Regulation of Distinct Septin Rings in a Single Cell by Elm1p and Gin4p Kinases

DeMay, Bradley S.; Meseroll, Rebecca A.; Occhipinti, Patricia; Gladfelter, Amy S.

doi:10.1091/mbc.e08-12-1169

Cited by 72 publications

(120 citation statements)

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“…This is somewhat similar to the case in S. pombe, where a mutant in Spn4, the AspC ortholog, shows delayed cytokinesis, a more severe effect than loss of Spn3 (1). These differences in septin defects are consistent with recent literature showing that though different septins interact for proper function, septin dynamics within a complex can vary (5).…”

Section: Discussionsupporting

confidence: 91%

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Septins AspA and AspC Are Important for Normal Development and Limit the Emergence of New Growth Foci in the Multicellular Fungus Aspergillus nidulans

et al. 2010

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Septins are cytoskeletal proteins found in fungi, animals, and microsporidia, where they form multiseptin complexes that act as scaffolds recruiting and organizing other proteins to ensure normal cell division and development. Here we characterize the septins AspA and AspC in the multicellular, filamentous fungus Aspergillus nidulans. Mutants with deletions of aspA, aspC, or both aspA and aspC show early and increased germ tube and branch emergence, abnormal septation, and disorganized conidiophores. Strains in which the native aspA has been replaced with a single copy of aspA-GFP driven by the native septin promoter or in which aspC has been replaced with a single copy of aspC-GFP driven by the native promoter show wild-type phenotypes. AspA-GFP and AspC-GFP show identical localization patterns as discrete spots or bars in dormant and expanding conidia, as rings at forming septa and at the bases of emerging germ tubes and branches, and as punctate spots and filaments in the cytoplasm and at the cell cortex. In conidiophores, AspA-GFP and AspC-GFP localize as diffuse bands or rings at the bases of emerging layers and conidial chains and as discrete spots or bars in newly formed conidia. AspA-GFP forms abnormal structures in ⌬aspC strains while AspC-GFP does not localize in ⌬aspA strains. Our results suggest that AspA and AspC interact with each other and are important for normal development, especially for preventing the inappropriate emergence of germ tubes and branches. This is the first report of a septin limiting the emergence of new growth foci in any organism.

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Section: Discussionsupporting

confidence: 91%

“…In A. gossypii septins localize as discrete filamentous bars at septation sites, at tips of hyphae, and at the bases of emerging branches. A. gossypii septins are not essential, though they have been shown to be involved in mitosis, sporulation, hyphal morphogenesis, and septum formation (5,9).…”

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confidence: 99%

Septins AspA and AspC Are Important for Normal Development and Limit the Emergence of New Growth Foci in the Multicellular Fungus Aspergillus nidulans

et al. 2010

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“…In C. albicans Cdc10 septin filaments were observed during the final stage of chlamydospore morphogenesis (42), and Cdc3 and Cdc10 filaments were observed in a small percentage of C. neoformans dikaryotic hyphae (36). In A. gossypii, a series of short bars has been observed to form the mature septin ring (15). In U. maydis the Cdc10 filaments extend from pole to pole in the budding stage and in A. fumigatus AspD and AspE septins form visible filaments (1,32).…”

Section: Discussionmentioning

confidence: 99%

The Septin AspB in Aspergillus nidulans Forms Bars and Filaments and Plays Roles in Growth Emergence and Conidiation

2012

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In yeast, septins form rings at the mother-bud neck and function as diffusion barriers. In animals, septins form filaments that can colocalize with other cytoskeletal elements. In the filamentous fungus Aspergillus nidulans there are five septin genes, aspA (an ortholog of Saccharomyces cerevisiae CDC11), aspB (an ortholog of S. cerevisiae CDC3), aspC (an ortholog of S. cerevisiae CDC12), aspD (an ortholog of S. cerevisiae CDC10), and aspE (found only in filamentous fungi). The aspB gene was previously reported to be the most highly expressed Aspergillus nidulans septin and to be essential. Using improved gene targeting techniques, we found that deletion of aspB is not lethal but results in delayed septation, increased emergence of germ tubes and branches, and greatly reduced conidiation. We also found that AspB-green fluorescent protein (GFP) localizes as rings and collars at septa, branches, and emerging layers of the conidiophore and as bars and filaments in conidia and hyphae. Bars are found in dormant and isotropically expanding conidia and in subapical nongrowing regions of hyphae and display fast movements. Filaments form as the germ tube emerges, localize to hyphal and branch tips, and display slower movements. All visible AspB-GFP structures are retained in ⌬aspD and lost in ⌬aspA and ⌬aspC strains. Interestingly, in the ⌬aspE mutant, AspB-GFP rings, bars, and filaments are visible in early growth, but AspB-GFP rods and filaments disappear after septum formation. AspE orthologs are only found in filamentous fungi, suggesting that this class of septins might be required for stability of septin bars and filaments in highly polar cells. Septins are evolutionarily conserved GTP binding proteins that form complexes and are increasingly viewed as cytoskeletal elements (62). Septins are found in all eukaryotes except higher plants (20,52) and are involved in a variety of cellular processes including cytokinesis, vesicle trafficking, cytoskeleton organization, polarity, and formation of diffusion barriers (35,39,44,53,62). Perhaps, not surprisingly given their roles in such critical processes, septin defects have been associated with many human diseases (29).The septins were first discovered in the budding yeast Saccharomyces cerevisiae as temperature-sensitive cell cycle mutants defective in cytokinesis (31, 41). Early in the yeast cell cycle, septins localize as a cap at the future site of bud emergence. As the bud emerges, septins localize first as a ring at the mother/bud neck and later as an hourglass structure as the bud develops (25,26,37). At cytokinesis, the hourglass structure converts into two rings. Septins at the neck form diffusion barriers that keep the cellular machinery necessary for growth and cytokinesis properly localized (16,18,22,49,50,60). In addition, septins are part of the morphogenesis checkpoint that coordinates nuclear division with bud formation (37).In S. cerevisiae septins organize into hetero-oligomeric octamers that associate end to end to form nonpolar filaments (6). Electron ...

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“…In S. cerevisiae, septins form scaffolds that are essential for normal polarized growth, septation, and cytokinesis (Oh and Bi 2011). In filamentous fungi, septins are needed for normal septum formation and appear to delimit growth sites (DeMay et al 2009;Lindsey et al 2010;Ryder et al 2013). For example, the absence of septins in A. nidulans leads to the simultaneous emergence of multiple germ tubes and hyperbranching.…”

Section: The Cytoskeletonmentioning

confidence: 99%

Fungal Morphogenesis

Lin

Alspaugh

Liu

et al. 2014

Cold Spring Harbor Perspectives in Medicine

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Morphogenesis in fungi is often induced by extracellular factors and executed by fungal genetic factors. Cell surface changes and alterations of the microenvironment often accompany morphogenetic changes in fungi. In this review, we will first discuss the general traits of yeast and hyphal morphotypes and how morphogenesis affects development and adaptation by fungi to their native niches, including host niches. Then we will focus on the molecular machinery responsible for the two most fundamental growth forms, yeast and hyphae. Last, we will describe how fungi incorporate exogenous environmental and host signals together with genetic factors to determine their morphotype and how morphogenesis, in turn, shapes the fungal microenvironment. PROPERTIES OF MORPHOGENESIS IN FUNGAL CELLS

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Regulation of Distinct Septin Rings in a Single Cell by Elm1p and Gin4p Kinases

Cited by 72 publications

References 50 publications

Septins AspA and AspC Are Important for Normal Development and Limit the Emergence of New Growth Foci in the Multicellular Fungus Aspergillus nidulans

Septins AspA and AspC Are Important for Normal Development and Limit the Emergence of New Growth Foci in the Multicellular Fungus Aspergillus nidulans

The Septin AspB in Aspergillus nidulans Forms Bars and Filaments and Plays Roles in Growth Emergence and Conidiation

Fungal Morphogenesis

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