Biology subjects

Jacotot, E. D.

Publications and source records attributed to Jacotot, E. D..

4 recordsLinked to original sources

bioRxiv2026

Centrosome architecture and m6A-dependent gating of p53 surveillanceafter whole-genome doubling

Whole-genome doubling (WGD) generates a tetraploid state that challenges cellular homeostasis and is strongly selected against in TP53-proficient contexts. Although centrosome amplification serves as a structural correlate of genome doubling, how centrosomal features engage and sustain p53 surveillance remains incompletely understood. Here, we develop a genetically encoded MDM2-based fluorescent reporter to monitor Caspase-2 pathway activation in living cells after WGD. Combining pharmacological profiling and genome-wide CRISPR screening, we uncover a multi-layered regulation of p53 responses. We identify PLK1-dependent centriole maturation and subdistal appendage integrity as architectural determinants of PIDDosome-dependent Caspase-2 activation, independent of distal appendage assembly. We show that upon WGD, Caspase-2-mediated cleavage of MDM2 reshapes the p53-MDM2 regulatory loop, enabling sustained p53 signaling. This sustained output depends on the catalytic activity of METTL3 and associated m6A writer proteins. Together, these findings demonstrate that centrosome architecture and epitranscriptomic regulation cooperate to shape p53 surveillance after genome doubling. HighlightsO_LIWhole-genome doubling creates a surveillance state sensed by centrosome cluster architecture. C_LIO_LICaspase-2 activation converts the p53-MDM2 loop from negative to positive feedback. C_LIO_LIm6A methylation establishes competence of the p53 module for sustained output. C_LIO_LIA genetically encoded biosensor enables functional dissection of this circuit. C_LI

cell biology↗

bioRxiv2024

The PIDDosome controls cardiomyocyte polyploidization during postnatal heart development

The adult mammalian heart is characterized by post-mitotic polyploid cardiomyocytes (CMs). Understanding how CMs regulate cell cycle exit and ploidy can help developing new heart regenerative therapies. Here, we uncover that the PIDDosome, a multi-protein complex activating the endopeptidase Caspase-2, helps to implement a CM-specific differentiation program that limits ploidy during postnatal heart development. DNA content analyses show that PIDDosome-loss causes a cell-autonomous increase in nuclear and cellular CM ploidy. Remarkably, increased ploidy does not affect cardiac structure nor function. PIDDosome-imposed ploidy restriction commences at postnatal day 7 (P7), reaching a plateau on P14. PIDDosome activation requires ANKRD26, targeting PIDD1 to mother centrioles. Opposite to prior observations in liver development, the PIDDosome limits CM polyploidization in a p53-independent manner but reliant on p21/Cdkn1a, a notion supported by nuclear RNA sequencing and genetic deletion experiments. Our results provide new insights how proliferation of polyploid CMs is restricted during postnatal heart development.

developmental biology↗

bioRxiv2024

Caspase-2 kills cells with extra centrosomes

Centrosomes are membrane-less organelles that orchestrate a wide array of biological functions by acting as microtubule organizing centers. Here, we report that caspase-2-driven apoptosis is elicited in blood cells failing cytokinesis and that extra centrosomes are necessary to trigger this cell death. Activation of caspase-2 depends on the PIDDosome multi-protein complex and priming of PIDD1 at extra centrosomes is necessary for this pathway. Accordingly, loss of its centrosomal adapter, ANKRD26, allows for cell survival and unrestricted polyploidization in response to cytokinesis failure. Mechanistically, cell death is initiated upstream of mitochondria via caspase-2-mediated processing of the BCL2 family protein BID, driving BAX/BAK-dependent mitochondrial outer membrane permeabilization (MOMP). Remarkably, BID-deficient cells enforce apoptosis by engaging p53-dependent pro-apoptotic transcriptional responses initiated by caspase-2. Consistently, BID and MDM2 act as shared caspase-2 substrates, with BID being kinetically favored. Our findings document that the centrosome limits its own unscheduled duplication by the induction of PIDDosome-driven mitochondrial apoptosis to avoid potentially pathogenic polyploidization events.

cell biology↗

bioRxiv2021

Genuine Selective Caspase-2 Inhibition with new Irreversible Small Peptidomimetics

Caspase-2 (Casp2) is a promising therapeutic target in several human diseases including nonalcoholic steatohepatitis (NASH) and Alzheimers disease (AD). However, the design of active-site-directed inhibitor selective to individual caspase family members is challenging because caspases have extremely similar active sites. Here we present new peptidomimetics derived from the VDVAD pentapeptide structure, harboring non-natural modifications at the P2 position and an irreversible warhead. Enzyme kinetics shows that these new compounds, such as LJ2 or its specific isomer LJ2a, and LJ3a, strongly and irreversibly inhibit Casp2 with genuine selectivity. According to Casp2 role in cellular stress responses, LJ2 inhibits cell death induced by microtubule destabilization or hydroxamic acid-based deacetylase inhibition. The most potent peptidomimetic, LJ2a, inhibits human Casp2 with a remarkably high inactivation rate (k3/Ki ~ 5 500 000 M-1s-1) and the most selective inhibitor, LJ3a, has a near to 1000 times higher inactivation rate on Casp2 as compared to Casp3. Structural analysis of LJ3a shows that spatial configuration of C at the P2 position determines inhibitor efficacy. In transfected human cell lines overexpressing site-1 protease (S1P), sterol regulatory element-binding protein 2 (SREBP2) and Casp2, LJ2a and LJ3a fully inhibit SREBP2 activation, suggesting a potential to prevent NASH development. Furthermore, in primary hippocampal neurons treated with {beta}-amyloid oligomers, submicromolar concentrations of LJ2a and of LJ3a prevent synapse loss, indicating a potential for further investigations in AD treatment.

pharmacology and toxicology↗