Direct and indirect regulation of Pom1 cell size pathway by the protein phosphatase 2C Ptc1.
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ABSTRACT:
SUBMITTER: Gerganova V
PROVIDER: S-EPMC8108516 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Yeast ptc1 mutants are rapamycin and caffeine sensitive, suggesting a functional connection between Ptc1 and the TOR pathway that is not shared by most members of the type 2C phosphatase family. Genome-wide profiling revealed that the ptc1 mutation largely attenuates the transcriptional response to rapamycin. The lack of Ptc1 significantly prevents the nuclear translocation of Gln3 and Msn2 transcription factors to the nucleus, as well as the dephosphorylation of the Npr1 kinase, in response to rapamycin. This could explain the observed decrease in both the basal and rapamycin-induced expression of several genes subjected to nitrogen catabolite repression (GAT1, MEP1, and GLN1) and stress response element (STRE)-driven promoters. Interestingly, this decrease is abolished in the absence of the Sit4 phosphatase. Epitasis analysis indicates that the mutation of SIT4 or TIP41, encoding a Tap42-interacting protein, abolishes the sensitivity of the ptc1 strain to rapamycin and caffeine. All of these results suggest that Ptc1 is required for normal TOR signaling, possibly by regulating a step upstream of Sit4 function. According to this hypothesis, we observe that the mutation of PTC1 drastically diminishes the rapamycin-induced interaction between Tap42 and Tip41, and this can be explained by lower-than-normal levels of Tip41 in ptc1 cells. Ptc1 is not necessary for the normal expression of the TIP41 gene; instead, its absence dramatically affects the stability of Tip41. The lack of Ptc1 partially abolishes the rapamycin-induced dephosphorylation of Tip41, which may further decrease Tap42 binding. Reduced Tip41 levels contribute to the ptc1 phenotypes, although additional Ptc1 targets must exist. All of these results provide the first evidence showing that a type 2C protein phosphatase is required for the normal functioning of the TOR pathway.
| S-EPMC2682041 | biostudies-literature
Project description:Protein phosphatase 2C (PP2C), an Mg(2+)-dependent enzyme that dephosphorylates serine and threonine residues, defines one of the three major families of structurally unrelated eukaryotic protein phosphatases. Members of the two other families of protein phosphatases are known to have important cellular roles, but very little is known about the biological functions of PP2C. In this report we describe a genetic investigation of a PP2C enzyme in the fission yeast Schizosaccharomyces pombe. We discovered ptc1+ (phosphatase two C) as a multicopy suppressor gene of swo1-26, a temperature-sensitive mutation of a gene encoding the heat shock protein hsp90. The ptc1+ gene product is a 40-kDa protein with approximately 24% identity to a rat PP2C protein. Purified Ptc1 has Mg(2+)-dependent casein phosphatase activity, confirming that it is a PP2C enzyme. A ptc1 deletion mutant is viable and has approximately normal levels of PP2C activity, observations consistent with the fact that ptc1+ is a member of a multigene family. Although a ptc1 deletion mutant is viable, it has a greatly reduced ability to survive brief exposure to elevated temperature. Moreover, ptc1+ mRNA levels increase 5- to 10-fold during heat shock. These data, demonstrating that Ptc1 activity is important for survival of heat shock, provide one of the first genetic clues as to the biological functions of PP2C.
| S-EPMC358741 | biostudies-other
Project description:Type 2C protein phosphatases are encoded in Saccharomyces cerevisiae by several related genes (PTC1-7). To gain insight into the functions attributable to a specific member of this gene family, we have investigated the transcriptional profile of ptc6 mutants under standard growth conditions. We have found that lack of Ptc6 did not alter the transcriptional profile when cells were in log phase in YPD medium. Only one gene, involved in iron transport (FIT3), in addition to PTC6 itself, was considered down-regulated. We also identified the transcriptional changes induced by the simultaneous lack of Ptc1 and Ptc6 proteins.
2013-04-19 | GSE38244 | GEO
Project description:Protein phosphatase 2C (PP2C) is an archetype of the PPM Ser/Thr phosphatases, characterized by dependence on divalent magnesium or manganese cofactors, absence of known regulatory proteins, and resistance to all known Ser/Thr phosphatase inhibitors. We have used virtual ligand screening with the AutoDock method and the National Cancer Institute Diversity Set to identify small-molecule inhibitors of PP2Calpha activity at a protein substrate. These inhibitors are active in the micromolar range and represent the first non-phosphate-based molecules found to inhibit a type 2C phosphatase. The compounds docked to three recurrent binding sites near the PP2Calpha active site and displayed novel Ser/Thr phosphatase selectivity profiles. Common chemical features of these compounds may form the basis for development of a PP2C inhibitor pharmacophore and may facilitate investigation of PP2C control and cellular function.
| S-EPMC2538531 | biostudies-literature
Project description:Type 2C protein phosphatases are encoded in Saccharomyces cerevisiae by several related genes (PTC1-7). To gain insight into the functions attributable to a specific member of this gene family, we have investigated the transcriptional profile of ptc6 mutants under standard growth conditions. We have found that lack of Ptc6 did not alter the transcriptional profile when cells were in log phase in YPD medium. Only one gene, involved in iron transport (FIT3), in addition to PTC6 itself, was considered down-regulated. We also identified the transcriptional changes induced by the simultaneous lack of Ptc1 and Ptc6 proteins. * In a first set of experiments we compared the expression profile of ptc6 mutant cells with that of wt cells. We performed 2 biological replicates, and for each experiment we performed two chips (dye swap). Overall we analyzed 4 chips: Biological replicate 1: GSM937247, GSM937248 Biological replicate 2: GSM937251, GSM937252 * In the second set of data we compared the expression profile of ptc1ptc6 double mutant cells with that of wt cells. We performed 2 biological replicates, and for each experiment we performed two chips (dye swap). Overall we analyzed 4 chips: Biological replicate 1: GSM937312, GSM937316 Biological replicate 2: GSM937319, GSM937320
2013-04-19 | E-GEOD-38244 | biostudies-arrayexpress
Project description:It has long been suspected that touch plays a fundamental role in the calibration of visual perception, and much recent evidence supports this idea. However, as the haptic exploration workspace is limited by the kinematics of the body, the contribution of haptic information to the calibration process should occur only within the region of the haptic workspace reachable by a limb (peripersonal space). To test this hypothesis we evaluated visual size perception and showed that it is indeed more accurate inside the peripersonal space. We then show that allowing subjects to touch the (unseen) stimulus after observation restores accurate size perception; the accuracy persists for some time, implying that calibration has occurred. Finally, we show that observing an actor grasp the object also produces accurate (and lasting) size perception, suggesting that the calibration can also occur indirectly by observing goal-directed actions, implicating the involvement of the "mirror system".
| S-EPMC3192750 | biostudies-literature
Project description:We are interested in the study of the already reported sensitivity of yeast cells lacking the type 1 protein phosphatase Ptc1 to the drug rapamycin. In order to carry out our studies, we analyzed the changes in the transcription profile that a short-term incubation with rapamycin (200 ng/mL) has in both, wild type and ptc1 cells. It has been shown that inhibition of the TOR pathway by treatment with rapamycin has profound effects on the global transcriptional profile. We confirmed the previously described transcription changes induced by the drug in wild type cells. Under our working conditions rapamycin increased, in wild type cells, at least 2-fold the expression of 667 genes, whereas it decreased the mRNA level of 721 genes (13.8% and 14.9% of genes with measurable expression level, respectively). Gene ontology analysis shows that, as previously documented, many induced genes falls into the NCR, Msn2/Msn4 regulated stress response or Retrograde response categories, whereas genes encoding cytoplasmic, but not mitochondrial, ribosomal proteins and the so called RIBI regulon where largely repressed. Deletion of PTC1 decreases the number of genes induced or repressed at least 2-fold by rapamycin treatment. Remarkably, lack of Ptc1 seems to lead to a general attenuation of changes triggered by rapamycin.
2008-12-31 | GSE11530 | GEO
Project description:The gene ptc4+ encodes one of four type 2C protein phosphatases (PP2C) in the fission yeast Schizosaccharomyces pombe. Deletion of ptc4+ is not lethal; however, Deltaptc4 cells grow slowly in defined minimal medium and undergo premature growth arrest in response to nitrogen starvation. Interestingly, Deltaptc4 cells are unable to fuse vacuoles in response to hypotonic stress or nutrient starvation. Conversely, Ptc4 overexpression appears to induce vacuole fusion. These findings reveal a hitherto unrecognized function of type 2C protein phosphatases: regulation of vacuole fusion. Ptc4 localizes in vacuole membranes, which suggests that Ptc4 regulates vacuole fusion by dephosphorylation of one or more proteins in the vacuole membrane. Vacuole function is required for the process of autophagy that is induced by nutrient starvation; thus, the vacuole defect of Deltaptc4 cells might explain why these cells undergo premature growth arrest in response to nitrogen starvation.
| S-EPMC25496 | biostudies-literature
Project description:Type 2C protein phosphatases are encoded in Saccharomyces cerevisiae by several related genes (PTC1-5 and PTC7). To gain insight into the functions attributable to specific members of this gene family, we have investigated the transcriptional profiles of ptc1-5 mutants. Two main patterns were obtained as follows: the one generated by the ptc1 mutation and the one resulting from the lack of Ptc2-5. ptc4 and ptc5 profiles were quite similar, whereas that of ptc2 was less related to this group. Mutation of PTC1 resulted in increased expression of numerous genes that are also induced by cell wall damage, such as YKL161c, SED1, or CRH1, as well as in higher amounts of active Slt2 mitogen-activated protein kinase, indicating that lack of the phosphatase activates the cell wall integrity pathway. ptc1 cells were even more sensitive than slt2 mutants to a number of cell wall-damaging agents, and both mutations had additive effects. The sensitivity of ptc1 cells was not dependent on Hog1. Besides these phenotypes, we observed that calcineurin was hyperactivated in ptc1 cells, which were also highly sensitive to calcium ions, heavy metals, and alkaline pH, and exhibited a random haploid budding pattern. Remarkably, many of these traits are found in certain mutants with impaired vacuolar function. As ptc1 cells also display fragmented vacuoles, we hypothesized that lack of Ptc1 would primarily cause vacuolar malfunction, from which other phenotypes would derive. In agreement with this scenario, overexpression of VPS73, a gene of unknown function involved in vacuolar protein sorting, largely rescues not only vacuolar fragmentation but also sensitivity to cell wall damage, high calcium, alkaline pH, as well as other ptc1-specific phenotypes. Keywords: yeast, type 2C protein phosphatases, mutant strains, transcriptional profiles
2007-01-24 | GSE6801 | GEO
Project description:cAMP-dependent phosphorylation activates the cystic fibrosis transmembrane conductance regulator (CFTR) in epithelia. However, the protein phosphatase (PP) that dephosphorylates and inactivates CFTR in airway and intestinal epithelia, two major sites of disease, is not certain. We found that in airway and colonic epithelia, neither okadaic acid nor FK506 prevented inactivation of CFTR when cAMP was removed. These results suggested that a phosphatase distinct from PP1, PP2A, and PP2B was responsible. Because PP2C is insensitive to these inhibitors, we tested the hypothesis that it regulates CFTR. We found that PP2Calpha is expressed in airway and T84 intestinal epithelia. To test its activity on CFTR, we generated recombinant human PP2Calpha and found that it dephosphorylated CFTR and an R domain peptide in vitro. Moreover, in cell-free patches of membrane, addition of PP2Calpha inactivated CFTR Cl- channels; reactivation required readdition of kinase. Finally, coexpression of PP2Calpha with CFTR in epithelia reduced the Cl- current and increased the rate of channel inactivation. These results suggest that PP2C may be the okadaic acid-insensitive phosphatase that regulates CFTR in human airway and T84 colonic epithelia. It has been suggested that phosphatase inhibitors could be of therapeutic value in cystic fibrosis; our data suggest that PP2C may be an important phosphatase to target.
| S-EPMC23594 | biostudies-literature