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Jennifer Gordon

Publications and source records attributed to Jennifer Gordon.

At least 19 recordsLinked to original sources

In vivo genome editing of central nervous system SIV reservoirs in ART-suppressed rhesus macaques.

Latent human immunodeficiency virus type 1 (HIV-1) reservoirs in the central nervous system (CNS) may sustain viral persistence and neuroinflammation contributing to HIV-associated neurocognitive disorders (HAND) despite suppressive ART. AAV9-delivered CRISPR has successfully edited SIV proviral DNA in peripheral tissues with acceptable safety profiles, but the extent of in vivo genome editing in the brain remains unclear. Using SIV-infected rhesus macaques, we mapped intact proviral DNA across CNS regions and tested systemic AAV9-CRISPR-Cas9 targeting conserved sites within Ψ packaging signal and Gag region. Ten adult rhesus macaques were infected with genetically barcoded SIVmac239, suppressed with ART, then randomized to receive intravenous AAV9-SaCas9 with dual gRNAs (Ψ + Gag) or a Cas9-only control. At necropsy after viral rebound, SIV genomes were detected in multiple brain regions as well as lymphoid tissues, confirming the CNS as a persistent reservoir during ART. Barcode analysis revealed region-specific patterns consistent with compartmentalized CNS persistence. In CRISPR-treated animals, proviral editing was measurable across anatomically distinct CNS sites. These findings demonstrate that intact and potentially replication-competent virus persists in the primate brain under ART and that systemic AAV9-CRISPR can reach and edit proviral DNA in this sanctuary, supporting genome editing as a strategy toward durable remission of CNS reservoirs.

ART↗

Frequency and phenotype of JC virus-specific CD8+ T lymphocytes in the peripheral blood of patients with progressive multifocal leukoencephalopathy.

JC virus (JCV)-specific CD8+ cytotoxic T lymphocytes (CTL) are associated with a favorable outcome in patients with progressive multifocal leukoencephalopathy (PML) and cross-recognize the polyomavirus BK virus (BKV). We sought to determine the frequency and phenotype in fresh blood of CD8+ T cells specific for two A*0201-restricted JCV epitopes, VP1(p36) and VP1(p100), and assess their impact on JC and BK viremia and viruria in 15 healthy subjects, eight human immunodeficiency virus-positive (HIV+) individuals, and nine HIV+ patients with PML (HIV+ PML patients) classified as survivors. After magnetic pre-enrichment of CD8+ T cells, epitope-specific cells ranged from 0.001% to 0.022% [corrected] by tetramer staining, with no significant difference among the three study groups. By use of seven-color flow cytometry, there was no predominant differentiation phenotype subset among JCV-specific CD8+ T cells in healthy individuals, HIV+ subjects, or HIV+ PML patients. However, in one HIV+ PML patient studied in the acute phase, there was a majority of activated effector memory cells. BKV DNA was undetectable in all blood samples by quantitative PCR, while a low JC viral load was found in the blood of only one HIV+ and two HIV+ PML patients. JCV and BKV DNA were detected in 33.3% and 13.3% of all urine samples, respectively, independent of the presence of JCV-specific CTL. The detection of JCV DNA in the urine was associated with the presence of a JCV VP1(p100) CTL response. Immunotherapies aiming at increasing the cellular immune response against JCV may be valuable in the treatment of HIV+ individuals with PML.

Adult↗

Role of Pur alpha in targeting mRNA to sites of translation in hippocampal neuronal dendrites.

Using genetic inactivation in the mouse, PURA, encoding Pur alpha, is demonstrated to be essential for developmentally-timed dendrite formation in the cerebellum and hippocampus. Comparison of RNA species bound by Pur alpha prompts the hypothesis that Pur alpha functions with non-coding RNA in transport of certain mRNA molecules to sites of translation in dendrites. Pur alpha binds to human BC200 RNA, implicated in dendritic targeting, and this has homologies to 7SL RNA, implicated in compartmentalized translation. Results using hippocampal rat neurons in situ show that Pur alpha binds to BC1 RNA, implicated in dendritic targeting as a mouse counterpart of BC200, and to mRNA molecules translated in dendrites; Pur alpha is specifically located in dendrites, where it is colocalized with Map2, but not in axons, where it fails to colocalize with Ankyrin G. Pur alpha and Staufen are colocalized at dendritic sites of mRNA translation. Microtubule disruptors inhibit Pur alpha dendritic targeting and allow its mislocalization to axons. Using mouse brain, double-RNA immunoprecipitation places Pur alpha together with Staufen or FMRP on BC1 RNA and specific mRNA species in vivo. These results help define a mechanism by which Pur alpha targets specific mRNA molecules to sites of dendritic translation.

Animals↗

Dysregulation of NGF-signaling and Egr-1 expression by Tat in neuronal cell culture.

Examination of signal transduction pathways that modulate neuronal cell differentiation and protection against apoptosis has revealed a central role for the MAPK/Erk cascade. The activation of MAPK/Erk through the TrkA NGF signaling pathway is critical for growth and survival of neuronal cells. Here, we investigate the impact of HIV-1 Tat on the NGF-signaling pathway in SK-N-MC neuroblastoma cells. Expression of Tat decreased cell growth and induced apoptosis. Our results revealed dysregulation of various steps involved in the NGF pathway including suppression of MAPK, and inhibition of the promoter activity of Egr-1, a key pleiotropic mediator of the expression of genes involved in cell growth upon expression of Tat in SK-N-MC cells. Similarly, exposure of SK-N-MC to conditioned media derived from cells expressing Tat decreased phosphorylation of MAPK and reduced the level of Egr-1 protein expression in SK-N-MC cells. Furthermore, MAPK was able to phosphorylate Puralpha, a cellular protein that plays an important role in neuronal cell function and differentiation, and this was inhibited by Tat. The ability of Puralpha to interact with a GA/GC-rich sequence positioned upstream from the transcription start site of the Egr-1 promoter provided a rationale to examine Egr-1 expression. Expression of Tat decreased NGF-induced Egr-1 levels in SK-N-MC cells and reduced binding of Puralpha to the Egr-1 promoter. All of these observations support a model where the interplay between Tat and Puralpha dysregulates the NGF pathway including the MAPK/Erk network, resulting in reduced expression and activity of Egr-1 in neuronal cells.

Cell Cycle↗

The polyomavirus, JCV and its involvement in human disease.

The human neurotropic polyomavirus, JC virus (JCV), is the etiologic agent of progressive multifocal leukoencephalopathy (PML), a fatal demyelinating disease of the central nervous system that occurs mainly in immunosuppressed patients. JCV has also been found to be associated with human tumors of the brain and other organs. In this chapter, we describe JC virus and its role in human diseases.

Central Nervous System Diseases↗

Interplay of cellular and humoral immune responses against BK virus in kidney transplant recipients with polyomavirus nephropathy.

Reactivation of the polyomavirus BK (BKV) causes polyomavirus nephropathy (PVN) in kidney transplant (KTx) recipients and may lead to loss of the renal allograft. We have identified two HLA-A*0201-restricted nine-amino-acid cytotoxic T lymphocyte (CTL) epitopes of the BKV major capsid protein VP1, VP1(p44), and VP1(p108). Using tetramer staining assays, we showed that these epitopes were recognized by CTLs in 8 of 10 (VP1(p44)) and 5 of 10 (VP1(p108)) HLA-A*0201+ healthy individuals, while both epitopes elicited a CTL response in 10 of 10 KTx recipients with biopsy-proven PVN, although at variable levels. After in vitro stimulation with the respective peptides, CTLs directed against VP1(p44) were more abundant than against VP1(p108) in most healthy individuals, while the converse was true in KTx recipients with PVN, suggesting a shift in epitope immunodominance in the setting of active BKV infection. A strong CTL response in KTx recipients with PVN appeared to be associated with decreased BK viral load in blood and urine and low anti-BKV antibody titers, while a low or undetectable CTL response correlated with viral persistence and high anti-BKV antibody titers. These results suggest that this cellular immune response is present in most BKV-seropositive healthy individuals and plays an important role in the containment of BKV in KTx recipients with PVN. Interestingly, the BKV CTL epitopes bear striking homology with the recently described CTL epitopes of the other human polyomavirus JC (JCV), JCV VP1(p36) and VP1(p100). A high degree of epitope cross-recognition was present between BKV and corresponding JCV-specific CTLs, which indicates that the same population of cells is functionally effective against these two closely related viruses.

Adult↗

Phosphorylation mutants of JC virus agnoprotein are unable to sustain the viral infection cycle.

Many eukaryotic and viral regulatory proteins are known to undergo posttranslational modifications including phosphorylation, which plays a critical role in many aspects of cell function. Previous studies from our and other laboratories indicated that the JC virus (JCV) late regulatory protein, agnoprotein, plays an important role in the JCV life cycle. Agnoprotein contains several potential phosphorylation sites, including Ser7, Ser11, and Thr21, which are potential targets for the serine/threonine-specific protein kinase C (PKC). In this study, we investigated the functional significance of these phosphorylation sites for the activity of agnoprotein. In vitro and in vivo kinase assays demonstrated that agnoprotein is a target for phosphorylation by PKC. In addition, each of the PKC phosphorylation sites was mutated to Ala singly and in combination, and the effects of these mutations on the JCV life cycle were analyzed. Although the expression of each mutant agnoprotein was detectable during the infection cycle, virus containing each of these mutations failed to propagate. These results contrast with those obtained with an agnoprotein start codon point (Pt) mutant where agnoprotein expression was completely inhibited. The Pt mutant was viable but replicates less efficiently than the wild type (WT). Moreover, conservative substitutions at PKC phosphorylation sites (Ser7, Ser11, and Thr21 to Asp) resulted in a viable virus, which further demonstrate the importance of these sites on agnoprotein function. Further analysis of the mutants by viral release assay and electron microscopy studies revealed that viral particles were efficiently released from infected cells and morphologically indistinguishable from those of WT but were deficient in DNA content. This may account for the defective propagation of the mutants. These results imply that phosphorylated forms of agnoprotein may have essential functions in the viral life cycle and serve as potential targets for therapeutic interventions to limit JCV propagation and JCV-induced diseases.

Amino Acid Sequence↗

Human polyomaviruses and brain tumors.

Polyomaviruses are DNA tumor viruses with small circular genomes. Three polyomaviruses have captured attention with regard to their potential role in the development of human brain tumors: JC virus (JCV), BK virus (BKV), and simian vacuolating virus 40 (SV40). JCV is a neurotropic polyomavirus that is the etiologic agent of progressive multifocal leukoencephalopathy (PML), a fatal demyelinating disease of the central nervous system occurring mainly in AIDS patients. BKV is the causative agent of polyomavirus-associated nephropathy (PVN) which occurs after renal transplantation when BKV reactivates from a latent state during immunosuppressive therapy to cause allograft failure. SV40, originating in rhesus monkeys, gained notoriety when it entered the human population via contaminated polio vaccines. All three viruses are highly oncogenic when injected into the brain of experimental animals. Reports indicate that these viruses, especially JCV, are associated with brain tumors and other cancers in humans as evidenced from the analysis of clinical samples for the presence of viral DNA sequences and expression of viral proteins. Human polyomaviruses encode three non-capsid regulatory proteins: large T-antigen, small t-antigen, and agnoprotein. These proteins interact with a number of cellular target proteins to exert effects that dysregulate pathways involved in the control of various host cell functions including the cell cycle, DNA repair, and others. In this review, we describe the three polyomaviruses, their abilities to cause brain and other tumors in experimental animals, the evidence for an association with human brain tumors, and the latest findings on the molecular mechanisms of their actions.

Animals↗

Polyomavirus-associated nephropathy in renal transplantation: interdisciplinary analyses and recommendations.

Polyomavirus-associated nephropathy (PVAN) is an emerging cause of kidney transplant failure affecting 1-10% of patients. As uncertainty exists regarding risk factors, diagnosis, and intervention, an independent panel of experts reviewed the currently available evidence and prepared this report. Most cases of PVAN are elicited by BK virus (BKV) in the context of intense immunosuppression. No specific immunosuppressive drug is exclusively associated with PVAN, but most cases reported to date arise while the patient is on triple immunosuppressive combinations, often comprising tacrolimus and/or mycophenolate mofetil plus corticosteroids. Immunologic control of polyomavirus replication can be achieved by reducing, switching, and/or discontinuing components of the immunosuppressive regimen, but the individual's risk of rejection should be considered. The success rate of this intervention is increased with earlier diagnosis. Therefore, it is recommended that all renal transplant recipients should be screened for BKV replication in the urine: 1) every three months during the first two years posttransplant; 2) when allograft dysfunction is noted; and 3) when allograft biopsy is performed. A positive screening result should be confirmed in <4 weeks and assessed by quantitative assays (e.g. BKV DNA or RNA load in plasma or urine). Definitive diagnosis of PVAN requires allograft biopsy. If PVAN and concurrent acute rejection is diagnosed, antirejection treatment should be considered, coupled with subsequently reducing immunosuppression. The antiviral cidofovir is not approved for PVAN, but investigational use at low doses (0.25-0.33 mg/kg intravenously biweekly) without probenicid should be considered for refractory cases. Retransplantation after renal allograft loss to PVAN remains a treatment option for patients clearing polyomavirus replication.

Humans↗

JCV T-antigen interacts with the neurofibromatosis type 2 gene product in a transgenic mouse model of malignant peripheral nerve sheath tumors.

The human polyomavirus, JC virus, has recently been associated with several human CNS tumors, including medulloblastomas and a broad range of glial-origin tumors. This ubiquitous virus is the causative agent of the rare demyelinating disease, progressive multifocal leukoencephalopathy in immunocompromised individuals. Expression of the viral protein, T-antigen, which possesses the ability to transform cells of neural origin, has been detected in human CNS tumors. In an effort to further understand the transforming potential of JCV T-antigen, transgenic mice expressing JCV T-antigen under the control of the Mad-4 promoter were generated. As described previously, approximately 50% of the animals developed pituitary tumors by 1 year of age. However, a small subset of the animals developed solid masses arising from the soft tissues surrounding the salivary gland, the sciatic nerve, and along the extremities that histologically resemble malignant peripheral nerve sheath tumors, rare neoplasms that occur in individuals with neurofibromatosis type 1 (NF1). JCV T-antigen was detected in tumor tissue by immunohistochemistry and immunoprecipitation/Western blotting, but not in normal tissues and was colocalized with NF2, the putative tumor suppressor protein associated with neurofibromatosis type 2, in the nucleus of some cells. In addition, T-antigen was co-precipitated with NF2, but not with NF1 protein, although NF1 was detectable in tumor tissue. Furthermore, precipitated immunocomplexes contained T-antigen, NF2, and p53, suggesting that these three proteins may form a ternary complex. The importance of these findings on mechanisms of T-antigen-mediated tumorigenesis and the pathogenesis of neurofibromatosis are discussed. Oncogene (2004) 23, 5459-5467. doi:10.1038/sj.onc.1207728 Published online 10 May 2004

Animals↗

Intracellular approach for blocking JC virus gene expression by using RNA interference during viral infection.

The human polyomavirus, JC virus (JCV), encodes two regulatory proteins at the early (T antigen) and the late (agnoprotein) phases of viral infection whose activities are important for the production of the viral capsid proteins and the dysregulation of several host factors and their functions. For this study, we designed and utilized an RNA interference strategy via small interfering RNAs (siRNAs) that targeted the expression of T antigen and agnoprotein in human astrocytic cells. The treatment of cells with specific siRNA oligonucleotides targeting a conserved region of T antigen, nucleotides (nt) 4256 to 4276 (Mad-1 strain), caused a >50% decline in the level of T antigen and in its transcriptional activity upon the viral capsid genes as well as a significant reduction in viral DNA replication in infected cells. Similarly, a single siRNA that aimed at nt 324 to 342 of agnoprotein noticeably reduced early and late viral protein production. A combined treatment of the infected cells with both T-antigen and agnoprotein siRNAs completely abolished viral capsid protein production, indicative of the ability of the siRNAs to effectively halt multiplication of the virus in infected cells. These observations provide a new avenue for possible treatments of patients with the JCV-induced demyelinating disease progressive multifocal leukoencephalopathy.

Antigens, Viral, Tumor↗

Primary central nervous system lymphoma expressing the human neurotropic polyomavirus, JC virus, genome.

B lymphocytes are known as a potential site for latency and reactivation of the human neurotropic polyomavirus, JC virus (JCV). In light of recent studies on the oncogenicity of JCV and the transforming ability of the JCV early protein, T antigen, we investigated the association of JCV with B-cell lymphomas of the central nervous system. Examination of 27 well-characterized clinical specimens by gene amplification and immunohistochemistry revealed the presence of DNA sequences corresponding to the JCV early genome and the late Agnoprotein in 22 samples and the JCV late genome encoding the viral capsid proteins in 8 samples. Expression of T antigen and that of Agnoprotein by immunohistochemistry were each detected in six specimens. No evidence of the production of viral capsid proteins was observed, ruling out productive infection of JCV in the tumor cells. The results from laser capture microdissection verified the presence of JCV T-antigen sequences in tumor cells with positive immunoreactivity to antibodies against the viral proteins T antigen and Agnoprotein. Due to previous reports demonstrating an association of the Epstein-Barr virus (EBV) with transformation of B lymphocytes, EBV DNA sequences and the EBV transforming protein, latent membrane protein 1 (LMP1), were analyzed in parallel. EBV LMP1 DNA sequences were detected in 16 of 23 samples, and LMP1 expression was detected in 16 samples, 5 of which exhibited positive immunoreactivity to JCV proteins. Double labeling demonstrated coexpression of JCV T antigen and EBV LMP1 in the same cells. The detection of the JCV genome in large numbers of B-cell lymphomas and its coexistence with EBV suggest a potential role for JCV in the pathogenesis of primary CNS lymphoma.

Adult↗

Polyomavirus nephropathy in kidney transplantation.

Polyomavirus nephropathy has become an important complication in kidney transplantation, with a prevalence of 1% to 8%. Unfortunately, the risk factors for polyomavirus nephropathy and renal allograft loss are not well defined. The definitive diagnosis is made through assessment of a kidney transplant biopsy. Recently, noninvasive urine and serum markers have been used to assist in polyomavirus nephropathy diagnosis and monitoring. Primary treatment is immunosuppression reduction, but must be balanced with the risks of rejection. No antiviral treatments for polyomavirus nephropathy have been approved by the Food and Drug Administration. Although cidofovir has shown in vitro activity against murine polyomaviruses, and has been effective in some patients, it is associated with significant nephrotoxicity. Graft loss due to polyomavirus nephropathy should not be a contraindication to retransplantation; however, experience is limited. This review presents potential risk factors, screening, diagnostic and monitoring methods, therapeutic management, and retransplantation experience for polyomavirus nephropathy.

Antiviral Agents↗

Basic and clinical research in polyomavirus nephropathy.

Over the last decade, polyomavirus nephropathy (PVN) has emerged as an important cause of renal allograft dysfunction and graft loss. PVN occurs with a prevalence of 1%-8% in renal transplant recipients and is most commonly reported within the first 12 months posttransplant. The human polyomavirus, BK virus, is thought to be the primary etiologic agent of PVN. Risk factors for PVN are not well defined and are most likely a result of a complex interaction between multiple donor and recipient factors. Definitive diagnosis of PVN is made through histological assessment of a renal allograft biopsy. Recent studies have also evaluated noninvasive urine and serum markers for screening of BK virus replication and as adjunct tools in PVN diagnosis and monitoring. The principal treatment for PVN is immunosuppression reduction, but this must be balanced against the risks of rejection. If rejection occurs concurrently with PVN, a brief increase in immunosuppression to treat the rejection episode followed by a subsequent reduction in immunosuppression is recommended. No antiviral treatments for PVN have been approved by the Food and Drug Administration. Although the antiviral drug cidofovir has shown in vitro activity against murine polyomaviruses, and has been effective in some patients, it is associated with significant nephrotoxicity. Small series of patients treated with leflunomide and intravenous immune globulin therapy for PVN have also recently been reported. Retransplantation after graft loss due to PVN is feasible, but experience is limited. Current research is focusing on identifying PVN risk factors, refining screening, diagnostic and monitoring methods, and developing therapy for prophylaxis and treatment of PVN with the goals of decreasing the prevalence of PVN and improving allograft outcomes in renal transplant recipients diagnosed with PVN. This review will present recent advances in basic and clinical research related to PVN and renal transplantation.

Humans↗

An in vitro system for developmental and genetic studies of Leishmania donovani phosphoglycans.

Glycoconjugates have been shown to play important roles in Leishmania development. However, the ability to study these molecules and other processes would benefit greatly from improved methods for genetic manipulation and analysis of the amastigote stage. This is especially challenging for L. donovani, the agent of the most severe form of leishmaniasis, which can rapidly lose virulence during in vitro culture. Here we report on a clonal subline of an L. donovani 1S2D (LdBob or LdB), which differentiates readily from promastigotes to amastigotes in axenic culture, and maintains this ability during extended parasite cultivation in vitro. This derivative can be plated and transfected efficiently while grown as promastigotes or amastigotes. Importantly, LdB maintains the ability to differentiate while undergoing genetic alterations required for creation of gene knockouts and complemented lines. Like virulent L. donovani, LdB exhibits down-regulation of lipophosphoglycan (LPG) synthesis and up-regulation of A2 protein synthesis in amastigotes. We showed that knockouts of LPG2, encoding a Golgi GDP-mannose transporter, eliminated phosphoglycan synthesis in LdB axenic amastigotes. These and other data suggest that LdB axenic amastigotes will be generally useful as a differentiation model in studies of gene expression, virulence, glycoconjugate function and drug susceptibility in L. donovani.

Animals↗

Human neurotropic polyomavirus, JCV, and its role in carcinogenesis.

A number of recent studies have reported the detection of the ubiquitous human polyomavirus, JC virus (JCV), in samples derived from several types of neural as well as non-neural human tumors. The human neurotropic JCV was first identified as the etiologic agent of the fatal demyelinating disease, progressive multifocal leukoencephalopathy, which usually occurs in individuals with defects in cell-mediated immunity, including AIDS. However, upon mounting evidence of the oncogenic potential of the viral regulatory protein, T-antigen, and JCV's oncogenecity in a broad range of animal models, studies were initiated to determine its potential involvement in human carcinogenesis. Initially, the most frequently observed tumors in rodent models, including medulloblastoma, astrocytoma, glioblastoma, and other neural-origin tumors were analysed. These studies were followed by analysis of non-neural tumors such as colorectal carcinomas. In a subset of each tumor type examined, JC viral genomic DNA sequences could be detected by PCR and confirmed by Southern blot hybridization or direct sequencing. In a smaller subset of the tumors, the expression of T-antigen was observed by immunohistochemical analysis. Owing to the established functions of T-antigen including its ability to interact with tumor suppressor proteins such as Rb and p53, and its ability to influence chromosomal stability, potential mechanisms of JCV T-antigen-mediated cellular dysregulation are discussed. Further, as increasing evidence suggests that T-antigen is not required for maintenance of a transformed phenotype, a hit-and-run model for T-antigen-induced transformation is proposed.

Animals↗

JC virus-induced changes in cellular gene expression in primary human astrocytes.

Cell-type-specific transcription of the JC virus (JCV) promoter in glial cells initiates a series of events leading to viral replication in the brain and the development of the fatal demyelinating disease progressive multifocal leukoencephalopathy (PML) in patients with neurologic complications due to infection with human immunodeficiency virus type 1. Here we employed an in vitro infection of primary cultures of human astrocytes to compare the transcriptional profile of cellular genes after JCV infection by using an oligonucleotide-based microarray of 12600 genes. Transcription of nearly 355 genes was enhanced and expression of 130 genes was decreased to various degrees. Many transcripts that were increased upon JCV infection were found to encode proteins with properties that suggest their involvement in cell proliferation, including cyclin A and cyclin B1; signaling pathways, such as transforming growth factor beta receptor 1, platelet-derived growth factor receptor and fibroblast growth factor family receptor; and other regulatory events, such as inflammatory responses, including cyclo-oxygenase-2 (Cox-2). Microarray-based data for several cell cycle-regulatory genes were further examined by using Western blot analysis of in vitro infected astrocytes harvested early and late during the infection. Results demonstrate that protein levels of all upregulated genes were found to increase at some point during the infection time course. In parallel, immunohistochemical assessment of cell cycle proteins, including cyclins A, B1, E, and Cdk2, showed positive staining of astrocytes within PML lesions of brain tissue from patients with neuro-AIDS. Microarray analysis was found to be a useful predictor of gene expression in infected cells; however, it may not directly correlate with protein levels during infection with JCV.

Astrocytes↗