MiR-125b Suppression Inhibits Apoptosis and Negatively Regulates Sema4D in Avian Leukosis Virus-Transformed Cells

Area of Science:

• Veterinary Virology
• Molecular Oncology
• Avian Pathology

Background:

• Subgroup J avian leukosis virus (ALV-J) is an oncogenic retrovirus causing significant economic losses in the poultry industry.
• Previous research indicated that microRNA-125b (miR-125b) is downregulated in ALV-J-induced tumors.
• Understanding the molecular mechanisms of ALV-J tumorigenesis is crucial for developing effective control strategies.

Purpose of the Study:

• To investigate the role of miR-125b in ALV-J infection and the development of associated tumors.
• To identify the molecular targets of miR-125b involved in ALV-J pathogenesis.
• To elucidate the functional relationship between miR-125b and Semaphorin 4D (Sema4D) in chicken tumor cells.

Main Methods:

• Cell culture experiments involving knockdown and overexpression of miR-125b in HP45 and DF1 cell lines.
• Bioinformatics analysis and luciferase reporter assays to predict and validate miR-125b targets.
• Quantitative real-time PCR (qRT-PCR) to measure mRNA expression levels of miR-125b and Sema4D.
• Animal infection models and in vitro assays to assess the functional impact of Sema4D during ALV-J infection.

Main Results:

• miR-125b expression levels were inversely correlated with Sema4D expression in chicken cells.
• Overexpression of miR-125b induced late-stage apoptosis in HP45 cells, while its knockdown reduced apoptosis.
• Sema4D mRNA levels were upregulated in ALV-J-infected tissues and cells.
• Downregulation of miR-125b and overexpression of Sema4D inhibited apoptosis, suggesting a pro-survival role in tumor cells.

Conclusions:

• miR-125b targets Semaphorin 4D (Sema4D) mRNA.
• The miR-125b/Sema4D axis plays a significant role in the proliferation of ALV-J-induced tumor cells.
• These findings contribute to understanding the molecular mechanisms underlying ALV-J tumorigenesis and offer potential targets for intervention.