Cell growth control: little eukaryotes make big contributions

Virgilio, Claudio De; Loewith, Robbie

doi:10.1038/sj.onc.1209884

Cited by 204 publications

(221 citation statements)

References 240 publications

(351 reference statements)

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“…Our data showing that nuclear Glc7 levels are reduced under conditions of lower TORC1 activity and the genetic interactions between the Glc7 and TORC1 pathways support the latter hypothesis. The phosphoprotein phosphatases PP2A and Sit4 are major downstream targets of TORC1 (38). Our work now provides evidence that PP1/Glc7 is also regulated by TORC1.…”

Section: Discussionsupporting

confidence: 51%

Temperature-sensitive ipl1-2/Aurora B mutation is suppressed by mutations in TOR complex 1 via the Glc7/PP1 phosphatase

Tatchell

Makrantoni

Stark

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

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Ipl1/Aurora B is the catalytic subunit of a complex that is required for chromosome segregation and nuclear division. Before anaphase, Ipl1 localizes to kinetochores, where it is required to establish proper kinetochore-microtubule associations and regulate the spindle assembly checkpoint. The protein phosphatase Glc7/ PP1 opposes Ipl1 for some of these activities. To more thoroughly characterize the Glc7 phosphatase that opposes Ipl1, we have identified mutations that suppress the thermosensitivity of an ipl1-2 mutant. In addition to mutations in genes previously associated with ipl1 suppression, we recovered a null mutant in TCO89, which encodes a subunit of the TOR complex 1 (TORC1), the conserved rapamycin-sensitive kinase activity that regulates cell growth in response to nutritional status. The temperature sensitivity of ipl1-2 can also be suppressed by null mutation of TOR1 or by administration of pharmacological TORC1 inhibitors, indicating that reduced TORC1 activity is responsible for the suppression. Suppression of the ipl1-2 growth defect is accompanied by increased fidelity of chromosome segregation and increased phosphorylation of the Ipl1 substrates histone H3 and Dam1. Nuclear Glc7 levels are reduced in a tco89 mutant, suggesting that TORC1 activity is required for the nuclear accumulation of Glc7. In addition, several mutant GLC7 alleles that suppress the temperature sensitivity of ipl1-2 exhibit negative synthetic genetic interactions with TORC1 mutants. Together, our results suggest that TORC1 positively regulates the Glc7 activity that opposes Ipl1 and provide a mechanism to tie nutritional status with mitotic regulation.

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Section: Discussionsupporting

confidence: 51%

Temperature-sensitive ipl1-2/Aurora B mutation is suppressed by mutations in TOR complex 1 via the Glc7/PP1 phosphatase

Tatchell

Makrantoni

Stark

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

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“…In addition to the abundance and/or quality of nutrients, TORC1 activity also appears to be sensitive to stress cues, but the mechanisms by which these cues are sensed and how this is communicated to TORC1 are presently unknown (De Virgilio and Loewith 2006a). Finally, the Golgi Ca 2?…”

Section: How Is Tor Signalling Regulated?mentioning

confidence: 99%

Life in the midst of scarcity: adaptations to nutrient availability in Saccharomyces cerevisiae

et al. 2010

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Cells of all living organisms contain complex signal transduction networks to ensure that a wide range of physiological properties are properly adapted to the environmental conditions. The fundamental concepts and individual building blocks of these signalling networks are generally well-conserved from yeast to man; yet, the central role that growth factors and hormones play in the regulation of signalling cascades in higher eukaryotes is executed by nutrients in yeast. Several nutrient-controlled pathways, which regulate cell growth and proliferation, metabolism and stress resistance, have been defined in yeast. These pathways are integrated into a signalling network, which ensures that yeast cells enter a quiescent, resting phase (G 0 ) to survive periods of nutrient scarceness and that they rapidly resume growth and cell proliferation when nutrient conditions become favourable again. A series of well-conserved nutrient-sensory protein kinases perform key roles in this signalling network: i.e. Snf1, PKA, Tor1 and Tor2, Sch9 and Pho85-Pho80. In this review, we provide a comprehensive overview on the current understanding of the signalling processes mediated via these kinases with a particular focus on how these individual pathways converge to signalling networks that ultimately ensure the dynamic translation of extracellular nutrient signals into appropriate physiological responses.

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“…Cell sizing is regulated mainly by two mechanisms: cell cycle control and the biochemical response to nutrients and/or growth factors (1)(2)(3)(4)(5). During cell cycle progression, both the G 1 (which is believed to be dominant) and the G 2 periods are important for cells to increase their volume (6 -9).…”

mentioning

confidence: 99%

The Death Effector Domain-containing DEDD Supports S6K1 Activity via Preventing Cdk1-dependent Inhibitory Phosphorylation

Kurabe

Arai

Nishijima

et al. 2009

Journal of Biological Chemistry

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؊/؊ cells and tissues. Consequently, as in S6K1 ؊/؊ mice, the insulin mass within pancreatic islets was reduced in DEDD ؊/؊ mice, resulting in glucose intolerance. These findings suggest a novel cell sizing mechanism achieved by DEDD through the maintenance of S6K1 activity prior to cell division. Our results also suggest that DEDD may harbor important roles in glucose homeostasis and that its deficiency might be involved in the pathogenesis of type 2 diabetes mellitus.Cell size is closely related to specialized cell function and to the specific patterning of tissues in the body. Cell sizing is regulated mainly by two mechanisms: cell cycle control and the biochemical response to nutrients and/or growth factors (1-5). During cell cycle progression, both the G 1 (which is believed to be dominant) and the G 2 periods are important for cells to increase their volume (6 -9). In addition, we recently provided evidence that the mitotic period (M phase) also influences cell size, through analysis of DEDD-deficient mice (10, 11). The DEDD molecule was initially described as a member of the death effector domain (DED) 2 -containing protein family (12). Although the absence of DEDD did not apparently influence progression of apoptosis (10), we found that during mitosis, DEDD is associated with Cdk1-cyclin B1 and that it decreases the kinase activity of Cdk1. This response impedes the Cdk1-dependent mitotic program to shut off synthesis of ribosomal RNA (rRNA) and protein and is consequently useful in gaining sufficient cell growth prior to cell division. Depletion of DEDD consistently results in a shortened mitotic duration and an overall reduction in the amount of cellular rRNA and protein and, furthermore, in cell and body size (10,11).Of the biochemical responses responsible for cell sizing, the signaling cascade involving phosphatydilinositol 3-kinase (PI3K) and its downstream target of rapamycin (TOR) is most crucial (13)(14)(15). In mammals, upon stimulation by growth factors, including insulin, the mammalian TOR (mTOR) cooperates with PI3K-dependent effectors to activate S6K1, thereby phosphorylating the 40 S ribosomal protein S6, and subsequently enhances translation of the 5Ј-terminal oligopyrimidine sequences that encode components of the translational machinery. This reaction increases the number of ribosomes and the efficacy of protein synthesis, thus critically promoting cell growth (16 -18). Therefore, mice deficient for S6K1 (S6K1 Ϫ/Ϫ ) had reduced cell and body size (19 -23). This effect also involves S6K1 in maintenance of glucose tolerance. S6K1 * This work was supported, in whole or in part, by National Institutes of Health Grant 5RO1AI50948-05. This work was also supported by grants-in-aid from the Ministry of Education, Sports, Culture, Science, and Technology, Japan, the Takeda Science Foundation (to T. M. and S. A.), the Mitsubishi Pharma Research Foundation, the Mochida Memorial Foundation for Medical and Pharmaceutical Research, the Danone Institute of Nutrition for Health, the Uehara Memorial Fou...

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Cell growth control: little eukaryotes make big contributions

Cited by 204 publications

References 240 publications

Temperature-sensitive ipl1-2/Aurora B mutation is suppressed by mutations in TOR complex 1 via the Glc7/PP1 phosphatase

Temperature-sensitive ipl1-2/Aurora B mutation is suppressed by mutations in TOR complex 1 via the Glc7/PP1 phosphatase

Life in the midst of scarcity: adaptations to nutrient availability in Saccharomyces cerevisiae

The Death Effector Domain-containing DEDD Supports S6K1 Activity via Preventing Cdk1-dependent Inhibitory Phosphorylation

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