Conserved Motifs within Hepatitis C Virus Envelope (E2) RNA and Protein Independently Inhibit T Cell Activation.
T cell receptor (TCR) signaling is required for T-cell activation, proliferation, differentiation, and effector function. Hepatitis C virus (HCV) infection is associated with impaired T-cell function leading to persistent viremia, delayed and inconsistent antibody responses, and mild immune dysfunct...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
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Public Library of Science (PLoS)
2015-09-01
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| Series: | PLoS Pathogens |
| Online Access: | http://europepmc.org/articles/PMC4589396?pdf=render |
| _version_ | 1818163274156343296 |
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| author | Nirjal Bhattarai James H McLinden Jinhua Xiang Thomas M Kaufman Jack T Stapleton |
| author_facet | Nirjal Bhattarai James H McLinden Jinhua Xiang Thomas M Kaufman Jack T Stapleton |
| author_sort | Nirjal Bhattarai |
| collection | DOAJ |
| description | T cell receptor (TCR) signaling is required for T-cell activation, proliferation, differentiation, and effector function. Hepatitis C virus (HCV) infection is associated with impaired T-cell function leading to persistent viremia, delayed and inconsistent antibody responses, and mild immune dysfunction. Although multiple factors appear to contribute to T-cell dysfunction, a role for HCV particles in this process has not been identified. Here, we show that incubation of primary human CD4+ and CD8+ T-cells with HCV RNA-containing serum, HCV-RNA containing extracellular vesicles (EVs), cell culture derived HCV particles (HCVcc) and HCV envelope pseudotyped retrovirus particles (HCVpp) inhibited TCR-mediated signaling. Since HCVpp's contain only E1 and E2, we examined the effect of HCV E2 on TCR signaling pathways. HCV E2 expression recapitulated HCV particle-induced TCR inhibition. A highly conserved, 51 nucleotide (nt) RNA sequence was sufficient to inhibit TCR signaling. Cells expressing the HCV E2 coding RNA contained a short, virus-derived RNA predicted to be a Dicer substrate, which targeted a phosphatase involved in Src-kinase signaling (PTPRE). T-cells and hepatocytes containing HCV E2 RNA had reduced PTPRE protein levels. Mutation of 6 nts abolished the predicted Dicer interactions and restored PTPRE expression and proximal TCR signaling. HCV RNA did not inhibit distal TCR signaling induced by PMA and Ionomycin; however, HCV E2 protein inhibited distal TCR signaling. This inhibition required lymphocyte-specific tyrosine kinase (Lck). Lck phosphorylated HCV E2 at a conserved tyrosine (Y613), and phospho-E2 inhibited nuclear translocation of NFAT. Mutation of Y613 restored distal TCR signaling, even in the context of HCVpps. Thus, HCV particles delivered viral RNA and E2 protein to T-cells, and these inhibited proximal and distal TCR signaling respectively. These effects of HCV particles likely aid in establishing infection and contribute to viral persistence. |
| first_indexed | 2024-12-11T16:46:57Z |
| format | Article |
| id | doaj.art-ff4a4a85745b4fb790b89abd534c09f1 |
| institution | Directory Open Access Journal |
| issn | 1553-7366 1553-7374 |
| language | English |
| last_indexed | 2024-12-11T16:46:57Z |
| publishDate | 2015-09-01 |
| publisher | Public Library of Science (PLoS) |
| record_format | Article |
| series | PLoS Pathogens |
| spelling | doaj.art-ff4a4a85745b4fb790b89abd534c09f12022-12-22T00:58:11ZengPublic Library of Science (PLoS)PLoS Pathogens1553-73661553-73742015-09-01119e100518310.1371/journal.ppat.1005183Conserved Motifs within Hepatitis C Virus Envelope (E2) RNA and Protein Independently Inhibit T Cell Activation.Nirjal BhattaraiJames H McLindenJinhua XiangThomas M KaufmanJack T StapletonT cell receptor (TCR) signaling is required for T-cell activation, proliferation, differentiation, and effector function. Hepatitis C virus (HCV) infection is associated with impaired T-cell function leading to persistent viremia, delayed and inconsistent antibody responses, and mild immune dysfunction. Although multiple factors appear to contribute to T-cell dysfunction, a role for HCV particles in this process has not been identified. Here, we show that incubation of primary human CD4+ and CD8+ T-cells with HCV RNA-containing serum, HCV-RNA containing extracellular vesicles (EVs), cell culture derived HCV particles (HCVcc) and HCV envelope pseudotyped retrovirus particles (HCVpp) inhibited TCR-mediated signaling. Since HCVpp's contain only E1 and E2, we examined the effect of HCV E2 on TCR signaling pathways. HCV E2 expression recapitulated HCV particle-induced TCR inhibition. A highly conserved, 51 nucleotide (nt) RNA sequence was sufficient to inhibit TCR signaling. Cells expressing the HCV E2 coding RNA contained a short, virus-derived RNA predicted to be a Dicer substrate, which targeted a phosphatase involved in Src-kinase signaling (PTPRE). T-cells and hepatocytes containing HCV E2 RNA had reduced PTPRE protein levels. Mutation of 6 nts abolished the predicted Dicer interactions and restored PTPRE expression and proximal TCR signaling. HCV RNA did not inhibit distal TCR signaling induced by PMA and Ionomycin; however, HCV E2 protein inhibited distal TCR signaling. This inhibition required lymphocyte-specific tyrosine kinase (Lck). Lck phosphorylated HCV E2 at a conserved tyrosine (Y613), and phospho-E2 inhibited nuclear translocation of NFAT. Mutation of Y613 restored distal TCR signaling, even in the context of HCVpps. Thus, HCV particles delivered viral RNA and E2 protein to T-cells, and these inhibited proximal and distal TCR signaling respectively. These effects of HCV particles likely aid in establishing infection and contribute to viral persistence.http://europepmc.org/articles/PMC4589396?pdf=render |
| spellingShingle | Nirjal Bhattarai James H McLinden Jinhua Xiang Thomas M Kaufman Jack T Stapleton Conserved Motifs within Hepatitis C Virus Envelope (E2) RNA and Protein Independently Inhibit T Cell Activation. PLoS Pathogens |
| title | Conserved Motifs within Hepatitis C Virus Envelope (E2) RNA and Protein Independently Inhibit T Cell Activation. |
| title_full | Conserved Motifs within Hepatitis C Virus Envelope (E2) RNA and Protein Independently Inhibit T Cell Activation. |
| title_fullStr | Conserved Motifs within Hepatitis C Virus Envelope (E2) RNA and Protein Independently Inhibit T Cell Activation. |
| title_full_unstemmed | Conserved Motifs within Hepatitis C Virus Envelope (E2) RNA and Protein Independently Inhibit T Cell Activation. |
| title_short | Conserved Motifs within Hepatitis C Virus Envelope (E2) RNA and Protein Independently Inhibit T Cell Activation. |
| title_sort | conserved motifs within hepatitis c virus envelope e2 rna and protein independently inhibit t cell activation |
| url | http://europepmc.org/articles/PMC4589396?pdf=render |
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