Kaposi's Sarcoma Herpesvirus Upregulates Aurora A Expression to Promote p53 Phosphorylation and Ubiquitylation

Abstract

Aberrant expression of Aurora A kinase has been frequently implicated in many cancers and contributes to chromosome instability and phosphorylation-mediated ubiquitylation and degradation of p53 for tumorigenesis. Previous studies showed that p53 is degraded by Kaposi's sarcoma herpesvirus (KSHV) encoded latency-associated nuclear antigen (LANA) through its SOCS-box (suppressor of cytokine signaling, LANASOCS) motif-mediated recruitment of the EC5S ubiquitin complex. Here we demonstrate that Aurora A transcriptional expression is upregulated by LANA and markedly elevated in both Kaposi's sarcoma tissue and human primary cells infected with KSHV. Moreover, reintroduction of Aurora A dramatically enhances the binding affinity of p53 with LANA and LANASOCS-mediated ubiquitylation of p53 which requires phosphorylation on Ser215 and Ser315. Small hairpin RNA or a dominant negative mutant of Aurora A kinase efficiently disrupts LANA-induced p53 ubiquitylation and degradation, and leads to induction of p53 transcriptional and apoptotic activities. These studies provide new insights into the mechanisms by which LANA can upregulate expression of a cellular oncogene and simultaneously destabilize the activities of the p53 tumor suppressor in KSHV-associated human cancers.

EBNA3C-Mediated Regulation of Aurora Kinase B Contributes to Epstein-Barr Virus-Induced B-Cell Proliferation through Modulation of the Activities of the Retinoblastoma Protein and Apoptotic Caspases

“…While deregulation of AK-B has earlier been shown to be associated with many human cancers, the functional role for AK-B in EBV-mediated human cancers has not been extensively explained. Recently, a study from our lab showed that the Aurora kinase A (AK-A), the first member of the AK family, was functionally regulated by the latency-associated nuclear antigen (LANA) in Kaposi's sarcoma-associated herpesvirus (KSHV)-associated viral oncogenesis (27). However, a role for the other AK-B family members in gammaherpesvirus-infected cells remains to be explored.…”

“…The CFAR Immunology Core maintains an Institutional Review Board (IRB)-approved protocol in which Declaration of Helsinki protocols are strictly followed. Every donor gave written and informed consent at the CFAR Immunology Core (27).…”

“…Reporter assays were performed as reported earlier (27,34). In brief, cells were transfected with specific plasmids.…”

“…Additionally, a pCMV␤gal construct was also transfected to obtain a measure of transfection efficiency. Cell harvesting and luciferase activity determination were performed as previously described (27). For the ␤-galactosidase (␤-gal) assay, we used 380 l cell lysate plus 40 l 10ϫ ␤-gal assay reagent (8.8 mg/ml o-nitrophenyl-␤-D-galactopyranoside, 10 mM MgCl 2 , and 0.45 M ␤-mercaptoethanol in 1ϫ PBS).…”

p53 Tumor Suppressor Protein Stability and Transcriptional Activity Are Targeted by Kaposi's Sarcoma-Associated Herpesvirus-Encoded Viral Interferon Regulatory Factor 3

“…Also latency-associated nuclear antigen (LANA) forms complexes with p53 in the nuclei of latently infected cells (84) and induces p53 ubiquitination and degradation (85,86). Moreover, LANA markedly elevates the expression of Aurora A oncogenic kinase, which leads to phosphorylation of p53 at S215 and S315 and subsequent p53 ubiquitination and proteasome-mediated degradation (87). Thus, KSHV developed…”