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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 inhibits accumulation of viral particles in cell supernatants.HOS, U2OS, 143B and HeLa cells were studied (labeled to the left of the gels). Cells were co-transfected with pR9 (encoding full-length HIV-1) and pTRIM22 or the control empty expression vector pcDNA3.1. After 48 hours, Western blots were performed on the supernatants (left panels) and cell pellets (right panels) using p24CA antibodies.
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ppat-1000007-g002: TRIM22 inhibits accumulation of viral particles in cell supernatants.HOS, U2OS, 143B and HeLa cells were studied (labeled to the left of the gels). Cells were co-transfected with pR9 (encoding full-length HIV-1) and pTRIM22 or the control empty expression vector pcDNA3.1. After 48 hours, Western blots were performed on the supernatants (left panels) and cell pellets (right panels) using p24CA antibodies.

Mentions: To test whether TRIM22 interferes with late events in the HIV lifecycle, we co-transfected plasmids encoding TRIM22 and a replication-competent HIV provirus. Forty-eight hours after transfection, Western blots of cell lysates and extracellular supernatants were probed with an antibody against the p24 capsid component of the Gag polyprotein (Figure 2). Co-expression of TRIM22 blocked the release of virions from HOS-CD4/CXCR4 cells, despite the production of substantial amounts of intracellular Gag (Figure 2). Gag also failed to accumulate in the extracellular supernatant in transfected U2OS, 143B and HeLa cells.


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

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

TRIM22 inhibits accumulation of viral particles in cell supernatants.HOS, U2OS, 143B and HeLa cells were studied (labeled to the left of the gels). Cells were co-transfected with pR9 (encoding full-length HIV-1) and pTRIM22 or the control empty expression vector pcDNA3.1. After 48 hours, Western blots were performed on the supernatants (left panels) and cell pellets (right panels) using p24CA antibodies.
© Copyright Policy
Related In: Results  -  Collection

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

ppat-1000007-g002: TRIM22 inhibits accumulation of viral particles in cell supernatants.HOS, U2OS, 143B and HeLa cells were studied (labeled to the left of the gels). Cells were co-transfected with pR9 (encoding full-length HIV-1) and pTRIM22 or the control empty expression vector pcDNA3.1. After 48 hours, Western blots were performed on the supernatants (left panels) and cell pellets (right panels) using p24CA antibodies.
Mentions: To test whether TRIM22 interferes with late events in the HIV lifecycle, we co-transfected plasmids encoding TRIM22 and a replication-competent HIV provirus. Forty-eight hours after transfection, Western blots of cell lysates and extracellular supernatants were probed with an antibody against the p24 capsid component of the Gag polyprotein (Figure 2). Co-expression of TRIM22 blocked the release of virions from HOS-CD4/CXCR4 cells, despite the production of substantial amounts of intracellular Gag (Figure 2). Gag also failed to accumulate in the extracellular supernatant in transfected U2OS, 143B and HeLa cells.

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