RNA Therapeutics Institute; Program in Molecular Medicine
Congenital, Hereditary, and Neonatal Diseases and Abnormalities | Nervous System Diseases | Neurology | Neuroscience and Neurobiology | Nucleic Acids, Nucleotides, and Nucleosides
Huntington's disease (HD) is caused by CAG repeat expansion within the HTT gene, with the dysfunction and eventual loss of striatal medium spiny neurons a notable feature. Since medium spiny neurons receive high amounts of synaptic input, we hypothesised that this vulnerability originates from an inability to sustain presynaptic performance during intense neuronal activity. To test this hypothesis, primary cultures of either hippocampal or striatal neurons were prepared from either wild-type mice or a knock-in HD mouse model which contains 140 poly-glutamine repeats in the huntingtin protein (htt(Q140/Q140)). We identified a striatum-specific defect in synaptic vesicle (SV) endocytosis in htt(Q140/Q140) neurons that was only revealed during high frequency stimulation. This dysfunction was also present in neurons that were heterozygous for the mutant HTT allele. Depletion of endogenous huntingtin using hydrophobically-modified siRNA recapitulated this activity-dependent defect in wild-type neurons, whereas depletion of mutant huntingtin did not rescue the effect in htt(Q140/Q140) neurons. Importantly, this SV endocytosis defect was corrected by overexpression of wild-type huntingtin in homozygous htt(Q140/Q140) neurons. Therefore, we have identified an activity-dependent and striatum-specific signature of presynaptic dysfunction in neurons derived from pre-symptomatic HD mice, which is due to loss of wild-type huntingtin function. This presynaptic defect may render this specific neuronal subtype unable to operate efficiently during high frequency activity patterns, potentially resulting in dysfunctional neurotransmission, synapse failure and ultimately degeneration.
Clathrin, Endocytosis, Endosome, Huntington's disease, Neurodegeneration, Neuron, Synapse, Vesicle
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© 2019 Elsevier Inc. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/BY-NC-ND/4.0/).
DOI of Published Version
McAdam RL, Morton A, Gordon SL, Alterman JF, Khvorova A, Cousin MA, Smillie KJ. Loss of huntingtin function slows synaptic vesicle endocytosis in striatal neurons from the httQ140/Q140 mouse model of Huntington's disease. Neurobiol Dis. 2020 Feb;134:104637. doi: 10.1016/j.nbd.2019.104637. Epub 2019 Oct 12. PMID: 31614197. Link to article on publisher's site
Neurobiology of disease
McAdam RL, Morton A, Gordon SL, Alterman JF, Khvorova A, Cousin MA, Smillie KJ. (2020). Loss of huntingtin function slows synaptic vesicle endocytosis in striatal neurons from the htt(Q140/Q140) mouse model of Huntington's disease. Open Access Articles. https://doi.org/10.1016/j.nbd.2019.104637. Retrieved from https://escholarship.umassmed.edu/oapubs/4166
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This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.
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