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Morozumi Y, Hayashi Y, Chu CM, Sofyantoro F, Akikusa Y, Fukuda T, Shiozaki K. Fission yeast Pib2 localizes to vacuolar membranes and regulates TOR complex 1 through evolutionarily conserved domains. FEBS Lett 2024. [PMID: 39010328 DOI: 10.1002/1873-3468.14980] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2024] [Revised: 06/08/2024] [Accepted: 06/10/2024] [Indexed: 07/17/2024]
Abstract
TOR complex 1 (TORC1) is a multi-protein kinase complex that coordinates cellular growth with environmental cues. Recent studies have identified Pib2 as a critical activator of TORC1 in budding yeast. Here, we show that loss of Pib2 causes severe growth defects in fission yeast cells, particularly when basal TORC1 activity is diminished by hypomorphic mutations in tor2, the gene encoding the catalytic subunit of TORC1. Consistently, TORC1 activity is significantly compromised in the tor2 hypomorphic mutants lacking Pib2. Moreover, as in budding yeast, fission yeast Pib2 localizes to vacuolar membranes via its FYVE domain, with its tail motif indispensable for TORC1 activation. These results strongly suggest that Pib2-mediated positive regulation of TORC1 is evolutionarily conserved between the two yeast species.
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Affiliation(s)
- Yuichi Morozumi
- Division of Biological Science, Nara Institute of Science and Technology, Ikoma, Japan
| | - Yumi Hayashi
- Division of Biological Science, Nara Institute of Science and Technology, Ikoma, Japan
| | - Cuong Minh Chu
- Division of Biological Science, Nara Institute of Science and Technology, Ikoma, Japan
| | - Fajar Sofyantoro
- Division of Biological Science, Nara Institute of Science and Technology, Ikoma, Japan
- Department of Animal Physiology, Faculty of Biology, Universitas Gadjah Mada, Yogyakarta, Indonesia
| | - Yutaka Akikusa
- Division of Biological Science, Nara Institute of Science and Technology, Ikoma, Japan
| | - Tomoyuki Fukuda
- Department of Cellular Physiology, Niigata University Graduate School of Medical and Dental Sciences, Japan
| | - Kazuhiro Shiozaki
- Division of Biological Science, Nara Institute of Science and Technology, Ikoma, Japan
- Department of Microbiology and Molecular Genetics, University of California, Davis, CA, USA
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2
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Fission Yeast Autophagy Machinery. Cells 2022; 11:cells11071086. [PMID: 35406650 PMCID: PMC8997447 DOI: 10.3390/cells11071086] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2022] [Revised: 03/19/2022] [Accepted: 03/22/2022] [Indexed: 01/27/2023] Open
Abstract
Autophagy is a conserved process that delivers cytoplasmic components to the vacuole/lysosome. It plays important roles in maintaining cellular homeostasis and conferring stress resistance. In the fission yeast Schizosaccharomyces pombe, autophagy is important for cell survival under nutrient depletion and ER stress conditions. Experimental analyses of fission yeast autophagy machinery in the last 10 years have unveiled both similarities and differences in autophagosome biogenesis mechanisms between fission yeast and other model eukaryotes for autophagy research, in particular, the budding yeast Saccharomyces cerevisiae. More recently, selective autophagy pathways that deliver hydrolytic enzymes, the ER, and mitochondria to the vacuole have been discovered in fission yeast, yielding novel insights into how cargo selectivity can be achieved in autophagy. Here, we review the progress made in understanding the autophagy machinery in fission yeast.
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Yu ZQ, Sun LL, Jiang ZD, Liu XM, Zhao D, Wang HT, He WZ, Dong MQ, Du LL. Atg38-Atg8 interaction in fission yeast establishes a positive feedback loop to promote autophagy. Autophagy 2020; 16:2036-2051. [PMID: 31941401 PMCID: PMC7595586 DOI: 10.1080/15548627.2020.1713644] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Macroautophagy (autophagy) is driven by the coordinated actions of core autophagy-related (Atg) proteins. Atg8, the core Atg protein generally considered acting most downstream, has recently been shown to interact with other core Atg proteins via their Atg8-family-interacting motifs (AIMs). However, the extent, functional consequence, and evolutionary conservation of such interactions remain inadequately understood. Here, we show that, in the fission yeast Schizosaccharomyces pombe, Atg38, a subunit of the phosphatidylinositol 3-kinase (PtdIns3K) complex I, interacts with Atg8 via an AIM, which is highly conserved in Atg38 proteins of fission yeast species, but not conserved in Atg38 proteins of other species. This interaction recruits Atg38 to Atg8 on the phagophore assembly site (PAS) and consequently enhances PAS accumulation of the PtdIns3K complex I and Atg proteins acting downstream of the PtdIns3K complex I, including Atg8. The disruption of the Atg38-Atg8 interaction leads to the reduction of autophagosome size and autophagic flux. Remarkably, the loss of this interaction can be compensated by an artificial Atg14-Atg8 interaction. Our findings demonstrate that the Atg38-Atg8 interaction in fission yeast establishes a positive feedback loop between Atg8 and the PtdIns3K complex I to promote efficient autophagosome formation, underscore the prevalence and diversity of AIM-mediated connections within the autophagic machinery, and reveal unforeseen flexibility of such connections. Abbreviations: AIM: Atg8-family-interacting motif; AP-MS: affinity purification coupled with mass spectrometry; Atg: autophagy-related; FLIP: fluorescence loss in photobleaching; PAS: phagophore assembly site; PB: piggyBac; PE: phosphatidylethanolamine; PtdIns3K: phosphatidylinositol 3-kinase; PtdIns3P: phosphatidylinositol 3-phosphate.
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Affiliation(s)
- Zhong-Qiu Yu
- National Institute of Biological Sciences , Beijing, China.,PTN Graduate Program, School of Life Sciences, Peking University , Beijing, China
| | - Ling-Ling Sun
- National Institute of Biological Sciences , Beijing, China
| | - Zhao-Di Jiang
- National Institute of Biological Sciences , Beijing, China
| | - Xiao-Man Liu
- National Institute of Biological Sciences , Beijing, China
| | - Dan Zhao
- National Institute of Biological Sciences , Beijing, China
| | - Hai-Tao Wang
- National Institute of Biological Sciences , Beijing, China
| | - Wan-Zhong He
- National Institute of Biological Sciences , Beijing, China
| | - Meng-Qiu Dong
- National Institute of Biological Sciences , Beijing, China.,Tsinghua Institute of Multidisciplinary Biomedical Research, Tsinghua University , Beijing, China
| | - Li-Lin Du
- National Institute of Biological Sciences , Beijing, China.,Tsinghua Institute of Multidisciplinary Biomedical Research, Tsinghua University , Beijing, China
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4
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Tsukamoto Y, Kagiwada S, Shimazu S, Takegawa K, Noguchi T, Miyamoto M. Coordinated regulation by two VPS9 domain-containing guanine nucleotide exchange factors in small GTPase Rab5 signaling pathways in fission yeast. Biochem Biophys Res Commun 2015; 458:802-9. [DOI: 10.1016/j.bbrc.2015.02.031] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2015] [Accepted: 02/06/2015] [Indexed: 12/11/2022]
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5
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Tsukamoto Y, Katayama C, Shinohara M, Shinohara A, Maekawa S, Miyamoto M. The small GTPase Rab5 homologue Ypt5 regulates cell morphology, sexual development, ion-stress response and vacuolar formation in fission yeast. Biochem Biophys Res Commun 2013; 441:867-72. [PMID: 24211211 DOI: 10.1016/j.bbrc.2013.10.158] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2013] [Accepted: 10/29/2013] [Indexed: 01/08/2023]
Abstract
Inner-membrane transport is critical to cell function. Rab family GTPases play an important role in vesicle transport. In mammalian cells, Rab5 is reported to be involved in the regulation of endosome formation, phagocytosis and chromosome alignment. Here, we examined the role of the fission yeast Rab5 homologue Ypt5 using a point mutant allele. Mutant cells displayed abnormal cell morphology, mating, sporulation, endocytosis, vacuole fusion and responses to ion stress. Our data strongly suggest that fission yeast Rab5 is involved in the regulation of various types of cellular functions.
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Affiliation(s)
- Yuta Tsukamoto
- Graduate School of Science, Kobe University, 1-1 Rokkodai-cho Nada, Kobe 657-8501, Japan
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6
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Role of septins in the orientation of forespore membrane extension during sporulation in fission yeast. Mol Cell Biol 2010; 30:2057-74. [PMID: 20123972 DOI: 10.1128/mcb.01529-09] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
During yeast sporulation, a forespore membrane (FSM) initiates at each spindle-pole body and extends to form the spore envelope. We used Schizosaccharomyces pombe to investigate the role of septins during this process. During the prior conjugation of haploid cells, the four vegetatively expressed septins (Spn1, Spn2, Spn3, and Spn4) coassemble at the fusion site and are necessary for its normal morphogenesis. Sporulation involves a different set of four septins (Spn2, Spn5, Spn6, and the atypical Spn7) that does not include the core subunits of the vegetative septin complex. The four sporulation septins form a complex in vitro and colocalize interdependently to a ring-shaped structure along each FSM, and septin mutations result in disoriented FSM extension. The septins and the leading-edge proteins appear to function in parallel to orient FSM extension. Spn2 and Spn7 bind to phosphatidylinositol 4-phosphate [PtdIns(4)P] in vitro, and PtdIns(4)P is enriched in the FSMs, suggesting that septins bind to the FSMs via this lipid. Cells expressing a mutant Spn2 protein unable to bind PtdIns(4)P still form extended septin structures, but these structures fail to associate with the FSMs, which are frequently disoriented. Thus, septins appear to form a scaffold that helps to guide the oriented extension of the FSM.
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Schizosaccharomyces pombe Sst4p, a conserved Vps27/Hrs homolog, functions downstream of phosphatidylinositol 3-kinase Pik3p to mediate proper spore formation. EUKARYOTIC CELL 2007; 6:2343-53. [PMID: 17951524 DOI: 10.1128/ec.00211-07] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Sporulation of the fission yeast Schizosaccharomyces pombe is a developmental process that generates gametes and that includes the formation of spore envelope precursors called the forespore membranes. Assembly and development of forespore membranes require vesicular trafficking from other intracellular membrane compartments. We have shown that phosphatidylinositol 3-kinase (PtdIns 3-kinase) is required for efficient and proper development of forespore membranes. The role of a FYVE domain protein, Sst4p, a homolog of Vps27p/Hrs, as a downstream factor for PtdIns 3-kinase in sporulation was investigated. sst4Delta asci formed spores with oval-shaped morphology and with reduced viability compared to that of the wild-type spores. The extension of forespore membranes was inefficient, and bubble-like structures emerged from the leading edges of the forespore membranes. Sst4p localization was examined using fluorescent protein fusions and was found to be adjacent to the forespore membranes during sporulation. The localization and function of Sst4p were dependent on its FYVE domain and on PtdIns 3-kinase. Sst4p colocalized and interacted with Hse1p, a homolog of Saccharomyces cerevisiae Hse1p and of mammalian STAM. Mutations in all three UIM domains of the Sst4p/Hse1p complex resulted in formation of spores with abnormal morphology. These results suggest that Sst4p is a downstream factor of PtdIns 3-kinase and functions in forespore membrane formation.
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8
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Strahl T, Thorner J. Synthesis and function of membrane phosphoinositides in budding yeast, Saccharomyces cerevisiae. BIOCHIMICA ET BIOPHYSICA ACTA 2007; 1771:353-404. [PMID: 17382260 PMCID: PMC1868553 DOI: 10.1016/j.bbalip.2007.01.015] [Citation(s) in RCA: 236] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2006] [Revised: 01/29/2007] [Accepted: 01/30/2007] [Indexed: 02/02/2023]
Abstract
It is now well appreciated that derivatives of phosphatidylinositol (PtdIns) are key regulators of many cellular processes in eukaryotes. Of particular interest are phosphoinositides (mono- and polyphosphorylated adducts to the inositol ring in PtdIns), which are located at the cytoplasmic face of cellular membranes. Phosphoinositides serve both a structural and a signaling role via their recruitment of proteins that contain phosphoinositide-binding domains. Phosphoinositides also have a role as precursors of several types of second messengers for certain intracellular signaling pathways. Realization of the importance of phosphoinositides has brought increased attention to characterization of the enzymes that regulate their synthesis, interconversion, and turnover. Here we review the current state of our knowledge about the properties and regulation of the ATP-dependent lipid kinases responsible for synthesis of phosphoinositides and also the additional temporal and spatial controls exerted by the phosphatases and a phospholipase that act on phosphoinositides in yeast.
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Affiliation(s)
- Thomas Strahl
- Divisions of Biochemistry & Molecular Biology and of Cell & Developmental Biology.Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720 USA
| | - Jeremy Thorner
- Divisions of Biochemistry & Molecular Biology and of Cell & Developmental Biology.Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720 USA
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9
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Hosking SL, Trinci AP, Robson GD. In vitro metabolism of inositol 1,4,5-trisphosphate by Neurospora crassa. FEMS Microbiol Lett 2006. [DOI: 10.1111/j.1574-6968.1997.tb12648.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
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10
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Koga T, Onishi M, Nakamura Y, Hirata A, Nakamura T, Shimoda C, Iwaki T, Takegawa K, Fukui Y. Sorting nexin homologues are targets of phosphatidylinositol 3-phosphate in sporulation of Schizosaccharomyces pombe. Genes Cells 2005; 9:561-74. [PMID: 15189449 DOI: 10.1111/j.1356-9597.2004.00744.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Schizosaccharomyces pombe defective in phosphatidylinositol (PtdIns) 3-kinase shows various defects in forespore membrane formation, including onset, growth orientation, and closure. Downstream factors of PtdIns 3-kinase in this system were explored. Among various phox homology (PX) domain-containing proteins, Vps5p and Vps17p, homologues of sorting nexins, were found to be required for efficient sporulation. Cells defective in these proteins showed a disordered growth orientation of the forespore membrane, as is the case with Deltapik3 cells. Vps5p and Vps17p with mutations in the PX domains failed to suppress the defects of their relevant disruptants. Vps5p and Vps17p migrated toward the the forespore membrane in a pik3+-dependent manner, suggesting that these proteins may interact with PtdIns(3)P. Electron-microscopic analysis revealed that the forespore membrane fails to engulf the nucleus in some of these cells, accumulating vesicle-like bodies similar to those seen in Deltaspo3 cells. These results suggest that Vps5p and Vps17p are the targets of PtdIns(3)P in vesicle transport required for onset of the forespore membrane formation.
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Affiliation(s)
- Takako Koga
- Laboratory of Biological Chemistry, Graduate School of Agricultural and Life Science, University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
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11
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Onishi M, Koga T, Morita R, Nakamura Y, Nakamura T, Shimoda C, Takegawa K, Hirata A, Fukui Y. Role of phosphatidylinositol 3-phosphate in formation of forespore membrane in Schizosaccharomyces pombe. Yeast 2003; 20:193-206. [PMID: 12557273 DOI: 10.1002/yea.953] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Phosphatidylinositol (PI) 3-kinase (encoded by the pik3(+) gene) in Schizosaccharomyces pombe has been identified as a homologue of VPS34p, a protein required for proper vesicular protein sorting. The clone defective in this protein carries enlarged vacuoles and exhibits sensitivity to high temperature or high ion concentration. The effect of disruption of pik3(+) on sporulation of Sz. pombe was examined. The diploid cells underwent G(1) arrest and meiosis. However, the spores formed by the deltapik3 cells were not viable. Electron-microscopic analysis revealed that the growth of the forespore membrane of deltapik3 cells was not correctly orientated, failing to engulf the nucleus or forming extremely small spores, as was confirmed by the use of Spo3p-GFP and GFP-Psy1p, which are markers of the forespore membrane. The coating materials found along the forespore membrane of the wild-type were greatly reduced in these cells. PI 3-P, the product of Pik3p, was detected on the forespore membrane, suggesting that PI 3-P-dependent vesicle transport may take place in formation of the forespore membrane. Misshaped forespore membrane, accumulation of vesicles, formation of small non-viable spores, and suppression by over expression of Psy1p were the phenotypes commonly seen in deltapik3 and deltaspo3 cells, suggesting a relationship between the functions of Pik3p and Spo3p in formation of the forespore membrane in Sz. pombe.
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Affiliation(s)
- Masayuki Onishi
- Laboratory of Biological Chemistry, Graduate School of Agriculture and Life Science, University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
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Takegawa K, Iwaki T, Fujita Y, Morita T, Hosomi A, Tanaka N. Vesicle-mediated Protein Transport Pathways to the Vacuole in Schizosaccharomyces pombe. Cell Struct Funct 2003; 28:399-417. [PMID: 14745133 DOI: 10.1247/csf.28.399] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
The vacuole of Saccharomyces cerevisiae plays essential roles not only for osmoregulation and ion homeostasis but also down-regulation (degradation) of cell surface proteins and protein and organellar turnover. Genetic selections and genome-wide screens in S. cerevisiae have resulted in the identification of a large number of genes required for delivery of proteins to the vacuole. Although the complete genome sequence of the fission yeast Schizosaccharomyces pombe has been reported, there have been few reports on the proteins required for vacuolar protein transport and vacuolar biogenesis in S. pombe. Recent progress in the S. pombe genome project of has revealed that most of the genes required for vacuolar biogenesis and protein transport are conserved between S. pombe and S. cerevisiae. This suggests that the basic machinery of vesicle-mediated protein delivery to the vacuole is conserved between the two yeasts. Identification and characterization of the fission yeast counterparts of the budding yeast Vps and Vps-related proteins have facilitated our understanding of protein transport pathways to the vacuole in S. pombe. This review focuses on the recent advances in vesicle-mediated protein transport to the vacuole in S. pombe.
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Affiliation(s)
- Kaoru Takegawa
- Department of Life Sciences, Faculty of Agriculture, Kagawa University, Miki-cho, Kagawa 761-0795, Japan.
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Augsten M, Hübner C, Nguyen M, Künkel W, Härtl A, Eck R. Defective Hyphal induction of a Candida albicans phosphatidylinositol 3-phosphate 5-kinase null mutant on solid media does not lead to decreased virulence. Infect Immun 2002; 70:4462-70. [PMID: 12117957 PMCID: PMC128189 DOI: 10.1128/iai.70.8.4462-4470.2002] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2001] [Revised: 11/27/2001] [Accepted: 04/25/2002] [Indexed: 11/20/2022] Open
Abstract
A phosphatidylinositol 3-phosphate [PI(3)P] 5-kinase gene (CaFAB1) of the most important human pathogenic yeast, Candida albicans, was cloned and sequenced. An open reading frame was detected which encodes a 2,369-amino-acid protein with a calculated molecular mass of 268 kDa and a relative isoelectric point of 6.76. This protein exhibits 38% overall amino acid sequence identity with Saccharomyces cerevisiae Fab1p. We localized the CaFAB1 gene on chromosome R. To determine the influence of the PI(3)P 5-kinase CaFab1p on processes involved in C. albicans morphogenesis and pathogenicity, we sequentially disrupted both copies of the gene. Homozygous deletion of C. albicans CaFAB1 resulted in a mutant strain which exhibited defects in morphogenesis. A Cafab1 null mutant had enlarged vacuoles, an acidification defect, and increased generation times and was unable to form hyphae on different solid media. The sensitivities to hyperosmotic and high-temperature stresses, adherence, and virulence compared to those of wild-type strain SC5314 were not affected.
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Affiliation(s)
- Martin Augsten
- Department of Infection Biology, Hans Knöll Institute for Natural Products Research, D-07745 Jena, Germany
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Morishita M, Morimoto F, Kitamura K, Koga T, Fukui Y, Maekawa H, Yamashita I, Shimoda C. Phosphatidylinositol 3-phosphate 5-kinase is required for the cellular response to nutritional starvation and mating pheromone signals in Schizosaccharomyces pombe. Genes Cells 2002; 7:199-215. [PMID: 11895483 DOI: 10.1046/j.1356-9597.2001.00510.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BACKGROUND Phosphatidylinositol (3,5) bisphosphate, which is converted from phosphatidylinositol 3-phosphate by phosphatidylinositol 3-phosphate 5-kinase, is implicated in vacuolar functions and the sorting of cell surface proteins within endosomes in the endocytic pathway of budding yeast. A homologous protein, SpFab1p, has been found in the fission yeast Schizosaccharomyces pombe, but its role is not known. RESULTS Here we report that SpFab1p is encoded by ste12+ known as a fertility gene in S. pombe. The ste12 mutant grew normally under stress-free conditions, but was highly vacuolated and swelled at high temperatures and under starvation conditions. In nitrogen-free medium, ste12 cells were arrested in G1 phase, but partially defective in the expression of genes responsible for mating and meiosis. The ste12 mutant was defective both in the production of, and in the response to, mating pheromones. The amount of the pheromone receptor protein Map3p, was substantially decreased in ste12 cells. Map3p was transported to the cell surface, then internalized and eventually transported to the vacuolar lumen, even in the ste12 mutant. CONCLUSION The results indicate that phosphatidylinositol(3,5)bisphosphate is essential for cellular responses to various stresses and for the mating pheromone signalling under starvation conditions.
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Affiliation(s)
- Masayo Morishita
- Department of Biology, Graduate School of Science, Osaka City University, Sumiyoshi-ku, Osaka 558-8585, Japan
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Bruckmann A, Künkel W, Härtl A, Wetzker R, Eck R. A phosphatidylinositol 3-kinase of Candida albicans influences adhesion, filamentous growth and virulence. MICROBIOLOGY (READING, ENGLAND) 2000; 146 ( Pt 11):2755-2764. [PMID: 11065354 DOI: 10.1099/00221287-146-11-2755] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
To determine if cellular functions of the phosphatidylinositol 3-kinase CaVps34p are related to processes governing Candida albicans pathogenicity, both copies of the gene were sequentially disrupted. Homozygous deletion of C. albicans VPS34 resulted in a mutant strain which exhibited defects not only in intracellular vesicle transport processes but also in morphogenesis. The CaVPS34 null mutant was unable to form hyphae on different solid media whilst showing a significantly delayed yeast-to-hyphae transition in liquid media. In addition, the mutant was rendered hypersensitive to temperature and osmotic stresses and had a strongly decreased ability to adhere to mouse fibroblast cells compared to the wild-type strain SC5314. Finally, evidence was obtained that CaVPS34 is essential for pathogenicity of C. albicans as the CaVPS34 null mutant was shown to be avirulent in a mouse model of systemic infection. C. albicans pathogenicity was restored to a near wild-type degree upon reintroduction of CaVPS34 into the chromosome of the null mutant, demonstrating that the observed avirulence corresponded to the loss of CaVPS34. Thus, the results suggest that CaVPS34 may serve as a potential target for antifungal drugs.
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Affiliation(s)
- Astrid Bruckmann
- Hans-Knöll-Institute for Natural Products Research, Department of Infection Biology1 and Department of Drug Testing2, Beutenbergstrasse 11, D-07745 Jena, Germany
| | - Waldemar Künkel
- Hans-Knöll-Institute for Natural Products Research, Department of Infection Biology1 and Department of Drug Testing2, Beutenbergstrasse 11, D-07745 Jena, Germany
| | - Albert Härtl
- Hans-Knöll-Institute for Natural Products Research, Department of Infection Biology1 and Department of Drug Testing2, Beutenbergstrasse 11, D-07745 Jena, Germany
| | - Reinhard Wetzker
- Friedrich Schiller University, Medical Faculty, Department of Molecular Cell Biology, Drackendorfer Strasse 1, D-07747 Jena, Germany3
| | - Raimund Eck
- Hans-Knöll-Institute for Natural Products Research, Department of Infection Biology1 and Department of Drug Testing2, Beutenbergstrasse 11, D-07745 Jena, Germany
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Eck R, Bruckmann A, Wetzker R, Künkel W. A phosphatidylinositol 3-kinase of Candida albicans: molecular cloning and characterization. Yeast 2000; 16:933-44. [PMID: 10870104 DOI: 10.1002/1097-0061(200007)16:10<933::aid-yea591>3.0.co;2-c] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
A phosphatidylinositol (PI) 3-kinase gene (CaVPS34) of the human pathogenic yeast Candida albicans was cloned by a PCR-based homology approach. The open reading frame encodes a 1020 amino acid protein with a calculated molecular weight of 118 kDa and a relative isoelectric point of 6.9. It shares 47% sequence identity with Saccharomyces cerevisiae Vps34p. Southern pattern indicated that CaVPS34 is probably present as a single copy gene per haploid genome in C. albicans. We localized the CaVPS34 gene on chromosome 1. Under all conditions tested a major CaVPS34 transcript of approximately 3. 5 kb could be detected. CaVPS34 mRNA levels increased during exponential growth up to 12-fold followed by a decline upon entry into stationary phase. The size of a 6xHis tag-CaVps34p fusion protein purified from Escherichia coli is in agreement with the calculated molecular mass of CaVps34p. It exhibits in vitro PI 3-kinase activity and produces only phosphatidylinositol 3-phosphate. The CaVPS34 gene under the control of its own promoter were not able to complement the temperature-sensitive growth of S. cerevisiae vps34. However, overexpression of CaVPS34 was sufficient to rescue the temperature-sensitive vps34 phenotype, suggesting a functional conservation in C. albicans.
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Affiliation(s)
- R Eck
- Hans-Knöll-Institute for Natural Products Research, Department of Infection Biology, Beutenbergstrasse 11, D-07745 Jena, Germany.
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17
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Babar P, Adamson C, Walker GA, Walker DW, Lithgow GJ. P13-kinase inhibition induces dauer formation, thermotolerance and longevity in C. elegans. Neurobiol Aging 1999; 20:513-9. [PMID: 10638524 DOI: 10.1016/s0197-4580(99)00094-9] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
The effects of 2-(4-Morpholinyl)-8-phenyl-4H-1-benzopyran-4-one (LY294002), an inhibitor of mammalian phosphatidylinositol 3-OH kinase, was tested on an insulin signaling-like pathway in the nematode Caenorhabditis elegans. Populations of C. elegans were treated with LY294002 at different stages of the life cycle, and its effects on development, thermotolerance and longevity were assessed. At concentrations of 160 microM and above, LY294002 significantly induced both dauer formation and thermotolerance. Treatment of adult worms also resulted in a small, but significant, increase in life span. The results presented are consistent with the view that a neuroendocrine signaling pathway functions in adult worms to determine stress resistance and longevity.
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Affiliation(s)
- P Babar
- The School of Biological Sciences, The University of Manchester, UK
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Kim BC, Lee MN, Kim JY, Lee SS, Chang JD, Kim SS, Lee SY, Kim JH. Roles of phosphatidylinositol 3-kinase and Rac in the nuclear signaling by tumor necrosis factor-alpha in rat-2 fibroblasts. J Biol Chem 1999; 274:24372-7. [PMID: 10446216 DOI: 10.1074/jbc.274.34.24372] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We investigated the extent to which phosphatidylinositol 3-kinase (PI 3-kinase) and Rac, a member of the Rho family of small GTPases, are involved in the signaling cascade triggered by tumor necrosis factor (TNF)-alpha leading to activation of c-fos serum response element (SRE) and c-Jun amino-terminal kinase (JNK) in Rat-2 fibroblasts. Inhibition of PI 3-kinase by LY294002 or wortmannin, two specific PI 3-kinase antagonists, or co-transfection with a dominant negative mutant of PI 3-kinase dose-dependently blocked stimulation of c-fos SRE by TNF-alpha. Similarly, LY294002 significantly diminished TNF-alpha-induced activation of JNK, suggesting that nuclear signaling triggered by TNF-alpha is dependent on PI 3-kinase-mediated activation of both c-fos SRE and JNK. We also found nuclear signaling by TNF-alpha to be Rac-dependent, as demonstrated by the inhibitory effect of transient co-transfection with a dominant negative Rac mutant, RacN17. Our findings suggest that Rac is situated downstream of PI 3-kinase in the TNF-alpha signaling pathway to the nucleus, and we conclude that PI 3-kinase and Rac each plays a pivotal role in the nuclear signaling cascade triggered by TNF-alpha.
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Affiliation(s)
- B C Kim
- Department of Life Science, Kwang-Ju Institute of Science and Technology, Kwang-Ju 500-712, Korea
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Munnik T, Irvine RF, Musgrave A. Phospholipid signalling in plants. BIOCHIMICA ET BIOPHYSICA ACTA 1998; 1389:222-72. [PMID: 9512651 DOI: 10.1016/s0005-2760(97)00158-6] [Citation(s) in RCA: 257] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- T Munnik
- Institute for Molecular Cell Biology, BioCentrum Amsterdam, University of Amsterdam, The Netherlands.
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Daduang S, Kimura K, Nagata S, Fukui Y. Density dependent elevation of phosphatidylinositol-3 kinase level in rat 3Y1 cells. BIOCHIMICA ET BIOPHYSICA ACTA 1998; 1401:113-20. [PMID: 9459491 DOI: 10.1016/s0167-4889(97)00108-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
We have explored the levels of phosphatidylinositol-3 kinase protein during culture of rat 3Y1 cells. Confluent cell cultures exhibited a higher level of phosphatidylinositol-3 kinase compared with that of growing cells. After replating of the cells on fresh dishes, the level of phosphatidylinositol-3 kinase returned to that of growing cells within 24h. This density-dependent regulation of the phosphatidylinositol-3 kinase level was not lined to cell growth, because growth arrest by serum starvation did not cause elevation of the phosphatidylinositol-3 kinase level. Northern blotting analysis revealed that this regulation was based on the transcriptional level. After cell growth was arrested by contact inhibition, elevation of the level of phosphatidylinositol-3,4,5-trisphosphate was detected suggesting that phosphatidylinositol-3 kinase was activated in these cells. These effects were not seen in src-transformed 3Y1 cells, suggesting that this regulation was lost in transformed cells.
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Affiliation(s)
- S Daduang
- Department of Applied Biological Chemistry, Graduate School of Agriculture and Life Science, University of Tokyo, Japan
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