Université PSL

Publications

SEARCH

Laboratory :
Author :
Revue :
Year :
Arc/Arg3.1 governs inflammatory dendritic cell migration from the skin and thereby controls T cell activation.
Ufer F, Vargas P, Engler JB, Tintelnot J, Schattling B, Winkler H, Bauer S,Kursawe N, Willing A, Keminer O, Ohana O, Salinas-Riester G, Pless O, Kuhl D, Friese MA.
Sci Immunol - 1(3) 8665 - doi: 10.1126/sciimmunol.aaf8665. - 2016
Skin-migratory dendritic cells (migDCs) are pivotal antigen-presenting cells that continuously transport antigens to draining lymph nodes and regulate immune responses. However, identification of migDCs is complicated by the lack of distinguishing markers, and it remains unclear which molecules determine their migratory capacity during inflammation. We show that, in the skin, the neuronal plasticity molecule activity-regulated cytoskeleton-associated protein/activity-regulated gene 3.1 (Arc/Arg3.1) was strictly confined to migDCs. Mechanistically, Arc/Arg3.1 was required for accelerated DC migration during inflammation because it regulated actin dynamics through nonmuscle myosin II. Accordingly, Arc/Arg3.1-dependent DC migration was critical for mounting T cell responses in experimental autoimmune encephalomyelitis and allergic contact dermatitis. Thus, Arc/Arg3.1 was restricted to migDCs in the skin and drove fast DC migration by exclusively coordinating cytoskeletal changes in response to inflammatory challenges. These findings commend Arc/Arg3.1 as a universal switch in migDCs that may be exploited to selectively modify immune responses.
Deterministic patterns in cell motility
Ido Lavi, Matthieu Piel, Ana-Maria Lennon-Duménil, Raphaël Voituriez & Nir S. Gov
Nature Physics - 12 1146–1152 - DOI : 10.1038/nphys3836 - 2016
Cell migration paths are generally described as random walks, associated with both intrinsic and extrinsic noise. However, complex cell locomotion is not merely related to such fluctuations, but is often determined by the underlying machinery. Cell motility is driven mechanically by actin and myosin, two molecular components that generate contractile forces. Other cell functions make use of the same components and, therefore, will compete with the migratory apparatus. Here, we propose a physical model of such a competitive system, namely dendritic cells whose antigen capture function and migratory ability are coupled by myosin II. The model predicts that this coupling gives rise to a dynamic instability, whereby cells switch from persistent migration to unidirectional self-oscillation, through a Hopf bifurcation. Cells can then switch to periodic polarity reversals through a homoclinic bifurcation. These predicted dynamic regimes are characterized by robust features that we identify through in vitro trajectories of dendritic cells over long timescales and distances. We expect that competition for limited resources in other migrating cell types can lead to similar deterministic migration modes.
On-Chip Quantitative Measurement of Mechanical Stresses During Cell Migration with Emulsion Droplets.
D Molino, S Quignard, C Gruget, F Pincet, Y Chen, M Piel, J Fattaccioli
Scientific Reports - 6 29113 - DOI : 10.1038/srep29113 - 2016
The ability of immune cells to migrate within narrow and crowded spaces is a critical feature involved in various physiological processes from immune response to metastasis. Several in-vitro techniques have been developed so far to study the behaviour of migrating cells, the most recent being based on the fabrication of microchannels within which cells move. To address the question of the mechanical stress a cell is able to produce during the encounter of an obstacle while migrating, we developed a hybrid microchip made of parallel PDMS channels in which oil droplets are sparsely distributed and serve as deformable obstacles. We thus show that cells strongly deform droplets while passing them. Then, we show that the microdevice can be used to study the influence of drugs on migration at the population level. Finally, we describe a quantitative analysis method of the droplet deformation that allows measuring in real-time the mechanical stress exerted by a single cell. The method presented herein thus constitutes a powerful analytical tool for cell migration studies under confinement.
Arc/Arg3.1 governs inflammatory dendritic cell migration from the skin and thereby controls T cell activation.
Ufer F, Vargas P, Engler JB, Tintelnot J, Schattling B, Winkler H, Bauer S, Kursawe N, Willing A, Keminer O, Ohana O, Salinas-Riester G, Pless O, Kuhl D, Friese MA.
Sci Immunol - 1(3) - DOI: 10.1126/sciimmunol.aaf8665 - 2016
Skin-migratory dendritic cells (migDCs) are pivotal antigen-presenting cells that continuously transport antigens to draining lymph nodes and regulate immune responses. However, identification of migDCs is complicated by the lack of distinguishing markers, and it remains unclear which molecules determine their migratory capacity during inflammation. We show that, in the skin, the neuronal plasticity molecule activity-regulated cytoskeleton-associated protein/activity-regulated gene 3.1 (Arc/Arg3.1) was strictly confined to migDCs. Mechanistically, Arc/Arg3.1 was required for accelerated DC migration during inflammation because it regulated actin dynamics through nonmuscle myosin II. Accordingly, Arc/Arg3.1-dependent DC migration was critical for mounting T cell responses in experimental autoimmune encephalomyelitis and allergic contact dermatitis. Thus, Arc/Arg3.1 was restricted to migDCs in the skin and drove fast DC migration by exclusively coordinating cytoskeletal changes in response to inflammatory challenges. These findings commend Arc/Arg3.1 as a universal switch in migDCs that may be exploited to selectively modify immune responses.
Innate control of actin nucleation determines two distinct migration behaviours in dendritic cells.
Vargas P1,2, Maiuri P2, Bretou M1, Sáez PJ1, Pierobon P, Maurin M, Chabaud M, Lankar D1, Obino D, Terriac E, Raab M, Thiam HR, Brocker T, Kitchen-Goosen SM, Alberts AS, Sunareni P, Xia S, Li R5, Voituriez R, Piel M, Lennon-Duménil AM.
Nat. Cell Biol. - 18(1) 18(1) - doi: 10.1038/ncb3284 - 2016
Dendritic cell (DC) migration in peripheral tissues serves two main functions: antigen sampling by immature DCs, and chemokine-guided migration towards lymphatic vessels (LVs) on maturation. These migratory events determine the efficiency of the adaptive immune response. Their regulation by the core cell locomotion machinery has not been determined. Here, we show that the migration of immature DCs depends on two main actin pools: a RhoA-mDia1-dependent actin pool located at their rear, which facilitates forward locomotion; and a Cdc42-Arp2/3-dependent actin pool present at their front, which limits migration but promotes antigen capture. Following TLR4-MyD88-induced maturation, Arp2/3-dependent actin enrichment at the cell front is markedly reduced. Consequently, mature DCs switch to a faster and more persistent mDia1-dependent locomotion mode that facilitates chemotactic migration to LVs and lymph nodes. Thus, the differential use of actin-nucleating machineries optimizes the migration of immature and mature DCs according to their specific function.
On-Chip Quantitative Measurement of Mechanical Stresses During Cell Migration with Emulsion Droplets
D. Molino, S. Quignard, C. Gruget, F. Pincet, Y. Chen, M. Piel & J. Fattaccioli
Scientific Reports - 6 29113 - DOI: 10.1038/srep29113 - 2016
The ability of immune cells to migrate within narrow and crowded spaces is a critical feature involved in various physiological processes from immune response to metastasis. Several in-vitro techniques have been developed so far to study the behaviour of migrating cells, the most recent being based on the fabrication of microchannels within which cells move. To address the question of the mechanical stress a cell is able to produce during the encounter of an obstacle while migrating, we developed a hybrid microchip made of parallel PDMS channels in which oil droplets are sparsely distributed and serve as deformable obstacles. We thus show that cells strongly deform droplets while passing them. Then, we show that the microdevice can be used to study the influence of drugs on migration at the population level. Finally, we describe a quantitative analysis method of the droplet deformation that allows measuring in real-time the mechanical stress exerted by a single cell. The method presented herein thus constitutes a powerful analytical tool for cell migration studies under confinement.
Human Upf1 is a highly processive RNA helicase and translocase with RNP remodelling activities
Francesca Fiorini, Debjani Bagchi, Hervé Le Hir and Vincent Croquette
Nature Communications - Volume 6 (2015) Article number: 7581 - doi:10.1038/ncomms8581 - 2015
RNA helicases are implicated in most cellular RNA-dependent events. In eukaryotes however, only few have been functionally characterized. Upf1 is a RNA helicase essential for nonsense-mediated mRNA decay (NMD). Here, using magnetic tweezers and bulk assays, we observe that human Upf1 is able to translocate slowly over long single-stranded nucleic acids with a processivity >10 kb. Upf1 efficiently translocates through double-stranded structures and protein-bound sequences, demonstrating that Upf1 is an efficient ribonucleoprotein complex remodeler. Our observation of processive unwinding by an eukaryotic RNA helicase reveals that Upf1, once recruited onto NMD mRNA targets, can scan the entire transcript to irreversibly remodel the mRNP, facilitating its degradation by the NMD machinery.
Two-step local functionalization of fluoropolymer Dyneon THV microfluidic materials by scanning electrochemical microscopy combined to click reaction
Cyrine Slim, Eva Ratajovà, Sophie Griveau, Frédéric Kanoufi, David Ferraro, Camille Perréard, Fanny d’Orlyé, Anne Varenne and Fethi Bedioui
Electrochemistry Communications - 60 (5–8) - doi:10.1016/j.elecom.2015.07.019 - 2015
We propose an original two-step strategy combining the use of scanning electrochemical microscopy (SECM) and molecular chemistry via a “click” reaction (copper (I)-catalyzed azide alkyne cycloaddition (CuAAC)) to locally functionalize Dyneon THV surfaces, an attractive fluoropolymer for microfluidic applications. The first step consists in the local reduction of THV using a SECM tip to activate the surface by the creation of a locally carbonized zone and notably the formation of surface alkyne functions. This is then followed by a direct CuAAC reaction with an azide-bearing ligand for its local immobilization. The proof of concept is demonstrated by efficient local functionalization of the substrate with a fluorescent dye stable up to 6 months. Surface modifications were characterized by IR-ATR, XPS, and fluorescence microscopy.
Dynamics of CRISPR-Cas9 genome interrogation in living cells
Knight SC, Xie L, Deng W, Guglielmi B, Witkowsky LB, Bosanac L, Zhang ET, El Beheiry M, Masson J-B, Dahan M, Liu Z, Doudna JA, Tjian R
Science - 350(6262) 823-6 - DOI: 10.1126/science.aac6572 - 2015
The RNA-guided CRISPR-associated protein Cas9 is used for genome editing, transcriptional modulation, and live-cell imaging. Cas9-guide RNA complexes recognize and cleave double-stranded DNA sequences on the basis of 20-nucleotide RNA-DNA complementarity, but the mechanism of target searching in mammalian cells is unknown. Here, we use single-particle tracking to visualize diffusion and chromatin binding of Cas9 in living cells. We show that three-dimensional diffusion dominates Cas9 searching in vivo, and off-target binding events are, on average, short-lived (<1 second). Searching is dependent on the local chromatin environment, with less sampling and slower movement within heterochromatin. These results reveal how the bacterial Cas9 protein interrogates mammalian genomes and navigates eukaryotic chromatin structure.
Droplets in Microchannels: Dynamical Properties of the Lubrication Film
Axel Huerre, Olivier Theodoly, Alexander M. Leshansky, Marie-Pierre Valignat, Isabelle Cantat and Marie-Caroline Jullien
Phys. Rev. Lett. - 115 (064501) 064501 - http://dx.doi.org/10.1103/PhysRevLett.115.064501 - 2015
We study the motion of droplets in a confined, micrometric geometry, by focusing on the lubrication film between a droplet and a wall. When capillary forces dominate, the lubrication film thickness evolves nonlinearly with the capillary number due to the viscous dissipation between the meniscus and the wall. However, this film may become thin enough (tens of nanometers) that intermolecular forces come into play and affect classical scalings. Our experiments yield highly resolved topographies of the shape of the interface and allow us to bring new insights into droplet dynamics in microfluidics. We report the novel characterization of two dynamical regimes as the capillary number increases: (i) at low capillary numbers, the film thickness is constant and set by the disjoining pressure, while (ii) above a critical capillary number, the interface behavior is well described by a viscous scenario. At a high surfactant concentration, structural effects lead to the formation of patterns on the interface, which can be used to trace the interface velocity, that yield direct confirmation of the boundary condition in the viscous regime.

346 publications.