Related Experiment Video
Updated: Jul 2, 2026
07:47
Microscopy of Fission Yeast Sexual Lifecycle
Published on: March 9, 2016
TOR signaling in fission yeast
Yoko Otsubo1, Masayuki Yamamato
1Department of Biophysics and Biochemistry, Graduate School of Science, University of Tokyo, Hongo, Tokyo, Japan.
Critical Reviews in Biochemistry and Molecular Biology
|August 30, 2008
Summary
Fission yeast possesses two TOR kinases, Tor1 and Tor2, with distinct roles in cell cycle and development. This microbe offers a model for studying TOR signaling pathways, even though rapamycin has limited effects on its growth.
Area of Science:
- Molecular Biology
- Cell Biology
- Yeast Genetics
Background:
- Fission yeast, like higher eukaryotes, exhibits a TSC/Rheb/TOR signaling pathway.
- Two distinct TOR complexes, TORC1 and TORC2, have been identified in fission yeast.
- TORC1 contains Tor2, while TORC2 contains Tor1, suggesting specialized functions.
Purpose of the Study:
- To investigate the opposing functions of fission yeast TORC1 and TORC2.
- To explore the role of TOR signaling in G1 arrest and sexual development.
- To understand the effects of rapamycin on fission yeast TOR pathways.
Main Methods:
- Analysis of TORC1 and TORC2 composition and function.
- Investigation of G1 arrest and sexual development pathways.
- Detailed examination of rapamycin's effects on cellular functions.
Main Results:
- Fission yeast TORC1 (containing Tor2) and TORC2 (containing Tor1) display opposing roles in promoting G1 arrest and sexual development.
- Rapamycin does not inhibit wild-type fission yeast growth but impacts specific TOR-mediated cellular functions.
- The identified TOR pathway components and their functions are conserved across eukaryotes.
Conclusions:
- Fission yeast TORC1 and TORC2 have divergent functions in regulating cell cycle and development.
- Despite resistance to growth inhibition, rapamycin reveals specific roles for TOR signaling in fission yeast.
- Fission yeast serves as a valuable model organism for dissecting conserved TOR signaling pathways.
Related Concept Videos
01:28Yeast Signaling
Yeasts are single-celled organisms, but unlike bacteria, they are eukaryotes (cells with a nucleus). Cell signaling in yeast is similar to signaling in other eukaryotic cells. A ligand, such as a protein or a small molecule released from a yeast cell, attaches to a receptor on the cell surface. The binding stimulates second-messenger kinases to activate or inactivate transcription factors that further regulate gene expression. Many of the yeast intracellular signaling cascades have similar...
01:17Gene Regulation During Sporulation
Sporulation is a complex developmental process that allows certain Gram-positive bacteria, such as Bacillus subtilis and Clostridium species, to survive extreme environmental conditions. This process is tightly regulated by a series of signaling cascades and transcriptional controls, ensuring the formation of a highly resistant endospore.Sporulation is triggered by unfavorable conditions, such as nutrient depletion, and is governed by a phosphorelay system. One of the sensor kinases, such as...
01:22PI3K/mTOR/AKT Signaling Pathway
The mammalian target of rapamycin (mTOR) is a serine/threonine kinase that regulates growth, proliferation, and cell survival in response to hormones, growth factors, or nutrient availability. This kinase exists in two structurally and functionally distinct forms: mTOR complex 1 (mTORC1) and mTOR complex 2 (mTORC2). The first form (mTORC1) is composed of a rapamycin-sensitive Raptor and proline-rich Akt substrate, PRAS40. In contrast, mTORC2 consists of a rapamycin-insensitive companion...
03:03mTOR Signaling and Cancer Progression
The mammalian target of rapamycin or mTOR protein was discovered in 1994 due to its direct interaction with rapamycin. The protein gets its name from a yeast homolog called TOR. The mTOR protein complex in mammalian cells plays a major role in balancing anabolic processes such as the synthesis of proteins, lipids, and nucleotides and catabolic processes, such as autophagy in response to environmental cues, such as availability of nutrients and growth factors.
The mTOR pathway or the...
The mTOR pathway or the...
01:19Interactions Between Signaling Pathways
Signaling cascades usually lack linearity. Multiple pathways interact and regulate one another, allowing cells to integrate and respond to diverse environmental stimuli.
Convergence and divergence, and cross-talk between signaling pathways
Two distinct signaling pathways can converge on a single functional unit, which may either be a single protein or a complex of proteins. The response is either functionally distinct or synergistic between the two pathways but different from the response...
Convergence and divergence, and cross-talk between signaling pathways
Two distinct signaling pathways can converge on a single functional unit, which may either be a single protein or a complex of proteins. The response is either functionally distinct or synergistic between the two pathways but different from the response...
01:07MAPK Signaling Cascades
Mitogen-activated protein kinase, or MAPK pathway, activates three sequential kinases to regulate cellular responses such as proliferation, differentiation, survival, and apoptosis. The canonical MAPK pathway starts with a mitogen or growth factor binding to an RTK. The activated RTKs stimulate Ras, which recruits Raf or MAP3 Kinase (MAPKKK), the first kinase of the MAPK signaling cascade. Raf further phosphorylates and activates MEK or MAP2 Kinases (MAPKK), which in turn phosphorylates MAP...