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Synthesis and Characterization of Molecularly Imprinted Polymers for the Selective Extraction of Carbamazepine and Analogs from Human Urine Samples
Laboratoire Sciences Analytiques Bioanalytiques et Miniaturisation - 287–295
Chromatographia - 82 287–295 - doi:10.1007/s10337-018-3680-4 - 2019
Two molecularly imprinted polymers (MIPs) were synthesized according to a previous work from our group dealing with the extraction of carbamazepine from environmental water. The potential of these MIPs, which differ in the nature of the monomer used for their synthesis, to selectively extract the drugs carbamazepine and oxcarbazepine and the metabolite 10,11-epoxycarbamazepine was first studied in spiked pure water, and high selectivity was obtained with both MIPs for the three target molecules in this pure medium. This selectivity was maintained when applying one of the MIPs to urine samples. Indeed, extraction recoveries were higher than 82% on the MIP and lower than 20% on the corresponding non-imprinted polymer used as a control. The repeatability of the extraction procedure applied to urine was also demonstrated, with relative standard deviation (RSD) below 20% for extraction recoveries of the three targets at a spiking level of 20 ng L−1. Limits of quantification between 1 and 7 ng L−1 were determined for urine samples using the MIP as extraction sorbent combined with LC–MS analysis. The potential of the MIP was compared to that of the Oasis HLB sorbent. This study shows that the MIP constitutes a powerful tool for avoiding matrix effects encountered in the quantification of the target molecules in urine samples extracted on Oasis HLB.
Contribution of proteases and cellulases produced by solid-state fermentation to the improvement of corn ethanol production
Laboratoire Spectrométrie de masse biologique et protéomique - Anaïs Guillaume, Aurore Thorigné, Yoann Carré, Joëlle Vinh and Loïc Levavasseur
Biosci Rep - 6 7 - - 2019
By cultivating a strain of Aspergillus tubingensis on agro-industrial by-products using solid-state fermentation technology, a biocatalyst containing more than 130 different enzymes was obtained. The enzymatic complex was composed mainly of hydrolases, among which a protease, an aspergillopepsin, accounted for more than half of the total proteins. Cell-wall-degrading enzymes such as pectinases, cellulases and hemicellulases were also highly represented. Adding the biocatalyst to corn mash at 1 kg/T corn allowed to significantly improve ethanol production performances. The final ethanol concentration was increased by 6.8% and the kinetics was accelerated by 14 h. The aim of this study was to identify the enzymes implicated in the effect on corn ethanol production. By fractionating the biocatalyst, the particular effect of the major enzymes was investigated. Experiments revealed that, together, the protease and two cellulolytic enzymes (an endoglucanase and a β-glucosidase) were responsible for 80% of the overall effect of the biocatalyst. Nevertheless, the crude extract of the biocatalyst showed greater impact than the combination of up to seven purified enzymes, demonstrating the complementary enzymatic complex obtained by solid-state fermentation. This technology could, therefore, be a relevant natural alternative to the use of GMO-derived enzymes in the ethanol industry.
Benzoquinone, a leukemogenic metabolite of benzene, catalytically inhibits the protein tyrosine phosphatase PTPN2 and alters STAT1 signaling
Laboratoire Spectrométrie de masse biologique et protéomique - Romain Duval, Linh-Chi Bui, Cécile Mathieu, Qing Nian, Jérémy Berthelet, Ximing Xu, Iman Haddad, Joelle Vinh, Jean-Marie Dupret, Florent Busi, Fabien Guidez, Christine Chomienne, and Fernando Rodrigues-Lima
J Biol Chem - 294(33) 12483–12494 - doi: 10.1074/jbc.RA119.008666 - 2019
Protein tyrosine phosphatase, nonreceptor type 2 (PTPN2) is mainly expressed in hematopoietic cells, where it negatively regulates growth factor and cytokine signaling. PTPN2 is an important regulator of hematopoiesis and immune/inflammatory responses, as evidenced by loss-of-function mutations of PTPN2 in leukemia and lymphoma and knockout mice studies. Benzene is an environmental chemical that causes hematological malignancies, and its hematotoxicity arises from its bioactivation in the bone marrow to electrophilic metabolites, notably 1,4-benzoquinone, a major hematotoxic benzene metabolite. Although the molecular bases for benzene-induced leukemia are not well-understood, it has been suggested that benzene metabolites alter topoisomerases II function and thereby significantly contribute to leukemogenesis. However, several studies indicate that benzene and its hematotoxic metabolites may also promote the leukemogenic process by reacting with other targets and pathways. Interestingly, alterations of cell-signaling pathways, such as Janus kinase (JAK)/signal transducer and activator of transcription (STAT), have been proposed to contribute to benzene-induced malignant blood diseases. We show here that 1,4-benzoquinone directly impairs PTPN2 activity. Mechanistic and kinetic experiments with purified human PTPN2 indicated that this impairment results from the irreversible formation (kinact = 645 m−1·s−1) of a covalent 1,4-benzoquinone adduct at the catalytic cysteine residue of the enzyme. Accordingly, cell experiments revealed that 1,4-benzoquinone exposure irreversibly inhibits cellular PTPN2 and concomitantly increases tyrosine phosphorylation of STAT1 and expression of STAT1-regulated genes. Our results provide molecular and cellular evidence that 1,4-benzoquinone covalently modifies key signaling enzymes, implicating it in benzene-induced malignant blood diseases.

Investigation of serum proteome homeostasis during radiation therapy by a quantitative proteomics approach
Laboratoire Spectrométrie de masse biologique et protéomique - Amira Ouerhani, Giovanni Chiappetta, Oussema Souiai, Halima Mahjoubi, Joelle Vinh
Biosci Rep - 39(7) - doi: 10.1042/BSR20182319 - 2019
The purpose of the present study is to analyze the serum proteome of patients receiving Radiation Therapy (RT) at different stages of their treatment to discovery candidate biomarkers of the radiation-induced skin lesions and the molecular pathways underlying the radiation signatures. Six stages of RT treatment were monitored from patients treated because of brain cancer: before starting the treatment, during the treatment (four time points), and at 4 weeks from the last RT dose. Serum samples were analyzed by a proteomics approach based on the Data Independent Acquisition (DIA) mass spectrometry (MS). RT induced clear changes in the expression levels of 36 serum proteins. Among these, 25 proteins were down- or up-regulated significantly before the emergence of skin lesions. Some of these were still deregulated after the completion of the treatment. Few days before the appearance of the skin lesions, the levels of some proteins involved in the wound healing processes were down-regulated. The pathway analysis indicated that after partial body irradiation, the expression levels of proteins functionally involved in the acute inflammatory and immune response, lipoprotein process and blood coagulation, were deregulated.

Global host molecular perturbations upon in situ loss of bacterial endosymbionts in the deep-sea mussel Bathymodiolus azoricus assessed using proteomics and transcriptomics
Laboratoire Spectrométrie de masse biologique et protéomique - Camille Détrée, Iman Haddad, Emmanuelle Demey-Thomas, Joëlle Vinh, François H Lallier, Arnaud Tanguy, Jean Mary
BMC Genomics - 20(1) 109 - doi: 10.1186/s12864-019-5456-0 - 2019
Background: Colonization of deep-sea hydrothermal vents by most invertebrates was made efficient through their adaptation to a symbiotic lifestyle with chemosynthetic bacteria, the primary producers in these ecosystems. Anatomical adaptations such as the establishment of specialized cells or organs have been evidenced in numerous deep-sea invertebrates. However, very few studies detailed global inter-dependencies between host and symbionts in these ecosystems. In this study, we proposed to describe, using a proteo-transcriptomic approach, the effects of symbionts loss on the deep-sea mussel Bathymodiolus azoricus' molecular biology. We induced an in situ depletion of symbionts and compared the proteo-transcriptome of the gills of mussels in three conditions: symbiotic mussels (natural population), symbiont-depleted mussels and aposymbiotic mussels.

Results: Global proteomic and transcriptomic results evidenced a global disruption of host machinery in aposymbiotic organisms. We observed that the total number of proteins identified decreased from 1118 in symbiotic mussels to 790 in partially depleted mussels and 761 in aposymbiotic mussels. Using microarrays we identified 4300 transcripts differentially expressed between symbiont-depleted and symbiotic mussels. Among these transcripts, 799 were found differentially expressed in aposymbiotic mussels and almost twice as many in symbiont-depleted mussels as compared to symbiotic mussels. Regarding apoptotic and immune system processes - known to be largely involved in symbiotic interactions - an overall up-regulation of associated proteins and transcripts was observed in symbiont-depleted mussels.

Conclusion: Overall, our study showed a global impairment of host machinery and an activation of both the immune and apoptotic system following symbiont-depletion. One of the main assumptions is the involvement of symbiotic bacteria in the inhibition and regulation of immune and apoptotic systems. As such, symbiotic bacteria may increase their lifespan in gill cells while managing the defense of the holobiont against putative pathogens.

Keywords: Chemoautotrophic symbiosis; Hydrothermal vent; In situ experiment; Mutualism; Proteo-transcriptomics.
Physicochemical Characterization of Phthalocyanine-Functionalized Quantum Dots by Capillary Electrophoresis Coupled to a LED Fluorescence Detector
Laboratoire Synthèse Electrochimie Imagerie et Systèmes Analytiques - Ramírez-García G, d'Orlyé F, Nyokong T, Bedioui F, Varenne A
Methods in Molecular Biology (Clifton, N.J.) - 2000 373-385 - DOI: 10.1007/978-1-4939-9516-5_23 - 2019
Capillary zone electrophoresis (CZE) complemented with Taylor Dispersion Analysis-CE (TDA-CE) was developed to physicochemically characterize phthalocyanine-capped core/shell/shell quantum dots (QDs) at various pH and ionic strengths. An LED-induced fluorescence detector was used to specifically detect the QDs. The electropherograms and taylorgrams allowed calculating the phthalocyanine-QDs (Pc-QDs) ζ-potential and size, respectively, and determining the experimental conditions for colloidal stability. This methodology allowed evidencing either a colloidal stability or an aggregation state according to the background electrolytes nature. The calculated ζ-potential values of Pc-QDs decreased when ionic strength increased, being well correlated with the aggregation of the nanoconjugates at elevated salt concentrations. For the same reason, the hydrodynamic diameter of Pc-QDs increased with increasing background electrolyte ionic strength. The use of electrokinetic methodologies has provided insights into the colloidal stability of the photosensitizer-functionalized QDs in physiologically relevant solutions and, thereby, its usefulness for improving their design and applications for photodynamic therapy.
Characterization of New Cyclic D,L-α-Alternate Amino Acid Peptides by Capillary Electrophoresis Coupled to Electrospray Ionization Mass Spectrometry.
Laboratoire Synthèse Electrochimie Imagerie et Systèmes Analytiques - Cortez-Díaz, d'Orlyé F, Varenne A
Methods in Molecular Biology (Clifton, N.J.) - 1855 315-326 - DOI: 10.1007/978-1-4939-8793-1_27 - 2019
The self-assembly of peptide nanotubes (PNTs) depends on the structure and chemistry of cyclic peptide (CP) monomers, impacting on their properties, which makes the choice of their monomers and their characterization a high challenge. For this purpose, we developed for the first time a capillary electrophoresis coupled to electrospray ionization mass spectrometry (CE-ESI-MS) methodology and characterized a set of eight original CP sequences of 8, 10, and 12 D,L-α-alternate amino acids with a controlled internal diameter (from 7 to 13 Å) and various properties (diameter, global surface charge, hydrophobicity). This new CE-ESI-MS methodology allows verifying the structure, the purity, as well as the stability (when stored during several months) of interesting potential precursors for PNTs that could be employed as nanoplatforms in diagnostics or pseudo sieving tools for separation purposes.
A Simple Efficient Click Synthesis of Novel Crown Ethers Containing 1,2,3-Triazole Moieties
Laboratoire Synthèse Electrochimie Imagerie et Systèmes Analytiques - H. Elamari, A. Ouerghui, F. Ammari & C. Girard
Russian Journal of Organic Chemistry - 55 1785-1790 - - 2019
Novel crown ether derivative containing 1,4-disubstituted-1,2,3-triazole moieties were synthesized. At the first step of the synthesis 4,13-diaza-18-crown-6 and 4-aminobenzo-15-crown-5 were converted into terminal alkynes, which were then subjected to copper(I)-catalyzed alkyne-azide coupling (CuAAC) in methylene chloride. This coupling reaction was performed according to the concept of click chemistry, using an Amberlyst A-21-supported copper(I) iodide catalyst
Surface functionalization of cyclic olefin copolymer by plasma‐enhanced chemical vapor deposition using atmospheric pressure plasma jet for microfluidic applications
Laboratoire Synthèse Electrochimie Imagerie et Systèmes Analytiques - Samantha Bourg Sophie Griveau Fanny d'Orlyé Michael Tatoulian Fethi Bedioui Cédric Guyon Anne Varenne
Plasma Process - 16 6 - - 2019
Lab‐On‐A‐Chips promise solutions for high throughput and specific analysis for environmental and health applications, with the challenge to develop materials allowing fast, easy, and cheap microfabrication and efficient surface treatment. Cyclic olefin copolymer (COC) is a promising thermoplastic, easily microfabricated for both rapid prototyping and low‐cost mass production of microfluidic devices but still needing efficient surface modification strategies. This study reports for the first time the optimization of an easy COC silica coating process by plasma‐enhanced chemical vapor deposition at atmospheric pressure with plasma jet and tetraethylorthosilicate as precursor, leading to a 158 ± 7 nm thickness and a 14‐day‐stability of hydrophilic properties for a COC‐embedded microchannel (100 µm), paving the way for a simplified and controlled COC surface modification.

Synthesis of new polymers containing 1,2,3-triazole units from poly(vinylchloride) via "click” chemistry catalyzed by copper iodide and its application in extraction of nitrates and metals contained in wastewater
Laboratoire Synthèse Electrochimie Imagerie et Systèmes Analytiques - Ouerghui Abid , Dardouri Mokthar , Sleimi Noomene , Bel Hadj Amor Abir , Ammari Faycel , Girard Christian
Baztech - - DOI - 2019
New polymers with potential application in a waste water purification from inorganic contaminants were synthesized via a chemical modification of poly(vinyl chloride) by "click” method based on copper(I)-catalyzed Huisgen reaction. The structure of the resulting polymers containing 1,4-disubstituted triazole units was confirmed by infrared spectroscopy (ATR-FTIR), nitrogen elemental analysis and differential thermal analysis (DTA). The obtained polymers were subsequently used in the elimination of nitrate ions and metalions from the wastewater of Beja region (Tunisia). It was found that new polymers were most efficient in capturing of zinc ions, the average extraction percentage of Zn2+ was 28%, while the average extraction percentage of nitrates did not exceed 12.5%. The selectivity of the binding of investigated ions can be arranged in the following order: Zn2+> NO3–> Ca2+> Mg2+.
Chemical Modification of Polystyrene Merrifield: Extraction of Zinc and Magnesium Located in Wastewater
Laboratoire Synthèse Electrochimie Imagerie et Systèmes Analytiques - Mokhtar Dardouri Hichem Elamari Fayçel Ammari
ELSEVIER - 5(3) 73 - DOI: 10.11648/j.ajpst.20190503.11 - 2019
In order to remove metals (Zn & Mg) located in wastewater, a new series of clickable polystyrene Merrifield grafted with azide and alkynes were synthesized and implicated in this domain. In a first step, we transformed the polystyrene Merrifield into the known Azidomethyl polystyrene, in a second step, a coupling reaction between the Azidomethyl polystyrene and dipropargylamine was realized for the synthesis of a new terminated polystyrene alkyne containing one unit of (1,4)-triazole. To increase the length of the chain grafted on the polystyrene Merrifield, several coupling reactions are applied, the main idea of this work was to increase the number of (1,2,3) –triazole units of this grafted chain. The click chemistry based on the Huygens’s reaction catalyzed by copper (I) was used in this synthesis, the new polymers containing (1,4)-disubstituted triazole are tested for the extraction of Mg and Zn located in wastewater. The structure of new obtained polymers was confirmed by infrared spectroscopy (ATR-FTIR), UV-visible spectroscopy and elemental analysis for nitrogen. Differential Thermal Analysis (DTA) and Thermo Gravimetric Analysis (TGA) were used to study crosslinking behavior of these polymers. This study shows a low selectivity of studied polymers for the retention of magnesium, while for the Zinc, the percentage removal was average, it’s in the order of 30%
Cobalt-Salen Catalyzed Electroreductive Alkylation of Activated Olefins
Laboratoire Synthèse Electrochimie Imagerie et Systèmes Analytiques - Sylvie Condon , Céline Cannes , and Fethi Bedioui
Journal of Chemistry - - - 2019
Cobalt-Salen mediated electroreductive and regioselective alkylation of electron deficient olefins is reported in one step in an undivided electrochemical cell, in the presence of an iron rod as sacrificial anode. Although the reactivity depends on the class of alkyl halides, the reported study offers a green and expeditious electrosynthetic route for Csp3-Csp3 bond formation in mild conditions. This study also confirms the possible formation of the heterobinuclear cobalt-Salen-iron complex previously reported as the effective catalyst.
Sign epistasis caused by hierarchy within signalling cascades.
Laboratoire Biochimie - Nghe P, Kogenaru M, Tans SJ.
Nat Commun - 9(1) 1451. - doi: 10.1038/s41467-018-03644-8 - 2018
Sign epistasis is a central evolutionary constraint, but its causal factors remain difficult to predict. Here we use the notion of parameterised optima to explain epistasis within a signalling cascade, and test these predictions in Escherichia coli. We show that sign epistasis arises from the benefit of tuning phenotypic parameters of cascade genes with respect to each other, rather than from their complex and incompletely known genetic bases. Specifically, sign epistasis requires only that the optimal phenotypic parameters of one gene depend on the phenotypic parameters of another, independent of other details, such as activating or repressing nature, position within the cascade, intra-genic pleiotropy or genotype. Mutational effects change sign more readily in downstream genes, indicating that optimising downstream genes is more constrained. The findings show that sign epistasis results from the inherent upstream-downstream hierarchy between signalling cascade genes, and can be addressed without exhaustive genotypic mapping.
Coupled catabolism and anabolism in autocatalytic RNA sets.
Laboratoire Biochimie - Arsène S, Ameta S, Lehman N, Griffiths AD, Nghe P.
Nucleic Acids Res. - 46(18) 9660-9666 - doi: 10.1093/nar/gky598. - 2018
The ability to process molecules available in the environment into useable building blocks characterizes catabolism in contemporary cells and was probably critical for the initiation of life. Here we show that a catabolic process in collectively autocatalytic sets of RNAs allows diversified substrates to be assimilated. We modify fragments of the Azoarcus group I intron and find that the system is able to restore the original native fragments by a multi-step reaction pathway. This allows in turn the formation of catalysts by an anabolic process, eventually leading to the accumulation of ribozymes. These results demonstrate that rudimentary self-reproducing RNA systems based on recombination possess an inherent capacity to assimilate an expanded repertoire of chemical resources and suggest that coupled catabolism and anabolism could have arisen at a very early stage in primordial living systems.
Selection Dynamics in Transient Compartmentalization.
Laboratoire Biochimie - Blokhuis A, Lacoste D, Nghe P, Peliti L
Phys. Rev. Lett. - 158101 120(15): - doi: 10.1371/journal.pcbi.1004972 - 2018
Transient compartments have been recently shown to be able to maintain functional replicators in the context of prebiotic studies. Here, we show that a broad class of selection dynamics is able to achieve this goal. We identify two key parameters, the relative amplification of nonactive replicators (parasites) and the size of compartments. These parameters account for competition and diversity, and the results are relevant to similar multilevel selection problems, such as those found in virus-host ecology and trait group selection.
Innate Immune Signals Induce Anterograde Endosome Transport Promoting MHC Class I Cross-Presentation.
Laboratoire Biologie cellulaire systémique de la polarité et de la division - Weimershaus M, Mauvais FX, Saveanu L, Adiko C, Babdor J, Abramova A, Montealegre S, Lawand M, Evnouchidou I, Huber KJ, Chadt A, Zwick M, Vargas P, Dussiot M, Lennon-Dumenil AM, Brocker T, Al-Hasani H, van Endert P.
Cell Reports - 24(13) 3568-3581 - doi: 10.1016/j.celrep.2018.08.041 - 2018
Both cross-presentation of antigens by dendritic cells, a key pathway triggering T cell immunity and immune tolerance, and survival of several pathogens residing in intracellular vacuoles are intimately linked to delayed maturation of vesicles containing internalized antigens and microbes. However, how early endosome or phagosome identity is maintained is incompletely understood. We show that Toll-like receptor 4 (TLR4) and Fc receptor ligation induces interaction of the GTPase Rab14 with the kinesin KIF16b mediating plus-end-directed microtubule transport of endosomes. As a result, Rab14 recruitment to phagosomes delays their maturation and killing of an internalized pathogen. Enhancing anterograde transport by overexpressing Rab14, promoting the GTP-bound Rab14 state, or inhibiting retrograde transport upregulates cross-presentation. Conversely, reducing Rab14 expression, destabilizing Rab14 endosomes, and inhibiting anterograde microtubule transport by Kif16b knockdown compromise cross-presentation. Therefore, regulation of early endosome trafficking by innate immune signals is a critical parameter in cross-presentation by dendritic cells.
Diversification of human plasmacytoid predendritic cells in response to a single stimulus
Laboratoire Biologie cellulaire systémique de la polarité et de la division - Alculumbre SG, Saint-André V1, Di Domizio J, Vargas P, Sirven P, Bost P, Maurin M, Maiuri P, Wery M, Roman MS, Savey L, Touzot M, Terrier B, Saadoun D, Conrad C, Gilliet M, Morillon A, Soumelis V.
Nat Immunol. - 19(1) 63-75 - doi: 10.1038/s41590-017-0012-z - 2018
Innate immune cells adjust to microbial and inflammatory stimuli through a process termed environmental plasticity, which links a given individual stimulus to a unique activated state. Here, we report that activation of human plasmacytoid predendritic cells (pDCs) with a single microbial or cytokine stimulus triggers cell diversification into three stable subpopulations (P1-P3). P1-pDCs (PD-L1+CD80-) displayed a plasmacytoid morphology and specialization for type I interferon production. P3-pDCs (PD-L1-CD80+) adopted a dendritic morphology and adaptive immune functions. P2-pDCs (PD-L1+CD80+) displayed both innate and adaptive functions. Each subpopulation expressed a specific coding- and long-noncoding-RNA signature and was stable after secondary stimulation. P1-pDCs were detected in samples from patients with lupus or psoriasis. pDC diversification was independent of cell divisions or preexisting heterogeneity within steady-state pDCs but was controlled by a TNF autocrine and/or paracrine communication loop. Our findings reveal a novel mechanism for diversity and division of labor in innate immune cells.
Spontaneous migration of cellular aggregates from giant keratocytes to running spheroids
Laboratoire Biologie cellulaire systémique de la polarité et de la division - Grégory Beaune, Carles Blanch-Mercader, Stéphane Douezan, Julien Dumond, David Gonzalez-Rodriguez, Damien Cuvelier, Thierry Ondarçuhu, Pierre Sens, Sylvie Dufour, Michael P. Murrell, and Françoise Brochard-Wyart
Cell Sci - 115 (51) 12926-12931 - - 2018
Despite extensive knowledge on the mechanisms that drive single-cell migration, those governing the migration of cell clusters, as occurring during embryonic development and cancer metastasis, remain poorly understood. Here, we investigate the collective migration of cell on adhesive gels with variable rigidity, using 3D cellular aggregates as a model system. After initial adhesion to the substrate, aggregates spread by expanding outward a cell monolayer, whose dynamics is optimal in a narrow range of rigidities. Fast expansion gives rise to the accumulation of mechanical tension that leads to the rupture of cell–cell contacts and the nucleation of holes within the monolayer, which becomes unstable and undergoes dewetting like a liquid film. This leads to a symmetry breaking and causes the entire aggregate to move as a single entity. Varying the substrate rigidity modulates the extent of dewetting and induces different modes of aggregate motion: “giant keratocytes,” where the lamellipodium is a cell monolayer that expands at the front and retracts at the back; “penguins,” characterized by bipedal locomotion; and “running spheroids,” for nonspreading aggregates. We characterize these diverse modes of collective migration by quantifying the flows and forces that drive them, and we unveil the fundamental physical principles that govern these behaviors, which underscore the biological predisposition of living material to migrate, independent of length scale.
Adhesion to nanofibers drives cell membrane remodeling through one-dimensional wetting.
Laboratoire Biologie cellulaire systémique de la polarité et de la division - Arthur Charles-Orszag, Feng-Ching Tsai, Daria Bonazzi, Valeria Manriquez, Martin Sachse, Adeline Mallet, Audrey Salles, Keira Melican, Ralitza Staneva, Aurélie Bertin, Corinne Millien, Sylvie Goussard, Pierre Lafaye, Spencer Shorte, Matthieu Piel, Jacomi
Nature Communications - 185.41666667 - Adhesion to nanofibers drives cell membrane remodeling through one-dimensional wetting. - 2018
The shape of cellular membranes is highly regulated by a set of conserved mechanisms that can be manipulated by bacterial pathogens to infect cells. Remodeling of the plasma membrane of endothelial cells by the bacterium Neisseria meningitidis is thought to be essential during the blood phase of meningococcal infection, but the underlying mechanisms are unclear. Here we show that plasma membrane remodeling occurs independently of F-actin, along meningococcal type IV pili fibers, by a physical mechanism that we term ‘one-dimensional’ membrane wetting. We provide a theoretical model that describes the physical basis of one-dimensional wetting and show that this mechanism occurs in model membranes interacting with nanofibers, and in human cells interacting with extracellular matrix meshworks. We propose one-dimensional wetting as a new general principle driving the interaction of cells with their environment at the nanoscale that is diverted by meningococci during infection.
Size control in mammalian cells involves modulation of both growth rate and cell cycle duration.
Laboratoire Biologie cellulaire systémique de la polarité et de la division - Article | OPEN | Published: 16 August 2018 Size control in mammalian cells involves modulation of both growth rate and cell cycle duration Clotilde Cadart, Sylvain Monnier, Jacopo Grilli, Pablo J. Sáez, Nishit Srivastava, Rafaele Attia, Emmanuel Terriac
Nature Communications - 9 3275 - DOI : 10.1038/s41467-018-05393-0 - 2018
Despite decades of research, how mammalian cell size is controlled remains unclear because of the difficulty of directly measuring growth at the single-cell level. Here we report direct measurements of single-cell volumes over entire cell cycles on various mammalian cell lines and primary human cells. We find that, in a majority of cell types, the volume added across the cell cycle shows little or no correlation to cell birth size, a homeostatic behavior called “adder”. This behavior involves modulation of G1 or S-G2 duration and modulation of growth rate. The precise combination of these mechanisms depends on the cell type and the growth condition. We have developed a mathematical framework to compare size homeostasis in datasets ranging from bacteria to mammalian cells. This reveals that a near-adder behavior is the most common type of size control and highlights the importance of growth rate modulation to size control in mammalian cells.


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