BACKGROUND: The kidney development involves a wide variety of developmental processes requiring a lot of genes expressed in a sequential manner. The aim of the present study is to identify new genes involved in these processes.
METHODS: To obtain a view of the mouse embryonic kidney transcriptome we used the SADE method, which allows large-scale quantitative gene expression measurements.
RESULTS: 7,689 tags were sequenced from our library. Among the 4,507 unique transcripts yielded, 64% correspond to known genes, 22% ESTs, 12% unidentified genes. 472 genes were differentially expressed as compared to published adult kidney library. Among these, we identified several candidate genes and focused on a particular one: thymosin beta4 (Tbeta4), an actin-sequestering protein more highly expressed in fetal kidney. First we studied the in vivo expression patterns of Tbeta4 transcript during kidney development. Tbeta4 increases throughout the kidney development and remains high during active nephrogenesis. Moreover, the spatial distribution of Tbeta4 mRNA was analysed and reveals that during active nephrogenesis (i.e., 18 dpc) Tbeta4 is localised in differentiating glomeruli. In adult kidney, Tbeta4 remains expressed in podocytes and collecting ducts.
CONCLUSION: Our results provide the first demonstration of Tbeta4 production in vivo by embryonic kidney and further show that Tbeta4 is implicated in kidney organogenesis.