1
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Gomes Paim LM, Bechstedt S. Regulation of microtubule growth rates and their impact on chromosomal instability. Cell Cycle 2025:1-20. [PMID: 40260826 DOI: 10.1080/15384101.2025.2485842] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2024] [Revised: 01/15/2025] [Accepted: 01/16/2025] [Indexed: 04/24/2025] Open
Abstract
Microtubules are polymers of α/β tubulin dimers that build the mitotic spindle, which segregates duplicated chromosomes during cell division. Microtubule function is governed by dynamic instability, whereby cycles of growth and shrinkage contribute to the forces necessary for chromosome movement. Regulation of microtubule growth velocity requires cell cycle-dependent changes in expression, localization and activity of microtubule-associated proteins (MAPs) as well as tubulin post-translational modifications that modulate microtubule dynamics. It has become clear that optimal microtubule growth velocities are required for proper chromosome segregation and ploidy maintenance. Suboptimal microtubule growth rates can result from altered activity of MAPs and could lead to aneuploidy, possibly by disrupting the establishment of microtubule bundles at kinetochores and altering the mechanical forces required for sister chromatid segregation. Future work using high-resolution, low-phototoxicity microscopy and novel fluorescent markers will be invaluable in obtaining deeper mechanistic insights into how microtubule processes contribute to chromosome segregation.
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Affiliation(s)
| | - Susanne Bechstedt
- Department of Anatomy and Cell Biology, McGill University, Montréal, Canada
- Centre de Recherche en Biologie Structurale (CRBS), McGill University, Montréal, Canada
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2
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Wang S, Xue D. Asymmetric partitioning of persistent paternal mitochondria during cell divisions safeguards embryo development and mitochondrial inheritance. Dev Cell 2025:S1534-5807(25)00033-4. [PMID: 39904343 DOI: 10.1016/j.devcel.2025.01.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2024] [Revised: 12/17/2024] [Accepted: 01/15/2025] [Indexed: 02/06/2025]
Abstract
Most eukaryotes inherit only maternal mitochondria. The reasons for paternal mitochondrial elimination and the impacts of persistent paternal mitochondria on animals remain elusive. We show that undegraded paternal mitochondria in autophagy-deficient C. elegans embryos are gradually excluded from germ blastomeres through asymmetric partitioning during cell divisions. The embryonic cortical flow drives anterior-directed movements of paternal mitochondria and contributes to their asymmetric apportioning between two daughter blastomeres. By contrast, autophagosome-enclosed paternal mitochondria cluster around and segregate with centrosomes during mitosis and are rapidly degraded through lysosomes concentrated near centrosomes. Failure to exclude persistent paternal mitochondria from the germ blastomere at first cleavage causes their enrichment in the descendant endomesodermal (EMS) blastomere, leading to elevated reactive oxygen species levels, elongated EMS lineage durations, and increased embryonic lethality, which antioxidant treatments can suppress. Thus, regulated paternal mitochondrial distribution away from germ blastomeres is a fail-safe mechanism, protecting embryo development and maternal mitochondrial inheritance.
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Affiliation(s)
- Songyun Wang
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO 80309, USA
| | - Ding Xue
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO 80309, USA.
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3
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Sengupta S, Sami AB, Gatlin JC, Levy DL. Proteasome inhibition induces microtubule-dependent changes in nuclear morphology. iScience 2025; 28:111550. [PMID: 39811669 PMCID: PMC11729685 DOI: 10.1016/j.isci.2024.111550] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2024] [Revised: 10/12/2024] [Accepted: 12/04/2024] [Indexed: 01/16/2025] Open
Abstract
Cancers and neurodegenerative disorders are associated with both disrupted proteostasis and altered nuclear morphology. Determining if changes in nuclear morphology contribute to pathology requires an understanding of the underlying mechanisms, which are difficult to elucidate in cells where pleiotropic effects of altering proteostasis might indirectly influence nuclear morphology. To investigate direct effects, we studied nuclei assembled in Xenopus egg extract where potentially confounding effects of transcription, translation, cell cycle progression, and actin dynamics are absent. We report that proteasome inhibition causes acute microtubule-dependent changes in nuclear morphology and stability and altered microtubule dynamics and organization. Proteomic analysis of proteasome-inhibited extracts identified an increased abundance of microtubule nucleator TubGCP6, and TubGCP6 depletion partially rescued nuclear morphology. Key results were confirmed in HeLa cells. We propose that accumulation of TubGCP6 leads to altered microtubule dynamics proximal to the nucleus, producing forces that deform the nucleus and impact nuclear morphology and integrity.
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Affiliation(s)
- Sourabh Sengupta
- Department of Molecular Biology, University of Wyoming, Laramie, WY 82071, USA
| | | | - Jesse C. Gatlin
- Department of Molecular Biology, University of Wyoming, Laramie, WY 82071, USA
| | - Daniel L. Levy
- Department of Molecular Biology, University of Wyoming, Laramie, WY 82071, USA
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4
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Zimyanin V, Magaj M, Manzi NI, Yu CH, Gibney T, Chen YZ, Basaran M, Horton X, Siller K, Pani A, Needleman D, Dickinson DJ, Redemann S. Chromokinesin Klp-19 regulates microtubule overlap and dynamics during anaphase in C. elegans. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.10.26.564275. [PMID: 37961478 PMCID: PMC10634869 DOI: 10.1101/2023.10.26.564275] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
Recent studies have highlighted the significance of the spindle midzone, the region between the segregating chromosomes, in ensuring proper chromosome segregation. By combining 3D electron tomography, cutting-edge light microscopy and a novel single cell in vitro essay allowing single molecule tracking, we have discovered a previously unknown role of the regulation of microtubule dynamics within the spindle midzone of C. elegans by the chromokinesin KLP-19, and its relevance for proper spindle function. Using Fluorescence recovery after photobleaching and a combination of second harmonic generation and two-photon fluorescence microscopy, we found that the length of the antiparallel microtubule overlap zone in the spindle midzone is constant throughout anaphase, and independent of cortical pulling forces as well as the presence of the microtubule bundling protein SPD-1. Further investigations of SPD-1 and KLP-19 in C. elegans, the homologs of PRC1 and KIF4a, suggest that KLP-19 regulates the overlap length and functions independently of SPD-1. Our data shows that KLP-19 plays an active role in regulating the length of microtubules within the midzone as well as the size of the antiparallel overlap region throughout mitosis. Depletion of KLP-19 in mitosis leads to an increase in microtubule length and thus microtubule-based interactions in the spindle midzone, which affects spindle dynamics and force transmission. Our data shows that by localizing KLP-19 to the spindle midzone in anaphase microtubule dynamics can be locally controlled allowing the formation of a functional midzone.
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Affiliation(s)
- Vitaly Zimyanin
- Department of Molecular Physiology and Biological Physics, University of Virginia, School of Medicine, Charlottesville, VA, USA
- Center for Membrane and Cell Physiology, University of Virginia School of Medicine, Charlottesville, VA, USA
| | - Magdalena Magaj
- Department of Molecular Physiology and Biological Physics, University of Virginia, School of Medicine, Charlottesville, VA, USA
- Department of Cell Biology, University of Virginia School of Medicine, Charlottesville, VA, USA
| | | | - Che-Hang Yu
- Department of Electrical and Computer Engineering, University of California, Santa Barbara, CA, USA
| | - Theresa Gibney
- Department of Biology, University of Virginia, Charlottesville, VA, USA
| | - Yu-Zen Chen
- Department of Molecular Physiology and Biological Physics, University of Virginia, School of Medicine, Charlottesville, VA, USA
- Center for Membrane and Cell Physiology, University of Virginia School of Medicine, Charlottesville, VA, USA
| | - Mustafa Basaran
- Molecular and Cellular Biology and School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
| | - Xavier Horton
- Department of Molecular Physiology and Biological Physics, University of Virginia, School of Medicine, Charlottesville, VA, USA
- Department of Cell Biology, University of Virginia School of Medicine, Charlottesville, VA, USA
| | - Karsten Siller
- IT-Research Computing, University of Virginia, Charlottesville, VA, USA
| | - Ariel Pani
- Department of Biology, University of Virginia, Charlottesville, VA, USA
| | - Daniel Needleman
- Molecular and Cellular Biology and School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
- Center for Computational Biology, Flatiron Institute, New York, NY, USA
| | - Daniel J Dickinson
- Department of Molecular Bioscience, University of Texas at Austin, TX, USA
| | - Stefanie Redemann
- Department of Molecular Physiology and Biological Physics, University of Virginia, School of Medicine, Charlottesville, VA, USA
- Center for Membrane and Cell Physiology, University of Virginia School of Medicine, Charlottesville, VA, USA
- Department of Cell Biology, University of Virginia School of Medicine, Charlottesville, VA, USA
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5
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Goda M, Shribak M, Ikeda Z, Okada N, Tani T, Goshima G, Oldenbourg R, Kimura A. Live-cell imaging under centrifugation characterized the cellular force for nuclear centration in the Caenorhabditis elegans embryo. Proc Natl Acad Sci U S A 2024; 121:e2402759121. [PMID: 39413133 PMCID: PMC11513977 DOI: 10.1073/pnas.2402759121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2024] [Accepted: 08/21/2024] [Indexed: 10/18/2024] Open
Abstract
Organelles in cells are appropriately positioned, despite crowding in the cytoplasm. However, our understanding of the force required to move large organelles, such as the nucleus, inside the cytoplasm is limited, in part owing to a lack of accurate methods for measurement. We devised a method to apply forces to the nucleus of living Caenorhabditis elegans embryos to measure the force generated inside the cell. We used a centrifuge polarizing microscope to apply centrifugal force and orientation-independent differential interference contrast microscopy to characterize the mass density of the nucleus and cytoplasm. The cellular forces moving the nucleus toward the cell center increased linearly at ~12 pN/μm depending on the distance from the center. The frictional coefficient was ~980 pN s/μm. The measured values were smaller than the previously reported estimates for sea urchin embryos. The forces were consistent with the centrosome-organelle mutual pulling model for nuclear centration. The frictional coefficient was reduced when microtubules were shorter or detached from nuclei in mutant embryos, demonstrating the contribution of astral microtubules. Finally, the frictional coefficient was higher than a theoretical estimate, indicating the contribution of uncharacterized properties of the cytoplasm.
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Affiliation(s)
- Makoto Goda
- Marine Biological Laboratory, Woods Hole, MA02543
- Institute of Photonics Medicine, Hamamatsu University School of Medicine, Hamamatsu431-3192, Japan
- Nagoya University, Nagoya464-8602, Japan
| | | | - Zenki Ikeda
- National Institute of Genetics, Mishima411-8540, Japan
- Genetics Program, Sokendai (Graduate University for Advanced Studies), Mishima411-8540, Japan
| | | | - Tomomi Tani
- Marine Biological Laboratory, Woods Hole, MA02543
- Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology, Ikeda563-8577, Japan
| | - Gohta Goshima
- Marine Biological Laboratory, Woods Hole, MA02543
- Nagoya University, Nagoya464-8602, Japan
| | | | - Akatsuki Kimura
- Marine Biological Laboratory, Woods Hole, MA02543
- National Institute of Genetics, Mishima411-8540, Japan
- Genetics Program, Sokendai (Graduate University for Advanced Studies), Mishima411-8540, Japan
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6
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Dey S, Kumar N, Balakrishnan S, Koushika SP, Ghosh-Roy A. KLP-7/Kinesin-13 orchestrates axon-dendrite checkpoints for polarized trafficking in neurons. Mol Biol Cell 2024; 35:ar115. [PMID: 38985513 PMCID: PMC7616348 DOI: 10.1091/mbc.e23-08-0335] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2023] [Revised: 06/27/2024] [Accepted: 07/03/2024] [Indexed: 07/12/2024] Open
Abstract
The polarized nature of neurons depends on their microtubule dynamics and orientation determined by both microtubule-stabilizing and destabilizing factors. The role of destabilizing factors in developing and maintaining neuronal polarity is unclear. We investigated the function of KLP-7, a microtubule depolymerizing motor of the Kinesin-13 family, in axon-dendrite compartmentalization using PVD neurons in Caenorhabditis elegans. Loss of KLP-7 caused a mislocalization of axonal proteins, including RAB-3, SAD-1, and their motor UNC-104, to dendrites. This is rescued by cell-autonomous expression of the KLP-7 or colchicine treatment, indicating the involvement of KLP-7-dependent microtubule depolymerization. The high mobility of KLP-7 is correlated to increased microtubule dynamics in the dendrites, which restricts the enrichment of UNC-44, an integral component of Axon Initial Segment (AIS) in these processes. Due to the loss of KLP-7, ectopic enrichment of UNC-44 in the dendrite potentially redirects axonal traffic into dendrites that include plus-end out microtubules, axonal motors, and cargoes. These observations indicate that KLP-7-mediated depolymerization defines the microtubule dynamics conducive to the specific enrichment of AIS components in dendrites. This further compartmentalizes dendritic and axonal microtubules, motors, and cargoes, thereby influencing neuronal polarity.
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Affiliation(s)
- Swagata Dey
- Cellular and Molecular Neuroscience, National Brain Research Centre, Manesar, Gurugram, Haryana 122052, India
| | - Nitish Kumar
- Cellular and Molecular Neuroscience, National Brain Research Centre, Manesar, Gurugram, Haryana 122052, India
| | - Supraja Balakrishnan
- Cellular and Molecular Neuroscience, National Brain Research Centre, Manesar, Gurugram, Haryana 122052, India
| | - Sandhya P. Koushika
- Department of Biological Sciences, Tata Institute of Fundamental Research, Mumbai, Maharashtra 400005, India
| | - Anindya Ghosh-Roy
- Cellular and Molecular Neuroscience, National Brain Research Centre, Manesar, Gurugram, Haryana 122052, India
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7
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Le Cunff Y, Chesneau L, Pastezeur S, Pinson X, Soler N, Fairbrass D, Mercat B, Rodriguez-Garcia R, Alayan Z, Abdouni A, de Neidhardt G, Costes V, Anjubault M, Bouvrais H, Héligon C, Pécréaux J. Unveiling inter-embryo variability in spindle length over time: Towards quantitative phenotype analysis. PLoS Comput Biol 2024; 20:e1012330. [PMID: 39236069 PMCID: PMC11376571 DOI: 10.1371/journal.pcbi.1012330] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2024] [Accepted: 07/15/2024] [Indexed: 09/07/2024] Open
Abstract
How can inter-individual variability be quantified? Measuring many features per experiment raises the question of choosing them to recapitulate high-dimensional data. Tackling this challenge on spindle elongation phenotypes, we showed that only three typical elongation patterns describe spindle elongation in C. elegans one-cell embryo. These archetypes, automatically extracted from the experimental data using principal component analysis (PCA), accounted for more than 95% of inter-individual variability of more than 1600 experiments across more than 100 different conditions. The two first archetypes were related to spindle average length and anaphasic elongation rate. The third archetype, accounting for 6% of the variability, was novel and corresponded to a transient spindle shortening in late metaphase, reminiscent of kinetochore function-defect phenotypes. Importantly, these three archetypes were robust to the choice of the dataset and were found even considering only non-treated conditions. Thus, the inter-individual differences between genetically perturbed embryos have the same underlying nature as natural inter-individual differences between wild-type embryos, independently of the temperatures. We thus propose that beyond the apparent complexity of the spindle, only three independent mechanisms account for spindle elongation, weighted differently in the various conditions. Interestingly, the spindle-length archetypes covered both metaphase and anaphase, suggesting that spindle elongation in late metaphase is sufficient to predict the late anaphase length. We validated this idea using a machine-learning approach. Finally, given amounts of these three archetypes could represent a quantitative phenotype. To take advantage of this, we set out to predict interacting genes from a seed based on the PCA coefficients. We exemplified this firstly on the role of tpxl-1 whose homolog tpx2 is involved in spindle microtubule branching, secondly the mechanism regulating metaphase length, and thirdly the central spindle players which set the length at anaphase. We found novel interactors not in public databases but supported by recent experimental publications.
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Affiliation(s)
- Yann Le Cunff
- CNRS, Univ Rennes, IGDR (Institut Genetics and Development of Rennes) - UMR 6290, Rennes, France
| | - Laurent Chesneau
- CNRS, Univ Rennes, IGDR (Institut Genetics and Development of Rennes) - UMR 6290, Rennes, France
| | - Sylvain Pastezeur
- CNRS, Univ Rennes, IGDR (Institut Genetics and Development of Rennes) - UMR 6290, Rennes, France
| | - Xavier Pinson
- CNRS, Univ Rennes, IGDR (Institut Genetics and Development of Rennes) - UMR 6290, Rennes, France
| | - Nina Soler
- CNRS, Univ Rennes, IGDR (Institut Genetics and Development of Rennes) - UMR 6290, Rennes, France
| | - Danielle Fairbrass
- CNRS, Univ Rennes, IGDR (Institut Genetics and Development of Rennes) - UMR 6290, Rennes, France
| | - Benjamin Mercat
- CNRS, Univ Rennes, IGDR (Institut Genetics and Development of Rennes) - UMR 6290, Rennes, France
| | - Ruddi Rodriguez-Garcia
- CNRS, Univ Rennes, IGDR (Institut Genetics and Development of Rennes) - UMR 6290, Rennes, France
| | - Zahraa Alayan
- CNRS, Univ Rennes, IGDR (Institut Genetics and Development of Rennes) - UMR 6290, Rennes, France
| | - Ahmed Abdouni
- CNRS, Univ Rennes, IGDR (Institut Genetics and Development of Rennes) - UMR 6290, Rennes, France
| | - Gary de Neidhardt
- CNRS, Univ Rennes, IGDR (Institut Genetics and Development of Rennes) - UMR 6290, Rennes, France
| | - Valentin Costes
- CNRS, Univ Rennes, IGDR (Institut Genetics and Development of Rennes) - UMR 6290, Rennes, France
| | - Mélodie Anjubault
- CNRS, Univ Rennes, IGDR (Institut Genetics and Development of Rennes) - UMR 6290, Rennes, France
| | - Hélène Bouvrais
- CNRS, Univ Rennes, IGDR (Institut Genetics and Development of Rennes) - UMR 6290, Rennes, France
| | - Christophe Héligon
- CNRS, Univ Rennes, IGDR (Institut Genetics and Development of Rennes) - UMR 6290, Rennes, France
| | - Jacques Pécréaux
- CNRS, Univ Rennes, IGDR (Institut Genetics and Development of Rennes) - UMR 6290, Rennes, France
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8
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Czajkowski ER, Zou Y, Divekar NS, Wignall SM. The doublecortin-family kinase ZYG-8DCLK1 regulates microtubule dynamics and motor-driven forces to promote the stability of C. elegans acentrosomal spindles. PLoS Genet 2024; 20:e1011373. [PMID: 39226307 PMCID: PMC11398696 DOI: 10.1371/journal.pgen.1011373] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2024] [Revised: 09/13/2024] [Accepted: 07/23/2024] [Indexed: 09/05/2024] Open
Abstract
Although centrosomes help organize spindles in most cell types, oocytes of most species lack these structures. During acentrosomal spindle assembly in C. elegans oocytes, microtubule minus ends are sorted outwards away from the chromosomes where they form poles, but then these outward forces must be balanced to form a stable bipolar structure. Simultaneously, microtubule dynamics must be precisely controlled to maintain spindle length and organization. How forces and dynamics are tuned to create a stable bipolar structure is poorly understood. Here, we have gained insight into this question through studies of ZYG-8, a conserved doublecortin-family kinase; the mammalian homolog of this microtubule-associated protein is upregulated in many cancers and has been implicated in cell division, but the mechanisms by which it functions are poorly understood. We found that ZYG-8 depletion from oocytes resulted in overelongated spindles with pole and midspindle defects. Importantly, experiments with monopolar spindles revealed that ZYG-8 depletion led to excess outward forces within the spindle and suggested a potential role for this protein in regulating the force-generating motor BMK-1/kinesin-5. Further, we found that ZYG-8 is also required for proper microtubule dynamics within the oocyte spindle and that kinase activity is required for its function during both meiosis and mitosis. Altogether, our findings reveal new roles for ZYG-8 in oocytes and provide insights into how acentrosomal spindles are stabilized to promote faithful meiosis.
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Affiliation(s)
- Emily R. Czajkowski
- Department of Molecular Biosciences, Northwestern University, Evanston, Illinois, United States of America
| | - Yuntong Zou
- Department of Molecular Biosciences, Northwestern University, Evanston, Illinois, United States of America
| | - Nikita S. Divekar
- Department of Molecular Biosciences, Northwestern University, Evanston, Illinois, United States of America
| | - Sarah M. Wignall
- Department of Molecular Biosciences, Northwestern University, Evanston, Illinois, United States of America
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9
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Narula JG, Wignall SM. Polo-like kinase 1 prevents excess microtubule polymerization in C. elegans oocytes to ensure faithful meiosis. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.08.03.606476. [PMID: 39131294 PMCID: PMC11312516 DOI: 10.1101/2024.08.03.606476] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/13/2024]
Abstract
Sexual reproduction relies on meiosis, a specialized cell division program that produces haploid gametes. Oocytes of most organisms lack centrosomes, and therefore chromosome segregation is mediated by acentrosomal spindles. Here, we explore the role of Polo-like kinase 1 (PLK-1) in C. elegans oocytes, revealing mechanisms that ensure the fidelity of this unique form of cell division. Previously, PLK-1 was shown to be required for nuclear envelope breakdown and chromosome segregation in oocytes. We now find that PLK-1 is also required for establishing and maintaining acentrosomal spindle organization and for preventing excess microtubule polymerization in these cells. Additionally, our studies revealed an unexpected new role for this essential kinase. While PLK-1 is known to be required for centrosome maturation during mitosis, we found that removal of this kinase from oocytes caused premature recruitment of pericentriolar material to the sperm-provided centrioles following fertilization. Thus, PLK-1 suppresses centrosome maturation during oocyte meiosis, which is opposite to its role in mitosis. Taken together, our work reveals multiple new roles for PLK-1 in oocytes, identifying PLK-1 as a key player that promotes faithful acentrosomal meiosis.
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Affiliation(s)
- Juhi G Narula
- Department of Molecular Biosciences, Northwestern University, Evanston, IL 60208
| | - Sarah M Wignall
- Department of Molecular Biosciences, Northwestern University, Evanston, IL 60208
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10
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Xu K, Li Z, Mao L, Guo Z, Chen Z, Chai Y, Xie C, Yang X, Na J, Li W, Ou G. AlphaFold2-guided engineering of split-GFP technology enables labeling of endogenous tubulins across species while preserving function. PLoS Biol 2024; 22:e3002615. [PMID: 39159282 PMCID: PMC11361732 DOI: 10.1371/journal.pbio.3002615] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2024] [Revised: 08/29/2024] [Accepted: 07/29/2024] [Indexed: 08/21/2024] Open
Abstract
Dynamic properties are essential for microtubule (MT) physiology. Current techniques for in vivo imaging of MTs present intrinsic limitations in elucidating the isotype-specific nuances of tubulins, which contribute to their versatile functions. Harnessing the power of the AlphaFold2 pipeline, we engineered a strategy for the minimally invasive fluorescence labeling of endogenous tubulin isotypes or those harboring missense mutations. We demonstrated that a specifically designed 16-amino acid linker, coupled with sfGFP11 from the split-sfGFP system and integration into the H1-S2 loop of tubulin, facilitated tubulin labeling without compromising MT dynamics, embryonic development, or ciliogenesis in Caenorhabditis elegans. Extending this technique to human cells and murine oocytes, we visualized MTs with the minimal background fluorescence and a pathogenic tubulin isoform with fidelity. The utility of our approach across biological contexts and species set an additional paradigm for studying tubulin dynamics and functional specificity, with implications for understanding tubulin-related diseases known as tubulinopathies.
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Affiliation(s)
- Kaiming Xu
- Tsinghua-Peking Center for Life Sciences, Beijing Frontier Research Center for Biological Structure, McGovern Institute for Brain Research, State Key Laboratory of Membrane Biology, School of Life Sciences and MOE Key Laboratory for Protein Science, Tsinghua University, Beijing, China
| | - Zhiyuan Li
- School of Life Sciences, MOE Key Laboratory of Bioinformatics, Center for Synthetic & Systems Biology, Tsinghua University, Beijing, China
| | - Linfan Mao
- School of Medicine, Tsinghua University, Beijing, China
| | - Zhengyang Guo
- Tsinghua-Peking Center for Life Sciences, Beijing Frontier Research Center for Biological Structure, McGovern Institute for Brain Research, State Key Laboratory of Membrane Biology, School of Life Sciences and MOE Key Laboratory for Protein Science, Tsinghua University, Beijing, China
| | - Zhe Chen
- Tsinghua-Peking Center for Life Sciences, Beijing Frontier Research Center for Biological Structure, McGovern Institute for Brain Research, State Key Laboratory of Membrane Biology, School of Life Sciences and MOE Key Laboratory for Protein Science, Tsinghua University, Beijing, China
| | - Yongping Chai
- Tsinghua-Peking Center for Life Sciences, Beijing Frontier Research Center for Biological Structure, McGovern Institute for Brain Research, State Key Laboratory of Membrane Biology, School of Life Sciences and MOE Key Laboratory for Protein Science, Tsinghua University, Beijing, China
| | - Chao Xie
- Tsinghua-Peking Center for Life Sciences, Beijing Frontier Research Center for Biological Structure, McGovern Institute for Brain Research, State Key Laboratory of Membrane Biology, School of Life Sciences and MOE Key Laboratory for Protein Science, Tsinghua University, Beijing, China
| | - Xuerui Yang
- School of Life Sciences, MOE Key Laboratory of Bioinformatics, Center for Synthetic & Systems Biology, Tsinghua University, Beijing, China
| | - Jie Na
- School of Medicine, Tsinghua University, Beijing, China
| | - Wei Li
- School of Medicine, Tsinghua University, Beijing, China
| | - Guangshuo Ou
- Tsinghua-Peking Center for Life Sciences, Beijing Frontier Research Center for Biological Structure, McGovern Institute for Brain Research, State Key Laboratory of Membrane Biology, School of Life Sciences and MOE Key Laboratory for Protein Science, Tsinghua University, Beijing, China
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11
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Agarwal P, Berger S, Shemesh T, Zaidel-Bar R. Active nuclear positioning and actomyosin contractility maintain leader cell integrity during gonadogenesis. Curr Biol 2024; 34:2373-2386.e5. [PMID: 38776903 DOI: 10.1016/j.cub.2024.03.049] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2023] [Revised: 02/01/2024] [Accepted: 03/25/2024] [Indexed: 05/25/2024]
Abstract
Proper distribution of organelles can play an important role in a moving cell's performance. During C. elegans gonad morphogenesis, the nucleus of the leading distal tip cell (DTC) is always found at the front, yet the significance of this localization is unknown. Here, we identified the molecular mechanism that keeps the nucleus at the front, despite a frictional force that pushes it backward. The Klarsicht/ANC-1/Syne homology (KASH) domain protein UNC-83 links the nucleus to the motor protein kinesin-1 that moves along a polarized acentrosomal microtubule network. Interestingly, disrupting nuclear positioning on its own did not affect gonad morphogenesis. However, reducing actomyosin contractility on top of nuclear mispositioning led to a dramatic phenotype: DTC splitting and gonad bifurcation. Long-term live imaging of the double knockdown revealed that, while the gonad attempted to perform a planned U-turn, the DTC was stretched due to the lagging nucleus until it fragmented into a nucleated cell and an enucleated cytoplast, each leading an independent gonadal arm. Remarkably, the enucleated cytoplast had polarity and invaded, but it could only temporarily support germ cell proliferation. Based on a qualitative biophysical model, we conclude that the leader cell employs two complementary mechanical approaches to preserve its integrity and ensure proper organ morphogenesis while navigating through a complex 3D environment: active nuclear positioning by microtubule motors and actomyosin-driven cortical contractility.
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Affiliation(s)
- Priti Agarwal
- Department of Cell and Developmental Biology, Faculty of Medical & Health Sciences, Tel Aviv University, Tel Aviv 6997801, Israel.
| | - Simon Berger
- Department of Molecular Life Sciences, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland
| | - Tom Shemesh
- Faculty of Biology, Technion - Israel Institute of Technology, Haifa 3200003, Israel
| | - Ronen Zaidel-Bar
- Department of Cell and Developmental Biology, Faculty of Medical & Health Sciences, Tel Aviv University, Tel Aviv 6997801, Israel.
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12
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Meier SM, Steinmetz MO, Barral Y. Microtubule specialization by +TIP networks: from mechanisms to functional implications. Trends Biochem Sci 2024; 49:318-332. [PMID: 38350804 DOI: 10.1016/j.tibs.2024.01.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2023] [Revised: 12/23/2023] [Accepted: 01/12/2024] [Indexed: 02/15/2024]
Abstract
To fulfill their actual cellular role, individual microtubules become functionally specialized through a broad range of mechanisms. The 'search and capture' model posits that microtubule dynamics and functions are specified by cellular targets that they capture (i.e., a posteriori), independently of the microtubule-organizing center (MTOC) they emerge from. However, work in budding yeast indicates that MTOCs may impart a functional identity to the microtubules they nucleate, a priori. Key effectors in this process are microtubule plus-end tracking proteins (+TIPs), which track microtubule tips to regulate their dynamics and facilitate their targeted interactions. In this review, we discuss potential mechanisms of a priori microtubule specialization, focusing on recent findings indicating that +TIP networks may undergo liquid biomolecular condensation in different cell types.
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Affiliation(s)
- Sandro M Meier
- Institute of Biochemistry, Department of Biology, and Bringing Materials to Life Initiative, ETH Zürich, Switzerland; Laboratory of Biomolecular Research, Division of Biology and Chemistry, Paul Scherrer Institut, Villigen, Switzerland; Bringing Materials to Life Initiative, ETH Zürich, Switzerland
| | - Michel O Steinmetz
- Laboratory of Biomolecular Research, Division of Biology and Chemistry, Paul Scherrer Institut, Villigen, Switzerland; University of Basel, Biozentrum, CH-4056 Basel, Switzerland.
| | - Yves Barral
- Institute of Biochemistry, Department of Biology, and Bringing Materials to Life Initiative, ETH Zürich, Switzerland; Bringing Materials to Life Initiative, ETH Zürich, Switzerland.
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13
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Chenevert J, Robert MLV, Sallé J, Cacchia S, Lorca T, Castro A, McDougall A, Minc N, Castagnetti S, Dumont J, Lacroix B. Measuring Mitotic Spindle and Microtubule Dynamics in Marine Embryos and Non-model Organisms. Methods Mol Biol 2024; 2740:187-210. [PMID: 38393477 DOI: 10.1007/978-1-0716-3557-5_12] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/25/2024]
Abstract
During eukaryotic cell division a microtubule-based structure, the mitotic spindle, aligns and segregates chromosomes between daughter cells. Understanding how this cellular structure is assembled and coordinated in space and in time requires measuring microtubule dynamics and visualizing spindle assembly with high temporal and spatial resolution. Visualization is often achieved by the introduction and the detection of molecular probes and fluorescence microscopy. Microtubules and mitotic spindles are highly conserved across eukaryotes; however, several technical limitations have restricted these investigations to only a few species. The ability to monitor microtubule and chromosome choreography in a wide range of species is fundamental to reveal conserved mechanisms or unravel unconventional strategies that certain forms of life have developed to ensure faithful partitioning of chromosomes during cell division. Here, we describe a technique based on injection of purified proteins that enables the visualization of microtubules and chromosomes with a high contrast in several divergent marine embryos. We also provide analysis methods and tools to extract microtubule dynamics and monitor spindle assembly. These techniques can be adapted to a wide variety of species in order to measure microtubule dynamics and spindle assembly kinetics when genetic tools are not available or in parallel to the development of such techniques in non-model organisms.
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Affiliation(s)
- Janet Chenevert
- Sorbonne Universités, CNRS, Laboratoire de Biologie du Développement de Villefranche-sur-mer (LBDV), Villefranche-sur-mer, France
| | - Morgane L V Robert
- Université de Montpellier, Centre de Recherche en Biologie cellulaire de Montpellier (CRBM), CNRS UMR 5237, Montpellier Cedex 5, France
| | - Jérémy Sallé
- CNRS, Institut Jacques Monod, Université Paris Cité, Paris, France
- Equipe Labellisée Ligue Contre le Cancer, Paris, France
| | - Sébastien Cacchia
- Université de Montpellier, Centre de Recherche en Biologie cellulaire de Montpellier (CRBM), CNRS UMR 5237, Montpellier Cedex 5, France
| | - Thierry Lorca
- Université de Montpellier, Centre de Recherche en Biologie cellulaire de Montpellier (CRBM), CNRS UMR 5237, Montpellier Cedex 5, France
| | - Anna Castro
- Université de Montpellier, Centre de Recherche en Biologie cellulaire de Montpellier (CRBM), CNRS UMR 5237, Montpellier Cedex 5, France
- Programme équipes Labellisées Ligue Contre le Cancer, Paris, France
| | - Alex McDougall
- Sorbonne Universités, CNRS, Laboratoire de Biologie du Développement de Villefranche-sur-mer (LBDV), Villefranche-sur-mer, France
| | - Nicolas Minc
- CNRS, Institut Jacques Monod, Université Paris Cité, Paris, France
- Equipe Labellisée Ligue Contre le Cancer, Paris, France
| | - Stefania Castagnetti
- Sorbonne Universités, CNRS, Laboratoire de Biologie du Développement de Villefranche-sur-mer (LBDV), Villefranche-sur-mer, France
| | - Julien Dumont
- CNRS, Institut Jacques Monod, Université Paris Cité, Paris, France
| | - Benjamin Lacroix
- Université de Montpellier, Centre de Recherche en Biologie cellulaire de Montpellier (CRBM), CNRS UMR 5237, Montpellier Cedex 5, France.
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14
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Li W, Crellin HA, Cheerambathur D, McNally FJ. Redundant microtubule crosslinkers prevent meiotic spindle bending to ensure diploid offspring in C. elegans. PLoS Genet 2023; 19:e1011090. [PMID: 38150489 PMCID: PMC10775986 DOI: 10.1371/journal.pgen.1011090] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Revised: 01/09/2024] [Accepted: 12/05/2023] [Indexed: 12/29/2023] Open
Abstract
Oocyte meiotic spindles mediate the expulsion of ¾ of the genome into polar bodies to generate diploid zygotes in nearly all animal species. Failures in this process result in aneuploid or polyploid offspring that are typically inviable. Accurate meiotic chromosome segregation and polar body extrusion require the spindle to elongate while maintaining its structural integrity. Previous studies have implicated three hypothetical activities during this process, including microtubule crosslinking, microtubule sliding and microtubule polymerization. However, how these activities regulate spindle rigidity and elongation as well as the exact proteins involved in the activities remain unclear. We discovered that C. elegans meiotic anaphase spindle integrity is maintained through redundant microtubule crosslinking activities of the Kinesin-5 family motor BMK-1, the microtubule bundling protein SPD-1/PRC1, and the Kinesin-4 family motor, KLP-19. Using time-lapse imaging, we found that single depletion of KLP-19KIF4A, SPD-1PRC1 or BMK-1Eg5 had minimal effects on anaphase B spindle elongation velocity. In contrast, double depletion of SPD-1PRC1 and BMK-1Eg5 or double depletion of KLP-19KIF4A and BMK-1Eg5 resulted in spindles that elongated faster, bent in a myosin-dependent manner, and had a high rate of polar body extrusion errors. Bending spindles frequently extruded both sets of segregating chromosomes into two separate polar bodies. Normal anaphase B velocity was observed after double depletion of KLP-19KIF4A and SPD-1PRC1. These results suggest that KLP-19KIF4A and SPD-1PRC1 act in different pathways, each redundant with a separate BMK-1Eg5 pathway in regulating meiotic spindle elongation. Depletion of ZYG-8, a doublecortin-related microtubule binding protein, led to slower anaphase B spindle elongation. We found that ZYG-8DCLK1 acts by excluding SPD-1PRC1 from the spindle. Thus, three mechanistically distinct microtubule regulation modules, two based on crosslinking, and one based on exclusion of crosslinkers, power the mechanism that drives spindle elongation and structural integrity during anaphase B of C.elegans female meiosis.
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Affiliation(s)
- Wenzhe Li
- Department of Molecular and Cellular Biology, University of California, Davis, California, United States of America
| | - Helena A. Crellin
- Wellcome Centre for Cell Biology & Institute of Cell Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Dhanya Cheerambathur
- Wellcome Centre for Cell Biology & Institute of Cell Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Francis J. McNally
- Department of Molecular and Cellular Biology, University of California, Davis, California, United States of America
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15
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Chen YZ, Zimyanin V, Redemann S. Loss of the mitochondrial protein SPD-3 elevates PLK-1 levels and dysregulates mitotic events. Life Sci Alliance 2023; 6:e202302011. [PMID: 37684042 PMCID: PMC10488725 DOI: 10.26508/lsa.202302011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2023] [Revised: 08/28/2023] [Accepted: 08/29/2023] [Indexed: 09/10/2023] Open
Abstract
In metazoans, Polo-like kinase (PLK1) controls several mitotic events including nuclear envelope breakdown, centrosome maturation, spindle assembly and progression through mitosis. Here we show that a mutation in the mitochondria-localized protein SPD-3 affects mitotic events by inducing elevated levels of PLK-1 in early Caenorhabditis elegans embryos. SPD-3 mutant embryos contain abnormally positioned mitotic chromosomes, show a delay in anaphase onset and asymmetrically disassemble the nuclear lamina. We found that more PLK-1 accumulated on centrosomes, nuclear envelope, nucleoplasm, and chromatin before NEBD, suggesting that PLK-1 overexpression is responsible for some of the observed mitotic phenotypes. In agreement with this, the chromosome positioning defects of the spd-3(oj35) mutant could be rescued by reducing PLK-1 levels. Our data suggests that the mitochondrial SPD-3 protein affects chromosome positioning and nuclear envelope integrity by up-regulating the endogenous levels of PLK-1 during early embryogenesis in C. elegans This finding suggests a novel link between mitochondria and nuclear envelope dynamics and chromosome positioning by increasing the amount of a key mitotic regulator, PLK-1, providing a novel link between mitochondria and mitosis.
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Affiliation(s)
- Yu-Zen Chen
- Center for Membrane and Cell Physiology, School of Medicine, University of Virginia, Charlottesville, VA, USA
- Department of Molecular Physiology and Biological Physics, School of Medicine, University of Virginia, Charlottesville, VA, USA
| | - Vitaly Zimyanin
- Center for Membrane and Cell Physiology, School of Medicine, University of Virginia, Charlottesville, VA, USA
- Department of Molecular Physiology and Biological Physics, School of Medicine, University of Virginia, Charlottesville, VA, USA
| | - Stefanie Redemann
- Center for Membrane and Cell Physiology, School of Medicine, University of Virginia, Charlottesville, VA, USA
- Department of Molecular Physiology and Biological Physics, School of Medicine, University of Virginia, Charlottesville, VA, USA
- Department of Cell Biology, School of Medicine, University of Virginia, Charlottesville, VA, USA
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16
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Mahadik SS, Lundquist EA. A short isoform of the UNC-6/Netrin receptor UNC-5 is required for growth cone polarity and robust growth cone protrusion in Caenorhabditis elegans. Front Cell Dev Biol 2023; 11:1240994. [PMID: 37649551 PMCID: PMC10464613 DOI: 10.3389/fcell.2023.1240994] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2023] [Accepted: 08/01/2023] [Indexed: 09/01/2023] Open
Abstract
Introduction: UNC-6/Netrin is a conserved bi-functional guidance cue which regulates dorsal-ventral axon guidance in C. elegans. In the Polarity/Protrusion model of UNC-6/Netrin mediated dorsal growth away from UNC-6/Netrin, The UNC-5 receptor first polarizes the VD growth cone such that filopodial protrusions are biased dorsally. Based on this polarity, the UNC-40/DCC receptor stimulates growth cone lamellipodial and filopodial protrusion dorsally. The UNC-5 receptor maintains dorsal polarity of protrusion, and inhibits growth cone protrusion ventrally, resulting in net dorsal growth cone advance. Methods: Growth cone imaging in mutants, combined with Cas9 genome editing and genetic analysis, were used to analyze the role of a novel short isoform on unc-5 in growth cone polarity and protrusion. Results: Work presented here demonstrates a novel role of a previously undescribed, conserved short isoform of UNC-5 (UNC-5B). UNC-5B lacks the cytoplasmic domains of UNC-5 long, including the DEATH domain, the UPA/DB domain, and most of the ZU5 domain. Mutations that specifically affect only the unc-5 long isoforms were hypomorphic, suggesting a role of unc-5B short. A mutation specifically affecting unc-5B caused loss of dorsal polarity of protrusion and reduced growth cone filopodial protrusion, the opposite of unc-5 long mutations. Transgenic expression of unc-5B partially rescued unc-5 axon guidance defects, and resulted in large growth cones. Tyrosine 482 (Y482) in the cytoplasmic juxtamembrane region has been shown to be important for UNC-5 function, and is present in both UNC-5 long and UNC-5B short. Results reported here show that Y482 is required for the function of UNC-5 long and for some functions of UNC-5B short. Finally, genetic interactions with unc-40 and unc-6 suggest that UNC-5B short acts in parallel to UNC-6/Netrin to ensure robust growth cone lamellipodial protrusion. Discussion: These results demonstrate a previously-undescribed role for the UNC-5B short isoform, which is required for dorsal polarity of growth cone filopodial protrusion and to stimulate growth cone protrusion, in contrast to the previously-described role of UNC-5 long in inhibiting growth cone protrusion.
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Affiliation(s)
| | - Erik A. Lundquist
- Program in Molecular, Cellular, and Developmental Biology, Department of Molecular Biosciences, The University of Kansas, Lawrence, KS, United States
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17
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Mahadik SS, Lundquist EA. A short isoform of the UNC-6/Netrin receptor UNC-5 is required for growth cone polarity and robust growth cone protrusion in Caenorhabditis elegans. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.02.539117. [PMID: 37205526 PMCID: PMC10187218 DOI: 10.1101/2023.05.02.539117] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
UNC-6/Netrin is a conserved bi-functional guidance cue which regulates dorsal-ventral axon guidance in C. elegans . In the Polarity/Protrusion model of UNC-6/Netrin mediated dorsal growth away from UNC-6/Netrin, The UNC-5 receptor first polarizes the VD growth cone such that filopodial protrusions are biased dorsally. Based on this polarity, the UNC-40/DCC receptor stimulates growth cone lamellipodial and filopodial protrusion dorsally. The UNC-5 receptor maintains dorsal polarity of protrusion, and inhibits growth cone protrusion ventrally, resulting in net dorsal growth cone advance. Work presented here demonstrates a novel role of a previously undescribed, conserved short isoform of UNC-5 (UNC-5B). UNC-5B lacks the cytoplasmic domains of UNC-5 long, including the DEATH domain, the UPA/DB domain, and most of the ZU5 domain. Mutations that specifically affect only the unc-5 long isoforms were hypomorphic, suggesting a role of unc-5B short. A mutation specifically affecting unc-5B cause loss of dorsal polarity of protrusion and reduced growth cone filopodial protrusion, the opposite of unc-5 long mutations. Transgenic expression of unc-5B partially rescued unc-5 axon guidance defects, and resulted in large growth cones. Tyrosine 482 (Y482) in the cytoplasmic juxtamembrane region has been shown to be important for UNC-5 function, and is present in both UNC-5 long and UNC-5B short. Results reported here show that Y482 is required for the function of UNC-5 long and for some functions of UNC-5B short. Finally, genetic interactions with unc-40 and unc-6 suggest that UNC-5B short acts in parallel to UNC-6/Netrin to ensure robust growth cone lamellipodial protrusion. In sum, these results demonstrate a previously-undescribed role for the UNC-5B short isoform, which is required for dorsal polarity of growth cone filopodial protrusion and to stimulate growth cone protrusion, in contrast to the previously-described role of UNC-5 long in inhibiting growth cone protrusion.
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Affiliation(s)
- Snehal S. Mahadik
- Program in Molecular, Cellular, and Developmental Biology, Department of Molecular Biosciences, The University of Kansas, 1200 Sunnyside Avenue, 5049 Haworth Hall, Lawrence, KS 66045
| | - Erik A. Lundquist
- Program in Molecular, Cellular, and Developmental Biology, Department of Molecular Biosciences, The University of Kansas, 1200 Sunnyside Avenue, 5049 Haworth Hall, Lawrence, KS 66045
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18
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Prevo B, Cheerambathur DK, Earnshaw WC, Desai A. Kinetochore dynein is sufficient to biorient chromosomes and remodel the outer kinetochore. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.23.534015. [PMID: 36993239 PMCID: PMC10055418 DOI: 10.1101/2023.03.23.534015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
Multiple microtubule-directed activities concentrate on chromosomes during mitosis to ensure their accurate distribution to daughter cells. These activities include couplers and dynamics regulators localized at the kinetochore, the specialized microtubule interface built on centromeric chromatin, as well as motor proteins recruited to kinetochores and to mitotic chromatin. Here, we describe an in vivo reconstruction approach in which the effect of removing the major microtubule-directed activities on mitotic chromosomes is compared to the selective presence of individual activities. This approach revealed that the kinetochore dynein module, comprised of the minus end-directed motor cytoplasmic dynein and its kinetochore-specific adapters, is sufficient to biorient chromosomes and to remodel outer kinetochore composition following microtubule attachment; by contrast, the kinetochore dynein module is unable to support chromosome congression. The chromosome-autonomous action of kinetochore dynein, in the absence of the other major microtubule-directed factors on chromosomes, rotates and orients a substantial proportion of chromosomes such that their sister chromatids attach to opposite spindle poles. In tight coupling with orientation, the kinetochore dynein module drives removal of outermost kinetochore components, including the dynein motor itself and spindle checkpoint activators. The removal is independent of the other major microtubule-directed activities and kinetochore-localized protein phosphatase 1, suggesting that it is intrinsic to the kinetochore dynein module. These observations indicate that the kinetochore dynein module has the ability coordinate chromosome biorientation with attachment state-sensitive remodeling of the outer kinetochore that facilitates cell cycle progression.
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Affiliation(s)
- Bram Prevo
- Ludwig Institute for Cancer Research, La Jolla, California 92093, USA
- Wellcome Centre for Cell Biology, University of Edinburgh, Max Born Crescent, Edinburgh EH9 3BF, Scotland, UK
| | - Dhanya K Cheerambathur
- Wellcome Centre for Cell Biology, University of Edinburgh, Max Born Crescent, Edinburgh EH9 3BF, Scotland, UK
| | - William C Earnshaw
- Wellcome Centre for Cell Biology, University of Edinburgh, Max Born Crescent, Edinburgh EH9 3BF, Scotland, UK
| | - Arshad Desai
- Department of Cell and Developmental Biology, School of Biological Sciences, University of California, San Diego, La Jolla, CA 92093, USA
- Department of Cellular and Molecular Medicine, University of California San Diego, La Jolla, California 92093, USA
- Ludwig Institute for Cancer Research, La Jolla, California 92093, USA
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19
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Maheshwari R, Rahman MM, Drey S, Onyundo M, Fabig G, Martinez MAQ, Matus DQ, Müller-Reichert T, Cohen-Fix O. A membrane reticulum, the centriculum, affects centrosome size and function in Caenorhabditis elegans. Curr Biol 2023; 33:791-806.e7. [PMID: 36693370 PMCID: PMC10023444 DOI: 10.1016/j.cub.2022.12.059] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Revised: 11/21/2022] [Accepted: 12/21/2022] [Indexed: 01/24/2023]
Abstract
Centrosomes are cellular structures that nucleate microtubules. At their core is a pair of centrioles that recruit pericentriolar material (PCM). Although centrosomes are considered membraneless organelles, in many cell types, including human cells, centrosomes are surrounded by endoplasmic reticulum (ER)-derived membranes of unknown structure and function. Using volume electron microscopy (vEM), we show that centrosomes in the Caenorhabditis elegans (C. elegans) early embryo are surrounded by a three-dimensional (3D), ER-derived membrane reticulum that we call the centriculum, for centrosome-associated membrane reticulum. The centriculum is adjacent to the nuclear envelope in interphase and early mitosis and fuses with the fenestrated nuclear membrane at metaphase. Centriculum formation is dependent on the presence of an underlying centrosome and on microtubules. Conversely, increasing centriculum size by genetic means led to the expansion of the PCM, increased microtubule nucleation capacity, and altered spindle width. The effect of the centriculum on centrosome function suggests that in the C. elegans early embryo, the centrosome is not membraneless. Rather, it is encased in a membrane meshwork that affects its properties. We provide evidence that the centriculum serves as a microtubule "filter," preventing the elongation of a subset of microtubules past the centriculum. Finally, we propose that the fusion between the centriculum and the nuclear membrane contributes to nuclear envelope breakdown by coupling spindle elongation to nuclear membrane fenestration.
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Affiliation(s)
- Richa Maheshwari
- The Laboratory of Biochemistry and Genetics, National Institute of Diabetes and Digestive and Kidney Disease, National Institutes of Health, Bethesda, MD 20892, USA
| | - Mohammad M Rahman
- The Laboratory of Biochemistry and Genetics, National Institute of Diabetes and Digestive and Kidney Disease, National Institutes of Health, Bethesda, MD 20892, USA
| | - Seth Drey
- The Laboratory of Biochemistry and Genetics, National Institute of Diabetes and Digestive and Kidney Disease, National Institutes of Health, Bethesda, MD 20892, USA
| | - Megan Onyundo
- The Laboratory of Biochemistry and Genetics, National Institute of Diabetes and Digestive and Kidney Disease, National Institutes of Health, Bethesda, MD 20892, USA
| | - Gunar Fabig
- Experimental Center, Faculty of Medicine Carl Gustav Carus, Technische Universität Dresden, Fetscherstraße 74, 01307 Dresden, Germany
| | - Michael A Q Martinez
- Department of Biochemistry and Cell Biology, Stony Brook University, 450 Life Sciences Building, Stony Brook, NY 11794, USA
| | - David Q Matus
- Department of Biochemistry and Cell Biology, Stony Brook University, 450 Life Sciences Building, Stony Brook, NY 11794, USA
| | - Thomas Müller-Reichert
- Experimental Center, Faculty of Medicine Carl Gustav Carus, Technische Universität Dresden, Fetscherstraße 74, 01307 Dresden, Germany
| | - Orna Cohen-Fix
- The Laboratory of Biochemistry and Genetics, National Institute of Diabetes and Digestive and Kidney Disease, National Institutes of Health, Bethesda, MD 20892, USA.
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20
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Harvey AM, Chuang CH, Sumiyoshi E, Bowerman B. C. elegans XMAP215/ZYG-9 and TACC/TAC-1 act at multiple times during oocyte meiotic spindle assembly and promote both spindle pole coalescence and stability. PLoS Genet 2023; 19:e1010363. [PMID: 36608115 PMCID: PMC9851561 DOI: 10.1371/journal.pgen.1010363] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Revised: 01/19/2023] [Accepted: 12/13/2022] [Indexed: 01/09/2023] Open
Abstract
The conserved two-component XMAP215/TACC modulator of microtubule stability is required in multiple animal phyla for acentrosomal spindle assembly during oocyte meiotic cell division. In C. elegans, XMAP215/zyg-9 and TACC/tac-1 mutant oocytes exhibit multiple and indistinguishable oocyte spindle assembly defects beginning early in meiosis I. To determine if these defects represent one or more early requirements with additional later and indirect consequences, or multiple temporally distinct and more direct requirements, we have used live cell imaging and fast-acting temperature-sensitive zyg-9 and tac-1 alleles to dissect their requirements at high temporal resolution. Temperature upshift and downshift experiments indicate that the ZYG-9/TAC-1 complex has multiple temporally distinct and separable requirements throughout oocyte meiotic cell division. First, we show that during prometaphase ZYG-9 and TAC-1 promote the coalescence of early pole foci into a bipolar structure, stabilizing pole foci as they grow and limiting their growth rate, with these requirements being independent of an earlier defect in microtubule organization that occurs upon nuclear envelope breakdown. Second, during metaphase, ZYG-9 and TAC-1 maintain spindle bipolarity by suppressing ectopic pole formation. Third, we show that ZYG-9 and TAC-1 also are required for spindle assembly during meiosis II, independently of their meiosis I requirements. The metaphase pole stability requirement appears to be important for maintaining chromosome congression, and we discuss how negative regulation of microtubule stability by ZYG-9/TAC-1 during oocyte meiotic cell division might account for the observed defects in spindle pole coalescence and stability.
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Affiliation(s)
- Austin M. Harvey
- Institute of Molecular Biology, University of Oregon, Eugene, Oregon, United States of America
| | - Chien-Hui Chuang
- Institute of Molecular Biology, University of Oregon, Eugene, Oregon, United States of America
| | - Eisuke Sumiyoshi
- Institute of Molecular Biology, University of Oregon, Eugene, Oregon, United States of America
| | - Bruce Bowerman
- Institute of Molecular Biology, University of Oregon, Eugene, Oregon, United States of America
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21
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Abstract
The microtubule cytoskeleton is assembled from the α- and β-tubulin subunits of the canonical tubulin heterodimer, which polymerizes into microtubules, and a small number of other family members, such as γ-tubulin, with specialized functions. Overall, microtubule function involves the collective action of multiple α- and β-tubulin isotypes. However, despite 40 years of awareness that most eukaryotes harbor multiple tubulin isotypes, their role in the microtubule cytoskeleton has remained relatively unclear. Various model organisms offer specific advantages for gaining insight into the role of tubulin isotypes. Whereas simple unicellular organisms such as yeast provide experimental tractability that can facilitate deeper access to mechanistic details, more complex organisms, such as the fruit fly, nematode and mouse, can be used to discern potential specialized functions of tissue- and structure-specific isotypes. Here, we review the role of α- and β-tubulin isotypes in microtubule function and in associated tubulinopathies with an emphasis on the advances gained using model organisms. Overall, we argue that studying tubulin isotypes in a range of organisms can reveal the fundamental mechanisms by which they mediate microtubule function. It will also provide valuable perspectives on how these mechanisms underlie the functional and biological diversity of the cytoskeleton.
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Affiliation(s)
- Emmanuel T Nsamba
- Genetics, Development, and Cell Biology, Iowa State University, Ames, IA 50011, USA
| | - Mohan L Gupta
- Genetics, Development, and Cell Biology, Iowa State University, Ames, IA 50011, USA
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22
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Velez-Aguilera G, Ossareh-Nazari B, Van Hove L, Joly N, Pintard L. Cortical microtubule pulling forces contribute to the union of the parental genomes in the C. elegans zygote. eLife 2022; 11:75382. [PMID: 35259092 PMCID: PMC8956289 DOI: 10.7554/elife.75382] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Accepted: 03/04/2022] [Indexed: 11/23/2022] Open
Abstract
Previously, we reported that the Polo-like kinase PLK-1 phosphorylates the single Caenorhabditis elegans lamin (LMN-1) to trigger lamina depolymerization during mitosis. We showed that this event is required to form a pronuclear envelope scission event that removes membranes on the juxtaposed oocyte and sperm pronuclear envelopes in the zygote, allowing the parental chromosomes to merge in a single nucleus after segregation (Velez-Aguilera et al., 2020). Here, we show that cortical microtubule pulling forces contribute to pronuclear envelopes scission by promoting mitotic spindle elongation, and conversely, nuclear envelopes remodeling facilitates spindle elongation. We also demonstrate that weakening the pronuclear envelopes via PLK-1-mediated lamina depolymerization, is a prerequisite for the astral microtubule pulling forces to trigger pronuclear membranes scission. Finally, we provide evidence that PLK-1 mainly acts via lamina depolymerization in this process. These observations thus indicate that temporal coordination between lamina depolymerization and mitotic spindle elongation facilitates pronuclear envelopes scission and parental genomes unification.
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Affiliation(s)
| | | | - Lucie Van Hove
- Cell Cycle and Development, Institut Jacques Monod, Paris, France
| | - Nicolas Joly
- Cell Cycle and Development, Institut Jacques Monod, Paris, France
| | - Lionel Pintard
- Cell Cycle and Development, Institut Jacques Monod, Paris, France
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23
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Lacroix B, Dumont J. Spatial and Temporal Scaling of Microtubules and Mitotic Spindles. Cells 2022; 11:cells11020248. [PMID: 35053364 PMCID: PMC8774166 DOI: 10.3390/cells11020248] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Revised: 01/07/2022] [Accepted: 01/09/2022] [Indexed: 02/01/2023] Open
Abstract
During cell division, the mitotic spindle, a macromolecular structure primarily comprised of microtubules, drives chromosome alignment and partitioning between daughter cells. Mitotic spindles can sense cellular dimensions in order to adapt their length and mass to cell size. This scaling capacity is particularly remarkable during early embryo cleavage when cells divide rapidly in the absence of cell growth, thus leading to a reduction of cell volume at each division. Although mitotic spindle size scaling can occur over an order of magnitude in early embryos, in many species the duration of mitosis is relatively short, constant throughout early development and independent of cell size. Therefore, a key challenge for cells during embryo cleavage is not only to assemble a spindle of proper size, but also to do it in an appropriate time window which is compatible with embryo development. How spatial and temporal scaling of the mitotic spindle is achieved and coordinated with the duration of mitosis remains elusive. In this review, we will focus on the mechanisms that support mitotic spindle spatial and temporal scaling over a wide range of cell sizes and cellular contexts. We will present current models and propose alternative mechanisms allowing cells to spatially and temporally coordinate microtubule and mitotic spindle assembly.
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Affiliation(s)
- Benjamin Lacroix
- Centre de Recherche de Biologie Cellulaire de Montpellier (CRBM), CNRS UMR 5237, Université de Montpellier, 1919 Route de Mende, CEDEX 5, 34293 Montpellier, France
- Correspondence:
| | - Julien Dumont
- Université de Paris, CNRS, Institut Jacques Monod, F-75013 Paris, France;
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24
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Kwon M, Rubio G, Nolan N, Auteri P, Volmar JA, Adem A, Javidian P, Zhou Z, Verzi MP, Pine SR, Libutti SK. FILIP1L Loss Is a Driver of Aggressive Mucinous Colorectal Adenocarcinoma and Mediates Cytokinesis Defects through PFDN1. Cancer Res 2021; 81:5523-5539. [PMID: 34417201 DOI: 10.1158/0008-5472.can-21-0897] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Revised: 06/25/2021] [Accepted: 08/17/2021] [Indexed: 12/24/2022]
Abstract
Aneuploid mucinous colorectal adenocarcinoma (MAC) is an aggressive subtype of colorectal cancer with poor prognosis. The tumorigenic mechanisms in aneuploid MAC are currently unknown. Here we show that downregulation of Filamin A-interacting protein 1-like (FILIP1L) is a driver of MAC. Loss of FILIP1L increased xenograft growth, and, in colon-specific knockout mice, induced colonic epithelial hyperplasia and mucin secretion. The molecular chaperone prefoldin 1 (PFDN1) was identified as a novel binding partner of FILIP1L at the centrosomes throughout mitosis. FILIP1L was required for proper centrosomal localization of PFDN1 and regulated proteasome-dependent degradation of PFDN1. Importantly, increased PFDN1, caused by downregulation of FILIP1L, drove multinucleation and cytokinesis defects in vitro and in vivo, which were confirmed by time-lapse imaging and 3D cultures of normal epithelial cells. Overall, these findings suggest that downregulation of FILIP1L and subsequent upregulation of PFDN1 is a driver of the unique neoplastic characteristics in aggressive aneuploid MAC. SIGNIFICANCE: This study identifies FILIP1L as a tumor suppressor in mucinous colon cancer and demonstrates that FILIP1L loss results in aberrant stabilization of a centrosome-associated chaperone protein to drive aneuploidy and disease progression.
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Affiliation(s)
- Mijung Kwon
- Rutgers Cancer Institute of New Jersey, New Brunswick, New Jersey
| | - Genesaret Rubio
- Rutgers Cancer Institute of New Jersey, New Brunswick, New Jersey
| | - Nicholas Nolan
- Rutgers Cancer Institute of New Jersey, New Brunswick, New Jersey
| | - Peter Auteri
- Rutgers Cancer Institute of New Jersey, New Brunswick, New Jersey
| | - Jean Arly Volmar
- Rutgers Cancer Institute of New Jersey, New Brunswick, New Jersey
| | - Asha Adem
- Rutgers Cancer Institute of New Jersey, New Brunswick, New Jersey
| | - Parisa Javidian
- Department of Pathology, Robert Wood Johnson Medical School, Rutgers University, New Brunswick, New Jersey
| | - Zhongren Zhou
- Department of Pathology, Robert Wood Johnson Medical School, Rutgers University, New Brunswick, New Jersey
| | - Michael P Verzi
- Department of Genetics, Rutgers University, Piscataway, New Jersey
| | - Sharon R Pine
- Rutgers Cancer Institute of New Jersey, New Brunswick, New Jersey.,Department of Pharmacology and Medicine, Robert Wood Johnson Medical School, Rutgers University, New Brunswick, New Jersey
| | - Steven K Libutti
- Rutgers Cancer Institute of New Jersey, New Brunswick, New Jersey.
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25
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Maheshwari R, Rahman MM, Joseph-Strauss D, Cohen-Fix O. An RNAi screen for genes that affect nuclear morphology in Caenorhabditis elegans reveals the involvement of unexpected processes. G3 (BETHESDA, MD.) 2021; 11:jkab264. [PMID: 34849797 PMCID: PMC8527477 DOI: 10.1093/g3journal/jkab264] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Accepted: 07/19/2021] [Indexed: 06/13/2023]
Abstract
Aberration in nuclear morphology is one of the hallmarks of cellular transformation. However, the processes that, when mis-regulated, result aberrant nuclear morphology are poorly understood. In this study, we carried out a systematic, high-throughput RNAi screen for genes that affect nuclear morphology in Caenorhabditis elegans embryos. The screen employed over 1700 RNAi constructs against genes required for embryonic viability. Nuclei of early embryos are typically spherical, and their NPCs are evenly distributed. The screen was performed on early embryos expressing a fluorescently tagged component of the nuclear pore complex (NPC), allowing visualization of nuclear shape as well as the distribution of NPCs around the nuclear envelope. Our screen uncovered 182 genes whose downregulation resulted in one or more abnormal nuclear phenotypes, including multiple nuclei, micronuclei, abnormal nuclear shape, anaphase bridges, and abnormal NPC distribution. Many of these genes fall into common functional groups, including some that were not previously known to affect nuclear morphology, such as genes involved in mitochondrial function, the vacuolar ATPase, and the CCT chaperonin complex. The results of this screen add to our growing knowledge of processes that affect nuclear morphology and that may be altered in cancer cells that exhibit abnormal nuclear shape.
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Affiliation(s)
- Richa Maheshwari
- The Laboratory of Biochemistry and Genetics, The National Institute of Diabetes and Digestive and Kidney Diseases, The National Institutes of Health, Bethesda, MD 20892, USA
| | - Mohammad M Rahman
- The Laboratory of Biochemistry and Genetics, The National Institute of Diabetes and Digestive and Kidney Diseases, The National Institutes of Health, Bethesda, MD 20892, USA
| | - Daphna Joseph-Strauss
- The Laboratory of Biochemistry and Genetics, The National Institute of Diabetes and Digestive and Kidney Diseases, The National Institutes of Health, Bethesda, MD 20892, USA
| | - Orna Cohen-Fix
- The Laboratory of Biochemistry and Genetics, The National Institute of Diabetes and Digestive and Kidney Diseases, The National Institutes of Health, Bethesda, MD 20892, USA
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26
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Puri D, Ponniah K, Biswas K, Basu A, Dey S, Lundquist EA, Ghosh-Roy A. Wnt signaling establishes the microtubule polarity in neurons through regulation of Kinesin-13. J Cell Biol 2021; 220:212396. [PMID: 34137792 DOI: 10.1083/jcb.202005080] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Neuronal polarization is facilitated by the formation of axons with parallel arrays of plus-end-out and dendrites with the nonuniform orientation of microtubules. In C. elegans, the posterior lateral microtubule (PLM) neuron is bipolar with its two processes growing along the anterior-posterior axis under the guidance of Wnt signaling. Here we found that loss of the Kinesin-13 family microtubule-depolymerizing enzyme KLP-7 led to the ectopic extension of axon-like processes from the PLM cell body. Live imaging of the microtubules and axonal transport revealed mixed polarity of the microtubules in the short posterior process, which is dependent on both KLP-7 and the minus-end binding protein PTRN-1. KLP-7 is positively regulated in the posterior process by planar cell polarity components of Wnt involving rho-1/rock to induce mixed polarity of microtubules, whereas it is negatively regulated in the anterior process by the unc-73/ced-10 cascade to establish a uniform microtubule polarity. Our work elucidates how evolutionarily conserved Wnt signaling establishes the microtubule polarity in neurons through Kinesin-13.
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Affiliation(s)
- Dharmendra Puri
- Department of Cellular and Molecular Neuroscience, National Brain Research Centre, Manesar, Gurgaon, Haryana, India
| | - Keerthana Ponniah
- Department of Cellular and Molecular Neuroscience, National Brain Research Centre, Manesar, Gurgaon, Haryana, India
| | - Kasturi Biswas
- Department of Cellular and Molecular Neuroscience, National Brain Research Centre, Manesar, Gurgaon, Haryana, India
| | - Atrayee Basu
- Department of Cellular and Molecular Neuroscience, National Brain Research Centre, Manesar, Gurgaon, Haryana, India
| | - Swagata Dey
- Department of Cellular and Molecular Neuroscience, National Brain Research Centre, Manesar, Gurgaon, Haryana, India
| | - Erik A Lundquist
- Department of Molecular Biosciences, University of Kansas, Lawrence, KS
| | - Anindya Ghosh-Roy
- Department of Cellular and Molecular Neuroscience, National Brain Research Centre, Manesar, Gurgaon, Haryana, India
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27
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Bouvrais H, Chesneau L, Le Cunff Y, Fairbrass D, Soler N, Pastezeur S, Pécot T, Kervrann C, Pécréaux J. The coordination of spindle-positioning forces during the asymmetric division of the Caenorhabditis elegans zygote. EMBO Rep 2021; 22:e50770. [PMID: 33900015 DOI: 10.15252/embr.202050770] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Revised: 02/22/2021] [Accepted: 03/03/2021] [Indexed: 12/28/2022] Open
Abstract
In Caenorhabditis elegans zygote, astral microtubules generate forces essential to position the mitotic spindle, by pushing against and pulling from the cortex. Measuring microtubule dynamics there, we revealed the presence of two populations, corresponding to pulling and pushing events. It offers a unique opportunity to study, under physiological conditions, the variations of both spindle-positioning forces along space and time. We propose a threefold control of pulling force, by polarity, spindle position and mitotic progression. We showed that the sole anteroposterior asymmetry in dynein on-rate, encoding pulling force imbalance, is sufficient to cause posterior spindle displacement. The positional regulation, reflecting the number of microtubule contacts in the posterior-most region, reinforces this imbalance only in late anaphase. Furthermore, we exhibited the first direct proof that dynein processivity increases along mitosis. It reflects the temporal control of pulling forces, which strengthens at anaphase onset following mitotic progression and independently from chromatid separation. In contrast, the pushing force remains constant and symmetric and contributes to maintaining the spindle at the cell centre during metaphase.
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Affiliation(s)
| | | | - Yann Le Cunff
- CNRS, IGDR - UMR 6290, University of Rennes, Rennes, France
| | | | - Nina Soler
- CNRS, IGDR - UMR 6290, University of Rennes, Rennes, France
| | | | - Thierry Pécot
- INRIA, Centre Rennes - Bretagne Atlantique, Rennes, France
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28
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Chapa-Y-Lazo B, Hamanaka M, Wray A, Balasubramanian MK, Mishima M. Polar relaxation by dynein-mediated removal of cortical myosin II. J Cell Biol 2021; 219:151836. [PMID: 32497213 PMCID: PMC7401816 DOI: 10.1083/jcb.201903080] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2019] [Revised: 02/03/2020] [Accepted: 05/04/2020] [Indexed: 12/24/2022] Open
Abstract
Nearly six decades ago, Lewis Wolpert proposed the relaxation of the polar cell cortex by the radial arrays of astral microtubules as a mechanism for cleavage furrow induction. While this mechanism has remained controversial, recent work has provided evidence for polar relaxation by astral microtubules, although its molecular mechanisms remain elusive. Here, using C. elegans embryos, we show that polar relaxation is achieved through dynein-mediated removal of myosin II from the polar cortexes. Mutants that position centrosomes closer to the polar cortex accelerated furrow induction, whereas suppression of dynein activity delayed furrowing. We show that dynein-mediated removal of myosin II from the polar cortexes triggers a bidirectional cortical flow toward the cell equator, which induces the assembly of the actomyosin contractile ring. These results provide a molecular mechanism for the aster-dependent polar relaxation, which works in parallel with equatorial stimulation to promote robust cytokinesis.
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Affiliation(s)
- Bernardo Chapa-Y-Lazo
- Centre for Mechanochemical Cell Biology & Division of Biomedical Sciences, Warwick Medical School, Coventry, UK
| | - Motonari Hamanaka
- Centre for Mechanochemical Cell Biology & Division of Biomedical Sciences, Warwick Medical School, Coventry, UK.,Hokkaido University, Sapporo, Japan
| | - Alexander Wray
- Centre for Mechanochemical Cell Biology & Division of Biomedical Sciences, Warwick Medical School, Coventry, UK.,University of Nottingham, Nottingham, UK
| | - Mohan K Balasubramanian
- Centre for Mechanochemical Cell Biology & Division of Biomedical Sciences, Warwick Medical School, Coventry, UK
| | - Masanori Mishima
- Centre for Mechanochemical Cell Biology & Division of Biomedical Sciences, Warwick Medical School, Coventry, UK
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29
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Mimori-Kiyosue Y. Imaging mitotic processes in three dimensions with lattice light-sheet microscopy. Chromosome Res 2021; 29:37-50. [PMID: 33694045 PMCID: PMC8058003 DOI: 10.1007/s10577-021-09656-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Revised: 02/17/2021] [Accepted: 02/19/2021] [Indexed: 12/11/2022]
Abstract
There are few technologies that can capture mitotic processes occurring in three-dimensional space with the desired spatiotemporal resolution. Due to such technical limitations, our understanding of mitosis, which has been studied since the early 1880s, is still incomplete with regard to mitotic processes and their regulatory mechanisms at a molecular level. A recently developed high-resolution type of light-sheet microscopy, lattice light-sheet microscopy (LLSM), has achieved unprecedented spatiotemporal resolution scans of intracellular spaces at the whole-cell level. This technology enables experiments that were not possible before (e.g., tracking of growth of every spindle microtubule end and discrimination of individual chromosomes in living cells), thus providing a new avenue for the analysis of mitotic processes. Herein, principles of LLSM technology are introduced, as well as experimental techniques that became possible with LLSM. In addition, issues remaining to be solved for use of this technology in mitosis research, big image data problems, are presented to help guide mitosis research into a new era.
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Affiliation(s)
- Yuko Mimori-Kiyosue
- Laboratory for Molecular and Cellular Dynamics, RIKEN Center for Biosystems Dynamics Research, 2-2-3 Minatojima-minamimachi, Chuo-ku, Kobe, 650-0047, Japan.
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30
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Spindle scaling mechanisms. Essays Biochem 2021; 64:383-396. [PMID: 32501481 DOI: 10.1042/ebc20190064] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Revised: 05/11/2020] [Accepted: 05/12/2020] [Indexed: 02/02/2023]
Abstract
The mitotic spindle robustly scales with cell size in a plethora of different organisms. During development and throughout evolution, the spindle adjusts to cell size in metazoans and yeast in order to ensure faithful chromosome separation. Spindle adjustment to cell size occurs by the scaling of spindle length, spindle shape and the velocity of spindle assembly and elongation. Different mechanisms, depending on spindle structure and organism, account for these scaling relationships. The limited availability of critical spindle components, protein gradients, sequestration of spindle components, or post-translational modification and differential expression levels have been implicated in the regulation of spindle length and the spindle assembly/elongation velocity in a cell size-dependent manner. In this review, we will discuss the phenomenon and mechanisms of spindle length, spindle shape and spindle elongation velocity scaling with cell size.
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31
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Lantzsch I, Yu CH, Chen YZ, Zimyanin V, Yazdkhasti H, Lindow N, Szentgyoergyi E, Pani AM, Prohaska S, Srayko M, Fürthauer S, Redemann S. Microtubule reorganization during female meiosis in C. elegans. eLife 2021; 10:58903. [PMID: 34114562 PMCID: PMC8225387 DOI: 10.7554/elife.58903] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Accepted: 05/24/2021] [Indexed: 02/01/2023] Open
Abstract
Most female meiotic spindles undergo striking morphological changes while transitioning from metaphase to anaphase. The ultra-structure of meiotic spindles, and how changes to this structure correlate with such dramatic spindle rearrangements remains largely unknown. To address this, we applied light microscopy, large-scale electron tomography and mathematical modeling of female meiotic Caenorhabditis elegans spindles. Combining these approaches, we find that meiotic spindles are dynamic arrays of short microtubules that turn over within seconds. The results show that the metaphase to anaphase transition correlates with an increase in microtubule numbers and a decrease in their average length. Detailed analysis of the tomographic data revealed that the microtubule length changes significantly during the metaphase-to-anaphase transition. This effect is most pronounced for microtubules located within 150 nm of the chromosome surface. To understand the mechanisms that drive this transition, we developed a mathematical model for the microtubule length distribution that considers microtubule growth, catastrophe, and severing. Using Bayesian inference to compare model predictions and data, we find that microtubule turn-over is the major driver of the spindle reorganizations. Our data suggest that in metaphase only a minor fraction of microtubules, those closest to the chromosomes, are severed. The large majority of microtubules, which are not in close contact with chromosomes, do not undergo severing. Instead, their length distribution is fully explained by growth and catastrophe. This suggests that the most prominent drivers of spindle rearrangements are changes in nucleation and catastrophe rate. In addition, we provide evidence that microtubule severing is dependent on katanin.
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Affiliation(s)
- Ina Lantzsch
- Experimental Center, Faculty of Medicine Carl Gustav Carus, Technische Universität DresdenDresdenGermany
| | - Che-Hang Yu
- Department of Electrical and Computer Engineering, University of California, Santa BarbaraSanta BarbaraUnited States
| | - Yu-Zen Chen
- Center for Membrane and Cell Physiology, University of Virginia School of MedicineCharlottesvilleUnited States,Department of Molecular Physiology and Biological Physics, University of Virginia, School of MedicineCharlottesvilleUnited States
| | - Vitaly Zimyanin
- Center for Membrane and Cell Physiology, University of Virginia School of MedicineCharlottesvilleUnited States,Department of Molecular Physiology and Biological Physics, University of Virginia, School of MedicineCharlottesvilleUnited States
| | - Hossein Yazdkhasti
- Center for Membrane and Cell Physiology, University of Virginia School of MedicineCharlottesvilleUnited States,Department of Molecular Physiology and Biological Physics, University of Virginia, School of MedicineCharlottesvilleUnited States
| | | | - Erik Szentgyoergyi
- Experimental Center, Faculty of Medicine Carl Gustav Carus, Technische Universität DresdenDresdenGermany
| | - Ariel M Pani
- Department of Biology, University of VirginiaCharlottesvilleUnited States,Department of Cell Biology, University of Virginia School of MedicineCharlottesvilleUnited States
| | | | - Martin Srayko
- Department of Biological Sciences, University of AlbertaEdmontonCanada
| | | | - Stefanie Redemann
- Center for Membrane and Cell Physiology, University of Virginia School of MedicineCharlottesvilleUnited States,Department of Molecular Physiology and Biological Physics, University of Virginia, School of MedicineCharlottesvilleUnited States,Department of Cell Biology, University of Virginia School of MedicineCharlottesvilleUnited States
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32
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Farhadifar R, Yu CH, Fabig G, Wu HY, Stein DB, Rockman M, Müller-Reichert T, Shelley MJ, Needleman DJ. Stoichiometric interactions explain spindle dynamics and scaling across 100 million years of nematode evolution. eLife 2020; 9:e55877. [PMID: 32966209 PMCID: PMC7511230 DOI: 10.7554/elife.55877] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2020] [Accepted: 08/31/2020] [Indexed: 01/17/2023] Open
Abstract
The spindle shows remarkable diversity, and changes in an integrated fashion, as cells vary over evolution. Here, we provide a mechanistic explanation for variations in the first mitotic spindle in nematodes. We used a combination of quantitative genetics and biophysics to rule out broad classes of models of the regulation of spindle length and dynamics, and to establish the importance of a balance of cortical pulling forces acting in different directions. These experiments led us to construct a model of cortical pulling forces in which the stoichiometric interactions of microtubules and force generators (each force generator can bind only one microtubule), is key to explaining the dynamics of spindle positioning and elongation, and spindle final length and scaling with cell size. This model accounts for variations in all the spindle traits we studied here, both within species and across nematode species spanning over 100 million years of evolution.
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Affiliation(s)
- Reza Farhadifar
- Department of Molecular and Cellular Biology and School of Engineering and Applied Sciences, Harvard UniversityCambridgeUnited States
- Center for Computational Biology, Flatiron InstituteNew YorkUnited States
| | - Che-Hang Yu
- Department of Molecular and Cellular Biology and School of Engineering and Applied Sciences, Harvard UniversityCambridgeUnited States
| | - Gunar Fabig
- Experimental Center, Faculty of Medicine Carl Gustav CarusDresdenGermany
| | - Hai-Yin Wu
- Department of Molecular and Cellular Biology and School of Engineering and Applied Sciences, Harvard UniversityCambridgeUnited States
| | - David B Stein
- Center for Computational Biology, Flatiron InstituteNew YorkUnited States
| | - Matthew Rockman
- Department of Biology and Center for Genomics & Systems Biology, New York UniversityNew YorkUnited States
| | | | - Michael J Shelley
- Center for Computational Biology, Flatiron InstituteNew YorkUnited States
- Courant Institute, New York UniversityNew YorkUnited States
| | - Daniel J Needleman
- Department of Molecular and Cellular Biology and School of Engineering and Applied Sciences, Harvard UniversityCambridgeUnited States
- Center for Computational Biology, Flatiron InstituteNew YorkUnited States
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33
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Rondelet A, Lin YC, Singh D, Porfetye AT, Thakur HC, Hecker A, Brinkert P, Schmidt N, Bendre S, Müller F, Mazul L, Widlund PO, Bange T, Hiller M, Vetter IR, Bird AW. Clathrin's adaptor interaction sites are repurposed to stabilize microtubules during mitosis. J Cell Biol 2020; 219:133599. [PMID: 31932847 PMCID: PMC7041688 DOI: 10.1083/jcb.201907083] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2019] [Revised: 10/31/2019] [Accepted: 11/24/2019] [Indexed: 11/22/2022] Open
Abstract
Clathrin ensures mitotic spindle stability and efficient chromosome alignment, independently of its vesicle trafficking function. Although clathrin localizes to the mitotic spindle and kinetochore fiber microtubule bundles, the mechanisms by which clathrin stabilizes microtubules are unclear. We show that clathrin adaptor interaction sites on clathrin heavy chain (CHC) are repurposed during mitosis to directly recruit the microtubule-stabilizing protein GTSE1 to the spindle. Structural analyses reveal that these sites interact directly with clathrin-box motifs on GTSE1. Disruption of this interaction releases GTSE1 from spindles, causing defects in chromosome alignment. Surprisingly, this disruption destabilizes astral microtubules, but not kinetochore-microtubule attachments, and chromosome alignment defects are due to a failure of chromosome congression independent of kinetochore-microtubule attachment stability. GTSE1 recruited to the spindle by clathrin stabilizes microtubules by inhibiting the microtubule depolymerase MCAK. This work uncovers a novel role of clathrin adaptor-type interactions to stabilize nonkinetochore fiber microtubules to support chromosome congression, defining for the first time a repurposing of this endocytic interaction mechanism during mitosis.
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Affiliation(s)
- Arnaud Rondelet
- Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Yu-Chih Lin
- Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Divya Singh
- Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | | | - Harish C Thakur
- Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Andreas Hecker
- Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Pia Brinkert
- Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Nadine Schmidt
- Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Shweta Bendre
- Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | | | - Lisa Mazul
- Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Per O Widlund
- Institute of Biomedicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Tanja Bange
- Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Michael Hiller
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany.,Max Planck Institute for the Physics of Complex Systems, Dresden, Germany.,Center for Systems Biology, Dresden, Germany
| | - Ingrid R Vetter
- Max Planck Institute of Molecular Physiology, Dortmund, Germany
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34
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Cell Biology: Social Distancing of Microtubule Ends Increases Their Assembly Rates. Curr Biol 2020; 30:R888-R890. [PMID: 32750351 DOI: 10.1016/j.cub.2020.06.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Microtubules assembled from artificial centrosomes in microfluidic chambers of defined size are amenable to high resolution live imaging of their dynamics and space-filling properties. By using this experimental regime in conjunction with cytoplasmic extract, a new study finds that microtubule end density negatively influences their assembly rates.
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35
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Geisterfer ZM, Zhu DY, Mitchison TJ, Oakey J, Gatlin JC. Microtubule Growth Rates Are Sensitive to Global and Local Changes in Microtubule Plus-End Density. Curr Biol 2020; 30:3016-3023.e3. [PMID: 32531285 DOI: 10.1016/j.cub.2020.05.056] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2020] [Revised: 04/14/2020] [Accepted: 05/18/2020] [Indexed: 01/02/2023]
Abstract
The microtubule cytoskeleton plays critically important roles in numerous cellular functions in eukaryotes, and it does so across a functionally diverse and morphologically disparate range of cell types [1]. In these roles, microtubule assemblies must adopt distinct morphologies and physical dimensions to perform specific functions [2-5]. As such, these macromolecular assemblies-as well as the dynamics of the individual microtubule polymers from which they are made-must scale and change in accordance with cell size, geometry, and function. Microtubules in cells typically assemble to a steady state in mass, leaving enough of their tubulin subunits soluble to allow rapid growth and turnover. This suggests some negative feedback that limits the extent of assembly, for example, decrease in growth rate, or increase in catastrophe rate, as the soluble subunit pool decreases. Although these ideas have informed the field for decades, they have not been observed experimentally. Here, we describe the application of an experimental approach that combines cell-free extracts with photo-patterned hydrogel micro-enclosures as a means to investigate microtubule dynamics in cytoplasmic volumes of defined size and shape. Our measurements reveal a negative correlation between microtubule plus-end density and microtubule growth rates and suggest that these rates are sensitive to the presence of nearby growing ends.
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Affiliation(s)
- Zachary M Geisterfer
- Department of Molecular Biology, University of Wyoming, 1000 E. University Avenue, Laramie, WY 82070, USA.
| | - Daniel Y Zhu
- Department of Molecular Biology, University of Wyoming, 1000 E. University Avenue, Laramie, WY 82070, USA
| | - Timothy J Mitchison
- Department of Systems Biology, Harvard Medical School, 25 Shattuck Street, Boston, MA 02115, USA; Marine Biological Laboratory, Cell Division and Organization Group, 7 MBL Street, Woods Hole, MA 02543, USA
| | - John Oakey
- Marine Biological Laboratory, Cell Division and Organization Group, 7 MBL Street, Woods Hole, MA 02543, USA; Department of Chemical Engineering, University of Wyoming, 1000 E. University Avenue, Laramie, WY 82070, USA
| | - Jesse C Gatlin
- Department of Molecular Biology, University of Wyoming, 1000 E. University Avenue, Laramie, WY 82070, USA; Marine Biological Laboratory, Cell Division and Organization Group, 7 MBL Street, Woods Hole, MA 02543, USA.
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36
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Yamashita N, Morita M, Yokota H, Mimori-Kiyosue Y. Digital Spindle: A New Way to Explore Mitotic Functions by Whole Cell Data Collection and a Computational Approach. Cells 2020; 9:E1255. [PMID: 32438637 PMCID: PMC7291015 DOI: 10.3390/cells9051255] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Revised: 05/15/2020] [Accepted: 05/17/2020] [Indexed: 02/06/2023] Open
Abstract
From cells to organisms, every living system is three-dimensional (3D), but the performance of fluorescence microscopy has been largely limited when attempting to obtain an overview of systems' dynamic processes in three dimensions. Recently, advanced light-sheet illumination technologies, allowing drastic improvement in spatial discrimination, volumetric imaging times, and phototoxicity/photobleaching, have been making live imaging to collect precise and reliable 3D information increasingly feasible. In particular, lattice light-sheet microscopy (LLSM), using an ultrathin light-sheet, enables whole-cell 3D live imaging of cellular processes, including mitosis, at unprecedented spatiotemporal resolution for extended periods of time. This technology produces immense and complex data, including a significant amount of information, raising new challenges for big image data analysis and new possibilities for data utilization. Once the data are digitally archived in a computer, the data can be reused for various purposes by anyone at any time. Such an information science approach has the potential to revolutionize the use of bioimage data, and provides an alternative method for cell biology research in a data-driven manner. In this article, we introduce examples of analyzing digital mitotic spindles and discuss future perspectives in cell biology.
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Affiliation(s)
- Norio Yamashita
- Image Processing Research Team, RIKEN Center for Advanced Photonics, 2-1, Hirosawa, Wako, Saitama 351-0198, Japan; (N.Y.); (M.M.); (H.Y.)
| | - Masahiko Morita
- Image Processing Research Team, RIKEN Center for Advanced Photonics, 2-1, Hirosawa, Wako, Saitama 351-0198, Japan; (N.Y.); (M.M.); (H.Y.)
| | - Hideo Yokota
- Image Processing Research Team, RIKEN Center for Advanced Photonics, 2-1, Hirosawa, Wako, Saitama 351-0198, Japan; (N.Y.); (M.M.); (H.Y.)
| | - Yuko Mimori-Kiyosue
- Laboratory for Molecular and Cellular Dynamics, RIKEN Center for Biosystems Dynamics Research (BDR), 2-2-3 Minatojima-minamimachi, Chuo-ku, Kobe 650-0047, Japan
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37
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Meaders JL, Burgess DR. Microtubule-Based Mechanisms of Pronuclear Positioning. Cells 2020; 9:E505. [PMID: 32102180 PMCID: PMC7072840 DOI: 10.3390/cells9020505] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Revised: 02/18/2020] [Accepted: 02/19/2020] [Indexed: 12/22/2022] Open
Abstract
The zygote is defined as a diploid cell resulting from the fusion of two haploid gametes. Union of haploid male and female pronuclei in many animals occurs through rearrangements of the microtubule cytoskeleton into a radial array of microtubules known as the sperm aster. The sperm aster nucleates from paternally-derived centrioles attached to the male pronucleus after fertilization. Nematode, echinoderm, and amphibian eggs have proven as invaluable models to investigate the biophysical principles for how the sperm aster unites male and female pronuclei with precise spatial and temporal regulation. In this review, we compare these model organisms, discussing the dynamics of sperm aster formation and the different force generating mechanism for sperm aster and pronuclear migration. Finally, we provide new mechanistic insights for how sperm aster growth may influence sperm aster positioning.
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Affiliation(s)
| | - David R Burgess
- Department of Biology, Boston College, Chestnut Hill, MA 02467, USA
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38
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Taffoni C, Omi S, Huber C, Mailfert S, Fallet M, Rupprecht JF, Ewbank JJ, Pujol N. Microtubule plus-end dynamics link wound repair to the innate immune response. eLife 2020; 9:e45047. [PMID: 31995031 PMCID: PMC7043892 DOI: 10.7554/elife.45047] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2019] [Accepted: 01/27/2020] [Indexed: 01/20/2023] Open
Abstract
The skin protects animals from infection and physical damage. In Caenorhabditis elegans, wounding the epidermis triggers an immune reaction and a repair response, but it is not clear how these are coordinated. Previous work implicated the microtubule cytoskeleton in the maintenance of epidermal integrity (Chuang et al., 2016). Here, by establishing a simple wounding system, we show that wounding provokes a reorganisation of plasma membrane subdomains. This is followed by recruitment of the microtubule plus end-binding protein EB1/EBP-2 around the wound and actin ring formation, dependent on ARP2/3 branched actin polymerisation. We show that microtubule dynamics are required for the recruitment and closure of the actin ring, and for the trafficking of the key signalling protein SLC6/SNF-12 toward the injury site. Without SNF-12 recruitment, there is an abrogation of the immune response. Our results suggest that microtubule dynamics coordinate the cytoskeletal changes required for wound repair and the concomitant activation of innate immunity.
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Affiliation(s)
- Clara Taffoni
- CIML, Centre d’Immunologie de Marseille-Luminy, Turing Centre for Living SystemsAix Marseille Univ, INSERM, CNRSMarseilleFrance
| | - Shizue Omi
- CIML, Centre d’Immunologie de Marseille-Luminy, Turing Centre for Living SystemsAix Marseille Univ, INSERM, CNRSMarseilleFrance
| | - Caroline Huber
- CIML, Centre d’Immunologie de Marseille-Luminy, Turing Centre for Living SystemsAix Marseille Univ, INSERM, CNRSMarseilleFrance
| | - Sébastien Mailfert
- CIML, Centre d’Immunologie de Marseille-Luminy, Turing Centre for Living SystemsAix Marseille Univ, INSERM, CNRSMarseilleFrance
| | - Mathieu Fallet
- CIML, Centre d’Immunologie de Marseille-Luminy, Turing Centre for Living SystemsAix Marseille Univ, INSERM, CNRSMarseilleFrance
| | | | - Jonathan J Ewbank
- CIML, Centre d’Immunologie de Marseille-Luminy, Turing Centre for Living SystemsAix Marseille Univ, INSERM, CNRSMarseilleFrance
| | - Nathalie Pujol
- CIML, Centre d’Immunologie de Marseille-Luminy, Turing Centre for Living SystemsAix Marseille Univ, INSERM, CNRSMarseilleFrance
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39
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Bondaz A, Cirillo L, Meraldi P, Gotta M. Cell polarity-dependent centrosome separation in the C. elegans embryo. J Cell Biol 2019; 218:4112-4126. [PMID: 31645459 PMCID: PMC6891102 DOI: 10.1083/jcb.201902109] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Revised: 07/10/2019] [Accepted: 09/06/2019] [Indexed: 12/30/2022] Open
Abstract
Bondaz et al. show that in C. elegans embryos, the microtubule depolymerase KLP-7/MCAK is required for efficient centrosome separation in the somatic AB cell, but not the germline P1 cell. This difference in spindle assembly depends on cell polarity via the mitotic kinase PLK1. In animal cells, faithful chromosome segregation depends on the assembly of a bipolar spindle driven by the timely separation of the two centrosomes. Here we took advantage of the highly stereotypical cell divisions in Caenorhabditis elegans embryos to identify new regulators of centrosome separation. We find that at the two-cell stage, the somatic AB cell initiates centrosome separation later than the germline P1 cell. This difference is strongly exacerbated by the depletion of the kinesin-13 KLP-7/MCAK, resulting in incomplete centrosome separation at NEBD in AB but not P1. Our genetic and cell biology data indicate that this phenotype depends on cell polarity via the enrichment in AB of the mitotic kinase PLK-1, which itself limits the cortical localization of the dynein-binding NuMA orthologue LIN-5. We postulate that the timely separation of centrosomes is regulated in a cell type–dependent manner.
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Affiliation(s)
- Alexandra Bondaz
- Department of Cell Physiology and Metabolism, Faculty of Medicine, University of Geneva, Geneva, Switzerland.,Translational Research Centre in Onco-hematology, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Luca Cirillo
- Department of Cell Physiology and Metabolism, Faculty of Medicine, University of Geneva, Geneva, Switzerland.,Translational Research Centre in Onco-hematology, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Patrick Meraldi
- Department of Cell Physiology and Metabolism, Faculty of Medicine, University of Geneva, Geneva, Switzerland .,Translational Research Centre in Onco-hematology, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Monica Gotta
- Department of Cell Physiology and Metabolism, Faculty of Medicine, University of Geneva, Geneva, Switzerland .,Translational Research Centre in Onco-hematology, Faculty of Medicine, University of Geneva, Geneva, Switzerland.,Swiss National Centre for Competence in Research in Chemical Biology, University of Geneva, Geneva, Switzerland
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40
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Vargas E, McNally KP, Cortes DB, Panzica MT, Danlasky BM, Li Q, Maddox AS, McNally FJ. Spherical spindle shape promotes perpendicular cortical orientation by preventing isometric cortical pulling on both spindle poles during C. elegans female meiosis. Development 2019; 146:dev.178863. [PMID: 31575646 DOI: 10.1242/dev.178863] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Accepted: 09/16/2019] [Indexed: 12/13/2022]
Abstract
Meiotic spindles are positioned perpendicular to the oocyte cortex to facilitate segregation of chromosomes into a large egg and a tiny polar body. In C. elegans, spindles are initially ellipsoid and parallel to the cortex before shortening to a near-spherical shape with flattened poles and then rotating to the perpendicular orientation by dynein-driven cortical pulling. The mechanistic connection between spindle shape and rotation has remained elusive. Here, we have used three different genetic backgrounds to manipulate spindle shape without eliminating dynein-dependent movement or dynein localization. Ellipsoid spindles with flattened or pointed poles became trapped in either a diagonal or a parallel orientation. Mathematical models that recapitulated the shape dependence of rotation indicated that the lower viscous drag experienced by spherical spindles prevented recapture of the cortex by astral microtubules emanating from the pole pivoting away from the cortex. In addition, maximizing contact between pole dynein and cortical dynein stabilizes flattened poles in a perpendicular orientation, and spindle rigidity prevents spindle bending that can lock both poles at the cortex. Spindle shape can thus promote perpendicular orientation by three distinct mechanisms.
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Affiliation(s)
- Elizabeth Vargas
- Department of Molecular and Cellular Biology, University of California, Davis, Davis, CA 95616, USA
| | - Karen P McNally
- Department of Molecular and Cellular Biology, University of California, Davis, Davis, CA 95616, USA
| | - Daniel B Cortes
- Biology Department, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Michelle T Panzica
- Department of Molecular and Cellular Biology, University of California, Davis, Davis, CA 95616, USA
| | - Brennan M Danlasky
- Department of Molecular and Cellular Biology, University of California, Davis, Davis, CA 95616, USA
| | - Qianyan Li
- Department of Molecular and Cellular Biology, University of California, Davis, Davis, CA 95616, USA
| | - Amy Shaub Maddox
- Biology Department, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Francis J McNally
- Department of Molecular and Cellular Biology, University of California, Davis, Davis, CA 95616, USA
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41
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Gujar MR, Stricker AM, Lundquist EA. RHO-1 and the Rho GEF RHGF-1 interact with UNC-6/Netrin signaling to regulate growth cone protrusion and microtubule organization in Caenorhabditis elegans. PLoS Genet 2019; 15:e1007960. [PMID: 31233487 PMCID: PMC6611649 DOI: 10.1371/journal.pgen.1007960] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2019] [Revised: 07/05/2019] [Accepted: 05/31/2019] [Indexed: 01/02/2023] Open
Abstract
UNC-6/Netrin is a conserved axon guidance cue that directs growth cone migrations in the dorsal-ventral axis of C. elegans and in the vertebrate spinal cord. UNC-6/Netrin is expressed in ventral cells, and growth cones migrate ventrally toward or dorsally away from UNC-6/Netrin. Recent studies of growth cone behavior during outgrowth in vivo in C. elegans have led to a polarity/protrusion model in directed growth cone migration away from UNC-6/Netrin. In this model, UNC-6/Netrin first polarizes the growth cone via the UNC-5 receptor, leading to dorsally biased protrusion and F-actin accumulation. UNC-6/Netrin then regulates protrusion based on this polarity. The receptor UNC-40/DCC drives protrusion dorsally, away from the UNC-6/Netrin source, and the UNC-5 receptor inhibits protrusion ventrally, near the UNC-6/Netrin source, resulting in dorsal migration. UNC-5 inhibits protrusion in part by excluding microtubules from the growth cone, which are pro-protrusive. Here we report that the RHO-1/RhoA GTPase and its activator GEF RHGF-1 inhibit growth cone protrusion and MT accumulation in growth cones, similar to UNC-5. However, growth cone polarity of protrusion and F-actin were unaffected by RHO-1 and RHGF-1. Thus, RHO-1 signaling acts specifically as a negative regulator of protrusion and MT accumulation, and not polarity. Genetic interactions are consistent with RHO-1 and RHGF-1 acting with UNC-5, as well as with a parallel pathway, to regulate protrusion. The cytoskeletal interacting molecule UNC-33/CRMP was required for RHO-1 activity to inhibit MT accumulation, suggesting that UNC-33/CRMP might act downstream of RHO-1. In sum, these studies describe a new role of RHO-1 and RHGF-1 in regulation of growth cone protrusion by UNC-6/Netrin.
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Affiliation(s)
- Mahekta R. Gujar
- Department of Molecular Biosciences, Program in Molecular, Cellular, and Developmental Biology, University of Kansas, Lawrence, KS, United States of America
| | - Aubrie M. Stricker
- Department of Molecular Biosciences, Program in Molecular, Cellular, and Developmental Biology, University of Kansas, Lawrence, KS, United States of America
| | - Erik A. Lundquist
- Department of Molecular Biosciences, Program in Molecular, Cellular, and Developmental Biology, University of Kansas, Lawrence, KS, United States of America
- * E-mail:
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42
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Kinetochore Recruitment of the Spindle and Kinetochore-Associated (Ska) Complex Is Regulated by Centrosomal PP2A in Caenorhabditis elegans. Genetics 2019; 212:509-522. [PMID: 31018924 DOI: 10.1534/genetics.119.302105] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2018] [Accepted: 04/07/2019] [Indexed: 12/31/2022] Open
Abstract
During mitosis, kinetochore-microtubule interactions ensure that chromosomes are accurately segregated to daughter cells. RSA-1 (regulator of spindle assembly-1) is a regulatory B″ subunit of protein phosphatase 2A that was previously proposed to modulate microtubule dynamics during spindle assembly. We have identified a genetic interaction between the centrosomal protein, RSA-1, and the spindle- and kinetochore-associated (Ska) complex in Caenorhabditis elegans In a forward genetic screen for suppressors of rsa-1(or598) embryonic lethality, we identified mutations in ska-1 and ska-3 Loss of SKA-1 and SKA-3, as well as components of the KMN (KNL-1/MIS-12/NDC-80) complex and the microtubule end-binding protein EBP-2, all suppressed the embryonic lethality of rsa-1(or598) These suppressors also disrupted the intracellular localization of the Ska complex, revealing a network of proteins that influence Ska function during mitosis. In rsa-1(or598) embryos, SKA-1 is excessively and prematurely recruited to kinetochores during spindle assembly, but SKA-1 levels return to normal just prior to anaphase onset. Loss of the TPX2 homolog, TPXL-1, also resulted in overrecruitment of SKA-1 to the kinetochores and this correlated with the loss of Aurora A kinase on the spindle microtubules. We propose that rsa-1 regulates the kinetochore localization of the Ska complex, with spindle-associated Aurora A acting as a potential mediator. These data reveal a novel mechanism of protein phosphatase 2A function during mitosis involving a centrosome-based regulatory mechanism for Ska complex recruitment to the kinetochore.
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43
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Boudreau V, Chen R, Edwards A, Sulaimain M, Maddox PS. PP2A-B55/SUR-6 collaborates with the nuclear lamina for centrosome separation during mitotic entry. Mol Biol Cell 2019; 30:876-886. [PMID: 30840554 PMCID: PMC6589783 DOI: 10.1091/mbc.e18-10-0631] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Across most sexually reproducing animals, centrosomes are provided to the oocyte through fertilization and must be positioned properly to establish the zygotic mitotic spindle. How centrosomes are positioned in space and time through the concerted action of key mitotic entry biochemical regulators, including protein phosphatase 2A (PP2A-B55/SUR-6), biophysical regulators, including dynein, and the nuclear lamina is unclear. Here, we uncover a role for PP2A-B55/SUR-6 in regulating centrosome separation. Mechanistically, PP2A-B55/SUR-6 regulates nuclear size before mitotic entry, in turn affecting nuclear envelope–based dynein density and motor capacity. Computational simulations predicted the requirement of PP2A-B55/SUR-6 regulation of nuclear size and nuclear-envelope dynein density for proper centrosome separation. Conversely, compromising nuclear lamina integrity led to centrosome detachment from the nuclear envelope and migration defects. Removal of PP2A-B55/SUR-6 and the nuclear lamina simultaneously further disrupted centrosome separation, leading to unseparated centrosome pairs dissociated from the nuclear envelope. Taking these combined results into consideration, we propose a model in which centrosomes migrate and are positioned through the concerted action of PP2A-B55/SUR-6–regulated nuclear envelope–based dynein pulling forces and centrosome–nuclear envelope tethering. Our results add critical precision to models of centrosome separation relative to the nucleus during spindle formation in cell division.
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Affiliation(s)
- Vincent Boudreau
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27514
| | - Richard Chen
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27514
| | - Alan Edwards
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27514
| | - Muhammad Sulaimain
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27514
| | - Paul S Maddox
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27514
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44
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Moura M, Conde C. Phosphatases in Mitosis: Roles and Regulation. Biomolecules 2019; 9:E55. [PMID: 30736436 PMCID: PMC6406801 DOI: 10.3390/biom9020055] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2018] [Revised: 01/31/2019] [Accepted: 02/01/2019] [Indexed: 02/07/2023] Open
Abstract
Mitosis requires extensive rearrangement of cellular architecture and of subcellular structures so that replicated chromosomes can bind correctly to spindle microtubules and segregate towards opposite poles. This process originates two new daughter nuclei with equal genetic content and relies on highly-dynamic and tightly regulated phosphorylation of numerous cell cycle proteins. A burst in protein phosphorylation orchestrated by several conserved kinases occurs as cells go into and progress through mitosis. The opposing dephosphorylation events are catalyzed by a small set of protein phosphatases, whose importance for the accuracy of mitosis is becoming increasingly appreciated. This review will focus on the established and emerging roles of mitotic phosphatases, describe their structural and biochemical properties, and discuss recent advances in understanding the regulation of phosphatase activity and function.
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Affiliation(s)
- Margarida Moura
- IBMC-Instituto de Biologia Molecular e Celular, Universidade do Porto, 4200-135 Porto, Portugal.
- i3S-Instituto de Investigação e Inovação em Saúde da Universidade do Porto, 4200-135, Porto, Portugal.
- Programa Doutoral em Biologia Molecular e Celular (MCbiology), Instituto de Ciências Biomédicas Abel Salazar (ICBAS), Universidade do Porto, 4050-313 Porto, Portugal.
| | - Carlos Conde
- IBMC-Instituto de Biologia Molecular e Celular, Universidade do Porto, 4200-135 Porto, Portugal.
- i3S-Instituto de Investigação e Inovação em Saúde da Universidade do Porto, 4200-135, Porto, Portugal.
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45
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Pintard L, Bowerman B. Mitotic Cell Division in Caenorhabditis elegans. Genetics 2019; 211:35-73. [PMID: 30626640 PMCID: PMC6325691 DOI: 10.1534/genetics.118.301367] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2018] [Accepted: 10/24/2018] [Indexed: 11/18/2022] Open
Abstract
Mitotic cell divisions increase cell number while faithfully distributing the replicated genome at each division. The Caenorhabditis elegans embryo is a powerful model for eukaryotic cell division. Nearly all of the genes that regulate cell division in C. elegans are conserved across metazoan species, including humans. The C. elegans pathways tend to be streamlined, facilitating dissection of the more redundant human pathways. Here, we summarize the virtues of C. elegans as a model system and review our current understanding of centriole duplication, the acquisition of pericentriolar material by centrioles to form centrosomes, the assembly of kinetochores and the mitotic spindle, chromosome segregation, and cytokinesis.
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Affiliation(s)
- Lionel Pintard
- Equipe labellisée Ligue contre le Cancer, Institut Jacques Monod, Team Cell Cycle and Development UMR7592, Centre National de la Recherche Scientifique - Université Paris Diderot, Sorbonne Paris Cité, 75013 Paris, France
| | - Bruce Bowerman
- Institute of Molecular Biology, University of Oregon, Eugene, OR 97403
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46
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Rodriguez-Garcia R, Chesneau L, Pastezeur S, Roul J, Tramier M, Pécréaux J. The polarity-induced force imbalance in Caenorhabditis elegans embryos is caused by asymmetric binding rates of dynein to the cortex. Mol Biol Cell 2018; 29:3093-3104. [PMID: 30332325 PMCID: PMC6340208 DOI: 10.1091/mbc.e17-11-0653] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2017] [Revised: 10/04/2018] [Accepted: 10/10/2018] [Indexed: 12/17/2022] Open
Abstract
During asymmetric cell division, the molecular motor dynein generates cortical pulling forces that position the spindle to reflect polarity and adequately distribute cell fate determinants. In Caenorhabditis elegans embryos, despite a measured anteroposterior force imbalance, antibody staining failed to reveal dynein enrichment at the posterior cortex, suggesting a transient localization there. Dynein accumulates at the microtubule plus ends, in an EBP-2EB-dependent manner. This accumulation, although not transporting dynein, contributes modestly to cortical forces. Most dyneins may instead diffuse to the cortex. Tracking of cortical dynein revealed two motions: one directed and the other diffusive-like, corresponding to force-generating events. Surprisingly, while dynein is not polarized at the plus ends or in the cytoplasm, diffusive-like tracks were more frequently found at the embryo posterior tip, where the forces are higher. This asymmetry depends on GPR-1/2LGN and LIN-5NuMA, which are enriched there. In csnk-1(RNAi) embryos, the inverse distribution of these proteins coincides with an increased frequency of diffusive-like tracks anteriorly. Importantly, dynein cortical residence time is always symmetric. We propose that the dynein-binding rate at the posterior cortex is increased, causing the polarity-reflecting force imbalance. This mechanism of control supplements the regulation of mitotic progression through the nonpolarized dynein detachment rate.
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Affiliation(s)
- Ruddi Rodriguez-Garcia
- CNRS, Univ Rennes, IGDR (Institute of Genetics and Development of Rennes)–UMR 6290, F-35000 Rennes, France
| | - Laurent Chesneau
- CNRS, Univ Rennes, IGDR (Institute of Genetics and Development of Rennes)–UMR 6290, F-35000 Rennes, France
| | - Sylvain Pastezeur
- CNRS, Univ Rennes, IGDR (Institute of Genetics and Development of Rennes)–UMR 6290, F-35000 Rennes, France
| | - Julien Roul
- CNRS, Univ Rennes, IGDR (Institute of Genetics and Development of Rennes)–UMR 6290, F-35000 Rennes, France
| | - Marc Tramier
- CNRS, Univ Rennes, IGDR (Institute of Genetics and Development of Rennes)–UMR 6290, F-35000 Rennes, France
| | - Jacques Pécréaux
- CNRS, Univ Rennes, IGDR (Institute of Genetics and Development of Rennes)–UMR 6290, F-35000 Rennes, France
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47
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Edwards F, Maton G, Gareil N, Canman JC, Dumont J. BUB-1 promotes amphitelic chromosome biorientation via multiple activities at the kinetochore. eLife 2018; 7:40690. [PMID: 30547880 PMCID: PMC6303103 DOI: 10.7554/elife.40690] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Accepted: 12/13/2018] [Indexed: 12/03/2022] Open
Abstract
Accurate chromosome segregation relies on bioriented amphitelic attachments of chromosomes to microtubules of the mitotic spindle, in which sister chromatids are connected to opposite spindle poles. BUB-1 is a protein of the Spindle Assembly Checkpoint (SAC) that coordinates chromosome attachment with anaphase onset. BUB-1 is also required for accurate sister chromatid segregation independently of its SAC function, but the underlying mechanism remains unclear. Here we show that, in Caenorhabditis elegans embryos, BUB-1 accelerates the establishment of non-merotelic end-on kinetochore-microtubule attachments by recruiting the RZZ complex and its downstream partner dynein-dynactin at the kinetochore. In parallel, BUB-1 limits attachment maturation by the SKA complex. This activity opposes kinetochore-microtubule attachment stabilisation promoted by CLS-2CLASP-dependent kinetochore-microtubule assembly. BUB-1 is therefore a SAC component that coordinates the function of multiple downstream kinetochore-associated proteins to ensure accurate chromosome segregation.
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Affiliation(s)
- Frances Edwards
- Institut Jacques Monod, CNRS, UMR 7592, University Paris Diderot, Sorbonne Paris Cité, Paris, France
| | - Gilliane Maton
- Institut Jacques Monod, CNRS, UMR 7592, University Paris Diderot, Sorbonne Paris Cité, Paris, France
| | - Nelly Gareil
- Institut Jacques Monod, CNRS, UMR 7592, University Paris Diderot, Sorbonne Paris Cité, Paris, France
| | - Julie C Canman
- Department of Pathology and Cell Biology, Columbia University, New York, United States
| | - Julien Dumont
- Institut Jacques Monod, CNRS, UMR 7592, University Paris Diderot, Sorbonne Paris Cité, Paris, France
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48
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Zwetsloot AJ, Tut G, Straube A. Measuring microtubule dynamics. Essays Biochem 2018; 62:725-735. [PMID: 30287587 PMCID: PMC6281472 DOI: 10.1042/ebc20180035] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Revised: 08/31/2018] [Accepted: 09/04/2018] [Indexed: 12/31/2022]
Abstract
Microtubules are key players in cellular self-organization, acting as structural scaffolds, cellular highways, force generators and signalling platforms. Microtubules are polar filaments that undergo dynamic instability, i.e. transition between phases of growth and shrinkage. This allows microtubules to explore the inner space of the cell, generate pushing and pulling forces and remodel themselves into arrays with different geometry and function such as the mitotic spindle. To do this, eukaryotic cells employ an arsenal of regulatory proteins to control microtubule dynamics spatially and temporally. Plants and microorganisms have developed secondary metabolites that perturb microtubule dynamics, many of which are in active use as cancer chemotherapeutics and anti-inflammatory drugs. Here, we summarize the methods used to visualize microtubules and to measure the parameters of dynamic instability to study both microtubule regulatory proteins and the action of small molecules interfering with microtubule assembly and/or disassembly.
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Affiliation(s)
- Alexander James Zwetsloot
- Centre for Mechanochemical Cell Biology, University of Warwick, Coventry, CV4 7AL, U.K
- MRC Doctoral Training Partnership, University of Warwick, Coventry, CV4 7AL, U.K
| | - Gokhan Tut
- Centre for Mechanochemical Cell Biology, University of Warwick, Coventry, CV4 7AL, U.K
- MRC Doctoral Training Partnership, University of Warwick, Coventry, CV4 7AL, U.K
| | - Anne Straube
- Centre for Mechanochemical Cell Biology, University of Warwick, Coventry, CV4 7AL, U.K.
- Division of Biomedical Sciences, Warwick Medical School, Coventry, CV4 7AL, U.K
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Bouvrais H, Chesneau L, Pastezeur S, Fairbrass D, Delattre M, Pécréaux J. Microtubule Feedback and LET-99-Dependent Control of Pulling Forces Ensure Robust Spindle Position. Biophys J 2018; 115:2189-2205. [PMID: 30447992 PMCID: PMC6289040 DOI: 10.1016/j.bpj.2018.10.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2018] [Revised: 10/03/2018] [Accepted: 10/09/2018] [Indexed: 11/26/2022] Open
Abstract
During asymmetric division of the Caenorhabditis elegans zygote, to properly distribute cell fate determinants, the mitotic spindle is asymmetrically localized by a combination of centering and cortical-pulling microtubule-mediated forces, the dynamics of the latter being regulated by mitotic progression. Here, we show a, to our knowledge, novel and additional regulation of these forces by spindle position itself. For that, we observed the onset of transverse spindle oscillations, which reflects the burst of anaphase pulling forces. After delaying anaphase onset, we found that the position at which the spindle starts to oscillate was unchanged compared to control embryos and uncorrelated to anaphase onset. In mapping the cortical microtubule dynamics, we measured a steep increase in microtubule contact density after the posterior centrosome reached the critical position of 70% of embryo length, strongly suggesting the presence of a positional switch for spindle oscillations. Expanding a previous model based on a force-generator temporal control, we implemented this positional switch and observed that the large increase in microtubule density accounted for the pulling force burst. Thus, we propose that the spindle position influences the cortical availability of microtubules on which the active force generators, controlled by cell cycle progression, can pull. Importantly, we found that this positional control relies on the polarity-dependent LET-99 cortical band, the boundary of which could be probed by microtubules. This dual positional and temporal control well accounted for our observation that the oscillation onset position resists changes in cellular geometry and moderate variations in the active force generator number. Finally, our model suggests that spindle position at mitosis end is more sensitive to the polarity factor LET-99, which restricts the region of active force generators to a posterior-most region, than to microtubule number or force generator number/activity. Overall, we show that robustness in spindle positioning originates in cell mechanics rather than biochemical networks.
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Affiliation(s)
| | | | | | | | - Marie Delattre
- Univ Lyon, ENS de Lyon, Univ Claude Bernard, Laboratory of Biology and Modelling of the Cell, Lyon University, Lyon, France
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Ding C, Hammarlund M. Aberrant information transfer interferes with functional axon regeneration. eLife 2018; 7:e38829. [PMID: 30371349 PMCID: PMC6231761 DOI: 10.7554/elife.38829] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Accepted: 10/26/2018] [Indexed: 12/16/2022] Open
Abstract
Functional axon regeneration requires regenerating neurons to restore appropriate synaptic connectivity and circuit function. To model this process, we developed an assay in Caenorhabditis elegans that links axon and synapse regeneration of a single neuron to recovery of behavior. After axon injury and regeneration of the DA9 neuron, synapses reform at their pre-injury location. However, these regenerated synapses often lack key molecular components. Further, synaptic vesicles accumulate in the dendrite in response to axon injury. Dendritic vesicle release results in information misrouting that suppresses behavioral recovery. Dendritic synapse formation depends on dynein and jnk-1. But even when information transfer is corrected, axonal synapses fail to adequately transmit information. Our study reveals unexpected plasticity during functional regeneration. Regeneration of the axon is not sufficient for the reformation of correct neuronal circuits after injury. Rather, synapse reformation and function are also key variables, and manipulation of circuit reformation improves behavioral recovery.
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Affiliation(s)
- Chen Ding
- Department of NeuroscienceYale UniversityNew HavenUnited States
| | - Marc Hammarlund
- Department of NeuroscienceYale UniversityNew HavenUnited States
- Department of GeneticsYale UniversityNew HavenUnited States
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