A transgenic mouse line to study axon initial segments and nodes of Ranvier in living neurons in vitro and in vivo
1 Heidelberg University
2 Heidelberg University, Medical Faculty Mannheim
3 MPI for Medical Research
4 University of Michigan
5 Duke University
The axon initial segment (AIS) is the cellular compartment where most neurons generate their primary output signal: the action potential. Saltatory transmission of action potentials is enabled by nodes of Ranvier, which share structural features with the AIS such as an Ankyrin-G scaffold and the clustering of voltage-gated sodium and potassium channels. Recent techniques to study the AIS and its remodeling have been limited in their application in acute living tissue. Here, we present and characterize a transgenic mouse line, in which AIS and nodes of Ranvier are intrinsically labeled with a genetically encoded fluorophore. In this model, a modified sequence generates an Ankyrin-G-GFP fusion protein that is activated by Cre recombinase and only visualizes endogenous Ankyrin-G. The label is thus specific to subsets of neurons at defined time-points in the living animal, depending on which Cre-line is selected as a cross or which virus is injected.