HTLV-1 basic leucine zipper factor protects cells from oxidative stress by upregulating expression of Heme Oxygenase I

Adult T-cell Leukemia (ATL) is a lymphoproliferative disease of CD4+ T-cells infected with Human T-cell Leukemia Virus type I (HTLV-1). With the exception of allogeneic hematopoietic stem cell transplantation, there are no effective treatments to cure ATL, and ATL cells often acquire resistance to conventional chemotherapeutic agents. Accumulating evidence shows that development and maintenance of ATL requires key contributions from the viral protein, HTLV-1 basic leucine zipper factor (HBZ). In this study we found that HBZ activates expression of Heme Oxygenase 1 (HMOX-1), a component of the oxidative stress response that functions to detoxify free heme. Transcription of HMOX1 and other antioxidant genes is regulated by the small Mafs. These cellular basic leucine zipper (bZIP) factors control transcription by forming homo- or heterodimers among themselves or with other cellular bZIP factors that then bind Maf responsive elements (MAREs) in promoters or enhancers of antioxidant genes. Our data support a model in which HBZ activates HMOX1 transcription by forming heterodimers with the small Mafs that bind MAREs located in an upstream enhancer region. Consistent with this model, we found that HMOX-1 is upregulated in HTLV-1-transformed T-cell lines and confers these cells with resistance to heme-induced cytotoxicity. In this context, HBZ-mediated activation of HMOX-1 expression may contribute to resistance of ATL cells to certain chemotherapeutic agents. We also provide evidence that HBZ counteracts oxidative stress caused by two other HTLV-1-encoded proteins, Tax and p13. Tax induces oxidative stress as a byproduct of driving mitotic expansion of infected cells, and p13 is believed to induce oxidative stress to eliminate infected cells that have become transformed. Therefore, in this context, HBZ-mediated activation of HMOX-1 expression may facilitate transformation. Overall, this study characterizes a novel function of HBZ that may support the development and maintenance of ATL

The Human T-cell Leukemia Virus type I basic leucine zipper factor upregulates the expression of the antioxidant Heme Oxygenase I,

Adult T-cell Leukemia/Lymphoma (ATLL) is a resilient lymphoproliferative disease of CD4+ T-cells infected by the Human T-cell Leukemia Virus type I (HTLV-1), for which there are no effective treatments. Mounting evidence supports that the overexpression of antioxidants contributes to drug resistance in many types of cancer. One such antioxidant is the iron-recycling enzyme Heme Oxygenase (HMOX-1), which has been shown to enhance cancer cell survival upon exposure to stress-inducing agents. HMOX-1 expression is regulated by the small Maf AP1 proteins, which control transcription from promoter antioxidant response elements (AREs). A previous report, confirmed by our laboratory, shows that the HTLV-1 antisense-encoded basic leucine zipper factor, HBZ, interacts with small Mafs for recruitment to AREs in vitro. We questioned whether HBZ and small Mafs regulate the expression of antioxidants like HMOX-1 as a pro-survival strategy in ATLL cells. Our results show that HMOX-1 is overexpressed in ATLL cells in a manner dependent upon both HBZ and the small Mafs. These proteins were found to be present at an ARE in the promoter of HMOX-1 in vivo, and HBZ expression was observed to promote ARE transactivation in a small Maf-dependent manner. HMOX-1 is thought to be the main mediator of iron metabolism and functions in a cytoprotective capacity during oxidative stress. We observed that ATLL cells, as well as HBZ-expressing cells, exhibited resistance to iron-induced cytotoxicity, which was attenuated upon inhibition of HMOX-1 enzyme activity. Furthermore, HBZ expression was found to be important for maintaining ATLL cell redox state, as well as for maintaining cell viability in response to iron exposure. These findings support the possibility that HBZ and small Mafs may upregulate transcription at AREs to positively regulate some antioxidant response genes in ATLL cells, wherein these gene products may have cytoprotective effects in response to oxidative stress and may contribute to anti-cancer drug resistance.ECU Research and Creative Achievement Wee

Regulation of human T-cell leukemia virus type 1 antisense promoter by myocyte enhancer factor-2C in the context of adult T-cell leukemia and lymphoma

Adult T-cell leukemia and lymphoma (ATLL) is an intractable T-cell neoplasia caused by a retrovirus, namely human T-cell leukemia virus type 1 (HTLV-1). Patients suffering from ATLL present a poor prognosis and have a dearth of treatment options. In contrast to the sporadic expression of viral transactivator protein Tax present at the 5’ promoter region long terminal repeats (LTR), HTLV-1 bZIP gene (HBZ) is encoded by 3’LTR (the antisense promoter) and maintains its constant expression in ATLL cells and patients. The antisense promoter is associated with selective retroviral gene expression and has been an understudied phenomenon. Herein, we delineate the activity of transcription factor MEF (myocyte enhancer factor)-2 family members, which were found to be enriched at the 3'LTR and play an important role in the pathogenesis of ATLL. Of the four MEF isoforms (A to D), MEF-2A and 2C were highly overexpressed in a wide array of ATLL cell lines and in acute ATLL patients. The activity of MEF-2 isoforms were determined by knockdown experiments that led to decreased cell proliferation and regulated cell cycle progression. High enrichment of MEF-2C was observed at the 3'LTR along with cofactors Menin and JunD resulting in binding of MEF-2C to HBZ at this region. Chemical inhibition of MEF-2 proteins resulted in the cytotoxicity of ATLL cells in vitro and reduction of proviral load in a humanized mouse model. Taken together, this study provides a novel mechanism of 3’LTR regulation and establishes MEF-2 signaling a potential target for therapeutic intervention for ATLL

HTLV-1 basic leucine zipper factor protects cells from oxidative stress by upregulating expression of Heme Oxygenase I

Adult T-cell Leukemia (ATL) is a lymphoproliferative disease of CD4+ T-cells infected with Human T-cell Leukemia Virus type I (HTLV-1). With the exception of allogeneic hematopoietic stem cell transplantation, there are no effective treatments to cure ATL, and ATL cells often acquire resistance to conventional chemotherapeutic agents. Accumulating evidence shows that development and maintenance of ATL requires key contributions from the viral protein, HTLV-1 basic leucine zipper factor (HBZ). In this study we found that HBZ activates expression of Heme Oxygenase 1 (HMOX-1), a component of the oxidative stress response that functions to detoxify free heme. Transcription of HMOX1 and other antioxidant genes is regulated by the small Mafs. These cellular basic leucine zipper (bZIP) factors control transcription by forming homo- or heterodimers among themselves or with other cellular bZIP factors that then bind Maf responsive elements (MAREs) in promoters or enhancers of antioxidant genes. Our data support a model in which HBZ activates HMOX1 transcription by forming heterodimers with the small Mafs that bind MAREs located in an upstream enhancer region. Consistent with this model, we found that HMOX-1 is upregulated in HTLV-1-transformed T-cell lines and confers these cells with resistance to heme-induced cytotoxicity. In this context, HBZ-mediated activation of HMOX-1 expression may contribute to resistance of ATL cells to certain chemotherapeutic agents. We also provide evidence that HBZ counteracts oxidative stress caused by two other HTLV-1-encoded proteins, Tax and p13. Tax induces oxidative stress as a byproduct of driving mitotic expansion of infected cells, and p13 is believed to induce oxidative stress to eliminate infected cells that have become transformed. Therefore, in this context, HBZ-mediated activation of HMOX-1 expression may facilitate transformation. Overall, this study characterizes a novel function of HBZ that may support the development and maintenance of ATL

The Human T-cell Leukemia Virus type I basic leucine zipper factor upregulates the expression of the antioxidant Heme Oxygenase I,

Adult T-cell Leukemia/Lymphoma (ATLL) is a resilient lymphoproliferative disease of CD4+ T-cells infected by the Human T-cell Leukemia Virus type I (HTLV-1), for which there are no effective treatments. Mounting evidence supports that the overexpression of antioxidants contributes to drug resistance in many types of cancer. One such antioxidant is the iron-recycling enzyme Heme Oxygenase (HMOX-1), which has been shown to enhance cancer cell survival upon exposure to stress-inducing agents. HMOX-1 expression is regulated by the small Maf AP1 proteins, which control transcription from promoter antioxidant response elements (AREs). A previous report, confirmed by our laboratory, shows that the HTLV-1 antisense-encoded basic leucine zipper factor, HBZ, interacts with small Mafs for recruitment to AREs in vitro. We questioned whether HBZ and small Mafs regulate the expression of antioxidants like HMOX-1 as a pro-survival strategy in ATLL cells. Our results show that HMOX-1 is overexpressed in ATLL cells in a manner dependent upon both HBZ and the small Mafs. These proteins were found to be present at an ARE in the promoter of HMOX-1 in vivo, and HBZ expression was observed to promote ARE transactivation in a small Maf-dependent manner. HMOX-1 is thought to be the main mediator of iron metabolism and functions in a cytoprotective capacity during oxidative stress. We observed that ATLL cells, as well as HBZ-expressing cells, exhibited resistance to iron-induced cytotoxicity, which was attenuated upon inhibition of HMOX-1 enzyme activity. Furthermore, HBZ expression was found to be important for maintaining ATLL cell redox state, as well as for maintaining cell viability in response to iron exposure. These findings support the possibility that HBZ and small Mafs may upregulate transcription at AREs to positively regulate some antioxidant response genes in ATLL cells, wherein these gene products may have cytoprotective effects in response to oxidative stress and may contribute to anti-cancer drug resistance

HBZ upregulates myoferlin expression to facilitate HTLV-1 infection.

The complex retrovirus, human T-cell leukemia virus type 1 (HTLV-1), primarily infects CD4+ T-cells in vivo. Infectious spread within this cell population requires direct contact between virally-infected and target cells. The HTLV-1 accessory protein, HBZ, was recently shown to enhance HTLV-1 infection by activating intracellular adhesion molecule 1 (ICAM-1) expression, which promotes binding of infected cells to target cells and facilitates formation of a virological synapse. In this study we show that HBZ additionally enhances HTLV-1 infection by activating expression of myoferlin (MyoF), which functions in membrane fusion and repair and vesicle transport. Results from ChIP assays and quantitative reverse transcriptase PCR indicate that HBZ forms a complex with c-Jun or JunB at two enhancer sites within the MYOF gene and activates transcription through recruitment of the coactivator p300/CBP. In HTLV-1-infected T-cells, specific inhibition of MyoF using the drug, WJ460, or shRNA-mediated knockdown of MyoF reduced infection efficiency. This effect was associated with a decrease in cell adhesion and an intracellular reduction in the abundance of HTLV-1 envelope (Env) surface unit (SU) and transmembrane domain (TM). Lysosomal protease inhibitors partially restored SU levels in WJ460-treated cells, and SU localization to LAMP-2 sites was increased by MyoF knockdown, suggesting that MyoF restricts SU trafficking to lysosomes for degradation. Consistent with these effects, less SU was associated with cell-free virus particles. Together, these data suggest that MyoF contributes to HTLV-1 infection through modulation of Env trafficking and cell adhesion

Interventions to improve system-level coproduction in the Cystic Fibrosis Learning Network

Background Coproduction is defined as patients and clinicians collaborating equally and reciprocally in healthcare and is a crucial concept for quality improvement (QI) of health services. Learning Health Networks (LHNs) provide insights to integrate coproduction with QI efforts from programmes from various health systems.Objective We describe interventions to develop and maintain patient and family partner (PFP) coproduction, measured by PFP-reported and programme-reported scales. We aim to increase percentage of programmes with PFPs reporting active QI work within their programme, while maintaining satisfaction in PFP-clinician relationships.Methods Conducted in the Cystic Fibrosis Learning Network (CFLN), an LHN comprising over 30 cystic fibrosis (CF) programmes, people with CF, caregivers and clinicians cocreated interventions in readiness awareness, inclusive PFP recruitment, onboarding process, partnership development and leadership opportunities. Interventions were adapted by CFLN programmes and summarised in a change package for existing programmes and the orientation of new ones. We collected monthly assessments for PFP and programme perceptions of coproduction and PFP self-rated competency of QI skills and satisfaction with programme QI efforts. We used control charts to analyse coproduction scales and run charts for PFP self-ratings.Results Between 2018 and 2022, the CFLN expanded to 34 programmes with 52% having ≥1 PFP reporting active QI participation. Clinicians from 76% of programmes reported PFPs were actively participating or leading QI efforts. PFPs reported increased QI skills competency (17%–32%) and consistently high satisfaction and feeling valued in their work.Conclusions Implementing system-level programmatic strategies to engage and sustain partnerships between clinicians and patients and families with CF improved perceptions of coproduction to conduct QI work. Key adaptable strategies for programmes included onboarding and QI training, supporting multiple PFPs simultaneously and developing financial recognition processes. Interventions may be applicable in other health conditions beyond CF seeking to foster the practice of coproduction