Ballistic intracellular nanorheology reveals ROCK-hard cytoplasmic stiffening response to fluid flow

• DOI: 10.1242/jcs.02899
• Publication Date: 2006-04-24T16:29:27Z
• Authors: Jerry S. H. Lee; Porntula Panorchan; Christopher M. Hale; Shyam B. Khatau; Thomas P. Kole; Yiider Tseng; Denis Wirtz
• Keywords: Mechanotransduction; Stiffening

Cells in vivo are constantly subjected to mechanical shear stresses that play important regulatory roles various physiological and pathological processes. Cytoskeletal reorganizations occur response flow have been studied extensively, but whether the cytoplasm of an adherent cell adapts its properties respond is largely unknown. Here we develop a new method where fluorescent nanoparticles ballistically injected into cells probe, with high resolution, possible local viscoelastic changes individual fluid flow. This assay, ballistic intracellular nanorheology (BIN), reveals induces dramatic sustained 25-fold increase cytoplasmic viscosity serum-starved Swiss 3T3 fibroblasts. By contrast, stimulated actin contractile agonist LPA show highly transient stiffening much lower amplitude, despite formation similar cytoskeletal structures. Shear-induced attenuated by inhibiting actomyosin interactions entirely eliminated specific Rho-kinase (ROCK) inhibition. Together, these results biochemical biophysical stimuli may elicit qualitatively cytoskeleton structures (i.e. stress fibers focal adhesions), quantitatively different micromechanical responses. Our suggest when stresses, first order action prevent detachment from substratum greatly through enhanced assembly mediated contractility.