Biology subjects

Cloix, C.

Publications and source records attributed to Cloix, C..

5 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↗

bioRxiv2023

Mitochondrial outer membrane integrity regulates a ubiquitin-dependent NF-κB inflammatory response

Mitochondria are often essential for apoptosis through mitochondrial outer membrane permeabilization (MOMP). This central event enables cytochrome c release leading to caspase activation and rapid cell death. Recently, MOMP has been shown to be inherently pro-inflammatory, for instance, by enabling mitochondrial DNA-dependent activation of cGAS-STING signalling. Alongside having emerging functions in health and disease, MOMP associated inflammation can also elicit anti-tumour immunity. Nonetheless, how MOMP triggers inflammation and how the cell counteracts this remains poorly defined. We find that upon MOMP, mitochondria are ubiquitylated in a promiscuous manner targeting proteins localised to both inner and outer mitochondrial membranes. Mitochondrial ubiquitylation serves to recruit the essential adaptor molecule, NEMO, leading to activation of pro-inflammatory NF-{kappa}B signalling. We find that disruption of mitochondrial outer membrane integrity through different means leads to engagement of a similar pro-inflammatory signalling platform. Thus, mitochondrial integrity directly controls inflammation, such that permeabilised mitochondria initiate NF-{kappa}B signalling. This event may be important for the various pathophysiological functions of MOMP-associated inflammation.

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

Increased apoptotic priming of glioblastoma enables therapeutic targeting by BH3-mimetics

IDH wild-type glioblastoma (GBM) is the most prevalent malignant primary brain tumour in adults. GBM typically has a poor prognosis, mainly due to a lack of effective treatment options leading to tumour persistence or recurrence. Tackling this, we investigated the therapeutic potential of targeting anti-apoptotic BCL-2 proteins in GBM. Levels of anti- apoptotic BCL-xL and MCL-1 were consistently increased in GBM compared with non- malignant cells and tissue. Moreover, we found that relative to their differentiated counterparts, patient-derived GBM stem-like cells also displayed higher expression of anti- apoptotic BCL-2 family members. Surprisingly, high anti-apoptotic BCL-xL and MCL-1 expression correlated with heightened susceptibility of GBM to BCL-2 family protein- targeting BH3-mimetics. This is indicative of increased apoptotic priming. Indeed, GBM displayed an obligate requirement for MCL-1 expression in both tumour development and maintenance. Investigating this apoptotic sensitivity, we found that sequential inhibition of BCL-xL and MCL-1 led to robust anti-tumour responses in vivo, in the absence of overt toxicity. These data demonstrate that BCL-xL and MCL-1 pro-survival function is a fundamental prerequisite for GBM survival that can be therapeutically exploited by BH3- mimetics.

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↗