Cdh5-Optoβ2AR-IRES-lacZ transgenic mice express the light-sensitive Optoβ2AR fusion protein and lacZ under control of the Cdh5 locus promoter/enhancer regions within the BAC transgene. Cdh5-Optoβ2AR-IRES-lacZ mice from founder line B27-3 exhibit high expression levels of Optoβ2AR and lacZ in vascular endothelial cells (e.g., heart, lung, brain) - consistent with endogenous Cdh5. Additional details described further below.
The Optoβ2AR fusion protein has the transmembrane and light-sensitive domains from bovine G protein-coupled protein rhodopsin with the intracellular domains from hamster β2-adrenergic receptor. When activated with light (~473 nm), Optoβ2AR generates the secondary messenger cyclic AMP (cAMP).
For Cdh5-Optoβ2AR-IRES-lacZ transgenic mice, light activation of the Optoβ2AR molecule in vascular endothelial cells is expected to result in release of cyclic AMP (cAMP), which results in muscle relaxation.
The donating investigator reports that expression patterns appear to mimic the endogenous Cdh5 expression. Specifically, lacZ staining was observed in endothelial lined capillaries and vessels of the heart, lung and brain. Also, high levels of lacZ expression were observed in diaphragm vasculature. Before exposure to the specific wavelength of activating light, lacZ expression is observable, and the Optoβ2AR imparts no cAMP release. Upon exposure to ~473 nm light, Optoβ2AR activation causes cAMP release and results in muscle relaxation. Subsequent removal of the activating light returns muscle to the baseline state.
Mice hemizygous for the Cdh5-Optoβ2AR-IRES-lacZ transgene are viable and fertile with normal breeding, and no reported gross phenotypic abnormalities. To date (July 2019), it has not been attempted to make this strain homozygous.
This mouse model is available by way of a collaborative effort between Cornell/National Heart Lung Blood Resource for Optogenetic Mouse Signaling (CHROMus) and The Jackson Laboratory.
