No abstract

Huntington’s disease (HD) is a neurodegenerative disorder caused by a CAG trinucleotide repeat expansion in the HTT gene for which no therapies are available. HTT mutation causes protein misfolding and aggregation, preferentially affecting medium spiny neurons (MSNs) of the basal ganglia. Transcriptional perturbations in synaptic genes and neuroinflammation are key processes that precede MSN dysfunction and motor symptom onset. Understanding the interplay between these processes is crucial to develop effective therapeutic strategies to treat HD. We investigated the role of protein kinase CK2α’, a kinase upregulated in MSNs in HD and previously associated with Parkinson’s disease (PD), in the regulation of neuroinflammation and synaptic function in HD. We used the heterozygous knock-in zQ175 HD mouse model and compared that to zQ175 mice lacking one allele of CK2α’ (zQ175:CK2α’(±)). CK2α’ haploinsufficiency in zQ175 mice resulted in decreased levels of pro-inflammatory cytokines, HTT aggregation, astrogliosis and transcriptional alterations of synaptic genes related to glutamatergic signaling. zQ175:CK2α’(±) mice also presented increased frequency of striatal miniature excitatory postsynaptic currents (mEPSCs), an indicator of synaptic activity, and improved motor coordination compared to zQ175 mice. Neuropathological and phenotypic changes mediated by CK2α’ were connected to alpha-synuclein (α-syn) dysregulation and correlated with differences in α-syn serine 129 phosphorylation (pS129-α-syn), a post-translational modification involved in α-synucleinopathy and shown to be regulated by CK2 in PD. pS129-α-syn was increased in the nuclei of MSNs in zQ175 mice and in the striatum of patients with HD, and it decreased in zQ175:CK2α’(±) mice. Collectively, our data established a novel connection between CK2α’, neuroinflammation and synaptic gene dysregulation with synucleinopathy in HD and suggested common molecular mechanisms of neurodegeneration between HD and PD. Our results also support CK2α’ inhibition as a potential therapeutic strategy to modulate neuronal function and neuroprotection in HD.

Purpose The primary goal of this study was to investigate whether chronic exposures to ultra‐high B0 fields can induce long‐term cognitive, behavioral, or biological changes in C57BL/6 mice. Methods C57BL/6 mice were chronically exposed to 10.5‐T or 16.4‐T magnetic fields (3‐h exposures, two exposure sessions per week, 4 or 8 weeks of exposure). In vivo single‐voxel 1H magnetic resonance spectroscopy was used to investigate possible neurochemical changes in the hippocampus. In addition, a battery of behavioral tests, including the Morris water‐maze, balance‐beam, rotarod, and fear‐conditioning tests, were used to examine long‐term changes induced by B0 exposures. Results Hippocampal neurochemical profile, cognitive, and basic motor functions were not impaired by chronic magnetic field exposures. However, the balance‐beam–walking test and the Morris water‐maze testing revealed B0‐induced changes in motor coordination and balance. The tight‐circling locomotor behavior during Morris water‐maze tests was found as the most sensitive factor indexing B0‐induced changes. Long‐term behavioral changes were observed days or even weeks subsequent to the last B0 exposure at 16.4 T but not at 10.5 T. Fast motion of mice in and out of the 16.4‐T magnet was not sufficient to induce such changes. Conclusion Observed results suggest that the chronic exposure to a magnetic field as high as 16.4 T may result in long‐term impairment of the vestibular system in mice. Although observation of mice may not directly translate to humans, nevertheless, they indicate that studies focused on human safety at very high magnetic fields are necessary.

Huntington′s Disease (HD) is a neurodegenerative disorder caused a polyglutamine expansion in the HTT protein. This mutation causes HTT misfolding and aggregation, preferentially affecting neurons of the basal ganglia. Other aggregation-prone proteins like alpha-synuclein (α-syn), mostly associated with Parkinson′s disease (PD), has recently been involved in motor deficits in HD, but its mechanism of action is unknown. Here we showed that α-syn serine 129 phosphorylation (α-syn-pS129), a posttranslational modification linked to α-synucleinopathy, is highly phosphorylated in the brain of symptomatic zQ175 HD mice. We demonstrated that such phosphorylation is mediated by Protein Kinase CK2 alpha prime (CK2α′), which is preferentially induced in striatal neurons in HD. Knocking out one allele of CK2α′ in zQ175 mice decreased α-syn-pS129 in the striatum and ameliorated several HD-like symptoms including neuroinflammation, transcriptional alterations, excitatory synaptic transmission dysfunction and motor deficits. Our data suggests CK2α′-mediated synucleinopathy as a key molecular mechanism for striatal neurons degeneration in HD.

Spinocerebellar ataxia type 1 (SCA1) is a lethal, autosomal dominant neurodegenerative disease caused by a polyglutamine expansion in the ATAXIN-1 (ATXN1) protein. Preclinical studies demonstrate the therapeutic efficacy of approaches that target and reduce Atxn1 expression in a non-allele-specific manner. However, studies using Atxn1 −/− mice raise cautionary notes that therapeutic reductions of ATXN1 might lead to undesirable effects such as reduction in the activity of the tumor suppressor Capicua (CIC), activation of the protease β-secretase 1 (BACE1) and subsequent increased amyloidogenic cleavage of the amyloid precursor protein (APP), or a reduction in hippocampal neuronal precursor cells that would impact hippocampal function. Here, we tested whether an antisense oligonucleotide (ASO)-mediated reduction of Atxn1 produced unwanted effects involving BACE1, CIC activity, or reduction in hippocampal neuronal precursor cells. Notably, no effects on BACE1, CIC tumor suppressor function, or number of hippocampal neuronal precursor cells were found in mice subjected to a chronic in vivo ASO-mediated reduction of Atxn1 . These data provide further support for targeted reductions of ATXN1 as a therapeutic approach for SCA1.