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Cockrell AJ, Lange JJ, Wood C, Mattingly M, McCroskey SM, Bradford WD, Conkright-Fincham J, Weems L, Guo MS, Gerton JL. Regulators of rDNA array morphology in fission yeast. PLoS Genet 2024; 20:e1011331. [PMID: 38968290 PMCID: PMC11253961 DOI: 10.1371/journal.pgen.1011331] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2023] [Revised: 07/17/2024] [Accepted: 06/04/2024] [Indexed: 07/07/2024] Open
Abstract
Nucleolar morphology is a well-established indicator of ribosome biogenesis activity that has served as the foundation of many screens investigating ribosome production. Missing from this field of study is a broad-scale investigation of the regulation of ribosomal DNA morphology, despite the essential role of rRNA gene transcription in modulating ribosome output. We hypothesized that the morphology of rDNA arrays reflects ribosome biogenesis activity. We established GapR-GFP, a prokaryotic DNA-binding protein that recognizes transcriptionally-induced overtwisted DNA, as a live visual fluorescent marker for quantitative analysis of rDNA organization in Schizosaccharomyces pombe. We found that the morphology-which we refer to as spatial organization-of the rDNA arrays is dynamic throughout the cell cycle, under glucose starvation, RNA pol I inhibition, and TOR activation. Screening the haploid S. pombe Bioneer deletion collection for spatial organization phenotypes revealed large ribosomal protein (RPL) gene deletions that alter rDNA organization. Further work revealed RPL gene deletion mutants with altered rDNA organization also demonstrate resistance to the TOR inhibitor Torin1. A genetic analysis of signaling pathways essential for this resistance phenotype implicated many factors including a conserved MAPK, Pmk1, previously linked to extracellular stress responses. We propose RPL gene deletion triggers altered rDNA morphology due to compensatory changes in ribosome biogenesis via multiple signaling pathways, and we further suggest compensatory responses may contribute to human diseases such as ribosomopathies. Altogether, GapR-GFP is a powerful tool for live visual reporting on rDNA morphology under myriad conditions.
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Affiliation(s)
- Alexandria J. Cockrell
- Stowers Institute for Medical Research, Kansas City, Missouri, United States of America
- Department of Biochemistry and Molecular Biology, University of Kansas Medical Center, Kansas City, Kansas, United States of America
| | - Jeffrey J. Lange
- Stowers Institute for Medical Research, Kansas City, Missouri, United States of America
| | - Christopher Wood
- Stowers Institute for Medical Research, Kansas City, Missouri, United States of America
| | - Mark Mattingly
- Stowers Institute for Medical Research, Kansas City, Missouri, United States of America
| | - Scott M. McCroskey
- Stowers Institute for Medical Research, Kansas City, Missouri, United States of America
| | - William D. Bradford
- Stowers Institute for Medical Research, Kansas City, Missouri, United States of America
| | - Juliana Conkright-Fincham
- Stowers Institute for Medical Research, Kansas City, Missouri, United States of America
- Promega Corporation, Madison, Wisconsin, United States of America
| | - Lauren Weems
- Stowers Institute for Medical Research, Kansas City, Missouri, United States of America
| | - Monica S. Guo
- Department of Microbiology, University of Washington School of Medicine, Seattle, state of Washington, United States of America
| | - Jennifer L. Gerton
- Stowers Institute for Medical Research, Kansas City, Missouri, United States of America
- Department of Biochemistry and Molecular Biology, University of Kansas Medical Center, Kansas City, Kansas, United States of America
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2
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Villota-Salazar NA, Ramos-García VH, González-Prieto JM, Hernández-Delgado S. Effects of chemical inhibition of histone deacetylase proteins in the growth and virulence of Macrophomina phaseolina (Tassi) Goid. Rev Argent Microbiol 2023; 55:296-306. [PMID: 37296064 DOI: 10.1016/j.ram.2023.04.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Revised: 01/31/2023] [Accepted: 04/14/2023] [Indexed: 06/12/2023] Open
Abstract
Chromatin remodeling enzymes are important "writers", "readers" and "erasers" of the epigenetic code. These proteins are responsible for the placement, recognition, and removal of molecular marks in histone tails that trigger structural and functional changes in chromatin. This is also the case for histone deacetylases (HDACs), i.e., enzymes that remove acetyl groups from histone tails, signaling heterochromatin formation. Chromatin remodeling is necessary for cell differentiation processes in eukaryotes, and fungal pathogenesis in plants includes many adaptations to cause disease. Macrophomina phaseolina (Tassi) Goid. is a nonspecific, necrotrophic ascomycete phytopathogen that causes charcoal root disease. M. phaseolina is a frequent and highly destructive pathogen in crops such as common beans (Phaseolus vulgaris L.), particularly under both water and high temperature stresses. Here, we evaluated the effects of the classical HDAC inhibitor trichostatin A (TSA) on M. phaseolinain vitro growth and virulence. During inhibition assays, the growth of M. phaseolina in solid media, as well as the size of the microsclerotia, were reduced (p<0.05), and the colony morphology was remarkably affected. Under greenhouse experiments, treatment with TSA reduced (p<0.05) fungal virulence in common bean cv. BAT 477. Tests of LIPK, MAC1 and PMK1 gene expression during the interaction of fungi with BAT 477 revealed noticeable deregulation. Our results provide additional evidence about the role of HATs and HDACs in important biological processes of M. phaseolina.
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Affiliation(s)
- Nubia Andrea Villota-Salazar
- Biotecnología Vegetal, Centro de Biotecnología Genómica, Instituto Politécnico Nacional, Blvd. del Maestro s/n esq. Elías Piña, Col. Narciso Mendoza, 88710 Reynosa, Tamaulipas, Mexico
| | - Víctor Hugo Ramos-García
- Biotecnología Vegetal, Centro de Biotecnología Genómica, Instituto Politécnico Nacional, Blvd. del Maestro s/n esq. Elías Piña, Col. Narciso Mendoza, 88710 Reynosa, Tamaulipas, Mexico
| | - Juan Manuel González-Prieto
- Biotecnología Vegetal, Centro de Biotecnología Genómica, Instituto Politécnico Nacional, Blvd. del Maestro s/n esq. Elías Piña, Col. Narciso Mendoza, 88710 Reynosa, Tamaulipas, Mexico
| | - Sanjuana Hernández-Delgado
- Biotecnología Vegetal, Centro de Biotecnología Genómica, Instituto Politécnico Nacional, Blvd. del Maestro s/n esq. Elías Piña, Col. Narciso Mendoza, 88710 Reynosa, Tamaulipas, Mexico.
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3
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Abah F, Kuang Y, Biregeya J, Abubakar YS, Ye Z, Wang Z. Mitogen-Activated Protein Kinases SvPmk1 and SvMps1 Are Critical for Abiotic Stress Resistance, Development and Pathogenesis of Sclerotiophoma versabilis. J Fungi (Basel) 2023; 9:jof9040455. [PMID: 37108909 PMCID: PMC10142639 DOI: 10.3390/jof9040455] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2023] [Revised: 03/31/2023] [Accepted: 04/04/2023] [Indexed: 04/29/2023] Open
Abstract
Mitogen-activated protein kinase (MAPK) signaling pathways are evolutionarily conserved in eukaryotes and modulate responses to both internal and external stimuli. Pmk1 and Mps MAPK pathways regulate stress tolerance, vegetative growth and cell wall integrity in Saccharomyces cerevisiae and Pyricularia oryzae. Here, we deployed genetic and cell biology strategies to investigate the roles of the orthologs of Pmk1 and Mps1 in Sclerotiophoma versabilis (herein referred to as SvPmk1 and SvMps1, respectively). Our results showed that SvPmk1 and SvMps1 are involved in hyphal development, asexual reproduction and pathogenesis in S. versabilis. We found that ∆Svpmk1 and ∆Svmps1 mutants have significantly reduced vegetative growths on PDA supplemented with osmotic stress-inducing agents, compared to the wild type, with ∆Svpmps1 being hypersensitive to hydrogen peroxide. The two mutants failed to produce pycnidia and have reduced pathogenicity on Pseudostellaria heterophylla. Unlike SvPmk1, SvMps1 was found to be indispensable for the fungal cell wall integrity. Confocal microscopic analyses revealed that SvPmk1 and SvMps1 are ubiquitously expressed in the cytosol and nucleus. Taken together, we demonstrate here that SvPmk1 and SvMps1 play critical roles in the stress resistance, development and pathogenesis of S. versabilis.
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Affiliation(s)
- Felix Abah
- Ministerial and Provincial Joint Innovation Centre for Safety Production of Cross-Strait Crops, College of Life Sciences & College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Yunbo Kuang
- Ministerial and Provincial Joint Innovation Centre for Safety Production of Cross-Strait Crops, College of Life Sciences & College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou 350002, China
- The Engineering Technology Research Center of Characteristic Medicinal Plants of Fujian, College of Life Sciences, Ningde Normal University, Ningde 352100, China
| | - Jules Biregeya
- Ministerial and Provincial Joint Innovation Centre for Safety Production of Cross-Strait Crops, College of Life Sciences & College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Yakubu Saddeeq Abubakar
- Ministerial and Provincial Joint Innovation Centre for Safety Production of Cross-Strait Crops, College of Life Sciences & College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Zuyun Ye
- The Engineering Technology Research Center of Characteristic Medicinal Plants of Fujian, College of Life Sciences, Ningde Normal University, Ningde 352100, China
| | - Zonghua Wang
- Ministerial and Provincial Joint Innovation Centre for Safety Production of Cross-Strait Crops, College of Life Sciences & College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou 350002, China
- Fujian Provincial Key Laboratory on Conservation and Sustainable Utilization of Marine Biodiversity, Fuzhou Institute of Oceanography, Minjiang University, Fuzhou 350108, China
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Cansado J, Soto T, Franco A, Vicente-Soler J, Madrid M. The Fission Yeast Cell Integrity Pathway: A Functional Hub for Cell Survival upon Stress and Beyond. J Fungi (Basel) 2021; 8:jof8010032. [PMID: 35049972 PMCID: PMC8781887 DOI: 10.3390/jof8010032] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Revised: 12/27/2021] [Accepted: 12/27/2021] [Indexed: 12/11/2022] Open
Abstract
The survival of eukaryotic organisms during environmental changes is largely dependent on the adaptive responses elicited by signal transduction cascades, including those regulated by the Mitogen-Activated Protein Kinase (MAPK) pathways. The Cell Integrity Pathway (CIP), one of the three MAPK pathways found in the simple eukaryote fission of yeast Schizosaccharomyces pombe, shows strong homology with mammalian Extracellular signal-Regulated Kinases (ERKs). Remarkably, studies over the last few decades have gradually positioned the CIP as a multi-faceted pathway that impacts multiple functional aspects of the fission yeast life cycle during unperturbed growth and in response to stress. They include the control of mRNA-stability through RNA binding proteins, regulation of calcium homeostasis, and modulation of cell wall integrity and cytokinesis. Moreover, distinct evidence has disclosed the existence of sophisticated interplay between the CIP and other environmentally regulated pathways, including Stress-Activated MAP Kinase signaling (SAPK) and the Target of Rapamycin (TOR). In this review we present a current overview of the organization and underlying regulatory mechanisms of the CIP in S. pombe, describe its most prominent functions, and discuss possible targets of and roles for this pathway. The evolutionary conservation of CIP signaling in the dimorphic fission yeast S. japonicus will also be addressed.
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Gómez-Gil E, Franco A, Vázquez-Marín B, Prieto-Ruiz F, Pérez-Díaz A, Vicente-Soler J, Madrid M, Soto T, Cansado J. Specific Functional Features of the Cell Integrity MAP Kinase Pathway in the Dimorphic Fission Yeast Schizosaccharomyces japonicus. J Fungi (Basel) 2021; 7:jof7060482. [PMID: 34198697 PMCID: PMC8232204 DOI: 10.3390/jof7060482] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2021] [Revised: 06/10/2021] [Accepted: 06/11/2021] [Indexed: 11/16/2022] Open
Abstract
Mitogen activated protein kinase (MAPK) signaling pathways execute essential functions in eukaryotic organisms by transducing extracellular stimuli into adaptive cellular responses. In the fission yeast model Schizosaccharomyces pombe the cell integrity pathway (CIP) and its core effector, MAPK Pmk1, play a key role during regulation of cell integrity, cytokinesis, and ionic homeostasis. Schizosaccharomyces japonicus, another fission yeast species, shows remarkable differences with respect to S. pombe, including a robust yeast to hyphae dimorphism in response to environmental changes. We show that the CIP MAPK module architecture and its upstream regulators, PKC orthologs Pck1 and Pck2, are conserved in both fission yeast species. However, some of S. pombe's CIP-related functions, such as cytokinetic control and response to glucose availability, are regulated differently in S. japonicus. Moreover, Pck1 and Pck2 antagonistically regulate S. japonicus hyphal differentiation through fine-tuning of Pmk1 activity. Chimeric MAPK-swapping experiments revealed that S. japonicus Pmk1 is fully functional in S. pombe, whereas S. pombe Pmk1 shows a limited ability to execute CIP functions and promote S. japonicus mycelial development. Our findings also suggest that a modified N-lobe domain secondary structure within S. japonicus Pmk1 has a major influence on the CIP signaling features of this evolutionarily diverged fission yeast.
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Li P, Ding L, Cao S, Feng X, Zhang Q, Chen Y, Zhang N, Qiu F. Curcumin metabolites contribute to the effect of curcumin on ameliorating insulin sensitivity in high-glucose-induced insulin-resistant HepG2 cells. JOURNAL OF ETHNOPHARMACOLOGY 2020; 259:113015. [PMID: 32464315 DOI: 10.1016/j.jep.2020.113015] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2019] [Revised: 05/22/2020] [Accepted: 05/22/2020] [Indexed: 06/11/2023]
Abstract
ETHNOPHARMACOLOGICAL EVIDENCE Curcumin (CUR) is the active ingredient of Traditional Chinese Medicine turmeric (Curcuma longa L.), which has been used for treatment of diabetes in Ayurveda and China. CUR exerts potent anti-insulin-resistant effects in various cell lines. However, previous studies indicated CUR was metabolized extensively in vivo and massively degraded in a medium alkaline buffer solution. The real active component of the anti-insulin-resistant activity of CUR in vitro is not clear. AIM OF THE STUDY Our study identified the functional contribution of the metabolites of CUR and the related molecular mechanism in improving insulin sensitivity. MATERIALS AND METHODS HPLC and UPLC-QQQ-MS analyses were used to investigate the stability and metabolism of CUR in HepG2 cells. The effect of the metabolic products of CUR on insulin sensitivity was evaluated in high glucose (HG)-induced insulin-resistant HepG2 cells. A network pharmacology approach was used to examine the potential targets of the metabolites, and Western blotting was performed to verify changes in the targets. RESULTS CUR was unstable in the cell culture medium, but the prototypes, metabolites and degradation products of CUR coexisted in the HepG2 cell culture experiment. The insulin sensitivity assay demonstrated that CUR and its metabolites enhanced insulin sensitivity in HG-induced insulin-resistant HepG2 cells, but the total degradation products of CUR may not play the major role. Similar to CUR, hexahydrocurcumin (HHC) and octahydrocurcumin (OHC) improved insulin sensitivity by strengthening the PI3K-AKT-GSK3B signal and suppressing the phosphorylation of ERK/JNK in HG-induced insulin-resistant HepG2 cells. CONCLUSIONS Metabolites of CUR played a critical role in counteracting insulin resistance in HG-induced HepG2 cells. CUR exerted anti-insulin resistance effect in HepG2 cells in a multi-component, multi-target, and multi-pathway manner.
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Affiliation(s)
- Pan Li
- School of Chinese Materia Medica, Tianjin University of Traditional Chinese Medicine, Tianjin, 301617, China; State Key Laboratory of Modern Chinese Medicine, Tianjin University of Traditional Chinese Medicine, Tianjin, 301617, China
| | - Liqin Ding
- State Key Laboratory of Modern Chinese Medicine, Tianjin University of Traditional Chinese Medicine, Tianjin, 301617, China
| | - Shijie Cao
- State Key Laboratory of Modern Chinese Medicine, Tianjin University of Traditional Chinese Medicine, Tianjin, 301617, China
| | - Xinchi Feng
- School of Chinese Materia Medica, Tianjin University of Traditional Chinese Medicine, Tianjin, 301617, China
| | - Qiang Zhang
- State Key Laboratory of Modern Chinese Medicine, Tianjin University of Traditional Chinese Medicine, Tianjin, 301617, China
| | - Yuwei Chen
- School of Chinese Materia Medica, Tianjin University of Traditional Chinese Medicine, Tianjin, 301617, China; State Key Laboratory of Modern Chinese Medicine, Tianjin University of Traditional Chinese Medicine, Tianjin, 301617, China
| | - Nan Zhang
- School of Chinese Materia Medica, Tianjin University of Traditional Chinese Medicine, Tianjin, 301617, China; State Key Laboratory of Modern Chinese Medicine, Tianjin University of Traditional Chinese Medicine, Tianjin, 301617, China
| | - Feng Qiu
- School of Chinese Materia Medica, Tianjin University of Traditional Chinese Medicine, Tianjin, 301617, China; State Key Laboratory of Modern Chinese Medicine, Tianjin University of Traditional Chinese Medicine, Tianjin, 301617, China.
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7
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Imai Y, Shimasaki T, Enokimura C, Ohtsuka H, Tsubouchi S, Ihara K, Aiba H. gas1 mutation extends chronological lifespan via Pmk1 and Sty1 MAPKs in Schizosaccharomyces pombe. Biosci Biotechnol Biochem 2019; 84:330-337. [PMID: 31601154 DOI: 10.1080/09168451.2019.1676695] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
In the longevity research by using yeasts, chronological lifespan is defined as the survival time after entry into stationary phase. Previously, screening for long lived mutants of Schizosaccharomyces pombe was performed to identify the novel factors involved in longevity. From this screening, one long lived mutant called as No.36 was obtained. In this study, we identified the mutation caused in gas1+, which encodes glucanosyltransferase (gas1-287 mutation) is responsible for the longevity of No.36 mutant. Through the analysis of this mutant, we found that cell wall perturbing agent micafungin also extends chronological lifespan in fission yeast. This lifespan extension depended on both Pmk1 and Sty1 MAP kinases, and longevity caused by the gas1-287 mutation also depended on these kinases. In summary, we propose that the gas1-287 mutation causes longevity as the similar mechanism as cell wall stress depending on Pmk1 and Sty1 MAPK pathways.
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Affiliation(s)
- Yuki Imai
- Laboratory of Molecular Microbiology, Department of Basic Medicinal Sciences, Graduate School of Pharmaceutical Sciences, Nagoya University, Chikusa-ku, Nagoya, Japan
| | - Takafumi Shimasaki
- Laboratory of Molecular Microbiology, Department of Basic Medicinal Sciences, Graduate School of Pharmaceutical Sciences, Nagoya University, Chikusa-ku, Nagoya, Japan
| | - Chihiro Enokimura
- Laboratory of Molecular Microbiology, Department of Basic Medicinal Sciences, Graduate School of Pharmaceutical Sciences, Nagoya University, Chikusa-ku, Nagoya, Japan
| | - Hokuto Ohtsuka
- Laboratory of Molecular Microbiology, Department of Basic Medicinal Sciences, Graduate School of Pharmaceutical Sciences, Nagoya University, Chikusa-ku, Nagoya, Japan
| | - Satoshi Tsubouchi
- Laboratory of Molecular Microbiology, Graduate School of Bioagricultural Sciences, Nagoya University, Chikusa-ku, Nagoya, Japan
| | - Kunio Ihara
- Center for Gene Research, Nagoya University, Chikusa-ku, Nagoya, Japan
| | - Hirofumi Aiba
- Laboratory of Molecular Microbiology, Department of Basic Medicinal Sciences, Graduate School of Pharmaceutical Sciences, Nagoya University, Chikusa-ku, Nagoya, Japan
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Fletcher J, Griffiths L, Caspari T. Nutrient Limitation Inactivates Mrc1-to-Cds1 Checkpoint Signalling in Schizosaccharomyces pombe. Cells 2018; 7:cells7020015. [PMID: 29473861 PMCID: PMC5850103 DOI: 10.3390/cells7020015] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2018] [Revised: 02/21/2018] [Accepted: 02/21/2018] [Indexed: 01/27/2023] Open
Abstract
The S. pombe checkpoint kinase, Cds1, protects the integrity of stalled DNA replication forks after its phosphorylation at threonine-11 by Rad3 (ATR). Modified Cds1 associates through its N-terminal forkhead-associated domain (FHA)-domain with Mrc1 (Claspin) at stalled forks. We report here that nutrient starvation results in post-translational changes to Cds1 and the loss of Mrc1. A drop in glucose after a down-shift from 3% to 0.1–0.3%, or when cells enter the stationary phase, triggers a sharp decline in Mrc1 and the accumulation of insoluble Cds1. Before this transition, Cds1 is transiently activated and phosphorylated by Rad3 when glucose levels fall. Because this coincides with the phosphorylation of histone 2AX at S129 by Rad3, an event that occurs towards the end of every unperturbed S phase, we suggest that a glucose limitation promotes the exit from the S phase. Since nitrogen starvation also depletes Mrc1 while Cds1 is post-translationally modified, we suggest that nutrient limitation is the general signal that promotes exit from S phase before it inactivates the Mrc1–Cds1 signalling component. Why Cds1 accumulates in resting cells while its activator Mrc1 declines is, as yet, unclear but suggests a novel function of Cds1 in non-replicating cells.
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Affiliation(s)
- Jessica Fletcher
- School of Medical Sciences, Bangor University, Bangor LL57 2UW, UK.
- Medical School, Swansea University, Swansea SA2 8PP, UK.
| | - Liam Griffiths
- School of Medical Sciences, Bangor University, Bangor LL57 2UW, UK.
| | - Thomas Caspari
- School of Medical Sciences, Bangor University, Bangor LL57 2UW, UK.
- Postgraduate Doctoral Studies, Paracelsus Medical University, 5020 Salzburg, Austria.
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9
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Vishwanatha A, D'Souza CJM, Schweingruber ME. Genes Controlling 2-deoxyglucose Induced Lysis and Formation of Reactive Oxygen Species in Schizosaccharomyces pombe. Pol J Microbiol 2017; 66:393-396. [PMID: 29319508 DOI: 10.5604/01.3001.0010.4877] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Schizosaccharomyces pombe cells of strains each carrying a deletion of one of the genes snf5, ypa1, pho7 and pas1 and of a strain overexpressing gene odr1, have been previously shown to grow in presence of the toxic glucose analogue 2-deoxyglucose (2-DG). Here we report that these genes control 2-DG induced lysis and are, with the exception of odr1, also involved in control of formation of reactive oxygen species (ROS) upon exposure of cells to H2O2. Lysis of deletion strains, but not of strain overexpressing odr1, is dependent on glucose concentration of the medium whereas ROS formation is glucose independent.
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Affiliation(s)
- Akshay Vishwanatha
- Department of Studies in Biochemistry, University of Mysore, Manasagangotri, Mysuru, Karnataka, India
| | - Cletus J M D'Souza
- Department of Studies in Biochemistry, University of Mysore, Manasagangotri, Mysuru, Karnataka, India
| | - Martin E Schweingruber
- Department of Studies in Biochemistry, University of Mysore, Manasagangotri, Mysuru, Karnataka, India
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10
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Madrid M, Vázquez-Marín B, Soto T, Franco A, Gómez-Gil E, Vicente-Soler J, Gacto M, Pérez P, Cansado J. Differential functional regulation of protein kinase C (PKC) orthologs in fission yeast. J Biol Chem 2017; 292:11374-11387. [PMID: 28536259 DOI: 10.1074/jbc.m117.786087] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2017] [Revised: 05/22/2017] [Indexed: 11/06/2022] Open
Abstract
The two PKC orthologs Pck1 and Pck2 in the fission yeast Schizosaccharomyces pombe operate in a redundant fashion to control essential functions, including morphogenesis and cell wall biosynthesis, as well as the activity of the cell integrity pathway and its core element, the MAPK Pmk1. We show here that, despite the strong structural similarity and functional redundancy of these two enzymes, the mechanisms regulating their maturation, activation, and stabilization have a remarkably distinct biological impact on both kinases. We found that, in contrast to Pck2, putative in vivo phosphorylation of Pck1 within the conserved activation loop, turn, and hydrophobic motifs is essential for Pck1 stability and biological functions. Constitutive Pck activation promoted dephosphorylation and destabilization of Pck2, whereas it enhanced Pck1 levels to interfere with proper downstream signaling to the cell integrity pathway via Pck2. Importantly, although catalytic activity was essential for Pck1 function, Pck2 remained partially functional independent of its catalytic activity. Our findings suggest that early divergence from a common ancestor in fission yeast involved important changes in the mechanisms regulating catalytic activation and stability of PKC family members to allow for flexible and dynamic control of downstream functions, including MAPK signaling.
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Affiliation(s)
- Marisa Madrid
- From the Yeast Physiology Group, Department of Genetics and Microbiology, Facultad de Biología, Universidad de Murcia, 30071 Murcia, Spain and
| | - Beatriz Vázquez-Marín
- From the Yeast Physiology Group, Department of Genetics and Microbiology, Facultad de Biología, Universidad de Murcia, 30071 Murcia, Spain and
| | - Teresa Soto
- From the Yeast Physiology Group, Department of Genetics and Microbiology, Facultad de Biología, Universidad de Murcia, 30071 Murcia, Spain and
| | - Alejandro Franco
- From the Yeast Physiology Group, Department of Genetics and Microbiology, Facultad de Biología, Universidad de Murcia, 30071 Murcia, Spain and
| | - Elisa Gómez-Gil
- From the Yeast Physiology Group, Department of Genetics and Microbiology, Facultad de Biología, Universidad de Murcia, 30071 Murcia, Spain and
| | - Jero Vicente-Soler
- From the Yeast Physiology Group, Department of Genetics and Microbiology, Facultad de Biología, Universidad de Murcia, 30071 Murcia, Spain and
| | - Mariano Gacto
- From the Yeast Physiology Group, Department of Genetics and Microbiology, Facultad de Biología, Universidad de Murcia, 30071 Murcia, Spain and
| | - Pilar Pérez
- the Instituto de Biología Funcional y Genómica, Consejo Superior de Investigaciones Científicas, Universidad de Salamanca, 37007 Salamanca, Spain
| | - José Cansado
- From the Yeast Physiology Group, Department of Genetics and Microbiology, Facultad de Biología, Universidad de Murcia, 30071 Murcia, Spain and
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11
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Vishwanatha A, D'Souza CJM. Multifaceted effects of antimetabolite and anticancer drug, 2-deoxyglucose on eukaryotic cancer models budding and fission yeast. IUBMB Life 2017; 69:137-147. [DOI: 10.1002/iub.1599] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2016] [Accepted: 12/20/2016] [Indexed: 01/14/2023]
Affiliation(s)
- Akshay Vishwanatha
- Department of Studies in Biochemistry; University of Mysore; Manasagangotri Mysore Karnataka India
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12
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Multiple crosstalk between TOR and the cell integrity MAPK signaling pathway in fission yeast. Sci Rep 2016; 6:37515. [PMID: 27876895 PMCID: PMC5120329 DOI: 10.1038/srep37515] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Accepted: 10/28/2016] [Indexed: 02/07/2023] Open
Abstract
In eukaryotic cells, the highly conserved Target of Rapamycin (TOR) and the Mitogen Activated Protein Kinase (MAPK) signaling pathways elicit adaptive responses to extra- and intracellular conditions by regulating essential cellular functions. However, the nature of the functional relationships between both pathways is not fully understood. In the fission yeast Schizosaccharomyces pombe the cell integrity MAPK pathway (CIP) regulates morphogenesis, cell wall structure and ionic homeostasis. We show that the Rab GTPase Ryh1, a TORC2 complex activator, cross-activates the CIP and its core member, the MAPK Pmk1, by two distinct mechanisms. The first one involves TORC2 and its downstream effector, Akt ortholog Gad8, which together with TORC1 target Psk1 increase protein levels of the PKC ortholog Pck2 during cell wall stress or glucose starvation. Also, Ryh1 activates Pmk1 in a TORC2-independent fashion by prompting plasma membrane trafficking and stabilization of upstream activators of the MAPK cascade, including PDK ortholog Ksg1 or Rho1 GEF Rgf1. Besides, stress-activated Pmk1 cross-inhibits Ryh1 signaling by decreasing the GTPase activation cycle, and this ensures cell growth during alterations in phosphoinositide metabolism. Our results reveal a highly intricate cross-regulatory relationship between both pathways that warrants adequate cell adaptation and survival in response to environmental changes.
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Vishwanatha A, Rallis C, Bevkal Subramanyaswamy S, D'Souza CJM, Bähler J, Schweingruber ME. Identification of nuclear genes affecting 2-Deoxyglucose resistance in Schizosaccharomyces pombe. FEMS Yeast Res 2016; 16:fow061. [PMID: 27481777 PMCID: PMC5452730 DOI: 10.1093/femsyr/fow061] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/25/2016] [Indexed: 01/16/2023] Open
Abstract
2-Deoxyglucose (2-DG) is a toxic glucose analog. To identify genes involved in 2-DG toxicity in Schizosaccharomyces pombe, we screened a wild-type overexpression library for genes which render cells 2-DG resistant. A gene we termed odr1, encoding an uncharacterized hydrolase, led to strong resistance and altered invertase expression when overexpressed. We speculate that Odr1 neutralizes the toxic form of 2-DG, similar to the Saccharomyces cerevisiae Dog1 and Dog2 phosphatases which dephosphorylate 2-DG-6-phosphate synthesized by hexokinase. In a complementary approach, we screened a haploid deletion library to identify 2-DG-resistant mutants. This screen identified the genes snf5, ypa1, pas1 and pho7. In liquid medium, deletions of these genes conferred 2-DG resistance preferentially under glucose-repressed conditions. The deletion mutants expressed invertase activity more constitutively than the control strain, indicating defects in the control of glucose repression. No S. cerevisiae orthologs of the pho7 gene is known, and no 2-DG resistance has been reported for any of the deletion mutants of the other genes identified here. Moreover, 2-DG leads to derepressed invertase activity in S. pombe, while in S. cerevisiae it becomes repressed. Taken together, these findings suggest that mechanisms involved in 2-DG resistance differ between budding and fission yeasts.
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Affiliation(s)
- Akshay Vishwanatha
- Department of Studies in Biochemistry, University of Mysore, Manasagangotri, Mysuru 570 006, Karnataka, India
| | - Charalampos Rallis
- Research Department of Genetics, Evolution and Environment, UCL Institute of Healthy Ageing, University College London, London WC1E 6BT, UK
| | - Shubha Bevkal Subramanyaswamy
- Department of Studies in Biochemistry, University of Mysore, Manasagangotri, Mysuru 570 006, Karnataka, India Institute of Cell Biology, University of Bern, Baltzerstrasse 4, CH-3012 Bern, Switzerland
| | | | - Jürg Bähler
- Research Department of Genetics, Evolution and Environment, UCL Institute of Healthy Ageing, University College London, London WC1E 6BT, UK
| | - Martin Ernst Schweingruber
- Department of Studies in Biochemistry, University of Mysore, Manasagangotri, Mysuru 570 006, Karnataka, India
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Bond ME, Brown R, Rallis C, Bähler J, Mole SE. A central role for TOR signalling in a yeast model for juvenile CLN3 disease. MICROBIAL CELL 2015; 2:466-480. [PMID: 28357272 PMCID: PMC5354605 DOI: 10.15698/mic2015.12.241] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Yeasts provide an excellent genetically tractable eukaryotic system for investigating the function of genes in their biological context, and are especially relevant for those conserved genes that cause disease. We study the role of btn1, the orthologue of a human gene that underlies an early onset neurodegenerative disease (juvenile CLN3 disease, neuronal ceroid lipofuscinosis (NCLs) or Batten disease) in the fission yeast Schizosaccharomyces pombe. A global screen for genetic interactions with btn1 highlighted a conserved key signalling hub in which multiple components functionally relate to this conserved disease gene. This signalling hub includes two major mitogen-activated protein kinase (MAPK) cascades, and centers on the Tor kinase complexes TORC1 and TORC2. We confirmed that yeast cells modelling CLN3 disease exhibit features consistent with dysfunction in the TORC pathways, and showed that modulating TORC function leads to a comprehensive rescue of defects in this yeast disease model. The same pathways may be novel targets in the development of therapies for the NCLs and related diseases.
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Affiliation(s)
- Michael E Bond
- MRC Laboratory for Molecular Cell Biology, University College London, London WC1E 6BT, UK
| | - Rachel Brown
- MRC Laboratory for Molecular Cell Biology, University College London, London WC1E 6BT, UK
| | - Charalampos Rallis
- Department of Genetics, Evolution and Environment, University College London, London WC1E 6BT, UK. ; Institute of Healthy Ageing, University College London, London WC1E 6BT, UK
| | - Jürg Bähler
- Department of Genetics, Evolution and Environment, University College London, London WC1E 6BT, UK. ; Institute of Healthy Ageing, University College London, London WC1E 6BT, UK
| | - Sara E Mole
- MRC Laboratory for Molecular Cell Biology, University College London, London WC1E 6BT, UK. ; UCL Institute of Child Health, 30 Guilford Street, London WC1N 1EH, UK. ; Department of Genetics, Evolution and Environment, University College London, London WC1E 6BT, UK
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15
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Takeda K, Starzynski C, Mori A, Yanagida M. The critical glucose concentration for respiration-independent proliferation of fission yeast, Schizosaccharomyces pombe. Mitochondrion 2015; 22:91-5. [DOI: 10.1016/j.mito.2015.04.003] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2015] [Revised: 03/30/2015] [Accepted: 04/09/2015] [Indexed: 11/25/2022]
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16
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Cohen A, Kupiec M, Weisman R. 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. J Biol Chem 2014; 289:21727-37. [PMID: 24928510 DOI: 10.1074/jbc.m114.573824] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The target of rapamycin (TOR) kinase belongs to the highly conserved eukaryotic family of phosphatidylinositol 3-kinase-related kinases. TOR proteins are found at the core of two evolutionary conserved complexes, known as TORC1 and TORC2. In fission yeast, TORC2 is dispensable for proliferation under optimal growth conditions but is required for starvation and stress responses. TORC2 has been implicated in a wide variety of functions; however, the signals that regulate TORC2 activity have so far remained obscure. TORC2 has one known direct substrate, the AGC kinase Gad8, which is related to AKT in human cells. Gad8 is phosphorylated by TORC2 at Ser-546 (equivalent to AKT Ser-473), leading to its activation. Here, we show that glucose is necessary and sufficient to induce Gad8 Ser-546 phosphorylation in vivo and Gad8 kinase activity in vitro. The glucose signal that activates TORC2-Gad8 is mediated via the cAMP/PKA pathway, a major glucose-sensing pathway. By contrast, Pmk1, similar to human extracellular signal-regulated kinases and a major stress-induced mitogen activated protein kinase (MAPK) in fission yeast, inhibits TORC2-dependent Gad8 phosphorylation and activation. Inhibition of TORC2-Gad8 also occurs in response to ionic or osmotic stress, in a manner dependent on the cAMP/PKA and Pmk1-MAPK signaling pathways. Our findings highlight the significance of glucose availability in regulation of TORC2-Gad8 and indicate a novel link between the cAMP/PKA, Pmk1/MAPK, and TORC2-Gad8 signaling.
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Affiliation(s)
- Adiel Cohen
- From the Department of Natural and Life Sciences, Open University of Israel, University Road 1, 4353701 Ranana and
| | - Martin Kupiec
- the Department of Molecular Microbiology and Biotechnology, Tel Aviv University, 69978 Tel Aviv, Israel
| | - Ronit Weisman
- From the Department of Natural and Life Sciences, Open University of Israel, University Road 1, 4353701 Ranana and
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Leong HS, Dawson K, Wirth C, Li Y, Connolly Y, Smith DL, Wilkinson CRM, Miller CJ. A global non-coding RNA system modulates fission yeast protein levels in response to stress. Nat Commun 2014; 5:3947. [PMID: 24853205 PMCID: PMC4050258 DOI: 10.1038/ncomms4947] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2013] [Accepted: 04/25/2014] [Indexed: 12/24/2022] Open
Abstract
Non-coding RNAs (ncRNAs) are frequent and prevalent across the taxa. Although individual non-coding loci have been assigned a function, most are uncharacterized. Their global biological significance is unproven and remains controversial. Here we investigate the role played by ncRNAs in the stress response of Schizosaccharomyces pombe. We integrate global proteomics and RNA sequencing data to identify a systematic programme in which elevated antisense RNA arising both from ncRNAs and from 3'-overlapping convergent gene pairs is directly associated with substantial reductions in protein levels throughout the genome. We describe an extensive array of ncRNAs with trans associations that have the potential to influence multiple pathways. Deletion of one such locus reduces levels of atf1, a transcription factor downstream of the stress-activated mitogen-activated protein kinase (MAPK) pathway, and alters sensitivity to oxidative stress. These non-coding transcripts therefore regulate specific stress responses, adding unanticipated information-processing capacity to the MAPK signalling system.
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Affiliation(s)
- Hui Sun Leong
- Applied Computational Biology and Bioinformatics Group, Cancer
Research UK Manchester Institute, University of Manchester,
Wilmslow Road, Manchester
M20 4BX, UK
- These authors contributed equally to this work
| | - Keren Dawson
- Applied Computational Biology and Bioinformatics Group, Cancer
Research UK Manchester Institute, University of Manchester,
Wilmslow Road, Manchester
M20 4BX, UK
- These authors contributed equally to this work
| | - Chris Wirth
- Applied Computational Biology and Bioinformatics Group, Cancer
Research UK Manchester Institute, University of Manchester,
Wilmslow Road, Manchester
M20 4BX, UK
| | - Yaoyong Li
- Applied Computational Biology and Bioinformatics Group, Cancer
Research UK Manchester Institute, University of Manchester,
Wilmslow Road, Manchester
M20 4BX, UK
| | - Yvonne Connolly
- Biological Mass Spectrometry Facility, Cancer Research UK
Manchester Institute, University of Manchester, Wilmslow
Road, Manchester
M20 4BX, UK
| | - Duncan L. Smith
- Biological Mass Spectrometry Facility, Cancer Research UK
Manchester Institute, University of Manchester, Wilmslow
Road, Manchester
M20 4BX, UK
| | - Caroline R. M. Wilkinson
- Cell Regulation Group, Cancer Research UK Manchester Institute,
University of Manchester, Wilmslow Road,
Manchester
M20 4BX, UK
| | - Crispin J. Miller
- Applied Computational Biology and Bioinformatics Group, Cancer
Research UK Manchester Institute, University of Manchester,
Wilmslow Road, Manchester
M20 4BX, UK
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Oda Y, Kimura M, Kose S, Fasken MB, Corbett AH, Imamoto N. TheSchizosaccharomyces pombeHikeshi/Opi10 protein has similar biochemical functions to its human homolog but acts in different physiological contexts. FEBS Lett 2014; 588:1899-905. [DOI: 10.1016/j.febslet.2014.04.018] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2014] [Revised: 04/11/2014] [Accepted: 04/14/2014] [Indexed: 01/19/2023]
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19
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Sánchez-Mir L, Soto T, Franco A, Madrid M, Viana RA, Vicente J, Gacto M, Pérez P, Cansado J. Rho1 GTPase and PKC ortholog Pck1 are upstream activators of the cell integrity MAPK pathway in fission yeast. PLoS One 2014; 9:e88020. [PMID: 24498240 PMCID: PMC3909290 DOI: 10.1371/journal.pone.0088020] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2013] [Accepted: 01/02/2014] [Indexed: 12/22/2022] Open
Abstract
In the fission yeast Schizosaccharomyces pombe the cell integrity pathway (CIP) orchestrates multiple biological processes like cell wall maintenance and ionic homeostasis by fine tuning activation of MAPK Pmk1 in response to various environmental conditions. The small GTPase Rho2 positively regulates the CIP through protein kinase C ortholog Pck2. However, Pmk1 retains some function in mutants lacking either Rho2 or Pck2, suggesting the existence of additional upstream regulatory elements to modulate its activity depending on the nature of the environmental stimulus. The essential GTPase Rho1 is a candidate to control the activity of the CIP by acting upstream of Pck2, whereas Pck1, a second PKC ortholog, appears to negatively regulate Pmk1 activity. However, the exact regulatory nature of these two proteins within the CIP has remained elusive. By exhaustive characterization of strains expressing a hypomorphic Rho1 allele (rho1-596) in different genetic backgrounds we show that both Rho1 and Pck1 are positive upstream regulatory members of the CIP in addition to Rho2 and Pck2. In this new model Rho1 and Rho2 control Pmk1 basal activity during vegetative growth mainly through Pck2. Notably, whereas Rho2-Pck2 elicit Pmk1 activation in response to most environmental stimuli, Rho1 drives Pmk1 activation through either Pck2 or Pck1 exclusively in response to cell wall damage. Our study reveals the intricate and complex functional architecture of the upstream elements participating in this signaling pathway as compared to similar routes from other simple eukaryotic organisms.
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Affiliation(s)
- Laura Sánchez-Mir
- Yeast Physiology Group, Department of Genetics and Microbiology, Facultad de Biología, Universidad de Murcia, Murcia, Spain
| | - Teresa Soto
- Yeast Physiology Group, Department of Genetics and Microbiology, Facultad de Biología, Universidad de Murcia, Murcia, Spain
| | - Alejandro Franco
- Yeast Physiology Group, Department of Genetics and Microbiology, Facultad de Biología, Universidad de Murcia, Murcia, Spain
| | - Marisa Madrid
- Yeast Physiology Group, Department of Genetics and Microbiology, Facultad de Biología, Universidad de Murcia, Murcia, Spain
| | - Raúl A. Viana
- Instituto de Biología Funcional y Genómica, Consejo Superior de Investigaciones Científicas/Departamento de Microbiología y Genética, Universidad de Salamanca, Salamanca, Spain
| | - Jero Vicente
- Yeast Physiology Group, Department of Genetics and Microbiology, Facultad de Biología, Universidad de Murcia, Murcia, Spain
| | - Mariano Gacto
- Yeast Physiology Group, Department of Genetics and Microbiology, Facultad de Biología, Universidad de Murcia, Murcia, Spain
| | - Pilar Pérez
- Instituto de Biología Funcional y Genómica, Consejo Superior de Investigaciones Científicas/Departamento de Microbiología y Genética, Universidad de Salamanca, Salamanca, Spain
| | - José Cansado
- Yeast Physiology Group, Department of Genetics and Microbiology, Facultad de Biología, Universidad de Murcia, Murcia, Spain
- * E-mail:
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Madrid M, Jiménez R, Sánchez-Mir L, Soto T, Franco A, Vicente-Soler J, Gacto M, Pérez P, Cansado J. Multiple regulatory levels influence cell integrity control by PKC ortholog Pck2 in fission yeast. J Cell Sci 2014; 128:266-80. [DOI: 10.1242/jcs.158295] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Fission yeast PKC ortholog Pck2 controls cell wall synthesis and is a major upstream activator of the cell integrity pathway (CIP) and its core component, MAP kinase Pmk1, in response to environmental stimuli. We show that in vivo phosphorylation of Pck2 at the conserved T842 activation loop during growth and in response to different stresses is mediated by the PDK ortholog Ksg1 and an autophosphorylation mechanism. However, T842 phosphorylation is not essential for Pmk1 activation, and putative phosphorylation at T846 might play an additional role for Pck2 catalytic activation and downstream signaling. These events together with turn motif autophosphorylation at T984 and binding to small GTPases Rho1 and/or Rho2 stabilize and render Pck2 competent to exert its biological functions. Remarkably, the TORC2 complex does not participate in catalytic activation of Pck2, but instead contributes to de novo Pck2 synthesis which is essential to activate the CIP in response to cell wall damage or glucose exhaustion. These results unveil a novel mechanism whereby TOR regulates PKC function at a translational level and add a new regulatory layer to MAPK signaling cascades.
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21
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Negative functional interaction between cell integrity MAPK pathway and Rho1 GTPase in fission yeast. Genetics 2013; 195:421-32. [PMID: 23934882 DOI: 10.1534/genetics.113.154807] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Rho1 GTPase is the main activator of cell wall glucan biosynthesis and regulates actin cytoskeleton in fungi, including Schizosaccharomyces pombe. We have obtained a fission yeast thermosensitive mutant strain carrying the rho1-596 allele, which displays reduced Rho1 GTPase activity. This strain has severe cell wall defects and a thermosensitive growth, which is partially suppressed by osmotic stabilization. In a global screening for rho1-596 multicopy suppresors the pmp1+ gene was identified. Pmp1 is a dual specificity phosphatase that negatively regulates the Pmk1 mitogen-activated protein kinase (MAPK) cell integrity pathway. Accordingly, elimination of Pmk1 MAPK partially rescued rho1-596 thermosensitivity, corroborating the unexpected antagonistic functional relationship of these genes. We found that rho1-596 cells displayed increased basal activation of the cell integrity MAPK pathway and therefore were hypersensitive to MgCl2 and FK506. Moreover, the absence of calcineurin was lethal for rho1-596. We found a higher level of calcineurin activity in rho1-596 than in wild-type cells, and overexpression of constitutively active calcineurin partially rescued rho1-596 thermosensitivity. All together our results suggest that loss of Rho1 function causes an increase in the cell integrity MAPK activity, which is detrimental to the cells and turns calcineurin activity essential.
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