AAV with CamKII promoter driven Cre Inducible hChR2(T159C)-mCherry

This AAV expresses DIO-hChR2(T159C)-mCherry driven by a neuron CamKII promoter.

This 1.3 Kb promoter is derived from the murine α-Calcium/calmodulin-dependent kinase II (CaMKII), a gene with expression restricted to excitatory neurons in the neocortex and hippocampus. In cortical neurons, it was shown that the promoter activity of CaMKII(1.3) is about double that of CaMKII(2.4), probably due to some inhibitory element(s).

hChR2 is a humanized version of ChR2 for mammalian expression. The wild-type, as well as a few mutations, provide the fastest excitation of the channelrhodopsins offered, and are widely used in optogenetics techniques in neuroscience. hChR2(T159C) shows slightly higher photocurrents than the hChR2(H134R), another commonly used optogenetics tool.

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).