scholarly journals Yeast actin cytoskeleton mutants accumulate a new class of Golgi-derived secretary vesicle.

1997 ◽  
Vol 8 (8) ◽  
pp. 1481-1499 ◽  
Author(s):  
J Mulholland ◽  
A Wesp ◽  
H Riezman ◽  
D Botstein
Keyword(s):  
Cell Wall ◽  
Plasma Membrane ◽  
Actin Cytoskeleton ◽  
Biochemical Analysis ◽  
Small Gtpase ◽  
Secretory Vesicles ◽  
Cytoskeleton Organization ◽  
New Class ◽  
Actin Cytoskeleton Organization ◽  
Vectorial Transport

Many yeast actin cytoskeleton mutants accumulate large secretory vesicles and exhibit phenotypes consistent with defects in polarized growth. This, together with actin's polarized organization, has suggested a role for the actin cytoskeleton in the vectorial transport of late secretory vesicles to the plasma membrane. By using ultrastructural and biochemical analysis, we have characterized defects manifested by mutations in the SLA2 gene (also known as the END4 gene), previously found to affect both the organization of the actin cytoskeleton and endocytosis in yeast. Defects in cell wall morphology, accumulated vesicles, and protein secretion kinetics were found in sla2 mutants similar to defects found in act1 mutants. Vesicles that accumulate in the sla2 and act1 mutants are immunoreactive with antibodies directed against the small GTPase Ypt1p but not with antibodies directed against the homologous Sec4p found on classical "late" secretory vesicles. In contrast, the late-acting secretory mutants sec1-1 and sec6-4 are shown to accumulate anti-Sec4p-positive secretory vesicles as well as vesicles that are immunoreactive with antibodies directed against Ypt1p. The late sec mutant sec4-8 is also shown to accumulate Ypt1p-containing vesicles and to exhibit defects in actin cytoskeleton organization. These results indicate the existence of at least two classes of morphologically similar, late secretory vesicles (associated with Ypt1p+ and Sec4p+, respectively), one of which appears to accumulate when the actin cytoskeleton is disorganized.

scholarly journals Pan1p, End3p, and Sla1p, Three Yeast Proteins Required for Normal Cortical Actin Cytoskeleton Organization, Associate with Each Other and Play Essential Roles in Cell Wall Morphogenesis

2000 ◽  
Vol 20 (1) ◽  
pp. 12-25 ◽  
Author(s):  
Hsin-Yao Tang ◽  
Jing Xu ◽  
Mingjie Cai
Keyword(s):  
Cell Wall ◽  
Actin Cytoskeleton ◽  
Normal Cell ◽  
Cell Cortex ◽  
Repeat Region ◽  
Cortical Actin ◽  
Cytoskeleton Organization ◽  
Eh Domain ◽  
Actin Cytoskeleton Organization ◽  
Cell Wall Morphogenesis

ABSTRACT The EH domain proteins Pan1p and End3p of budding yeast have been known to form a complex in vivo and play important roles in organization of the actin cytoskeleton and endocytosis. In this report, we describe new findings concerning the function of the Pan1p-End3p complex. First, we found that the Pan1p-End3p complex associates with Sla1p, another protein known to be required for the assembly of cortical actin structures. Sla1p interacts with the first long repeat region of Pan1p and the N-terminal EH domain of End3p, thus leaving the Pan1p-End3p interaction, which requires the second long repeat of Pan1p and the C-terminal repeat region of End3p, undisturbed. Second, Pan1p, End3p, and Sla1p are also required for normal cell wall morphogenesis. Each of the Pan1-4, sla1Δ, andend3Δ mutants displays the abnormal cell wall morphology previously reported for the act1-1 mutant. These cell wall defects are also exhibited by wild-type cells overproducing the C-terminal region of Sla1p that is responsible for interactions with Pan1p and End3p. These results indicate that the functions of Pan1p, End3p, and Sla1p in cell wall morphogenesis may depend on the formation of a heterotrimeric complex. Interestingly, the cell wall abnormalities exhibited by these cells are independent of the actin cytoskeleton organization on the cell cortex, as they manifest despite the presence of apparently normal cortical actin cytoskeleton. Examination of several act1 mutants also supports this conclusion. These observations suggest that the Pan1p-End3p-Sla1p complex is required not only for normal actin cytoskeleton organization but also for normal cell wall morphogenesis in yeast.

Mutations in the Rho1 small GTPase disrupt morphogenesis and segmentation during early Drosophila development

Development ◽  
1999 ◽  
Vol 126 (23) ◽  
pp. 5353-5364 ◽  
Author(s):  
C.R. Magie ◽  
M.R. Meyer ◽  
M.S. Gorsuch ◽  
S.M. Parkhurst
Keyword(s):  
Actin Cytoskeleton ◽  
Rho Gtpases ◽  
Cell Cycle Progression ◽  
Small Gtpase ◽  
Dorsal Closure ◽  
Loss Of Function ◽  
Drosophila Development ◽  
Cytoskeleton Organization ◽  
Actin Cytoskeleton Organization ◽  
Egg Chambers

Rho GTPases play an important role in diverse biological processes such as actin cytoskeleton organization, gene transcription, cell cycle progression and adhesion. They are required during early Drosophila development for proper execution of morphogenetic movements of individual cells and groups of cells important for the formation of the embryonic body plan. We isolated loss-of-function mutations in the Drosophila Rho1 (Rho1) gene during a genetic screen for maternal-effect mutations, allowing us to investigate the specific roles Rho1 plays in the context of the developing organism. Here we report that Rho1 is required for many early events: loss of Rho1 function results in both maternal and embryonic phenotypes. Embryos homozygous for the Rho1 mutation exhibit a characteristic zygotic phenotype, which includes severe defects in head involution and imperfect dorsal closure. Two phenotypes are associated with reduction of maternal Rho1 activity: the actin cytoskeleton is disrupted in egg chambers, especially in the ring canals and embryos display patterning defects as a result of improper maintenance of segmentation gene expression. Despite showing imperfect dorsal closure, Rho1 does not activate downstream genes or interact genetically with members of the JNK signaling pathway, used by its relatives dRac and dCdc42 for proper dorsal closure. Consistent with its roles in regulating actin cytoskeletal organization, we find that Rho1 interacts genetically and physically with the Drosophila formin homologue, cappuccino. We also show that Rho1 interacts both genetically and physically with concertina, a G(alpha) protein involved in cell shape changes during gastrulation.

scholarly journals TheSaccharomyces cerevisiae14-3-3 Proteins Are Required for the G1/S Transition, Actin Cytoskeleton Organization and Cell Wall Integrity

Genetics ◽  
2006 ◽  
Vol 173 (2) ◽  
pp. 661-675 ◽  
Author(s):  
Francisca Lottersberger ◽  
Andrea Panza ◽  
Giovanna Lucchini ◽  
Simonetta Piatti ◽  
Maria Pia Longhese
Keyword(s):  
Cell Wall ◽  
Actin Cytoskeleton ◽  
Cell Wall Integrity ◽  
Cytoskeleton Organization ◽  
Actin Cytoskeleton Organization

scholarly journals Single-site sonoporation disrupts actin cytoskeleton organization

2014 ◽  
Vol 11 (95) ◽  
pp. 20140071 ◽  
Author(s):  
Xian Chen ◽  
Ruen Shan Leow ◽  
Yaxin Hu ◽  
Jennifer M. F. Wan ◽  
Alfred C. H. Yu
Keyword(s):  
Plasma Membrane ◽  
Actin Cytoskeleton ◽  
Bubble Diameter ◽  
Single Site ◽  
Drug Induced ◽  
Cytoskeleton Organization ◽  
Ultrasound Frequency ◽  
Actin Cytoskeleton Organization ◽  
Cytoplasmic Accumulation ◽  
Confocal Fluorescence Imaging

Sonoporation is based upon an ultrasound–microbubble cavitation routine that physically punctures the plasma membrane on a transient basis. During such a process, the actin cytoskeleton may be disrupted in tandem because this network of subcellular filaments is physically interconnected with the plasma membrane. Here, by performing confocal fluorescence imaging of single-site sonoporation episodes induced by ultrasound-triggered collapse of a single targeted microbubble, we directly observed immediate rupturing of filamentary actin (F-actin) at the sonoporation site (cell type: ZR-75-30; ultrasound frequency: 1 MHz; peak negative pressure: 0.45 MPa; pulse duration: 30 cycles; bubble diameter: 2–4 µm). Also, through conducting a structure tensor analysis, we observed further disassembly of the F-actin network over the next 60 min after the onset of sonoporation. The extent of F-actin disruption was found to be more substantial in cells with higher uptake of sonoporation tracer. Commensurate with this process, cytoplasmic accumulation of globular actin (G-actin) was evident in sonoporated cells, and in turn the G-actin : F-actin ratio was increased in a trend similar to drug-induced (cytochalasin D) actin depolymerization. These results demonstrate that sonoporation is not solely a membrane-level phenomenon: organization of the actin cytoskeleton is concomitantly perturbed.

scholarly journals Golgi Body Motility in the Plant Cell Cortex Correlates with Actin Cytoskeleton Organization

2011 ◽  
Vol 52 (10) ◽  
pp. 1844-1855 ◽  
Author(s):  
Miriam Akkerman ◽  
Elysa J. R. Overdijk ◽  
Jan H. N. Schel ◽  
Anne Mie C. Emons ◽  
Tijs Ketelaar
Keyword(s):  
Actin Cytoskeleton ◽  
Plant Cell ◽  
Golgi Body ◽  
Cell Cortex ◽  
Cytoskeleton Organization ◽  
Actin Cytoskeleton Organization ◽  
Body Motility

The actin cytoskeleton is required to elaborate and maintain spatial patterning during trichome cell morphogenesis in Arabidopsis thaliana

Development ◽  
1999 ◽  
Vol 126 (24) ◽  
pp. 5559-5568 ◽  
Author(s):  
J. Mathur ◽  
P. Spielhofer ◽  
B. Kost ◽  
N. Chua
Keyword(s):  
Arabidopsis Thaliana ◽  
Actin Cytoskeleton ◽  
Spatial Patterning ◽  
Actin Microfilaments ◽  
Cell Morphogenesis ◽  
Actin Organization ◽  
Cytoskeleton Organization ◽  
Branch Formation ◽  
Actin Cytoskeleton Organization ◽  
Trichome Cell

Arabidopsis thaliana trichomes provide an attractive model system to dissect molecular processes involved in the generation of shape and form in single cell morphogenesis in plants. We have used transgenic Arabidopsis plants carrying a GFP-talin chimeric gene to analyze the role of the actin cytoskeleton in trichome cell morphogenesis. We found that during trichome cell development the actin microfilaments assumed an increasing degree of complexity from fine filaments to thick, longitudinally stretched cables. Disruption of the F-actin cytoskeleton by actin antagonists produced distorted but branched trichomes which phenocopied trichomes of mutants belonging to the ‘distorted’ class. Subsequent analysis of the actin cytoskeleton in trichomes of the distorted mutants, alien, crooked, distorted1, gnarled, klunker and wurm uncovered actin organization defects in each case. Treatments of wild-type seedlings with microtubule-interacting drugs elicited a radically different trichome phenotype characterized by isotropic growth and a severe inhibition of branch formation; these trichomes did not show defects in actin cytoskeleton organization. A normal actin cytoskeleton was also observed in trichomes of the zwichel mutant which have reduced branching. ZWICHEL, which was previously shown to encode a kinesin-like protein is thought to be involved in microtubule-linked processes. Based on our results we propose that microtubules establish the spatial patterning of trichome branches whilst actin microfilaments elaborate and maintain the overall trichome pattern during development.

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