title: Podosome Force Generation Machinery: A Local Balance between Protrusion at the Core and Traction at the Ring.
abstract: Determining how cells generate and transduce mechanical forces at the nanoscale is a major technical challenge for the understanding of numerous physiological and pathological processes. Podosomes are submicrometer cell structures with a columnar F-actin core surrounded by a ring of adhesion proteins, which possess the singular ability to protrude into and probe the extracellular matrix. Using protrusion force microscopy, we have previously shown that single podosomes produce local nanoscale protrusions on the extracellular environment. However, how cellular forces are distributed to allow this protruding mechanism is still unknown. To investigate the molecular machinery of protrusion force generation, we performed mechanical simulations and developed quantitative image analyses of nanoscale architectural and mechanical measurements. First, in silico modeling showed that the deformations of the substrate made by podosomes require protrusion forces to be balanced by local traction forces at the immediate core periphery where the adhesion ring is located. Second, we showed that three-ring proteins are required for actin polymerization and protrusion force generation. Third, using DONALD, a 3D nanoscopy technique that provides 20 nm isotropic localization precision, we related force generation to the molecular extension of talin within the podosome ring, which requires vinculin and paxillin, indicating that the ring sustains mechanical tension. Our work demonstrates that the ring is a site of tension, balancing protrusion at the core. This local coupling of opposing forces forms the basis of protrusion and reveals the podosome as a nanoscale autonomous force generator.
authors.affiliation: Institut de Pharmacologie et de Biologie Structurale, Université de Toulouse , CNRS, UPS, Toulouse 31400, France.
authors.forename: Anaïs
authors.initials: A
authors.lastname: Bouissou
authors.affiliation: Institut de Pharmacologie et de Biologie Structurale, Université de Toulouse , CNRS, UPS, Toulouse 31400, France.
authors.forename: Amsha
authors.initials: A
authors.lastname: Proag
authors.affiliation: Institut des Sciences Moléculaires d'Orsay, Université Paris-Sud , CNRS UMR8214, Orsay 91405, France.|Université Paris-Sud , Centre de Photonique BioMédicale, Fédération LUMAT, CNRS, FR 2764, Orsay 91405, France.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Bourg
authors.affiliation: Institut de Pharmacologie et de Biologie Structurale, Université de Toulouse , CNRS, UPS, Toulouse 31400, France.
authors.forename: Karine
authors.initials: K
authors.lastname: Pingris
authors.affiliation: Institut des Sciences Moléculaires d'Orsay, Université Paris-Sud , CNRS UMR8214, Orsay 91405, France.|Université Paris-Sud , Centre de Photonique BioMédicale, Fédération LUMAT, CNRS, FR 2764, Orsay 91405, France.
authors.forename: Clément
authors.initials: C
authors.lastname: Cabriel
authors.affiliation: METi , Toulouse 31062, France.
authors.forename: Stéphanie
authors.initials: S
authors.lastname: Balor
authors.affiliation: LBCMCP, Centre de Biologie Intégrative, Université de Toulouse , CNRS, UPS, Toulouse 31062, France.
authors.forename: Thomas
authors.initials: T
authors.lastname: Mangeat
authors.affiliation: CNRS, LAAS , Toulouse 31031, France.|Université de Toulouse , INSA, Toulouse 31077, France.
authors.forename: Christophe
authors.initials: C
authors.lastname: Thibault
authors.affiliation: CNRS, LAAS , Toulouse 31031, France.|Université de Toulouse , INSA, Toulouse 31077, France.
authors.forename: Christophe
authors.initials: C
authors.lastname: Vieu
authors.affiliation: Université Paris-Sud , Centre de Photonique BioMédicale, Fédération LUMAT, CNRS, FR 2764, Orsay 91405, France.
authors.forename: Guillaume
authors.initials: G
authors.lastname: Dupuis
authors.affiliation: Institut Langevin, ESPCI, CNRS, PSL Research University , Paris 75005, France.
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Fort
authors.affiliation: Institut des Sciences Moléculaires d'Orsay, Université Paris-Sud , CNRS UMR8214, Orsay 91405, France.|Université Paris-Sud , Centre de Photonique BioMédicale, Fédération LUMAT, CNRS, FR 2764, Orsay 91405, France.
authors.forename: Sandrine
authors.initials: S
authors.lastname: Lévêque-Fort
authors.affiliation: Institut de Pharmacologie et de Biologie Structurale, Université de Toulouse , CNRS, UPS, Toulouse 31400, France.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Maridonneau-Parini
authors.affiliation: Institut de Pharmacologie et de Biologie Structurale, Université de Toulouse , CNRS, UPS, Toulouse 31400, France.
authors.forename: Renaud
authors.identifier: 0000-0003-2884-1744
authors.initials: R
authors.lastname: Poincloux
mesh_terms: D000199:Actins / Q000737:chemistry / Q000378:metabolism; D001696:Biomechanical Phenomena; D002448:Cell Adhesion; D002478:Cells, Cultured; D003198:Computer Simulation; D006801:Humans; D008264:Macrophages / Q000166:cytology / Q000378:metabolism; D040542:Mechanotransduction, Cellular; D009000:Monocytes / Q000166:cytology / Q000378:metabolism; D049329:Nanostructures / Q000737:chemistry; D010316:Particle Size; D051419:Paxillin / Q000737:chemistry / Q000378:metabolism; D000069261:Podosomes / Q000737:chemistry* / Q000648:ultrastructure; D013499:Surface Properties; D016608:Talin / Q000737:chemistry / Q000378:metabolism; D016596:Vinculin / Q000737:chemistry / Q000378:metabolism
chemical_list: D000199:Actins; D051419:Paxillin; D016608:Talin; D016596:Vinculin
keywords: 3D nanoscopy; atomic force microscopy; cell mechanics; podosomes; protrusion force