Abstract
AbstractSpinocerebellar ataxia type 17 (SCA17) is a neurodegenerative disease caused by a polyglutamine-encoding trinucleotide repeat expansion in the gene of transcription factor TATA box-binding protein (TBP). While its underlying pathomechanism is elusive, polyglutamine-expanded TBP fragments of unknown origin mediate the mutant protein’s toxicity. Calcium-dependent calpain proteases are protagonists in neurodegenerative disorders. Here, we demonstrate that calpains cleave TBP, and emerging C-terminal fragments mislocalize to the cytoplasm. SCA17 cell and rat models exhibited calpain overactivation, leading to excessive fragmentation and depletion of neuronal proteins in vivo. Transcriptome analysis of SCA17 cells revealed synaptogenesis and calcium signaling perturbations, indicating the potential cause of elevated calpain activity. Pharmacological or genetic calpain inhibition reduced TBP cleavage and aggregation, consequently improving cell viability. Our work underlines the general significance of calpains and their activating pathways in neurodegenerative disorders and presents these proteases as novel players in the molecular pathogenesis of SCA17.
Funder
Deutsche Forschungsgemeinschaft
Interdisziplinäres zentrum für klinische forschung, universitätsklinikum tübingen
Conselho nacional de desenvolvimento científico e tecnológico
Ruhr-Universität Bochum
Publisher
Springer Science and Business Media LLC
Subject
Cell Biology,Cellular and Molecular Neuroscience,Pharmacology,Molecular Biology,Molecular Medicine
Cited by
6 articles.
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