Huntington’s disease (HD) is a progressive neurodegenerative disease characterized by mutations in the huntingtin gene (mHtt), causing an unstable repeat of the CAG trinucleotide, leading to abnormal long repeats of polyglutamine (poly-Q) in the N-terminal region of the huntingtin, which form abnormal conformations and aggregates. Alterations in Ca2+ signaling are involved in HD models and the accumulation of mutated huntingtin interferes with Ca2+ homeostasis. Lysosomes are intracellular Ca2+ storages that participate in endocytic and lysosomal degradation processes, including autophagy. Nicotinic acid adenine dinucleotide phosphate (NAADP) is an intracellular second messenger that promotes Ca2+ release from the endo-lysosomal system via Two-Pore Channels (TPCs) activation. Herein, we show the impact of lysosomal Ca2+ signals on mHtt aggregation and autophagy blockade in murine astrocytes overexpressing mHtt-Q74. We observed that mHtt-Q74 overexpression causes an increase in NAADP-evoked Ca2+ signals and mHtt aggregation, which was inhibited in the presence of Ned-19, a TPC antagonist, or BAPTA-AM, a Ca2+ chelator. Additionally, TPC2 silencing revert the mHtt aggregation. Furthermore, mHtt has been shown co-localized with TPC2 which may contribute to its effects on lysosomal homeostasis. Moreover, NAADP-mediated autophagy was also blocked since its function is dependent on lysosomal functionality. Taken together, our data show that increased levels of cytosolic Ca2+ mediated by NAADP causes mHtt aggregation. Additionally, mHtt co-localizes with the lysosomes, where it possibly affects organelle functions and impairs autophagy.
NAADP-Evoked Ca2+ Signaling Leads to Mutant Huntingtin Aggregation and Autophagy Impairment in Murine Astrocytes
Cássia Arruda Souza Pereira,N. C. Medaglia,R. Ureshino,C. Bincoletto,M. Antonioli,G. Fimia,M. Piacentini,Gustavo Pereira,A. Erustes,S. Smaili
Published 2023 in International Journal of Molecular Sciences
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- Publication year
2023
- Venue
International Journal of Molecular Sciences
- Publication date
2023-03-01
- Fields of study
Biology, Medicine
- Identifiers
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- Source metadata
Semantic Scholar, PubMed
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