scholarly journals Regulation of microtubule dynamic instability by the carboxy-terminal tail of β-tubulin

2018 ◽  
Vol 1 (2) ◽  
pp. e201800054 ◽  
Author(s):  
Colby P Fees ◽  
Jeffrey K Moore
Keyword(s):  
Dynamic Instability ◽  
Intrinsic Property ◽  
In Vivo Studies ◽  
Microtubule Dynamic ◽  
Microtubule Stability ◽  
Microtubule Networks ◽  
Carboxy Terminal ◽  
Β Tubulin

Dynamic instability is an intrinsic property of microtubules; however, we do not understand what domains of αβ-tubulins regulate this activity or how these regulate microtubule networks in cells. Here, we define a role for the negatively charged carboxy-terminal tail (CTT) domain of β-tubulin in regulating dynamic instability. By combining in vitro studies with purified mammalian tubulin and in vivo studies with tubulin mutants in budding yeast, we demonstrate that β-tubulin CTT inhibits microtubule stability and regulates the structure and stability of microtubule plus ends. Tubulin that lacks β-tubulin CTT polymerizes faster and depolymerizes slower in vitro and forms microtubules that are more prone to catastrophe. The ends of these microtubules exhibit a more blunted morphology and rapidly switch to disassembly after tubulin depletion. In addition, we show that β-tubulin CTT is required for magnesium cations to promote depolymerization. We propose that β-tubulin CTT regulates the assembly of stable microtubule ends and provides a tunable mechanism to coordinate dynamic instability with ionic strength in the cell.

scholarly journals Aurora B suppresses microtubule dynamics and limits central spindle size by locally activating KIF4A

2013 ◽  
Vol 202 (4) ◽  
pp. 605-621 ◽  
Author(s):  
Ricardo Nunes Bastos ◽  
Sapan R. Gandhi ◽  
Ryan D. Baron ◽  
Ulrike Gruneberg ◽  
Erich A. Nigg ◽  
...  
Keyword(s):  
Dynamic Instability ◽  
Phosphorylation Site ◽  
Size Control ◽  
Aurora B ◽  
Microtubule Dynamic ◽  
Central Spindle ◽  
Specific Subset ◽  
Mutant Forms

Anaphase central spindle formation is controlled by the microtubule-stabilizing factor PRC1 and the kinesin KIF4A. We show that an MKlp2-dependent pool of Aurora B at the central spindle, rather than global Aurora B activity, regulates KIF4A accumulation at the central spindle. KIF4A phosphorylation by Aurora B stimulates the maximal microtubule-dependent ATPase activity of KIF4A and promotes its interaction with PRC1. In the presence of phosphorylated KIF4A, microtubules grew more slowly and showed long pauses in growth, resulting in the generation of shorter PRC1-stabilized microtubule overlaps in vitro. Cells expressing only mutant forms of KIF4A lacking the Aurora B phosphorylation site overextended the anaphase central spindle, demonstrating that this regulation is crucial for microtubule length control in vivo. Aurora B therefore ensures that suppression of microtubule dynamic instability by KIF4A is restricted to a specific subset of microtubules and thereby contributes to central spindle size control in anaphase.

Structure, function and biology of tissue factor pathway inhibitor-2

2005 ◽  
Vol 94 (12) ◽  
pp. 1122-1130 ◽  
Author(s):  
Hitendra S. Chand ◽  
Donald C. Foster ◽  
Walter Kisiel
Keyword(s):  
Tissue Factor ◽  
Tissue Factor Pathway Inhibitor ◽  
Serine Proteinase ◽  
In Vivo Studies ◽  
Amino Terminal ◽  
Tissue Factor Pathway ◽  
Kunitz Type ◽  
Carboxy Terminal

SummaryTissue factor pathway inhibitor-2 (TFPI-2) is a 32 kDa matrix-associated Kunitz-type serine proteinase inhibitor consisting of a short amino-terminal region, three tandem Kunitz-type domains and a positively charged carboxy-terminal tail. Human TFPI-2, previously designated as placental protein 5, inhibits a broad spectrum of serine proteinases almost exclusively through its first Kunitz-type domain, and is thought to play an important role in the regulation of extracellular matrix digestion and re-modeling. In this context, reduced synthesis of TFPI-2 has been related to numerous pathophysiological processes such as inflammation, angiogenesis, atherosclerosis, retinal degeneration and tumor growth/metastasis. In this review, we document current information regarding the expression of TFPI-2 by various tissues, its inhibitory activity and proteinase specificity in-vitro, and discuss possible physiological roles for this inhibitor based on in-vivo studies.

scholarly journals Modulation of microtubule stability by kinetochores in vitro.

1990 ◽  
Vol 110 (5) ◽  
pp. 1607-1616 ◽  
Author(s):  
A A Hyman ◽  
T J Mitchison
Keyword(s):  
Dynamic Behavior ◽  
Mitotic Spindle ◽  
Dynamic Instability ◽  
Full Range ◽  
Chromosome Movement ◽  
Vitro Assay ◽  
Microtubule Stability ◽  
Rigor State

The interface between kinetochores and microtubules in the mitotic spindle is known to be dynamic. Kinetochore microtubules can both polymerize and depolymerize, and their dynamic behavior is intimately related to chromosome movement. In this paper we investigate the influence of kinetochores on the inherent dynamic behavior of microtubules using an in vitro assay. The dynamics of microtubule plus ends attached to kinetochores are compared to those of free plus ends in the same solution. We show that microtubules attached to kinetochores exhibit the full range of dynamic instability behavior, but at altered transition rates. Surprisingly, we find that kinetochores increase the rate at which microtubule ends transit from growing to shrinking. This result contradicts our previous findings (Mitchison, T. J., and M. W. Kirschner, 1985b) for technical reasons which are discussed. We suggest that catalysis of the growing to shrinking transition by kinetochores may account for selective depolymerization of kinetochore microtubules during anaphase in vivo. We also investigate the effects of a nonhydrolyzable ATP analogue on kinetochore microtubule dynamics. We find that 5' adenylylimido diphosphate induces a rigor state at the kinetochore-microtubule interface, which prevents depolymerization of the microtubule.

scholarly journals Nanomolar concentrations of nocodazole alter microtubule dynamic instability in vivo and in vitro.

1997 ◽  
Vol 8 (6) ◽  
pp. 973-985 ◽  
Author(s):  
R J Vasquez ◽  
B Howell ◽  
A M Yvon ◽  
P Wadsworth ◽  
L Cassimeris
Keyword(s):  
Dynamic Instability ◽  
Light Level ◽  
Pause Duration ◽  
Microtubule Assembly ◽  
Differential Interference Contrast Microscopy ◽  
Microtubule Dynamic ◽  
State Behavior ◽  
Dose Dependent Decrease

Previous studies demonstrated that nanomolar concentrations of nocodazole can block cells in mitosis without net microtubule disassembly and resulted in the hypothesis that this block was due to a nocodazole-induced stabilization of microtubules. We tested this hypothesis by examining the effects of nanomolar concentrations of nocodazole on microtubule dynamic instability in interphase cells and in vitro with purified brain tubulin. Newt lung epithelial cell microtubules were visualized by video-enhanced differential interference contrast microscopy and cells were perfused with solutions of nocodazole ranging in concentration from 4 to 400 nM. Microtubules showed a loss of the two-state behavior typical of dynamic instability as evidenced by the addition of a third state where they exhibited little net change in length (a paused state). Nocodazole perfusion also resulted in slower elongation and shortening velocities, increased catastrophe, and an overall decrease in microtubule turnover. Experiments performed on BSC-1 cells that were microinjected with rhodamine-labeled tubulin, incubated in nocodazole for 1 h, and visualized by using low-light-level fluorescence microscopy showed similar results except that nocodazole-treated BSC-1 cells showed a decrease in catastrophe. To gain insight into possible mechanisms responsible for changes in dynamic instability, we examined the effects of 4 nM to 12 microM nocodazole on the assembly of purified tubulin from axoneme seeds. At both microtubule plus and minus ends, perfusion with nocodazole resulted in a dose-dependent decrease in elongation and shortening velocities, increase in pause duration and catastrophe frequency, and decrease in rescue frequency. These effects, which result in an overall decrease in microtubule turnover after nocodazole treatment, suggest that the mitotic block observed is due to a reduction in microtubule dynamic turnover. In addition, the in vitro results are similar to the effects of increasing concentrations of GDP-tubulin (TuD) subunits on microtubule assembly. Given that nocodazole increases tubulin GTPase activity, we propose that nocodazole acts by generating TuD subunits that then alter dynamic instability.

Analysis of the Mechanism of Microtubule Dynamic Instability Using a UV Microbeam to Sever Elongating Microtubules

1988 ◽  
Vol 46 ◽  
pp. 122-123
Author(s):  
R.A Walker ◽  
S. Inoue ◽  
E.D. Salmon
Keyword(s):  
Dynamic Instability ◽  
Microtubule Dynamic ◽  
Gtp Hydrolysis ◽  
Abrupt Transition ◽  
Microtubule Associated Proteins ◽  
Asymmetrical Structure ◽  
Associated Proteins

Microtubules polymerized in vitro from tubulin purified free of microtubule-associated proteins exhibit dynamic instability (1,2,3). Free microtubule ends exist in persistent phases of elongation or rapid shortening with infrequent, but, abrupt transitions between these phases. The abrupt transition from elongation to rapid shortening is termed catastrophe and the abrupt transition from rapid shortening to elongation is termed rescue. A microtubule is an asymmetrical structure. The plus end grows faster than the minus end. The frequency of catastrophe of the plus end is somewhat greater than the minus end, while the frequency of rescue of the plus end in much lower than for the minus end (4).The mechanism of catastrophe is controversial, but for both the plus and minus microtubule ends, catastrophe is thought to be dependent on GTP hydrolysis. Microtubule elongation occurs by the association of tubulin-GTP subunits to the growing end. Sometime after incorporation into an elongating microtubule end, the GTP is hydrolyzed to GDP, yielding a core of tubulin-GDP capped by tubulin-GTP (“GTP-cap”).

In vitro and in vivo studies of new cationic Zn(II)‐benzonaphthoporphyrazines as photosensitizers for PDT

2001 ◽  
Vol 5 (8) ◽  
pp. 645-651
Author(s):  
M. Peeva ◽  
M. Shopova ◽  
U. Michelsen ◽  
D. Wöhrle ◽  
G. Petrov ◽  
...  
Keyword(s):  
In Vivo Studies

Effect of caffeine on theophyliine on cerebral blood flow response to brain activation: In vitro and in vivo studies

2005 ◽  
Vol 25 (1_suppl) ◽  
pp. S198-S198
Author(s):  
Joseph R Meno ◽  
Thien-son K Nguyen ◽  
Elise M Jensen ◽  
G Alexander West ◽  
Leonid Groysman ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Brain Activation ◽  
In Vivo Studies ◽  
Blood Flow Response ◽  
Flow Response

Effects of Unfractionated and Low Molecular Weight Heparins on Platelet Thromboxane Biosynthesis “In Vivo”

1994 ◽  
Vol 72 (06) ◽  
pp. 942-946 ◽  
Author(s):  
Raffaele Landolfi ◽  
Erica De Candia ◽  
Bianca Rocca ◽  
Giovanni Ciabattoni ◽  
Armando Antinori ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Unfractionated Heparin ◽  
Low Molecular Weight Heparin ◽  
Primary Source ◽  
In Vivo Studies ◽  
Low Molecular Weight ◽  
Heparin Administration ◽  
To Receive

SummarySeveral “in vitro” and “in vivo” studies indicate that heparin administration may affect platelet function. In this study we investigated the effects of prophylactic heparin on thromboxane (Tx)A2 biosynthesis “in vivo”, as assessed by the urinary excretion of major enzymatic metabolites 11-dehydro-TxB2 and 2,3-dinor-TxB2. Twenty-four patients who were candidates for cholecystectomy because of uncomplicated lithiasis were randomly assigned to receive placebo, unfractionated heparin, low molecular weight heparin or unfractionaed heparin plus 100 mg aspirin. Measurements of daily excretion of Tx metabolites were performed before and during the treatment. In the groups assigned to placebo and to low molecular weight heparin there was no statistically significant modification of Tx metabolite excretion while patients receiving unfractionated heparin had a significant increase of both metabolites (11-dehydro-TxB2: 3844 ± 1388 vs 2092 ±777, p <0.05; 2,3-dinor-TxB2: 2737 ± 808 vs 1535 ± 771 pg/mg creatinine, p <0.05). In patients randomized to receive low-dose aspirin plus unfractionated heparin the excretion of the two metabolites was largely suppressed thus suggesting that platelets are the primary source of enhanced thromboxane biosynthesis associated with heparin administration. These data indicate that unfractionated heparin causes platelet activation “in vivo” and suggest that the use of low molecular weight heparin may avoid this complication.

Effectiveness of the integration of quercetin, turmeric, and N-acetylcysteine in reducing inflammation and pain associated with endometriosis. In-vitro and in-vivo studies

2020 ◽  
Vol 72 (5) ◽  
Author(s):  
Mario Fadin ◽  
Maria C. Nicoletti ◽  
Marzia Pellizzato ◽  
Manuela Accardi ◽  
Maria G. Baietti ◽  
...  
Keyword(s):  
In Vivo Studies
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