scholarly journals Identification and Characterization of LFD-2, a Predicted Fringe Protein Required for Membrane Integrity during Cell Fusion in Neurospora crassa

2015 ◽  
Vol 14 (3) ◽  
pp. 265-277 ◽  
Author(s):  
Javier Palma-Guerrero ◽  
Jiuhai Zhao ◽  
A. Pedro Gonçalves ◽  
Trevor L. Starr ◽  
N. Louise Glass
Keyword(s):  
Neurospora Crassa ◽  
Somatic Cell ◽  
Cell Fusion ◽  
Cell Lysis ◽  
Extracellular Calcium ◽  
Data Set ◽  
Content Type ◽  
Calcium Dependent ◽  
Somatic Cell Fusion ◽  
Dependent Cell

ABSTRACTThe molecular mechanisms of membrane merger during somatic cell fusion in eukaryotic species are poorly understood. In the filamentous fungusNeurospora crassa, somatic cell fusion occurs between genetically identical germinated asexual spores (germlings) and between hyphae to form the interconnected network characteristic of a filamentous fungal colony. InN. crassa, two proteins have been identified to function at the step of membrane fusion during somatic cell fusion: PRM1 and LFD-1. The absence of either one of these two proteins results in an increase of germling pairs arrested during cell fusion with tightly appressed plasma membranes and an increase in the frequency of cell lysis of adhered germlings. The level of cell lysis in ΔPrm1or Δlfd-1germlings is dependent on the extracellular calcium concentration. An available transcriptional profile data set was used to identify genes encoding predicted transmembrane proteins that showed reduced expression levels in germlings cultured in the absence of extracellular calcium. From these analyses, we identified a mutant (lfd-2, forlatefusiondefect-2) that showed a calcium-dependent cell lysis phenotype.lfd-2encodes a protein with a Fringe domain and showed endoplasmic reticulum and Golgi membrane localization. The deletion of an additional gene predicted to encode a low-affinity calcium transporter,fig1, also resulted in a strain that showed a calcium-dependent cell lysis phenotype. Genetic analyses showed that LFD-2 and FIG1 likely function in separate pathways to regulate aspects of membrane merger and repair during cell fusion.

scholarly journals The Predicted Mannosyltransferase GT69-2 Antagonizes RFW-1 To Regulate Cell Fusion in Neurospora crassa

mBio ◽  
2021 ◽  
Vol 12 (2) ◽  
Author(s):  
Yang Li ◽  
Jens Heller ◽  
A. Pedro Gonçalves ◽  
N. Louise Glass
Keyword(s):  
Cell Wall ◽  
Neurospora Crassa ◽  
Somatic Cell ◽  
Filamentous Fungi ◽  
Cell Fusion ◽  
Wild Type ◽  
Content Type ◽  
Asexual Sporulation ◽  
Somatic Cell Fusion ◽  
Cell Wall Remodeling

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.

scholarly journals The ham-2 Locus, Encoding a Putative Transmembrane Protein, Is Required for Hyphal Fusion in Neurospora crassa

Genetics ◽  
2002 ◽  
Vol 160 (1) ◽  
pp. 169-180
Author(s):  
Qijun Xiang ◽  
Carolyn Rasmussen ◽  
N Louise Glass
Keyword(s):  
Neurospora Crassa ◽  
Somatic Cell ◽  
Molecular Mechanism ◽  
Cell Fusion ◽  
Deletion Mutant ◽  
Transmembrane Protein ◽  
Wild Type ◽  
Vegetative Incompatibility ◽  
Hyphal Fusion ◽  
Aerial Hyphae

Abstract Somatic cell fusion is common during organogenesis in multicellular eukaryotes, although the molecular mechanism of cell fusion is poorly understood. In filamentous fungi, somatic cell fusion occurs during vegetative growth. Filamentous fungi grow as multinucleate hyphal tubes that undergo frequent hyphal fusion (anastomosis) during colony expansion, resulting in the formation of a hyphal network. The molecular mechanism of the hyphal fusion process and the role of networked hyphae in the growth and development of these organisms are unexplored questions. We use the filamentous fungus Neurospora crassa as a model to study the molecular mechanism of hyphal fusion. In this study, we identified a deletion mutant that was restricted in its ability to undergo both self-hyphal fusion and fusion with a different individual to form a heterokaryon. This deletion mutant displayed pleiotropic defects, including shortened aerial hyphae, altered conidiation pattern, female sterility, slow growth rate, lack of hyphal fusion, and suppression of vegetative incompatibility. Complementation with a single open reading frame (ORF) within the deletion region in this mutant restored near wild-type growth rates, female fertility, aerial hyphae formation, and hyphal fusion, but not vegetative incompatibility and wild-type conidiation pattern. This ORF, which we named ham-2 (for hyphal anastomosis), encodes a putative transmembrane protein that is highly conserved, but of unknown function among eukaryotes.

Acquisition of Metastatic Properties via Somatic Cell Fusion: Implications for Tumor Progression in Vivo

1986 ◽  
pp. 41-55 ◽  
Author(s):  
Patrick De Baetselier ◽  
Ed Roos ◽  
Hendrik Verschueren ◽  
Steven Verhaegen ◽  
Daniel Dekegel ◽  
...  
Keyword(s):  
Tumor Progression ◽  
Somatic Cell ◽  
Cell Fusion ◽  
Somatic Cell Fusion

scholarly journals Comparison of reprogramming ability of mouse ES and iPS cells measured by somatic cell fusion

2010 ◽  
Vol 54 (11-12) ◽  
pp. 1723-1728 ◽  
Author(s):  
Huseyin Sumer ◽  
Craig Nicholls ◽  
Jun Liu ◽  
Pollyanna A. Tat ◽  
Jun-Ping Liu ◽  
...  
Keyword(s):  
Somatic Cell ◽  
Cell Fusion ◽  
Ips Cells ◽  
Somatic Cell Fusion

Reconstitution of TGF-β Sensitivity in the VACO-411 Human Colon Carcinoma Line by Somatic Cell Fusion with MCF-7

2003 ◽  
Vol 10 (2) ◽  
pp. 253-259 ◽  
Author(s):  
June L. Traicoff ◽  
Sumudra Periyasamy ◽  
Michael G. Brattain ◽  
William Grady ◽  
Graham Casey
Keyword(s):  
Somatic Cell ◽  
Cell Fusion ◽  
Colon Carcinoma ◽  
Human Colon ◽  
Tgf Beta ◽  
Human Colon Carcinoma ◽  
Somatic Cell Fusion ◽  
Mcf 7

scholarly journals Calcineurin Activity Is Required for the Initiation of Skeletal Muscle Differentiation

2000 ◽  
Vol 149 (3) ◽  
pp. 657-666 ◽  
Author(s):  
Bret B. Friday ◽  
Valerie Horsley ◽  
Grace K. Pavlath
Keyword(s):  
Skeletal Muscle ◽  
Cell Fusion ◽  
Transcriptional Activation ◽  
Active Form ◽  
Extracellular Calcium ◽  
Molecular Signaling ◽  
Phenotypic Differentiation ◽  
Calcium Dependent ◽  
Sequence Of Events

Differentiation of skeletal muscle myoblasts follows an ordered sequence of events: commitment, cell cycle withdrawal, phenotypic differentiation, and finally cell fusion to form multinucleated myotubes. The molecular signaling pathways that regulate the progression are not well understood. Here we investigate the potential role of calcium and the calcium-dependent phosphatase calcineurin in myogenesis. Commitment, phenotypic differentiation, and cell fusion are identified as distinct calcium-regulated steps, based on the extracellular calcium concentration required for the expression of morphological and biochemical markers specific to each of these stages. Furthermore, differentiation is inhibited at the commitment stage by either treatment with the calcineurin inhibitor cyclosporine A (CSA) or expression of CAIN, a physiological inhibitor of calcineurin. Retroviral-mediated gene transfer of a constitutively active form of calcineurin is able to induce myogenesis only in the presence of extracellular calcium, suggesting that multiple calcium-dependent pathways are required for differentiation. The mechanism by which calcineurin initiates differentiation includes transcriptional activation of myogenin, but does not require the participation of NFAT. We conclude that commitment of skeletal muscle cells to differentiation is calcium and calcineurin-dependent, but NFAT-independent.

scholarly journals Mitochondrial DNA Transmission and Transcription After Somatic Cell Fusion to One or More Cytoplasts

Stem Cells ◽  
2008 ◽  
Vol 26 (3) ◽  
pp. 775-782 ◽  
Author(s):  
Emma J. Bowles ◽  
R. Tayfur Tecirlioglu ◽  
Andrew J. French ◽  
Michael K. Holland ◽  
Justin C. St. John
Keyword(s):  
Mitochondrial Dna ◽  
Somatic Cell ◽  
Cell Fusion ◽  
Somatic Cell Fusion

scholarly journals The Cell Wall Integrity MAPK pathway controls actin cytoskeleton assembly during fungal somatic cell fusion

2020 ◽  
Author(s):  
Antonio Serrano ◽  
Hamzeh H. Hammadeh ◽  
Natalie Schwarz ◽  
Ulrike Brandt ◽  
André Fleißner
Keyword(s):  
Cell Wall ◽  
Actin Cytoskeleton ◽  
Somatic Cell ◽  
Cell Fusion ◽  
Rho Gtpase ◽  
Cell Wall Integrity ◽  
Physical Contact ◽  
Functional Link ◽  
Somatic Cell Fusion ◽  
Gtpase Rac

AbstractSomatic cell fusion is widely studied in the filamentous fungus Neurospora crassa. The interaction of genetically identical germlings is mediated by a signaling mechanism in which the cells take turns in signal-sending and receiving. The switch between these physiological states is represented by the alternating membrane recruitment of the SO protein and the MAPK MAK-2. This dialog-like behavior is observed until the cells establish physical contact, when the cell-wall-integrity MAK-1 is recruited to the contact area to control the final steps of the cell fusion process. This work revealed, for the first-time, an additional MAK-1-function during the tropic growth phase. Specific inhibition of MAK-1 during tropic-growth resulted in disassembly of the actin-aster, and mislocalization of SO and MAK-2. Similar defects were observed after the inhibition of the Rho-GTPase RAC-1, suggesting a functional link between them, being MAK-1 upstream of RAC-1. In contrast, after inhibition of MAK-2, the actin-aster stayed intact, however, its subcellular localization became instable within the cell-membrane. Together these observations led to a new working model, in which MAK-1 promotes the formation and stability of the actin-aster, while MAK-2 controls its positionning and cell growth directionality.Summary statementThe CWI MAPK MAK-1 pathway controls actin cytoskeleton assembly at the cell tips through activation of the Rho-GTPase RAC-1 exclusively on somatic cell fusion.

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