title: Single-site sonoporation disrupts actin cytoskeleton organization.
abstract: Sonoporation is based upon an ultrasound-microbubble cavitation routine that physically punctures the plasma membrane on a transient basis. During such a process, the actin cytoskeleton may be disrupted in tandem because this network of subcellular filaments is physically interconnected with the plasma membrane. Here, by performing confocal fluorescence imaging of single-site sonoporation episodes induced by ultrasound-triggered collapse of a single targeted microbubble, we directly observed immediate rupturing of filamentary actin (F-actin) at the sonoporation site (cell type: ZR-75-30; ultrasound frequency: 1 MHz; peak negative pressure: 0.45 MPa; pulse duration: 30 cycles; bubble diameter: 2-4 µm). Also, through conducting a structure tensor analysis, we observed further disassembly of the F-actin network over the next 60 min after the onset of sonoporation. The extent of F-actin disruption was found to be more substantial in cells with higher uptake of sonoporation tracer. Commensurate with this process, cytoplasmic accumulation of globular actin (G-actin) was evident in sonoporated cells, and in turn the G-actin : F-actin ratio was increased in a trend similar to drug-induced (cytochalasin D) actin depolymerization. These results demonstrate that sonoporation is not solely a membrane-level phenomenon: organization of the actin cytoskeleton is concomitantly perturbed.
authors.affiliation: Medical Engineering Program, The University of Hong Kong, , Pokfulam, Hong Kong.
authors.forename: Xian
authors.initials: X
authors.lastname: Chen
authors.forename: Ruen Shan
authors.initials: RS
authors.lastname: Leow
authors.forename: Yaxin
authors.initials: Y
authors.lastname: Hu
authors.forename: Jennifer M F
authors.initials: JM
authors.lastname: Wan
authors.forename: Alfred C H
authors.initials: AC
authors.lastname: Yu
mesh_terms: D008841:Actin Cytoskeleton / Q000378:metabolism*; D000199:Actins / Q000378:metabolism*; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000378:metabolism*; D006801:Humans; D018613:Microscopy, Confocal; D013016:Sound
chemical_list: D000199:Actins
keywords: F-actin disassembly; G-actin accumulation; actin cytoskeleton; characteristic time; single-site sonoporation; structure tensor analysis