Unintegrated HIV-1 DNAs are loaded with core and linker histones and transcriptionally silenced

Geis, Franziska K.; Goff, Stephen P.

doi:10.1073/pnas.1912638116

Cited by 46 publications

(63 citation statements)

References 51 publications

(64 reference statements)

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“…We used ChIP-PCR to quantify the level of two inhibitory chromatin modifications (H3K9me3 and H3K27me3) and two activating chromatin modifications (H3K4me3 and H3Ac) on integrated and unintegrated HIV-1 DNA in the presence and absence of Tax. As previously reported (16), unintegrated HIV-1 DNA was significantly enriched for repressive H3K9 trimethylation, and depleted for activating H3K4 trimethylation, when compared to integrated proviruses ( Fig. 4A).…”

Section: Tax Expression Allows In-hiv-1 To Mount a Spreading Infectionsupporting

confidence: 86%

“…These increases in viral DNA and protein expression were lost when a replication incompetent, env-deficient HIV-1 was analyzed, and hence must result from virus spread ( Fig. 2E and F Previously, it has been reported that unintegrated retroviral DNA is rapidly chromatinized after nuclear entry and then decorated with inhibitory epigenetic marks that are removed, by an unknown process, after integration occurs (16,17). Here, we demonstrate that Tax expression also reduces the deposition of inhibitory chromatin marks, and increases the deposition of activating marks, on unintegrated proviral DNA (Fig.…”

Section: Discussionmentioning

confidence: 91%

“…It has previously been reported that unintegrated HIV-1 DNA is rapidly loaded with core and linker histones and then epigenetically silenced due to the addition of inhibitory histone modifications (16). Therefore, we predicted that Tax, which induces the efficient transcription of unintegrated HIV-1 DNA, was likely acting to prevent this latter effect.…”

Section: Tax Expression Allows In-hiv-1 To Mount a Spreading Infectionmentioning

confidence: 93%

“…Conversely, we hypothesize that retroviruses avoid cellular restriction factors that recognize and silence extrachromosomal DNA by integrating their proviral DNA into the host genome, where it eludes detection. It is well established that unintegrated retroviral DNA is rapidly loaded with histones that are then decorated with repressive chromatin marks that induce epigenetic silencing (16,17). In the case of unintegrated murine leukemia virus (MLV) DNA, epigenetic silencing is mediated not by PML-NBs but rather by a DNA binding protein called NP220 acting in concert with the human silencing hub (HUSH) complex (18).…”

Section: Introductionmentioning

confidence: 99%

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Robust HIV-1 replication in the absence of integrase function

Irwan

Karnowski

Bogerd

et al. 2020

Preprint

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Integration of the proviral DNA intermediate into the host cell genome represents an essential step in the retroviral life cycle. While the reason(s) for this requirement remains unclear, it is known that unintegrated proviral DNA is epigenetically silenced. Here, we demonstrate that HIV-1 mutants lacking functional integrase can mount a robust, spreading infection in cells expressing the Tax transcription factor encoded by human T-cell leukemia virus 1. In these cells, HIV-1 forms episomal DNA circles, analogous to Hepatitis B virus covalently closed circular DNAs (cccDNAs), that are transcriptionally active and fully capable of supporting viral replication. This rescue correlates with the loss of inhibitory epigenetic marks, and the acquisition of activating marks, on histones bound to unintegrated HIV-1 DNA. Thus retroviral DNA integration may have evolved, at least in part, as a mechanism to avoid the epigenetic silencing of extrachromosomal viral DNA by host innate antiviral factors. SignificanceWhile retroviral DNA is synthesized normally after infection by integrase-deficient viruses, the resultant episomal DNA is then epigenetically silenced. Here, we show that expression of the Tax transcription factor encoded by a second human retrovirus, HTLV-1, prevents the epigenetic silencing of unintegrated HIV-1 DNA and instead induces the addition of activating epigenetic marks, and the recruitment of NF-kB/Rel proteins, to the HIV-1 LTR promoter. Moreover, in the presence of Tax, the HIV-1 DNA circles that form in the absence of integrase function are not only efficiently transcribed but also support a spreading, pathogenic IN-HIV-1 infection. Thus, retroviruses have the potential to replicate without integration, as is indeed seen with HBV.

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Section: Tax Expression Allows In-hiv-1 To Mount a Spreading Infectionsupporting

confidence: 86%

Section: Discussionmentioning

confidence: 91%

Section: Tax Expression Allows In-hiv-1 To Mount a Spreading Infectionmentioning

confidence: 93%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Robust HIV-1 replication in the absence of integrase function

Irwan

Karnowski

Bogerd

et al. 2020

Preprint

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show abstract

“…Indeed, integrated viral DNA was measured in TGCs by Alu-gag PCR and was inhibited by a RT inhibitor, demonstrating the specificity of this detection. In addition, early viral protein synthesis was observed in labelled germ cells using confocal microscopy, an indicator of viral integration since unintegrated HIV-1 DNA is associated with transcriptional silencing [65]. Finally, viral proteins detection in TGCs by flow cytometry was inhibited by both RT and integrase inhibitors.…”

Section: Discussionmentioning

confidence: 99%

Potential for virus endogenization in humans through testicular germ cell infection: the case of HIV

Mahé

Matusali

Deléage

et al. 2020

Preprint

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30Viruses have colonized the germ line of our ancestors at several occasions during evolution, 31 leading to the integration in the human genome of viral sequences from over 30 retroviral 32 groups and a few non-retroviruses. Among the recently emerged viruses infecting humans, 33 several target the testis (eg HIV, Zika and Ebola viruses). Here we aimed to investigate whether 34 human testicular germ cells (TGCs) can support integration by HIV, a contemporary retrovirus 35 that started to spread in the human population during the last century. We report that albeit 36 alternative receptors enabled HIV-1 binding to TGCs, HIV virions failed to infect TGCs in 37 vitro. Nevertheless, exposure of TGCs to infected lymphocytes, naturally present in the testis 38 from HIV+ men, led to HIV-1 entry, integration and early protein expression. Similarly, cell-39 associated infection or bypassing viral entry led to HIV-1 integration in a spermatogonial cell 40 line. Using DNAscope, HIV-1 and SIV DNA were detected within a few TGCs in the testis 41 from one infected patient, one rhesus macaque and one African Green monkey in vivo. 42 Molecular landscape analysis revealed that early TGCs were enriched in HIV early co-factors 43 up to integration and had overall low antiviral defenses when compared with testicular 44 macrophages and Sertoli cells. In conclusion, our study reveals that TGCs can support the entry 45 and integration of HIV upon cell-associated infection. This could represent a way for this 46 contemporary virus to integrate our germline and become endogenous in the future, as happened 47 Importance 52 Viruses have colonized the host germ line at many occasions during evolution to eventually 53 become endogenous. Here we aimed at investigating whether human testicular germ cells 54 (TGCs) can support such viral invasion by studying HIV interactions with TGCs in vitro. Our 55 results indicate that isolated primary TGCs express alternative HIV-1 receptors allowing virions 56 binding but not entry. However, HIV-1 entered and integrated in TGCs upon cell-associated 57 infection, and produced low level of viral proteins. In vivo, HIV-1 and SIV DNA was detected 58 in a few TGCs. Molecular landscape analysis showed that TGCs have overall weak antiviral 59 defenses. Altogether, our results indicate that human TGCs can support HIV-1 early replication 60 including integration, suggesting potential for endogenization in the future generations. 61 62 63 Retroviruses have repeatedly infected the germline during our evolution and integrated their 64 DNA into the host genome , which has been passed on to the next generations by Mendelian 65 inheritance [1,2]. When not detrimental, the integration of viral sequences has led to their 66 fixation and endogenization in the population [3]. Thus, about 8% of the human genome is now 67 composed of endogenous retroviruses (ERVs), representing 31 distinct viral groups [2]. Such 68 integration, still ongoing in mammals [4], has driven the acquisition of new functions in the 69 host,...

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Chromatin Immunoprecipitation of Retroviral Genomes with Antibodies Recognizing Modified Histones and Specific Viral Proteins

Geis,

Goff

2024

Methods in Molecular Biology

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Unintegrated HIV-1 DNAs are loaded with core and linker histones and transcriptionally silenced

Cited by 46 publications

References 51 publications

Robust HIV-1 replication in the absence of integrase function

Robust HIV-1 replication in the absence of integrase function

Potential for virus endogenization in humans through testicular germ cell infection: the case of HIV

Chromatin Immunoprecipitation of Retroviral Genomes with Antibodies Recognizing Modified Histones and Specific Viral Proteins

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