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Zinc-finger antiviral protein inhibits XMRV infection.

Wang X, Tu F, Zhu Y, Gao G - PLoS ONE (2012)

Bottom Line: ZAP inhibits XMRV replication by preventing the accumulation of viral mRNA in the cytoplasm.Documentation of ZAP inhibiting XMRV helps to broaden the spectrum of ZAP's antiviral activity.Comparison of the target sequences of ZAP in XMRV and MoMLV helps to better understand the features of ZAP-responsive elements.

View Article: PubMed Central - PubMed

Affiliation: Key Laboratory of Infection and Immunity, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China.

ABSTRACT

Background: The zinc-finger antiviral protein (ZAP) is a host factor that specifically inhibits the replication of certain viruses, including Moloney murine leukemia virus (MoMLV), HIV-1, and certain alphaviruses and filoviruses. ZAP binds to specific viral mRNAs and recruits cellular mRNA degradation machinery to degrade the target RNA. The common features of ZAP-responsive RNA sequences remain elusive and thus whether a virus is susceptible to ZAP can only be determined experimentally. Xenotropic murine leukemia virus-related virus (XMRV) is a recently identified γ-retrovirus that was originally thought to be involved in prostate cancer and chronic fatigue syndrome but recently proved to be a laboratory artefact. Nonetheless, XMRV as a new retrovirus has been extensively studied. Since XMRV and MoMLV share only 67.9% sequence identity in the 3'UTRs, which is the target sequence of ZAP in MoMLV, whether XMRV is susceptible to ZAP remains to be determined.

Findings: We constructed an XMRV-luc vector, in which the coding sequences of Gag-Pol and part of Env were replaced with luciferase-coding sequence. Overexpression of ZAP potently inhibited the expression of XMRV-luc in a ZAP expression-level-dependent manner, while downregulation of endogenous ZAP rendered cells more sensitive to infection. Furthermore, ZAP inhibited the spreading of replication-competent XMRV. Consistent with the previously reported mechanisms by which ZAP inhibits viral infection, ZAP significantly inhibited the accumulation of XMRV-luc mRNA in the cytoplasm. The ZAP-responsive element in XMRV mRNA was mapped to the 3'UTR.

Conclusions: ZAP inhibits XMRV replication by preventing the accumulation of viral mRNA in the cytoplasm. Documentation of ZAP inhibiting XMRV helps to broaden the spectrum of ZAP's antiviral activity. Comparison of the target sequences of ZAP in XMRV and MoMLV helps to better understand the features of ZAP-responsive elements.

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Related in: MedlinePlus

Downregulation of RIG-I does not affect ZAP's antiviral activity against XMRV-luc.(A) Control shRNA and shRNAs against RIG-I (Ri446 and Ri583) were stably expressed in 293TRex-hZAP-v2 cells. RIG-I mRNA levels were measured by real-time PCR and normalized to that of GAPDH. Data presented are means ± SE of three parallel experiments. (B) Cells were transfected with pGl3-IFNβ-luc and pRL-TK. At 48 h posttransfection, cells were transfected with poly (I:C). Luciferase activity was assayed 12 h later. (C) Cells were infected with XMRV-luc, mock treated or treated with tetracycline for 48 h to induce ZAP expression, and luciferase activities were measured. Fold inhibition was calculated as the luciferase activity in mock treated cells divided by that in tetracycline treated cells. Data presented are means ± SE of three parallel experiments.
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pone-0039159-g004: Downregulation of RIG-I does not affect ZAP's antiviral activity against XMRV-luc.(A) Control shRNA and shRNAs against RIG-I (Ri446 and Ri583) were stably expressed in 293TRex-hZAP-v2 cells. RIG-I mRNA levels were measured by real-time PCR and normalized to that of GAPDH. Data presented are means ± SE of three parallel experiments. (B) Cells were transfected with pGl3-IFNβ-luc and pRL-TK. At 48 h posttransfection, cells were transfected with poly (I:C). Luciferase activity was assayed 12 h later. (C) Cells were infected with XMRV-luc, mock treated or treated with tetracycline for 48 h to induce ZAP expression, and luciferase activities were measured. Fold inhibition was calculated as the luciferase activity in mock treated cells divided by that in tetracycline treated cells. Data presented are means ± SE of three parallel experiments.

Mentions: ZAPs was recently reported to stimulate type I interferon production through interaction with RIG-I [26]. To explore whether ZAP inhibits XMRV infection by activating the RIG-I pathway, endogenous RIG-I expression was downregulated in 293Trex-hZAP-v2 cells by RNAi (Fig. 4A). Downregulation of RIG-I impaired poly (I:C)-activated IFNβ-luc reporter expression (Fig. 4B), but had little effect on the antiviral activity of ZAP against XMRV (Fig. 4C), implicating that inhibition of XMRV infection by ZAP is independent of the RIG-I pathway.


Zinc-finger antiviral protein inhibits XMRV infection.

Wang X, Tu F, Zhu Y, Gao G - PLoS ONE (2012)

Downregulation of RIG-I does not affect ZAP's antiviral activity against XMRV-luc.(A) Control shRNA and shRNAs against RIG-I (Ri446 and Ri583) were stably expressed in 293TRex-hZAP-v2 cells. RIG-I mRNA levels were measured by real-time PCR and normalized to that of GAPDH. Data presented are means ± SE of three parallel experiments. (B) Cells were transfected with pGl3-IFNβ-luc and pRL-TK. At 48 h posttransfection, cells were transfected with poly (I:C). Luciferase activity was assayed 12 h later. (C) Cells were infected with XMRV-luc, mock treated or treated with tetracycline for 48 h to induce ZAP expression, and luciferase activities were measured. Fold inhibition was calculated as the luciferase activity in mock treated cells divided by that in tetracycline treated cells. Data presented are means ± SE of three parallel experiments.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3376128&req=5

pone-0039159-g004: Downregulation of RIG-I does not affect ZAP's antiviral activity against XMRV-luc.(A) Control shRNA and shRNAs against RIG-I (Ri446 and Ri583) were stably expressed in 293TRex-hZAP-v2 cells. RIG-I mRNA levels were measured by real-time PCR and normalized to that of GAPDH. Data presented are means ± SE of three parallel experiments. (B) Cells were transfected with pGl3-IFNβ-luc and pRL-TK. At 48 h posttransfection, cells were transfected with poly (I:C). Luciferase activity was assayed 12 h later. (C) Cells were infected with XMRV-luc, mock treated or treated with tetracycline for 48 h to induce ZAP expression, and luciferase activities were measured. Fold inhibition was calculated as the luciferase activity in mock treated cells divided by that in tetracycline treated cells. Data presented are means ± SE of three parallel experiments.
Mentions: ZAPs was recently reported to stimulate type I interferon production through interaction with RIG-I [26]. To explore whether ZAP inhibits XMRV infection by activating the RIG-I pathway, endogenous RIG-I expression was downregulated in 293Trex-hZAP-v2 cells by RNAi (Fig. 4A). Downregulation of RIG-I impaired poly (I:C)-activated IFNβ-luc reporter expression (Fig. 4B), but had little effect on the antiviral activity of ZAP against XMRV (Fig. 4C), implicating that inhibition of XMRV infection by ZAP is independent of the RIG-I pathway.

Bottom Line: ZAP inhibits XMRV replication by preventing the accumulation of viral mRNA in the cytoplasm.Documentation of ZAP inhibiting XMRV helps to broaden the spectrum of ZAP's antiviral activity.Comparison of the target sequences of ZAP in XMRV and MoMLV helps to better understand the features of ZAP-responsive elements.

View Article: PubMed Central - PubMed

Affiliation: Key Laboratory of Infection and Immunity, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China.

ABSTRACT

Background: The zinc-finger antiviral protein (ZAP) is a host factor that specifically inhibits the replication of certain viruses, including Moloney murine leukemia virus (MoMLV), HIV-1, and certain alphaviruses and filoviruses. ZAP binds to specific viral mRNAs and recruits cellular mRNA degradation machinery to degrade the target RNA. The common features of ZAP-responsive RNA sequences remain elusive and thus whether a virus is susceptible to ZAP can only be determined experimentally. Xenotropic murine leukemia virus-related virus (XMRV) is a recently identified γ-retrovirus that was originally thought to be involved in prostate cancer and chronic fatigue syndrome but recently proved to be a laboratory artefact. Nonetheless, XMRV as a new retrovirus has been extensively studied. Since XMRV and MoMLV share only 67.9% sequence identity in the 3'UTRs, which is the target sequence of ZAP in MoMLV, whether XMRV is susceptible to ZAP remains to be determined.

Findings: We constructed an XMRV-luc vector, in which the coding sequences of Gag-Pol and part of Env were replaced with luciferase-coding sequence. Overexpression of ZAP potently inhibited the expression of XMRV-luc in a ZAP expression-level-dependent manner, while downregulation of endogenous ZAP rendered cells more sensitive to infection. Furthermore, ZAP inhibited the spreading of replication-competent XMRV. Consistent with the previously reported mechanisms by which ZAP inhibits viral infection, ZAP significantly inhibited the accumulation of XMRV-luc mRNA in the cytoplasm. The ZAP-responsive element in XMRV mRNA was mapped to the 3'UTR.

Conclusions: ZAP inhibits XMRV replication by preventing the accumulation of viral mRNA in the cytoplasm. Documentation of ZAP inhibiting XMRV helps to broaden the spectrum of ZAP's antiviral activity. Comparison of the target sequences of ZAP in XMRV and MoMLV helps to better understand the features of ZAP-responsive elements.

Show MeSH
Related in: MedlinePlus