Knockdown of ezrin causes intrahepatic cholestasis by the dysregulation of bile fluidity in the bile duct epithelium in mice

  • Ryo Hatano
    Department of Molecular Physiology, College of Pharmaceutical Sciences,Ritsumeikan University,Shiga,Japan
  • Kaori Akiyama
    Department of Molecular Physiology, College of Pharmaceutical Sciences,Ritsumeikan University,Shiga,Japan
  • Atsushi Tamura
    Laboratory of Biological Science, Graduate School of Frontier Biosciences and Graduate School of Medicine,Osaka University,Osaka,Japan
  • Shigekuni Hosogi
    Department of Molecular Cell Physiology and Bio‐Ionomics,Kyoto Prefectural University of Medicine,Kyoto,Japan
  • Yoshinori Marunaka
    Department of Molecular Cell Physiology and Bio‐Ionomics,Kyoto Prefectural University of Medicine,Kyoto,Japan
  • Michael J. Caplan
    Department of Cellular and Molecular Physiology,Yale School of Medicine,New Haven,CT
  • Yoshiyuki Ueno
    Department of Gastroenterology,Yamagata University School of Medicine,Yamagata,Japan
  • Sachiko Tsukita
    Laboratory of Biological Science, Graduate School of Frontier Biosciences and Graduate School of Medicine,Osaka University,Osaka,Japan
  • Shinji Asano
    Department of Molecular Physiology, College of Pharmaceutical Sciences,Ritsumeikan University,Shiga,Japan

抄録

<jats:p>Cholangiopathies share common features, including bile duct proliferation, periportal fibrosis, and intrahepatic cholestasis. Damage of biliary epithelium by autoimunne disorder, virus infection, toxic compounds, and developmental abnormalities causes severe progressive hepatic disorders responsible for high mortality. However, the etiologies of these cholestatic diseases remain unclear because useful models to study the pathogenic mechanisms are not available. In the present study, we have found that ezrin knockdown (<jats:italic toggle="yes">Vil2kd/kd </jats:italic>) mice develop severe intrahepatic cholestasis characterized by extensive bile duct proliferation, periductular fibrosis, and intrahepatic bile acid accumulation without developmental defects of bile duct morphology and infiltration of inflammatory cells. Ezrin is a membrane cytoskeletal cross‐linker protein, which is known to interact with transporters, scaffold proteins, and actin cytoskeleton at the plasma membrane. We found that the normal apical membrane localizations of several transport proteins including cystic fibrosis transmembrane conductance regulator (CFTR), anion exchanger 2 (AE‐2), aquaporin 1 (AQP1), and Na<jats:sup>+</jats:sup>/H<jats:sup>+</jats:sup> exchanger regulatory factor were disturbed in bile ducts of <jats:italic toggle="yes">Vil2kd/kd </jats:italic> mice. Stable expression of a dominant negative form of ezrin in immortalized mouse cholangiocytes also led to the reduction of the surface expression of CFTR, AE‐2, and AQP1. Reduced surface expression of these transport proteins was accompanied by reduced functional expression, as evidenced by the fact these cells exhibited decreased CFTR‐mediated Cl<jats:sup>−</jats:sup> efflux activity. Furthermore, bile flow and biliary HCO<jats:sub>3</jats:sub> <jats:sup>−</jats:sup> concentration were also significantly reduced in <jats:italic toggle="yes">Vil2kd/kd </jats:italic> mice. <jats:italic toggle="yes">Conclusion</jats:italic>: Dysfunction of ezrin mimics important aspects of the pathological mechanisms responsible for cholangiopathies. The <jats:italic toggle="yes">Vil2kd/kd </jats:italic> mouse may be a useful model to exploit in the development and testing of potential therapies for cholangiopathies. (H<jats:sc>epatology</jats:sc> 2015;61:1660‐1671)</jats:p>

収録刊行物

  • Hepatology

    Hepatology 61 (5), 1660-1671, 2015-03-23

    Ovid Technologies (Wolters Kluwer Health)

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