Biology subjects

Theart, R. P.

Publications and source records attributed to Theart, R. P..

5 recordsLinked to original sources

bioRxiv2026

Modeling the cell biology of PEX11β deficiency during human neurogenesis

Peroxisomes are highly specialized organelles that are important for various metabolic functions, including {beta}-oxidation of very-long-chain fatty acids and the synthesis of plasmalogens. Mutations in peroxisomal biogenesis proteins cause Zellweger spectrum disorders (ZSD), rare multisystem disorders often associated with neurological phenotypes. Unlike other peroxisome biogenesis proteins, PEX11{beta} regulates peroxisomal fission, and PEX11{beta} mutations result in milder metabolic phenotypes but persistent neurodevelopmental abnormalities, suggesting a role for PEX11{beta} in neurodevelopment. To model PEX11{beta} deficiency during human neurogenesis, we generated PEX11{beta} knockout human iPSCs and differentiated them into neural progenitors and neural rosettes. PEX11{beta} loss caused elongated peroxisomal morphology, reduced fission, and impaired recruitment of fission proteins, without affecting mitochondrial morphology or respiration. Elongated peroxisomal morphology was independent of the peroxisome-endoplasmic reticulum tether. Lipidomic analysis revealed reduced ether-linked phospholipids in PEX11{beta}-deficient neural progenitors, suggesting impaired peroxisomal function. Finally, PEX11{beta} deficiency led to increased neural rosette lumen size and neural progenitor number.

cell biology↗

bioRxiv2025

Presynaptic Actin Nanostructures: A Reproducibility Case Study

In an effort to assess the reproducibility of bioimage analyses in current publications, we took part in a Global BioImage Analysts Society (GloBIAS) initiative to try and reproduce results from published articles. We attempted to reproduce core findings from the work of Bingham et al., which investigates the actin organisation in presynaptic structures by using diffraction-limited and super-resolution microscopy. While the original paper unveiled clear biological insight, it lacked sufficient detail in the bioimage analysis methodological approach, limiting the depth of reproducibility we could achieve. Through frequent contacts with the corresponding author, we managed to replicate qualitative aspects of the analysis of actin nanostructures in bead-induced presynapses. We performed image reconstruction from super-resolution microscopy data, automatic image registration and visual inspection, followed by manual annotation of structures of interest in [~]35 images. Our experience with this exercise highlights the importance of transparent data sharing and accessibility, as well as the need to adhere to bioimage analysis standards that ensure the reproducibility of nowadays complex biological image analysis studies. It also shows how crucial interdisciplinary collaboration is, since many biology labs are simply unaware of these standards, which are often easy to implement and would likely be widely adopted if their value was better understood or known.

neuroscience↗

bioRxiv2025

Targeting Aurora kinases as essential cell cycle regulators to deliver multi-stage antimalarials against Plasmodium falciparum

Kinases that play critical roles in the development and adaptation of Plasmodium falciparum present novel opportunities for chemotherapeutic intervention. Of particular interest are mitotic kinases that regulate the proliferation of the parasites by controlling nuclear division, segregation and cytokinesis. We evaluated the potential of human Aurora kinase (Aur) inhibitors to inhibit P. falciparum development by targeting members of the Aurora-related kinase (Ark) family in this parasite. Several human AurB inhibitors exhibited multistage potency (<250 nM) against all proliferative stages of parasite development, including asexual blood stages, liver schizonts and male gametes. Among the most potent compounds, hesperadin and AT83 exhibit >1000x selectivity towards the parasite without concerns about mammalian cell toxicity. Importantly, we identified PfArk1 as the principal vulnerable Ark family member, with specific inhibition of PfArk1 as the primary target for hesperadin and the human anaplastic lymphoma kinase (ALK) inhibitor TAE684. Hesperadins whole-cell and protein activity validates it as a unique PfArk1 tool compound. Inhibition of PfArk1 results in the parasites inability to complete mitotic processes, presenting with unsegregated, multi-lobed nuclei caused by aberrant microtubule organization. This suggests that PfArk1 is the main Aur mitotic kinase in proliferative stages of Plasmodium, characterized by bifunctional AurA and B activity. This paves the way for drug discovery campaigns based on hesperadin targeting PfArk1.

molecular biology↗

bioRxiv2022

Three-dimensional mitochondrial fission, fusion and depolarisation event location prediction for a high throughput analysis of fluorescence microscopy images

This paper documents the development of a novel method to predict the occurrence and exact locations of mitochondrial fission, fusion and depolarisation events in three dimensions. These occurrence and location of these events were successfully predicted with a three-dimensional version of the Pix2Pix generative adversarial network (GAN) as well as a three-dimensional adversarial segmentation network called the Vox2Vox GAN. The Pix2Pix GAN predicted the locations of mitochondrial fission, fusion and depolarisation events with accuracies of 35.9%, 33.2% and 4.90%, respectively. Similarly, the Vox2Vox GAN achieved accuracies of 37.1%, 37.3% and 7.43%. The accuracies achieved by the networks in this paper are too low for the immediate implementation of these tools in life science research. They do however indicate that the networks have modelled the mitochondrial dynamics to some degree of accuracy and may therefore still be helpful as an indication of where events might occur if time lapse sequences are not available. The prediction of these morphological mitochondrial events have, to our knowledge, never been achieved before in literature. The results from this paper can be used as a baseline for the results obtained by future work.

cell biology↗

bioRxiv2020

Mitochondrial event localiser (MEL) to quantitatively describe fission, fusion and depolarisation in the three-dimensional space

Mitochondrial fission and fusion play an important role not only in maintaining mitochondrial homeostasis but also in preserving overall cellular viability. However, quantitative analysis based on the three-dimensional localisation of these highly dynamic mitochondrial events in the cellular context has not yet been accomplished. Moreover, it remains largely uncertain where in the mitochondrial network depolarisation is most likely to occur. We present the mitochondrial event localiser (MEL), a method that allows high-throughput, automated and deterministic localisation and quantification of mitochondrial fission, fusion and depolarisation events in large three-dimensional microscopy time-lapse sequences. In addition, MEL calculates the number of mitochondrial structures as well as their combined and average volume for each image frame in the time-lapse sequence. The mitochondrial event locations can subsequently be visualised by superposition onto the fluorescence micrograph z-stack. We apply MEL to both control samples as well as cells that have been treated with hydroxychloroquine sulphate (HCQ) and observe that fission and fusion events mostly occur around the terminal branches of the mitochondrial network, with few events detected in the strongly networked areas such as the perinuclear region. Depolarisation was most abundant in the HCQ treated samples, with the majority of the depolarisation events occurring in the cell periphery.

bioinformatics↗