Interferon Regulatory Factor-2 (IRF-2) belongs to IRF family, was identified as a mammalian transcription factor involved in Interferon beta (IFNβ) gene regulation. Besides that IRF-2 is involved in immunomodulation,...Interferon Regulatory Factor-2 (IRF-2) belongs to IRF family, was identified as a mammalian transcription factor involved in Interferon beta (IFNβ) gene regulation. Besides that IRF-2 is involved in immunomodulation, hematopoietic differentiation, cell cycle regulation and oncogenesis. We have done molecular sub-cloning and expression of recombinant murine IRF-2 as GST (Glutathione-S-Transferase)- IRF-2 fusion protein in E. coli/XL-1blue cells. Recombinant IRF-2 with GST moiety at N-terminus expressed as GST-IRF-2 (~66 kd) in E. coli along with different low molecular mass degradation products revealed approximately 30, 42, 60 and 62 kd by SDS-PAGE and Western blot, respectively. We further confirm that degradation takes place at C-terminus of the fusion protein not at N-terminus as anti-GST antibody was detecting all bands in the immunoblot. The recombinant IRF-2 was biologically active along with their degradation products in terms of their DNA binding activity as assessed by Electrophoretically Mobility Shift Assay (EMSA). We observed three different molecular mass DNA/protein complexes (1 - 3) with Virus Response Element (VRE) derived from human Interferon IFNβ gene and five different molecular mass complexes (1 - 5) with IRF-E motif (GAAAGT)4 in EMSA gel. GST only expressed from empty vector did not bind to these DNA elements. To confirm that the binding is specific, all complexes were competed out completely when challenged with 100-X fold molar excess of IRF-E oligo under cold competition. It means degradation products along with full-length protein are able to interact with VREβ as well as IRF-E motif. This means degradation products may regulate the target gene (s) activation/repression via interacting with VRE/IRF-E.展开更多
AIM: To investigate whether DNA-dependent activator of interferon-regulatory factors (DAI) inhibits hepatitis B virus (HBV) replication and what the mechanism is. METHODS: After the human hepatoma cell line Huh7 was c...AIM: To investigate whether DNA-dependent activator of interferon-regulatory factors (DAI) inhibits hepatitis B virus (HBV) replication and what the mechanism is. METHODS: After the human hepatoma cell line Huh7 was cotransfected with DAI and HBV expressing plasmid, viral protein (HBV surface antigen and HBV e antigen) secretion was detected by enzyme-linked immunosorbent assay, and HBV RNA was analyzed by real-time polymerase chain reaction and Northern blotting, and viral DNA replicative intermediates were examined by Southern blotting. Interferon regulatory factor 3 (IRF3) phosphorylation and nuclear translocation were analyzed via Western blotting and immunofluorescence staining respectively. Nuclear factor-B (NF- B) activity induced by DAI was detected by immunofluorescence staining of P65 and dual luciferase reporter assay. Transwell co-culture experiment was performed in order to investigate whether the antiviral effects of DAI were dependent on the secreted cytokines. RESULTS: Viral protein secretion was significantly reduced by 57% (P < 0.05), and the level of total HBV RNA was reduced by 67% (P < 0.05). The viral core particle-associated DNA was also dramatically down-regulated in DAI-expressing Huh7 cells. Analysis of involved signaling pathways revealed that activation of NF-B signaling was essential for DAI to elicit antiviral response in Huh7 cells. When the NF-B signaling pathway was blocked by a NF-B signaling suppressor (I B -SR), the anti-HBV activity of DAI was remarkably abrogated. The inhibitory effect of DAI was independent of IRF3 signaling and secreted cytokines. CONCLUSION: This study demonstrates that DAI can inhibit HBV replication and the inhibitory effect is associated with activation of NF-B but independent of IRF3 and secreted cytokines.展开更多
文摘Interferon Regulatory Factor-2 (IRF-2) belongs to IRF family, was identified as a mammalian transcription factor involved in Interferon beta (IFNβ) gene regulation. Besides that IRF-2 is involved in immunomodulation, hematopoietic differentiation, cell cycle regulation and oncogenesis. We have done molecular sub-cloning and expression of recombinant murine IRF-2 as GST (Glutathione-S-Transferase)- IRF-2 fusion protein in E. coli/XL-1blue cells. Recombinant IRF-2 with GST moiety at N-terminus expressed as GST-IRF-2 (~66 kd) in E. coli along with different low molecular mass degradation products revealed approximately 30, 42, 60 and 62 kd by SDS-PAGE and Western blot, respectively. We further confirm that degradation takes place at C-terminus of the fusion protein not at N-terminus as anti-GST antibody was detecting all bands in the immunoblot. The recombinant IRF-2 was biologically active along with their degradation products in terms of their DNA binding activity as assessed by Electrophoretically Mobility Shift Assay (EMSA). We observed three different molecular mass DNA/protein complexes (1 - 3) with Virus Response Element (VRE) derived from human Interferon IFNβ gene and five different molecular mass complexes (1 - 5) with IRF-E motif (GAAAGT)4 in EMSA gel. GST only expressed from empty vector did not bind to these DNA elements. To confirm that the binding is specific, all complexes were competed out completely when challenged with 100-X fold molar excess of IRF-E oligo under cold competition. It means degradation products along with full-length protein are able to interact with VREβ as well as IRF-E motif. This means degradation products may regulate the target gene (s) activation/repression via interacting with VRE/IRF-E.
基金Supported by Grants of The Chinese State Basic Research, No.2009CB522504National Mega Projects for Infectious Diseases, No. 2008ZX10203
文摘AIM: To investigate whether DNA-dependent activator of interferon-regulatory factors (DAI) inhibits hepatitis B virus (HBV) replication and what the mechanism is. METHODS: After the human hepatoma cell line Huh7 was cotransfected with DAI and HBV expressing plasmid, viral protein (HBV surface antigen and HBV e antigen) secretion was detected by enzyme-linked immunosorbent assay, and HBV RNA was analyzed by real-time polymerase chain reaction and Northern blotting, and viral DNA replicative intermediates were examined by Southern blotting. Interferon regulatory factor 3 (IRF3) phosphorylation and nuclear translocation were analyzed via Western blotting and immunofluorescence staining respectively. Nuclear factor-B (NF- B) activity induced by DAI was detected by immunofluorescence staining of P65 and dual luciferase reporter assay. Transwell co-culture experiment was performed in order to investigate whether the antiviral effects of DAI were dependent on the secreted cytokines. RESULTS: Viral protein secretion was significantly reduced by 57% (P < 0.05), and the level of total HBV RNA was reduced by 67% (P < 0.05). The viral core particle-associated DNA was also dramatically down-regulated in DAI-expressing Huh7 cells. Analysis of involved signaling pathways revealed that activation of NF-B signaling was essential for DAI to elicit antiviral response in Huh7 cells. When the NF-B signaling pathway was blocked by a NF-B signaling suppressor (I B -SR), the anti-HBV activity of DAI was remarkably abrogated. The inhibitory effect of DAI was independent of IRF3 signaling and secreted cytokines. CONCLUSION: This study demonstrates that DAI can inhibit HBV replication and the inhibitory effect is associated with activation of NF-B but independent of IRF3 and secreted cytokines.
