Fluid shear stress remodels expression and function of junctional proteins in cultured bone cells

Mia M. Thi, Takashi Kojima, Stephen C. Cowin, Sheldon Weinbaum, David C. Spray

Research output: Contribution to journalArticle

74 Scopus citations

Abstract

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.

Original languageEnglish (US)
Pages (from-to)C389-C403
JournalAmerican Journal of Physiology - Cell Physiology
Volume284
Issue number2 53-2
DOIs
StatePublished - Feb 1 2003

Keywords

  • Bone remodeling
  • Connexin
  • Gap junctions
  • Mechanotransduction
  • Zona occludens-1

ASJC Scopus subject areas

  • Physiology
  • Cell Biology

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