title: Activation of a bacterial mechanosensitive channel in mammalian cells by cytoskeletal stress.
abstract: Cells can sense a myriad of mechanical stimuli. Mechanosensitive channel of large conductance (MscL) found in bacteria is a well-characterized mechanosensitive channel that rapidly responds to an increase in turgor pressure. Functional expression of MscL in mammalian cells has recently been demonstrated, revealing that molecular delivery or transport can be achieved by charge-induced activation of MscL. Despite a well-accepted mechanism for MscL activation by membrane tension in bacteria, it is not clear whether and how MscL can be opened by other modes of force transduction in mammalian cells. In this work, we used a variety of techniques to characterize the gating of MscL expressed in mammalian cells, using both wild type and a G22S mutant which activates at a lower threshold. In particular, employing a new technique, acoustic tweezing cytometry (ATC), we show that ultrasound actuation of integrin-bound microbubbles can lead to MscL opening and that ATC induced MscL activation was dependent on the functional linkage of the microbubbles with an intact actin cytoskeleton. Our results indicate that localized mechanical stress can mediate opening of MscL that requires force transduction through the actin cytoskeleton, revealing a new mode of MscL activation that may prove to be a useful tool for mechanobiology and drug delivery research.
authors.affiliation: Department of Mechanical Engineering, University of Michigan, Ann Arbor, Michigan, United States of America.
authors.forename: Johanna
authors.initials: J
authors.lastname: Heureaux
authors.affiliation: Department of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan, United States of America.
authors.forename: Di
authors.initials: D
authors.lastname: Chen
authors.affiliation: Department of Mechanical Engineering, University of Michigan, Ann Arbor, Michigan, United States of America.
authors.forename: Victoria L
authors.initials: VL
authors.lastname: Murray
authors.affiliation: Department of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan, United States of America.
authors.forename: Cheri X
authors.initials: CX
authors.lastname: Deng
authors.affiliation: Department of Mechanical Engineering, University of Michigan, Ann Arbor, Michigan, United States of America ; Department of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan, United States of America ; Cellular and Molecular Biology Program, University of Michigan, Ann Arbor, Michigan, United States of America ; Biophysics Program, University of Michigan, Ann Arbor, Michigan, United States of America.
authors.forename: Allen P
authors.initials: AP
authors.lastname: Liu
keywords: Mechanosensitive channels; acoustic tweezing cytometry; mechanobiology; membrane tension