1
|
Integration in oncogenes plays only a minor role in determining the in vivo distribution of HIV integration sites before or during suppressive antiretroviral therapy. PLoS Pathog 2021; 17:e1009141. [PMID: 33826675 PMCID: PMC8055010 DOI: 10.1371/journal.ppat.1009141] [Citation(s) in RCA: 38] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2020] [Revised: 04/19/2021] [Accepted: 03/24/2021] [Indexed: 12/11/2022] Open
Abstract
HIV persists during antiretroviral therapy (ART) as integrated proviruses in cells descended from a small fraction of the CD4+ T cells infected prior to the initiation of ART. To better understand what controls HIV persistence and the distribution of integration sites (IS), we compared about 15,000 and 54,000 IS from individuals pre-ART and on ART, respectively, with approximately 395,000 IS from PBMC infected in vitro. The distribution of IS in vivo is quite similar to the distribution in PBMC, but modified by selection against proviruses in expressed genes, by selection for proviruses integrated into one of 7 specific genes, and by clonal expansion. Clones in which a provirus integrated in an oncogene contributed to cell survival comprised only a small fraction of the clones persisting in on ART. Mechanisms that do not involve the provirus, or its location in the host genome, are more important in determining which clones expand and persist. In HIV-infected individuals, a small fraction of the infected cells persist and divide. This reservoir persists during fully suppressive ART and can rekindle the infection if ART is discontinued. Because the number of possible sites of HIV DNA integration is very large, each infected cell, and all of its descendants, can be identified by the site where the provirus is integrated (IS). To understand the selective forces that determine the fates of infected cells in vivo, we compared the distribution of HIV IS in freshly-infected cells to cells from HIV-infected donors sampled both before and during ART. We found that, as previously reported, integration favors highly-expressed genes. However, over time, the fraction of cells with proviruses integrated in highly-expressed genes decreases, implying that they grow less well. There are exceptions to this broad negative selection. When a provirus is integrated in a specific region in one of seven genes, the proviruses affect the expression of the target gene, promoting growth and/or survival of the cell. Although this effect is striking, it is only a minor component of the forces that promote the growth and survival of the population of infected cells during ART.
Collapse
|
2
|
Transcriptional behavior of the HIV-1 promoter in context of the BACH2 prominent proviral integration gene. Virus Res 2020; 293:198260. [PMID: 33316352 DOI: 10.1016/j.virusres.2020.198260] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2020] [Accepted: 12/04/2020] [Indexed: 11/23/2022]
Abstract
Chronic infection with human immunodeficiency virus (HIV)-1 is characterized by accumulation of proviral sequences in the genome of target cells. Integration of viral DNA in patients on long-term antiretroviral therapy selectively persists at preferential loci, suggesting site-specific crosstalk of viral sequences and human genes. This crosstalk likely contributes to chronic HIV disease through modulation of host immune pathways and emergence of clonal infected cell populations. To systematically interrogate such effects, we undertook genome engineering to generate Jurkat cell models that replicate integration of HIV-1 long terminal repeat (LTR) sequences at the BTB and CNC Homolog 2 (BACH2) integration locus. This locus is a prominent HIV-1 integration gene in chronic infection, found in 30 % of long-term treated patients with mapped proviral integrations. Using five clonal models carrying an LTR-driven reporter at different BACH2 intergenic regions, we here show that LTR transcriptional activity is repressed in BACH2 regions associated with proviral-DNA integrations in vivo but not in a control region. Our data indicates that this repression is in part epigenetically regulated, particularly through DNA methylation. Importantly, we demonstrate that transcriptional activity of the LTR is independent of BACH2 gene transcription and vice versa in our models. This suggests no transcriptional interference of endogenous and HIV-1 promoters. Taken together, our study provides first insights into how activity of HIV-1 LTR sequences is regulated at the BACH2 locus as prominent example for a recurrently-detected integration gene in chronic infection. Given the importance of integration-site dependent virus/host crosstalk for chronic HIV disease, our findings for the BACH2 locus have potential implications for future therapeutic strategies.
Collapse
|
3
|
Inderbitzin A, Kok YL, Jörimann L, Kelley A, Neumann K, Heinzer D, Cathomen T, Metzner KJ. HIV-1 promoter is gradually silenced when integrated into BACH2 in Jurkat T-cells. PeerJ 2020; 8:e10321. [PMID: 33282555 PMCID: PMC7694569 DOI: 10.7717/peerj.10321] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Accepted: 10/17/2020] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND The persistence of the latent HIV-1 reservoir is a major obstacle to curing HIV-1 infection. HIV-1 integrates into the cellular genome and some targeted genomic loci are frequently detected in clonally expanded latently HIV-1 infected cells, for instance, the gene BTB domain and CNC homology 2 (BACH2). METHODS We investigated HIV-1 promoter activity after integration into specific sites in BACH2 in Jurkat T-cells. The HIV-1-based vector LTatCL[M] contains two fluorophores: (1) Cerulean, which reports the activity of the HIV-1 promoter and (2) mCherry driven by a constitutive promotor and flanked by genetic insulators. This vector was inserted into introns 2 and 5 of BACH2 of Jurkat T-cells via CRISPR/Cas9 technology in the same and convergent transcriptional orientation of BACH2, and into the genomic safe harbour AAVS1. Single cell clones representing active (Cerulean+/mCherry+) and inactive (Cerulean-/mCherry+) HIV-1 promoters were characterised. RESULTS Upon targeted integration of the 5.3 kb vector LTatCL[M] into BACH2, the HIV-1 promoter was gradually silenced as reflected by the decrease in Cerulean expression over a period of 162 days. Silenced HIV-1 promoters could be reactivated by TNF-α and Romidepsin. This observation was independent of the targeted intron and the transcriptional orientation. BACH2 mRNA and protein expression was not impaired by mono-allelic integration of LTatCL[M]. CONCLUSION Successful targeted integration of the HIV-1-based vector LTatCL[M] allows longitudinal analyses of HIV-1 promoter activity.
Collapse
Affiliation(s)
- Anne Inderbitzin
- Department of Infectious Diseases and Hospital Epidemiology, Division of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, Zurich, Switzerland
- Institute of Medical Virology, University of Zurich, Zurich, Switzerland
- Life Science Zurich Graduate School, University of Zurich, Zurich, Switzerland
| | - Yik Lim Kok
- Department of Infectious Diseases and Hospital Epidemiology, Division of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, Zurich, Switzerland
- Institute of Medical Virology, University of Zurich, Zurich, Switzerland
| | - Lisa Jörimann
- Department of Infectious Diseases and Hospital Epidemiology, Division of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, Zurich, Switzerland
- Institute of Medical Virology, University of Zurich, Zurich, Switzerland
- Life Science Zurich Graduate School, University of Zurich, Zurich, Switzerland
| | - Audrey Kelley
- Department of Infectious Diseases and Hospital Epidemiology, Division of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, Zurich, Switzerland
- Institute of Medical Virology, University of Zurich, Zurich, Switzerland
- Life Science Zurich Graduate School, University of Zurich, Zurich, Switzerland
| | - Kathrin Neumann
- Department of Infectious Diseases and Hospital Epidemiology, Division of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, Zurich, Switzerland
- Institute of Medical Virology, University of Zurich, Zurich, Switzerland
| | - Daniel Heinzer
- Institute for Neuropathology, University Hospital Zurich, Zurich, Switzerland
- Neuroscience Center Zurich Graduate School, University of Zurich, Zurich, Switzerland
| | - Toni Cathomen
- Institute for Transfusion Medicine and Gene Therapy, Medical Center, University of Freiburg, Freiburg, Germany
- Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Karin J. Metzner
- Department of Infectious Diseases and Hospital Epidemiology, Division of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, Zurich, Switzerland
- Institute of Medical Virology, University of Zurich, Zurich, Switzerland
| |
Collapse
|