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:Clustering of the Enteropathogenic (EPEC) Escherichia coli Tir effector, induced by its binding to Intimin, leads to pyroptotic cell death in macrophages. The effect of Tir clustering following EPEC infection of epithelial cells remains unexplored. In this study, we show that EPEC induces pyroptosis in an intestinal epithelial cell (IEC) line, in a Tir-dependent but actin polymerisation-independent manner, which was enhanced by priming with IFNγ. Mechanistically, Tir clustering induces rapid Ca2+ influx, which promotes internalisation of LPS, followed by activation of caspase-4. Chelation of extracellular Ca2+ or knockdown of caspase-4 inhibited cell death upon EPEC infection, whereas ATP-induced extracellular Ca2+ influx had the opposite effect confirming the regulatory role of calcium in the pathway. Additionally, IEC lines with low endogenous expression of caspase-4 were resistant to EPEC-induced cell death. We reveal a novel mechanism of LPS internalisation, following infection with an extracellular pathogen, leading to pyroptosis in IECs.
Project description:Formation of the Death-Inducing Signalling Complex (DISC) initiates the extrinsic apoptotic signalling cascade. Caspase-8 and its regulator cFLIP control death signalling by binding to the receptor via DISC-bound FADD. By elucidating the function of Caspase-10, a close homologue of caspase-8, we unexpectedly found that caspase-10 negatively regulates caspase-8-mediated cell death signalling in the DISC. We demonstrate that caspase-10 inhibits the activation of caspase-8 independent of cFLIP. Furthermore, we show that caspase-8 does not compete with other tandem DED proteins such as cFLIP or caspase-10 in binding via FADD to the receptor as current models suggest. By utilizing caspase-8 knockout cells, we demonstrate that caspase-8 has to be placed upstream of both cFLIP and caspase-10 in the DISC. We further show that DISC formation and/or stability depends on caspase-8 but is independent from its enzymatic activity. Surprisingly, we identified caspase-10 to rewire DISC-signalling to NF-kB activation and cell survival. Our data are consistent with a model in which caspase-10 and cFLIP co-ordinately regulate caspase-8-mediated cell death signalling.
Project description:HDAC1 aberrantly over expressed in HCC and it was considered as an oncogene gene in HCC development. So we want to analyze in greater detail of the genes regulated by HDAC1 using microarray assay. Hep3B RNA was extracted after transfected by HDAC1 shRNA or scrambled shRNA (Mock) for 72hr. For microarray analysis of gene expression unpon depletion of HDAC1, 0.5 μg of total RNA was used to make biotin-labeled cRNA using the Ambion Illumina cRNA amplification and labeling kit according to manufacturers’ instructions (Ambion, Austin, TX)
