scholarly journals A midbody component homolog, too much information/prc1-like, is required for microtubule reorganization during both cytokinesis and axis induction in the early zebrafish embryo

2021 ◽  
Author(s):  
Sreelaja Nair ◽  
Elaine L Welch ◽  
Cara E Moravec ◽  
Ryan L Trevena ◽  
Francisco Pelegri
Keyword(s):  
Cell Division ◽  
Zebrafish Embryo ◽  
Early Embryo ◽  
Embryonic Cell ◽  
Additional Function ◽  
Microtubule Associated Proteins ◽  
Vegetal Cortex ◽  
Homozygous Mutant ◽  
Vegetal Pole ◽  
Associated Proteins

We show that the zebrafish maternal-effect mutation too much information (tmi) corresponds to zebrafish prc1-like (prc1l), which encodes a member of the MAP65/Ase1/PRC1family of microtubule-associated proteins. Embryos from tmi/prc1l homozygous mutant mothers display cytokinesis defects in meiotic and mitotic divisions in the early embryo, indicating that tmi/prc1l has a role in midbody formation during cell division at the egg-to-embryo transition. Unexpectedly, maternal tmi/prc1l function is also essential for the reorganization of vegetal pole microtubules required for embryonic axis induction. While Prc1 is widely regarded to crosslink microtubules in an antiparallel conformation, our studies provide evidence for an additional function of Prc1 in the bundling of parallel microtubules in the vegetal cortex of the early embryo during cortical rotation and prior to mitotic cycling. These findings highlight common yet distinct aspects of microtubule reorganization that occur during the egg-to-embryo transition, driven by maternal product for the midbody component Prc1l and required for embryonic cell division and pattern formation.

scholarly journals KIF14 and citron kinase act together to promote efficient cytokinesis

2006 ◽  
Vol 172 (3) ◽  
pp. 363-372 ◽  
Author(s):  
Ulrike Gruneberg ◽  
Rüdiger Neef ◽  
Xiuling Li ◽  
Eunice H.Y. Chan ◽  
Ravindra B. Chalamalasetty ◽  
...  
Keyword(s):  
Cell Division ◽  
Human Cell ◽  
Cleavage Furrow ◽  
General Requirement ◽  
Central Spindle ◽  
Microtubule Associated Proteins ◽  
Cell Biol ◽  
Associated Proteins ◽  
Essential Function ◽  
Citron Kinase

Multiple mitotic kinesins and microtubule-associated proteins (MAPs) act in concert to direct cytokinesis (Glotzer, M. 2005. Science. 307:1735–1739). In anaphase cells, many of these proteins associate with an antiparallel array of microtubules termed the central spindle. The MAP and microtubule-bundling protein PRC1 (protein-regulating cytokinesis 1) is one of the key molecules required for the integrity of this structure (Jiang, W., G. Jimenez, N.J. Wells, T.J. Hope, G.M. Wahl, T. Hunter, and R. Fukunaga. 1998. Mol. Cell. 2:877–885; Mollinari, C., J.P. Kleman, W. Jiang, G. Schoehn, T. Hunter, and R.L. Margolis. 2002. J. Cell Biol. 157:1175–1186). In this study, we identify an interaction between endogenous PRC1 and the previously uncharacterized kinesin KIF14 as well as other mitotic kinesins (MKlp1/CHO1, MKlp2, and KIF4) with known functions in cytokinesis (Hill, E., M. Clarke, and F.A. Barr. 2000. EMBO J. 19:5711–5719; Matuliene, J., and R. Kuriyama. 2002. Mol. Biol. Cell. 13:1832–1845; Kurasawa, Y., W.C. Earnshaw, Y. Mochizuki, N. Dohmae, and K. Todokoro. 2004. EMBO J. 23:3237–3248). We find that KIF14 targets to the central spindle via its interaction with PRC1 and has an essential function in cytokinesis. In KIF14-depleted cells, citron kinase but not other components of the central spindle and cleavage furrow fail to localize. Furthermore, the localization of KIF14 and citron kinase to the central spindle and midbody is codependent, and they form a complex depending on the activation state of citron kinase. Contrary to a previous study (Di Cunto, F., S. Imarisio, E. Hirsch, V. Broccoli, A. Bulfone, A. Migheli, C. Atzori, E. Turco, R. Triolo, G.P. Dotto, et al. 2000. Neuron. 28:115–127), we find a general requirement for citron kinase in human cell division. Together, these findings identify a novel pathway required for efficient cytokinesis.

scholarly journals Cell lineage-dependent chiral actomyosin flows drive cellular rearrangements in early development

2019 ◽  
Author(s):  
Lokesh Pimpale ◽  
Teije C. Middelkoop ◽  
Alexander Mietke ◽  
Stephan W. Grill
Keyword(s):  
Cell Division ◽  
Cell Lineage ◽  
Early Embryo ◽  
Embryonic Cell ◽  
Rotating Flows ◽  
Cell Divisions ◽  
Fluid Theory ◽  
Division Axis ◽  
Cell Reorientation ◽  
Shed Light

ABSTRACTProper positioning of cells is important for many aspects of embryonic development, tissue homeostasis, and regeneration. A simple mechanism by which cell positions can be specified is via orienting the cell division axis. This axis is specified at the onset of cytokinesis, but can be reoriented as cytokinesis proceeds. Rotatory actomyosin flows have been implied in specifying and reorienting the cell division axis in certain cases, but how general such reorientation events are, and how they are controlled, remains unclear. In this study, we set out to address these questions by investigating early Caenorhabditis elegans development. In particular, we determined which of the early embryonic cell divisions exhibit chiral counter-rotating actomyosin flows, and which do not. We follow the first nine divisions of the early embryo, and discover that chiral counter-rotating flows arise systematically in the early AB lineage, but not in early P/EMS lineage cell divisions. Combining our experiments with thin film active chiral fluid theory we identify specific properties of the actomyosin cortex in the symmetric AB lineage divisions that favor chiral counter-rotating actomyosin flows of the two halves of the dividing cell. Finally, we show that these counter-rotations are the driving force of both the AB lineage spindle skew and cell reorientation events. In conclusion, we here have shed light on the physical basis of lineage-specific actomyosin-based processes that drive chiral morphogenesis during development.

scholarly journals On the embryonic cell division beyond the contractile ring mechanism: experimental and computational investigation of effects of vitelline confinement, temperature and egg size

PeerJ ◽  
2015 ◽  
Vol 3 ◽  
pp. e1490 ◽  
Author(s):  
Evgeny Gladilin ◽  
Roland Eils ◽  
Leonid Peshkin
Keyword(s):  
Cell Division ◽  
Egg Size ◽  
Early Embryo ◽  
Embryonic Cell ◽  
Vitelline Membrane ◽  
Imaging Data ◽  
Contractile Ring ◽  
Dividing Cells ◽  
Vitelline Envelope ◽  
Effects Of Temperature

Embryonic cell division is a mechanical process which is predominantly driven by contraction of the cleavage furrow and response of the remaining cellular matter. While most previous studies focused on contractile ring mechanisms of cytokinesis, effects of environmental factors such as pericellular vitelline membrane and temperature on the mechanics of dividing cells were rarely studied. Here, we apply a model-based analysis to the time-lapse imaging data of two species (Saccoglossus kowalevskiiandXenopus laevis) with relatively large eggs, with the goal of revealing the effects of temperature and vitelline envelope on the mechanics of the first embryonic cell division. We constructed a numerical model of cytokinesis to estimate the effects of vitelline confinement on cellular deformation and to predict deformation of cellular contours. We used the deviations of our computational predictions from experimentally observed cell elongation to adjust variable parameters of the contractile ring model and to quantify the contribution of other factors (constitutive cell properties, spindle polarization) that may influence the mechanics and shape of dividing cells. We find that temperature affects the size and rate of dilatation of the vitelline membrane surrounding fertilized eggs and show that in native (not artificially devitellinized) egg cells the effects of temperature and vitelline envelope on mechanics of cell division are tightly interlinked. In particular, our results support the view that vitelline membrane fulfills an important role of micromechanical environment around the early embryo the absence or improper function of which under moderately elevated temperature impairs normal development. Furthermore, our findings suggest the existence of scale-dependent mechanisms that contribute to cytokinesis in species with different egg size, and challenge the view of mechanics of embryonic cell division as a scale-independent phenomenon.

scholarly journals The contribution of αβ-tubulin curvature to microtubule dynamics

2014 ◽  
Vol 207 (3) ◽  
pp. 323-334 ◽  
Author(s):  
Gary J. Brouhard ◽  
Luke M. Rice
Keyword(s):  
Cell Division ◽  
Mitotic Spindle ◽  
Fundamental Property ◽  
Microtubule Dynamics ◽  
Cellular Structures ◽  
Microtubule Associated Proteins ◽  
Associated Proteins ◽  
Microtubule Growth ◽  
Microtubule Networks ◽  
And Control

Microtubules are dynamic polymers of αβ-tubulin that form diverse cellular structures, such as the mitotic spindle for cell division, the backbone of neurons, and axonemes. To control the architecture of microtubule networks, microtubule-associated proteins (MAPs) and motor proteins regulate microtubule growth, shrinkage, and the transitions between these states. Recent evidence shows that many MAPs exert their effects by selectively binding to distinct conformations of polymerized or unpolymerized αβ-tubulin. The ability of αβ-tubulin to adopt distinct conformations contributes to the intrinsic polymerization dynamics of microtubules. αβ-Tubulin conformation is a fundamental property that MAPs monitor and control to build proper microtubule networks.

scholarly journals Stu2p, the budding yeast member of the conserved Dis1/XMAP215 family of microtubule-associated proteins is a plus end–binding microtubule destabilizer

2003 ◽  
Vol 161 (2) ◽  
pp. 359-369 ◽  
Author(s):  
Mark van Breugel ◽  
David Drechsel ◽  
Anthony Hyman
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Division ◽  
Quantitative Analysis ◽  
Family Member ◽  
Budding Yeast ◽  
Microtubule Dynamics ◽  
Biochemical Activity ◽  
Microtubule Associated Proteins ◽  
Associated Proteins

The Dis1/XMAP215 family of microtubule-associated proteins conserved from yeast to mammals is essential for cell division. XMAP215, the Xenopus member of this family, has been shown to stabilize microtubules in vitro, but other members of this family have not been biochemically characterized. Here we investigate the properties of the Saccharomyces cerevisiae homologue Stu2p in vitro. Surprisingly, Stu2p is a microtubule destabilizer that binds preferentially to microtubule plus ends. Quantitative analysis of microtubule dynamics suggests that Stu2p induces microtubule catastrophes by sterically interfering with tubulin addition to microtubule ends. These results reveal both a new biochemical activity for a Dis1/XMAP215 family member and a novel mechanism for microtubule destabilization.

Characterization of microtubules by dark-field STEM and replication

1991 ◽  
Vol 49 ◽  
pp. 152-153
Author(s):  
S.B. Andrews ◽  
R.D. Leapman ◽  
P.E. Gallant ◽  
T.S. Reese
Keyword(s):  
Protein Interactions ◽  
Low Dose ◽  
Unit Length ◽  
Dark Field ◽  
Carbon Films ◽  
Microtubule Associated Proteins ◽  
Molecular Weights ◽  
Freeze Dried ◽  
Protein Motors ◽  
Associated Proteins

As part of a study on protein interactions involved in microtubule (MT)-based transport, we used the VG HB501 field-emission STEM to obtain low-dose dark-field mass maps of isolated, taxol-stabilized MTs and correlated these micrographs with detailed stereo images from replicas of the same MTs. This approach promises to be useful for determining how protein motors interact with MTs. MTs prepared from bovine and squid brain tubulin were purified and free from microtubule-associated proteins (MAPs). These MTs (0.1-1 mg/ml tubulin) were adsorbed to 3-nm evaporated carbon films supported over Formvar nets on 600-m copper grids. Following adsorption, the grids were washed twice in buffer and then in either distilled water or in isotonic or hypotonic ammonium acetate, blotted, and plunge-frozen in ethane/propane cryogen (ca. -185 C). After cryotransfer into the STEM, specimens were freeze-dried and recooled to ca.-160 C for low-dose (<3000 e/nm2) dark-field mapping. The molecular weights per unit length of MT were determined relative to tobacco mosaic virus standards from elastic scattering intensities. Parallel grids were freeze-dried and rotary shadowed with Pt/C at 14°.

Filaments and membranes in the mitotic apparatus

1983 ◽  
Vol 41 ◽  
pp. 544-547
Author(s):  
Kent McDonald
Keyword(s):  
Intermediate Filaments ◽  
Mitotic Spindle ◽  
Mitotic Apparatus ◽  
Light Microscope Level ◽  
Microtubule Associated Proteins ◽  
Recent Developments ◽  
Associated Proteins ◽  
Force Generator ◽  
Spindle Function ◽  
Antibody Technology

At the light microscope level the recent developments and interest in antibody technology have permitted the localization of certain non-microtubule proteins within the mitotic spindle, e.g., calmodulin, actin, intermediate filaments, protein kinases and various microtubule associated proteins. Also, the use of fluorescent probes like chlorotetracycline suggest the presence of membranes in the spindle. Localization of non-microtubule structures in the spindle at the EM level has been less rewarding. Some mitosis researchers, e.g., Rarer, have maintained that actin is involved in mitosis movements though the bulk of evidence argues against this interpretation. Others suggest that a microtrabecular network such as found in chromatophore granule movement might be a possible force generator but there is little evidence for or against this view. At the level of regulation of spindle function, Harris and more recently Hepler have argued for the importance of studying spindle membranes. Hepler also believes that membranes might play a structural or mechanical role in moving chromosomes.

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”).

Molecular architecture and functions of the neuronal cytoskeleton

1990 ◽  
Vol 48 (3) ◽  
pp. 2-3
Author(s):  
Nobutaka Hirokawa
Keyword(s):  
Major Elements ◽  
Molecular Structures ◽  
Organelle Transport ◽  
Molecular Architecture ◽  
Neuronal Morphogenesis ◽  
Microtubule Associated Proteins ◽  
Associated Proteins ◽  
And Function ◽  
Small Clusters

In this symposium I will present our studies about the molecular architecture and function of the cytomatrix of the nerve cells. The nerve cell is a highly polarized cell composed of highly branched dendrites, cell body, and a single long axon along the direction of the impulse propagation. Each part of the neuron takes characteristic shapes for which the cytoskeleton provides the framework. The neuronal cytoskeletons play important roles on neuronal morphogenesis, organelle transport and the synaptic transmission. In the axon neurofilaments (NF) form dense arrays, while microtubules (MT) are arranged as small clusters among the NFs. On the other hand, MTs are distributed uniformly, whereas NFs tend to run solitarily or form small fascicles in the dendrites Quick freeze deep etch electron microscopy revealed various kinds of strands among MTs, NFs and membranous organelles (MO). These structures form major elements of the cytomatrix in the neuron. To investigate molecular nature and function of these filaments first we studied molecular structures of microtubule associated proteins (MAP1A, MAP1B, MAP2, MAP2C and tau), and microtubules reconstituted from MAPs and tubulin in vitro. These MAPs were all fibrous molecules with different length and formed arm like projections from the microtubule surface.

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