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Ikeda KN, Belevich I, Zelaya-Lainez L, Orel L, Füssl J, Gumulec J, Hellmich C, Jokitalo E, Raible F. Dynamic microvilli sculpt bristles at nanometric scale. Nat Commun 2024; 15:3733. [PMID: 38740737 DOI: 10.1038/s41467-024-48044-3] [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: 08/21/2023] [Accepted: 04/19/2024] [Indexed: 05/16/2024] Open
Abstract
Organisms generate shapes across size scales. Whereas patterning and morphogenesis of macroscopic tissues has been extensively studied, the principles underlying the formation of micrometric and submicrometric structures remain largely enigmatic. Individual cells of polychaete annelids, so-called chaetoblasts, are associated with the generation of chitinous bristles of highly stereotypic geometry. Here we show that bristle formation requires a chitin-producing enzyme specifically expressed in the chaetoblasts. Chaetoblasts exhibit dynamic cell surfaces with stereotypical patterns of actin-rich microvilli. These microvilli can be matched with internal and external structures of bristles reconstructed from serial block-face electron micrographs. Individual chitin teeth are deposited by microvilli in an extension-disassembly cycle resembling a biological 3D printer. Consistently, pharmacological interference with actin dynamics leads to defects in tooth formation. Our study reveals that both material and shape of bristles are encoded by the same cell, and that microvilli play a role in micro- to submicrometric sculpting of biomaterials.
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Affiliation(s)
- Kyojiro N Ikeda
- Max Perutz Labs; University of Vienna, 1030, Vienna, Austria.
| | - Ilya Belevich
- Institute of Biotechnology, Helsinki Institute of Life Science, University of Helsinki, Helsinki, Finland
| | - Luis Zelaya-Lainez
- Institute for Mechanics of Materials and Structures, TU Wien-Vienna University of Technology, Vienna, Austria
| | - Lukas Orel
- Max Perutz Labs; University of Vienna, 1030, Vienna, Austria
| | - Josef Füssl
- Institute for Mechanics of Materials and Structures, TU Wien-Vienna University of Technology, Vienna, Austria
| | - Jaromír Gumulec
- Department of Pathophysiology, Faculty of Medicine, Masaryk University, Brno, Czech Republic
| | - Christian Hellmich
- Institute for Mechanics of Materials and Structures, TU Wien-Vienna University of Technology, Vienna, Austria
| | - Eija Jokitalo
- Institute of Biotechnology, Helsinki Institute of Life Science, University of Helsinki, Helsinki, Finland
| | - Florian Raible
- Max Perutz Labs; University of Vienna, 1030, Vienna, Austria.
- Research Platform "Single-Cell Regulation of Stem Cells", University of Vienna, Vienna, Austria.
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2
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Meziu E, Shehu K, Koch M, Schneider M, Kraegeloh A. Impact of mucus modulation by N-acetylcysteine on nanoparticle toxicity. Int J Pharm X 2023; 6:100212. [PMID: 37771516 PMCID: PMC10522980 DOI: 10.1016/j.ijpx.2023.100212] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2023] [Revised: 09/14/2023] [Accepted: 09/17/2023] [Indexed: 09/30/2023] Open
Abstract
Human respiratory mucus is a biological hydrogel that forms a protective barrier for the underlying epithelium. Modulation of the mucus layer has been employed as a strategy to enhance transmucosal drug carrier transport. However, a drawback of this strategy is a potential reduction of the mucus barrier properties, in particular in situations with an increased exposure to particles. In this study, we investigated the impact of mucus modulation on its protective role. In vitro mucus was produced by Calu-3 cells, cultivated at the air-liquid interface for 21 days and used for further testing as formed on top of the cells. Analysis of confocal 3D imaging data revealed that after 21 days Calu-3 cells secrete a mucus layer with a thickness of 24 ± 6 μm. Mucus appeared to restrict penetration of 500 nm carboxyl-modified polystyrene particles to the upper 5-10 μm of the layer. Furthermore, a mucus modulation protocol using aerosolized N-acetylcysteine (NAC) was developed. This treatment enhanced the penetration of particles through the mucus down to deeper layers by means of the mucolytic action of NAC. These findings were supported by cytotoxicity data, indicating that intact mucus protects the underlying epithelium from particle-induced effects on membrane integrity. The impact of NAC treatment on the protective properties of mucus was probed by using 50 and 100 nm amine-modified and 50 nm carboxyl-modified polystyrene nanoparticles, respectively. Cytotoxicity was only induced by the amine-modified particles in combination with NAC treatment, implying a reduced protective function of modulated mucus. Overall, our data emphasize the importance of integrating an assessment of the protective function of mucus into the development of therapy approaches involving mucus modulation.
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Affiliation(s)
- Enkeleda Meziu
- INM – Leibniz Institute for New Materials, 66123 Saarbrücken, Germany
- Department of Pharmacy, Biopharmaceutics & Pharmaceutical Technology, Saarland University, 66123 Saarbrücken, Germany
| | - Kristela Shehu
- INM – Leibniz Institute for New Materials, 66123 Saarbrücken, Germany
- Department of Pharmacy, Biopharmaceutics & Pharmaceutical Technology, Saarland University, 66123 Saarbrücken, Germany
| | - Marcus Koch
- INM – Leibniz Institute for New Materials, 66123 Saarbrücken, Germany
| | - Marc Schneider
- Department of Pharmacy, Biopharmaceutics & Pharmaceutical Technology, Saarland University, 66123 Saarbrücken, Germany
| | - Annette Kraegeloh
- INM – Leibniz Institute for New Materials, 66123 Saarbrücken, Germany
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3
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Krishnan RK, Halachmi N, Baskar R, Bakhrat A, Zarivach R, Salzberg A, Abdu U. Revisiting the Role of ß-Tubulin in Drosophila Development: β-tubulin60D is not an Essential Gene, and its Novel Pin1 Allele has a Tissue-Specific Dominant-Negative Impact. Front Cell Dev Biol 2022; 9:787976. [PMID: 35111755 PMCID: PMC8802551 DOI: 10.3389/fcell.2021.787976] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Accepted: 12/09/2021] [Indexed: 11/19/2022] Open
Abstract
Diversity in cytoskeleton organization and function may be achieved through alternative tubulin isotypes and by a variety of post-translational modifications. The Drosophila genome contains five different β-tubulin paralogs, which may play an isotype tissue-specific function in vivo. One of these genes, the β-tubulin60D gene, which is expressed in a tissue-specific manner, was found to be essential for fly viability and fertility. To further understand the role of the β-tubulin60D gene, we generated new β-tubulin60D null alleles (β-tubulin60DM) using the CRISPR/Cas9 system and found that the homozygous flies were viable and fertile. Moreover, using a combination of genetic complementation tests, rescue experiments, and cell biology analyses, we identified Pin1, an unknown dominant mutant with bristle developmental defects, as a dominant-negative allele of β-tubulin60D. We also found a missense mutation in the Pin1 mutant that results in an amino acid replacement from the highly conserved glutamate at position 75 to lysine (E75K). Analyzing the ß-tubulin structure suggests that this E75K alteration destabilizes the alpha-helix structure and may also alter the GTP-Mg2+ complex binding capabilities. Our results revisited the credence that β-tubulin60D is required for fly viability and revealed for the first time in Drosophila, a novel dominant-negative function of missense β-tubulin60D mutation in bristle morphogenesis.
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Affiliation(s)
| | - Naomi Halachmi
- Department of Genetics and Developmental Biology, Rappaport Faculty of Medicine, Technion, Haifa, Israel
| | - Raju Baskar
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer’Sheva, Israel
| | - Anna Bakhrat
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer’Sheva, Israel
| | - Raz Zarivach
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer’Sheva, Israel
- National Institute for Biotechnology in the Negev and the Ilse Katz Institute for Nanoscale Science and Technology, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Adi Salzberg
- Department of Genetics and Developmental Biology, Rappaport Faculty of Medicine, Technion, Haifa, Israel
| | - Uri Abdu
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer’Sheva, Israel
- *Correspondence: Uri Abdu,
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4
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Liu YJ, Zhang T, Chen S, Cheng D, Wu C, Wang X, Duan D, Zhu L, Lou H, Gong Z, Wang XD, Ho MS, Duan S. The noncanonical role of the protease cathepsin D as a cofilin phosphatase. Cell Res 2021; 31:801-813. [PMID: 33514914 PMCID: PMC8249557 DOI: 10.1038/s41422-020-00454-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2020] [Accepted: 11/16/2020] [Indexed: 01/30/2023] Open
Abstract
Cathepsin D (cathD) is traditionally regarded as a lysosomal protease that degrades substrates in acidic compartments. Here we report cathD plays an unconventional role as a cofilin phosphatase orchestrating actin remodeling. In neutral pH environments, the cathD precursor directly dephosphorylates and activates the actin-severing protein cofilin independent of its proteolytic activity, whereas mature cathD degrades cofilin in acidic pH conditions. During development, cathD complements the canonical cofilin phosphatase slingshot and regulates the morphogenesis of actin-based structures. Moreover, suppression of cathD phosphatase activity leads to defective actin organization and cytokinesis failure. Our findings identify cathD as a dual-function molecule, whose functional switch is regulated by environmental pH and its maturation state, and reveal a novel regulatory role of cathD in actin-based cellular processes.
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Affiliation(s)
- Yi-Jun Liu
- grid.13402.340000 0004 1759 700XDepartment of Neurobiology and Department of Neurology of Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310009 China ,grid.13402.340000 0004 1759 700XResearch Units for Emotion and Emotion Disorders, NHC and CAMS Key Laboratory of Medical Neurobiology, MOE Frontier Science Center for Brain Research and Brain-Machine Integration, School of Brain Science and Brain Medicine, Zhejiang University, Hangzhou, Zhejiang 310058 China
| | - Ting Zhang
- grid.13402.340000 0004 1759 700XDepartment of Neurobiology and Department of Neurology of Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310009 China ,grid.13402.340000 0004 1759 700XResearch Units for Emotion and Emotion Disorders, NHC and CAMS Key Laboratory of Medical Neurobiology, MOE Frontier Science Center for Brain Research and Brain-Machine Integration, School of Brain Science and Brain Medicine, Zhejiang University, Hangzhou, Zhejiang 310058 China
| | - Sicong Chen
- grid.412465.0Clinical Research Center, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310009 China
| | - Daxiao Cheng
- grid.13402.340000 0004 1759 700XDepartment of Neurobiology and Department of Neurology of Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310009 China ,grid.13402.340000 0004 1759 700XResearch Units for Emotion and Emotion Disorders, NHC and CAMS Key Laboratory of Medical Neurobiology, MOE Frontier Science Center for Brain Research and Brain-Machine Integration, School of Brain Science and Brain Medicine, Zhejiang University, Hangzhou, Zhejiang 310058 China
| | - Cunjin Wu
- grid.13402.340000 0004 1759 700XResearch Units for Emotion and Emotion Disorders, NHC and CAMS Key Laboratory of Medical Neurobiology, MOE Frontier Science Center for Brain Research and Brain-Machine Integration, School of Brain Science and Brain Medicine, Zhejiang University, Hangzhou, Zhejiang 310058 China
| | - Xingyue Wang
- grid.13402.340000 0004 1759 700XDepartment of Neurobiology and Department of Neurology of Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310009 China ,grid.13402.340000 0004 1759 700XResearch Units for Emotion and Emotion Disorders, NHC and CAMS Key Laboratory of Medical Neurobiology, MOE Frontier Science Center for Brain Research and Brain-Machine Integration, School of Brain Science and Brain Medicine, Zhejiang University, Hangzhou, Zhejiang 310058 China
| | - Duo Duan
- grid.13402.340000 0004 1759 700XResearch Units for Emotion and Emotion Disorders, NHC and CAMS Key Laboratory of Medical Neurobiology, MOE Frontier Science Center for Brain Research and Brain-Machine Integration, School of Brain Science and Brain Medicine, Zhejiang University, Hangzhou, Zhejiang 310058 China
| | - Liya Zhu
- grid.13402.340000 0004 1759 700XDepartment of Neurobiology and Department of Neurology of Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310009 China ,grid.13402.340000 0004 1759 700XResearch Units for Emotion and Emotion Disorders, NHC and CAMS Key Laboratory of Medical Neurobiology, MOE Frontier Science Center for Brain Research and Brain-Machine Integration, School of Brain Science and Brain Medicine, Zhejiang University, Hangzhou, Zhejiang 310058 China
| | - Huifang Lou
- grid.13402.340000 0004 1759 700XDepartment of Neurobiology and Department of Neurology of Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310009 China ,grid.13402.340000 0004 1759 700XResearch Units for Emotion and Emotion Disorders, NHC and CAMS Key Laboratory of Medical Neurobiology, MOE Frontier Science Center for Brain Research and Brain-Machine Integration, School of Brain Science and Brain Medicine, Zhejiang University, Hangzhou, Zhejiang 310058 China
| | - Zhefeng Gong
- grid.13402.340000 0004 1759 700XResearch Units for Emotion and Emotion Disorders, NHC and CAMS Key Laboratory of Medical Neurobiology, MOE Frontier Science Center for Brain Research and Brain-Machine Integration, School of Brain Science and Brain Medicine, Zhejiang University, Hangzhou, Zhejiang 310058 China
| | - Xiao-Dong Wang
- grid.13402.340000 0004 1759 700XResearch Units for Emotion and Emotion Disorders, NHC and CAMS Key Laboratory of Medical Neurobiology, MOE Frontier Science Center for Brain Research and Brain-Machine Integration, School of Brain Science and Brain Medicine, Zhejiang University, Hangzhou, Zhejiang 310058 China ,grid.13402.340000 0004 1759 700XDepartment of Psychiatry, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310016 China
| | - Margaret S. Ho
- grid.440637.20000 0004 4657 8879School of Life Science and Technology, ShanghaiTech University, Shanghai, 201210 China
| | - Shumin Duan
- grid.13402.340000 0004 1759 700XDepartment of Neurobiology and Department of Neurology of Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310009 China ,grid.13402.340000 0004 1759 700XResearch Units for Emotion and Emotion Disorders, NHC and CAMS Key Laboratory of Medical Neurobiology, MOE Frontier Science Center for Brain Research and Brain-Machine Integration, School of Brain Science and Brain Medicine, Zhejiang University, Hangzhou, Zhejiang 310058 China
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5
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Raval MH, Quintero OA, Weck ML, Unrath WC, Gallagher JW, Cui R, Kachar B, Tyska MJ, Yengo CM. Impact of the Motor and Tail Domains of Class III Myosins on Regulating the Formation and Elongation of Actin Protrusions. J Biol Chem 2016; 291:22781-22792. [PMID: 27582493 PMCID: PMC5077211 DOI: 10.1074/jbc.m116.733741] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Revised: 08/29/2016] [Indexed: 11/06/2022] Open
Abstract
Class III myosins (MYO3A and MYO3B) are proposed to function as transporters as well as length and ultrastructure regulators within stable actin-based protrusions such as stereocilia and calycal processes. MYO3A differs from MYO3B in that it contains an extended tail domain with an additional actin-binding motif. We examined how the properties of the motor and tail domains of human class III myosins impact their ability to enhance the formation and elongation of actin protrusions. Direct examination of the motor and enzymatic properties of human MYO3A and MYO3B revealed that MYO3A is a 2-fold faster motor with enhanced ATPase activity and actin affinity. A chimera in which the MYO3A tail was fused to the MYO3B motor demonstrated that motor activity correlates with formation and elongation of actin protrusions. We demonstrate that removal of individual exons (30-34) in the MYO3A tail does not prevent filopodia tip localization but abolishes the ability to enhance actin protrusion formation and elongation in COS7 cells. Interestingly, our results demonstrate that MYO3A slows filopodia dynamics and enhances filopodia lifetime in COS7 cells. We also demonstrate that MYO3A is more efficient than MYO3B at increasing formation and elongation of stable microvilli on the surface of cultured epithelial cells. We propose that the unique features of MYO3A, enhanced motor activity, and an extended tail with tail actin-binding motif, allow it to play an important role in stable actin protrusion length and ultrastructure maintenance.
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Affiliation(s)
- Manmeet H Raval
- From the Department of Cellular and Molecular Physiology, Pennsylvania State University, College of Medicine, Hershey, Pennsylvania 17033
| | - Omar A Quintero
- the Department of Biology, University of Richmond, Richmond, Virginia 23173
| | - Meredith L Weck
- the Department of Cell and Developmental Biology, Vanderbilt University Medical Center, Nashville, Tennessee 37232
| | - William C Unrath
- From the Department of Cellular and Molecular Physiology, Pennsylvania State University, College of Medicine, Hershey, Pennsylvania 17033
| | - James W Gallagher
- the Department of Biology, Lincoln University, Philadelphia, Pennsylvania 19104, and
| | - Runjia Cui
- the Laboratory of Cell Structure and Dynamics, NIDCD, National Institutes of Health, Bethesda, Maryland 20892
| | - Bechara Kachar
- the Laboratory of Cell Structure and Dynamics, NIDCD, National Institutes of Health, Bethesda, Maryland 20892
| | - Matthew J Tyska
- the Department of Cell and Developmental Biology, Vanderbilt University Medical Center, Nashville, Tennessee 37232
| | - Christopher M Yengo
- From the Department of Cellular and Molecular Physiology, Pennsylvania State University, College of Medicine, Hershey, Pennsylvania 17033,
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6
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Sebé-Pedrós A, Burkhardt P, Sánchez-Pons N, Fairclough SR, Lang BF, King N, Ruiz-Trillo I. Insights into the origin of metazoan filopodia and microvilli. Mol Biol Evol 2013; 30:2013-23. [PMID: 23770652 PMCID: PMC3748353 DOI: 10.1093/molbev/mst110] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Filopodia are fine actin-based cellular projections used for both environmental sensing and cell motility, and they are essential organelles for metazoan cells. In this study, we reconstruct the origin of metazoan filopodia and microvilli. We first report on the evolutionary assembly of the filopodial molecular toolkit and show that homologs of many metazoan filopodial components, including fascin and myosin X, were already present in the unicellular or colonial progenitors of metazoans. Furthermore, we find that the actin crosslinking protein fascin localizes to filopodia-like structures and microvilli in the choanoflagellate Salpingoeca rosetta. In addition, homologs of filopodial genes in the holozoan Capsaspora owczarzaki are upregulated in filopodia-bearing cells relative to those that lack them. Therefore, our findings suggest that proteins essential for metazoan filopodia and microvilli are functionally conserved in unicellular and colonial holozoans and that the last common ancestor of metazoans bore a complex and specific filopodial machinery.
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Affiliation(s)
- Arnau Sebé-Pedrós
- Institut de Biologia Evolutiva (CSIC-Universitat Pompeu Fabra), Barcelona, Catalonia, Spain
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7
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Abstract
Abstract Chitin is the second most abundant polysaccharide on earth. It is produced at the apical side of epidermal, tracheal, fore-, and hindgut epithelial cells in insects as a central component of the protective and supporting extracellular cuticle. Chitin is also an important constituent of the midgut peritrophic matrix that encases the food supporting its digestion and protects the epithelium against invasion by possibly ingested pathogens. The enzyme producing chitin is a glycosyltransferase that resides in the apical plasma membrane forming a pore to extrude the chains of chitin into the extracellular space. The apical plasma membrane is not only a platform for chitin synthases but, probably through its shape and equipment with distinct factors, also plays an important role in orienting and organizing chitin fibers. Here, I review findings on the cellular and molecular constitution of the apical plasma membrane of chitin-producing epithelia mainly focusing on work done in the fruit fly Drosophila melanogaster.
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Affiliation(s)
- Bernard Moussian
- Animal Genetics, Interfaculty Institute for Cell Biology, University of Tübingen, 72076 Tübingen, Germany.
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8
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Bitan A, Rosenbaum I, Abdu U. Stable and dynamic microtubules coordinately determine and maintain Drosophila bristle shape. Development 2012; 139:1987-96. [PMID: 22513371 DOI: 10.1242/dev.076893] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Within interphase cells, microtubules (MTs) are organized in a cell-specific manner to support cell shape and function. Here, we report that coordination between stable and dynamic MTs determines and maintains the highly elongated bristle cell shape. By following MT-decorating hooks and by tracking EB1 we identified two MT populations within bristles: a stable MT population polarized with their minus ends distal to the cell body, and a dynamic MT population that exhibits mixed polarity. Manipulating MT dynamics by Klp10A downregulation demonstrates that MTs can initiate new shaft extensions and thus possess the ability to determine growth direction. Actin filament bundling subsequently supports the newly formed shaft extensions. Analysis of ik2 mutant bristles, established by elongation defects in the Drosophila ikkε homolog, led to the observation that stable and dynamic MT orientation and polarized organization are important for proper bristle elongation. Thus, we demonstrate for the first time that coordination between stable and dynamic MT sets that are axially organized yet differently polarized drives cell elongation.
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Affiliation(s)
- Amir Bitan
- Department of Life Sciences and the National Institute for Biotechnology in the Negev, Ben-Gurion University, Beer-Sheva 84105, Israel
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9
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Nagaraj R, Adler PN. Dusky-like functions as a Rab11 effector for the deposition of cuticle during Drosophila bristle development. Development 2012; 139:906-16. [PMID: 22278919 DOI: 10.1242/dev.074252] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The morphogenesis of Drosophila sensory bristles is dependent on the function of their actin and microtubule cytoskeleton. Actin filaments are important for bristle shape and elongation, while microtubules are thought to mediate protein and membrane trafficking to promote growth. We have identified an essential role for the bristle cuticle in the maintenance of bristle structure and shape at late stages of bristle development. We show that the small GTPase Rab11 mediates the organized deposition of chitin, a major cuticle component in bristles, and disrupting Rab11 function leads to phenotypes that result from bristle collapse rather than a failure to elongate. We further establish that Rab11 is required for the plasma membrane localization of the ZP domain-containing Dusky-like (Dyl) protein and that Dyl is also required for cuticle formation in bristles. Our data argue that Dyl functions as a Rab11 effector for mediating the attachment of the bristle cell membrane to chitin to establish a stable cuticle. Our studies also implicate the exocyst as a Rab11 effector in this process and that Rab11 trafficking along the bristle shaft is mediated by microtubules.
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Affiliation(s)
- Ranganayaki Nagaraj
- Biology Department, Cell Biology Department, Institute for Morphogenesis and Regenerative Medicine, University of Virginia, Charlottesville, VA 22903, USA
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10
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Abstract
We describe a molecularly defined duplication kit for the X chromosome of Drosophila melanogaster. A set of 408 overlapping P[acman] BAC clones was used to create small duplications (average length 88 kb) covering the 22-Mb sequenced portion of the chromosome. The BAC clones were inserted into an attP docking site on chromosome 3L using ΦC31 integrase, allowing direct comparison of different transgenes. The insertions complement 92% of the essential and viable mutations and deletions tested, demonstrating that almost all Drosophila genes are compact and that the current annotations of the genome are reasonably accurate. Moreover, almost all genes are tolerated at twice the normal dosage. Finally, we more precisely mapped two regions at which duplications cause diplo-lethality in males. This collection comprises the first molecularly defined duplication set to cover a whole chromosome in a multicellular organism. The work presented removes a long-standing barrier to genetic analysis of the Drosophila X chromosome, will greatly facilitate functional assays of X-linked genes in vivo, and provides a model for functional analyses of entire chromosomes in other species.
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11
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Bitan A, Guild GM, Bar-Dubin D, Abdu U. Asymmetric microtubule function is an essential requirement for polarized organization of the Drosophila bristle. Mol Cell Biol 2010; 30:496-507. [PMID: 19917727 PMCID: PMC2798467 DOI: 10.1128/mcb.00861-09] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2009] [Revised: 08/14/2009] [Accepted: 11/06/2009] [Indexed: 01/21/2023] Open
Abstract
While previous studies have shown that microtubules (MTs) are essential for maintaining the highly biased axial growth of the Drosophila bristle, the mechanism for this process has remained vague. We report that the MT minus-end marker, Nod-KHC, accumulates at the bristle tip, suggesting that the MT network in the bristle is organized minus end out. Potential markers for studying the importance of properly polarized MTs to bristle axial growth are Ik2 and Spindle-F (Spn-F), since mutations in spn-F and ik2 affect bristle development. We demonstrate that Spn-F and Ik2 are localized to the bristle tip and that mutations in ik2 and spn-F affect bristle MT and actin organization. Specifically, mutation in ik2 affects polarized bristle MT function. It was previously found that the hook mutant exhibited defects in bristle polarity and that hook is involved in endocytic trafficking. We found that Hook is localized at the bristle tip and that this localization is affected in ik2 mutants, suggesting that the contribution of MTs within the bristle shaft is important for correct endocytic trafficking. Thus, our results show that MTs are organized in a polarized manner within the highly elongated bristle and that this organization is essential for biased bristle axial growth.
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Affiliation(s)
- Amir Bitan
- Department of Life Sciences and National Institute for Biotechnology in the Negev, Ben-Gurion University, Beer-Sheva, Israel, Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Gregory M. Guild
- Department of Life Sciences and National Institute for Biotechnology in the Negev, Ben-Gurion University, Beer-Sheva, Israel, Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Dikla Bar-Dubin
- Department of Life Sciences and National Institute for Biotechnology in the Negev, Ben-Gurion University, Beer-Sheva, Israel, Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Uri Abdu
- Department of Life Sciences and National Institute for Biotechnology in the Negev, Ben-Gurion University, Beer-Sheva, Israel, Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania
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12
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Nemethova M, Auinger S, Small JV. Building the actin cytoskeleton: filopodia contribute to the construction of contractile bundles in the lamella. J Cell Biol 2008; 180:1233-44. [PMID: 18362182 PMCID: PMC2290848 DOI: 10.1083/jcb.200709134] [Citation(s) in RCA: 139] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2007] [Accepted: 02/27/2008] [Indexed: 01/09/2023] Open
Abstract
Filopodia are rodlike extensions generally attributed with a guidance role in cell migration. We now show in fish fibroblasts that filopodia play a major role in generating contractile bundles in the lamella region behind the migrating front. Filopodia that developed adhesion to the substrate via paxillin containing focal complexes contributed their proximal part to stress fiber assembly, and filopodia that folded laterally contributed to the construction of contractile bundles parallel to the cell edge. Correlated light and electron microscopy of cells labeled for actin and fascin confirmed integration of filopodia bundles into the lamella network. Inhibition of myosin II did not subdue the waving and folding motions of filopodia or their entry into the lamella, but filopodia were not then integrated into contractile arrays. Comparable results were obtained with B16 melanoma cells. These and other findings support the idea that filaments generated in filopodia and lamellipodia for protrusion are recycled for seeding actomyosin arrays for use in retraction.
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Affiliation(s)
- Maria Nemethova
- Institute of Molecular Biotechnology, Austrian Academy of Sciences, Vienna 1030, Austria
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13
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Applewhite DA, Barzik M, Kojima SI, Svitkina TM, Gertler FB, Borisy GG. Ena/VASP proteins have an anti-capping independent function in filopodia formation. Mol Biol Cell 2007; 18:2579-91. [PMID: 17475772 PMCID: PMC1924831 DOI: 10.1091/mbc.e06-11-0990] [Citation(s) in RCA: 164] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Filopodia have been implicated in a number of diverse cellular processes including growth-cone path finding, wound healing, and metastasis. The Ena/VASP family of proteins has emerged as key to filopodia formation but the exact mechanism for how they function has yet to be fully elucidated. Using cell spreading as a model system in combination with small interfering RNA depletion of Capping Protein, we determined that Ena/VASP proteins have a role beyond anticapping activity in filopodia formation. Analysis of mutant Ena/VASP proteins demonstrated that the entire EVH2 domain was the minimal domain required for filopodia formation. Fluorescent recovery after photobleaching data indicate that Ena/VASP proteins rapidly exchange at the leading edge of lamellipodia, whereas virtually no exchange occurred at filopodial tips. Mutation of the G-actin-binding motif (GAB) partially compromised stabilization of Ena/VASP at filopodia tips. These observations led us to propose a model where the EVH2 domain of Ena/VASP induces and maintains clustering of the barbed ends of actin filaments, which putatively corresponds to a transition from lamellipodial to filopodial localization. Furthermore, the EVH1 domain, together with the GAB motif in the EVH2 domain, helps to maintain Ena/VASP at the growing barbed ends.
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Affiliation(s)
- Derek A. Applewhite
- *Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611
| | - Melanie Barzik
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - Shin-ichiro Kojima
- *Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611
| | - Tatyana M. Svitkina
- Department of Biology, University of Pennsylvania, Philadelphia, PA 19104; and
| | - Frank B. Gertler
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - Gary G. Borisy
- *Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611
- Marine Biological Laboratory, Woods Hole, MA 02453
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Kachoei BA, Knox RJ, Uthuza D, Levy S, Kaczmarek LK, Magoski NS. A store-operated Ca(2+) influx pathway in the bag cell neurons of Aplysia. J Neurophysiol 2006; 96:2688-98. [PMID: 16885525 PMCID: PMC2894935 DOI: 10.1152/jn.00118.2006] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Although store-operated Ca(2+) influx has been well-studied in nonneuronal cells, an understanding of its nature in neurons remains poor. In the bag cell neurons of Aplysia californica, prior work has suggested that a Ca(2+) entry pathway can be activated by Ca(2+) store depletion. Using fura-based imaging of intracellular Ca(2+) in cultured bag cell neurons, we now characterize this pathway as store-operated Ca(2+) influx. In the absence of extracellular Ca(2+), the endoplasmic reticulum Ca(2+)-ATPase inhibitors, cyclopiazonic acid (CPA) or thapsigargin, depleted intracellular stores and elevated intracellular free Ca(2+). With the subsequent addition of extracellular Ca(2+), a prominent Ca(2+) influx was observed. The ryanodine receptor agonist, chloroethylphenol (CEP), also increased intracellular Ca(2+) but did not initiate store-operated Ca(2+) influx, despite overlap between CEP- and CPA-sensitive stores. Bafilomycin A, a vesicular H(+)-ATPase inhibitor, liberated intracellular Ca(2+) from acidic stores and attenuated subsequent Ca(2+) influx, presumably by replenishing CPA-depleted stores. Store-operated Ca(2+) influx was partially blocked by low concentrations of La(3+) or BTP2, and strongly inhibited by either 1-[b-[3-(4-methoxyphenyl)propoxy]-4-methoxyphenethyl]-1H-imidazole (SKF-96365) or a high concentration of Ni(2+). Regarding IP(3) receptor blockers, 2-aminoethyldiphenyl borate, but not xestospongin C, prevented store-operated Ca(2+) influx. However, jasplakinolide, an actin stabilizer reported to inhibit this pathway in smooth muscle cell lines, was ineffective. The bag cell neurons initiate reproductive behavior through a prolonged afterdischarge associated with intracellular Ca(2+) release and neuropeptide secretion. Store-operated Ca(2+) influx may serve to replenish stores depleted during the afterdischarge or participate in the release of peptide that triggers behavior.
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Affiliation(s)
- Babak A Kachoei
- Department of Physiology, Queen's University, 4th Floor, Botterell Hall, 18 Stuart St., Kingston, ON, K7L 3N6, Canada
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Tilney LG, DeRosier DJ. How to make a curved Drosophila bristle using straight actin bundles. Proc Natl Acad Sci U S A 2005; 102:18785-92. [PMID: 16357198 PMCID: PMC1323189 DOI: 10.1073/pnas.0509437102] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
This, our Inaugural Article as Academy Members, is ironically our swan song from the field of the actin cytoskeleton. By reviewing what we have learned and what we think is going on during development, we hope to lure you, the reader, into applying your skills to the bristle cell. The processes of the assembly and disassembly of actin bundles is laid out in time and space in an organism that lends itself to genetic manipulation. The cell provides every process you could want: filament nucleation, growth of microvilli, joining of microvillar bundles into modules, assembly of modules into bundles, time-dependent use of at least two crossbridging proteins, filament turnover, treadmilling, disassembly, and filament translocation.
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Affiliation(s)
- Lewis G Tilney
- Department of Biology, University of Pennsylvania, Philadelphia, PA 19104, USA
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Tilney LG, Connelly PS, Ruggiero L, Vranich KA, Guild GM, Derosier D. The role actin filaments play in providing the characteristic curved form of Drosophila bristles. Mol Biol Cell 2004; 15:5481-91. [PMID: 15371540 PMCID: PMC532027 DOI: 10.1091/mbc.e04-06-0472] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Drosophila bristles display a precise orientation and curvature. An asymmetric extension of the socket cell overlies the newly emerging bristle rudiment to provide direction for bristle elongation, a process thought to be orchestrated by the nerve dendrite lying between these cells. Scanning electron microscopic analysis of individual bristles showed that curvature is planar and far greater near the bristle base. Correlated with this, as development proceeds the pupa gradually recedes from the inner pupal case (an extracellular layer that encloses the pupa) leading to less bristle curvature along the shaft. We propose that the inner pupal case induces elongating bristles to bend when they contact this barrier. During elongation the actin cytoskeleton locks in this curvature by grafting together the overlapping modules that comprise the long filament bundles. Because the bristle is curved, the actin bundles on the superior side must be longer than those on the inferior side. This is accomplished during grafting by greater elongation of superior side modules. Poor actin cross-bridging in mutant bristles results in altered curvature. Thus, the pattern of bristle curvature is a product of both extrinsic factors-the socket cell and the inner pupal case--and intrinsic factors--actin cytoskeleton assembly.
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Affiliation(s)
- Lewis G Tilney
- Department of Biology, University of Pennsylvania, Philadelphia, PA 19104-6018, USA
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