State Key Laboratory of Organ Failure Research, Guangdong Provincial Research Center for Liver Fibrosis, Department of Infectious Diseases and Hepatology Unit, Nanfang Hospital, Southern Medical University, Guangzhou, Guangdong 510515, China.
Biomedical Research Center, Southern Medical University, Guangzhou, Guangdong 510515, China.
Biomed Res Int. 2020 Aug 5;2020:8016306. doi: 10.1155/2020/8016306. eCollection 2020.
There remain few data about the role of homeostatic compaction in hepatic polarization. A previous study has found that mechanical compaction can accelerate hepatocyte polarization; however, the cellular mechanism underlying the effect is mostly unclear. Hepatocyte nuclear factor 4 alpha (HNF4) is crucial for hepatic polarization in liver morphogenesis. Therefore, we sought to identify any possible involvement of HNF4 in the process of hepatocyte polarization accelerated by mechanical compaction. We first verified in the nonhepatic cell model HEK-293T, and the hepatic cell model primary hepatocytes that the mechanical compaction on cell aggregates simulated by using transient centrifugation can directly activate the expression of HNF4 promoters. Moreover, data using primary hepatocytes showed that the HNF4 expression is positively associated with the levels of compaction force: 2.1-folds higher at the mRNA level and 2.1-folds higher at the protein level for 500 g vs. 0 g. Furthermore, activated HNF4 expression is associated with the enhanced biliary canalicular formation and the increased production of albumin and urea. Pretreatment with Latrunculin B, an inhibitor of F-actin, and SHE78-7, an inhibitor of E-cadherin, which both interrupt the pathway of mechanical transduction, partially but significantly reduced the HNF4 expression and production of albumin and urea. In conclusion, HNF4 can be actively involved in the hepatic polarization in the context of environmental mechanical compaction.
关于内稳态致密在肝极化中的作用，目前数据仍然较少。先前的研究发现，机械致密可以加速肝细胞极化；然而，其作用的细胞机制在很大程度上尚不清楚。肝细胞核因子 4 阿尔法（HNF4）在肝形态发生中对肝极化至关重要。因此，我们试图确定 HNF4 是否可能参与机械致密加速的肝细胞极化过程。我们首先在非肝细胞模型 HEK-293T 和肝原代细胞中验证，通过瞬时离心模拟的细胞聚集体的机械致密可以直接激活 HNF4 启动子的表达。此外，使用原代肝细胞的数据表明，HNF4 的表达与致密力水平呈正相关：mRNA 水平升高 2.1 倍，蛋白水平升高 2.1 倍，500g 比 0g。此外，激活的 HNF4 表达与胆管形成的增强以及白蛋白和尿素的产生增加有关。Latrunculin B（一种 F-肌动蛋白抑制剂）和 SHE78-7（一种 E-钙粘蛋白抑制剂）预处理，这两种抑制剂都中断了机械转导途径，部分但显著降低了 HNF4 的表达和白蛋白和尿素的产生。总之，HNF4 可以在环境机械致密的情况下主动参与肝极化。
