PhD Scientific Days 2023

KDP Poster session

Phosphoproteomic Analysis Reveals Post-Transcriptional Dysregulation in Huntington’s Disease Patient-Derived Induced Neurons

Text of the abstract

Huntington disease (HD) is a heritable fatal neurodegenerative disorder with rising prevalence characterized by severe symptoms but no successful treatment available. HD is caused by CAG expansions in the huntingtin (HTT) gene, leading to protein aggregation. It is challenging to study HD due to the lack of appropriate model systems that can capture human ageing. Our group studies HD using a novel induced neuronal (iN) model which serves as a unique patient-derived cellular system for age-related neuronal disease modeling. iNs uniquely maintain the aging, epigenetic and genetic features of the donor. Impairments in autophagy - an ubiquitinal lysosomal protein degradation pathway indispensable for protein homeostasis and cellular function – seems to play a critical role in the neuronal death in HD. However, understanding of how alterations in autophagy causes cellular dysfunction and death is lacking.
In this study, we established an iN model to study impairments in HD at the proteome level with special interest in autophagy-related pathways.
We performed mass spectrometry (MS) and phospho-MS measurements of iNs generated from HD-iNs and healthy donors (Ctr-iNs). We gained information about protein abundance and activity from MS and phospho-MS data, respectively. Following quality check and normalization of the raw data we performed bioinformatical analysis.
We found 139 proteins with significantly altered abundance and activity, 68 of which has lower and 71 higher activity in HD-iNs. Most interestingly we identified 26 “ON/OFF” proteins with no detectable activity in HD-iNs. These proteins showed no significant differences in the RNA level or in the protein abundance, ensuring that HD specific alteration happened post-translationally. This is a highly valuable finding, as the radical difference in these “ON/OFF” proteins suggest they play critical role in HD pathomechanism. To confirm this, we will validate the significance of 2-3 selected targets which showed such robust alteration in HD iNs. We will perform CRISPR modification experiments to silence (CRISPRi) or enhance (CRISPRa) the selected targets to gain new information about their role in neural function.
Our main purpose in this project is to identify novel key protein targets dysregulated in HD which can serve for future therapeutic strategies.