Poster Presentation 28th Annual Lorne Proteomics Symposium 2023

Quantitative targeted and global proteomics reveal novel biomarkers of disease in mouse models of a rare-genetic epilepsy disorder  (#105)

Todd Blackburn 1 , Selvam Paramasivan 1 , Nikola Jancovski 1 , Melody Li 1 , Nicholas Williamson 2 , Snezana Maljevic 1 , Steven Petrou 1
  1. Florey Institute, Parkville, VIC, Australia
  2. Mass Spectrometry and Proteomics, Bio21 Institute, Parkville, VIC, Australia

SCN2A encodes a voltage-gated sodium channel and de novo variants are the cause of autism and a spectrum of developmental and epileptic encephalopathies (DEEs). In this study, mass spectrometry is utilised to measure the brain proteome to assess the role of altered protein expression in various phenotypes of SCN2A DEE as well as identify potential novel biomarkers for the disorder. Brain samples were collected from WT Bl6 mice and mice heterozygous for SCN2A R854Q and S1759R mutations at postnatal (P) day 25. Samples were digested with trypsin/LysC and desalted using C18 cartridges and analysed on a Shimadzu 8050 LCMS Triple Quadrupole (QQQ) mass spectrometer for targeted quantification of SCN2A protein, as well as on a Thermofisher Orbitrap Eclipse for global proteomics. An experimental spectral library was generated from representative pooled samples from our experiment. Targeted quantitation of SCN2A protein showed no significant changes between models and brain regions. The consensus spectral library created for the DIA experiments contained 6,576 unique protein IDs and 47,917 unique peptides. An average of 4757 shared proteins were quantified using DIA between WT and SCN2A mutant models, with an average of 210 and 621 significantly up and down-regulated proteins, respectively. SCN2A protein is not differentially expressed suggesting dysfunction in neuronal firing previously seen is due to functional effects of the mutation. Proteins up and down regulated in the SCN2A models are associated with pathways related to neuronal firing, metabolism, synaptic plasticity and behaviour, suggesting these proteome changes could influence the wide range of symptoms seen in patients with SCN2A DEE.