Les corps nucléaires à PML (Voies de phosporylation de PML et différenciation des neuroblastomes. Apports potentiels du SIMS dans l étude des interactions des protéines)

Les assemblages moléculaires sont essentiels dans de nombreux processus cellulaires. Les interactions entre les macromolécules les constituant sont le plus souvent sous le contrôle de nombreuses voies de signalisation et présentent ainsi un caractère très dynamique. Notre étude a porté sur les corps nucléaires à PML, assemblages moléculaires impliqués notamment dans la régulation de l apoptose, le maintien de l intégrité du génome et la différenciation cellulaire. Nous avons identifié les voies de signalisation (ERK et PKC) et les mécanismes moléculaires (principalement la phosporylation de PML) de leur formation lors des phases précoces de la différenciation des neuroblastomes. Notre étude a aussi mis en évidence de probables cibles thérapeutiques portant sur l inhibition de la voie des PKC. En parallèle, une nouvelle méthode d étude des assemblages moléculaires a été développée. Cette méthode repose sur l imagerie NanoSIMS 50. Nous montrons qu elle permet la détection et la localisation subcellulaire d une protéine unique. Nous montrons également qu elle permet de détecter l extrême proximité de deux molécules (2nm). En perspective, l utilisation de cette nouvelle méthode devrait apporter des éléments nouveaux à notre compréhension des mécanismes de formation des corps nucléaires à PML.Assemblies of molecules and macromolecules play and essential role in many cellular processes. The dynamic interactions between the macromolecules in these assemblies are often controlled by several signalling pathways. The study presented here focuses on PML nuclear bodies which are molecular aseemblies involved in the regulation of apoptosis, the maintenance of genome integrity and cell differenciation. In thus study, we indentify both molecular mechanisms (principally phosphorylation of PML itself) and the ERK and PKC signal transduction pathways as responsible for the assembly of PML nuclear bodies in early neuroblastoma differentiation. This study also reveals potential targets within the PKC transduction for drug therapies. In parallel, we have developped a new method for determining molecular interactions. This method, which is based on imaging using a NanoSIMS 50, allows the detection and intracellular localization of a single protein. We also shom that this method allows two molecules to be co-localized to within 2 nm. This method promises to give new insight into the interactions responsible for the assembly of PML nuclear bodies.ROUEN-BU Sciences (764512102) / SudocSudocFranceF

SIED-significant Isotopic enrichment Detection version 1.61

logicie

LOCALIZATION AND MEASUREMENT OF COSMETIC COMPOUNDS IN SKIN BY SECONDARYION MASS SPECTROMETRY (SIMS)

International audienc

LOCALIZATION AND MEASUREMENT OF COSMETIC COMPOUNDS IN SKIN BY SECONDARYION MASS SPECTROMETRY (SIMS)

International audienc

LOCALIZATION AND MEASUREMENT OF COSMETIC COMPOUNDS IN SKIN BY SECONDARYION MASS SPECTROMETRY (SIMS)

International audienc

Localisation de nanoparticules de TiO2 dans les tissus cutanés par imagerie corrélative MET/NanoSIMS

International audienc

The High Resolutive Detection of TiO2 Nanoparticles in Human Corneocytes via TEM/NanoSIMS Correlation

Titanium dioxide (TiO2) nanoparticles (NPs) are the subject of numerous studies and controversies on the risks they could pose to the environment and human health. When in contact with biological tissues, NPs can sometimes be challenging to precisely localize within subcellular structures (typically around 0.1 µm) when they exist as isolated NPs, particularly when using the SIMS approach. Indeed, the chemical signals produced by isolated NPs are very low, so they can be confused with background signals. This was the motivation behind our development of a new strategy for correlating TEM/SIMS to detect TiO2 NPs in close proximity to cutaneous corneocytes. For this purpose, we initially developed a new tool for TEM and SIMS image registration based on a non-rigid image-deformation-enabling image overlay. Combining SIMS and TEM data through this overlay enhances NP localization’s precision. Secondly, we developed an algorithm based on the statistical analysis of multiplane SIMS images to denoise them. As a result, background noise was reduced, illuminating the low yet specific signals from isolated NPs. Finally, this new correlative approach enables the precise 3D localization of isolated NPs within the analyzed volume. We consider this method a breakthrough for subcellular-scale NP localization

Localisation de nanoparticules de TiO2 dans les tissus cutanés par imagerie corrélative MET/NanoSIMS

International audienc