino acids. The basic helix-loop-helix region is well conserved between X. laevis and mammals. Overexpression of an Xp8-EGFP fusion protein indicated that Xp8 was localized to nucleus, as in mammals. Analysis by RT-PCR showed that expression of Xp8 was increased after gastrulation and maintained into later developmental stages. Expression was detected in the prospective neural region at the neurula stage by whole-mount in situ hybridization. At the larval stage, Xp8 was expressed in central nervous regions, such as ventrolateral brain, trigeminal nerve, vestibulocochlear nerve and dorsal neural tube. Expression was also detected in the basal cement gland, olfactory placode, ear vesicle, notochord and anus. This specific pattern of expression suggests that Xp8 may play a role in the development of the central nervous system in X. laevis.