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Li L, Zhang N, Beati SAH, De Las Heras Chanes J, di Pietro F, Bellaiche Y, Müller HAJ, Großhans J. Kinesin-1 patterns Par-1 and Rho signaling at the cortex of syncytial embryos of Drosophila. J Cell Biol 2024; 223:e202206013. [PMID: 37955925 PMCID: PMC10641515 DOI: 10.1083/jcb.202206013] [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: 06/03/2022] [Revised: 03/23/2023] [Accepted: 10/18/2023] [Indexed: 11/14/2023] Open
Abstract
The cell cortex of syncytial Drosophila embryos is patterned into cap and intercap regions by centrosomes, specific sets of proteins that are restricted to their respective regions by unknown mechanisms. Here, we found that Kinesin-1 is required for the restriction of plus- and minus-ends of centrosomal and non-centrosomal microtubules to the cap region, marked by EB1 and Patronin/Shot, respectively. Kinesin-1 also directly or indirectly restricts proteins and Rho signaling to the intercap, including the RhoGEF Pebble, Dia, Myosin II, Capping protein-α, and the polarity protein Par-1. Furthermore, we found that Par-1 is required for cap restriction of Patronin/Shot, and vice versa Patronin, for Par-1 enrichment at the intercap. In summary, our data support a model that Kinesin-1 would mediate the restriction of centrosomal and non-centrosomal microtubules to a region close to the centrosomes and exclude Rho signaling and Par-1. In addition, mutual antagonistic interactions would refine and maintain the boundary between cap and intercap and thus generate a distinct cortical pattern.
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Affiliation(s)
- Long Li
- Department of Biology, Philipps University, Marburg, Germany
| | - Na Zhang
- Department of Biology, Philipps University, Marburg, Germany
| | - Seyed Amir Hamze Beati
- Division of Developmental Genetics, Institute for Biology, University of Kassel, Kassel, Germany
| | - Jose De Las Heras Chanes
- Institut Curie, Université PSL, Sorbonne Université, CNRS UMR 3215, Inserm U934, Genetics and Developmental Biology , Paris, France
| | - Florencia di Pietro
- Institut Curie, Université PSL, Sorbonne Université, CNRS UMR 3215, Inserm U934, Genetics and Developmental Biology , Paris, France
| | - Yohanns Bellaiche
- Institut Curie, Université PSL, Sorbonne Université, CNRS UMR 3215, Inserm U934, Genetics and Developmental Biology , Paris, France
| | - Hans-Arno J Müller
- Division of Developmental Genetics, Institute for Biology, University of Kassel, Kassel, Germany
| | - Jörg Großhans
- Department of Biology, Philipps University, Marburg, Germany
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2
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Bakshi A, Iturra FE, Alamban A, Rosas-Salvans M, Dumont S, Aydogan MG. Cytoplasmic division cycles without the nucleus and mitotic CDK/cyclin complexes. Cell 2023; 186:4694-4709.e16. [PMID: 37832525 PMCID: PMC10659773 DOI: 10.1016/j.cell.2023.09.010] [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: 06/05/2022] [Revised: 05/11/2023] [Accepted: 09/12/2023] [Indexed: 10/15/2023]
Abstract
Cytoplasmic divisions are thought to rely on nuclear divisions and mitotic signals. We demonstrate in Drosophila embryos that cytoplasm can divide repeatedly without nuclei and mitotic CDK/cyclin complexes. Cdk1 normally slows an otherwise faster cytoplasmic division cycle, coupling it with nuclear divisions, and when uncoupled, cytoplasm starts dividing before mitosis. In developing embryos where CDK/cyclin activity can license mitotic microtubule (MT) organizers like the spindle, cytoplasmic divisions can occur without the centrosome, a principal organizer of interphase MTs. However, centrosomes become essential in the absence of CDK/cyclin activity, implying that the cytoplasm can employ either the centrosome-based interphase or CDK/cyclin-dependent mitotic MTs to facilitate its divisions. Finally, we present evidence that autonomous cytoplasmic divisions occur during unperturbed fly embryogenesis and that they may help extrude mitotically stalled nuclei during blastoderm formation. We postulate that cytoplasmic divisions occur in cycles governed by a yet-to-be-uncovered clock mechanism autonomous from CDK/cyclin complexes.
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Affiliation(s)
- Anand Bakshi
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Fabio Echegaray Iturra
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Andrew Alamban
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA 94158, USA; Biophysics Graduate Program, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Miquel Rosas-Salvans
- Department of Bioengineering and Therapeutic Science, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Sophie Dumont
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA 94158, USA; Chan Zuckerberg Biohub, San Francisco, CA 94158, USA
| | - Mustafa G Aydogan
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA 94158, USA; Biophysics Graduate Program, University of California, San Francisco, San Francisco, CA 94158, USA.
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3
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Yeh AR, Hoeprich GJ, Goode BL, Martin AC. Bitesize bundles F-actin and influences actin remodeling in syncytial Drosophila embryo development. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.17.537198. [PMID: 37131807 PMCID: PMC10153138 DOI: 10.1101/2023.04.17.537198] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Actin networks undergo rearrangements that influence cell and tissue shape. Actin network assembly and organization is regulated in space and time by a host of actin binding proteins. The Drosophila Synaptotagmin-like protein, Bitesize (Btsz), is known to organize actin at epithelial cell apical junctions in a manner that depends on its interaction with the actin-binding protein, Moesin. Here, we showed that Btsz functions in actin reorganization at earlier, syncytial stages of Drosophila embryo development. Btsz was required for the formation of stable metaphase pseudocleavage furrows that prevented spindle collisions and nuclear fallout prior to cellularization. While previous studies focused on Btsz isoforms containing the Moesin Binding Domain (MBD), we found that isoforms lacking the MBD also function in actin remodeling. Consistent with this, we found that the C-terminal half of BtszB cooperatively binds to and bundles F-actin, suggesting a direct mechanism for Synaptotagmin-like proteins regulating actin organization during animal development.
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4
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Sokac AM, Biel N, De Renzis S. Membrane-actin interactions in morphogenesis: Lessons learned from Drosophila cellularization. Semin Cell Dev Biol 2023; 133:107-122. [PMID: 35396167 PMCID: PMC9532467 DOI: 10.1016/j.semcdb.2022.03.028] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2022] [Revised: 03/18/2022] [Accepted: 03/21/2022] [Indexed: 01/12/2023]
Abstract
During morphogenesis, changes in the shapes of individual cells are harnessed to mold an entire tissue. These changes in cell shapes require the coupled remodeling of the plasma membrane and underlying actin cytoskeleton. In this review, we highlight cellularization of the Drosophila embryo as a model system to uncover principles of how membrane and actin dynamics are co-regulated in space and time to drive morphogenesis.
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Affiliation(s)
- Anna Marie Sokac
- Department of Cell and Developmental Biology, University of Illinois at Urbana Champaign, Urbana, IL 61801, USA; Graduate Program in Integrative and Molecular Biomedical Sciences, Baylor College of Medicine, Houston, TX 77030, USA.
| | - Natalie Biel
- Department of Cell and Developmental Biology, University of Illinois at Urbana Champaign, Urbana, IL 61801, USA; Graduate Program in Integrative and Molecular Biomedical Sciences, Baylor College of Medicine, Houston, TX 77030, USA
| | - Stefano De Renzis
- European Molecular Biology Laboratory Heidelberg, 69117 Heidelberg, Germany
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5
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Fine-tuning cell organelle dynamics during mitosis by small GTPases. Front Med 2022; 16:339-357. [PMID: 35759087 DOI: 10.1007/s11684-022-0926-1] [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: 10/26/2021] [Accepted: 02/24/2022] [Indexed: 11/04/2022]
Abstract
During mitosis, the allocation of genetic material concurs with organelle transformation and distribution. The coordination of genetic material inheritance with organelle dynamics directs accurate mitotic progression, cell fate determination, and organismal homeostasis. Small GTPases belonging to the Ras superfamily regulate various cell organelles during division. Being the key regulators of membrane dynamics, the dysregulation of small GTPases is widely associated with cell organelle disruption in neoplastic and non-neoplastic diseases, such as cancer and Alzheimer's disease. Recent discoveries shed light on the molecular properties of small GTPases as sophisticated modulators of a remarkably complex and perfect adaptors for rapid structure reformation. This review collects current knowledge on small GTPases in the regulation of cell organelles during mitosis and highlights the mediator role of small GTPase in transducing cell cycle signaling to organelle dynamics during mitosis.
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6
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Zhang J, Jiang Z, Shi A. Rab GTPases: The principal players in crafting the regulatory landscape of endosomal trafficking. Comput Struct Biotechnol J 2022; 20:4464-4472. [PMID: 36051867 PMCID: PMC9418685 DOI: 10.1016/j.csbj.2022.08.016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2022] [Revised: 08/05/2022] [Accepted: 08/07/2022] [Indexed: 11/16/2022] Open
Abstract
After endocytosis, diverse cargos are sorted into endosomes and directed to various destinations, including extracellular macromolecules, membrane lipids, and membrane proteins. Some cargos are returned to the plasma membrane via endocytic recycling. In contrast, others are delivered to the Golgi apparatus through the retrograde pathway, while the rest are transported to late endosomes and eventually to lysosomes for degradation. Rab GTPases are major regulators that ensure cargos are delivered to their proper destinations. Rabs are localized to distinct endosomes and play predominant roles in membrane budding, vesicle formation and motility, vesicle tethering, and vesicle fusion by recruiting effectors. The cascades between Rabs via shared effectors or the recruitment of Rab activators provide an additional layer of spatiotemporal regulation of endocytic trafficking. Notably, several recent studies have indicated that disorders of Rab-mediated endocytic transports are closely associated with diseases such as immunodeficiency, cancer, and neurological disorders.
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7
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Lattao R, Rangone H, Llamazares S, Glover DM. Mauve/LYST limits fusion of lysosome-related organelles and promotes centrosomal recruitment of microtubule nucleating proteins. Dev Cell 2021; 56:1000-1013.e6. [PMID: 33725482 PMCID: PMC8024676 DOI: 10.1016/j.devcel.2021.02.019] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2020] [Revised: 11/17/2020] [Accepted: 02/17/2021] [Indexed: 11/28/2022]
Abstract
Lysosome-related organelles (LROs) are endosomal compartments carrying tissue-specific proteins, which become enlarged in Chediak-Higashi syndrome (CHS) due to mutations in LYST. Here, we show that Drosophila Mauve, a counterpart of LYST, suppresses vesicle fusion events with lipid droplets (LDs) during the formation of yolk granules (YGs), the LROs of the syncytial embryo, and opposes Rab5, which promotes fusion. Mauve localizes on YGs and at spindle poles, and it co-immunoprecipitates with the LDs' component and microtubule-associated protein Minispindles/Ch-TOG. Minispindles levels are increased at the enlarged YGs and diminished around centrosomes in mauve-derived mutant embryos. This leads to decreased microtubule nucleation from centrosomes, a defect that can be rescued by dominant-negative Rab5. Together, this reveals an unanticipated link between endosomal vesicles and centrosomes. These findings establish Mauve/LYST's role in regulating LRO formation and centrosome behavior, a role that could account for the enlarged LROs and centrosome positioning defects at the immune synapse of CHS patients.
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Affiliation(s)
- Ramona Lattao
- University of Cambridge, Department of Genetics, Downing Street, Cambridge CB23EH, UK.
| | - Hélène Rangone
- University of Cambridge, Department of Genetics, Downing Street, Cambridge CB23EH, UK
| | - Salud Llamazares
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Parc Cientific de Barcelona, C/ Baldiri Reixac 10, 08028 Barcelona, Spain
| | - David M Glover
- University of Cambridge, Department of Genetics, Downing Street, Cambridge CB23EH, UK; Division of Biology and Biological Engineering, California Institute of Technology, 1200 E, California Blvd, Pasadena, CA 91125, USA.
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8
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Willoughby PM, Allen M, Yu J, Korytnikov R, Chen T, Liu Y, So I, Macpherson N, Mitchell JA, Fernandez-Gonzalez R, Bruce AE. The recycling endosome protein Rab25 coordinates collective cell movements in the zebrafish surface epithelium. eLife 2021; 10:66060. [PMID: 33755014 PMCID: PMC8034978 DOI: 10.7554/elife.66060] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Accepted: 03/22/2021] [Indexed: 12/16/2022] Open
Abstract
In emerging epithelial tissues, cells undergo dramatic rearrangements to promote tissue shape changes. Dividing cells remain interconnected via transient cytokinetic bridges. Bridges are cleaved during abscission and currently, the consequences of disrupting abscission in developing epithelia are not well understood. We show that the Rab GTPase Rab25 localizes near cytokinetic midbodies and likely coordinates abscission through endomembrane trafficking in the epithelium of the zebrafish gastrula during epiboly. In maternal-zygotic Rab25a and Rab25b mutant embryos, morphogenic activity tears open persistent apical cytokinetic bridges that failed to undergo timely abscission. Cytokinesis defects result in anisotropic cell morphologies that are associated with a reduction of contractile actomyosin networks. This slows cell rearrangements and alters the viscoelastic responses of the tissue, all of which likely contribute to delayed epiboly. We present a model in which Rab25 trafficking coordinates cytokinetic bridge abscission and cortical actin density, impacting local cell shape changes and tissue-scale forces.
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Affiliation(s)
| | - Molly Allen
- Department of Cell and Systems Biology, University of Toronto, Toronto, Canada
| | - Jessica Yu
- Ted Rogers Centre for Heart Research, Translational Biology and Engineering Program, University of Toronto, Toronto, Canada.,Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Canada
| | - Roman Korytnikov
- Department of Cell and Systems Biology, University of Toronto, Toronto, Canada
| | - Tianhui Chen
- Department of Cell and Systems Biology, University of Toronto, Toronto, Canada
| | - Yupeng Liu
- Department of Cell and Systems Biology, University of Toronto, Toronto, Canada
| | - Isis So
- Department of Cell and Systems Biology, University of Toronto, Toronto, Canada
| | - Neil Macpherson
- Department of Cell and Systems Biology, University of Toronto, Toronto, Canada
| | - Jennifer A Mitchell
- Department of Cell and Systems Biology, University of Toronto, Toronto, Canada
| | - Rodrigo Fernandez-Gonzalez
- Department of Cell and Systems Biology, University of Toronto, Toronto, Canada.,Ted Rogers Centre for Heart Research, Translational Biology and Engineering Program, University of Toronto, Toronto, Canada.,Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Canada
| | - Ashley Ee Bruce
- Department of Cell and Systems Biology, University of Toronto, Toronto, Canada
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9
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Rozés-Salvador V, González-Billault C, Conde C. The Recycling Endosome in Nerve Cell Development: One Rab to Rule Them All? Front Cell Dev Biol 2020; 8:603794. [PMID: 33425908 PMCID: PMC7793921 DOI: 10.3389/fcell.2020.603794] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2020] [Accepted: 11/11/2020] [Indexed: 12/13/2022] Open
Abstract
Endocytic recycling is an intracellular process that returns internalized molecules back to the plasma membrane and plays crucial roles not only in the reuse of receptor molecules but also in the remodeling of the different components of this membrane. This process is required for a diversity of cellular events, including neuronal morphology acquisition and functional regulation, among others. The recycling endosome (RE) is a key vesicular component involved in endocytic recycling. Recycling back to the cell surface may occur with the participation of several different Rab proteins, which are master regulators of membrane/protein trafficking in nerve cells. The RE consists of a network of interconnected and functionally distinct tubular subdomains that originate from sorting endosomes and transport their cargoes along microtubule tracks, by fast or slow recycling pathways. Different populations of REs, particularly those formed by Rab11, Rab35, and Arf6, are associated with a myriad of signaling proteins. In this review, we discuss the cumulative evidence suggesting the existence of heterogeneous domains of REs, controlling different aspects of neurogenesis, with a particular focus on the commonalities and singularities of these REs and their contribution to nerve development and differentiation in several animal models.
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Affiliation(s)
- Victoria Rozés-Salvador
- Instituto de Investigación Médica Mercedes y Martín Ferreyra INIMEC-CONICET-UNC, Córdoba, Argentina.,Instituto de Ciencias Básicas, Universidad Nacional de Villa María, Córdoba, Argentina
| | - Christian González-Billault
- Department of Biology, Faculty of Sciences, Universidad de Chile, Santiago, Chile.,Department of Neurosciences, Faculty of Medicine, Universidad de Chile, Santiago, Chile.,Geroscience Center for Brain Health and Metabolism, Santiago, Chile.,The Buck Institute for Research on Aging, Novato, CA, United States
| | - Cecilia Conde
- Instituto de Investigación Médica Mercedes y Martín Ferreyra INIMEC-CONICET-UNC, Córdoba, Argentina
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10
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Nandy N, Roy JK. Rab11 is essential for lgl mediated JNK-Dpp signaling in dorsal closure and epithelial morphogenesis in Drosophila. Dev Biol 2020; 464:188-201. [PMID: 32562757 DOI: 10.1016/j.ydbio.2020.06.005] [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: 07/30/2019] [Revised: 06/11/2020] [Accepted: 06/11/2020] [Indexed: 11/30/2022]
Abstract
Dorsal closure during Drosophila embryogenesis provides a robust genetic platform to study the basic cellular mechanisms that govern epithelial wound healing and morphogenesis. As dorsal closure proceeds, the lateral epithelial tissue (LE) adjacent to the dorsal opening advance contra-laterally, with a simultaneous retraction of the amnioserosa. The process involves a fair degree of coordinated cell shape changes in the dorsal most epithelial (DME) cells as well as a few penultimate rows of lateral epithelial (LE) cells (collectively referred here as Dorsolateral Epithelial (DLE) cells), lining the periphery of the amnioserosa, which in due course of time extend contra-laterally and ultimately fuse over the dorsal hole, giving rise to a dorsal epithelial continuum. The JNK-Dpp signaling in the dorsolateral epidermis, plays an instrumental role in guiding their fate during this process. A large array of genes have been reported to be involved in the regulation of this core signaling pathway, yet the mechanisms by which they do so is hitherto unclear, which forms the objective of our present study. Here we show a probable mechanism via which lgl, a conserved tumour suppressor gene, regulates the JNK-Dpp pathway during dorsal closure and epithelial morphogenesis. A conditional/targeted knock-down of lgl in the dorsolateral epithelium of embryos results in failure of dorsal closure. Interestingly, we also observed a similar phenotype in a Rab11 knockdown condition. Our experiment suggests Rab11 to be interacting with lgl as they seem to synergize in order to regulate the core JNK-Dpp signaling pathway during dorsal closure and also during adult thorax closure process.
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Affiliation(s)
- Nabarun Nandy
- Cytogenetics Laboratory, Department of Zoology, Banaras Hindu University, Varanasi, 221005, India
| | - Jagat Kumar Roy
- Cytogenetics Laboratory, Department of Zoology, Banaras Hindu University, Varanasi, 221005, India.
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11
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Dey B, Rikhy R. DE-cadherin and Myosin II balance regulates furrow length for onset of polygon shape in syncytial Drosophila embryos. J Cell Sci 2020; 133:jcs240168. [PMID: 32265269 DOI: 10.1242/jcs.240168] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2019] [Accepted: 03/26/2020] [Indexed: 08/31/2023] Open
Abstract
Cell shape morphogenesis, from spherical to polygonal, occurs in epithelial cell formation in metazoan embryogenesis. In syncytial Drosophila embryos, the plasma membrane incompletely surrounds each nucleus and is organized as a polygonal epithelial-like array. Each cortical syncytial division cycle shows a circular to polygonal plasma membrane transition along with furrow extension between adjacent nuclei from interphase to metaphase. In this study, we assess the relative contribution of DE-cadherin (also known as Shotgun) and Myosin II (comprising Zipper and Spaghetti squash in flies) at the furrow to polygonal shape transition. We show that polygonality initiates during each cortical syncytial division cycle when the furrow extends from 4.75 to 5.75 μm. Polygon plasma membrane organization correlates with increased junctional tension, increased DE-cadherin and decreased Myosin II mobility. DE-cadherin regulates furrow length and polygonality. Decreased Myosin II activity allows for polygonality to occur at a lower length than controls. Increased Myosin II activity leads to loss of lateral furrow formation and complete disruption of the polygonal shape transition. Our studies show that DE-cadherin-Myosin II balance regulates an optimal lateral membrane length during each syncytial cycle for polygonal shape transition.This article has an associated First Person interview with the first author of the paper.
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Affiliation(s)
- Bipasha Dey
- Biology, Indian Institute of Science Education and Research, Homi Bhabha Road, Pashan, Pune, 411008, India
| | - Richa Rikhy
- Biology, Indian Institute of Science Education and Research, Homi Bhabha Road, Pashan, Pune, 411008, India
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12
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Cofilin-Mediated Actin Stress Response Is Maladaptive in Heat-Stressed Embryos. Cell Rep 2020; 26:3493-3501.e4. [PMID: 30917306 PMCID: PMC6447309 DOI: 10.1016/j.celrep.2019.02.092] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2018] [Revised: 01/22/2019] [Accepted: 02/21/2019] [Indexed: 01/04/2023] Open
Abstract
Environmental stress threatens the fidelity of embryonic morphogenesis. Heat, for example, is a teratogen. Yet how heat affects morphogenesis is poorly understood. Here, we identify a heat-inducible actin stress response (ASR) in Drosophila embryos that is mediated by the activation of the actin regulator Cofilin. Similar to ASR in adult mammalian cells, heat stress in fly embryos triggers the assembly of intra-nuclear actin rods. Rods measure up to a few microns in length, and their assembly depends on elevated free nuclear actin concentration and Cofilin. Outside the nucleus, heat stress causes Cofilin-dependent destabilization of filamentous actin (F-actin) in actomyosin networks required for morphogenesis. F-actin destabilization increases the chance of morphogenesis mistakes. Blocking the ASR by reducing Cofilin dosage improves the viability of heat-stressed embryos. However, improved viability correlates with restoring F-actin stability, not rescuing morphogenesis. Thus, ASR endangers embryos, perhaps by shifting actin from cytoplasmic filaments to an elevated nuclear pool. Figard et al. show that heat stress induces an actin stress response (ASR) in early Drosophila embryos. This ASR is mediated by a heat-induced increase in Cofilin activity. Increased Cofilin activity destabilizes F-actin structures required for morphogenesis. In addition, the Cofilin-mediated ASR reduces embryo viability.
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13
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Biel N, Figard L, Sokac AM. Imaging Intranuclear Actin Rods in Live Heat Stressed Drosophila Embryos. J Vis Exp 2020. [PMID: 32478727 DOI: 10.3791/61297] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
The purpose of this protocol is to visualize intranuclear actin rods that assemble in live Drosophila melanogaster embryos following heat stress. Actin rods are a hallmark of a conserved, inducible Actin Stress Response (ASR) that accompanies human pathologies, including neurodegenerative disease. Previously, we showed that the ASR contributes to morphogenesis failures and reduced viability of developing embryos. This protocol allows the continued study of mechanisms underlying actin rod assembly and the ASR in a model system that is highly amenable to imaging, genetics and biochemistry. Embryos are collected and mounted on a coverslip to prepare them for injection. Rhodamine-conjugated globular actin (G-actinRed) is diluted and loaded into a microneedle. A single injection is made into the center of each embryo. After injection, embryos are incubated at elevated temperature and intranuclear actin rods are then visualized by confocal microscopy. Fluorescence recovery after photobleaching (FRAP) experiments may be performed on the actin rods; and other actin-rich structures in the cytoplasm can also be imaged. We find that G-actinRed polymerizes like endogenous G-actin and does not, on its own, interfere with normal embryo development. One limitation of this protocol is that care must be taken during injection to avoid serious injury to the embryo. However, with practice, injecting G-actinRed into Drosophila embryos is a fast and reliable way to visualize actin rods and can easily be used with flies of any genotype or with the introduction of other cellular stresses, including hypoxia and oxidative stress.
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Affiliation(s)
- Natalie Biel
- Integrative Molecular and Biomedical Sciences, Baylor College of Medicine; Department of Cell and Molecular Biology, School of Molecular and Cellular Biology, University of Illinois at Urbana-Champaign
| | - Lauren Figard
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine
| | - Anna Marie Sokac
- Integrative Molecular and Biomedical Sciences, Baylor College of Medicine; Department of Cell and Molecular Biology, School of Molecular and Cellular Biology, University of Illinois at Urbana-Champaign; Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine;
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14
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Zou C, Fan J, He M, Xu Y, Wang K, Cai Y, Li M. Epigenetic silencing of Rab39a promotes epithelial to mesenchymal transition of cervical cancer through AKT signaling. Exp Cell Res 2019; 378:139-148. [PMID: 30826396 DOI: 10.1016/j.yexcr.2019.02.025] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2018] [Revised: 02/13/2019] [Accepted: 02/27/2019] [Indexed: 11/24/2022]
Abstract
The objective of this study was to investigate the functional role of Rab39a in human cervical cancer (CC) and the underlying molecular mechanisms. We first measured Rab39a mRNA expression in CC tissues and paired non-tumor tissues by quantitative real-time PCR (QRT-PCR). Overall survival of CC patients with different mRNA levels of Rab39a in The Cancer Genome Atlas (TCGA) database was assessed by Kaplan-Meier survival curves analysis. Next methylation-specific PCR (MSP) was performed to determine the expression mechanism of Rab39a. Then cell proliferation, migration and invasion of Rab39a-transfected or mock-transfected cervical cancer cells were determined by CCK-8, flow cytometry, wound healing, transwell migration and invasion assays, respectively. Finally, the molecular mechanism by which Rab39a modulated CC cell epithelial-mesenchymal transition (EMT) was explored. It was found that Rab39a mRNA was significantly down-regulated in the high-risk patients compared to the low-risk patients (p = 0.0054). Six of seven cancer tissues with lymph node metastasis express low Rab39a mRNA compared to the surrounding non-tumor tissues. Cervical cancer patients with low level of Rab39a were showed a poorly clinical outcome (p = 0.004). Loss of Rab39a expression in cervical cancer tissues was associated with the aberrant DNA methylation in the promoter of Rab39a gene. Disrupted Rab39a expression in cervical cancer cells could be restored after treatment with the demethylated agent 5-Aza-2'-deoxycytidine. Furthermore, it was found that Rab39a hardly influenced cell growth but significantly suppressed cell migration, invasion and EMT process. Rab39a exerted its potential suppressor functions through inhibiting AKT phosphorylation. The inhibition effects of Rab39a could be blocked by AKT pathway inhibitor. Collectively, our data shows that Rab39a is a potential epigenetic silenced tumor suppressor inhibiting cancer invasion and migration through modulating the AKT signaling.
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Affiliation(s)
- Chun Zou
- Department of Immunology, College of Basic Medical Science, Central South University, Changsha, Hunan 410008, PR China
| | - Jielin Fan
- Department of Gynecologic Tumor, Affiliated Cancer Hospital of Central South University, Changsha, Hunan 410013, PR China
| | - Mei He
- Department of Immunology, College of Basic Medical Science, Central South University, Changsha, Hunan 410008, PR China
| | - Yan Xu
- Department of Immunology, College of Basic Medical Science, Central South University, Changsha, Hunan 410008, PR China
| | - Kangtao Wang
- Department of Gastrointestinal Surgery, Xiangya Hospital, Central South University, Changsha, Hunan 410008, PR China
| | - Yubo Cai
- Department of Immunology, College of Basic Medical Science, Central South University, Changsha, Hunan 410008, PR China
| | - Ming Li
- Department of Immunology, College of Basic Medical Science, Central South University, Changsha, Hunan 410008, PR China.
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15
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Blake-Hedges C, Megraw TL. Coordination of Embryogenesis by the Centrosome in Drosophila melanogaster. Results Probl Cell Differ 2019; 67:277-321. [PMID: 31435800 DOI: 10.1007/978-3-030-23173-6_12] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The first 3 h of Drosophila melanogaster embryo development are exemplified by rapid nuclear divisions within a large syncytium, transforming the zygote to the cellular blastoderm after 13 successive cleavage divisions. As the syncytial embryo develops, it relies on centrosomes and cytoskeletal dynamics to transport nuclei, maintain uniform nuclear distribution throughout cleavage cycles, ensure generation of germ cells, and coordinate cellularization. For the sake of this review, we classify six early embryo stages that rely on processes coordinated by the centrosome and its regulation of the cytoskeleton. The first stage features migration of one of the female pronuclei toward the male pronucleus following maturation of the first embryonic centrosomes. Two subsequent stages distribute the nuclei first axially and then radially in the embryo. The remaining three stages involve centrosome-actin dynamics that control cortical plasma membrane morphogenesis. In this review, we highlight the dynamics of the centrosome and its role in controlling the six stages that culminate in the cellularization of the blastoderm embryo.
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Affiliation(s)
- Caitlyn Blake-Hedges
- Department of Biomedical Sciences, College of Medicine, Florida State University, Tallahassee, FL, USA.
| | - Timothy L Megraw
- Department of Biomedical Sciences, College of Medicine, Florida State University, Tallahassee, FL, USA
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16
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Molinar-Inglis O, Oliver SL, Rudich P, Kunttas E, McCartney BM. APC2 associates with the actin cortex through a multipart mechanism to regulate cortical actin organization and dynamics in the Drosophila ovary. Cytoskeleton (Hoboken) 2018; 75:323-335. [PMID: 30019417 DOI: 10.1002/cm.21471] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2018] [Revised: 05/24/2018] [Accepted: 06/19/2018] [Indexed: 01/20/2023]
Abstract
The actin cortex that lines the plasma membrane of most eukaryotic cells resists external mechanical forces and plays critical roles in a variety of cellular processes including morphogenesis, cytokinesis, and cell migration. Despite its ubiquity and significance, we understand relatively little about the composition, dynamics, and structure of the actin cortex. Adenomatous polyposis coli (APC) proteins regulate the actin and microtubule cytoskeletons through a variety of mechanisms, and in some contexts, APC proteins are cortically enriched. Here we show that APC2 regulates cortical actin dynamics in the follicular epithelium and the nurse cells of the Drosophila ovary and in addition affects the distribution of cortical actin at the apical side of the follicular epithelium. To understand how APC2 influences these properties of the actin cortex, we investigated the mechanisms controlling the cortical localization of APC2 in S2 cultured cells. We previously showed that the N-terminal half of APC2 containing the Armadillo repeats and the C-terminal 30 amino acids (C30) are together necessary and sufficient for APC2's cortical localization. Our work presented here supports a model that cortical localization of APC2 is governed in part by self-association through the N-terminal APC Self-Association Domain (ASAD) and a highly conserved coiled-coil within the C30 domain.
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Affiliation(s)
- Olivia Molinar-Inglis
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania
| | - Stacie L Oliver
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania
| | - Paige Rudich
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania
| | - Ezgi Kunttas
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania
| | - Brooke M McCartney
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania
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17
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Tillery MML, Blake-Hedges C, Zheng Y, Buchwalter RA, Megraw TL. Centrosomal and Non-Centrosomal Microtubule-Organizing Centers (MTOCs) in Drosophila melanogaster. Cells 2018; 7:E121. [PMID: 30154378 PMCID: PMC6162459 DOI: 10.3390/cells7090121] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2018] [Revised: 08/19/2018] [Accepted: 08/20/2018] [Indexed: 12/14/2022] Open
Abstract
The centrosome is the best-understood microtubule-organizing center (MTOC) and is essential in particular cell types and at specific stages during Drosophila development. The centrosome is not required zygotically for mitosis or to achieve full animal development. Nevertheless, centrosomes are essential maternally during cleavage cycles in the early embryo, for male meiotic divisions, for efficient division of epithelial cells in the imaginal wing disc, and for cilium/flagellum assembly in sensory neurons and spermatozoa. Importantly, asymmetric and polarized division of stem cells is regulated by centrosomes and by the asymmetric regulation of their microtubule (MT) assembly activity. More recently, the components and functions of a variety of non-centrosomal microtubule-organizing centers (ncMTOCs) have begun to be elucidated. Throughout Drosophila development, a wide variety of unique ncMTOCs form in epithelial and non-epithelial cell types at an assortment of subcellular locations. Some of these cell types also utilize the centrosomal MTOC, while others rely exclusively on ncMTOCs. The impressive variety of ncMTOCs being discovered provides novel insight into the diverse functions of MTOCs in cells and tissues. This review highlights our current knowledge of the composition, assembly, and functional roles of centrosomal and non-centrosomal MTOCs in Drosophila.
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Affiliation(s)
- Marisa M L Tillery
- Department of Biomedical Sciences, Florida State University, 1115 West Call St., Tallahassee, FL 32306, USA.
| | - Caitlyn Blake-Hedges
- Department of Biomedical Sciences, Florida State University, 1115 West Call St., Tallahassee, FL 32306, USA.
| | - Yiming Zheng
- Department of Biomedical Sciences, Florida State University, 1115 West Call St., Tallahassee, FL 32306, USA.
| | - Rebecca A Buchwalter
- Department of Biomedical Sciences, Florida State University, 1115 West Call St., Tallahassee, FL 32306, USA.
| | - Timothy L Megraw
- Department of Biomedical Sciences, Florida State University, 1115 West Call St., Tallahassee, FL 32306, USA.
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18
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The ABD on the nascent polypeptide and PH domain are required for the precise Anillin localization in Drosophila syncytial blastoderm. Sci Rep 2018; 8:12910. [PMID: 30150713 PMCID: PMC6110771 DOI: 10.1038/s41598-018-31106-0] [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: 05/02/2018] [Accepted: 08/03/2018] [Indexed: 01/19/2023] Open
Abstract
Targeting proteins to regions where they are required is essential for proper development of organisms. For achievement of this, subcellular mRNA localization is one of the critical mechanisms. Subcellular mRNA localization is an evolutionarily conserved phenomenon from E. coli to human and contributes to limiting the regions at which its products function and efficiently supplies substrates for protein translation. During early Drosophila embryogenesis, while 71% of the 3370 mRNAs analyzed have shown prominent subcellular localization, the underlying molecular mechanisms have not been elucidated. Here, we reveal that anillin mRNA, one of the localized mRNAs in early Drosophila embryo, localizes to the tip of the pseudo-cleavage furrow in the Drosophila syncytial blastoderm using in situ hybridization combined with immunohistochemistry. Localization analyses with transgenic fly lines carrying a series of deletion mRNAs indicate that this localization is dependent on its own nascent polypeptides including the actin binding domain (ABD). In addition to the mRNA localization, it is revealed that the pleckstrin homology (PH) domain of Anillin protein is also required for its proper localization. Thus, we indicate that the precise localization of Anillin protein is tightly regulated by the ABD on the nascent polypeptide and PH domain in the Drosophila syncytial blastoderm.
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19
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A Cyclin E Centered Genetic Network Contributes to Alcohol-Induced Variation in Drosophila Development. G3-GENES GENOMES GENETICS 2018; 8:2643-2653. [PMID: 29871898 PMCID: PMC6071605 DOI: 10.1534/g3.118.200260] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Prenatal exposure to ethanol causes a wide range of adverse physiological, behavioral and cognitive consequences. However, identifying allelic variants and genetic networks associated with variation in susceptibility to prenatal alcohol exposure is challenging in human populations, since time and frequency of exposure and effective dose cannot be determined quantitatively and phenotypic manifestations are diverse. Here, we harnessed the power of natural variation in the Drosophila melanogaster Genetic Reference Panel (DGRP) to identify genes and genetic networks associated with variation in sensitivity to developmental alcohol exposure. We measured development time from egg to adult and viability of 201 DGRP lines reared on regular or ethanol- supplemented medium and identified polymorphisms associated with variation in susceptibility to developmental ethanol exposure. We also documented genotype-dependent variation in sensorimotor behavior after developmental exposure to ethanol using the startle response assay in a subset of 39 DGRP lines. Genes associated with development, including development of the nervous system, featured prominently among genes that harbored variants associated with differential sensitivity to developmental ethanol exposure. Many of them have human orthologs and mutational analyses and RNAi targeting functionally validated a high percentage of candidate genes. Analysis of genetic interaction networks identified Cyclin E (CycE) as a central, highly interconnected hub gene. Cyclin E encodes a protein kinase associated with cell cycle regulation and is prominently expressed in ovaries. Thus, exposure to ethanol during development of Drosophila melanogaster might serve as a genetic model for translational studies on fetal alcohol spectrum disorder.
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20
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Schmidt A, Grosshans J. Dynamics of cortical domains in early Drosophila development. J Cell Sci 2018; 131:131/7/jcs212795. [DOI: 10.1242/jcs.212795] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
ABSTRACT
Underlying the plasma membrane of eukaryotic cells is an actin cortex that includes actin filaments and associated proteins. A special feature of all polarized and epithelial cells are cortical domains, each of which is characterized by specific sets of proteins. Typically, an epithelial cell contains apical, subapical, lateral and basal domains. The domain-specific protein sets contain evolutionarily conserved proteins, as well as cell-type-specific factors. Among the conserved proteins are, the Par proteins, Crumbs complex and the lateral proteins Scribbled and Discs large 1. Organization of the plasma membrane into cortical domains is dynamic and depends on cell type, differentiation and developmental stage. The dynamics of cortical organization is strikingly visible in early Drosophila embryos, which increase the number of distinct cortical domains from one, during the pre-blastoderm stage, to two in syncytial blastoderm embryos, before finally acquiring the four domains that are typical for epithelial cells during cellularization. In this Review, we will describe the dynamics of cortical organization in early Drosophila embryos and discuss the processes and mechanisms underlying cortical remodeling.
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Affiliation(s)
- Anja Schmidt
- Institute for Developmental Biochemistry, Medical School, University of Göttingen, 37077 Göttingen, Germany
| | - Jörg Grosshans
- Institute for Developmental Biochemistry, Medical School, University of Göttingen, 37077 Göttingen, Germany
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21
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Figard L, Wang M, Zheng L, Golding I, Sokac AM. Membrane Supply and Demand Regulates F-Actin in a Cell Surface Reservoir. Dev Cell 2017; 37:267-78. [PMID: 27165556 DOI: 10.1016/j.devcel.2016.04.010] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2015] [Revised: 11/19/2015] [Accepted: 04/12/2016] [Indexed: 11/16/2022]
Abstract
Cells store membrane in surface reservoirs of pits and protrusions. These membrane reservoirs facilitate cell shape change and buffer mechanical stress, but we do not know how reservoir dynamics are regulated. During cellularization, the first cytokinesis in Drosophila embryos, a reservoir of microvilli unfolds to fuel cleavage furrow ingression. We find that regulated exocytosis adds membrane to the reservoir before and during unfolding. Dynamic F-actin deforms exocytosed membrane into microvilli. Single microvilli extend and retract in ∼20 s, while the overall reservoir is depleted in sync with furrow ingression over 60-70 min. Using pharmacological and genetic perturbations, we show that exocytosis promotes microvillar F-actin assembly, while furrow ingression controls microvillar F-actin disassembly. Thus, reservoir F-actin and, consequently, reservoir dynamics are regulated by membrane supply from exocytosis and membrane demand from furrow ingression.
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Affiliation(s)
- Lauren Figard
- Verna & Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, One Baylor Plaza, BCM125, Houston, TX 77030, USA; Graduate Program in Integrative Molecular and Biomedical Sciences, Baylor College of Medicine, Houston, TX 77030, USA
| | - Mengyu Wang
- Verna & Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, One Baylor Plaza, BCM125, Houston, TX 77030, USA; Graduate Program in Structural and Computational Biology and Molecular Biophysics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Liuliu Zheng
- Verna & Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, One Baylor Plaza, BCM125, Houston, TX 77030, USA
| | - Ido Golding
- Verna & Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, One Baylor Plaza, BCM125, Houston, TX 77030, USA; Graduate Program in Structural and Computational Biology and Molecular Biophysics, Baylor College of Medicine, Houston, TX 77030, USA; Center for the Physics of Living Cells, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA; Center for Theoretical Biological Physics, Rice University, Houston, TX 77005, USA
| | - Anna Marie Sokac
- Verna & Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, One Baylor Plaza, BCM125, Houston, TX 77030, USA; Graduate Program in Integrative Molecular and Biomedical Sciences, Baylor College of Medicine, Houston, TX 77030, USA.
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22
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Brose L, Crest J, Tao L, Sullivan W. Polo kinase mediates the phosphorylation and cellular localization of Nuf/FIP3, a Rab11 effector. Mol Biol Cell 2017; 28:1435-1443. [PMID: 28381422 PMCID: PMC5449144 DOI: 10.1091/mbc.e16-04-0236] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2016] [Revised: 03/23/2017] [Accepted: 03/31/2017] [Indexed: 01/28/2023] Open
Abstract
Animal cytokinesis involves both actin-myosin-based contraction and vesicle-mediated membrane addition. In many cell types, including early Drosophila embryos, Nuf/FIP3, a Rab11 effector, mediates recycling endosome (RE)-based vesicle delivery to the cytokinesis furrow. Nuf exhibits a cell cycle-regulated concentration at the centrosome that is accompanied by dramatic changes in its phosphorylation state. Here we demonstrate that maximal phosphorylation of Nuf occurs at prophase, when centrosome-associated Nuf disperses throughout the cytoplasm. Accordingly, ectopic Cdk1 activation results in immediate Nuf dispersal from the centrosome. Screening of candidate kinases reveals a specific, dosage-sensitive interaction between Nuf and Polo with respect to Nuf-mediated furrow formation. Inhibiting Polo activity results in Nuf underphosphorylation and prolonged centrosome association. In vitro, Polo directly binds and is required for Nuf phosphorylation at Ser-225 and Thr-227, matching previous in vivo-mapped phosphorylation sites. These results demonstrate a role for Polo kinase in directly mediating Nuf cell cycle-dependent localization.
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Affiliation(s)
- Lotti Brose
- Department of Molecular, Cell, and Developmental Biology, University of California, Santa Cruz, Santa Cruz, CA 95064
| | - Justin Crest
- Department of Molecular, Cell, and Developmental Biology, University of California, Santa Cruz, Santa Cruz, CA 95064
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720
| | - Li Tao
- Department of Molecular, Cell, and Developmental Biology, University of California, Santa Cruz, Santa Cruz, CA 95064
- Department of Biology, University of Hawaii, Hilo, HI 96720
| | - William Sullivan
- Department of Molecular, Cell, and Developmental Biology, University of California, Santa Cruz, Santa Cruz, CA 95064
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23
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Gulluni F, Martini M, Hirsch E. Cytokinetic Abscission: Phosphoinositides and ESCRT
s
Direct the Final Cut. J Cell Biochem 2017; 118:3561-3568. [DOI: 10.1002/jcb.26066] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2017] [Accepted: 04/14/2017] [Indexed: 01/23/2023]
Affiliation(s)
- Federico Gulluni
- Department of Molecular Biotechnology and Health SciencesUniversity of TurinTurinItaly
| | - Miriam Martini
- Department of Molecular Biotechnology and Health SciencesUniversity of TurinTurinItaly
| | - Emilio Hirsch
- Department of Molecular Biotechnology and Health SciencesUniversity of TurinTurinItaly
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24
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Abstract
BAR domain proteins can regulate ‘membrane reservoirs’ that provide surface area and buffer membrane tension. Syndapin is an F-BAR and SH3 domain containing protein involved in cytoskeletal remodelling and endocytosis. The Syndapin F-BAR domain is uniquely versatile compared to others in the family and can bend phospholipid membranes into tubules of various diameters and directly bind actin. The Syndapin SH3 domain can also interact with actin remodelling proteins and modulate cytoskeletal contractility. Pseudocleavage furrow extension in the syncytial division cycles of Drosophila embryos requires the homeostatic control of conserved processes that control plasma membrane tension and actin contractility. We find that Syndapin plays an important role in promoting pseudocleavage furrow extension. We propose a model involving roles for Syndapin in membrane dynamics and direct or indirect effect on the cytoskeleton to explain how it affects pseudocleavage furrow growth, independent of its role in endocytosis.
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Affiliation(s)
- Aparna Sherlekar
- Biology, Indian Institute of Science Education and Research, Pune, India
| | - Richa Rikhy
- Biology, Indian Institute of Science Education and Research, Pune, India
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25
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Proteomics Screen Identifies Class I Rab11 Family Interacting Proteins as Key Regulators of Cytokinesis. Mol Cell Biol 2017; 37:MCB.00278-16. [PMID: 27872148 DOI: 10.1128/mcb.00278-16] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Accepted: 11/11/2016] [Indexed: 01/08/2023] Open
Abstract
The 14-3-3 protein family orchestrates a complex network of molecular interactions that regulates various biological processes. Owing to their role in regulating the cell cycle and protein trafficking, 14-3-3 proteins are prevalent in human diseases such as cancer, diabetes, and neurodegeneration. 14-3-3 proteins are expressed in all eukaryotic cells, suggesting that they mediate their biological functions through evolutionarily conserved protein interactions. To identify these core 14-3-3 client proteins, we used an affinity-based proteomics approach to characterize and compare the human and Drosophila 14-3-3 interactomes. Using this approach, we identified a group of Rab11 effector proteins, termed class I Rab11 family interacting proteins (Rab11-FIPs), or Rip11 in Drosophila We found that 14-3-3 binds to Rip11 in a phospho-dependent manner to ensure its proper subcellular distribution during cell division. Our results indicate that Rip11 plays an essential role in the regulation of cytokinesis and that this function requires its association with 14-3-3 but not with Rab11. Together, our results suggest an evolutionarily conserved role for 14-3-3 in controlling Rip11-dependent protein transport during cytokinesis.
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26
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Khanal I, Elbediwy A, Diaz de la Loza MDC, Fletcher GC, Thompson BJ. Shot and Patronin polarise microtubules to direct membrane traffic and biogenesis of microvilli in epithelia. J Cell Sci 2016; 129:2651-9. [PMID: 27231092 PMCID: PMC4958304 DOI: 10.1242/jcs.189076] [Citation(s) in RCA: 60] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2016] [Accepted: 05/19/2016] [Indexed: 01/08/2023] Open
Abstract
In epithelial tissues, polarisation of microtubules and actin microvilli occurs along the apical-basal axis of each cell, yet how these cytoskeletal polarisation events are coordinated remains unclear. Here, we examine the hierarchy of events during cytoskeletal polarisation in Drosophila melanogaster epithelia. Core apical-basal polarity determinants polarise the spectrin cytoskeleton to recruit the microtubule-binding proteins Patronin (CAMSAP1, CAMSAP2 and CAMSAP3 in humans) and Shortstop [Shot; MACF1 and BPAG1 (also known as DST) in humans] to the apical membrane domain. Patronin and Shot then act to polarise microtubules along the apical-basal axis to enable apical transport of Rab11 endosomes by the Nuf-Dynein microtubule motor complex. Finally, Rab11 endosomes are transferred to the MyoV (also known as Didum in Drosophila) actin motor to deliver the key microvillar determinant Cadherin 99C to the apical membrane to organise the biogenesis of actin microvilli.
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Affiliation(s)
- Ichha Khanal
- The Francis Crick Institute, 44 Lincoln's Inn Fields, London WC2A 3LY, UK
| | - Ahmed Elbediwy
- The Francis Crick Institute, 44 Lincoln's Inn Fields, London WC2A 3LY, UK
| | | | | | - Barry J Thompson
- The Francis Crick Institute, 44 Lincoln's Inn Fields, London WC2A 3LY, UK
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27
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Sherlekar A, Rikhy R. Syndapin promotes pseudocleavage furrow formation by actin organization in the syncytial Drosophila embryo. Mol Biol Cell 2016; 27:2064-79. [PMID: 27146115 PMCID: PMC4927280 DOI: 10.1091/mbc.e15-09-0656] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2015] [Accepted: 04/26/2016] [Indexed: 12/03/2022] Open
Abstract
F-BAR domain–containing proteins link the actin cytoskeleton to the membrane during membrane remodeling. Syndapin associates with the pseudocleavage furrow membrane and is essential for furrow morphology, actin organization, and extension downstream of initiation factor RhoGEF2. Coordinated membrane and cytoskeletal remodeling activities are required for membrane extension in processes such as cytokinesis and syncytial nuclear division cycles in Drosophila. Pseudocleavage furrow membranes in the syncytial Drosophila blastoderm embryo show rapid extension and retraction regulated by actin-remodeling proteins. The F-BAR domain protein Syndapin (Synd) is involved in membrane tubulation, endocytosis, and, uniquely, in F-actin stability. Here we report a role for Synd in actin-regulated pseudocleavage furrow formation. Synd localized to these furrows, and its loss resulted in short, disorganized furrows. Synd presence was important for the recruitment of the septin Peanut and distribution of Diaphanous and F-actin at furrows. Synd and Peanut were both absent in furrow-initiation mutants of RhoGEF2 and Diaphanous and in furrow-progression mutants of Anillin. Synd overexpression in rhogef2 mutants reversed its furrow-extension phenotypes, Peanut and Diaphanous recruitment, and F-actin organization. We conclude that Synd plays an important role in pseudocleavage furrow extension, and this role is also likely to be crucial in cleavage furrow formation during cell division.
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Affiliation(s)
- Aparna Sherlekar
- Biology, Indian Institute of Science Education and Research, Pashan, Pune 411008, India
| | - Richa Rikhy
- Biology, Indian Institute of Science Education and Research, Pashan, Pune 411008, India
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28
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Mavor LM, Miao H, Zuo Z, Holly RM, Xie Y, Loerke D, Blankenship JT. Rab8 directs furrow ingression and membrane addition during epithelial formation in Drosophila melanogaster. Development 2016; 143:892-903. [PMID: 26839362 PMCID: PMC4813336 DOI: 10.1242/dev.128876] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2015] [Accepted: 01/25/2016] [Indexed: 01/31/2023]
Abstract
One of the most fundamental changes in cell morphology is the ingression of a plasma membrane furrow. The Drosophila embryo undergoes several cycles of rapid furrow ingression during early development that culminate in the formation of an epithelial sheet. Previous studies have demonstrated the requirement for intracellular trafficking pathways in furrow ingression; however, the pathways that link compartmental behaviors with cortical furrow ingression events are unclear. Here, we show that Rab8 has striking dynamic behaviors in vivo. As furrows ingress, cytoplasmic Rab8 puncta are depleted and Rab8 accumulates at the plasma membrane in a location that coincides with known regions of directed membrane addition. We additionally use CRISPR/Cas9 technology to N-terminally tag Rab8, which is then used to address endogenous localization and function. Endogenous Rab8 displays partial coincidence with Rab11 and the Golgi, and this colocalization is enriched during the fast phase of cellularization. When Rab8 function is disrupted, furrow formation in the early embryo is completely abolished. We also demonstrate that Rab8 behaviors require the function of the exocyst complex subunit Sec5 as well as the recycling endosome protein Rab11. Active, GTP-locked Rab8 is primarily associated with dynamic membrane compartments and the plasma membrane, whereas GDP-locked Rab8 forms large cytoplasmic aggregates. These studies suggest a model in which active Rab8 populations direct furrow ingression by guiding the targeted delivery of cytoplasmic membrane stores to the cell surface through interactions with the exocyst tethering complex.
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Affiliation(s)
- Lauren M Mavor
- Department of Biological Sciences, University of Denver, Denver, CO 80208, USA
| | - Hui Miao
- Department of Biological Sciences, University of Denver, Denver, CO 80208, USA
| | - Zhongyuan Zuo
- Department of Biological Sciences, University of Denver, Denver, CO 80208, USA
| | - Ryan M Holly
- Department of Biological Sciences, University of Denver, Denver, CO 80208, USA
| | - Yi Xie
- Department of Biological Sciences, University of Denver, Denver, CO 80208, USA
| | - Dinah Loerke
- Department of Physics, University of Denver, Denver, CO 80208, USA
| | - J Todd Blankenship
- Department of Biological Sciences, University of Denver, Denver, CO 80208, USA
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29
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DeBruhl H, Albertson R, Swider Z, Sullivan W. Rop, the Sec1/Munc18 homolog in Drosophila, is required for furrow ingression and stable cell shape during cytokinesis. J Cell Sci 2015; 129:430-43. [PMID: 26631487 DOI: 10.1242/jcs.179200] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2015] [Accepted: 11/30/2015] [Indexed: 01/08/2023] Open
Abstract
Physically separating daughter cells during cytokinesis requires contraction of an actin-myosin ring and vesicle-mediated membrane addition at the cleavage furrow. To identify vesicle trafficking proteins that function in cytokinesis, we screened deficiencies and mutations of candidate genes by live imaging the mitotic domains of the Drosophila embryo. In embryos homozygous for some of these deficiencies, we observed several cytokinesis phenotypes, including slow furrow ingression and increased membrane blebbing. We also found that cytokinesis required the Sec1/Munc18 homolog Rop, which interacts with syntaxin and mediates exocytosis at the plasma membrane. In a temperature-sensitive Rop mutant (Rop(TS)), the contractile ring disassembled during furrow ingression, indicating that maintenance of the ring required vesicle addition. Furthermore, in some dividing Rop(TS) cells, the shape of the daughter cells became unstable, causing cytokinesis failure. These results further highlight the importance of vesicle trafficking in animal cytokinesis and show that vesicle fusion influences cell shape during cytokinesis.
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Affiliation(s)
- Heather DeBruhl
- Molecular, Cell and Developmental Biology, University of California at Santa Cruz, Santa Cruz, CA 95064, USA
| | | | - Zachary Swider
- Molecular, Cell and Developmental Biology, University of California at Santa Cruz, Santa Cruz, CA 95064, USA
| | - William Sullivan
- Molecular, Cell and Developmental Biology, University of California at Santa Cruz, Santa Cruz, CA 95064, USA
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30
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Nakayama K. Regulation of cytokinesis by membrane trafficking involving small GTPases and the ESCRT machinery. Crit Rev Biochem Mol Biol 2015; 51:1-6. [PMID: 26362026 DOI: 10.3109/10409238.2015.1085827] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
During cell division, cells undergo membrane remodeling to achieve changes in their size and shape. In addition, cell division entails local delivery and retrieval of membranes and specific proteins as well as remodeling of cytoskeletons, in particular, upon cytokinetic abscission. Accumulating lines of evidence highlight that endocytic membrane removal from and subsequent membrane delivery to the plasma membrane are crucial for the changes in cell size and shape, and that trafficking of vesicles carrying specific proteins to the abscission site participate in local remodeling of membranes and cytoskeletons. Furthermore, the endosomal sorting complex required for transport (ESCRT) machinery has been shown to play crucial roles in cytokinetic abscission. Here, the author briefly overviews membrane-trafficking events early in cell division, and subsequently focus on regulation and functional significance of membrane trafficking involving Rab11 and Arf6 small GTPases in late cytokinesis phases and assembly of the ESCRT machinery in cytokinetic abscission.
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Affiliation(s)
- Kazuhisa Nakayama
- a Graduate School of Pharmaceutical Sciences, Kyoto University , Kyoto , Japan
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Holly RM, Mavor LM, Zuo Z, Blankenship JT. A rapid, membrane-dependent pathway directs furrow formation through RalA in the early Drosophila embryo. Development 2015; 142:2316-28. [PMID: 26092850 DOI: 10.1242/dev.120998] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2014] [Accepted: 05/13/2015] [Indexed: 01/31/2023]
Abstract
Plasma membrane furrow formation is crucial in cell division and cytokinesis. Furrow formation in early syncytial Drosophila embryos is exceptionally rapid, with furrows forming in as little as 3.75 min. Here, we use 4D imaging to identify furrow formation, stabilization, and regression periods, and identify a rapid, membrane-dependent pathway that is essential for plasma membrane furrow formation in vivo. Myosin II function is thought to provide the ingression force for cytokinetic furrows, but the role of membrane trafficking pathways in guiding furrow formation is less clear. We demonstrate that a membrane trafficking pathway centered on Ras-like protein A (RalA) is required for fast furrow ingression in the early fly embryo. RalA function is absolutely required for furrow formation and initiation. In the absence of RalA and furrow function, chromosomal segregation is aberrant and polyploid nuclei are observed. RalA localizes to syncytial furrows, and mediates the movement of exocytic vesicles to the plasma membrane. Sec5, which is an exocyst complex subunit and localizes to ingressing furrows in wild-type embryos, becomes punctate and loses its cortical association in the absence of RalA function. Rab8 also fails to traffic to the plasma membrane and accumulates aberrantly in the cytoplasm in RalA disrupted embryos. RalA localization precedes F-actin recruitment to the furrow tip, suggesting that membrane trafficking might function upstream of cytoskeletal remodeling. These studies identify a pathway, which stretches from Rab8 to RalA and the exocyst complex, that mediates rapid furrow formation in early Drosophila embryos.
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Affiliation(s)
- Ryan M Holly
- Department of Biological Sciences, University of Denver, Denver, CO 80208, USA
| | - Lauren M Mavor
- Department of Biological Sciences, University of Denver, Denver, CO 80208, USA
| | - Zhongyuan Zuo
- Department of Biological Sciences, University of Denver, Denver, CO 80208, USA
| | - J Todd Blankenship
- Department of Biological Sciences, University of Denver, Denver, CO 80208, USA
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Kang M, Andreani M, Kenworthy AK. Validation of Normalizations, Scaling, and Photofading Corrections for FRAP Data Analysis. PLoS One 2015; 10:e0127966. [PMID: 26017223 PMCID: PMC4446327 DOI: 10.1371/journal.pone.0127966] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2014] [Accepted: 04/22/2015] [Indexed: 01/14/2023] Open
Abstract
Fluorescence Recovery After Photobleaching (FRAP) has been a versatile tool to study transport and reaction kinetics in live cells. Since the fluorescence data generated by fluorescence microscopy are in a relative scale, a wide variety of scalings and normalizations are used in quantitative FRAP analysis. Scaling and normalization are often required to account for inherent properties of diffusing biomolecules of interest or photochemical properties of the fluorescent tag such as mobile fraction or photofading during image acquisition. In some cases, scaling and normalization are also used for computational simplicity. However, to our best knowledge, the validity of those various forms of scaling and normalization has not been studied in a rigorous manner. In this study, we investigate the validity of various scalings and normalizations that have appeared in the literature to calculate mobile fractions and correct for photofading and assess their consistency with FRAP equations. As a test case, we consider linear or affine scaling of normal or anomalous diffusion FRAP equations in combination with scaling for immobile fractions. We also consider exponential scaling of either FRAP equations or FRAP data to correct for photofading. Using a combination of theoretical and experimental approaches, we show that compatible scaling schemes should be applied in the correct sequential order; otherwise, erroneous results may be obtained. We propose a hierarchical workflow to carry out FRAP data analysis and discuss the broader implications of our findings for FRAP data analysis using a variety of kinetic models.
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Affiliation(s)
- Minchul Kang
- School of Science, Technology & Engineering Management, St. Thomas University, Miami Gardens, Florida, USA
- * E-mail:
| | - Manuel Andreani
- School of Science, Technology & Engineering Management, St. Thomas University, Miami Gardens, Florida, USA
| | - Anne K. Kenworthy
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
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Rikhy R, Mavrakis M, Lippincott-Schwartz J. Dynamin regulates metaphase furrow formation and plasma membrane compartmentalization in the syncytial Drosophila embryo. Biol Open 2015; 4:301-11. [PMID: 25661871 PMCID: PMC4359736 DOI: 10.1242/bio.20149936] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
The successive nuclear division cycles in the syncytial Drosophila embryo are accompanied by ingression and regression of plasma membrane furrows, which surround individual nuclei at the embryo periphery, playing a central role in embryo compartmentalization prior to cellularization. Here, we demonstrate that cell cycle changes in dynamin localization and activity at the plasma membrane (PM) regulate metaphase furrow formation and PM organization in the syncytial embryo. Dynamin was localized on short PM furrows during interphase, mediating endocytosis of PM components. Dynamin redistributed off ingressed PM furrows in metaphase, correlating with stabilized PM components and the associated actin regulatory machinery on long furrows. Acute inhibition of dynamin in the temperature sensitive shibire mutant embryo resulted in morphogenetic consequences in the syncytial division cycle. These included inhibition of metaphase furrow ingression, randomization of proteins normally polarized to intercap PM and disruption of the diffusion barrier separating PM domains above nuclei. Based on these findings, we propose that cell cycle changes in dynamin orchestrate recruitment of actin regulatory machinery for PM furrow dynamics during the early mitotic cycles in the Drosophila embryo.
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Affiliation(s)
- Richa Rikhy
- Cell Biology and Metabolism Program, NICHD, NIH, Building 18T, 101, 18 Library Drive, Bethesda, MD, USA. Present address: Indian Institute of Science Education and Research, Homi Bhabha Road, Pashan, Pune, 411008, India.
| | - Manos Mavrakis
- Institut de Biologie du Développement de Marseille, CNRS UMR7288, Aix-Marseille Université, 13288 Marseille, France
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Phosphoinositides: Lipids with informative heads and mastermind functions in cell division. Biochim Biophys Acta Mol Cell Biol Lipids 2014; 1851:832-43. [PMID: 25449648 DOI: 10.1016/j.bbalip.2014.10.013] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2014] [Revised: 10/21/2014] [Accepted: 10/28/2014] [Indexed: 01/22/2023]
Abstract
Phosphoinositides are low abundant but essential phospholipids in eukaryotic cells and refer to phosphatidylinositol and its seven polyphospho-derivatives. In this review, we summarize our current knowledge on phosphoinositides in multiple aspects of cell division in animal cells, including mitotic cell rounding, longitudinal cell elongation, cytokinesis furrow ingression, intercellular bridge abscission and post-cytokinesis events. PtdIns(4,5)P₂production plays critical roles in spindle orientation, mitotic cell shape and bridge stability after furrow ingression by recruiting force generator complexes and numerous cytoskeleton binding proteins. Later, PtdIns(4,5)P₂hydrolysis and PtdIns3P production are essential for normal cytokinesis abscission. Finally, emerging functions of PtdIns3P and likely PtdIns(4,5)P₂have recently been reported for midbody remnant clearance after abscission. We describe how the multiple functions of phosphoinositides in cell division reflect their distinct roles in local recruitment of protein complexes, membrane traffic and cytoskeleton remodeling. This article is part of a Special Issue entitled Phosphoinositides.
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Lee DM, Harris TJC. Coordinating the cytoskeleton and endocytosis for regulated plasma membrane growth in the early Drosophila embryo. BIOARCHITECTURE 2014; 4:68-74. [PMID: 24874871 PMCID: PMC4199814 DOI: 10.4161/bioa.28949] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Plasma membrane organization is under the control of cytoskeletal networks and endocytic mechanisms, and a growing literature is showing how closely these influences are interconnected. Here, we review how plasma membranes are formed around individual nuclei of the syncytial Drosophila embryo. Specifically, we outline the pathways that promote and maintain the growth of pseudocleavage and cellularization furrows, as well as specific pathways that keep furrow growth in check. This system has become important for studies of actin regulators, such as Rho1, Diaphanous, non-muscle myosin II and Arp2/3, and endocytic regulators, such as a cytohesin Arf-GEF (Steppke), clathrin, Amphiphysin and dynamin. More generally, it provides a model for understanding how cytoskeletal-endocytic cross-talk regulates the assembly of a cell.
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Affiliation(s)
- Donghoon M Lee
- Department of Cell and Systems Biology; University of Toronto; Toronto, ON CA
| | - Tony J C Harris
- Department of Cell and Systems Biology; University of Toronto; Toronto, ON CA
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Function and dynamics of slam in furrow formation in early Drosophila embryo. Dev Biol 2013; 386:371-84. [PMID: 24368071 DOI: 10.1016/j.ydbio.2013.12.022] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2013] [Revised: 12/11/2013] [Accepted: 12/13/2013] [Indexed: 12/31/2022]
Abstract
The Drosophila embryo undergoes a developmental transition in the blastoderm stage switching from syncytial to cellular development. The cleavage furrow, which encloses nuclei into cells, is a prominent morphological feature of this transition. It is not clear how the pattern of the furrow array is defined and how zygotic genes trigger the formation and invagination of interphase furrows. A key to these questions is provided by the gene slam, which has been previously implicated in controlling furrow invagination. Here we investigate the null phenotype of slam, the dynamics of Slam protein, and its control by the recycling endosome. We find that slam is essential for furrow invagination during cellularisation and together with nullo, for specification of the furrow. During cellularisation, Slam marks first the furrow, which is derived from the metaphase furrow of the previous mitosis. Slightly later, Slam accumulates at new furrows between daughter cells early in interphase. Slam is stably associated with the furrow canal except for the onset of cellularisation as revealed by FRAP experiments. Restriction of Slam to the furrow canal and Slam mobility during cellularisation is controlled by the recycling endosome and centrosomes. We propose a three step model. The retracting metaphase furrow leaves an initial mark. This mark and the border between corresponding daughter nuclei are refined by vesicular transport away from pericentrosomal recycling endosome towards the margins of the somatic buds. Following the onset of zygotic gene expression, Slam and Nullo together stabilise this mark and Slam triggers invagination of the cleavage furrow.
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The maternal-to-zygotic transition targets actin to promote robustness during morphogenesis. PLoS Genet 2013; 9:e1003901. [PMID: 24244181 PMCID: PMC3820746 DOI: 10.1371/journal.pgen.1003901] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2013] [Accepted: 09/06/2013] [Indexed: 11/26/2022] Open
Abstract
Robustness is a property built into biological systems to ensure stereotypical outcomes despite fluctuating inputs from gene dosage, biochemical noise, and the environment. During development, robustness safeguards embryos against structural and functional defects. Yet, our understanding of how robustness is achieved in embryos is limited. While much attention has been paid to the role of gene and signaling networks in promoting robust cell fate determination, little has been done to rigorously assay how mechanical processes like morphogenesis are designed to buffer against variable conditions. Here we show that the cell shape changes that drive morphogenesis can be made robust by mechanisms targeting the actin cytoskeleton. We identified two novel members of the Vinculin/α-Catenin Superfamily that work together to promote robustness during Drosophila cellularization, the dramatic tissue-building event that generates the primary epithelium of the embryo. We find that zygotically-expressed Serendipity-α (Sry-α) and maternally-loaded Spitting Image (Spt) share a redundant, actin-regulating activity during cellularization. Spt alone is sufficient for cellularization at an optimal temperature, but both Spt plus Sry-α are required at high temperature and when actin assembly is compromised by genetic perturbation. Our results offer a clear example of how the maternal and zygotic genomes interact to promote the robustness of early developmental events. Specifically, the Spt and Sry-α collaboration is informative when it comes to genes that show both a maternal and zygotic requirement during a given morphogenetic process. For the cellularization of Drosophilids, Sry-α and its expression profile may represent a genetic adaptive trait with the sole purpose of making this extreme event more reliable. Since all morphogenesis depends on cytoskeletal remodeling, both in embryos and adults, we suggest that robustness-promoting mechanisms aimed at actin could be effective at all life stages. Every embryo develops under its own unique set of circumstances, with variable inputs coming from mother, father, and the environment. To then ensure a reliable outcome, mechanisms are built into development to buffer against challenges like genetic deficiency, maternal fever, alcohol exposure, etc. This buffering, called “robustness”, can be overwhelmed, ending in miscarriage, pre-mature birth, and structural and functional birth defects. Thus, we need to understand how robustness arises in order to define an embryo's susceptibilities to genetic background and environment; and to ultimately promote healthy reproduction. In this work we provide new insight into how morphogenesis, the process of tissue building in embryos, is made more robust. First, we show that early gene expression by the embryo, or zygote, supplements the stockpile of proteins already supplied by the mother to ensure the robustness of early morphogenesis. Specifically, our data suggests that a specific gene, sry-α, and its expression by the embryo at the maternal-to-zygotic transition, is a genetic adaptation with the sole function of making the first tissue building event in the fruit fly more robust. In addition, we show that the robustness of this morphogenetic event is promoted by mechanisms regulating the actin cytoskeleton.
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Lee DM, Harris TJC. An Arf-GEF regulates antagonism between endocytosis and the cytoskeleton for Drosophila blastoderm development. Curr Biol 2013; 23:2110-20. [PMID: 24120639 DOI: 10.1016/j.cub.2013.08.058] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2013] [Revised: 08/15/2013] [Accepted: 08/27/2013] [Indexed: 12/31/2022]
Abstract
BACKGROUND Actin cytoskeletal networks push and pull the plasma membrane (PM) to control cell structure and behavior. Endocytosis also regulates the PM and can be promoted or inhibited by cytoskeletal networks. However, endocytic regulation of the general membrane cytoskeleton is undocumented. RESULTS Here, we provide evidence for endocytic inhibition of actomyosin networks. Specifically, we find that Steppke, a cytohesin Arf-guanine nucleotide exchange factor (GEF), controls initial PM furrow ingression during the syncytial nuclear divisions and cellularization of the Drosophila embryo. Acting at the tips of ingressing furrows, Steppke promotes local endocytic events through its Arf-GEF activity and in cooperation with the AP-2 clathrin adaptor complex. These Steppke activities appear to reduce local Rho1 protein levels and ultimately restrain actomyosin networks. Without Steppke, Rho1 pathways linked to actin polymerization and myosin activation abnormally expand the membrane cytoskeleton into taut sheets emanating perpendicularly from the furrow tips. These expansions lead to premature cellularization and abnormal expulsions of nuclei from the forming blastoderm. Finally, consistent with earlier reports, we also find that actomyosin activity can act reciprocally to inhibit the endocytosis at furrow tips. CONCLUSIONS We propose that Steppke-dependent endocytosis keeps the cytoskeleton in check as early PM furrows form. Specifically, a cytohesin Arf-GEF-Arf G protein-AP-2 endocytic axis appears to antagonize Rho1 cytoskeletal pathways to restrain the membrane cytoskeleton. However, as furrows lengthen during cellularization, the cytoskeleton gains strength, blocks the endocytic inhibition, and finally closes off the base of each cell to form the blastoderm.
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Affiliation(s)
- Donghoon M Lee
- Department of Cell & Systems Biology, University of Toronto, Toronto, ON M5S 3G5, Canada
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Poulton JS, Mu FW, Roberts DM, Peifer M. APC2 and Axin promote mitotic fidelity by facilitating centrosome separation and cytoskeletal regulation. Development 2013; 140:4226-36. [PMID: 24026117 DOI: 10.1242/dev.094425] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
To ensure the accurate transmission of genetic material, chromosome segregation must occur with extremely high fidelity. Segregation errors lead to chromosomal instability (CIN), with deleterious consequences. Mutations in the tumor suppressor adenomatous polyposis coli (APC) initiate most colon cancers and have also been suggested to promote disease progression through increased CIN, but the mechanistic role of APC in preventing CIN remains controversial. Using fly embryos as a model, we investigated the role of APC proteins in CIN. Our findings suggest that APC2 loss leads to increased rates of chromosome segregation error. This occurs through a cascade of events beginning with incomplete centrosome separation leading to failure to inhibit formation of ectopic cleavage furrows, which result in mitotic defects and DNA damage. We test several hypotheses related to the mechanism of action of APC2, revealing that APC2 functions at the embryonic cortex with several protein partners, including Axin, to promote mitotic fidelity. Our in vivo data demonstrate that APC2 protects genome stability by modulating mitotic fidelity through regulation of the cytoskeleton.
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Affiliation(s)
- John S Poulton
- Department of Biology, University of North Carolina, Chapel Hill, NC 27599, USA
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Abstract
Dendritic arborization of neurons is regulated by brain-derived neurotrophic factor (BDNF) together with its receptor, TrkB. Endocytosis is required for dendritic branching and regulates TrkB signaling, but how postendocytic trafficking determines the neuronal response to BDNF is not well understood. The monomeric GTPase Rab11 regulates the dynamics of recycling endosomes and local delivery of receptors to specific dendritic compartments. We investigated whether Rab11-dependent trafficking of TrkB in dendrites regulates BDNF-induced dendritic branching in rat hippocampal neurons. We report that TrkB in dendrites is a cargo for Rab11 endosomes and that both Rab11 and its effector, MyoVb, are required for BDNF/TrkB-induced dendritic branching. In addition, BDNF induces the accumulation of Rab11-positive endosomes and GTP-bound Rab11 in dendrites and the expression of a constitutively active mutant of Rab11 is sufficient to increase dendritic branching by increasing TrkB localization in dendrites and enhancing sensitization to endogenous BDNF. We propose that Rab11-dependent dendritic recycling provides a mechanism to retain TrkB in dendrites and to increase local signaling to regulate arborization.
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Qi X, Zheng H. Rab-A1c GTPase defines a population of the trans-Golgi network that is sensitive to endosidin1 during cytokinesis in Arabidopsis. MOLECULAR PLANT 2013; 6:847-59. [PMID: 23075992 DOI: 10.1093/mp/sss116] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
In plant cells, Rab-A proteins have been implicated to play important roles in membrane trafficking from the trans-Golgi network (TGN) to the plasma membrane/cell wall and to the newly formed cell plate in cytokinesis. But how different Rab-A proteins may work in the TGN is not well studied. We show here that RAB-A1c defines a population of TGN that is partially overlapped with the VHA-a1 marked-TGN. Interestingly, the morphology of RAB-A1c defined-TGN is sensitive to endosidin 1 (ES1), but not to wortmannin. In mitotic cells, RAB-A1c is relocated to the cell plate. We revealed that this process could be interrupted by ES1, but not by wortmannin. In addition, root growth and cytokinesis in root mitotic cells of rab-a1a/b/c triple mutant seedlings are hypersensitive to lower concentrations of ES1. ES1 is known to selectively block the transport of several plasma membrane auxin transporters, including PIN2 and AUX1 at the TGN. Together with the known facts that members of Rab-A1 proteins are involved in auxin-mediated responses in root growth and that mutations in TRAPPII, a protein complex that acts upstream of RAB-A1c, also selectively impair the transport of PIN2 and AUX1 at the TGN, we propose that the Rab-A1-mediated trafficking pathways around the TGN, but not Rab-A1s directly, are the target of ES1.
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Affiliation(s)
- Xingyun Qi
- Department of Biology, McGill University, 1205 Dr Penfield Avenue, Montreal, Quebec H3A 1B1, Canada
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Ramel D, Wang X, Laflamme C, Montell DJ, Emery G. Rab11 regulates cell-cell communication during collective cell movements. Nat Cell Biol 2013; 15:317-24. [PMID: 23376974 DOI: 10.1038/ncb2681] [Citation(s) in RCA: 121] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2012] [Accepted: 12/19/2012] [Indexed: 12/15/2022]
Abstract
Collective cell movements contribute to development and metastasis. The small GTPase Rac is a key regulator of actin dynamics and cell migration but the mechanisms that restrict Rac activation and localization in a group of collectively migrating cells are unknown. Here, we demonstrate that the small GTPases Rab5 and Rab11 regulate Rac activity and polarization during collective cell migration. We use photoactivatable forms of Rac to demonstrate that Rab11 acts on the entire group to ensure that Rac activity is properly restricted to the leading cell through regulation of cell-cell communication. In addition, we show that Rab11 binds to the actin cytoskeleton regulator Moesin and regulates its activation in vivo during migration. Accordingly, reducing the level of Moesin activity also affects cell-cell communication, whereas expressing active Moesin rescues loss of Rab11 function. Our model suggests that Rab11 controls the sensing of the relative levels of Rac activity in a group of cells, leading to the organization of individual cells in a coherent multicellular motile structure.
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Affiliation(s)
- Damien Ramel
- Institute for Research in Immunology and Cancer (IRIC) and Department of Pathology and Cell Biology, Faculty of Medicine, Université de Montréal, Montréal, Quebec, H3C 3J7, Canada
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Abstract
Endocytic membrane transport has recently emerged as a key process required for the successful completion of cytokinesis. Specific endocytic membranes act in concert with the cytoskeleton and ESCRT proteins to regulate the various stages of cytokinesis. In this review, we focus on the different endocytic Arf and Rab GTPases and their interaction proteins that regulate organelle transport to the intracellular bridge during cytokinesis. The identity and function of these endocytic organelles during the late stages of cell division will also be discussed.
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Abstract
New findings provide evidence that developmentally staged RhoGEFs control assembly of two alternative forms of cleavage furrows: the 'Rappaport' furrows, which govern division of Drosophila syncytial cortical division cycles, and conventional spindle-directed furrows.
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RhoGEF and positioning of rappaport-like furrows in the early Drosophila embryo. Curr Biol 2012; 22:2037-41. [PMID: 23022066 DOI: 10.1016/j.cub.2012.08.046] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2012] [Revised: 07/26/2012] [Accepted: 08/20/2012] [Indexed: 12/22/2022]
Abstract
Early Drosophila embryogenesis is characterized by shifting from astral microtubule-based to central spindle-based positioning of cleavage furrows. Before cellularization, astral microtubules determine metaphase furrow position by producing Rappaport-like furrows, which encompass rather than bisect the spindle. Their positioning is explained by our finding that the conserved central spindle components centralspindlin (mKLP1 and RacGAP50C), Polo, and Fascetto (Prc1) localize to the astral microtubule overlap region. These components and the chromosomal passenger complex localize to the central spindle, though no furrow forms there. We identify the maternally supplied RhoGEF2 as a key factor in metaphase furrow positioning. Unlike the zygotic, central spindle-localized RhoGEF (Pebble), RhoGEF2 localizes to metaphase furrows, a function distinct from RhoGEF/Pebble and likely due to the absence of a RacGAP50C binding domain. Accordingly, we find that ectopic activation of Rho GTPase generates furrows perpendicular to the central spindle during syncytial divisions. Whereas metaphase furrow formation is myosin independent, these ectopic furrows, like conventional furrows, require myosin as well as microtubules. These studies demonstrate that early Drosophila embryogenesis is primed to form furrows at either overlapping astral microtubules or the central spindle. We propose that the shift to the latter is driven by a corresponding shift from RhoGEF2 to Pebble in controlling furrow formation.
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Echard A. Phosphoinositides and cytokinesis: the "PIP" of the iceberg. Cytoskeleton (Hoboken) 2012; 69:893-912. [PMID: 23012232 DOI: 10.1002/cm.21067] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2012] [Revised: 08/20/2012] [Accepted: 08/21/2012] [Indexed: 12/21/2022]
Abstract
Phosphoinositides [Phosphatidylinositol (PtdIns), phosphatidylinositol 3-monophosphate (PtdIns3P), phosphatidylinositol 4-monophosphate (PtdIns4P), phosphatidylinositol 5-monophosphate (PtdIns5P), phosphatidylinositol 3,4-bisphosphate (PtdIns(3,4)P(2) ), phosphatidylinositol 3,5-bisphosphate (PtdIns(3,5)P(2) ), phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P(2) ), and phosphatidylinositol 3,4,5-trisphosphate (PtdIns(3,4,5)P(3) )] are lowly abundant acidic lipids found at the cytosolic leaflet of the plasma membrane and intracellular membranes. Initially discovered as precursors of second messengers in signal transduction, phosphoinositides are now known to directly or indirectly control key cellular functions, such as cell polarity, cell migration, cell survival, cytoskeletal dynamics, and vesicular traffic. Phosphoinositides actually play a central role at the interface between membranes and cytoskeletons and contribute to the identity of the cellular compartments by recruiting specific proteins. Increasing evidence indicates that several phosphoinositides, particularly PtdIns(4,5)P(2) , are essential for cytokinesis, notably after furrow ingression. The present knowledge about the specific phosphoinositides and phosphoinositide modifying-enzymes involved in cytokinesis will be first presented. The review of the current data will then show that furrow stability and cytokinesis abscission require that both phosphoinositide production and hydrolysis are regulated in space and time. Finally, I will further discuss recent mechanistic insights on how phosphoinositides regulate membrane trafficking and cytoskeletal remodeling for successful furrow ingression and intercellular bridge abscission. This will highlight unanticipated connections between cytokinesis and enzymes implicated in human diseases, such as the Lowe syndrome.
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Affiliation(s)
- Arnaud Echard
- Membrane Traffic and Cell Division Lab, Institut Pasteur, 28 rue du Dr Roux 75015 Paris, France; CNRS URA2582, Paris, France.
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47
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Caenorhabditis elegans screen reveals role of PAR-5 in RAB-11-recycling endosome positioning and apicobasal cell polarity. Nat Cell Biol 2012; 14:666-76. [PMID: 22634595 DOI: 10.1038/ncb2508] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2012] [Accepted: 04/19/2012] [Indexed: 02/08/2023]
Abstract
Apically enriched Rab11-positive recycling endosomes (Rab11-REs) are important for establishing and maintaining epithelial polarity. Yet, little is known about the molecules controlling trafficking of Rab11-REs in an epithelium in vivo. Here, we report a genome-wide, image-based RNA interference screen for regulators of Rab11-RE positioning and transport of an apical membrane protein (PEPT-1) in C. elegans intestine. Among the 356 screen hits was the 14-3-3 and partitioning defective protein PAR-5, which we found to be specifically required for Rab11-RE positioning and apicobasal polarity maintenance. Depletion of PAR-5 induced abnormal clustering of Rab11-REs to ectopic sites at the basolateral cortex containing F-actin and other apical domain components. This phenotype required key regulators of F-actin dynamics and polarity, such as Rho GTPases (RHO-1 and the Rac1 orthologue CED-10) and apical PAR proteins. Our data suggest that PAR-5 acts as a regulatory hub for a polarity-maintaining network required for apicobasal asymmetry of F-actin and proper Rab11-RE positioning.
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Abstract
Endocytic trafficking is a highly organized process regulated by a network of proteins, including the Rab family of small GTP-binding proteins and the C-terminal EHDs (Eps15 homology-domain-containing proteins). Central roles for Rab proteins have been described in vesicle budding, delivery, tethering and fusion, whereas little is known about the functions of EHDs in membrane transport. Common effectors for these two protein families have been identified, and they facilitate regulation of sequential steps in transport. By comparing and contrasting key aspects in their modes of function, we shall promote a better understanding of how Rab proteins and EHDs regulate endocytic trafficking.
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Kitazawa D, Yamaguchi M, Mori H, Inoue YH. COPI-mediated membrane trafficking is required for cytokinesis in Drosophila male meiotic divisions. J Cell Sci 2012; 125:3649-60. [DOI: 10.1242/jcs.103317] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The coatomer protein complex, COPI, mediates retrograde vesicle transport from the Golgi apparatus to the ER. Here, we investigated the meiotic phenotype of Drosophila spermatocytes expressing dsRNA of 52 genes encoding membrane trafficking-related factors. We identified COPI as an essential factor for male meiosis. In Drosophila male meiotic divisions, COPI is localized in the ER-Golgi intermediate compartment of tER-Golgi units scattered throughout the spermatocyte cytoplasm. Prior to chromosome segregation, the vesicles assemble at the spindle pole periphery through a poleward movement, mediated by minus-ended motor dynein along astral microtubules. At the end of each meiotic division, COPI-containing vesicles are equally partitioned between 2 daughter cells. Our present data strongly suggest that spermatocytes possess a regulatory mechanism, to fulfill equal inheritance of several types of membrane vesicles. Using testis-specific knockdown of COPI subunits or small GTPase Arf, or mutations of the γCOP gene, we examined the role of COPI in male meiosis. COPI depletion resulted in the failure of cytokinesis, through disrupted accumulation of essential proteins and lipid components at the cleavage furrow region. Furthermore, it caused a reduction in the number of overlapping central spindle microtubules, which are essential for cytokinesis. Drosophila spermatocytes construct ER-based intracellular structures associated with astral and spindle microtubules. COPI depletion resulted in severe disruption of these ER-based structures. Thus, we propose that COPI plays an important role in Drosophila male meiosis, not only through vesicle transport to the cleavage furrow region, but also via the formation of ER-based structures.
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Tang BL. Membrane Trafficking Components in Cytokinesis. Cell Physiol Biochem 2012; 30:1097-108. [DOI: 10.1159/000343301] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/07/2012] [Indexed: 12/11/2022] Open
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