TGEV nucleocapsid protein induces cell cycle arrest and apoptosis through activation of p53 signaling

Area of Science:

• Virology
• Molecular Biology
• Cell Biology

Background:

• Transmissible Gastroenteritis Virus (TGEV) infection is known to induce cell cycle arrest and apoptosis.
• The specific viral gene responsible for these effects has not been identified.
• Previous research indicated p53 signaling pathway activation during TGEV infection.

Purpose of the Study:

• To investigate the effects of the TGEV nucleocapsid (N) protein on host cell proliferation and apoptosis.
• To elucidate the molecular mechanisms by which TGEV N protein influences cell cycle regulation and programmed cell death.
• To determine the role of the p53 signaling pathway in TGEV N protein-mediated cellular effects.

Main Methods:

• Transfection of PK-15 cells with TGEV N gene.
• Cell cycle analysis (S and G2/M phase arrest).
• Apoptosis assays (Bax translocation, cytochrome c release, caspase-3 activation).
• Western blot analysis for p53, p21, cyclin B1, cdc2, and cdk2 expression.
• Treatment with a p53 inhibitor.

Main Results:

• TGEV N protein expression suppressed PK-15 cell proliferation, inducing cell cycle arrest at S and G2/M phases and apoptosis.
• N protein expression led to increased p53 and p21 levels, suppressing cyclin B1, cdc2, and cdk2.
• TGEV N protein promoted Bax translocation to mitochondria, cytochrome c release, and subsequent caspase-3 activation, leading to apoptosis.
• A p53 inhibitor reversed N protein-induced cell cycle arrest and apoptosis by restoring protein expression and preventing mitochondrial pathway activation.

Conclusions:

• The TGEV nucleocapsid (N) protein is a key viral factor inducing cell cycle arrest at S and G2/M phases and apoptosis.
• TGEV N protein activates the p53 signaling pathway, leading to cell cycle dysregulation and programmed cell death.
• These findings highlight the critical role of the TGEV N protein in the pathogenesis of TGEV infection.