Receptor interacting protein 1 involved in ultraviolet B induced NIH3T3 cell apoptosis through expression of matrix metalloproteinases and reactive oxygen species production

Background Receptor interacting protein 1 （RIP1）, which plays a key role in apoptosis, cell survival and programmed cell necrosis, is one of the most important proteins in the RIP family. The purpose of this study was to investigate the roles of RIP1 in the apoptosis, the generation of reactive oxygen species （ROS） and the expression of matrix metalloproteinases （MMPs） induced by ultraviolet B （UVB） in fibroblasts. Methods siRNA targeting RIP1 was used to silence RIP1 expression in the NIH3T3 fibroblasts. The mRNA and protein levels of MMP-1 and MMP-3, caspase-3 and -8 activities, and ROS activities were determined by reverse transcriptasequantitative polymerase chain reaction （RT-qPCR）, immunoblotting, caspase activity assay, immunofiuorescence, and flow cytometry. Results The mRNA and protein expressions of MMP-1 and MMP-3 were significantly increased in RIP1 deficient NIH3T3 cells at 24 hours after UVB treatment. At 24 hours after exposure to UVB, RIP1 deficient NIH3T3 cells presented apoptotic morphology, and the apoptosis rate was significantly increased accompanied by pronounced increase in caspase-8 and -3 activities. ROS production was inhibited by UVB at 12 hours in RIP1 deficient NIH3T3 cells. Conclusion RIP1 is involved in NIH3T3 cell damage induced by UVB via participating in the apoptosis, expression of MMPs and ROS production.

Isolation and Characterization of Proteins Interacting with Activin Type Ⅱ Receptors

Regulation of the number of aetivin receptors that are present in the cell membrane plays a key role in the modulation of cellular responses to activin. In order to find the regulators, a novel protein ARIPzip, interacting with activin type II receptors, was searched and identified by using yeast two-hybrid screening. ARIPzip is a splicing variant of ARIP2. This has been discussed previously. ARIPzip can specifically interact with ActR Ⅱ A, and is widely distributed in mouse tissues. Overexpression of ARIPzip can cause the activin-induced transcriptional activities to increase in a dose-dependent manner while the overexpression of ARIV2 can decrease these activities. These data suggest that the C-terminal rezions of ARIP2 and ARIPzip are involved in the regulation of activin signaling.

Necroptosis in inflammatory bowel disease and other intestinal diseases

Guo-Qiang XuFor a long time, it was believed that apoptosis and necrosis were the main pathways for cell death, but a growing body of research has shown that there are other pathways. Among these, necroptosis, a regulatory caspase-independent, programmed cell death pathway, is supposed to be of importance in the pathogenesis of many diseases. The mechanism of regulating, in-ducing and blocking necroptosis is a complex process that involves expression and regulation of a series of molecules including receptor interacting protein kinase 1 （RIPK1）, RIPK3, and mixed lineage kinase like protein. By blocking or downregulating expression of key molecules in the necroptotic pathway, intestinal inflammation can be affected to some extent. In this paper, we introduce the concept of necroptosis, its main pathway, and its impact on the pathogenesis ofinfammatory bowel disease （IBD） and other intestinal diseases, to explore new drug targets for intestinal diseases, including IBD.

Cross electro-nape-acupuncture ameliorates cerebral hemorrhageinduced brain damage by inhibiting necroptosis

BACKGROUND Receptor interacting protein kinase 1(RIPK1)-mediated cell death,including apoptosis and necroptosis,belongs to programmed cell death.It has been reported that RIPK1-mediated necroptosis exists in lesions of cerebral hemorrhage(CH).Electroacupuncture,a treatment derived from traditional Chinese medicine,could improve neurological impairment in patients with brain injury.AIM To investigate the protective role of cross electro-nape acupuncture(CENA)in CH,and clarify the potential mechanism.METHODS CH rat models were established,and CENA was applied to the experimental rats.Neurological functions and encephaledema were then measured.Necrotic cells in the brain of rats with CH were evaluated by propidium iodide staining.Necroptosis was assessed by immunofluorescence.Activation of the necroptosisrelated pathway was detected by western blot.Extraction of brain tissue,cerebrospinal fluid and serum samples was conducted to measure the expression and secretion of inflammatory cytokines by quantitative real-time polymerase chain reaction and enzyme-linked immunosorbent assay.RESULTS The necroptotic marker p-MLKL was detectable in the brains of rats with CH.Next,we found that CENA could ameliorate neurological functions in rat models of CH.Moreover,the upregulation of RIPK1-mediated necroptosis-related molecules in the brains of rats with CH were inhibited by CENA.Further investigation revealed that CENA partially blocked the interaction between RIPK1 and RIPK3.Finally,in vivo assays showed that CENA decreased the expression of the inflammatory cytokines tumor necrosis factor-α,interleukin-6 and interleukin-8 in CH rat models.CONCLUSION These findings revealed that CENA exerts a protective role in CH models by inhibiting RIPK1-mediated necroptosis.

Foot-and-Mouth Disease Virus Inhibits RIP2 Protein Expression to Promote Viral Replication

Receptors interaction protein 2(RIP2)is a specific adaptor molecule in the downstream of NOD2.The role of RIP2 during foot-and-mouth disease virus(FMDV)infection remains unknown.Here,our results showed that RIP2 inhibited FMDV replication and played an important role in the activation of IFN-βand NF-κB signal pathways during FMDV infection.FMDV infection triggered RIP2 transcription,while it reduced the expression of RIP2 protein.Detailed analysis showed that FMDV 2B,2C,3C^(pro),and L^(pro) proteins were responsible for inducing the reduction of RIP2 protein.3C^(pro) and L^(pro) are viral proteinases that can induce the cleavage or reduction of many host proteins and block host protein synthesis.The carboxyl terminal 105-C114 and 135-C144 regions of 2B were essential for reduction of RIP2.Our results also showed that the N terminal 1-61 region of 2C were essential for the reduction of RIP2.The 2C-induced reduction of RIP2 was dependent on inducing the reduction of poly(A)-binding protein 1(PABPC1).The interaction between RIP2 and 2C was observed in the context of viral infection,and the residues 1-61 were required for the interaction.These data clarify novel mechanisms of reduction of RIP2 mediated by FMDV.