The role of the Lim1 gene in vertebrate kidney development

Lim1 has been reported to regulate the head, nerve system and kidney development in mouse, zebrafish and Xenopus. In the present study, we demonstrate that Xlim1 plays a pivotal role in the pronephric specification and development in Xenopus.In Xenopus embryos at 4-cell and 8-cell stage, loss of function experiments using DEED depletion showed that down-regulation of Xlim1 expression severely impairs the formation of pronephros, assessed by pax8 expression. Overexpressing Xlim1 by injecting constitutively active Lim1 constructs in Xenopus embryos induce remarking enlargement of pronephros at various stages during development, assessed by both in situ hybridization and immunohistochemistry staining. Furthermore we studied the working window of Xlim1 on pronephric specification in mesoderm and observed the peak time point is at stage 10.5 while the whole working window is between stage 9 and 12.5. To understand the mechanism of Xlim1's regulation in kidney development, then we performed the microarray analysis on the induced pronephric RNA sample extracted from animal caps, targeting couple of genes that either are the members involved in the lim1 pathway or in the networking that induce the pronephric specification.In summary, our data suggest that Lim1 acts as a potent factor that determines the early specification of pronephros. Its expression levels at the early stage critically influences the specification of the pronephric tubules. More knowledge about XLim1's pathway in kidney development will be studied via examining the gene targets screened from microarray analysis