iScience (Feb 2022)

TORC1 inactivation promotes APC/C-dependent mitotic slippage in yeast and human cells

  • Chihiro Yamada,
  • Aya Morooka,
  • Seira Miyazaki,
  • Masayoshi Nagai,
  • Satoru Mase,
  • Kenji Iemura,
  • Most Naoshia Tasnin,
  • Tsuneyuki Takuma,
  • Shotaro Nakamura,
  • Shamsul Morshed,
  • Naoki Koike,
  • Md. Golam Mostofa,
  • Muhammad Arifur Rahman,
  • Tasnuva Sharmin,
  • Haruko Katsuta,
  • Kotaro Ohara,
  • Kozo Tanaka,
  • Takashi Ushimaru

Journal volume & issue
Vol. 25, no. 2
p. 103675

Abstract

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Summary: Unsatisfied kinetochore-microtubule attachment activates the spindle assembly checkpoint to inhibit the metaphase-anaphase transition. However, some cells eventually override mitotic arrest by mitotic slippage. Here, we show that inactivation of TORC1 kinase elicits mitotic slippage in budding yeast and human cells. Yeast mitotic slippage was accompanied with aberrant aspects, such as degradation of the nucleolar protein Net1, release of phosphatase Cdc14, and anaphase-promoting complex/cyclosome (APC/C)-Cdh1-dependent degradation of securin and cyclin B in metaphase. This mitotic slippage caused chromosome instability. In human cells, mammalian TORC1 (mTORC1) inactivation also invoked mitotic slippage, indicating that TORC1 inactivation-induced mitotic slippage is conserved from yeast to mammalian cells. However, the invoked mitotic slippage in human cells was not dependent on APC/C-Cdh1. This study revealed an unexpected involvement of TORC1 in mitosis and provides information on undesirable side effects of the use of TORC1 inhibitors as immunosuppressants and anti-tumor drugs.

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