Loss of huntingtin function slows synaptic vesicle endocytosis in striatal neurons from the httQ140/Q140 mouse model of Huntington's disease.

Loss of huntingtin function slows synaptic vesicle endocytosis in striatal neurons from the httQ140/Q140 mouse model of Huntington's disease. Neurobiol Dis. 2019 Oct 12;:104637 Authors: McAdam RL, Morton A, Gordon SL, Alterman JF, Khvorova A, Cousin MA, Smillie KJ Abstract 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 (httQ140/Q140). We identified a striatum-specific defect in synaptic vesicle (SV) endocytosis in httQ140/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 httQ140/Q140 neurons. Importantly, this SV endocytosis defect was corrected by overexpression of wild-type...
Source: Neurobiology of Disease - Category: Neurology Authors: Tags: Neurobiol Dis Source Type: research