1.The mechanism of HBV disruption on RIG-I signaling pathway.
Libo YAN ; Feijun HUANG ; Hong TANG
Journal of Biomedical Engineering 2012;29(5):995-1013
Hepatitis B virus (HBV) infection disrupt the innate immunity response, which may play an important role in the chronic mechanism, while retinoic acid-induced gene I (RIG-I) mediated signaling pathway is one of the most important channel in the innate immunity. HBx and HBV polymerase may disrupt RIG-I mediated signaling pathway. The recent advances about HBV and RIG-I are reviewed in this article.
DEAD Box Protein 58
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DEAD-box RNA Helicases
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metabolism
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Gene Products, pol
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metabolism
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Hepatitis B
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immunology
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Humans
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Immunity, Innate
;
immunology
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Signal Transduction
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Trans-Activators
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metabolism
2.Retinoic acid inducible gene-I, more than a virus sensor.
Protein & Cell 2011;2(5):351-357
Retinoic acid inducible gene-I (RIG-I) is a caspase recruitment domain (CARD) containing protein that acts as an intracellular RNA receptor and senses virus infection. After binding to double stranded RNA (dsRNA) or 5'-triphosphate single stranded RNA (ssRNA), RIG-I transforms into an open conformation, translocates onto mitochondria, and interacts with the downstream adaptor mitochondrial antiviral signaling (MAVS) to induce the production of type I interferon and inflammatory factors via IRF3/7 and NF-κB pathways, respectively. Recently, accumulating evidence suggests that RIG-I could function in non-viral systems and participate in a series of biological events, such as inflammation and inflammation related diseases, cell proliferation, apoptosis and even senescence. Here we review recent advances in antiviral study of RIG-I as well as the functions of RIG-I in other fields.
Antiviral Agents
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chemistry
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DEAD Box Protein 58
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DEAD-box RNA Helicases
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chemistry
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metabolism
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physiology
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Humans
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Inflammation
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metabolism
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Interferon Regulatory Factor-3
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metabolism
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NF-kappa B
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metabolism
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RNA Viruses
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metabolism
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RNA, Double-Stranded
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metabolism
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Signal Transduction
3.RIG-I: a multifunctional protein beyond a pattern recognition receptor.
Xiao-Xiao XU ; Han WAN ; Li NIE ; Tong SHAO ; Li-Xin XIANG ; Jian-Zhong SHAO
Protein & Cell 2018;9(3):246-253
It was widely known that retinoic acid inducible gene I (RIG-I) functions as a cytosolic pattern recognition receptor that initiates innate antiviral immunity by detecting exogenous viral RNAs. However, recent studies showed that RIG-I participates in other various cellular activities by sensing endogenous RNAs under different circumstances. For example, RIG-I facilitates the therapy resistance and expansion of breast cancer cells and promotes T cell-independent B cell activation through interferon signaling activation by recognizing non-coding RNAs and endogenous retroviruses in certain situations. While in hepatocellular carcinoma and acute myeloid leukemia, RIG-I acts as a tumor suppressor through either augmenting STAT1 activation by competitively binding STAT1 against its negative regulator SHP1 or inhibiting AKT-mTOR signaling pathway by directly interacting with Src respectively. These new findings suggest that RIG-I plays more diverse roles in various cellular life activities, such as cell proliferation and differentiation, than previously known. Taken together, the function of RIG-I exceeds far beyond that of a pattern recognition receptor.
Animals
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DEAD Box Protein 58
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genetics
;
metabolism
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Mice
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RNA, Viral
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genetics
;
metabolism
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STAT1 Transcription Factor
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genetics
;
metabolism
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Signal Transduction
;
genetics
;
physiology
4.RIG-I-like receptor-induced IRF3 mediated pathway of apoptosis (RIPA): a new antiviral pathway.
Saurabh CHATTOPADHYAY ; Ganes C SEN
Protein & Cell 2017;8(3):165-168
The innate immune response is the first line of host defense to eliminate viral infection. Pattern recognition receptors in the cytosol, such as RIG-I-like receptors (RLR) and Nod-like receptors (NLR), and membrane bound Toll like receptors (TLR) detect viral infection and initiate transcription of a cohort of antiviral genes, including interferon (IFN) and interferon stimulated genes (ISGs), which ultimately block viral replication. Another mechanism to reduce viral spread is through RIPA, the RLR-induced IRF3-mediated pathway of apoptosis, which causes infected cells to undergo premature death. The transcription factor IRF3 can mediate cellular antiviral responses by both inducing antiviral genes and triggering apoptosis through the activation of RIPA. The mechanism of IRF3 activation in RIPA is distinct from that of transcriptional activation; it requires linear polyubiquitination of specific lysine residues of IRF3. Using RIPA-active, but transcriptionally inactive, IRF3 mutants, it was shown that RIPA can prevent viral replication and pathogenesis in mice.
Animals
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Apoptosis
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DEAD Box Protein 58
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genetics
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immunology
;
metabolism
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Humans
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Immunity, Innate
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Interferon Regulatory Factor-3
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genetics
;
immunology
;
metabolism
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Mice
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Virus Diseases
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genetics
;
immunology
;
metabolism
5.TRIM25 inhibits HBV replication by promoting HBx degradation and the RIG-I-mediated pgRNA recognition.
Hongxiao SONG ; Qingfei XIAO ; Fengchao XU ; Qi WEI ; Fei WANG ; Guangyun TAN
Chinese Medical Journal 2023;136(7):799-806
BACKGROUND:
The hepatitis B virus (HBV) vaccine has been efficiently used for decades. However, hepatocellular carcinoma caused by HBV is still prevalent globally. We previously reported that interferon (IFN)-induced tripartite motif-containing 25 (TRIM25) inhibited HBV replication by increasing the IFN expression, and this study aimed to further clarify the anti-HBV mechanism of TRIM25.
METHODS:
The TRIM25-mediated degradation of hepatitis B virus X (HBx) protein was determined by detecting the expression of HBx in TRIM25-overexpressed or knocked-out HepG2 or HepG2-NTCP cells via Western blotting. Co-immunoprecipitation was performed to confirm the interaction between TRIM25 and HBx, and colocalization of TRIM25 and HBx was identified via immunofluorescence; HBV e-antigen and HBV surface antigen were qualified by using an enzyme-linked immunosorbent assay (ELISA) kit from Kehua Biotech. TRIM25 mRNA, pregenomic RNA (pgRNA), and HBV DNA were detected by quantitative real-time polymerase chain reaction. The retinoic acid-inducible gene I (RIG-I) and pgRNA interaction was verified by RNA-binding protein immunoprecipitation assay.
RESULTS:
We found that TRIM25 promoted HBx degradation, and confirmed that TRIM25 could enhance the K90-site ubiquitination of HBx as well as promote HBx degradation by the proteasome pathway. Interestingly, apart from the Really Interesting New Gene (RING) domain, the SPRY domain of TRIM25 was also indispensable for HBx degradation. In addition, we found that the expression of TRIM25 increased the recognition of HBV pgRNA by interacting with RIG-I, which further increased the IFN production, and SPRY, but not the RING domain is critical in this process.
CONCLUSIONS
The study found that TRIM25 interacted with HBx and promoted HBx-K90-site ubiquitination, which led to HBx degradation. On the other hand, TRIM25 may function as an adaptor, which enhanced the recognition of pgRNA by RIG-I, thereby further promoting IFN production. Our study can contribute to a better understanding of host-virus interaction.
Humans
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Hepatitis B virus
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DEAD Box Protein 58/metabolism*
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RNA
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Liver Neoplasms
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Virus Replication
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Tripartite Motif Proteins/genetics*
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Transcription Factors
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Ubiquitin-Protein Ligases/genetics*
6.Structural and biochemical studies of RIG-I antiviral signaling.
Miao FENG ; Zhanyu DING ; Liang XU ; Liangliang KONG ; Wenjia WANG ; Shi JIAO ; Zhubing SHI ; Mark I GREENE ; Yao CONG ; Zhaocai ZHOU
Protein & Cell 2013;4(2):142-154
Retinoic acid-inducible gene I (RIG-I) is an important pattern recognition receptor that detects viral RNA and triggers the production of type-I interferons through the downstream adaptor MAVS (also called IPS-1, CARDIF, or VISA). A series of structural studies have elaborated some of the mechanisms of dsRNA recognition and activation of RIG-I. Recent studies have proposed that K63-linked ubiquitination of, or unanchored K63-linked polyubiquitin binding to RIG-I positively regulates MAVS-mediated antiviral signaling. Conversely phosphorylation of RIG-I appears to play an inhibitory role in controlling RIG-I antiviral signal transduction. Here we performed a combined structural and biochemical study to further define the regulatory features of RIG-I signaling. ATP and dsRNA binding triggered dimerization of RIG-I with conformational rearrangements of the tandem CARD domains. Full length RIG-I appeared to form a complex with dsRNA in a 2:2 molar ratio. Compared with the previously reported crystal structures of RIG-I in inactive state, our electron microscopic structure of full length RIG-I in complex with blunt-ended dsRNA, for the first time, revealed an exposed active conformation of the CARD domains. Moreover, we found that purified recombinant RIG-I proteins could bind to the CARD domain of MAVS independently of dsRNA, while S8E and T170E phosphorylation-mimicking mutants of RIG-I were defective in binding E3 ligase TRIM25, unanchored K63-linked polyubiquitin, and MAVS regardless of dsRNA. These findings suggested that phosphorylation of RIG inhibited downstream signaling by impairing RIG-I binding with polyubiquitin and its interaction with MAVS.
Adaptor Proteins, Signal Transducing
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metabolism
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Adenosine Triphosphate
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metabolism
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DEAD Box Protein 58
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DEAD-box RNA Helicases
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chemistry
;
genetics
;
metabolism
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Dimerization
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Humans
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Mutagenesis, Site-Directed
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Phosphorylation
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Polyubiquitin
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metabolism
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Protein Binding
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Protein Structure, Tertiary
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RNA, Double-Stranded
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metabolism
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Recombinant Proteins
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biosynthesis
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chemistry
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genetics
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Signal Transduction
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Transcription Factors
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metabolism
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Tripartite Motif Proteins
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Ubiquitin-Protein Ligases
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metabolism
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Ubiquitination
7.Emerging relationship between RNA helicases and autophagy.
Miao-Miao ZHAO ; Ru-Sha WANG ; Yan-Lin ZHOU ; Zheng-Gang YANG
Journal of Zhejiang University. Science. B 2020;21(10):767-778
RNA helicases, the largest family of proteins that participate in RNA metabolism, stabilize the intracellular environment through various processes, such as translation and pre-RNA splicing. These proteins are also involved in some diseases, such as cancers and viral diseases. Autophagy, a self-digestive and cytoprotective trafficking process in which superfluous organelles and cellular garbage are degraded to stabilize the internal environment or maintain basic cellular survival, is associated with human diseases. Interestingly, similar to autophagy, RNA helicases play important roles in maintaining cellular homeostasis and are related to many types of diseases. According to recent studies, RNA helicases are closely related to autophagy, participate in regulating autophagy, or serve as a bridge between autophagy and other cellular activities that widely regulate some pathophysiological processes or the development and progression of diseases. Here, we summarize the most recent studies to understand how RNA helicases function as regulatory proteins and determine their association with autophagy in various diseases.
Animals
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Antiviral Agents/pharmacology*
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Autophagy
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Beclin-1/metabolism*
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Carcinogenesis
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Cell Survival
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DEAD Box Protein 58/metabolism*
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Disease Progression
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Gene Expression Regulation
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Homeostasis
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Humans
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Immune System/physiology*
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Neoplasms/metabolism*
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RNA Helicases/metabolism*
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RNA Splicing
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Receptors, Immunologic/metabolism*
8.Mechanism of inhibiting type I interferon induction by hepatitis B virus X protein.
Protein & Cell 2010;1(12):1106-1117
Hepatitis B virus (HBV) is regarded as a stealth virus, invading and replicating efficiently in human liver undetected by host innate antiviral immunity. Here, we show that type I interferon (IFN) induction but not its downstream signaling is blocked by HBV replication in HepG2.2.15 cells. This effect may be partially due to HBV X protein (HBx), which impairs IFNβ promoter activation by both Sendai virus (SeV) and components implicated in signaling by viral sensors. As a deubiquitinating enzyme (DUB), HBx cleaves Lys63-linked polyubiquitin chains from many proteins except TANK-binding kinase 1 (TBK1). It binds and deconjugates retinoic acid-inducible gene I (RIG I) and TNF receptor-associated factor 3 (TRAF3), causing their dissociation from the downstream adaptor CARDIF or TBK1 kinase. In addition to RIG I and TRAF3, HBx also interacts with CARDIF, TRIF, NEMO, TBK1, inhibitor of kappa light polypeptide gene enhancer in B-cells, kinase epsilon (IKKi) and interferon regulatory factor 3 (IRF3). Our data indicate that multiple points of signaling pathways can be targeted by HBx to negatively regulate production of type I IFN.
Animals
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B-Lymphocytes
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immunology
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metabolism
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Cell Line
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DEAD Box Protein 58
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DEAD-box RNA Helicases
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antagonists & inhibitors
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immunology
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metabolism
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Hep G2 Cells
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Hepatitis B virus
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immunology
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metabolism
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Humans
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I-kappa B Kinase
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antagonists & inhibitors
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immunology
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metabolism
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Immune Evasion
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Immunity, Innate
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Interferon Regulatory Factor-3
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antagonists & inhibitors
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immunology
;
metabolism
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Interferon Type I
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antagonists & inhibitors
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immunology
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metabolism
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Mice
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Molecular Targeted Therapy
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Polyubiquitin
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antagonists & inhibitors
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metabolism
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Protein Binding
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immunology
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Sendai virus
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immunology
;
metabolism
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Signal Transduction
;
immunology
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TNF Receptor-Associated Factor 3
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antagonists & inhibitors
;
immunology
;
metabolism
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Trans-Activators
;
immunology
;
metabolism
9.Andrographolide as an anti-H1N1 drug and the mechanism related to retinoic acid-inducible gene-I-like receptors signaling pathway.
Bin YU ; Cong-qi DAI ; Zhen-you JIANG ; En-qing LI ; Chen CHEN ; Xian-lin WU ; Jia CHEN ; Qian LIU ; Chang-lin ZHAO ; Jin-xiong HE ; Da-hong JU ; Xiao-yin CHEN
Chinese journal of integrative medicine 2014;20(7):540-545
OBJECTIVETo observe the anti-virus effects of andrographolide (AD) on the retinoic acid-inducible gene-I (RIG-I)-like receptors (RLRs) signaling pathway when immunological cells were infected with H1N1.
METHODSLeukomonocyte was obtained from umbilical cord blood by Ficoll density gradient centrifugation, and immunological cells were harvested after cytokines stimulation. Virus infected cell model was established by H1N1 co-cultured with normal human bronchial epithelial cell line (16HBE). The optimal concentration of AD was defined by methyl-thiazolyl-tetrazolium (MTT) assay. After the virus infected cell model was established, AD was added into the medium as a treatment intervention. After 24-h co-culture, cell supernatant was collected for interferon gamma (IFN-γ) and interleukin-4 (IL-4) enzyme-linked immunosorbent assay (ELISA) detection while immunological cells for real-time polymerase chain reaction (RT-PCR).
RESULTSThe optimal concentration of AD for anti-virus effect was 250 μg/mL. IL-4 and IFN-γ in the supernatant and mRNA levels in RLRs pathway increased when cells was infected by virus, RIG-I, IFN-β promoter stimulator-1 (IPS-1), interferon regulatory factor (IRF)-7, IRF-3 and nuclear transcription factor κB (NF-κB) mRNA levels increased significantly (P<0.05). When AD was added into co-culture medium, the levels of IL-4 and IFN-γ were lower than those in the non-interference groups and the mRNA expression levels decreased, RIG-I, IPS-1, IRF-7, IRF-3 and NF-κB decreased significantly in each group with significant statistic differences (P<0.05).
CONCLUSIONSThe RLRs mediated viral recognition provided a potential molecular target for acute viral infections and andrographolide could ameliorate H1N1 virus-induced cell mortality. And the antiviral effects might be related to its inhibition of viral-induced activation of the RLRs signaling pathway.
Adaptor Proteins, Signal Transducing ; genetics ; metabolism ; Antiviral Agents ; pharmacology ; Cells, Cultured ; Coculture Techniques ; DEAD Box Protein 58 ; DEAD-box RNA Helicases ; genetics ; metabolism ; Dendritic Cells ; drug effects ; immunology ; virology ; Diterpenes ; pharmacology ; Fetal Blood ; cytology ; Humans ; Influenza A Virus, H1N1 Subtype ; drug effects ; immunology ; Influenza, Human ; drug therapy ; immunology ; virology ; Interferon-beta ; genetics ; metabolism ; Interferon-gamma ; metabolism ; Interleukin-4 ; metabolism ; Leukocytes, Mononuclear ; drug effects ; immunology ; virology ; Macrophages ; drug effects ; virology ; NF-kappa B ; genetics ; metabolism ; Promoter Regions, Genetic ; drug effects ; immunology ; RNA, Messenger ; metabolism ; Signal Transduction ; drug effects ; genetics ; immunology
10.Molecular cloning, characterization and expression analysis of woodchuck retinoic acid-inducible gene I.
Qi YAN ; Qin LIU ; Meng-Meng LI ; Fang-Hui LI ; Bin ZHU ; Jun-Zhong WANG ; Yin-Ping LU ; Jia LIU ; Jun WU ; Xin ZHENG ; Meng-Ji LU ; Bao-Ju WANG ; Dong-Liang YANG
Journal of Huazhong University of Science and Technology (Medical Sciences) 2016;36(3):335-343
Cytosolic retinoic acid-inducible gene I (RIG-I) is an important innate immune RNA sensor and can induce antiviral cytokines, e.g., interferon-β (IFN-β). Innate immune response to hepatitis B virus (HBV) plays a pivotal role in viral clearance and persistence. However, knowledge of the role that RIG-I plays in HBV infection is limited. The woodchuck is a valuable model for studying HBV infection. To characterize the molecular basis of woodchuck RIG-I (wRIG-I), we analyzed the complete coding sequences (CDSs) of wRIG-I, containing 2778 base pairs that encode 925 amino acids. The deduced wRIG-I protein was 106.847 kD with a theoretical isoelectric point (pI) of 6.07, and contained three important functional structures [caspase activation and recruitment domains (CARDs), DExD/H-box helicases, and a repressor domain (RD)]. In woodchuck fibroblastoma cell line (WH12/6), wRIG-I-targeted small interfering RNA (siRNA) down-regulated RIG-I and its downstrean effector-IFN-β transcripts under RIG-I' ligand, 5'-ppp double stranded RNA (dsRNA) stimulation. We also measured mRNA levels of wRIG-I in different tissues from healthy woodchucks and in the livers from woodchuck hepatitis virus (WHV)-infected woodchucks. The basal expression levels of wRIG-I were abundant in the kidney and liver. Importantly, wRIG-I was significantly up-regulated in acutely infected woodchuck livers, suggesting that RIG-I might be involved in WHV infection. These results may characterize RIG-I in the woodchuck model, providing a strong basis for further study on RIG-I-mediated innate immunity in HBV infection.
Animals
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Cell Line, Tumor
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Cloning, Molecular
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DEAD Box Protein 58
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antagonists & inhibitors
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genetics
;
immunology
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Fibroblasts
;
immunology
;
pathology
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Gene Expression
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Hepatitis B
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genetics
;
immunology
;
pathology
;
veterinary
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Hepatitis B Virus, Woodchuck
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Immunity, Innate
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Interferon-beta
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genetics
;
immunology
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Isoelectric Point
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Kidney
;
immunology
;
pathology
;
virology
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Liver
;
immunology
;
pathology
;
virology
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Marmota
;
genetics
;
immunology
;
virology
;
Open Reading Frames
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Protein Domains
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RNA, Double-Stranded
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RNA, Small Interfering
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genetics
;
metabolism
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Rodent Diseases
;
genetics
;
immunology
;
pathology
;
virology