LincRNA-p21 acts as a mediator of ING1b-induced apoptosis

Cell Death Dis. 2015 Mar 5;6(3):e1668. doi: 10.1038/cddis.2015.15.

Abstract

ING1b is a tumor suppressor that affects transcription, cell cycle control and apoptosis. ING1b is deregulated in disease, and its activity is closely linked to that of p53. In addition to regulating protein-coding genes, we found that ING1b also influences the expression of large intergenic non-coding RNAs (lincRNAs). In particular, lincRNA-p21 was significantly induced after DNA-damage stress or by ING1b overexpression. Furthermore, lincRNA-p21 expression in response to DNA damage was significantly attenuated in cells lacking ING1b. LincRNA-p21 is also a target of p53 and can trigger apoptosis in mouse cell models. We found that this function of lincRNA-p21 is conserved in human cell models. Moreover, ING1b and p53 could function independently to influence lincRNA-p21 expression. However, their effects become more additive under conditions of stress. In particular, ING1b regulates lincRNA-p21 levels by binding to its promoter and is required for induction of lincRNA-p21 by p53. The ability of ING1b to cause apoptosis is also impaired in the absence of lincRNA-p21. Surprisingly, deletion of the ING1b plant homeodomain, which allows it to bind histones and regulate chromatin structure, did not alter regulation of lincRNA-p21. Our findings suggest that ING1b induces lincRNA-p21 expression independently of histone 3 lysine 4 trimethylation mark recognition and that lincRNA-p21 functions downstream of ING1b. Thus, regulation at the level of lincRNA-p21 may represent the point at which ING1b and p53 pathways converge to induce apoptosis under specific stress conditions.

MeSH terms

  • Apoptosis / genetics
  • Apoptosis / physiology
  • Cell Line, Tumor
  • Cell Survival / genetics
  • Cell Survival / physiology
  • Chromatin Immunoprecipitation
  • Cyclin-Dependent Kinase Inhibitor p21 / genetics
  • Cyclin-Dependent Kinase Inhibitor p21 / metabolism*
  • Humans
  • In Situ Nick-End Labeling
  • Inhibitor of Growth Protein 1
  • Intracellular Signaling Peptides and Proteins / genetics
  • Intracellular Signaling Peptides and Proteins / metabolism*
  • Nuclear Proteins / genetics
  • Nuclear Proteins / metabolism*
  • Promoter Regions, Genetic / genetics
  • RNA Interference
  • RNA, Long Noncoding / genetics
  • RNA, Long Noncoding / metabolism*
  • Real-Time Polymerase Chain Reaction
  • Tumor Suppressor Proteins / genetics
  • Tumor Suppressor Proteins / metabolism*

Substances

  • Cyclin-Dependent Kinase Inhibitor p21
  • ING1 protein, human
  • Inhibitor of Growth Protein 1
  • Intracellular Signaling Peptides and Proteins
  • Nuclear Proteins
  • RNA, Long Noncoding
  • Tumor Suppressor Proteins