Characterization and expressional analysis of Dleu7 during Xenopus tropicalis embryogenesis

We characterized the genomic structure and developmental expression of the Dleu7 (deleted in lymphocytic leukemia, 7) gene in Xenopus tropicalis and the evolution of the gene across species. Within the protein-coding sequence (CDS) region, X. tropicalis Dleu7 consists of two exons and one intron. However, bioinformatic analysis indicates that this 211-amino-acid protein contains no obvious functional domains or known motifs. Reverse-transcription polymerase chain reaction and whole-mount in situ hybridization results revealed that, in addition to its expression in the blood island region, some regions of the central nervous system, and subdomains of the neural tube, X. tropicalis Dleu7 is zygotically expressed primarily in mesoderm tissues such as notochord and muscles during early embryogenesis. Expression in notochord is consistent with results from genome-wide association studies suggesting that DLEU7 is related to human adult height. Expression in the blood island region, where blood cell precursors (including B cells) are generated, implies a potential conserved role for Dleu7 in B-cell development between amphibians and mammals. Expression of Dleu7 in some regions of the central nervous system and subdomains of the neural tube also suggests other functions in development. Phylogenetic analysis indicated that Dleu7 is a vertebrate-specific gene and undergoes strong selective pressure in lower vertebrates but is functionally constrained in higher mammals. When subcellular localization was examined by overexpression of enhanced green fluorescent protein fusion protein, Dleu7 showed centrosome localization with main distribution in cytoplasm. Treating gastrula embryos with SU5402, a small molecular inhibitor of the fibroblast growth factor (FGF) receptor, confirmed that Dleu7 expression in mesoderm is regulated by FGF signaling. Our data provide important clues for pathogenesis and physiology during development from the perspective of evolutionary conservation.