scholarly journals Integrin-linked kinase localizes to the centrosome and regulates mitotic spindle organization

2008 ◽  
Vol 180 (4) ◽  
pp. 681-689 ◽  
Author(s):  
Andrew B. Fielding ◽  
Iveta Dobreva ◽  
Paul C. McDonald ◽  
Leonard J. Foster ◽  
Shoukat Dedhar
Keyword(s):  
Mitotic Spindle ◽  
Protein Complexes ◽  
Focal Adhesions ◽  
Spindle Pole ◽  
Serine Threonine Kinase ◽  
Centrosomal Protein ◽  
Threonine Kinase ◽  
Dna Segregation ◽  
Integrin Linked Kinase ◽  
Mitotic Spindle Assembly

Integrin-linked kinase (ILK) is a serine-threonine kinase and scaffold protein with well defined roles in focal adhesions in integrin-mediated cell adhesion, spreading, migration, and signaling. Using mass spectrometry–based proteomic approaches, we identify centrosomal and mitotic spindle proteins as interactors of ILK. α- and β-tubulin, ch-TOG (XMAP215), and RUVBL1 associate with ILK and colocalize with it to mitotic centrosomes. Inhibition of ILK activity or expression induces profound apoptosis-independent defects in the organization of the mitotic spindle and DNA segregation. ILK fails to localize to the centrosomes of abnormal spindles in RUVBL1-depleted cells. Additionally, depletion of ILK expression or inhibition of its activity inhibits Aurora A–TACC3/ch-TOG interactions, which are essential for spindle pole organization and mitosis. These data demonstrate a critical and unexpected function for ILK in the organization of centrosomal protein complexes during mitotic spindle assembly and DNA segregation.

scholarly journals Beyond focal adhesions: Integrin linked kinase associates with tubulin and regulates mitotic spindle organization

Cell Cycle ◽  
2008 ◽  
Vol 7 (13) ◽  
pp. 1899-1906 ◽  
Author(s):  
Andrew B. Fielding ◽  
Iveta Dobreva ◽  
Shoukat Dedhar
Keyword(s):  
Mitotic Spindle ◽  
Focal Adhesions ◽  
Integrin Linked Kinase

scholarly journals A Drosophila homolog of the Rac- and Cdc42-activated serine/threonine kinase PAK is a potential focal adhesion and focal complex protein that colocalizes with dynamic actin structures.

1996 ◽  
Vol 16 (5) ◽  
pp. 1896-1908 ◽  
Author(s):  
N Harden ◽  
J Lee ◽  
H Y Loh ◽  
Y M Ong ◽  
I Tan ◽  
...  
Keyword(s):  
Focal Adhesion ◽  
Cell Shape ◽  
Focal Adhesions ◽  
Leading Edge ◽  
Epidermal Cells ◽  
Dorsal Closure ◽  
Serine Threonine Kinase ◽  
Threonine Kinase ◽  
Amino Terminal ◽  
Drosophila Homolog

Changes in cell morphology are essential in the development of a multicellular organism. The regulation of the cytoskeleton by the Rho subfamily of small GTP-binding proteins is an important determinant of cell shape. The Rho subfamily has been shown to participate in a variety of morphogenetic processes during Drosophila melanogaster development. We describe here a Drosophila homolog, DPAK, of the serine/threonine kinase PAK, a protein which is a target of the Rho subfamily proteins Rac and Cdc42. Rac, Cdc42, and PAK have previously been implicated in signaling by c-Jun amino-terminal kinases. DPAK bound to activated (GTP-bound) Drosophila Rac (DRacA) and Drosophila Cdc42. Similarities in the distributions of DPAK, integrin, and phosphotyrosine suggested an association of DPAK with focal adhesions and Cdc42- and Rac-induced focal adhesion-like focal complexes. DPAK was elevated in the leading edge of epidermal cells, whose morphological changes drive dorsal closure of the embryo. We have previously shown that the accumulation of cytoskeletal elements initiating cell shape changes in these cells could be inhibited by expression of a dominant-negative DRacA transgene. We show that leading-edge epidermal cells flanking segment borders, which express particularly large amounts of DPAK, undergo transient losses of cytoskeletal structures during dorsal closure. We propose that DPAK may be regulating the cytoskeleton through its association with focal adhesions and focal complexes and may be participating with DRacA in a c-Jun amino-terminal kinase signaling pathway recently demonstrated to be required for dorsal closure.

scholarly journals Targeting Alp7/TACC to the spindle pole body is essential for mitotic spindle assembly in fission yeast

FEBS Letters ◽  
2014 ◽  
Vol 588 (17) ◽  
pp. 2814-2821 ◽  
Author(s):  
Ngang Heok Tang ◽  
Naoyuki Okada ◽  
Chii Shyang Fong ◽  
Kunio Arai ◽  
Masamitsu Sato ◽  
...  
Keyword(s):  
Fission Yeast ◽  
Mitotic Spindle ◽  
Spindle Pole Body ◽  
Spindle Assembly ◽  
Spindle Pole ◽  
Pole Body ◽  
Mitotic Spindle Assembly

scholarly journals Kinetochore-driven formation of kinetochore fibers contributes to spindle assembly during animal mitosis

2004 ◽  
Vol 167 (5) ◽  
pp. 831-840 ◽  
Author(s):  
Helder Maiato ◽  
Conly L. Rieder ◽  
Alexey Khodjakov
Keyword(s):  
Mitotic Spindle ◽  
Spindle Assembly ◽  
Spindle Pole ◽  
S2 Cells ◽  
Spindle Poles ◽  
Drosophila S2 Cells ◽  
Mitotic Spindle Assembly ◽  
Normal Mitosis ◽  
Proper Orientation ◽  
Dependent Mechanism

It is now clear that a centrosome-independent pathway for mitotic spindle assembly exists even in cells that normally possess centrosomes. The question remains, however, whether this pathway only activates when centrosome activity is compromised, or whether it contributes to spindle morphogenesis during a normal mitosis. Here, we show that many of the kinetochore fibers (K-fibers) in centrosomal Drosophila S2 cells are formed by the kinetochores. Initially, kinetochore-formed K-fibers are not oriented toward a spindle pole but, as they grow, their minus ends are captured by astral microtubules (MTs) and transported poleward through a dynein-dependent mechanism. This poleward transport results in chromosome bi-orientation and congression. Furthermore, when individual K-fibers are severed by laser microsurgery, they regrow from the kinetochore outward via MT plus-end polymerization at the kinetochore. Thus, even in the presence of centrosomes, the formation of some K-fibers is initiated by the kinetochores. However, centrosomes facilitate the proper orientation of K-fibers toward spindle poles by integrating them into a common spindle.

Regulation of the cytokinesis cleavage furrow by PKCε

2014 ◽  
Vol 42 (6) ◽  
pp. 1534-1537 ◽  
Author(s):  
Nicola Brownlow ◽  
Tanya Pike ◽  
Victoria Crossland ◽  
Jeroen Claus ◽  
Peter Parker
Keyword(s):  
Cell Cycle ◽  
Actin Binding ◽  
Cleavage Furrow ◽  
Binding Region ◽  
Serine Threonine Kinase ◽  
Threonine Kinase ◽  
Dna Segregation ◽  
Daughter Cells ◽  
Cell Adhesion And Migration ◽  
And Migration

Cytokinesis is the final act of the cell cycle where the replicated DNA and cellular contents are finally split into two daughter cells. This process is very tightly controlled as DNA segregation errors and cytokinesis failure is commonly associated with aneuploidy and aggressive tumours. Protein kinase Cε (PKCε) is a lipid-activated serine/threonine kinase that is part of the PKC superfamily. PKCε plays a complex role in the regulation of migration, adhesion and cytokinesis and in the present article we discuss the interplay between these processes. Integrin-mediated interaction with the actin cytoskeleton is a known regulator of cell adhesion and migration and there is emerging evidence that this pathway may also be essential for cytokinesis. We discuss evidence that a known actin-binding region in PKCε is involved in PKCε-mediated regulation of cytokinesis, providing a link between integrin-mediated stabilization of the cytokinesis furrow and PKCε recruitment.

scholarly journals The APC/C targets the Cep152-Cep63 complex at the centrosome to regulate mitotic spindle assembly

2021 ◽  
Author(s):  
Thomas Tischer ◽  
Jing Yang ◽  
David Barford
Keyword(s):  
Mitotic Spindle ◽  
Spindle Assembly ◽  
Protein Abundance ◽  
Anaphase Promoting Complex ◽  
Mitotic Progression ◽  
Centrosomal Protein ◽  
Temporal Regulation ◽  
Spindle Poles ◽  
Main Protein ◽  
Mitotic Spindle Assembly

The control of protein abundance is a fundamental regulatory mechanism during mitosis. The anaphase promoting complex/cyclosome (APC/C) is the main protein ubiquitin ligase responsible for the temporal regulation of mitotic progression. It has been proposed that the APC/C might fulfil other functions including assembly of the mitotic spindle. Here, we show that the APC/C localizes to centrosomes, the organizers of the eukaryotic microtubule cytoskeleton, specifically during mitosis. Recruitment of the APC/C to spindle poles requires the centrosomal protein Cep152, and we identified Cep152 as both an APC/C interaction partner and as an APC/C substrate. Previous studies showed that Cep152 forms a complex with Cep57 and Cep63. The APC/C-mediated ubiquitination of Cep152 at the centrosome releases Cep57 from this inhibitory complex and enables its interaction with pericentrin, a critical step in promoting microtubule nucleation. Thus, our study extends the function of the APC/C from being a regulator of mitosis to also acting as a positive governor of spindle assembly. The APC/C thereby integrates control of these two important processes in a temporal manner.

scholarly journals CDK5 is a major regulator of the tumor suppressor DLC1

2014 ◽  
Vol 207 (5) ◽  
pp. 627-642 ◽  
Author(s):  
Brajendra K. Tripathi ◽  
Xiaolan Qian ◽  
Philipp Mertins ◽  
Dunrui Wang ◽  
Alex G. Papageorge ◽  
...  
Keyword(s):  
Tumor Suppressor ◽  
Rho Gtpase ◽  
Selective Pressure ◽  
Focal Adhesions ◽  
Tumor Suppressor Protein ◽  
Gtpase Activating Protein ◽  
Serine Threonine Kinase ◽  
Autoinhibitory Domain ◽  
Threonine Kinase ◽  
Important Regulator

DLC1 is a tumor suppressor protein whose full activity depends on its presence at focal adhesions, its Rho–GTPase activating protein (Rho-GAP) function, and its ability to bind several ligands, including tensin and talin. However, the mechanisms that regulate and coordinate these activities remain poorly understood. Here we identify CDK5, a predominantly cytoplasmic serine/threonine kinase, as an important regulator of DLC1 functions. The CDK5 kinase phosphorylates four serines in DLC1 located N-terminal to the Rho-GAP domain. When not phosphorylated, this N-terminal region functions as an autoinhibitory domain that places DLC1 in a closed, inactive conformation by efficiently binding to the Rho-GAP domain. CDK5 phosphorylation reduces this binding and orchestrates the coordinate activation DLC1, including its localization to focal adhesions, its Rho-GAP activity, and its ability to bind tensin and talin. In cancer, these anti-oncogenic effects of CDK5 can provide selective pressure for the down-regulation of DLC1, which occurs frequently in tumors, and can contribute to the pro-oncogenic activity of CDK5 in lung adenocarcinoma.

scholarly journals Theory of cytoskeletal reorganization during crosslinker-mediated mitotic spindle assembly

2018 ◽  
Author(s):  
A. R. Lamson ◽  
C. J. Edelmaier ◽  
M. A. Glaser ◽  
M. D. Betterton
Keyword(s):  
Mitotic Spindle ◽  
Large Scale ◽  
Dynamic Instability ◽  
Kinetic Monte Carlo ◽  
Spindle Assembly ◽  
Spindle Pole ◽  
Balance Model ◽  
Cytoskeletal Reorganization ◽  
Bipolar Spindle ◽  
Mitotic Spindle Assembly

AbstractCells grow, move, and respond to outside stimuli by large-scale cytoskeletal reorganization. A prototypical example of cytoskeletal remodeling is mitotic spindle assembly, during which micro-tubules nucleate, undergo dynamic instability, bundle, and organize into a bipolar spindle. Key mechanisms of this process include regulated filament polymerization, crosslinking, and motor-protein activity. Remarkably, using passive crosslinkers, fission yeast can assemble a bipolar spindle in the absence of motor proteins. We develop a torque-balance model that describes this reorganization due to dynamic microtubule bundles, spindle-pole bodies, the nuclear envelope, and passive crosslinkers to predict spindle-assembly dynamics. We compare these results to those obtained with kinetic Monte Carlo-Brownian dynamics simulations, which include crosslinker-binding kinetics and other stochastic effects. Our results show that rapid crosslinker reorganization to microtubule overlaps facilitates crosslinker-driven spindle assembly, a testable prediction for future experiments. Combining these two modeling techniques, we illustrate a general method for studying cytoskeletal network reorganization.

scholarly journals Mitotic spindle assembly is controlled by the APC/C localized at the centrosome

2020 ◽  
Author(s):  
Thomas Tischer ◽  
Jing Yang ◽  
David Barford
Keyword(s):  
Mitotic Spindle ◽  
Spindle Assembly ◽  
Anaphase Promoting Complex ◽  
Mitotic Progression ◽  
Centrosomal Protein ◽  
Temporal Regulation ◽  
Spindle Poles ◽  
Defective Mutant ◽  
Main Protein ◽  
Mitotic Spindle Assembly

AbstractThe control of protein abundance is a fundamental regulatory mechanism during mitosis. The anaphase promoting complex/cyclosome (APC/C) is the main protein ubiquitin ligase responsible for the temporal regulation of mitotic progression. It has long been speculated that the APC/C might fulfil other functions including assembly of the mitotic spindle. Here, we show that the APC/C localizes to centrosomes, the organizers of the eukaryotic microtubule cytoskeleton, specifically during mitosis. The APC/C is recruited to spindle poles by the centrosomal protein Cep152, and we identified Cep152 as both a novel APC/C interaction partner, and as an APC/C substrate. Importantly, this revealed a mitotic function of Cep152 that is reciprocally regulated by the APC/C. A destruction-defective mutant of Cep152 showed that the timely regulation of Cep152 levels at the centrosome controls spindle assembly and chromosome segregation. The APC/C-mediated degradation of Cep152 at the centrosome releases Cep57 from an inhibitory complex to enable its interaction with pericentrin, a critical step in promoting microtubule nucleation. Thus, our study extends the function of the APC/C from being a regulator of mitosis to also acting as a positive governor of spindle assembly. The APC/C thereby integrates control of these two important processes in a temporal manner.

scholarly journals Ran-GTP is non-essential to activate NuMA for spindle pole focusing, but dynamically polarizes HURP to control mitotic spindle length

2018 ◽  
Author(s):  
Kenta Tsuchiya ◽  
Hisato Hayashi ◽  
Momoko Nishina ◽  
Masako Okumura ◽  
Yoshikatsu Sato ◽  
...  
Keyword(s):  
Mitotic Spindle ◽  
Spindle Assembly ◽  
Nucleocytoplasmic Transport ◽  
Spindle Pole ◽  
Human Cells ◽  
Fiber Formation ◽  
List Type ◽  
Mitotic Spindle Assembly ◽  
Ran Gtp ◽  
Dynamic Microtubule

AbstractDuring mitosis, a bipolar spindle is assembled around chromosomes to efficiently capture chromosomes. Previous work proposed that a chromosome-derived Ran-GTP gradient promotes spindle assembly around chromosomes by liberating spindle assembly factors (SAFs) from inhibitory importins. However, Ran’s dual functions in interphase nucleocytoplasmic transport and mitotic spindle assembly have made it difficult to assess its mitotic roles in somatic cells. Here, using auxin-inducible degron technology in human cells, we developed acute mitotic degradation assays to dissect Ran’s mitotic roles systematically and separately from its interphase function. In contrast to the prevailing model, we found that the Ran pathway is not essential for spindle assembly activities that occur at sites spatially separated from chromosomes, including activating NuMA for spindle pole focusing or for targeting TPX2. In contrast, Ran-GTP is required to localize HURP and HSET specifically at chromosome-proximal regions. We demonstrated that Ran-GTP and importin-β coordinately promote HURP’s dynamic microtubule binding-dissociation cycle near chromosomes, which results in stable kinetochore-fiber formation. Intriguingly, this pathway acts to establish proper spindle length preferentially during prometaphase, rather than metaphase. Together, we propose that the Ran pathway is required to activate SAFs specifically near chromosomes, but not generally during human mitotic spindle assembly. Ran-dependent spindle assembly is likely coupled with parallel pathways to activate SAFs, including NuMA, for spindle pole focusing away from chromosomes.HighlightsUsing auxin-inducible degron technology, we developed mitotic degradation assays for the Ran pathway in human cells.The Ran pathway is non-essential to activate NuMA for spindle pole focusing.The Ran pathway dynamically polarizes HURP and defines mitotic spindle length preferentially during prometaphase.Ran-GTP is required to activate SAFs specifically near chromosomes, but not generally, in human mitotic cells.

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