The interaction between p53 and Mdm2 is independent of MEG3-p53 association

The ability of the long noncoding RNA MEG3 to suppress cell proliferation led to its recognition as a tumor suppressor. MEG3 has previously been shown to bind to p53 in vitro, which led us to hypothesize that MEG3 functions by disrupting the interaction of p53 and its E3 ubiquitin ligase Mdm2. To test this hypothesis in vivo, we built a cross-nearest neighbor/Monte Carlo analytical method based on two color direct stochastic optical reconstruction microscopy (dSTORM), a single-molecule localization microscopy (SMLM) technique. Our data support the interaction of MEG3 and p53. Surprisingly, this association had no effect on the binding of p53 and Mdm2, distinct from the most commonly proposed model for the mechanism of MEG3 action. Additionally, our mathematical approach to analyzing SMLM data has general applicability to assessing molecular interactions in a native cellular context.