ABSTRACT
Retinoic acid-inducible gene I is an important intracellular pattern recognition receptor in antiviral innate immune responses.After recognition of viral RNA, retinoic acid-inducible gene I triggers antiviral signaling pathways which induce the production of interferons and proinflammatory cytokines.Kidney is an important organ of human body.The occurrence of kidney diseases in childhood has a great impact on children's growth and daily life.Recent studies have shown that retinoic acid-inducible gene I can participate in inflammation and immune responses of kidney, and promote the occurrence and progression of kidney diseases.This article reviews the research progress of retinoic acid-inducible gene I in kidney diseases, and discusses its application prospect as a biomarker and therapeutic target of kidney diseases.
ABSTRACT
Intracellular double-stranded RNA (dsRNA) is a chief sign of replication for many viruses. Pattern recognition receptors (PRRs) of the innate immune system detected the dsRNA and initiate the antiviral responses. Retinoic acid-inducible gene I (RIG-I), a member of PRRs, plays an essential regulatory role in dsRNA-induced signalling. In this study, the full-length complementary DNA (cDNA) of duck RIG-I (duRIG-I) was cloned using the reverse transcription-polymerase chain reaction (RT-PCR) and rapid amplification of the cDNA ends (RACE). The cDNA of duRIG-I contained 97-bp 50 UTR, 141-bp 30 -UTR and 2802 bp complete open-reading frame (ORF) encoding 933 amino acids. Multiple sequence alignments showed that duRIG-I shared high similarity with RIG-I from other vertebrates. Quantitative real-time PCR (qRT-PCR) analysis revealed that duRIG-I mRNA was expressed in all tested tissues, with high levels in the liver, heart, spleen, kidney and thymus, while lower in the duodenum. duRIG-I could be induced by treatment with poly(I:C). Further, overexpression of duRIG-I significantly activated the transcription of poly(I:C)-induced IFN-b, IRF7, TRIF, Mx, STAT1 and STAT2 mRNA, and duRIG-I knockdown showed the opposite results. Overall, our results suggested that duRIG-I could be an important receptor for mimicking antiviral state in duck, which warrant further studies to show the possible mechanism.
ABSTRACT
Objective:To investigate the therapeutic efficacy of andrographolide, a plant derived compound, against chikungunya virus (CHIKV) infection.Methods:Using flow cytometry and immunoblotting assay, in vitro viral protein expression was studied in THP-1 cells line. In Balb/c mouse neonates, viral RNA copy number was determined by real time PCR.Results:The results showed reduced CHIKV protein expression on andrographolide treatment in CHIKV-infected human peripheral blood mononuclear cells, Vero cells and THP-1 cell line. In vivo, andrographolide treatment to CHIKV-infected neonates reduced viral RNA copy number. Further, andrographolide also increased cytotoxic T lymphocytes both in vitro and in vivo. Andrographolide also activated host innate immune pathways, viz., protein kinase R, phosphorylated eukaryotic initiation factor 2α , retinoic acid inducible gene-I and interferon regulatory factor 3/7, thereby increasing IFN- α secretion. CHIKV-induced nuclear factor κ light chain enhancer of activated B cells and tumor necrosis factor- α was also reduced on andrographolide treatment.Conclusion:Andrographolide inhibits CHIKV by suppressing viral protein expression and up-regulating host innate immunity and hence could be an effective therapeutic agent against CHIKV infection.
ABSTRACT
Objective: To investigate the therapeutic efficacy of andrographolide, a plant derived compound, against chikungunya virus (CHIKV) infection. Methods: Using flow cytometry and immunoblotting assay, in vitro viral protein expression was studied in THP-1 cells line. In Balb/c mouse neonates, viral RNA copy number was determined by real time PCR. Results: The results showed reduced CHIKV protein expression on andrographolide treatment in CHIKV-infected human peripheral blood mononuclear cells, Vero cells and THP-1 cell line. In vivo, andrographolide treatment to CHIKV-infected neonates reduced viral RNA copy number. Further, andrographolide also increased cytotoxic T lymphocytes both in vitro and in vivo. Andrographolide also activated host innate immune pathways, viz., protein kinase R, phosphorylated eukaryotic initiation factor 2α , retinoic acid inducible gene-I and interferon regulatory factor 3/7, thereby increasing IFN- α secretion. CHIKV-induced nuclear factor κ light chain enhancer of activated B cells and tumor necrosis factor- α was also reduced on andrographolide treatment. Conclusion: Andrographolide inhibits CHIKV by suppressing viral protein expression and up-regulating host innate immunity and hence could be an effective therapeutic agent against CHIKV infection.
ABSTRACT
Exogenous nucleic acids induce an innate immune response in mammalian host cells through activation of the retinoic acid-inducible gene I (RIG-I). We evaluated RIG-I protein for RNA binding and ATPase stimulation with RNA ligands to investigate the correlation with the extent of immune response through RIG-I activation in cells. RIG-I protein favored blunt-ended, double-stranded RNA (dsRNA) ligands over sticky-ended dsRNA. Moreover, the presence of the 5'-triphosphate (5'-ppp) moiety in dsRNA further enhanced binding affinity to RIG-I. Two structural motifs in RNA, blunt ends in dsRNA and 5'-ppp, stimulated the ATP hydrolysis activity of RIG-I. These structural motifs also strongly induced IFN expression as an innate immune response in cells. Therefore, we suggest that IFN induction through RIG-I activation is mainly determined by structural motifs in dsRNA that increase its affinity for RIG-I protein and stimulate ATPase activity in RIG-I.
Subject(s)
Adenosine Triphosphatases , Adenosine Triphosphate , Hydrolysis , Immunity, Innate , Interferon Type I , Ligands , Nucleic Acids , RNA , RNA, Double-StrandedABSTRACT
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.