Biology subjects

Leray, I.

Publications and source records attributed to Leray, I..

4 recordsLinked to original sources

bioRxiv2026

MMRi62 induces iron depletion-driven apoptosis through a ferritin-independent mechanism

The modulation of iron metabolism is increasingly explored as a therapeutic strategy in cancer, particularly through the induction of ferroptosis. Given the central role of ferritin as a major intracellular iron buffer, targeting ferritin represents an attractive strategy to disrupt iron homeostasis; however, the lack of pharmacological approaches capable of selectively targeting ferritin currently limits the therapeutic exploitation of this vulnerability. MMRi62, initially developed to target the MDM2-MDM4 axis, has been proposed to induce ferroptosis via ferritin degradation. Here, we revisited this hypothesis in the context of medulloblastoma (MB). Contrary to this proposed mechanism, we found that MMRi62 does not trigger ferroptosis but instead induces robust apoptotic cell death. This effect is observed in both p53-mutant DAOY and p53 wild-type HD-MB03 cells, as well as in c-Myc/OTX2-driven medulloblastoma-like tumours genetically induced in brain organoids. Although ferritin degradation occurs upon treatment, genetic dissection demonstrates that neither ferritin itself nor ferritinophagy are required for MMRi62-induced cytotoxicity. Together, these findings rule out ferritin-dependent mechanisms as primary drivers of cytotoxicity. Instead, we uncovered that MMi62 induces a profound rewiring of iron metabolism consistent with a canonical iron starvation response, accompanied by a marked reduction in intracellular iron levels. Consistently, the UV-visible spectroscopic data were in agreement with the proposed iron-chelating properties of MMRi62. Taken together, our findings identify iron depletion-driven apoptosis, rather than ferroptosis, independently of ferritin degradation, as the primary mechanism of MMRi62 cytotoxicity in MB, refining its mode of action and highlighting iron homeostasis as a therapeutic vulnerability.

cancer biology↗

bioRxiv2025

Glutaminolysis Fuels Reactive Astrocytes, Exacerbating Amyloid Pathology in Alzheimer's Disease.

Amyloid-{beta} (A{beta}) plaques with progressively increasing reactive astrocytes characterize Alzheimers disease (AD). Reactive astrocytes are regulated by cellular and molecular mechanisms that are known to progress A{beta} pathology. However, the metabolic adaptation and metabolites required to fuel these molecular changes in reactive astrocytes remain unknown. Using human AD samples, in vivo amyloid mouse models, and in vitro approaches, we demonstrate that reactive astrocytes utilize glutamine to fuel anaplerosis and meet their metabolic demands, thereby progressing amyloidosis. We show that reactive astrocytes increase Na+-coupled neutral amino acid transporters for glutamine uptake that are interdependent on Na+/K+ ATPase. Furthermore, increasing brain-glutamine levels with a high-glutamine diet exacerbated reactive astrocytes, increasing A{beta} burden in an amyloid mouse model. We demonstrate that glutamine undergoes glutaminolysis via glutaminase-2/glutamate dehydrogenase-1 enzymes to be incorporated into TCA metabolites for anaplerosis. Pharmacologically or genetically blocking glutaminolysis reduces reactive astrocytes and decreases A{beta} pathology in an amyloid mouse. Our findings reveal the first glutamine-dependent metabolic adaptation of reactive astrocytes affecting A{beta} pathology, which may be harnessed for AD therapeutic strategies.

neuroscience↗

bioRxiv2021

Highly Efficient Knockin in Human iPS Cells and Rat Embryos by CRISPR/Cas9 Molecular Optimization

The CRISPR/Cas9 system is now the gold standard for the generation of genetically modified cell and animal models but knockin is a bottleneck. One reason could be that there is no consensus regarding the concentrations of its components to be used. Here, we defined optimal Cas9 protein, guide RNA and short donor DNA concentrations on a GFP to BFP conversion model of human induced pluripotent stem cells and point mutations on rat transgenic embryos. With a molecular rational approach of the CRISPR/Cas9 system and study of ribonucleoprotein complex formation by nanodifferential scanning fluorimetry, we defined that Cas9/guide RNA 1/1 molar ratio with 0.2M and 0.4M of Cas9, coupled with 2M of ssODN are sufficient for optimal and high knockin frequencies in rat embryos and human induced pluripotent stem cells, respectively. These optimal conditions use lower concentrations of CRISPR reagents to form the RNP complex than most conditions published while achieving 50% of knockin. This study allowed us to reduce costs and toxicity while improving editing and knockin efficacy on two particularly key models to mimic human diseases.

bioengineering↗

bioRxiv2020

Physiological synaptic activity and recognition memory are fueled by astroglial glutamine

Presynaptic glutamate replenishment is fundamental to brain function. In high activity regimes, such as epileptic episodes, this process is thought to rely on the glutamate-glutamine cycle between neurons and astrocytes. However the presence of an astroglial glutamine supply, as well as its functional relevance in vivo in the healthy brain remain controversial, partly due to a lack of tools that can directly examine glutamine transfer. Here, we generated a novel fluorescent probe that tracks glutamine in live cells, which provided direct visual evidence of an activity-dependent glutamine supply from astroglial networks to presynaptic structures under physiological conditions. This mobilization is mediated by connexin43, an astroglial protein with both gap-junction and hemichannel functions, and is essential for synaptic transmission and object recognition memory. Our findings uncover an indispensable recruitment of astroglial glutamine in physiological synaptic activity and memory via an unconventional pathway, thus providing an astrocyte basis for cognitive processes.

neuroscience↗