Department of Pathology, University of Pittsburgh, Pittsburgh, PA.
Pittsburgh Liver Research Center, University of Pittsburgh and University of Pittsburgh Medical Center, Pittsburgh, PA.
Hepatology. 2019 Feb;69(2):742-759. doi: 10.1002/hep.30270. Epub 2019 Jan 4.
Liver regeneration after injury is normally mediated by proliferation of hepatocytes, although recent studies have suggested biliary epithelial cells (BECs) can differentiate into hepatocytes during severe liver injury when hepatocyte proliferation is impaired. We investigated the effect of hepatocyte-specific β-catenin deletion in recovery from severe liver injury and BEC-to-hepatocyte differentiation. To induce liver injury, we administered choline-deficient, ethionine-supplemented (CDE) diet to three different mouse models, the first being mice with deletion of β-catenin in both BECs and hepatocytes (Albumin-Cre; Ctnnb1 mice). In our second model, we performed hepatocyte lineage tracing by injecting Ctnnb1 ; Rosa-stop -EYFP mice with the adeno-associated virus serotype 8 encoding Cre recombinase under the control of the thyroid binding globulin promoter, a virus that infects only hepatocytes. Finally, we performed BEC lineage tracing via Krt19-Cre ; Rosa-stop -tdTomato mice. To observe BEC-to-hepatocyte differentiation, mice were allowed to recover on normal diet following CDE diet-induced liver injury. Livers were collected from all mice and analyzed by quantitative real-time polymerase chain reaction, western blotting, immunohistochemistry, and immunofluorescence. We show that mice with lack of β-catenin in hepatocytes placed on the CDE diet develop severe liver injury with impaired hepatocyte proliferation, creating a stimulus for BECs to differentiate into hepatocytes. In particular, we use both hepatocyte and BEC lineage tracing to show that BECs differentiate into hepatocytes, which go on to repopulate the liver during long-term recovery. Conclusion: β-catenin is important for liver regeneration after CDE diet-induced liver injury, and BEC-derived hepatocytes can permanently incorporate into the liver parenchyma to mediate liver regeneration.
肝损伤后的再生通常是通过肝细胞的增殖来介导的，尽管最近的研究表明，在肝实质细胞增殖受损时，胆管上皮细胞（BECs）在严重肝损伤时可以分化为肝细胞。我们研究了肝特异性β-catenin 缺失对严重肝损伤恢复和 BEC 向肝细胞分化的影响。为了诱导肝损伤，我们用胆碱缺乏、蛋氨酸补充（CDE）饮食处理了三种不同的小鼠模型，第一种模型是 BEC 和肝细胞中均缺失β-catenin 的小鼠（Albumin-Cre; Ctnnb1 小鼠）。在我们的第二个模型中，我们通过注射 Ctnnb1; Rosa-stop-EYFP 小鼠用腺相关病毒血清型 8 编码的 Cre 重组酶进行肝系追踪，该病毒受甲状腺结合球蛋白启动子的控制，只能感染肝细胞。最后，我们通过 Krt19-Cre; Rosa-stop-tdTomato 小鼠进行 BEC 系追踪。为了观察 BEC 向肝细胞的分化，在 CDE 饮食诱导的肝损伤后，让小鼠在正常饮食中恢复。从所有小鼠中收集肝脏并进行实时定量聚合酶链反应、western blot、免疫组织化学和免疫荧光分析。我们表明，在 CDE 饮食下缺乏肝细胞中的β-catenin 的小鼠会发生严重的肝损伤，伴有肝细胞增殖受损，为 BEC 分化为肝细胞创造了刺激。特别是，我们使用肝和 BEC 系追踪来显示 BEC 分化为肝细胞，这些肝细胞在长期恢复过程中继续重新填充肝脏。结论：β-catenin 对 CDE 饮食诱导的肝损伤后的肝再生很重要，BEC 来源的肝细胞可以永久性地整合到肝实质中，从而介导肝再生。
