Localization of RHO-4 Indicates Differential Regulation of Conidial versus Vegetative Septation in the Filamentous Fungus
            <i>Neurospora crassa</i>

Rasmussen, Carolyn G.; Glass, N. Louise

doi:10.1128/ec.00050-07

Cited by 35 publications

(46 citation statements)

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“…For example, genes encoding Rho GTPases (rho-2, NCU08683; rho-4, NCU03407) and a component of the Arp2/3 complex (sop2, NCU02781) showed maximal expression at the colony periphery in both N. crassa and A. niger. In N. crassa, mutations in rho-4 result in strains that lack septa, show slow growth, and have altered microtubule dynamics (52)(53)(54). Homologs of these proteins in animal cells are involved in the establishment of cell polarity and migration (43), and in plant cells, in proper polar cell expansion (3,25,81).…”

Section: Resultsmentioning

confidence: 99%

Dissecting Colony Development ofNeurospora crassaUsing mRNA Profiling and Comparative Genomics Approaches

Kasuga

Glass

2008

Eukaryot Cell

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Colony development, which includes hyphal extension, branching, anastomosis, and asexual sporulation, is a fundamental aspect of the life cycle of filamentous fungi; genetic mechanisms underlying these phenomena are poorly understood. We conducted transcriptional profiling during colony development of the model filamentous fungus Neurospora crassa, using 70-mer oligonucleotide microarrays. Relative mRNA expression levels were determined for six sections of defined age excised from a 27-h-old N. crassa colony. Functional category analysis showed that the expression of genes involved in cell membrane biosynthesis, polar growth, and cellular signaling was enriched at the periphery of the colony. The relative expression of genes involved in protein synthesis and energy production was enriched in the middle section of the colony, while sections of the colony undergoing asexual development (conidiogenesis) were enriched in expression of genes involved in protein/peptide degradation and unclassified proteins. A cross-examination of the N. crassa data set with a published data set of Aspergillus niger revealed shared patterns in the spatiotemporal regulation of gene orthologs during colony development. At present, less than 50% of genes in N. crassa have functional annotation, which imposes the chief limitation on data analysis. Using an evolutionary approach, we observed that the expression of phylogenetically conserved groups of genes was enriched in the middle section of an N. crassa colony whereas expression of genes unique to euascomycete species and of N. crassa orphan genes was enriched at the colony periphery and in the older, conidiating sections of a fungal colony.

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Section: Resultsmentioning

confidence: 99%

Dissecting Colony Development ofNeurospora crassaUsing mRNA Profiling and Comparative Genomics Approaches

Kasuga

Glass

2008

Eukaryot Cell

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“…In a previous study, we have shown that the actin-binding protein BUD-6 becomes recruited to the incipient septation site and, together with the formin BNI-1, remains associated with the leading edge of the constricting actomyosin ring (CAR) (Lichius et al, 2012b). It has been suggested that the CDC-42-RAC-1-CDC-24 module acts as a negative regulator of the septation process, counteracting RHO-1 and RHO-4 which have been positively attributed to septation (Rasmussen and Glass, 2005;Rasmussen and Glass, 2007;JustaSchuch et al, 2010; see also reviews by Seiler and Justa-Schuch, 2010;Mouriño-Pérez and Riquelme, 2013).…”

Section: Discussionmentioning

confidence: 99%

CDC-42 and RAC-1 regulate opposite chemotropisms inNeurospora crassa

Lichius

Goryachev

Fricker

et al. 2014

Journal of Cell Science

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Cell polarization and fusion are crucial developmental processes that occur in response to intracellular and extracellular signals. Asexual spores (conidia) of the mold Neurospora crassa differentiate two types of polarized cell protrusions, germ tubes and conidial anastomosis tubes (CATs), which exhibit negative and positive chemotropism, respectively. We provide the first evidence that shared and separate functions of the Rho-type GTPases CDC-42 and RAC-1 regulate these opposite chemotropisms. We demonstrate that RAC-1 is essential for CAT formation and cell fusion, whereas CDC-42 is necessary and sufficient for normal germ tube development. Cdc42-Rac-interactive-binding (CRIB) reporters were constructed to exclusively label locally activated GTP-bound GTPases. Time course analyses showed that repositioning of these activated GTPase clusters within germ tube and CAT tip apices controls directional growth in the absence of a tip-localized vesicle supply center (Spitzenkö rper). We propose a model in which the local assembly of a plasma-membraneassociated GTPase-PAK-MAPK signaling platform regulates chemoattractant perception and secretion in order to synchronize oscillatory cell-cell communication and directional CAT tip growth.

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“…In contrast, a rho4 mutation in N. crassa leads to a complete loss of septation in vegetative hyphae (44). Rasmussen and Glass further showed that RHO-4 localizes to septa and identified a difference in the regulation of septation during conidiation versus vegetative septation in N. crassa (44,45). Recent studies in N. crassa and A. nidulans indicate that RHO-4 localizes to septa and to the plasma membrane and is involved in signaling pathways that regulate septum formation (19,58).…”

Section: Discussionmentioning

confidence: 99%

A Mutant Defective in Sexual Development Produces Aseptate Ascogonia

et al. 2010

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The transition from the vegetative to the sexual cycle in filamentous ascomycetes is initiated with the formation of ascogonia. Here, we describe a novel type of sterile mutant from Sordaria macrospora with a defect in ascogonial septum formation. This mutant, named pro22, produces only small, defective protoperithecia and carries a point mutation in a gene encoding a protein that is highly conserved throughout eukaryotes. Sequence analyses revealed three putative transmembrane domains and a C-terminal domain of unknown function. Live-cell imaging showed that PRO22 is predominantly localized in the dynamic tubular and vesicular vacuolar network of the peripheral colony region close to growing hyphal tips and in ascogonia; it is absent from the large spherical vacuoles in the vegetative hyphae of the subperipheral region of the colony. This points to a specific role of PRO22 in the tubular and vesicular vacuolar network, and the loss of intercalary septation in ascogonia suggests that PRO22 functions during the initiation of sexual development.The formation of fruiting bodies in filamentous ascomycetes is a process of multicellular differentiation controlled by many developmentally regulated genes. The self-fertile ascomycete Sordaria macrospora represents an excellent model for studying cell differentiation during fungal fruiting body development (reviewed in references 9 and 24).During the life cycle of S. macrospora, a mature haploid ascospore germinates and produces a mycelium composed of multinucleate hyphal compartments. After 2 to 3 days, coiled female reproductive hyphae, called ascogonia, are formed. Each ascogonium develops further into a more-or-less spherical protoperithecium composed of pseudoparenchymatous tissue surrounding the original ascogonium (24, 47). Ascogenous hyphae emerge from the ascogonium inside the protoperithecium. Within the ascogenous hyphae, the nuclei pair up to form the dikaryotic state, even though S. macrospora is selffertile and does not require fertilization with an opposite mating type (11,49). The transition from the spherical protoperithecial to the flask-shaped perithecial stage, is believed to be stimulated by the formation of the dikaryon, although this has not been experimentally verified (24). The dikaryotic state in individual hyphal compartments of the growing ascogenous hyphae is maintained by precisely orchestrated crozier formation from the tip of an ascogenous hypha, fusion of the crozier tip with the penultimate cell of the ascogenous hypha, conjugate mitotic divisions, and highly regulated septation (50, 69). Karyogamy of two nuclei in the penultimate cell results in the formation of a diploid ascus mother cell. The diploid state is very short-lived because the diploid nuclei which are formed immediately undergo meiosis, followed by an extra mitotic division resulting in an ascus containing eight haploid ascospores (11,49). An identical process has been observed in the heterothallic fungus Neurospora crassa, with the exception that cell fusion between opposit...

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Localization of RHO-4 Indicates Differential Regulation of Conidial versus Vegetative Septation in the Filamentous Fungus Neurospora crassa

Cited by 35 publications

References 50 publications

Dissecting Colony Development ofNeurospora crassaUsing mRNA Profiling and Comparative Genomics Approaches

Dissecting Colony Development ofNeurospora crassaUsing mRNA Profiling and Comparative Genomics Approaches

CDC-42 and RAC-1 regulate opposite chemotropisms inNeurospora crassa

A Mutant Defective in Sexual Development Produces Aseptate Ascogonia

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