Orphan nuclear receptor NR4A2 inhibits hepatic stellate cell proliferation through MAPK pathway in liver fibrosis

Area of Science:

• Hepatology
• Molecular Biology
• Cell Biology

Background:

• Hepatic stellate cells (HSCs) are central to liver fibrosis, a condition marked by extracellular matrix (ECM) buildup.
• NR4A2, a nuclear receptor, regulates critical cellular functions, but its role in HSCs remains undefined.

Purpose of the Study:

• To investigate the expression and function of NR4A2 in hepatic stellate cells during liver fibrogenesis.
• To elucidate the impact of NR4A2 on HSC proliferation, cell cycle, apoptosis, and the MAPK signaling pathway.

Main Methods:

• Quantitative real-time PCR, Western blotting, immunohistochemistry, and immunofluorescence were used to assess NR4A2 expression.
• NR4A2 knockdown was performed in HSCs to analyze its effects on proliferation, cell cycle, apoptosis, and MAPK pathway activation.

Main Results:

• NR4A2 expression was significantly downregulated in fibrotic liver tissues and activated HSCs.
• NR4A2 knockdown led to increased expression of alpha-smooth muscle actin and collagen type I.
• Silencing NR4A2 promoted HSC proliferation, increased S-phase cell population, and reduced phosphorylation of ERK1/2, p38, and JNK.

Conclusions:

• NR4A2 inhibits HSC proliferation and reduces ECM production, likely via the MAPK pathway.
• NR4A2 represents a potential therapeutic target for mitigating liver fibrosis.