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Wu C, Chen H, Yuan M, Zhang M, Abubakar YS, Chen X, Zhong H, Zheng W, Zheng H, Zhou J. FgAP1 σ Is Critical for Vegetative Growth, Conidiation, Virulence, and DON Biosynthesis in Fusarium graminearum. J Fungi (Basel) 2023; 9:jof9020145. [PMID: 36836259 PMCID: PMC9962196 DOI: 10.3390/jof9020145] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2022] [Revised: 01/17/2023] [Accepted: 01/19/2023] [Indexed: 01/24/2023] Open
Abstract
The AP1 complex is a highly conserved clathrin adaptor that plays important roles in regulating cargo protein sorting and intracellular vesicle trafficking in eukaryotes. However, the functions of the AP1 complex in the plant pathogenic fungi including the devastating wheat pathogen Fusarium graminearum are still unclear. In this study, we investigated the biological functions of FgAP1σ, a subunit of the AP1 complex in F. graminearum. Disruption of FgAP1σ causes seriously impaired fungal vegetative growth, conidiogenesis, sexual development, pathogenesis, and deoxynivalenol (DON) production. The ΔFgap1σ mutants were found to be less sensitive to KCl- and sorbitol-induced osmotic stresses but more sensitive to SDS-induced stress than the wild-type PH-1. Although the growth inhibition rate of the ΔFgap1σ mutants was not significantly changed under calcofluor white (CFW) and Congo red (CR) stresses, the protoplasts released from ΔFgap1σ hyphae were decreased compared with the wild-type PH-1, suggesting that FgAP1σ is necessary for cell wall integrity and osmotic stresses in F. graminearum. Subcellular localization assays showed that FgAP1σ was predominantly localized to endosomes and the Golgi apparatus. In addition, FgAP1β-GFP, FgAP1γ-GFP, and FgAP1μ-GFP also localize to the Golgi apparatus. FgAP1β interacts with FgAP1σ, FgAP1γ, and FgAP1μ, while FgAP1σ regulates the expression of FgAP1β, FgAP1γ, and FgAP1μ in F. graminearum. Furthermore, the loss of FgAP1σ blocks the transportation of the v-SNARE protein FgSnc1 from the Golgi to the plasma membrane and delays the internalization of FM4-64 dye into the vacuole. Taken together, our results demonstrate that FgAP1σ plays vital roles in vegetative growth, conidiogenesis, sexual reproduction, DON production, pathogenicity, cell wall integrity, osmotic stress, exocytosis, and endocytosis in F. graminearum. These findings unveil the functions of the AP1 complex in filamentous fungi, most notably in F. graminearum, and lay solid foundations for effective prevention and control of Fusarium head blight (FHB).
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Affiliation(s)
- Congxian Wu
- Fujian Universities Key Laboratory for Plant-Microbe Interaction, College of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China
- Public Technology Service Center, Fujian Medical University, Fuzhou 350122, China
| | - Huilin Chen
- Fujian Universities Key Laboratory for Plant-Microbe Interaction, College of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Mingyue Yuan
- Fujian Universities Key Laboratory for Plant-Microbe Interaction, College of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Meiru Zhang
- Fujian Universities Key Laboratory for Plant-Microbe Interaction, College of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Yakubu Saddeeq Abubakar
- Fujian Universities Key Laboratory for Plant-Microbe Interaction, College of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China
- Department of Biochemistry, Faculty of Life Sciences, Ahmadu Bello University, Zaria 810107, Nigeria
| | - Xin Chen
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Haoming Zhong
- Fujian Universities Key Laboratory for Plant-Microbe Interaction, College of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Wenhui Zheng
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Huawei Zheng
- Fujian Universities Key Laboratory for Plant-Microbe Interaction, College of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China
- Institute of Oceanography, College of Geography and Oceanography, Minjiang University, Fuzhou 350108, China
- Correspondence: (H.Z.); (J.Z.)
| | - Jie Zhou
- Fujian Universities Key Laboratory for Plant-Microbe Interaction, College of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China
- Correspondence: (H.Z.); (J.Z.)
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Cell wall integrity is compromised under temperature stress in Schizosaccharomyces pombe expressing a valproic acid-sensitive vas4 mutant. Sci Rep 2021; 11:13483. [PMID: 34188069 PMCID: PMC8242086 DOI: 10.1038/s41598-021-92466-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2020] [Accepted: 06/03/2021] [Indexed: 11/17/2022] Open
Abstract
Valproic acid (VPA) is widely used as a eutherapeutic and safe anticonvulsant drug, but the mechanism is not well elucidated. Histone deacetylases (HDACs) were first identified as direct targets of VPA. Many loss-of function mutants in S. pombe have been shown to be VPA sensitive but not sensitive to other HDAC inhibitors, such as sodium butyrate or trichostatin A (TSA). This difference suggests that there are multiple VPA target genes. In the current study, we isolated a VPA-sensitive (vas) mutant, vas4-1, and cloned the VPA target gene vas4+/vrg4+ by performing complementation experiments. The vas4+/vrg4+ gene encodes a putative Golgi GDP-mannose transporter, Vrg4, which is highly homologous with ScVrg4p. Physiological experiments indicated that SpVrg4p is involved in maintaining cell wall integrity (CWI) under high- or low-temperature stress. The results of a coimmunoprecipitation assay suggested that SpVrg4p may be transferred from the ER to the Golgi through SpGot1p loaded COPII vesicles, and both single and double mutations (S263C and A271V) in SpVrg4p compromised this transfer. Our results suggested that CWI in S. pombe is compromised under temperature stress by the VPA-sensitive vas4 mutant.
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Secretory Vesicle Polar Sorting, Endosome Recycling and Cytoskeleton Organization Require the AP-1 Complex in Aspergillus nidulans. Genetics 2018; 209:1121-1138. [PMID: 29925567 DOI: 10.1534/genetics.118.301240] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2018] [Accepted: 06/19/2018] [Indexed: 11/18/2022] Open
Abstract
The AP-1 complex is essential for membrane protein traffic via its role in the pinching-off and sorting of secretory vesicles (SVs) from the trans-Golgi and/or endosomes. While its essentiality is undisputed in metazoa, its role in simpler eukaryotes seems less clear. Here, we dissect the role of AP-1 in the filamentous fungus Aspergillus nidulans and show that it is absolutely essential for growth due to its role in clathrin-dependent maintenance of polar traffic of specific membrane cargoes toward the apex of growing hyphae. We provide evidence that AP-1 is involved in both anterograde sorting of RabERab11-labeled SVs and RabA/BRab5-dependent endosome recycling. Additionally, AP-1 is shown to be critical for microtubule and septin organization, further rationalizing its essentiality in cells that face the challenge of cytoskeleton-dependent polarized cargo traffic. This work also opens a novel issue on how nonpolar cargoes, such as transporters, are sorted to the eukaryotic plasma membrane.
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More than Just an Immunosuppressant: The Emerging Role of FTY720 as a Novel Inducer of ROS and Apoptosis. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2018; 2018:4397159. [PMID: 29785244 PMCID: PMC5896217 DOI: 10.1155/2018/4397159] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/29/2017] [Accepted: 02/28/2018] [Indexed: 02/03/2023]
Abstract
Fingolimod hydrochloride (FTY720) is a first-in-class of sphingosine-1-phosphate (S1P) receptor modulator approved to treat multiple sclerosis by its phosphorylated form (FTY720-P). Recently, a novel role of FTY720 as a potential anticancer drug has emerged. One of the anticancer mechanisms of FTY720 involves the induction of reactive oxygen species (ROS) and subsequent apoptosis, which is largely independent of its property as an S1P modulator. ROS have been considered as a double-edged sword in tumor initiation/progression. Intriguingly, prooxidant therapies have attracted much attention due to its efficacy in cancer treatment. These strategies include diverse chemotherapeutic agents and molecular targeted drugs such as sulfasalazine which inhibits the CD44v-xCT (cystine transporter) axis. In this review, we introduce our recent discoveries using a chemical genomics approach to uncover a signaling network relevant to FTY720-mediated ROS signaling and apoptosis, thereby proposing new potential targets for combination therapy as a means to enhance the antitumor efficacy of FTY720 as a ROS generator. We extend our knowledge by summarizing various measures targeting the vulnerability of cancer cells' defense mechanisms against oxidative stress. Future directions that may lead to the best use of FTY720 and ROS-targeted strategies as a promising cancer treatment are also discussed.
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Venugopal K, Werkmeister E, Barois N, Saliou JM, Poncet A, Huot L, Sindikubwabo F, Hakimi MA, Langsley G, Lafont F, Marion S. Dual role of the Toxoplasma gondii clathrin adaptor AP1 in the sorting of rhoptry and microneme proteins and in parasite division. PLoS Pathog 2017; 13:e1006331. [PMID: 28430827 PMCID: PMC5415223 DOI: 10.1371/journal.ppat.1006331] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2016] [Revised: 05/03/2017] [Accepted: 04/03/2017] [Indexed: 12/13/2022] Open
Abstract
Toxoplasma gondii possesses a highly polarized secretory system, which efficiently assembles de novo micronemes and rhoptries during parasite replication. These apical secretory organelles release their contents into host cells promoting parasite invasion and survival. Using a CreLox-based inducible knock-out strategy and the ddFKBP over-expression system, we unraveled novel functions of the clathrin adaptor complex TgAP1. First, our data indicate that AP1 in T. gondii likely functions as a conserved heterotetrameric complex composed of the four subunits γ, β, μ1, σ1 and interacts with known regulators of clathrin-mediated vesicular budding such as the unique ENTH-domain containing protein, which we named Epsin-like protein (TgEpsL). Disruption of the μ1 subunit resulted in the mis-sorting of microneme proteins at the level of the Trans-Golgi-Network (TGN). Furthermore, we demonstrated that TgAP1 regulates rhoptry biogenesis by activating rhoptry protein exit from the TGN, but also participates in the post-Golgi maturation process of preROP compartments into apically anchored club-shaped mature organelles. For this latter activity, our data indicate a specific functional relationship between TgAP1 and the Rab5A-positive endosome-like compartment. In addition, we unraveled an original role for TgAP1 in the regulation of parasite division. APμ1-depleted parasites undergo normal daughter cell budding and basal complex assembly but fail to segregate at the end of cytokinesis. The phylum Apicomplexa comprises a large group of obligate intracellular parasites of wide human and agricultural significance. Most notable are Plasmodium, the causative agent of malaria, and Toxoplasma gondii, one of the most common human parasites, responsible for disease of the developing fetus and immune-compromised individuals. Apicomplexa are characterized by the presence of an apical complex consisting of secretory organelles named micronemes (MIC) and rhoptries (ROP). MIC and ROP proteins, released upon host cell recognition, are essential for host cell invasion and parasite survival. After invasion, these organelles are neo-synthesized at each parasite replication cycle. In our study, we demonstrate a crucial role for the T. gondii clathrin adaptor complex AP1 in the vesicular transport of neo-synthesized MIC and ROP proteins, thereby regulating mature apical organelle formation. In addition, we unravel an original role for TgAP1 in the late stages of the parasite division process during daughter cell segregation. Therefore, our study provides new insights into key regulatory mechanisms of the vesicular trafficking system essential for host invasion and intracellular survival of Toxoplasma gondii.
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Affiliation(s)
- Kannan Venugopal
- Centre d'Infection et d'Immunité de Lille, Université de Lille, Inserm U1019, CNRS UMR 8204, CHU Lille, Institut Pasteur de Lille, Lille, France
| | - Elisabeth Werkmeister
- Centre d'Infection et d'Immunité de Lille, Université de Lille, Inserm U1019, CNRS UMR 8204, CHU Lille, Institut Pasteur de Lille, Lille, France
| | - Nicolas Barois
- Centre d'Infection et d'Immunité de Lille, Université de Lille, Inserm U1019, CNRS UMR 8204, CHU Lille, Institut Pasteur de Lille, Lille, France
| | - Jean-Michel Saliou
- Centre d'Infection et d'Immunité de Lille, Université de Lille, Inserm U1019, CNRS UMR 8204, CHU Lille, Institut Pasteur de Lille, Lille, France
| | - Anais Poncet
- Centre d'Infection et d'Immunité de Lille, Université de Lille, Inserm U1019, CNRS UMR 8204, CHU Lille, Institut Pasteur de Lille, Lille, France
| | - Ludovic Huot
- Centre d'Infection et d'Immunité de Lille, Université de Lille, Inserm U1019, CNRS UMR 8204, CHU Lille, Institut Pasteur de Lille, Lille, France
| | - Fabien Sindikubwabo
- IAB, Team Host-pathogen interactions & immunity to infection, Université Grenoble Alpes, Inserm U1209, CNRS UMR5309, Grenoble, France
| | - Mohamed Ali Hakimi
- IAB, Team Host-pathogen interactions & immunity to infection, Université Grenoble Alpes, Inserm U1209, CNRS UMR5309, Grenoble, France
| | - Gordon Langsley
- Laboratoire de Biologie Cellulaire Comparative des Apicomplexes, Faculté de Médicine, Université Paris Descartes-Sorbonne Paris Cité, France. Inserm U1016, CNRS UMR8104, Institut Cochin, Paris, France
| | - Frank Lafont
- Centre d'Infection et d'Immunité de Lille, Université de Lille, Inserm U1019, CNRS UMR 8204, CHU Lille, Institut Pasteur de Lille, Lille, France
| | - Sabrina Marion
- Centre d'Infection et d'Immunité de Lille, Université de Lille, Inserm U1019, CNRS UMR 8204, CHU Lille, Institut Pasteur de Lille, Lille, France
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Hu L, Yao F, Ma Y, Liu Q, Chen S, Hayafuji T, Kuno T, Fang Y. Genetic evidence for involvement of membrane trafficking in the action of 5-fluorouracil. Fungal Genet Biol 2016; 93:17-24. [PMID: 27255861 DOI: 10.1016/j.fgb.2016.05.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2016] [Revised: 05/24/2016] [Accepted: 05/29/2016] [Indexed: 10/21/2022]
Abstract
To identify novel genes that mediate cellular sensitivity and resistance to 5-fluorouracil (5-FU), we performed a genome-wide genetic screening to identify altered susceptibility to 5-FU by Schizosaccharomyces pombe haploid nonessential gene deletion library containing 3004 deletion mutants. We identified 50 hypersensitive and 12 resistant mutants to this drug. Mutants sensitive or resistant to 5-FU were classified into various categories based on their putative functions. The largest group of the genes whose disruption renders cells altered susceptibility to 5-FU is involved in nucleic acid metabolism, but to our surprise, the second largest group is involved in membrane trafficking. In addition, several other membrane traffic mutants examined including gdi1-i11, ypt3-i5, Δryh1, Δric1, and Δaps1 exhibited hypersensitivity to 5-FU. Furthermore, we found that 5-FU in low concentration that generally do not affect cell growth altered the localization of Syb1, a secretory vesicle SNARE synaptobrevin which is cycled between the plasma membrane and the endocytic pathway. Notably, 5-FU at such low concentration also significantly inhibited the secretion of acid phosphatase. Altogether, our findings revealed the first evidence that 5-FU influences membrane trafficking as the potential underlying mechanism of the drug action.
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Affiliation(s)
- Lingling Hu
- Department of Microbial and Biochemical Pharmacy, School of Pharmacy, China Medical University, No. 77 Puhe Road, Shenyang North New Area, Shenyang, Liaoning Province 110112, China; Division of Pharmacology, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki-cho, Chuo-ku, Kobe 650-0017, Japan
| | - Fan Yao
- Department of Breast Surgery and Surgical Oncology, Research Unit of General Surgery, The First Affiliated Hospital of China Medical University, Shenyang, Liaoning Province 110001, China
| | - Yan Ma
- Division of Pharmacology, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki-cho, Chuo-ku, Kobe 650-0017, Japan
| | - Qiannan Liu
- Department of Microbial and Biochemical Pharmacy, School of Pharmacy, China Medical University, No. 77 Puhe Road, Shenyang North New Area, Shenyang, Liaoning Province 110112, China
| | - Si Chen
- Department of Microbial and Biochemical Pharmacy, School of Pharmacy, China Medical University, No. 77 Puhe Road, Shenyang North New Area, Shenyang, Liaoning Province 110112, China
| | - Tsutomu Hayafuji
- Division of Pharmacology, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki-cho, Chuo-ku, Kobe 650-0017, Japan
| | - Takayoshi Kuno
- Department of Microbial and Biochemical Pharmacy, School of Pharmacy, China Medical University, No. 77 Puhe Road, Shenyang North New Area, Shenyang, Liaoning Province 110112, China; Division of Pharmacology, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki-cho, Chuo-ku, Kobe 650-0017, Japan
| | - Yue Fang
- Department of Microbial and Biochemical Pharmacy, School of Pharmacy, China Medical University, No. 77 Puhe Road, Shenyang North New Area, Shenyang, Liaoning Province 110112, China.
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Ma N, Ma Y, Nakashima A, Kikkawa U, Furuyashiki T. The Loss of Lam2 and Npr2-Npr3 Diminishes the Vacuolar Localization of Gtr1-Gtr2 and Disinhibits TORC1 Activity in Fission Yeast. PLoS One 2016; 11:e0156239. [PMID: 27227887 PMCID: PMC4881991 DOI: 10.1371/journal.pone.0156239] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2015] [Accepted: 05/11/2016] [Indexed: 12/13/2022] Open
Abstract
In mammalian cells, mTORC1 activity is regulated by Rag GTPases. It is thought that the Ragulator complex and the GATOR (GAP activity towards Rags) complex regulate RagA/B as its GDP/GTP exchange factor (GEF) and GTPase-activating protein (GAP), respectively. However, the functions of components in these complexes remain elusive. Using fission yeast as a model organism, here we found that the loss of Lam2 (SPBC1778.05c), a homolog of a Ragulator component LAMTOR2, as well as the loss of Gtr1 or Gtr2 phenocopies the loss of Npr2 or Npr3, homologs of GATOR components Nprl2 or Nprl3, respectively. These phenotypes were rescued by TORC1 inhibition using pharmacological or genetic means, and the loss of Lam2, Gtr1, Gtr2, Npr2 or Npr3 disinhibited TORC1 activity under nitrogen depletion, as measured by Rps6 phosphorylation. Consistently, overexpression of GDP-locked Gtr1S20L or GTP-locked Gtr2Q60L, which suppress TORC1 activity in budding yeast, rescued the growth defect of Δgtr1 cells or Δgtr2 cells, respectively, and the loss of Lam2, Npr2 or Npr3 similarly diminished the vacuolar localization and the protein levels of Gtr1 and Gtr2. Furthermore, Lam2 physically interacted with Npr2 and Gtr1. These findings suggest that Lam2 and Npr2-Npr3 function together as a tether for GDP-bound Gtr1 to the vacuolar membrane, thereby suppressing TORC1 activity for multiple cellular functions.
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Affiliation(s)
- Ning Ma
- Division of Pharmacology, Graduate School of Medicine, Kobe University, Kobe, Japan
| | - Yan Ma
- Division of Pharmacology, Graduate School of Medicine, Kobe University, Kobe, Japan
- * E-mail:
| | | | - Ushio Kikkawa
- Biosignal Research Center, Kobe University, Kobe, Japan
| | - Tomoyuki Furuyashiki
- Division of Pharmacology, Graduate School of Medicine, Kobe University, Kobe, Japan
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de León N, Valdivieso MH. The long life of an endocytic patch that misses AP-2. Curr Genet 2016; 62:765-770. [PMID: 27126383 DOI: 10.1007/s00294-016-0605-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2016] [Accepted: 04/15/2016] [Indexed: 10/21/2022]
Abstract
Endocytosis is the process by which cells regulate extracellular fluid uptake and internalize molecules bound to their plasma membrane. This process requires the generation of protein-coated vesicles. In clathrin-mediated endocytosis (CME) the assembly polypeptide 2 (AP-2) adaptor facilitates rapid endocytosis of some plasma membrane receptors by mediating clathrin recruitment to the endocytic site and by connecting cargoes to the clathrin coat. While this adaptor is essential for early embryonic development in mammals, initial results suggested that it is dispensable for endocytosis in unicellular eukaryotes. The drastic effect of depleting AP-2 in metazoa and the mild effect of deleting AP-2 subunits in Saccharomyces cerevisiae have prevented a detailed analysis of the dynamics of endocytic patches in the absence of this adaptor. Using live-cell imaging of Schizosaccharomyces pombe endocytic sites we have shown that eliminating AP-2 perturbs the dynamics of endocytic patches beyond the moment of coat assembly. These perturbations affect the cell growth pattern and cell wall synthesis. Our results highlight the importance of using different model organisms to address the study of conserved aspects of CME.
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Affiliation(s)
- Nagore de León
- Departamento de Microbiología y Genética/Instituto de Biología Funcional y Genómica (IBFG), University of Salamanca/CSIC, Calle Zacarías González 2, 37007, Salamanca, Spain.,Department of Zoology, University of Oxford, South Parks Road, Oxford, OX1 3PS, UK
| | - M-Henar Valdivieso
- Departamento de Microbiología y Genética/Instituto de Biología Funcional y Genómica (IBFG), University of Salamanca/CSIC, Calle Zacarías González 2, 37007, Salamanca, Spain.
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Liu Q, Ma Y, Zhou X, Furuyashiki T. Constitutive Tor2 Activity Promotes Retention of the Amino Acid Transporter Agp3 at Trans-Golgi/Endosomes in Fission Yeast. PLoS One 2015; 10:e0139045. [PMID: 26447710 PMCID: PMC4598100 DOI: 10.1371/journal.pone.0139045] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2015] [Accepted: 09/07/2015] [Indexed: 12/13/2022] Open
Abstract
Amino acid transporters are located at specific subcellular compartments, and their localizations are regulated by the extracellular availability of amino acids. In yeast, target of rapamycin (TOR) activation induces the internalization of amino acid transporters located at the plasma membrane. However, whether and how TOR signaling regulates other amino acid transporters located at intracellular compartments remains unknown. Here, we demonstrate that in the fission yeast, the TOR inhibitor Torin-1 induces the transfer of several yellow fluorescent protein (YFP)-fused intracellular amino acid transporters, including Agp3, Isp5, Aat1, and Put4, from trans-Golgi/endosomes into the vacuoles. By contrast, the localizations of YFP-fused Can1, Fnx1, and Fnx2 transporter proteins were unaffected upon Torin-1 treatment. There are two TOR isoforms in fission yeast, Tor1 and Tor2. Whereas tor1 deletion did not affect the Torin-1-induced transfer of Agp3-YFP, Tor2 inhibition using a temperature-sensitive mutant induced the transfer of Agp3-YFP to the vacuolar lumen, similar to the effects of Torin-1 treatment. Tor2 inhibition also induced the transfer of the YFP-fused Isp5, Aat1, and Put4 transporter proteins to the vacuoles, although only partial transfer of the latter two transporters was observed. Under nitrogen depletion accompanied by reduced Tor2 activity, Agp3-YFP was transferred from the trans-Golgi/endosomes to the plasma membrane and then to the vacuoles, where it was degraded by the vacuolar proteases Isp6 and Psp3. Mutants with constitutively active Tor2 showed delayed transfer of Agp3-YFP to the plasma membrane upon nitrogen depletion. Cells lacking Tsc2, a negative regulator of Tor2, also showed a delay in this process in a Tor2-dependent manner. Taken together, these findings suggest that constitutive Tor2 activity is critical for the retention of amino acid transporters at trans-Golgi/endosomes. Moreover, nitrogen depletion suppresses Tor2 activity through Tsc2, thereby promoting the surface expression of these transporters.
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Affiliation(s)
- Qingbin Liu
- Division of Pharmacology, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Yan Ma
- Division of Pharmacology, Kobe University Graduate School of Medicine, Kobe, Japan
- * E-mail:
| | - Xin Zhou
- Department of Oncology, the First Affiliated Hospital of Liaoning Medical University, Jinzhou, China
| | - Tomoyuki Furuyashiki
- Division of Pharmacology, Kobe University Graduate School of Medicine, Kobe, Japan
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Abstract
The target of rapamycin (TOR) is a highly conserved protein kinase that regulates cell growth and metabolism. Here we performed a genome-wide screen to identify negative regulators of TOR complex 1 (TORC1) in Schizosaccharomyces pombe by isolating mutants that phenocopy Δtsc2, in which TORC1 signaling is known to be up-regulated. We discovered that Δnpr2 displayed similar phenotypes to Δtsc2 in terms of amino acid uptake defects and mislocalization of the Cat1 permease. However, Δnpr2 and Δtsc2 clearly showed different phenotypes in terms of rapamycin supersensitivity and Isp5 transcription upon various treatments. Furthermore, we showed that Tor2 controls amino acid homeostasis at the transcriptional and post-transcriptional levels. Our data reveal that both Npr2 and Tsc2 negatively regulate TORC1 signaling, and Npr2, but not Tsc2, may be involved in the feedback loop of a nutrient-sensing pathway.
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Zhang L, Ma N, Liu Q, Ma Y. Genome-wide screening for genes associated with valproic acid sensitivity in fission yeast. PLoS One 2013; 8:e68738. [PMID: 23861937 PMCID: PMC3702616 DOI: 10.1371/journal.pone.0068738] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2012] [Accepted: 06/03/2013] [Indexed: 11/22/2022] Open
Abstract
We have been studying the action mechanisms of valproic acid (VPA) in fission yeast Schizosaccharomyces pombe by developing a genetic screen for mutants that show hypersensitivity to VPA. In the present study, we performed a genome-wide screen of 3004 haploid deletion strains and confirmed 148 deletion strains to be VPA sensitive. Of the 148 strains, 93 strains also showed sensitivity to another aliphatic acids HDAC inhibitor, sodium butyrate (SB), and 55 strains showed sensitivity to VPA but not to SB. Interestingly, we found that both VPA and SB treatment induced a marked increase in the transcription activity of Atf1 in wild-type cells. However, in clr6-1, a mutant allele the clr6+ gene encoding class I HDAC, neither VPA- nor SB induced the activation of Atf1 transcription activity. We also found that VPA, but not SB, caused an increase in cytoplasmic Ca2+ level. We further found that the cytoplasmic Ca2+ increase was caused by Ca2+ influx from extracellular medium via Cch1-Yam8 channel complex. Altogether, our present study indicates that VPA and SB play similar but distinct roles in multiple physiological processes in fission yeast.
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Affiliation(s)
- Lili Zhang
- Division of Molecular Pharmacology and Pharmacogenomics, Department of Biochemistry and Molecular Biology, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Ning Ma
- Division of Molecular Pharmacology and Pharmacogenomics, Department of Biochemistry and Molecular Biology, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Qingbin Liu
- Division of Molecular Pharmacology and Pharmacogenomics, Department of Biochemistry and Molecular Biology, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Yan Ma
- Division of Molecular Pharmacology and Pharmacogenomics, Department of Biochemistry and Molecular Biology, Kobe University Graduate School of Medicine, Kobe, Japan
- * E-mail:
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Yu Y, Li C, Kita A, Katayama Y, Kubouchi K, Udo M, Imanaka Y, Ueda S, Masuko T, Sugiura R. Sip1, an AP-1 accessory protein in fission yeast, is required for localization of Rho3 GTPase. PLoS One 2013; 8:e68488. [PMID: 23840894 PMCID: PMC3698097 DOI: 10.1371/journal.pone.0068488] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2013] [Accepted: 05/29/2013] [Indexed: 11/18/2022] Open
Abstract
Rho family GTPases act as molecular switches to regulate a range of physiological functions, including the regulation of the actin-based cytoskeleton, membrane trafficking, cell morphology, nuclear gene expression, and cell growth. Rho function is regulated by its ability to bind GTP and by its localization. We previously demonstrated functional and physical interactions between Rho3 and the clathrin-associated adaptor protein-1 (AP-1) complex, which revealed a role of Rho3 in regulating Golgi/endosomal trafficking in fission yeast. Sip1, a conserved AP-1 accessory protein, recruits the AP-1 complex to the Golgi/endosomes through physical interaction. In this study, we showed that Sip1 is required for Rho3 localization. First, overexpression of rho3⁺ suppressed defective membrane trafficking associated with sip1-i4 mutant cells, including defects in vacuolar fusion, Golgi/endosomal trafficking and secretion. Notably, Sip1 interacted with Rho3, and GFP-Rho3, similar to Apm1-GFP, did not properly localize to the Golgi/endosomes in sip1-i4 mutant cells at 27°C. Interestingly, the C-terminal region of Sip1 is required for its localization to the Golgi/endosomes, because Sip1-i4-GFP protein failed to properly localize to Golgi/endosomes, whereas the fluorescence of Sip1ΔN mutant protein co-localized with that of FM4-64. Consistently, in the sip1-i4 mutant cells, which lack the C-terminal region of Sip1, binding between Apm1 and Rho3 was greatly impaired, presumably due to mislocalization of these proteins in the sip1-i4 mutant cells. Furthermore, the interaction between Apm1 and Rho3 as well as Rho3 localization to the Golgi/endosomes were significantly rescued in sip1-i4 mutant cells by the expression of Sip1ΔN. Taken together, these results suggest that Sip1 recruits Rho3 to the Golgi/endosomes through physical interaction and enhances the formation of the Golgi/endosome AP-1/Rho3 complex, thereby promoting crosstalk between AP-1 and Rho3 in the regulation of Golgi/endosomal trafficking in fission yeast.
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Affiliation(s)
- Yang Yu
- Laboratory of Molecular Pharmacogenomics, School of Pharmaceutical Sciences, Kinki University, Kowakae, Higashi-Osaka, Japan
| | - Cuifang Li
- Laboratory of Molecular Pharmacogenomics, School of Pharmaceutical Sciences, Kinki University, Kowakae, Higashi-Osaka, Japan
- Japan Society for the Promotion of Science, Tokyo, Japan
| | - Ayako Kita
- Laboratory of Molecular Pharmacogenomics, School of Pharmaceutical Sciences, Kinki University, Kowakae, Higashi-Osaka, Japan
| | - Yuta Katayama
- Laboratory of Molecular Pharmacogenomics, School of Pharmaceutical Sciences, Kinki University, Kowakae, Higashi-Osaka, Japan
| | - Koji Kubouchi
- Laboratory of Molecular Pharmacogenomics, School of Pharmaceutical Sciences, Kinki University, Kowakae, Higashi-Osaka, Japan
| | - Masako Udo
- Laboratory of Molecular Pharmacogenomics, School of Pharmaceutical Sciences, Kinki University, Kowakae, Higashi-Osaka, Japan
| | - Yukako Imanaka
- Laboratory of Molecular Pharmacogenomics, School of Pharmaceutical Sciences, Kinki University, Kowakae, Higashi-Osaka, Japan
| | - Shiho Ueda
- Laboratory of Molecular Cell Biology, School of Pharmaceutical Sciences, Kinki University, Kowakae, Higashi-Osaka, Japan
| | - Takashi Masuko
- Laboratory of Molecular Cell Biology, School of Pharmaceutical Sciences, Kinki University, Kowakae, Higashi-Osaka, Japan
| | - Reiko Sugiura
- Laboratory of Molecular Pharmacogenomics, School of Pharmaceutical Sciences, Kinki University, Kowakae, Higashi-Osaka, Japan
- * E-mail:
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Mutations in ap1b1 cause mistargeting of the Na(+)/K(+)-ATPase pump in sensory hair cells. PLoS One 2013; 8:e60866. [PMID: 23593334 PMCID: PMC3625210 DOI: 10.1371/journal.pone.0060866] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2013] [Accepted: 03/04/2013] [Indexed: 11/19/2022] Open
Abstract
The hair cells of the inner ear are polarized epithelial cells with a specialized structure at the apical surface, the mechanosensitive hair bundle. Mechanotransduction occurs within the hair bundle, whereas synaptic transmission takes place at the basolateral membrane. The molecular basis of the development and maintenance of the apical and basal compartments in sensory hair cells is poorly understood. Here we describe auditory/vestibular mutants isolated from forward genetic screens in zebrafish with lesions in the adaptor protein 1 beta subunit 1 (ap1b1) gene. Ap1b1 is a subunit of the adaptor complex AP-1, which has been implicated in the targeting of basolateral membrane proteins. In ap1b1 mutants we observed that although the overall development of the inner ear and lateral-line organ appeared normal, the sensory epithelium showed progressive signs of degeneration. Mechanically-evoked calcium transients were reduced in mutant hair cells, indicating that mechanotransduction was also compromised. To gain insight into the cellular and molecular defects in ap1b1 mutants, we examined the localization of basolateral membrane proteins in hair cells. We observed that the Na(+)/K(+)-ATPase pump (NKA) was less abundant in the basolateral membrane and was mislocalized to apical bundles in ap1b1 mutant hair cells. Accordingly, intracellular Na(+) levels were increased in ap1b1 mutant hair cells. Our results suggest that Ap1b1 is essential for maintaining integrity and ion homeostasis in hair cells.
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Eckler AM, Wilder C, Castanon A, Ferris VM, Lamere RA, Perrin BA, Pearlman R, White B, Byrd C, Ludvik N, Nichols N, Poole-Sumrall K, Sztul E, Styers ML. Haploinsufficiency of the Sec7 guanine nucleotide exchange factor gea1 impairs septation in fission yeast. PLoS One 2013; 8:e56807. [PMID: 23457617 PMCID: PMC3574105 DOI: 10.1371/journal.pone.0056807] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2012] [Accepted: 01/15/2013] [Indexed: 11/19/2022] Open
Abstract
Membrane trafficking is essential to eukaryotic life and is controlled by a complex network of proteins that regulate movement of proteins and lipids between organelles. The GBF1/GEA family of Guanine nucleotide Exchange Factors (GEFs) regulates trafficking between the endoplasmic reticulum and Golgi by catalyzing the exchange of GDP for GTP on ADP Ribosylation Factors (Arfs). Activated Arfs recruit coat protein complex 1 (COP-I) to form vesicles that ferry cargo between these organelles. To further explore the function of the GBF1/GEA family, we have characterized a fission yeast mutant lacking one copy of the essential gene gea1 (gea1+/-), the Schizosaccharomyces pombe ortholog of GBF1. The haploinsufficient gea1+/- strain was shown to be sensitive to the GBF1 inhibitor brefeldin A (BFA) and was rescued from BFA sensitivity by gea1p overexpression. No overt defects in localization of arf1p or arf6p were observed in gea1+/- cells, but the fission yeast homolog of the COP-I cargo sac1 was mislocalized, consistent with impaired COP-I trafficking. Although Golgi morphology appeared normal, a slight increase in vacuolar size was observed in the gea1+/- mutant strain. Importantly, gea1+/- cells exhibited dramatic cytokinesis-related defects, including disorganized contractile rings, an increased septation index, and alterations in septum morphology. Septation defects appear to result from altered secretion of enzymes required for septum dynamics, as decreased secretion of eng1p, a β-glucanase required for septum breakdown, was observed in gea1+/- cells, and overexpression of eng1p suppressed the increased septation phenotype. These observations implicate gea1 in regulation of septum breakdown and establish S. pombe as a model system to explore GBF1/GEA function in cytokinesis.
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Affiliation(s)
- Alan M. Eckler
- Department of Biology, Birmingham-Southern College, Birmingham, Alabama, United States of America
| | - Caroline Wilder
- Department of Biology, Birmingham-Southern College, Birmingham, Alabama, United States of America
| | - Antonio Castanon
- Department of Biology, Birmingham-Southern College, Birmingham, Alabama, United States of America
| | - Veronica M. Ferris
- Department of Biology, Birmingham-Southern College, Birmingham, Alabama, United States of America
| | - Rachael A. Lamere
- Department of Biology, Birmingham-Southern College, Birmingham, Alabama, United States of America
| | - Benjamin A. Perrin
- Department of Biology, Birmingham-Southern College, Birmingham, Alabama, United States of America
| | - Ross Pearlman
- Department of Biology, Birmingham-Southern College, Birmingham, Alabama, United States of America
| | - Blaise White
- Department of Biology, Birmingham-Southern College, Birmingham, Alabama, United States of America
| | - Clifton Byrd
- Department of Biology, Birmingham-Southern College, Birmingham, Alabama, United States of America
| | - Nicholas Ludvik
- Department of Biology, Birmingham-Southern College, Birmingham, Alabama, United States of America
| | - Nona Nichols
- Department of Biology, Birmingham-Southern College, Birmingham, Alabama, United States of America
| | - Kristen Poole-Sumrall
- Department of Biology, Birmingham-Southern College, Birmingham, Alabama, United States of America
| | - Elizabeth Sztul
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
| | - Melanie L. Styers
- Department of Biology, Birmingham-Southern College, Birmingham, Alabama, United States of America
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15
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Sip1, a conserved AP-1 accessory protein, is important for Golgi/endosome trafficking in fission yeast. PLoS One 2012; 7:e45324. [PMID: 23028933 PMCID: PMC3444471 DOI: 10.1371/journal.pone.0045324] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2012] [Accepted: 08/15/2012] [Indexed: 01/20/2023] Open
Abstract
We had previously identified the mutant allele of apm1+ that encodes a homolog of the mammalian μ 1A subunit of the clathrin-associated adaptor protein-1 (AP-1) complex and demonstrated that the AP-1 complex plays a role in Golgi/endosome trafficking, secretion, and vacuole fusion in fission yeast. Here, we isolated a mutant allele of its4+/sip1+, which encodes a conserved AP-1 accessory protein. The its4-1/sip1-i4 mutants and apm1-deletion cells exhibited similar phenotypes, including sensitivity to the calcineurin inhibitor FK506, Cl− and valproic acid as well as various defects in Golgi/endosomal trafficking and cytokinesis. Electron micrographs of sip1-i4 mutants revealed vacuole fragmentation and accumulation of abnormal Golgi-like structures and secretory vesicles. Overexpression of Apm1 suppressed defective membrane trafficking in sip1-i4 mutants. The Sip1-green fluorescent protein (GFP) co-localized with Apm1-mCherry at Golgi/endosomes, and Sip1 physically interacted with each subunit of the AP-1 complex. We found that Sip1 was a Golgi/endosomal protein and the sip1-i4 mutation affected AP-1 localization at Golgi/endosomes, thus indicating that Sip1 recruited the AP-1 complex to endosomal membranes by physically interacting with each subunit of this complex. Furthermore, Sip1 is required for the correct localization of Bgs1/Cps1, 1,3-β-D-glucan synthase to polarized growth sites. Consistently, the sip1-i4 mutants displayed a severe sensitivity to micafungin, a potent inhibitor of 1,3-β-D-glucan synthase. Taken together, our findings reveal a role for Sip1 in the regulation of Golgi/endosome trafficking in coordination with the AP-1 complex, and identified Bgs1, required for cell wall synthesis, as the new cargo of AP-1-dependent trafficking.
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Studies on the roles of clathrin-mediated membrane trafficking and zinc transporter Cis4 in the transport of GPI-anchored proteins in fission yeast. PLoS One 2012; 7:e41946. [PMID: 22848669 PMCID: PMC3405024 DOI: 10.1371/journal.pone.0041946] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2012] [Accepted: 06/29/2012] [Indexed: 11/30/2022] Open
Abstract
We previously identified Cis4, a zinc transporter belonging to the cation diffusion facilitator protein family, and we demonstrated that Cis4 is implicated in Golgi membrane trafficking in fission yeast. Here, we identified three glycosylphosphatidylinositol (GPI)-anchored proteins, namely Ecm33, Aah3, and Gaz2, as multicopy suppressors of the MgCl2-sensitive phenotype of cis4-1 mutant. The phenotypes of ecm33, aah3 and gaz2 deletion cells were distinct from each other, and Cis4 overexpression suppressed Δecm33 phenotypes but did not suppress Δaah3 defects. Notably, green fluorescent protein-tagged Ecm33, which was observed at the cell surface in wild-type cells, mostly localized as intracellular dots that are presumed to be the Golgi and endosomes in membrane-trafficking mutants, including Δapm1, ypt3-i5, and chc1-1 mutants. Interestingly, all these membrane-trafficking mutants showed hypersensitivity to BE49385A, an inhibitor of Its8 that is involved in GPI-anchored protein synthesis. Taken together, these results suggest that GPI-anchored proteins are transported through a clathrin-mediated post-Golgi membrane trafficking pathway and that zinc transporter Cis4 may play roles in membrane trafficking of GPI-anchored proteins in fission yeast.
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Estravís M, Rincón SA, Santos B, Pérez P. Cdc42 regulates multiple membrane traffic events in fission yeast. Traffic 2011; 12:1744-58. [PMID: 21899677 DOI: 10.1111/j.1600-0854.2011.01275.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Fission yeast Cdc42 regulates polarized growth and is involved in For3 formin activation and actin cable assembly. We show here that a thermosensitive strain carrying the cdc42L160S allele has membrane traffic defects independent of the actin cable defects. This strain has decreased acid phosphatase (AP) secretion, intracellular accumulation of vesicles and fragmentation of vacuoles. In addition, the exocyst is not localized to the tips of these cells. Overproduction of the scaffold protein Pob1 suppressed cdc42L160S thermosensitive growth and restored exocyst localization and AP secretion. The GTPase Rho3 also suppressed cdc42L160S thermosensitivity, restored exocyst localization and AP secretion. However, Rho3 did not restore the actin cables in these cells as Pob1 does. Similarly, overexpression of psy1(+) , coding a syntaxin (t-SNARE) homolog, or of ypt2(+) , coding an SEC4 homolog in fission yeast, rescued growth at high temperature but did not restore actin cables, nor the exocyst-polarized localization. cdc42L160S cells also have defects in vacuole formation that were rescued by Pob1, Rho3 and Psy1. All together, we propose that Cdc42 and the scaffold Pob1 are required for membrane trafficking and fusion, contributing to polarized secretion, endosome recycling, vacuole formation and growth.
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Affiliation(s)
- Miguel Estravís
- Instituto de Biología funcional y Genómica, Consejo Superior de Investigaciones Científicas CSIC/Departamento de Microbiología y Genética, Universidad de Salamanca, 30007 Salamanca, Spain
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18
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Ma Y, Jiang W, Liu Q, Ryuko S, Kuno T. Genome-wide screening for genes associated with FK506 sensitivity in fission yeast. PLoS One 2011; 6:e23422. [PMID: 21850271 PMCID: PMC3151288 DOI: 10.1371/journal.pone.0023422] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2011] [Accepted: 07/17/2011] [Indexed: 01/05/2023] Open
Abstract
We have been studying calcineurin signal transduction pathway in fission yeast Schizosaccharomyces pombe (S. pombe) by developing a genetic screen for mutants that show hypersensitivity to the immunosuppressive calcineurin inhibitor FK506 (tacrolimus). In the present study, to identify nonessential genes that are functionally related to the calcineurin signaling pathway, we performed a genome-wide screen of 3004 haploid deletion strains and confirmed 72 deletion strains to be FK506 sensitive. These 72 genes are classified into nine functional groups to include membrane trafficking (16 genes), signal transduction (10 genes), ubiquitination (8 genes), chromatin remodeling (6 genes), cytokinesis (4 genes), ribosomal protein (3 genes), RNA binding protein (3 genes), and a variety of other known functions (17 genes) or still unknown functions (5 genes) in the biological system. In our previous screening of FK506-sensitive mutants we isolated several membrane-trafficking mutants showing defective cell wall integrity. Here, we further examined the vacuolar fusion, the v-SNARE synaptobrevin Syb1 localization, and the sensitivity to the β-glucan synthase inhibitor micafungin in these 72 FK506-sensitive strains. Results showed that 25 deletion strains exhibited abnormal vacuole fusion, 19 deletion strains exhibited Syb1 mislocalization, and 14 deletion strains exhibited both abnormal vacuole fusion and Syb1 mislocalization, while 42 deletion strains showed both normal vacuole fusion and Syb1 localization. Likewise, 16 deletion strains showed sensitivity to micafungin. Altogether, our present study indicates that calcineurin mediates a plethora of physiological processes in fission yeast, and that calcineurin is extensively involved in cross-talk between signaling pathways.
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Affiliation(s)
- Yan Ma
- Division of Molecular Pharmacology and Pharmacogenomics, Department of Biochemistry and Molecular Biology, Kobe University Graduate School of Medicine, Kobe, Japan.
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19
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Kita A, Li C, Yu Y, Umeda N, Doi A, Yasuda M, Ishiwata S, Taga A, Horiuchi Y, Sugiura R. Role of the Small GTPase Rho3 in Golgi/Endosome trafficking through functional interaction with adaptin in Fission Yeast. PLoS One 2011; 6:e16842. [PMID: 21304827 PMCID: PMC3033427 DOI: 10.1371/journal.pone.0016842] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2010] [Accepted: 01/14/2011] [Indexed: 01/08/2023] Open
Abstract
Background We had previously identified the mutant allele of apm1+ that encodes a homolog of the mammalian µ1A subunit of the clathrin-associated adaptor protein-1 (AP-1) complex, and we demonstrated the role of Apm1 in Golgi/endosome trafficking, secretion, and vacuole fusion in fission yeast. Methodology/Principal Findings In the present study, we isolated rho3+, which encodes a Rho-family small GTPase, an important regulator of exocystosis, as a multicopy-suppressor of the temperature-sensitive growth of the apm1-1 mutant cells. Overexpression of Rho3 suppressed the Cl− sensitivity and immunosuppressant sensitivity of the apm1-1 mutant cells. Overexpression of Rho3 also suppressed the fragmentation of vacuoles, and the accumulation of v-SNARE Syb1 in Golgi/endosomes and partially suppressed the defective secretion associated with apm1-deletion cells. Notably, electron microscopic observation of the rho3-deletion cells revealed the accumulation of abnormal Golgi-like structures, vacuole fragmentation, and accumulation of secretory vesicles; these phenotypes were very similar to those of the apm1-deletion cells. Furthermore, the rho3-deletion cells and apm1-deletion cells showed very similar phenotypic characteristics, including the sensitivity to the immunosuppressant FK506, the cell wall-damaging agent micafungin, Cl−, and valproic acid. Green fluorescent protein (GFP)-Rho3 was localized at Golgi/endosomes as well as the plasma membrane and division site. Finally, Rho3 was shown to form a complex with Apm1 as well as with other subunits of the clathrin-associated AP-1 complex in a GTP- and effector domain-dependent manner. Conclusions/Significance Taken together, our findings reveal a novel role of Rho3 in the regulation of Golgi/endosome trafficking and suggest that clathrin-associated adaptor protein-1 and Rho3 co-ordinate in intracellular transport in fission yeast. To the best of our knowledge, this study provides the first evidence of a direct link between the small GTPase Rho and the clathrin-associated adaptor protein-1 in membrane trafficking.
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Affiliation(s)
- Ayako Kita
- Laboratory of Molecular Pharmacogenomics, School of Pharmaceutical Sciences, Kinki University, Higashi-Osaka, Japan
| | - Cuifang Li
- Laboratory of Molecular Pharmacogenomics, School of Pharmaceutical Sciences, Kinki University, Higashi-Osaka, Japan
| | - Yang Yu
- Laboratory of Molecular Pharmacogenomics, School of Pharmaceutical Sciences, Kinki University, Higashi-Osaka, Japan
| | - Nanae Umeda
- Laboratory of Molecular Pharmacogenomics, School of Pharmaceutical Sciences, Kinki University, Higashi-Osaka, Japan
| | - Akira Doi
- Laboratory of Molecular Pharmacogenomics, School of Pharmaceutical Sciences, Kinki University, Higashi-Osaka, Japan
| | - Mitsuko Yasuda
- Laboratory of Molecular Pharmacogenomics, School of Pharmaceutical Sciences, Kinki University, Higashi-Osaka, Japan
| | - Shunji Ishiwata
- Laboratory of Molecular Pharmacogenomics, School of Pharmaceutical Sciences, Kinki University, Higashi-Osaka, Japan
| | - Atsushi Taga
- Laboratory of Pharmaceutical Analytical Chemistry, School of Pharmaceutical Sciences, Kinki University, Higashi-Osaka, Japan
| | | | - Reiko Sugiura
- Laboratory of Molecular Pharmacogenomics, School of Pharmaceutical Sciences, Kinki University, Higashi-Osaka, Japan
- * E-mail:
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Ma Y, Sugiura R, Zhang L, Zhou X, Takeuchi M, He Y, Kuno T. Isolation of a fission yeast mutant that is sensitive to valproic acid and defective in the gene encoding Ric1, a putative component of Ypt/Rab-specific GEF for Ryh1 GTPase. Mol Genet Genomics 2010; 284:161-71. [PMID: 20623139 DOI: 10.1007/s00438-010-0550-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2010] [Accepted: 06/10/2010] [Indexed: 01/08/2023]
Abstract
Valproic acid (VPA) causes various therapeutic and biological effects, but the exact mechanisms underlying these effects, however, remain elusive. To gain insights into the molecular mechanisms of VPA action, we performed in fission yeast a genetic screen for mutants that show VPA hypersensitivity and have identified several membrane-trafficking mutants including vas1-1/vps45 and vas2-1/aps1. Here, we describe the isolation and characterization of vas3-1/ric1-v3, a mutant allele of the ric1 (+) gene encoding a fission yeast homolog of the budding yeast Ric1p, a component of Ypt/Rab-specific guanyl-nucleotide exchange factor (GEF). The Rab GTPase Ryh1 knockout (Deltaryh1) cells and Deltaric1 cells exhibited similar phenotypes. The double knockout Deltaric1Deltaryh1 cells did not display synthetic growth defects. These results are consistent with the notion that Ric1 may be a component of the GEF complex for Ryh1. Overexpression of wild-type Ryh1 and the constitutively active Ryh1Q70L only partially suppressed the phenotypes of ric1-v3 and Deltaric1 cells, and they failed to localize to the Golgi/endosomes in ric1-v3 and Deltaric1 cells. Furthermore, we isolated vps15 (+) gene, encoding a serine/threonine protein kinase, as a dosage-dependent suppressor of the temperature-sensitive phenotype of ric1-v3 mutant, but not that of Deltaric1 cells. Our results showed that the ric1-v3 mutant allele has some residual functional activity and suggest that Vps15 plays a role in the regulation of Ric1 function. In conclusion, Ric1 is a putative component of GEF for Ryh1 and might be regulated by Vps15. Further studies are needed to reveal the mechanism underlying the regulation.
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Affiliation(s)
- Yan Ma
- Division of Molecular Pharmacology and Pharmacogenomics, Department of Biochemistry and Molecular Biology, Kobe University Graduate School of Medicine, Kobe, Hyogo, Japan.
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Current awareness on yeast. Yeast 2010. [DOI: 10.1002/yea.1714] [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] Open
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