The Experts below are selected from a list of 4134 Experts worldwide ranked by ideXlab platform
Cécile Sykes - One of the best experts on this subject based on the ideXlab platform.
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Fluctuations of a Membrane Nanotube covered with an actin sleeve
Physical Review E, 2020Co-Authors: A. Allard, F. Valentino, T. Betz, Cécile Sykes, Clément CampilloAbstract:Many biological functions rely on the reshaping of cell Membranes, in particular into Nanotubes, which are covered in vivo by dynamic actin networks. Nanotubes are subject to thermal fluctuations, but the effect of these on cell functions is unknown. Here, we form Nanotubes from liposomes using an optically trapped bead adhering to the liposome Membrane. From the power spectral density of this bead, we study the Nanotube fluctuations in the range of Membrane tensions measured in vivo. We show that an actin sleeve covering the Nanotube damps its high-frequency fluctuations because of the network viscoelasticity. Our work paves the way for further studies of the effect of Nanotube fluctuations on cellular functions.
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Fluctuations of a Membrane Nanotube revealed by high-resolution force measurements
Soft Matter, 2016Co-Authors: F. Valentino, P. Sens, J. Lemière, A. Allard, T. Betz, Clément Campillo, Cécile SykesAbstract:Pulling Membrane Nanotubes from liposomes presents a powerful method to gain access to Membrane mechanics. Here we extend classical optical tweezers studies to infer Membrane Nanotube dynamics with high spatial and temporal resolution. We first validate our force measurement setup by accurately measuring the bending modulus of EPC Membrane in tube pulling experiments. Then we record the position signal of a trapped bead when it is connected, or not, to a tube. We derive the fluctuation spectrum of these signals and find that the presence of a Membrane Nanotube induces higher fluctuations, especially at low frequencies (10-1000 Hz). We analyse these spectra by taking into account the peristaltic modes of Nanotube fluctuations. This analysis provides a new experimental framework for a quantitative study of the fluctuations of nanotubular Membrane structures that are present in living cells, and now classically used for in vitro biomimetic approaches.
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Fluctuations of a Membrane Nanotube revealed by high-resolution force measurements
Soft Matter, 2016Co-Authors: F. Valentino, P. Sens, J. Lemière, A. Allard, T. Betz, Clément Campillo, Cécile SykesAbstract:Pulling Membrane Nanotubes from liposomes presents a powerful method to gain access to Membrane mechanics. Here we extend classical optical tweezers studies to infer Membrane Nanotube dynamics with high spatial and temporal resolution. We first validate our force measurement setup by accurately measuring the bending modulus of EPC Membrane in tube pulling experiments. Then we record the position signal of a trapped bead when it is connected, or not, to a tube. We derive the fluctuation spectrum of these signals and find that the presence of a Membrane Nanotube induces higher fluctuations, especially at low frequencies (10-1000 Hz). We analyse these spectra by taking into account the peristaltic modes of Nanotube fluctuations. This analysis provides a new experimental framework for a quantitative study of the fluctuations of nanotubular Membrane structures that are present in living cells, and now classically used for in vitro biomimetic approaches.
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Unexpected Membrane Dynamics Unveiled by Membrane Nanotube Extrusion
Biophysical Journal, 2013Co-Authors: Clément Campillo, Pierre Sens, Darius Koester, Lea-laetitia Pontani, Daniel Lévy, Patricia Bassereau, Pierre Nassoy, Cécile SykesAbstract:In cell mechanics, distinguishing the respective roles of the plasma Membrane and of the cytoskeleton is a challenge. The difference in the behavior of cellular and pure lipid Membranes is usually attributed to the presence of the cytoskeleton as explored by Membrane Nanotube extrusion. Here we revisit this prevalent picture by unveiling unexpected force responses of plasma Membrane spheres devoid of cytoskeleton and synthetic liposomes. We show that a tiny variation in the content of synthetic Membranes does not affect their static mechanical properties, but is enough to reproduce the dynamic behavior of their cellular counterparts. This effect is attributed to an amplified intraMembrane friction. Reconstituted actin cortices inside liposomes induce an additional, but not dominant, contribution to the effective Membrane friction. Our work underlines the necessity of a careful consideration of the role of Membrane proteins on cell Membrane rheology in addition to the role of the cytoskeleton.
Winfried Weissenhorn - One of the best experts on this subject based on the ideXlab platform.
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Human ESCRT-III polymers assemble on positively curved Membranes and induce helical Membrane tube formation
Nature Communications, 2020Co-Authors: Aurélie Bertin, Nicola De Franceschi, Eugenio De La Mora, Sourav Maiti, Maryam Alqabandi, Nolwenn Miguet, Aurelie Di Cicco, Wouter Roos, Stéphanie Mangenot, Winfried WeissenhornAbstract:Endosomal sorting complexes for transport-III (ESCRT-III) assemble in vivo onto Membranes with negative Gaussian curvature. How Membrane shape influences ESCRT-III polymerization and how ESCRT-III shapes Membranes is yet unclear. Human core ESCRT-III proteins, CHMP4B, CHMP2A, CHMP2B and CHMP3 are used to address this issue in vitro by combining Membrane Nanotube pulling experiments, cryo-electron tomography and AFM. We show that CHMP4B filaments preferentially bind to flat Membranes or to tubes with positive mean curvature. Both CHMP2B and CHMP2A/CHMP3 assemble on positively curved Membrane tubes. Combinations of CHMP4B/CHMP2B and CHMP4B/CHMP2A/CHMP3 are recruited to the neck of pulled Membrane tubes and reshape vesicles into helical "corkscrew-like" Membrane tubes. Sub-tomogram averaging reveals that the ESCRT-III filaments assemble parallel and locally perpendicular to the tube axis, highlighting the mechanical stresses imposed by ESCRT-III. Our results underline the versatile Membrane remodeling activity of ESCRT-III that may be a general feature required for cellular Membrane remodeling processes.
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Human ESCRT-III polymers assemble on positively curved Membranes and induce helical Membrane tube formation
Nature Communications, 2020Co-Authors: Aurélie Bertin, Nicola De Franceschi, Eugenio De La Mora, Maryam Alqabandi, Nolwenn Miguet, Aurelie Di Cicco, Stéphanie Mangenot, Sourav Maity, Wouter H. Roos, Winfried WeissenhornAbstract:Endosomal sorting complexes for transport-III (ESCRT-III) assemble in vivo onto Membranes with negative Gaussian curvature. How Membrane shape influences ESCRT-III polymerization and how ESCRT-III shapes Membranes is yet unclear. Human core ESCRT-III proteins, CHMP4B, CHMP2A, CHMP2B and CHMP3 are used to address this issue in vitro by combining Membrane Nanotube pulling experiments, cryo-electron tomography and AFM. We show that CHMP4B filaments preferentially bind to flat Membranes or to tubes with positive mean curvature. Both CHMP2B and CHMP2A/CHMP3 assemble on positively curved Membrane tubes. Combinations of CHMP4B/CHMP2B and CHMP4B/CHMP2A/CHMP3 are recruited to the neck of pulled Membrane tubes and reshape vesicles into helical “corkscrew-like” Membrane tubes. Sub-tomogram averaging reveals that the ESCRT-III filaments assemble parallel and locally perpendicular to the tube axis, highlighting the mechanical stresses imposed by ESCRT-III. Our results underline the versatile Membrane remodeling activity of ESCRT-III that may be a general feature required for cellular Membrane remodeling processes. ESCRT-III complexes assemble in vivo inside Membrane structures with a negative Gaussian curvature, but how Membrane shape influences ESCRT-III polymerization remains unclear. Here authors use structural and biophysical methods to show how human ESCRT-III polymers assemble on positively curved Membranes and induce helical Membrane tube formation.
Aurélie Bertin - One of the best experts on this subject based on the ideXlab platform.
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Human ESCRT-III polymers assemble on positively curved Membranes and induce helical Membrane tube formation
Nature Communications, 2020Co-Authors: Aurélie Bertin, Nicola De Franceschi, Eugenio De La Mora, Sourav Maiti, Maryam Alqabandi, Nolwenn Miguet, Aurelie Di Cicco, Wouter Roos, Stéphanie Mangenot, Winfried WeissenhornAbstract:Endosomal sorting complexes for transport-III (ESCRT-III) assemble in vivo onto Membranes with negative Gaussian curvature. How Membrane shape influences ESCRT-III polymerization and how ESCRT-III shapes Membranes is yet unclear. Human core ESCRT-III proteins, CHMP4B, CHMP2A, CHMP2B and CHMP3 are used to address this issue in vitro by combining Membrane Nanotube pulling experiments, cryo-electron tomography and AFM. We show that CHMP4B filaments preferentially bind to flat Membranes or to tubes with positive mean curvature. Both CHMP2B and CHMP2A/CHMP3 assemble on positively curved Membrane tubes. Combinations of CHMP4B/CHMP2B and CHMP4B/CHMP2A/CHMP3 are recruited to the neck of pulled Membrane tubes and reshape vesicles into helical "corkscrew-like" Membrane tubes. Sub-tomogram averaging reveals that the ESCRT-III filaments assemble parallel and locally perpendicular to the tube axis, highlighting the mechanical stresses imposed by ESCRT-III. Our results underline the versatile Membrane remodeling activity of ESCRT-III that may be a general feature required for cellular Membrane remodeling processes.
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Human ESCRT-III polymers assemble on positively curved Membranes and induce helical Membrane tube formation
Nature Communications, 2020Co-Authors: Aurélie Bertin, Nicola De Franceschi, Eugenio De La Mora, Maryam Alqabandi, Nolwenn Miguet, Aurelie Di Cicco, Stéphanie Mangenot, Sourav Maity, Wouter H. Roos, Winfried WeissenhornAbstract:Endosomal sorting complexes for transport-III (ESCRT-III) assemble in vivo onto Membranes with negative Gaussian curvature. How Membrane shape influences ESCRT-III polymerization and how ESCRT-III shapes Membranes is yet unclear. Human core ESCRT-III proteins, CHMP4B, CHMP2A, CHMP2B and CHMP3 are used to address this issue in vitro by combining Membrane Nanotube pulling experiments, cryo-electron tomography and AFM. We show that CHMP4B filaments preferentially bind to flat Membranes or to tubes with positive mean curvature. Both CHMP2B and CHMP2A/CHMP3 assemble on positively curved Membrane tubes. Combinations of CHMP4B/CHMP2B and CHMP4B/CHMP2A/CHMP3 are recruited to the neck of pulled Membrane tubes and reshape vesicles into helical “corkscrew-like” Membrane tubes. Sub-tomogram averaging reveals that the ESCRT-III filaments assemble parallel and locally perpendicular to the tube axis, highlighting the mechanical stresses imposed by ESCRT-III. Our results underline the versatile Membrane remodeling activity of ESCRT-III that may be a general feature required for cellular Membrane remodeling processes. ESCRT-III complexes assemble in vivo inside Membrane structures with a negative Gaussian curvature, but how Membrane shape influences ESCRT-III polymerization remains unclear. Here authors use structural and biophysical methods to show how human ESCRT-III polymers assemble on positively curved Membranes and induce helical Membrane tube formation.
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human escrt iii polymers assemble on positively curved Membranes and induce helical Membrane tube formation
bioRxiv, 2019Co-Authors: Aurélie Bertin, Nicola De Franceschi, Eugenio De La Mora, Nolwenn Miguet, Sourav Maity, Aurelie Di CiccoAbstract:Endosomal sorting complexes required for transport-III (ESCRT-III) are thought to assemble in vivo inside Membrane structures with a negative Gaussian curvature. How Membrane shape influences ESCRT-III polymerization and conversely how ESCRT-III polymers shape Membranes is still unclear. Here, we used human core ESCRT-III proteins, CHMP4B, CHMP2A, CHMP2B and CHMP3 to address this issue in vitro by combining Membrane Nanotube pulling experiments, cryo-electron microscopy, cryo-electron tomography and high-speed AFM. We show that CHMP4B filaments bind preferentially to flat Membranes or to Membrane tubes with a positive mean curvature. Both CHMP2B and CHMP2A/CHMP3 assemble on positively curved Membrane tubes, the latter winding around the tubes. Although combinations of CHMP4B/CHMP2B and CHMP4B/CHMP2A/CHMP3 are recruited to the neck of pulled Membrane tubes, they also reshape large unilamellar vesicles into helical Membrane tubes with a pipe surface shape. Sub-tomogram averaging reveals that the filaments assemble parallel to the tube axis with some local perpendicular connections, highlighting the particular mechanical stresses imposed by ESCRT-III to stabilize the corkscrew-like Membrane architecture. Our results thus underline the versatile Membrane remodeling activity of ESCRT-III that may be a general feature of ESCRT-III required for all or selected cellular Membrane remodeling processes.
F. Valentino - One of the best experts on this subject based on the ideXlab platform.
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Fluctuations of a Membrane Nanotube covered with an actin sleeve
Physical Review E, 2020Co-Authors: A. Allard, F. Valentino, T. Betz, Cécile Sykes, Clément CampilloAbstract:Many biological functions rely on the reshaping of cell Membranes, in particular into Nanotubes, which are covered in vivo by dynamic actin networks. Nanotubes are subject to thermal fluctuations, but the effect of these on cell functions is unknown. Here, we form Nanotubes from liposomes using an optically trapped bead adhering to the liposome Membrane. From the power spectral density of this bead, we study the Nanotube fluctuations in the range of Membrane tensions measured in vivo. We show that an actin sleeve covering the Nanotube damps its high-frequency fluctuations because of the network viscoelasticity. Our work paves the way for further studies of the effect of Nanotube fluctuations on cellular functions.
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Fluctuations of a Membrane Nanotube revealed by high-resolution force measurements
Soft Matter, 2016Co-Authors: F. Valentino, P. Sens, J. Lemière, A. Allard, T. Betz, Clément Campillo, Cécile SykesAbstract:Pulling Membrane Nanotubes from liposomes presents a powerful method to gain access to Membrane mechanics. Here we extend classical optical tweezers studies to infer Membrane Nanotube dynamics with high spatial and temporal resolution. We first validate our force measurement setup by accurately measuring the bending modulus of EPC Membrane in tube pulling experiments. Then we record the position signal of a trapped bead when it is connected, or not, to a tube. We derive the fluctuation spectrum of these signals and find that the presence of a Membrane Nanotube induces higher fluctuations, especially at low frequencies (10-1000 Hz). We analyse these spectra by taking into account the peristaltic modes of Nanotube fluctuations. This analysis provides a new experimental framework for a quantitative study of the fluctuations of nanotubular Membrane structures that are present in living cells, and now classically used for in vitro biomimetic approaches.
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Fluctuations of a Membrane Nanotube revealed by high-resolution force measurements
Soft Matter, 2016Co-Authors: F. Valentino, P. Sens, J. Lemière, A. Allard, T. Betz, Clément Campillo, Cécile SykesAbstract:Pulling Membrane Nanotubes from liposomes presents a powerful method to gain access to Membrane mechanics. Here we extend classical optical tweezers studies to infer Membrane Nanotube dynamics with high spatial and temporal resolution. We first validate our force measurement setup by accurately measuring the bending modulus of EPC Membrane in tube pulling experiments. Then we record the position signal of a trapped bead when it is connected, or not, to a tube. We derive the fluctuation spectrum of these signals and find that the presence of a Membrane Nanotube induces higher fluctuations, especially at low frequencies (10-1000 Hz). We analyse these spectra by taking into account the peristaltic modes of Nanotube fluctuations. This analysis provides a new experimental framework for a quantitative study of the fluctuations of nanotubular Membrane structures that are present in living cells, and now classically used for in vitro biomimetic approaches.
Nicola De Franceschi - One of the best experts on this subject based on the ideXlab platform.
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Human ESCRT-III polymers assemble on positively curved Membranes and induce helical Membrane tube formation
Nature Communications, 2020Co-Authors: Aurélie Bertin, Nicola De Franceschi, Eugenio De La Mora, Sourav Maiti, Maryam Alqabandi, Nolwenn Miguet, Aurelie Di Cicco, Wouter Roos, Stéphanie Mangenot, Winfried WeissenhornAbstract:Endosomal sorting complexes for transport-III (ESCRT-III) assemble in vivo onto Membranes with negative Gaussian curvature. How Membrane shape influences ESCRT-III polymerization and how ESCRT-III shapes Membranes is yet unclear. Human core ESCRT-III proteins, CHMP4B, CHMP2A, CHMP2B and CHMP3 are used to address this issue in vitro by combining Membrane Nanotube pulling experiments, cryo-electron tomography and AFM. We show that CHMP4B filaments preferentially bind to flat Membranes or to tubes with positive mean curvature. Both CHMP2B and CHMP2A/CHMP3 assemble on positively curved Membrane tubes. Combinations of CHMP4B/CHMP2B and CHMP4B/CHMP2A/CHMP3 are recruited to the neck of pulled Membrane tubes and reshape vesicles into helical "corkscrew-like" Membrane tubes. Sub-tomogram averaging reveals that the ESCRT-III filaments assemble parallel and locally perpendicular to the tube axis, highlighting the mechanical stresses imposed by ESCRT-III. Our results underline the versatile Membrane remodeling activity of ESCRT-III that may be a general feature required for cellular Membrane remodeling processes.
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Human ESCRT-III polymers assemble on positively curved Membranes and induce helical Membrane tube formation
Nature Communications, 2020Co-Authors: Aurélie Bertin, Nicola De Franceschi, Eugenio De La Mora, Maryam Alqabandi, Nolwenn Miguet, Aurelie Di Cicco, Stéphanie Mangenot, Sourav Maity, Wouter H. Roos, Winfried WeissenhornAbstract:Endosomal sorting complexes for transport-III (ESCRT-III) assemble in vivo onto Membranes with negative Gaussian curvature. How Membrane shape influences ESCRT-III polymerization and how ESCRT-III shapes Membranes is yet unclear. Human core ESCRT-III proteins, CHMP4B, CHMP2A, CHMP2B and CHMP3 are used to address this issue in vitro by combining Membrane Nanotube pulling experiments, cryo-electron tomography and AFM. We show that CHMP4B filaments preferentially bind to flat Membranes or to tubes with positive mean curvature. Both CHMP2B and CHMP2A/CHMP3 assemble on positively curved Membrane tubes. Combinations of CHMP4B/CHMP2B and CHMP4B/CHMP2A/CHMP3 are recruited to the neck of pulled Membrane tubes and reshape vesicles into helical “corkscrew-like” Membrane tubes. Sub-tomogram averaging reveals that the ESCRT-III filaments assemble parallel and locally perpendicular to the tube axis, highlighting the mechanical stresses imposed by ESCRT-III. Our results underline the versatile Membrane remodeling activity of ESCRT-III that may be a general feature required for cellular Membrane remodeling processes. ESCRT-III complexes assemble in vivo inside Membrane structures with a negative Gaussian curvature, but how Membrane shape influences ESCRT-III polymerization remains unclear. Here authors use structural and biophysical methods to show how human ESCRT-III polymers assemble on positively curved Membranes and induce helical Membrane tube formation.
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human escrt iii polymers assemble on positively curved Membranes and induce helical Membrane tube formation
bioRxiv, 2019Co-Authors: Aurélie Bertin, Nicola De Franceschi, Eugenio De La Mora, Nolwenn Miguet, Sourav Maity, Aurelie Di CiccoAbstract:Endosomal sorting complexes required for transport-III (ESCRT-III) are thought to assemble in vivo inside Membrane structures with a negative Gaussian curvature. How Membrane shape influences ESCRT-III polymerization and conversely how ESCRT-III polymers shape Membranes is still unclear. Here, we used human core ESCRT-III proteins, CHMP4B, CHMP2A, CHMP2B and CHMP3 to address this issue in vitro by combining Membrane Nanotube pulling experiments, cryo-electron microscopy, cryo-electron tomography and high-speed AFM. We show that CHMP4B filaments bind preferentially to flat Membranes or to Membrane tubes with a positive mean curvature. Both CHMP2B and CHMP2A/CHMP3 assemble on positively curved Membrane tubes, the latter winding around the tubes. Although combinations of CHMP4B/CHMP2B and CHMP4B/CHMP2A/CHMP3 are recruited to the neck of pulled Membrane tubes, they also reshape large unilamellar vesicles into helical Membrane tubes with a pipe surface shape. Sub-tomogram averaging reveals that the filaments assemble parallel to the tube axis with some local perpendicular connections, highlighting the particular mechanical stresses imposed by ESCRT-III to stabilize the corkscrew-like Membrane architecture. Our results thus underline the versatile Membrane remodeling activity of ESCRT-III that may be a general feature of ESCRT-III required for all or selected cellular Membrane remodeling processes.