Cell Reports (Aug 2023)

Senescent cells form nuclear foci that contain the 26S proteasome

  • Tomohiro Iriki,
  • Hiroaki Iio,
  • Shu Yasuda,
  • Shun Masuta,
  • Masakazu Kato,
  • Hidetaka Kosako,
  • Shoshiro Hirayama,
  • Akinori Endo,
  • Fumiaki Ohtake,
  • Mako Kamiya,
  • Yasuteru Urano,
  • Yasushi Saeki,
  • Jun Hamazaki,
  • Shigeo Murata

Journal volume & issue
Vol. 42, no. 8
p. 112880

Abstract

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Summary: The proteasome plays a central role in intracellular protein degradation. Age-dependent decline in proteasome activity is associated with cellular senescence and organismal aging; however, the mechanism by which the proteasome plays a role in senescent cells remains elusive. Here, we show that nuclear foci that contain the proteasome and exhibit liquid-like properties are formed in senescent cells. The formation of senescence-associated nuclear proteasome foci (SANPs) is dependent on ubiquitination and RAD23B, similar to previously known nuclear proteasome foci, but also requires proteasome activity. RAD23B knockdown suppresses SANP formation and increases mitochondrial activity, leading to reactive oxygen species production without affecting other senescence traits such as cell-cycle arrest and cell morphology. These findings suggest that SANPs are an important feature of senescent cells and uncover a mechanism by which the proteasome plays a role in senescent cells.

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