Antisense transcription of bovine leukemia virus is essential for viral replication and oncogenesis
Ontology highlight
ABSTRACT: In sheep infected with bovine leukemia virus (BLV), transcription of structural, enzymatic, and accessory genes is silenced. However, the BLV provirus transcribes a series of non-coding RNAs that remain undetected by the host immune response. Specifically, three RNAs (AS1-L, AS1-S, and AS2) are consistently expressed from the antisense strand, originating from transcriptional initiation at the 3'-LTR. To investigate the role of these non-coding RNAs in viral replication and pathogenesis, a reverse genetics approach was devised, capitalizing on a mechanistic disparity in transcription initiation between the 5' and 3' promoters. A two-nucleotide mutation (GG>TA) in the TFIIB-recognition element (BRE) impaired antisense transcription originating from the 3'-LTR. In the context of the provirus, this A1 mutation significantly diminished the expression of antisense RNAs, while not notably affecting sense transcription. When inoculated to sheep, the A1 provirus was infectious but exhibited reduced replication levels, shedding light on the role of antisense transcription in vivo. In comparison to lymphoid organs in sheep infected with a wild-type (WT) provirus, the A1 mutant demonstrated alterations in both the spatial distribution and rates of cell proliferation in the lymph nodes and the spleen. Analysis through RNA sequencing and RT-qPCR unveiled an upregulation of the Hmcn1 gene in B-lymphocytes from A1-infected sheep. Further examination via confocal microscopy and immunohistochemistry revealed an increase in the amount of hemicentin-1 protein encoded by Hmcn1 in peripheral blood mononuclear cells (PBMCs) and lymphoid organs of sheep infected with the A1 mutant. RNA interference targeting Hmcn1 expression impacted the migration of ovine kidney (OVK) cells in vitro. In contrast to the WT provirus, the A1 mutant lacked oncogenic activity when inoculated into sheep. Collectively, this study underscores the essential role of antisense transcription in BLV replication and pathogenicity. These findings may offer valuable insights into understanding the relevance of antisense transcription in the context of human T-cell leukemia virus (HTLV-1).
Project description:Bovine Leukemia Virus (BLV)-induced tumoral development is a multifactorial phenomenon which remains incompletely understood. Here, we highlight the critical role of the cellular CCCTC-binding factor (CTCF) both in the regulation of BLV transcriptional activities and in the deregulation of the three-dimensional (3D) chromatin architecture surrounding the BLV integration site. We demonstrated the in vivo recruitment of CTCF to three conserved CTCF binding motifs along the BLV provirus. Next, we showed the localization of CTCF to transitions in the histone modifications profile along BLV genome as well as its implication in the repression the 5’Long Terminal Repeat (LTR) promoter activity, thereby contributing to viral latency, while favoring the 3’LTR promoter activity. Finally, we demonstrated that BLV integration deregulated host cellular 3D chromatin organization through the formation of viral/host chromatin loops. Altogether, our results highlight CTCF as a new critical effector of BLV transcriptional regulation and BLV-induced physiopathology.
Project description:Bovine Leukemia Virus (BLV)-induced tumoral development is a multifactorial phenomenon which remains incompletely understood. Here, we highlight the critical role of the cellular CCCTC-binding factor (CTCF) both in the regulation of BLV transcriptional activities and in the deregulation of the three-dimensional (3D) chromatin architecture surrounding the BLV integration site. We demonstrated the in vivo recruitment of CTCF to three conserved CTCF binding motifs along the BLV provirus. Next, we showed the localization of CTCF to transitions in the histone modifications profile along BLV genome as well as its implication in the repression the 5’Long Terminal Repeat (LTR) promoter activity, thereby contributing to viral latency, while favoring the 3’LTR promoter activity. Finally, we demonstrated that BLV integration deregulated host cellular 3D chromatin organization through the formation of viral/host chromatin loops. Altogether, our results highlight CTCF as a new critical effector of BLV transcriptional regulation and BLV-induced physiopathology.
Project description:Long non-coding RNAs (lncRNAs) comprise a diverse class of gene expression regulators with emerging roles in many biological processes including cancer. Here we show that the expression of the lncRNA Hedgehog Interacting Protein Antisense 1 (HHIP-AS1) is a hallmark feature of human SHH-driven tumors. Importantly, loss of HHIP-AS1 leads to reduced tumor growth in SHH-driven tumors in vitro and in vivo. Our results demonstrate the power of cross-entity transcriptome-wide comparisons to identify novel epigenetic–regulatory lncRNA circuitries underlying human cancers.
Project description:The three-dimensional structure of the genome is a regulator of transcription and cell function; HIV-1 infection can influence host cell function, but the degree to which this is mediated through changes to host chromatin architecture is unclear. We interrogated genome-wide chromatin organization and the structure of chromatin around latently infected HIV-1 integration sites using Hi-C and ATAC-seq and combined these data with RNA transcriptional analysis of the provirus and neighboring genes in HIV-inducible cellular models. We found chromatin interaction networks around integrated HIV-1 are predominantly preserved with respect to uninfected cells, proving the lack of an obligate association between latent integration and major chromatin remodeling. Instead, we find that induction of proviral transcription may lead to local changes in chromatin accessibility downstream from the 3’ LTR, demonstrating that HIV-1 can alter local cellular chromatin structure post-integration. Using long-read Nanopore RNA-seq, we interrogated the local host and HIV-1 transcriptomes and observed that 1-5% of HIV-1 transcripts initiated at the 5’ LTR promoter extended into the flanking cellular genome, generating chimeric virus-host RNAs. Thus, integration leading to latency (and provirus activation) may not lead to obligate global chromatin rearrangements; we also observed, previously unreported, novel changes in chromatin accessibility during HIV-1 transcription.
Project description:Characterisation IER3-AS1 interacting proteins using chromatin oligo-affinity precipitation (ChOP) followed by mass spectrometry. The HeLa cell lysates was incubated with biotinylated antisense oligonucleotides (ASO), targeting an experimental target antisense long noncoding RNA IER3-AS1 or a control RNA LacZ. LacZ and IER3-AS1 interacting proteomes were pulldown using Streptavidin beads. The eluted protein samples from both LacZ control ASOs and IER3-AS1 ASOs subjected to mass-spectrometry analyses to identify IER3-AS1 interacting proteins.
Project description:Systemic sclerosis (SSc) is an autoimmune disease characterized by fibrosis of skin and multiple organs of which the pathogenesis is poorly understood. Here we studied differentially expressed coding and non-coding genes in relation to SSc pathogenesis with a specific focus on antisense non-coding RNAs. Skin biopsy-derived RNAs from fourteen early SSc patients and six healthy individuals were sequenced with ion-torrent and analysed using DEseq2. Overall, 4901 genes with a fold change >1.5 and a false discovery rate < 5% were detected in patients versus controls. Upregulated genes clustered in immunological, cell adhesion and keratin-related processes. Interestingly, 676 deregulated non-coding genes were detected, 257 of which were classified as antisense genes. Sense genes expressed opposite of these antisense genes were also deregulated in 42% of the observed sense-antisense gene pairs. The majority of the antisense genes had a similar effect sizes in an independent North American dataset with three genes (CTBP1-AS2, OTUD6B-AS1 and AGAP2-AS1) exceeding the study-wide Bonferroni-corrected ρ-value (PBonf<0.0023, Pcombined = 1.1x10-9, 1.4x10-8, 1.7x10-6, respectively). In this study, we highlight that together with coding genes, (antisense) long non-coding RNAs are deregulated in skin tissue of SSc patients suggesting a novel class of genes involved in pathogenesis of SSc.
Project description:LncRNA Hypoxia-inducible factor 1α-antisense 1 (HIF1α-AS1) is located on the antisense strand of the important Hypoxia-inducible factor 1α (HIF1α) gene, but being transcribed in antisense direction along the HIF1α promoter. Here we used the 3’end biotinylated HIF1a-AS1 RNA and a control RNA for RNA Pulldown and searched for interacting proteins in nuclear extracts of human umbilical vein endothelial cells (HUVEC).
Project description:NFYC-AS1 is an overlapping antisense RNA transcribed head-to-head to NFYC sense gene, encoding for the subunit C of NF-Y transcription factor, which is known as master regulator of cell cycle and proliferation in normal and tumor cells. Here we performed NFYC-AS1 silencing in lung squamous carcinoma H520 cells by Gapmer antisense oligonucleotides and CRISPR/Cas9 TSS deletion. Afterwards, we performed differentially expressed analysis and gene set enrichement analysis to investigate on NFYC-AS1 function and mechanism of action.
Project description:LlorénsRico2016 - Effects of cis-Encoded antisense RNAs (asRNAs) - Case1
Three
putative effects of the asRNAs were considered in this study: in
case 1
(this
model)
,
the binding of the asRNA to the corresponding mRNA induces
degradation of the duplex. In case 2, the binding of the asRNA to
the mRNA induces degradation of the mRNA, but not of the asRNA.
In case 3, the mRNA and the asRNA bind reversibly to form a
stable duplex, preventing translation of the mRNA. In all the
three cases, binding to the ribosome protects the mRNA from the
effect of the asRNA.
This model is described in the article:
Bacterial antisense RNAs are
mainly the product of transcriptional noise.
Lloréns-Rico V, Cano J,
Kamminga T, Gil R, Latorre A, Chen WH, Bork P, Glass JI, Serrano
L, Lluch-Senar M.
Sci Adv 2016 Mar; 2(3): e1501363
Abstract:
cis-Encoded antisense RNAs (asRNAs) are widespread along
bacterial transcriptomes. However, the role of most of these
RNAs remains unknown, and there is an ongoing discussion as to
what extent these transcripts are the result of transcriptional
noise. We show, by comparative transcriptomics of 20 bacterial
species and one chloroplast, that the number of asRNAs is
exponentially dependent on the genomic AT content and that
expression of asRNA at low levels exerts little impact in terms
of energy consumption. A transcription model simulating mRNA
and asRNA production indicates that the asRNA regulatory effect
is only observed above certain expression thresholds,
substantially higher than physiological transcript levels.
These predictions were verified experimentally by
overexpressing nine different asRNAs in Mycoplasma pneumoniae.
Our results suggest that most of the antisense transcripts
found in bacteria are the consequence of transcriptional noise,
arising at spurious promoters throughout the genome.
This model is hosted on
BioModels Database
and identified by:
MODEL1511170000.
To cite BioModels Database, please use:
BioModels Database:
An enhanced, curated and annotated resource for published
quantitative kinetic models.
To the extent possible under law, all copyright and related or
neighbouring rights to this encoded model have been dedicated to
the public domain worldwide. Please refer to
CC0
Public Domain Dedication for more information.
Project description:LlorénsRico2016 - Effects of cis-Encoded
antisense RNAs (asRNAs) - Case1
Three
putative effects of the asRNAs were considered in this study: in
case 1
,
the binding of the asRNA to the corresponding mRNA induces
degradation of the duplex. In case 2
(this
model)
the binding of the asRNA to the mRNA induces degradation of the
mRNA, but not of the asRNA. In case 3, the mRNA and the asRNA
bind reversibly to form a stable duplex, preventing translation
of the mRNA. In all the three cases, binding to the ribosome
protects the mRNA from the effect of the asRNA.
This model is described in the article:
Bacterial antisense RNAs are
mainly the product of transcriptional noise.
Lloréns-Rico V, Cano J,
Kamminga T, Gil R, Latorre A, Chen WH, Bork P, Glass JI, Serrano
L, Lluch-Senar M.
Sci Adv 2016 Mar; 2(3): e1501363
Abstract:
cis-Encoded antisense RNAs (asRNAs) are widespread along
bacterial transcriptomes. However, the role of most of these
RNAs remains unknown, and there is an ongoing discussion as to
what extent these transcripts are the result of transcriptional
noise. We show, by comparative transcriptomics of 20 bacterial
species and one chloroplast, that the number of asRNAs is
exponentially dependent on the genomic AT content and that
expression of asRNA at low levels exerts little impact in terms
of energy consumption. A transcription model simulating mRNA
and asRNA production indicates that the asRNA regulatory effect
is only observed above certain expression thresholds,
substantially higher than physiological transcript levels.
These predictions were verified experimentally by
overexpressing nine different asRNAs in Mycoplasma pneumoniae.
Our results suggest that most of the antisense transcripts
found in bacteria are the consequence of transcriptional noise,
arising at spurious promoters throughout the genome.
This model is hosted on
BioModels Database
and identified by:
MODEL1511170001.
To cite BioModels Database, please use:
BioModels Database:
An enhanced, curated and annotated resource for published
quantitative kinetic models.
To the extent possible under law, all copyright and related or
neighbouring rights to this encoded model have been dedicated to
the public domain worldwide. Please refer to
CC0
Public Domain Dedication for more information.