Regulation of PAX-6 gene expression in the lens

Purpose: PAX-6 expression in the neuroretina is dependent on an upstream promoter, a 3′ enhancer and appears to be dependent on the transcription factor cMyb. We are defining and characterizing the promoter elements and transcription factors required for regulation of PAX-6 gene expression in the lens and have begun to compare the requirements for lens expression of PAX-6 with those of the neuroretina. Methods: Transfection analysis, Northern blotting, electrophoretic mobility shift assay, DNA footprinting and 5′ RACE analysis. Results: Our initial transfection analysis indicate that -1386 to +127 (P0) of the quail PAX-6 promoter is more active in 14 day primary chicken lens cells than is -162 to +77 of the chicken αA-crystallin promoter. Deletion of the 460-bp 3′ enhancer had no effect on PAX-6 expression in chicken lens cells. cMyb mRNA was not detected in mouse or chicken lens indicating that it does not regulate expression of PAX-6 in the lens. Conclusions: These studies are the first to examine the regulation of a transcription factor required for expression of crystallin genes in the lens. Our results suggest that PAX6 expression in the lens may depend on different regulatory elements and different transcription factors than are required in the neuroretina.