scholarly journals Over-representation of MEF-2 isoforms (A/C) is associated with HTLV-1-induced acute ATLL and their recruitment to 3’LTR facilitates HBZ expression from the antisense promoter via interactions with Menin and Jun D

2021 ◽  
Author(s):  
Kiran Madugula ◽  
Julie Joseph ◽  
Vanessa Teixeira ◽  
Rashida Ginwala ◽  
Catherine Demarino ◽  
...  
Keyword(s):  
T Cell ◽  
Transcriptional Control ◽  
Treatment Options ◽  
Viral Gene Expression ◽  
Etiologic Agent ◽  
Antisense Strand ◽  
Viral Gene ◽  
Adult T Cell Leukemia

Abstract Background. HTLV-1 is a complex human retrovirus and an etiologic agent causing a malignant and intractable T-cell neoplasia termed Adult T-cell leukemia and lymphoma (ATLL). Patients suffering from ATLL present with poor prognoses and a dearth of treatment options warranting a continuous need to develop novel therapeutic targets. In contrast to the HTLV-1 transactivator protein Tax, HTLV-1 bZIP protein (HBZ) maintains its expression in ATLL cells. The HBZ gene is encoded from the antisense strand of the provirus and is not under the transcriptional control of the 5’ long terminal repeat (LTR) unlike other viral genes such as Tax. Few modifications have been reported in the 3’LTR, which regulates HBZ expression. Herein, we delineate the activities of a transcription factor MEF (Myocyte enhancer factor)-2 at both 5’ and 3’LTRs in the context of ATLL progression and maintenance. Results. In this study, we report that two MEF isoforms (2A and 2C) are highly overexpressed in acute ATLL patients from North America. These isoforms are recruited to the viral promoters at both the 5’ and 3’LTRs. Their knockdown by shRNAs resulted in the downregulation of Tax and HBZ expression as well as a significant decrease in proliferation and cell cycle arrest in ATLL cells. Similarly, chemical inhibition of MEF proteins by MC1568 (a selective Class IIa HDAC inhibitor) resulted in the cytotoxicity of ATLL cells in vitro as well as reduction of proviral load and viral gene expression in vivo. At the molecular level, high enrichment of MEF-2C occurred at the 3’LTR along with cofactors Menin, Jun D, and Sp1/Sp3 thus providing a novel mechanism of regulation at the antisense promoter of HTLV-1. Conclusions. This study establishes MEF-2 as critical players in ATLL, which interacts with Tax and HBZ at their respective promoters highlighting a novel mechanism of regulation at the 3’LTR involving Jun D and Menin. MEF signaling represent a potential target for therapeutic intervention.

scholarly journals Mechanisms of Oncogenesis by HTLV-1 Tax

Pathogens ◽  
2020 ◽  
Vol 9 (7) ◽  
pp. 543 ◽  
Author(s):  
Suchitra Mohanty ◽  
Edward W. Harhaj
Keyword(s):  
T Cells ◽  
T Cell ◽  
Leucine Zipper ◽  
Viral Gene Expression ◽  
Viral Persistence ◽  
Viral Gene ◽  
Basic Leucine Zipper ◽  
Adult T Cell Leukemia ◽  
Human T Cell ◽  
Apoptotic Genes

The human T-cell lymphotropic virus type 1 (HTLV-1) is the etiological agent of adult T-cell leukemia/lymphoma (ATLL), a neoplasm of CD4+CD25+ T cells that occurs in 2–5% of infected individuals after decades of asymptomatic latent infection. Multiple HTLV-1-encoded regulatory proteins, including Tax and HTLV-1 basic leucine zipper factor (HBZ), play key roles in viral persistence and latency. The HTLV-1 Tax oncoprotein interacts with a plethora of host cellular proteins to regulate viral gene expression and also promote the aberrant activation of signaling pathways such as NF-κB to drive clonal proliferation and survival of T cells bearing the HTLV-1 provirus. Tax undergoes various post-translational modifications such as phosphorylation and ubiquitination that regulate its function and subcellular localization. Tax shuttles in different subcellular compartments for the activation of anti-apoptotic genes and deregulates the cell cycle with the induction of DNA damage for the accumulation of genomic instability that can result in cellular immortalization and malignant transformation. However, Tax is highly immunogenic and therefore HTLV-1 has evolved numerous strategies to tightly regulate Tax expression while maintaining the pool of anti-apoptotic genes through HBZ. In this review, we summarize the key findings on the oncogenic mechanisms used by Tax that set the stage for the development of ATLL, and the strategies used by HTLV-1 to tightly regulate Tax expression for immune evasion and viral persistence.

Histone deacetylase–mediated transcriptional activation reduces proviral loads in HTLV-1–associated myelopathy/tropical spastic paraparesis patients

Blood ◽  
2007 ◽  
Vol 110 (10) ◽  
pp. 3722-3728 ◽  
Author(s):  
Agnès Lezin ◽  
Nicolas Gillet ◽  
Stéphane Olindo ◽  
Aïssatou Signaté ◽  
Nathalie Grandvaux ◽  
...  
Keyword(s):  
Histone Deacetylase ◽  
Transcriptional Activation ◽  
Gene Activation ◽  
Spastic Paraparesis ◽  
Viral Gene Expression ◽  
Tropical Spastic Paraparesis ◽  
Viral Reservoir ◽  
Viral Gene

AbstractEpigenetic modifications of chromatin may play a role in maintaining viral latency and thus persistence of the human T-lymphotropic virus type 1 (HTLV-1), which is responsible for HTLV-associated myelopathy/tropical spastic paraparesis (HAM/TSP). A major determinant of disease progression is increased peripheral blood proviral load (PVL), possibly via the accumulation of infected cells in the central nervous system (CNS) creating a damaging inflammatory response. Current therapeutic approaches that focus on reducing either cell proliferation, viral replication, or tissue invasion are still unsatisfactory. Contrasting with these inhibitory strategies, we evaluated the efficacy of a novel approach aimed, paradoxically, at activating viral gene expression to expose virus-positive cells to the host immune response. We used valproate (VPA), a histone deacetylase inhibitor that has been used for decades as a chronic, safe treatment for epileptic disorders. Based on in vitro and in vivo data, we provide evidence that transient activation of the latent viral reservoir causes its collapse, a process that may alleviate the condition of HAM/TSP. This represents the first such approach to treating HAM/TSP, using gene activation therapy to tilt the host-pathogen balance in favor of an existing antiviral response. This trial is registered at http://clinicaltrials.gov/as no. NCT00519181.

Selective Ablation of Human T-Cell Lymphotropic Virus Type 1 p12I Reduces Viral Infectivity In Vivo

Blood ◽  
1998 ◽  
Vol 91 (12) ◽  
pp. 4701-4707 ◽  
Author(s):  
Nathaniel D. Collins ◽  
Garret C. Newbound ◽  
Björn Albrecht ◽  
Jennifer L. Beard ◽  
Lee Ratner ◽  
...  
Keyword(s):  
T Cell ◽  
Virus Type ◽  
Rabbit Model ◽  
Etiologic Agent ◽  
Peripheral Blood Mononuclear ◽  
Antigen Production ◽  
Human T Cell

Human T-cell lymphotropic virus type 1 (HTLV-1) is the etiologic agent of adult T-cell leukemia and HTLV-1-associated myelopathy. Novel, yet conserved RNA transcripts encoded from open reading frames (ORFs) I and II of the viral pX region are expressed both in vitro and in infected individuals. The ORF I mRNA encodes the protein p12I, which has been shown to localize to cellular endomembranes, cooperate with bovine papillomavirus E5 in transformation, as well as bind to the IL-2 receptor β and γ chains and the H+ vacuolar ATPase. It is unknown what role p12I plays in the viral life cycle. Using an infectious molecular clone of HTLV-1 (ACH) and a derivative clone, ACH.p12I, which fails to produce the p12Imessage, we investigated the importance of p12I in infected primary cells and in a rabbit model of the infection. ACH.p12I was infectious in vitro as shown by viral passage in culture and no qualitative or quantitative differences were noted between ACH and ACH.p12I in posttransfection viral antigen production. However, in contrast to ACH, ACH.p12I failed to establish persistent infection in vivo as indicated by reduced anti-HTLV-1 antibody responses, failure to demonstrate viral p19 antigen production in peripheral blood mononuclear cell (PBMC) cultures, and only transient detection of provirus by polymerase chain reaction in PBMC from ACH.p12I-inoculated rabbits. These results are the first to show the essential role of HTLV-1 p12I in the establishment of persistent viral infection in vivo and suggest potential new targets in antiviral strategies to prevent HTLV-1 infection.

Development of a novel redirected T-cell–based adoptive immunotherapy targeting human telomerase reverse transcriptase for adult T-cell leukemia

Blood ◽  
2013 ◽  
Vol 121 (24) ◽  
pp. 4894-4901 ◽  
Author(s):  
Yukihiro Miyazaki ◽  
Hiroshi Fujiwara ◽  
Hiroaki Asai ◽  
Fumihiro Ochi ◽  
Toshiki Ochi ◽  
...  
Keyword(s):  
T Cell ◽  
Adoptive Immunotherapy ◽  
Receptor Gene ◽  
Cell Receptor ◽  
T Cell Leukemia ◽  
Cell Leukemia ◽  
Human Telomerase Reverse Transcriptase ◽  
Adult T Cell Leukemia

Key Points The efficacy and safety of a novel redirected T-cell–based adoptive immunotherapy targeting hTERT for patients with adult T-cell leukemia. hTERT-specific T-cell receptor gene-transduced CD8+ T cells lyse ATL cells, but not normal cells, both in vitro and in vivo.

scholarly journals The orphan nuclear receptor LRH-1/NR5a2 critically regulates T cell functions

2019 ◽  
Vol 5 (7) ◽  
pp. eaav9732 ◽  
Author(s):  
Carina Seitz ◽  
Juan Huang ◽  
Anna-Lena Geiselhöringer ◽  
Pamela Galbani-Bianchi ◽  
Svenja Michalek ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Nuclear Receptor ◽  
Transcriptional Control ◽  
Intestinal Inflammation ◽  
Critical Role ◽  
Orphan Nuclear Receptor ◽  
Cell Functions

LRH-1 (liver receptor homolog-1/NR5a2) is an orphan nuclear receptor, which regulates glucose and lipid metabolism, as well as intestinal inflammation via the transcriptional control of intestinal glucocorticoid synthesis. Predominantly expressed in epithelial cells, its expression and role in immune cells are presently enigmatic. LRH-1 was found to be induced in immature and mature T lymphocytes upon stimulation. T cell–specific deletion of LRH-1 causes a drastic loss of mature peripheral T cells. LRH-1–depleted CD4+ T cells exert strongly reduced activation-induced proliferation in vitro and in vivo and fail to mount immune responses against model antigens and to induce experimental intestinal inflammation. Similarly, LRH-1–deficient cytotoxic CD8+ T cells fail to control viral infections. This study describes a novel and critical role of LRH-1 in T cell maturation, functions, and immopathologies and proposes LRH-1 as an emerging pharmacological target in the treatment of T cell–mediated inflammatory diseases.

scholarly journals Cell-to-Cell Contact as an Efficient Mode of Epstein-Barr Virus Infection of Diverse Human Epithelial Cells

1998 ◽  
Vol 72 (5) ◽  
pp. 4371-4378 ◽  
Author(s):  
Shosuke Imai ◽  
Jun Nishikawa ◽  
Kenzo Takada
Keyword(s):  
Epithelial Cells ◽  
Cell Lines ◽  
Viral Gene Expression ◽  
Viral Gene ◽  
Cell Contact ◽  
Barr Virus ◽  
Epithelial Cell Lines ◽  
Epstein Barr

ABSTRACT We show clear evidence for direct infection of various human epithelial cells by Epstein-Barr virus (EBV) in vitro. The successful infection was achieved by using recombinant EBV (Akata strain) carrying a selective marker gene but without any other artificial operations, such as introduction of the known EBV receptor (CD21) gene or addition of polymeric immunoglobulin A against viral gp350 in culture. Of 21 human epithelial cell lines examined, 18 became infected by EBV, as ascertained by the detection of EBV-determined nuclear antigen (EBNA) 1 expression in the early period after virus exposure, and the following selection culture easily yielded a number of EBV-infected clones from 15 cell lines. None of the human fibroblasts and five nonhuman-derived cell lines examined was susceptible to the infection. By comparison, cocultivation with virus producers showed ≈800-fold-higher efficiency of infection than cell-free infection did, suggesting the significance of direct cell-to-cell contact as a mode of virus spread in vivo. Most of the epithelial cell lines infectable with EBV were negative for CD21 expression at the protein and mRNA levels. The majority of EBV-infected clones established from each cell line invariably expressed EBNA1, EBV-encoded small RNAs, rightward transcripts from theBamHI-A region of the virus genome, and latent membrane protein (LMP) 2A, but not the other EBNAs or LMP1. This restricted form of latent viral gene expression, which is a central issue for understanding epithelial oncogenesis by EBV, resembled that seen in EBV-associated gastric carcinoma and LMP1-negative nasopharyngeal carcinoma. The results indicate that direct infection of epithelial cells by EBV may occur naturally in vivo, and this could be mediated by an unidentified, epithelium-specific binding receptor for EBV. The EBV convertants are viewed, at least in terms of viral gene expression, as in vitro analogs of EBV-associated epithelial tumor cells, thus facilitating analysis of an oncogenic role(s) for EBV in epithelial cells.

Selective Ablation of Human T-Cell Lymphotropic Virus Type 1 p12I Reduces Viral Infectivity In Vivo

Blood ◽  
1998 ◽  
Vol 91 (12) ◽  
pp. 4701-4707 ◽  
Author(s):  
Nathaniel D. Collins ◽  
Garret C. Newbound ◽  
Björn Albrecht ◽  
Jennifer L. Beard ◽  
Lee Ratner ◽  
...  
Keyword(s):  
T Cell ◽  
Virus Type ◽  
Rabbit Model ◽  
Etiologic Agent ◽  
Peripheral Blood Mononuclear ◽  
Antigen Production ◽  
Human T Cell

Abstract Human T-cell lymphotropic virus type 1 (HTLV-1) is the etiologic agent of adult T-cell leukemia and HTLV-1-associated myelopathy. Novel, yet conserved RNA transcripts encoded from open reading frames (ORFs) I and II of the viral pX region are expressed both in vitro and in infected individuals. The ORF I mRNA encodes the protein p12I, which has been shown to localize to cellular endomembranes, cooperate with bovine papillomavirus E5 in transformation, as well as bind to the IL-2 receptor β and γ chains and the H+ vacuolar ATPase. It is unknown what role p12I plays in the viral life cycle. Using an infectious molecular clone of HTLV-1 (ACH) and a derivative clone, ACH.p12I, which fails to produce the p12Imessage, we investigated the importance of p12I in infected primary cells and in a rabbit model of the infection. ACH.p12I was infectious in vitro as shown by viral passage in culture and no qualitative or quantitative differences were noted between ACH and ACH.p12I in posttransfection viral antigen production. However, in contrast to ACH, ACH.p12I failed to establish persistent infection in vivo as indicated by reduced anti-HTLV-1 antibody responses, failure to demonstrate viral p19 antigen production in peripheral blood mononuclear cell (PBMC) cultures, and only transient detection of provirus by polymerase chain reaction in PBMC from ACH.p12I-inoculated rabbits. These results are the first to show the essential role of HTLV-1 p12I in the establishment of persistent viral infection in vivo and suggest potential new targets in antiviral strategies to prevent HTLV-1 infection.

scholarly journals Comparison of the Genetic Organization, Expression Strategies and Oncogenic Potential of HTLV-1 and HTLV-2

2012 ◽  
Vol 2012 ◽  
pp. 1-14 ◽  
Author(s):  
Francesca Rende ◽  
Ilaria Cavallari ◽  
Maria Grazia Romanelli ◽  
Erica Diani ◽  
Umberto Bertazzoni ◽  
...  
Keyword(s):  
T Cell ◽  
Leukemia Virus ◽  
Spastic Paraparesis ◽  
T Cell Leukemia ◽  
Cell Leukemia ◽  
Pathogenic Potential ◽  
Adult T Cell Leukemia ◽  
Human T Cell

Human T cell leukemia virus types 1 and 2 (HTLV-1 and HTLV-2) are genetically related complex retroviruses that are capable of immortalizing human T-cells in vitro and establish life-long persistent infections in vivo. In spite of these apparent similarities, HTLV-1 and HTLV-2 exhibit a significantly different pathogenic potential. HTLV-1 is recognized as the causative agent of adult T-cell leukemia/lymphoma (ATLL) and tropical spastic paraparesis/HTLV-1-associated myelopathy (TSP/HAM). In contrast, HTLV-2 has not been causally linked to human malignancy, although it may increase the risk of developing inflammatory neuropathies and infectious diseases. The present paper is focused on the studies aimed at defining the viral genetic determinants of the pathobiology of HTLV-1 and HTLV-2 through a comparison of the expression strategies and functional properties of the different gene products of the two viruses.

scholarly journals HTLV-1 Rex is required for viral spread and persistence in vivo but is dispensable for cellular immortalization in vitro

Blood ◽  
2003 ◽  
Vol 102 (12) ◽  
pp. 3963-3969 ◽  
Author(s):  
Jianxin Ye ◽  
Lee Silverman ◽  
Michael D. Lairmore ◽  
Patrick L. Green
Keyword(s):  
Gene Expression ◽  
Interleukin 2 ◽  
Viral Gene Expression ◽  
Viral Gene ◽  
Viral Oncoprotein ◽  
Cell Leukemia Virus Type ◽  
Viral Spread ◽  
Human T Cell

Abstract Human T-cell leukemia virus type 1 (HTLV-1) is associated with leukemia/lymphoma and neurologic disorders. Although the viral transcriptional activator Tax is the critical viral oncoprotein, Rex, which regulates the expression of the viral structural and enzymatic genes, is essential for efficient viral replication. Herein, we investigate the contribution of Rex in HTLV-1 immortalization of primary T cells in vitro and viral survival in an infectious rabbit animal model. A Rex-deficient HTLV-1 (HTLVRex-) was constructed and characterized for viral gene expression, protein production, and immortalization capacity. Cells transiently transfected with the HTLVRex- proviral clone produced low detectable levels of p19 Gag. 729HTLVRex- stable transfectants produced functional Tax, but undetectable levels of Rex or p19 Gag. Coculture of irradiated 729HTLVRex- cells with peripheral blood mononuclear cells (PBMCs) resulted in sustained interleukin-2 (IL-2)-dependent growth of primary T lymphocytes. These cells carried the HTLVRex- genome and expressed tax/rex mRNA but produced no detectable Rex or p19 Gag. Rabbits inoculated with irradiated 729HTLVRex- cells or 729HTLVRex- cells transiently transfected with a Rex cDNA expression plasmid failed to become persistently infected or mount a detectable antibody response to the viral gene products. Together, our results provide the first direct evidence that Rex and its function to modulate viral gene expression and virion production is not required for in vitro immortalization by HTLV-1. However, Rex is critical for efficient infection of cells and persistence in vivo.

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