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RIG-I is required for the inhibition of measles virus by retinoids.

Soye KJ, Trottier C, Richardson CD, Ward BJ, Miller WH - PLoS ONE (2011)

Bottom Line: Vitamin A can significantly decrease measles-associated morbidity and mortality.Retinoid signaling was also found to act in combination with IFN to induce high levels of RIG-I expression.IRF-1 is known to be regulated by retinoids and MeV, but we found recruitment of IRF-1 to the RIG-I promoter by retinoids alone.

View Article: PubMed Central - PubMed

Affiliation: McGill University Health Center Research Institute, Department of Infectious Diseases, McGill University, Montreal, Quebec, Canada.

ABSTRACT
Vitamin A can significantly decrease measles-associated morbidity and mortality. Vitamin A can inhibit the replication of measles virus (MeV) in vitro through an RARα- and type I interferon (IFN)-dependent mechanism. Retinoid-induced gene I (RIG-I) expression is induced by retinoids, activated by MeV RNA and is important for IFN signaling. We hypothesized that RIG-I is central to retinoid-mediated inhibition of MeV in vitro. We demonstrate that RIG-I expression is increased in cells treated with retinoids and infected with MeV. The central role of RIG-I in the retinoid-anti-MeV effect was demonstrated in the Huh-7/7.5 model; the latter cells having non-functional RIG-I. RAR-dependent retinoid signaling was required for the induction of RIG-I by retinoids and MeV. Retinoid signaling was also found to act in combination with IFN to induce high levels of RIG-I expression. RIG-I promoter activation required both retinoids and MeV, as indicated by markers of active chromatin. IRF-1 is known to be regulated by retinoids and MeV, but we found recruitment of IRF-1 to the RIG-I promoter by retinoids alone. Using luciferase expression constructs, we further demonstrated that the IRF-1 response element of RIG-I was required for RIG-I activation by retinoids or IFN. These results reveal that retinoid treatment and MeV infection induces significant RIG-I. RIG-I is required for the retinoid-MeV antiviral response. The induction is dependent on IFN, retinoids and IRF-1.

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MeV with ATRA induces the soluble factor IFN to elicit the expression of RIG-I.(A) Cells were infected with MeV at an MOI of 0.1 in the presence of 1 µM ATRA or DMSO, and either IFNαβ-receptor blocking antibodies or isotype control. RNA was extracted at 24 h and RIG-I expression was measured by qPCR. Data presented are representative of 2 experiments performed in triplicate (N = 2). (B) Transwell membrane inserts with 0.02 µm pores were used to separate the infected cells from the uninfected, bystander cells in the inner chamber [9]. (C) Cells from transwell-free control wells and the inner chamber bystander cells were harvested after 48 hours and RIG-I mRNA was measured by qPCR. Data presented are representative of three experiments performed in triplicate (N = 3). (D) Supernatants from the control wells and the inner chambers of the transwells were used to treat fresh U937 cells with either IFNαβ-receptor blocking antibody or isotype control antibody. Following 24 hours of incubation, RIG-I expression was assessed by qPCR. Data presented are representative of three experiments performed in triplicate (N = 3). **p<0.01, ***p<0.001.
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pone-0022323-g003: MeV with ATRA induces the soluble factor IFN to elicit the expression of RIG-I.(A) Cells were infected with MeV at an MOI of 0.1 in the presence of 1 µM ATRA or DMSO, and either IFNαβ-receptor blocking antibodies or isotype control. RNA was extracted at 24 h and RIG-I expression was measured by qPCR. Data presented are representative of 2 experiments performed in triplicate (N = 2). (B) Transwell membrane inserts with 0.02 µm pores were used to separate the infected cells from the uninfected, bystander cells in the inner chamber [9]. (C) Cells from transwell-free control wells and the inner chamber bystander cells were harvested after 48 hours and RIG-I mRNA was measured by qPCR. Data presented are representative of three experiments performed in triplicate (N = 3). (D) Supernatants from the control wells and the inner chambers of the transwells were used to treat fresh U937 cells with either IFNαβ-receptor blocking antibody or isotype control antibody. Following 24 hours of incubation, RIG-I expression was assessed by qPCR. Data presented are representative of three experiments performed in triplicate (N = 3). **p<0.01, ***p<0.001.

Mentions: In this study, we have confirmed our previous findings demonstrating the presence of IFNα1 and IFNβ in the supernatant of the ATRA+MeV cells (data not shown). The substantial induction of RIG-I mRNA by ATRA+MeV was found to be abrogated when U937 cultures were treated with IFN α/β receptor blocking antibodies (Figure 3A), in agreement with our previous findings [9]. A transwell system (Figure 3B) was used to determine if up-regulation of RIG-I could be induced in bystander cells, not in contact with the virus, as previously described for IRF-7 [9]. As predicted, there was a robust up-regulation of RIG-I mRNA in bystander cells exposed to ATRA-treated, MeV-infected cells in the transwell system (Figure 3C).


RIG-I is required for the inhibition of measles virus by retinoids.

Soye KJ, Trottier C, Richardson CD, Ward BJ, Miller WH - PLoS ONE (2011)

MeV with ATRA induces the soluble factor IFN to elicit the expression of RIG-I.(A) Cells were infected with MeV at an MOI of 0.1 in the presence of 1 µM ATRA or DMSO, and either IFNαβ-receptor blocking antibodies or isotype control. RNA was extracted at 24 h and RIG-I expression was measured by qPCR. Data presented are representative of 2 experiments performed in triplicate (N = 2). (B) Transwell membrane inserts with 0.02 µm pores were used to separate the infected cells from the uninfected, bystander cells in the inner chamber [9]. (C) Cells from transwell-free control wells and the inner chamber bystander cells were harvested after 48 hours and RIG-I mRNA was measured by qPCR. Data presented are representative of three experiments performed in triplicate (N = 3). (D) Supernatants from the control wells and the inner chambers of the transwells were used to treat fresh U937 cells with either IFNαβ-receptor blocking antibody or isotype control antibody. Following 24 hours of incubation, RIG-I expression was assessed by qPCR. Data presented are representative of three experiments performed in triplicate (N = 3). **p<0.01, ***p<0.001.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3139622&req=5

pone-0022323-g003: MeV with ATRA induces the soluble factor IFN to elicit the expression of RIG-I.(A) Cells were infected with MeV at an MOI of 0.1 in the presence of 1 µM ATRA or DMSO, and either IFNαβ-receptor blocking antibodies or isotype control. RNA was extracted at 24 h and RIG-I expression was measured by qPCR. Data presented are representative of 2 experiments performed in triplicate (N = 2). (B) Transwell membrane inserts with 0.02 µm pores were used to separate the infected cells from the uninfected, bystander cells in the inner chamber [9]. (C) Cells from transwell-free control wells and the inner chamber bystander cells were harvested after 48 hours and RIG-I mRNA was measured by qPCR. Data presented are representative of three experiments performed in triplicate (N = 3). (D) Supernatants from the control wells and the inner chambers of the transwells were used to treat fresh U937 cells with either IFNαβ-receptor blocking antibody or isotype control antibody. Following 24 hours of incubation, RIG-I expression was assessed by qPCR. Data presented are representative of three experiments performed in triplicate (N = 3). **p<0.01, ***p<0.001.
Mentions: In this study, we have confirmed our previous findings demonstrating the presence of IFNα1 and IFNβ in the supernatant of the ATRA+MeV cells (data not shown). The substantial induction of RIG-I mRNA by ATRA+MeV was found to be abrogated when U937 cultures were treated with IFN α/β receptor blocking antibodies (Figure 3A), in agreement with our previous findings [9]. A transwell system (Figure 3B) was used to determine if up-regulation of RIG-I could be induced in bystander cells, not in contact with the virus, as previously described for IRF-7 [9]. As predicted, there was a robust up-regulation of RIG-I mRNA in bystander cells exposed to ATRA-treated, MeV-infected cells in the transwell system (Figure 3C).

Bottom Line: Vitamin A can significantly decrease measles-associated morbidity and mortality.Retinoid signaling was also found to act in combination with IFN to induce high levels of RIG-I expression.IRF-1 is known to be regulated by retinoids and MeV, but we found recruitment of IRF-1 to the RIG-I promoter by retinoids alone.

View Article: PubMed Central - PubMed

Affiliation: McGill University Health Center Research Institute, Department of Infectious Diseases, McGill University, Montreal, Quebec, Canada.

ABSTRACT
Vitamin A can significantly decrease measles-associated morbidity and mortality. Vitamin A can inhibit the replication of measles virus (MeV) in vitro through an RARα- and type I interferon (IFN)-dependent mechanism. Retinoid-induced gene I (RIG-I) expression is induced by retinoids, activated by MeV RNA and is important for IFN signaling. We hypothesized that RIG-I is central to retinoid-mediated inhibition of MeV in vitro. We demonstrate that RIG-I expression is increased in cells treated with retinoids and infected with MeV. The central role of RIG-I in the retinoid-anti-MeV effect was demonstrated in the Huh-7/7.5 model; the latter cells having non-functional RIG-I. RAR-dependent retinoid signaling was required for the induction of RIG-I by retinoids and MeV. Retinoid signaling was also found to act in combination with IFN to induce high levels of RIG-I expression. RIG-I promoter activation required both retinoids and MeV, as indicated by markers of active chromatin. IRF-1 is known to be regulated by retinoids and MeV, but we found recruitment of IRF-1 to the RIG-I promoter by retinoids alone. Using luciferase expression constructs, we further demonstrated that the IRF-1 response element of RIG-I was required for RIG-I activation by retinoids or IFN. These results reveal that retinoid treatment and MeV infection induces significant RIG-I. RIG-I is required for the retinoid-MeV antiviral response. The induction is dependent on IFN, retinoids and IRF-1.

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Related in: MedlinePlus