The oncogenic virus Kaposi’s sarcoma-associated herpesvirus (KSHV) is the aetiological agent of Kaposi’s sarcoma (KS). The majority of KSHV infections result in latency, which allows for a persistent host cell infection. During latency, only a limited number of viral genes and at least 12 KSHV microRNAs (miRNAs), ten of which form a cluster, are co-expressed from the KSHV Latency Associated Region. The aim of this project was to investigate the molecular mechanisms and consequences of KSHV miRNA-mediated regulation of cellular signaling. To identify signaling pathways that are altered by KSHV miRNA cluster expression, a Collaborative Enzyme Enhanced Reactive ImmunoAssay (CEER) was performed in lymphatic endothelial cells (LECs) expressing the KSHV miRNA cluster versus control. In addition, a PepChip Kinomics Array in KSHV miRNA cluster expressing LECs was analysed to find signaling pathways that were affected by KSHV miRNA cluster expression. Data from both screens together suggested the regulation of the ERK-TAL1 signaling pathway by the KSHV miRNA cluster. Subsequent experimental validations in LECs and 293T cells showed that the ERK signaling pathway is indeed negatively regulated by the KSHV miRNA cluster through increasing RAF1 S43 phosphorylation. Moreover, KSHV miRNA cluster expression decreases TAL1 S122 phosphorylation and increases total TAL1 protein levels in LECs. 293T cells that exogenously express TAL1 also show an increase in TAL1 protein levels upon KSHV miRNA cluster induction. Interestingly, the RTA promoter was shown to contain a putative binding site for TAL1, which could suggest a potential role for TAL1 in the regulation of the RTA, as well as in the maintenance of KSHV latency. Taken together, the outcome of this PhD project identified the ERK-TAL1 signaling pathway as a novel pathway targeted by the KSHV miRNA cluster and added insights to the role of TAL1 in KS.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:644429 |
| Date | January 2015 |
| Creators | Kaufman, R. |
| Publisher | University College London (University of London) |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://discovery.ucl.ac.uk/1463969/ |
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