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Sun H, Cai X, Yan B, Bai H, Meng D, Mo X, He S, Su G, Jiang C. Multi-Omics Analysis of Lipid Metabolism for a Marine Probiotic Meyerozyma guilliermondii GXDK6 Under High NaCl Stress. Front Genet 2022; 12:798535. [PMID: 35096014 PMCID: PMC8792971 DOI: 10.3389/fgene.2021.798535] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Accepted: 12/24/2021] [Indexed: 11/13/2022] Open
Abstract
Investigating microbial lipid regulation contributes to understanding the lipid-dependent signal transduction process of cells and helps to improve the sensitivity of microorganisms to environmental factors by interfering with lipid metabolism, thus beneficial for constructing advanced cell factories of novel molecular drugs. Integrated omics technology was used to systematically reveal the lipid metabolism mechanism of a marine Meyerozyma guilliermondii GXDK6 under high NaCl stress and test the sensitivity of GXDK6 to antibiotics when its lipid metabolism transformed. The omics data showed that when GXDK6 perceived 10% NaCl stress, the expression of AYR1 and NADPH-dependent 1-acyldihydroxyacetone phosphate reductase was inhibited, which weaken the budding and proliferation of cell membranes. This finding was further validated by decreased 64.39% of OD600 under 10% NaCl stress when compared with salt-free stress. In addition, salt stress promoted a large intracellular accumulation of glycerol, which was also verified by exogenous addition of glycerol. Moreover, NaCl stress remarkably inhibited the expression of drug target proteins (such as lanosterol 14-alpha demethylase), thereby increasing sensitivity to fluconazole. This study provided new insights into the molecular mechanism involved in the regulation of lipid metabolism in Meyerozyma guilliermondii strain and contributed to developing new methods to improve the effectiveness of killing fungi with lower antibiotics.
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Affiliation(s)
- Huijie Sun
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, Guangxi Research Center for Microbial and Enzyme Engineering Technology, College of Life Science and Technology, Guangxi University, Nanning, China
| | - Xinghua Cai
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, Guangxi Research Center for Microbial and Enzyme Engineering Technology, College of Life Science and Technology, Guangxi University, Nanning, China
| | - Bing Yan
- Guangxi Key Lab of Mangrove Conservation and Utilization, Guangxi Mangrove Research Center, Guangxi Academy of Sciences, Beihai, China
| | - Huashan Bai
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, Guangxi Research Center for Microbial and Enzyme Engineering Technology, College of Life Science and Technology, Guangxi University, Nanning, China
| | - Duotao Meng
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, Guangxi Research Center for Microbial and Enzyme Engineering Technology, College of Life Science and Technology, Guangxi University, Nanning, China
| | - Xueyan Mo
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, Guangxi Research Center for Microbial and Enzyme Engineering Technology, College of Life Science and Technology, Guangxi University, Nanning, China
| | - Sheng He
- Guangxi Birth Defects Prevention and Control Institute, Maternal and Child Health Hospital of Guangxi Zhuang Autonomous Region, Nanning, China
| | - Guijiao Su
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, Guangxi Research Center for Microbial and Enzyme Engineering Technology, College of Life Science and Technology, Guangxi University, Nanning, China
| | - Chengjian Jiang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, Guangxi Research Center for Microbial and Enzyme Engineering Technology, College of Life Science and Technology, Guangxi University, Nanning, China.,Guangxi Key Lab of Mangrove Conservation and Utilization, Guangxi Mangrove Research Center, Guangxi Academy of Sciences, Beihai, China
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Bohnert S, Antelo L, Grünewald C, Yemelin A, Andresen K, Jacob S. Rapid adaptation of signaling networks in the fungal pathogen Magnaporthe oryzae. BMC Genomics 2019; 20:763. [PMID: 31640564 PMCID: PMC6805500 DOI: 10.1186/s12864-019-6113-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2019] [Accepted: 09/20/2019] [Indexed: 11/10/2022] Open
Abstract
Background One fundamental question in biology is how the evolution of eukaryotic signaling networks has taken place. “Loss of function” (lof) mutants from components of the high osmolarity glycerol (HOG) signaling pathway in the filamentous fungus Magnaporthe oryzae are viable, but impaired in osmoregulation. Results After long-term cultivation upon high osmolarity, stable individuals with reestablished osmoregulation capacity arise independently from each of the mutants with inactivated HOG pathway. This phenomenon is extremely reproducible and occurs only in osmosensitive mutants related to the HOG pathway – not in other osmosensitive Magnaporthe mutants. The major compatible solute produced by these adapted strains to cope with high osmolarity is glycerol, whereas it is arabitol in the wildtype strain. Genome and transcriptome analysis resulted in candidate genes related to glycerol metabolism, perhaps responsible for an epigenetic induced reestablishment of osmoregulation, since these genes do not show structural variations within the coding or promotor sequences. Conclusion This is the first report of a stable adaptation in eukaryotes by producing different metabolites and opens a door for the scientific community since the HOG pathway is worked on intensively in many eukaryotic model organisms.
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Affiliation(s)
- Stefan Bohnert
- Institut für Biotechnologie und Wirkstoff-Forschung gGmbH (IBWF), Erwin-Schrödinger-Str. 56, D-67663, Kaiserslautern, Germany
| | - Luis Antelo
- Institut für Biotechnologie und Wirkstoff-Forschung gGmbH (IBWF), Erwin-Schrödinger-Str. 56, D-67663, Kaiserslautern, Germany
| | - Christiane Grünewald
- Johannes Gutenberg-University Mainz, Mikrobiologie und Weinforschung am Institut für Molekulare Physiologie, Johann-Joachim-Becherweg 15, D-55128, Mainz, Germany
| | - Alexander Yemelin
- Institut für Biotechnologie und Wirkstoff-Forschung gGmbH (IBWF), Erwin-Schrödinger-Str. 56, D-67663, Kaiserslautern, Germany
| | - Karsten Andresen
- Johannes Gutenberg-University Mainz, Mikrobiologie und Weinforschung am Institut für Molekulare Physiologie, Johann-Joachim-Becherweg 15, D-55128, Mainz, Germany
| | - Stefan Jacob
- Institut für Biotechnologie und Wirkstoff-Forschung gGmbH (IBWF), Erwin-Schrödinger-Str. 56, D-67663, Kaiserslautern, Germany. .,Johannes Gutenberg-University Mainz, Mikrobiologie und Weinforschung am Institut für Molekulare Physiologie, Johann-Joachim-Becherweg 15, D-55128, Mainz, Germany.
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GPD1 Specifically Marks Dormant Glioma Stem Cells with a Distinct Metabolic Profile. Cell Stem Cell 2019; 25:241-257.e8. [DOI: 10.1016/j.stem.2019.06.004] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2018] [Revised: 03/15/2019] [Accepted: 06/07/2019] [Indexed: 12/26/2022]
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Improving ethanol yields in sugarcane molasses fermentation by engineering the high osmolarity glycerol pathway while maintaining osmotolerance in Saccharomyces cerevisiae. Appl Microbiol Biotechnol 2018; 103:1031-1042. [DOI: 10.1007/s00253-018-9532-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2018] [Revised: 11/12/2018] [Accepted: 11/17/2018] [Indexed: 01/10/2023]
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5
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Phospholipases play multiple cellular roles including growth, stress tolerance, sexual development, and virulence in fungi. Microbiol Res 2018; 209:55-69. [DOI: 10.1016/j.micres.2017.12.012] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Revised: 12/21/2017] [Accepted: 12/31/2017] [Indexed: 12/16/2022]
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6
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Adaptive response and tolerance to sugar and salt stress in the food yeast Zygosaccharomyces rouxii. Int J Food Microbiol 2014; 185:140-57. [DOI: 10.1016/j.ijfoodmicro.2014.05.015] [Citation(s) in RCA: 84] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2013] [Revised: 04/18/2014] [Accepted: 05/04/2014] [Indexed: 11/21/2022]
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Trancriptional landscape of Aspergillus niger at breaking of conidial dormancy revealed by RNA-sequencing. BMC Genomics 2013; 14:246. [PMID: 23577966 PMCID: PMC3635940 DOI: 10.1186/1471-2164-14-246] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2012] [Accepted: 04/06/2013] [Indexed: 12/14/2022] Open
Abstract
Background Genome-wide analysis was performed to assess the transcriptional landscape of germinating A. niger conidia using both next generation RNA-sequencing and GeneChips. The metabolism of storage compounds during conidial germination was also examined and compared to the transcript levels from associated genes. Results The transcriptome of dormant conidia was shown to be highly differentiated from that of germinating conidia and major changes in response to environmental shift occurred within the first hour of germination. The breaking of dormancy was associated with increased transcript levels of genes involved in the biosynthesis of proteins, RNA turnover and respiratory metabolism. Increased transcript levels of genes involved in metabolism of nitrate at the onset of germination implies its use as a source of nitrogen. The transcriptome of dormant conidia contained a significant component of antisense transcripts that changed during germination. Conclusion Dormant conidia contained transcripts of genes involved in fermentation, gluconeogenesis and the glyoxylate cycle. The presence of such transcripts in dormant conidia may indicate the generation of energy from non-carbohydrate substrates during starvation-induced conidiation or for maintenance purposes during dormancy. The immediate onset of metabolism of internal storage compounds after the onset of germination, and the presence of transcripts of relevant genes, suggest that conidia are primed for the onset of germination. For some genes, antisense transcription is regulated in the transition from resting conidia to fully active germinants.
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Casolari JM, Thompson MA, Salzman J, Champion LM, Moerner WE, Brown PO. Widespread mRNA association with cytoskeletal motor proteins and identification and dynamics of myosin-associated mRNAs in S. cerevisiae. PLoS One 2012; 7:e31912. [PMID: 22359641 PMCID: PMC3281097 DOI: 10.1371/journal.pone.0031912] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2012] [Accepted: 01/15/2012] [Indexed: 01/08/2023] Open
Abstract
Programmed mRNA localization to specific subcellular compartments for localized translation is a fundamental mechanism of post-transcriptional regulation that affects many, and possibly all, mRNAs in eukaryotes. We describe here a systematic approach to identify the RNA cargoes associated with the cytoskeletal motor proteins of Saccharomyces cerevisiae in combination with live-cell 3D super-localization microscopy of endogenously tagged mRNAs. Our analysis identified widespread association of mRNAs with cytoskeletal motor proteins, including association of Myo3 with mRNAs encoding key regulators of actin branching and endocytosis such as WASP and WIP. Using conventional fluorescence microscopy and expression of MS2-tagged mRNAs from endogenous loci, we observed a strong bias for actin patch nucleator mRNAs to localize to the cell cortex and the actin patch in a Myo3- and F-actin dependent manner. Use of a double-helix point spread function (DH-PSF) microscope allowed super-localization measurements of single mRNPs at a spatial precision of 25 nm in x and y and 50 nm in z in live cells with 50 ms exposure times, allowing quantitative profiling of mRNP dynamics. The actin patch mRNA exhibited distinct and characteristic diffusion coefficients when compared to a control mRNA. In addition, disruption of F-actin significantly expanded the 3D confinement radius of an actin patch nucleator mRNA, providing a quantitative assessment of the contribution of the actin cytoskeleton to mRNP dynamic localization. Our results provide evidence for specific association of mRNAs with cytoskeletal motor proteins in yeast, suggest that different mRNPs have distinct and characteristic dynamics, and lend insight into the mechanism of actin patch nucleator mRNA localization to actin patches.
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Affiliation(s)
- Jason M. Casolari
- Department of Biochemistry, Stanford University School of Medicine, Stanford, California, United States of America
- Howard Hughes Medical Institute, Stanford University School of Medicine, Stanford, California, United States of America
| | - Michael A. Thompson
- Department of Chemistry, Stanford University, Stanford, California, United States of America
| | - Julia Salzman
- Department of Biochemistry, Stanford University School of Medicine, Stanford, California, United States of America
- Howard Hughes Medical Institute, Stanford University School of Medicine, Stanford, California, United States of America
- Department of Statistics, Stanford University, Stanford, California, United States of America
| | - Lowry M. Champion
- Department of Biochemistry, Stanford University School of Medicine, Stanford, California, United States of America
- Howard Hughes Medical Institute, Stanford University School of Medicine, Stanford, California, United States of America
| | - W. E. Moerner
- Department of Chemistry, Stanford University, Stanford, California, United States of America
| | - Patrick O. Brown
- Department of Biochemistry, Stanford University School of Medicine, Stanford, California, United States of America
- Howard Hughes Medical Institute, Stanford University School of Medicine, Stanford, California, United States of America
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Alexandrov A, Colognori D, Steitz JA. Human eIF4AIII interacts with an eIF4G-like partner, NOM1, revealing an evolutionarily conserved function outside the exon junction complex. Genes Dev 2011; 25:1078-90. [PMID: 21576267 DOI: 10.1101/gad.2045411] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Despite the lack of an exon junction complex (EJC), Saccharomyces cerevisiae contains Fal1p, a DEAD-box helicase highly homologous to eIF4AIII. We show that yeast Fal1p is functionally orthologous to human eIF4AIII, since expression of human eIF4AIII complements both the lethal phenotype and the 18S rRNA biogenesis defect of fal1Δ(null) yeast. We further show that yeast Fal1p interacts genetically with an eIF4G-like protein, Sgd1p: One allele of sgd1 acts as a dominant extragenic suppressor of a mutation in a predicted RNA-binding residue of Fal1p, whereas another synthetically exacerbates the growth defect of this fal1 mutation. Both sgd1 mutations map to a single, short, evolutionarily conserved patch that matches key eIF4A-interacting residues of eIF4G when superimposed on the X-ray structure of the eIF4A/eIF4G complex. We demonstrate direct physical interactions between yeast Sgd1p and Fal1p, and between their human orthologs (NOM1 and eIF4AIII) in vitro and in vivo, identifying human NOM1 as a missing eIF4G-like interacting partner of eIF4AIII. Knockdown of eIF4AIII and NOM1 in human cells demonstrates that this novel conserved eIF4A/eIF4G-like complex acts in pre-rRNA processing, adding to the established functions of eIF4A/eIF4G in translation initiation and of eIF4AIII as the core component of the EJC.
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Affiliation(s)
- Andrei Alexandrov
- Department of Molecular Biophysics and Biochemistry, Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, Connecticut 06536, USA
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Role of the osmotic stress regulatory pathway in morphogenesis and secondary metabolism in filamentous fungi. Toxins (Basel) 2010; 2:367-81. [PMID: 22069590 PMCID: PMC3153207 DOI: 10.3390/toxins2040367] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2010] [Revised: 03/16/2010] [Accepted: 03/17/2010] [Indexed: 01/06/2023] Open
Abstract
Environmental stimuli trigger an adaptative cellular response to optimize the probability of survival and proliferation. In eukaryotic organisms from mammals to fungi osmotic stress, mainly through the action of the high osmolarity glycerol (HOG) pathway, leads to a response necessary for adapting and surviving hyperosmotic environments. In this review we show that the osmoadaptative response is conserved but not identical in different fungi. The osmoadaptative response system is also intimately linked to morphogenesis in filamentous fungi, including mycotoxin producers. Previous studies indicate that the response to osmotic stress is also coupled to the biosynthesis of natural products, including mycotoxins.
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Master and commander in fungal pathogens: the two-component system and the HOG signaling pathway. EUKARYOTIC CELL 2008; 7:2017-36. [PMID: 18952900 DOI: 10.1128/ec.00323-08] [Citation(s) in RCA: 122] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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12
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Marques JM, Rodrigues RJ, de Magalhães-Sant'ana AC, Gonçalves T. Saccharomyces cerevisiae Hog1 protein phosphorylation upon exposure to bacterial endotoxin. J Biol Chem 2006; 281:24687-94. [PMID: 16790423 DOI: 10.1074/jbc.m603753200] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The yeast Hog1 protein is both functionally and structurally similar to the mammalian p38, belonging to the same family of mitogen-activated protein (MAP) kinases and responding to extracellular changes in osmolarity. Since p38 mediates lipopolysaccharide (LPS) effects in mammalian cells, we now tested the responsiveness of Hog1 upon exposure of the yeast Saccharomyces cerevisiae to bacterial LPS. In the presence of Escherichia coli LPS (100 ng/ml) and an endotoxically active, hexaacylated, synthetic lipid A (compound 506; 100 ng/ml), Hog1 becomes phosphorylated with a maximum of phosphorylation between 3 and 6 h, whereas a tetraacylated, inactive form of lipid A (compound 406) did not cause any modification in the phosphorylation state of Hog1. A triple labeling immunocytochemical study showed that phosphorylated Hog1 translocates into the nucleus after a 90-min incubation and becomes sparsely located in the cytoplasm. The translocation of the phospho-Hog1 is preceded by an increased expression of the HOG1 gene and concomitant with the expression of the Hog1 target gene, GPD1. We also observed that cells unable to synthesize Hog1 do not resist LPS as efficiently as wild-type cells. We conclude that the yeast S. cerevisiae is able to respond to the presence of Gram-negative bacteria endotoxin and that Hog1 is involved in this response.
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Affiliation(s)
- Joana M Marques
- Centre for Neuroscience and Cell Biology of Coimbra and Institutes of Microbiology and Biochemistry, Faculty of Medicine, University of Coimbra, 3004-504 Coimbra, Portugal
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Simmons HM, Ruis BL, Kapoor M, Hudacek AW, Conklin KF. Identification of NOM1, a nucleolar, eIF4A binding protein encoded within the chromosome 7q36 breakpoint region targeted in cases of pediatric acute myeloid leukemia. Gene 2005; 347:137-45. [PMID: 15715967 DOI: 10.1016/j.gene.2004.12.027] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2004] [Revised: 12/02/2004] [Accepted: 12/15/2004] [Indexed: 11/19/2022]
Abstract
Proteins that contain the recently described MIF4G and/or MA3 domains function in translation, cell growth, proliferation, transformation, and apoptosis. Examples of MIF4G/MA3 containing proteins and their functions include eIF4G, which serves as a scaffold for assembly of factors required for translation initiation, programmed cell death protein 4 (Pdcd4) that inhibits translation and functions as a tumor suppressor, and NMD2, which is essential for nonsense-mediated mRNA decay. MIF4G and MA3 domains serve as binding sites for one or more isoforms of the eIF4A family of ATP-dependent DEAD-box RNA helicases that are required for translation and for nonsense-mediated decay. In this report, we describe the characterization of a novel MIF4G/MA3 family member called NOM1 (nucleolar protein with MIF4G domain 1) that was identified at the chromosome 7q36 breakpoint involved in 7;12 translocations associated with certain acute leukemias of childhood. NOM1, which includes a previously described EST called c7orf3, encodes a ubiquitously expressed transcript composed of 11 exons and an approximately 3 kb 3' UTR that contains several Alu repeats. The predicted NOM1 protein contains one MIF4G domain and one MA3 domain and, consistent with data obtained with other MIF4G/MA3 proteins, interacts with members of the eIF4A family of helicases. Database searches reveal that NOM1 homologs exist in several organisms and that at least two of these are essential genes. Finally, like its Saccharomyces cerevisiae homolog Sgd1p, NOM1 localizes predominantly to the nucleolus. These data demonstrate that NOM1 is a new member of the MIF4G/MA3 family of proteins and suggest that it may provide an essential function in metazoans.
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MESH Headings
- Alu Elements/genetics
- Alu Elements/physiology
- Apoptosis/genetics
- Apoptosis/physiology
- Cell Nucleus/metabolism
- Cell Proliferation
- Cell Transformation, Neoplastic/genetics
- Cell Transformation, Neoplastic/metabolism
- Chromosome Breakage/genetics
- Chromosomes, Human, Pair 7/genetics
- Codon, Nonsense/genetics
- Codon, Nonsense/metabolism
- Eukaryotic Initiation Factor-4A/genetics
- Eukaryotic Initiation Factor-4A/metabolism
- Exons/genetics
- Exons/physiology
- Gene Expression Regulation, Leukemic/genetics
- Gene Expression Regulation, Leukemic/physiology
- Humans
- Leukemia, Myeloid, Acute/genetics
- Leukemia, Myeloid, Acute/metabolism
- Nuclear Proteins/genetics
- Nuclear Proteins/metabolism
- Protein Binding/genetics
- Protein Binding/physiology
- RNA Stability/genetics
- RNA Stability/physiology
- RNA-Binding Proteins/genetics
- RNA-Binding Proteins/metabolism
- Transcription, Genetic/genetics
- Transcription, Genetic/physiology
- Translocation, Genetic/genetics
- Translocation, Genetic/physiology
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Affiliation(s)
- Heidi M Simmons
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA
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DeLillo N, Romero C, Lin H, Vancura A. Genetic evidence for a role of phospholipase C at the budding yeast kinetochore. Mol Genet Genomics 2003; 269:261-70. [PMID: 12756538 DOI: 10.1007/s00438-003-0832-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2002] [Accepted: 02/12/2003] [Indexed: 10/25/2022]
Abstract
Chromosome segregation during mitosis requires kinetochores, specialized organelles that mediate chromosome attachment to spindle microtubules. We have shown previously that in budding yeast, Plc1p (phosphoinositide-specific phospholipase C) localizes to centromeric loci, associates with the kinetochore proteins Ndc10p and Cep3p, and affects the function of kinetochores. Deletion of PLC1 results in nocodazole sensitivity, mitotic delay, and a higher frequency of chromosome loss. We report here that despite the nocodazole sensitivity of plc1Delta cells, Plc1p is not required for the spindle checkpoint. However, plc1Delta cells require a functional BUB1/BUB3-dependent spindle checkpoint for viability. PLC1 displays strong genetic interactions with genes encoding components of the inner kinetochore, including NDC10, SKP1, MIF2, CEP1, CEP3, and CTF13. Furthermore, plc1Delta cells display alterations in chromatin structure in the core centromere. Chromatin immunoprecipitation experiments indicate that Plc1p localizes to centromeric loci independently of microtubules, and accumulates at the centromeres during G(2)/M stage of cell cycle. These results are consistent with the view that Plc1p affects kinetochore function, possibly by modulating the structure of centromeric chromatin.
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Affiliation(s)
- N DeLillo
- Department of Biological Sciences, St. John's University, 8000 Utopia Parkway, Jamaicam New York, NY 11439, USA
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Abstract
The ability to adapt to altered availability of free water is a fundamental property of living cells. The principles underlying osmoadaptation are well conserved. The yeast Saccharomyces cerevisiae is an excellent model system with which to study the molecular biology and physiology of osmoadaptation. Upon a shift to high osmolarity, yeast cells rapidly stimulate a mitogen-activated protein (MAP) kinase cascade, the high-osmolarity glycerol (HOG) pathway, which orchestrates part of the transcriptional response. The dynamic operation of the HOG pathway has been well studied, and similar osmosensing pathways exist in other eukaryotes. Protein kinase A, which seems to mediate a response to diverse stress conditions, is also involved in the transcriptional response program. Expression changes after a shift to high osmolarity aim at adjusting metabolism and the production of cellular protectants. Accumulation of the osmolyte glycerol, which is also controlled by altering transmembrane glycerol transport, is of central importance. Upon a shift from high to low osmolarity, yeast cells stimulate a different MAP kinase cascade, the cell integrity pathway. The transcriptional program upon hypo-osmotic shock seems to aim at adjusting cell surface properties. Rapid export of glycerol is an important event in adaptation to low osmolarity. Osmoadaptation, adjustment of cell surface properties, and the control of cell morphogenesis, growth, and proliferation are highly coordinated processes. The Skn7p response regulator may be involved in coordinating these events. An integrated understanding of osmoadaptation requires not only knowledge of the function of many uncharacterized genes but also further insight into the time line of events, their interdependence, their dynamics, and their spatial organization as well as the importance of subtle effects.
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Affiliation(s)
- Stefan Hohmann
- Department of Cell and Molecular Biology/Microbiology, Göteborg University, S-405 30 Göteborg, Sweden.
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