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Differential activation and inhibition of RhoA by fluid flow induced shear stress in chondrocytes
Author(s) -
Wan Qiaoqiao,
Kim Seung Joon,
Yokota Hiroki,
Na Sungsoo
Publication year - 2013
Publication title -
cell biology international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.932
H-Index - 77
eISSN - 1095-8355
pISSN - 1065-6995
DOI - 10.1002/cbin.10072
Subject(s) - rhoa , shear stress , cdc42 , mechanotransduction , chemistry , cytoskeleton , microbiology and biotechnology , shear (geology) , biophysics , stress fiber , small gtpase , rac1 , actin cytoskeleton , gtpase , materials science , signal transduction , biology , cell , biochemistry , composite material
Physical force environment is a major factor that influences cellular homeostasis and remodelling. It is not well understood, however, as a potential role of force intensities in the induction of cellular mechanotransduction. Using a fluorescence resonance energy transfer‐based approach, we asked whether activities of GTPase RhoA in chondrocytes are dependent on intensities of flow‐induced shear stress. We hypothesized that RhoA activities can be either elevated or reduced by selecting different levels of shear‐stress intensities. The result indicates that C28/I2 chondrocytes have increased RhoA activities in response to high shear stress (10 or 20 dyn/cm 2 ), whereas a decrease in activity was seen with an intermediate shear stress of 5 dyn/cm 2 . No changes were seen under low shear stress (2 dyn/cm 2 ). The observed two‐level switch of RhoA activities is closely linked to the shear‐stress‐induced alterations in actin cytoskeleton and traction forces. In the presence of constitutively active RhoA (RhoA‐V14), intermediate shear stress suppressed RhoA activities, while high shear stress failed to activate them. In chondrocytes, expression of various metalloproteinases is, in part, regulated by shear and normal stresses through a network of GTPases. Collectively, the data suggest that intensities of shear stress are critical in differential activation and inhibition of RhoA activities in chondrocytes.