scholarly journals Microtubule Bundle

2020 ◽  
Author(s):  
Keyword(s):  
Microtubule Bundle

scholarly journals Studies concerning the temporal and genetic control of cell polarity in Saccharomyces cerevisiae.

1991 ◽  
Vol 114 (3) ◽  
pp. 515-532 ◽  
Author(s):  
M Snyder ◽  
S Gehrung ◽  
B D Page
Keyword(s):  
Cell Cycle ◽  
Cell Polarity ◽  
Spindle Pole Body ◽  
Spindle Pole ◽  
Yeast Cells ◽  
Cell Cycle Distribution ◽  
Restrictive Temperature ◽  
Microtubule Bundle ◽  
Pole Body ◽  
Capture Site

The establishment of cell polarity was examined in the budding yeast, S. cerevisiae. The distribution of a polarized protein, the SPA2 protein, was followed throughout the yeast cell cycle using synchronized cells and cdc mutants. The SPA2 protein localizes to a patch at the presumptive bud site of G1 cells. Later it concentrates at the bud tip in budded cells. At cytokinesis, the SPA2 protein is at the neck between the mother and daughter cells. Analysis of unbudded haploid cells has suggested a series of events that occurs during G1. The SPA2 patch is established very early in G1, while the spindle pole body residues on the distal side of the nucleus. Later, microtubules emanating from the spindle pole body intersect the SPA2 crescent, and the nucleus probably rotates towards the SPA2 patch. By middle G1, most cells contain the SPB on the side of the nucleus proximal to the SPA2 patch, and a long extranuclear microtubule bundle intersects this patch. We suggest that a microtubule capture site exists in the SPA2 staining region that stabilizes the long microtubule bundle; this capture site may be responsible for rotation of the nucleus. Cells containing a polarized distribution of the SPA2 protein also possess a polarized distribution of actin spots in the same region, although the actin staining is much more diffuse. Moreover, cdc4 mutants, which form multiple buds at the restrictive temperature, exhibit simultaneous staining of the SPA2 protein and actin spots in a subset of the bud tips. spa2 mutants contain a polarized distribution of actin spots, and act1-1 and act1-2 mutants often contain a polarized distribution of the SPA2 protein suggesting that the SPA2 protein is not required for localization of the actin spots and the actin spots are not required for localization of the SPA2 protein. cdc24 mutants, which fail to form buds at the restrictive temperature, fail to exhibit polarized localization of the SPA2 protein and actin spots, indicating that the CDC24 protein is directly or indirectly responsible for controlling the polarity of these proteins. Based on the cell cycle distribution of the SPA2 protein, a "cytokinesis tag" model is proposed to explain the mechanism of the non-random positioning of bud sites in haploid yeast cells.

scholarly journals Condensation of Divalent Metail Ions by Map-Tau Remodels Tau-Microtubule Bundle Architecture

2019 ◽  
Vol 116 (3) ◽  
pp. 255a
Author(s):  
Bretton Fletcher ◽  
Chaeyeon Song ◽  
Phillip Kohl ◽  
Peter J. Chung ◽  
Herbert Miller ◽  
...  
Keyword(s):  
Microtubule Bundle

scholarly journals Pivot-and-bond model explains microtubule bundle formation

2019 ◽  
Vol 100 (1) ◽  
Author(s):  
Marcel Prelogović ◽  
Lora Winters ◽  
Ana Milas ◽  
Iva M. Tolić ◽  
Nenad Pavin
Keyword(s):  
Microtubule Bundle ◽  
Bond Model

scholarly journals Two Related Subpellicular Cytoskeleton-associated Proteins inTrypanosoma brucei Stabilize Microtubules

2002 ◽  
Vol 13 (3) ◽  
pp. 1058-1070 ◽  
Author(s):  
Cécile Vedrenne ◽  
Christiane Giroud ◽  
Derrick R. Robinson ◽  
Sébastien Besteiro ◽  
Christophe Bosc ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Molecular Weight ◽  
Trypanosoma Brucei ◽  
Cold Resistance ◽  
Chinese Hamster ◽  
Low Molecular Weight ◽  
Microtubule Bundle ◽  
Microtubule Associated Proteins ◽  
Associated Proteins ◽  
Asymmetric Cytokinesis

The subpellicular microtubules of the trypanosome cytoskeleton are cross-linked to each other and the plasma membrane, creating a cage-like structure. We have isolated, from Trypanosoma brucei, two related low-molecular-weight cytoskeleton-associated proteins (15- and 17-kDa), called CAP15 and CAP17, which are differentially expressed during the life cycle. Immunolabeling shows a corset-like colocalization of both CAPs and tubulin. Western blot and electron microscope analyses show CAP15 and CAP17 labeling on detergent-extracted cytoskeletons. However, the localization of both proteins is restricted to the anterior, microtubule minus, and less dynamic half of the corset. CAP15 and CAP17 share properties of microtubule-associated proteins when expressed in heterologous cells (Chinese hamster ovary and HeLa), colocalization with their microtubules, induction of microtubule bundle formation, cold resistance, and insensitivity to nocodazole. When overexpressed inT. brucei, both CAP15 and CAP17 cover the whole subpellicular corset and induce morphological disorders, cell cycle-based abnormalities, and subsequent asymmetric cytokinesis.

scholarly journals Tau mediates microtubule bundle architectures mimicking fascicles of microtubules found in the axon initial segment

2016 ◽  
Vol 7 (1) ◽  
Author(s):  
Peter J. Chung ◽  
Chaeyeon Song ◽  
Joanna Deek ◽  
Herbert P. Miller ◽  
Youli Li ◽  
...  
Keyword(s):  
Initial Segment ◽  
Axon Initial Segment ◽  
Microtubule Bundle

scholarly journals Microtubule Bundle Formation and Cell Death Induced by the Human CLASP/Orbit N-Terminal Fragment

2005 ◽  
Vol 30 (1) ◽  
pp. 7-13 ◽  
Author(s):  
Miki Aonuma ◽  
Mamiko Miyamoto ◽  
Yoshihiro H. Inoue ◽  
Katsuyuki Tamai ◽  
Hikoichi Sakai ◽  
...  
Keyword(s):  
Cell Death ◽  
Microtubule Bundle ◽  
Terminal Fragment

scholarly journals Quiescent Saccharomyces cerevisiae forms telomere hyperclusters at the nuclear membrane vicinity through a multifaceted mechanism involving Esc1, the Sir complex, and chromatin condensation

2016 ◽  
Vol 27 (12) ◽  
pp. 1875-1884 ◽  
Author(s):  
Damien Laporte ◽  
Fabien Courtout ◽  
Sylvain Tollis ◽  
Isabelle Sagot
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Nuclear Membrane ◽  
Chromatin Condensation ◽  
Histone H1 ◽  
Chromosome Condensation ◽  
Histone H4 ◽  
Microtubule Bundle ◽  
Quiescent Cells ◽  
Nuclear Reorganization ◽  
Sir Complex

Like other eukaryotes, Saccharomyces cerevisiae spatially organizes its chromosomes within the nucleus. In G1 phase, the yeast’s 32 telomeres are clustered into 6–10 foci that dynamically interact with the nuclear membrane. Here we show that, when cells leave the division cycle and enter quiescence, telomeres gather into two to three hyperclusters at the nuclear membrane vicinity. This localization depends on Esc1 but not on the Ku proteins. Telomere hypercluster formation requires the Sir complex but is independent of the nuclear microtubule bundle that specifically assembles in quiescent cells. Importantly, mutants deleted for the linker histone H1 Hho1 or defective in condensin activity or affected for histone H4 Lys-16 deacetylation are impaired, at least in part, for telomere hypercluster formation in quiescence, suggesting that this process involves chromosome condensation. Finally, we establish that telomere hypercluster formation is not necessary for quiescence establishment, maintenance, and exit, raising the question of the physiological raison d’être of this nuclear reorganization.

First-in-human phase I trial of a novel epothilone, KOS-1584

2006 ◽  
Vol 24 (18_suppl) ◽  
pp. 2003-2003 ◽  
Author(s):  
M. Villalona-Calero ◽  
S. Goel ◽  
L. Schaaf ◽  
B. McCracken ◽  
K. Desai ◽  
...  
Keyword(s):  
Ovarian Cancer ◽  
Screening Program ◽  
Optimal Dose ◽  
Microtubule Bundle ◽  
Emax Model ◽  
Solid Malignancies ◽  
Epothilone D ◽  
Grade 3 ◽  
Ecog Ps ◽  
New Generation

2003 Background: KOS-1584 (9,10-didehydroepothilone D) was discovered as part of a screening program to develop a new generation of epothilones with higher potency and an improved pharmacologic/pharmacokinetic (PK) profile. Epothilones stabilize microtubule polymerization, inducing rapid G2/M arrest and apoptosis. Antitumor activity of KOS-1584 (Chou et al 2003) is approximately 3–12 fold more potent when compared to the structurally related Epothilone D. KOS-1584 demonstrates enhanced tumor tissue penetration and reduced exposure to selected tissues (including CNS). We report the results of the initial dose-escalation trial in which KOS-1584 was administered to pts with advanced solid malignancies. Methods: Define the MTD, toxicity profile and PK of KOS-1584 when administered via 3-hour infusion every 3 weeks. PK was determined after the 1st and 2nd infusion. Pharmacodynamics were assessed by serial sampling of PBMCs for microtubule bundle formation. Results: 27 pts (17 F; median age 60; median ECOG PS 1; median prior regimens 3, range 0–7) enrolled in 8 dose levels (between 0.8 - 11.3 mg/m2). To date, no Cycle 1 DLT has been seen. Toxicities (n=24) did not show obvious dose dependency; common toxicity (Grade 1–2) included gastrointestinal (diarrhea, constipation, nausea), fatigue, and ↑AST. Drug-related Grade 3 toxicity: constipation, fatigue and ↑AST (1 each). Drug-related neurotoxicity was not notable. PK/parent (n=25): t½ 17.7 ± 4.6h, Vz 741±330 L and CL 30.2± 16.5 L/h. At 8.5 mg/m2 Cmax 78 ± 29 ng/mL; AUCtot 631 ± 337 ng*h/mL. Cmax and AUCtot increased linearly with dose over the range tested. Vz is ∼5-fold and t½ 2-fold higher than that of Epothilone D. Dose dependent increases in microtubule bundle formation were observed (8.5 mg/m2: 40–50% at end of infusion, compared to 60–65% for ixabepilone and 50–60% for Epothilone D using the same assay at their phase 2 dose). A sigmoidal Emax model described the relationship between plasma concentration and microtubule bundle formation. Activity consisted of 4 pts with extended stable disease (6 cycles leiomyosarcoma and ovarian cancer; 5 cycles colon cancer; a 2nd patient with ovarian cancer is active at 5 cycles). Of these, 3 had document progressive disease prior to study. Conclusions: Accrual is continuing in order to define the optimal dose on the 3-week regimen. [Table: see text]

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