iScience (Jan 2024)

Rapamycin-sensitive mechanisms confine the growth of fission yeast below the temperatures detrimental to cell physiology

  • Yuichi Morozumi,
  • Fontip Mahayot,
  • Yukiko Nakase,
  • Jia Xin Soong,
  • Sayaka Yamawaki,
  • Fajar Sofyantoro,
  • Yuki Imabata,
  • Arisa H. Oda,
  • Miki Tamura,
  • Shunsuke Kofuji,
  • Yutaka Akikusa,
  • Ayu Shibatani,
  • Kunihiro Ohta,
  • Kazuhiro Shiozaki

Journal volume & issue
Vol. 27, no. 1
p. 108777

Abstract

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Summary: Cells cease to proliferate above their growth-permissible temperatures, a ubiquitous phenomenon generally attributed to heat damage to cellular macromolecules. We here report that, in the presence of rapamycin, a potent inhibitor of Target of Rapamycin Complex 1 (TORC1), the fission yeast Schizosaccharomyces pombe can proliferate at high temperatures that usually arrest its growth. Consistently, mutations to the TORC1 subunit RAPTOR/Mip1 and the TORC1 substrate Sck1 significantly improve cellular heat resistance, suggesting that TORC1 restricts fission yeast growth at high temperatures. Aiming for a more comprehensive understanding of the negative regulation of high-temperature growth, we conducted genome-wide screens, which identified additional factors that suppress cell proliferation at high temperatures. Among them is Mks1, which is phosphorylated in a TORC1-dependent manner, forms a complex with the 14-3-3 protein Rad24, and suppresses the high-temperature growth independently of Sck1. Our study has uncovered unexpected mechanisms of growth restraint even below the temperatures deleterious to cell physiology.

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