Combining CRISPR/Cas9 and brain imaging to study the link from genes to molecules to networks

Receptors, transporters, and ion channels are important targets for
therapy development in neurological diseases, but their mechanistic role
in pathogenesis is often poorly understood. Gene-editing and in vivo
imaging approaches will help to identify the molecular and functional role
of these targets and the consequence of their regional dysfunction on the
whole-brain level. We combine CRISPR/Cas9 gene-editing with in vivo
positron emission tomography (PET) and functional magnetic resonance
imaging (fMRI) to investigate the direct link between genes, molecules,
and the brain connectome. The extensive knowledge of the Slc18a2 gene
encoding the vesicular monoamine transporter (VMAT2), involved in the
storage and release of dopamine, makes it an excellent target for studying
the gene network relationships while structurally preserving neuronal
integrity and function. We edited the Slc18a2 in the substantia nigra pars
compacta of adult rats and used in vivo molecular imaging besides
behavioral, histological, and biochemical assessments to characterize the
CRISPR/Cas9-mediated VMAT2 knockdown. Simultaneous PET/fMRI was performed
to investigate molecular and functional brain alterations. We found that
stage-specific adaptations of brain functional connectivity follow the
selective impairment of presynaptic dopamine storage and release. Our
study reveals that recruiting different brain networks is an early
response to the dopaminergic dysfunction preceding neuronal cell loss. Our
combinatorial approach is a novel tool to investigate the impact of
specific genes on brain molecular and functional dynamics, which will help
to develop tailored therapies for normalizing brain function.