ABSTRACT: Stage-specific expression of TNFα regulates bad/bid-mediated apoptosis and RIP1/ROS-mediated secondary necrosis in Birnavirus-infected fish cells
Project description:Infectious pancreatic necrosis virus (IPNV) is an aquatic virus that causes acute infection in freshwater and marine fish. The stage-specific expression of TNFα regulates Bad/Bid-mediated apoptosis and RIP1/ROS-mediated secondary necrosis in IPNV-infected fish cells. Using microRNA microarray and real-time quantitative PCR assays, the expression patterns of microRNA were characterized in different replication stages of IPNV or stimulation of LPS.
Project description:Infectious pancreatic necrosis virus (IPNV) is an aquatic virus that causes acute infection in freshwater and marine fish. The stage-specific expression of TNFα regulates Bad/Bid-mediated apoptosis and RIP1/ROS-mediated secondary necrosis in IPNV-infected fish cells. Using microRNA microarray and real-time quantitative PCR assays, the expression patterns of microRNA were characterized in different replication stages of IPNV or stimulation of LPS. Two-condition experiment, normal vs IPNV-infected cells (at 6, 12 or 24 hr post-infection), or normal vs LPS-stimulated cells (at 6, 12 or 24 h post-treatment).
Project description:Infectious pancreatic necrosis virus (IPNV) is a fish-derived pathogen and possess a bi-segmented, double-stranded RNA genome. By using zebrafish 14K oligo-microarray and quantitative RT-PCR, we identified differential expression of a defined subset of genes involved in apoptosis and immunity at 6-, 12- and 24- hour after IPNV infection. Transcripts divided into 11 functional categories were significantly modulated by IPNV, including immune response, apoptosis, transcription, signal transduction, lipid and cholesterol metabolism, carbohydrate metabolism, oxidative phosphorylation, cell cycle, protein degradation, protein folding and stress response, protein synthesis, nucleoside metabolism and synthesis. Most of pro-apoptotic bcl-2 family members were up-regulated after IPNV infection. Activation of pro-apoptotic members might disrupt potential of mitochondria and leaded to the mitochondria-mediated apoptosis in the late stage of IPNV infection. After treating the IPNV-infected cells with TNFα inhibitor AP126, expression of two bcl-2 family genes Bad and Bid and activation of caspase-8 and -3 had been inhibited significantly in early stage of IPNV infection. Expression of RIP-1 and Bmf-1 these two necroptosis-related genes and production of ROS were diminished in virus-infected cells which pre-treated with AP126. Our study shows the interactions between host cells and IPNV, the molecular mechanisms involved in IPNV-induced pathogenesis, and the variation of transcriptome through TNFα during infection which shows the important component of host defense. TNFα might lead to apoptosis in early stage and necrosis in late stage in ZF4 cells infected by IPNV. TNFα is crucial to apoptosis and ROS-mediated necrosis caused by IPNV in zebrafish cells.
Project description:Infectious pancreatic necrosis virus (IPNV) is a fish-derived pathogen and possess a bi-segmented, double-stranded RNA genome. By using zebrafish 14K oligo-microarray and quantitative RT-PCR, we identified differential expression of a defined subset of genes involved in apoptosis and immunity at 6-, 12- and 24- hour after IPNV infection. Transcripts divided into 11 functional categories were significantly modulated by IPNV, including immune response, apoptosis, transcription, signal transduction, lipid and cholesterol metabolism, carbohydrate metabolism, oxidative phosphorylation, cell cycle, protein degradation, protein folding and stress response, protein synthesis, nucleoside metabolism and synthesis. Most of pro-apoptotic bcl-2 family members were up-regulated after IPNV infection. Activation of pro-apoptotic members might disrupt potential of mitochondria and leaded to the mitochondria-mediated apoptosis in the late stage of IPNV infection. After treating the IPNV-infected cells with TNFM-NM-1 inhibitor AP126, expression of two bcl-2 family genes Bad and Bid and activation of caspase-8 and -3 had been inhibited significantly in early stage of IPNV infection. Expression of RIP-1 and Bmf-1 these two necroptosis-related genes and production of ROS were diminished in virus-infected cells which pre-treated with AP126. Our study shows the interactions between host cells and IPNV, the molecular mechanisms involved in IPNV-induced pathogenesis, and the variation of transcriptome through TNFM-NM-1 during infection which shows the important component of host defense. TNFM-NM-1 might lead to apoptosis in early stage and necrosis in late stage in ZF4 cells infected by IPNV. TNFM-NM-1 is crucial to apoptosis and ROS-mediated necrosis caused by IPNV in zebrafish cells. Zebrafish ZF4 cell line was derived from 24h post-fertilization zebrafish embryos. Previous studies have been shown that adult zebrafish and zebrafish cell line could be infected with IPNV. In the present study, ZF4 cells were infected with IPNV, and total RNA was isolated from infected and uninfected control cells at 0 h, 6 h, 12 h, 24 h post-infection. Microarray analysis gene expression between IPNV-infected and uninfected cells relative to internal control on slides. The zebrafish 14K oligo microarray we used comprise 1800 zebrafish gene sequences from the NCBI and a database of 12768 putative open reading frames using NCBI zebrafish EST sequence information. Data files were imported into GeneSpring GX 7.3 for further analysis. Expression data sets must pass all the following quality control categories before used for cluster analysis. Clustering analysis allowed us to observe differences in cellular gene expression. A similar expression pattern was seen when comparing differentially expressed host cell genes between 12 and 24 h post-infection. The expression profiles were significantly different between 6 and 12 h post-infection. Therefore, we conclude that the regulation of host gene expression was changed after 12 h post-infection, and progressed into the late stage. To understand the interactions between host cells and IPNV and the molecular mechanisms involved in IPNV-induced pathogenesis, we used zebrafish oligo microarrays to investigate the gene expression profiles of IPNV-infected zebrafish embryonic cells. We also studied expression of specific genes related to immune response and apoptosis which were not present on the microarray we used by real-time quantitative RT-PCR. We used Pathway StudioM-bM-^@M-^Ys software to analyze the altered genes in cellular pathway for IPNV, TNFM-NM-1 was shown to be crucial to these genes of host response. Our study proved the variation of transcriptome during infection, which shows the activation of important component of host defense, apoptosis and necrosis through TNFM-NM-1 mediate pathway.
Project description:Altered metabolism is an important part of malignant transformation of tumor cells. Oncogenic transformation may reprogram tumor metabolism and render tumor cells addicted to extracellular nutrients. Such nutrient addictions associated with oncogenic mutations may offer therapeutic opportunities; however, it remains difficult to predict these nutrient addictions. Here, we performed a nutrigenetic screen to determine the phenotypes of isogenic pairs of clear-cell renal cancer cells (ccRCC) with or without VHL upon the deprivation of individual amino acids. We identified that cystine deprivation triggered rapid programmed necrosis in VHL-deficient RCC, but not in their VHL-restored counterparts. Similar cystine addiction was also observed in VHL-deficient primary RCC tumors cells. Blockage of cystine uptake significantly delayed xenograft growth of ccRCC. Importantly, cystine deprivation triggered similar metabolic changes regardless of VHL status. Therefore, metabolic differences due to cystine deprivation are not different enough to readily explain the distinct fate of life vs. death in VHL-deficient and restored cell.. Instead, we found that increased levels of TNFα associated with VHL loss in the VHL-deficient RCC force them to rely on intact RIPK1 to inhibit apoptosis. However, this pre-existing elevated TNFα in the VHL-deficient ccRCC renders these cells susceptible to the necrosis signaling triggered by cystine deprivation. In addition, we identified that cystine-deprived necrosis in VHL-deficient RCC depends on reciprocal amplification of the Src-p38-Noxa signaling and TNFα-RIP1/3-MLKL necrosis pathways that culminate in MLKL oligomerization and programmed necrosis. Together, our data reveal that the contextual cystine-addictions in VHL-deficient ccRCC is dependent on activating pre-existing oncogenic pathways to trigger programmed necrosis.
Project description:Many anticancer agents induce apoptosis, mitotic catastrophe or cellular senescence. Here, we report the functional characterization of an experimental inducer of tumor necrosis factor (TNF)-independent necrosis, necrocide-1 (NC1). NC1 (but not its stereoisomer) killed a panel of human cancer cells (but not normal cells) at nanomolar concentrations and with a non-apoptotic, necrotic morphotype, both in vitro and in vivo. NC1-induced killing was not inhibited by caspase blockers, anti-apoptotic BCL2 overexpression or TNFα neutralization, suggesting that NC1 elicits a bona fide necrotic pathway. However, pharmacological or genetic inhibition of necroptosis, pyroptosis and ferroptosis failed to block NC1-mediated cell death. Instead, NC1 elicited reactive oxygen species (ROS) production by mitochondria, and elimination of mitochondrial DNA, quenching of mitochondrial ROS, as well as blockade of mitochondrial permeability transition with cyclosporine A, interfered with NC1-induced cell death. NC1 induced hallmarks of immunogenic cell death incurring calreticulin (CALR) exposure, ATP secretion and high mobility group box 1 (HMGB1) release. Taken together, these data identify a previously uncharacterized signaling cascade leading to an immunogenic variant of mitochondrion-regulated necrosis, supporting the notion that eliciting regulated necrosis may constitute a valid approach for anticancer therapy.
Project description:Cellular senescence is a key cell-fate program that leads to an essentially irreversible proliferative arrest in potentially damaged cells. Cytokine production and signaling play a significant role in senescence. Tumor necrosis factor-alpha (TNFα), an important pro-inflammatory cytokine secreted by some senescent cells, can induce senescence in mouse and human cells. However, downstream signaling pathways and key regulatory genes linking inflammation to senescence are not fully characterized. Using human umbilical vein endothelial cells (HUVECs) as a model, we show TNFα induces permanent growth arrest and increased senescence markers such as p21, p16, and senescence-associated β-galactosidase (SA-β-gal), accompanied by persistent DNA damage and ROS. By gene expression profiling and pathway analysis, we identify the crucial involvement of inflammatory networks, an interferon signature, and persistent activation of the Janus kinase (JAK) /signal transducer and activator of transcription (STAT) pathway in TNFα-mediated senescence. TNFα initiates a STAT-dependent autocrine loop leading to sustained inflammation, DNA damage, and expression of interferon response genes to lock cells into senescence. Further, we show STAT1/3 activation is necessary for cytokine and ROS production during TNFα-induced senescence. However, inhibition of STAT1/3 did not rescue cells from TNFα-mediated senescence. Rather, blockade of STAT activation accelerated senescence, suppressed genes that control the cell cycle, and modulated TNFα-induced senescence. Our findings suggest a positive feedback mechanism via a STAT pathway that sustains cytokine production and reveal a reciprocal regulatory role of JAK/STAT in TNFα-mediated senescence.
Project description:Cellular senescence is a key cell-fate program that leads to an essentially irreversible proliferative arrest in potentially damaged cells. Cytokine production and signaling play a significant role in senescence. Tumor necrosis factor-alpha (TNFα), an important pro-inflammatory cytokine secreted by some senescent cells, can induce senescence in mouse and human cells. However, downstream signaling pathways and key regulatory genes linking inflammation to senescence are not fully characterized. Using human umbilical vein endothelial cells (HUVECs) as a model, we show TNFα induces permanent growth arrest and increased senescence markers such as p21, p16, and senescence-associated β-galactosidase (SA-β-gal), accompanied by persistent DNA damage and ROS. By gene expression profiling and pathway analysis, we identify the crucial involvement of inflammatory networks, an interferon signature, and persistent activation of the Janus kinase (JAK) /signal transducer and activator of transcription (STAT) pathway in TNFα-mediated senescence. TNFα initiates a STAT-dependent autocrine loop leading to sustained inflammation, DNA damage, and expression of interferon response genes to lock cells into senescence. Further, we show STAT1/3 activation is necessary for cytokine and ROS production during TNFα-induced senescence. However, inhibition of STAT1/3 did not rescue cells from TNFα-mediated senescence. Rather, blockade of STAT activation accelerated senescence, suppressed genes that control the cell cycle, and modulated TNFα-induced senescence. Our findings suggest a positive feedback mechanism via a STAT pathway that sustains cytokine production and reveal a reciprocal regulatory role of JAK/STAT in TNFα-mediated senescence.
Project description:Histone deacetylases (HDACs), as important enzymes regulating acetylation, participate in a series of cell physiological process. Here we reported that HDAC3-deficient macrophages had elevated expression of multiple cathepsins and over-expressed cathepsins such as cathepsin B (CTSB) caused remarkable degradation of receptor (TNFRSF)-interacting serine-threonine kinase 1 (RIP1), which resulted in reduced TNFα mediated NF-κB activation and inflammatory response. Consistent with these findings, mice with macrophage specific knockout of HDAC3 were impaired in inflammatory response and susceptible to pseudomonas aeruginosa infection. Thus, our studies uncovered important roles of HDAC3 in the regulation of cathepsin-mediated lysosomal degradation and RIP1-mediated inflammatory response in macrophages as well as in host defense against bacterial infection.
Project description:Histone deacetylases (HDACs), as important enzymes regulating acetylation, participate in a series of cell physiological process. Here we reported that HDAC3-deficient macrophages had elevated expression of multiple cathepsins and over-expressed cathepsins such as cathepsin B (CTSB) caused remarkable degradation of receptor (TNFRSF)-interacting serine-threonine kinase 1 (RIP1), which resulted in reduced TNFα mediated NF-κB activation and inflammatory response. Consistent with these findings, mice with macrophage specific knockout of HDAC3 were impaired in inflammatory response and susceptible to pseudomonas aeruginosa infection. Thus, our studies uncovered important roles of HDAC3 in the regulation of cathepsin-mediated lysosomal degradation and RIP1-mediated inflammatory response in macrophages as well as in host defense against bacterial infection.