1
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Li S, Liu Q, Wang E, Wang J. Global quantitative understanding of non-equilibrium cell fate decision-making in response to pheromone. iScience 2023; 26:107885. [PMID: 37766979 PMCID: PMC10520453 DOI: 10.1016/j.isci.2023.107885] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Revised: 08/09/2023] [Accepted: 09/07/2023] [Indexed: 09/29/2023] Open
Abstract
Cell-cycle arrest and polarized growth are commonly used to characterize the response of yeast to pheromone. However, the quantitative decision-making processes underlying time-dependent changes in cell fate remain unclear. In this study, we conducted single-cell level experiments to observe multidimensional responses, uncovering diverse fates of yeast cells. Multiple states are revealed, along with the kinetic switching rates and pathways among them, giving rise to a quantitative landscape of mating response. To quantify the experimentally observed cell fates, we developed a theoretical framework based on non-equilibrium landscape and flux theory. Additionally, we performed stochastic simulations of biochemical reactions to elucidate signal transduction and cell growth. Notably, our experimental findings have provided the first global quantitative evidence of the real-time synchronization between intracellular signaling, physiological growth, and morphological functions. These results validate the proposed underlying mechanism governing the emergence of multiple cell fate states. This study introduces an emerging mechanistic approach to understand non-equilibrium cell fate decision-making in response to pheromone.
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Affiliation(s)
- Sheng Li
- College of Chemistry, Jilin University, Changchun, Jilin 130012, China
- State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin 130022, China
| | - Qiong Liu
- State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin 130022, China
| | - Erkang Wang
- College of Chemistry, Jilin University, Changchun, Jilin 130012, China
- State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin 130022, China
| | - Jin Wang
- Department of Chemistry and of Physics and Astronomy, State University of New York at Stony Brook, Stony Brook, NY 11794-3400, USA
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2
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Medina-Castellanos E, Salgado-Bautista DA, Martínez-Andrade JM, Cadena-Nava RD, Riquelme M. Nanosized extracellular vesicles released by Neurospora crassa hyphae. Fungal Genet Biol 2023; 165:103778. [PMID: 36690295 DOI: 10.1016/j.fgb.2023.103778] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Revised: 01/13/2023] [Accepted: 01/17/2023] [Indexed: 01/22/2023]
Abstract
Extracellular vesicles (EVs) are nanosized structures containing proteins, lipids, and nucleic acids, released by living cells to the surrounding medium. EVs participate in diverse processes, such as intercellular communication, virulence, and disease. In pathogenic fungi, EVs carry enzymes that allow them to invade the host or undergo environmental adaptation successfully. In Neurospora crassa, a non-pathogenic filamentous fungus widely used as a model organism, the vesicle-dependent secretory mechanisms that lead to polarized growth are well studied. In contrast, biosynthesis of EVs in this fungus has been practically unexplored. In the present work, we analyzed N. crassa culture's supernatant for the presence of EVs by dynamic light scattering (DLS), transmission electron microscopy (TEM) and proteomic analysis. We identified spherical membranous structures, with a predominant subpopulation averaging a hydrodynamic diameter (dh) of 68 nm and a particle diameter (dp) of 38 nm. EV samples stained with osmium tetroxide vapors were better resolved than those stained with uranyl acetate. Mass spectrometry analysis identified 252 proteins, including enzymes involved in carbohydrate metabolic processes, oxidative stress response, cell wall organization/remodeling, and circadian clock-regulated proteins. Some of these proteins have been previously reported in exosomes from human cells or in EVs of other fungi. In view of the results, it is suggested a putative role for EVs in cell wall biosynthesis and vegetative development in N. crassa.
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Affiliation(s)
- Elizabeth Medina-Castellanos
- Department of Microbiology, Centro de Investigación Científica y Educación Superior de Ensenada (CICESE), Ensenada, Mexico
| | - Daniel A Salgado-Bautista
- Department of Microbiology, Centro de Investigación Científica y Educación Superior de Ensenada (CICESE), Ensenada, Mexico
| | - Juan M Martínez-Andrade
- Department of Microbiology, Centro de Investigación Científica y Educación Superior de Ensenada (CICESE), Ensenada, Mexico
| | - Ruben Dario Cadena-Nava
- Department of Bionanotechnology, Centro de Nanociencias y Nanotecnología, Universidad Nacional Autónoma de México, Ensenada, Mexico
| | - Meritxell Riquelme
- Department of Microbiology, Centro de Investigación Científica y Educación Superior de Ensenada (CICESE), Ensenada, Mexico.
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3
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Schalamun M, Beier S, Hinterdobler W, Wanko N, Schinnerl J, Brecker L, Engl DE, Schmoll M. MAPkinases regulate secondary metabolism, sexual development and light dependent cellulase regulation in Trichoderma reesei. Sci Rep 2023; 13:1912. [PMID: 36732590 PMCID: PMC9894936 DOI: 10.1038/s41598-023-28938-w] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2022] [Accepted: 01/27/2023] [Indexed: 02/04/2023] Open
Abstract
The filamentous fungus Trichoderma reesei is a prolific producer of plant cell wall degrading enzymes, which are regulated in response to diverse environmental signals for optimal adaptation, but also produces a wide array of secondary metabolites. Available carbon source and light are the strongest cues currently known to impact secreted enzyme levels and an interplay with regulation of secondary metabolism became increasingly obvious in recent years. While cellulase regulation is already known to be modulated by different mitogen activated protein kinase (MAPK) pathways, the relevance of the light signal, which is transmitted by this pathway in other fungi as well, is still unknown in T. reesei as are interconnections to secondary metabolism and chemical communication under mating conditions. Here we show that MAPkinases differentially influence cellulase regulation in light and darkness and that the Hog1 homologue TMK3, but not TMK1 or TMK2 are required for the chemotropic response to glucose in T. reesei. Additionally, MAPkinases regulate production of specific secondary metabolites including trichodimerol and bisorbibutenolid, a bioactive compound with cytostatic effect on cancer cells and deterrent effect on larvae, under conditions facilitating mating, which reflects a defect in chemical communication. Strains lacking either of the MAPkinases become female sterile, indicating the conservation of the role of MAPkinases in sexual fertility also in T. reesei. In summary, our findings substantiate the previously detected interconnection of cellulase regulation with regulation of secondary metabolism as well as the involvement of MAPkinases in light dependent gene regulation of cellulase and secondary metabolite genes in fungi.
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Affiliation(s)
- Miriam Schalamun
- Center for Health and Bioresources, Bioresources Unit, AIT Austrian Institute of Technology GmbH, Konrad Lorenz Strasse 24, 3430, Tulln, Austria
| | - Sabrina Beier
- Center for Health and Bioresources, Bioresources Unit, AIT Austrian Institute of Technology GmbH, Konrad Lorenz Strasse 24, 3430, Tulln, Austria
| | - Wolfgang Hinterdobler
- Center for Health and Bioresources, Bioresources Unit, AIT Austrian Institute of Technology GmbH, Konrad Lorenz Strasse 24, 3430, Tulln, Austria
- MyPilz GmbH, Wienerbergstrasse 55/13-15, 1120, Vienna, Austria
| | - Nicole Wanko
- Center for Health and Bioresources, Bioresources Unit, AIT Austrian Institute of Technology GmbH, Konrad Lorenz Strasse 24, 3430, Tulln, Austria
| | - Johann Schinnerl
- Department of Botany and Biodiversity Research, University of Vienna, Rennweg 14, 1030, Vienna, Austria
| | - Lothar Brecker
- Department of Organic Chemistry, University of Vienna, Währinger Strasse 38, 1090, Vienna, Austria
| | - Dorothea Elisa Engl
- Department of Organic Chemistry, University of Vienna, Währinger Strasse 38, 1090, Vienna, Austria
| | - Monika Schmoll
- Center for Health and Bioresources, Bioresources Unit, AIT Austrian Institute of Technology GmbH, Konrad Lorenz Strasse 24, 3430, Tulln, Austria.
- Division of Terrestrial Ecosystem Research, Department of Microbiology and Ecosystem Science, University of Vienna, Djerassiplatz 1, 1030, Vienna, Austria.
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4
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A dialogue-like cell communication mechanism is conserved in filamentous ascomycete fungi and mediates interspecies interactions. Proc Natl Acad Sci U S A 2022; 119:e2112518119. [PMID: 35286209 PMCID: PMC8944665 DOI: 10.1073/pnas.2112518119] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
This study reveals that a dialogue-like communication mechanism, which mediates cell–cell fusion in filamentous fungi, is a conserved complex trait. It allows the communication and behavioral coordination of cells of distantly related species and mediates their mutual attraction and subsequent physical contact, although interspecies fusion does not occur. Through the activation of this signaling machinery, one species can reprogram the developmental program of the other fungus. These data promote our understanding of microbial communication, illustrate the mechanism of repurposing of existing building blocks in cellular evolution, revive the hypothesis of vegetative fusion as an avenue of horizontal gene transfer in fungi, and establish the idea of developmental reprogramming as a tool for controlling fungi. In many filamentous fungi, germinating spores cooperate by fusing into supracellular structures, which develop into the mycelial colony. In the model fungus Neurospora crassa, this social behavior is mediated by an intriguing mode of communication, in which two fusing cells take turns in signal sending and receiving. Here we show that this dialogue-like cell communication mechanism is highly conserved in distantly related fungal species and mediates interspecies interactions. In mixed populations, cells of N. crassa and the phytopathogenic gray mold Botrytis cinerea coordinate their behavior over a spatial distance and establish physical contact. Subsequent cell–cell fusion is, however, restricted to germlings of the same species, indicating that species specificity of germling fusion has evolved not on the level of the signal/receptor but at subsequent levels of the fusion process. In B. cinerea, fusion and infectious growth are mutually exclusive cellular programs. Remarkably, the presence of N. crassa can reprogram this behavior and induce fusion of the gray mold on plant surfaces, potentially weakening its pathogenic potential. In a third fungal species, the nematode-trapping fungus Arthrobotrys flagrans, the conserved signaling mechanism mediates vegetative fusion within mycelial colonies but has also been repurposed for the formation of nematode-catching traps. In summary, this study identified the cell dialogue mechanism as a conserved complex trait and revealed that even distantly related fungi possess a common molecular language, which promotes cellular contact formation across species borders.
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Abstract
Fungi exhibit an enormous variety of morphologies, including yeast colonies, hyphal mycelia, and elaborate fruiting bodies. This diversity arises through a combination of polar growth, cell division, and cell fusion. Because fungal cells are nonmotile and surrounded by a protective cell wall that is essential for cell integrity, potential fusion partners must grow toward each other until they touch and then degrade the intervening cell walls without impacting cell integrity. Here, we review recent progress on understanding how fungi overcome these challenges. Extracellular chemoattractants, including small peptide pheromones, mediate communication between potential fusion partners, promoting the local activation of core cell polarity regulators to orient polar growth and cell wall degradation. However, in crowded environments, pheromone gradients can be complex and potentially confusing, raising the question of how cells can effectively find their partners. Recent findings suggest that the cell polarity circuit exhibits searching behavior that can respond to pheromone cues through a remarkably flexible and effective strategy called exploratory polarization.
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6
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The Predicted Mannosyltransferase GT69-2 Antagonizes RFW-1 To Regulate Cell Fusion in Neurospora crassa. mBio 2021; 12:mBio.00307-21. [PMID: 33727349 PMCID: PMC8092235 DOI: 10.1128/mbio.00307-21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Filamentous fungi undergo somatic cell fusion to create a syncytial, interconnected hyphal network which confers a fitness benefit during colony establishment. However, barriers to somatic cell fusion between genetically different cells have evolved that reduce invasion by parasites or exploitation by maladapted genetic entities (cheaters). Here, we identified a predicted mannosyltransferase, glycosyltransferase family 69 protein (GT69-2) that was required for somatic cell fusion in Neurospora crassa Cells lacking GT69-2 prematurely ceased chemotropic signaling and failed to complete cell wall dissolution and membrane merger in pairings with wild-type cells or between Δgt69-2 cells (self fusion). However, loss-of-function mutations in the linked regulator of cell fusion and cell wall remodeling-1 (rfw-1) locus suppressed the self-cell-fusion defects of Δgt69-2 cells, although Δgt69-2 Δrfw-1 double mutants still failed to undergo fusion with wild-type cells. Both GT69-2 and RFW-1 localized to the Golgi apparatus. Genetic analyses indicated that RFW-1 negatively regulates cell wall remodeling-dependent processes, including cell wall dissolution during cell fusion, separation of conidia during asexual sporulation, and conidial germination. GT69-2 acts as an antagonizer to relieve or prevent negative functions on cell fusion by RFW-1. In Neurospora species and N. crassa populations, alleles of gt69-2 were highly polymorphic and fell into two discrete haplogroups. In all isolates within haplogroup I, rfw-1 was conserved and linked to gt69-2 All isolates within haplogroup II lacked rfw-1. These data indicated that gt69-2/rfw-1 are under balancing selection and provide new mechanisms regulating cell wall remodeling during cell fusion and conidial separation.IMPORTANCE Cell wall remodeling is a dynamic process that balances cell wall integrity versus cell wall dissolution. In filamentous fungi, cell wall dissolution is required for somatic cell fusion and conidial separation during asexual sporulation. In the filamentous fungus Neurospora crassa, allorecognition checkpoints regulate the cell fusion process between genetically different cells. Our study revealed two linked loci with transspecies polymorphisms and under coevolution, rfw-1 and gt69-2, which form a coordinated system to regulate cell wall remodeling during somatic cell fusion, conidial separation, and asexual spore germination. RFW-1 acts as a negative regulator of these three processes, while GT69-2 functions antagonistically to RFW-1. Our findings provide new insight into the mechanisms involved in regulation of fungal cell wall remodeling during growth and development.
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7
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Weichert M, Herzog S, Robson SA, Brandt R, Priegnitz BE, Brandt U, Schulz S, Fleißner A. Plasma Membrane Fusion Is Specifically Impacted by the Molecular Structure of Membrane Sterols During Vegetative Development of Neurospora crassa. Genetics 2020; 216:1103-1116. [PMID: 33046504 PMCID: PMC7768248 DOI: 10.1534/genetics.120.303623] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Accepted: 10/11/2020] [Indexed: 02/07/2023] Open
Abstract
Cell-to-cell fusion is crucial for the development and propagation of most eukaryotic organisms. Despite this importance, the molecular mechanisms mediating this process are only poorly understood in biological systems. In particular, the step of plasma membrane merger and the contributing proteins and physicochemical factors remain mostly unknown. Earlier studies provided the first evidence of a role of membrane sterols in cell-to-cell fusion. By characterizing different ergosterol biosynthesis mutants of the fungus Neurospora crassa, which accumulate different ergosterol precursors, we show that the structure of the sterol ring system specifically affects plasma membrane merger during the fusion of vegetative spore germlings. Genetic analyses pinpoint this defect to an event prior to engagement of the fusion machinery. Strikingly, this effect is not observed during sexual fusion, suggesting that the specific sterol precursors do not generally block membrane merger, but rather impair subcellular processes exclusively mediating fusion of vegetative cells. At a colony-wide level, the altered structure of the sterol ring system affects a subset of differentiation processes, including vegetative sporulation and steps before and after fertilization during sexual propagation. Together, these observations corroborate the notion that the accumulation of particular sterol precursors has very specific effects on defined cellular processes rather than nonspecifically disturbing membrane functioning. Given the phenotypic similarities of the ergosterol biosynthesis mutants of N. crassa during vegetative fusion and of Saccharomyces cerevisiae cells undergoing mating, our data support the idea that yeast mating is evolutionarily and mechanistically more closely related to vegetative than sexual fusion of filamentous fungi.
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Affiliation(s)
- Martin Weichert
- Institut für Genetik, Technische Universität Braunschweig, 38106 Braunschweig, Germany
| | - Stephanie Herzog
- Institut für Genetik, Technische Universität Braunschweig, 38106 Braunschweig, Germany
| | - Sarah-Anne Robson
- Institut für Genetik, Technische Universität Braunschweig, 38106 Braunschweig, Germany
| | - Raphael Brandt
- Institut für Genetik, Technische Universität Braunschweig, 38106 Braunschweig, Germany
| | - Bert-Ewald Priegnitz
- Institut für Genetik, Technische Universität Braunschweig, 38106 Braunschweig, Germany
| | - Ulrike Brandt
- Institut für Genetik, Technische Universität Braunschweig, 38106 Braunschweig, Germany
| | - Stefan Schulz
- Institut für Organische Chemie, Technische Universität Braunschweig, 38106 Braunschweig, Germany
| | - André Fleißner
- Institut für Genetik, Technische Universität Braunschweig, 38106 Braunschweig, Germany
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8
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Schmidt S, Märker R, Ramšak B, Beier-Rosberger AM, Teichert I, Kück U. Crosstalk Between Pheromone Signaling and NADPH Oxidase Complexes Coordinates Fungal Developmental Processes. Front Microbiol 2020; 11:1722. [PMID: 32849367 PMCID: PMC7401384 DOI: 10.3389/fmicb.2020.01722] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2020] [Accepted: 06/30/2020] [Indexed: 12/13/2022] Open
Abstract
Sexual and asexual development in filamentous ascomycetes is controlled by components of conserved signaling pathways. Here, we investigated the development of mutant strains lacking genes for kinases MAK2, MEK2, and MIK2, as well as the scaffold protein HAM5 of the pheromone response (PR) pathway. All had a defect in fruiting body development and hyphal fusion. Another phenotype was a defect in melanin-dependent ascospore germination. However, this deficiency was observed only in kinase deletion mutants, but not in strains lacking HAM5. Notably, the same developmental phenotypes were previously described for nicotinamide adenine dinucleotide phosphate (NADPH) oxidase 1 (NOX1) mutants, but the germination defect was only seen in NOX2 mutants. These data suggest a molecular link between the pheromone signaling pathway and both NOX complexes. Using data from yeast two-hybrid (Y2H) analysis, we found that the scaffolding protein HAM5 interacts with NOR1, the regulator of NOX1 and NOX2 complexes. This interaction was further confirmed using differently fluorescent-labeled proteins to demonstrate that NOR1 and HAM5 co-localize at cytoplasmic spots and tips of mature hyphae. This observation was supported by phenotypic characterization of single and double mutants. The oxidative stress response and the initiation of fruiting bodies were similar in Δham5Δnor1 and Δham5, but distinctly reduced in Δnor1, indicating that the double deletion leads to a partial suppression of the Δnor1 phenotype. We conclude that the PR and NOX1 complexes are connected by direct interaction between HAM5 and NOR1. In contrast, PR kinases are linked to the NOX2 complex without participation of HAM5.
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Affiliation(s)
| | | | | | | | | | - Ulrich Kück
- Allgemeine und Molekulare Botanik, Ruhr-Universität Bochum, Bochum, Germany
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9
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Lau AYT, Xie Y, Cheung MK, Cheung PCK, Kwan HS. Genome-wide mRNA and miRNA analysis in the early stages of germ tube outgrowth in Coprinopsis cinerea. Fungal Genet Biol 2020; 142:103416. [PMID: 32522620 DOI: 10.1016/j.fgb.2020.103416] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Revised: 05/28/2020] [Accepted: 06/01/2020] [Indexed: 01/28/2023]
Abstract
Coprinopsis cinerea is a model mushroom-forming basidiomycete which produces basidiospores during sexual reproduction. This fungus is widely used to study fruiting body formation and development. Molecular mechanisms controlling its growth from vegetative mycelium to multicellular mature fruiting body have been studied extensively. However, little is known about the underlying biological processes during germ tube outgrowth or the transition from basidiospores to multinucleate hyphae. To better understand sexual spore germination in fungi, here we examined the time-dependent cellular events at resting, germinating and fully germinated basidiospores of C. cinerea by genome-wide transcriptional and post-transcriptional analyses and by carbohydrate composition analysis. Our results revealed a high demand of protein degradation, and biosynthesis of various compounds at the early stage of basidiospore gemination and dynamic changes of carbohydrate metabolism throughout the germination process. Seven microRNA-like RNAs (milRNAs) were identified in the resting basidiospores of C. cinerea, six of which were basidiospore-specific. Glycogen and trehalose were shown to be the carbon sources supporting the initiation of germ tube outgrowth. One basidiospore-specific milRNA, cci-milR-37, was found to be a potential regulator of glycogen metabolic pathways related to vegetative hyphal growth. Our results demonstrated the mRNA and miRNA-mediated regulation on energy production, protein and carbohydrate metabolisms at the early developmental stages of germ tube to form totipotent hyphae. To our knowledge, this is the first study to show the roles of miRNAs in mushroom basidiospore germination and out-growth.
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Affiliation(s)
- Amy Yuet Ting Lau
- School of Life Sciences, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong
| | - Yichun Xie
- School of Life Sciences, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong
| | - Man Kit Cheung
- Department of Surgery, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong
| | - Peter Chi Keung Cheung
- School of Life Sciences, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong; CUHK Shenzhen Research Institute, Shenzhen, China
| | - Hoi Shan Kwan
- School of Life Sciences, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong; HSK GeneTech Limited, Science Park, Shatin, New Territories, Hong Kong; Probiolife Limited, Science Park, Shatin, New Territories, Hong Kong; Mushroom-X Limited, Cheung Sha Wan Plaza, Lai Chi Kok, Kowloon, Hong Kong.
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10
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Gonçalves AP, Chow KM, Cea-Sánchez S, Glass NL. WHI-2 Regulates Intercellular Communication via a MAP Kinase Signaling Complex. Front Microbiol 2020; 10:3162. [PMID: 32038591 PMCID: PMC6987382 DOI: 10.3389/fmicb.2019.03162] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Accepted: 12/31/2019] [Indexed: 01/15/2023] Open
Abstract
The formation of the fungal mycelial network is facilitated by somatic cell fusion of germinating asexual spores (or germlings). Neurospora crassa germlings in close proximity display chemotropic growth that is dependent upon an intracellular network of mitogen-activated protein kinase (MAPK) signaling cascades. Approximately 80 genes involved in intercellular communication and fusion have been identified, including three mutants with similar morphological phenotypes: Δwhi-2, Δcsp-6, and Δamph-1. Here we show that WHI-2 localizes to the cell periphery and regulates endocytosis, mitochondrial organization, sporulation, and cell fusion. WHI-2 was required to transduce signals through a conserved MAPK pathway (NRC-1/MEK-2/MAK-2) and target transcription factors (PP-1/ADV-1). The amph-1 locus encodes a Bin/Amphiphysin/Rvs domain-containing protein and mis-expression of whi-2 compensated for the cell fusion and endocytosis deficiencies of a Δamph-1 mutant. The csp-6 locus encodes a haloacid dehalogenase phosphatase whose activity was essential for cell fusion. Although fusion-deficient with themselves, cells that lacked whi-2, csp-6, or amph-1 showed a low frequency of chemotropic interactions with wild type cells. We hypothesize that WHI-2 could be important for signal perception during chemotropic interactions via a role in endocytosis.
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Affiliation(s)
- A Pedro Gonçalves
- Department of Plant and Microbial Biology, University of California, Berkeley, Berkeley, CA, United States
| | - Karen M Chow
- Department of Plant and Microbial Biology, University of California, Berkeley, Berkeley, CA, United States
| | - Sara Cea-Sánchez
- Departamento de Genética, Universidad de Sevilla, Sevilla, Spain
| | - N Louise Glass
- Department of Plant and Microbial Biology, University of California, Berkeley, Berkeley, CA, United States.,Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA, United States
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11
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Schumann MR, Brandt U, Adis C, Hartung L, Fleißner A. Plasma Membrane Integrity During Cell-Cell Fusion and in Response to Pore-Forming Drugs Is Promoted by the Penta-EF-Hand Protein PEF1 in Neurospora crassa. Genetics 2019; 213:195-211. [PMID: 31270133 PMCID: PMC6727798 DOI: 10.1534/genetics.119.302363] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2019] [Accepted: 06/14/2019] [Indexed: 12/20/2022] Open
Abstract
Plasma membrane damage commonly occurs during cellular growth and development. To counteract these potentially lethal injuries, membrane repair mechanisms have evolved, which promote the integrity of the lipid bilayer. Although the membrane of fungi is the target of important clinical drugs and agricultural fungicides, the molecular mechanisms which mediate membrane repair in these organisms remain elusive. Here we identify the penta-EF-hand protein PEF1 of the genetic model fungus Neurospora crassa as part of a cellular response mechanism against different types of membrane injury. Deletion of the pef1 gene in the wild type and different lysis-prone gene knockout mutants revealed a function of the protein in maintaining cell integrity during cell-cell fusion and in the presence of pore-forming drugs, such as the plant defense compound tomatine. By fluorescence and live-cell imaging we show that green fluorescent protein (GFP)-tagged PEF1 accumulates at the sites of membrane injury in a Ca2+-dependent manner. Site-directed mutagenesis identified Ca2+-binding domains essential for the spatial dynamics and function of the protein. In addition, the subcellular localization of PEF1 revealed that the syncytial fungal colony undergoes compartmentation in response to antifungal treatment. We propose that plasma membrane repair in fungi constitutes an additional line of defense against membrane-disturbing drugs, thereby expanding the current model of fungal drug resistance mechanisms.
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Affiliation(s)
| | - Ulrike Brandt
- Institut für Genetik, Technische Universität Braunschweig, 38106, Germany
| | - Christian Adis
- Institut für Genetik, Technische Universität Braunschweig, 38106, Germany
| | - Lisa Hartung
- Institut für Genetik, Technische Universität Braunschweig, 38106, Germany
| | - André Fleißner
- Institut für Genetik, Technische Universität Braunschweig, 38106, Germany
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12
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Martin SG. Molecular mechanisms of chemotropism and cell fusion in unicellular fungi. J Cell Sci 2019; 132:132/11/jcs230706. [PMID: 31152053 DOI: 10.1242/jcs.230706] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
In all eukaryotic phyla, cell fusion is important for many aspects of life, from sexual reproduction to tissue formation. Fungal cells fuse during mating to form the zygote, and during vegetative growth to connect mycelia. Prior to fusion, cells first detect gradients of pheromonal chemoattractants that are released by their partner and polarize growth in their direction. Upon pairing, cells digest their cell wall at the site of contact and merge their plasma membrane. In this Review, I discuss recent work on the chemotropic response of the yeast models Saccharomyces cerevisiae and Schizosaccharomyces pombe, which has led to a novel model of gradient sensing: the cell builds a motile cortical polarized patch, which acts as site of communication where pheromones are released and sensed. Initial patch dynamics serve to correct its position and align it with the gradient from the partner cell. Furthermore, I highlight the transition from cell wall expansion during growth to cell wall digestion, which is imposed by physical and signaling changes owing to hyperpolarization that is induced by cell proximity. To conclude, I discuss mechanisms of membrane fusion, whose characterization remains a major challenge for the future.
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Affiliation(s)
- Sophie G Martin
- Department of Fundamental Microbiology, University of Lausanne, 1015 Lausanne, Switzerland
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13
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Fischer MS, Glass NL. Communicate and Fuse: How Filamentous Fungi Establish and Maintain an Interconnected Mycelial Network. Front Microbiol 2019; 10:619. [PMID: 31001214 PMCID: PMC6455062 DOI: 10.3389/fmicb.2019.00619] [Citation(s) in RCA: 67] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2018] [Accepted: 03/12/2019] [Indexed: 12/22/2022] Open
Abstract
Cell-to-cell communication and cell fusion are fundamental biological processes across the tree of life. Survival is often dependent upon being able to identify nearby individuals and respond appropriately. Communication between genetically different individuals allows for the identification of potential mating partners, symbionts, prey, or predators. In contrast, communication between genetically similar (or identical) individuals is important for mediating the development of multicellular organisms or for coordinating density-dependent behaviors (i.e., quorum sensing). This review describes the molecular and genetic mechanisms that mediate cell-to-cell communication and cell fusion between cells of Ascomycete filamentous fungi, with a focus on Neurospora crassa. Filamentous fungi exist as a multicellular, multinuclear network of hyphae, and communication-mediated cell fusion is an important aspect of colony development at each stage of the life cycle. Asexual spore germination occurs in a density-dependent manner. Germinated spores (germlings) avoid cells that are genetically different at specific loci, while chemotropically engaging with cells that share identity at these recognition loci. Germlings with genetic identity at recognition loci undergo cell fusion when in close proximity, a fitness attribute that contributes to more rapid colony establishment. Communication and cell fusion also occur between hyphae in a colony, which are important for reinforcing colony architecture and supporting the development of complex structures such as aerial hyphae and sexual reproductive structures. Over 70 genes have been identified in filamentous fungi (primarily N. crassa) that are involved in kind recognition, chemotropic interactions, and cell fusion. While the hypothetical signal(s) and receptor(s) remain to be described, a dynamic molecular signaling network that regulates cell-cell interactions has been revealed, including two conserved MAP-Kinase cascades, a conserved STRIPAK complex, transcription factors, a NOX complex involved in the generation of reactive oxygen species, cell-integrity sensors, actin, components of the secretory pathway, and several other proteins. Together these pathways facilitate the integration of extracellular signals, direct polarized growth, and initiate a transcriptional program that reinforces signaling and prepares cells for downstream processes, such as membrane merger, cell fusion and adaptation to heterokaryon formation.
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Affiliation(s)
- Monika S. Fischer
- Department of Plant and Microbial Biology, University of California, Berkeley, Berkeley CA, United States
| | - N. Louise Glass
- Department of Plant and Microbial Biology, University of California, Berkeley, Berkeley CA, United States
- Environmental Genomics and Systems Biology Division, The Lawrence Berkeley National Laboratory, Berkeley, CA, United States
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Integration of Self and Non-self Recognition Modulates Asexual Cell-to-Cell Communication in Neurospora crassa. Genetics 2019; 211:1255-1267. [PMID: 30718271 DOI: 10.1534/genetics.118.301780] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2018] [Accepted: 01/27/2019] [Indexed: 02/06/2023] Open
Abstract
Cells rarely exist alone, which drives the evolution of diverse mechanisms for identifying and responding appropriately to the presence of other nearby cells. Filamentous fungi depend on somatic cell-to-cell communication and fusion for the development and maintenance of a multicellular, interconnected colony that is characteristic of this group of organisms. The filamentous fungus Neurospora crassa is a model for investigating the mechanisms of somatic cell-to-cell communication and fusion. N. crassa cells chemotropically grow toward genetically similar cells, which ultimately make physical contact and undergo cell fusion. Here, we describe the development of a Pprm1-luciferase reporter system that differentiates whether genes function upstream or downstream of a conserved MAP kinase (MAPK) signaling complex, by using a set of mutants required for communication and cell fusion. The vast majority of these mutants are deficient for self-fusion and for fusion when paired with wild-type cells. However, the Δham-11 mutant is unique in that it fails to undergo self-fusion, but chemotropic interactions and cell fusion are restored in Δham-11 + wild-type interactions. In genetically dissimilar cells, chemotropic interactions are regulated by genetic differences at doc-1 and doc-2, which regulate prefusion non-self recognition; cells with dissimilar doc-1 and doc-2 alleles show greatly reduced cell-fusion frequencies. Here, we show that HAM-11 functions in parallel with the DOC-1 and DOC-2 proteins to regulate the activity of the MAPK signaling complex. Together, our data support a model of integrated self and non-self recognition processes that modulate somatic cell-to-cell communication in N. crassa.
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