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The human antiviral factor TRIM11 is under the regulation of HIV-1 Vpr.

Yuan T, Yao W, Huang F, Sun B, Yang R - PLoS ONE (2014)

Bottom Line: In this study, we demonstrated that TRIM11 mainly suppressed the early steps of HIV-1 transduction, resulting in decreased reverse transcripts.Additionally, we found that TRIM11 could inhibit HIV-1 long terminal repeat (LTR) activity, which may be related to its inhibitory effects on NF-κB.These results suggest that the antiviral factor TRIM11 is indirectly regulated by HIV-1 Vpr through unknown mechanisms and that the concentration of Vpr is essential to these processes.

View Article: PubMed Central - PubMed

Affiliation: Research Group of HIV Molecular Epidemiology and Virology, Center for Emerging Infectious Diseases, The State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, Hubei, The People's Republic of China.

ABSTRACT
TRIM11 has been reported to be able to restrict HIV-1 replication, but the detailed aspects of the interfering mechanisms remain unclear. In this study, we demonstrated that TRIM11 mainly suppressed the early steps of HIV-1 transduction, resulting in decreased reverse transcripts. Additionally, we found that TRIM11 could inhibit HIV-1 long terminal repeat (LTR) activity, which may be related to its inhibitory effects on NF-κB. Deletion mutant experiments showed that the RING domain of TRIM11 was indispensable in inhibiting the early steps of HIV-1 transduction but was dispensable in decreasing NF-κB and LTR activities. Moreover, we found that low levels of Vpr decreased TRIM11 protein levels, while high levels increased them, and these regulations were independent of the VprBP-associated proteasome machinery. These results suggest that the antiviral factor TRIM11 is indirectly regulated by HIV-1 Vpr through unknown mechanisms and that the concentration of Vpr is essential to these processes. Thus, our work confirms TRIM11 as a host cellular factor that interferes with the early steps of HIV-1 replication and provides a connection between viral protein and host antiviral factors.

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Effects of TRIM11 on HIV-1 LTR activity.A, C. HEK293 cells were cotransfected with 200, 500 or 900 ng of plasmids expressing TRIM11, 50 ng of the HIV-1 LTR firefly luciferase reporter and 50 ng of renilla luciferase plasmid. Twenty hours after transfection, cells were left untreated (A) or were treated with 20 ng/ml TNFα(C) for 4 h before luciferase assays were performed. B. HEK293 cells were cotransfected with control siRNA or TRIM11 siRNA, 50 ng of the HIV-1 LTR firefly luciferase reporter and 50 ng of renilla luciferase plasmid. Luciferase assays were performed at 24 h after transfection. D. Fold inductions upon TNFα stimulation were compared in the absence (Myc) or presence of 900 ng of Myc-TRIM11. E. HEK293 cells were cotransfected with 200, 500 or 900 ng of plasmids expressing TRIM11, 50 ng of the NF-κB firefly luciferase reporter and 50 ng of renilla luciferase plasmid. Luciferase assays were performed at 24 h after transfection. F. The wild type or NF-κB mutant LTR reporter constructs along with the 900 ng Myc-TRIM11 plasmids or empty vectors were transfected into HEK293 cells. Luciferase assays were performed at 24 h after transfection. Data are presented as fold-changes compared with TRIM11 restriction rates on the wild type LTR promoter. Error bars represent the standard deviations from three independent replicates of the same experiment. *P<0.05.
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pone-0104269-g003: Effects of TRIM11 on HIV-1 LTR activity.A, C. HEK293 cells were cotransfected with 200, 500 or 900 ng of plasmids expressing TRIM11, 50 ng of the HIV-1 LTR firefly luciferase reporter and 50 ng of renilla luciferase plasmid. Twenty hours after transfection, cells were left untreated (A) or were treated with 20 ng/ml TNFα(C) for 4 h before luciferase assays were performed. B. HEK293 cells were cotransfected with control siRNA or TRIM11 siRNA, 50 ng of the HIV-1 LTR firefly luciferase reporter and 50 ng of renilla luciferase plasmid. Luciferase assays were performed at 24 h after transfection. D. Fold inductions upon TNFα stimulation were compared in the absence (Myc) or presence of 900 ng of Myc-TRIM11. E. HEK293 cells were cotransfected with 200, 500 or 900 ng of plasmids expressing TRIM11, 50 ng of the NF-κB firefly luciferase reporter and 50 ng of renilla luciferase plasmid. Luciferase assays were performed at 24 h after transfection. F. The wild type or NF-κB mutant LTR reporter constructs along with the 900 ng Myc-TRIM11 plasmids or empty vectors were transfected into HEK293 cells. Luciferase assays were performed at 24 h after transfection. Data are presented as fold-changes compared with TRIM11 restriction rates on the wild type LTR promoter. Error bars represent the standard deviations from three independent replicates of the same experiment. *P<0.05.

Mentions: HIV-1 transduction, which was measured in terms of luciferase activity as shown in Figure 1, encompassed not only the early steps but also the LTR-directed transcription. We further investigated whether TRIM11 affected HIV-1 transcription under the LTR promoter by cotransfecting HEK293 cells with increasing amounts of the TRIM11-expressing vector together with a fixed amount of the HIV-1 LTR luciferase reporter construct. The results from the dual luciferase assay showed that TRIM11 significantly decreased HIV-1 LTR activity as its concentration increased (Figure 3A). The effect of ectopically expressed TRIM11 on cell viability was assessed by MTT assay (Figure S1B). Compared with control vector, overexpression of TRIM11 did not show any additional effect on cell viability (Figure S1B). To determine the effects of endogenous TRIM11 on HIV-1 LTR activity, we knocked down TRIM11 by siRNAs. A dual luciferase assay revealed that the knockdown of TRIM11 correspondingly facilitated HIV-1 LTR activity by approximately 1.5-fold (Figure 3B). These results suggest that TRIM11 is able to inhibit basal HIV-1 transcription.


The human antiviral factor TRIM11 is under the regulation of HIV-1 Vpr.

Yuan T, Yao W, Huang F, Sun B, Yang R - PLoS ONE (2014)

Effects of TRIM11 on HIV-1 LTR activity.A, C. HEK293 cells were cotransfected with 200, 500 or 900 ng of plasmids expressing TRIM11, 50 ng of the HIV-1 LTR firefly luciferase reporter and 50 ng of renilla luciferase plasmid. Twenty hours after transfection, cells were left untreated (A) or were treated with 20 ng/ml TNFα(C) for 4 h before luciferase assays were performed. B. HEK293 cells were cotransfected with control siRNA or TRIM11 siRNA, 50 ng of the HIV-1 LTR firefly luciferase reporter and 50 ng of renilla luciferase plasmid. Luciferase assays were performed at 24 h after transfection. D. Fold inductions upon TNFα stimulation were compared in the absence (Myc) or presence of 900 ng of Myc-TRIM11. E. HEK293 cells were cotransfected with 200, 500 or 900 ng of plasmids expressing TRIM11, 50 ng of the NF-κB firefly luciferase reporter and 50 ng of renilla luciferase plasmid. Luciferase assays were performed at 24 h after transfection. F. The wild type or NF-κB mutant LTR reporter constructs along with the 900 ng Myc-TRIM11 plasmids or empty vectors were transfected into HEK293 cells. Luciferase assays were performed at 24 h after transfection. Data are presented as fold-changes compared with TRIM11 restriction rates on the wild type LTR promoter. Error bars represent the standard deviations from three independent replicates of the same experiment. *P<0.05.
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pone-0104269-g003: Effects of TRIM11 on HIV-1 LTR activity.A, C. HEK293 cells were cotransfected with 200, 500 or 900 ng of plasmids expressing TRIM11, 50 ng of the HIV-1 LTR firefly luciferase reporter and 50 ng of renilla luciferase plasmid. Twenty hours after transfection, cells were left untreated (A) or were treated with 20 ng/ml TNFα(C) for 4 h before luciferase assays were performed. B. HEK293 cells were cotransfected with control siRNA or TRIM11 siRNA, 50 ng of the HIV-1 LTR firefly luciferase reporter and 50 ng of renilla luciferase plasmid. Luciferase assays were performed at 24 h after transfection. D. Fold inductions upon TNFα stimulation were compared in the absence (Myc) or presence of 900 ng of Myc-TRIM11. E. HEK293 cells were cotransfected with 200, 500 or 900 ng of plasmids expressing TRIM11, 50 ng of the NF-κB firefly luciferase reporter and 50 ng of renilla luciferase plasmid. Luciferase assays were performed at 24 h after transfection. F. The wild type or NF-κB mutant LTR reporter constructs along with the 900 ng Myc-TRIM11 plasmids or empty vectors were transfected into HEK293 cells. Luciferase assays were performed at 24 h after transfection. Data are presented as fold-changes compared with TRIM11 restriction rates on the wild type LTR promoter. Error bars represent the standard deviations from three independent replicates of the same experiment. *P<0.05.
Mentions: HIV-1 transduction, which was measured in terms of luciferase activity as shown in Figure 1, encompassed not only the early steps but also the LTR-directed transcription. We further investigated whether TRIM11 affected HIV-1 transcription under the LTR promoter by cotransfecting HEK293 cells with increasing amounts of the TRIM11-expressing vector together with a fixed amount of the HIV-1 LTR luciferase reporter construct. The results from the dual luciferase assay showed that TRIM11 significantly decreased HIV-1 LTR activity as its concentration increased (Figure 3A). The effect of ectopically expressed TRIM11 on cell viability was assessed by MTT assay (Figure S1B). Compared with control vector, overexpression of TRIM11 did not show any additional effect on cell viability (Figure S1B). To determine the effects of endogenous TRIM11 on HIV-1 LTR activity, we knocked down TRIM11 by siRNAs. A dual luciferase assay revealed that the knockdown of TRIM11 correspondingly facilitated HIV-1 LTR activity by approximately 1.5-fold (Figure 3B). These results suggest that TRIM11 is able to inhibit basal HIV-1 transcription.

Bottom Line: In this study, we demonstrated that TRIM11 mainly suppressed the early steps of HIV-1 transduction, resulting in decreased reverse transcripts.Additionally, we found that TRIM11 could inhibit HIV-1 long terminal repeat (LTR) activity, which may be related to its inhibitory effects on NF-κB.These results suggest that the antiviral factor TRIM11 is indirectly regulated by HIV-1 Vpr through unknown mechanisms and that the concentration of Vpr is essential to these processes.

View Article: PubMed Central - PubMed

Affiliation: Research Group of HIV Molecular Epidemiology and Virology, Center for Emerging Infectious Diseases, The State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, Hubei, The People's Republic of China.

ABSTRACT
TRIM11 has been reported to be able to restrict HIV-1 replication, but the detailed aspects of the interfering mechanisms remain unclear. In this study, we demonstrated that TRIM11 mainly suppressed the early steps of HIV-1 transduction, resulting in decreased reverse transcripts. Additionally, we found that TRIM11 could inhibit HIV-1 long terminal repeat (LTR) activity, which may be related to its inhibitory effects on NF-κB. Deletion mutant experiments showed that the RING domain of TRIM11 was indispensable in inhibiting the early steps of HIV-1 transduction but was dispensable in decreasing NF-κB and LTR activities. Moreover, we found that low levels of Vpr decreased TRIM11 protein levels, while high levels increased them, and these regulations were independent of the VprBP-associated proteasome machinery. These results suggest that the antiviral factor TRIM11 is indirectly regulated by HIV-1 Vpr through unknown mechanisms and that the concentration of Vpr is essential to these processes. Thus, our work confirms TRIM11 as a host cellular factor that interferes with the early steps of HIV-1 replication and provides a connection between viral protein and host antiviral factors.

Show MeSH
Related in: MedlinePlus