Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P05231 (interleukin-6)
 23,907 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Human herpesvirus 8 (HHV-8) is a gamma-2 herpesvirus, related genetically to simian herpesvirus saimiri (HVS), the prototype virus of this subgroup of the gammaherpesvirus subfamily. HHV-8 DNA is present in all forms of Kaposi's sarcoma (KS) and primary effusion lymphoma (PEL), and in most forms of multicentric Castleman's disease (MCD), especially in HIV infected individuals. Of relevance to attempts to explain the molecular basis of HHV-8 associated neoplasia, are the unique genes specified by this virus, in particular angiogenic cytokines viral interleukin-6 (vIL-6) and viral CC-class chemokines (vCCL-1, vCCL-2, vCCL-3), mitogenic signaling membrane proteins variable ITAM-containing protein (VIP) and latency associated membrane protein (LAMP), pro-survival latently-expressed viral interferon regulatory factor (vIRF3), and the kaposin family of proteins that promote cell growth and cytokine production. Also of relevance are the angiogenic and cytokine-inducing viral G protein-coupled receptor (vGPCR), pro-proliferative and pro-survival latency proteins viral FLICE inhibitory protein (vFLIP) and latency-associated nuclear antigen (LANA), and G1-S phase cell-cycle promoter viral cyclin (v-cyclin), proteins specified also by other gamma-2 herpesviruses. The enormous progress on the characterization of the properties and biological activities of these proteins over the last ten years has provided insight into the potential mechanisms of HHV-8-induced neoplasia. Present data suggest that there operates a combination of cell transformation mediated by latently expressed proteins that promote cell proliferation and survival coupled with paracrine signaling functions mediated by either the viral cytokines or viral receptor-induced secreted cellular proteins. This review discusses the properties of the viral proteins believed to contribute to viral neoplasia via these mechanisms.
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PMID:Human herpesvirus 8-encoded proteins with potential roles in virus-associated neoplasia. 1712 98

Kaposi's sarcoma-associated herpesvirus (KSHV) is the infectious cause of Kaposi's sarcoma, primary effusion lymphoma, and plasmablastic multicentric Castleman's disease. STAT3 has been shown to be important for the maintenance of primary effusion lymphoma cells in culture and is chronically activated in many tumor cell lines. However, little is known about the role of KSHV in the activation of STAT3 or the role of STAT3 in KS tumors. We demonstrate that STAT3 is activated by KSHV infection of endothelial cells, the KS tumor cell type, in a biphasic fashion. Viral binding and entry activate STAT3 in the first 2 h after infection, but this activation dissipates by 4 h postinfection. By 12 h after KSHV infection, concomitant with the expression of latent genes, STAT3 is once again activated, and this activation persists for as long as latent infection is maintained. Activated STAT3 translocates to the nucleus, where it can bind to STAT3-specific DNA elements and can activate STAT3-dependent promoter activity. Conditioned medium from KSHV-infected endothelial cells is able to transiently activate STAT3, indicating the involvement of a secreted factor and that a latency-associated factor in KSHV-infected cells is necessary for sustained activation. KSHV upregulates gp130 receptor expression, and both gp130 and JAK2 are required for the activation of STAT3. However, neither human nor viral interleukin-6 is required for STAT3 activation. Persistent activation of the oncogenic signal transducer, STAT3, by KSHV may play a critical role in the viral pathogenesis of Kaposi's sarcoma, as well as in primary effusion lymphomas.
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PMID:Persistent activation of STAT3 by latent Kaposi's sarcoma-associated herpesvirus infection of endothelial cells. 1715 Nov

Human immunodeficiency virus type 1 (HIV-1) infection significantly increases the risk of Kaposi's sarcoma (KS) occurrence in individuals infected with Kaposi's sarcoma-associated herpesvirus (KSHV). KSHV infection appears to be necessary but not sufficient for KS development without other cofactors. However, factors that facilitate KSHV to cause KS have not been well defined. Previously, we determined that human herpesvirus 6 was one of the cofactors that activated lytic cycle replication of KSHV. Here, we demonstrate that the Tat protein of HIV-1 is a potentially important factor in the pathogenesis of KS, as determined by production of lytic phase mRNA transcripts and viral proteins in BCBL-1 cells. Mechanistic studies showed ectopic expression of Tat induced the production of human interleukin-6 (huIL-6) and its receptor (huIL-6Ra) and activated STAT3 signaling. Neutralization of huIL-6 or huIL-6R or inhibition of STAT3 signaling enhanced the replication. In addition, IL-4/STAT6 signaling also partially contributed to Tat-induced KSHV replication. These findings suggest that Tat may participate in KS pathogenesis by inducing KSHV replication and increasing KSHV viral load. These data also suggest that JAK/STAT signaling may be of therapeutic value in AIDS-related KS patients.
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PMID:Intracellular Tat of human immunodeficiency virus type 1 activates lytic cycle replication of Kaposi's sarcoma-associated herpesvirus: role of JAK/STAT signaling. 1715 Nov 25

Kaposi's sarcoma (KS) is caused by Kaposi's sarcoma-associated herpesvirus (KSHV) and consists of proliferating spindle cells, which are related to lymphatic endothelial cells (LEC). Angiopoietin-2 (Ang2) is a secreted proangiogenic and lymphangiogenic molecule. Here, we show the expression of Ang2 protein in KS and confirm that KSHV infection up-regulates Ang2 in LEC. We show that a paracrine mechanism contributes to this up-regulation. A lentiviral library of individual KSHV-encoding genes, comprising the majority of known latent genes and a selection of lytic viral genes, was constructed to investigate the underlying mechanism of this up-regulation. Two lytic genes, viral interleukin-6 (vIL6) and viral G-protein-coupled receptor (vGPCR), up-regulated Ang2 expression in LEC. Both vIL6 and vGPCR are expressed in KSHV-infected LEC and caused up-regulation of Ang2 in a paracrine manner. KSHV, vIL6, and vGPCR up-regulated Ang2 through the mitogen-activated protein kinase (MAPK) pathway. Gene expression microarray analysis identified several other angiogenic molecules affected by KSHV, including the vascular endothelial growth factor (VEGF)/VEGF receptor (VEGFR) axis, which is also affected by vIL6 and vGPCR in LEC, and matrix metalloproteinases, which could act in concert with Ang2 to contribute to KS development. These findings support the paracrine and autocrine roles of the lytic KSHV-encoded proteins, vIL6 and vGPCR, in KS pathogenesis and identify Ang2 as a potential therapeutic target for this neoplasm.
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PMID:Kaposi's sarcoma-associated herpesvirus-encoded interleukin-6 and G-protein-coupled receptor regulate angiopoietin-2 expression in lymphatic endothelial cells. 1748 15

Angiofollicular lymphoid hyperplasia (Castleman's disease) is a lymphoproliferative process thought to be mediated by overexpression of II interleukin-6. Castleman's disease has two variants: Castleman's disease has two variants: Hyaline vascular type and plasma cell variant (multicentric Castleman's disease). The hyaline vascular type tends to be localized, and the plasma cell variant shows more systematic signs and carriers a worse clinical prognosis. Castleman's disease is associated with B-cell lymphoma, Kaposi sarcoma, Human herpes virus 8 (HHV-8), and Epstein-Barr virus. Castleman's disease have been described thrice post kidney transplant. In this report, we document the course of a renal recipient who developed the plasma cell variant of Castleman's disease at 16 months after failure of his allograft and return to dialysis. He displayed clinical resolution of this complication after graft nephrectomy. To our knowledge, this is the first case where the disease manifestations disappeared after graft removal. Our patient experienced chronic renal allograft rejection which may have driven all the systematic manifestations of multicentric castleman's disease and possibly reactivated a latent HHV-8 infection. In this case immunohistochemical testing for HHV-8 was not available to prove a role for this agent.
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PMID:Post renal transplant Castleman's disease resolved after graft nephrectomy: a case report. 1752 52

Multicentric Castleman's disease (MCD), a relatively rare lymphoproliferative disorder that presents with heterogenous symptoms including fevers, anemia, and multifocal lymphadenopathy, is today most commonly observed in individuals infected with human immunodeficiency virus type-1 (HIV). In such individuals, a lymph node biopsy typically identifies cells that stain for Kaposi's sarcoma-associated herpesvirus proteins, and most HIV-associated MCD features can be attributed to the presence of this gamma-herpesvirus. Surgery and antiviral therapies including highly active antiretroviral therapy, interferon-alpha, foscarnet, ganciclovir, and antibodies to interleukin-6 have proved largely ineffective, and chemotherapy in HIV positive individuals is complicated by limited efficacy and pronounced toxicity. While no randomized trials have been performed, more recently the use of the anti-CD20 monoclonal antibody rituximab in large single center cohorts has been associated with prolonged remissions, radiologic responses, as well as hematologic and serum chemistry normalization of the inflammatory picture observed, at the expense of B cell depletion and flare of Kaposi's sarcoma. MCD represents a model of disease at the interplay between tumor biology, infection, and immunology.
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PMID:HIV-associated multicentric Castleman's disease. 1826 Jan 15

Kaposi's sarcoma-associated herpesvirus (KSHV), also known as human herpesvirus 8, is associated with several malignant disorders, including Kaposi's sarcoma, primary effusion lymphoma (PEL), and multicentric Castleman's disease. An early lytic gene of KSHV encodes viral interleukin-6 (vIL-6), a viral homologue of the proinflammatory cytokine and an autocrine/paracrine growth factor human IL-6. In this study, we examined the effects of suppressing vIL-6 expression in PEL cells with antisense peptide-conjugated phosphorodiamidate morpholino oligomers (PPMO). PPMO are ssDNA-analogues that have a modified backbone and enter cells readily. Treatment of PEL cells with a PPMO designed against vIL-6 mRNA led to a marked reduction in the proportion of vIL-6-positive cells detected by immunofluorescence assay. Analysis by Western blot confirmed a specific reduction in the vIL-6 protein level and showed that the reduction was dependent on the dose of vIL-6 PPMO. PEL cells treated with the vIL-6 PPMO exhibited reduced levels of cellular growth, IL-6 expression and KSHV DNA, and an elevated level of p21 protein. Treatment of PEL cells with a combination of two vIL-6 PPMO compounds targeting different sequences in the vIL-6 mRNA led to an inhibitory effect that was greater than that achieved with either PPMO alone. These results show that PPMO targeting vIL-6 mRNA can potently reduce vIL-6 protein translation and indicate that further exploration of these compounds in an animal model for potential clinical application is warranted.
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PMID:Blockade of viral interleukin-6 expression of Kaposi's sarcoma-associated herpesvirus. 1834 56

The transmembrane protein gp130 acts as the signal transducing receptor subunit for interleukin-6 type cytokines, including viral interleukin-6, which is encoded by the Kaposi's sarcoma-associated herpes virus. Viral interleukin-6 has been shown to mimic human IL-6 functions, including activation of the JAK1 and STAT1/3 signaling pathways. Based on the crystal structure of three extracellular domains of gp130 in complex with viral interleukin-6, we have designed and synthesized a range of assembled peptides that mimic the sequentially discontinuous binding site of gp130 for viral interleukin-6. These peptides, which present the three binding site fragments of gp130 in a nonlinear, discontinuous fashion, were shown to inhibit the interaction of gp130 with viral interleukin-6, as well as the stimulation of viral interleukin-6-induced cell proliferation. These results validate the concept of synthetic mimicry of discontinuous protein-binding sites through assembled peptides, and the use of such molecules as modulators of protein-ligand interactions.
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PMID:Synthetic mimetics of the gp130 binding site for viral interleukin-6 as inhibitors of the vIL-6-gp130 interaction. 1837 51

Kaposi's sarcoma-associated herpesvirus (KSHV)-encoded viral FLICE inhibitory protein K13 interacts with a cytosolic IkappaB kinase (IKK) complex to activate nuclear factor-kappaB (NF-kappaB). We recently reported that K13 antagonizes KSHV lytic regulator RTA (replication and transcription activator) and blocks lytic replication, but spares RTA-induced viral interleukin-6 (vIL6). Here we report that K13 is also present in the nuclear compartment, a property not shared by its structural homologs. K13 interacts with and activates the nuclear IKK complex, and binds to the IkappaBalpha promoter. K13 mutants that are retained in the cytosol lack NF-kappaB activity. However, neither the IKKs nor NF-kappaB activation is required for nuclear localization of K13. Instead, this ability is dependent on a nuclear localization signal located in its N-terminal 40 amino acids. Finally, K13, along with p65/RelA, binds to the promoters of a number of KSHV lytic genes, including RTA, ORF57 and vGPCR, but not to the promoter of the vIL6 gene. Thus, K13 has an unexpected nuclear role in viral and cellular gene regulation and its differential binding to the promoters of lytic genes may not only contribute to the inhibition of KSHV lytic replication, but may also account for the escape of vIL6 from K13-induced transcriptional suppression.
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PMID:A nuclear role for Kaposi's sarcoma-associated herpesvirus-encoded K13 protein in gene regulation. 1846 54

Lytic reactivation from latency is critical for the pathogenesis of Kaposi's sarcoma-associated herpesvirus (KSHV). We previously demonstrated that the 691-amino-acid (aa) KSHV Rta transcriptional transactivator is necessary and sufficient to reactivate the virus from latency. Viral lytic cycle genes, including those expressing additional transactivators and putative oncogenes, are induced in a cascade fashion following Rta expression. In this study, we sought to define Rta's direct targets during reactivation by generating a conditionally nuclear variant of Rta. Wild-type Rta protein is constitutively localized to cell nuclei and contains two putative nuclear localization signals (NLSs). Only one NLS (NLS2; aa 516 to 530) was required for the nuclear localization of Rta, and it relocalized enhanced green fluorescent protein exclusively to cell nuclei. The results of analyses of Rta NLS mutants demonstrated that proper nuclear localization of Rta was required for transactivation and the stimulation of viral reactivation. RTA with NLS1 and NLS2 deleted was fused to the hormone-binding domain of the murine estrogen receptor to generate an Rta variant whose nuclear localization and ability to transactivate and induce reactivation were tightly controlled posttranslationally by the synthetic hormone tamoxifen. We used this strategy in KSHV-infected cells treated with protein synthesis inhibitors to identify direct transcriptional targets of Rta. Rta activated only eight KSHV genes in the absence of de novo protein synthesis. These direct transcriptional targets of Rta were transactivated to different levels and included the genes nut-1/PAN, ORF57/Mta, ORF56/Primase, K2/viral interleukin-6 (vIL-6), ORF37/SOX, K14/vOX, K9/vIRF1, and ORF52. Our data suggest that the induction of most of the KSHV lytic cycle genes requires additional protein expression after the expression of Rta.
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PMID:Identification of direct transcriptional targets of the Kaposi's sarcoma-associated herpesvirus Rta lytic switch protein by conditional nuclear localization. 1871 5


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