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Dive into the research topics where Maxime Dahan is active.

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Featured researches published by Maxime Dahan.


Human Molecular Genetics | 2016

Altered microtubule dynamics and vesicular transport in mouse and human MeCP2-deficient astrocytes

Chloé Delépine; Hamid Meziane; Juliette Nectoux; Matthieu Opitz; Amos B. Smith; Carlo Ballatore; Yoann Saillour; Annelise Bennaceur-Griscelli; Qiang Chang; Emily Cunningham Williams; Maxime Dahan; Aurélien Duboin; Pierre Billuart; Yann Herault; Thierry Bienvenu

Rett syndrome (RTT) is a rare X-linked neurodevelopmental disorder, characterized by normal post-natal development followed by a sudden deceleration in brain growth with progressive loss of acquired motor and language skills, stereotypic hand movements and severe cognitive impairment. Mutations in the methyl-CpG-binding protein 2 (MECP2) cause more than 95% of classic cases. Recently, it has been shown that the loss of Mecp2 from glia negatively influences neurons in a non-cell-autonomous fashion, and that in Mecp2-null mice, re-expression of Mecp2 preferentially in astrocytes significantly improved locomotion and anxiety levels, restored respiratory abnormalities to a normal pattern and greatly prolonged lifespan compared with globally null mice. We now report that microtubule (MT)-dependent vesicle transport is altered in Mecp2-deficient astrocytes from newborn Mecp2-deficient mice compared with control wild-type littermates. Similar observation has been made in human MECP2 p.Arg294* iPSC-derived astrocytes. Importantly, administration of Epothilone D, a brain-penetrant MT-stabilizing natural product, was found to restore MT dynamics in Mecp2-deficient astrocytes and in MECP2 p.Arg294* iPSC-derived astrocytes in vitro. Finally, we report that relatively low weekly doses of Epothilone D also partially reversed the impaired exploratory behavior in Mecp2(308/y) male mice. These findings represent a first step toward the validation of an innovative treatment for RTT.


Nature Methods | 2015

InferenceMAP: mapping of single-molecule dynamics with Bayesian inference

Mohamed El Beheiry; Maxime Dahan; Jean-Baptiste Masson

Single-molecule imaging has become ubiquitous in biophysics, biology, biochemistry and biotechnology, covering a large range of in vitro and in vivo applications. This ever-growing field now requires new and reliable statistical tools for data analysis. This is especially true for high-density single-molecule tracking methods that yield massive amounts of data and invite the use of statistics-based methods for analysis. Of particular importance is the extraction of dynamic properties (such as diffusion and transport parameters) and the ability to map these properties at different spatial scales (up to the full extent of the cell).Bayesian analysis is a powerful method that has recently garnered interest in the treatment of single-molecule trajectories. Previously, we have shown that it provides an efficient means for estimating the relevant physical parameters that characterize the motion of individual molecules. Of particular importance, we have shown that interaction fields (which are systematically neglected in most approaches) play a paramount role in the long-term dynamics of biomolecules.With this motivation, we present InferenceMAP, an interactive software tool that uses a powerful Bayesian technique to extract the parameters that describe the motion of individual molecules from single-molecule trajectories. The main features of our tool include:⋅A versatile calculation platform for estimating dynamic parameters, including the ability to specify relevant prior probabilities.⋅Adaptive meshing methods to conform to different temporal and spatial scales⋅The ability to generate vast three-dimensional landscapes of single-molecule dynamicsWe present relevant applications inside lipid rafts, glycine receptors, and HIV assembly platforms.


Proceedings of SPIE | 2013

Dual-color 3D PALM/dSTORM imaging of centrosomal proteins using MicAO 3DSR

Grégory Clouvel; Audrius Jasaitis; James Sillibourne; Ignacio Izeddin; Mohamed El Beheiry; Xavier Levecq; Maxime Dahan; Michel Bornens; Xavier Darzacq

The determination of 3-dimensional arrangement of subcellular assemblies has become a necessary requirement in cellular biology. Unfortunately, the size of most assemblies lies beyond the diffraction limit and therefore they cannot be visualized using conventional fluorescence microscopy techniques. Photoactivation localization microscopy (PALM) and stochastic optical reconstruction microscopy (STORM) enable the localization of fluorescent molecules with nanometric resolution. We used these microscopy methods together with MicAO 3D-SR – the first adaptive optics device which introduces the three-dimensional imaging capability for PALM/STORM. MicAO also corrects various types of aberrations induced by optical elements inside the microscope and by the biological sample. The correction of these aberrations almost doubles the number of detected photons, increasing the localization precision of PALM/STORM by 40%. At 1000 detected photons the localization precision of our setup is 8 nm in lateral and 16 nm in axial directions. The separate optimization performed for two different colors delivers superb imaging quality, as demonstrated by dual-color 3-dimentional imaging of two centrosomal proteins in HeLa cells.


bioRxiv | 2018

Live single molecule microscopy of HIV-1 assembly in host T cells reveals a spatio-temporal effect of the viral genome.

Charlotte Floderer; Jean-Baptiste Masson; Elise Boiley; Sonia Georgeault; Peggy Merida; Mohamed El Beheiry; Maxime Dahan; Philippe Roigeard; Jean-Baptiste Sibarita; Cyril Favard; Delphine Muriaux

Monitoring virus assembly dynamic at the nanoscale level in host cells remains a major challenge. Human Immunodeficiency Virus type 1 (HIV-1) components are addressed to the plasma membrane where they assemble to form spherical particles of 100nm in diameter. HIV-1 Gag protein expression alone is sufficient to produce virus-like particles (VLPs) that resemble immature virus. Here, we monitored Gag assembly in host CD4 T lymphocytes using single molecule dynamics microscopy and energy mapping. A workflow allowing long time recordings of single Gag molecule localization, diffusion and effective energy maps was developed for robust quantitative analysis of HIV assembly and budding. Comparison of numerous cell plasma membrane assembling platforms in cells expressing wild type or assembly-defective Gag proteins showed that VLP formation last 15 minutes, with an assembly time of 5 minutes, and that the nucleocapsid domain is mandatory. Importantly, it reveals that the viral genome coordinates spatio-temporally HIV-1 assembly.


bioRxiv | 2018

Optogenetic dissection of Rac1 and Cdc42 gradient shaping

Simon De Beco; Kotryna Vaidziulyte; John Manzi; Fabrice Dalier; Fahima Di Frederico; Gaetan Cornilleau; Maxime Dahan; Mathieu Coppey

During migration, cells present a polarized activity that is aligned with the direction of motion. This cell polarity is established by an internal molecular circuitry, without the requirement of extracellular cues. At the heart of this circuitry, Rho GTPases spontaneously form spatial gradients that define the front and back of migrating cells. At the front of the cell, active Cdc42 forms a steep gradient whereas active Rac1 forms a more extended pattern peaking a few microns away from the cell tip. What are the mechanisms shaping these gradients, and what is the functional role of the shape of these gradients? Combining optogenetics and cell micopatterning, we show that Cdc42 and Rac1 gradients are set by spatial patterns of activators and deactivators and not directly by advection or diffusion mechanisms. Cdc42 simply follows the distribution of GEFs thanks to a uniform GAP activity, whereas Rac1 shaping requires the activity of an additional GAP, β2-chimaerin, which is sharply localized at the tip of the cell. We find that β2-chimaerin recruitment depends on feedbacks from Cdc42 and Rac1. Functionally, the extent -neither the slope nor the amplitude- of RhoGTPases gradients governs cell migration. A Cdc42 gradient with a short spatial extent is required to maximize directionality during cell migration while an extended Rac1 gradient controls the speed of the cell.


Reference Module in Biomedical Sciences#R##N#Encyclopedia of Cell Biology | 2016

High-Speed Localization Microscopy and Single-Particle Tracking

M. El Beheiry; Maxime Dahan

Based on the detection of individually fluorescing molecules, localization microscopy (LM) is currently an established imaging modality in studies of cellular biology. Applied to live cells, LM provides the means to probe environments with single-molecule precision and, moreover, provide information on elementary biological processes. High-speed LM involves generating discrete high-resolution snapshots of molecular distributions in living cells and single-particle tracking involves following the motion of individual molecules over time. This article details these two popular configurations of LM.


Archive | 2016

Nanobiosciences: New Ideas and Tools for Investigating and Manipulating Living Systems

Maxime Dahan

Nanoscience has reached a point today where we can begin to create hybrid objects at the interface between nanomaterials and the life sciences. These objects combine advanced physical properties, viz., optical, mechanical, magnetic, etc., with the remarkable reactivity of biological molecules. In particular, they can be used as probes or micromanipulation tools, from the molecular and cellular scale right up to the scale of organisms. This should bring us new insights into the organisation of living things, and new prospects for diagnosis and therapy in nanomedicine.


international symposium on biomedical imaging | 2018

Multi-resolution based spatially adaptive multi-order total variation for image restoration

Sanjay Viswanath; Simon De Beco; Maxime Dahan; Muthuvel Arigovindan


Biophysical Journal | 2018

Functional and Structural Studies of Interplay between an ABC Transporter and its Surrounding Membrane Environment

Su-Jin Paik; Alicia Damm; John Manzi; Maxime Dahan; Patricia Bassereau; Emmanuel Margeat; Daniel Lévy


Biophysical Journal | 2016

Magnetogenetic Manipulation of Intracellular Signaling using Ferritin Nanoparticles

Chiara Vicario; Domenik Liße; Cornelia Monzel; Albert Ikramov; Jacob Piehler; Mathieu Coppey; Maxime Dahan

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Antoine Triller

École Normale Supérieure

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Ignacio Izeddin

École Normale Supérieure

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John Manzi

PSL Research University

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Xavier Darzacq

University of California

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