KSHV vFLIP interacts with the itch/A20 ubiquitin-editing complex via a SUMO dependent mechanism

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Towson University Graduate Theses and Dissertations

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2016-11-02

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Towson University. Department of Biological Sciences

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Abstract

KSHV is known to cause Kaposi Sarcoma (KS), and has been implicated in two B-cell lymphoproliferative disorders. We have previously demonstrated that expression of RTA, the lytic switch protein, results in the proteasomal degradation of vFLIP (Viral FLICE Inhibitory Protein) and down regulation of NF-κB associated gene expression early in lytic reactivation. We have also demonstrated that RTA interacts with the cellular Itch/A20 complex and that Itch and A20 are required to induce degradation of vFLIP. Here we provide evidence for vFLIP interaction with Itch and A20 via a SUMO-dependent mechanism. We have identified a SUMO interaction motif (SIM) in vFLIP through sequence analysis and demonstrate that a SIM deficient vFLIP cannot interact with SUMO. SIM deficient vFLIP is unable to activate NF-kB. Preliminary studies suggest that Itch is SUMOylated and cannot interact with SIM-deficient vFLIP. This suggests that the Itch/A20 complex may interact with vFLIP via a SUMO-dependent mechanism.