Articles by Stéphanie Balor in JoVE
Protrusion Force Microscopy: A Method to Quantify Forces Developed by Cell Protrusions Anaïs Bouissou*1, Amsha Proag*1, Marion Portes1, Vanessa Soldan2, Stéphanie Balor2, Christophe Thibault3,4, Christophe Vieu3,4, Isabelle Maridonneau-Parini1, Renaud Poincloux1 1Institut de Pharmacologie et Biologie Structurale, IPBS, Université de Toulouse, CNRS, UPS, 2METi, 3CNRS, LAAS, 4Univ de Toulouse, INSA Here, we detail the experimental techniques used to evaluate the protrusion forces that podosomes apply on a compliant film, from the preparation of the film to the automated analysis of topographical images.
Other articles by Stéphanie Balor on PubMed
Proteome Characterization of Melanoma Exosomes Reveals a Specific Signature for Metastatic Cell Lines Pigment Cell & Melanoma Research. Jul, 2015 | Pubmed ID: 25950383 Exosomes are important mediators in cell-to-cell communication and, recently, their role in melanoma progression has been brought to light. Here, we characterized exosomes secreted by seven melanoma cell lines with varying degrees of aggressivity. Extensive proteomic analysis of their exosomes confirmed the presence of characteristic exosomal markers as well as melanoma-specific antigens and oncogenic proteins. Importantly, the protein composition differed among exosomes from different lines. Exosomes from aggressive cells contained specific proteins involved in cell motility, angiogenesis, and immune response, while these proteins were less abundant or absent in exosomes from less aggressive cells. Interestingly, when exposed to exosomes from metastatic lines, less aggressive cells increased their migratory capacities, likely due to transfer of pro-migratory exosomal proteins to recipient cells. Hence, this study shows that the specific protein composition of melanoma exosomes depends on the cells' aggressivity and suggests that exosomes influence the behavior of other tumor cells and their microenvironment.
Podosome Force Generation Machinery: A Local Balance Between Protrusion at the Core and Traction at the Ring ACS Nano. Apr, 2017 | Pubmed ID: 28355484 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.