Effect of a Heterodimeric Complex of the Transcription Factors SoxD (Sox15) and Xanf1 on the Formation of the Xanf1 Gene Expression Zone during the Early Development of the Forebrain in the Spur-Toed Frog

Abstract

The effect of a protein complex consisting of the homeodomain transcription factor Xanf1 and the HMG-containing transcription factor SoxD (homologue Sox15 in human and mouse, group G of the Sox family) on the formation of a spatial pattern of the Xanf1 gene expression has been studied. The Xanf1 factor determines the early development of the forebrain, and the disturbance of its expression results in the reduction of this part of the brain; the pan-neural factor SoxD is necessary for the formation of the neuroectoderm at the earliest stages of development. The study of the functioning of a complex of these factors is important for understanding the molecular bases of the formation of the nervous system. The functional role of the formation of the SoxD–Xanf1 complex directly in developing embryos of the spur-toed frog Xenopus laevis has been studied using the method of in situ hybridization with probes to Xanf1 mRNA. The analysis of changes in the Xanf1 gene expression by the action of the heterodimeric complex suggests that the inhibitory effect of the repressor Xanf1 on the transcription of its own gene is neutralized in the anterior zone at the neurula stage where it is functionally necessary for the stabilization of the cellular status as the anterior forebrain neuroectoderm.