ABSTRACT: Population of viral small RNAs expressed in common marmoset (Callithrix jacchus) T cells latently infected with Herpesvirus saimiri (strain A11)
Project description:We report the discovery of six novel miRNAs expressed by Herpesvirus saimiri (strain A11). These miRNAs are generated by a non-canonical biogenesis pathway that does not require the Microprocessor complex. Examination of one sample prepared from common marmoset (Callithrix jacchus) T cells latently infected with Hespesvirus saimiri (strain A11).
Project description:We report the discovery of six novel miRNAs expressed by Herpesvirus saimiri (strain A11). These miRNAs are generated by a non-canonical biogenesis pathway that does not require the Microprocessor complex.
Project description:In latently-infected marmoset T cells, Herpesvirus saimiri (HVS) expresses six microRNAs (known as miR-HSURs). The viral miR-HSURs are processed from chimeric primary transcripts, each containing a noncoding U-rich RNA (HSUR) and a pre-miRNA hairpin. To uncover functions of miR-HSURs, we identified mRNA targets in infected cells using High-Throughput Sequencing of RNA Isolated by Crosslinking Immunoprecipitation (HITS-CLIP). HITS-CLIP revealed hundreds of robust Argonaute (Ago) binding sites mediated by miR-HSURs in the host genome, but few in the HVS genome. Gene Ontology analysis showed that several pathways regulating the cell cycle are enriched among cellular targets of miR-HSURs. Interestingly, miR-HSUR4-3p represses expression of the p300 transcriptional co-activator by binding the open reading frame of its mRNA. miR-HSUR5-3p directly regulates BiP, an endoplasmic reticulum (ER) localized chaperone facilitating maturation of the Major Histocompatibility Complex I (MHC I) and the antiviral response. miR-HSUR5-3p also robustly downregulates WEE1, a key negative regulator of cell-cycle progression, leading to reduced phosphorylation of its substrate cyclin-dependent kinase (Cdk1). Consistently, inhibition of miR-HSUR5-3p in HVS-infected cells decreases their proliferation. Together, our results shed light on the roles of viral miRNAs in cellular transformation and viral latency.
Project description:Viruses express several classes of non-coding (nc) RNAs1. For most of them, the functions and mechanisms by which they act are unknown. Herpesvirus saimiri (HVS), a g-herpesvirus that establishes latency in T cells of New World primates and has the ability to cause aggressive leukemias and lymphomas in non-natural hosts2, expresses seven small nuclear (sn), U-rich ncRNAs called HSURs in latently infected cells3-5. HSURs associate with Sm proteins and share biogenesis and structural features with cellular Sm-class snRNAs4,6. One of these viral snRNAs, HSUR 2, base-pairs with two host microRNAs (miRNAs), miR-142-3p and miR-167. However, HSUR 2 does not affect the abundance or activity of these two cellular miRNAs, suggesting alternative functions for these interactions. Here we show that HSUR 2 also base-pairs with messenger RNAs (mRNAs) in infected cells. We combined in vivo psoralen-mediated RNA-RNA crosslinking and high-throughput sequencing to identify mRNAs targeted by HSUR 2. HSUR 2 targets include mRNAs encoding Retinoblastoma (pRb) and factors involved in p53 signaling and apoptosis. We show that HSUR 2 represses expression of target mRNAs. Base-pairing between HSUR 2 and miR-142-3p and miR-16 is essential for HSUR 2-mediated mRNA repression, suggesting that HSUR 2 recruits these two cellular miRNAs to target mRNAs. Moreover, we show that HSUR 2 utilizes this mechanism to inhibit apoptosis. Our results uncover a role for a viral Sm-class RNA as a miRNA adaptor in post pre-mRNA-processing regulation of gene expression.
Project description:We compared gene expression patterns between the occipital cortex tissues of four male and four female individuals in three species: an ape (human, Homo sapiens), an Old World monkey (macaque; Macaca fascicularis), and a New World monkey (marmoset; Callithrix jacchus). To do so, we hybridized cDNA from each sample (n = 24) to a human cDNA microarray that contains 46,128 probes. (Human 46k cDNA, http://www.biotech.kth.se/molbio/microarray/). We used a loop hybridization study design restricted to within-species comparisons only, in which we co-hybridized on each slide samples from the opposite sex.
Project description:In primates, high-acuity vision is mediated by the fovea, a small specialized central region of the retina. The fovea, unique to the anthropoid lineage among mammals, undergoes notable neuronal morphological changes during postnatal maturation. However, the degree of cellular similarity across anthropoid foveas and the molecular underpinnings of foveal maturation remain unclear. Here, we used high throughput single cell RNA sequencing (scRNA-seq) to profile retinal cells of the common marmoset (Callithrix jacchus), an early divergent in anthropoid evolution from humans, apes, and macaques. We generated atlases of the marmoset fovea and peripheral retina for both neonates and adults.
