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author:("Li, mengo")
1.  Lupus nephritis associated with placental site trophoblastic tumor: A case report and review of the literature 
•An improved YASSO model is proposed by considering residual spatial autocorrelation.•Model prediction errors are minimised using GIS data at the appropriate spatial scale.•Topographical factors describe 24–49% of variation in soil carbon.
PMCID: PMC4060261  PMID: 24944882
Amenorrhoea; Lupus nephritis; Nephrotic syndrome; Placental site trophoblastic tumor
2.  Chinese SLE Treatment and Research Group Registry: III. Association of Autoantibodies with Clinical Manifestations in Chinese Patients with Systemic Lupus Erythematosus 
Journal of Immunology Research  2014;2014:809389.
We investigated the characteristics of Chinese SLE patients by analyzing the association between specific autoantibodies and clinical manifestations of 2104 SLE patients from registry data of CSTAR cohort. Significant (P < 0.05) associations were found between anti-Sm antibody, anti-rRNP antibody, and malar rash; between anti-RNP antibody, anti-SSA antibody, and pulmonary arterial hypertension (PAH); between anti-SSB antibody and hematologic involvement; and between anti-dsDNA antibody and nephropathy. APL antibody was associated with hematologic involvement, interstitial lung disease, and a lower prevalence of oral ulcerations (P < 0.05). Associations were also found between anti-dsDNA antibody and a lower prevalence of photosensitivity, and between anti-SSA antibody and a lower prevalence of nephropathy (P < 0.05). Most of these findings were consistent with other studies in the literature but this study is the first report on the association between anti-SSA and a lower prevalence of nephropathy. The correlations of specific autoantibodies and clinical manifestations could provide clues for physicians to predict organ damages in SLE patients. We suggest that a thorough screening of autoantibodies should be carried out when the diagnosis of SLE is established, and repeated echocardiography annually in SLE patients with anti-RNP or anti-SSA antibody should be performed.
PMCID: PMC4017718  PMID: 24864270
3.  Elevated Levels of CD4+CD25+FoxP3+ T Cells in Systemic Sclerosis Patients Contribute to the Secretion of IL-17 and Immunosuppression Dysfunction 
PLoS ONE  2013;8(6):e64531.
Immune imbalance between regulatory T (Treg) and Th17 cells is a characteristic of systemic sclerosis (SSc). The functional heterogeneity among Treg can be elucidated by separating Treg into different subsets based on the expression of FoxP3 and CD45RA. The aim of this study was to investigate the role of Treg subsets in the immune imbalance in naïve SSc.
Peripheral blood mononuclear cells (PBMCs) of 31 SSc patients and 33 healthy controls were analyzed for the expression of CD4, CD25, CD45RA, CTLA-4, FoxP3, and IL-17 using flow cytometry. Treg immunesuppression capacity was measured in co-culture experiments. The expression of FoxP3, CTLA-4, IL-17A, and RORC mRNA was measured by real-time PCR.
The frequency of CD4+CD25+FoxP3+ Treg cells was significantly elevated in patients with SSc (3.62±1.14 vs 1.97±0.75, p<0.001) with diminished immunosuppression capacity. In SSc, the proportion of FoxP3highCD45RA− activated Treg cells (aTreg) was decreased, the proportion of FoxP3lowCD45RA− T cells was increased, and the proportion of FoxP3lowCD45RA+ resting Treg cells (rTreg) was decreased. The immune suppression capacity of aTreg and rTreg was diminished, while FoxP3lowCD45RA− T cells exhibited a lack of suppression capacity. The immune dysfunction of aTreg was accompanied by the abnormal expression of CTLA-4. Th17 cell numbers were elevated in SSc, FoxP3lowCD45RA− T cells produced IL-17, confirming their Th17 potential, which was consistent with the elevated levels of FoxP3+IL-17+ cells in SSc.
A decrease in aTreg levels, along with functional deficiency, and an increase in the proportion of FoxP3lowCD45RA− T cells, was the reason for the increase in dysfunctional Treg in SSc patients, potentially causing the immune imbalance between Treg and Th17 cells.
PMCID: PMC3679128  PMID: 23776439
4.  Associations between salivary gland histopathologic diagnoses and phenotypic features of Sjögren’s Syndrome (SS) among 1726 registry participants 
Arthritis and rheumatism  2011;63(7):2021-2030.
The Sjögren’s International Collaborative Clinical Alliance (SICCA) is an ongoing NIH-funded registry whose cohort ranges from those with symptoms of possible Sjögren’s syndrome (SS) to those with obvious disease. Using this database we examined associations between labial salivary gland (LSG) histopathology and other phenotypic features of SS.
LSG biopsy specimens from SICCA participants underwent protocol-directed histopathological assessments. Among 1726 LSG specimens exhibiting any pattern of sialadenitis, we compared biopsy diagnoses against concurrent salivary, ocular and serological assessments.
LSG specimens included 61% with focal lymphocytic sialadenitis, (FLS; 66% of which had focus scores [FS] ≥ 1 per 4 mm2) and 38% with non-specific or sclerosing chronic sialadenitis (NS/SCS). FS ≥ 1 was strongly associated with positive serum anti-SS-A/-B, rheumatoid factor and the ocular component of SS, but not with symptoms of dry mouth or eyes. Those with positive anti-SS-A/-B were 9 times more likely to have a FS ≥ 1 (95% CI: 7.4; 11.9) than FS<1 or another pattern, while those with unstimulated whole salivary flow < 0.1 ml/min were only 2 times more likely to have a FS ≥ 1 (95% CI:1.7; 2.8) than FS<1 or another pattern, while controlling for other phenotypic features of SS.
Distinguishing FLS from NS/SCS is essential in assessing LSG biopsies, before determining FS. A diagnosis of FLS with FS ≥ 1 per 4 mm2, as compared to FLS with FS< 1 or with NS/SCS, was strongly associated with the ocular and serological components of SS and reflects SS autoimmunity.
PMCID: PMC3128201  PMID: 21480190
5.  Ser-634 and Ser-636 of Kaposi’s Sarcoma-Associated Herpesvirus RTA are Involved in Transactivation and are Potential Cdk9 Phosphorylation Sites 
The replication and transcription activator (RTA) of Kaposi’s sarcoma-associated herpesvirus (KSHV), K-RTA, is a lytic switch protein that moderates the reactivation process of KSHV latency. By mass spectrometric analysis of affinity purified K-RTA, we showed that Thr-513 or Thr-514 was the primary in vivo phosphorylation site. Thr-513 and Thr-514 are proximal to the nuclear localization signal (527KKRK530) and were previously hypothesized to be target sites of Ser/Thr kinase hKFC. However, substitutions of Thr with Ala at 513 and 514 had no effect on K-RTA subcellular localization or transactivation activity. By contrast, replacement of Ser with Ala at Ser-634 and Ser-636 located in a Ser/Pro-rich region of K-RTA, designated as S634A/S636A, produced a polypeptide with ∼10 kDa shorter in molecular weight and reduced transactivation in a luciferase reporter assay relative to the wild type. In contrast to prediction, the decrease in molecular weight was not due to lack of phosphorylation because the overall Ser and Thr phosphorylation state in K-RTA and S634A/S636A were similar, excluding that Ser-634 or Ser-636 motif served as docking sites for consecutive phosphorylation. Interestingly, S634A/S636A lost ∼30% immuno-reactivity to MPM2, an antibody specific to pSer/pThr-Pro motif, indicating that 634SPSP637 motif was in vivo phosphorylated. By in vitro kinase assay, we showed that K-RTA is a substrate of CDK9, a Pro-directed Ser/Thr kinase central to transcriptional regulation. Importantly, the capability of K-RTA in associating with endogenous CDK9 was reduced in S634A/S636A, which suggested that Ser-634 and Ser-636 may be involved in CDK9 recruitment. In agreement, S634A/S636A mutant exhibited ∼25% reduction in KSHV lytic cycle reactivation relative to that by the wild type K-RTA. Taken together, our data propose that Ser-634 and Ser-636 of K-RTA are phosphorylated by host transcriptional kinase CDK9 and such a process contributes to a full transcriptional potency of K-RTA.
PMCID: PMC3283893  PMID: 22371709
Kaposi’s sarcoma-associated herpesvirus; replication and transcription activator; phosphorylation; negative elongation factor B; CDK9
7.  HIV-1 Reactivation Induced by the Periodontal Pathogens Fusobacterium nucleatum and Porphyromonas gingivalis Involves Toll-Like Receptor 4 and 9 Activation in Monocytes/Macrophages▿  
Although oral coinfections (e.g., periodontal disease) are highly prevalent in human immunodeficiency virus type 1-positive (HIV-1+) patients and appear to positively correlate with viral load levels, the potential for oral bacteria to induce HIV-1 reactivation in latently infected cells has received little attention. We showed that HIV-1 long terminal repeat (LTR) promoter activation can be induced by periodontopathogens in monocytes/macrophages; nevertheless, the mechanisms involved in this response remain undetermined. Since Toll-like receptor 2 (TLR2), TLR4, and TLR9 activation have been involved in HIV-1 recrudescence, we sought to determine the role of these TLRs in HIV-1 reactivation induced by the periodontal pathogens Fusobacterium nucleatum and Porphyromonas gingivalis using BF24 monocytes/macrophages stably transfected with the HIV-1 promoter driving chloramphenicol acetyltransferase (CAT) expression and THP89GFP cells, a model of HIV-1 latency. We demonstrated that TLR9 activation by F. nucleatum and TLR2 activation by both bacteria appear to be involved in HIV-1 reactivation; however, TLR4 activation had no effect. Moreover, the autocrine activity of tumor necrosis factor alpha (TNF-α) but not interleukin-1β (IL-1β) produced in response to bacteria could impact viral reactivation. The transcription factors NF-κB and Sp1 appear to be positively regulating HIV-1 reactivation induced by these oral pathogens. These results suggest that oral Gram-negative bacteria (F. nucleatum and P. gingivalis) associated with oral and systemic chronic inflammatory disorders enhance HIV-1 reactivation in monocytes/macrophages through TLR2 and TLR9 activation in a mechanism that appears to be transcriptionally regulated. Increased bacterial growth and emergence of these bacteria or their products accompanying chronic oral inflammatory diseases could be risk modifiers for viral replication, systemic immune activation, and AIDS progression in HIV-1+ patients.
PMCID: PMC2944464  PMID: 20610663
8.  Mitf Induction by RANKL Is Critical for Osteoclastogenesis 
Molecular Biology of the Cell  2010;21(10):1763-1771.
This study provides the first evidence that RANKL-induced Mitf is critical for osteoclastogenesis and Mitf is not completely redundant with Tfe3.
Microphthalmia-associated transcription factor (Mitf) regulates the development and function of several cell lineages, including osteoclasts. In this report, we identified a novel mechanism by which RANKL regulates osteoclastogenesis via induction of Mitf isoform E (Mitf-E). Both Mitf-A and Mitf-E are abundantly present in osteoclasts. Unlike Mitf-A, which is ubiquitously expressed and is present in similar amounts in macrophages and osteoclasts, Mitf-E is almost nondetectable in macrophages, but its expression is significantly up-regulated during osteoclastogenesis. In addition to their different expression profiles, the two isoforms are drastically different in their abilities to support osteoclastogenesis, despite sharing all known functional domains. Unlike Mitf-A, small amounts of Mitf-E are present in nuclear lysates unless chromatin is digested/sheared during the extraction. Based on these data, we propose a model in which Mitf-E is induced during osteoclastogenesis and is closely associated with chromatin to facilitate its interaction with target promoters; therefore, Mitf-E has a stronger osteoclastogenic activity. Mitf-A is a weaker osteoclastogenic factor, but activated Mitf-A alone is not sufficient to fully support osteoclastogenesis. Therefore, this receptor activator for nuclear factor-κB ligand (RANKL)-induced Mitf phenomenon seems to play an important role during osteoclastogenesis. Although the current theory indicates that Mitf and its binding partner Tfe3 are completely redundant in osteoclasts, using RNA interference, we demonstrated that Mitf has a distinct role from Tfe3. This study provides the first evidence that RANKL-induced Mitf is critical for osteoclastogenesis and Mitf is not completely redundant with Tfe3.
PMCID: PMC2869381  PMID: 20357005
9.  Subcellular localization of Mitf in monocytic cells 
Histochemistry and Cell Biology  2010;133(6):651-658.
Microphthalmia-associated transcription factor (Mitf) is a transcription factor that plays an important role in regulating the development of several cell lineages. The subcellular localization of Mitf is dynamic and is associated with its transcription activity. In this study, we examined factors that affect its subcellular localization in cells derived from the monocytic lineage since Mitf is present abundantly in these cells. We identified a domain encoded by Mitf exon 1B1b to be important for Mitf to commute between the cytoplasm and the nucleus. Deletion of this domain disrupts the shuttling of Mitf to the cytoplasm and results in its retention in the nucleus. M-CSF and RANKL both induce nuclear translocation of Mitf. We showed that Mitf nuclear transport is greatly influenced by ratio of M-CSF/Mitf protein expression. In addition, cell attachment to a solid surface also is needed for the nuclear transport of Mitf.
PMCID: PMC2869019  PMID: 20437053
M-CSF; Monocytic cells; Nuclear localization signal; Attachment; Transcription factor
10.  Identification of Novel Viral Interleukin-10 Isoforms of Human Cytomegalovirus AD169 
Virus research  2007;131(2):213-223.
Two products of human cytomegalovirus (HCMV) UL111a gene have been previously identified to resemble human IL-10 (hIL-10). These viral IL-10s (vIL-10s) are able to induce signal transduction events and biological activities in a variety of cells. In this study, five novel vIL-10 transcripts were identified from HCMV AD169 infected MRC-5 cells. Some vIL-10 isoforms were post-translationally glycosylated, depending on the existence of a predicted N-linked glycosylation site. Similar to hIL-10, four of the vIL-10 isoforms apparently formed putative dimers. Among the different vIL-10 isoforms, vIL-10A significantly induced the phosphorylation of transcription factor STAT3 in THP-1 cells. All identified vIL-10 isoforms were able to form complexes with hIL-10, and enhanced hIL-10-induced STAT3 phosphorylation in different degrees. Identification of diverse forms of vIL-10 suggests that HCMV has developed a sophisticated mechanism to interfere with hIL-10 signaling pathway.
PMCID: PMC2268987  PMID: 17976852
cytomegalovirus; IL-10; vIL-10
11.  Kaposi's Sarcoma-Associated Herpesvirus K-Cyclin Interacts with Cdk9 and Stimulates Cdk9-Mediated Phosphorylation of p53 Tumor Suppressor▿  
Journal of Virology  2007;82(1):278-290.
K-cyclin, encoded by Kaposi's sarcoma-associated herpesvirus, has previously been demonstrated to activate cyclin-dependent kinase 6 (Cdk6) to induce the phosphorylation of various cell cycle regulators. In this study, we identified Cdk9 as a new K-cyclin-associated Cdk and showed that K-cyclin interacted with Cdk9 through its basic domain. We hypothesized that K-cyclin served as a regulatory subunit for the activity of Cdk9. Recent reports show that Cdk9 phosphorylates tumor suppressor p53, and we found that the K-cyclin/Cdk9 interaction greatly enhanced the kinase activity of Cdk9 toward p53. The phosphorylation site(s) of K-cyclin/Cdk9 kinase complexes was mapped in the transactivation domain of p53. We showed that the ectopic expression of K-cyclin led to a sustained increase of p53 phosphorylation on Ser33 in vivo, and the phosphorylation could be inhibited by a dominant negative Cdk9 mutant, dn-Cdk9. Using p53-positive U2OS and p53-null SaOS2 cells, we demonstrated that K-cyclin-induced growth arrest was associated with the presence of p53. In addition, K-cyclin-induced p53-dependent growth arrest was rescued by the dn-Cdk9- or Cdk9-specific short hairpin RNA in SaOS2 cells. Together, our findings for the first time demonstrated the interaction of K-cyclin and Cdk9 and revealed a new molecular link between K-cyclin and p53.
PMCID: PMC2224387  PMID: 17942552
12.  Inhibition of p53 Tumor Suppressor by Viral Interferon Regulatory Factor 
Journal of Virology  2001;75(16):7572-7582.
The irreversible cell cycle arrest and apoptosis induced by p53 are part of the host surveillance mechanisms for viral infection and tumor induction. Kaposi's sarcoma-associated herpesvirus (KSHV), the most recently discovered human tumor virus, is associated with the pathogenesis of Kaposi's sarcoma, primary effusion lymphoma, and multicentric Castleman's disease. The K9 open reading frame of KSHV encodes a viral interferon (IFN) regulatory factor (vIRF) which functions as a repressor for cellular IFN-mediated signal transduction and as an oncoprotein to induce cell growth transformation. Here, we demonstrate that KSHV vIRF interacts with the cellular p53 tumor suppressor through the putative DNA binding region of vIRF and the central region of p53. This interaction suppresses the level of phosphorylation and acetylation of p53 and inhibits transcriptional activation of p53. As a consequence, vIRF efficiently prevents p53-mediated apoptosis. These results suggest that KSHV vIRF interacts with and inhibits the p53 tumor suppressor to circumvent host growth surveillance and to facilitate uncontrolled cell proliferation.
PMCID: PMC114992  PMID: 11462029
13.  Identification of the Novel K15 Gene at the Rightmost End of the Kaposi's Sarcoma-Associated Herpesvirus Genome 
Journal of Virology  2000;74(1):436-446.
Kaposi's sarcoma-associated herpesvirus (KSHV) encodes a distinct open reading frame called K15 at a position equivalent to the gene encoding LMP2A of Epstein-Barr virus (EBV). K15 isolates from body cavity-based lymphoma (BCBL) cells exhibited a dramatic sequence variation and a complex splicing pattern. However, all K15 alleles are organized similarly with the potential SH2 and SH3 binding motifs in their cytoplasmic regions. Northern blot analysis showed that K15 was weakly expressed in latently infected BCBL-1 cells, and the level of its expression was significantly induced by tetradecanoyl phorbol acetate stimulation. K15 encoded 40- to 55-kDa proteins, as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and was localized at the cytoplasm and plasma membrane. To demonstrate the signal-transducing activity of the K15 protein, we constructed a chimeric protein in which the cytoplasmic tail of the human CD8α polypeptide was replaced with that of KSHV K15. While the CD8-K15 chimera was not capable of eliciting cellular signal transduction upon stimulation with an anti-CD8 antibody, it significantly inhibited B-cell receptor signaling, as evidenced by a suppression of tyrosine phosphorylation and intracellular calcium mobilization. This inhibition required the putative SH2 or SH3 binding motif in the cytoplasmic region of K15. Biochemical study of CD8-K15 chimeras showed that the cytoplasmic region of K15 was constitutively tyrosine phosphorylated and that the tyrosine residue within the putative SH2 binding motif of K15 was a primary site of phosphorylation. These results demonstrate that KSHV K15 resembles LMP2A in genomic location, splicing pattern, and protein structure and by the presence of functional signal-transducing motifs in the cytoplasmic region. Thus, KSHV K15 is likely a distant evolutionary relative of EBV LMP2A.
PMCID: PMC111555  PMID: 10590133
14.  Identification of the R1 Oncogene and Its Protein Product from the Rhadinovirus of Rhesus Monkeys 
Journal of Virology  1999;73(6):5123-5131.
Rhesus monkey rhadinovirus (RRV) is a gamma-2 herpesvirus that is most closely related to the human Kaposi’s sarcoma-associated herpesvirus (KSHV). We have identified a distinct open reading frame at the left end of RRV and designated it R1. The position of the R1 gene is equivalent to that of the saimiri transforming protein (STP) of herpesvirus saimiri (HVS) and of K1 of KSHV, other members of the gamma-2 or rhadinovirus subgroup of herpesviruses. The R1 sequence revealed an open reading frame encoding a product of 423 amino acids that was predicted to contain an extracellular domain, a transmembrane domain, and a C-terminal cytoplasmic tail reflective of a type I membrane-bound protein. The predicted structural motifs of R1, including the presence of immunoreceptor tyrosine-based activation motifs, resembled those in K1 of KSHV but were distinct from those of STP. R1 sequences from four independent isolates from three different macaque species revealed 0.95 to 7.3% divergence over the 423 amino acids. Variation was located predominantly within the predicted extracellular domain. The R1 protein migrated at 70 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and was extensively glycosylated. Tagged R1 protein was localized to the cytoplasmic and plasma membranes of transfected cells. Expression of the R1 gene in Rat-1 fibroblasts induced morphologic changes and focus formation, and injection of R1-expressing cells into nude mice induced the formation of multifocal tumors. A recombinant herpesvirus in which the STP oncogene of HVS was replaced by R1 immortalized T lymphocytes to interleukin-2-independent growth. These results indicate that R1 is an oncogene of RRV.
PMCID: PMC112557  PMID: 10233975
15.  Role of Cellular Tumor Necrosis Factor Receptor-Associated Factors in NF-κB Activation and Lymphocyte Transformation by Herpesvirus Saimiri STP 
Journal of Virology  1999;73(5):3913-3919.
The STP oncoproteins of the herpesvirus saimiri (HVS) subgroup A strain 11 and subgroup C strain 488 are now found to be stably associated with tumor necrosis factor receptor-associated factor (TRAF) 1, 2, or 3. Mutational analyses identified residues of PXQXT/S in STP-A11 as critical for TRAF association. In addition, a somewhat divergent region of STP-C488 is critical for TRAF association. Mutational analysis also revealed that STP-C488 induced NF-κB activation that was correlated with its ability to associate with TRAFs. The HVS STP-C488 P10→R mutant was deficient in human T-lymphocyte transformation to interleukin-2-independent growth but showed wild-type phenotype for marmoset T-lymphocyte transformation in vitro and in vivo. The STP-C488 P10→R mutant was also defective in Rat-1 fibroblast transformation, and fibroblast cell transformation was blocked by a TRAF2 dominant-negative mutant. These data implicate TRAFs in STP-C488-mediated transformation of human lymphocytes and rodent fibroblasts. Other factors are implicated in immortalization of common marmoset T lymphocytes and may also be critical in the transformation of human lymphocytes and rodent fibroblasts.
PMCID: PMC104169  PMID: 10196286
16.  Identification and Characterization of Kaposi’s Sarcoma-Associated Herpesvirus K8.1 Virion Glycoprotein 
Journal of Virology  1999;73(2):1341-1349.
Kaposi’s sarcoma-associated herpesvirus (KSHV) has been consistently identified in Kaposi’s sarcomas (KS), body cavity-based lymphomas (BCBL), and some forms of Castleman’s disease. Previous serological tests with KS patient sera have detected lytic-cycle polypeptides from KSHV-infected BCBL cells. We have found that these polypeptides are predominantly encoded by the K8.1 open reading frame, which is present in the same genomic position as virion envelope glycoproteins of other gammaherpesviruses. The cDNA of K8.1 from BCBL-1 cells was found to encode a glycosylated protein with an apparent molecular mass of 37 kDa. K8.1 was found to be expressed during lytic KSHV replication in BCBL-1 cells and was localized on the surface of cells and virions. The results of immunofluorescence and immunoelectron microscopy suggest that KSHV acquires K8.1 protein on its virion surface during the process of budding at the plasma cell membrane. When KSHV K8.1 derived from mammalian cells was used as an antigen in immunoblot tests, antibodies to K8.1 were detected in 18 of 20 KS patients and in 0 of 10 KS-negative control subjects. These results demonstrate that the K8.1 gene encodes a KSHV virion-associated glycoprotein and suggest that antibodies to K8.1 may prove useful as contributory serological markers for infection by KSHV.
PMCID: PMC103958  PMID: 9882339
17.  Identification of an Immunoreceptor Tyrosine-Based Activation Motif of K1 Transforming Protein of Kaposi’s Sarcoma-Associated Herpesvirus 
Molecular and Cellular Biology  1998;18(9):5219-5228.
Kaposi’s sarcoma-associated herpesvirus (KSHV) is consistently identified in Kaposi’s sarcoma and body cavity-based lymphoma. KSHV encodes a transforming protein called K1 which is structurally similar to lymphocyte receptors. We have found that a highly conserved region of the cytoplasmic domain of K1 resembles the sequence of immunoreceptor tyrosine-based activation motifs (ITAMs). To demonstrate the signal-transducing activity of K1, we constructed a chimeric protein in which the cytoplasmic tail of the human CD8α polypeptide was replaced with that of KSHV K1. Expression of the CD8-K1 chimera in B cells induced cellular tyrosine phosphorylation and intracellular calcium mobilization upon stimulation with an anti-CD8 antibody. Mutational analyses showed that the putative ITAM of K1 was required for its signal-transducing activity. Furthermore, tyrosine residues of the putative ITAM of K1 were phosphorylated upon stimulation, and this allowed subsequent binding of SH2-containing proteins. These results demonstrate that the KSHV transforming protein K1 contains a functional ITAM in its cytoplasmic domain and that it can transduce signals to induce cellular activation.
PMCID: PMC109107  PMID: 9710606
18.  Kaposi’s Sarcoma-Associated Herpesvirus Viral Interferon Regulatory Factor 
Journal of Virology  1998;72(7):5433-5440.
Interferons (IFNs) are a family of multifunctional cytokines with antiviral activities. The K9 open reading frame of Kaposi’s sarcoma-associated herpesvirus (KSHV) exhibits significant homology with cellular IFN regulatory factors (IRFs). We have investigated the functional consequence of K9 expression in IFN-mediated signal transduction. Expression of K9 dramatically repressed transcriptional activation induced by IFN-α, -β, and -γ. Further, it induced transformation of NIH 3T3 cells, resulting in morphologic changes, focus formation, and growth in reduced-serum conditions. The expression of antisense K9 in KSHV-infected BCBL-1 cells consistently increased IFN-mediated transcriptional activation but drastically decreased the expression of certain KSHV genes. Thus, the K9 gene of KSHV encodes the first virus-encoded IRF (v-IRF) which functions as a repressor for cellular IFN-mediated signal transduction. In addition, v-IRF likely plays an important role in regulating KSHV gene expression. These results suggest that KSHV employs an unique mechanism to antagonize IFN-mediated antiviral activity by harboring a functional v-IRF.
PMCID: PMC110176  PMID: 9620998

Results 1-18 (18)