Comparative transcriptome analysis reveals the role of p53 signalling pathway during red‐spotted grouper nervous necrosis virus infection in Lateolabrax japonicus brain cells

Abstract

Nervous necrosis virus (NNV) is one of the fish pathogens that have caused mass mortalities of many marine and freshwater fishes in the world. To better comprehend the molecular immune mechanism of sea perch (Lateolabrax japonicus) against NNV infection, the comparative transcriptome analysis of red‐spotted grouper nervous necrosis virus (RGNNV)‐infected or mock‐infected L. japonicus brain (LJB) cells was performed via RNA sequencing technology. Here, 1,969 up‐regulated genes and 9,858 down‐regulated genes, which were widely implicated in immune response pathways, were identified. Furthermore, we confirmed that p53 signalling pathway was repressed at 48 hr post‐RGNNV infection, as indicated by up‐regulation of Mdm2 and down‐regulation of p53 and its downstream target genes, including Bax, Casp8 and CytC. Overexpression of L. japonicus p53 (Ljp53) significantly inhibited RGNNV replication and up‐regulated the expression of apoptosis‐related genes, whereas the down‐regulation caused by pifithrin‐α led to the opposite effect, suggesting Ljp53 might promote cell apoptosis to repress virus replication. Luciferase assay indicated that Ljp53 could enhance the promoter activities of zebrafish interferon (IFN)1, indicating that Ljp53 could exert its anti‐RGNNV activities by enforcing the type I IFN response. This study revealed the potential antiviral role of p53 during NNV infection.

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“…In another study also performed with DLB-1 cells, the transcriptomic profiles obtained from European sea bass head-kidney leucocytes incubated with NNV infected and uninfected cells were very similar, supporting that cell-mediated cytotoxic activity in sea bass is not primed upon NNV infection [231]. Other cells used for transcriptome analysis were Asian seabass (Lateolabrax japonicus) epithelial cells (SB) [229], grouper kidney (GK) cells [228] and Lateolabrax japonicus brain cells (LJB) [233]. The assembly of the transcriptome of NNV-infected SB cells, as in the previously described cell lines, showed a strong induction of various genes relevant to innate immunity which were identified as receptor-transporting 3 (RTP3), Viperin, IRF3, IFN and two heat shock protein (HSP) family members (Hsp30 and 70) [229].…”

“…In recent years, a great deal of progress has been made on high-throughput tools for sequencing the transcriptome (RNA-Seq), enabling genome-wide transcriptomic analysis and providing valuable information for understanding virus-host interactions [227]. Different transcriptomic analyses have been performed on both NNV-infected cells [228][229][230][231][232][233] and fish [234][235][236][237][238].…”

“…It was also observed that the p53 signaling pathway was involved in NNV infection and inhibited by RGNNV. The overexpression of L. japonicus p53 (Ljp53) significantly inhibited RGNNV replication and up-regulated the expression of apoptosis-related genes, suggesting that Ljp53 might promote cell apoptosis to repress virus replication [233].…”

Transcriptomic Analysis of Fish Hosts Responses to Nervous Necrosis Virus

“…As seen in the DLB-1 cell line, RGNNV infection of L. japonicus brain cells (LJB) resulted in immune response regulation and apoptotic-related proteins' transcription (e.g., ISG15, IRFs, TLRs, HSPs) to assist the virus in escaping the host antiviral response. In the same study, the p53 signaling pathway was shown to be repressed by down-regulation of p53 and its downstream target genes (BAX, CASP8, CytC) and by up-regulation of its negative regulators MDM2 and MDM4 [40]. The p53 signaling pathway repression has a dual effect in the viral response by inhibiting the innate antiviral immunity and the type I IFN response, and the virus-infected cells apoptosis [120], thus promoting virus replication in RGNNV-infected LJB cells and facilitating the transmission of newly formed viral particles to other cells.…”

“…In order to take a closer look at the effects of nodavirus in infected fish, several studies have focused on the transcriptome profiling of in vitro infected cells. Such investigations have been performed in brain cell lines of European sea bass (DLB-1 cell line) [43] and Lateolabrax japonicus (LJB cells) [40,51], in grouper kidney cells (GK cell line) [30], in European sea bass head-kidney leukocytes [37], and in Asian sea bass epithelial cells (SB cell line) [35]. Similar studies were performed in ZF-4 cells, an embryonic-derived zebrafish cell line [34], in striped snakehead fish cells (SSN-1) [36], and in orange-spotted grouper (Epinephelus coioides) fin cells [39].…”