Biology subjects

Tait, S. W.

Publications and source records attributed to Tait, S. W..

7 recordsLinked to original sources

bioRxiv2026

RNF213 M1-ubiquitinates damaged mitochondria to activate pro-inflammatory NF-κB signaling

Through mitochondrial outer membrane permeabilization (MOMP), mitochondria are central to apoptosis. MOMP is pro-inflammatory, impacting diverse processes including anti-tumor immunity and cellular senescence. Despite this, how damaged mitochondria activate inflammation remains unclear. Recent studies have shown that following MOMP, mitochondria are extensively ubiquitinated activating pro-inflammatory NF-{kappa}B signaling. We identify the E3 ligase, RNF213, as essential for pro-inflammatory mitochondrial ubiquitination following MOMP. RNF213 has an established role in pro- inflammatory, cell-autonomous immunity to bacteria and other pathogens. We discover that RNF213 is required for mitochondrial M1-linked (linear) ubiquitination. Interestingly, this was found to be independent of the canonical M1-ubiquitin ligase complex LUBAC. RNF213 can directly catalyze M1-linked ubiquitination. By promoting mitochondrial M1-linked ubiquitination, RNF213 initiates the recruitment of the essential NF{kappa}B adaptor molecule, NEMO, and subsequently activates pro-inflammatory NF-{kappa}B signaling. Collectively, our findings highlight striking similarities between how cells detect damaged mitochondria and intracellular pathogens, leading to inflammation.

cell biology↗

bioRxiv2025

Thiol Scarcity in Cerebrospinal Fluid Renders Leptomeningeal Acute Lymphoblastic Leukaemia Therapeutically Vulnerable to Ferroptosis

The leptomeninges present a challenging tumour microenvironment with cells receiving low levels of nutrients and oxygen from cerebrospinal fluid (CSF), however these metabolic constraints are yet to be exploited therapeutically. Central nervous system (CNS) relapse in acute lymphoblastic leukaemia (ALL) remains a formidable clinical challenge because the leptomeningeal niche restricts drug penetration and immune surveillance. Current CNS-directed treatments rely on neurotoxic intrathecal chemotherapy, underscoring the urgent need for novel targeted strategies. Here, we uncover a profound niche-specific metabolic vulnerability in CNS-resident ALL cells, characterised by an obligate reliance on LRP8-mediated selenium uptake to sustain selenocysteine biosynthesis and GPX4 activity under profound glutathione limitation. We show that scarcity of thiols and cystine in CSF creates an inherently pro-ferroptotic microenvironment. Interference with selenocysteine biosynthesis under these conditions induces synthetic lethality in both in vitro and in vivo CNS-ALL models. This vulnerability is exploitable both by genetic targeting of the selenocysteine biosynthesis pathway and, notably, through repurposing the FDA-approved agent Auranofin, which disrupts selenium utilisation, induces lipid peroxidation, and demonstrates CNS-specific anti-leukaemic eaicacy with excellent tolerability in vivo. These findings identify a novel mechanistically grounded approach, leveraging features of the unique leptomeningeal microenvironment to selectively kill invading cells, with potential implications for all leptomeningeal-tropic malignancies. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=116 SRC="FIGDIR/small/693383v1_ufig1.gif" ALT="Figure 1"> View larger version (26K): org.highwire.dtl.DTLVardef@2303dforg.highwire.dtl.DTLVardef@d357ceorg.highwire.dtl.DTLVardef@129cb26org.highwire.dtl.DTLVardef@d83183_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOGraphical Abstract:C_FLOATNO The leptomeningeal tumour microenvironment is intrinsically pro-ferroptotic due to low concentrations of free thiols and cystine in cerebrospinal fluid. ALL cells in this niche exhibit disrupted glutathione metabolism and a novel dependency on LRP8-mediated SELENOP uptake to sustain GPX4 levels and thus protect themselves from spontaneous ferroptotic cell death. Perturbation of selenocysteine biosynthesis via genetic inhibition SEPHS2 or LRP8 leads to synthetic lethality in leukaemic cells exposed to CSF in vitro and in vivo - an effect phenocopied by use of Auranofin. C_FIG

cancer biology↗

bioRxiv2024

Large transient assemblies of Apaf1 constitute the apoptosome in cells

Upon cell death signals, the apoptotic protease-activating factor Apaf1 and cytochrome c interact to form the apoptosome complex. The apoptosome is crucial for mitochondrial apoptosis, as it activates caspases that dismantle the cell. However, the assembly mechanism and appearance of the apoptosome in vivo remain unclear. We show that upon onset of apoptosis, Apaf1 molecules accumulate into multiple foci per cell. Disassembly of the foci is linked to survival of the cell. Structurally, Apaf1 foci resemble organelle-sized, cloud-like assemblies. Foci form upon specific molecular interactions with cytochrome c and depending on procaspase-9. We propose that Apaf1 foci correspond to the apoptosome in cells. Transientness and ultrastructure of Apaf1 foci suggest that the dynamic spatiotemporal organisation of apoptosome components regulates progression of apoptosis.

cell biology↗

bioRxiv2021

Mitochondrial dynamics regulate genome stability via control of caspase-dependent DNA damage

Mitochondrial dysfunction is interconnected with cancer. Nevertheless, how defective mitochondria promote cancer is poorly understood. We find that mitochondrial dysfunction promotes DNA damage under conditions of increased apoptotic priming. Underlying this process, we reveal a key role for mitochondrial dynamics in the regulation of DNA damage and genome instability. The ability of mitochondrial dynamics to regulate oncogenic DNA damage centres upon the control of minority MOMP, a process that enables non-lethal caspase activation leading to DNA damage. Mitochondrial fusion suppresses minority MOMP, and its associated DNA damage, by enabling homogenous mitochondrial expression of anti-apoptotic BCL-2 proteins. Finally, we find that mitochondrial dysfunction inhibits pro-apoptotic BAX retrotranslocation, causing BAX mitochondrial localization thereby promoting minority MOMP. Unexpectedly, these data reveal oncogenic effects of mitochondrial dysfunction that are mediated via mitochondrial dynamics and caspase-dependent DNA damage.

cell biology↗

bioRxiv2021

Confined migration promotes cancer metastasis through resistance to anoikis and increased invasiveness

Mechanical stress is known to fuel several hallmarks of cancer, ranging from genome instability to uncontrolled proliferation or invasion. Cancer cells are constantly challenged by mechanical stresses not only in the primary tumour but also during metastasis. However, this latter has seldom been studied with regards to mechanobiology, in particular resistance to anoikis, a cell death programme triggered by loss of cell adhesion. Here, we show in vitro that migrating breast cancer cells develop resistance to anoikis following their passage through microporous membranes mimicking confined migration (CM), a mechanical constriction that cancer cells encounter during metastasis. This CM-induced resistance was mediated by Inhibitory of Apoptosis Proteins (IAPs), and sensitivity to anoikis could be restored after their inhibition using SMAC mimetics. Anoikis-resistant mechanically-stressed cancer cells displayed enhanced cell motility and evasion from natural killer cell-mediated immune surveillance, as well as a marked advantage to form lung metastatic lesions in mice. Our findings reveal that CM increases the metastatic potential of breast cancer cells.

cancer biology↗

bioRxiv2020

Quantitative in vivo bioluminescence imaging of orthotopic patient-derived glioblastoma xenografts

Despite extensive research, little progress has been made in glioblastoma therapy, owing in part to a lack of adequate preclinical in vivo models to study this disease. To mitigate this, primary patient-derived cell lines, which maintain their specific stem-like phenotypes, have replaced established glioblastoma cell lines. However, due to heterogenous tumour growth inherent in glioblastoma, the use of primary cells for orthotopic in vivo studies often requires large experimental group sizes. Therefore, when using intracranial patient-derived xenograft (PDX) approaches, it is advantageous to deploy imaging techniques to monitor tumour growth and allow stratification of mice. Here we show that stable expression of near-infrared fluorescent protein (iRFP) in patient-derived glioblastoma cells enables rapid direct non-invasive monitoring of tumour development without compromising tumour stemness or tumorigenicity. Moreover, as this approach does not depend on the use of agents like luciferin, which can cause variability due to changing bioavailability, it can be used for quantitative longitudinal monitoring of tumour growth. Notably, we show that this technique also allows quantitative assessment of tumour burden in highly invasive models spreading throughout the brain. Thus, iRFP transduction of primary patient-derived glioblastoma cells is a reliable, cost- and time-effective way to monitor heterogenous orthotopic PDX growth.

cancer biology↗

bioRxiv2020

Monocytes mediate Salmonella Typhimurium-induced tumour growth inhibition

The use of bacteria as an alternative cancer therapy has been re-investigated in recent years. A number of bacterial strains for this purpose have been generated, one of which is SL7207: an auxotrophic Salmonella enterica serovar Typhimurium aroA mutant with immune-stimulatory potential. Here we show that systemic administration of SL7207 induces melanoma tumour growth arrest in vivo, with greater survival of the SL7207-treated group compared to control PBS-treated mice. Administration of SL7207 is accompanied by a change in the immune phenotype of the tumour-infiltrating cells towards pro-inflammatory, with expression of the TH1 cytokines IFN-{gamma}, TNF-, and IL-12 significantly increased. Interestingly, Ly6C+MHCII+ monocytes were recruited to the tumours following SL7207 treatment and were pro-inflammatory. Accordingly, the abrogation of these infiltrating monocytes using clodronate liposomes prevented SL7207-induced tumour growth inhibition. These data demonstrate a previously unappreciated role for infiltrating inflammatory monocytes underlying bacterial-mediated tumour growth inhibition. This information highlights a novel role for monocytes in controlling tumour growth, contributing to our understanding of the immune responses required for successful immunotherapy of cancer.

immunology↗