To isolate the genes involved in mouse primordial germ cell (PGC) development, we carried out subtraction cDNA cloning between PGC-derived embryonic germ (EG) cells and inner cell mass-derived embryonic stem cells. Among the genes preferentially expressed in EG cells, we found a gene encoding a receptor tyrosine kinase ErbB3. By in situ hybridization and immunohistochemical staining, the expression of ErbB3 as well as that of ErbB2, a coreceptor for ErbB3, was detected in PGCs in genital ridges at 12.5 dpc (days postcoitum). The expression was, however, downregulated at 14.5 dpc when the PGCs underwent growth cessation. Neuregulin-beta, a ligand for ErbB2 and ErbB3, was also expressed in genital ridges. In addition, a recombinant Neuregulin-beta enhanced the number of PGCs in 12.5-dpc embryos in culture. Taken together, these observations suggest that ErbB signaling controls the growth or survival of PGCs in genital ridges.
Copyright 1999 Academic Press.