PML isoforms IV and V contribute to adenovirus-mediated oncogenic transformation by functionally inhibiting the tumor-suppressor p53

Abstract

Although modulation of the cellular tumor-suppressor p53 is considered to have the major role in E1A/E1B-55K-mediated tumorigenesis, other promyelocytic leukemia nuclear body (PML-NB)/PML oncogenic domain (POD)-associated factors including SUMO, Mre11, Daxx, as well as the integrity of these nuclear bodies contribute to the transformation process. However, the biochemical consequences and oncogenic alterations of PML-associated E1B-55K by SUMO-dependent PML-IV and PML-V interaction have so far remained elusive. We performed mutational analysis to define a PML interaction motif within the E1B-55K polypeptide. Our results showed that E1B-55K/PML binding is not required for p53, Mre11 and Daxx interaction. We also observed that E1B-55K lacking subnuclear PML localization because of either PML-IV or PML-V-binding deficiency was no longer capable of mediating E1B-55K-dependent SUMOylation of p53, inhibition of p53-mediated transactivation or efficiently transforming primary rodent cells. These results together with the observation that E1B-55K-dependent SUMOylation of p53 is required for efficient cell transformation, provides evidence for the idea that the SUMO ligase activity of the E1B-55K viral oncoprotein is intimately linked to its growth-promoting oncogenic activities.

KAP1 Is a Host Restriction Factor That Promotes Human Adenovirus E1B-55K SUMO Modification

“…Studies from Pennella and coworkers suggest that E1B-55K is also a p53-SUMO1 E3 ligase (63). In line with this, we recently showed that E1B-55K SUMOylation and, hence, PML-NB localization are prerequisites for the SUMO ligase activity of the viral protein (31). However, the detailed mechanism of how E1B-55K mediates the SUMOylation of other proteins is still not fully understood.…”

“…KAP1 point mutations were introduced by site-directed mutagenesis using the primers shown in Table 1. For transient transfection, subconfluent cells were treated with a transfection mixture of DNA and 25-kDa linear polyethylenimine as described recently (31).…”

PMLIV overexpression promotes TGF‐β‐associated epithelial–mesenchymal transition and migration in MCF‐7 cancer cells

“…Despite being one of the least abundant isoforms, PMLIV has been the most intensively studied PML isoform so far, gaining attention because of its ability to mediate p53‐induced senescence and apoptosis (Bernardi, Papa, & Pandolfi, ; Wimmer et al, ). Numerous studies have identified that PMLIV ‐induced senescence involves stabilization and activation of p53 through phosphorylation at Ser 46 and acetylation at Lys 382 (Ivanschitz et al, ).…”

“…Scale bar = 20 μm. co-IP, coimmunoprecipitation; DAPI, 4,6-diamidino-2-phenylindole; GADPH, glyceraldehyde 3-phosphate dehydrogenase; ns, not significant; MCF-7, Michigan Cancer Foundation-7; PML, promyelocytic leukemia; TGF-β1, transforming growth factor-β1 [Color figure can be viewed at wileyonlinelibrary.com] because of its ability to mediate p53-induced senescence and apoptosis (Bernardi, Papa, & Pandolfi, 2008;Wimmer et al, 2016).…”

Viral Interplay with the Host Sumoylation System

“…Since E1B-55K, in conjunction with E4orf6, mediates ubiquitinylation and proteasomal degradation of p53, this was the first example of a viral protein having dual activity in both the ubiquitin and SUMO pathways. Mutation of the p53 sumoylation site decreased the ability of E1B-55K to repress the transcriptional activity of p53 and to tether p53 in PML bodies (Pennella et al 2010;Wimmer et al 2016). These results demonstrate that the E1B-55K protein induced sumoylation is functionally relevant and contributes to the overall abrogation of p53 defenses in the adenoviral infected cell.…”