1
|
Cacciotti A, Beccaccioli M, Reverberi M. The CRZ1 transcription factor in plant fungi: regulation mechanism and impact on pathogenesis. Mol Biol Rep 2024; 51:647. [PMID: 38727981 PMCID: PMC11087348 DOI: 10.1007/s11033-024-09593-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2024] [Accepted: 04/29/2024] [Indexed: 05/13/2024]
Abstract
Calcium (Ca2+) is a universal signaling molecule that is tightly regulated, and a fleeting elevation in cytosolic concentration triggers a signal cascade within the cell, which is crucial for several processes such as growth, tolerance to stress conditions, and virulence in fungi. The link between calcium and calcium-dependent gene regulation in cells relies on the transcription factor Calcineurin-Responsive Zinc finger 1 (CRZ1). The direct regulation of approximately 300 genes in different stress pathways makes it a hot topic in host-pathogen interactions. Notably, CRZ1 can modulate several pathways and orchestrate cellular responses to different types of environmental insults such as osmotic stress, oxidative stress, and membrane disruptors. It is our belief that CRZ1 provides the means for tightly modulating and synchronizing several pathways allowing pathogenic fungi to install into the apoplast and eventually penetrate plant cells (i.e., ROS, antimicrobials, and quick pH variation). This review discusses the structure, function, regulation of CRZ1 in fungal physiology and its role in plant pathogen virulence.
Collapse
Affiliation(s)
- A Cacciotti
- Department of Environmental Biology, Sapienza University of Rome, Rome, Italy
| | - M Beccaccioli
- Department of Environmental Biology, Sapienza University of Rome, Rome, Italy.
| | - M Reverberi
- Department of Environmental Biology, Sapienza University of Rome, Rome, Italy
| |
Collapse
|
2
|
Flynn MJ, Harper NW, Li R, Zhu LJ, Lee MJ, Benanti JA. Calcineurin promotes adaptation to chronic stress through two distinct mechanisms. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.19.585797. [PMID: 38562881 PMCID: PMC10983906 DOI: 10.1101/2024.03.19.585797] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/04/2024]
Abstract
Adaptation to environmental stress requires coordination between stress-defense programs and cell cycle progression. The immediate response to many stressors has been well characterized, but how cells survive in challenging environments long-term is unknown. Here, we investigate the role of the stress-activated phosphatase calcineurin (CN) in adaptation to chronic CaCl2 stress in Saccharomyces cerevisiae. We find that prolonged exposure to CaCl2 impairs mitochondrial function and demonstrate that cells respond to this stressor using two CN-dependent mechanisms - one that requires the downstream transcription factor Crz1 and another that is Crz1-independent. Our data indicate that CN maintains cellular fitness by promoting cell cycle progression and preventing CaCl2-induced cell death. When Crz1 is present, transient CN activation suppresses cell death and promotes adaptation despite high levels of mitochondrial loss. However, in the absence of Crz1, prolonged activation of CN prevents mitochondrial loss and further cell death by upregulating glutathione (GSH) biosynthesis genes thereby mitigating damage from reactive oxygen species. These findings illustrate how cells maintain long-term fitness during chronic stress and suggest that CN promotes adaptation in challenging environments by multiple mechanisms.
Collapse
Affiliation(s)
- Mackenzie J Flynn
- Department of Molecular, Cell and Cancer Biology, University of Massachusetts Chan Medical School, Worcester, MA 01605
- Interdisciplinary Graduate Program, Morningside Graduate School of Biomedical Sciences, University of Massachusetts Chan Medical School, Worcester, MA 01605
| | - Nicholas W Harper
- Interdisciplinary Graduate Program, Morningside Graduate School of Biomedical Sciences, University of Massachusetts Chan Medical School, Worcester, MA 01605
- Department of Systems Biology, University of Massachusetts Chan Medical School, Worcester, MA 01605
| | - Rui Li
- Department of Molecular, Cell and Cancer Biology, University of Massachusetts Chan Medical School, Worcester, MA 01605
| | - Lihua Julie Zhu
- Department of Molecular, Cell and Cancer Biology, University of Massachusetts Chan Medical School, Worcester, MA 01605
- Department of Genomics and Computational Biology, University of Massachusetts Chan Medical School, Worcester MA 01605
- Program in Molecular Medicine, University of Massachusetts Chan Medical School, Worcester MA 01605
| | - Michael J Lee
- Department of Systems Biology, University of Massachusetts Chan Medical School, Worcester, MA 01605
| | - Jennifer A Benanti
- Department of Molecular, Cell and Cancer Biology, University of Massachusetts Chan Medical School, Worcester, MA 01605
| |
Collapse
|
3
|
Gupta S, Kumar A, Tamuli R. CRZ1 transcription factor is involved in cell survival, stress tolerance, and virulence in fungi. J Biosci 2022. [DOI: 10.1007/s12038-022-00294-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
|
4
|
Yang Y, Xie P, Li Y, Bi Y, Prusky DB. Updating Insights into the Regulatory Mechanisms of Calcineurin-Activated Transcription Factor Crz1 in Pathogenic Fungi. J Fungi (Basel) 2022; 8:jof8101082. [PMID: 36294647 PMCID: PMC9604740 DOI: 10.3390/jof8101082] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2022] [Revised: 10/06/2022] [Accepted: 10/10/2022] [Indexed: 11/05/2022] Open
Abstract
Ca2+, as a second messenger in cells, enables organisms to adapt to different environmental stresses by rapidly sensing and responding to external stimuli. In recent years, the Ca2+ mediated calcium signaling pathway has been studied systematically in various mammals and fungi, indicating that the pathway is conserved among organisms. The pathway consists mainly of complex Ca2+ channel proteins, calcium pumps, Ca2+ transporters and many related proteins. Crz1, a transcription factor downstream of the calcium signaling pathway, participates in regulating cell survival, ion homeostasis, infection structure development, cell wall integrity and virulence. This review briefly summarizes the Ca2+ mediated calcium signaling pathway and regulatory roles in plant pathogenic fungi. Based on discussing the structure and localization of transcription factor Crz1, we focus on the regulatory role of Crz1 on growth and development, stress response, pathogenicity of pathogenic fungi and its regulatory mechanisms. Furthermore, we explore the cross-talk between Crz1 and other signaling pathways. Combined with the important role and pathogenic mechanism of Crz1 in fungi, the new strategies in which Crz1 may be used as a target to explore disease control in practice are also discussed.
Collapse
Affiliation(s)
- Yangyang Yang
- College of Food Science and Engineering, Gansu Agricultural University, Lanzhou 730070, China
| | - Pengdong Xie
- College of Food Science and Engineering, Gansu Agricultural University, Lanzhou 730070, China
| | - Yongcai Li
- College of Food Science and Engineering, Gansu Agricultural University, Lanzhou 730070, China
- Correspondence:
| | - Yang Bi
- College of Food Science and Engineering, Gansu Agricultural University, Lanzhou 730070, China
| | - Dov B. Prusky
- Department of Postharvest Science, Agricultural Research Organization, Volcani Center, Rishon LeZion 7505101, Israel
| |
Collapse
|
5
|
Improvement of Lignocellulolytic Enzyme Production Mediated by Calcium Signaling in Bacillus subtilis Z2 under Graphene Oxide Stress. Appl Environ Microbiol 2022; 88:e0096022. [PMID: 36121214 PMCID: PMC9552604 DOI: 10.1128/aem.00960-22] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
An increase in exoenzyme production can be enhanced by environmental stresses such as graphene oxide (GO) stress, but the link between the two events is still unclear. In this work, the effect of GO as an environmental stress factor on exoenzyme (lignocellulolytic enzyme, amylase, peptidase, and protease) biosynthesis was investigated in Bacillus subtilis Z2, and a plausible mechanism by which cytosolic Ca2+ regulates lignocellulolytic enzyme production in B. subtilis Z2 subjected to GO stress was proposed. The filter paper-hydrolyzing (FPase [representing total cellulase]), carboxymethylcellulase (CMCase [representing endoglucanase]), and β-glucosidase activities and extracellular protein concentration of the wild-type strain under 10 μg/mL GO stress were 1.37-, 1.64-, 1.24-, and 1.16-fold those of the control (without GO stress), respectively. Correspondingly, the transcription levels of lignocellulolytic enzyme genes, cytosolic Ca2+ level, and biomass concentration of B. subtilis were all increased. With lignocellulolytic enzyme from B. subtilis used to hydrolyze alkali-pretreated rice straw, the released reducing sugar concentration reached 265.53 mg/g, and the removal rates of cellulose, hemicellulose, and lignin were 52.4%, 30.1%, and 7.5%, respectively. Furthermore, transcriptome data revealed that intracellular Ca2+ homeostasis played a key role in regulating the levels of gene transcription related to the synthesis of lignocellulolytic enzymes and exoenzymes. Finally, the use of Ca2+ inhibitors (LaCl3 and EDTA) and deletion of spcF (a calmodulin-like protein gene) further demonstrated that the overexpression of those genes was regulated via calcium signaling in B. subtilis subjected to GO stress. IMPORTANCE To effectively convert lignocellulose into fermentable sugars, high lignocellulolytic enzyme loading is needed. Graphene oxide (GO) has been shown to promote exoenzyme (lignocellulolytic enzyme, amylase, peptidase, and protease) production in some microorganisms; however, the regulatory mechanism of the biosynthesis of lignocellulolytic enzymes under GO stress remains unclear. In this work, the lignocellulolytic enzyme production of B. subtilis under GO stress was investigated, and the potential mechanism by which B. subtilis enhanced lignocellulolytic enzyme production through the calcium signaling pathway under GO stress was proposed. This work revealed the role of calcium signaling in the production of enzymes under external environmental stress and provided a direction to facilitate lignocellulolytic enzyme production by B. subtilis.
Collapse
|
6
|
Cells under pressure: how yeast cells respond to mechanical forces. Trends Microbiol 2022; 30:495-510. [PMID: 35000797 DOI: 10.1016/j.tim.2021.11.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Revised: 10/31/2021] [Accepted: 11/08/2021] [Indexed: 11/23/2022]
Abstract
In their natural habitats, unicellular fungal microbes are exposed to a myriad of mechanical cues such as shear forces from fluid flow, osmotic changes, and contact forces arising from microbial expansion in confined niches. While the rigidity of the cell wall is critical to withstand such external forces and balance high internal turgor pressure, it poses mechanical challenges during physiological processes such as cell growth, division, and mating that require cell wall remodeling. Thus, even organisms as simple as yeast have evolved complex signaling networks to sense and respond to intrinsic and extrinsic mechanical forces. In this review, we summarize the type and origin of mechanical forces experienced by unicellular yeast and discuss how these forces reorganize cell polarity and how pathogenic fungi exploit polarized assemblies to track weak spots in host tissues for successful penetration. We then describe mechanisms of force-sensing by conserved sets of mechanosensors. Finally, we elaborate downstream mechanotransduction mechanisms that orchestrate appropriate cellular responses, leading to improved mechanical fitness.
Collapse
|
7
|
Zhao K, Liu Z, Li M, Hu Y, Yang L, Song X, Qin Y. Drafting Penicillium oxalicum calcineurin-CrzA pathway by combining the analysis of phenotype, transcriptome, and endogenous protein-protein interactions. Fungal Genet Biol 2021; 158:103652. [PMID: 34920105 DOI: 10.1016/j.fgb.2021.103652] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2021] [Revised: 11/17/2021] [Accepted: 12/08/2021] [Indexed: 11/04/2022]
Abstract
Fungi sense environmental signals and coordinate growth, development, and metabolism accordingly. Calcium-calmodulin-calcineurin signaling is a conserved cascade pathway in fungi. One of the most important downstream targets of this pathway is the transcription factor Crz1/CrzA, which plays an essential role in various cellular processes. The putative collaborators of Penicillium oxalicum CrzA (PoCrzA) were found, through tandem affinity purification followed by mass spectrometric analysis (TAP-MS). A total of 50 protein-protein interaction collaborators of PoCrzA were observed. Among them, some collaborators, such as the catalytic subunit of calcineurin (Cna1, calcineurin A), the regulatory catalytic subunit of calcineurin (Cnb1, calcineurin B), and a 14-3-3 protein Bmh1, which were previously reported in yeast, were identified. Some putative collaborators, including two karyopherins (exportin Los1 and importin Srp1), two kinases (Fus3 and Slt2p), and a general transcriptional corepressor (Cyc8), were also found. The CrzA deletion mutant ΔPocrzA exhibited slow hyphal growth, impaired conidiogenesis, and reduced extracellular cellulase synthesis. Phenotype and transcriptome analysis showed that PoCrzA regulated fungal development in a Flbs-BrlA-dependent manner and participated in cellulase synthesis by modulating cellulolytic gene expression. On the basis of the results of TAP-MS, transcriptome, and phenotypic analysis in P. oxalicum, our study was the first to draft the calcineurin-CrzA pathway in cellulolytic fungi.
Collapse
Affiliation(s)
- Kaili Zhao
- National Glycoengineering Research Center, Shandong University, No. 72 Binhai Road, Qingdao 266237, China.
| | - Zhongjiao Liu
- National Glycoengineering Research Center, Shandong University, No. 72 Binhai Road, Qingdao 266237, China.
| | - Mengxue Li
- National Glycoengineering Research Center, Shandong University, No. 72 Binhai Road, Qingdao 266237, China.
| | - Yueyan Hu
- National Glycoengineering Research Center, Shandong University, No. 72 Binhai Road, Qingdao 266237, China; State Key Laboratory of Microbial Technology, Microbial Technology Institute, Shandong University, No. 72 Binhai Road, Qingdao 266237, China.
| | - Ling Yang
- Vocational Education College, Dezhou University, Dezhou 253023, China.
| | - Xin Song
- National Glycoengineering Research Center, Shandong University, No. 72 Binhai Road, Qingdao 266237, China; State Key Laboratory of Microbial Technology, Microbial Technology Institute, Shandong University, No. 72 Binhai Road, Qingdao 266237, China.
| | - Yuqi Qin
- National Glycoengineering Research Center, Shandong University, No. 72 Binhai Road, Qingdao 266237, China; State Key Laboratory of Microbial Technology, Microbial Technology Institute, Shandong University, No. 72 Binhai Road, Qingdao 266237, China.
| |
Collapse
|
8
|
Hsu IS, Strome B, Lash E, Robbins N, Cowen LE, Moses AM. A functionally divergent intrinsically disordered region underlying the conservation of stochastic signaling. PLoS Genet 2021; 17:e1009629. [PMID: 34506483 PMCID: PMC8457507 DOI: 10.1371/journal.pgen.1009629] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Revised: 09/22/2021] [Accepted: 08/06/2021] [Indexed: 12/18/2022] Open
Abstract
Stochastic signaling dynamics expand living cells' information processing capabilities. An increasing number of studies report that regulators encode information in their pulsatile dynamics. The evolutionary mechanisms that lead to complex signaling dynamics remain uncharacterized, perhaps because key interactions of signaling proteins are encoded in intrinsically disordered regions (IDRs), whose evolution is difficult to analyze. Here we focused on the IDR that controls the stochastic pulsing dynamics of Crz1, a transcription factor in fungi downstream of the widely conserved calcium signaling pathway. We find that Crz1 IDRs from anciently diverged fungi can all respond transiently to calcium stress; however, only Crz1 IDRs from the Saccharomyces clade support pulsatility, encode extra information, and rescue fitness in competition assays, while the Crz1 IDRs from distantly related fungi do none of the three. On the other hand, we find that Crz1 pulsing is conserved in the distantly related fungi, consistent with the evolutionary model of stabilizing selection on the signaling phenotype. Further, we show that a calcineurin docking site in a specific part of the IDRs appears to be sufficient for pulsing and show evidence for a beneficial increase in the relative calcineurin affinity of this docking site. We propose that evolutionary flexibility of functionally divergent IDRs underlies the conservation of stochastic signaling by stabilizing selection.
Collapse
Affiliation(s)
- Ian S. Hsu
- Department of Cell & Systems Biology, University of Toronto, Toronto, Canada
| | - Bob Strome
- Department of Cell & Systems Biology, University of Toronto, Toronto, Canada
| | - Emma Lash
- Department of Molecular Genetics, University of Toronto, Toronto, Canada
| | - Nicole Robbins
- Department of Molecular Genetics, University of Toronto, Toronto, Canada
| | - Leah E. Cowen
- Department of Molecular Genetics, University of Toronto, Toronto, Canada
| | - Alan M. Moses
- Department of Cell & Systems Biology, University of Toronto, Toronto, Canada
- Department of Computer Science, University of Toronto, Toronto, Canada
- * E-mail:
| |
Collapse
|
9
|
Shwab EK, Juvvadi PR, Waitt G, Soderblom EJ, Barrington BC, Asfaw YG, Moseley MA, Steinbach WJ. Calcineurin-dependent dephosphorylation of the transcription factor CrzA at specific sites controls conidiation, stress tolerance, and virulence of Aspergillus fumigatus. Mol Microbiol 2019; 112:62-80. [PMID: 30927289 DOI: 10.1111/mmi.14254] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/24/2019] [Indexed: 12/15/2022]
Abstract
Calcium signaling through calcineurin and its major transcription factor (TF), CrzA, is integral to hyphal growth, stress response and virulence of the pathogenic fungus Aspergillus fumigatus, the leading etiology of invasive aspergillosis. Dephosphorylation of CrzA by calcineurin activates the TF, but the specific phosphorylation sites and their roles in the activation/inactivation mechanism are unknown. Mass spectroscopic analysis identified 20 phosphorylation sites, the majority of which were specific to filamentous fungi and distributed throughout the CrzA protein, with particular concentration in a serine-rich region N-terminal to the conserved DNA-binding domain (DBD). Site-directed mutagenesis of phosphorylated residues revealed that CrzA activity during calcium stimulation can only be suppressed by a high degree of phosphorylation in multiple regions of the protein. Our findings further suggest that this regulation is not solely accomplished through control of CrzA nuclear import. Additionally, we demonstrate the importance of the CrzA phosphorylation state in regulating growth, conidiation, calcium and cell wall stress tolerance, and virulence. Finally, we identify two previously undescribed nuclear localization sequences in the DBD. These findings provide novel insight into the phosphoregulation of CrzA which may be exploited to selectively target A. fumigatus.
Collapse
Affiliation(s)
- E Keats Shwab
- Division of Pediatric Infectious Diseases, Department of Pediatrics, Duke University Medical Center, Durham, NC, USA
| | - Praveen R Juvvadi
- Division of Pediatric Infectious Diseases, Department of Pediatrics, Duke University Medical Center, Durham, NC, USA
| | - Greg Waitt
- Duke Proteomics and Metabolomics Core Facility, Center for Genomic and Computational Biology, Duke University, Durham, NC, USA
| | - Erik J Soderblom
- Duke Proteomics and Metabolomics Core Facility, Center for Genomic and Computational Biology, Duke University, Durham, NC, USA
| | - Blake C Barrington
- Division of Pediatric Infectious Diseases, Department of Pediatrics, Duke University Medical Center, Durham, NC, USA
| | - Yohannes G Asfaw
- Department of Laboratory Animal Resources, Duke University Medical Center, Durham, NC, USA
| | - M Arthur Moseley
- Duke Proteomics and Metabolomics Core Facility, Center for Genomic and Computational Biology, Duke University, Durham, NC, USA
| | - William J Steinbach
- Division of Pediatric Infectious Diseases, Department of Pediatrics, Duke University Medical Center, Durham, NC, USA.,Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC, USA
| |
Collapse
|
10
|
Lu AX, Chong YT, Hsu IS, Strome B, Handfield LF, Kraus O, Andrews BJ, Moses AM. Integrating images from multiple microscopy screens reveals diverse patterns of change in the subcellular localization of proteins. eLife 2018; 7:e31872. [PMID: 29620521 PMCID: PMC5935485 DOI: 10.7554/elife.31872] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2017] [Accepted: 03/30/2018] [Indexed: 01/29/2023] Open
Abstract
The evaluation of protein localization changes on a systematic level is a powerful tool for understanding how cells respond to environmental, chemical, or genetic perturbations. To date, work in understanding these proteomic responses through high-throughput imaging has catalogued localization changes independently for each perturbation. To distinguish changes that are targeted responses to the specific perturbation or more generalized programs, we developed a scalable approach to visualize the localization behavior of proteins across multiple experiments as a quantitative pattern. By applying this approach to 24 experimental screens consisting of nearly 400,000 images, we differentiated specific responses from more generalized ones, discovered nuance in the localization behavior of stress-responsive proteins, and formed hypotheses by clustering proteins that have similar patterns. Previous approaches aim to capture all localization changes for a single screen as accurately as possible, whereas our work aims to integrate large amounts of imaging data to find unexpected new cell biology.
Collapse
Affiliation(s)
- Alex X Lu
- Department of Computer ScienceUniversity of TorontoTorontoCanada
| | - Yolanda T Chong
- Terrence Donnelly Centre for Cellular and Biomolecular ResearchUniversity of TorontoTorontoCanada
| | - Ian Shen Hsu
- Department of Cell and Systems BiologyUniversity of TorontoTorontoCanada
| | - Bob Strome
- Department of Cell and Systems BiologyUniversity of TorontoTorontoCanada
| | | | - Oren Kraus
- Department of Electrical and Computer EngineeringUniversity of TorontoTorontoCanada
| | - Brenda J Andrews
- Terrence Donnelly Centre for Cellular and Biomolecular ResearchUniversity of TorontoTorontoCanada
- Department of Molecular GeneticsUniversity of TorontoTorontoCanada
| | - Alan M Moses
- Department of Computer ScienceUniversity of TorontoTorontoCanada
- Department of Cell and Systems BiologyUniversity of TorontoTorontoCanada
- Center for Analysis of Genome Evolution and FunctionUniversity of TorontoTorontoCanada
| |
Collapse
|
11
|
Petrezsélyová S, López-Malo M, Canadell D, Roque A, Serra-Cardona A, Marqués MC, Vilaprinyó E, Alves R, Yenush L, Ariño J. Regulation of the Na+/K+-ATPase Ena1 Expression by Calcineurin/Crz1 under High pH Stress: A Quantitative Study. PLoS One 2016; 11:e0158424. [PMID: 27362362 PMCID: PMC4928930 DOI: 10.1371/journal.pone.0158424] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2016] [Accepted: 06/15/2016] [Indexed: 11/18/2022] Open
Abstract
Regulated expression of the Ena1 Na+-ATPase is a crucial event for adaptation to high salt and/or alkaline pH stress in the budding yeast Saccharomyces cerevisiae. ENA1 expression is under the control of diverse signaling pathways, including that mediated by the calcium-regulatable protein phosphatase calcineurin and its downstream transcription factor Crz1. We present here a quantitative study of the expression of Ena1 in response to alkalinization of the environment and we analyze the contribution of Crz1 to this response. Experimental data and mathematical models substantiate the existence of two stress-responsive Crz1-binding sites in the ENA1 promoter and estimate that the contribution of Crz1 to the early response of the ENA1 promoter is about 60%. The models suggest the existence of a second input with similar kinetics, which would be likely mediated by high pH-induced activation of the Snf1 kinase.
Collapse
Affiliation(s)
- Silvia Petrezsélyová
- Institut de Biotecnologia i Biomedicina, Universitat Autònoma de Barcelona, Cerdanyola del Vallès 08193, Barcelona, Spain
- Departament de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, Cerdanyola del Vallès 08193, Barcelona, Spain
| | - María López-Malo
- Institut de Biotecnologia i Biomedicina, Universitat Autònoma de Barcelona, Cerdanyola del Vallès 08193, Barcelona, Spain
- Departament de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, Cerdanyola del Vallès 08193, Barcelona, Spain
| | - David Canadell
- Institut de Biotecnologia i Biomedicina, Universitat Autònoma de Barcelona, Cerdanyola del Vallès 08193, Barcelona, Spain
- Departament de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, Cerdanyola del Vallès 08193, Barcelona, Spain
| | - Alicia Roque
- Departament de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, Cerdanyola del Vallès 08193, Barcelona, Spain
| | - Albert Serra-Cardona
- Institut de Biotecnologia i Biomedicina, Universitat Autònoma de Barcelona, Cerdanyola del Vallès 08193, Barcelona, Spain
- Departament de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, Cerdanyola del Vallès 08193, Barcelona, Spain
| | - M. Carmen Marqués
- Instituto de Biología Molecular y Celular de Plantas (IBMCP), Universitat Politècnica de València-Consejo Superior de Investigaciones Científicas, Valencia, 46022, Spain
| | - Ester Vilaprinyó
- IRB Lleida, Universitat de Lleida, Lleida 25198, Spain
- Universitat de Lleida, Lleida 25198, Spain
| | - Rui Alves
- IRB Lleida, Universitat de Lleida, Lleida 25198, Spain
- Universitat de Lleida, Lleida 25198, Spain
| | - Lynne Yenush
- Instituto de Biología Molecular y Celular de Plantas (IBMCP), Universitat Politècnica de València-Consejo Superior de Investigaciones Científicas, Valencia, 46022, Spain
| | - Joaquín Ariño
- Institut de Biotecnologia i Biomedicina, Universitat Autònoma de Barcelona, Cerdanyola del Vallès 08193, Barcelona, Spain
- Departament de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, Cerdanyola del Vallès 08193, Barcelona, Spain
| |
Collapse
|
12
|
Chen L, Zou G, Wang J, Wang J, Liu R, Jiang Y, Zhao G, Zhou Z. Characterization of the Ca2+-responsive signaling pathway in regulating the expression and secretion of cellulases inTrichoderma reeseiRut-C30. Mol Microbiol 2016; 100:560-75. [DOI: 10.1111/mmi.13334] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/21/2016] [Indexed: 11/28/2022]
Affiliation(s)
- Ling Chen
- Key Laboratory of Synthetic Biology; Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences; Shanghai 200032 China
| | - Gen Zou
- Key Laboratory of Synthetic Biology; Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences; Shanghai 200032 China
| | - Jingzhi Wang
- Key Laboratory of Synthetic Biology; Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences; Shanghai 200032 China
| | - Jin Wang
- Key Laboratory of Synthetic Biology; Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences; Shanghai 200032 China
| | - Rui Liu
- Key Laboratory of Synthetic Biology; Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences; Shanghai 200032 China
| | - Yanping Jiang
- Key Laboratory of Synthetic Biology; Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences; Shanghai 200032 China
| | - Guoping Zhao
- Key Laboratory of Synthetic Biology; Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences; Shanghai 200032 China
| | - Zhihua Zhou
- Key Laboratory of Synthetic Biology; Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences; Shanghai 200032 China
| |
Collapse
|
13
|
Abstract
Calcium is an essential cation for a cell. This cation participates in the regulation of numerous processes in either prokaryotes or eukaryotes, from bacteria to humans. Saccharomyces cerevisiae has served as a model organism to understand calcium homeostasis and calcium-dependent signaling in fungi. In this chapter it will be reviewed known and predicted transport mechanisms that mediate calcium homeostasis in the yeast. How and when calcium enters the cell, how and where it is stored, when is reutilized, and finally secreted to the environment to close the cycle. As a second messenger, maintenance of a controlled free intracellular calcium concentration is important for mediating transcriptional regulation. Many environmental stimuli modify the concentration of cytoplasmic free calcium generating the "calcium signal". This is sensed and transduced through the calmodulin/calcineurin pathway to a transcription factor, named calcineurin-responsive zinc finger, CRZ, also known as "crazy", to mediate transcriptional regulation of a large number of genes of diverse pathways including a negative feedback regulation of the calcium homeostasis system.
Collapse
Affiliation(s)
- Eduardo A Espeso
- Department of Cellular and Molecular Biology, Centro de Investigaciones Biológicas, CSIC, Ramiro de Maeztu, 9, 28040, Madrid, Spain.
| |
Collapse
|
14
|
Cisneros-Barroso E, Yance-Chávez T, Kito A, Sugiura R, Gómez-Hierro A, Giménez-Zaragoza D, Aligue R. Negative feedback regulation of calcineurin-dependent Prz1 transcription factor by the CaMKK-CaMK1 axis in fission yeast. Nucleic Acids Res 2014; 42:9573-87. [PMID: 25081204 PMCID: PMC4150787 DOI: 10.1093/nar/gku684] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Calcium signals trigger the translocation of the Prz1 transcription factor from the cytoplasm to the nucleus. The process is regulated by the calcium-activated phosphatase calcineurin, which activates Prz1 thereby maintaining active transcription during calcium signalling. When calcium signalling ceases, Prz1 is inactivated by phosphorylation and exported to the cytoplasm. In budding yeast and mammalian cells, different kinases have been reported to counter calcineurin activity and regulate nuclear export. Here, we show that the Ca(2+)/calmodulin-dependent kinase Cmk1 is first phosphorylated and activated by the newly identified kinase CaMKK2 homologue, Ckk2, in response to Ca(2+). Then, active Cmk1 binds, phosphorylates and inactivates Prz1 transcription activity whilst at the same time cmk1 expression is enhanced by Prz1 in response to Ca(2+). Furthermore, Cdc25 phosphatase is also phosphorylated by Cmk1, inducing cell cycle arrest in response to an increase in Ca(2+). Moreover, cmk1 deletion shows a high tolerance to chronic exposure to Ca(2+), due to the lack of cell cycle inhibition and elevated Prz1 activity. This work reveals that Cmk1 kinase activated by the newly identified Ckk2 counteracts calcineurin function by negatively regulating Prz1 activity which in turn is involved in activating cmk1 gene transcription. These results are the first insights into Cmk1 and Ckk2 function in Schizosaccharomyces pombe.
Collapse
Affiliation(s)
- Eugenia Cisneros-Barroso
- Departament de Biologia Cellular, Immunologia i Neurociències, Facultat de Medicina, Universitat de Barcelona, Institute of Biomedical Research August Pi i Sunyer (IDIBAPS), Barcelona 08036, Catalunya, Spain
| | - Tula Yance-Chávez
- Departament de Biologia Cellular, Immunologia i Neurociències, Facultat de Medicina, Universitat de Barcelona, Institute of Biomedical Research August Pi i Sunyer (IDIBAPS), Barcelona 08036, Catalunya, Spain
| | - Ayako Kito
- Laboratory of Molecular Pharmacogenomics, School of Pharmaceutical Sciences, Kinki University, Kowakae, Higashi-Osaka 577-8502, Japan
| | - Reiko Sugiura
- Laboratory of Molecular Pharmacogenomics, School of Pharmaceutical Sciences, Kinki University, Kowakae, Higashi-Osaka 577-8502, Japan
| | - Alba Gómez-Hierro
- Departament de Biologia Cellular, Immunologia i Neurociències, Facultat de Medicina, Universitat de Barcelona, Institute of Biomedical Research August Pi i Sunyer (IDIBAPS), Barcelona 08036, Catalunya, Spain
| | - David Giménez-Zaragoza
- Departament de Biologia Cellular, Immunologia i Neurociències, Facultat de Medicina, Universitat de Barcelona, Institute of Biomedical Research August Pi i Sunyer (IDIBAPS), Barcelona 08036, Catalunya, Spain
| | - Rosa Aligue
- Departament de Biologia Cellular, Immunologia i Neurociències, Facultat de Medicina, Universitat de Barcelona, Institute of Biomedical Research August Pi i Sunyer (IDIBAPS), Barcelona 08036, Catalunya, Spain
| |
Collapse
|
15
|
Abstract
Calcium ions are ubiquitous intracellular messengers. An increase in the cytosolic Ca(2+) concentration activates many proteins, including calmodulin and the Ca(2+)/calmodulin-dependent protein phosphatase calcineurin. The phosphatase is conserved from yeast to humans (except in plants), and many target proteins of calcineurin have been identified. The most prominent and best-investigated targets, however, are the transcription factors NFAT (nuclear factor of activated T cells) in mammals and Crz1 (calcineurin-responsive zinc finger 1) in yeast. In recent years, many orthologues of Crz1 have been identified and characterized in various species of fungi, amoebae, and other lower eukaryotes. It has been shown that the functions of calcineurin-Crz1 signaling, ranging from ion homeostasis through cell wall biogenesis to the building of filamentous structures, are conserved in the different organisms. Furthermore, frequency-modulated gene expression through Crz1 has been discovered as a striking new mechanism by which cells can coordinate their response to a signal. In this review, I focus on the latest findings concerning calcineurin-Crz1 signaling in fungi, amoebae and other lower eukaryotes. I discuss the potential of Crz1 and its orthologues as putative drug targets, and I also discuss possible parallels with calcineurin-NFAT signaling in mammals.
Collapse
|
16
|
Genetic bypass of Aspergillus nidulans crzA function in calcium homeostasis. G3-GENES GENOMES GENETICS 2013; 3:1129-41. [PMID: 23665873 PMCID: PMC3704241 DOI: 10.1534/g3.113.005983] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
After dephosphorylation by the phosphatase calcineurin, the fungal transcription factor CrzA enters the nucleus and activates the transcription of genes responsible for calcium homeostasis and many other calcium-regulated activities. A lack of CrzA confers calcium-sensitivity to the filamentous fungus Aspergillus nidulans. To further understand calcium signaling in filamentous fungi and to identify genes that interact genetically with CrzA, we selected for mutations that were able to suppress crzAΔ calcium intolerance and identified three genes. Through genetic mapping, gene sequencing, and mutant rescue, we were able to identify these as cnaB (encoding the calcineurin regulatory subunit), folA (encoding an enzyme involved in folic acid biosynthesis, dihydroneopterin aldolase), and scrC (suppression of crzA-, encoding a hypothetical protein). By using a calcium indicator, Fluo-3, we were able to determine that the wild-type and the suppressor strains were either able to regulate intracellular calcium levels or were able to take up and or store calcium correctly. The increased expression of calcium transporters, pmcA and/or pmcB, in suppressor mutants possibly enabled tolerance to high levels of calcium. Our results suggest that a cnaB suppressor mutation confers calcium tolerance to crzAΔ strains through restoration of calcium homeostasis. These results stress that in A. nidulans there are calcineurin-dependent and CrzA-independent pathways. In addition, it is possible that CrzA is able to contribute to the modulation of folic acid biosynthesis.
Collapse
|
17
|
Hernández-Ortiz P, Espeso EA. Phospho-regulation and nucleocytoplasmic trafficking of CrzA in response to calcium and alkaline-pH stress in Aspergillus nidulans. Mol Microbiol 2013; 89:532-51. [PMID: 23772954 DOI: 10.1111/mmi.12294] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/11/2013] [Indexed: 12/20/2022]
Abstract
Tolerance to abiotic stresses by microorganisms require of appropriate signalling and regulatory pathways. Calcineurin phosphatases mediate calcium-dependent signalling pathways which are widely distributed among phylogeny. In Saccharomyces cerevisiae, calcineurin mediates the post-translational modification of downstream effectors, most of them transcription factors, being the best-characterized calcineurin-regulated zinc-finger factor 1, Crz1p. Here we study the signalling process of CrzA, a filamentous fungal Crz orthologue, in response to calcium and ambient-pH alkalinization. In Aspergillus nidulans resting cells CrzA locates in the cytoplasm being excluded from nuclei. CrzA is a phospho-protein and upon calcium, manganese or alkaline-pH stresses, accumulates in nuclei in a calcineurin-dependent manner. Functional analysis of CrzA defined the presence of a nuclear-export and two nuclear-localization signals as well as a PSINVE sequence that constitutes the major calcineurin-docking domain. First 450 amino acids of CrzA contain these functional motifs and in this region is where phosphorylated residues locate. Different phosphorylation steps are identified in CrzA and activities of casein kinase 1 homologue, CkiA, and of glycogen synthase kinase-3β, identified for the first time here as GskA, are involved. The phospho-signalling process and nucleocytoplasmic trafficking of CrzA shows similarities to those described in yeast for Crz1p homologues and of NFATs in mammals.
Collapse
Affiliation(s)
- Patricia Hernández-Ortiz
- Department of Cellular and Molecular Biology, Centro Investigaciones Biológicas, CSIC, Ramiro de Maeztu, 9, Madrid, 28040, Spain
| | | |
Collapse
|
18
|
Severe osmotic compression triggers a slowdown of intracellular signaling, which can be explained by molecular crowding. Proc Natl Acad Sci U S A 2013; 110:5725-30. [PMID: 23493557 DOI: 10.1073/pnas.1215367110] [Citation(s) in RCA: 128] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Regulation of the cellular volume is fundamental for cell survival and function. Deviations from equilibrium trigger dedicated signaling and transcriptional responses that mediate water homeostasis and volume recovery. Cells are densely packed with proteins, and molecular crowding may play an important role in cellular processes. Indeed, increasing molecular crowding has been shown to modify the kinetics of biochemical reactions in vitro; however, the effects of molecular crowding in living cells are mostly unexplored. Here, we report that, in yeast, a sudden reduction in cellular volume, induced by severe osmotic stress, slows down the dynamics of several signaling cascades, including the stress-response pathways required for osmotic adaptation. We show that increasing osmotic compression decreases protein mobility and can eventually lead to a dramatic stalling of several unrelated signaling and cellular processes. The rate of these cellular processes decreased exponentially with protein density when approaching stalling osmotic compression. This suggests that, under compression, the cytoplasm behaves as a soft colloid undergoing a glass transition. Our results shed light on the physical mechanisms that force cells to cope with volume fluctuations to maintain an optimal protein density compatible with cellular functions.
Collapse
|
19
|
Bodvard K, Jörhov A, Blomberg A, Molin M, Käll M. The yeast transcription factor Crz1 is activated by light in a Ca2+/calcineurin-dependent and PKA-independent manner. PLoS One 2013; 8:e53404. [PMID: 23335962 PMCID: PMC3546054 DOI: 10.1371/journal.pone.0053404] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2012] [Accepted: 11/28/2012] [Indexed: 11/19/2022] Open
Abstract
Light in the visible range can be stressful to non-photosynthetic organisms. The yeast Saccharomyces cerevisiae has earlier been reported to respond to blue light via activation of the stress-regulated transcription factor Msn2p. Environmental changes also induce activation of calcineurin, a Ca(2+)/calmodulin dependent phosphatase, which in turn controls gene transcription by dephosphorylating the transcription factor Crz1p. We investigated the connection between cellular stress caused by blue light and Ca(2+) signalling in yeast by monitoring the nuclear localization dynamics of Crz1p, Msn2p and Msn4p. The three proteins exhibit distinctly different stress responses in relation to light exposure. Msn2p, and to a lesser degree Msn4p, oscillate rapidly between the nucleus and the cytoplasm in an apparently stochastic fashion. Crz1p, in contrast, displays a rapid and permanent nuclear localization induced by illumination, which triggers Crz1p-dependent transcription of its target gene CMK2. Moreover, increased extracellular Ca(2+) levels stimulates the light-induced responses of all three transcription factors, e.g. Crz1p localizes much quicker to the nucleus and a larger fraction of cells exhibits permanent Msn2p nuclear localization at higher Ca(2+) concentration. Studies in mutants lacking Ca(2+) transporters indicate that influx of extracellular Ca(2+) is crucial for the initial stages of light-induced Crz1p nuclear localization, while mobilization of intracellular Ca(2+) stores appears necessary for a sustained response. Importantly, we found that Crz1p nuclear localization is dependent on calcineurin and the carrier protein Nmd5p, while not being affected by increased protein kinase A activity (PKA), which strongly inhibits light-induced nuclear localization of Msn2/4p. We conclude that the two central signalling pathways, cAMP-PKA-Msn2/4 and Ca(2+)-calcineurin-Crz1, are both activated by blue light illumination.
Collapse
Affiliation(s)
- Kristofer Bodvard
- Department of Applied Physics, Chalmers University of Technology, Göteborg, Sweden.
| | | | | | | | | |
Collapse
|
20
|
Finn EM, DeRoo EP, Clement GW, Rao S, Kruse SE, Kokanovich KM, Belanger KD. A subset of FG-nucleoporins is necessary for efficient Msn5-mediated nuclear protein export. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2013; 1833:1096-103. [PMID: 23295456 DOI: 10.1016/j.bbamcr.2012.12.020] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2012] [Revised: 12/21/2012] [Accepted: 12/26/2012] [Indexed: 12/27/2022]
Abstract
The transport of proteins between the cytoplasm and nucleus requires interactions between soluble transport receptors (karyopherins) and phenylalanine-glycine (FG) repeat domains on nuclear pore complex proteins (nucleoporins). However, the role of specific FG repeat-containing nucleoporins in nuclear protein export has not been carefully investigated. We have developed a novel kinetic assay to investigate the relative export kinetics mediated by the karyopherin Msn5/Kap142 in yeast containing specific FG-Nup mutations. Using the Msn5 substrate Crz1 as a marker for Msn5-mediated protein export, we observe that deletions of NUP100 or NUP2 result in decreased rates of Crz1 export, while nup60Δ and nup42Δ mutants do not vary significantly from wild type. The decreased Msn5 export rate in nup100Δ was confirmed using Mig1-GFP as a transport substrate. A nup100ΔGLFG mutant shows defects in nuclear export kinetics similar to a nup100Δ deletion. Removal of FG-repeats from Nsp1 also decreases export kinetics, while a loss of Nup1 FXFGs does not. To confirm that our export data reflected functional differences in protein localization, we performed Crz1 transcription activation assays using a CDRE::LacZ reporter gene that is upregulated upon increased transcription activation by Crz1 in vivo. We observe that expression from this reporter increases in nup100ΔGLFG and nsp1ΔFGΔFXFG strains that exhibit decreased Crz1 export kinetics but resembles wild-type levels in nup1ΔFXFG strains that do not exhibit export defects. These data provide evidence that the export of Msn5 is likely mediated by a specific subset of FG-Nups and that the GLFG repeat domain of Nup100 is important for Msn5-mediated nuclear protein export.
Collapse
Affiliation(s)
- Erin M Finn
- Department of Biological Sciences, Colgate University, Hamilton, NY 13346, USA.
| | | | | | | | | | | | | |
Collapse
|
21
|
Peláez R, Fernández-García P, Herrero P, Moreno F. Nuclear import of the yeast hexokinase 2 protein requires α/β-importin-dependent pathway. J Biol Chem 2011; 287:3518-29. [PMID: 22157003 DOI: 10.1074/jbc.m111.317230] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Hexokinase 2 (Hxk2) from Saccharomyces cerevisiae was one of the first metabolic enzymes described as a multifunctional protein. Hxk2 has a double subcellular localization and role, it functions as a glycolytic enzyme in the cytoplasm and as a regulator of gene transcription of several Mig1-regulated genes in the nucleus. However, the mechanism by which Hxk2 enters in the nucleus was unknown until now. Here, we report that the Hxk2 protein is an import substrate of the carriers α-importin (Kap60 in yeast) and β-importin (Kap95 in yeast). We also show that the Hxk2 nuclear import and the binding of Hxk2 with Kap60 are glucose-dependent and involve one lysine-rich nuclear localization sequence (NLS), located between lysine 6 and lysine 12. Moreover, Kap95 facilitates the recognition of the Hxk2 NLS1 motif by Kap60 and both importins are essential for Hxk2 nuclear import. It is also demonstrated that Hxk2 nuclear import and its binding to Kap95 and Kap60 depend on the Gsp1-GTP/GDP protein levels. Thus, our study uncovers Hxk2 as a new cargo for the α/β-importin pathway of S. cerevisiae.
Collapse
Affiliation(s)
- Rafael Peláez
- Department of Biochemistry and Molecular Biology, University of Oviedo, 33006 Oviedo, Spain
| | | | | | | |
Collapse
|
22
|
Margassery LM, Kennedy J, O'Gara F, Dobson AD, Morrissey JP. A high-throughput screen to identify novel calcineurin inhibitors. J Microbiol Methods 2011; 88:63-6. [PMID: 22056231 DOI: 10.1016/j.mimet.2011.10.012] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2011] [Revised: 10/19/2011] [Accepted: 10/19/2011] [Indexed: 01/26/2023]
Abstract
Calcineurin is a eukaryotic protein phosphatase important for many signalling and developmental processes in cells. Inhibitors of this enzyme are used clinically and there is interest in identifying novel inhibitors for therapeutic applications. This report describes a high-throughput assay that can be used to screen natural or chemical libraries of compounds to identify new calcineurin inhibitors. The microtitre plate assay is based on a yeast reporter strain and was validated with known inhibitors and tested in a pilot screen of bacterial extracts.
Collapse
Affiliation(s)
- Lekha Menon Margassery
- Marine Biotechnology Centre, Environmental Research Institute, Microbiology Department, University College Cork, Ireland
| | | | | | | | | |
Collapse
|
23
|
Markina-Iñarrairaegui A, Etxebeste O, Herrero-García E, Araújo-Bazán L, Fernández-Martínez J, Flores JA, Osmani SA, Espeso EA. Nuclear transporters in a multinucleated organism: functional and localization analyses in Aspergillus nidulans. Mol Biol Cell 2011; 22:3874-86. [PMID: 21880896 PMCID: PMC3192866 DOI: 10.1091/mbc.e11-03-0262] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Nuclear transporters mediate bidirectional macromolecule traffic through the nuclear pore complex (NPC), thus participating in vital processes of eukaryotic cells. A systematic functional analysis in Aspergillus nidulans permitted the identification of 4 essential nuclear transport pathways of a hypothetical number of 14. The absence of phenotypes for most deletants indicates redundant roles for these nuclear receptors. Subcellular distribution studies of these carriers show three main distributions: nuclear, nucleocytoplasmic, and in association with the nuclear envelope. These locations are not specific to predicted roles as exportins or importins but indicate that bidirectional transport may occur coordinately in all nuclei of a syncytium. Coinciding with mitotic NPC rearrangements, transporters dynamically modified their localizations, suggesting supplementary roles to nucleocytoplasmic transport specifically during mitosis. Loss of transportin-SR and Mex/TAP from the nuclear envelope indicates absence of RNA transport during the partially open mitosis of Aspergillus, whereas nucleolar accumulation of Kap121 and Kap123 homologues suggests a role in nucleolar disassembly. This work provides new insight into the roles of nuclear transporters and opens an avenue for future studies of the molecular mechanisms of transport among nuclei within a common cytoplasm, using A. nidulans as a model organism.
Collapse
Affiliation(s)
- Ane Markina-Iñarrairaegui
- Department of Cellular and Molecular Medicine, Centro de Investigaciones Biológicas, National Research Council, 28040 Madrid, Spain
| | | | | | | | | | | | | | | |
Collapse
|
24
|
Cunningham KW. Acidic calcium stores of Saccharomyces cerevisiae. Cell Calcium 2011; 50:129-38. [PMID: 21377728 DOI: 10.1016/j.ceca.2011.01.010] [Citation(s) in RCA: 95] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2010] [Revised: 01/25/2011] [Accepted: 01/31/2011] [Indexed: 02/06/2023]
Abstract
Fungi and animals constitute sister kingdoms in the eukaryotic domain of life. The major classes of transporters, channels, sensors, and effectors that move and respond to calcium ions were already highly networked in the common ancestor of fungi and animals. Since that time, some key components of the network have been moved, altered, relocalized, lost, or duplicated in the fungal and animal lineages and at the same time some of the regulatory circuitry has been dramatically rewired. Today the calcium transport and signaling networks in fungi provide a fresh perspective on the scene that has emerged from studies of the network in animal cells. This review provides an overview of calcium signaling networks in fungi, particularly the model yeast Saccharomyces cerevisiae, with special attention to the dominant roles of acidic calcium stores in fungal cell physiology.
Collapse
Affiliation(s)
- Kyle W Cunningham
- Department of Biology, Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218, USA.
| |
Collapse
|
25
|
Chook YM, Süel KE. Nuclear import by karyopherin-βs: recognition and inhibition. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2010; 1813:1593-606. [PMID: 21029754 DOI: 10.1016/j.bbamcr.2010.10.014] [Citation(s) in RCA: 300] [Impact Index Per Article: 21.4] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 07/15/2010] [Revised: 10/06/2010] [Accepted: 10/19/2010] [Indexed: 01/24/2023]
Abstract
Proteins in the karyopherin-β family mediate the majority of macromolecular transport between the nucleus and the cytoplasm. Eleven of the 19 known human karyopherin-βs and 10 of the 14S. cerevisiae karyopherin-βs mediate nuclear import through recognition of nuclear localization signals or NLSs in their cargos. This receptor-mediated process is essential to cellular viability as proteins are translated in the cytoplasm but many have functional roles in the nucleus. Many known karyopherin-β-cargo interactions were discovered through studies of the individual cargos rather than the karyopherins, and this information is thus widely scattered in the literature. We consolidate information about cargos that are directly recognized by import-karyopherin-βs and review common characteristics or lack thereof among cargos of different import pathways. Knowledge of karyopherin-β-cargo interactions is also critical for the development of nuclear import inhibitors and the understanding of their mechanisms of inhibition. This article is part of a Special Issue entitled: Regulation of Signaling and Cellular Fate through Modulation of Nuclear Protein Import.
Collapse
Affiliation(s)
- Yuh Min Chook
- Department of Pharmacology, University of Texas Southerwestern Medical Center, Dallas, TX 75206, USA.
| | | |
Collapse
|
26
|
Life in the midst of scarcity: adaptations to nutrient availability in Saccharomyces cerevisiae. Curr Genet 2010; 56:1-32. [PMID: 20054690 DOI: 10.1007/s00294-009-0287-1] [Citation(s) in RCA: 163] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2009] [Revised: 12/18/2009] [Accepted: 12/19/2009] [Indexed: 12/27/2022]
Abstract
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 (G0) 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.
Collapse
|
27
|
Lai TP, Stauffer KA, Murthi A, Shaheen HH, Peng G, Martin NC, Hopper AK. Mechanism and a peptide motif for targeting peripheral proteins to the yeast inner nuclear membrane. Traffic 2009; 10:1243-56. [PMID: 19602197 DOI: 10.1111/j.1600-0854.2009.00956.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Trm1 is a tRNA specific m(2)(2)G methyltransferase shared by nuclei and mitochondria in Saccharomyces cerevisiae. In nuclei, Trm1 is peripherally associated with the inner nuclear membrane (INM). We investigated the mechanism delivering/tethering Trm1 to the INM. Analyses of mutations of the Ran pathway and nuclear pore components showed that Trm1 accesses the nucleoplasm via the classical nuclear import pathway. We identified a Trm1 cis-acting sequence sufficient to target passenger proteins to the INM. Detailed mutagenesis of this region uncovered specific amino acids necessary for authentic Trm1 to locate at the INM. The INM information is contained within a sequence of less than 20 amino acids, defining the first motif for addressing a peripheral protein to this important subnuclear location. The combined studies provide a multi-step process to direct Trm1 to the INM: (i) translation in the cytoplasm; (ii) Ran-dependent import into the nucleoplasm; and (iii) redistribution from the nucleoplasm to the INM via the INM motif. Furthermore, we demonstrate that the Trm1 mitochondrial targeting and nuclear localization signals are in competition with each other, as Trm1 becomes mitochondrial if prevented from entering the nucleus.
Collapse
Affiliation(s)
- Tsung-Po Lai
- Department of Molecular Genetics, The Ohio State University, Columbus, OH 43210, USA
| | | | | | | | | | | | | |
Collapse
|
28
|
Reytor E, Pérez-Miguelsanz J, Alvarez L, Pérez-Sala D, Pajares MA. Conformational signals in the C-terminal domain of methionine adenosyltransferase I/III determine its nucleocytoplasmic distribution. FASEB J 2009; 23:3347-60. [PMID: 19497982 DOI: 10.1096/fj.09-130187] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The methyl donor S-adenosylmethionine is synthesized in mammalian cytosol by three isoenzymes. Methionine adenosyltransferase II is ubiquitously expressed, whereas isoenzymes I (homotetramer) and III (homodimer) are considered the hepatic enzymes. In this work, we identified methionine adenosyltransferase I/III in most rat tissues, both in the cytoplasm and the nucleus. Nuclear localization was the preferred distribution observed in extrahepatic tissues, where the protein colocalizes with nuclear matrix markers. A battery of mutants used in several cell lines to decipher the determinants involved in methionine adenosyltransferase subcellular localization demonstrated, by confocal microscopy and subcellular fractionation, the presence of two partially overlapping areas at the C-terminal end of the protein involved both in cytoplasmic retention and nuclear localization. Immunoprecipitation of coexpressed FLAG and EGFP fusions and gel-filtration chromatography allowed detection of tetramers and monomers in nuclear fractions that also exhibited S-adenosylmethionine synthesis. Neither nuclear localization nor matrix binding required activity, as demonstrated with the inactive F251D mutant. Nuclear accumulation of the active enzyme only correlated with histone H3K27 trimethylation among the epigenetic modifications evaluated, therefore pointing to the necessity of methionine adenosyltransferase I/III to guarantee the supply of S-adenosylmethionine for specific methylations. However, nuclear monomers may exhibit additional roles.
Collapse
Affiliation(s)
- Edel Reytor
- Instituto de Investigaciones Biomédicas Alberto Sols (CSIC-UAM), Arturo Duperier 4, 28029 Madrid, Spain
| | | | | | | | | |
Collapse
|
29
|
Two zinc finger transcription factors, CrzA and SltA, are involved in cation homoeostasis and detoxification in Aspergillus nidulans. Biochem J 2008; 414:419-29. [PMID: 18471095 DOI: 10.1042/bj20080344] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
To investigate cation adaptation and homoeostasis in Aspergillus nidulans, two transcription-factor-encoding genes have been characterized. The A. nidulans orthologue crzA of the Saccharomyces cerevisiae CRZ1 gene, encoding a transcription factor mediating gene regulation by Ca(2+), has been identified and deleted. The crzA deletion phenotype includes extreme sensitivity to alkaline pH, Ca(2+) toxicity and aberrant morphology connected with alterations of cell-wall-related phenotypes such as reduced expression of a chitin synthase gene, chsB. A fully functional C-terminally GFP (green fluorescent protein)-tagged form of the CrzA protein is apparently excluded from nuclei in the absence of added Ca(2+), but rapidly accumulates in nuclei upon exposure to Ca(2+). In addition, the previously identified sltA gene, which has no identifiable homologues in yeasts, was deleted, and the resulting phenotype includes considerably enhanced toxicity by a number of cations other than Ca(2+) and also by alkaline pH. Reduced expression of a homologue of the S. cerevisiae P-type ATPase Na(+) pump gene ENA1 might partly explain the cation sensitivity of sltA-null strains. Up-regulation of the homologue of the S. cerevisiae vacuolar Ca(2+)/H(+) exchanger gene VCX1 might explain the lack of Ca(2+) toxicity to null-sltA mutants, whereas down-regulation of this gene might be responsible for Ca(2+) toxicity to crzA-null mutants. Both crzA and sltA encode DNA-binding proteins, and the latter exerts both positive and negative gene regulation.
Collapse
|
30
|
Geda P, Patury S, Ma J, Bharucha N, Dobry CJ, Lawson SK, Gestwicki JE, Kumar A. A small molecule-directed approach to control protein localization and function. Yeast 2008; 25:577-94. [DOI: 10.1002/yea.1610] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
|
31
|
Cramer RA, Perfect BZ, Pinchai N, Park S, Perlin DS, Asfaw YG, Heitman J, Perfect JR, Steinbach WJ. Calcineurin target CrzA regulates conidial germination, hyphal growth, and pathogenesis of Aspergillus fumigatus. EUKARYOTIC CELL 2008; 7:1085-97. [PMID: 18456861 PMCID: PMC2446674 DOI: 10.1128/ec.00086-08] [Citation(s) in RCA: 135] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2008] [Accepted: 04/17/2008] [Indexed: 11/20/2022]
Abstract
The calcineurin pathway is a critical signal transduction pathway in fungi that mediates growth, morphology, stress responses, and pathogenicity. The importance of the calcineurin pathway in fungal physiology creates an opportunity for the development of new antifungal therapies that target this critical signaling pathway. In this study, we examined the role of the zinc finger transcription factor Crz1 homolog (CrzA) in the physiology and pathogenicity of the opportunistic human fungal pathogen Aspergillus fumigatus. Genetic replacement of the crzA locus in A. fumigatus resulted in a strain with significant defects in conidial germination, polarized hyphal growth, cell wall structure, and asexual development that are similar to but with differences from defects seen in the A. fumigatus DeltacnaA (calcineurin A) strain. Like the DeltacnaA strain, the DeltacrzA strain was incapable of causing disease in an experimental persistently neutropenic inhalational murine model of invasive pulmonary aspergillosis. Our results suggest that CrzA is an important downstream effector of calcineurin that controls morphology in A. fumigatus, but additional downstream effectors that mediate calcineurin signal transduction are likely present in this opportunistic fungal pathogen. In addition, the importance of CrzA to the production of disease is critical, and thus CrzA is an attractive fungus-specific antifungal target for the treatment of invasive aspergillosis.
Collapse
Affiliation(s)
- Robert A Cramer
- Duke University Medical Center, Box 3499, Pediatric Infectious Diseases, Durham, NC 27710, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
32
|
Calcineurin-responsive zinc finger transcription factor CRZ1 of Botrytis cinerea is required for growth, development, and full virulence on bean plants. EUKARYOTIC CELL 2008; 7:584-601. [PMID: 18263765 DOI: 10.1128/ec.00426-07] [Citation(s) in RCA: 111] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Recently, we showed that the alpha subunit BCG1 of a heterotrimeric G protein is an upstream activator of the Ca(2+)/calmodulin-dependent phosphatase calcineurin in the gray mold fungus Botrytis cinerea. To identify the transcription factor acting downstream of BCG1 and calcineurin, we cloned the gene encoding the B. cinerea homologue of CRZ1 ("CRaZy," calcineurin-responsive zinc finger transcription factor), the mediator of calcineurin function in yeast. BcCRZ1 is able to partially complement the corresponding Saccharomyces cerevisiae mutant, and the subcellular localization of the green fluorescent protein-BcCRZ1 fusion product in yeast cells depends on the calcium level and calcineurin activity. Bccrz1 deletion mutants are not able to grow on minimal media and grow slowly on media containing plant extracts. Hyphal morphology, conidiation, and sclerotium formation are impaired. The cell wall and membrane integrity, stress response (extreme pH, H(2)O(2), Ca(2+), Li(+)), and ability of the hyphae to penetrate the intact plant surface are affected in the mutants. However, BcCRZ1 is almost dispensable for the conidium-derived infection of bean plants. The addition of Mg(2+) restores the growth rate, conidiation, and penetration and improves the cell wall integrity but has no impact on sclerotium formation or hypersensitivity to Ca(2+) and H(2)O(2). The expression of a set of recently identified BCG1- and calcineurin-dependent genes is also affected in DeltaBccrz1 mutants, confirming that this transcription factor acts downstream of calcineurin in B. cinerea. Since the Bccrz1 mutants still respond to calcineurin inhibitors, we conclude that BcCRZ1 is not the only target of calcineurin.
Collapse
|
33
|
Steinbach WJ, Reedy JL, Cramer RA, Perfect JR, Heitman J. Harnessing calcineurin as a novel anti-infective agent against invasive fungal infections. Nat Rev Microbiol 2007; 5:418-30. [PMID: 17505522 DOI: 10.1038/nrmicro1680] [Citation(s) in RCA: 247] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The number of immunocompromised patients with invasive fungal infections continues to increase and new antifungal therapies are not keeping pace with the growing incidence of these infections and their associated mortality. Calcineurin inhibition is currently used to exert effective immunosuppression following organ transplantation and in treating various other conditions. However, the calcineurin pathway is also intricately involved in the growth and pathogenesis of the three major fungal pathogens of humans, Cryptococcus neoformans, Candida albicans and Aspergillus fumigatus, and the exploitation of fungal calcineurin pathways holds great promise for the future development of novel antifungal agents. This Review summarizes our current understanding of calcineurin biology in these fungal species, and its exciting potential role in treating invasive fungal infections.
Collapse
Affiliation(s)
- William J Steinbach
- Division of Pediatric Infectious Diseases, Department of Pediatrics, Duke University Medical Center, Durham, North Carolina 27710, USA.
| | | | | | | | | |
Collapse
|
34
|
Roy J, Li H, Hogan PG, Cyert MS. A conserved docking site modulates substrate affinity for calcineurin, signaling output, and in vivo function. Mol Cell 2007; 25:889-901. [PMID: 17386265 PMCID: PMC2913616 DOI: 10.1016/j.molcel.2007.02.014] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2006] [Revised: 01/19/2007] [Accepted: 02/16/2007] [Indexed: 01/07/2023]
Abstract
Calcineurin, the conserved Ca(2+)/calmodulin-regulated protein phosphatase, mediates diverse aspects of Ca(2+)-dependent signaling. We show that substrates bind calcineurin with varying strengths and examine the impact of this affinity on signaling. We altered the calcineurin-docking site, or PxIxIT motif, in Crz1, the calcineurin-regulated transcription factor in S. cerevisiae, to decrease (Crz1(PVIAVN)) or increase (Crz1(PVIVIT)) its affinity for calcineurin. As a result, the Ca(2+)-dependent dephosphorylation and activation of Crz1(PVIAVN) are decreased, whereas Crz1(PVIVIT) is constitutively dephosphorylated and hyperactive. Surprisingly, the physiological consequences of altering calcineurin-Crz1 affinity depend on the growth conditions. Crz1(PVIVIT) improves yeast growth under several environmental stress conditions but causes a growth defect during alkaline stress, most likely by titrating calcineurin away from other substrates or regulators. Thus, calcineurin-substrate affinity determines the Ca(2+) concentration dependence and output of signaling in vivo as well as the balance between different branches of calcineurin signaling in an overall biological response.
Collapse
Affiliation(s)
- Jagoree Roy
- Department of Biological Sciences, Stanford University, 371 Serra Mall, Stanford, CA 94305, USA
| | - Huiming Li
- CBR Institute for Biomedical Research, Harvard Medical School, 200 Longwood Avenue, Boston, MA 02115, USA
- Department of Pathology, Harvard Medical School, 200 Longwood Avenue, Boston, MA 02115, USA
| | - Patrick G. Hogan
- CBR Institute for Biomedical Research, Harvard Medical School, 200 Longwood Avenue, Boston, MA 02115, USA
| | - Martha S. Cyert
- Department of Biological Sciences, Stanford University, 371 Serra Mall, Stanford, CA 94305, USA
- Correspondence:
| |
Collapse
|
35
|
Wiesenberger G, Steinleitner K, Malli R, Graier WF, Vormann J, Schweyen RJ, Stadler JA. Mg2+ deprivation elicits rapid Ca2+ uptake and activates Ca2+/calcineurin signaling in Saccharomyces cerevisiae. EUKARYOTIC CELL 2007; 6:592-9. [PMID: 17337637 PMCID: PMC1865649 DOI: 10.1128/ec.00382-06] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
To learn about the cellular processes involved in Mg(2+) homeostasis and the mechanisms allowing cells to cope with low Mg(2+) availability, we performed RNA expression-profiling experiments and followed changes in gene activity upon Mg(2+) depletion on a genome-wide scale. A striking portion of genes up-regulated under Mg(2+) depletion are also induced by high Ca(2+) and/or alkalinization. Among the genes significantly up-regulated by Mg(2+) starvation, Ca(2+) stress, and alkalinization are ENA1 (encoding a P-type ATPase sodium pump) and PHO89 (encoding a sodium/phosphate cotransporter). We show that up-regulation of these genes is dependent on the calcineurin/Crz1p (calcineurin-responsive zinc finger protein) signaling pathway. Similarly to Ca(2+) stress, Mg(2+) starvation induces translocation of the transcription factor Crz1p from the cytoplasm into the nucleus. The up-regulation of ENA1 and PHO89 upon Mg(2+) starvation depends on extracellular Ca(2+). Using fluorescence resonance energy transfer microscopy, we demonstrate that removal of Mg(2+) results in an immediate increase in free cytoplasmic Ca(2+). This effect is dependent on external Ca(2+). The results presented indicate that Mg(2+) depletion in yeast cells leads to enhanced cellular Ca(2+) concentrations, which activate the Crz1p/calcineurin pathway. We provide evidence that calcineurin/Crz1p signaling is crucial for yeast cells to cope with Mg(2+) depletion stress.
Collapse
Affiliation(s)
- Gerlinde Wiesenberger
- Max F. Perutz Laboratories, Department of Genetics, University of Vienna, Vienna, Austria
| | | | | | | | | | | | | |
Collapse
|
36
|
Caesar S, Greiner M, Schlenstedt G. Kap120 functions as a nuclear import receptor for ribosome assembly factor Rpf1 in yeast. Mol Cell Biol 2006; 26:3170-80. [PMID: 16581791 PMCID: PMC1446960 DOI: 10.1128/mcb.26.8.3170-3180.2006] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The nucleocytoplasmic exchange of macromolecules is mediated by receptors specialized in passage through the nuclear pore complex. The majority of these receptors belong to the importin beta protein family, which has 14 members in Saccharomyces cerevisiae. Nine importins carry various cargos from the cytoplasm into the nucleus, whereas four exportins mediate nuclear export. Kap120 is the only receptor whose transport cargo has not been found previously. Here, we characterize Kap120 as an importin for the ribosome maturation factor Rpf1, which was identified in a two-hybrid screen. Kap120 binds directly to Rpf1 in vitro and is released by Ran-GTP. At least three parallel import pathways exist for Rpf1, since nuclear import is defective in strains with the importins Kap120, Kap114, and Nmd5 deleted. Both kap120 and rpf1 mutants accumulate large ribosomal subunits in the nucleus. The nuclear accumulation of 60S ribosomal subunits in kap120 mutants is abolished upon RPF1 overexpression, indicating that Kap120 does not function in the actual ribosomal export step but rather in import of ribosome maturation factors.
Collapse
Affiliation(s)
- Stefanie Caesar
- Medizinische Biochemie und Molekularbiologie, Universität des Saarlandes, D-66421 Homburg, Germany
| | | | | |
Collapse
|
37
|
Sopko R, Huang D, Preston N, Chua G, Papp B, Kafadar K, Snyder M, Oliver SG, Cyert M, Hughes TR, Boone C, Andrews B. Mapping pathways and phenotypes by systematic gene overexpression. Mol Cell 2006; 21:319-30. [PMID: 16455487 DOI: 10.1016/j.molcel.2005.12.011] [Citation(s) in RCA: 493] [Impact Index Per Article: 27.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2005] [Revised: 11/24/2005] [Accepted: 12/07/2005] [Indexed: 11/23/2022]
Abstract
Many disease states result from gene overexpression, often in a specific genetic context. To explore gene overexpression phenotypes systematically, we assembled an array of 5280 yeast strains, each containing an inducible copy of an S. cerevisiae gene, covering >80% of the genome. Approximately 15% of the overexpressed genes (769) reduced growth rate. This gene set was enriched for cell cycle-regulated genes, signaling molecules, and transcription factors. Overexpression of most toxic genes resulted in phenotypes different from known deletion mutant phenotypes, suggesting that overexpression phenotypes usually reflect a specific regulatory imbalance rather than disruption of protein complex stoichiometry. Global overexpression effects were also assayed in the context of a cyclin-dependent kinase mutant (pho85Delta). The resultant gene set was enriched for Pho85p targets and identified the yeast calcineurin-responsive transcription factor Crz1p as a substrate. Large-scale application of this approach should provide a strategy for identifying target molecules regulated by specific signaling pathways.
Collapse
Affiliation(s)
- Richelle Sopko
- Department of Medical Genetics and Microbiology, University of Toronto, 1 King's College Circle, Toronto, Ontario M5S 1A8, Canada
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
38
|
Karababa M, Valentino E, Pardini G, Coste AT, Bille J, Sanglard D. CRZ1, a target of the calcineurin pathway inCandida albicans. Mol Microbiol 2006; 59:1429-51. [PMID: 16468987 DOI: 10.1111/j.1365-2958.2005.05037.x] [Citation(s) in RCA: 177] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Calcineurin is a major player in calcium-dependent signal transduction pathways of eukaryotes. Calcineurin acts on transcription factors (e.g. CRZ1 in Saccharomyces cerevisiae) and governs the expression of genes in a species-dependent fashion. In Candida albicans, the calcineurin pathway is involved in tolerance to antifungal agents, cation homeostasis and virulence. However, the components of the calcineurin pathway are still poorly investigated in this yeast species. Taking S. cerevisiae as a model to reconstitute this pathway, two CRZ1-like genes, CRZ1 and CRZ2 (for calcineurin-responsive zinc finger 1 and 2 genes), were found with C(2)H(2) zinc finger domains. Only CRZ1 was able to restore the calcium hypersusceptibility of a S. cerevisiae crz1Delta mutant and to mediate calcium-dependent gene expression in this yeast species. Several experiments showed that CRZ1 was dependent on calcineurin in C. albicans: (i) phenotypic analysis of a crz1Delta/Delta mutant showed impaired growth as compared with the wild type in the presence of cations (Ca(2+), Mn(2+)) as does a mutant lacking calcineurin subunit A (cnaDelta/Delta) and (ii) a green fluorescent protein (GFP)-Crz1p fusion protein showed a calcium- and calcineurin-dependent nuclear localization. To further analyse the relationship between calcineurin and CRZ1, a comprehensive analysis of calcineurin/Crz1p-dependent gene expression following addition of Ca(2+) (200 mM) was performed. Among the expression of 264 genes altered by at least twofold, the upregulation of 60 genes was dependent on both calcineurin and CRZ1. Interestingly, a motif [5'-G(C/T)GGT-3'] with similarity to the target sequence of Crz1p (GNGGCG/TCA) from S. cerevisiae was identified as a putative regulatory sequence in the upstream regions of these calcineurin/Crz1p-dependent genes. However, additional experiments showed that calcineurin may have other targets in addition to CRZ1. First, CRZ1 was not involved in tolerance to antifungal agents (fluconazole, terbinafine) on the opposite to calcineurin. Second, CRZ1 was only moderately influencing virulence in a mice model of infection which is in sharp contrast to the strong avirulence of cnaDelta/Delta mutant in the same animal model. Even though this work establishes CRZ1 as a calcineurin target, further studies are needed to identify other calcineurin-dependent elements in C. albicans.
Collapse
Affiliation(s)
- Mahir Karababa
- Institute of Microbiology, University Hospital Lausanne, CH-1011 Lausanne, Switzerland
| | | | | | | | | | | |
Collapse
|
39
|
Santos M, de Larrinoa IF. Functional characterization of the Candida albicans CRZ1 gene encoding a calcineurin-regulated transcription factor. Curr Genet 2005; 48:88-100. [PMID: 16044281 DOI: 10.1007/s00294-005-0003-8] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2005] [Revised: 05/25/2005] [Accepted: 06/03/2005] [Indexed: 01/26/2023]
Abstract
Calcineurin is a phosphoprotein phosphatase devoted to the transduction of Ca(2+)-signals in eukaryotes. In the human pathogen Candida albicans, calcineurin function is required for cell morphogenesis, azole tolerance, membrane stress responses, survival in serum and virulence in mice. Molecular mechanisms as well as targets downstream C. albicans calcineurin involved in all these processes are still uncharacterized. Here we report the characterization of a C. albicans Crz1 calcineurin-regulated transcription factor using a Saccharomyces cerevisiae crz1Delta defective strain as heterologous host. CaCrz1p fulfils the function of its S. cerevisiae homolog protein to control the expression of several Ca(2+)/calcineurin-responsive genes acting on the CDRE sequence in promoters. In the model yeast, CaCrz1p activity and localization are regulated by calcineurin. Deletion of CRZ1 gene renders C. albicans hypersensitive to alkaline cations and membrane stress conditions, including that elicited by SDS and antifungal azoles. Our findings indicate that CaCrz1p is member of a calcium-regulated pathway required for the maintenance of membrane integrity.
Collapse
Affiliation(s)
- Mikel Santos
- Departamento de Química Aplicada, Facultad de Ciencias Químicas, Universidad del País Vasco (UPV/EHU), 20018 San Sebastián, Spain
| | | |
Collapse
|
40
|
Denis V, Cyert MS. Molecular analysis reveals localization of Saccharomyces cerevisiae protein kinase C to sites of polarized growth and Pkc1p targeting to the nucleus and mitotic spindle. EUKARYOTIC CELL 2005; 4:36-45. [PMID: 15643058 PMCID: PMC544167 DOI: 10.1128/ec.4.1.36-45.2005] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The catalytic activity and intracellular localization of protein kinase C (PKC) are both highly regulated in vivo. This family of kinases contains conserved regulatory motifs, i.e., the C1, C2, and HR1 domains, which target PKC isoforms to specific subcellular compartments and restrict their activity spatially. Saccharomyces cerevisiae contains a single PKC isozyme, Pkc1p, which contains all of the regulatory motifs found in mammalian PKCs. Pkc1p localizes to sites of polarized growth, consistent with its main function in maintaining cell integrity. We dissected the molecular basis of Pkc1p localization by expressing each of its domains individually and in combinations as green fluorescent protein fusions. We find that the Rho1p-binding domains, HR1 and C1, are responsible for targeting Pkc1p to the bud tip and cell periphery, respectively. We demonstrate that Pkc1p activity is required for its normal localization to the bud neck, which also depends on the integrity of the septin ring. In addition, we show for the first time that yeast protein kinase C can accumulate in the nucleus, and we identify a nuclear exit signal as well as nuclear localization signals within the Pkc1p sequence. Thus, we propose that Pkc1p shuttles in and out of the nucleus and consequently has access to nuclear substrates. Surprisingly, we find that deletion of the HR1 domain results in Pkc1p localization to the mitotic spindle and that the C2 domain is responsible for this targeting. This novel nuclear and spindle localization of Pkc1p may provide a molecular explanation for previous observations that suggest a role for Pkc1p in regulating microtubule function.
Collapse
Affiliation(s)
- Valérie Denis
- Department of Biological Sciences, Stanford University, Stanford, California 94305-5020, USA
| | | |
Collapse
|
41
|
Kafadar KA, Cyert MS. Integration of stress responses: modulation of calcineurin signaling in Saccharomyces cerevisiae by protein kinase A. EUKARYOTIC CELL 2005; 3:1147-53. [PMID: 15470242 PMCID: PMC522609 DOI: 10.1128/ec.3.5.1147-1153.2004] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Calcineurin is a Ca2+/calmodulin-dependent protein phosphatase required for Saccharomyces cerevisiae to adapt to a variety of environmental stresses. Once activated, calcineurin dephosphorylates the Zn-finger transcription factor Crz1p/Tcn1p, causing it to accumulate in the nucleus where it activates gene expression. Here we show that cyclic AMP-dependent protein kinase A (PKA) phosphorylates and negatively regulates Crz1p activity by inhibiting its nuclear import. Activation of PKA in vivo decreases Crz1p-dependent transcription. PKA phosphorylates Crz1p in vitro, and we identify specific residues required for this phosphorylation, all of which reside in or adjacent to the nuclear localization signal. Mutation of these residues to alanine results in increased nuclear import of Crz1p and results in higher levels of both basal and Ca2+-induced Crz1p transcriptional activity. PKA regulates the general stress response in yeast and coordinates this response with nutrient availability. In contrast, calcineurin regulates the cellular response to a restricted set of environmental insults. Thus, these studies identify a specific biochemical mechanism through which the activities of multiple stress-activated signaling pathways are integrated in vivo.
Collapse
Affiliation(s)
- Kimberly A Kafadar
- Department of Biological Sciences, Stanford University, 337 Campus Dr., Lokey Building, Stanford, CA 94305-5020, USA
| | | |
Collapse
|
42
|
Le Gallic L, Virgilio L, Cohen P, Biteau B, Mavrothalassitis G. ERF nuclear shuttling, a continuous monitor of Erk activity that links it to cell cycle progression. Mol Cell Biol 2004; 24:1206-18. [PMID: 14729966 PMCID: PMC321421 DOI: 10.1128/mcb.24.3.1206-1218.2004] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The ets domain transcriptional repressor ERF is an effector of the receptor tyrosine kinase/Ras/Erk pathway, which, it has been suggested, is regulated by subcellular localization as a result of Erk-dependent phosphorylation and is capable of suppressing cell proliferation and ras-induced tumorigenicity. Here, we analyze the effect of ERF phosphorylation on nuclear import and export, the timing of its phosphorylation and dephosphorylation in relation to its subcellular location, Erk activity, and the requirements for ERF-induced cell cycle arrest. Our findings indicate that ERF continuously shuttles between the nucleus and the cytoplasm and that both phosphorylation and dephosphorylation of ERF occur within the nucleus. While nuclear import is not affected by phosphorylation, ERF nuclear export and cytoplasmic release require multisite phosphorylation and dephosphorylation. ERF export is CRM1 dependent, although ERF does not have a detectable nuclear export signal. ERF phosphorylation and export correlate with the levels of nuclear Erk activity. The cell cycle arrest induced by nonphosphorylated ERF requires the wild-type retinoblastoma protein and can be suppressed by overexpression of cyclin. These data suggest that ERF may be a very sensitive and constant sensor of Erk activity that can affect cell cycle progression through G(1), providing another link between the Ras/Erk pathway and cellular proliferation.
Collapse
|
43
|
Cyert MS. Calcineurin signaling in Saccharomyces cerevisiae: how yeast go crazy in response to stress. Biochem Biophys Res Commun 2004; 311:1143-50. [PMID: 14623300 DOI: 10.1016/s0006-291x(03)01552-3] [Citation(s) in RCA: 273] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
In the yeast Saccharomyces cerevisiae, Ca(2+) signaling mediated by the Ca(2+)/calmodulin dependent phosphatase, calcineurin, is required for survival during environmental stress. One role of the phosphatase under these conditions is to activate gene expression through its regulation of the Crz1p ("crazy") transcription factor. Calcineurin dephosphorylates Crz1p and causes its rapid translocation from the cytosol to the nucleus. Crz1p then activates the transcription of genes whose products promote cell survival. Recent studies concerning the regulation of Crz1p by calcineurin are discussed in this review and the mechanisms by which calcineurin controls gene expression in yeast and mammalian cells are compared.
Collapse
Affiliation(s)
- Martha S Cyert
- Department of Biological Sciences, Stanford University, Stanford, CA 94306, USA.
| |
Collapse
|
44
|
Greiner M, Caesar S, Schlenstedt G. The histones H2A/H2B and H3/H4 are imported into the yeast nucleus by different mechanisms. Eur J Cell Biol 2004; 83:511-20. [PMID: 15679097 DOI: 10.1078/0171-9335-00418] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Proteins are imported from the cytoplasm into the nucleus by importin beta-related transport receptors. The yeast Saccharomyces cerevisiae contains ten of these importins, but only two of them are essential. After transfer through the nuclear pore, importins release their cargo upon binding to the Ran GTPase, the key regulator of nuclear transport. We investigated the import of the core histones in yeast and found that four importins are involved. The essential Pse1p and the nonessential importins Kap114p, Kap104p, and Yrb4p/Kap123p specifically bind to histones H2A and H2B. Release of H2 histones from importins requires Ran-GTP and DNA simultaneously suggesting a function of the importins in intranuclear targeting. H3 and H4 associate mainly with Pse1p and the dissociation requires Ran but not DNA, which points to a different import mechanism. Import of green fluorescent protein fusions to H2A and H2B requires primarily Pse1p and Kap114p, whereas Yrb4p plays an auxiliary role. Pse1p is predominantly necessary for nuclear uptake of H3 and H4, while Kap104p and Yrb4p also support import. We conclude from our in vivo and in vitro experiments that import of the essential histones is mediated mainly by the essential importin Pse1p, while the non-essential Kap114p functions in a parallel import pathway for H2A and H2B.
Collapse
Affiliation(s)
- Markus Greiner
- Medizinische Biochemie und Molekularbiologie, Universität des Saarlandes, Homburg, Germany
| | | | | |
Collapse
|
45
|
Kafadar KA, Zhu H, Snyder M, Cyert MS. Negative regulation of calcineurin signaling by Hrr25p, a yeast homolog of casein kinase I. Genes Dev 2003; 17:2698-708. [PMID: 14597664 PMCID: PMC280619 DOI: 10.1101/gad.1140603] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Calcineurin is a Ca2+/calmodulin-regulated protein phosphatase required for Saccharomyces cerevisiae to respond to a variety of environmental stresses. Calcineurin promotes cell survival during stress by dephosphorylating and activating the Zn-finger transcription factor Crz1p/Tcn1p. Using a high-throughput assay, we screened 119 yeast kinases for their ability to phosphorylate Crz1p in vitro and identified the casein kinase I homolog Hrr25p. Here we show that Hrr25p negatively regulates Crz1p activity and nuclear localization in vivo. Hrr25p binds to and phosphorylates Crz1p in vitro and in vivo. Overexpression of Hrr25p decreases Crz1p-dependent transcription and antagonizes its Ca2+-induced nuclear accumulation. In the absence of Hrr25p, activation of Crz1p by Ca2+/calcineurin is potentiated. These findings represent the first identification of a negative regulator for Crz1p, and establish a novel physiological role for Hrr25p in antagonizing calcineurin signaling.
Collapse
Affiliation(s)
- Kimberly A Kafadar
- Department of Biological Sciences Stanford University, Stanford, California, 94305-5020, USA
| | | | | | | |
Collapse
|
46
|
Sanglard D, Ischer F, Marchetti O, Entenza J, Bille J. Calcineurin A of Candida albicans: involvement in antifungal tolerance, cell morphogenesis and virulence. Mol Microbiol 2003; 48:959-76. [PMID: 12753189 DOI: 10.1046/j.1365-2958.2003.03495.x] [Citation(s) in RCA: 274] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The azole antifungal fluconazole possesses only fungistatic activity in Candida albicans and, therefore, this human pathogen is tolerant to this agent. However, tolerance to fluconazole can be inhibited when C. albicans is exposed to fluconazole combined with the immunosuppressive drug cyclosporin A, which is known to inhibit calcineurin activity in yeast. A mutant lacking both alleles of a gene encoding the calcineurin A subunit (CNA) lost viability in the presence of fluconazole, thus making calcineurin essential for fluconazole tolerance. Consistent with this observation, tolerance to fluconazole was modulated by calcium ions or by the expression of a calcineurin A derivative autoactivated by the removal of its C-terminal inhibitory domain. Interestingly, CNA was also essential for tolerance to other antifungal agents (voriconazole, itraconazole, terbinafine, amorolfine) and to several other metabolic inhibitors (caffeine, brefeldin A, mycophenolic acid, fluphenazine) or cell wall-perturbing agents (SDS, calcofluor white, Congo red), thus indicating that the calcineurin pathway plays an important role in the survival of C. albicans in the presence of external growth inhibitors. Several genes, including PMC1, a vacuolar calcium P-type ATPase, were regulated in a calcineurin- and fluconazole-dependent manner. However, PMC1 did not play a direct role in the survival of C. albicans when exposed to fluconazole. In addition to these different properties, calcineurin was found to affect colony morphology in several media known to modulate the C. albicans dimorphic switch. In particular, calcineurin was found to be essential for C. albicans viability in serum-containing media. Finally, calcineurin was found to be necessary for the virulence of C. albicans in a mice model of infection, thus making calcineurin an important element for adequate adaptation to the conditions of the host environment.
Collapse
Affiliation(s)
- Dominique Sanglard
- Institute of Microbiology, Centre Hospitalier Universitaire Vaudois (CHUV), Rue du Bugnon 44, CH-1011 Lausanne, Switzerland.
| | | | | | | | | |
Collapse
|
47
|
Abstract
Calcineurin is a Ca(2+)/calmodulin-activated protein phosphatase that is conserved in eukaryotes, from yeast to humans, and is the conserved target of the immunosuppressive drugs cyclosporin A (CsA) and FK506. Genetic studies in yeast and fungi established the molecular basis of calcineurin inhibition by the cyclophilin A-CsA and FKBP12-FK506 complexes. Calcineurin also functions in fungi to control a myriad of physiological processes including cell cycle progression, cation homeostasis, and morphogenesis. Recent investigations into the molecular mechanisms of pathogenesis in Candida albicans and Cryptococcus neoformans, two fungi that cause life-threatening infections in humans, have revealed an essential role for calcineurin in morphogenesis, virulence, and antifungal drug action. Novel non-immunosuppressive analogs of the calcineurin inhibitors CsA and FK506 that retain antifungal activity have been identified and hold promise as candidate antifungal drugs. In addition, comparisons of calcineurin function in both fungi and humans may identify fungal-specific components of calcineurin-signaling pathways that could be targeted for therapy, as well as conserved elements of calcium signaling events.
Collapse
Affiliation(s)
- Deborah S Fox
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC 27710, USA
| | | |
Collapse
|
48
|
Yoshimoto H, Saltsman K, Gasch AP, Li HX, Ogawa N, Botstein D, Brown PO, Cyert MS. Genome-wide analysis of gene expression regulated by the calcineurin/Crz1p signaling pathway in Saccharomyces cerevisiae. J Biol Chem 2002; 277:31079-88. [PMID: 12058033 DOI: 10.1074/jbc.m202718200] [Citation(s) in RCA: 319] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In Saccharomyces cerevisiae, the Ca(2+)/calmodulin-dependent protein phosphatase, calcineurin, is activated by specific environmental conditions, including exposure to Ca(2+) and Na(+), and induces gene expression by regulating the Crz1p/Tcn1p transcription factor. We used DNA microarrays to perform a comprehensive analysis of calcineurin/Crz1p-dependent gene expression following addition of Ca(2+) (200 mm) or Na(+) (0.8 m) to yeast. 163 genes exhibited increased expression that was reduced 50% or more by calcineurin inhibition. These calcineurin-dependent genes function in signaling pathways, ion/small molecule transport, cell wall maintenance, and vesicular transport, and include many open reading frames of previously unknown function. Three distinct gene classes were defined as follows: 28 genes displayed calcineurin-dependent induction in response to Ca(2+) and Na(+), 125 showed calcineurin-dependent expression following Ca(2+) but not Na(+) addition, and 10 were regulated by calcineurin in response to Na(+) but not Ca(2+). Analysis of crz1Delta cells established Crz1p as the major effector of calcineurin-regulated gene expression in yeast. We identified the Crz1p-binding site as 5'-GNGGC(G/T)CA-3' by in vitro site selection. A similar sequence, 5'-GAGGCTG-3', was identified as a common sequence motif in the upstream regions of calcineurin/ Crz1p-dependent genes. This finding is consistent with direct regulation of these genes by Crz1p.
Collapse
Affiliation(s)
- Hiroyuki Yoshimoto
- Department of Biological Sciences, Stanford University, 371 Serra Mall, Stanford, CA 94305-5020, USA
| | | | | | | | | | | | | | | |
Collapse
|
49
|
Betz C, Zajonc D, Moll M, Schweizer E. ISC1-encoded inositol phosphosphingolipid phospholipase C is involved in Na+/Li+ halotolerance of Saccharomyces cerevisiae. EUROPEAN JOURNAL OF BIOCHEMISTRY 2002; 269:4033-9. [PMID: 12180980 DOI: 10.1046/j.1432-1033.2002.03096.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In Saccharomyces cerevisiae, toxic concentrations of Na+ orLi+ ions induce the expression of the cation-extrusion ATPase gene, ENA1. Several well-studied signal transduction pathways are known correlating high salinity to the transcriptional activation of ENA1. Nevertheless, information on the actual sensing mechanism initiating these pathways is limited. Here, we report that the ISC1-encoded phosphosphingolipid-specific phospholipase C appears to be involved in stimulation of ENA1 expression and, consequently, in mediating Na+ and Li+ tolerance in yeast. Deletion of ISC1 distinctly decreased cellular Na+ and Li+ tolerance as growth of the Deltaisc1::HIS5 mutant, DZY1, was severely impaired by 0.5 m NaCl or 0.01 m LiCl. In contrast,K+ tolerance and general osmostress regulation wereunaffected. Isc1Delta mutant growth with 0.9 m KCl and glycerol accumulation in the presence of 0.9 m NaCl or 1.5 m sorbitol were comparable to that of the wild-type. ENA1-lacZ reporter studies suggested that the increased salt sensitivity of the isc1Delta mutant is related to a significant reduction of Na+/Li+-stimulated ENA1 expression. Correspondingly, Ena1p-dependent extrusion of Na+/Li+ ions was less efficient in the isc1Delta mutant than in wild-type cells. Itis suggested that ISC1-dependent hydrolysis of an unidentified yeast inositol phosphosphingolipid represents an early event in one of the salt-induced signalling pathways of ENA1 transcriptional activation.
Collapse
Affiliation(s)
- Christian Betz
- Lehrstuhl für Biochemie and the Lehrstuhl für Anorganische und Allgemeine Chemie, Universität Erlangen-Nürnberg, Erlangen, Germany
| | | | | | | |
Collapse
|
50
|
Boustany LM, Cyert MS. Calcineurin-dependent regulation of Crz1p nuclear export requires Msn5p and a conserved calcineurin docking site. Genes Dev 2002; 16:608-19. [PMID: 11877380 PMCID: PMC155349 DOI: 10.1101/gad.967602] [Citation(s) in RCA: 105] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Calcineurin, a conserved Ca(2+)/calmodulin-regulated protein phosphatase, plays a crucial role in Ca(2+) signaling in a wide variety of cell types. In Saccharomyces cerevisiae, calcineurin positively regulates transcription in response to stress by dephosphorylating the transcription factor Crz1p/Tcn1p. Dephosphorylation promotes Crz1p nuclear localization in part by increasing the efficiency of its nuclear import. In this work, we show that calcineurin-dependent dephosphorylation of Crz1p also down-regulates its nuclear export. Using a genetic approach, we identify Msn5p as the exportin for Crz1p. In addition, we define the Crz1p nuclear export signal (NES) and show that it interacts with Msn5p in a phosphorylation-dependent manner. This indicates that calcineurin regulates Crz1p nuclear export by dephosphorylating and inactivating its NES. Finally, we define a motif in Crz1p, PIISIQ, similar to the PxIxIT docking site for calcineurin on the mammalian transcription factor NFAT, that mediates the in vivo interaction between calcineurin and Crz1p and is required for calcineurin-dependent regulation of Crz1p nuclear export and activity. Therefore, in yeast as in mammals, a docking site is required to target calcineurin to its substrate such that it can dephosphorylate it efficiently.
Collapse
Affiliation(s)
- Leila M Boustany
- Department of Biological Sciences, Stanford University, Stanford, California 94305-5020, USA
| | | |
Collapse
|