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Wilson DW. Motor Skills: Recruitment of Kinesins, Myosins and Dynein during Assembly and Egress of Alphaherpesviruses. Viruses 2021; 13:v13081622. [PMID: 34452486 PMCID: PMC8402756 DOI: 10.3390/v13081622] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Revised: 08/11/2021] [Accepted: 08/13/2021] [Indexed: 12/14/2022] Open
Abstract
The alphaherpesviruses are pathogens of the mammalian nervous system. Initial infection is commonly at mucosal epithelia, followed by spread to, and establishment of latency in, the peripheral nervous system. During productive infection, viral gene expression, replication of the dsDNA genome, capsid assembly and genome packaging take place in the infected cell nucleus, after which mature nucleocapsids emerge into the cytoplasm. Capsids must then travel to their site of envelopment at cytoplasmic organelles, and enveloped virions need to reach the cell surface for release and spread. Transport at each of these steps requires movement of alphaherpesvirus particles through a crowded and viscous cytoplasm, and for distances ranging from several microns in epithelial cells, to millimeters or even meters during egress from neurons. To solve this challenging problem alphaherpesviruses, and their assembly intermediates, exploit microtubule- and actin-dependent cellular motors. This review focuses upon the mechanisms used by alphaherpesviruses to recruit kinesin, myosin and dynein motors during assembly and egress.
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Affiliation(s)
- Duncan W. Wilson
- Department of Developmental and Molecular Biology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA; ; Tel.: +1-718-430-2305
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA
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2
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Girón-Pérez DA, Piedra-Quintero ZL, Santos-Argumedo L. Class I myosins: Highly versatile proteins with specific functions in the immune system. J Leukoc Biol 2019; 105:973-981. [PMID: 30821871 DOI: 10.1002/jlb.1mr0918-350rrr] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2018] [Revised: 02/04/2019] [Accepted: 02/06/2019] [Indexed: 12/20/2022] Open
Abstract
Connections established between cytoskeleton and plasma membrane are essential in cellular processes such as cell migration, vesicular trafficking, and cytokinesis. Class I myosins are motor proteins linking the actin-cytoskeleton with membrane phospholipids. Previous studies have implicated these molecules in cell functions including endocytosis, exocytosis, release of extracellular vesicles and the regulation of cell shape and membrane elasticity. In immune cells, those proteins also are involved in the formation and maintenance of immunological synapse-related signaling. Thus, these proteins are master regulators of actin cytoskeleton dynamics in different scenarios. Although the localization of class I myosins has been described in vertebrates, their functions, regulation, and mechanical properties are not very well understood. In this review, we focused on and summarized the current understanding of class I myosins in vertebrates with particular emphasis in leukocytes.
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Affiliation(s)
- Daniel Alberto Girón-Pérez
- Departamento de Biomedicina Molecular, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Ciudad de México, México
| | - Zayda Lizbeth Piedra-Quintero
- Departamento de Biomedicina Molecular, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Ciudad de México, México
| | - Leopoldo Santos-Argumedo
- Departamento de Biomedicina Molecular, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Ciudad de México, México
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3
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Li YR, Yang WX. Myosin superfamily: The multi-functional and irreplaceable factors in spermatogenesis and testicular tumors. Gene 2015; 576:195-207. [PMID: 26478466 DOI: 10.1016/j.gene.2015.10.022] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Revised: 09/21/2015] [Accepted: 10/12/2015] [Indexed: 10/22/2022]
Abstract
Spermatogenesis is a fundamental process in sexual development and reproduction, in which the diploid spermatogonia transform into haploid mature spermatozoa. This process is under the regulation of multiple factors and pathway. Myosin has been implicated in various aspects during spermatogenesis. Myosins constitute a diverse superfamily of actin-based molecular motors that translocate along microfilament in an ATP-dependent manner, and six kinds of myosins have been proved that function during spermatogenesis. In mitosis and meiosis, myosins play an important role in spindle assembly and positioning, karyokinesis and cytokinesis. During spermiogenesis, myosins participate in acrosomal formation, nuclear morphogenesis, mitochondrial translocation and spermatid individualization. In this review, we summarize current understanding of the functions of myosin in spermatogenesis and some reproductive system diseases such as testicular tumors and prostate cancer, and discuss the roles of possible upstream molecules which regulate myosin in these processes.
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Affiliation(s)
- Yan-Ruide Li
- The Sperm Laboratory, College of Life Sciences, Zhejiang University, Hangzhou 310058, China
| | - Wan-Xi Yang
- The Sperm Laboratory, College of Life Sciences, Zhejiang University, Hangzhou 310058, China.
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4
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Lu Q, Li J, Zhang M. Cargo recognition and cargo-mediated regulation of unconventional myosins. Acc Chem Res 2014; 47:3061-70. [PMID: 25230296 DOI: 10.1021/ar500216z] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Organized motions are hallmarks of living organisms. Such motions range from collective cell movements during development and muscle contractions at the macroscopic scale all the way down to cellular cargo (e.g., various biomolecules and organelles) transportation and mechanoforce sensing at more microscopic scales. Energy required for these biological motions is almost invariably provided by cellular chemical fuels in the form of nucleotide triphosphate. Biological systems have designed a group of nanoscale engines, known as molecular motors, to convert cellular chemical fuels into mechanical energy. Molecular motors come in various forms including cytoskeleton motors (myosin, kinesin, and dynein), nucleic-acid-based motors, cellular membrane-based rotary motors, and so on. The main focus of this Account is one subfamily of actin filament-based motors called unconventional myosins (other than muscle myosin II, the remaining myosins are collectively referred to as unconventional myosins). In general, myosins can use ATP to fuel two types of mechanomotions: dynamic tethering actin filaments with various cellular compartments or structures and actin filament-based intracellular transport. In contrast to rich knowledge accumulated over many decades on ATP hydrolyzing motor heads and their interactions with actin filaments, how various myosins recognize their specific cargoes and whether and how cargoes can in return regulate functions of motors are less understood. Nonetheless, a series of biochemical and structural investigations in the past few years, including works from our own laboratory, begin to shed lights on these latter questions. Some myosins (e.g., myosin-VI) can function both as cellular transporters and as mechanical tethers. To function as a processive transporter, myosins need to form dimers or multimers. To be a mechanical tether, a monomeric myosin is sufficient. It has been shown for myosin-VI that its cellular cargo proteins can play critical roles in determining the motor properties. Dab2, an adaptor protein linking endocytic vesicles with actin-filament-bound myosin-VI, can induce the motor to form a transport competent dimer. Such a cargo-mediated dimerization mechanism has also been observed in other myosins including myosin-V and myosin-VIIa. The tail domains of myosins are very diverse both in their lengths and protein domain compositions and thus enable motors to engage a broad range of different cellular cargoes. Remarkably, the cargo binding tail of one myosin alone often can bind to multiple distinct target proteins. A series of atomic structures of myosin-V/cargo complexes solved recently reveals that the globular cargo binding tail of the motor contains a number of nonoverlapping target recognition sites for binding to its cargoes including melanophilin, vesicle adaptors RILPL2, and vesicle-bound GTPase Rab11. The structures of the MyTH4-FERM tandems from myosin-VIIa and myosin-X in complex with their respective targets reveal that MyTH4 and FERM domains extensively interact with each other forming structural and functional supramodules in both motors and demonstrate that the structurally similar MyTH4-FERM tandems of the two motors display totally different target binding modes. These structural studies have also shed light on why numerous mutations found in these myosins can cause devastating human diseases such as deafness and blindness, intellectual disabilities, immune disorders, and diabetes.
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Affiliation(s)
- Qing Lu
- Division
of Life Science, State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong China
| | - Jianchao Li
- Division
of Life Science, State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong China
| | - Mingjie Zhang
- Division
of Life Science, State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong China
- Center of Systems Biology and Human Health, School of
Science and Institute for Advanced Study, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong China
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Nie J, Mahato S, Zelhof AC. The actomyosin machinery is required for Drosophila retinal lumen formation. PLoS Genet 2014; 10:e1004608. [PMID: 25233220 PMCID: PMC4168998 DOI: 10.1371/journal.pgen.1004608] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2014] [Accepted: 07/15/2014] [Indexed: 12/13/2022] Open
Abstract
Multicellular tubes consist of polarized cells wrapped around a central lumen and are essential structures underlying many developmental and physiological functions. In Drosophila compound eyes, each ommatidium forms a luminal matrix, the inter-rhabdomeral space, to shape and separate the key phototransduction organelles, the rhabdomeres, for proper visual perception. In an enhancer screen to define mechanisms of retina lumen formation, we identified Actin5C as a key molecule. Our results demonstrate that the disruption of lumen formation upon the reduction of Actin5C is not linked to any discernible defect in microvillus formation, the rhabdomere terminal web (RTW), or the overall morphogenesis and basal extension of the rhabdomere. Second, the failure of proper lumen formation is not the result of previously identified processes of retinal lumen formation: Prominin localization, expansion of the apical membrane, or secretion of the luminal matrix. Rather, the phenotype observed with Actin5C is phenocopied upon the decrease of the individual components of non-muscle myosin II (MyoII) and its upstream activators. In photoreceptor cells MyoII localizes to the base of the rhabdomeres, overlapping with the actin filaments of the RTW. Consistent with the well-established roll of actomyosin-mediated cellular contraction, reduction of MyoII results in reduced distance between apical membranes as measured by a decrease in lumen diameter. Together, our results indicate the actomyosin machinery coordinates with the localization of apical membrane components and the secretion of an extracellular matrix to overcome apical membrane adhesion to initiate and expand the retinal lumen. Biological tubes are integral units of tissues and organs such as lung, kidney, and the cardiovascular system. The fundamental design of tubes involves a central lumen wrapped by a sheet of cells. To function properly, the tubes require a precise genetic control over their creation, the diametric growth and maintenance of the lumen during development. In the fruit fly, Drosophila melanogaster, the photoreceptor cells of the eye form a tubular structure. The formation of the retinal lumen is critical for separating and positioning the light sensing organelles of each photoreceptor cell to achieve visual sensitivity. In an effort to investigate the mechanisms of Drosophila retinal lumen formation, we identified a contractile machinery that was present at the apical portion of photoreceptor cells. Our data is consistent with the idea that a contractile force contributes to the initial separation of the juxtaposed apical membranes and subsequent enlargement of the luminal space. Our work suggests that building a biological tube requires not only an extrinsic pushing force provided by the growing central lumen, but also a cell intrinsic pulling force powered by contraction of cells lining the lumen. Our findings expand and demonstrate the coordination of several molecular mechanisms to generate a tube.
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Affiliation(s)
- Jing Nie
- Department of Biology, Indiana University, Bloomington, Indiana, United States of America
| | - Simpla Mahato
- Department of Biology, Indiana University, Bloomington, Indiana, United States of America
| | - Andrew C. Zelhof
- Department of Biology, Indiana University, Bloomington, Indiana, United States of America
- * E-mail:
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6
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Brzeska H, Guag J, Preston GM, Titus MA, Korn ED. Molecular basis of dynamic relocalization of Dictyostelium myosin IB. J Biol Chem 2012; 287:14923-36. [PMID: 22367211 DOI: 10.1074/jbc.m111.318667] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Class I myosins have a single heavy chain comprising an N-terminal motor domain with actin-activated ATPase activity and a C-terminal globular tail with a basic region that binds to acidic phospholipids. These myosins contribute to the formation of actin-rich protrusions such as pseudopodia, but regulation of the dynamic localization to these structures is not understood. Previously, we found that Acanthamoeba myosin IC binds to acidic phospholipids in vitro through a short sequence of basic and hydrophobic amino acids, BH site, based on the charge density of the phospholipids. The tail of Dictyostelium myosin IB (DMIB) also contains a BH site. We now report that the BH site is essential for DMIB binding to the plasma membrane and describe the molecular basis of the dynamic relocalization of DMIB in live cells. Endogenous DMIB is localized uniformly on the plasma membrane of resting cells, at active protrusions and cell-cell contacts of randomly moving cells, and at the front of motile polarized cells. The BH site is required for association of DMIB with the plasma membrane at all stages where it colocalizes with phosphoinositide bisphosphate/phosphoinositide trisphosphate (PIP(2)/PIP(3)). The charge-based specificity of the BH site allows for in vivo specificity of DMIB for PIP(2)/PIP(3) similar to the PH domain-based specificity of other class I myosins. However, DMIB-head is required for relocalization of DMIB to the front of migrating cells. Motor activity is not essential, but the actin binding site in the head is important. Thus, dynamic relocalization of DMIB is determined principally by the local PIP(2)/PIP(3) concentration in the plasma membrane and cytoplasmic F-actin.
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Affiliation(s)
- Hanna Brzeska
- Laboratory of Cell Biology, NHLBI, National Institutes of Health, Bethesda, Maryland 20892, USA.
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7
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Syamaladevi DP, Spudich JA, Sowdhamini R. Structural and functional insights on the Myosin superfamily. Bioinform Biol Insights 2012; 6:11-21. [PMID: 22399849 PMCID: PMC3290112 DOI: 10.4137/bbi.s8451] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
The myosin superfamily is a versatile group of molecular motors involved in the transport of specific biomolecules, vesicles and organelles in eukaryotic cells. The processivity of myosins along an actin filament and transport of intracellular ‘cargo’ are achieved by generating physical force from chemical energy of ATP followed by appropriate conformational changes. The typical myosin has a head domain, which harbors an ATP binding site, an actin binding site, and a light-chain bound ‘lever arm’, followed often by a coiled coil domain and a cargo binding domain. Evolution of myosins started at the point of evolution of eukaryotes, S. cerevisiae being the simplest one known to contain these molecular motors. The coiled coil domain of the myosin classes II, V and VI in whole genomes of several model organisms display differences in the length and the strength of interactions at the coiled coil interface. Myosin II sequences have long-length coiled coil regions that are predicted to have a highly stable dimeric interface. These are interrupted, however, by regions that are predicted to be unstable, indicating possibilities of alternate conformations, associations to make thick filaments, and interactions with other molecules. Myosin V sequences retain intermittent regions of strong and weak interactions, whereas myosin VI sequences are relatively devoid of strong coiled coil motifs. Structural deviations at coiled coil regions could be important for carrying out normal biological function of these proteins.
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Affiliation(s)
- Divya P Syamaladevi
- National Centre for Biological Sciences (NCBS-TIFR), GKVK Campus, Bellary Road, Bangalore, India
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8
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Hartman MA, Finan D, Sivaramakrishnan S, Spudich JA. Principles of unconventional myosin function and targeting. Annu Rev Cell Dev Biol 2011; 27:133-55. [PMID: 21639800 DOI: 10.1146/annurev-cellbio-100809-151502] [Citation(s) in RCA: 130] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Unconventional myosins are a superfamily of actin-based motors implicated in diverse cellular processes. In recent years, much progress has been made in describing their biophysical properties, and headway has been made into analyzing their cellular functions. Here, we focus on the principles that guide in vivo motor function and targeting to specific cellular locations. Rather than describe each motor comprehensively, we outline the major themes that emerge from research across the superfamily and use specific examples to illustrate each. In presenting the data in this format, we seek to identify open questions in each field as well as to point out commonalities between them. To advance our understanding of myosins' roles in vivo, clearly we must identify their cellular cargoes and the protein complexes that regulate motor attachment to fully appreciate their functions on the cellular and developmental levels.
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Affiliation(s)
- M Amanda Hartman
- Department of Biochemistry, Stanford University, Stanford, California 94305, USA
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9
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A mutation in Myo15 leads to Usher-like symptoms in LEW/Ztm-ci2 rats. PLoS One 2011; 6:e15669. [PMID: 21479269 PMCID: PMC3066203 DOI: 10.1371/journal.pone.0015669] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2010] [Accepted: 11/22/2010] [Indexed: 02/02/2023] Open
Abstract
The LEW/Ztm-ci2 rat is an animal model for syndromal deafness that arose from a spontaneous mutation. Homozygous animals show locomotor abnormalities like lateralized circling behavior. Additionally, an impaired vision can be observed in some animals through behavioral studies. Syndromal deafness as well as retinal degeneration are features of the Usher syndrome in humans. In the present study, the mutation was identified as a base substitution (T->C) in exon 56 of Myo15, leading to an amino acid exchange from leucine (Leu) to proline (Pro) within the carboxy-terminal MyTH4 domain in the proteins' tail region. Myo15 mRNA was expressed in the retina as demonstrated for the first time with the help of in-situ hybridization and PCR. To characterize the visual phenotype, rats were examined by scotopic and photopic electroretinography and, additionally, histological analyses of the retinas were conducted. The complete loss of sight was detected along with a severe degeneration of photoreceptor cells. Interestingly, the manifestation of the disease does not solely depend on the mutation, but also on environmental factors. Since the LEW/Ztm-ci2 rat features the entire range of symptoms of the human Usher syndrome we think that this strain is an appropriate model for this disease. Our findings display that mutations in binding domains of myosin XV do not only cause non-syndromic hearing loss but can also lead to syndromic disorders including retinal dysfunction.
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Sun X, Kovacs T, Hu YJ, Yang WX. The role of actin and myosin during spermatogenesis. Mol Biol Rep 2010; 38:3993-4001. [DOI: 10.1007/s11033-010-0517-0] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2010] [Accepted: 11/13/2010] [Indexed: 01/08/2023]
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Spitznagel D, O'Rourke JF, Leddy N, Hanrahan O, Nolan DP. Identification and characterization of an unusual class I myosin involved in vesicle traffic in Trypanosoma brucei. PLoS One 2010; 5:e12282. [PMID: 20808867 PMCID: PMC2924389 DOI: 10.1371/journal.pone.0012282] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2010] [Accepted: 07/16/2010] [Indexed: 01/19/2023] Open
Abstract
Myosins are a multimember family of motor proteins with diverse functions in eukaryotic cells. African trypanosomes possess only two candidate myosins and thus represent a useful system for functional analysis of these motors. One of these candidates is an unusual class I myosin (TbMyo1) that is expressed at similar levels but organized differently during the life cycle of Trypanosoma brucei. This myosin localizes to the polarized endocytic pathway in bloodstream forms of the parasite. This organization is actin dependent. Knock down of TbMyo1 results in a significant reduction in endocytic activity, a cessation in cell division and eventually cell death. A striking morphological feature in these cells is an enlargement of the flagellar pocket, which is consistent with an imbalance in traffic to and from the surface. In contrast TbMyo1 is distributed throughout procyclic forms of the tsetse vector and a loss of ∼90% of the protein has no obvious effects on growth or morphology. These results reveal a life cycle stage specific requirement for this myosin in essential endocytic traffic and represent the first description of the involvement of a motor protein in vesicle traffic in these parasites.
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Affiliation(s)
- Diana Spitznagel
- Molecular Parasitology Group, School of Biochemistry and Immunology, Trinity College Dublin, Dublin, Ireland
| | - John F. O'Rourke
- European Bioinformatics Institute, Wellcome Trust Genome Campus, Hinxton, United Kingdom
| | - Neal Leddy
- Centre for Microscopy and Analysis, Trinity College Dublin, Dublin, Ireland
| | - Orla Hanrahan
- Molecular Parasitology Group, School of Biochemistry and Immunology, Trinity College Dublin, Dublin, Ireland
| | - Derek P. Nolan
- Molecular Parasitology Group, School of Biochemistry and Immunology, Trinity College Dublin, Dublin, Ireland
- * E-mail:
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12
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Unconventional myosin traffic in cells reveals a selective actin cytoskeleton. Proc Natl Acad Sci U S A 2009; 106:9685-90. [PMID: 19478066 DOI: 10.1073/pnas.0810451106] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Eukaryotic cells have a self-organizing cytoskeleton where motors transport cargoes along cytoskeletal tracks. To understand the sorting process, we developed a system to observe single-molecule motility in a cellular context. We followed myosin classes V, VI, and X on triton-extracted actin cytoskeletons from Drosophila S2, mammalian COS-7, and mammalian U2OS cells. We find that these cells vary considerably in their global traffic patterns. The S2 and U2OS cells have regions of actin that either enhance or inhibit specific myosin classes. U2OS cells allow for 1 motor class, myosin VI, to move along stress fiber bundles, while motility of myosin V and X are suppressed. Myosin X motors are recruited to filopodia and the lamellar edge in S2 cells, whereas myosin VI motility is excluded from the same regions. Furthermore, we also see different velocities of myosin V motors in central regions of S2 cells, suggesting regional control of motor motility by the actin cytoskeleton. We also find unexpected features of the actin cytoskeletal network, including a population of reversed filaments with the barbed-end toward the cell center. This myosin motor regulation demonstrates that native actin cytoskeletons are more than just a collection of filaments.
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Abstract
Transport of cargo by molecular motors on microtubule and actin filament tracks is a fundamental property of eukaryotic cells. A new study reports that actin dynamics are required in cells for myosin I and V motor proteins to transport their organelle cargos on actin tracks.
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Affiliation(s)
- Louise Cramer
- MRC-Laboratory Molecular Cell Biology/Cell Biology Unit and Department of Cell and Developmental Biology, University College London, Gower St, London WC1E 6BT, UK.
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Semenova I, Burakov A, Berardone N, Zaliapin I, Slepchenko B, Svitkina T, Kashina A, Rodionov V. Actin dynamics is essential for myosin-based transport of membrane organelles. Curr Biol 2008; 18:1581-6. [PMID: 18951026 DOI: 10.1016/j.cub.2008.08.070] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2008] [Revised: 08/25/2008] [Accepted: 08/26/2008] [Indexed: 01/11/2023]
Abstract
Actin filaments that serve as "rails" for the myosin-based transport of membrane organelles [1-4] continuously turn over by concurrent growth and shortening at the opposite ends [5]. Although it is known that dynamics of actin filaments is essential for many of the actin cytoskeleton functions, the role of such dynamics in myosin-mediated organelle transport was never studied before. Here, we addressed the role of turnover of actin filaments in the myosin-based transport of membrane organelles by treating cells with the drugs that suppress actin-filament dynamics and found that such a suppression significantly inhibited organelle transport along the actin filaments without inhibiting their intracellular distribution or the activity of the myosin motors. We conclude that dynamics of actin filaments is essential for myosin-based transport of membrane organelles and suggest a previously unknown role of actin-filament dynamics in providing the "rails" for continuous organelle movement resulting in the increased distances traveled by membrane organelles along the actin filaments.
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Affiliation(s)
- Irina Semenova
- Department of Cell Biology and Center for Cell Analysis and Modeling, University of Connecticut Health Center, Farmington, Connecticut 06032-1507, USA
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15
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Semenova I, Ikeda K, Ivanov P, Rodionov V. The protein kinase A-anchoring protein moesin is bound to pigment granules in melanophores. Traffic 2008; 10:153-60. [PMID: 18980611 DOI: 10.1111/j.1600-0854.2008.00852.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Major signaling cascades have been shown to play a role in the regulation of intracellular transport of organelles. In Xenopus melanophores, aggregation and dispersion of pigment granules are regulated by the second messenger cyclic AMP through the protein kinase A (PKA) signaling pathway. PKA is bound to pigment granules where it forms complexes with molecular motors involved in pigment transport. Association of PKA with pigment granules occurs through binding to A-kinase-anchoring proteins (AKAPs), whose identity remains largely unknown. In this study, we used mass spectrometry to examine an 80 kDa AKAP detected in preparations of purified pigment granules. We found that tryptic digests of granule protein fractions enriched in the 80 kDa AKAP contained peptides that corresponded to the actin-binding protein moesin, which has been shown to function as an AKAP in mammalian cells. We also found that recombinant Xenopus moesin interacted with PKA in vitro, copurified with pigment granules and bound to pigment granules in cells. Overexpression in melanophores of a mutant moesin lacking conserved PKA-binding domain did not affect aggregation of pigment granules but partially inhibited their dispersion. We conclude that Xenopus moesin is an AKAP whose PKA-scaffolding activity plays a role in the regulation of pigment dispersion in Xenopus melanophores.
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Affiliation(s)
- Irina Semenova
- Department of Cell Biology and Center for Cell Analysis and Modeling, University of Connecticut Health Center, Farmington, CT 06032-1507, USA
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16
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Takagi Y, Yang Y, Fujiwara I, Jacobs D, Cheney RE, Sellers JR, Kovács M. Human myosin Vc is a low duty ratio, nonprocessive molecular motor. J Biol Chem 2008; 283:8527-37. [PMID: 18201966 DOI: 10.1074/jbc.m709150200] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Myosin Vc is the product of one of the three genes of the class V myosin found in vertebrates. It is widely found in secretory and glandular tissues, with a possible involvement in transferrin trafficking. Transient and steady-state kinetic studies of human myosin Vc were performed using a truncated, single-headed construct. Steady-state actin-activated ATPase measurements revealed a V(max) of 1.8 +/- 0.3 s(-1) and a K(ATPase) of 43 +/- 11 microm. Unlike previously studied vertebrate myosin Vs, the rate-limiting step in the actomyosin Vc ATPase pathway is the release of inorganic phosphate (~1.5 s(-1)), rather than the ADP release step (~12.0-16.0 s(-1)). Nevertheless, the ADP affinity of actomyosin Vc (K(d) = 0.25 +/- 0.02 microm) reflects a higher ADP affinity than seen in other myosin V isoforms. Using the measured kinetic rates, the calculated duty ratio of myosin Vc was approximately 10%, indicating that myosin Vc spends the majority of the actomyosin ATPase cycle in weak actin-binding states, unlike the other vertebrate myosin V isoforms. Consistent with this, a fluorescently labeled double-headed heavy meromyosin form showed no processive movements along actin filaments in a single molecule assay, but it did move actin filaments at a velocity of approximately 24 nm/s in ensemble assays. Kinetic simulations reveal that the high ADP affinity of actomyosin Vc may lead to elevations of the duty ratio of myosin Vc to as high as 64% under possible physiological ADP concentrations. This, in turn, may possibly imply a regulatory mechanism that may be sensitive to moderate changes in ADP concentration.
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Affiliation(s)
- Yasuharu Takagi
- Laboratory of Molecular Physiology, NHLBI, NIH, Bethesda, MD 20892-8015, USA
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Sittaramane V, Chandrasekhar A. Expression of unconventional myosin genes during neuronal development in zebrafish. Gene Expr Patterns 2007; 8:161-70. [PMID: 18078791 DOI: 10.1016/j.gep.2007.10.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2007] [Revised: 10/27/2007] [Accepted: 10/30/2007] [Indexed: 12/12/2022]
Abstract
Neuronal migration and growth cone motility are essential aspects of the development and maturation of the nervous system. These cellular events result from dynamic changes in the organization and function of the cytoskeleton, in part due to the activity of cytoskeletal motor proteins such as myosins. Although specific myosins such as Myo2 (conventional or muscle myosin), Myo1, and Myo5 have been well characterized for roles in cell motility, the roles of the majority of unconventional (other than Myo2) myosins in cell motility events have not been investigated. To address this issue, we have undertaken an analysis of unconventional myosins in zebrafish, a premier model for studying cellular and growth cone motility in the vertebrate nervous system. We describe the characterization and expression patterns of several members of the unconventional myosin gene family. Based on available genomic sequence data, we identified 18 unconventional myosin- and 4 Myo2-related genes in the zebrafish genome in addition to previously characterized myosin (1, 2, 3, 5, 6, 7) genes. Phylogenetic analyses indicate that these genes can be grouped into existing classifications for unconventional myosins from mouse and man. In situ hybridization analyses using EST probes for 18 of the 22 identified genes indicate that 11/18 genes are expressed in a restricted fashion in the zebrafish embryo. Specific myosins are expressed in particular neuronal or neuroepithelial cell types in the developing zebrafish nervous system, spanning the periods of neuronal differentiation and migration, and of growth cone guidance and motility.
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Affiliation(s)
- Vinoth Sittaramane
- Division of Biological Sciences, University of Missouri, Columbia, MO 65211-7310, USA
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18
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Bhaskar L, Krishnan VS, Thampan RV. Cytoskeletal elements and intracellular transport. J Cell Biochem 2007; 101:1097-108. [PMID: 17471536 DOI: 10.1002/jcb.21347] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Recent advances in the understanding of the functions of various components of the cytoskeleton indicate that, besides serving a structural role, the cytoskeletal elements may regulate the transport of several proteins in the cell. Studies reveal that there are co-operative interactions between the actin and microtubule cytoskeletons including functional overlap in the transport influenced by different motor families. Multiple motors are probably involved in the control of the dynamics of many proteins and intriguing hints about how these motors are co-ordinated are appearing. It has been shown that some of the intermediate elements also participate in selected intracellular transport mechanisms. In view of the author's preoccupation with the steroid receptor systems, special attention has been given to the role of the cytoskeletal elements, particularly actin, in the intracellular transport of steroid receptors and receptor-related proteins.
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Affiliation(s)
- Lakshmi Bhaskar
- Department of Industrial Microbiology, Govt. College for Women, Vazhuthacaud, Trivandrum 695014, Kerala, India
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19
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Morriswood B, Ryzhakov G, Puri C, Arden SD, Roberts R, Dendrou C, Kendrick-Jones J, Buss F. T6BP and NDP52 are myosin VI binding partners with potential roles in cytokine signalling and cell adhesion. J Cell Sci 2007; 120:2574-85. [PMID: 17635994 PMCID: PMC2621013 DOI: 10.1242/jcs.007005] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Myosin VI has been implicated in many cellular processes including endocytosis, secretion, membrane ruffling and cell motility. We carried out a yeast two-hybrid screen and identified TRAF6-binding protein (T6BP) and nuclear dot protein 52 (NDP52) as myosin VI binding partners. Myosin VI interaction with T6BP and NDP52 was confirmed in vitro and in vivo and the binding sites on each protein were accurately mapped. Immunofluorescence and electron microscopy showed that T6BP, NDP52 and myosin VI are present at the trans side of the Golgi complex, and on vesicles in the perinuclear region. Although the SKICH domain in T6BP and NDP52 does not mediate recruitment into membrane ruffles, loss of T6BP and NDP52 in RNAi knockdown cells results in reduced membrane ruffling activity and increased stress fibre and focal adhesion formation. Furthermore, we observed in these knockdown cells an upregulation of constitutive secretion of alkaline phosphatase, implying that both proteins act as negative regulators of secretory traffic at the Golgi complex. T6BP was also found to inhibit NF-kappaB activation, implicating it in the regulation of TRAF6-mediated cytokine signalling. Thus myosin VI-T6BP interactions may link membrane trafficking pathways with cell adhesion and cytokine-dependent cell signalling.
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Affiliation(s)
- Brooke Morriswood
- MRC Laboratory of Molecular Biology, Hills Road, Cambridge, CB2 2QH, UK
| | - Grigory Ryzhakov
- MRC Laboratory of Molecular Biology, Hills Road, Cambridge, CB2 2QH, UK
| | - Claudia Puri
- Cambridge Institute for Medical Research, University of Cambridge, Wellcome Trust/MRC Building, Hills Road, Cambridge, CB2 2XY, UK
| | - Susan D. Arden
- Cambridge Institute for Medical Research, University of Cambridge, Wellcome Trust/MRC Building, Hills Road, Cambridge, CB2 2XY, UK
| | - Rhys Roberts
- MRC Laboratory of Molecular Biology, Hills Road, Cambridge, CB2 2QH, UK
| | - Calliope Dendrou
- Cambridge Institute for Medical Research, University of Cambridge, Wellcome Trust/MRC Building, Hills Road, Cambridge, CB2 2XY, UK
| | - John Kendrick-Jones
- MRC Laboratory of Molecular Biology, Hills Road, Cambridge, CB2 2QH, UK
- Author for correspondence (e-mail: )
| | - Folma Buss
- Cambridge Institute for Medical Research, University of Cambridge, Wellcome Trust/MRC Building, Hills Road, Cambridge, CB2 2XY, UK
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20
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Watanabe TM, Sato T, Gonda K, Higuchi H. Three-dimensional nanometry of vesicle transport in living cells using dual-focus imaging optics. Biochem Biophys Res Commun 2007; 359:1-7. [PMID: 17512495 DOI: 10.1016/j.bbrc.2007.04.168] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2007] [Accepted: 04/25/2007] [Indexed: 11/17/2022]
Abstract
Dual-focus imaging optics for three-dimensional tracking of individual quantum dots has been developed to study the molecular mechanisms of motor proteins in cells. The new system has a high spatial and temporal precision, 2 nm in the x-y sample plane and 5 nm along the z-axis at a frame time of 2 ms. Three-dimensional positions of the vesicles labeled with quantum dots were detected in living cells. Vesicles were transported on the microtubules using 8-nm steps towards the nucleus. The steps had fluctuation of approximately 20 nm which were perpendicular to the axis of the microtubule but with the constant distance from the microtubule. The most of perpendicular movement was not synchronized with the 8-nm steps, indicating that dynein moved on microtubules without changing the protofilaments. When the vesicles changed their direction of movement toward the cell membrane, they moved perpendicular with the constant distance from the microtubule. The present method is powerful tool to investigate three dimensional movement of molecules in cells with nanometer and millisecond accuracy.
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Affiliation(s)
- Tomonobu M Watanabe
- Biomedical and Engineering Research Organization, Tohoku University, Sendai, Miyagi 980-8579, Japan
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21
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Watanabe TM, Higuchi H. Stepwise movements in vesicle transport of HER2 by motor proteins in living cells. Biophys J 2007; 92:4109-20. [PMID: 17369416 PMCID: PMC1868978 DOI: 10.1529/biophysj.106.094649] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The stepwise movements generated by myosin, dynein, and kinesin were observed in living cells in an attempt to understand the molecular mechanisms of movement within cells. First, the sequential process of the transport of vesicles, including human epidermal factor 2 receptor, after endocytosis was observed for long periods in three dimensions using quantum dots (QDs) and a three-dimensional confocal microscope. QD vesicles, after being endocytosed into the cells, moved along the membrane by transferring actin filaments and were then rapidly transported toward the nucleus along microtubules. Second, the position of vesicles was detected with a precision up to 1.9 nm and 330 micros using a new two-dimensional tracking method. The movement of the QDs transported by myosin VI lying just beneath the cell membrane consisted of 29- and 15-nm steps with a transition phase between these two steps. QD vesicles were then transported toward the nucleus or away from the nucleus toward the cell membrane with successive 8-nm steps. The stepwise movements of these motor proteins in cells were observed using new imaging methods that allowed the molecular mechanisms underlying traffic to and from the membrane to be determined.
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Affiliation(s)
- Tomonobu M Watanabe
- Biomedical and Engineering Research Organization, Tohoku University, Sendai, Japan
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22
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Rey M, Valenzuela-Fernández A, Urzainqui A, Yáñez-Mó M, Pérez-Martínez M, Penela P, Mayor F, Sánchez-Madrid F. Myosin IIA is involved in the endocytosis of CXCR4 induced by SDF-1alpha. J Cell Sci 2007; 120:1126-33. [PMID: 17327270 DOI: 10.1242/jcs.03415] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Endocytosis of chemokine receptors regulates signal transduction initiated by chemokines, but the molecular mechanisms underlying this process are not fully defined. In this work, we assessed the involvement of the motor protein nonmuscle myosin heavy chain IIA (MIIA) in the endocytosis of CXCR4 induced by SDF-1alpha (also known as CXCL12) in T lymphocytes. Overexpression of the C-terminal half of MIIA inhibited the ligand-induced endocytosis of CXCR4, but not that of transferrin receptor. Targeting MIIA either by silencing its expression with small interfering RNA (siRNA) or by blebbistatin treatment also inhibited endocytosis of CXCR4. Inhibition of endocytosis of CXCR4 by targeting endogenous MIIA resulted in an increased migration of T cells induced by SDF-1alpha, and in the inhibition of the HIV-1-Env antifusogenic activity of this chemokine. Coimmunoprecipitation and protein-protein binding studies demonstrated that MIIA interacts with both the cytoplasmic tail of CXCR4 and beta-arrestin. Moreover, SDF-1alpha promotes a rapid MIIA-beta-arrestin dissociation. Our data reveal a novel role for MIIA in CXCR4 endocytosis, which involves its dynamic association with beta-arrestin and highlights the role of endogenous MIIA as a regulator of CXCR4 internalization and, therefore, the onset of SDF-1alpha signaling.
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Affiliation(s)
- Mercedes Rey
- Servicio de Inmunología, Hospital Universitario de la Princesa, Diego de León, 62, 28006 Madrid, Spain
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23
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D'Souza VM, Bareford LM, Ray A, Swaan PW. Cytoskeletal scaffolds regulate riboflavin endocytosis and recycling in placental trophoblasts. J Nutr Biochem 2006; 17:821-9. [PMID: 16563724 DOI: 10.1016/j.jnutbio.2006.01.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2005] [Revised: 01/19/2006] [Accepted: 01/21/2006] [Indexed: 12/25/2022]
Abstract
Microfilaments and microtubules (MT) play a vital role in cellular endocytic processes. The present study evaluates the role of these cytoskeletal elements in the apical internalization and postendocytic fate of riboflavin (RF) in placental trophoblasts (BeWo cells). Biochemical modification of the actin and microtubule network by (1) okadaic acid (OA), which disrupts MT-based vesicular trafficking; (2) cytochalasin D and latrunculin B, which promote actin depolymerization; and (3) 2,3-butanedione monoxime (BDM), which inhibits myosin-actin interaction, was confirmed by immunofluorescence microscopy using actin- and tubulin-specific antibodies. Furthermore, involvement of the molecular motors dynein and kinesin was assessed in the presence of (1) sodium orthovanadate, which inhibits dynein-ATPase activity and (2) adenosine 5'-(beta,gamma-imido)triphosphate tetralithium salt hydrate, a non-hydrolyzable ATP analog, which results in defective kinesin-driven processes. RF internalization consequent to cytoskeletal alterations was compared with that of a clathrin-dependent endocytic marker ([125I]-transferrin [TF]), a caveolae-mediated endocytic substrate ([3H]-folic acid [FA]), and a fluid-phase endocytic marker ([125I]-horse radish peroxidase [HRP]). Apical recycling and bidirectional transport of RF and TF was measured following cytoskeletal alterations. Results indicate that uptake of RF, TF, FA and HRP are markedly reduced (approximately 30-65%) in the presence OA and BDM, suggesting differential sensitivities to modification of kinesin-driven microtubules. However, actin depolymerization negatively affected HRP endocytosis alone, while RF, FA and TF internalization remained unchanged. Disturbances in protein phosphorylation cascades also influenced apical recycling while net ligand transport across monolayers remained unaffected. In conclusion, apical RF trafficking in placental cells is tightly regulated by microtubules and supported by accessory actin involvement.
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Affiliation(s)
- Vanessa M D'Souza
- Department of Pharmaceutical Sciences, University of Maryland, Baltimore, MD 21201, USA
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24
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O'Connell CB, Tyska MJ, Mooseker MS. Myosin at work: motor adaptations for a variety of cellular functions. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2006; 1773:615-30. [PMID: 16904206 DOI: 10.1016/j.bbamcr.2006.06.012] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2006] [Revised: 05/22/2006] [Accepted: 06/30/2006] [Indexed: 12/30/2022]
Abstract
Cells have evolved multiple mechanisms to overcome the effects of entropy and diffusion to create a highly ordered environment. For cells to function properly, some components must be anchored to provide a framework or structure. Others must be rapidly transported over long distances to generate asymmetries in cell morphology and composition. To accomplish long-range transport, cells cannot rely on diffusion alone as many large organelles and macromolecular complexes are essentially immobilized by the dense meshwork of the cytosol. One strategy used by cells to overcome diffusion is to harness the free energy liberated by ATP hydrolysis through molecular motors. Myosins are a family of actin based molecular motors that have evolved a variety of ways to contribute to cellular organization through numerous modifications to the manner they convert that free energy into mechanical work.
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25
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Abstract
Non-syndromic deafness is a paradigm of genetic heterogeneity with 85 loci and 39 nuclear disease genes reported so far. Autosomal-recessive genes are responsible for about 80% of the cases of hereditary non-syndromic deafness of pre-lingual onset with 23 different genes identified to date. In the present article, we review these 23 genes, their function, and their contribution to genetic deafness in different populations. The wide range of functions of these DFNB genes reflects the heterogeneity of the genes involved in hearing and hearing loss. Several of these genes are involved in both recessive and dominant deafness, or in both non-syndromic and syndromic deafness. Mutations in the GJB2 gene encoding connexin 26 are responsible for as much as 50% of pre-lingual, recessive deafness. By contrast, mutations in most of the other DFNB genes have so far been detected in only a small number of families, and their contribution to deafness on a population scale might therefore be limited. Identification of all genes involved in hereditary hearing loss will help in our understanding of the basic mechanisms underlying normal hearing, in early diagnosis and therapy.
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Affiliation(s)
- M B Petersen
- Department of Genetics, Institute of Child Health, Aghia Sophia Children's Hospital, Athens, Greece.
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26
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Major RJ, Irvine KD. Localization and requirement for Myosin II at the dorsal-ventral compartment boundary of theDrosophila wing. Dev Dyn 2006; 235:3051-8. [PMID: 17013876 DOI: 10.1002/dvdy.20966] [Citation(s) in RCA: 105] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
As organisms develop, their tissues can become separated into distinct cell populations through the establishment of compartment boundaries. Compartment boundaries have been discovered in a wide variety of tissues, but in many cases the molecular mechanisms that separate cells remain poorly understood. In the Drosophila wing, a stripe of Notch activation maintains the dorsal-ventral compartment boundary, through a process that depends on the actin cytoskeleton. Here, we show that the dorsal-ventral boundary exhibits a distinct accumulation of Myosin II, and that this accumulation is regulated downstream of Notch signaling. Conversely, the dorsal-ventral boundary is depleted for the Par-3 homologue Bazooka. We further show that mutations in the Myosin heavy chain subunit encoded by zipper can impair dorsal-ventral compartmentalization without affecting anterior-posterior compartmentalization. These observations identify a distinct accumulation and requirement for Myosin activity in dorsal-ventral compartmentalization, and suggest a novel mechanism in which contractile tension along an F-actin cable at the compartment boundary contributes to compartmentalization.
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Affiliation(s)
- Robert J Major
- Howard Hughes Medical Institute, Waksman Institute, and Department of Molecular Biology and Biochemistry, Rutgers The State University of New Jersey, Piscataway, New Jersey, USA
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27
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Abstract
Small GTPases of the Rab family control timing of vesicle fusion. Fusion of two vesicles can only occur when they have been brought into close contact. Transport by microtubule- or actin-based motor proteins will facilitate this process in vivo. Ideally, transport and vesicle fusion are linked activities. Active, GTP-bound Rab proteins dock on specific compartments and are therefore perfect candidates to control transport of the different compartments. Recently, a number of Rab proteins were identified that control motor protein recruitment to their specific target membranes. By cycling through inactive and active states, Rab proteins are able to control motor protein-mediated transport and subsequent fusion of intracellular structures in both spatial and timed manners.
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Affiliation(s)
- Ingrid Jordens
- Department of Tumor Biology, Netherlands Cancer Institute, Amsterdam, Netherlands
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28
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Steimle PA, Fulcher FK, Patel YM. A novel role for myosin II in insulin-stimulated glucose uptake in 3T3-L1 adipocytes. Biochem Biophys Res Commun 2005; 331:1560-5. [PMID: 15883051 DOI: 10.1016/j.bbrc.2005.04.082] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2005] [Indexed: 11/25/2022]
Abstract
Insulin-stimulated glucose uptake requires the activation of several signaling pathways to mediate the translocation and fusion of GLUT4 vesicles from an intracellular pool to the plasma membrane. The studies presented here show that inhibition of myosin II activity impairs GLUT4-mediated glucose uptake but not GLUT4 translocation to the plasma membrane. We also show that adipocytes express both myosin IIA and IIB isoforms, and that myosin IIA is recruited to the plasma membrane upon insulin stimulation. Taken together, the data presented here represent the first demonstration that GLUT4-mediated glucose uptake is a myosin II-dependent process in adipocytes. Based on our findings, we hypothesize that myosin II is activated upon insulin stimulation and recruited to the cell cortex to facilitate GLUT4 fusion with the plasma membrane. The identification of myosin II as a key component of GLUT4-mediated glucose uptake represents an important advance in our understanding of the mechanisms regulating glucose homeostasis.
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Affiliation(s)
- Paul A Steimle
- Department of Biology, University of North Carolina at Greensboro, Greensboro, NC 27402, USA
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29
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Dance AL, Miller M, Seragaki S, Aryal P, White B, Aschenbrenner L, Hasson T. Regulation of myosin-VI targeting to endocytic compartments. Traffic 2005; 5:798-813. [PMID: 15355515 DOI: 10.1111/j.1600-0854.2004.00224.x] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Myosin-VI has been implicated in endocytic trafficking at both the clathrin-coated and uncoated vesicle stages. The identification of alternative splice forms led to the suggestion that splicing defines the vesicle type to which myosin-VI is recruited. In contrast to this hypothesis, we find that in all cell types examined, myosin-VI is associated with uncoated endocytic vesicles, regardless of splice form. GIPC, a PDZ-domain containing adapter protein, co-assembles with myosin-VI on these vesicles. Myosin-VI is only recruited to clathrin-coated vesicles in cells that express high levels of Dab2, a clathrin-binding adapter protein. Overexpression of Dab2 is sufficient to reroute myosin-VI to clathrin-coated pits in cells where myosin-VI is normally associated with uncoated vesicles. In normal rat kidney (NRK) cells, which express high endogenous levels of Dab2, splicing of the globular tail domain further modulates targeting of ectopically expressed myosin-VI. Although myosin-VI can be recruited to clathrin-coated pits, we find no requirement for myosin-VI motor activity in endocytosis in NRK cells. Instead, our data suggest that myosin-VI recruitment to clathrin-coated pits may be an early step in the recruitment of GIPC to the vesicle surface.
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Affiliation(s)
- Amber L Dance
- Section of Cell and Developmental Biology, Division of Biological Sciences, University of California at San Diego, La Jolla, CA 92093, USA
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30
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Hosein RE, Williams SA, Gavin RH. Directed motility of phagosomes inTetrahymena thermophila requires actin and Myo1p, a novel unconventional myosin. ACTA ACUST UNITED AC 2005; 61:49-60. [PMID: 15810016 DOI: 10.1002/cm.20065] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The phagosome cycle was investigated in Tetrahymena thermophila, which had internalized fluorescent latex beads. Confocal microscopy of cells from a GFP-actin strain revealed actin filaments that extended 3-5 mum from the periphery of fluorescent phagosomes. In GFP-actin cells and in wild-type cells, motility of fluorescent phagosomes was directed from the oral cavity to the posterior end of the cell. Although 60% of fluorescent phagosomes in the MYO1-knockout strain were motile, movement of phagosomes was not directed toward the posterior end of the cell and was random. Forty percent of fluorescent phagosomes in knockout cells were non-motile in contrast to only 20% non-motile phagosomes in wild-type cells. The increased incidence of non-motile phagosomes in the knockout strain could reflect absence of Myo1p as a motor. Another myosin or other molecular motors could power random movement of phagosomes in the MYO1-knockout strain. In latrunculin-treated GFP-actin cells, movement of fluorescent phagosomes was random. Average velocity of random movement of fluorescent phagosomes in the knockout strain and in latrunculin-treated cells was statistically the same as the average velocity (2.0 +/- 1.9 microm/min) of phagosomes in GFP-actin cells. These findings are an indication that dynamic actin and Myo1p are required for directed motility of phagosomes.
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Affiliation(s)
- Roland E Hosein
- Department of Biology, Brooklyn College of the City University of New York, Brooklyn, New York 11210, USA
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31
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Abstract
Melanosomes are lysosome-related organelles within which melanin pigment is synthesized. The molecular motors that allow these organelles to move within melanocytes have been the subject of intense study in several organisms. In mammals, melanosomes travel bi-directionally along microtubule tracks. The anterograde movement, i.e., towards microtubule plus-ends at the periphery, is accomplished by proteins of the kinesin superfamily, whereas the retrograde movement, i.e., towards microtubule minus-ends at the cell center, is achieved by dynein and dynein-associated proteins. At the periphery, melanosomes interact with the actin cytoskeleton via a tripartite complex formed by the small GTPase Rab27a, melanophilin and myosin Va, an actin-based motor. This interaction is essential for the maintenance of a dispersed state of the melanosomes, as shown by the perinuclear clustering of organelles in mutants in any of the referred proteins. In the retinal pigment epithelium, a similar complex formed by Rab27a, a melanophilin homolog called MyRIP and myosin VIIa is probably responsible for the tethering of melanosomes to the actin cytoskeleton. The coordination of motor activities is still poorly characterized, although some models have emerged in recent years and are discussed here. Unraveling regulatory mechanisms responsible for melanosome motility in pigmented cells will provide general insights into organelles dynamics within eukaryotic cells.
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Affiliation(s)
- Duarte C Barral
- Division of Biomedical Sciences, Faculty of Medicine, Imperial College London, London, UK
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32
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Allen ML, Handler AM, Berkebile DR, Skoda SR. piggyBac transformation of the New World screwworm, Cochliomyia hominivorax, produces multiple distinct mutant strains. MEDICAL AND VETERINARY ENTOMOLOGY 2004; 18:1-9. [PMID: 15009439 DOI: 10.1111/j.1365-2915.2004.0473.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Sterile insect technique (SIT) programs are designed to eradicate pest species by releasing mass-reared, sterile insects into an infested area. The first major implementation of SIT was the New World Screwworm Eradication Program, which successfully eliminated the New World screwworm (NWS), Cochliomyia hominivorax (Coquerel) (Diptera: Calliphoridae), from the Continental US, Mexico and much of Central America. Ionizing radiation is currently used for sterilization, but transgenic insect techniques could replace this method, providing a safer, more cost-effective alternative. Genetic transformation methods have been demonstrated in NWS, and verified by Southern blot hybridization, PCR and sequencing of element insertion junctions. A lethal insertional mutation and enhancer detection-like phenotypic expression variations are presented and discussed. In addition to supporting the eradication efforts, transformation methods offer potential means to identify genes and examine gene function in NWS.
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Affiliation(s)
- M L Allen
- Midwest Livestock Insects Laboratory, US Department of Agriculture, Lincoln, NE 68583, USA.
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33
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Rodionov V, Yi J, Kashina A, Oladipo A, Gross SP. Switching between microtubule- and actin-based transport systems in melanophores is controlled by cAMP levels. Curr Biol 2004; 13:1837-47. [PMID: 14588239 DOI: 10.1016/j.cub.2003.10.027] [Citation(s) in RCA: 97] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BACKGROUND Intracellular transport involves the movement of organelles along microtubules (MTs) or actin filaments (AFs) by means of opposite-polarity MT motors or actin-dependent motors of the myosin family. The correct delivery of organelles to their different destinations involves a precise coordination of the two transport systems. Such coordination could occur through regulation of the densities of the two cytoskeletal systems or through regulation of the activities of the cytoskeletal motors by signaling mechanisms. RESULTS To investigate the mechanisms of switching between MT and AF-dependent transport, we examine the influence of the densities of the MT and AF network on pigment transport in fish melanophores. We also change signaling by using activators and inhibitors of Protein Kinase A (PKA). We find that the key parameters characterizing pigment granule transport along MTs do not depend on MT density and are not significantly altered by complete disruption of AFs. In contrast, the kinetics of changes in these parameters correlate with the kinetics of changes in the intracellular levels of cAMP and are affected by the inhibitors of PKA, suggesting the regulation of MT- and AF-dependent motors by cAMP-induced signaling. Furthermore, perturbation of cAMP levels prevents the transfer of pigment granules from MTs onto AFs. CONCLUSIONS We conclude that the switching of pigment granules between the two major cytoskeletal systems is independent of the densities of MT or AF but is tightly controlled by signaling events.
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Affiliation(s)
- Vladimir Rodionov
- University of Connecticut Health Center, Department of Physiology and Center for Biomedical Imaging Technology, Farmington 06032-1507, USA
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34
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Togo T, Steinhardt RA. Nonmuscle myosin IIA and IIB have distinct functions in the exocytosis-dependent process of cell membrane repair. Mol Biol Cell 2003; 15:688-95. [PMID: 14617807 PMCID: PMC329289 DOI: 10.1091/mbc.e03-06-0430] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Vesicle generation, recruitment, and exocytosis are essential for repairing disruptions of cell membranes. The functions of nonmuscle myosin IIA and IIB in this exocytotic process of membrane repair were studied by the antisense technique. Knockdown of myosin IIB suppressed wound-induced exocytosis and the membrane resealing process. Knockdown of myosin IIA did not suppress exocytosis at an initial wound and had no inhibitory effect on the resealing at initial wounds but did inhibit the facilitated rate of resealing normally found at repeated wounds made at the same site. COS-7 cells, which lack myosin IIA, did not show the facilitated response of membrane resealing to a repeated wound. S91 melanoma cells, a mutant cell line lacking myosin Va, showed normal membrane resealing and normal facilitated responses. We concluded that myosin IIB was required for exocytosis and therefore cell membrane repair itself and that myosin IIA was required in facilitation of cell membrane repair at repeated wounds. Myosin IIB was primarily at the subplasmalemma cortex and myosin IIA was concentrated at the trans-Golgi network consistent with their distinct roles in vesicle trafficking in cell membrane repair.
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Affiliation(s)
- Tatsuru Togo
- Misaki Marine Biological Station, University of Tokyo, Misaki, Miura, Kanagawa 238-0225, Japan
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35
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Abstract
Actin is found at the cortex of the cell where endocytosis occurs, but does it play a role in this essential process? Recent studies on the unconventional myosin, myosin VI, an actin-based molecular motor, provide compelling evidence that this myosin and therefore actin is involved in two distinct steps of endocytosis in higher eukaryotes: the formation of clathrin-coated vesicles and the movement of nascent uncoated vesicles from the actin-rich cell periphery to the early endosome. Three distinct adapter proteins--GIPC, Dab2 and SAP97--that associate with the cargo-binding tail domain of myosin VI have been identified. These proteins may recruit myosin VI to its sites of action.
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Affiliation(s)
- Tama Hasson
- Division of Biological Sciences, Section of Cell and Developmental Biology, University of California at San Diego, 2129 Bonner Hall, MC 0368, 9500 Gilman Drive, La Jolla, CA 92093-0368, USA.
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36
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Donaudy F, Ferrara A, Esposito L, Hertzano R, Ben-David O, Bell RE, Melchionda S, Zelante L, Avraham KB, Gasparini P. Multiple mutations of MYO1A, a cochlear-expressed gene, in sensorineural hearing loss. Am J Hum Genet 2003; 72:1571-7. [PMID: 12736868 PMCID: PMC1180318 DOI: 10.1086/375654] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2003] [Accepted: 03/31/2003] [Indexed: 11/03/2022] Open
Abstract
Myosin I isozymes have been implicated in various motile processes, including organelle translocation, ion-channel gating, and cytoskeleton reorganization. Unconventional myosins were among the first family of proteins found to be associated with hearing loss in both humans and mice. Here, we report the identification of a nonsense mutation, of a trinucleotide insertion leading to an addition of an amino acid, and of six missense mutations in MYO1A cDNA sequence in a group of hearing-impaired patients from Italy. MYO1A, which is located within the DFNA48 locus, is the first myosin I family member found to be involved in causing deafness and may be a major contributor to autosomal dominant-hearing loss.
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Affiliation(s)
- Francesca Donaudy
- Telethon Institute of Genetics and Medicine and Genetica Medica, Dipartimento di Patologia Generale, Seconda Università di Napoli, Naples, Italy; Department of Human Genetics and Molecular Medicine, Sackler School of Medicine, and Department of Biochemistry, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv; and Servizio Genetica Medica, Istituto di Ricovero e Cura a Carattere Scientifico-Ospedale “Casa Sollievo della Sofferenza,” San Giovanni Rotondo, Italy
| | - Antonella Ferrara
- Telethon Institute of Genetics and Medicine and Genetica Medica, Dipartimento di Patologia Generale, Seconda Università di Napoli, Naples, Italy; Department of Human Genetics and Molecular Medicine, Sackler School of Medicine, and Department of Biochemistry, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv; and Servizio Genetica Medica, Istituto di Ricovero e Cura a Carattere Scientifico-Ospedale “Casa Sollievo della Sofferenza,” San Giovanni Rotondo, Italy
| | - Laura Esposito
- Telethon Institute of Genetics and Medicine and Genetica Medica, Dipartimento di Patologia Generale, Seconda Università di Napoli, Naples, Italy; Department of Human Genetics and Molecular Medicine, Sackler School of Medicine, and Department of Biochemistry, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv; and Servizio Genetica Medica, Istituto di Ricovero e Cura a Carattere Scientifico-Ospedale “Casa Sollievo della Sofferenza,” San Giovanni Rotondo, Italy
| | - Ronna Hertzano
- Telethon Institute of Genetics and Medicine and Genetica Medica, Dipartimento di Patologia Generale, Seconda Università di Napoli, Naples, Italy; Department of Human Genetics and Molecular Medicine, Sackler School of Medicine, and Department of Biochemistry, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv; and Servizio Genetica Medica, Istituto di Ricovero e Cura a Carattere Scientifico-Ospedale “Casa Sollievo della Sofferenza,” San Giovanni Rotondo, Italy
| | - Orit Ben-David
- Telethon Institute of Genetics and Medicine and Genetica Medica, Dipartimento di Patologia Generale, Seconda Università di Napoli, Naples, Italy; Department of Human Genetics and Molecular Medicine, Sackler School of Medicine, and Department of Biochemistry, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv; and Servizio Genetica Medica, Istituto di Ricovero e Cura a Carattere Scientifico-Ospedale “Casa Sollievo della Sofferenza,” San Giovanni Rotondo, Italy
| | - Rachel E. Bell
- Telethon Institute of Genetics and Medicine and Genetica Medica, Dipartimento di Patologia Generale, Seconda Università di Napoli, Naples, Italy; Department of Human Genetics and Molecular Medicine, Sackler School of Medicine, and Department of Biochemistry, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv; and Servizio Genetica Medica, Istituto di Ricovero e Cura a Carattere Scientifico-Ospedale “Casa Sollievo della Sofferenza,” San Giovanni Rotondo, Italy
| | - Salvatore Melchionda
- Telethon Institute of Genetics and Medicine and Genetica Medica, Dipartimento di Patologia Generale, Seconda Università di Napoli, Naples, Italy; Department of Human Genetics and Molecular Medicine, Sackler School of Medicine, and Department of Biochemistry, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv; and Servizio Genetica Medica, Istituto di Ricovero e Cura a Carattere Scientifico-Ospedale “Casa Sollievo della Sofferenza,” San Giovanni Rotondo, Italy
| | - Leopoldo Zelante
- Telethon Institute of Genetics and Medicine and Genetica Medica, Dipartimento di Patologia Generale, Seconda Università di Napoli, Naples, Italy; Department of Human Genetics and Molecular Medicine, Sackler School of Medicine, and Department of Biochemistry, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv; and Servizio Genetica Medica, Istituto di Ricovero e Cura a Carattere Scientifico-Ospedale “Casa Sollievo della Sofferenza,” San Giovanni Rotondo, Italy
| | - Karen B. Avraham
- Telethon Institute of Genetics and Medicine and Genetica Medica, Dipartimento di Patologia Generale, Seconda Università di Napoli, Naples, Italy; Department of Human Genetics and Molecular Medicine, Sackler School of Medicine, and Department of Biochemistry, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv; and Servizio Genetica Medica, Istituto di Ricovero e Cura a Carattere Scientifico-Ospedale “Casa Sollievo della Sofferenza,” San Giovanni Rotondo, Italy
| | - Paolo Gasparini
- Telethon Institute of Genetics and Medicine and Genetica Medica, Dipartimento di Patologia Generale, Seconda Università di Napoli, Naples, Italy; Department of Human Genetics and Molecular Medicine, Sackler School of Medicine, and Department of Biochemistry, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv; and Servizio Genetica Medica, Istituto di Ricovero e Cura a Carattere Scientifico-Ospedale “Casa Sollievo della Sofferenza,” San Giovanni Rotondo, Italy
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37
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Mundy DI, Machleidt T, Ying YS, Anderson RGW, Bloom GS. Dual control of caveolar membrane traffic by microtubules and the actin cytoskeleton. J Cell Sci 2002; 115:4327-39. [PMID: 12376564 DOI: 10.1242/jcs.00117] [Citation(s) in RCA: 241] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Live cell, time-lapse microscopy was used to study trafficking of caveolin-1-GFP in stably expressing CHO cells. Multiple cytological and biochemical tests verified that caveolin-1-GFP was a reliable marker for endogenous caveolin-1. At steady state, most caveolin-1-GFP was either at the cell surface associated with invaginated caveolae or near the centrosome in caveosomes. Live cell fluorescence imaging indicated that while much of the caveolin-1-GFP in caveolae at the cell surface was relatively sessile, numerous, highly motile caveolin-1-GFP-positive vesicles were present within the cell interior. These vesicles moved at speeds ranging from 0.3-2 microm/second and movement was abolished when microtubules were depolymerized with nocodazole. In the absence of microtubules, cell surface invaginated caveolae increased more than twofold and they became organized into linear arrays. Complete depolymerization of the actin cytoskeleton with latrunculin A, by contrast, triggered rapid and massive movements of caveolin-positive structures towards the centrosomal region of the cell. The caveolar membrane system of CHO cells therefore appears to be comprised of three caveolin-1-containing compartments. These include caveolae that are confined to the cell surface by cortical actin filaments, the peri-centrosomal caveosomes and caveolar vesicles, which we call 'cavicles', that move constitutively and bi-directionally along microtubules between the cell surface and caveosomes. The behavior of cavicles suggests that they function as transport intermediates between caveolae and caveosomes.
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Affiliation(s)
- Dorothy I Mundy
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9039, USA.
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38
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Cox D, Berg JS, Cammer M, Chinegwundoh JO, Dale BM, Cheney RE, Greenberg S. Myosin X is a downstream effector of PI(3)K during phagocytosis. Nat Cell Biol 2002; 4:469-77. [PMID: 12055636 DOI: 10.1038/ncb805] [Citation(s) in RCA: 181] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Phagocytosis is a phosphatidylinositol-3-OH-kinase (PI(3)K)-dependent process in macrophages. We identified Myo10 (Myosin-X), an unconventional myosin with pleckstrin homology (PH) domains, as a potential downstream target of PI(3)K. Myo10 was recruited to phagocytic cups in a wortmannin-sensitive manner. Expression of a truncation construct of Myo10 (Myo10 tail) in a macrophage cell line or cytosolic loading of anti-Myo10 antibodies in bovine alveolar macrophages inhibited phagocytosis. In contrast, expression of a Myo10 tail construct containing a point mutation in one of its PH domains failed to inhibit phagocytosis. Expression of Myo10 tail inhibited spreading, but not adhesion, on IgG-coated substrates, consistent with a function for Myo10 in pseudopod extension. We propose that Myo10 provides a molecular link between PI(3)K and pseudopod extension during phagocytosis.
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Affiliation(s)
- Dianne Cox
- Department of Medicine, Columbia University, 630 West 168th Street, New York, NY 10032, USA
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39
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Teng FYH, Tang BL. Neuritogenesis: polarization of constitutive exocytosis by effectors of Rho-family GTPases? Biochem Biophys Res Commun 2002; 294:923-5. [PMID: 12074564 DOI: 10.1016/s0006-291x(02)00609-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The sprouting of neurites from a neuron represents a highly specialized form of cellular morphogenesis that must involve coordinated changes in two major cellular processes at two membrane locations: reorganization of the cytoskeleton and redirection of membrane traffic from the trans-Golgi network to the plasma membrane of the growth tip. How exactly are these two processes linked and how is spatial and temporal coordination achieved at the first instance of neurite sprouting? Recent advances may have already revealed some, if not most of the pieces in the puzzle. We discuss below, with some extrapolations, of what has recently come to light, and what more is needed to construct a coherent picture.
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Affiliation(s)
- Felicia Y H Teng
- NCA lab, Institute of Molecular and Cell Biology, 30 Medical Drive, Singapore 117609, Singapore
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40
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Rodriguez OC, Cheney RE. Human myosin-Vc is a novel class V myosin expressed in epithelial cells. J Cell Sci 2002; 115:991-1004. [PMID: 11870218 DOI: 10.1242/jcs.115.5.991] [Citation(s) in RCA: 128] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Class V myosins are one of the most ancient and widely distributed groups of the myosin superfamily and are hypothesized to function as motors for actin-dependent organelle transport. We report the discovery and initial characterization of a novel member of this family, human myosin-Vc (Myo5c). The Myo5c protein sequence shares ∼50% overall identity with the two other class V myosins in vertebrates, myosin-Va (Myo5a) and myosin-Vb (Myo5b). Systematic analysis of the mRNA and protein distribution of these myosins indicates that Myo5a is most abundant in brain, whereas Myo5b and Myo5c are expressed chiefly in non-neuronal tissues. Myo5c is particularly abundant in epithelial and glandular tissues including pancreas, prostate, mammary,stomach, colon and lung. Immunolocalization in colon and exocrine pancreas indicates that Myo5c is expressed chiefly in epithelial cells. A dominant negative approach using a GFP-Myo5c tail construct in HeLa cells reveals that the Myo5c tail selectively colocalizes with and perturbs a membrane compartment containing the transferrin receptor and rab8. Transferrin also accumulates in this compartment, suggesting that Myo5c is involved in transferrin trafficking. As a class V myosin of epithelial cells, Myo5c is likely to power actin-based membrane trafficking in many physiologically crucial tissues of the human body.
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Affiliation(s)
- Olga C Rodriguez
- Department of Cell and Molecular Physiology, Medical Science Research Building, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
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41
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Abstract
All cells experience and respond to mechanical stimuli, such as changes in plasma membrane tension, shear stress, hydrostatic pressure, and compression. This review is an examination of the changes in membrane traffic that occur in response to mechanical forces. The plasma membrane has an associated tension that modulates both exocytosis and endocytosis. As membrane tension increases, exocytosis is stimulated, which acts to decrease membrane tension. In contrast, increased membrane tension slows endocytosis, whereas decreased tension stimulates internalization. In most cases, secretion is stimulated by external mechanical stimuli. However, in some cells mechanical forces block secretion. External stimuli also enhance membrane and fluid endocytosis in several cell types. Transduction of mechanical stimuli into changes in exocytosis/endocytosis may involve the cytoskeleton, stretch-activated channels, integrins, phospholipases, tyrosine kinases, and cAMP.
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Affiliation(s)
- Gerard Apodaca
- Laboratory of Epithelial Cell Biology, Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, USA.
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42
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Abstract
The myosin superfamily includes conventional and unconventional myosin proteins. Among unconventional myosins, myosin XVA has recently been characterized, and it has been suggested that it may be involved in cytoplasmic organelle movement, including secretory granules in pituitary cells and pituitary adenomas. In this study, we investigated the expression of myosin XVA protein and mRNA in normal endocrine cells and in a series of 53 endocrine tumors of the gut and pancreas. Myosin XVA was expressed in rare normal endocrine cells of the gut and in almost all pancreatic islet cells. In addition, myosin XVA was detected in several cells of all endocrine tumors investigated, and its expression was not related to malignancy, type, site, or functional status of tumors. These results indicate that myosin XVA protein and mRNA are widely distributed in endocrine cells of the gut and pancreas. Although the role of this protein in endocrine cells is unknown, previous studies suggest that it may have a role in secretory granule movement and/or hormone secretion.
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Affiliation(s)
- Stefano La Rosa
- Department of Pathology, Ospedale di Circolo, Varese, Italy.
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43
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Liu X, Osherov N, Yamashita R, Brzeska H, Korn ED, May GS. Myosin I mutants with only 1% of wild-type actin-activated MgATPase activity retain essential in vivo function(s). Proc Natl Acad Sci U S A 2001; 98:9122-7. [PMID: 11459943 PMCID: PMC55383 DOI: 10.1073/pnas.161285698] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/07/2001] [Indexed: 11/18/2022] Open
Abstract
The single class I myosin (MYOA) of Aspergillus nidulans is essential for hyphal growth. It is generally assumed that the functions of all myosins depend on their actin-activated MgATPase activity. Here we show that MYOA mutants with no more than 1% of the actin-activated MgATPase activity of wild-type MYOA in vitro and no detectable in vitro motility activity can support fungal cell growth, albeit with a delay in germination time and a reduction in hyphal elongation. From these and other data, we conclude that the essential role(s) of myosin I in A. nidulans is probably structural, requiring little, if any, actin-activated MgATPase or motor activity, which have long been considered the defining characteristics of the myosin family.
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Affiliation(s)
- X Liu
- Laboratory of Cell Biology, National Heart, Lung, and Blood Institute, National Institutes of Health, Building 50, Room 2517, Bethesda, MD 20892, USA
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44
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Reilein AR, Rogers SL, Tuma MC, Gelfand VI. Regulation of molecular motor proteins. INTERNATIONAL REVIEW OF CYTOLOGY 2001; 204:179-238. [PMID: 11243595 DOI: 10.1016/s0074-7696(01)04005-0] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Motor proteins in the kinesin, dynein, and myosin superfamilies are tightly regulated to perform multiple functions in the cell requiring force generation. Although motor proteins within families are diverse in sequence and structure, there are general mechanisms by which they are regulated. We first discuss the regulation of the subset of kinesin family members for which such information exists, and then address general mechanisms of kinesin family regulation. We review what is known about the regulation of axonemal and cytoplasmic dyneins. Recent work on cytoplasmic dynein has revealed the existence of multiple isoforms for each dynein chain, making the study of dynein regulation more complicated than previously realized. Finally, we discuss the regulation of myosins known to be involved in membrane trafficking. Myosins and kinesins may be evolutionarily related, and there are common themes of regulation between these two classes of motors.
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Affiliation(s)
- A R Reilein
- Department of Cell and Structural Biology, University of Illinois, Urbana-Champaign, Urbana 61801, USA
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45
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Okamoto CT, Forte JG. Vesicular trafficking machinery, the actin cytoskeleton, and H+-K+-ATPase recycling in the gastric parietal cell. J Physiol 2001; 532:287-96. [PMID: 11306650 PMCID: PMC2278542 DOI: 10.1111/j.1469-7793.2001.0287f.x] [Citation(s) in RCA: 66] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Gastric HCl secretion by the parietal cell involves the secretagogue-regulated re-cycling of the H+-K+-ATPase at the apical membrane. The trafficking of the H+-K+-ATPase and the remodelling of the apical membrane during this process are likely to involve the co-ordination of the function of vesicular trafficking machinery and the cytoskeleton. This review summarizes the progress made in the identification and characterization of components of the vesicular trafficking machinery that are associated with the H+-K+-ATPase and of components of the actin-based cytoskeleton that are associated with the apical membrane of the parietal cell. Since many of these proteins are also expressed at the apical pole of other epithelial cells, the parietal cell may represent a model system to characterize the protein- protein interactions that regulate apical membrane trafficking in many other epithelial cells.
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Affiliation(s)
- C T Okamoto
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Southern California, Los Angeles, CA 90089-9121, USA.
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46
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Abstract
The cytoskeleton is required for multiple cellular events including endocytosis and the transfer of cargo within the endocytic system. Polarized epithelial cells are capable of endocytosis at either of their distinct apical or basolateral plasma membrane domains. Actin plays a role in internalization at both cell surfaces. Microtubules and actin are required for efficient transcytosis and delivery of proteins to late endosomes and lysosomes. Microtubules are also important in apical recycling pathways and, in some polarized cell types, basolateral recycling requires actin. The microtubule motor proteins dynein and kinesin and the class I unconventional myosin motors play a role in many of these trafficking steps. This review examines the endocytic pathways of polarized epithelial cells and focuses on the emerging roles of the actin cytoskeleton in these processes.
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Affiliation(s)
- G Apodaca
- Renal-Electrolyte Division of the Department of Medicine, Laboratory of Epithelial Biology, and Department of Cell Biology and Physiology, University of Pittsburgh, PA 15261, USA.
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47
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Abstract
Intracellular pathogens such as Listeria monocytogenes and vaccinia virus propel themselves through the cytoplasm of mammalian cells by nucleating actin filaments. Recently, actin assembly has also been shown to power the movement of intracellular vesicles, and this may be a mechanism underlying endomembrane movement in a variety of physiological contexts. Surprisingly, class I myosins have been found to play important roles in both actin nucleation and endomembrane trafficking.
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Affiliation(s)
- J Taunton
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, 513 Parnassus Avenue, San Francisco, California 94143, USA.
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48
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Abstract
As sequencing of the human genome nears completion, the genes that cause many human diseases are being identified and functionally described. This has revealed that many human diseases are due to defects of intracellular trafficking. This 'Toolbox' catalogs and briefly describes these diseases.
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Affiliation(s)
- M Aridor
- Department of Cell Biology and Physiology, University of Pittsburgh, School of Medicine, 3500 Terrace St, Pittsburgh, PA 15261, USA
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49
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Abstract
Geometry-based mechanisms have been proposed to account for the sorting of membranes and fluid phase in the endocytic pathway, yet little is known about the involvement of the actin-myosin cytoskeleton. Here, we demonstrate that Dictyostelium discoideum myosin IB functions in the recycling of plasma membrane components from endosomes back to the cell surface. Cells lacking MyoB (myoA(-)/B(-), and myoB(-) cells) and wild-type cells treated with the myosin inhibitor butanedione monoxime accumulated a plasma membrane marker and biotinylated surface proteins on intracellular endocytic vacuoles. An assay based on reversible biotinylation of plasma membrane proteins demonstrated that recycling of membrane components is severely impaired in myoA/B null cells. In addition, MyoB was specifically found on magnetically purified early pinosomes. Using a rapid-freezing cryoelectron microscopy method, we observed an increased number of small vesicles tethered to relatively early endocytic vacuoles in myoA(-)/B(-) cells, but not to later endosomes and lysosomes. This accumulation of vesicles suggests that the defects in membrane recycling result from a disordered morphology of the sorting compartment.
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Affiliation(s)
- Eva M. Neuhaus
- Department of Molecular Cell Research, Max-Planck-Institute for Medical Research, D-69120 Heidelberg, Germany
| | - Thierry Soldati
- Department of Molecular Cell Research, Max-Planck-Institute for Medical Research, D-69120 Heidelberg, Germany
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