Project description:Here, we characterize RIPK3-dependent transcriptional responses in cortical neurons following infection with neurotropic flaviviruses. Neurons were infected with either Zika virus (ZIKV) strain MR766 at an MOI of 0.1, West Nile virus (WNV) strain TX 2002-HC at an MOI of 0.001, or a saline mock solution. Neurons were derived from mice lacking RIPK3 expression (Ripk3-/-) or wildtype controls. These studies revealed a number of antiviral genes whose upregulation following viral infection is absent in neurons lacking RIPK3, a subset of which were validated using qRT-PCR.
Project description:Astrocyte activation is a common feature of neurodegenerative diseases. However, the ways in which dying neurons influence the activity of astrocytes is poorly understood. RIPK3 signaling has recently been described as a key regulator of neuroinflammation, but whether this kinase mediates astrocytic responsiveness to neuronal death has not yet been studied. Here, we used the MPTP model of Parkinson’s disease to show that activation of astrocytic RIPK3 drives dopaminergic cell death and axon damage. Transcriptomic profiling revealed that astrocytic RIPK3 promoted gene expression associated with neuroinflammation and movement disorders, and this coincided with significant engagement of DAMP signaling. Using human cell culture systems, we show that factors released from dying neurons signal through RAGE to induce RIPK3-dependent astrocyte activation. These findings highlight a mechanism of neuron-glia crosstalk in which neuronal death perpetuates further neurodegeneration by engaging inflammatory astrocyte activation via RIPK3.
Project description:Ripk3-deficient fibroblasts and lung epithelial cells are resistant to influenza-induced cell deaths. However, Ripk3 is required for protection against influenza infection in vivo. Here, we examine the influenza-regulated gene expressions between wild type and knock out MEFs as well as an involvement of kinase activity if any.
Project description:Ptpn6 is a cytoplasmic phosphatase that functions to prevent autoimmune disease and IL-1R-dependent caspase-1-independent inflammatory disease. Conditional deletion of Ptpn6 in neutrophils (Ptpn6∆PMN) is sufficient to initiate IL-1R-dependent cutaneous inflammatory disease, but the source of IL-1 and the mechanisms behind IL-1 release remain unclear. Here, we investigated the mechanisms controlling IL-1α/β release from neutrophils by inhibiting caspase-8-dependent apoptosis and Ripk1/Ripk3/Mlkl-regulated necroptosis. Loss of Ripk1 accelerated disease onset, whereas combined deletion of caspase-8 and either Ripk3 or Mlkl strongly protected Ptpn6∆PMN mice. Ptpn6∆PMN neutrophils displayed increased p38-dependent Ripk1-independent IL-1 and TNF production, and were prone to cell death. Together, these data emphasize dual functions for Ptpn6 in the negative regulation of p38 MAP kinase activation to control TNF and IL-1α/β transcription, and in maintaining Ripk1 function to prevent caspase-8- and Ripk3/Mlkl-dependent cell death and concomitant IL-1α/β release.
Project description:RIPK4 but not the related kinases RIPK1, RIPK2, and RIPK3 caused similar transcriptional changes to Wnt3a. PA1 cells were transfected by 8ug RIPK1, RIPK2, RIPK3, or RIPK4 for 48h, RNA were extracted and sequenced.
Project description:Pathogen recognition receptors and TNF superfamily members engage Receptor Interacting Serine/threonine Kinase-3 (RIPK3) to activate programmed cell death, including MLKL-mediated necroptosis and caspase-8-dependent apoptosis. However, the post-translational control of RIPK3 signalling is not fully understood. Using mass-spectrometry, we identified a novel ubiquitylation site on murine RIPK3 beyond the RIP homotypic interaction motif (RHIM) on K469. Complementation of RIPK3-deficient cells with a Ripk3K469R mutant demonstrated that the decoration of RIPK3 K469 by ubiquitin limits both RIPK3-mediated caspase-8 activation and apoptotic killing, in addition to RIPK3 autophosphorylation and MLKL-mediated necroptosis. Unexpectedly, the overall ubiquitylation of mutant RIPK3K469R was enhanced, which largely resulted from additional RIPK3 ubiquitylation on K359. Loss of RIPK3 K359 ubiquitylation reduced RIPK3K469R hyper-ubiquitylation and limited the ability of Ripk3K469R/K469R to trigger enhanced killing. Ripk3K469R/K469R mice challenged with Salmonella displayed increased bacterial loads in the spleen and liver, with reduced IFN serum levels. Therefore, RIPK3 K469 ubiquitylation can function to prevent RIPK3 ubiquitylation on alternate lysine residues, which otherwise promote RIPK3 oligomerization and consequent cell death signalling.
Project description:Lethally irradiated recipient C57BL/6 WT, RIPK3-/- and Villin-cre RIPK3fl/fl mice received Balb/c bone marrow and CD4+ T cells. After 17 days, total RNA was extracted from small intestine and deep sequenced to compare the gene expression profiles among WT, RIPK3-/- and Villin-cre RIPK3fl/fl.
Project description:Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a well-known inducer of apoptosis via formation of the primary death-inducing signaling complex (TRAIL-DISC) at the level of membrane death receptors (DR4 and DR5) which recruit successively FADD and caspase-8. TRAIL can also induce necroptosis when caspases are inhibited. Necroptosis is a regulated cell death dependent on the formation of a cytosolic necrosome complex which includes RIPK1, RIPK3 and MLKL proteins. Elucidating the molecular mechanisms involved in TRAIL-induced necroptosis might provide new insights into the TRAIL death signaling pathway. Here, we report the analysis by mass spectrometry of endogenous RIPK3-dependent necrosome complex constituents upon necroptosis induced by TRAIL/z-VAD/Birinapant (TzB) in HT29 cells. Besides characterization of RIPK1, RIPK3, MLKL, FADD, caspase-8, we find TRIM21 as a new constituent of the necrosome complex. Moreover RIPK1, RIPK3, MLKL, P-MLKL, FADD, caspase-8 and TRIM21 are also found associated to the native TRAIL-DISC upon TzB stimulation showing initiation of the necrotic pathway at the level of TRAIL death receptors in HT29 cells. Finally, TRIM21 may positively modulate necroptosis induction by downregulating NF-kB activation.
Project description:This purpose of this experiment was to investigate the transcriptional differences between C57BL6, RIPK3 knock-out mice infected with influenza strain A/CA/04/2009 (H1N1) virus. Overview of Experiment: Groups of 6-8 week-old C57BL6 and RIPK3 knock-out mice were infected with influenza A/CA/04/2009 virus. Infections were done at 10^5 PFU or time-matched mock infected. Time points were 2 and 4 d.p.i. There were 2-3 animals/dose/time point. Lung samples were collected for virus load and transcriptional analysis. Weight loss and animal survival were also monitored.