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Persistent prion infection disturbs the function of Oct-1, resulting in the down-regulation of murine interferon regulatory factor-3.

Homma T, Ishibashi D, Nakagaki T, Fuse T, Sano K, Satoh K, Atarashi R, Nishida N - Sci Rep (2014)

Bottom Line: We further investigated promoter activity of 5'- flanking region of murine IRF-3 using a luciferase reporter system and found that the nucleotides -119 to -1 were indispensable for the promoter activity.Intriguingly, Oct-1 protein was significantly reduced in prion-infected cells and mice brains compared with uninfected groups.Taken together, we concluded that prion infection could interfere in the function of Oct-1, resulting in the down-regulation of IRF-3.

View Article: PubMed Central - PubMed

Affiliation: 1] Department of Molecular Microbiology and Immunology, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan [2].

ABSTRACT
As a prompt response against invasion of various viruses, interferon regulatory factor-3 (IRF-3) is initially phosphorylated to become activated and upregulates mainly Type I Interferons (IFN-I) in most cell types. We previously reported that IRF-3-dependent host innate immune responses partially interfere in infection of prions. Here, we found that stable infection of prion suppressed IRF-3 gene-expression. The decreased promoter activity of IRF-3 was significantly restored along with treatment of anti-prion drugs in the prion-infected cells, suggesting that infection of prion directly influence the regulation of IRF-3 transcription. We further investigated promoter activity of 5'- flanking region of murine IRF-3 using a luciferase reporter system and found that the nucleotides -119 to -1 were indispensable for the promoter activity. Within this region, mutations in the Oct-1 binding site significantly reduced the promoter activity and chromatin immunoprecipitation (ChIP) assay revealed that Oct-1 indeed binds to the region. In addition, overexpression of Oct-1 increased the promoter activity of IRF-3. Intriguingly, Oct-1 protein was significantly reduced in prion-infected cells and mice brains compared with uninfected groups. Taken together, we concluded that prion infection could interfere in the function of Oct-1, resulting in the down-regulation of IRF-3.

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Related in: MedlinePlus

Down-regulation of Oct-1 in prion-infected materials.The endogenous Oct-1 expression was examined in N2a58 and ScN2a58 cells (a), and in the uninfected and 22 L prion-infected ddY mice brains (Un-Br and 22L-Br) (b). The amount of Oct-1 was analyzed by immunoblotting. Each β-actin was used as a loading control. Quantification results were shown on bottom of WB panels, respectively. P values were determined by Student's-t test.
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f5: Down-regulation of Oct-1 in prion-infected materials.The endogenous Oct-1 expression was examined in N2a58 and ScN2a58 cells (a), and in the uninfected and 22 L prion-infected ddY mice brains (Un-Br and 22L-Br) (b). The amount of Oct-1 was analyzed by immunoblotting. Each β-actin was used as a loading control. Quantification results were shown on bottom of WB panels, respectively. P values were determined by Student's-t test.

Mentions: We next examined the expression levels of Oct-1 proteins in prion-infected cells. As shown in Fig. 5a, Oct-1 expression in ScN2a58 cells was significantly decreased compared with that in N2a58 cells. Similarly, we also analyzed the expression levels of Oct-1 proteins in prion-infected mice brains. We intracerebrally inoculated 22L or FK-1 prion strains into ddY mice and analyzed the levels of Oct-1 protein in their brains after becoming terminal, respectively. Of note, the levels of Oct-1 protein in the two distinct prion strains-infected mouse brains significantly decreased, suggesting that prion infection might repress endogenous Oct-1 expression (Fig. 5b and Supplementary Fig. S6c). These results demonstrate that reduced IRF-3 promoter activity in prion-infected cells is accompanied by decreased levels of Oct-1.


Persistent prion infection disturbs the function of Oct-1, resulting in the down-regulation of murine interferon regulatory factor-3.

Homma T, Ishibashi D, Nakagaki T, Fuse T, Sano K, Satoh K, Atarashi R, Nishida N - Sci Rep (2014)

Down-regulation of Oct-1 in prion-infected materials.The endogenous Oct-1 expression was examined in N2a58 and ScN2a58 cells (a), and in the uninfected and 22 L prion-infected ddY mice brains (Un-Br and 22L-Br) (b). The amount of Oct-1 was analyzed by immunoblotting. Each β-actin was used as a loading control. Quantification results were shown on bottom of WB panels, respectively. P values were determined by Student's-t test.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4126003&req=5

f5: Down-regulation of Oct-1 in prion-infected materials.The endogenous Oct-1 expression was examined in N2a58 and ScN2a58 cells (a), and in the uninfected and 22 L prion-infected ddY mice brains (Un-Br and 22L-Br) (b). The amount of Oct-1 was analyzed by immunoblotting. Each β-actin was used as a loading control. Quantification results were shown on bottom of WB panels, respectively. P values were determined by Student's-t test.
Mentions: We next examined the expression levels of Oct-1 proteins in prion-infected cells. As shown in Fig. 5a, Oct-1 expression in ScN2a58 cells was significantly decreased compared with that in N2a58 cells. Similarly, we also analyzed the expression levels of Oct-1 proteins in prion-infected mice brains. We intracerebrally inoculated 22L or FK-1 prion strains into ddY mice and analyzed the levels of Oct-1 protein in their brains after becoming terminal, respectively. Of note, the levels of Oct-1 protein in the two distinct prion strains-infected mouse brains significantly decreased, suggesting that prion infection might repress endogenous Oct-1 expression (Fig. 5b and Supplementary Fig. S6c). These results demonstrate that reduced IRF-3 promoter activity in prion-infected cells is accompanied by decreased levels of Oct-1.

Bottom Line: We further investigated promoter activity of 5'- flanking region of murine IRF-3 using a luciferase reporter system and found that the nucleotides -119 to -1 were indispensable for the promoter activity.Intriguingly, Oct-1 protein was significantly reduced in prion-infected cells and mice brains compared with uninfected groups.Taken together, we concluded that prion infection could interfere in the function of Oct-1, resulting in the down-regulation of IRF-3.

View Article: PubMed Central - PubMed

Affiliation: 1] Department of Molecular Microbiology and Immunology, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan [2].

ABSTRACT
As a prompt response against invasion of various viruses, interferon regulatory factor-3 (IRF-3) is initially phosphorylated to become activated and upregulates mainly Type I Interferons (IFN-I) in most cell types. We previously reported that IRF-3-dependent host innate immune responses partially interfere in infection of prions. Here, we found that stable infection of prion suppressed IRF-3 gene-expression. The decreased promoter activity of IRF-3 was significantly restored along with treatment of anti-prion drugs in the prion-infected cells, suggesting that infection of prion directly influence the regulation of IRF-3 transcription. We further investigated promoter activity of 5'- flanking region of murine IRF-3 using a luciferase reporter system and found that the nucleotides -119 to -1 were indispensable for the promoter activity. Within this region, mutations in the Oct-1 binding site significantly reduced the promoter activity and chromatin immunoprecipitation (ChIP) assay revealed that Oct-1 indeed binds to the region. In addition, overexpression of Oct-1 increased the promoter activity of IRF-3. Intriguingly, Oct-1 protein was significantly reduced in prion-infected cells and mice brains compared with uninfected groups. Taken together, we concluded that prion infection could interfere in the function of Oct-1, resulting in the down-regulation of IRF-3.

Show MeSH
Related in: MedlinePlus