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Modulation of human endogenous retrovirus (HERV) transcription during persistent and de novo HIV-1 infection.

Vincendeau M, Göttesdorfer I, Schreml JM, Wetie AG, Mayer J, Greenwood AD, Helfer M, Kramer S, Seifarth W, Hadian K, Brack-Werner R, Leib-Mösch C - Retrovirology (2015)

Bottom Line: Analysis of transcripts from individual members of this group revealed up-regulation of predominantly two proviral loci (ERVK-7 and ERVK-15) on chromosomes 1q22 and 7q34 in persistently infected KE37.1 cells, as well as in de novo HIV-1 infected LC5 cells, while only one single HML-2 locus (ERV-K6) on chromosome 7p22.1 was activated in persistently infected LC5 cells.Our results demonstrate that HIV-1 can alter HERV transcription patterns of infected cells and indicate a correlation between activation of HERV elements and the level of HIV-1 production.Moreover, our results suggest that the effects of HIV-1 on HERV activity may be far more extensive and complex than anticipated from initial studies with clinical material.

View Article: PubMed Central - PubMed

Affiliation: Institute of Virology, Helmholtz Zentrum München, German Research Center for Environmental Health, Neuherberg, Germany. michelle.vincendeau@helmholtz-muenchen.de.

ABSTRACT

Background: The human genome contains multiple LTR elements including human endogenous retroviruses (HERVs) that together account for approximately 8-9% of the genomic DNA. At least 40 different HERV groups have been assigned to three major HERV classes on the basis of their homologies to exogenous retroviruses. Although most HERVs are silenced by a variety of genetic and epigenetic mechanisms, they may be reactivated by environmental stimuli such as exogenous viruses and thus may contribute to pathogenic conditions. The objective of this study was to perform an in-depth analysis of the influence of HIV-1 infection on HERV activity in different cell types.

Results: A retrovirus-specific microarray that covers major HERV groups from all three classes was used to analyze HERV transcription patterns in three persistently HIV-1 infected cell lines of different cellular origins and in their uninfected counterparts. All three persistently infected cell lines showed increased transcription of multiple class I and II HERV groups. Up-regulated transcription of five HERV taxa (HERV-E, HERV-T, HERV-K (HML-10) and two ERV9 subgroups) was confirmed by quantitative reverse transcriptase PCR analysis and could be reversed by knock-down of HIV-1 expression with HIV-1-specific siRNAs. Cells infected de novo by HIV-1 showed stronger transcriptional up-regulation of the HERV-K (HML-2) group than persistently infected cells of the same origin. Analysis of transcripts from individual members of this group revealed up-regulation of predominantly two proviral loci (ERVK-7 and ERVK-15) on chromosomes 1q22 and 7q34 in persistently infected KE37.1 cells, as well as in de novo HIV-1 infected LC5 cells, while only one single HML-2 locus (ERV-K6) on chromosome 7p22.1 was activated in persistently infected LC5 cells.

Conclusions: Our results demonstrate that HIV-1 can alter HERV transcription patterns of infected cells and indicate a correlation between activation of HERV elements and the level of HIV-1 production. Moreover, our results suggest that the effects of HIV-1 on HERV activity may be far more extensive and complex than anticipated from initial studies with clinical material.

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Down-regulation of HIV-1 induced HERV activity by siRNAs targeting HIV-1 transcripts. LC5-HIV cells were treated with the RNAiFect transfection reagent (mock), non-silencing siRNAs (sin.s.) or with siRNAs against gag (sigag), rev (sirev), nef (sinef) and env (sienv). Relative transcript levels of (A) HERV taxa S71pCRTK-1 (group HERV-T), (B) E4-1 (group HERV-E), (C) ERV9 and Seq59 (both group ERV9) and (D) HERV-KC4 (group HERV-K (HML-10)) were determined by qRT-PCR. The Y-axis shows the x-fold relative HERV transcript levels in LC5-HIV cells transfected with non-silencing siRNA (sin.s) and HIV-1-specific siRNAs (sigag, sitat/rev, sinef, sienv) referred to uninfected control cells. The data were normalized to the house-keeping gene RNA Polymerase II (RPII). Standard errors for triplicate experiments are indicated.
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Fig4: Down-regulation of HIV-1 induced HERV activity by siRNAs targeting HIV-1 transcripts. LC5-HIV cells were treated with the RNAiFect transfection reagent (mock), non-silencing siRNAs (sin.s.) or with siRNAs against gag (sigag), rev (sirev), nef (sinef) and env (sienv). Relative transcript levels of (A) HERV taxa S71pCRTK-1 (group HERV-T), (B) E4-1 (group HERV-E), (C) ERV9 and Seq59 (both group ERV9) and (D) HERV-KC4 (group HERV-K (HML-10)) were determined by qRT-PCR. The Y-axis shows the x-fold relative HERV transcript levels in LC5-HIV cells transfected with non-silencing siRNA (sin.s) and HIV-1-specific siRNAs (sigag, sitat/rev, sinef, sienv) referred to uninfected control cells. The data were normalized to the house-keeping gene RNA Polymerase II (RPII). Standard errors for triplicate experiments are indicated.

Mentions: The five HERV taxa S71pCRTK-1, E4-1, ERV-9, Seq59 and HERV-KC4 activated by HIV-1 in previous experiments were analyzed by qRT-PCR 72 hours after transfection of the siRNAs. Figure 4 shows the relative transcription levels of the HERV subgroups in the HIV-1 infected HeLa cells (LC5-HIV) transfected with specific siRNAs against gag, rev, nef and env compared to control cells transfected with non-silencing siRNA. Knockdown of HIV-1 in LC5-HIV cells resulted in a loss of HERV transcription in four of five HERV subgroups (Figure 4A-D). Only Seq59, a subgroup of ERV9 elements (Figure 4C), appears to be only partially diminished. Thus, we can show that knockdown of HIV-1 transcripts by RNAi reverses activation of specific HERV elements in infected cells. Moreover, overexpression of a natural inhibitor of HIV-1 production, the Rev-interacting human protein family (Risp) [57], was found to reverse HERV activation in HIV-1 infected LC5 cells (Additional file 2). Taken together, our results indicate that HIV-1 infection is associated with the activation of several taxa of class I and class II HERVs.Figure 4


Modulation of human endogenous retrovirus (HERV) transcription during persistent and de novo HIV-1 infection.

Vincendeau M, Göttesdorfer I, Schreml JM, Wetie AG, Mayer J, Greenwood AD, Helfer M, Kramer S, Seifarth W, Hadian K, Brack-Werner R, Leib-Mösch C - Retrovirology (2015)

Down-regulation of HIV-1 induced HERV activity by siRNAs targeting HIV-1 transcripts. LC5-HIV cells were treated with the RNAiFect transfection reagent (mock), non-silencing siRNAs (sin.s.) or with siRNAs against gag (sigag), rev (sirev), nef (sinef) and env (sienv). Relative transcript levels of (A) HERV taxa S71pCRTK-1 (group HERV-T), (B) E4-1 (group HERV-E), (C) ERV9 and Seq59 (both group ERV9) and (D) HERV-KC4 (group HERV-K (HML-10)) were determined by qRT-PCR. The Y-axis shows the x-fold relative HERV transcript levels in LC5-HIV cells transfected with non-silencing siRNA (sin.s) and HIV-1-specific siRNAs (sigag, sitat/rev, sinef, sienv) referred to uninfected control cells. The data were normalized to the house-keeping gene RNA Polymerase II (RPII). Standard errors for triplicate experiments are indicated.
© Copyright Policy - open-access
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4375885&req=5

Fig4: Down-regulation of HIV-1 induced HERV activity by siRNAs targeting HIV-1 transcripts. LC5-HIV cells were treated with the RNAiFect transfection reagent (mock), non-silencing siRNAs (sin.s.) or with siRNAs against gag (sigag), rev (sirev), nef (sinef) and env (sienv). Relative transcript levels of (A) HERV taxa S71pCRTK-1 (group HERV-T), (B) E4-1 (group HERV-E), (C) ERV9 and Seq59 (both group ERV9) and (D) HERV-KC4 (group HERV-K (HML-10)) were determined by qRT-PCR. The Y-axis shows the x-fold relative HERV transcript levels in LC5-HIV cells transfected with non-silencing siRNA (sin.s) and HIV-1-specific siRNAs (sigag, sitat/rev, sinef, sienv) referred to uninfected control cells. The data were normalized to the house-keeping gene RNA Polymerase II (RPII). Standard errors for triplicate experiments are indicated.
Mentions: The five HERV taxa S71pCRTK-1, E4-1, ERV-9, Seq59 and HERV-KC4 activated by HIV-1 in previous experiments were analyzed by qRT-PCR 72 hours after transfection of the siRNAs. Figure 4 shows the relative transcription levels of the HERV subgroups in the HIV-1 infected HeLa cells (LC5-HIV) transfected with specific siRNAs against gag, rev, nef and env compared to control cells transfected with non-silencing siRNA. Knockdown of HIV-1 in LC5-HIV cells resulted in a loss of HERV transcription in four of five HERV subgroups (Figure 4A-D). Only Seq59, a subgroup of ERV9 elements (Figure 4C), appears to be only partially diminished. Thus, we can show that knockdown of HIV-1 transcripts by RNAi reverses activation of specific HERV elements in infected cells. Moreover, overexpression of a natural inhibitor of HIV-1 production, the Rev-interacting human protein family (Risp) [57], was found to reverse HERV activation in HIV-1 infected LC5 cells (Additional file 2). Taken together, our results indicate that HIV-1 infection is associated with the activation of several taxa of class I and class II HERVs.Figure 4

Bottom Line: Analysis of transcripts from individual members of this group revealed up-regulation of predominantly two proviral loci (ERVK-7 and ERVK-15) on chromosomes 1q22 and 7q34 in persistently infected KE37.1 cells, as well as in de novo HIV-1 infected LC5 cells, while only one single HML-2 locus (ERV-K6) on chromosome 7p22.1 was activated in persistently infected LC5 cells.Our results demonstrate that HIV-1 can alter HERV transcription patterns of infected cells and indicate a correlation between activation of HERV elements and the level of HIV-1 production.Moreover, our results suggest that the effects of HIV-1 on HERV activity may be far more extensive and complex than anticipated from initial studies with clinical material.

View Article: PubMed Central - PubMed

Affiliation: Institute of Virology, Helmholtz Zentrum München, German Research Center for Environmental Health, Neuherberg, Germany. michelle.vincendeau@helmholtz-muenchen.de.

ABSTRACT

Background: The human genome contains multiple LTR elements including human endogenous retroviruses (HERVs) that together account for approximately 8-9% of the genomic DNA. At least 40 different HERV groups have been assigned to three major HERV classes on the basis of their homologies to exogenous retroviruses. Although most HERVs are silenced by a variety of genetic and epigenetic mechanisms, they may be reactivated by environmental stimuli such as exogenous viruses and thus may contribute to pathogenic conditions. The objective of this study was to perform an in-depth analysis of the influence of HIV-1 infection on HERV activity in different cell types.

Results: A retrovirus-specific microarray that covers major HERV groups from all three classes was used to analyze HERV transcription patterns in three persistently HIV-1 infected cell lines of different cellular origins and in their uninfected counterparts. All three persistently infected cell lines showed increased transcription of multiple class I and II HERV groups. Up-regulated transcription of five HERV taxa (HERV-E, HERV-T, HERV-K (HML-10) and two ERV9 subgroups) was confirmed by quantitative reverse transcriptase PCR analysis and could be reversed by knock-down of HIV-1 expression with HIV-1-specific siRNAs. Cells infected de novo by HIV-1 showed stronger transcriptional up-regulation of the HERV-K (HML-2) group than persistently infected cells of the same origin. Analysis of transcripts from individual members of this group revealed up-regulation of predominantly two proviral loci (ERVK-7 and ERVK-15) on chromosomes 1q22 and 7q34 in persistently infected KE37.1 cells, as well as in de novo HIV-1 infected LC5 cells, while only one single HML-2 locus (ERV-K6) on chromosome 7p22.1 was activated in persistently infected LC5 cells.

Conclusions: Our results demonstrate that HIV-1 can alter HERV transcription patterns of infected cells and indicate a correlation between activation of HERV elements and the level of HIV-1 production. Moreover, our results suggest that the effects of HIV-1 on HERV activity may be far more extensive and complex than anticipated from initial studies with clinical material.

Show MeSH
Related in: MedlinePlus