Identification of positive and negative regulatory regions controlling expression of the Xenopus laevis betaTrCP gene.

betaTrCP mediates the ubiquitination and subsequent degradation of several key molecules thereby playing a relevant role in different cellular processes during development and in the adult. In Xenopus embryo, betaTrCP acts as a negative regulator of Wnt signaling by interacting with beta-catenin. In this paper, we report results of the study on expression and regulation of the Xenopus betaTrCP gene. We found that xbetaTrCP is expressed in Xenopus oocytes as three transcripts, which very likely correspond to the previously identified localized mRNAs, and four isoforms. The xbetaTrCP promoter functional and structural analysis showed the presence of elements target of positive transcriptional control. Among them, we have identified a beta-catenin/Tcf signaling responsive region and a 45-bp element containing a sequence motif conforming to the SRF binding site, closer to the transcription initiation sites. There are also elements of transcriptional negative control.