TY - JOUR
T1 - Fluid shear stress remodels expression and function of junctional proteins in cultured bone cells
AU - Thi, Mia M.
AU - Kojima, Takashi
AU - Cowin, Stephen C.
AU - Weinbaum, Sheldon
AU - Spray, David C.
PY - 2003/2/1
Y1 - 2003/2/1
N2 - We tested the hypothesis that fluid shear stress (τ) modifies the expression, function, and distribution of junctional proteins [connexin (Cx)43, Cx45, and zona occludens (ZO)-1] in cultured bone cells. Cell lines with osteoblastic (MC3T3-E1 cells) and osteocytic (MLO-Y4 cells) phenotypes were exposed to τ-values of 5 or 20 dyn/cm2 for 1-3 h. Immunostaining indicated that at 5 dyn/cm2, the distribution of Cx43, Cx45, and ZO-1 was moderately disrupted at cell membranes; at 20 dyn/cm2, disruption was more severe. Intercellular coupling was significantly decreased at both shear stress levels. Western blots showed the downregulation of membrane-bound Cx43 and ZO-1 and the upregulation of cytosolic Cx43 and Cx45 at different levels of shear stress. Similarly, Northern blots revealed that expression of Cx43, Cx45, and ZO-1 was selectively up- and down-regulated in response to different shear stress levels. These results indicate that in cultured bone cells, fluid shear stress disrupts junctional communication, rearranges junctional proteins, and determines de novo synthesis of specific connexins to an extent that depends on the magnitude of the shear stress. Such disconnection from the bone cell network may provide part of the signal whereby the disconnected cells or the remaining network initiate focal bone remodeling.
AB - We tested the hypothesis that fluid shear stress (τ) modifies the expression, function, and distribution of junctional proteins [connexin (Cx)43, Cx45, and zona occludens (ZO)-1] in cultured bone cells. Cell lines with osteoblastic (MC3T3-E1 cells) and osteocytic (MLO-Y4 cells) phenotypes were exposed to τ-values of 5 or 20 dyn/cm2 for 1-3 h. Immunostaining indicated that at 5 dyn/cm2, the distribution of Cx43, Cx45, and ZO-1 was moderately disrupted at cell membranes; at 20 dyn/cm2, disruption was more severe. Intercellular coupling was significantly decreased at both shear stress levels. Western blots showed the downregulation of membrane-bound Cx43 and ZO-1 and the upregulation of cytosolic Cx43 and Cx45 at different levels of shear stress. Similarly, Northern blots revealed that expression of Cx43, Cx45, and ZO-1 was selectively up- and down-regulated in response to different shear stress levels. These results indicate that in cultured bone cells, fluid shear stress disrupts junctional communication, rearranges junctional proteins, and determines de novo synthesis of specific connexins to an extent that depends on the magnitude of the shear stress. Such disconnection from the bone cell network may provide part of the signal whereby the disconnected cells or the remaining network initiate focal bone remodeling.
KW - Bone remodeling
KW - Connexin
KW - Gap junctions
KW - Mechanotransduction
KW - Zona occludens-1
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U2 - 10.1152/ajpcell.00052.2002
DO - 10.1152/ajpcell.00052.2002
M3 - Article
C2 - 12388096
AN - SCOPUS:0037302142
SN - 0363-6143
VL - 284
SP - C389-C403
JO - American Journal of Physiology - Cell Physiology
JF - American Journal of Physiology - Cell Physiology
IS - 2 53-2
ER -