UMR168 – Physico-Chimie Curie Lab

Team Publications

Year of publication 2019

Jamecna D, Polidori DJ, Mesmin B, Dezi M, Lévy D, Bigay J, Antonny B (2019 Mar 22)

An intrinsically disordered region in OSBP acts as an entropic barrier to control protein dynamics and orientation at membrane contact sites

Developmental cell : DOI : doi.org/10.1016/j.devcel.2019.02.021 Learn more
Summary

Lipid transfer proteins (LTPs) acting at membrane contact sites (MCS) between the ER and other organelles contain domains involved in heterotypic (e.g. ER to Golgi) membrane tethering as well as domains involved in lipid transfer. Here, we show that a long ≈ 90 aa intrinsically unfolded sequence at the N-terminus of oxysterol binding protein (OSBP) controls OSBP orientation and dynamics at MCS. This Gly-Pro-Ala-rich sequence, whose hydrodynamic radius is twice as that of folded domains, prevents the two PH domains of the OSBP dimer from homotypically tethering two Golgi-like membranes and considerably facilitates OSBP in-plane diffusion and recycling at MCS. Although quite distant in sequence, the N-terminus of OSBP-related protein-4 (ORP4) has similar effects. We propose that N-terminal sequences of low complexity in ORPs form an entropic barrier that restrains protein orientation, limits protein density and facilitates protein mobility in the narrow and crowded MCS environment.

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Simon C*, Kusters R*, Caorsi V*, Allard A, Abou-Ghali M, Manzi J, Di Cicco A, Lévy D, Lenz M, Joanny J-F, Campillo C, Plastino J, Sens P*, Sykes C* (2019 Mar 18)

Actin dynamics drive cell-like membrane deformation

Nature Physics : DOI : 10.1038/s41567-019-0464-1 Learn more
Summary

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Bertin Aurélie, Lomakin Alexis (2019 Feb 15)

Meeting report – Building the Cell 2018

journal of cell science : 132 : DOI : 10.1242/jcs.229765 Learn more
Summary

Cell biologists from all around the world gathered in Paris on the 26 to 28 September 2018 to participate in the 3rd international meeting ‘Building the Cell’. It was organized by Hélène Barelli, Arnaud Echard, Thierry Galli, Florence Niedergang, Manuel Théry and Marie Hélène Verlhac on behalf of the French Society for Cell Biology (SBCF) at the Institut Pasteur. Around 230 participants joined the meeting for stimulating talks, discussions, poster sessions, and a gala dinner on the Seine that included a music performance by the rock group ‘Membrane Band’. The unifying theme of the meeting was the development of creative multidisciplinary approaches to understand cellular life at different scales in a dynamic and quantitative manner. Here, we summarize the results presented at the meeting and the emerging ideas from the different sessions.

The 3rd international meeting ‘Building the Cell’ (Fig. 1Fig. 2) was divided into ten different sessions that covered a variety of topics including intracellular trafficking, cell division, cytoskeletal dynamics and cell mechanics, cancer and stem cell biology, embryonic development and tissue morphogenesis, neurobiology, and aggregates and phase transitions. A broad spectrum of modern approaches and experimental systems ranging from synthetic biology and stem cell technologies to 3D organoids and animal models was presented. The meeting highlighted some of the latest and novel findings in cell biology, often coupled to major methodological developments in quantitative microscopy and computational modelling, as well as cell and tissue micro-engineering.

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Dreier J, Castello M, Coceano G, Cáceres R, Plastino J, Vicidomini G, Testa I (2019 Feb 1)

Smart scanning for low-illumination and fast RESOLFT nanoscopy in vivo

Nature Communications : 10 : 556 : DOI : 10.1038/s41467-019-08442-4 Learn more
Summary

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Simon† C, Kusters† R, Caorsi† V, Allard A, Abou-Ghali M, Manzi J, Di Cicco A, Lévy D, Lenz M, Joanny JF, Campillo C, Plastino J, Sens P &, Sykes C& (2019 Jan 24)

Actin dynamics drive cell-like membrane deformation.

Nature Physics : Accepted Learn more
Summary

Cell membrane deformations are crucial for proper cell function. Specialized protein assemblies initiate inward or outward membrane deformations that turn into, for example, endocytic intermediates or filopodia. Actin assembly and dynamics are involved in this process, although their detailed role remains controversial. We show here that a dynamic, branched actin network is sufficient to initiate both inward and outward membrane deformation. With actin polymerization triggered at the membrane of liposomes, we produce inward filopodia-like structures at low tension, while outward endocytosis-like structures are robustly generated regardless of tension. Our results shed light on the mechanism of endocytosis, both in mammalian cells, where actin polymerization forces are required when membrane tension is increased, and in yeast, where those forces are necessary to overcome the opposing turgor pressure. By combining experimental observations with physical modeling, we propose a mechanism for actin-driven endocytosis controlled by membrane tension and the architecture of the actin network.

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Beber A, Taveneau C, Nania M, Tsai FC, Di Cicco A, Bassereau P, Lévy D, Cabral JT, Isambert H, Mangenot S*, Bertin A* (2019 Jan 24)

Membrane reshaping by micrometric curvature sensitive septin filaments

Nature communications : DOI : 10.1038/s41467-019-08344-5 Learn more
Summary

Septins are cytoskeletal filaments that assemble at the inner face of the plasma membrane.They are localized at constriction sites and impact membrane remodeling. We report in vitro tools to examine how yeast septins behave on curved and deformable membranes. Septins reshape the membranes of Giant Unilamellar Vesicles with the formation of periodic spikes, while flattening smaller vesicles. We show that membrane deformations are associated to preferential arrangement of Septin filaments on specific curvatures. When binding to bilayers supported on custom-designed periodic wavy patterns displaying positive and negative micrometric radii of curvatures, septin filaments remain straight and perpendicular to the curvature of the convex parts, while bending negatively to follow concave geometries. Based on these results, we propose a theoretical model that describes the deformations and micrometric curvature sensitivity observed in vitro. The model captures the reorganizations of septin filaments throughout cytokinesis in vivo, providing mechanistic insights into cell division.

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Kelley LC, Chi Q, Cáceres R, Hastie E, Schindler AJ, Jiang Y, Matus DQ, Plastino J, Sherwood DR (2019 Jan 24)

Adaptive F-actin polymerization and localized ATP production drive basement membrane invasion in the absence of MMPs

Developmental Cell : 48 : 313-328 : DOI : 10.1016/j.devcel.2018.12.018 Learn more
Summary

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Year of publication 2018

McHugh T, Zou J, Volkov VA, Bertin A, Rappsilber J, Dogterom M, Welburn JPI (2018 Dec 21)

The depolymerase activity of MCAK shows graded response to Aurora B kinase phosphorylation through allosteric regulation.

journal of cell science : DOI : 10.1242/jcs.228353 Learn more
Summary

Kinesin-13 motors regulate precise microtubule dynamics and limit microtubule length throughout metazoans by depolymerizing microtubule ends. Recently, MCAK has been proposed to undergo large conformational changes during its catalytic cycle, as it switches from solution to bound state. Here, we reveal that MCAK has a compact conformation in solution using crosslinking and electron microscopy. When MCAK is bound to the microtubule ends, it adopts an extended conformation with the N terminus and neck region of MCAK interacting with the microtubule. Interestingly, the region of MCAK that interacts with the microtubule is the region phosphorylated by Aurora B and contains an EB-binding motif. The level of phosphorylation of the N terminus results in a graded microtubule depolymerase activity. Here we show the N terminus of MCAK forms a platform to integrate Aurora B kinase downstream signals and in response fine-tunes its depolymerase activity during mitosis. We propose that this allosteric control mechanism allows decoupling of the N terminus from the motor domain of MCAK to allow MCAK depolymerase activity at kinetochores.

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Kutscher LM, Keil W, Shaham S (2018 Oct 22)

RAB-35 and ARF-6 GTPases Mediate Engulfment and Clearance Following Linker Cell-Type Death

Developmental Cell : 47 : 222-238 : DOI : 10.1016/j.devcel.2018.08.015 Learn more
Summary

Clearance of dying cells is essential for development and homeostasis. Conserved genes mediate apoptotic cell removal, but whether these genes control non-apoptotic cell removal is a major open question. Linker cell-type death (LCD) is a prevalent non-apoptotic developmental cell death process with features conserved from C. elegans to vertebrates. Using microfluidics-based long-term in vivo imaging, we show that unlike apoptotic cells, the C. elegans linker cell, which dies by LCD, is competitively phagocytosed by two neighboring cells, resulting in cell splitting. Subsequent cell elimination does not require apoptotic engulfment genes. Rather, we find that RAB-35 GTPase is a key coordinator of competitive phagocytosis onset and cell degradation. RAB-35 binds CNT-1, an ARF-6 GTPase activating protein, and removes ARF-6, a degradation inhibitor, from phagosome membranes. This facilitates phosphatidylinositol-4,5-bisphosphate removal from phagosome membranes, promoting phagolysosome maturation. Our studies suggest that RAB-35 and ARF-6 drive a conserved program eliminating cells dying by LCD.

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Coscoy S, Baiz S, Octon J, Rhoné B, Perquis L, Tseng Q, Amblard F, Semetey V. (2018 Oct 16)

Microtopographies control the development of basal protrusions in epithelial sheets

Biointerphases : 13 : 041003 : DOI : 10.1116/1.5024601 Learn more
Summary

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Venzac B, Madoun R, Benarab T, Monnier S, Cayrac F, Myram S, Leconte L, Amblard F, Viovy JL, Descroix S, Coscoy S (2018 Oct 16)

Engineering small tubes with changes in diameter for the study of kidney cell organization

Biomicrofluidics : 12 : 024114 : DOI : 10.1063/1.5025027 Learn more
Summary

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Bipul R Acharya, Alexander Nestor-Bergmann, Xuan Liang, Shafali Gupta, Kinga Duszyc, Estelle Gauquelin, Guillermo A Gomez, Srikanth Budnar, Philippe Marcq, Oliver E Jensen, Zev Bryant, Alpha S Yap (2018 Oct 16)

A Mechanosensitive RhoA Pathway that Protects Epithelia against Acute Tensile Stress.

Developmental cell : DOI : S1534-5807(18)30776-7 Learn more
Summary

Adherens junctions are tensile structures that couple epithelial cells together. Junctional tension can arise from cell-intrinsic application of contractility or from the cell-extrinsic forces of tissue movement. Here, we report a mechanosensitive signaling pathway that activates RhoA at adherens junctions to preserve epithelial integrity in response to acute tensile stress. We identify Myosin VI as the force sensor, whose association with E-cadherin is enhanced when junctional tension is increased by mechanical monolayer stress. Myosin VI promotes recruitment of the heterotrimeric Gα12 protein to E-cadherin, where it signals for p114 RhoGEF to activate RhoA. Despite its potential to stimulate junctional actomyosin and further increase contractility, tension-activated RhoA signaling is necessary to preserve epithelial integrity. This is explained by an increase in tensile strength, especially at the multicellular vertices of junctions, that is due to mDia1-mediated actin assembly.

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Blanch-Mercader C., Yashunsky V., Garcia S., Duclos G., Giomi L., Silberzan P. (2018 Oct 9)

Turbulent dynamics of epithelial cell cultures

Phys. Rev. Lett. : 120 : 208001 : DOI : 10.1103/PhysRevLett.120.208101 Learn more
Summary

We investigate the large length and long time scales collective flows and structural rearrangements within in vitro human bronchial epithelial cell (HBEC) cultures. Activity-driven collective flows result in ensembles of vortices randomly positioned in space. By analyzing a large population of vortices, we show that their area follows an exponential law with a constant mean value and their rotational frequency is size independent, both being characteristic features of the chaotic dynamics of active nematic suspensions. Indeed, we find that HBECs self- organize in nematic domains of several cell lengths. Nematic defects are found at the interface between domains with a total number that remains constant due to the dynamical balance of nucleation and annihilation events. The mean velocity fields in the vicinity of defects are well described by a hydrodynamic theory of extensile active nematics.

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Duclos G., Blanch-Mercader C., Yashunsky V., Salbreux G., Joanny J.-F., Prost J., Silberzan P. (2018 Oct 3)

Spontaneous shear flow in confined cellular nematics

Nature Physics : DOI : 10.1038/s41567-018-0099-7 Learn more
Summary

In embryonic development or tumour evolution, cells often migrate collectively within confining tracks defined by their microenvironment1,2. In some of these situations, the displacements within a cell strand are antiparallel3, giving rise to shear flows. However, the mechanisms underlying these spontaneous flows remain poorly understood. Here, we show that an ensemble of spindle-shaped cells plated in a well-defined stripe spontaneously develops a shear flow whose characteristics depend on the width of the stripe. On wide stripes, the cells self-organize in a nematic phase with a director at a well-defined angle with the stripe’s direction, and develop a shear flow close to the stripe’s edges. However, on stripes narrower than a critical width, the cells perfectly align with the stripe’s direction and the net flow vanishes. A hydrodynamic active gel theory provides an understanding of these observations and identifies the transition between the non-flowing phase oriented along the stripe and the tilted phase exhibiting shear flow as a Fréedericksz transition driven by the activity of the cells. This physical theory is grounded in the active nature of the cells and based on symmetries and conservation laws, providing a generic mechanism to interpret in vivo antiparallel cell displacements.

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Feng-Ching Tsai*, Aurelie Bertin*, Hugo Bousquet, John Manzi, Yosuke Senju, Meng-Chen Tsai, Laura Picas, Stephanie Miserey-Lenkei, Pekka Lappalainen, Emmanuel Lemichez, Evelyne Coudrier*, Patricia Bassereau* (2018 Sep 30)

Ezrin enrichment on curved membranes requires a specific conformation or interaction with a curvature-sensitive partner.

elife : 7 : e37262 : DOI : 10.7554/eLife.37262 Learn more
Summary

One challenge in cell biology is to decipher the biophysical mechanisms governing protein enrichment on curved membranes and the resulting membrane deformation. The ERM protein ezrin is abundant and associated with cellular membranes that are flat, positively or negatively curved. Using in vitro and cell biology approaches, we assess mechanisms of ezrin’s enrichment on curved membranes. We evidence that wild-type ezrin (ezrinWT) and its phosphomimetic mutant T567D (ezrinTD) do not deform membranes but self-assemble anti-parallelly, zipping adjacent membranes. EzrinTD’s specific conformation reduces intermolecular interactions, allows binding to actin filaments, which reduces membrane tethering, and promotes ezrin binding to positively-curved membranes. While neither ezrinTD nor ezrinWT senses negative curvature alone, we demonstrate that interacting with curvature-sensing I-BAR-domain proteins facilitates ezrin enrichment in negatively-curved membrane protrusions. Overall, our work demonstrates that ezrin can tether membranes, or be targeted to curved membranes, depending on conformations and interactions with actin and curvature-sensing binding partners.

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