Genetic analysis of TOR signaling pathway in fission yeast as a model system

2006 Fiscal Year Final Research Report Summary

• Project/Area Number: 16570114
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Functional biochemistry
• Research Institution: Shizuoka University
• Principal Investigator: URITANI Masahiro Shizuoka University, Faculty of Science, professor, 理学部, 教授 (40193974)
• Project Period (FY): 2004 – 2006
• Keywords: Fission yeast / TOR signaling pathway / Genetics / Rapamycin / Protein kinase / Temperature sensitive mutant / Amino acid uptake / Amino acid analogue

Research Abstract

The target of rapamycin (Tor) plays a pivotal role in cell growth and metabolism. Yeast contains two related proteins, Tor1 and Tor2. In fission yeast, Tor1 is dispensable for normal growth but is involved in amino acid uptake and cell survival under various stress conditions. In contrast, Tor2 is essential for cell proliferation ; however, its physiological function remains unknown. Here we characterize the roles of fission yeast Tor2 by creating temperature sensitive (tor2^<ts>) mutants. Remarkably, we have found that tor2^<ts> mimics nitrogen starvation responses, because the mutant displays a number of phenotypes that are normally induced only upon nitrogen deprivation. These include G1 cell-cycle arrest with a small cell size, induction of autophagy and commitment to sexual differentiation. By contrast, tor1 Δtor2ts double mutant cells show distinct phenotypes, as the cells cease division with normal cell size in the absence of G1 arrest. Tor2 physically interacts with the conserved Rhb1/GTPase. Intriguingly, overexpression of rhb1^+ or deletion of Rhb1-GAP-encoding tsc2^+ is capable of rescuing stress-sensitive phenotypes of the torl mutant, implying that Tor1 and Tor2 also share functions in cell survival under adverse environment. We propose that Tor1 and Tor2 are involved in both corroborative and independent roles in nutrient sensing and stress responses pathways.

Research Products

• [Journal Article] Fission yeast Tor2 links nitrogen signals to cell proliferation and acts downstream of the Rheb GTPase (2006)
  • Author(s): Uritani M, Hidaka H, Hotta Y, Ueno M, Ushimaru T, Toda T
  • Journal Title: Genes to Cells 11 Pages: 1367-1379
  • Description: 「研究成果報告書概要(和文)」より
• [Journal Article] TOR regulates late steps of ribosome maturation in the nucleoplasm via Nog1 in response to nutrients. (2006)
  • Author(s): Honma Y, Kitamura A, Shioda R, Maruyama H, Ozaki K, Oda Y, Mini T, Jeno P, Maki Y, Yonezawa K, Hurt E, Ueno M, Uritani M, Hall M N, Ushimaru T
  • Journal Title: The EMBO Journal 25 Pages: 3832-3842
  • Description: 「研究成果報告書概要(和文)」より
• [Journal Article] A starvation-specific serine protease gene, isp6^+, is involved in both autophagy and sexual development in Schizosaccharomyces pombe (2006)
  • Author(s): Nakashima, Takahiro Hasegawa, Saori Mori, Masaru Ueno, Shigeyasu Tanaka, Takashi Ushimaru, Shusei Sato, Masahiro Uritani
  • Journal Title: Current Genetics 49 Pages: 403-413
  • Description: 「研究成果報告書概要(和文)」より
• [Journal Article] TOR regulates late steps of ribosome maturation in the nucleoplasm via Nogl in response to nutrients (2006)
  • Author(s): Honma Y, Kitamura A, Shioda R, Maruyama H, Ozaki K, Oda Y, Mini T, Jeno P, Maki Y, Yonezawa K, Hurt E, Ueno M, Uritani M, Hall M N, Ushimaru T
  • Journal Title: The EMBO Journal l25 Pages: 3832-3842
  • Description: 「研究成果報告書概要(欧文)」より
• [Journal Article] A starvation-specific serine protease gene, isp6^+, is involved in both autophagy and sexual development in Schizosaccharomyces pombe (2006)
  • Author(s): Nakashima A, Hasegawa T, Mori S, Ueno M, Tanaka S, Ushimaru T, Sato S, Uritani M
  • Journal Title: Current Genetics 49 Pages: 403-413
  • Description: 「研究成果報告書概要(欧文)」より