RESUMEN

Stem cell therapies for degenerative cartilage disease are limited by an incomplete understanding of hyaline cartilage formation and maintenance. Human bone marrow stromal cells/skeletal stem cells (hBMSCs/SSCs) produce stable hyaline cartilage when attached to hyaluronic acid-coated fibrin microbeads (HyA-FMBs), yet the mechanism remains unclear. In vitro, hBMSC/SSC/HyA-FMB organoids exhibited reduced BMP signaling early in chondrogenic differentiation, followed by restoration of BMP signaling in chondrogenic IGFBP5 + /MGP + cells. Subsequently, human-induced pluripotent stem cell (hiPSC)-derived sclerotome cells were established (BMP inhibition) and then treated with transforming growth factor ß (TGF-ß) -/+ BMP2 and growth differentiation factor 5 (GDF5) (BMP signaling activation). TGF-ß alone elicited a weak chondrogenic response, but TGF-ß/BMP2/GDF5 led to delamination of SOX9 + aggregates (chondrospheroids) with high expression of COL2A1, ACAN, and PRG4 and minimal expression of COL10A1 and ALP in vitro. While transplanted hBMSCs/SSCs/HyA-FMBs did not heal articular cartilage defects in immunocompromised rodents, chondrospheroid-derived cells/HyA-FMBs formed non-hypertrophic cartilage that persisted until at least 5 months in vivo.

RESUMEN

The mechanisms by which bone marrow stromal cells (BMSCs) maintain multilineage potency in vitro remain elusive. To identify the transcriptional regulatory circuits that contribute to BMSC multipotency, we performed paired single-nucleus multiomics of the expansion of freshly isolated BMSCs and of BMSCs undergoing tri-lineage differentiation. By computationally reconstructing the regulatory programs associated with initial stages of differentiation and early expansion, we identified the TEAD family of transcription factors, which is inhibited by Hippo signaling, as highly active in the BMSC in vitro multipotent state. Pharmacological inhibition of TEAD enhanced BMSC osteogenic and adipogenic differentiation, whereas its activation maintained BMSCs in an undifferentiated state, supporting a model whereby isolation of BMSCs coincides with a TEAD-controlled transcriptional state linked to multipotency. Our study highlights the Hippo pathway as a pivotal regulator of BMSC multipotency, and our regulatory network inferences are a reservoir of testable hypotheses that link transcription factors and their regulons to specific aspects of BMSC behavior.

RESUMEN

Introduction: Erythropoietin (EPO), produced in the kidney in a hypoxia responsive manner, is required for red blood cell production. In non-erythroid tissue, EPO increases endothelial cell production of nitric oxide (NO) and endothelial nitric oxide synthase (eNOS) that regulates vascular tone to improve oxygen delivery. This contributes to EPO cardioprotective activity in mouse models. Nitric oxide treatment in mice shifts hematopoiesis toward the erythroid lineage, increases red blood cell production and total hemoglobin. In erythroid cells, nitric oxide can also be generated by hydroxyurea metabolism that may contribute to hydroxyurea induction of fetal hemoglobin. We find that during erythroid differentiation, EPO induces neuronal nitric oxide synthase (nNOS) and that neuronal nitric oxide synthase is required for normal erythropoietic response. Methods: Wild type (WT) mice and mice with targeted deletion of nNOS (nNOS-/-) and eNOS (eNOS-/-) were assessed for EPO stimulated erythropoietic response. Bone marrow erythropoietic activity was assessed in culture by EPO dependent erythroid colony assay and in vivo by bone marrow transplantation into recipient WT mice. Contribution of nNOS to EPO stimulated cell proliferation was assessed in EPO dependent erythroid cells and in primary human erythroid progenitor cell cultures. Results: EPO treatment increased hematocrit similarly in WT and eNOS-/- mice and showed a lower increase in hematocrit nNOS-/- mice. Erythroid colony assays from bone marrow cells were comparable in number from wild type, eNOS-/- and nNOS-/- mice at low EPO concentration. Colony number increased at high EPO concentration is seen only in cultures from bone marrow cells of wild type and eNOS-/- mice but not from nNOS-/- mice. Colony size with high EPO treatment also exhibited a marked increase in erythroid cultures from wild type and eNOS-/- mice but not from nNOS-/- mice. Bone marrow transplant from nNOS-/- mice into immunodeficient mice showed engraftment at comparable levels to WT bone marrow transplant. With EPO treatment, the increase in hematocrit was blunted in recipient mice that received with nNOS-/- donor marrow compared with recipient mice that received WT donor marrow. In erythroid cell cultures, addition of nNOS inhibitor resulted in decreased EPO dependent proliferation mediated in part by decreased EPO receptor expression, and decreased proliferation of hemin induced differentiating erythroid cells. Discussion: EPO treatment in mice and in corresponding cultures of bone marrow erythropoiesis suggest an intrinsic defect in erythropoietic response of nNOS-/- mice to high EPO stimulation. Transplantation of bone marrow from donor WT or nNOS-/- mice into recipient WT mice showed that EPO treatment post-transplant recapitulated the response of donor mice. Culture studies suggest nNOS regulation of EPO dependent erythroid cell proliferation, expression of EPO receptor and cell cycle associated genes, and AKT activation. These data provide evidence that nitric oxide modulates EPO dose dependent erythropoietic response.

RESUMEN

In this case report, we focus on Muenke syndrome (MS), a disease caused by the p.Pro250Arg variant in fibroblast growth factor receptor 3 (FGFR3) and characterized by uni- or bilateral coronal suture synostosis, macrocephaly without craniosynostosis, dysmorphic craniofacial features, and dental malocclusion. The clinical findings of MS are further complicated by variable expression of phenotypic traits and incomplete penetrance. As such, unraveling the mechanisms behind MS will require a comprehensive and systematic way of phenotyping patients to precisely identify the impact of the mutation variant on craniofacial development. To establish this framework, we quantitatively delineated the craniofacial phenotype of an individual with MS and compared this to his unaffected parents using three-dimensional cephalometric analysis of cone beam computed tomography scans and geometric morphometric analysis, in addition to an extensive clinical evaluation. Secondly, given the utility of human induced pluripotent stem cells (hiPSCs) as a patient-specific investigative tool, we also generated the first hiPSCs derived from a family trio, the proband and his unaffected parents as controls, with detailed characterization of all cell lines. This report provides a starting point for evaluating the mechanistic underpinning of the craniofacial development in MS with the goal of linking specific clinical manifestations to molecular insights gained from hiPSC-based disease modeling.

RESUMEN

Human pluripotent stem cells (hPSCs) can provide a platform to model bone organogenesis and disease. To reflect the developmental process of the human skeleton, hPSC differentiation methods should include osteogenic progenitors (OPs) arising from three distinct embryonic lineages: the paraxial mesoderm, lateral plate mesoderm, and neural crest. Although OP differentiation protocols have been developed, the lineage from which they are derived, as well as characterization of their genetic and molecular differences, has not been well reported. Therefore, to generate lineage-specific OPs from human embryonic stem cells and human induced pluripotent stem cells, we employed stepwise differentiation of paraxial mesoderm-like cells, lateral plate mesoderm-like cells, and neural crest-like cells toward their respective OP subpopulation. Successful differentiation, confirmed through gene expression and in vivo assays, permitted the identification of transcriptomic signatures of all three cell populations. We also report, for the first time, high FGF1 levels in neural crest-derived OPs-a notable finding given the critical role of fibroblast growth factors (FGFs) in osteogenesis and mineral homeostasis. Our results indicate that FGF1 influences RUNX2 levels, with concomitant changes in ERK1/2 signaling. Overall, our study further validates hPSCs' power to model bone development and disease and reveals new, potentially important pathways influencing these processes.

Asunto(s)

Diferenciación Celular , Linaje de la Célula , Subunidad alfa 1 del Factor de Unión al Sitio Principal/metabolismo , Factor 1 de Crecimiento de Fibroblastos/metabolismo , Cresta Neural/citología , Osteogénesis , Células Madre Pluripotentes/citología , Células Madre Pluripotentes/metabolismo , Animales , Humanos , Sistema de Señalización de MAP Quinasas , Masculino , Ratones , Análisis de Componente Principal , Transcriptoma/genética

RESUMEN

Chronic granulomatous disease (CGD) is an immune deficiency characterized by defects in the production of microbicidal reactive oxygen species (ROS) by the phagocytic oxidase (phox) enzyme complex in neutrophils. We have previously described targeted gene editing strategies using zinc finger nucleases (ZFNs), transcription activator-like effector nucleases (TALENs), or clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 nucleases for gene targeting with homology-directed repair in CGD patient stem cells to achieve functional restoration of expression of phox genes and NADPH oxidase activity in differentiated neutrophils. In this chapter, we describe detailed protocols for targeted gene editing in human-induced pluripotent stem cells and hematopoietic stem cells and for subsequent differentiation of these stem cells into mature neutrophils, as well as assays to characterize neutrophil identity and function including flow cytometry analysis of neutrophil surface markers, intracellular staining for phox proteins, and analysis of ROS generation.

Asunto(s)

Edición Génica , Enfermedad Granulomatosa Crónica/genética , Sistemas CRISPR-Cas , Diferenciación Celular/genética , Diferenciación Celular/inmunología , Línea Celular , Células Cultivadas , Clonación Molecular , Edición Génica/métodos , Orden Génico , Marcación de Gen , Vectores Genéticos , Enfermedad Granulomatosa Crónica/metabolismo , Células Madre Hematopoyéticas/citología , Células Madre Hematopoyéticas/metabolismo , Humanos , Células Madre Pluripotentes Inducidas/citología , Células Madre Pluripotentes Inducidas/metabolismo , Neutrófilos/citología , Neutrófilos/inmunología , Neutrófilos/metabolismo , ARN Guía de Kinetoplastida , Especies Reactivas de Oxígeno/metabolismo

RESUMEN

X-linked chronic granulomatous disease (X-CGD) is an immune deficiency resulting from defective production of microbicidal reactive oxygen species (ROS) by phagocytes. Causative mutations occur throughout the CYBB gene, resulting in absent or defective gp91phox protein expression. To correct CYBB exon 5 mutations while retaining normal gene regulation, we utilized TALEN or Cas9 for exon 5 replacement in induced pluripotent stem cells (iPSCs) from patients, which restored gp91phox expression and ROS production in iPSC-derived granulocytes. Alternate approaches for correcting the majority of X-CGD mutations were assessed, involving TALEN- or Cas9-mediated insertion of CYBB minigenes at exon 1 or 2 of the CYBB locus. Targeted insertion of an exon 1-13 minigene into CYBB exon 1 resulted in no detectable gp91phox expression or ROS activity in iPSC-derived granulocytes. In contrast, targeted insertion of an exon 2-13 minigene into exon 2 restored both gp91phox and ROS activity. This demonstrates the efficacy of two correction strategies: seamless repair of specific CYBB mutations by exon replacement or targeted insertion of an exon 2-13 minigene to CYBB exon 2 while retaining exon/intron 1. Furthermore, it highlights a key issue for targeted insertion strategies for expression from an endogenous promoter: retention of intronic elements can be necessary for expression.

Asunto(s)

Regulación de la Expresión Génica , Enfermedad Granulomatosa Crónica/genética , Enfermedad Granulomatosa Crónica/metabolismo , Células Madre Pluripotentes Inducidas/metabolismo , Intrones , Glicoproteínas de Membrana/genética , NADPH Oxidasas/genética , Reparación del Gen Blanco , Diferenciación Celular/genética , Línea Celular , Exones , Edición Génica , Orden Génico , Marcación de Gen , Técnicas de Transferencia de Gen , Sitios Genéticos , Vectores Genéticos , Granulocitos/citología , Granulocitos/metabolismo , Enfermedad Granulomatosa Crónica/terapia , Humanos , Mutación , NADPH Oxidasa 2 , Transgenes

RESUMEN

Nonhuman primate (NHP) induced pluripotent stem cells (iPSCs) offer the opportunity to investigate the safety, feasibility, and efficacy of proposed iPSC-derived cellular delivery in clinically relevant in vivo models. However, there is need for stable, robust, and safe labeling methods for NHP iPSCs and their differentiated lineages to study survival, proliferation, tissue integration, and biodistribution following transplantation. Here we investigate the utility of the adeno-associated virus integration site 1 (AAVS1) as a safe harbor for the addition of transgenes in our rhesus macaque iPSC (RhiPSC) model. A clinically relevant marker gene, human truncated CD19 (hΔCD19), or GFP was inserted into the AAVS1 site in RhiPSCs using the CRISPR/Cas9 system. Genetically modified RhiPSCs maintained normal karyotype and pluripotency, and these clones were able to further differentiate into all three germ layers in vitro and in vivo. In contrast to transgene delivery using randomly integrating viral vectors, AAVS1 targeting allowed stable transgene expression following differentiation. Off-target mutations were observed in some edited clones, highlighting the importance of careful characterization of these cells prior to downstream applications. Genetically marked RhiPSCs will be useful to further advance clinically relevant models for iPSC-based cell therapies.

Asunto(s)

Diferenciación Celular , Edición Génica , Expresión Génica , Estratos Germinativos/metabolismo , Células Madre Pluripotentes Inducidas/citología , Células Madre Pluripotentes Inducidas/metabolismo , Transgenes , Animales , Biomarcadores , Sistemas CRISPR-Cas , Reprogramación Celular , Marcación de Gen , Sitios Genéticos , Estratos Germinativos/embriología , Macaca mulatta , Especificidad de Órganos/genética

RESUMEN

Pseudogenes are duplicated genes with mutations rendering them nonfunctional. For single-gene disorders with homologous pseudogenes, the pseudogene might be a target for genetic correction. Autosomal-recessive p47phox-deficient chronic granulomatous disease (p47-CGD) is a life-threatening immune deficiency caused by mutations in NCF1, a gene with 2 pseudogenes, NCF1B and NCF1C. The most common NCF1 mutation, a GT deletion (ΔGT) at the start of exon 2 (>90% of alleles), is constitutive to NCF1B and NCF1C. NCF1 ΔGT results in premature termination, undetectable protein expression, and defective production of antimicrobial superoxide in neutrophils. We examined strategies for p47-CGD gene correction using engineered zinc-finger nucleases targeting the exon 2 ΔGT in induced pluripotent stem cells or CD34+ hematopoietic stem cells derived from p47-CGD patients. Correction of ΔGT in NCF1 pseudogenes restores oxidase function in p47-CGD, providing the first demonstration that targeted restoration of pseudogene function can correct a monogenic disorder.

RESUMEN

In vitro generation of mature neutrophils from human induced pluripotent stem cells (iPSCs) requires hematopoietic progenitor development followed by myeloid differentiation. The purpose of our studies was to extensively characterize this process, focusing on the critical window of development between hemogenic endothelium, hematopoietic stem/progenitor cells (HSPCs), and myeloid commitment, to identify associated regulators and markers that might enable the stem cell field to improve the efficiency and efficacy of iPSC hematopoiesis. We utilized a four-stage differentiation protocol involving: embryoid body (EB) formation (stage-1); EB culture with hematopoietic cytokines (stage-2); HSPC expansion (stage-3); and neutrophil maturation (stage-4). CD34(+) CD45(-) putative hemogenic endothelial cells were observed in stage-3 cultures, and expressed VEGFR-2/Flk-1/KDR and VE-cadherin endothelial markers, GATA-2, AML1/RUNX1, and SCL/TAL1 transcription factors, and endothelial/HSPC-associated microRNAs miR-24, miR-125a-3p, miR-126/126*, and miR-155. Upon further culture, CD34(+) CD45(-) cells generated CD34(+) CD45(+) HSPCs that produced hematopoietic CFUs. Mid-stage-3 CD34(+) CD45(+) HSPCs exhibited increased expression of GATA-2, AML1/RUNX1, SCL/TAL1, C/EBPα, and PU.1 transcription factors, but exhibited decreased expression of HSPC-associated microRNAs, and failed to engraft in immune-deficient mice. Mid-stage-3 CD34(-) CD45(+) cells maintained PU.1 expression and exhibited increased expression of hematopoiesis-associated miR-142-3p/5p and a trend towards increased miR-223 expression, indicating myeloid commitment. By late Stage-4, increased CD15, CD16b, and C/EBPɛ expression were observed, with 25%-65% of cells exhibiting morphology and functions of mature neutrophils. These studies demonstrate that hematopoiesis and neutrophil differentiation from human iPSCs recapitulates many features of embryonic hematopoiesis and neutrophil production in marrow, but reveals unexpected molecular signatures that may serve as a guide for enhancing iPSC hematopoiesis. Stem Cells 2016;34:1513-1526.

Asunto(s)

Diferenciación Celular , Hematopoyesis , Células Madre Pluripotentes Inducidas/citología , Células Madre Pluripotentes Inducidas/metabolismo , Neutrófilos/citología , Antígenos de Superficie/metabolismo , Ensayo de Unidades Formadoras de Colonias , Regulación de la Expresión Génica , Humanos , Cinética , MicroARNs/genética , MicroARNs/metabolismo , Factores de Transcripción/metabolismo

RESUMEN

There are five genetic forms of chronic granulomatous disease (CGD), resulting from mutations in any of five subunits of phagocyte oxidase, an enzyme complex in neutrophils, monocytes, and macrophages that produces microbicidal reactive oxygen species. We generated induced pluripotent stem cells (iPSCs) from peripheral blood CD34(+) hematopoietic stem cells of patients with each of five CGD genotypes. We used zinc finger nuclease (ZFN) targeting the AAVS1 safe harbor site together with CGD genotype-specific minigene plasmids with flanking AAVS1 sequence to target correction of iPSC representing each form of CGD. We achieved targeted insertion with constitutive expression of desired oxidase subunit in 70-80% of selected iPSC clones. Neutrophils and macrophages differentiated from corrected CGD iPSCs demonstrated restored oxidase activity and antimicrobial function against CGD bacterial pathogens Staphylococcus aureus and Granulibacter bethesdensis. Using a standard platform that combines iPSC generation from peripheral blood CD34(+) cells and ZFN mediated AAVS1 safe harbor minigene targeting, we demonstrate efficient generation of genetically corrected iPSCs using an identical approach for all five genetic forms of CGD. This safe harbor minigene targeting platform is broadly applicable to a wide range of inherited single gene metabolic disorders.

Asunto(s)

Dependovirus/genética , Enfermedad Granulomatosa Crónica/terapia , Células Madre Hematopoyéticas/metabolismo , Células Madre Pluripotentes Inducidas/metabolismo , NADPH Oxidasas/genética , Acetobacteraceae/crecimiento & desarrollo , Acetobacteraceae/inmunología , Diferenciación Celular , Expresión Génica , Terapia Genética/métodos , Vectores Genéticos , Genotipo , Enfermedad Granulomatosa Crónica/genética , Enfermedad Granulomatosa Crónica/metabolismo , Enfermedad Granulomatosa Crónica/patología , Células Madre Hematopoyéticas/patología , Humanos , Células Madre Pluripotentes Inducidas/patología , Macrófagos/inmunología , Macrófagos/microbiología , Macrófagos/patología , NADPH Oxidasas/metabolismo , Neutrófilos/inmunología , Neutrófilos/microbiología , Neutrófilos/patología , Staphylococcus aureus/crecimiento & desarrollo , Staphylococcus aureus/inmunología , Dedos de Zinc/genética

RESUMEN

Induced pluripotent stem cells (iPSCs) are pluripotent stem cells established from somatic cells. The capability of iPSCs to differentiate into any mature cell lineage under the appropriate conditions allows for modeling of cell processes as well as disease states. Here, we describe an in vitro method for generating functional mature neutrophils from human iPSCs. We also describe assays for testing these differentiated cells for neutrophil characteristics and functions by morphology, cell surface markers, production of reactive oxygen species, microbial killing, and mobilization of neutrophils to an inflammatory site in an in vivo immunodeficient mouse infusion model.

Asunto(s)

Diferenciación Celular/fisiología , Células Madre Pluripotentes Inducidas/citología , Neutrófilos/citología , Neutrófilos/fisiología , Animales , Técnicas de Cultivo de Célula , Movimiento Celular , Humanos , Inmunofenotipificación/métodos , Ratones , Especies Reactivas de Oxígeno/metabolismo

RESUMEN

A variety of somatic cells can be reprogrammed to induced pluripotent stem cells (iPSCs), but CD34(+) hematopoietic stem cells (HSCs) present in nonmobilized peripheral blood (PB) would be a convenient target. We report a method for deriving iPSC from PB HSCs using immunobead purification and 2- to 4-day culture to enrich CD34(+) HSCs to 80% ± 9%, followed by reprogramming with loxP-flanked polycistronic (human Oct4, Klf4, Sox2, and c-Myc) STEMCCA-loxP lentivector, or with Sendai vectors. Colonies arising with STEMCCA-loxP were invariably TRA-1-60(+), yielding 5.3 ± 2.8 iPSC colonies per 20 mL PB (n = 17), where most colonies had single-copy STEMCCA-loxP easily excised by transient Cre expression. Colonies arising with Sendai were variably reprogrammed (10%-80% TRA-1-60(+)), with variable yield (6 to >500 TRA-1-60(+) iPSC colonies per 10 mL blood; n = 6). Resultant iPSC clones expressed pluripotent cell markers and generated teratomas. Genomic methylation patterns of STEMCCA-loxP-reprogrammed clones closely matched embryonic stem cells. Furthermore, we showed that iPSCs are derived from the nonmobilized CD34(+) HSCs enriched from PB rather than from any lymphocyte or monocyte contaminants because they lack somatic rearrangements typical of T or B lymphocytes and because purified CD14(+) monocytes do not yield iPSC colonies under these reprogramming conditions.

Asunto(s)

Linaje de la Célula/genética , Reprogramación Celular/genética , Células Madre Pluripotentes Inducidas/citología , Células Madre Pluripotentes Inducidas/fisiología , Transgenes/genética , Antígenos CD34/metabolismo , Secuencia de Bases , Técnicas de Cultivo de Célula/métodos , Línea Celular , Separación Celular/métodos , Dermatoglifia del ADN , Células Madre Embrionarias/citología , Células Madre Embrionarias/fisiología , Fibroblastos/citología , Fibroblastos/fisiología , Reordenamiento Génico de Linfocito B/genética , Reordenamiento Génico de Linfocito T/genética , Estudio de Asociación del Genoma Completo , Humanos , Síndromes de Inmunodeficiencia/patología , Integrasas/genética , Factor 4 Similar a Kruppel , Lentivirus/genética , Linfocitos/citología , Linfocitos/fisiología , Datos de Secuencia Molecular , Monocitos/citología , Monocitos/fisiología , Virus Sendai/genética , Teratoma/patología , Transducción Genética/métodos

RESUMEN

Infection by the human T-cell leukemia virus type 1 (HTLV-1) is thought to cause dysregulated T-cell proliferation, which in turn leads to adult T-cell leukemia/lymphoma. Early cellular changes after HTLV-1 infection have been difficult to study due to the poorly infectious nature of HTLV-1 and the need for cell-to-cell contact for HTLV-1 transmission. Using a series of reporter systems, we show that HeLa cells cease proliferation within one or two division cycles after infection by HTLV-1 or transduction of the HTLV-1 tax gene. HTLV-1-infected HeLa cells, like their tax-transduced counterparts, expressed high levels of p21(CIP1/WAF1) and p27(KIP1), developed mitotic abnormalities, and became arrested in G(1) in senescence. In contrast, cells of a human osteosarcoma lineage (HOS) continued to divide after HTLV-1 infection or Tax expression, albeit at a reduced growth rate and with mitotic aberrations. Unique to HOS cells is the dramatic reduction of p21(CIP1/WAF1) and p27(KIP1) expression, which is in part associated with the constitutive activation of the phosphatidylinositol-3-kinase (PI3K)-protein kinase B (Akt) pathway. The loss of p21(CIP1/WAF1) and p27(KIP1) in HOS cells apparently allows HTLV-1- and Tax-induced G(1) arrest to be bypassed. Finally, HTLV-1 infection and Tax expression also cause human SupT1 T cells to arrest in the G(1) phase of the cell cycle. These results suggest that productive HTLV-1 infection ordinarily leads to Tax-mediated G(1) arrest. However, T cells containing somatic mutations that inactivate p21(CIP1/WAF1) and p27(KIP1) may continue to proliferate after HTLV-1 infection and Tax expression. These infected cells can expand clonally, accumulate additional chromosomal abnormalities, and progress to cancer.

Asunto(s)

Ciclo Celular/fisiología , Fase G1/fisiología , Virus Linfotrópico T Tipo 1 Humano/fisiología , Línea Celular , Técnicas de Cocultivo , Infecciones por HTLV-I/virología , Células HeLa , Humanos , Riñón/citología

RESUMEN

HTLV-1 Tax is a potent activator of viral transcription and NF-kappaB. Recent data indicate that Tax activates the anaphase promoting complex/cyclosome (APC/C) ahead of schedule, causing premature degradation of cyclin A, cyclin B1, securin, and Skp2. Premature loss of these mitotic regulators is accompanied by mitotic aberrations and leads to rapid senescence and cell cycle arrest in HeLa and S. cerevisiae cells. Tax-induced rapid senescence (tax-IRS) of HeLa cells is mediated primarily by a dramatic stabilization of p27KIP and is also accompanied by a great surge in the level of p21CIP1mRNA and protein. Deficiencies in p27KIP prevent Tax-IRS. A collection of tax point mutants that permit normal growth of S. cerevisiae have been isolated. Like wild-type tax, many of them (C23W, A108T, L159F, and L235F) transactivate both the HTLV-LTR and the NF-kappaB reporters. One of them, V19M, preferentially activates NF-kappaB, but is attenuated for LTR activation. None of the mutants significantly elevated the levels of p21CIP1and p27KIP1, indicating that the dramatic surge in p21CIP1/WAF1and p27KIP 1induced by Tax is brought about by a mechanism distinct from NF-kappaB or LTR activation. Importantly, the ability of these mutants to activate APC/C is attenuated or abrogated. These data indicate that Tax-induced rapid senescence is causally associated with APC/C activation.

Asunto(s)

Fase G1 , Genes pX , Virus Linfotrópico T Tipo 1 Humano/patogenicidad , Mutación Puntual , Complejos de Ubiquitina-Proteína Ligasa/metabolismo , Sustitución de Aminoácidos , Ciclosoma-Complejo Promotor de la Anafase , Senescencia Celular , Inhibidor p21 de las Quinasas Dependientes de la Ciclina/biosíntesis , Inhibidor p27 de las Quinasas Dependientes de la Ciclina , Células HeLa , Virus Linfotrópico T Tipo 1 Humano/genética , Humanos , Péptidos y Proteínas de Señalización Intracelular/metabolismo , FN-kappa B/biosíntesis , ARN Viral/biosíntesis , Saccharomyces cerevisiae/citología , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/crecimiento & desarrollo , Secuencias Repetidas Terminales , Activación Transcripcional

RESUMEN

The switching on-and-off of I-kappaB kinase (IKK) and NF-kappaB occurs rapidly after signaling. How activated IKK becomes down-regulated is not well understood. Here we show that following tumor necrosis factor-alpha stimulation, protein phosphatase 2A (PP2A) association with IKK is increased. A heptad repeat in IKKgamma, helix 2 (HLX2), mediates PP2A recruitment. Two other heptad repeats downstream of HLX2, termed coiled-coil region 2 (CCR2) and leucine zipper (LZ), bind HLX2 and negatively regulate HLX2 interaction with PP2A. HTLV-1 transactivator Tax also binds HLX2, and this interaction is enhanced by CCR2 but reduced by LZ. In the presence of Tax, PP2A-IKKgamma binding is greatly strengthened. Interestingly, peptides spanning CCR2 and/or LZ disrupt IKKgamma-Tax and IKKgamma-PP2A interactions and potently inhibit NF-kappaB activation by Tax and tumor necrosis factor-alpha. We propose that when IKK is resting, HLX2, CCR2, and LZ form a helical bundle in which HLX2 is sequestered. The HLX2-CCR2-LZ bundle becomes unfolded by signal-induced modifications of IKKgamma or after Tax binding. In this conformation, IKK becomes activated. IKKgamma then recruits PP2A via the exposed HLX2 domain for rapid down-regulation of IKK. Tax-PP2A interaction, however, renders PP2A inactive, thus maintaining Tax-PP2A-IKK in an active state. Finally, CCR2 and LZ possibly inhibit IKK activation by stabilizing the HLX2-CCR2-LZ bundle.

Asunto(s)

Regulación Viral de la Expresión Génica , Productos del Gen tax/metabolismo , Quinasa I-kappa B/metabolismo , FN-kappa B/metabolismo , Fosfoproteínas Fosfatasas/metabolismo , Animales , Línea Celular , Línea Celular Tumoral , Glutatión Transferasa/metabolismo , Humanos , Ratones , Modelos Genéticos , Unión Proteica , Proteína Fosfatasa 2 , Estructura Terciaria de Proteína , Técnicas del Sistema de Dos Híbridos

RESUMEN

Potent activation of human T-cell leukemia virus type 1 (HTLV-1) gene expression is mediated by the virus-encoded transactivator protein Tax and three imperfect 21-bp repeats in the viral long terminal repeats. Each 21-bp repeat contains a cAMP-responsive-element core flanked by 5' G-rich and 3' C-rich sequences. Tax alone does not bind DNA. Rather, it interacts with basic domain-leucine zipper transcription factors CREB and ATF-1 to form ternary complexes with the 21-bp repeats. In the context of the ternary complexes, Tax contacts the G/C-rich sequences and recruits transcriptional coactivators CREB-binding protein (CBP)/p300 to effect potent transcriptional activation. Using an easily transduced and chromosomally integrated reporter system derived from a self-inactivating lentivirus vector, we showed in a BRG1- and BRM1-deficient adrenal carcinoma cell line, SW-13, that Tax- and 21-bp repeat-mediated transactivation does not require BRG1 or BRM1 and is not enhanced by BRG1. With a similar reporter system, we further demonstrated that Tax- and tumor necrosis factor alpha-induced NF-kappaB activation occurs readily in SW-13 cells in the absence of BRG1 and BRM1. These results suggest that the assembly of stable multiprotein complexes containing Tax, CREB/ATF-1, and CBP/p300 on the 21-bp repeats is the principal mechanism employed by Tax to preclude nucleosome formation at the HTLV-1 enhancer/promoter. This most likely bypasses the need for BRG1-containing chromatin-remodeling complexes. Likewise, recruitment of CBP/p300 by NF-kappaB may be sufficient to disrupt histone-DNA interaction for the initiation of transcription.

Asunto(s)

Cromatina/genética , Productos del Gen tax/genética , Virus Linfotrópico T Tipo 1 Humano/genética , Proteínas Nucleares/genética , Factores de Transcripción/genética , Activación Transcripcional , Factores de Transcripción Activadores/genética , Factores de Transcripción Activadores/metabolismo , Carcinoma Corticosuprarrenal/genética , Carcinoma Corticosuprarrenal/metabolismo , Cromatina/metabolismo , Proteína de Unión a Elemento de Respuesta al AMP Cíclico/química , Proteína de Unión a Elemento de Respuesta al AMP Cíclico/genética , Proteína de Unión a Elemento de Respuesta al AMP Cíclico/metabolismo , ADN Helicasas , Productos del Gen tax/aislamiento & purificación , Productos del Gen tax/metabolismo , Proteínas Fluorescentes Verdes/metabolismo , Histonas/metabolismo , Virus Linfotrópico T Tipo 1 Humano/metabolismo , Humanos , FN-kappa B/genética , FN-kappa B/metabolismo , Proteínas Nucleares/metabolismo , Factores de Transcripción/metabolismo , Transcripción Genética , Factor de Necrosis Tumoral alfa/farmacología

RESUMEN

We report the design of a unique two-plasmid production system for the first lentiviral vector to be evaluated in humans, VRX496. VRX496 is an optimized VSV-G pseudotyped vector derived from HIV-1 that expresses antisense to the HIV envelope gene. We found that a two-plasmid approach to production resulted in higher vector production titers when compared with a three-plasmid approach, which is particularly important for vector production at the large scale. Therefore, we carefully designed a single packaging construct, VIRPAC, for safety by reducing its homology with VRX496 and by insertion of functionally validated genetic elements designed to reduce the risk of generation of a replication-competent lentivirus (RCL). A native cis-acting ribozyme is used to prevent read through into the envelope gene from the upstream gag-pol genes in the packaging vector, thus preventing RNAs containing gag-pol and env together for comparable safety to a three-plasmid system. We demonstrate that there is no significant in vivo vector mobilization using a primary SCID-hu mouse transplantation model, which correlates with the presence of an anti-HIV payload and suggests that inclusion of antisense may be a useful tool to restrict mobilization in other vector constructs. Gene transfer is achieved using a one-step transduction procedure that is simple and clinically translatable, which reaches stable transduction efficiencies of >99% in CD4+ T lymphocytes within 3 days of culture initiation.

Asunto(s)

Terapia Genética , Vectores Genéticos/genética , Lentivirus/genética , Plásmidos/genética , Animales , Elementos sin Sentido (Genética)/genética , Células Cultivadas , Productos del Gen env/genética , Ingeniería Genética , Vectores Genéticos/efectos adversos , Vectores Genéticos/biosíntesis , VIH-1/genética , Humanos , Ratones , Ratones SCID , ARN Catalítico/genética , ARN Catalítico/fisiología , ARN Viral/metabolismo , Linfocitos T , Transducción Genética , Proteínas Virales/genética

RESUMEN

We present preclinical studies that demonstrate in vitro the feasibility and efficacy of lentivirus-based vector antisense gene therapy for control of HIV replication in primary T lymphocytes isolated from HIV-infected patients discordant for clinical status. VRX496 is a VSV-G-pseudotyped HIV-based vector that encodes an antisense payload against the HIV envelope gene. The antisense payload is under the control of the native LTR promoter, which is highly transactivated by tat upon HIV infection in the cell. Transfer of autologous CD4(+) T lymphocytes genetically modified with VRX496 (VRX496T) into HIV-infected patients is intended to provide a reservoir of cells capable of controlling HIV, potentially delaying AIDS onset. To determine the patient population likely to respond to VRX496 for optimal efficacy, we examined the ability of our research vector, VRX494, to modify and suppress HIV in vitro in lymphocytes isolated from 20 study subjects discordant for CD4 count and viral load. VRX494 is analogous to the clinical vector VRX496, except that it contains GFP as a marker gene instead of the 186-tag marker in the clinical vector. To transfer VRX494 to target cells we developed a novel scalable two-step transduction procedure that has been translated to the clinic in an ongoing clinical trial. This procedure achieved unprecedented transduction efficiencies of 94 +/- 5% in HIV(+) study subject cells. In addition the vector inhibited HIV replication >/=93% in culture regardless of the viral load or CD4 count of the subject or tropism of the virus strain with which they were infected. These findings demonstrate that VRX496T therapy is expected to be beneficial to patients that differ in their status in term of CD4 count and viral load. The methods described represent significant technical advances facilitating execution of lentivirus vector-mediated gene therapy for treatment of HIV and are currently being employed in the first trial evaluating lentivirus vector safety in humans.

Asunto(s)

Elementos sin Sentido (Genética)/genética , Linfocitos T CD4-Positivos/virología , Vectores Genéticos/genética , Infecciones por VIH/terapia , VIH-1/fisiología , Replicación Viral , Antígenos de Superficie/análisis , Antígenos de Superficie/genética , Elementos sin Sentido (Genética)/metabolismo , Recuento de Linfocito CD4 , Regulación hacia Abajo , Terapia Genética/métodos , Infecciones por VIH/inmunología , Infecciones por VIH/virología , Humanos , Transducción Genética , Carga Viral

RESUMEN

The impact of HIV-1 genetic diversity on candidate vaccines is uncertain. To minimize genetic diversity in the evaluation of HIV-1 vaccines, vaccine products must be matched to the predominant subtype in a vaccine cohort. To that end, full genome sequencing was used to detect and characterize HIV-1 subtypes and recombinant strains from individuals in Rakai District, Uganda. DNA extracted from peripheral blood mononuclear cells (PMBC) was PCR amplified using primers in the long terminal repeats (LTRs) to generate nearly full length genomes. Amplicons were directly sequenced with dye terminators and automated sequencers. Sequences were phylogenetically analyzed and recombinants were detected and mapped with distance scan and bootscan. Among 46 sequences, 54% were subtype D, 15% were subtype A, and 30% were recombinant. All recombinants were individually unique, and most combined subtypes A and D. Subtype D comprised more than 70% of all the HIV-1 genomes in Rakai when both pure subtypes and recombinants were considered. Candidate vaccines based on HIV-1 subtype D would be appropriate for evaluation in Rakai District, Uganda.

Asunto(s)

ADN Viral/química , Genoma Viral , VIH-1/clasificación , VIH-1/genética , Adolescente , Adulto , Secuencia de Bases , Femenino , Humanos , Masculino , Datos de Secuencia Molecular , Filogenia , Recombinación Genética , Uganda