Biology subjects

Dupre, M.

Publications and source records attributed to Dupre, M..

4 recordsLinked to original sources

bioRxiv2023

Biallelic non-productive enhancer-promoter interaction precedes imprinted expression of Kcnk9 during mouse neural commitment

How constitutive allelic methylation at imprinting control regions (ICRs) interacts with other levels of regulation to drive timely parental allele-specific expression along large imprinted domains remains partially understood. To gain insight into the regulation of the Peg13-Kcnk9 domain, an imprinted domain with important brain functions, during neural commitment, we performed an integrative analysis of the epigenetic, transcriptomic and cis-spatial organisation in an allele-specific manner in a mouse stem cell-based model of corticogenesis that recapitulates the control of imprinted gene expression during neurodevelopment. We evidence that despite an allelic higher-order chromatin structure associated with the paternally CTCF-bound Peg13 ICR, the enhancer-Kcnk9 promoter contacts can occur on both alleles, although they are only productive on the maternal allele. This observation challenges the canonical model in which CTCF binding isolates the enhancer and its target gene on either side, and suggests a more nuanced role for allelic CTCF binding at some ICRs.

molecular biology↗

bioRxiv2022

A multi-parameter optimization in middle-down analysis of monoclonal antibodies by LC-MS/MS

In antibody-based drug research, regulatory agencies request a complete characterization of antibody proteoforms covering both the amino acid sequence and all post-translational modifications. The usual mass spectrometry-based approach to achieve this goal is bottom-up proteomics, which relies on the digestion of antibodies, but does not allow the diversity of proteoforms to be assessed. Middle-down and top-down approaches have recently emerged as attractive alternatives but are not yet mastered and thus used in routine by many analytical chemistry laboratories. The work described here aims at providing guidelines to achieve the best sequence coverage for the fragmentation of intact light and heavy chains generated from a simple reduction of intact antibodies using Orbitrap mass spectrometry. Three parameters were found crucial to this aim: the use of an electron-based activation technique, the multiplex selection of precursor ions of different charge states and the combination of replicates.

biochemistry↗

bioRxiv2021

TDFragMapper: a visualization tool for evaluating experimental parameters in top-down proteomics

MotivationWe present a new software-tool allowing an easy visualization of fragment ions and thus a rapid evaluation of key experimental parameters on the sequence coverage obtained for the MS/MS analysis of intact proteins. Our tool can deal with multiple fragmentation methods. ResultsWe demonstrate that TDFragMapper can rapidly highlight the experimental fragmentation parameters that are critical to the characterization of intact proteins of various size using top-down proteomics. AvailabilityTDFragMapper, a demonstration video and user tutorial are freely available at https://msbio.pas-teur.fr/tdfragmapper, for academic use; all data are thus available from the ProteomeXchange consortium (identifier PXD024643). Contactdiogobor@gmail.com or julia.chamot-rooke@pasteur.fr

biochemistry↗

bioRxiv2021

Universal amyloidogenicity of patient-derivedimmunoglobulin light chains

The deposition of immunoglobulin light chains (IgLCs) in the form of amorphous aggregates or amyloid fibrils in different tissues of patients can lead to severe and potentially fatal organ damage, requiring transplantation in some cases. There has been great interest in recent years to elucidate the origin of the very different in vivo solubilities of IgLCs, as well as the molecular determinants that drive either the formation of ordered amyloid fibrils or disordered amorphous aggregates. It is commonly thought that the reason of this differential aggregation behaviour is to be found in the amino acid sequences of the respective IgLCs, i.e. that some sequences display higher intrinsic tendencies to form amyloid fibrils. Here we perform in depth Thermodynamic and Aggregation Fingerprinting (ThAgg-Fip) of 9 multiple myeloma patient-derived IgLCs, the amino acid sequences of all of which we have solved by de novo protein sequencing with mass spectrometry. The latter technique was also used for one IgLc from a patient with AL amyloidosis. We find that all samples also contain proteases that fragment the proteins under physiologically relevant mildly acidic pH conditions, leading to amyloid fibril formation in all cases. Our results suggest that while every pathogenic IgLC has a unique ThAgg fingerprint, all sequences have comparable amyloidogenic potential. Therefore, extrinsic factors, in particular presence of, and susceptibility to, proteolytic cleavage is likely to be a strong determinant of in vivo aggregation behaviour. The important conclusion, which is corroborated by systematic analysis of our sequences, as well as many sequences of IgLCs from amyloidosis patients reported in the literature, challenges the current paradigm of the link between sequence and amyloid fibril formation of pathogenic light chains.

biophysics↗