Dégradation de protéines induite par la lumière : une approche de biologie chimique

The regulation of proteolysis is an efficient way to control protein function in cells. Here, we present a general strategy enabling to increase the spatiotemporal resolution of conditional proteolysis by using light activation as trigger. Our approach relies on the auxin-inducible degradation (AID) system obtained by transposing components of the plant auxin-dependent degradation pathway in mammalian cells. We developed an optimized version of the AID which enables to significantly destabilize target proteins in presence of auxin. Parallely, we developed a photoactivatable auxin that acts as a photoactivatable inducer of degradation. Upon local and short light illumination, auxin is released in cells and triggers the degradation of a protein of interest with spatiotemporal control. This generic method was implemented in nuclear and cytoplasmic contexts.La régulation de la protéolyse est un outil efficace pour le contrôle de la fonction d'une protéine dans des cellules. Nous présentons dans ce travail une stratégie générique permettant d'activer la protéolyse de façon conditionnelle par la lumière, améliorant ainsi la résolution spatio-temporelle. Notre approche repose sur un système de dégradation inductible par l'auxine (AID), mis au point en transposant des composants de la voie de dégradation contrôlée par l'auxine existant chez les plantes dans des cellules de mammifères. Nous présentons une version optimisée du système AID qui a permis de diminuer de façon significative la stabilité de protéines cibles en présence d'auxine. Nous avons en parallèle développé un déclencheur de dégradation photo-activable sous la forme d'une auxine cagée. Une illumination courte et locale permet la libération efficace de l'auxine dans les cellules et induit la dégradation de protéine d'intérêt avec un bon contrôle spatiotemporel. Cette méthode générique a été utilisée dans des contextes nucléaires et cytoplasmiques

Dégradation de protéines induite par la lumière : une approche de biologie chimique

La régulation de la protéolyse est un outil efficace pour le contrôle de la fonction d'une protéine dans des cellules. Nous présentons dans ce travail une stratégie générique permettant d'activer la protéolyse de façon conditionnelle par la lumière, améliorant ainsi la résolution spatio-temporelle. Notre approche repose sur un système de dégradation inductible par l'auxine (AID), mis au point en transposant des composants de la voie de dégradation contrôlée par l'auxine existant chez les plantes dans des cellules de mammifères. Nous présentons une version optimisée du système AID qui a permis de diminuer de façon significative la stabilité de protéines cibles en présence d'auxine. Nous avons en parallèle développé un déclencheur de dégradation photo-activable sous la forme d'une auxine cagée. Une illumination courte et locale permet la libération efficace de l'auxine dans les cellules et induit la dégradation de protéine d'intérêt avec un bon contrôle spatiotemporel. Cette méthode générique a été utilisée dans des contextes nucléaires et cytoplasmiques.The regulation of proteolysis is an efficient way to control protein function in cells. Here, we present a general strategy enabling to increase the spatiotemporal resolution of conditional proteolysis by using light activation as trigger. Our approach relies on the auxin-inducible degradation (AID) system obtained by transposing components of the plant auxin-dependent degradation pathway in mammalian cells. We developed an optimized version of the AID which enables to significantly destabilize target proteins in presence of auxin. Parallely, we developed a photoactivatable auxin that acts as a photoactivatable inducer of degradation. Upon local and short light illumination, auxin is released in cells and triggers the degradation of a protein of interest with spatiotemporal control. This generic method was implemented in nuclear and cytoplasmic contexts

Re-investigating PLK1 inhibitors as antimitotic agents

Polo-like kinase 1 (PLK1) plays key roles during mitosis, prompting the development of PLK1 inhibitors for anticancer therapy. We recently determined that PLK1 is crucially required for entry into mitosis. Hence, we discuss the potential and limitations of PLK1 inhibition strategies to promote mitotic arrest and death of cancer cells

Monolayer Graphene Coating of Intracortical Probes for Long‐Lasting Neural Activity Monitoring

International audienceThe invasiveness of intracortical interfaces currently used today is responsible for the formation of an intense immunoresponse and inflammatory reaction from neural cells and tissues. This leads to a high concentration of reactive glial cells around the implant site, creating a physical barrier between the neurons and the recording channels. Such a rejection of foreign analog interfaces causes neural signals to fade from recordings which become flooded by background noise after a few weeks. Despite their invasiveness, those devices are required to track single neuron activity and decode fine sensory or motor commands. In particular, such quantitative and long‐lasting recordings of individual neurons are crucial during a long time period (several months) to restore essential functions of the cortex, disrupted after injuries, stroke, or neurodegenerative diseases. To overcome this limitation, graphene and related materials have attracted numerous interests, as they gather in the same material many suitable properties for interfacing living matter, such as an exceptionally high neural affinity, diffusion barrier, and high physical robustness. In this work, the neural affinity of a graphene monolayer with numerous materials commonly used in neuroprostheses is compared, and its impact on the performance and durability of intracortical probes is investigated. For that purpose, an innovative coating method to wrap 3D intracortical probes with a continuous monolayer graphene is developed. Experimental evidence demonstrate the positive impact of graphene on the bioacceptance of conventional intracortical probes, in terms of detection efficiency and tissues responses, allowing real‐time samplings of motor neuron activity during 5 weeks. Since continuous graphene coatings can easily be implemented on a wide range of 3D surfaces, this study further motivates the use of graphene and related materials as it could significantly contribute to reduce the current rejection of neural probes currently used in many research areas, from fundamental neurosciences to medicine and neuroprostheses

Introducing a biomimetic coating for graphene neuroelectronics: toward in-vivo applications

International audienc

Light-Activated Proteolysis for the Spatiotemporal Control of Proteins

The regulation of proteolysis is an efficient way to control protein function in cells. Here, we present a general strategy enabling to increase the spatiotemporal resolution of conditional proteolysis by using light activation as trigger. Our approach relies on the auxin-inducible degradation system obtained by transposing components of the plant auxin-dependent degradation pathway in mammalian cells. We developed a photoactivatable auxin that acts as a photoactivatable inducer of degradation. Upon local and short light illumination, auxin is released in cells and triggers the degradation of a protein of interest with spatiotemporal control

DNA polymerase zeta contributes to heterochromatin replication to prevent genome instability

International audienceThe DNA polymerase zeta (Polf) plays a critical role in bypassing DNA damage. REV3L, the catalytic subunit of Polf, is also essential in mouse embryonic development and cell proliferation for reasons that remain incompletely understood. In this study, we reveal that REV3L protein interacts with heterochromatin components including repressive histone marks and localizes in pericentromeric regions through direct interaction with HP1 dimer. We demonstrate that Polf/REV3L ensures progression of replication forks through difficult-to-replicate pericentromeric heterochromatin, thereby preventing spontaneous chromosome break formation. We also find that Rev3l-deficient cells are compromised in the repair of heterochromatin-associated double-stranded breaks, eliciting deletions in late-replicating regions. Lack of REV3L leads to further consequences that may be ascribed to heterochromatin replication and repair-associated functions of Polf, with a disruption of the temporal replication program at specific loci. This is correlated with changes in epigenetic landscape and transcriptional control of developmentally regulated genes. These results reveal a new function of Polf in preventing chromosome instability during replication of heterochromatic regions

Education as Risk Factor of Mild Cognitive Impairment: The Link to the Gut Microbiome

peer reviewedBackground: With differences apparent in the gut microbiome in mild cognitive impairment (MCI) and dementia, and risk factors of dementia linked to alterations of the gut microbiome, the question remains if gut microbiome characteristics may mediate associations of education with MCI. Objectives: We sought to examine potential mediation of the association of education and MCI by gut microbiome diversity or composition. Design: Cross-sectional study. Setting: Luxembourg, the Greater Region (surrounding areas in Belgium, France, Germany). Participants: Control participants of the Luxembourg Parkinson’s Study. Measurements: Gut microbiome composition, ascertained with 16S rRNA gene amplicon sequencing. Differential abundance, assessed across education groups (0–10, 11–16, 16+ years of education). Alpha diversity (Chao1, Shannon and inverse Simpson indices). Mediation analysis with effect decomposition was conducted with education as exposure, MCI as outcome and gut microbiome metrics as mediators. Results: After exclusion of participants below 50, or with missing data, n=258 participants (n=58 MCI) were included (M [SD] Age=64.6 [8.3] years). Higher education (16+ years) was associated with MCI (Odds ratio natural direct effect=0.35 [95% CI 0.15–0.81]. Streptococcus and Lachnospiraceae-UCG-001 genera were more abundant in higher education. Conclusions: Education is associated with gut microbiome composition and MCI risk without clear evidence for mediation. However, our results suggest signatures of the gut microbiome that have been identified previously in AD and MCI to be reflected in lower education and suggest education as important covariate in microbiome studies.MCI-BIOME_20193. Good health and well-bein