A bacterial artificial chromosome transgenic mouse model for visualization of neurite growth.

Class III β-tubulin (Tubb3) is a component of the microtubules in neurons and contributes to microtubule dynamics that are required for axon outgrowth and guidance during neuronal development. We here report a novel bacterial artificial chromosome (BAC) transgenic mouse line that expresses Class III β-tubulin fused to mCherry, an improved monomeric red fluorescent protein, for the visualization of microtubules during neuronal development. A BAC containing Tubb3 gene was modified by insertion of mCherry complementary DNA downstream of Tubb3 coding sequence via homologous recombination. mCherry fusion protein was expressed in the nervous system and testis of the transgenic animal, and the fluorescent signal was observed in the neurons that located in the olfactory bulb, cerebral cortex, hippocampal formation, cerebellum, as well as the retina. Besides, Tubb3-mCherry fusion protein mainly distributed in neurites and colocalized with endogenous Class III β-tubulin. The fusion protein labels Purkinje cell dendrites during cerebellar circuit formation. Therefore, this transgenic line might be a novel tool for scientific community to study neuronal development both in vitro and in vivo.