Brown, T. G. | bioRxiv Science

bioRxiv2021

Peroxide antimalarial drugs target redox homeostasis in Plasmodium falciparum infected red blood cells

Plasmodium falciparum causes the most lethal form of malaria. Peroxide antimalarials based on artemisinin underpin the frontline treatments for malaria, but artemisinin resistance is rapidly spreading. Synthetic peroxide antimalarials, known as ozonides, are in clinical development and offer a potential alternative. Here, we used chemoproteomics to investigate the protein alkylation targets of artemisinin and ozonide probes, including an analogue of the ozonide clinical candidate, artefenomel. We greatly expanded the list of protein targets for peroxide antimalarials and identified significant enrichment of redox-related proteins for both artemisinins and ozonides. Disrupted redox homeostasis was confirmed by dynamic live imaging of the glutathione redox potential using a genetically encoded redox-sensitive fluorescence-based biosensor. Targeted LC-MS-based thiol metabolomics also confirmed changes in cellular thiol levels. This work shows that peroxide antimalarials disproportionately alkylate proteins involved in redox homeostasis and that disrupted redox processes are involved in the mechanism of action of these important antimalarials. ImportanceThe frontline treatments for malaria are combination therapies based on the peroxide antimalarial, artemisinin. Concerningly, artemisinin resistance has emerged in malaria-endemic regions, and now poses a major threat to malaria treatment and eradication efforts. New medicines are urgently required to replace the artemisinins, and some of the most advanced candidates are the fully synthetic peroxide antimalarials, OZ277 (arterolane) and OZ439 (artefenomel). The mechanism of action of peroxide antimalarials involves the reductive activation of the peroxide bond by intra-parasitic haem, but there is no consensus regarding the specific protein targets of the resulting radical species for artemisinins and/or the ozonides. This study provides a comprehensive and unbiased chemoproteomic profile of over 400 target proteins, and confirms the specific impact of peroxide antimalarials on redox metabolism. The key role of redox targets is particularly relevant considering that the mechanism of artemisinin resistance appears to involve modulation of peroxide activation and redox homeostasis.

pharmacology and toxicology↗

bioRxiv2020

Protein kinase CK2 alpha prime and alpha-synuclein constitute a key regulatory pathway in Huntington's disease

BackgroundHuntingtons Disease (HD) is a neurodegenerative disorder caused by a CAG trinucleotide repeat expansion in the HTT gene for which no therapies are available. This mutation causes HTT 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 whether protein kinase CK2, a kinase upregulated in MSNs in HD and previously associated with Parkinsons disease (PD), participates in the regulation of neuroinflammation and synaptic function during HD progression. MethodsWe used the heterozygous knock-in zQ175 HD mouse model and compared that to zQ175 mice lacking one allele of CK2. We performed neuropathological analyses using immunohistochemistry, cytokine proteome profiling, RNA-seq analyses in the striatum, electrophysiological recordings, and behavioral analyses. We also used the murine immortalized striatal cell lines STHdhQ7 and STHdhQ111 and studied the expression of various synaptic genes dysregulated by CK2. ResultsWe showed that CK2 haploinsufficiency in zQ175 mice ameliorated neuroinflammation, HTT aggregation, transcriptional alterations, excitatory synaptic transmission, and motor coordination deficits. RNA-seq analyses also revealed a connection between -syn, a protein associated with PD, and the transcriptional perturbations mediated by CK2 in HD. We also found increased -syn serine 129 phosphorylation (pS129--syn), a post-translational modification linked to -synucleinopathy, in the nuclei of MSNs in zQ175 mice and in patients with HD. Levels of pS129--syn were ameliorated in zQ175 lacking one allele of CK2. ConclusionsOur data demonstrated that CK2 contributes to transcriptional dysregulation of synaptic genes and neuroinflammation in zQ175 mice and its depletion improved several HD-like phenotypes in this mouse model. These effects were related to increased phosphorylation of S129--syn in the striatum of HD mice, suggesting that CK2 contributes to worsening HD by mediating synucleinopathy. Our study highlights a possible convergent mechanism of neurodegeneration between HD and PD and suggests targeting CK2 as a potential therapeutic strategy to ameliorate synaptic dysfunction in HD as well as other neurodegenerative diseases.

neuroscience↗