Receptor-interacting Protein 3 Protein Research Articles

Necroptosis specific inhibitor-1 inhibits necroptosis in rat brain and improves brain injury after cardiac arrest

To explore the effects of necroptosis specific inhibitor-1 (Nec-1) on brain injury in rats after cardiac arrest and its mechanism. A total of 24 Sprague-Dawley (SD) rats were divided into Sham group, model group and Nec-1 group (n = 8 per group) according to random number table method. In the Sham group, only general surgical procedures were underdone without inducing cardiac arrest. In the model group, the rats were subjected to asphyxial cardiac arrest followed by cardiopulmonary resuscitation (CPR) at 6 minutes after cardiac arrest. In the Nec-1 group, Nec-1 of 1 mg/kg was administered after cardiac arrest, and CPR was performed at 6 minutes after cardiac arrest. At 72 hours after CPR, neurological deficit scores (NDS) were assessed, serum S100B levels were measured by enzyme linked immunosorbent assay (ELISA), receptor-interacting protein 3 (RIP3) expression in cerebral cortex and hippocampus was observed under immunofluorescence and positive rate was calculated, and the levels of RIP3 protein expression in brain were analyzed by Western blotting. At 72 hours after CPR, the rats in the model group showed obvious necroptosis and injury in brain. Compared with the Sham group, the NDS scores in the model group were significantly decreased [57.0 (52.7, 60.0) vs. 80.0 (80.0, 80.0), P < 0.05], the serum S100B was significantly increased (ng/L: 44.9±4.5 vs. 18.6±1.5, P < 0.05), the percentages of RIP3 positive cells in cerebral cortex and hippocampus were significantly elevated [cerebral cortex: (31.7±4.8)% vs. (11.6±3.2)%, hippocampus: (28.4±0.8)% vs. (10.9±0.6)%, both P < 0.05], and the levels of RIP3 protein expression in brain were significantly increased [RIP3 protein (RIP3/GAPDH): 0.708 (0.642, 0.722) vs. 0.408 (0.253, 0.504), P < 0.05]. After Nec-1 intervention, necroptosis and injury in brain were obviously improved. Compared with the model group, the NDS scores at 72 hours after CPR in the Nec-1 group were significantly increased [70.5 (68.5, 71.7) vs. 57.0 (52.7, 60.0), P < 0.05), the serum S100B was significantly decreased (ng/L: 31.9±2.7 vs. 44.9±4.5, P < 0.05), the percentages of RIP3 positive cells in cerebral cortex and hippocampus were significantly lowered [cerebral cortex: (23.7±4.1)% vs. (31.7±4.8)%,hippocampus: (20.4±0.4)% vs. (28.4±0.8)%, both P < 0.05], and the levels of RIP3 protein expression in brain were significantly declined [RIP3 protein (RIP3/GAPDH): 0.437 (0.379, 0.507) vs. 0.708 (0.642, 0.722), P < 0.05]. Nec-1 attenuated necroptosis of brain cells by inhibiting the expression of RIP3 protein, so as to reduce brain injury after cardiac arrest in rats.

Pannexin1 Channel Inhibitor (10panx) Protects Against Transient Focal Cerebral Ischemic Injury by Inhibiting RIP3 Expression and Inflammatory Response in Rats

Background: Recent studies have demonstrated that programmed necrosis (necroptosis) is a delayed component of ischemic neuronal injury and our previous study has shown that pannexin 1 channel is involved in cerebral ischemic injury and cellular inflammatory response. Here, we examined whether the pannexin 1 channel inhibitor, 10panx, could reduce focal ischemic brain injury in rats by inhibiting cellular necroptosis and the associated inflammation. Male Sprague–Dawley rats were randomly divided into sham-operated, MCAO (transient middle cerebral artery occlusion) group, and 10panx-treated groups. We investigated the effect of 10panx by assessing infarct volume and neurological deficit. Further, we determined the potential mechanism using immunofluorescent staining, Western blotting, enzyme-linked immunosorbent assay (ELISA) and TUNEL assay. We demonstrated that 10panx reduced infarct volume and alleviated neurological deficit in the MCAO injury model. 10panx ameliorated post-ischemic neuronal death, but it did not reduce the TUNEL positive neurons and expression of cleaved-caspase3. In contrast, expression of necroptosis related protein receptor-interacting protein 3 (RIP3) was significantly decreased. Furthermore, 10panx reduced the release of high mobility group box 1 (HMGB1) from neurons and inhibited microglial activation and secretion of pro-inflammatory factors. Immunent co-labeling of RIP3 with HMGB1 showed that RIP3 protein was closely related with the release of HMGB1 from nucleus to cytoplasm. Our data suggested that 10panx treatment may ameliorate MCAO injury by reducing RIP3-mediated necroptosis, HMGB1 release and associated inflammatory response. RIP3 may play an important role in the release of HMGB1 and inflammation after stroke.

RIP3/MLKL-mediated neuronal necroptosis induced by methamphetamine at 39°C.

Methamphetamine is one of the most prevalent drugs abused in the world. Methamphetamine abusers usually present with hyperpyrexia (39°C), hallucination and other psychiatric symptoms. However, the detailed mechanism underlying its neurotoxic action remains elusive. This study investigated the effects of methamphetamine + 39°C on primary cortical neurons from the cortex of embryonic Sprague-Dawley rats. Primary cortex neurons were exposed to 1 mM methamphetamine + 39°C. Propidium iodide staining and lactate dehydrogenase release detection showed that methamphetamine + 39°C triggered obvious necrosis-like death in cultured primary cortical neurons, which could be partially inhibited by receptor-interacting protein-1 (RIP1) inhibitor Necrostatin-1 partially. Western blot assay results showed that there were increases in the expressions of receptor-interacting protein-3 (RIP3) and mixed lineage kinase domain-like protein (MLKL) in the primary cortical neurons treated with 1 mM methamphetamine + 39°C for 3 hours. After pre-treatment with RIP3 inhibitor GSK'872, propidium iodide staining and lactate dehydrogenase release detection showed that neuronal necrosis rate was significantly decreased; RIP3 and MLKL protein expression significantly decreased. Immunohistochemistry staining results also showed that the expressions of RIP3 and MLKL were up-regulated in brain specimens from humans who had died of methamphetamine abuse. Taken together, the above results suggest that methamphetamine + 39°C can induce RIP3/MLKL regulated necroptosis, thereby resulting in neurotoxicity. The study protocol was approved by the Medical Ethics Committee of the Third Xiangya Hospital of Central South University, China (approval numbers: 2017-S026 and 2017-S033) on March 7, 2017.

Urotensin-#receptor antagonist SB-706375 protected isolated rat heart from ischaemia-reperfusion injury by attenuating myocardial necrosis via RhoA/ROCK/RIP3 signalling pathway.

SB-706375 is a selective receptor antagonist of human urotensin-II (hU-II), which can block the aorta contraction induced by hU-II in rats. The effect of SB-706375 on myocardial ischaemia-reperfusion (I/R) injury is unclear. The major objective of this study was to investigate whether SB-706375 has a protective effect on myocardial I/R injury in rats and explore its possible mechanisms. Isolated hearts of Adult Sprague-Dawley were perfused in a Langendorff apparatus, and haemodynamic parameters, lactate dehydrogenase (LDH), creatine phosphokinase-MB (CK-MB), cardiac troponin I (cTnI), RhoA, and the protein expressions of U-II receptor (UTR), receptor-interacting protein 3 (RIP3), Rho-associated coiled-coil-containing protein kinase 1 (ROCK1) and Rho-associated coiled-coil-containing protein kinase 2 (ROCK2) were assessed. We found that SB-706375 (1 × 10-6 and 1 × 10-5mol/L) significantly inhibited the changes of haemodynamic parameters and reduced LDH and CK-MB activities and also cTnI level in the coronary effluents in the heart subjected to myocardial I/R injury. Further experiments studies showed that SB-706375 obviously prevented myocardial I/R increased RhoA activity and UTR, RIP3, ROCK1, and ROCK2 protein expressions. ROCK inhibition abolished the improving effect of SB-706375 on myocardial I/R-induced haemodynamic change in the isolated perfused rat heart. These findings suggested that SB-706375 provides cardio-protection against I/R injury in isolated rats by blocking UTR-RhoA/ROCK-RIP3 pathway.

Molecular Pathways: The Necrosome-A Target for Cancer Therapy.

Necroptosis is a caspase-8-independent cell death that requires coactivation of receptor-interacting protein 1 (RIP1) and receptor-interacting protein 3 (RIP3) kinases. The necrosome is a complex consisting of RIP1, RIP3, and Fas-associated protein with death domain leading to activation of the pseudokinase mixed lineage kinase like followed by a rapid plasma membrane rupture and inflammatory response through the release of damage-associated molecular patterns and cytokines. The necrosome has been shown to be relevant in multiple tumor types, including pancreatic adenocarcinoma, melanoma, and several hematologic malignancies. Preclinical data suggest that targeting this complex can have differential impact on tumor progression and that the effect of necroptosis on oncogenesis is cell-type and context dependent. The emerging data suggest that targeting the necrosome may lead to immunogenic reprogramming in the tumor microenvironment in multiple tumors and that combining therapies targeting the necrosome with either conventional chemotherapy or immunotherapy may have beneficial effects. Thus, understanding the interplay of necroptotic cell death, transformed cells, and the immune system may enable the development of novel therapeutic approaches. Clin Cancer Res; 23(5); 1132-6. ©2016 AACR.

Cisplatin-induced necroptosis in TNFα dependent and independent pathways

Cisplatin is a chemotherapeutic drug for treatment of many solid tumors. It has been shown to induce apoptosis and/or necrosis in different types of cancer cells. However, the underlying mechanisms remain elusive. In this study, we provide evidences that cisplatin induces necroptosis in receptor-interacting protein 3 (RIP3)-expressing cell lines, but not in cell lines lacking RIP3 protein expression. Deficiency of core components of necroptotic pathway, RIP1, RIP3, or mixed lineage kinase domain-like protein (MLKL) blocked cisplatin-induced cell death in L929 cells. This phenomenon is dependent on RIP1/RIP3/MLKL necrosome formation and translocation to mitochondria-associated membrane (MAM), but only partially via autocrine production of tumor necrosis factor α (TNFα). Moreover, we demonstrate that the mitochondrial permeability transition pore opening (mPTP) opening and reactive oxygen species (ROS) generation is a critical downstream event of the formation of necrosome in cisplatin-induced necroptosis, which is TNFα independent. Deficiency of cyclophilin-D (CypD) partially reduced cisplatin-induced cell death, indicating CypD mediated-mPTP opening plays an important role during cisplatin-induced necroptosis. Both deletion of CypD and TNFα completely blocked cisplatin-induced cell death, suggesting that cisplatin could induce necroptosis through TNFα dependent and independent pathway. These findings provide new insight into the molecular mechanisms underlying cisplatin-induced necroptosis.

Receptor Interacting Protein 3-Mediated Necroptosis Promotes Lipopolysaccharide-Induced Inflammation and Acute Respiratory Distress Syndrome in Mice.

Necrosis amplifies inflammation and plays important roles in acute respiratory distress syndrome (ARDS). Necroptosis is a newly identified programmed necrosis that is mediated by receptor interacting protein 3 (RIP3). However, the potential involvement and impact of necroptosis in lipopolysaccharide (LPS)-induced ARDS remains unknown. We therefore explored the role and mechanism of RIP3-mediated necroptosis in LPS-induced ARDS. Mice were instilled with increasing doses of LPS intratracheally to induce different degrees of ARDS. Lung tissues were harvested for histological and TUNEL staining and western blot for RIP3, p-RIP3, X-linked inhibitor of apoptosis protein (XIAP), mixed lineage kinase domain-like protein (MLKL), total and cleaved caspases-3/8. Then, wild-type and RIP3 knock-out mice were induced ARDS with 30 mg/kg LPS. Pulmonary cellular necrosis was labeled by the propidium Iodide (PI) staining. Levels of TNF-a, Interleukin (IL)-1β, IL-6, IL-1α, IL-10 and HMGB1, tissue myeloperoxidase (MPO) activity, neutrophil counts and total protein concentration were measured. Results showed that in high dose LPS (30mg/kg and 40mg/kg) -induced severe ARDS, RIP3 protein was increased significantly, accompanied by increases of p-RIP3 and MLKL, while in low dose LPS (10mg/kg and 20mg/kg) -induced mild ARDS, apoptosis was remarkably increased. In LPS-induced severe ARDS, RIP3 knock-out alleviated the hypothermia symptom, increased survival rate and ameliorated the lung tissue injury RIP3 depletion also attenuated LPS-induced increase in IL-1α/β, IL-6 and HMGB1 release, decreased tissue MPO activity, and reduced neutrophil influx and total protein concentration in BALF in severe ARDS. Further, RIP3 depletion reduced the necrotic cells in the lung and decreased the expression of MLKL, but had no impact on cleaved caspase-3 in LPS-induced ARDS. It is concluded that RIP3-mediated necroptosis is a major mechanism of enhanced inflammation and lung tissue injury in high dose LPS- induced severe ARDS in mice.

Upregulation of the receptor-interacting protein 3 expression and involvement in neural tissue damage after spinal cord injury in mice.

BackgroundNecroptosis is a newly identified type of programmed cell death that differs from apoptosis. Recent studies have demonstrated that necroptosis is involved in multiple pathologies of various human diseases. Receptor-interacting protein 3 (RIP3) is known to be a critical regulator of necroptosis. This study investigated alterations in the RIP3 expression and the involvement in neural tissue damage after spinal cord injury (SCI) in mice.ResultsImmunohistochemical analysis demonstrated that the RIP3 expression was significantly increased in the lesion site after spinal cord hemisection. The increased expression of RIP3 started at 24 h, peaked at 3 days and lasted for at least 21 days after hemisection. The RIP3 expression was observed in neurons, astrocytes and oligodendrocytes. Western blot analysis also demonstrated the RIP3 protein expression significantly upregulated in the injured spinal cord. RIP3 staining using propidium iodide (PI)-labeled sections showed most of the PI-labeled cells were observed as RIP3-positive. Double staining of TUNEL and RIP3 demonstrated that TUNEL-positive cells exhibiting shrunken or fragmented nuclei, as generally observed in apoptotic cells, rarely expressed RIP3.ConclusionsThe present study first demonstrated that the expression of RIP3 is dramatically upregulated in various neural cells in the injured spinal cord and peaked at 3 days after injury. Additionally, most of the PI-labeled cells expressed RIP3 in response to neural tissue damage after SCI. The present study suggested that the upregulation of the RIP3 expression may play a role as a novel molecular mechanism in secondary neural tissue damage following SCI. However, further study is needed to clarify the specific molecular mechanism underlying the relationship between the RIP3 expression and cell death in the injured spinal cord.

RIP3 overexpression sensitizes human breast cancer cells to parthenolide in vitro via intracellular ROS accumulation.

Receptor-interacting protein 3 (RIP3) is involved in tumor necrosis factor receptor signaling, and results in NF-κB-mediated prosurvival signaling and programmed cell death. The aim of this study was to determine whether overexpression of the RIP3 gene could sensitize human breast cancer cells to parthenolide in vitro. The expression of RIP3 mRNA in human breast cancer cell lines (MCF-7, MDA-MB-231, MDA-MB-435 and T47D) was detected using RT-PCR. Both MDA-MB-231 and MCF-7 cells were transfected with RIP3 expression or blank vectors via lentivirus. Cell viability was measured with MTT assay; intracellular ROS level and cell apoptosis were analyzed using flow cytometry. RIP3 mRNA expression was not detected in the four human breast cancer cell lines tested. However, the transfection induced higher levels of RIP3 protein in MCF-7 and MDA-MB-231 cells. Furthermore, overexpression of RIP3 decreased the IC50 values of parthenolide from 17.6 to 12.6 μmol/L in MCF-7 cells, and from 16.6 to 9.9 μmol/L in MDA-MB-231 cells. Moreover, overexpression of RIP3 significantly increased parthenolide-induced apoptosis and ROS accumulation in MCF-7 and MDA-MB-231 cells. Pretreatment with N-acetyl-cysteine abrogated the increased sensitivity of RIP3-transfected MCF-7 and MDA-MB-231 cells to parthenolide. Overexpression of RIP3 sensitizes MCF-7 and MDA-MB-231 breast cancer cells to parthenolide in vitro via intracellular ROS accumulation.

Necroptosis Is Active in Children With Inflammatory Bowel Disease and Contributes to Heighten Intestinal Inflammation

A new caspase-independent mode of programmed cell death, termed necroptosis, has recently been identified. Altered expression of molecules involved in the necroptosis pathway has been shown to trigger intestinal inflammation. The initiation of necroptosis is principally mediated by the release of receptor interacting protein 3 (RIP3) from suppression by caspase-8. Furthermore, it has been suggested that the mixed lineage kinase domain-like (MLKL) factor is an interacting target of RIP3 in active necroptosis. This study aims at investigating the occurrence of necroptosis in children with inflammatory bowel disease (IBD) and its contribution to human intestinal inflammation. Biopsy samples were collected from the ileum and colon of 33 children with Crohn's disease, 30 with ulcerative colitis, and 20 healthy controls. Ten children with allergic colitis (AC) were used as non-IBD comparators. RIP3, caspase-8, and MLKL protein expression levels were evaluated by western blotting. The adenocarcinoma cell line HT29 was used for in vitro experiments. RIP3 and MLKL increased (P<0.01) in inflamed tissues of IBD and AC patients, whereas caspase-8 was reduced. No variations were observed in uninflamed tissues of patients. The relationship between RIP3 increase, active necroptosis, and intestinal inflammation was confirmed by in vitro analyses. We show for the first time that necroptosis is strongly associated with intestinal inflammation in children with IBD and contributes to strengthen the inflammatory process. We believe that RIP3 and MLKL could represent attractive targets for the management of human IBD.

Advances in Research of RIP3 Protein

Receptor-interacting protein 3 (RIP3) is a member of the Ser/Thr protein kinase family (RIPs). Increasing evidences have revealed that RIPs are essential sensors of cellular stress and key regulators of cell survival, apoptosis and necrosis. Recent studies have demonstrated that RIP3 participates in the signal pathway of cellular necrosis induced by TNF-a. RIP3 functions as an essential regulator of the TNF-a-induced necrosis mainly mediated by reactive oxygen species (ROS) accumulation. These new findings will offer a new target for the advanced tumor therapeutic strategy.

RIP3: a Possible Trigger of Apoptosis or Necrosis*

The receptor-interacting protein 3 (RIP3) is a member of RIP kinase family,which has highly conserved serine/threonine kinase activity.Increasing number of evidences has revealed RIPs to be essential sensors of cellular stress and a key regulator of cell apoptosis,necrosis and survival.Recent studies demonstrating RIP3 as a possible trigger for cellular necrosis in response to TNF-α family of death inducing cytokines may lead to new strategies for developing cancer therapy.This review focuses on the biological characteristics and structure of RIP3 protein,and its cell death control function between apoptotic and necrotic.

Cloning, overexpression, purification, and characterization of receptor-interacting protein 3 truncation inEscherichia coli

To facilitate structural studies of receptor-interacting protein 3 (RIP3), we developed a large-scale expression system of a glutathione-S-transferase (GST) fused with an 82 amino acid RIP3 protein in Escherichia coli. RIP3 truncation was subcloned into the pGEX-4T-1 vector and overexpressed in BL21(DE3)RIL cells. The soluble RIP3 protein was successfully purified to homogeneity using GST tag, an anion-exchange column, and gel filtration chromatography. The purity, identity, and conformation of the RIP3 protein were determined using sodium dodecyl sulfate polyacrylamide gel electrophoresis, Western blotting, matrix-assisted laser desorption ionization mass spectrometry, circular dichroism, and fluorescence spectroscopic studies. RIP3 showed dominance of the alpha-helix structure and temperature-dependent conformational change.