Flagellar regeneration requires cytoplasmic microtubule depolymerization and kinesin-13

2013 ◽  
Vol 126 (6) ◽  
pp. 1531-1540 ◽  
Author(s):  
L. Wang ◽  
T. Piao ◽  
M. Cao ◽  
T. Qin ◽  
L. Huang ◽  
...  
Keyword(s):  
Microtubule Depolymerization ◽  
Cytoplasmic Microtubule ◽  
Flagellar Regeneration

Regulation of cell shape in Euglena gracilis. III. Involvement of stable microtubules

1985 ◽  
Vol 74 (1) ◽  
pp. 219-237
Author(s):  
C.L. Lachney ◽  
T.A. Lonergan
Keyword(s):  
Euglena Gracilis ◽  
Cell Shape ◽  
Microtubule Assembly ◽  
Live Cells ◽  
Microtubule Depolymerization ◽  
Cytoplasmic Microtubule ◽  
Intact Cells ◽  
Calmodulin Antagonist ◽  
Cell Shapes ◽  
In Cells

The role of cytoplasmic microtubules in a recently reported biological clock-controlled rhythm in cell shape of the alga Euglena gracilis (strain Z) was examined using indirect immunofluorescence microscopy. The resulting fluorescent patterns indicated that, unlike many other cell systems, Euglena cells apparently change from round to long to round cell shape without associated cytoplasmic microtubule assembly and disassembly. Instead, the different cell shapes were correlated with microtubule patterns, which suggested that movement of stable microtubules to accomplish cell shape changes. In live intact cells, these microtubules were demonstrated by immunofluorescence to be stable to lowered temperature and elevated intracellular Ca2+ levels, treatments that are commonly used to depolymerize microtubules. In cells extracted in detergent at low temperature or in the presence of elevated Ca2+ levels, the fluorescent image of the microtubules was disrupted. Transmission electron microscopy confirmed the loss of one subset of pellicle microtubules. The difference in microtubule stability to these agents between live intact cells and cells extracted in detergent suggested the presence of a microtubule-stabilizing factor in live cells, which is released from the cell by extraction with detergent, thereby permitting microtubule depolymerization by Ca2+ or lowered temperature. The calmodulin antagonist trifluoperazine prevented the Ca2+-induced disruption of the fluorescent microtubule pattern in cells extracted in detergent. These results implied the involvement of calmodulin in the sensitivity to Ca2+ of the microtubules of cells extracted in detergent.

scholarly journals The short flagella 1 (SHF1) gene in Chlamydomonas encodes a Crescerin TOG-domain protein required for late stages of flagellar growth.

2021 ◽  
Author(s):  
Karina Perlaza ◽  
Mariya Mirvis ◽  
Hiroaki Ishikawa ◽  
Wallace F Marshall
Keyword(s):  
Model Organism ◽  
Size Control ◽  
Intraflagellar Transport ◽  
Loss Of Function ◽  
Wild Type ◽  
Cytoplasmic Microtubule ◽  
Flagellar Assembly ◽  
Flagellar Regeneration ◽  
Domain Protein ◽  
Late Stages

Length control of flagella represents a simple and tractable system to investigate the dynamics of organelle size. Models for flagellar length control in the model organism, Chlamydomonas reinhardtii have focused on the length-dependence of the intraflagellar transport (IFT) system which manages the delivery and removal of axonemal subunits at the tip of the flagella. One of these cargoes, tubulin, is the major axonemal subunit, and its frequency of arrival at the tip plays a central role in size control models. However, the mechanisms determining tubulin dynamics at the tip are still poorly understood. We discovered a loss-of-function mutation that leads to shortened flagella, and found that this was an allele of a previously described gene, SHF1, whose molecular identity had not previously been determined. We found that SHF1 encodes a Chlamydomonas ortholog of Crescerin, previously identified as a cilia specific TOG-domain array protein that can bind tubulin via its TOG domains and increase tubulin polymerization rates. In this mutant, flagellar regeneration occurs with the same initial kinetics as wild-type cells, but plateaus at a shorter length. Using a computational model in which the flagellar microtubules are represented by a differential equation for flagellar length combined with a stochastic model for cytoplasmic microtubule dynamics, we found that our experimental results are best described by a model in which Crescerin/SHF1 binds tubulin dimers in the cytoplasm and transports them into the flagellum. We suggest that this TOG-domain protein is necessary to efficiently and preemptively increase intra-flagella tubulin levels to offset decreasing IFT cargo at the tip as flagellar assembly progresses.

scholarly journals The short flagella 1 (SHF1) gene in Chlamydomonas encodes a Crescerin TOG-domain protein required for late stages of flagellar growth

2021 ◽  
Author(s):  
Karina Perlaza ◽  
Mary Mirvis ◽  
Hiroaki Ishikawa ◽  
Wallace Marshall
Keyword(s):  
Model Organism ◽  
Size Control ◽  
Intraflagellar Transport ◽  
Loss Of Function ◽  
Wild Type ◽  
Cytoplasmic Microtubule ◽  
Flagellar Assembly ◽  
Flagellar Regeneration ◽  
Domain Protein ◽  
Late Stages

Length control of flagella represents a simple and tractable system to investigate the dynamics of organelle size. Models for flagellar length control in the model organism, Chlamydomonas reinhardtii have focused on the length-dependence of the intraflagellar transport (IFT) system which manages the delivery and removal of axonemal subunits at the tip of the flagella. One of these cargoes, tubulin, is the major axonemal subunit, and its frequency of arrival at the tip plays a central role in size control models. However, the mechanisms determining tubulin dynamics at the tip are still poorly understood. We discovered a loss-of-function mutation that leads to shortened flagella, and found that this was an allele of a previously described gene, SHF1, whose molecular identity had not previously been determined.  We found that SHF1 encodes a Chlamydomonas ortholog of Crescerin, previously identified as a cilia-specific TOG-domain array protein that can bind tubulin via its TOG domains and increase tubulin polymerization rates. In this mutant, flagellar regeneration occurs with the same initial kinetics as wild-type cells, but plateaus at a shorter length. Using a computational model in which the flagellar microtubules are represented by a differential equation for flagellar length combined with a stochastic model for cytoplasmic microtubule dynamics, we found that our experimental results are best described by a model in which Crescerin/SHF1 binds tubulin dimers in the cytoplasm and transports them into the flagellum. We suggest that this TOG-domain protein is necessary to efficiently and preemptively increase intra-flagella tubulin levels to offset decreasing IFT cargo at the tip as flagellar assembly progresses.

Growth factors and the primary cilium in BALB/c 3T3 cells

1987 ◽  
Vol 45 ◽  
pp. 830-831
Author(s):  
R. W. Tucker ◽  
N. S. More ◽  
S. Jayaraman
Keyword(s):  
Growth Factors ◽  
Primary Cilium ◽  
Cultured Cells ◽  
Morphological Changes ◽  
Calcium Ionophore ◽  
Growth Stimulation ◽  
Calcium Ionophore A23187 ◽  
Ionophore A23187 ◽  
3T3 Cells ◽  
Microtubule Depolymerization

The mechanisms by which polypeptide growth factors Induce DNA synthesis in cultured cells is not understood, but morphological changes Induced by growth factors have been used as clues to Intracellular messengers responsible for growth stimulation. One such morphological change has been the transient disappearance of the primary cilium, a “9 + 0” cilium formed by the perinuclear centriole in interphase cells. Since calcium ionophore A23187 also produced both mitogenesis and ciliary changes, microtubule depolymerization might explain ciliary disappearance monitored by indirect immunofluorescence with anti-tubulin antibody. However, complete resorption and subsequent reformation of the primary cilium occurs at mitosis, and might also account for ciliary disappearance induced by growth factors. To settle this issue, we investigated the ultrastructure of the primary cilium using serial thin-section electron microscopy of quiescent BALB/c 3T3 cells before and after stimulation with serum.

scholarly journals Developmental-Dependent Action of Microtubule Depolymerization on the Function and Structure of Synaptic Glycine Receptor Clusters in Spinal Neurons

2004 ◽  
Vol 91 (2) ◽  
pp. 1036-1049 ◽  
Author(s):  
Brigitte van Zundert ◽  
Francisco J. Alvarez ◽  
Juan Carlos Tapia ◽  
Hermes H. Yeh ◽  
Emilio Diaz ◽  
...  
Keyword(s):  
Average Length ◽  
Glycine Receptor ◽  
Colchicine Treatment ◽  
Morphological Properties ◽  
Microtubule Depolymerization ◽  
Spinal Neurons ◽  
Functional Changes ◽  
Microtubule Disruption ◽  
Immature Neurons ◽  
Mature Neurons

Microtubules have been proposed to interact with gephyrin/glycine receptors (GlyRs) in synaptic aggregates. However, the consequence of microtubule disruption on the structure of postsynaptic GlyR/gephyrin clusters is controversial and possible alterations in function are largely unknown. In this study, we have examined the physiological and morphological properties of GlyR/gephyrin clusters after colchicine treatment in cultured spinal neurons during development. In immature neurons (5-7 DIV), disruption of microtubules resulted in a 33 ± 4% decrease in the peak amplitude and a 72 ± 15% reduction in the frequency of spontaneous glycinergic miniature postsynaptic currents (mIPSCs) recorded in whole cell mode. However, similar colchicine treatments resulted in smaller effects on 10-12 DIV neurons and no effect on mature neurons (15-17 DIV). The decrease in glycinergic mIPSC amplitude and frequency reflects postsynaptic actions of colchicine, since postsynaptic stabilization of microtubules with GTP prevented both actions and similar reductions in mIPSC frequency were obtained by modifying the Cl- driving force to obtain parallel reductions in mIPSC amplitude. Confocal microscopy revealed that colchicine reduced the average length and immunofluorescence intensity of synaptic gephyrin/GlyR clusters in immature (approximately 30%) and intermediate (approximately 15%) neurons, but not in mature clusters. Thus the structural and functional changes of postsynaptic gephyrin/GlyR clusters after colchicine treatment were tightly correlated. Finally, RT-PCR, kinetic analysis and picrotoxin blockade of glycinergic mIPSCs indicated a reorganization of the postsynaptic region from containing both α2β and α1β GlyRs in immature neurons to only α1β GlyRs in mature neurons. Microtubule disruption preferentially affected postsynaptic sites containing α2β-containing synaptic receptors.

scholarly journals Synthesis of New Simplified and Racemic Hemiasterlin Derivatives with Extremely High Cytotoxicity

2018 ◽  
Vol 13 (12) ◽  
pp. 1934578X1801301
Author(s):  
Pham The Chinh ◽  
Đang Thi Tuyet Anh ◽  
Duong Huong Quynh ◽  
Le Nhat Thuy Giang ◽  
Nguyen Ha Thanh ◽  
...  
Keyword(s):  
Cytotoxic Activity ◽  
Cell Lines ◽  
Human Cancer ◽  
Microtubule Depolymerization ◽  
Antimitotic Agent ◽  
Human Cancer Cell Lines ◽  
Weak Activity ◽  
High Cytotoxicity ◽  
Chemistry Community

Hemiasterlin is a potent antimitotic agent acting through inhibition of microtubule depolymerization. For this reason, the synthesis of new hemiasterlin derivatives has attracted a lot of interest in the organic chemistry community recently. In this paper, the synthesis and evaluation of the cytotoxicity of new simplified and racemic hemiasterlin derivatives were reported. All of the synthesized analogues were evaluated in vitro for cytotoxic activity against four human cell lines (KB, Hep-G2, LU and MCF7). Most of these analogues possess a strong cytotoxic activity on two human cancer cell lines (KB and Hep-G2) and very weak activity on LU and MCF7 cell lines.

scholarly journals Microtubule-dependent distribution of mRNA in adult cardiocytes

2008 ◽  
Vol 294 (3) ◽  
pp. H1135-H1144 ◽  
Author(s):  
Dimitri Scholz ◽  
Catalin F. Baicu ◽  
William J. Tuxworth ◽  
Lin Xu ◽  
Harinath Kasiganesan ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Fluorescent Protein ◽  
Average Distance ◽  
Yellow Fluorescent Protein ◽  
Pressure Overload ◽  
Structural Protein ◽  
Protein Fusion ◽  
Microtubule Depolymerization ◽  
Microtubule Network ◽  
Hypertrophic Growth

Synthesis of myofibrillar proteins in the diffusion-restricted adult cardiocyte requires microtubule-based active transport of mRNAs as part of messenger ribonucleoprotein particles (mRNPs) to translation sites adjacent to nascent myofibrils. This is especially important for compensatory hypertrophy in response to hemodynamic overloading. The hypothesis tested here is that excessive microtubule decoration by microtubule-associated protein 4 (MAP4) after cardiac pressure overloading could disrupt mRNP transport and thus hypertrophic growth. MAP4-overexpressing and pressure-overload hypertrophied adult feline cardiocytes were infected with an adenovirus encoding zipcode-binding protein 1-enhanced yellow fluorescent protein fusion protein, which is incorporated into mRNPs, to allow imaging of these particles. Speed and distance of particle movement were measured via time-lapse microscopy. Microtubule depolymerization was used to study microtubule-based transport and distribution of mRNPs. Protein synthesis was assessed as radioautographic incorporation of [3H]phenylalanine. After microtubule depolymerization, mRNPs persist only perinuclearly and apparent mRNP production and protein synthesis decrease. Reestablishing microtubules restores mRNP production and transport as well as protein synthesis. MAP4 overdecoration of microtubules via adenovirus infection in vitro or following pressure overloading in vivo reduces the speed and average distance of mRNP movement. Thus cardiocyte microtubules are required for mRNP transport and structural protein synthesis, and MAP4 decoration of microtubules, whether directly imposed or accompanying pressure-overload hypertrophy, causes disruption of mRNP transport and protein synthesis. The dense, highly MAP4-decorated microtubule network seen in severe pressure-overload hypertrophy both may cause contractile dysfunction and, perhaps even more importantly, may prevent a fully compensatory growth response to hemodynamic overloading.

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