Article

Cloning and Identification of a MicroRNA Cluster within the Latency-Associated Region of Kaposi's Sarcoma-Associated Herpesvirus

Department of Molecular Genetics and Microbiology, University of Florida, Gainesville, FL 32610, USA.
Journal of Virology (Impact Factor: 4.44). 08/2005; 79(14):9301-5. DOI: 10.1128/JVI.79.14.9301-9305.2005
Source: PubMed

ABSTRACT

MicroRNAs (miRNAs) are small, noncoding regulatory RNA molecules that bind to 3′ untranslated regions (UTRs) of mRNAs to either
prevent their translation or induce their degradation. Previously identified in a variety of organisms ranging from plants
to mammals, miRNAs are also now known to be produced by viruses. The human gammaherpesvirus Epstein-Barr virus has been shown
to encode miRNAs, which potentially regulate both viral and cellular genes. To determine whether Kaposi's sarcoma-associated
herpesvirus (KSHV) encodes miRNAs, we cloned small RNAs from KSHV-positive primary effusion lymphoma-derived cells and endothelial
cells. Sequence analysis revealed 11 isolated RNAs of 19 to 23 bases in length that perfectly align with KSHV. Surprisingly,
all candidate miRNAs mapped to a single genomic locale within the latency-associated region of KSHV. These data suggest that
viral and host cellular gene expression may be regulated by miRNAs during both latent and lytic KSHV replication.

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Available from: Rebecca L Skalsky
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    • "The oncogenic Kaposi's sarcoma-associated herpesvirus (KSHV) infects B cells and endothelial cells to cause lymphoproliferative disorders and the AIDS-defining cancer Kaposi's sarcoma, respectively . Like many other herpesviruses, KSHV expresses its own set of ∼20 mature miRNAs (Cai et al. 2005; Pfeffer et al. 2005; Samols et al. 2005; Grundhoff et al. 2006; Umbach and Cullen 2010). These microRNAs include known viral mimics of cellular miR-155 and miR-23 (Gottwein et al. 2007; Skalsky et al. 2007; Manzano et al. 2013). "
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    ABSTRACT: Sequence heterogeneity at the ends of mature microRNAs (miRNAs) is well documented, but its effects on miRNA function are largely unexplored. Here we studied the impact of miRNA 5'-heterogeneity, which affects the seed region critical for target recognition. Using the example of miR-142-3p, an emerging regulator of the hematopoietic lineage in vertebrates, we show that naturally coexpressed 5'-variants (5'-isomiRs) can recognize largely distinct sets of binding sites. Despite this, both miR-142-3p isomiRs regulate exclusive and shared targets involved in actin dynamics. Thus, 5'-heterogeneity can substantially broaden and enhance regulation of one pathway. Other 5'-isomiRs, in contrast, recognize largely overlapping sets of binding sites. This is exemplified by two herpesviral 5'-isomiRs that selectively mimic one of the miR-142-3p 5'-isomiRs. We hypothesize that other cellular and viral 5'-isomiRs can similarly be grouped into those with divergent or convergent target repertoires, based on 5'-sequence features. Taken together, our results provide a detailed characterization of target recognition by miR-142-3p and its 5'-isomiR-specific viral mimic. We furthermore demonstrate that miRNA 5'-end variation leads to differential targeting and can thus broaden the target range of miRNAs. © 2015 Manzano et al.; Published by Cold Spring Harbor Laboratory Press for the RNA Society.
    Preview · Article · Jul 2015 · RNA
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    • "However, it has yet to be revealed if LANA1 functions in this manner in DC. HHV-8 also produces multiple microRNAs, all of which are encoded within latency-associated genes (Samols et al., 2005), and are detectable in latently infected B cell lines suggesting that they play a role in inducing and/or maintenance of HHV-8 latency (Cai et al., 2005). However, their impact on DC function is not clear and could be studied with RNA silencing technology. "
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    ABSTRACT: Human herpesvirus 8 (HHV-8; Kaposi's sarcoma-associated herpesvirus) is an oncogenic gammaherpesvirus that primarily infects cells of the immune and vascular systems. HHV-8 interacts with and targets professional antigen presenting cells and influences their function. Infection alters the maturation, antigen presentation, and immune activation capabilities of certain dendritic cells (DC) despite non-robust lytic replication in these cells. DC sustains a low level of antiviral functionality during HHV-8 infection in vitro. This may explain the ability of healthy individuals to effectively control this virus without disease. Following an immune compromising event, such as organ transplantation or human immunodeficiency virus type 1 infection, a reduced cellular antiviral response against HHV-8 compounded with skewed DC cytokine production and antigen presentation likely contributes to the development of HHV-8 associated diseases, i.e., Kaposi's sarcoma and certain B cell lymphomas. In this review we focus on the role of DC in the establishment of HHV-8 primary and latent infection, the functional state of DC during HHV-8 infection, and the current understanding of the factors influencing virus-DC interactions in the context of HHV-8-associated disease.
    Full-text · Article · Aug 2014 · Frontiers in Microbiology
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    • "One possible mechanism for inducing viral lytic genes is through repression of KSHV-encoded microRNAs (miRNAs). Thus far, 12 KSHV pre-miRNAs, encoding 18 mature miRNAs have been identified [23]–[25]. Recent published data demonstrate a role for KSHV miRNAs including miR-K12-1, 3, 4, 5, 9 and 11, in the regulation of viral “latent-lytic switch” in KSHV-infected cells (mostly for maintaining viral latency in host cells), through either direct targeting viral lytic reactivation activator, RTA [26], [27], or indirect mechanisms including targeting varied host factors including IκBα, nuclear factor I/B (NFIB) and IKKε [28]–[30]. Therefore, we sought to determine whether higher expressional levels of lytic genes in ascites cells were due to changes in the viral miRNA profile. "
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    ABSTRACT: Kaposi's sarcoma-associated herpesvirus is the causative agent of primary effusion lymphoma (PEL), which arises preferentially in the setting of infection with human immunodeficiency virus (HIV). Even with standard cytotoxic chemotherapy, PEL continues to cause high mortality rates, requiring the development of novel therapeutic strategies. PEL xenograft models employing immunodeficient mice have been used to study the in vivo effects of a variety of therapeutic approaches. However, it remains unclear whether these xenograft models entirely reflect clinical presentations of KSHV(+) PEL, especially given the recent description of extracavitary solid tumor variants arising in patients. In addition, effusion and solid tumor cells propagated in vivo exhibit unique biology, differing from one another or from their parental cell lines propagated through in vitro culture. Therefore, we used a KSHV(+) PEL/BCBL-1 xenograft model involving non-obese diabetic/severe-combined immunodeficient (NOD/SCID) mice, and compared characteristics of effusion and solid tumors with their parent cell culture-derived counterparts. Our results indicate that although this xenograft model can be used for study of effusion and solid lymphoma observed in patients, tumor cells in vivo display unique features to those passed in vitro, including viral lytic gene expression profile, rate of solid tumor development, the host proteins and the complex of tumor microenvironment. These items should be carefully considered when the xenograft model is used for testing novel therapeutic strategies against KSHV-related lymphoma.
    Full-text · Article · Feb 2014 · PLoS ONE
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