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Lily Dara, Zhang-Xu Liu, Neil Kaplowitz
Hepatocyte death, which can be apoptosis or necrosis depending on the context, is a prominent feature of liver disease. The lectin concanavalin A (ConA) activates immune cells, resulting in inflammatory liver injury and hepatocyte necrosis. In this issue of the JCI, Günther et al. demonstrate that the pseudokinase mixed lineage kinase domain-like protein (MLKL) participates in hepatocyte death in ConA injury and that MLKL-mediated death is independent of the receptor-interacting protein kinase RIPK3. RIPK3 was absent in hepatocytes, and MLKL-deficient mice, but not RIPK3-deficient mice, were protected from ConA-induced liver injury...
October 17, 2016: Journal of Clinical Investigation
Piotr T Filipczak, Cynthia L Thomas, Wenshu Chen, Andrew Salzman, Jacob D McDonald, Yong Lin, Steven A Belinsky
Tuberous sclerosis complex (TSC) is a genetic multi-organ disorder characterized by the development of neoplastic lesions in kidney, lung, brain, heart and skin. It is caused by an inactivating mutation in tumor suppressor genes coding the TSC1/TSC2 complex, resulting in hyperactivation of mTOR- and Raf/MEK/MAPK-dependent signaling that stimulates tumor cell proliferation and metastasis. Despite its oncogenic effect, cells with TSC deficiency were more sensitive to oxidative stress and dependent on mitochondrial metabolism, providing a rationale for a new therapeutic approach...
October 18, 2016: Cancer Research
Claudia Günther, Gui-Wei He, Andreas E Kremer, James M Murphy, Emma J Petrie, Kerstin Amann, Peter Vandenabeele, Andreas Linkermann, Christopher Poremba, Ulrike Schleicher, Christin Dewitz, Stefan Krautwald, Markus F Neurath, Christoph Becker, Stefan Wirtz
Although necrosis and necroinflammation are central features of many liver diseases, the role of programmed necrosis in the context of inflammation-dependent hepatocellular death remains to be fully determined. Here, we have demonstrated that the pseudokinase mixed lineage kinase domain-like protein (MLKL), which plays a key role in the execution of receptor-interacting protein (RIP) kinase-dependent necroptosis, is upregulated and activated in human autoimmune hepatitis and in a murine model of inflammation-dependent hepatitis...
October 18, 2016: Journal of Clinical Investigation
C-Y Lin, T-W Chang, W-H Hsieh, M-C Hung, I-H Lin, S-C Lai, Y-J Tzeng
Tanshinone IIA (Tan IIA), a constituent of the traditional medicinal plant Salvia miltiorrhiza BUNGE, has been reported to possess anticancer activity through induction of apoptosis in many cancer cells. Surprisingly, the present study finds that Tan IIA simultaneously causes apoptosis and necroptosis in human hepatocellular carcinoma HepG2 cells. We further find that apoptosis can be converted to necroptosis by pan-caspase inhibitor Z-VAD-fmk, and the two death modes can be blocked by necroptotic inhibitor necrostatin-1...
2016: Cell Death Discovery
J Xin, D You, P Breslin, J Li, J Zhang, W Wei, J Cannova, A Volk, R Gutierrez, Y Xiao, A Ni, G Ng, R Schmidt, Z Xia, J Pan, H Chen, M M Patel, P C Kuo, S Nand, A R Kini, J Zhang, J Chen, J Zhu, J Zhang
Tumor necrosis factor-α (TNF)-induced RIP1/RIP3-mediated necroptosis has been proposed to be an alternative strategy for treating apoptosis-resistant leukemia. However, we found that most acute myeloid leukemia (AML) cells, especially M4 and M5 subtypes, produce TNF and show basal level activation of RIP1/RIP3/MLKL signaling, yet do not undergo necroptosis. TNF, through RIP1/RIP3 signaling, prevents degradation of SOCS1, a key negative regulator of interferon-γ (IFN-γ) signaling. Using both pharmacologic and genetic assays, we show here that inactivation of RIP1/RIP3 resulted in reduction of SOCS1 protein levels and partial differentiation of AML cells...
October 17, 2016: Leukemia: Official Journal of the Leukemia Society of America, Leukemia Research Fund, U.K
Roshan J Thapa, Justin P Ingram, Katherine B Ragan, Shoko Nogusa, David F Boyd, Asiel A Benitez, Haripriya Sridharan, Rachelle Kosoff, Maria Shubina, Vanessa J Landsteiner, Mark Andrake, Peter Vogel, Luis J Sigal, Benjamin R tenOever, Paul G Thomas, Jason W Upton, Siddharth Balachandran
Influenza A virus (IAV) is an RNA virus that is cytotoxic to most cell types in which it replicates. IAV activates the host kinase RIPK3, which induces cell death via parallel pathways of necroptosis, driven by the pseudokinase MLKL, and apoptosis, dependent on the adaptor proteins RIPK1 and FADD. How IAV activates RIPK3 remains unknown. We report that DAI (ZBP1/DLM-1), previously implicated as a cytoplasmic DNA sensor, is essential for RIPK3 activation by IAV. Upon infection, DAI recognizes IAV genomic RNA, associates with RIPK3, and is required for recruitment of MLKL and RIPK1 to RIPK3...
October 8, 2016: Cell Host & Microbe
Simone Wicki, Ursina Gurzeler, W Wei-Lynn Wong, Philipp J Jost, Daniel Bachmann, Thomas Kaufmann
Neutrophils are essential players in the first-line defense against invading bacteria and fungi. Besides its antiapoptotic role, the inhibitor of apoptosis protein (IAP) family member X-linked IAP (XIAP) has been shown to regulate innate immune signaling. Whereas the role of XIAP in innate signaling pathways is derived mostly from work in macrophages and dendritic cells, it is not known if and how XIAP contributes to these pathways in neutrophils. Here we show that in response to bacterial lipopolysaccharides (LPS), mouse neutrophils secreted considerable amounts of tumor necrosis factor-α (TNFα) and interleukin-1β (IL-1β) and, in accordance with earlier reports, XIAP prevented LPS-induced hypersecretion of IL-1β also in neutrophils...
October 13, 2016: Cell Death & Disease
Ryodai Shindo, Soh Yamazaki, Masaki Ohmuraya, Kimi Araki, Hiroyasu Nakano
Cellular FLICE-inhibitory protein (cFLIP) is a catalytically inactive homolog of the initiator caspase, caspase 8 and blocks apoptosis through binding to caspase 8. Human CFLAR gene encodes two proteins, a long form cFLIP (cFLIPL) and a short form cFLIP (cFLIPs) due to an alternative splicing. Recent studies have shown that expression of cFLIPs, but not cFLIPL promotes programmed necrosis (also referred to as necroptosis) in an immortalized human keratinocyte cell line, HaCaT. Here, we found that expression of cFLIPs similarly promoted necroptosis in immortalized fibroblasts...
October 6, 2016: Biochemical and Biophysical Research Communications
Lianshuang Zhang, Jialiu Wei, Lihua Ren, Jin Zhang, Man Yang, Li Jing, Ji Wang, Zhiwei Sun, Xianqing Zhou
Endosulfan, an organochlorine pesticide, was found in human blood, and its possible cardiovascular toxicity has been suggested. However, the mechanism about endothelial cell injuries induced by endosulfan has remained unknown. In the present study, human umbilical vein endothelial cells (HUVECs) were chosen to explore the toxicity mechanism and were treated with 0, 1, 6, and 12 μg/mL(-1) endosulfan for 24 h, respectively. The results showed that exposure to endosulfan could inhibit the cell viability, increase the release of lactate dehydrogenase (LDH), damage the ultrastructure, and lead to apoptosis and necroptosis in HUVECs...
October 5, 2016: Environmental Science and Pollution Research International
Marta B Afonso, Pedro M Rodrigues, André L Simão, Dimitry Ofengeim, Tânia Carvalho, Joana D Amaral, Maria M Gaspar, Helena Cortez-Pinto, Rui E Castro, Junying Yuan, Cecília M P Rodrigues
Cholestasis encompasses liver injury and inflammation. Necroptosis, a necrotic cell death pathway regulated by receptor-interacting protein (RIP) 3, may mediate cell death and inflammation in the liver. We aimed to investigate the role of necroptosis in mediating deleterious processes associated with cholestatic liver disease. Hallmarks of necroptosis were evaluated in liver biopsies of primary biliary cholangitis (PBC) patients and in wild-type and RIP3-deficient (RIP3(-/-)) mice subjected to common bile duct ligation (BDL)...
2016: Cell Death & Disease
Edward A Ratovitski
Dehydroleucodine (DhL), a natural sesquiterpene lactone from Artemisia douglassiana Besser (Argentine) and Gynoxys verrucosa (Ecuador) was shown to induce a cell death in cancer cells through senescence, apoptosis, and DNA damage. Here, we found that the DhL exposure upregulated the total and phosphorylated (p-Y99) levels of TP73 in human glioblastoma U87-MG cells. We further found that TP73 silencing led to a partial rescue of U87-MG cells from the cell death induced by DhL. Upon the DhL exposure numerous gene targets were upregulated and downregulated through a TP73-dependent transcriptional mechanism...
September 23, 2016: Anti-cancer Agents in Medicinal Chemistry
Zhirui Zhang, Hong-Mei Li, Can Zhou, Qixiang Li, Linyan Ma, Zixuan Zhang, Yiming Sun, Lirong Wang, Xudong Zhang, Bing Zhu, Young-Soo Hong, Cheng-Zhu Wu, Hao Liu
BACKGROUND: Hsp90 proteins are important therapeutic targets for many anti-cancer drugs in clinical trials. Geldanamycin (GA) was identified as the first natural inhibitor of Hsp90, increasing evidence suggests that GA was not a good choice for clinical trials. In this study, we investigated two new non-benzoquinone geldanamycin analogs of Hsp90 inhibitors, DHQ3 and 17-demethoxy-reblastatin (17-DR), to explore the molecular mechanisms of their anti-cancer activity in vivo and vitro. METHODS: MTT and colony formation assays were used to measure cell viability...
2016: Journal of Experimental & Clinical Cancer Research: CR
Jo Suda, Lily Dara, Luoluo Yang, Mariam Aghajan, Yong Song, Neil Kaplowitz, Zhang-Xu Liu
Receptor-interacting protein kinase (RIPK)1 has an essential role in the signaling pathways triggered by death receptors through activation of NF-κB and regulation of caspase-dependent apoptosis and RIPK3/mixed lineage kinase domain-like protein (MLKL)-mediated necroptosis. We examined the effect of RIPK1 antisense knockdown on immune-mediated liver injury in C57BL/6 mice caused by α-galactosylceramide (αGalCer), a specific activator for invariant NKT cells. We found that knockdown of RIPK1 markedly exacerbated αGalCer-mediated liver injury and induced lethality...
September 7, 2016: Journal of Immunology: Official Journal of the American Association of Immunologists
Long Pan, Dun-Chen Yao, Yu-Zhong Yu, Sheng-Jie Li, Bing-Jun Chen, Gui-He Hu, Chang Xi, Zi-Hui Wang, Hong-Yan Wang, Jian-Hua Li, Yong-Sheng Tu
Necroptosis is a recently discovered necrotic cell death which is regulated by receptor interacting protein kinase 1 (RIPK1) and RIPK3 under the stimulus of death signal and can be inhibited by necrostatin-1 (Nec-1) specifically. Therefore, the aim was to investigate the role of necroptosis in a rat model of acute respiratory distress syndrome (ARDS) induced by oleic acid (OA) and assess the effect of Nec-1 on lung injury in ARDS. Our results found that RIPK1, RIPK3 and mixed lineage kinase domain-like protein (MLKL) were abundantly expressed in rat lung tissues of OA-induced ARDS...
September 30, 2016: Biochemical and Biophysical Research Communications
Xin Chen, Wan-Ting He, Lichen Hu, Jingxian Li, Yuan Fang, Xin Wang, Xiaozheng Xu, Zhuo Wang, Kai Huang, Jiahuai Han
Necroptosis and pyroptosis are two forms of programmed cell death with a common feature of plasma membrane rupture. Here we studied the morphology and mechanism of pyroptosis in comparison with necroptosis. Different from necroptosis, pyroptosis undergoes membrane blebbing and produces apoptotic body-like cell protrusions (termed pyroptotic bodies) prior to plasma membrane rupture. The rupture in necroptosis is explosion-like, whereas in pyroptosis it leads to flattening of cells. It is known that the execution of necroptosis is mediated by mixed lineage kinase domain-like (MLKL) oligomers in the plasma membrane, whereas gasdermin-D (GSDMD) mediates pyroptosis after its cleavage by caspase-1 or caspase-11...
September 2016: Cell Research
Jaydeep Bhat, Justyna Sosna, Jürgen Fritsch, Elgar Susanne Quabius, Stefan Schütze, Sebastian Zeissig, Ole Ammerpohl, Dieter Adam, Dieter Kabelitz
Previously, the expression of a non-secreted IL-4 variant (IL-4δ13) has been described in association with apoptosis and age-dependent Th2 T-cell polarization. Signaling pathways involved in this process have so far not been studied. Here we report the induction of IL-4δ13 expression in human γδ T-cells upon treatment with a sublethal dose of histone deacetylase (HDACi) inhibitor valproic acid (VPA). Induction of IL-4δ13 was associated with increased cytoplasmic IL-4Rα and decreased IL-4 expression, while mRNA for mature IL-4 was concomitantly down-regulated...
August 20, 2016: Oncotarget
Jiraporn Ousingsawat, Inês Cabrita, Podchanart Wanitchakool, Lalida Sirianant, Stefan Krautwald, Andreas Linkermann, Rainer Schreiber, Karl Kunzelmann
Activated receptor-interacting protein kinase 3 (RIPK3) and mixed lineage kinase domain like (MLKL) are essential components of the necroptotic pathway. Phosphorylated MLKL (pMLKL) is thought to induce membrane leakage, leading to cell swelling and disintegration of the cell membrane. However, the molecular identity of the necroptotic membrane pore remains unclear, and the role of pMLKL for membrane permeabilization is currently disputed. We observed earlier that the phospholipid scramblase and ion channel TMEM16F/anoctamin 6 cause large membrane currents, cell swelling, and cell death when activated by a strong increase in intracellular Ca(2+)...
August 17, 2016: Cellular and Molecular Life Sciences: CMLS
Denuja Karunakaran, Michele Geoffrion, Lihui Wei, Wei Gan, Laura Richards, Prakriti Shangari, Ella M DeKemp, Rachelle A Beanlands, Ljubica Perisic, Lars Maegdefessel, Ulf Hedin, Subash Sad, Liang Guo, Frank D Kolodgie, Renu Virmani, Terrence Ruddy, Katey J Rayner
Atherosclerosis results from maladaptive inflammation driven primarily by macrophages, whose recruitment and proliferation drive plaque progression. In advanced plaques, macrophage death contributes centrally to the formation of plaque necrosis, which underlies the instability that promotes plaque rupture and myocardial infarction. Hence, targeting macrophage cell death pathways may offer promise for the stabilization of vulnerable plaques. Necroptosis is a recently discovered pathway of programmed cell necrosis regulated by RIP3 and MLKL kinases that, in contrast to apoptosis, induces a proinflammatory state...
July 2016: Science Advances
Kipyegon Kitur, Sarah Wachtel, Armand Brown, Matthew Wickersham, Franklin Paulino, Hernán F Peñaloza, Grace Soong, Susan Bueno, Dane Parker, Alice Prince
Staphylococcus aureus triggers inflammation through inflammasome activation and recruitment of neutrophils, responses that are critical for pathogen clearance but are associated with substantial tissue damage. We postulated that necroptosis, cell death mediated by the RIPK1/RIPK3/MLKL pathway, would function to limit pathological inflammation. In models of skin infection or sepsis, Mlkl-/- mice had high bacterial loads, an inability to limit interleukin-1b (IL-1b) production, and excessive inflammation. Similarly, mice treated with RIPK1 or RIPK3 inhibitors had increased bacterial loads in a model of sepsis...
August 23, 2016: Cell Reports
Silvia Alvarez-Diaz, Christopher P Dillon, Najoua Lalaoui, Maria C Tanzer, Diego A Rodriguez, Ann Lin, Marion Lebois, Razq Hakem, Emma C Josefsson, Lorraine A O'Reilly, John Silke, Warren S Alexander, Douglas R Green, Andreas Strasser
The kinases RIPK1 and RIPK3 and the pseudo-kinase MLKL have been identified as key regulators of the necroptotic cell death pathway, although a role for MLKL within the whole animal has not yet been established. Here, we have shown that MLKL deficiency rescued the embryonic lethality caused by loss of Caspase-8 or FADD. Casp8(-/-)Mlkl(-/-) and Fadd(-/-)Mlkl(-/-) mice were viable and fertile but rapidly developed severe lymphadenopathy, systemic autoimmune disease, and thrombocytopenia. These morbidities occurred more rapidly and with increased severity in Casp8(-/-)Mlkl(-/-) and Fadd(-/-)Mlkl(-/-) mice compared to Casp8(-/-)Ripk3(-/-) or Fadd(-/-)Ripk3(-/-) mice, respectively...
September 20, 2016: Immunity
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