TORC2 Is Required to Maintain Genome Stability during S Phase in Fission Yeast

Schonbrun, Miriam; Kolesnikov, Masha; Kupiec, Martin; Weisman, Ronit

doi:10.1074/jbc.m113.464974

Cited by 26 publications

(46 citation statements)

References 72 publications

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“…Disruption of TORC2 (⌬tor1, ⌬ste20, or ⌬sin1) results in pleiotrophic defects, including elongated cell morphology, deregulation of mitotic entrance, sensitivity to osmotic and oxidative stress, inability to enter sexual development or acquire stationary phase physiology, and a decrease in amino acid uptake (5-7, 9 -11). Recently, we have showed that TORC2 is required under DNA replication stress and for maintenance of telomere length and gene silencing (12). Interestingly, a role for TORC2 in maintenance of genome stability has also been reported in Saccharomyces cerevisiae (13), suggesting that the role of TORC2 in tolerance to DNA damage and genome integrity is conserved in evolution.…”

Section: Target Of Rapamycin (Tor)mentioning

confidence: 99%

“…Consistent with our findings showing a rapid and translation-independent response of TORC2-Gad8 to glucose, the stimulating effect of the cAMP/ PKA pathway on TORC2-Gad8 was independent of the Pka1-regulated transcription factor Rst2. We have recently identified a role for TORC2-Gad8 in survival under DNA-damaging conditions, in particular those occurring during DNA replication (6,12). A screen for CPT-sensitive mutant cells has recently identified mutations in the cAMP/PKA pathway as sensitive to this drug (41).…”

Section: Discussionmentioning

confidence: 99%

“…CPT forms a toxic complex with topoisomerase I that prevents DNA re-ligation and therefore causes DNA damage. We have previously demonstrated that cells disrupted for any component of TORC2 (⌬tor1, ⌬ste20, or ⌬sin1) or disruption of gad8 ϩ lead to sensitivity to CPT (12). Overexpression of gad8 ϩ from a multicopy plasmid partially suppressed the CPT sensitivity of ⌬git3, ⌬gpa2, ⌬gpb1, or ⌬pka1 cells (Fig.…”

Section: Torc2-dependent Gad8 Phosphorylation and Gad8mentioning

confidence: 99%

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Glucose Activates TORC2-Gad8 Protein via Positive Regulation of the cAMP/cAMP-dependent Protein Kinase A (PKA) Pathway and Negative Regulation of the Pmk1 Protein-Mitogen-activated Protein Kinase Pathway

Cohen

Kupiec

Weisman

2014

Journal of Biological Chemistry

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Background: TORC2 is a conserved protein complex that regulates multiple aspects of cell survival and proliferation. Results: Gad8 is regulated by the cAMP-dependent protein kinase A and the Pmk1 protein-mitogen-activated protein kinase. Conclusion: Glucose is a major regulator of TORC2-Gad8 signaling. Significance: Identification of a novel mode of regulation of TORC2-Gad8 in response to glucose and stress.

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Section: Target Of Rapamycin (Tor)mentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Torc2-dependent Gad8 Phosphorylation and Gad8mentioning

confidence: 99%

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Glucose Activates TORC2-Gad8 Protein via Positive Regulation of the cAMP/cAMP-dependent Protein Kinase A (PKA) Pathway and Negative Regulation of the Pmk1 Protein-Mitogen-activated Protein Kinase Pathway

Cohen

Kupiec

Weisman

2014

Journal of Biological Chemistry

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“…Upon glucose withdrawal or shift from glucose to a less favorable carbon source such as glycerol, there is a reduction of TORC2-dependent phosphorylation of Gad8 at serine 546 (equivalent to serine 473 in AKT) and concomitant reduced Gad8 kinase activity (17, 18). Thus, S. pombe TORC1 and TORC2 play essential roles in regulating growth by responding to two distinct key nutritional cues.As mentioned above, our functional analysis of cells lacking TORC2 or Gad8 indicated a role for TORC2-Gad8 in the survival under DNA damage and replication stresses (10,11 …”

mentioning

confidence: 94%

Gad8 Protein Is Found in the Nucleus Where It Interacts with the MluI Cell Cycle Box-binding Factor (MBF) Transcriptional Complex to Regulate the Response to DNA Replication Stress

Cohen

Kupiec

Weisman

2016

Journal of Biological Chemistry

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The target of rapamycin (TOR) kinase is found at the core of two evolutionarily conserved complexes known as TOR complexes 1 and 2 (TORC1 and TORC2). In fission yeast, TORC2 is dispensable for proliferation under optimal growth conditions but is required for starvation and stress responses. We have previously reported that loss of function of TORC2 renders cells highly sensitive to DNA replication stress; however, the mechanism underlying this sensitivity is unknown. TORC2 has one known direct substrate, the kinase Gad8, which is related to AKT in human cells. Here we show that both TORC2 and its substrate Gad8 are found in the nucleus and are bound to the chromatin. We also demonstrate that Gad8 physically interacts with the MluI cell cycle box-binding factor (MBF) transcription complex that regulates the G 1 /S progression and the response to DNA stress. In mutant cells lacking TORC2 or Gad8, the binding of the MBF complex to its cognate promoters is compromised, and the induction of MBF target genes in response to DNA replication stress is reduced. Consistently, the protein levels of Cdt2 and Cig2, two MBF target genes, are reduced in the absence of TORC2-Gad8 signaling. Taken together, our findings highlight critical functions of TORC2 in the nucleus and suggest a role in surviving DNA replication stress via transcriptional regulation of MBF target genes. Target of rapamycin (TOR)2 is an atypical protein kinase that was isolated as the target of the immunosuppressive and anticancer drug rapamycin. TOR proteins play a central role in growth, proliferation, and survival and can be found in two distinct and evolutionarily conserved complexes, TORC1 and TORC2 (1-3). The two TOR complexes are key regulators of cellular growth; however, they respond to different stimuli and phosphorylate distinct sets of protein substrates (1-3). Human cells contain a single TOR protein, known as mTOR, which functions as the catalytic subunit of both mTORC1 and mTORC2. In the fission yeast, Schizosaccharomyces pombe, there are two genes encoding for TOR proteins. Tor1 interacts with Ste20 (Rictor in human cells) and Sin1 (mSin1 in human cells) to form TORC2, whereas Tor2 interacts with Mip1 (Raptor in human cells) to form TORC1 (4). TORC1 is essential for growth in S. pombe and plays a critical role in regulating the switch between growth and sexual development in response to nitrogen starvation. Consistently, disruption of S. pombe TORC1 results in many features characteristic of nitrogenstarved cells (5-8), and TORC1-dependent phosphorylation of the small ribosomal protein Rps6 is diminished under nitrogen starvation (9).S. pombe TORC2 is not essential for growth but is required for cell survival under a wide variety of stress conditions, including high or low temperatures, oxidative or osmotic stress, and DNA damage or replication stresses (10, 11). TORC2 is also essential for entrance into a stationary (G 0 -like) phase and sexual development, two processes that occur in response to nutritional starvation. Under normal growth ...

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“…In fission yeast, TORC2 is required for recovery from DNA replicative arrest (7) and maintenance of genome stability after S-phase-specific DNA damage (8). In budding yeast, TORC2 is required for maintenance of genome stability after double-stranded DNA (dsDNA) damage (9).…”

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confidence: 99%

mTORC1 and -2 Coordinate Transcriptional and Translational Reprogramming in Resistance to DNA Damage and Replicative Stress in Breast Cancer Cells

Silvera

Ernlund

Arju

et al. 2017

Molecular and Cellular Biology

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mTOR coordinates growth signals with metabolic pathways and protein synthesis and is hyperactivated in many human cancers. mTOR exists in two complexes: mTORC1, which stimulates protein, lipid, and ribosome biosynthesis, and mTORC2, which regulates cytoskeleton functions. While mTOR is known to be involved in the DNA damage response, little is actually known regarding the functions of mTORC1 compared to mTORC2 in this regard or the respective impacts on transcriptional versus translational regulation. We show that mTORC1 and mTORC2 are both required to enact DNA damage repair and cell survival, resulting in increased cancer cell survival during DNA damage. Together mTORC1 and -2 enact coordinated transcription and translation of protective cell cycle and DNA replication, recombination, and repair genes. This coordinated transcriptional-translational response to DNA damage was not impaired by rapalog inhibition of mTORC1 or independent inhibition of mTORC1 or mTORC2 but was blocked by inhibition of mTORC1/2. Only mTORC1/2 inhibition reversed cancer cell resistance to DNA damage and replicative stress and increased tumor cell killing and tumor control by DNA damage therapies in animal models. When combined with DNA damage, inhibition of mTORC1/2 blocked transcriptional induction more strongly than translation of DNA replication, survival, and DNA damage response mRNAs.KEYWORDS breast cancer, DNA damage, mTOR, protein synthesis, translational control, DNA damage response, protein synthesis, transcriptional control T he mammalian target of rapamycin (mTOR) is a downstream kinase of the phosphatidylinositol 3-kinase (PI3K)/AKT signaling pathway that integrates signals from growth factors and nutrients to regulate key metabolic and macromolecular processes and is dysregulated in many human cancers (1-3). mTOR exists in two complexes, mTOR complex 1 (mTORC1) and mTORC2, which mediate different functions defined by their molecular composition. In response to nutrient levels, growth factors, and other mitogenic signals, mTORC1 regulates protein synthesis, lipid synthesis, and ribosome biogenesis (1, 3). mTORC1 includes the proteins mTOR, Raptor, and G␤L, among others (4), and is responsible for the phosphorylation (inactivation) of the negative regulator of cap binding protein eukaryotic translation initiation factor 4E (eIF4E) known as 4E-BP1. 4E-BP1 binds and blocks the activity of the translation initiation factor eIF4E by competing for interaction with translation initiation factor eIF4G, a molecular scaffold upon which the 40S ribosome and translation factors assemble (5). mTORC2 includes the proteins mTOR, Rictor, and G␤L, among others. mTORC2 regulates cytoskeleton

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TORC2 Is Required to Maintain Genome Stability during S Phase in Fission Yeast

Cited by 26 publications

References 72 publications

Glucose Activates TORC2-Gad8 Protein via Positive Regulation of the cAMP/cAMP-dependent Protein Kinase A (PKA) Pathway and Negative Regulation of the Pmk1 Protein-Mitogen-activated Protein Kinase Pathway

Glucose Activates TORC2-Gad8 Protein via Positive Regulation of the cAMP/cAMP-dependent Protein Kinase A (PKA) Pathway and Negative Regulation of the Pmk1 Protein-Mitogen-activated Protein Kinase Pathway

Gad8 Protein Is Found in the Nucleus Where It Interacts with the MluI Cell Cycle Box-binding Factor (MBF) Transcriptional Complex to Regulate the Response to DNA Replication Stress

mTORC1 and -2 Coordinate Transcriptional and Translational Reprogramming in Resistance to DNA Damage and Replicative Stress in Breast Cancer Cells

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