title: Anti-apoptotic genes Bcl-2 and Bcl-xL overexpression can block iridovirus serine/threonine kinase-induced Bax/mitochondria-mediated cell death in GF-1 cells.
abstract: Although serine/threonine (ST) kinase is known to induce host cell death in GF-1 cells, it remains unclear how ST kinase induces mitochondrial function loss. In the present study, we addressed the issue of mitochondrial function loss by determining whether the Bcl-2 family members Bcl-2 and Bcl-xL can prevent ST kinase-induced cell death activity via interacting with the pro-apoptotic gene Bax. Grouper fin cells (GF-1) carrying EGFP-Bal-xL and EGFP-Bcl-2 fused genes were selected, established in cell culture, and used to examine the involvement of Bcl-2 and Bcl-xL overexpression in protection of GF-1 cells from the effects of the giant sea perch iridovirus (GSIV) ST kinase gene. Using the TUNEL assay, we found that EGFP-Bcl-2 and EGFP-Bcl-xL reduced GSIV ST kinase-induced apoptosis to 20% all at 24 h and 48 h post-transfection (pt). Also, Bcl-2 and Bcl-xL substantially reduced the percentage of cells with GSIV ST kinase-induced loss of mitochondrial membrane potential (Δψps) at 24 and 48 hpt, respectively, and this reduction correlated with a 30% and 50% enhancement of host cell viability at 24 and 48 hpt as compared with vector control. Moreover, analysis of the effect of Bcl-2 and Bcl-xL interaction with Bax targeted to mitochondria during ST kinase expression at 48 hpt found that Bcl-2 and Bcl-xL also interacted with Bax to block cytochrome c release. Finally, Bcl-2 and Bcl-xL overexpression caused blockage of ST kinase function at 48 hpt, which was correlated with preventing caspase-9 and -3 cleavage and activation, thereby blocking downstream death signaling events. Taken together, our results suggest that the ST kinase-induced Bax/mitochondria-mediated cell death pathway can be blocked by the interaction of Bcl-2 and Bcl-xL with Bax to inhibit cytochrome c release during MMP loss. This rescue activity also correlated with inhibition of caspase-9 and -3 activation, thereby enhancing cell viability.
authors.affiliation: Lab of Molecular Virology and Biotechnology, Institute of Biotechnology, National Cheng Kung University, No. 1 University Road, Tainan City 701, Taiwan, ROC; Department of Life Sciences, College of Bioscience and Biotechnology, National Cheng Kung University, No. 1 University Road, Tainan City 701, Taiwan, ROC.
authors.forename: Latif
authors.initials: L
authors.lastname: Reshi
authors.affiliation: Department of Life Sciences, College of Bioscience and Biotechnology, National Cheng Kung University, No. 1 University Road, Tainan City 701, Taiwan, ROC.
authors.forename: Hua-Ven
authors.initials: HV
authors.lastname: Wang
authors.affiliation: Institute of Cellular and Organismic Biology, Academia Sinica, Nankang, Taipei 115, Taiwan, ROC.
authors.forename: Cho-Fat
authors.initials: CF
authors.lastname: Hui
authors.affiliation: Lab of Molecular Virology and Biotechnology, Institute of Biotechnology, National Cheng Kung University, No. 1 University Road, Tainan City 701, Taiwan, ROC.
authors.forename: Yu-Chin
authors.initials: YC
authors.lastname: Su
authors.affiliation: Lab of Molecular Virology and Biotechnology, Institute of Biotechnology, National Cheng Kung University, No. 1 University Road, Tainan City 701, Taiwan, ROC; Department of Biotechnology and Bioindustry, National Cheng Kung University, No. 1 University Road, Tainan City 701, Taiwan, ROC. Electronic address: jrhong@mail.ncku.edu.tw.
authors.forename: Jiann-Ruey
authors.initials: JR
authors.lastname: Hong
mesh_terms: D000818:Animals; D001492:Bass / Q000235:genetics* / Q000378:metabolism / Q000821:virology; D002460:Cell Line; D029941:Fish Proteins / Q000235:genetics* / Q000378:metabolism; D017994:Iridovirus / Q000502:physiology*; D053078:Membrane Potential, Mitochondrial; D008928:Mitochondria / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000235:genetics* / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics* / Q000378:metabolism; D015398:Signal Transduction; D051028:bcl-2-Associated X Protein / Q000235:genetics* / Q000378:metabolism; D051020:bcl-X Protein / Q000235:genetics / Q000378:metabolism
chemical_list: D029941:Fish Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D051028:bcl-2-Associated X Protein; D051020:bcl-X Protein; D017346:Protein Serine-Threonine Kinases
keywords: Grouper sea perch iridovirus; Mitochondrial membrane potential loss; Pro-apoptotic Bax; Serine/threonine kinase; p53