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Polycomb complexes regulate cellular senescence by repression of ARF in cooperation with E2F3

Jun Miki1, Yu-ichi Fujimura, Haruhiko Koseki

  • 1Department of Pediatrics, Shinshu University School of Medicine, Matsumoto, Nagano 390-8621, Japan.

Genes to Cells : Devoted to Molecular & Cellular Mechanisms
|December 14, 2007
PubMed

Insights

Class II polycomb proteins, like Mel18, are crucial for cellular senescence. Their absence accelerates senescence by impacting the ARF/p53 pathway, highlighting a key mechanism in stress-induced aging.

Area of Science:

  • Cellular and Molecular Biology
  • Epigenetics and Gene Regulation
  • Aging Research

Background:

  • Cellular senescence is a stress-induced state impacting normal cells in culture.
  • The class II polycomb complex, including Mel18, plays a role in regulating cellular processes.
  • Understanding senescence mechanisms is vital for aging and disease research.

Purpose of the Study:

  • To investigate the functional role of the class II polycomb complex, specifically Mel18, in cellular senescence.
  • To elucidate the molecular pathways involved in Mel18-deficient premature senescence.
  • To determine the interplay between polycomb proteins, E2F3b, and the ARF/p53 pathway in senescence.

Main Methods:

  • Utilized genetically modified mouse embryo fibroblasts (MEFs) lacking Mel18.
  • Performed functional analyses including gene deletion (ARF, p53) and senescence assays.
  • Assessed gene expression (ARF, p53, p16INK4a, Ring1b, Bmi1) and protein binding to the ARF promoter (Ring1b, E2F3b).

Main Results:

  • Mel18-null MEFs exhibited premature senescence with increased ARF/p53/p16INK4a and decreased Ring1b/Bmi1.
  • Deletion of ARF or p53 abolished senescence in Mel18-null MEFs, confirming the ARF/p53 pathway's central role.
  • Ring1b/E2F3b binding to the ARF promoter decreased during senescence, with Mel18 inactivation accelerating this dissociation.

Conclusions:

  • The ARF/p53 pathway is central to stress-induced senescence.
  • Class II polycomb proteins and E2F3b cooperate to control ARF expression and cellular senescence.
  • Mel18's absence promotes senescence via the ARF/p53 pathway, revealing a novel regulatory mechanism.

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