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The interferon response inhibits HIV particle production by induction of TRIM22.

Barr SD, Smiley JR, Bushman FD - PLoS Pathog. (2008)

Bottom Line: To assess the role of TRIM22 expressed under natural inducing conditions, we compared the effects of interferon in cells depleted for TRIM22 using RNAi and found that HIV particle release was significantly increased in the knockdown, implying that TRIM22 acts as a natural antiviral effector.TRIM22 did not block the release of MLV or EIAV Gag particles.Inhibition was associated with diffuse cytoplasmic staining of HIV Gag rather than accumulation at the plasma membrane, suggesting TRIM22 disrupts proper trafficking.

View Article: PubMed Central - PubMed

Affiliation: Department of Medical Microbiology and Immunology, University of Alberta, Alberta Institute for Viral Immunology, Edmonton, Alberta, Canada. stephen.barr@ualberta.ca

ABSTRACT
Treatment of human cells with Type 1 interferons restricts HIV replication. Here we report that the tripartite motif protein TRIM22 is a key mediator. We used transcriptional profiling to identify cellular genes that were induced by interferon treatment and identified TRIM22 as one of the most strongly up-regulated genes. We confirmed, as in previous studies, that TRIM22 over-expression inhibited HIV replication. To assess the role of TRIM22 expressed under natural inducing conditions, we compared the effects of interferon in cells depleted for TRIM22 using RNAi and found that HIV particle release was significantly increased in the knockdown, implying that TRIM22 acts as a natural antiviral effector. Further studies showed that TRIM22 inhibited budding of virus-like particles containing Gag only, indicating that Gag was the target of TRIM22. TRIM22 did not block the release of MLV or EIAV Gag particles. Inhibition was associated with diffuse cytoplasmic staining of HIV Gag rather than accumulation at the plasma membrane, suggesting TRIM22 disrupts proper trafficking. Mutational analyses of TRIM22 showed that the catalytic amino acids Cys15 and Cys18 of the RING domain are required for TRIM22 antiviral activity. These data disclose a pathway by which Type 1 interferons obstruct HIV replication.

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TRIM22 interacts with Gag.HOS-CD4/CXCR4 cells were co-transfected with pGag-GFP and pFLAG-TRIM22 (or empty vector control pFLAG) and immunoprecipitated with anti-GFP or anti-FLAG. Precipitated Gag and TRIM22 were detected by Western blotting using p24CA or FLAG antibodies.
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ppat-1000007-g007: TRIM22 interacts with Gag.HOS-CD4/CXCR4 cells were co-transfected with pGag-GFP and pFLAG-TRIM22 (or empty vector control pFLAG) and immunoprecipitated with anti-GFP or anti-FLAG. Precipitated Gag and TRIM22 were detected by Western blotting using p24CA or FLAG antibodies.

Mentions: We next asked whether we could detect an interaction between TRIM22 and Pr55Gag. We immunoprecipitated a Gag-GFP fusion protein expressed in the presence of FLAG-tagged TRIM22 with anti-GFP antibodies and then performed a Western blot with anti-Flag antibodies and detected co-precipitation of FLAG-TRIM22 (Figure 7). Reverse immunoprecipitation using anti-FLAG pulled down Gag-GFP only when FLAG-TRIM22 was co-expressed. Treatment of the samples with RNaseA prior to immunoprecipitation did not interfere with the association of TRIM22 with Gag, indicating that an RNA bridge did not mediate the interaction. TRIM22 did not co-immunoprecipitate with either MLV or EIAV Gag (data not shown). Thus TRIM22 binds specifically to HIV Gag.


The interferon response inhibits HIV particle production by induction of TRIM22.

Barr SD, Smiley JR, Bushman FD - PLoS Pathog. (2008)

TRIM22 interacts with Gag.HOS-CD4/CXCR4 cells were co-transfected with pGag-GFP and pFLAG-TRIM22 (or empty vector control pFLAG) and immunoprecipitated with anti-GFP or anti-FLAG. Precipitated Gag and TRIM22 were detected by Western blotting using p24CA or FLAG antibodies.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2279259&req=5

ppat-1000007-g007: TRIM22 interacts with Gag.HOS-CD4/CXCR4 cells were co-transfected with pGag-GFP and pFLAG-TRIM22 (or empty vector control pFLAG) and immunoprecipitated with anti-GFP or anti-FLAG. Precipitated Gag and TRIM22 were detected by Western blotting using p24CA or FLAG antibodies.
Mentions: We next asked whether we could detect an interaction between TRIM22 and Pr55Gag. We immunoprecipitated a Gag-GFP fusion protein expressed in the presence of FLAG-tagged TRIM22 with anti-GFP antibodies and then performed a Western blot with anti-Flag antibodies and detected co-precipitation of FLAG-TRIM22 (Figure 7). Reverse immunoprecipitation using anti-FLAG pulled down Gag-GFP only when FLAG-TRIM22 was co-expressed. Treatment of the samples with RNaseA prior to immunoprecipitation did not interfere with the association of TRIM22 with Gag, indicating that an RNA bridge did not mediate the interaction. TRIM22 did not co-immunoprecipitate with either MLV or EIAV Gag (data not shown). Thus TRIM22 binds specifically to HIV Gag.

Bottom Line: To assess the role of TRIM22 expressed under natural inducing conditions, we compared the effects of interferon in cells depleted for TRIM22 using RNAi and found that HIV particle release was significantly increased in the knockdown, implying that TRIM22 acts as a natural antiviral effector.TRIM22 did not block the release of MLV or EIAV Gag particles.Inhibition was associated with diffuse cytoplasmic staining of HIV Gag rather than accumulation at the plasma membrane, suggesting TRIM22 disrupts proper trafficking.

View Article: PubMed Central - PubMed

Affiliation: Department of Medical Microbiology and Immunology, University of Alberta, Alberta Institute for Viral Immunology, Edmonton, Alberta, Canada. stephen.barr@ualberta.ca

ABSTRACT
Treatment of human cells with Type 1 interferons restricts HIV replication. Here we report that the tripartite motif protein TRIM22 is a key mediator. We used transcriptional profiling to identify cellular genes that were induced by interferon treatment and identified TRIM22 as one of the most strongly up-regulated genes. We confirmed, as in previous studies, that TRIM22 over-expression inhibited HIV replication. To assess the role of TRIM22 expressed under natural inducing conditions, we compared the effects of interferon in cells depleted for TRIM22 using RNAi and found that HIV particle release was significantly increased in the knockdown, implying that TRIM22 acts as a natural antiviral effector. Further studies showed that TRIM22 inhibited budding of virus-like particles containing Gag only, indicating that Gag was the target of TRIM22. TRIM22 did not block the release of MLV or EIAV Gag particles. Inhibition was associated with diffuse cytoplasmic staining of HIV Gag rather than accumulation at the plasma membrane, suggesting TRIM22 disrupts proper trafficking. Mutational analyses of TRIM22 showed that the catalytic amino acids Cys15 and Cys18 of the RING domain are required for TRIM22 antiviral activity. These data disclose a pathway by which Type 1 interferons obstruct HIV replication.

Show MeSH