Anti-Bcl-2 family members, zfBcl-xL and zfMcl-1a, prevent cytochrome c release from cells undergoing betanodavirus-induced secondary necrotic cell death

• Published in: Apoptosis (London) Vol. 12; no. 6; pp. 1043 - 1060
• Main Authors: Chen, Shi-Ping, Wu, Jen-Leih, Su, Yu-Chin, Hong, Jiann-Ruey
• Format: Journal Article
• Language: English
• Published: London New York : Kluwer Academic Publishers-Plenum Publishers 01.06.2007; Springer Nature B.V
• Subjects: Apoptosis; Bcl-2 protein; Betanodavirus; Cell death; Cells; Cycloheximide; Cytochrome; Cytochrome c; Cytochromes; Fish diseases; Gene expression; Membrane permeability; Mitochondria; Mitochondrial permeability transition pore; Mortality; Necrosis; Protein A; Protein biosynthesis; Protein synthesis; Proteins; Secondary necrosis; Transfection; Ultrastructure; Viruses; Western blotting; zfBcl-xL
• ISSN: 1360-8185; 1573-675X
• DOI: 10.1007/s10495-006-0032-x

Nervous necrosis virus (NNV)-induced, host cell apoptosis mediates secondary necrosis by an ill-understood process. In this study, redspotted grouper nervous necrosis virus (RGNNV) is shown to induce mitochondria-mediated necrotic cell death in GL-av cells (fish cells) via cytochrome c release, and anti-apoptotic proteins are shown to protect these cells from death. Western blots revealed that cytochrome c release coincided with disruption of mitochondrial ultrastructure and preceded necrosis, but did not correlate with caspases activation. To identify the mediator(s) of this necrotic process, a protein synthesis inhibitor (cycloheximide; CHX; 0.33 μg/ml) was used to block cytochrome c release as well as PS exposure and mitochondrial membrane permeability transition pore (MMP) loss. CHX (0.33 μg/ml) completely blocked viral protein B2 expression, and partly blocked protein A, protein α, and a pro-apoptotic death protein (Bad) expression. Overexpression of B2 gene increased necrotic-like cell death up to 30% at 48 h post-transfection, suggesting that newly synthesized protein (B2) may be involved in this necrotic process. Finally, necrotic death was prevented by overexpression of Bcl-2 family proteins, zfBcl-xL and xfMcl-1a. Thus, new protein synthesis and release of cytochrome c are required for RGNNV-induced necrotic cell death, which can be blocked by anti-apoptotic Bcl-2 members.