Objective: Excessive mitochondrial fission has been associated with several neurodegenerative diseases, including Huntington’s disease (HD). Consequently, mitochondrial dynamics has been suggested to be a promising therapeutic target for Huntington’s disease. Mitochondrial fission depends on recruitment of Drp1 to mitochondria, and Mff (mitochondrial fission factor) is one of the key adaptor proteins for this process. Removal of Mff therefore greatly reduces mitochondrial fission. Here we investigate whether removal of Mff can mitigate HD-associated pathologies in HD transgenic mice (R6/2) expressing mutant Htt.

Method: We compared the phenotype of HD mice with and without Mff. The mice were monitored for lifespan, neurological phenotypes, Htt aggregate formation, and brain histology.

Results: We found that HD mice lacking Mff display more severe neurological phenotypes and have shortened lifespans. Loss of Mff does not affect mutant Htt aggregation, but it accelerates HD pathology, including neuronal loss and neuroinflammation.

Conclusions: Our data indicate a protective role for mitochondrial fission in HD and suggest that more studies are needed before manipulation of mitochondrial dynamics can be applied to HD therapy.

Introduction: Huntington’s disease (HD) has profound motor, behavioural and cognitive symptoms. Despite the enormous burden of this disease on the quality of life (QoL) of patients and their families, there is very limited evidence on this topic. Considering the severity of HD patients, and the high prevalence in Cyprus more studies are needed to assess QoL among Cypriot patients, in order to improve our knowledge about their living conditions and to assist the management of this condition.

Project Aim: The aim of this cross-sectional study is to assess QoL among Cypriot patients with HD, using a standardized health-related QoL questionnaire.

Materials and Methods: A generic QoL questionnaire was used, namely EQ-5D, which is a standardised instrument for use as a measure of health outcomes and is applicable to a wide range of health conditions. The study was conducted with 34 patients, which represented 46% of the Cypriot HD patient population.

Results: Ability of patients to care for themselves and to carry out usual activities were reported to be most severely affected (37.5% and 40.6% replying “Severe Problems” respectively). Mobility and psychosocial well-being were also affected to a lesser extent (25.0% and 15.6% replying “Severe Problems”). Interestingly, in the anxiety/depression scale, 77.8% of asymptomatic patients reported “Some Problems”. Half of the patients did not experience pain or discomfort but 40.6% reported “Some Problems” and 6.3% reported “Severe Problems”. The Health Status as perceived by the patients was found to be moderately to severely affected.  In multivariate ordinal regression analyses, age at onset and disease duration significantly impacted on self-care. In addition, disease duration was significantly associated with mobility, self-care and usual activities scales. No significant determinants were evidenced for Pain/Discomfort and Anxiety/Depression. Lastly, age of onset was found to be the only significant determinant of the cumulative QoL score (Range=5-15).

Conclusions: Age at onset and disease duration were found to severely affect the QoL of Cypriot HD patients, and more specifically their mobility, ability to self-care and perform usual activities. The percentage of patients reporting “Some Problems” in the Pain/Discomfort category can be explained by the direct translation of the word as presented in the questionnaire, indicating the need for language specific instruments. Perhaps more noteworthy is the phychosocial burden on even asymptomatic patients, which needs to be acknowledged and managed to improve their quality of life.

Background: Huntington’s disease (HD) is a progressive neurodegenerative disorder caused by CAG repeat expansions in the HTT gene. Somatic repeat expansion in the R6/1 mouse model of HD depends on mismatch repair and is worsened by base excision repair initiated by the 7,8-dihydroxy-8-oxoguanine-DNA glycosylase (Ogg1) or Nei-like 1 (Neil1). Ogg1 and Neil1 repairs common oxidative lesions.

Methods: We investigated whether anthocyanin antioxidants added daily to the drinking water could affect CAG repeat instability in several organs and behaviour in R6/1 HD mice. In addition, anthocyanin-treated and untreated R6/1 HD mice at 22 weeks of age were tested in the open field test and on the rotarod.

Results: Anthocyanin-treated R6/1 HD mice showed reduced instability index in the ears and in the cortex compared to untreated R6/1 mice, and no difference in liver and kidney. There were no significant differences in any of the parameters tested in the behavioural tests among anthocyanin-treated and untreated R6/1 HD mice.

Conclusions: Our results indicate that continuous anthocyanin-treatment may have modest effects on CAG repeat instability in the ears and the cortex of R6/1 mice. More studies are required to investigate if anthocyanin-treatment could affect behaviour earlier in the disease course.

Background: Huntington disease (HD) is a genetic neurodegenerative disease leading to progressive motor, cognitive, and behavioral decline. Subtle changes in these domains are detectable up to 15 years before a definitive motor diagnosis is made. This period, called prodromal HD, provides an opportunity to examine lifestyle behaviors that may impact disease progression. Theoretical Framework: Physical activity relates to decreased rates of brain atrophy and improved cognitive and day-to-day functioning in Alzheimer disease and healthy aging populations. Previous research has yielded mixed results regarding the impact of physical activity on disease progression in HD and paid little attention to the prodromal phase.

Methods: We conducted analyses of associations among current physical activity level, current and retrospective rate of change for hippocampus and striatum volume, and cognitive, motor, and day-to-day functioning variables. Participants were 48 gene-expanded cases with prodromal and early-diagnosed HD and 27 nongene-expanded control participants. Participants wore Fitbit Ultra activity monitors for three days and completed the self-reported International Physical Activity Questionnaire (IPAQ). Hippocampal and striatal white matter volumes were measured using magnetic resonance imaging. Cognitive tests included the Stroop Color and Word Test, and the Symbol Digit Modalities Test (SDMT). Motor function was assessed using the Unified Huntington’s Disease Rating Scale total motor score (TMS). Day-to-day functioning was measured using the World Health Organization Disability Assessment Schedule (WHODAS) version 2.0.

Results: Higher Fitbit activity scores were significantly related to better scores on the SDMT and WHODAS in case participants but not in controls. Fitbit activity scores tracked better with TMS scores in the group as a whole, though the association did not reach statistical significance in the case participants. Higher Fitbit activity scores related to less day-to-day functioning decline in retrospective slope analyses. Fitbit activity scores did not differ significantly between cases and controls.

Conclusions: This is the first known study examining the associations between activity level and imaging, motor, cognitive, and day-to-day functioning outcomes in prodromal and early HD. Preliminary results suggest physical activity positively correlates with improved cognitive and day-to-day functioning and possibly motor function in individuals in the prodromal and early phase of the condition.

Huntington disease (HD) is caused by the CAG (Q) expansion in exon 1 of the IT15 gene encoding a polyglutamine (poly-Q) stretch of the Huntingtin protein (Htt). In the wild type protein, the repeats specify a stretch of up 34 Q in the N-terminal portion of Htt. In the pathological protein (mHtt) the poly-Q tract is longer. Proteolytic cleavage of the protein liberates an N-terminal fragment containing the expanded poly-Q tract becomes harmful to cells, in particular to striatal neurons. The fragments cause the transcriptional dysfunction of genes that are essential for neuronal survival. Htt, however, could also have non-transcriptional effects, e.g. it could directly alter Ca2+ homeostasis and/or mitochondrial morphology and function. Ca2+ dyshomeostasis and mitochondrial dysfunction are considered important in the molecular aetiology of the disease. Here we have analyzed the effect of the overexpression of Htt fragments (18Q, wild type form, wtHtt and 150Q mutated form, mHtt) on Ca2+ homeostasis in striatal neuronal precursor cells (Q7/7). We have found that the transient overexpression of the Htt fragments increases Ca2+ transients in the mitochondria of cells stimulated with Ca2+-mobilizing agonists. The bulk Ca2+ transients in the cytosol were unaffected, but the Ca2+ content of the endoplasmic reticulum was significantly decreased in the case of mHtt expression. To rule out possible transcriptional effects due to the presence of mHtt, we have measured the mRNA level of a subunit of the respiratory chain complex II, whose expression is commonly altered in many HD models. No effects on the mRNA level was found suggesting that, in our experimental condition, transcriptional action of Htt is not occurring and that the effects on Ca2+ homeostasis were dependent to non-transcriptional mechanisms.