Biology subjects

McGown, A.

Publications and source records attributed to McGown, A..

4 recordsLinked to original sources

bioRxiv2026

A novel pipeline for the validation of manganese chelators for the treatment of manganese overload

Manganese neurotoxicity, arising from environmental overexposure or inherited transporter disorders due to pathogenic variants in SLC30A10 and SLC39A14, leads to manganism, a debilitating Parkinsonian movement disorder. Alhtough chelation therapy can partially reverse neuropathology, current clinical practice relies on intravenous CaNa2EDTA, which is burdensome and poorly suited for long-term use. Consequently, there remains a significant unmet need for more effective, orally bioavailable chelators. This study aimed to establish and validate a pipeline for identifying and assessing novel ligands that attenuate manganese neurotoxicity and support preclinical translational development. Based on the structural features of manganese-based MRI contrast agents, we selected two chelators, N-picolyl-N,N',N'-trans-1,2-cyclohexylenediaminetriacetic acid (H3PyC3A) and ethylenediaminetetraacetic acid-benzothiazole aniline (H4EDTA-BTA), and their methyl ester derivatives, Me3PyC3A and Me4EDTA-BTA. These were evaluated in vivo using zebrafish (slc39a14U801/U801) and mouse (Slc30a10KO/KO) models of manganese overload. H3PyC3A and Me3PyC3A demonstrated greater manganese-mobilizing efficacy than CaNa2EDTA, improving locomotor behavior in slc39a14U801/U801 zebrafish. In Slc30a10KO/KO mice, intravenous administration confirmed selective in vivo chelation of excess manganese over physiological concentrations of zinc and copper. Although oral bioavailability was low (<1%), long-term oral administration of H3PyC3A modestly reduced liver and brain Mn accumulation, suggesting an added benefit of oral administration via gastrointestinal chelation. This integrated in vitro to in vivo pipeline provides a robust and scaleable approach for the development of next-generation Mn chelators. Slc39a14U801 loss-of-function zebrafish enable high throughput identification of candidate compounds while Slc30a10KO/KO mice offer a clinically relevant disease model for pharmacokinetic profiling and proof-of-concept validation.

pharmacology and toxicology↗

bioRxiv2024

Dual-targeting CRISPR-CasRx reduces C9orf72 ALS/FTD sense and antisense repeat RNAs in vitro and in vivo

The most common genetic cause of both frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS) is a G4C2 repeat expansion in intron 1 of the C9orf72 gene. This repeat expansion undergoes bidirectional transcription to produce sense and antisense repeat RNA species. Both sense and antisense-derived repeat RNAs undergo repeat-associated non-AUG translation in all reading frames to generate five distinct dipeptide repeat proteins (DPRs). Importantly, toxicity has been associated with both sense and antisense repeat-derived RNA and DPRs. This suggests targeting both sense and antisense repeat RNA may provide the most effective therapeutic strategy. The RNA-targeting CRISPR-Cas13 systems offer a promising avenue for simultaneous targeting of multiple RNA transcripts, as they mature their own guide arrays, thus allowing targeting of more than one RNA species from a single construct. We show that CRISPR-Cas13d originating from Ruminococcus flavefaciens (CasRx) can successfully reduce C9orf72 sense and antisense repeat transcripts and DPRs to background levels in HEK cells overexpressing C9orf72 repeats. CRISPR-CasRx also markedly reduced the endogenous sense and antisense repeat RNAs and DPRs in three independent C9orf72 patient-derived iPSC-neuron lines, without detectable off-target effects. To determine whether CRISPR-CasRx is effective in vivo, we treated two distinct C9orf72 repeat mouse models using AAV delivery and observed a significant reduction in both sense and antisense repeat-containing transcripts. Taken together this work highlights the potential for RNA-targeting CRISPR systems as therapeutics for C9orf72 ALS/FTD.

neuroscience↗

bioRxiv2024

RAN translation of C9ORF72-related dipeptide repeat proteins recapitulates hallmarks of motor neurone disease and identifies hypothermia as a therapeutic strategy in zebrafish

ObjectiveHexanucleotide repeat expansions in the C9orf72 gene are the most common genetic cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). A large body of evidence implicates DPRs as one of the main drivers of neuronal injury in cell and animal models. MethodsA pure repeat-associated non-AUG (RAN) translation zebrafish model of C9orf72-ALS/FTD was generated. Embryonic and adult transgenic zebrafish lysates were investigated for the presence of RAN-translated DPR species and adult-onset motor deficits. Using C9orf72 cell models as well as embryonic C9orf72-ALS/FTD zebrafish, hypothermic-therapeutic temperature management (TTM) was explored as a potential therapeutic option for C9orf72-ALS/FTD. ResultsHere we describe a pure RAN translation zebrafish model of C9orf72-ALS/FTD that exhibits significant RAN-translated DPR pathology and progressive motor decline. We further demonstrate that hypothermic-TTM results in a profound reduction in DPR species in C9orf72-ALS/FTD cell models as well as embryonic C9orf72-ALS/FTD zebrafish. InterpretationThe transgenic model detailed in this paper provides a medium throughput in vivo research tool to further investigate the role of RAN-translation in C9orf72-ALS/FTD and further understand the mechanisms that underpin neuroprotective strategies. Hypothermic-TTM presents a viable therapeutic avenue to explore in the context of C9orf72-ALS/FTD.

molecular biology↗

bioRxiv2023

The Crystal Structure of the Hsp90-LA1011 Complex and the Mechanism by which LA1011 may Improve the Prognosis of Alzheimer's Disease.

Chaperone systems play a major role in the decline of cognition and contribute to neurological pathologies such as Alzheimers disease (AD). While such a decline may occur naturally with age or with stress or trauma, the mechanisms involved have remained elusive. The current models suggest that amyloid-{beta} (A{beta}) plaque formation leads to the hyperphosphorylation of tau by a Hsp90 dependent process that triggers tau neurofibrillary tangle formation and neurotoxicity. Several co-chaperones of Hsp90 can influence the phosphorylation of tau, including FKBP51, FKBP52 and PP5. In particular elevated levels of FKBP51 occur with age and stress and are further elevated in AD. Recently, the dihydropyridine, LA1011 was shown to reduce tau pathology and amyloid plaque formation in transgenic AD mice, probably through its interaction with Hsp90 although the precise mode of action is currently unknown. Here, we present a co-crystal structure of LA1011 in complex with a fragment of Hsp90. We show that LA1011 can disrupt binding of FKBP51, which might help to rebalance the Hsp90-FKBP51 chaperone machinery and provide a favourable prognosis towards AD. Clinically, this is highly significant, as AD is generally a disease affecting older patients, where slowing of disease progression could result in AD no longer being life limiting.

molecular biology↗