AAV with CamKII(0.4) promoter driven Cre Inducible hChR2(T159C)-ECFP

This AAV expresses DIO-hChR2(T159C)-ECFP driven by a neuron CamKII(0.4) promoter.

This 0.4 Kb promoter is derived from murine α-Calcium/calmodulin-dependent kinase II (CaMKII), a gene with expression restricted to excitatory neurons in the neocortex and hippocampus. It was shown that the promoter activity of CaMKII(0.4) is almost identical to that of CaMKII(1.3) in cortical neurons, Compared to CaMKII(1.3), this short promoter allows cloning of longer gene of interest into the AAV construct .

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).