Blue cones and cone bipolar cells share transcriptional specificity as determined by expression of human blue visual pigment-derived transgenes

Sequences 5' of the human blue visual pigment gene have been assayed in transgenic mice for their ability to direct cell-type-specific expression of linked β-galactosidase (lacZ) and placental alkaline phosphatase (P ALP 1) reporters. Constructs containing either 5.4 kilobases (kb) or 0.47 kb of 5' flanking DNA direct expression exclusively to the retina. Within the retina, transgene expression is confined to blue cones and cone bipolar cells, as determined, respectively, by double labeling with anti-cone pigment antibodies and by morphologic analyses. These results imply that blue cones and cone bipolar cells have partially overlapping transcriptional specificities.