The fission yeast TOR proteins and the rapamycin response: an unexpected tale.
The TOR proteins are known as key regulators of cell growth in response to nutritional and mitogenic signals and as targets for the immunosuppressive and anti-cancerous drug rapamycin. The fission yeast Schizosaccharomyces pombe has two TOR homologues, tor1+ and tor2+. Despite their structural similarity, these genes have distinct functions: tor1+ is required under starvation, extreme temperatures, and osmotic or oxidative stress conditions, whereas tor2+ is required under normal growth conditions. Surprisingly, rapamycin does not seem to inhibit the S. pombe TOR-related functions. Rapamycin specifically inhibits sexual development in S. pombe, and this seems to stem from direct inhibition of the S. pombe FKBP12 homologue. Why S. pombe cells are resistant to rapamycin during the growth phase is as yet unclear and awaits further analysis of the TOR-dependent signaling pathways.
Weisman
R
R
Department of Molecular Microbiology and Biotechnology, Faculty of Life Sciences, Tel-Aviv University, 69978 Tel-Aviv, Israel. ronitt@post.tau.ac.il
D000935:Antifungal Agents / Q000494:pharmacology*; D002453:Cell Cycle / Q000502:physiology; D005656:Fungal Proteins / Q000378:metabolism / Q000502:physiology*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism / Q000502:physiology*; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000378:metabolism / Q000502:physiology*; D012568:Schizosaccharomyces / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism / Q000502:physiology*; D020123:Sirolimus / Q000494:pharmacology*; D022061:Tacrolimus Binding Protein 1A / Q000037:antagonists & inhibitors / Q000378:metabolism
D000935:Antifungal Agents; D005656:Fungal Proteins; D019869:Phosphatidylinositol 3-Kinases; D017853:Phosphotransferases (Alcohol Group Acceptor); D020123:Sirolimus; D022061:Tacrolimus Binding Protein 1A