Histone H1.2 Represses the Transcription of the p16 Tumor Suppressor Gene

Background/Aim: CDK inhibitor p16 plays a pivotal role in the induction of cellular senescence and functions as a tumor suppressor. Here, we demonstrate that histone H1.2 is involved in p16 repression. Materials and Methods: Cells were transfected with siRNAs and subjected to quantitative reverse transcription-polymerase chain reaction, immunoblotting and chromatin immunoprecipitation (ChIP) assay. Results: The decrease in H1.2 by oncogenic RAS was associated with increased levels of p16. Depletion of H1.2 selectively increased p16, but not alternative reading frame (ARF) mRNA. ChIP assay showed that H1.2 directly bound to the p16 promoter. Interestingly, silencing YB-1, a component of H1.2 complex, decreased the expression levels of H1.2, resulting in decreased binding of H1.2 on the p16 promoter. Conclusion: These results provide a model in which H1.2 is positively regulated by YB-1 and directly binds to and represses the transcription of p16.