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The role of actin, fimbrin and endocytosis in growth of hyphae in Aspergillus nidulans
"... Filamentous fungi are ideal systems to study the process of polarized growth, as their life cycle is dominated by hyphal growth exclusively at the cell apex. The actin cytoskeleton plays an important role in this growth. Until now, there have been no tools to visualize actin or the actin-binding pro ..."
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Filamentous fungi are ideal systems to study the process of polarized growth, as their life cycle is dominated by hyphal growth exclusively at the cell apex. The actin cytoskeleton plays an important role in this growth. Until now, there have been no tools to visualize actin or the actin-binding protein fimbrin in live cells of a filamentous fungus. We investigated the roles of actin (ActA) and fimbrin (FimA) in hyphal growth in Aspergillus nidulans. We examined the localization of ActA::GFP and FimA::GFP in live cells, and each displayed a similar localization pattern. In actively growing hyphae, cortical ActA::GFP and FimA::GFP patches were highly mobile throughout the hypha and were concentrated near hyphal apices. A patch-depleted zone occupied the apical 0.5 mm of growing hypha. Both FimA::GFP and Act::GFP also localize transiently to septa. Movement and later localization of both was compromised after cytocha-lasin treatment. Disruption of fimA resulted in delayed polarity establishment during conidium germination, abnormal hyphal growth and endocytosis defects in apolar cells. Endocytosis was severely impaired in apolar fimA disruption cells. Our data support a novel apical recycling model which indicates a critical role for actin patch-mediated endocytosis to maintain polarized growth at the apex.
Role of Actin Cytoskeletal Dynamics in Activation of the Cyclic AMP Pathway and HWP1 Gene Expression in Candida albicans � †
, 2007
"... This article cites 78 articles, 51 of which can be accessed free ..."
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This article cites 78 articles, 51 of which can be accessed free
CONTENT ALERTS
, 2009
"... This article cites 37 articles, 20 of which can be accessed free ..."
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, 2015
"... d The activity of ADF/cofilin depends on actin network architecture d Aip1 rapidly and completely disassembles actin networks marked by ADF/cofilin d 23 ADF/cofilins create mechanical stress and sever individual actin filaments d Aip1 stochastically disassembles filaments decorated with ..."
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d The activity of ADF/cofilin depends on actin network architecture d Aip1 rapidly and completely disassembles actin networks marked by ADF/cofilin d 23 ADF/cofilins create mechanical stress and sever individual actin filaments d Aip1 stochastically disassembles filaments decorated with
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"... rC mins are autoinhibited by association of their N- and C-terminalvents both formin nucleation and processive barbed end elongation and decreases formin’s affinity for the barbed end. Furthermore, low micromolar concen-trations of SMIFH2 disrupt formin-dependent, but not Arp2/3 complex-dependent, a ..."
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rC mins are autoinhibited by association of their N- and C-terminalvents both formin nucleation and processive barbed end elongation and decreases formin’s affinity for the barbed end. Furthermore, low micromolar concen-trations of SMIFH2 disrupt formin-dependent, but not Arp2/3 complex-dependent, actin cytoskeletal structures in fission yeast and mammalian NIH 3T3 fibroblasts.
Actin-Filament Stochastic Mediated by ADF/Cofilin
"... aments by ADF/cofilin is the key mechanism modulating treadmilling comprises the addition of actin monomers the prominent and frequent shortening events. The net effect of continuous actin polymerization, driven by a processive formin that uses profilin-actin, and of at filament barbed ends and the ..."
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aments by ADF/cofilin is the key mechanism modulating treadmilling comprises the addition of actin monomers the prominent and frequent shortening events. The net effect of continuous actin polymerization, driven by a processive formin that uses profilin-actin, and of at filament barbed ends and the accompanying depoly-merization of actin subunits at filament pointed ends (rate of 0.27 s21 [8]). This is two orders of magnitude too slow for it to be compatible with cell locomotion [9]. Biomimetic systems that reconstitute actin-based motility in vitro are a valuable tool for identifying the min-imum set of actin-binding proteins required for generat-
Actin Cable Function and Regulation in the Budding Yeast,
"... In the following chapters, I describe factors underlying actin cable dynamics and assembly in the budding yeast, S. cerevisiae. First, I examined the role of type II myosin and a tropomyosin isoform in retrograde actin flow (Chapter II). In yeast and other cell types, actin undergoes retrograde or c ..."
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In the following chapters, I describe factors underlying actin cable dynamics and assembly in the budding yeast, S. cerevisiae. First, I examined the role of type II myosin and a tropomyosin isoform in retrograde actin flow (Chapter II). In yeast and other cell types, actin undergoes retrograde or centripetal movement from the cell cortex towards the interior of the cell. Retrograde actin flow drives intracellular and cellular movement. Previous work in the Pon laboratory showed that actin cables undergo retrograde flow, which occurs, in part, from the force generated from actin polymerization and assembly at the elongating filament end. First, we find that the type II myosin, Myo1p, facilitates retrograde flow. We found that the rate of retrograde actin cable flow is reduced by 1) deletion of Myo1p, 2) displacement of Myo1p from the bud neck, or 3) a conditional mutation that inhibits Myo1p motor activity. These findings indicate that myosin motor activity provides the pulling force to drive movement of elongating actin cables from their site of assembly in the bud tip toward the mother cell. Additional work found that a tropomyosin isoform, Tpm2p, negatively regulates retrograde flow through inhibition of type II myosin binding to F-actin within actin cables. Since type II myosins and tropomyosins have a similar function in retrograde actin flow in animals cells, these findings provide the first evidence that yeast can be used as a model system to study this fundamental, conserved mechanism for actin dynamics.
THESE DE DOCTORAT DE L’UNIVERSITE JOSEPH FOURIER GRENOBLE – ECOLE DOCTORALE DE PHYSIQUE – Spécialité: Physique des Sciences du Vivant.
"... Dynamique des filaments d’actine De la molécule individuelle à la formation de structures organisées Soutenue le Vendredi 06 Juillet 2007 devant le jury composé de: ..."
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Dynamique des filaments d’actine De la molécule individuelle à la formation de structures organisées Soutenue le Vendredi 06 Juillet 2007 devant le jury composé de:
The Dual Function of the Chlamydia pneumoniae Cpn0572 Protein in Modulating the Host Actin
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"... ti ep l s n y, H 7; a ne 1 1. Introduction defects in late mitosis. Best studied are two homologous (D’Aquino et al., 2005). Further studies showed that Kin4 is not a component of the spindle alignment pathway itself but indeed is a component of the MEN. Deletion of KIN4 did not cause any discernibl ..."
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ti ep l s n y, H 7; a ne 1 1. Introduction defects in late mitosis. Best studied are two homologous (D’Aquino et al., 2005). Further studies showed that Kin4 is not a component of the spindle alignment pathway itself but indeed is a component of the MEN. Deletion of KIN4 did not cause any discernible phenotype under nor-
