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PA Janmey, JA Lamb, RM Ezzell, S Hvidt and SE Lind
Division of Experimental Medicine, Brigham and Women's Hospital, Boston, MA
02115.
The muscle and cytoskeletal protein actin is released from cells as a
consequence of cell death and interacts with components of the hemostatic
and fibrinolytic systems, including platelets, plasmin, and fibrin. We
report here that incorporation of actin filaments into fibrin clots changes
their viscoelastic properties by increasing their shear modulus at low
deforming stresses and by nearly eliminating their tendency to become more
rigid with increasing deformation (ie, exhibit strain-hardening). The
viscoelastic effects depended on the length of the actin filaments as shown
by the effects of the plasma filament- severing protein, gelsolin. Binding
of actin to fibrin clots also varied with actin filament length. The plasma
actin-binding proteins gelsolin and vitamin D-binding protein reduced, but
did not eliminate, the incorporation of actin in the clot. Fluorescence
microscopy showed a direct association of rhodamine-labeled actin filaments
with the fibrin network. Incubation of clots containing long actin
filaments in solutions containing physiologic concentrations of gelsolin (2
mumol/L) released 60% of the actin trapped in the clot. Reduction of the
actin content of a fibrin clot by incubation in a gelsolin-containing
solution resulted in an increased rate of clot lysis. The ability of plasma
gelsolin to shorten actin filaments may therefore be of physiologic and
potentially of therapeutic importance insofar as gelsolin-mediated
diffusion of actin from the clot may restore the clot's rheologic
properties and render it more sensitive to the lytic action of plasmin.
This article has been cited by other articles:
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| Copyright © 1992 by American Society of Hematology Online ISSN: 1528-0020 | |||||||||
