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- Pour toute publication de résultats ayant reçu l’aide de l’IPGG (présence dans les locaux de l’IPGG, passage sur la plateforme technologique de l’IPGG, collaboration inter équipes IPGG, lié à une bourse doctorale ou postdoctorale IPGG, ou encore utilisation des espaces communs), il vous faut indiquer  cette phrase « Ce travail a été réalisé avec le soutien du laboratoire d’excellence Institut Pierre-Gilles de Gennes (programme Investissements d’avenir ANR-10-IDEX-0001-02 PSL et ANR-10-LABX-31). » / « This work has received the support of "Institut Pierre-Gilles de Gennes" (laboratoire d’excellence, “Investissements d’avenir” program ANR-10-IDEX-0001-02 PSL and ANR-10-LABX-31.). ».

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Amination of Cyclohexane by Dielectric Barrier Discharge Processing in a Continuous Flow Microreactor: Experimental and Simulation Studies
Aurélien Lepoetre, Stéphanie Ognier, Mengxue Zhang, Julien Wengler, Safwan Al Ayoubi, Cyril Ollivier, Louis Fensterbank, Xavier Duten, Michael Tatoulian
Plasma Chemistry and Plasma Processing - - DOI: 10.1007/s11090-020-10140-9 - 2020
A miniaturized flow device has been developed to combine microfluidics technology and plasma process. In this microreactor, atmospheric pressure dielectric barrier discharges are generated in a gas in contact with a liquid phase. This study was conducted with plasma generated in ammonia in contact with a flow of liquid cyclohexane. Cyclohexylamine was synthesized with a good selectivity, and the process can be implemented to improve conversion and effectiveness. Numerical simulations confirmed that NH2 radicals are generated in the plasma and react with cyclohexyls radicals to achieve the reaction, giving a selectivity of 50% and a total molar conversion of 20% of cyclohexane. The effects of voltage and frequency on the selectivity and the experimental conversion rate were studied and discussed.
Characterization of home-made graphite/PDMS microband electrodes for amperometric detection in an original reusable glass-NOA®-PDMS electrophoretic microdevice
J.Gouyon F.d’Orlyé S.Griveau F.Bedioui A.Varenne
ELSEVIER - 329 135164 - doi.org/10.1016/j.electacta.2019.135164 - 2020
A new dismountable and reusable microchip for electrophoretic separation coupled to amperometric detection was developed. For this purpose, a new home made three-microbands electrode system was developed and microfabricated based on screen-printing for the inclusion of graphite/polydimethylsiloxane (C-PDMS) composite in microchannels down to 30 μm width. The composition of the composite as well as the fabrication methodology were optimized for an easy handling and an optimized electrochemical behavior. The electrochemical characterization of this composite material was first performed in bulk format (disc-shaped electrode, 6 mm diameter). It was then transposed to the micrometric scale for its integration in an original glass-NOA81®-PDMS microfluidic device allowing for reversible sealing. The microband electrodes were characterized by scanning electron microcopy and cyclic voltammetry, illustrating a good control of the microelectrode width. Then, the analytical performances of the C-PDMS composite microelectrodes were evaluated using Ru(NH3)63+ and FcMeOH as model electroactive molecules. The electrophoretic separation and quantitation of Ru(NH3)63+ were then performed in a background electrolyte made of hydrochloric acid and sodium chloride, leading to a LOD and a LOQ of 3.4 μmol L−1 and 11.3 μmol L−1, respectively. The re-openable NOA-based microdevice permits to regenerate the electrode surface by simply repositioning the microband on a new spot, allowing for robust analysis in a reusable system.
Hydrogel Matrix-Grafted Impedimetric Aptasensors for the Detection of Diclofenac
G. S. Kassahun, S. Griveau, S. Juillard, J. Champavert, A. Ringuedé, B. Bresson, Y. Tran*, F. Bedioui, and C. Slim
Langmuir - 36(4) 827–836 - doi.org/10.1021/acs.langmuir.9b02031 - 2020
Driven by the growing concern about the release of untreated emerging pollutants and the need for determining small amounts of these pollutants present in the environment, novel biosensors dedicated to molecular recognition are developed. We have designed biosensors using a novel class of grafted polymers, surface-attached hydrogel thin films, on conductive transducers as a biocompatible matrix for biomolecule immobilization. We showed that they can be dedicated to the molecular recognition of diclofenac (DCL). The immobilization of the aptamer onto surface-attached hydrogel thin films by covalent attachment provides a biodegradable shelter, providing the aptamer with excellent environments to preserve its active and functional structure while allowing the detection of DCL. The grafting of the aptamer is obtained using the formation of amide bonds via the activation of carboxylic acid groups of the poly(acrylic acid) hydrogel thin film. For improved sensitivity and higher stability of the sensor, a high density of the immobilized aptamer is enabled. The aptamer-modified electrode was then incubated with DCL solutions at different concentrations. The performances of the aptasensor were investigated by electrochemical impedance spectroscopy. The change in charge-transfer resistance was found to be linear with DCL concentration in the 30 pM to 1 μM range. The detection limit was calculated to be 0.02 nM. The improvement of the limit of detection can be mainly attributed to the three-dimensional environment of the hydrogel matrix which improves the grafting density of the aptamer and the affinity of the aptamer to DCL.
Polarization of Myosin II Refines Tissue Material Properties to Buffer Mechanical Stress
Maria Duda, Natalie J Kirkland, Nargess Khalilgharibi, Melda Tozluoglu , Alice C Yuen , Nicolas Carpi , Anna Bove , Matthieu Piel , Guillaume Charras , Buzz Baum , Yanlan Mao
Dev Cell - 48(2) 245-260.e7 - DOI: 10.1016/j.devcel.2018.12.020 - 2020
mTOR activation is essential and sufficient to cause polycystic kidneys in Tuberous Sclerosis Complex (TSC) and other genetic disorders. In disease models, a sharp increase of proliferation and cyst formation correlates with a dramatic loss of oriented cell division (OCD). We find that OCD distortion is intrinsically due to S6 kinase 1 (S6K1) activation. The concomitant loss of S6K1 in Tsc1-mutant mice restores OCD but does not decrease hyperproliferation, leading to non-cystic harmonious hyper growth of kidneys. Mass spectrometry-based phosphoproteomics for S6K1 substrates revealed Afadin, a known component of cell-cell junctions required to couple intercellular adhesions and cortical cues to spindle orientation. Afadin is directly phosphorylated by S6K1 and abnormally decorates the apical surface of Tsc1-mutant cells with E-cadherin and α-catenin. Our data reveal that S6K1 hyperactivity alters centrosome positioning in mitotic cells, affecting oriented cell division and promoting kidney cysts in conditions of mTOR hyperactivity.
Mechanochemical Crosstalk Produces Cell-Intrinsic Patterning of the Cortex to Orient the Mitotic Spindle.
Andrea Dimitracopoulos, Pragya Srivastava, Agathe Chaigne, Zaw Win, Roie Shlomovitz, Oscar M Lancaster, Maël Le Berre, Matthieu Piel, Kristian Franze, Guillaume Salbreux, Buzz Baum
Current biology - - DOI : S0960-9822(20)30984-2 - 2020
Proliferating animal cells are able to orient their mitotic spindles along their interphase cell axis, setting up the axis of cell division, despite rounding up as they enter mitosis. This has previously been attributed to molecular memory and, more specifically, to the maintenance of adhesions and retraction fibers in mitosis [1-6], which are thought to act as local cues that pattern cortical Gαi, LGN, and nuclear mitotic apparatus protein (NuMA) [3, 7-18]. This cortical machinery then recruits and activates Dynein motors, which pull on astral microtubules to position the mitotic spindle. Here, we reveal a dynamic two-way crosstalk between the spindle and cortical motor complexes that depends on a Ran-guanosine triphosphate (GTP) signal [12], which is sufficient to drive continuous monopolar spindle motion independently of adhesive cues in flattened human cells in culture. Building on previous work [1, 12, 19-23], we implemented a physical model of the system that recapitulates the observed spindle-cortex interactions. Strikingly, when this model was used to study spindle dynamics in cells entering mitosis, the chromatin-based signal was found to preferentially clear force generators from the short cell axis, so that cortical motors pulling on astral microtubules align bipolar spindles with the interphase long cell axis, without requiring a fixed cue or a physical memory of interphase shape. Thus, our analysis shows that the ability of chromatin to pattern the cortex during the process of mitotic rounding is sufficient to translate interphase shape into a cortical pattern that can be read by the spindle, which then guides the axis of cell division.
mTOR and S6K1 drive polycystic kidney by the control of Afadin-dependent oriented cell division
Martina Bonucci, Nicolas Kuperwasser, Serena Barbe, Vonda Koka, Delphine de Villeneuve, Chi Zhang, Nishit Srivastava, Xiaoying Jia, Matthew P Stokes, Frank Bienaimé, Virginie Verkarre, Jean Baptiste Lopez, Fanny Jaulin, Marco Pontoglio, Fabiola Terzi, Be
Nature Communications - - DOI : 10.1038/s41467-020-16978-z - 2020
mTOR activation is essential and sufficient to cause polycystic kidneys in Tuberous Sclerosis Complex (TSC) and other genetic disorders. In disease models, a sharp increase of proliferation and cyst formation correlates with a dramatic loss of oriented cell division (OCD). We find that OCD distortion is intrinsically due to S6 kinase 1 (S6K1) activation. The concomitant loss of S6K1 in Tsc1-mutant mice restores OCD but does not decrease hyperproliferation, leading to non-cystic harmonious hyper growth of kidneys. Mass spectrometry-based phosphoproteomics for S6K1 substrates revealed Afadin, a known component of cell-cell junctions required to couple intercellular adhesions and cortical cues to spindle orientation. Afadin is directly phosphorylated by S6K1 and abnormally decorates the apical surface of Tsc1-mutant cells with E-cadherin and α-catenin. Our data reveal that S6K1 hyperactivity alters centrosome positioning in mitotic cells, affecting oriented cell division and promoting kidney cysts in conditions of mTOR hyperactivity.
The nucleus acts as a ruler tailoring cell responses to spatial constraints
A. J. Lomakin, C. J. Cattin, D. Cuvelier, Z. Alraies, M. Molina. Nader, N. Sri
Science - 6514 370 - DOI: 10.1126/science.aba2894 - 2020
Single cells continuously experience and react to mechanical challenges in three-dimensional tissues. Spatial constraints in dense tissues, physical activity, and injury all impose changes in cell shape. How cells can measure shape deformations to ensure correct tissue development and homeostasis remains largely unknown (see the Perspective by Shen and Niethammer). Working independently, Venturini et al. and Lomakin et al. now show that the nucleus can act as an intracellular ruler to measure cellular shape variations. The nuclear envelope provides a gauge of cell deformation and activates a mechanotransduction pathway that controls actomyosin contractility and migration plasticity. The cell nucleus thereby allows cells to adapt their behavior to the local tissue microenvironment.
ATR is essential for preservation of cell mechanics and nuclear integrity during interstitial migration
Gururaj Rao Kidiyoor, Qingsen Li, Giulia Bastianello, Christopher Bruhn, Irene Giovannetti, Adhil Mohamood, Galina V. Beznoussenko, Alexandre Mironov, Matthew Raab, Matthieu Piel, Umberto Restuccia, Vittoria Matafora, Angela Bachi, Sara
Nature Communications - 11 4828 - https://doi.org/10.1038/s41467-020-18580-9 - 2020
ATR responds to mechanical stress at the nuclear envelope and mediates envelope-associated repair of aberrant topological DNA states. By combining microscopy, electron microscopic analysis, biophysical and in vivo models, we report that ATR-defective cells exhibit altered nuclear plasticity and YAP delocalization. When subjected to mechanical stress or undergoing interstitial migration, ATR-defective nuclei collapse accumulating nuclear envelope ruptures and perinuclear cGAS, which indicate loss of nuclear envelope integrity, and aberrant perinuclear chromatin status. ATR-defective cells also are defective in neuronal migration during development and in metastatic dissemination from circulating tumor cells. Our findings indicate that ATR ensures mechanical coupling of the cytoskeleton to the nuclear envelope and accompanying regulation of envelope-chromosome association. Thus the repertoire of ATR-regulated biological processes extends well beyond its canonical role in triggering biochemical implementation of the DNA damage response.

Sliding walls: a new paradigm for fluidic actuation and protocol implementation in microfluidics
Venzac, Bastien; Liu, Yang; Ferrante, Ivan; Vargas, Pablo; Yamada, Ayako; Courson, Rémi; Verhulsel, Marine; Malaquin, Laurent; Viovy, Jean-Louis; Descroix, Stéphanie
Microsystems & Nanoengineering - 6(1) 18 - DOI: 10.1038/s41378-019-0125-7 - 2020
Currently, fluidic control in microdevices is mainly achieved either by external pumps and valves, which are expensive and bulky, or by valves integrated in the chip. Numerous types of internal valves or actuation methods have been proposed, but they generally impose difficult compromises between performance and fabrication complexity. We propose here a new paradigm for actuation in microfluidic devices based on rigid or semi-rigid walls with transversal dimensions of hundreds of micrometres that are able to slide within a microfluidic chip and to intersect microchannels with hand-driven or translation stage-based actuation. With this new concept for reconfigurable microfluidics, the implementation of a wide range of functionalities was facilitated and allowed for no or limited dead volume, low cost and low footprint. We demonstrate here several fluidic operations, including on/off or switch valving, where channels are blocked or reconfigured depending on the sliding wall geometry. The valves sustain pressures up to 30 kPa. Pumping and reversible compartmentalisation of large microfluidic chambers were also demonstrated. This last possibility was applied to a "4D" migration assay of dendritic cells in a collagen gel. Finally, sliding walls containing a hydrogel-based membrane were developed and used to concentrate, purify and transport biomolecules from one channel to another, such functionality involving complex fluidic transport patterns not possible in earlier microfluidic devices. Overall, this toolbox is compatible with "soft lithography" technology, allowing easy implementation within usual fabrication workflows for polydimethylsiloxane chips. This new technology opens the route to a variety of microfluidic applications, with a focus on simple, hand-driven devices for point-of-care or biological laboratories with low or limited equipment and resources.
Oncogenic Signaling Alters Cell Shape and Mechanics to Facilitate Cell Division under Confinement
Helen K.Matthews, Sushila Ganguli, KatarzynaPlak, Anna V.Taubenberger, Zaw Win, Max Williamson, Matthieu Piel, Jochen Guck, Buzz Baum
Dev Cell - 52(5) 563-573.e3 - doi.org/10.1016/j.devcel.2020.01.004 - 2020
To divide in a tissue, both normal and cancer cells become spherical and mechanically stiffen as they enter mitosis. We investigated the effect of oncogene activation on this process in normal epithelial cells. We found that short-term induction of oncogenic RasV12 activates downstream mitogen-activated protein kinase (MEK-ERK) signaling to alter cell mechanics and enhance mitotic rounding, so that RasV12-expressing cells are softer in interphase but stiffen more upon entry into mitosis. These RasV12-dependent changes allow cells to round up and divide faithfully when confined underneath a stiff hydrogel, conditions in which normal cells and cells with reduced levels of Ras-ERK signaling suffer multiple spindle assembly and chromosome segregation errors. Thus, by promoting cell rounding and stiffening in mitosis, oncogenic RasV12 enables cells to proliferate under conditions of mechanical confinement like those experienced by cells in crowded tumors.

584 publications.