Epstein-Barr Virus Nuclear Antigen 3C Interacts with and Enhances the Stability of the c-Myc Oncoprotein

Bajaj, Bharat; Murakami, Masanao; Cai, Qiliang; Verma, Subhash C.; Lan, Ke; Robertson, Erle S.

doi:10.1128/jvi.02500-07

Cited by 61 publications

(85 citation statements)

References 44 publications

(88 reference statements)

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…HEK 293T cells were transfected by electroporation with a Bio-Rad Gene Pulser II electroporator. Briefly, 15 ϫ 10 6 cells harvested in exponential phase were collected, washed in phosphate-buffered saline (PBS), and resuspended in 400 l of the appropriate medium without serum containing DNA for transfection (3,35). Resuspended cells were transferred to an 0.4-cmgap cuvette, and electroporation was performed at 975 F and 210 V for HEK 293T cells.…”

Section: Methodsmentioning

confidence: 99%

“…pA3M or pA3F-EBNA3C constructs express either full-length EBNA3C or different truncated versions of EBNA3C with either a Myc tag or a Flag tag at the carboxy-terminal end, as described previously (3,37). Glutathione S-transferase (GST)-EBNA3C truncation mutants have been previously described (3). The C143N point mutation in the EBNA3C gene was prepared by a standard PCR primer mutagenesis method.…”

Section: Methodsmentioning

confidence: 99%

“…We have previously shown that the EBNA3C amino-terminal domain (especially residues 100 to 200) can bind to a number of important cell cycle-regulatory molecules (3,35,37). To further map the interacting domain within the Nterminal region of EBNA3C, in vitro-translated 35 S-radiolabeled fragments of EBNA3C (residues 1 to 100, 1 to 129, 1 to 159, and 1 to 200) were tested.…”

Section: Ebna3c Forms a Complex With Mdm2 Both In Vivo And In Vitromentioning

confidence: 99%

See 2 more Smart Citations

Epstein-Barr Virus Nuclear Antigen 3C Augments Mdm2-Mediated p53 Ubiquitination and Degradation by Deubiquitinating Mdm2

Saha

Murakami

Kumar

et al. 2009

J Virol

Self Cite

102

160

View full text Add to dashboard Cite

Epstein-Barr virus (EBV) nuclear antigen 3C (EBNA3C) is one of the essential latent antigens for primary B-cell transformation. Previous studies established that EBNA3C facilitates degradation of several vital cell cycle regulators, including the retinoblastoma (pRb) and p27KIP proteins, by recruitment of the SCF Skp2 E3 ubiquitin ligase complex. EBNA3C was also shown to be ubiquitinated at its N-terminal residues. Furthermore, EBNA3C can bind to and be degraded in vitro by purified 20S proteasomes. Surprisingly, in lymphoblastoid cell lines, EBNA3C is extremely stable, and the mechanism for this stability is unknown. In this report we show that EBNA3C can function as a deubiquitination enzyme capable of deubiquitinating itself in vitro as well as in vivo. Functional mapping using deletion and point mutational analysis showed that both the N-and C-terminal domains of EBNA3C contribute to the deubiquitination activity. We also show that EBNA3C efficiently deubiquitinates Mdm2, an important cellular proto-oncogene, which is known to be overexpressed in several human cancers. The data presented here further demonstrate that the N-terminal domain of EBNA3C can bind to the acidic domain of Mdm2. Additionally, the N-terminal domain of EBNA3C strongly stabilizes Mdm2. Importantly, EBNA3C simultaneously binds to both Mdm2 and p53 and can form a stable ternary complex; however, in the presence of p53 the binding affinity of Mdm2 toward EBNA3C was significantly reduced, suggesting that p53 and Mdm2 might share a common overlapping domain of EBNA3C. We also showed that EBNA3C enhances the intrinsic ubiquitin ligase activity of Mdm2 toward p53, which in turn facilitated p53 ubiquitination and degradation. Thus, manipulation of the oncoprotein Mdm2 by EBNA3C potentially provides a favorable environment for transformation and proliferation of EBV-infected cells.

show abstract

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Ebna3c Forms a Complex With Mdm2 Both In Vivo And In Vitromentioning

confidence: 99%

See 1 more Smart Citation

Epstein-Barr Virus Nuclear Antigen 3C Augments Mdm2-Mediated p53 Ubiquitination and Degradation by Deubiquitinating Mdm2

Saha

Murakami

Kumar

et al. 2009

J Virol

Self Cite

102

160

View full text Add to dashboard Cite

show abstract

“…A large number of earlier studies have successfully established that EBNA3C, an indispensable oncoprotein required for EBV-mediated B-cell transformation, strongly interferes with the functions of many important cellular proteins which are principally involved in cell cycle checkpoints at both the G 1 -to-S and G 2 -to-M transitions (1,6,7,22). Recently, in an initial study, we clearly showed that EBNA3C directly interacts with p53 and efficiently blocks its transcriptional as well as apoptotic activities (23).…”

Section: Discussionmentioning

confidence: 99%

“…Furthermore, EBNA3C interacts with a vast range of transcriptional modulators, including PU.1, Spi-B, HDAC1, CtBP, DP103, p300, prothymosin-␣, Nm23-H1, SUMO1, and SUMO3 (15,22,23). EBNA3C also plays a critical role in deregulating the mammalian cell cycle by targeting several cellular oncoproteins and tumor suppressors (1,7,8). Recently, we have shown that EBNA3C directly binds to p53 tumor suppressors and represses their apoptotic and transcriptional activities (23).…”

mentioning

confidence: 99%