Publication Date:
2014-04-15
Description:
Important processes of living cells, including intracellular transport, cell crawling, contraction, division, and mechanochemical signal transduction, are controlled by cytoskeletal (CSK) dynamics. CSK dynamics can
be measured by tracking the motion of CSK-bound particles. Particle motion has been reported to follow a
superdiffusive behavior that is believed to arise from ATP-driven intracellular stress fluctuations generated
by polymerization processes and motor proteins. The power spectrum of intracellular stress fluctuations has
been suggested to decay with 1/2 (Lau et al, Phys Rev Lett 91:198101). Here we report direct measurements of cellular force fluctuations that are transmitted to the extracellular matrix, and compared
them with the spontaneous motion of CSK-bound beads. Fibronectin coated fluorescent beads (Ø 1 m)
were bound to the CSK of confluent human vascular endothelial cells. Forces transmitted to the extracellular
matrix (ECM) were quantified by plating these cells onto a collagen coated elastic polyacrylamide hydrogel,
and measuring the gel deformation from the displacement of embedded fluorescent beads (Ø 0.5 m). Bead
motion of both CSK-bound and ECM-bound beads were measured with nanometer-resolution and expressed
as mean square displacement (MSD). The MSD of both CSK-bound and ECM-bound beads displayed a
superdiffusive behavior that was well described by a power law: MSD = a*t^b. Surprisingly, we found an
identical power law exponent for both CSK-bound and ECM-bound beads of b = 1.6. This finding suggests
that the spontaneous motion of CSK-bound beads is driven by stress fluctuations with a 1/
b+1 power spectrum. This result is consistent with the notion that CSK dynamics and CSK stress fluctuations are closely coupled.
Repository Name:
EPIC Alfred Wegener Institut
Type:
Book
,
peerRev
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