Cytoskeletal mechanics in confluent epithelial cells probed through
integrins and e-cadherins.
Potard, U. Silke Birlenbach, James P. Butler, and Ning Wang.
Physiology Program, Department of Environmental Health, Harvard
School of Public Health, Boston, MA 02115
APStracts 3:0409C, 1996.
Mechanical forces associated with the cytoskeleton (CSK) and
transmitted to adjacent cells or to the extracellular matrix (ECM)
influence cellular functions. We investigated the force transfer
across cell-ECM and cell-cell connections using magnetic twisting
cytometry. We probed the CSK through integrins and E-cadherins in
confluent epithelial cell lines (MCF-7). At high applied stress
(greater than 10 dynes/cm2), stiffness (stress/strain) of the CSK
coupled through integrins was greater than stiffness coupled through
E-cadherins. The stiffness reduction following microfilament or
microtubule disruption with cytochalasin D or colchicine was greater
for integrins. At low applied stress, disruption of microfilaments
had very little effect on stiffness probed through either receptor
type, indicating a correspondingly small contribution of
microfilaments to the CSK mechanics in these confluent cells. This
differs from results in non-confluent MCF-7 cells and from
predictions based on prestressed models wherein tensile stresses
presumably associated with the microfilaments are the origin of
prestress and, in consequence, cell stiffness. In addition, there was
substantial cell spreading on collagen-I-coated dishes, in contrast
to little spreading on dishes coated with E-cadherin antibody. This
result, together with observations of a relatively high cell
stiffness probed through integrins compared with the small stiffness
probed through E-cadherins, suggests that mechanical force
transmission might also be important in regulating cell spreading. We
conclude that the degree of confluency may be associated with
different mechanics and functions of the CSK network.
Received 9 August 1996; accepted in final form 6 December 1996.
APS Manuscript Number C449-6.
Article publication pending Am. J. Physiol. (Cell Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 31 December 1996