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Steffen Lawo - One of the best experts on this subject based on the ideXlab platform.
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haus the 8 subunit human augmin complex regulates centrosome and spindle integrity
Current Biology, 2009Co-Authors: Steffen Lawo, Ralf Kittler, Mikhail Bashkurov, Michael Mullin, Mariana Gomez Ferreria, Andrea Tagliaferro, Bianca Habermann, Ina Poser, James R.a. HutchinsAbstract:Summary Background The assembly of a robust microtubule-based mitotic spindle is a prerequisite for the accurate segregation of chromosomes to progeny. Spindle assembly relies on the concerted action of Centrosomes, spindle microtubules, molecular motors, and nonmotor spindle proteins. Results Here we use an RNA-interference screen of the human centrosome proteome to identify novel regulators of spindle assembly. One such regulator is HAUS, an 8-subunit protein complex that shares homology to Drosophila Augmin. HAUS localizes to interphase Centrosomes and to mitotic spindle microtubules, and its disruption induces microtubule-dependent fragmentation of Centrosomes along with an increase in centrosome size. HAUS disruption results in the destabilization of kinetochore microtubules and the eventual formation of multipolar spindles. These severe mitotic defects are alleviated by codepletion of NuMA, indicating that both factors regulate opposing activities. HAUS disruption alters NuMA localization, suggesting that mislocalized NuMA activity contributes to the spindle and centrosome defects observed. Conclusion The human Augmin complex (HAUS) is a critical and evolutionary conserved multisubunit protein complex that regulates centrosome and spindle integrity.
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HAUS, the 8-Subunit Human Augmin Complex, Regulates Centrosome and Spindle Integrity
Current Biology, 2009Co-Authors: Steffen Lawo, Ralf Kittler, Mikhail Bashkurov, Michael Mullin, Mariana Gomez Ferreria, Andrea Tagliaferro, James R.a. Hutchins, Bianca Habermann, Ina Poser, Björn HegemannAbstract:Background: The assembly of a robust microtubule-based mitotic spindle is a prerequisite for the accurate segregation of chromosomes to progeny. Spindle assembly relies on the concerted action of Centrosomes, spindle microtubules, molecular motors, and nonmotor spindle proteins. Results: Here we use an RNA-interference screen of the human centrosome proteome to identify novel regulators of spindle assembly. One such regulator is HAUS, an 8-subunit protein complex that shares homology to Drosophila Augmin. HAUS localizes to interphase Centrosomes and to mitotic spindle microtubules, and its disruption induces microtubule-dependent fragmentation of Centrosomes along with an increase in centrosome size. HAUS disruption results in the destabilization of kinetochore microtubules and the eventual formation of multipolar spindles. These severe mitotic defects are alleviated by codepletion of NuMA, indicating that both factors regulate opposing activities. HAUS disruption alters NuMA localization, suggesting that mislocalized NuMA activity contributes to the spindle and centrosome defects observed. Conclusion: The human Augmin complex (HAUS) is a critical and evolutionary conserved multisubunit protein complex that regulates centrosome and spindle integrity. © 2009 Elsevier Ltd. All rights reserved.
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the mammalian spd 2 ortholog cep192 regulates centrosome biogenesis
Current Biology, 2008Co-Authors: Steffen Lawo, Ralf Kittler, Alison Ralph, Laurence Pelletier, Anthony A. Hyman, Constance Richter, Deborah Pinchev, Alexander W Bird, Thomas MullerreichertAbstract:Summary Centrosomes are the major microtubule-organizing centers of mammalian cells. They are composed of a centriole pair and surrounding microtubule-nucleating material termed pericentriolar material (PCM) [1]. Bipolar mitotic spindle assembly relies on two intertwined processes: centriole duplication and centrosome maturation. In the first process, the single interphase centrosome duplicates in a tightly regulated manner so that two Centrosomes are present in mitosis [2, 3]. In the second process, the two Centrosomes increase in size and microtubule nucleation capacity through PCM recruitment, a process referred to as centrosome maturation [4]. Failure to properly orchestrate centrosome duplication and maturation is inevitably linked to spindle defects, which can result in aneuploidy and promote cancer progression [5]. It has been proposed that centriole assembly during duplication relies on both PCM and centriole proteins, raising the possibility that centriole duplication depends on PCM recruitment [6]. In support of this model, C. elegans SPD-2 and mammalian NEDD-1 (GCP-WD) are key regulators of both these processes [7–13]. SPD-2 protein sequence homologs have been identified in flies, mice, and humans, but their roles in centrosome biogenesis until now have remained unclear [10, 14–16]. Here, we show that Cep192, the human homolog of C. elegans and D. melanogaster SPD-2, is a major regulator of PCM recruitment, centrosome maturation, and centriole duplication in mammalian cells. We propose a model in which Cep192 and Pericentrin are mutually dependent for their localization to mitotic Centrosomes during centrosome maturation. Both proteins are then required for NEDD-1 recruitment and the subsequent assembly of γ-TuRCs and other factors into fully functional Centrosomes.
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The Mammalian SPD-2 Ortholog Cep192 Regulates Centrosome Biogenesis
Current Biology, 2008Co-Authors: Fei Zhu, Steffen Lawo, Ralf Kittler, Alex Bird, Alison Ralph, Thomas Müller-reichert, Anthony A. Hyman, Constance Richter, Deborah Pinchev, Laurence PelletierAbstract:Centrosomes are the major microtubule-organizing centers of mammalian cells. They are composed of a centriole pair and surrounding microtubule-nucleating material termed pericentriolar material (PCM) [1]. Bipolar mitotic spindle assembly relies on two intertwined processes: centriole duplication and centrosome maturation. In the first process, the single interphase centrosome duplicates in a tightly regulated manner so that two Centrosomes are present in mitosis [2, 3]. In the second process, the two Centrosomes increase in size and microtubule nucleation capacity through PCM recruitment, a process referred to as centrosome maturation [4]. Failure to properly orchestrate centrosome duplication and maturation is inevitably linked to spindle defects, which can result in aneuploidy and promote cancer progression [5]. It has been proposed that centriole assembly during duplication relies on both PCM and centriole proteins, raising the possibility that centriole duplication depends on PCM recruitment [6]. In support of this model, C. elegans SPD-2 and mammalian NEDD-1 (GCP-WD) are key regulators of both these processes [7-13]. SPD-2 protein sequence homologs have been identified in flies, mice, and humans, but their roles in centrosome biogenesis until now have remained unclear [10, 14-16]. Here, we show that Cep192, the human homolog of C. elegans and D. melanogaster SPD-2, is a major regulator of PCM recruitment, centrosome maturation, and centriole duplication in mammalian cells. We propose a model in which Cep192 and Pericentrin are mutually dependent for their localization to mitotic Centrosomes during centrosome maturation. Both proteins are then required for NEDD-1 recruitment and the subsequent assembly of γ-TuRCs and other factors into fully functional Centrosomes. © 2008 Elsevier Ltd. All rights reserved.
Laurence Pelletier - One of the best experts on this subject based on the ideXlab platform.
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Nek5 promotes centrosome integrity in interphase and loss of centrosome cohesion in mitosis
Journal of Cell Biology, 2015Co-Authors: Suzanna L Prosser, Navdeep K. Sahota, Laurence Pelletier, Ciaran G Morrison, Andrew M. FryAbstract:Nek5 is a poorly characterized member of the NIMA-related kinase family, other members of which play roles in cell cycle progression and primary cilia function. Here, we show that Nek5, similar to Nek2, localizes to the proximal ends of centrioles. Depletion of Nek5 or overexpression of kinase-inactive Nek5 caused unscheduled separation of Centrosomes in interphase, a phenotype also observed upon overexpression of active Nek2. However, separated Centrosomes that resulted from Nek5 depletion remained relatively close together, exhibited excess recruitment of the centrosome linker protein rootletin, and had reduced levels of Nek2. In addition, Nek5 depletion led to loss of PCM components, including γ-tubulin, pericentrin, and Cdk5Rap2, with Centrosomes exhibiting reduced microtubule nucleation. Upon mitotic entry, Nek5-depleted cells inappropriately retained centrosome linker components and exhibited delayed centrosome separation and defective chromosome segregation. Hence, Nek5 is required for the loss of centrosome linker proteins and enhanced microtubule nucleation that lead to timely centrosome separation and bipolar spindle formation in mitosis.
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Centrosome asymmetry and inheritance during animal development
Current Opinion in Cell Biology, 2012Co-Authors: Laurence Pelletier, Yukiko M. YamashitaAbstract:The centrosome is a subcellular organelle that is responsible for the majority of microtubule organization. Through this ability, the centrosome is involved in cell division, migration, and polarization. Recent studies have revealed intriguing asymmetries between mother and daughter centrioles as well as between mother and daughter Centrosomes, and the involvement of such asymmetries in multiple cellular and developmental processes. This review aims to summarize recent discoveries on such asymmetries in centrioles/Centrosomes and the potential implication of their inheritance patterns during cell division and development.
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Centrosome asymmetry and inheritance during animal development
Current Opinion in Cell Biology, 2012Co-Authors: Laurence Pelletier, Yukiko M. YamashitaAbstract:The centrosome is a subcellular organelle that is responsible for the majority of microtubule organization. Through this ability, the centrosome is involved in cell division, migration, and polarization. Recent studies have revealed intriguing asymmetries between mother and daughter centrioles as well as between mother and daughter Centrosomes, and the involvement of such asymmetries in multiple cellular and developmental processes. This review aims to summarize recent discoveries on such asymmetries in centrioles/Centrosomes and the potential implication of their inheritance patterns during cell division and development. © 2012 Elsevier Ltd.
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the mammalian spd 2 ortholog cep192 regulates centrosome biogenesis
Current Biology, 2008Co-Authors: Steffen Lawo, Ralf Kittler, Alison Ralph, Laurence Pelletier, Anthony A. Hyman, Constance Richter, Deborah Pinchev, Alexander W Bird, Thomas MullerreichertAbstract:Summary Centrosomes are the major microtubule-organizing centers of mammalian cells. They are composed of a centriole pair and surrounding microtubule-nucleating material termed pericentriolar material (PCM) [1]. Bipolar mitotic spindle assembly relies on two intertwined processes: centriole duplication and centrosome maturation. In the first process, the single interphase centrosome duplicates in a tightly regulated manner so that two Centrosomes are present in mitosis [2, 3]. In the second process, the two Centrosomes increase in size and microtubule nucleation capacity through PCM recruitment, a process referred to as centrosome maturation [4]. Failure to properly orchestrate centrosome duplication and maturation is inevitably linked to spindle defects, which can result in aneuploidy and promote cancer progression [5]. It has been proposed that centriole assembly during duplication relies on both PCM and centriole proteins, raising the possibility that centriole duplication depends on PCM recruitment [6]. In support of this model, C. elegans SPD-2 and mammalian NEDD-1 (GCP-WD) are key regulators of both these processes [7–13]. SPD-2 protein sequence homologs have been identified in flies, mice, and humans, but their roles in centrosome biogenesis until now have remained unclear [10, 14–16]. Here, we show that Cep192, the human homolog of C. elegans and D. melanogaster SPD-2, is a major regulator of PCM recruitment, centrosome maturation, and centriole duplication in mammalian cells. We propose a model in which Cep192 and Pericentrin are mutually dependent for their localization to mitotic Centrosomes during centrosome maturation. Both proteins are then required for NEDD-1 recruitment and the subsequent assembly of γ-TuRCs and other factors into fully functional Centrosomes.
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The Mammalian SPD-2 Ortholog Cep192 Regulates Centrosome Biogenesis
Current Biology, 2008Co-Authors: Fei Zhu, Steffen Lawo, Ralf Kittler, Alex Bird, Alison Ralph, Thomas Müller-reichert, Anthony A. Hyman, Constance Richter, Deborah Pinchev, Laurence PelletierAbstract:Centrosomes are the major microtubule-organizing centers of mammalian cells. They are composed of a centriole pair and surrounding microtubule-nucleating material termed pericentriolar material (PCM) [1]. Bipolar mitotic spindle assembly relies on two intertwined processes: centriole duplication and centrosome maturation. In the first process, the single interphase centrosome duplicates in a tightly regulated manner so that two Centrosomes are present in mitosis [2, 3]. In the second process, the two Centrosomes increase in size and microtubule nucleation capacity through PCM recruitment, a process referred to as centrosome maturation [4]. Failure to properly orchestrate centrosome duplication and maturation is inevitably linked to spindle defects, which can result in aneuploidy and promote cancer progression [5]. It has been proposed that centriole assembly during duplication relies on both PCM and centriole proteins, raising the possibility that centriole duplication depends on PCM recruitment [6]. In support of this model, C. elegans SPD-2 and mammalian NEDD-1 (GCP-WD) are key regulators of both these processes [7-13]. SPD-2 protein sequence homologs have been identified in flies, mice, and humans, but their roles in centrosome biogenesis until now have remained unclear [10, 14-16]. Here, we show that Cep192, the human homolog of C. elegans and D. melanogaster SPD-2, is a major regulator of PCM recruitment, centrosome maturation, and centriole duplication in mammalian cells. We propose a model in which Cep192 and Pericentrin are mutually dependent for their localization to mitotic Centrosomes during centrosome maturation. Both proteins are then required for NEDD-1 recruitment and the subsequent assembly of γ-TuRCs and other factors into fully functional Centrosomes. © 2008 Elsevier Ltd. All rights reserved.
Ralf Kittler - One of the best experts on this subject based on the ideXlab platform.
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haus the 8 subunit human augmin complex regulates centrosome and spindle integrity
Current Biology, 2009Co-Authors: Steffen Lawo, Ralf Kittler, Mikhail Bashkurov, Michael Mullin, Mariana Gomez Ferreria, Andrea Tagliaferro, Bianca Habermann, Ina Poser, James R.a. HutchinsAbstract:Summary Background The assembly of a robust microtubule-based mitotic spindle is a prerequisite for the accurate segregation of chromosomes to progeny. Spindle assembly relies on the concerted action of Centrosomes, spindle microtubules, molecular motors, and nonmotor spindle proteins. Results Here we use an RNA-interference screen of the human centrosome proteome to identify novel regulators of spindle assembly. One such regulator is HAUS, an 8-subunit protein complex that shares homology to Drosophila Augmin. HAUS localizes to interphase Centrosomes and to mitotic spindle microtubules, and its disruption induces microtubule-dependent fragmentation of Centrosomes along with an increase in centrosome size. HAUS disruption results in the destabilization of kinetochore microtubules and the eventual formation of multipolar spindles. These severe mitotic defects are alleviated by codepletion of NuMA, indicating that both factors regulate opposing activities. HAUS disruption alters NuMA localization, suggesting that mislocalized NuMA activity contributes to the spindle and centrosome defects observed. Conclusion The human Augmin complex (HAUS) is a critical and evolutionary conserved multisubunit protein complex that regulates centrosome and spindle integrity.
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HAUS, the 8-Subunit Human Augmin Complex, Regulates Centrosome and Spindle Integrity
Current Biology, 2009Co-Authors: Steffen Lawo, Ralf Kittler, Mikhail Bashkurov, Michael Mullin, Mariana Gomez Ferreria, Andrea Tagliaferro, James R.a. Hutchins, Bianca Habermann, Ina Poser, Björn HegemannAbstract:Background: The assembly of a robust microtubule-based mitotic spindle is a prerequisite for the accurate segregation of chromosomes to progeny. Spindle assembly relies on the concerted action of Centrosomes, spindle microtubules, molecular motors, and nonmotor spindle proteins. Results: Here we use an RNA-interference screen of the human centrosome proteome to identify novel regulators of spindle assembly. One such regulator is HAUS, an 8-subunit protein complex that shares homology to Drosophila Augmin. HAUS localizes to interphase Centrosomes and to mitotic spindle microtubules, and its disruption induces microtubule-dependent fragmentation of Centrosomes along with an increase in centrosome size. HAUS disruption results in the destabilization of kinetochore microtubules and the eventual formation of multipolar spindles. These severe mitotic defects are alleviated by codepletion of NuMA, indicating that both factors regulate opposing activities. HAUS disruption alters NuMA localization, suggesting that mislocalized NuMA activity contributes to the spindle and centrosome defects observed. Conclusion: The human Augmin complex (HAUS) is a critical and evolutionary conserved multisubunit protein complex that regulates centrosome and spindle integrity. © 2009 Elsevier Ltd. All rights reserved.
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the mammalian spd 2 ortholog cep192 regulates centrosome biogenesis
Current Biology, 2008Co-Authors: Steffen Lawo, Ralf Kittler, Alison Ralph, Laurence Pelletier, Anthony A. Hyman, Constance Richter, Deborah Pinchev, Alexander W Bird, Thomas MullerreichertAbstract:Summary Centrosomes are the major microtubule-organizing centers of mammalian cells. They are composed of a centriole pair and surrounding microtubule-nucleating material termed pericentriolar material (PCM) [1]. Bipolar mitotic spindle assembly relies on two intertwined processes: centriole duplication and centrosome maturation. In the first process, the single interphase centrosome duplicates in a tightly regulated manner so that two Centrosomes are present in mitosis [2, 3]. In the second process, the two Centrosomes increase in size and microtubule nucleation capacity through PCM recruitment, a process referred to as centrosome maturation [4]. Failure to properly orchestrate centrosome duplication and maturation is inevitably linked to spindle defects, which can result in aneuploidy and promote cancer progression [5]. It has been proposed that centriole assembly during duplication relies on both PCM and centriole proteins, raising the possibility that centriole duplication depends on PCM recruitment [6]. In support of this model, C. elegans SPD-2 and mammalian NEDD-1 (GCP-WD) are key regulators of both these processes [7–13]. SPD-2 protein sequence homologs have been identified in flies, mice, and humans, but their roles in centrosome biogenesis until now have remained unclear [10, 14–16]. Here, we show that Cep192, the human homolog of C. elegans and D. melanogaster SPD-2, is a major regulator of PCM recruitment, centrosome maturation, and centriole duplication in mammalian cells. We propose a model in which Cep192 and Pericentrin are mutually dependent for their localization to mitotic Centrosomes during centrosome maturation. Both proteins are then required for NEDD-1 recruitment and the subsequent assembly of γ-TuRCs and other factors into fully functional Centrosomes.
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The Mammalian SPD-2 Ortholog Cep192 Regulates Centrosome Biogenesis
Current Biology, 2008Co-Authors: Fei Zhu, Steffen Lawo, Ralf Kittler, Alex Bird, Alison Ralph, Thomas Müller-reichert, Anthony A. Hyman, Constance Richter, Deborah Pinchev, Laurence PelletierAbstract:Centrosomes are the major microtubule-organizing centers of mammalian cells. They are composed of a centriole pair and surrounding microtubule-nucleating material termed pericentriolar material (PCM) [1]. Bipolar mitotic spindle assembly relies on two intertwined processes: centriole duplication and centrosome maturation. In the first process, the single interphase centrosome duplicates in a tightly regulated manner so that two Centrosomes are present in mitosis [2, 3]. In the second process, the two Centrosomes increase in size and microtubule nucleation capacity through PCM recruitment, a process referred to as centrosome maturation [4]. Failure to properly orchestrate centrosome duplication and maturation is inevitably linked to spindle defects, which can result in aneuploidy and promote cancer progression [5]. It has been proposed that centriole assembly during duplication relies on both PCM and centriole proteins, raising the possibility that centriole duplication depends on PCM recruitment [6]. In support of this model, C. elegans SPD-2 and mammalian NEDD-1 (GCP-WD) are key regulators of both these processes [7-13]. SPD-2 protein sequence homologs have been identified in flies, mice, and humans, but their roles in centrosome biogenesis until now have remained unclear [10, 14-16]. Here, we show that Cep192, the human homolog of C. elegans and D. melanogaster SPD-2, is a major regulator of PCM recruitment, centrosome maturation, and centriole duplication in mammalian cells. We propose a model in which Cep192 and Pericentrin are mutually dependent for their localization to mitotic Centrosomes during centrosome maturation. Both proteins are then required for NEDD-1 recruitment and the subsequent assembly of γ-TuRCs and other factors into fully functional Centrosomes. © 2008 Elsevier Ltd. All rights reserved.
Anthony A. Hyman - One of the best experts on this subject based on the ideXlab platform.
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soluble tubulin is locally enriched at mitotic Centrosomes in c elegans
bioRxiv, 2019Co-Authors: Johannes Baumgart, Anthony A. Hyman, Marcel Kirchner, Stefanie Redemann, Jeffrey B Woodruff, Jeanmarc Verbavatz, Frank Julicher, Thomas Muellerreichert, Jan BruguesAbstract:During mitosis, the centrosome expands its capacity to nucleate microtubules. Understanding the mechanisms of centrosomal microtubule nucleation is, however, constrained by a lack of knowledge of the amount of soluble and polymer tubulin at mitotic Centrosomes. Here we combined light microscopy and serial-section electron tomography to measure the amount of dimer and polymer at mitotic Centrosomes in early C. elegans embryos. We show that a C. elegans one-cell stage centrosome at metaphase contains more than ten thousand microtubules with a total polymer concentration of 230 M. Centrosomes concentrate soluble /{beta} tubulin by about tenfold over the cytoplasm, reaching peak values of 470 M, giving a combined total monomer and polymer tubulin concentration at Centrosomes of up to 660 M. These findings support in vitro data suggesting that microtubule nucleation in C. elegans Centrosomes is driven in part by concentrating soluble tubulin.
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Centrosomes are autocatalytic droplets of pericentriolar material organized by centrioles
Proceedings of the National Academy of Sciences of the United States of America, 2014Co-Authors: David Zwicker, Anthony A. Hyman, Steffen Jaensch, Markus Decker, Frank JulicherAbstract:Centrosomes are highly dynamic, spherical organelles without a membrane. Their physical nature and their assembly are not understood. Using the concept of phase separation, we propose a theoretical description of Centrosomes as liquid droplets. In our model, centrosome material occurs in a form soluble in the cytosol and a form that tends to undergo phase separation from the cytosol. We show that an autocatalytic chemical transition between these forms accounts for the temporal evolution observed in experiments. Interestingly, the nucleation of Centrosomes can be controlled by an enzymatic activity of the centrioles, which are present at the core of all Centrosomes. This nonequilibrium feature also allows for multiple stable Centrosomes, a situation that is unstable in equilibrium phase separation. Our theory explains the growth dynamics of Centrosomes for all cell sizes down to the eight-cell stage of the Caenorhabditis elegans embryo, and it also accounts for data acquired in experiments with aberrant numbers of Centrosomes and altered cell volumes. Furthermore, the model can describe unequal centrosome sizes observed in cells with perturbed centrioles. We also propose an interpretation of the molecular details of the involved proteins in the case of C. elegans. Our example suggests a general picture of the organization of membraneless organelles.
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Limiting Amounts of Centrosome Material Set Centrosome Size in C. elegans Embryos
Current Biology, 2011Co-Authors: Markus Decker, Steffen Jaensch, Eugene W Myers, Andrei Pozniakovsky, Andrea Zinke, Kevin F. O'connell, Wolfgang Zachariae, Anthony A. HymanAbstract:BACKGROUND: The ways in which cells set the size of intracellular structures is an important but largely unsolved problem [1]. Early embryonic divisions pose special problems in this regard. Many checkpoints common in somatic cells are missing from these divisions, which are characterized by rapid reductions in cell size and short cell cycles [2]. Embryonic cells must therefore possess simple and robust mechanisms that allow the size of many of their intracellular structures to rapidly scale with cell size. RESULTS: Here, we study the mechanism by which one structure, the centrosome, scales in size during the early embryonic divisions of C. elegans. We show that centrosome size is directly related to cell size and is independent of lineage. Two findings suggest that the total amount of maternally supplied centrosome proteins could limit centrosome size. First, the combined volume of all Centrosomes formed at any one time in the developing embryo is constant. Second, the total volume of Centrosomes in any one cell is independent of centrosome number. By increasing the amount of centrosome proteins in the cell, we provide evidence that one component that limits centrosome size is the conserved pericentriolar material protein SPD-2 [3], which we show binds to and targets polo-like kinase 1 [3, 4] to Centrosomes. CONCLUSIONS: We propose a limiting component hypothesis, in which the volume of the cell sets centrosome size by limiting the total amount of centrosome components. This idea could be a general mechanism for setting the size of intracellular organelles during development.
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automated tracking and analysis of Centrosomes in early caenorhabditis elegans embryos
Bioinformatics, 2010Co-Authors: Steffen Jaensch, Anthony A. Hyman, Markus Decker, Eugene W MyersAbstract:Motivation: The centrosome is a dynamic structure in animal cells that serves as a microtubule organizing center during mitosis and also regulates cell-cycle progression and sets polarity cues. Automated and reliable tracking of Centrosomes is essential for genetic screens that study the process of centrosome assembly and maturation in the nematode Caenorhabditis elegans. Results: We have developed a fully automatic system for tracking and measuring fluorescently labeled Centrosomes in 3D time-lapse images of early C.elegans embryos. Using a spinning disc microscope, we monitor the centrosome cycle in living embryos from the 1-up to the 16-cell stage at imaging intervals between 30 and 50 s. After establishing the centrosome trajectories with a novel method involving two layers of inference, we also automatically detect the nuclear envelope breakdown in each cell division and recognize the identities of the Centrosomes based on the invariant cell lineage of C.elegans. To date, we have tracked Centrosomes in over 500 wild type and mutant embryos with almost no manual correction required. Availability: The centrosome tracking software along with test data is freely available at http://publications.mpi-cbg.de/itemPublication.html?documentId=4082 Contact: jaensch@mpi-cbg.de
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the mammalian spd 2 ortholog cep192 regulates centrosome biogenesis
Current Biology, 2008Co-Authors: Steffen Lawo, Ralf Kittler, Alison Ralph, Laurence Pelletier, Anthony A. Hyman, Constance Richter, Deborah Pinchev, Alexander W Bird, Thomas MullerreichertAbstract:Summary Centrosomes are the major microtubule-organizing centers of mammalian cells. They are composed of a centriole pair and surrounding microtubule-nucleating material termed pericentriolar material (PCM) [1]. Bipolar mitotic spindle assembly relies on two intertwined processes: centriole duplication and centrosome maturation. In the first process, the single interphase centrosome duplicates in a tightly regulated manner so that two Centrosomes are present in mitosis [2, 3]. In the second process, the two Centrosomes increase in size and microtubule nucleation capacity through PCM recruitment, a process referred to as centrosome maturation [4]. Failure to properly orchestrate centrosome duplication and maturation is inevitably linked to spindle defects, which can result in aneuploidy and promote cancer progression [5]. It has been proposed that centriole assembly during duplication relies on both PCM and centriole proteins, raising the possibility that centriole duplication depends on PCM recruitment [6]. In support of this model, C. elegans SPD-2 and mammalian NEDD-1 (GCP-WD) are key regulators of both these processes [7–13]. SPD-2 protein sequence homologs have been identified in flies, mice, and humans, but their roles in centrosome biogenesis until now have remained unclear [10, 14–16]. Here, we show that Cep192, the human homolog of C. elegans and D. melanogaster SPD-2, is a major regulator of PCM recruitment, centrosome maturation, and centriole duplication in mammalian cells. We propose a model in which Cep192 and Pericentrin are mutually dependent for their localization to mitotic Centrosomes during centrosome maturation. Both proteins are then required for NEDD-1 recruitment and the subsequent assembly of γ-TuRCs and other factors into fully functional Centrosomes.
David Pellman - One of the best experts on this subject based on the ideXlab platform.
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direct microtubule binding by myosin 10 orients Centrosomes toward retraction fibers and subcortical actin clouds
Developmental Cell, 2015Co-Authors: Mijung Kwon, David Pellman, Maria Bagonis, Gaudenz DanuserAbstract:Summary Positioning of Centrosomes is vital for cell division and development. In metazoan cells, spindle positioning is controlled by a dynamic pool of subcortical actin that organizes in response to the position of retraction fibers. These actin "clouds" are proposed to generate pulling forces on Centrosomes and mediate spindle orientation. However, the motors that pull astral microtubules toward these actin structures are not known. Here, we report that the unconventional myosin, Myo10, couples actin-dependent forces from retraction fibers and subcortical actin clouds to Centrosomes. Myo10-mediated centrosome positioning requires its direct microtubule binding. Computational image analysis of large microtubule populations reveals a direct effect of Myo10 on microtubule dynamics and microtubule-cortex interactions. Myo10's role in centrosome positioning is distinct from, but overlaps with, that of dynein. Thus, Myo10 plays a key role in integrating the actin and microtubule cytoskeletons to position Centrosomes and mitotic spindles.
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abstract c65 mechanisms to maintain extra Centrosomes in cancer cells
Cancer Research, 2009Co-Authors: Susana A Godinho, Mijung Kwon, Neil J Ganem, David PellmanAbstract:Multiple Centrosomes in tumor cells create the potential for multipolar divisions that can lead to aneuploidy and cell death. Nevertheless, many cancer cells successfully divide because of mechanisms that suppress multipolar mitoses. Using a genome‐wide RNAi screen in Drosophila S2 cells, we defined several mechanisms that suppress multipolar mitoses. We also found that HSET, a normally non‐essential kinesin motor was essential for the viability of cancer cells containing extra Centrosomes. Interestingly, using fibronectin micropatterns, we found that interphase cell shape and adhesion pattern can determine the success of the subsequent mitosis in cells with extra Centrosomes. Thus, cell adhesion is an important morphological feature that contributes to centrosome clustering. Importantly, during tumor progression, changes in cell architecture and adhesion patterns, such as loss of E‐cadherin and acquisition of an elongated cell shape, are often observed. This is referred to as the epithelial‐to‐mesenchymal transition (EMT). The presence of extra Centrosomes is often correlated with more malignant tumors, which lost their epithelial phenotype most likely through EMT. Thus, we hypothesized that the ability of cells to cluster extra Centrosomes varies between epithelial cells and non‐epithelial cells. To test this idea we used a panel of non‐transformed mammalian epithelial and non‐epithelial cell lines and quantified their ability to cluster extra Centrosomes. We treated cells with DCB to generate tetraploid cells containing extra Centrosomes and followed them by live‐cell imaging. We found that non‐epithelial cells cluster their extra Centrosomes much more efficiently than epithelial cells. This finding suggests that loss of cell‐cell adhesion might facilitate centrosome clustering. Consistent with this idea, our preliminary data indicate that induction of EMT in the epithelial cell lines MCF10A and MDCK increases the number of tetraploid cells that undergo a bipolar mitosis. We propose that changes that take place during tumor progression, such as loss of cell‐cell adhesion, might facilitate centrosome clustering and therefore increase the ability of cancer cells to maintain extra Centrosomes. We are currently investigating the nature of the changes that occur during EMT that facilitate centrosome clustering. Citation Information: Cancer Res 2009;69(23 Suppl):C65.
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Centrosomes and cancer how cancer cells divide with too many Centrosomes
Cancer and Metastasis Reviews, 2009Co-Authors: Susana A Godinho, Mijung Kwon, David PellmanAbstract:Precise control of centrosome number is crucial for bipolar spindle assembly and accurate transmission of genetic material to daughter cells. Failure to properly control centrosome number results in supernumerary Centrosomes, which are frequently found in cancer cells. This presents a paradox: during mitosis, cells with more than two Centrosomes are prone to multipolar mitoses and cell death, however, cancer cells possessing extra Centrosomes usually divide successfully. One mechanism frequently utilized by cancer cells to escape death caused by multipolar mitoses is the clustering of supernumerary Centrosomes into bipolar arrays. An understanding of the molecular mechanisms by which cancer cells can suppress multipolar mitoses is beginning to emerge. Here, we review what’s currently known about centrosome clustering mechanisms and discuss potential strategies to target these mechanisms for the selective killing of cancer cells.