These iBot transgenic mice contain a floxed-STOP cassette upstream of a Clostridium botulinum neurotoxin serotype B light chain (boNT/B) gene followed by an IRES-EGFP. A CAG promoter drives expression of the construct. Expression can be regulated by the presence of cre recombinase which would facilitate the excision the floxed-stop sequence. When translated, the boNT/B protein selectively blocks calcium-dependent exocytosis.
The boNT/B protein cleaves VAMP1 (vesicle-associated membrane protein 1), VAMP2 (vesicle-associated membrane protein 2, synaptobrevin 2) and VAMP3 (vesicle-associated membrane protein 3), preventing vesicle docking and release. Although botulinum neurotoxin is a potent neuroparalytic toxin, it is also used clinically for treatment of many neuromuscular diseases.
After Cre recombinase mediated excision of the STOP cassette, EGFP expression is detected by immunohistochemical staining, and co-expresses with the neurotoxin. Mice hemizygous for the transgenic insert are viable and fertile. The Donating Investigator has not attempted to make the strain homozygous.
When bred to a strain with widespread Cre recombinase expression, the bi-allelic progeny mice exhibit a perinatal lethal phenotype.
When bred to a strain with Cre recombinase expression in cerebellar neurons, this mutant mouse strain may be useful in studies of SNARE (soluble N-ethylmaleimide-sensitive factor-attachment protein receptor )-dependent synaptic transmission.
