Mass Spectrometry Imaging Reveals the Distribution of a GABRG2 Targeting Antisense Oligonucleotide and Its Functional Effect in Rat Brain.

In recent years, the development of antisense oligonucleotides (ASOs) has gained wide interest as therapeutic agents for their potential in treating neurodegenerative diseases. ASOs are chemically modified oligonucleotides that are designed to bind complementary regions of RNA or DNA and, thereby, modulate the expression of the corresponding protein. Here, we present a multiomics approach to investigate the spatial distribution and biological effect of an ASO designed to target the mRNA that translates for γ-aminobutyric acid A receptor γ2 subunit (GABRG2), which is abundantly expressed within the brain. In this study, a rat model was used to develop a multiomics mass spectrometry (imaging) approach to map ASO distribution in brain and kidney, followed by in-depth analysis of the lipidome, proteome, and metabolome. The ASOs' phosphorothioate-modified backbone was visualized using an optimized matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) protocol, which included the introduction of an organic washing step prior to MALDI-MSI acquisition and an optimized acquisition method. On consecutive tissue sections, reactive matrix FMP10 was applied to enable the visualization of neurotransmitters, which revealed significant alterations for multiple neurotransmitters. Lastly, on the same slide, the ASOs' effect on the lipidome and proteome of the brain was further analyzed. Proteins corresponding to synaptic activity and plasticity were mainly affected by the ASO. This spatial omics approach provides insight into the comprehensive molecular landscape of ASO-mediated interventions and their promise as treatments for neurological disorders.