DIFFERENTIAL EXPRESSION OF MAF-1 AND MAF-2 GENES IN THE DEVELOPING RAT LENS

Purpose. To examine the expression of maf-1 and maf-2 protocogenes in the developing rat lens. Methods. Maf-1 and maf-2 transcripts were ass ayed in rat lenses on embryonic days 13 and 16 (E13 and E16) by in sit u hybridization using single-stranded RNA probes. Proteins encoded by the maf-2 gene were assayed immunocytochemically in embryonic (E12, 13 , 16, 19) and postnatal day 14 and 90 (P14 and P90) lenses. Results. I n embryonic lenses, we detected maf-1 messenger RNA (mRNA) in the lens epithelium and maf-2 mRNA diffusely distributed in the lens fiber cel ls, By immunocytochemistry, Maf-2 was detected on E12 in the nuclei of almost all lens pit cells, On days E13, E16, and E19, however, lens e pithelial cells showed no immunoreactivity, but nuclei of fiber cells reacted strongly. On P14, nuclei containing Maf-2 protein were confine d to the equator of the lens, but at 3 months of age, no Maf-2 could b e detected in the rat lens. Western blotting showed that the anti-Maf- 2 antiserum reacted with a single protein, of molecular weight similar to 39 kDa, in rat lens. Conclusions. Results showed the spatial and t emporal regulation of maf gene expression and suggest that these genes participate in transcriptional regulation during the development of t he lens in the rat.