Multi-epitope immunocapture of huntingtin reveals striatum-selective molecular signatures in Huntington's disease mouse models

ABSTRACT: Huntington's disease (HD) is a debilitating progressive neurodegenerative disorder that has profound effects on an individual's cognitive, motor, and behavioral functions. HD is caused by mutation in the huntingtin (HTT) gene that results in CAG repeat expansion and production of an aggregation-prone polyglutamine-containing protein (mHTT). The expression of mHTT causes selective degeneration, mainly in the striatum and cortex brain regions. Yet, the molecular signatures that underlie their selective sensitization remain incompletely characterized. In HD mouse models, we systematically employed immunopurification-mass spectrometry using HTT antibodies targeting non-overlapping epitopes to capture distinct sub-cellular pools of HTT complexes and postulate domain-specific interactions. We also identified mHTT- and tissue-dependent interactions at different disease stages, which were validated using targeted mass spectrometry and computational analysis of HD genetic modifiers. Among the polyQ-dependent, striatum-enriched interactions, we identified interaction with the mediator complex that results in its altered nuclear-cytoplasmic distribution. Integrating IP-MS data with thermal profiling of the mediator complex in HTT deficient cells supports an interaction interface with the mediator tail domain. Broadly, striatum-enriched HTT interactions highlight calcium homeostasis and ion transport at the synapse as sensitizing molecular signatures.

INSTRUMENT(S): timsTOF Ultra, Q Exactive HF

ORGANISM(S): Homo Sapiens (ncbitaxon:9606) Mus Musculus (ncbitaxon:10090)

SUBMITTER: Ileana M Cristea  

PROVIDER: MSV000094509 | MassIVE | Wed Apr 10 09:45:00 BST 2024

SECONDARY ACCESSION(S): PXD051339

REPOSITORIES: MassIVE