NeuN-Specific Fluorescent Probe Revealing Neuronal Nuclei Protein and Nuclear Acids Association in Living Neurons under STED Nanoscopy.

Neuronal nuclei (NeuN) protein is a key RNA-associated protein to guide the transcription of RNA and regulate mRNA splicing in neurons. However, the lack of effective labeling and tracking method has hindered the elucidation of the biological mechanism of NeuN operation in living neurons to understand correlated central nervous system disorders. Here, we report a molecular probe that can be inserted into a neighboring hydrophobic-hydrophilic region in NeuN, which upon binding becomes capable of emitting light in red region. The NeuN specificity enables the probe imaging neuronal cells in primary brain regions including hippocampus, cerebellum, midbrain, and cingulate gyrus. The probes' optical properties are such to enable stimulated emission depletion imaging showing for the first time the 3D structure of RNA tangling into NeuN in a living neuron with tens of nanometer resolution.