Reticulon 4B (Nogo-B) facilitates hepatocyte proliferation and liver regeneration in mice

Authors

  • Lili Gao,

    1. Section of Digestive Diseases, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT
    2. Department of Geriatric Gastroenterology, PLA General Hospital, Beijing, China
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    • Potential conflict of interest: Nothing to report.

  • Teruo Utsumi,

    1. Section of Digestive Diseases, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT
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    • Potential conflict of interest: Nothing to report.

  • Keitaro Tashiro,

    1. Section of Digestive Diseases, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT
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    • Potential conflict of interest: Nothing to report.

  • Bo Liu,

    1. Section of Digestive Diseases, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT
    2. Department of Hepatobiliary Surgery, The Third Affiliated Hospital, Sun Yat-Sen University, Guangzhou, China
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  • Dahai Zhang,

    1. Section of Digestive Diseases, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT
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  • E. Scott Swenson,

    1. Section of Digestive Diseases, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT
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  • Yasuko Iwakiri

    Corresponding author
    1. Section of Digestive Diseases, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT
    • 1080 LMP, 333 Cedar Street, Section of Digestive Diseases, Yale University School of Medicine, New Haven, CT 06520
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    • fax: 203-785-7273


  • These authors contributed equally to this work.

Abstract

Nogo-B, also known as reticulon 4B, promotes liver fibrosis and cirrhosis by facilitating the transforming growth factor β (TGF-β) signaling pathway in activated hepatic stellate cells. The aim of this study was to determine the role of Nogo-B in hepatocyte proliferation and liver regeneration. Partial hepatectomy (PHx, 70% resection) was performed in male wild-type (WT) and Nogo-A/B knockout mice (referred to as Nogo-B KO mice). Remnant livers were isolated 2 hours, 5 hours, and 1, 2, 3, 7, and 14 days after PHx. Hepatocyte proliferation was assessed by Ki67 labeling index. Quantitative real-time polymerase chain reaction was performed for genes known to be involved in liver regeneration. Hepatocytes isolated from WT and Nogo-B KO mice were used to examine the role of Nogo-B in interleukin-6 (IL-6), hepatocyte growth factor (HGF), epidermal growth factor (EGF), and TGF-β signaling. Nogo-B protein levels increased in the regenerating livers in a time-dependent manner after PHx. Specifically, Nogo-B expression in hepatocytes gradually spread from the periportal toward the central areas by 7 days after PHx, but receded notably by 14 days. Nogo-B facilitated IL-6/signal transducer and activator of transcription 3 signaling, increased HGF-induced but not EGF-induced hepatocyte proliferation, and tended to reduce TGF-β1–induced suppression of hepatocyte proliferation in cultured hepatocytes. Lack of Nogo-B significantly induced TGF-β1 and inhibitor of DNA binding expression 1 day after PHx and IL-6 and EGF expression 2 days after PHx. Lack of Nogo-B delayed hepatocyte proliferation but did not affect the liver-to-body ratio in the regenerative process. Conclusion: Nogo-B expression in hepatocytes facilitates hepatocyte proliferation and liver regeneration. (HEPATOLOGY 2013)

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