Biology subjects

Frechin, M.

Publications and source records attributed to Frechin, M..

3 recordsLinked to original sources

bioRxiv2023

Dynamic label-free analysis of SARS-CoV-2 infection reveals virus-induced subcellular remodeling.

Assessing the impact of SARS-CoV-2 on organelle dynamics allows a better understanding of the mechanisms of viral replication. We combine label-free holo-tomographic microscopy (HTM) with Artificial Intelligence (AI) to visualize and quantify the subcellular changes triggered by SARS-CoV-2 infection. We study the dynamics of shape, position and dry mass of nucleoli, nuclei, lipid droplets (LD) and mitochondria within hundreds of single cells from early infection to syncytia formation and death. SARS-CoV-2 infection enlarges nucleoli, perturbs LD, changes mitochondrial shape and dry mass, and separates LD from mitochondria. We then used Bayesian statistics on organelle dry mass states to define organelle cross-regulation (OCR) networks and report modifications of OCR that are triggered by infection and syncytia formation. Our work highlights the subcellular remodeling induced by SARS-CoV-2 infection and provides a new AI-enhanced, label-free methodology to study in real-time the dynamics of cell populations and their content.

cell biology↗

bioRxiv2023

Targeting BTN2A1 enhances Vγ9Vδ2 T cell effector functions and triggers tumor cells pyroptosis

V{gamma}9V{delta}2 T cells are potent but elusive cytotoxic effectors. Means to stimulate their function could lead to powerful new cancer immunotherapies. BTN2A1, a surface protein has recently been shown to bind the V{gamma}9 chain of the {gamma}{delta} TCR but its precise role in modulating V{gamma}9V{delta}2 T cells functions remains unknown. Here we show that 107G3B5, a monoclonal anti-BTN2A1 agonist antibody, significantly enhances V{gamma}9V{delta}2 T cell functions against hematological or solid cell lines and against primary cells from adult acute lymphoblastic leukemia patients. New computer vision strategies applied to holotomographic microscopy videos show that 107G3B5 enhances the interaction between V{gamma}9V{delta}2 T cells and target cells in a quantitative and qualitative manner. In addition, we provide evidence that V{gamma}9V{delta}2 T cells activated by 107G3B5 induce caspase 3/7 activation in tumor cells, thereby triggering their death by pyroptosis. We thus demonstrate that targeting BTN2A1 with 107G3B5 enhances the V{gamma}9V{delta}2 T cell antitumor response by triggering the pyroptosis-induced immunogenic cell death.

cancer biology↗

bioRxiv2018

Label free 3D analysis of organelles in living cells by refractive index shows pre-mitotic organelle spinning in mammalian stem cells

Holo-tomographic microscopy (HTM) is a label-free non-phototoxic microscopy method reporting the fine changes of a cells refractive indexes (RI) in 3D. By combining HTM with epifluorescence, we demonstrate that cellular organelles such as Lipid droplets and mitochondria show a specific RI signature that distinguishes them with high resolution and contrast. We further show that HTM allows to follow in unprecedented ways the dynamics of mitochondria, lipid droplets as well as that of endocytic structures in live cells over long period of time, which led us to observe to our knowledge for the first time a global organelle spinning occurring before mitosis.

cell biology↗