TGF-β and Cancer Group. Oncobell Program, Bellvitge Biomedical Research Institute (IDIBELL), L'Hospitalet de Llobregat, Barcelona, Spain; Oncology Program, CIBEREHD, National Biomedical Research Institute on Liver and Gastrointestinal Diseases, Instituto de Salud Carlos III, Spain.
TGF-β and Cancer Group. Oncobell Program, Bellvitge Biomedical Research Institute (IDIBELL), L'Hospitalet de Llobregat, Barcelona, Spain; Oncology Program, CIBEREHD, National Biomedical Research Institute on Liver and Gastrointestinal Diseases, Instituto de Salud Carlos III, Spain; Department of Physiological Sciences, Faculty of Medicine and Health Sciences, University of Barcelona, Spain.
Redox Biol. 2021 Apr;40:101841. doi: 10.1016/j.redox.2020.101841. Epub 2020 Dec 23.
Liver is a unique organ in displaying a reparative and regenerative response after acute/chronic damage or partial hepatectomy, when all the cell types must proliferate to re-establish the liver mass. The NADPH oxidase NOX4 mediates Transforming Growth Factor-beta (TGF-β) actions, including apoptosis in hepatocytes and activation of stellate cells to myofibroblasts. Aim of this work was to analyze the impact of NOX4 in liver regeneration by using two mouse models where Nox4 was deleted: 1) general deletion of Nox4 (NOX4-/-) and 2) hepatocyte-specific deletion of Nox4 (NOX4hepKO). Liver regeneration was analyzed after 2/3 partial hepatectomy (PH). Results indicated an earlier recovery of the liver-to-body weight ratio in both NOX4-/- and NOX4hepKO mice and an increased survival, when compared to corresponding WT mice. The regenerative hepatocellular fat accumulation and the parenchyma organization recovered faster in NOX4 deleted livers. Hepatocyte proliferation, analyzed by Ki67 and phospho-Histone3 immunohistochemistry, was accelerated and increased in NOX4 deleted mice, coincident with an earlier and increased Myc expression. Primary hepatocytes isolated from NOX4 deleted mice showed higher proliferative capacity and increased expression of Myc and different cyclins in response to serum. Transcriptomic analysis through RNA-seq revealed significant changes after PH in NOX4-/- mice and support a relevant role for Myc in a node of regulation of proliferation-related genes. Interestingly, RNA-seq also revealed changes in the expression of genes related to activation of the TGF-β pathway. In fact, levels of active TGF-β1, phosphorylation of Smads and levels of its target p21 were lower at 24 h in NOX4 deleted mice. Nox4 did not appear to be essential for the termination of liver regeneration in vivo, neither for the in vitro hepatocyte response to TGF-β1 in terms of growth inhibition, which suggest its potential as therapeutic target to improve liver regeneration, without adverse effects.
肝脏在急性/慢性损伤或部分肝切除后具有修复和再生反应，此时所有细胞类型都必须增殖以重建肝质量。NADPH 氧化酶 NOX4 介导转化生长因子-β (TGF-β) 的作用，包括肝细胞凋亡和星状细胞向肌成纤维细胞的激活。本工作旨在分析 NOX4 在肝脏再生中的作用，使用两种 Nox4 缺失的小鼠模型：1) 普遍缺失 Nox4 (NOX4-/-) 和 2) 肝细胞特异性缺失 Nox4 (NOX4hepKO)。在 2/3 部分肝切除 (PH) 后分析肝脏再生。结果表明，与相应的 WT 小鼠相比，NOX4-/-和 NOX4hepKO 小鼠的肝重/体重比更早恢复，存活率更高。NOX4 缺失肝脏的再生肝细胞脂肪积累和实质组织恢复更快。Ki67 和磷酸化组蛋白 3 免疫组织化学分析显示，NOX4 缺失小鼠的肝细胞增殖更快且增加，与 Myc 的更早和更高表达一致。从 NOX4 缺失小鼠分离的原代肝细胞表现出更高的增殖能力，并且在响应血清时表达更高水平的 Myc 和不同的细胞周期蛋白。通过 RNA-seq 进行的转录组分析显示，NOX4-/-小鼠在 PH 后发生了显著变化，支持 Myc 在增殖相关基因调控节点中的重要作用。有趣的是，RNA-seq 还揭示了与 TGF-β 途径激活相关的基因表达变化。事实上，在 NOX4 缺失小鼠中，24 小时时 TGF-β1 的活性、Smads 的磷酸化以及其靶基因 p21 的水平较低。在体内，Nox4 似乎不是肝脏再生终止所必需的，也不是体外肝细胞对 TGF-β1 的反应所必需的，因为生长抑制没有不良影响。
