Spatial and temporal expression pattern of a novel gene in the frog Xenopus laevis: correlations with adult intestinal epithelial differentiation during metamorphosis.
We report the cloning of a novel gene (ID14) and its expression pattern in tadpoles and adults of Xenopus laevis. ID14 encodes a 315-amino acid protein that has a signal peptide and a nidogen domain. Even though several genes have a nidogen domain, ID14 is not the homolog of any known gene. ID14 is a late thyroid hormone (TH)-regulated gene in the tadpole intestine, and its expression in the intestine does not begin until the climax of metamorphosis, correlating with adult intestinal epithelial differentiation. In contrast, ID14 is expressed in tadpole skin and tail and is not regulated by TH. In situ hybridization revealed that this putative extracellular matrix protein is expressed in the epithelia of the tadpole skin and tail and in the intestinal epithelium after metamorphosis. In the adult, ID14 is found predominantly in the intestine with weak expression in the stomach, lung, and testis. Its exclusive expression in the adult intestinal epithelial cells makes it a useful marker for developmental studies and may give insights into cell/cell interactions in intestinal metamorphosis and adult intestinal stem cell maintenance.
PubMed ID: 15053982
Article link: Gene Expr Patterns.
Genes referenced: tecta.2 trhd
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|Fig. 5. In situ localization of ID14 mRNA to the intestinal epithelium. Cross-sections of the intestine were hybridized with the antisense (A–D) or sense (E) RNA probes. (A) No specific signals were detected in the larval epithelium (le) at stage 54. (B) No signals were seen in dying larval cells (le) or proliferating, undifferentiated adult epithelial cells (ae) at stages 61 and 62. Identification of the area of adult cell proliferation demarcated by dark line is based on previous studies (Ishizuya-Oka and Ueda, 1996). (C) Signals became detectable in the adult epithelium (ae) at stage 63, and intensified by stage 66 (D). (E) Background signal was weakly seen for the intestine at stage 66 hybridized with the sense probe. ct, connective tissue; m, muscles. Bars, 20 μm.|
|Fig. 6. In situ localization of ID14 mRNA to the epithelia of tadpole skin and tail. Cross-sections of back skin (stage 66) and tail (stage 55) were hybridized with the antisense (A and B) or sense (C and D) RNA probe. Specific signal in the epithelium is seen in sections hybridized with the antisense probe in the skin (compare A and C) and tail (compare B and D). The specific signal in the secretory glands in A is consistent with the epithelial origin of the glands. The dark spots in B–D are melanin pigment granules. e, epithelia; sg, epithelial secretory glands; cl, collagen lamella. Bars, 20 mm.|