Biology subjects

Lancien, M.

Publications and source records attributed to Lancien, M..

3 recordsLinked to original sources

bioRxiv2023

VRK3 depletion induces cell cycle arrest and metabolic reprogramming of Pontine Diffuse Midline Glioma (DMG)-K27 altered cells

We previously identified VRK3 as a specific vulnerability in DMG-H3K27M cells in a synthetic lethality screen targeting the whole kinome. The aim of the present study was to elucidate the mechanisms by which VRK3 depletion impact DMG-K27M cell fitness. Gene expression studies after VRK3 knockdown emphasized the inhibition of genes involved in G1/S transition of the cell cycle resulting in growth arrest in G1. Additionally, a massive modulation of genes involved in chromosome segregation was observed, concomitantly with a reduction in the level of phosphorylation of serine 10 and serine 28 of histone H3 supporting the regulation of chromatin condensation during cell division. This last effect could be partly due to a concomitant decrease of the chromatin kinase VRK1 in DMG following VRK3 knock-down. Furthermore, a metabolic switch specific to VRK3 function was observed towards increased oxidative phosphorylation without change in mitochondria content, that we hypothesized would represent a cell rescue mechanism. This study further explored the vulnerability of DMG-H3K27M cells to VRK3 depletion suggesting potential therapeutic combinations, e.g. with the mitochondrial ClpP protease activator ONC201.

cancer biology↗

bioRxiv2023

Single-cell mRNA-regulation analysis reveals cell type-specific mechanisms of type 2 diabetes

Perturbed secretion of insulin and other pancreatic islet hormones is the main cause of type 2 diabetes (T2D). The islets harbor five cell types that are potentially altered differently by T2D. Whole-islet transcriptomics and single-cell RNA-sequencing (scRNAseq) studies have revealed differentially expressed genes without reaching consensus. Here, we demonstrate that unprecedented insights into disease mechanisms can be obtained by network-based analysis of scRNAseq data. We developed differential gene coordination network analysis (dGCNA) and analyzed islet scRNAseq data from 16 T2D and 16 non-T2D individuals. dGCNA revealed T2D-induced cell type-specific networks of dysregulated genes with remarkable ontological specificity, thus allowing for a comprehensive and unbiased functional classification of genes involved in T2D. In beta cells eleven networks of genes were detected, revealing that mitochondrial electron transport chain, glycolysis, cytoskeleton organization, cell proliferation, unfolded protein response and three networks of beta cell transcription factors are perturbed, whereas exocytosis, lysosomal regulation and insulin translation programs are instead enhanced in T2D. Furthermore, we validated the ability of dGCNA to reveal disease mechanisms and predict the functional context of genes by showing that TMEM176A/B regulates the beta cell cytoskeleton and that CEPBG is a key regulator of the unfolded protein response. In addition, comparing beta- and alpha and cells, we found substantial differences, reproduced across independent datasets, confirming cell type-specific alterations in T2D. We conclude that analysis of networks of differentially coordinated genes provides outstanding insight into cell type-specific gene function and T2D pathophysiology.

cell biology↗

bioRxiv2019

Dendritic cells require TMEM176A/B ion channels for optimal MHC II antigen presentation to naive CD4+ T cells

Intracellular ion fluxes emerge as critical actors of immunoregulation but still remain poorly explored. Here we investigated the role of the redundant cation channels TMEM176A and TMEM176B (TMEM176A/B) in ROR{gamma}t+ cells and conventional dendritic cells (cDCs) using germline and conditional double knock-out (DKO) mice. While Tmem176a/b appeared surprisingly dispensable for the protective function of Th17 and group 3 innate lymphoid cells (ILC3s) in the intestinal mucosa, we found that they were required in cDCs for optimal antigen processing and presentation to CD4+ T cells. Using a real-time imaging method, we show that TMEM176A/B accumulate in dynamic post-Golgi vesicles preferentially linked to the late endolysosomal system and strongly colocalize with HLA-DM. Together, our results suggest that TMEM176A/B ion channels play a direct role in the MHC II compartment (MIIC) of DCs for the fine regulation of antigen presentation and naive CD4+ T cell priming.

immunology↗