A function for dystroglycan in pronephros development in Xenopus laevis.

Dystroglycan (Dg) is a laminin receptor that is expressed at the interface between the basement membrane and the cell membrane. Dg has been reported to play a role in skeletal muscle cell stability, morphogenesis of neuroepithelial tissues, and in regulating cytoskeletal organization, cell polarization, and cell signalling. In this study, we have focused our analysis on the expression of Dg-mRNA and protein at different developmental stages in the pronephros of Xenopus laevis. In order to study its role, we performed loss-of-function experiments mediated by Dg antisense morpholinos and dominant negative mutant. We show that Dg expression is first detectable when epithelialization begins in the pronephric anlage and persists later during tubulogenesis. Loss-of-function experiments induced a disorganization of the basement membrane, a drastic reduction of pronephric tubules and duct that can lead to a renal agenesis. A diminished proliferation of pronephric cell progenitors was also observed in Dg depleted embryos. Together, these data indicate that Dg plays a key role for laminin-1 assembly and pronephric cell anchoring to the basement membrane during early development of the pronephros. They also indicate that Dg may induce a signal transduction pathway controlling cell proliferation needed for the formation of tubules and their growth.