GRHL2 induces liver fibrosis and intestinal mucosal barrier dysfunction in non-alcoholic fatty liver disease via microRNA-200 and the MAPK pathway.

Ying Wang,Ran Ao,Zishu Zeng,Lin Guan

doi:10.1111/jcmm.15212

Abstract

Non‐alcoholic fatty liver disease (NAFLD) serves as the most common subtype of liver diseases and cause of liver dysfunction, which is closely related to obesity and insulin resistance. In our study, we sought to investigate effect of transcription factor grainyhead‐like 2 (GRHL2) on NAFLD and the relevant mechanism. NAFLD mouse model was established with a high‐fat feed. Then, serum was extracted from NAFLD patients and mice, followed by ectopic expression and depletion experiments in NAFLD mice and L02 cells. Next, the correlation between GRHL2 and microRNA (miR)‐200 and between miR‐200 and sirtuin‐1 (SIRT1) was evaluated. The observations demonstrated that miR‐200 and GRHL2 were overexpressed in the serum of NAFLD patients and mice, while SIRT1 was poorly expressed. GRHL2 positively regulated miR‐200 by binding to miR‐200 promoter region, which negatively targeted SIRT1. The inhibition of miR‐200 and GRHL2 or SIRT1 overexpression lowered HA and LN in mouse liver tissue, occludin and ZO‐1 in mouse small intestine tissue, TNF‐α and IL‐6 in mouse serum, glucose, total cholesterol (TC), triglyceride (TG), aspartate aminotransferase (AST) and alanine aminotransferase (ALT) in mouse serum, and also inhibited liver fibrosis and intestinal mucosal barrier dysfunction. Meanwhile, GRHL2 induced activation of MAPK signalling pathway in NAFLD mice. Collectively, GRHL2 played a contributory role in NAFLD by exacerbating liver fibrosis and intestinal mucosal barrier dysfunction with the involvement of miR‐200‐dependent SIRT1 and the MAPK signalling pathway.

Highlights

As a new health problem, non-alcoholic fatty liver disease (NAFLD) influences one-third of adults and an increasing number of children in developed countries.[1]
reverse transcription quantitative polymerase chain reaction (RT-qPCR) and Western blot analysis were performed to determine SIRT1 expression in normal human hepatocyte L02, and the results revealed obvious decrease in SIRT1 expression in response to sh-negative control (NC)+microRNA 200 S100B (miR-200) mimic or sh-grainyhead-like 2 (GRHL2)+miR-200 mimic compared with sh-NC+NC mimic or sh-GRHL2+NC mimic, respectively (Figure 3F, G)
Western blot analysis was adopted to determine the expressions of mitogen-activated protein kinase (MAPK)-related markers in liver tissues of NAFLD mice, and the results demonstrated that phosphorylated extracellular signal–regulated kinase (ERK) and phosphorylated p38 expression potently reduced in liver tissues of mice injected with sh-GRHL2, while no obvious change was seen in ERK, p38, Jun NH2-terminal kinase (JNK) and phosphorylated JNK expression (Figure 5D)

Summary

Introduction

As a new health problem, non-alcoholic fatty liver disease (NAFLD) influences one-third of adults and an increasing number of children in developed countries.[1]. NAFLD involves a spectrum of liver injuries including steatosis and steatohepatitis with or without fibrosis.[2]. NAFLD affected nearly one-third of people, and patients with NAFLD-related terminal or deteriorative liver diseases have become. One of the major groups receiving liver transplantation.[3]. Fibrosis is one of the causes for NAFLD,[4] and the degree of liver fibrosis is connected with therapeutic decisions or disease outcomes.[5]. Intestinal mucosal barrier dysfunction is intricately relevant to liver diseases, and progression of NAFLD might be attributed to impaired gut-liver axis.[6]. The current study was designed to investigate new molecular mechanisms and explore new targets for NAFLD and associated disorders

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Discussion

Conclusion