p53 upregulated regulator of p53 levels (PURPL)

PURPL (p53 upregulated regulator of p53 levels) is a human long intergenic non-coding RNA (lincRNA) induced by p53 following DNA damage and is encoded by the genomic locus LOC643401/LINC01021/RP11-46C20.1. PURPL is nuclear-localized and forms a negative feedback loop with p53: it is transcriptionally activated by p53 and, in turn, suppresses basal p53 protein levels. Mechanistically, PURPL sequesters the protein MYBBP1A (which stabilizes and activates p53) via an adaptor RNA-binding protein, HuR, thereby inhibiting MYBBP1A's binding to p53 and limiting p53 stabilization[1]. Knockout or knockdown of PURPL increases p53 levels and impairs proliferation and tumorigenicity of colorectal cancer cells both in vitro and in vivo[1][2]. High expression of PURPL is associated with cancer cell survival and resistance to chemotherapeutic stress. PURPL does not encode a protein and is not a canonical drug target such as a receptor, enzyme, or transporter, but disrupts cancer cell homeostasis via RNA-mediated modulation of the p53 pathway[1][3].

Other names

LOC643401LINC01021RP11-46C20.1long intergenic non-protein coding RNA 1021

Not applicable; not a classical druggable protein target. PURPL negatively regulates p53 protein levels by sequestering MYBBP1A via an RNA-binding adaptor (HuR), thereby inhibiting p53 stabilization[1][2].