Developmental expression of maf-1 messenger ribonucleic acids in rat kidney by in situ hybridization histochemistry

maf is a family of oncogenes, originally identified from the avian oncogeni c retrovirus AS42, which encodes a nuclear bZip transcription factor protei n. It has been reported that maf family genes have critical roles in embryo logical development and cellular differentiation. In this study, the distri bution of maf-1 genes, the rat homologues of mafB, was examined in rat kidn eys at the embryonic stages from 13 days, gestation (E13) through E21 and t hen 1, 2, 4, and 8 weeks after birth by in situ hybridization with S-35-lab eled antisense riboprobes. The cellular localization was determined using d ouble in situ hybridization. Expression of maf-1 mRNA appeared weakly on E1 5 and was restricted to glomerular visceral epithelial cells during the pre - and postnatal stages until 2 weeks after birth and then gradually diminis hed. Double in situ hybridization demonstrated that maf-1 mRNA-positive cel ls in glomerulus also expressed Pod-1 gene, suggesting that maf-1 mRNA was expressed in the podocyte. These findings suggest that the expression of ma f-1 gene may be involved in embryological development and/or differentiatio n of the kidney. (C) 2000 Academic Press.