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Activation of NF-kB pathway by virus infection requires Rb expression.

Garcia MA, Gallego P, Campagna M, González-Santamaría J, Martínez G, Marcos-Villar L, Vidal A, Esteban M, Rivas C - PLoS ONE (2009)

Bottom Line: Besides these roles, additional functions in the control of immune response have been suggested.Here we show that virus replication is increased by the absence of Rb, and that Rb is required for the activation of the NF-kB pathway in response to virus infection.These results reveal a novel role for tumor suppressor Rb in viral infection surveillance and further extend the concept of a link between tumor suppressors and antiviral activity.

View Article: PubMed Central - PubMed

Affiliation: Centro Nacional de Biotecnología, CSIC, Campus Universidad Autónoma, Madrid, Spain.

ABSTRACT
The retinoblastoma protein Rb is a tumor suppressor involved in cell cycle control, differentiation, and inhibition of oncogenic transformation. Besides these roles, additional functions in the control of immune response have been suggested. In the present study we investigated the consequences of loss of Rb in viral infection. Here we show that virus replication is increased by the absence of Rb, and that Rb is required for the activation of the NF-kB pathway in response to virus infection. These results reveal a novel role for tumor suppressor Rb in viral infection surveillance and further extend the concept of a link between tumor suppressors and antiviral activity.

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Rb-independent activation of NF-kB in response to TNF-α or poly-IC treatment.A, MEFs derived from WT or Rb−/− mice were treated with 20 ng/ml TNF-α (left panel) or transfected with poly-IC (right panel) and at the indicated times Western-blotting analysis of the indicated proteins was carried out. B, WT or Rb−/− MEFs were transfected with poly-IC and 4 h after transfection total RNA was isolated. After reverse transcription the samples were amplified by TaqMan-based QRT-PCR using taqman probes for TNF-α, IFN-β, and GADPH and analyzed. The expression levels were determined relative to GADPH and represented as fold change in Rb−/− relative to the expression detected in WT cells. C, WT or Rb−/− MEFs were transfected with poly-IC and 8 h after transfection IFN-β production in the cell culture supernatants was measured by ELISA. Error bars indicate mean+/−SE. ND, not detected.
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pone-0006422-g003: Rb-independent activation of NF-kB in response to TNF-α or poly-IC treatment.A, MEFs derived from WT or Rb−/− mice were treated with 20 ng/ml TNF-α (left panel) or transfected with poly-IC (right panel) and at the indicated times Western-blotting analysis of the indicated proteins was carried out. B, WT or Rb−/− MEFs were transfected with poly-IC and 4 h after transfection total RNA was isolated. After reverse transcription the samples were amplified by TaqMan-based QRT-PCR using taqman probes for TNF-α, IFN-β, and GADPH and analyzed. The expression levels were determined relative to GADPH and represented as fold change in Rb−/− relative to the expression detected in WT cells. C, WT or Rb−/− MEFs were transfected with poly-IC and 8 h after transfection IFN-β production in the cell culture supernatants was measured by ELISA. Error bars indicate mean+/−SE. ND, not detected.

Mentions: PKR has also a role in NF-kB activation after poly-IC or TNF-α treatment [26]. In order to determine if Rb is required for NF-kB activation in response to these stimuli, both IkB phosphorylation and degradation after TNF-α or poly-IC treatment in WT or Rb−/− cells was assessed. Both treatments induced phosphorylation and degradation of IkB in both WT and Rb−/− MEFs, indicating that Rb is not required for TNF-α or poly-IC-induced IkB activation or degradation (Figure 3A). Poly-IC treatment also induced the activation of the NF-kB targets, IFN-β and TNF-α, as measured by semiquantitative RT-PCR (Figure 3B) and led to an increased IFN-β production in the supernatant, of both WT and Rb−/− MEFs (Figure 3C). Interestingly, IFN-β mRΝΑ and protein production in response to poly-IC was higher in cells lacking Rb. All together these results indicate that Rb is required for NF-kB activation in response to specific stimulus. In this sense, since RIG-1 has been shown to be essential for VSV recognition [27], [28], and MAD-5 is the principal sensor for transfected poly-IC [28], [29], these results suggest a role of Rb downstream of RIG-1 in the pathway leading to IFN response.


Activation of NF-kB pathway by virus infection requires Rb expression.

Garcia MA, Gallego P, Campagna M, González-Santamaría J, Martínez G, Marcos-Villar L, Vidal A, Esteban M, Rivas C - PLoS ONE (2009)

Rb-independent activation of NF-kB in response to TNF-α or poly-IC treatment.A, MEFs derived from WT or Rb−/− mice were treated with 20 ng/ml TNF-α (left panel) or transfected with poly-IC (right panel) and at the indicated times Western-blotting analysis of the indicated proteins was carried out. B, WT or Rb−/− MEFs were transfected with poly-IC and 4 h after transfection total RNA was isolated. After reverse transcription the samples were amplified by TaqMan-based QRT-PCR using taqman probes for TNF-α, IFN-β, and GADPH and analyzed. The expression levels were determined relative to GADPH and represented as fold change in Rb−/− relative to the expression detected in WT cells. C, WT or Rb−/− MEFs were transfected with poly-IC and 8 h after transfection IFN-β production in the cell culture supernatants was measured by ELISA. Error bars indicate mean+/−SE. ND, not detected.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC2713421&req=5

pone-0006422-g003: Rb-independent activation of NF-kB in response to TNF-α or poly-IC treatment.A, MEFs derived from WT or Rb−/− mice were treated with 20 ng/ml TNF-α (left panel) or transfected with poly-IC (right panel) and at the indicated times Western-blotting analysis of the indicated proteins was carried out. B, WT or Rb−/− MEFs were transfected with poly-IC and 4 h after transfection total RNA was isolated. After reverse transcription the samples were amplified by TaqMan-based QRT-PCR using taqman probes for TNF-α, IFN-β, and GADPH and analyzed. The expression levels were determined relative to GADPH and represented as fold change in Rb−/− relative to the expression detected in WT cells. C, WT or Rb−/− MEFs were transfected with poly-IC and 8 h after transfection IFN-β production in the cell culture supernatants was measured by ELISA. Error bars indicate mean+/−SE. ND, not detected.
Mentions: PKR has also a role in NF-kB activation after poly-IC or TNF-α treatment [26]. In order to determine if Rb is required for NF-kB activation in response to these stimuli, both IkB phosphorylation and degradation after TNF-α or poly-IC treatment in WT or Rb−/− cells was assessed. Both treatments induced phosphorylation and degradation of IkB in both WT and Rb−/− MEFs, indicating that Rb is not required for TNF-α or poly-IC-induced IkB activation or degradation (Figure 3A). Poly-IC treatment also induced the activation of the NF-kB targets, IFN-β and TNF-α, as measured by semiquantitative RT-PCR (Figure 3B) and led to an increased IFN-β production in the supernatant, of both WT and Rb−/− MEFs (Figure 3C). Interestingly, IFN-β mRΝΑ and protein production in response to poly-IC was higher in cells lacking Rb. All together these results indicate that Rb is required for NF-kB activation in response to specific stimulus. In this sense, since RIG-1 has been shown to be essential for VSV recognition [27], [28], and MAD-5 is the principal sensor for transfected poly-IC [28], [29], these results suggest a role of Rb downstream of RIG-1 in the pathway leading to IFN response.

Bottom Line: Besides these roles, additional functions in the control of immune response have been suggested.Here we show that virus replication is increased by the absence of Rb, and that Rb is required for the activation of the NF-kB pathway in response to virus infection.These results reveal a novel role for tumor suppressor Rb in viral infection surveillance and further extend the concept of a link between tumor suppressors and antiviral activity.

View Article: PubMed Central - PubMed

Affiliation: Centro Nacional de Biotecnología, CSIC, Campus Universidad Autónoma, Madrid, Spain.

ABSTRACT
The retinoblastoma protein Rb is a tumor suppressor involved in cell cycle control, differentiation, and inhibition of oncogenic transformation. Besides these roles, additional functions in the control of immune response have been suggested. In the present study we investigated the consequences of loss of Rb in viral infection. Here we show that virus replication is increased by the absence of Rb, and that Rb is required for the activation of the NF-kB pathway in response to virus infection. These results reveal a novel role for tumor suppressor Rb in viral infection surveillance and further extend the concept of a link between tumor suppressors and antiviral activity.

Show MeSH
Related in: MedlinePlus