GSIV serine/threonine kinase can induce apoptotic cell death via p53 and pro-apoptotic gene Bax upregulation in fish cells

Abstract

Previous studies have shown that GSIV induces apoptotic cell death through upregulation of the pro-apoptotic genes Bax and Bak in Grouper fin cells (GF-1 cells). However, the role of viral genome-encoded protein(s) in this death process remains unknown. In this study, we demonstrated that the Giant seaperch iridovirus (GSIV) genome encoded a serine/threonine kinase (ST kinase) protein, and induced apoptotic cell death via a p53-mediated Bax upregulation approach and a downregulation of Bcl-2 in fish cells. The ST kinase expression profile was identified through Western blot analyses, which indicated that expression started at day 1 h post-infection (PI), increased up to day 3, and then decreased by day 5 PI. This profile indicated the role of ST kinase expression during the early and middle phases of viral replication. We then cloned the ST kinase gene and tested its function in fish cells. The ST kinase was transiently expressed and used to investigate possible novel protein functions. The transient expression of ST kinase in GF-1 cells resulted in apoptotic cell features, as revealed with Terminal deoxynucleotidyl transferase biotin-dUTP nick-end labeling (TUNEL) assays and Hoechst 33258 staining at 24 h (37 %) and 48 h post-transfection (PT) (49 %). Then, through studies on the mechanism of cell death, we found that ST kinase overexpression could upregulate the anti-stress gene p53 and the pro-apoptotic gene Bax at 48 h PT. Interestingly, this upregulation of p53 and Bax also correlated to alterations in the mitochondria function that induced loss of mitochondrial membrane potential (MMP) and activated the initiator caspase-9 and the effector caspase-3 in the downstream. Moreover, when the p53-dependent transcriptional downstream gene was blocked by a specific transcriptional inhibitor, it was found that pifithrin-α not only reduced Bax expression, but also averted cell death in GF-1 cells during the ST kinase overexpression. Taken altogether, these results suggested that aquatic GSIV ST kinase could induce apoptosis via upregulation of p53 and Bax expression, resulting in mitochondrial disruption, which activated a downstream caspases-mediated cell death pathway.

Fighting Cancer with Mathematics and Viruses

“…These models only allowed budding as a mechanism for viral particle production from syncytia, assuming that no apoptosis occurs from fused cells [ 158 ]. Recent reports suggest that this may not be the case [ 159 , 160 , 161 , 162 , 163 , 164 , 165 ], depending on the virus; adjustments during model development and fitting can resolve such issues. In their model, Jacobsen and Pilyugin found that an increase in burst size would allow for tumor control.…”

Fighting Cancer with Mathematics and Viruses

“…These models only allowed budding as a mechanism for viral particle production from syncytia, assuming that no apoptosis occurs from fused cells [130]. Recent reports give evidence that this may not be the case [131][132][133][134][135][136][137], depending on the virus; adjustments during model development and fitting can resolve such issues. In their model, Jacobsen and Pilyugin found that an increase in burst size would allow for tumor control.…”

Circular RNA CircEZH2 Suppresses Transmissible Gastroenteritis Coronavirus-induced Opening of Mitochondrial Permeability Transition Pore via Targeting MiR-22 in IPEC-J2

“…Persistent opening of mPTP can lead to decrease of the mitochondrial membrane potential (△ψm), reduction Ivyspring International Publisher of ATP production, release of ROS from mitochondria, finally mitochondrial damage [11][12][13][14]. Viral infection is one of the important factors for mitochondrial injury [15][16][17][18]. Studies have confirmed that TGEV infection can cause intracellular mitochondrial injury.…”