AAV with hRPE(1.5) promoter driven Cre Inducible TdTomato

This AAV expresses DIO-TdTomato driven by a retina hRPE(1.5) promoter.

The RPE65 gene encodes a protein of the retinal pigment epithelium (RPE) with a key role in the cycling of retinoids. This 1.5Kb promoter gives RPE-specific expression, but the expression level is not as high as that of the shorter, 0.8Kb, promoter. This is probably due to a negative regulatory element(s) present in the 1.5Kb promoter.

In the DIO scenario, the transgene of interest is inserted in reverse orientation relative to the 5' promoter and is flanked by oppositely oriented loxP and lox2272 sites. In the absence of Cre expression, the transgene will not be produced. In the presence of Cre expression, the transgene will be "FLip-EXchanged" or FLEXed, leading to expression of the transgene. This is due to a permanent Cre-mediated recombination/inversion of the flanked transgene. This arrangement is called DIO (double-floxed inverse ORF), Cre-ON, Flex-rev (reverse), Flex-ON/FlexON, or DIO-AAV/AAV-DIO (double-floxed inverse ORF in AAV).