PINT lincRNA connects the p53 pathway with epigenetic silencing by the Polycomb Repressive Complex 2 (tissue)

It has been recently shown that the transcription factor p53 induces the expression of multiple lincRNAs. However, relatively little is known about the role that lincRNAs play in this pathway. Here we characterize a lincRNA named PINT (p53 Induced Noncoding Transcript). We show that PINT is a ubiquitously expressed lincRNA that is finely regulated by p53. In mouse cells, PINT promotes cell proliferation and survival by regulating the expression of genes of TGF-beta, MAPK and p53 pathways. PINT is a nuclear lincRNA that directly interacts with Polycomb Repressive Complex 2 (PRC2), being required for PRC2 targeting of specific genes for repression. Furthermore, PINT functional activity is dependent on PRC2 expression, representing a connection between the p53 pathway and epigenetic regulation by PRC2. We have also identified PINT human ortholog (hPINT), which presents suggestive analogies with the mouse lincRNA. hPINT is similarly regulated by p53, and its expression correlates significantly with the same cellular pathways as the mouse ortholog, including the p53 pathway. Interestingly, hPINT is significantly downregulated in colon cancer, representing a novel tumor suppressor candidate. Our results not only help our understanding of the role of p53 and lincRNAs in cancer, but also contribute to the open debate regarding the utility of mouse models for the study of lincRNAs. Normal tissue located at least 20 cm away from a tumor was obtained through surgical resection from patients of colorectal cancer. Total RNA was extracted and subjected to microarray analysis.