Overview of the phosphorylation pathways inhibits by ORFV002.

<p>Binding of TNF to its receptor (TNF-R) causes TNF-R to phosphorylate IκBα, and NF-κB p65 at Ser⁵³⁶, freeing NF-κB p50/p65 (pSer⁵³⁶) from IκBα, and allowing NF-κB p50/p65 (pSer⁵³⁶) to translocate to the nucleus. After stimulation by TNF p38 and ERK MAPK kinases were also activated, both of which can activate MSK1 independently, with maximal activation requiring phosphorylation of MSK1 by both kinases. In the nucleus, activated MSK1 phosphorylates NF-κB p65 at Ser²⁷⁶, resulting in fully functional NF-κB that can interact with other transcriptional activators, such as p300, to drive transcription of NF-κB-regulated genes. Wild type ORFV002 (002GFP) and C-terminal deletion mutants of ORFV002 (002GM3 and 002GM4) can block MSK1 phosphorylation of NF-κB p65 at Ser²⁷⁶, while N-terminal deletion mutants of ORFV002 (002GM1 and 002GM2) cannot. SB203580, PD98059, and H89 are inhibitors of p38 activation of MSK1, MAPK activation of MSK1 and the ability of activate MSK1 to phosphorylate NF-κB p65, respectively (See Ref <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0058854#pone.0058854-Vermeulen1" target="_blank">[20]</a>).