title: Integrin-specific mechanoresponses to compression and extension probed by cylindrical flat-ended AFM tips in lung cells.
abstract: Cells from lung and other tissues are subjected to forces of opposing directions that are largely transmitted through integrin-mediated adhesions. How cells respond to force bidirectionality remains ill defined. To address this question, we nanofabricated flat-ended cylindrical Atomic Force Microscopy (AFM) tips with ~1 µm(2) cross-section area. Tips were uncoated or coated with either integrin-specific (RGD) or non-specific (RGE/BSA) molecules, brought into contact with lung epithelial cells or fibroblasts for 30 s to form focal adhesion precursors, and used to probe cell resistance to deformation in compression and extension. We found that cell resistance to compression was globally higher than to extension regardless of the tip coating. In contrast, both tip-cell adhesion strength and resistance to compression and extension were the highest when probed at integrin-specific adhesions. These integrin-specific mechanoresponses required an intact actin cytoskeleton, and were dependent on tyrosine phosphatases and Ca(2+) signaling. Cell asymmetric mechanoresponse to compression and extension remained after 5 minutes of tip-cell adhesion, revealing that asymmetric resistance to force directionality is an intrinsic property of lung cells, as in most soft tissues. Our findings provide new insights on how lung cells probe the mechanochemical properties of the microenvironment, an important process for migration, repair and tissue homeostasis.
authors.affiliation: Unitat de Biofísica i Bioenginyeria, Facultat de Medicina, Universitat de Barcelona, Barcelona, Spain.
authors.forename: Irene
authors.initials: I
authors.lastname: Acerbi
authors.forename: Tomás
authors.initials: T
authors.lastname: Luque
authors.forename: Alícia
authors.initials: A
authors.lastname: Giménez
authors.forename: Marta
authors.initials: M
authors.lastname: Puig
authors.forename: Noemi
authors.initials: N
authors.lastname: Reguart
authors.forename: Ramon
authors.initials: R
authors.lastname: Farré
authors.forename: Daniel
authors.initials: D
authors.lastname: Navajas
authors.forename: Jordi
authors.initials: J
authors.lastname: Alcaraz
mesh_terms: D000199:Actins / Q000737:chemistry; D002118:Calcium / Q000737:chemistry; D020013:Calcium Signaling; D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000378:metabolism; D003599:Cytoskeleton / Q000378:metabolism; D006801:Humans; D016023:Integrins / Q000378:metabolism; D008168:Lung / Q000166:cytology* / Q000378:metabolism; D018625:Microscopy, Atomic Force / Q000295:instrumentation* / Q000379:methods; D049329:Nanostructures; D009842:Oligopeptides / Q000737:chemistry; D010744:Phosphoric Monoester Hydrolases / Q000737:chemistry; D014443:Tyrosine / Q000737:chemistry
chemical_list: D000199:Actins; D016023:Integrins; D009842:Oligopeptides; D014443:Tyrosine; C047981:arginyl-glycyl-aspartic acid; D010744:Phosphoric Monoester Hydrolases; D002118:Calcium