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Miyoshi T, Vishwasrao H, Belyantseva I, Sajeevadathan M, Ishibashi Y, Adadey S, Harada N, Shroff H, Friedman T. Live-cell single-molecule fluorescence microscopy for protruding organelles reveals regulatory mechanisms of MYO7A-driven cargo transport in stereocilia of inner ear hair cells. RESEARCH SQUARE 2024:rs.3.rs-4369958. [PMID: 38826223 PMCID: PMC11142366 DOI: 10.21203/rs.3.rs-4369958/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2024]
Abstract
Stereocilia are unidirectional F-actin-based cylindrical protrusions on the apical surface of inner ear hair cells and function as biological mechanosensors of sound and acceleration. Development of functional stereocilia requires motor activities of unconventional myosins to transport proteins necessary for elongating the F-actin cores and to assemble the mechanoelectrical transduction (MET) channel complex. However, how each myosin localizes in stereocilia using the energy from ATP hydrolysis is only partially understood. In this study, we develop a methodology for live-cell single-molecule fluorescence microscopy of organelles protruding from the apical surface using a dual-view light-sheet microscope, diSPIM. We demonstrate that MYO7A, a component of the MET machinery, traffics as a dimer in stereocilia. Movements of MYO7A are restricted when scaffolded by the plasma membrane and F-actin as mediated by MYO7A's interacting partners. Here, we discuss the technical details of our methodology and its future applications including analyses of cargo transportation in various organelles.
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Affiliation(s)
| | | | | | | | | | | | | | | | - Thomas Friedman
- National Institute on Deafness and Other Communication Disorders, NIH
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2
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Miyoshi T, Vishwasrao HD, Belyantseva IA, Sajeevadathan M, Ishibashi Y, Adadey SM, Harada N, Shroff H, Friedman TB. Live-cell single-molecule fluorescence microscopy for protruding organelles reveals regulatory mechanisms of MYO7A-driven cargo transport in stereocilia of inner ear hair cells. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.04.590649. [PMID: 38766013 PMCID: PMC11100596 DOI: 10.1101/2024.05.04.590649] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2024]
Abstract
Stereocilia are unidirectional F-actin-based cylindrical protrusions on the apical surface of inner ear hair cells and function as biological mechanosensors of sound and acceleration. Development of functional stereocilia requires motor activities of unconventional myosins to transport proteins necessary for elongating the F-actin cores and to assemble the mechanoelectrical transduction (MET) channel complex. However, how each myosin localizes in stereocilia using the energy from ATP hydrolysis is only partially understood. In this study, we develop a methodology for live-cell single-molecule fluorescence microscopy of organelles protruding from the apical surface using a dual-view light-sheet microscope, diSPIM. We demonstrate that MYO7A, a component of the MET machinery, traffics as a dimer in stereocilia. Movements of MYO7A are restricted when scaffolded by the plasma membrane and F-actin as mediated by MYO7A's interacting partners. Here, we discuss the technical details of our methodology and its future applications including analyses of cargo transportation in various organelles.
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Affiliation(s)
- Takushi Miyoshi
- Laboratory of Molecular Genetics, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD, 20892, USA
- Division of Molecular and Integrative Physiology, Department of Biomedical Sciences, Southern Illinois University School of Medicine, Carbondale, IL, 62901, USA
| | - Harshad D. Vishwasrao
- Advanced Imaging and Microscopy Resource, National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Inna A. Belyantseva
- Laboratory of Molecular Genetics, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Mrudhula Sajeevadathan
- Division of Molecular and Integrative Physiology, Department of Biomedical Sciences, Southern Illinois University School of Medicine, Carbondale, IL, 62901, USA
| | - Yasuko Ishibashi
- Laboratory of Molecular Genetics, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD, 20892, USA
- Inner Ear Gene Therapy Program, National Institute on Deafness and Other Communication Disorders, National Institute of Health, Bethesda, Maryland 20892, USA
| | - Samuel M. Adadey
- Laboratory of Molecular Genetics, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Narinobu Harada
- Hearing Research Laboratory, Harada ENT Clinic, Higashi-Osaka, Osaka, 577-0816, Japan
| | - Hari Shroff
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, 20147, USA
| | - Thomas B. Friedman
- Laboratory of Molecular Genetics, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD, 20892, USA
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Miyoshi T, Belyantseva IA, Sajeevadathan M, Friedman TB. Pathophysiology of human hearing loss associated with variants in myosins. Front Physiol 2024; 15:1374901. [PMID: 38562617 PMCID: PMC10982375 DOI: 10.3389/fphys.2024.1374901] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2024] [Accepted: 02/21/2024] [Indexed: 04/04/2024] Open
Abstract
Deleterious variants of more than one hundred genes are associated with hearing loss including MYO3A, MYO6, MYO7A and MYO15A and two conventional myosins MYH9 and MYH14. Variants of MYO7A also manifest as Usher syndrome associated with dysfunction of the retina and vestibule as well as hearing loss. While the functions of MYH9 and MYH14 in the inner ear are debated, MYO3A, MYO6, MYO7A and MYO15A are expressed in inner ear hair cells along with class-I myosin MYO1C and are essential for developing and maintaining functional stereocilia on the apical surface of hair cells. Stereocilia are large, cylindrical, actin-rich protrusions functioning as biological mechanosensors to detect sound, acceleration and posture. The rigidity of stereocilia is sustained by highly crosslinked unidirectionally-oriented F-actin, which also provides a scaffold for various proteins including unconventional myosins and their cargo. Typical myosin molecules consist of an ATPase head motor domain to transmit forces to F-actin, a neck containing IQ-motifs that bind regulatory light chains and a tail region with motifs recognizing partners. Instead of long coiled-coil domains characterizing conventional myosins, the tails of unconventional myosins have various motifs to anchor or transport proteins and phospholipids along the F-actin core of a stereocilium. For these myosins, decades of studies have elucidated their biochemical properties, interacting partners in hair cells and variants associated with hearing loss. However, less is known about how myosins traffic in a stereocilium using their motor function, and how each variant correlates with a clinical condition including the severity and onset of hearing loss, mode of inheritance and presence of symptoms other than hearing loss. Here, we cover the domain structures and functions of myosins associated with hearing loss together with advances, open questions about trafficking of myosins in stereocilia and correlations between hundreds of variants in myosins annotated in ClinVar and the corresponding deafness phenotypes.
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Affiliation(s)
- Takushi Miyoshi
- Laboratory of Molecular Genetics, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD, United States
- Division of Molecular and Integrative Physiology, Department of Biomedical Sciences, Southern Illinois University School of Medicine, Carbondale, IL, United States
| | - Inna A. Belyantseva
- Laboratory of Molecular Genetics, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD, United States
| | - Mrudhula Sajeevadathan
- Division of Molecular and Integrative Physiology, Department of Biomedical Sciences, Southern Illinois University School of Medicine, Carbondale, IL, United States
| | - Thomas B. Friedman
- Laboratory of Molecular Genetics, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD, United States
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4
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Cirilo JA, Liao X, Perrin BJ, Yengo CM. The dynamics of actin protrusions can be controlled by tip-localized myosin motors. J Biol Chem 2024; 300:105516. [PMID: 38042485 PMCID: PMC10801316 DOI: 10.1016/j.jbc.2023.105516] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2023] [Revised: 11/20/2023] [Accepted: 11/22/2023] [Indexed: 12/04/2023] Open
Abstract
Class III myosins localize to inner ear hair cell stereocilia and are thought to be crucial for stereocilia length regulation. Mutations within the motor domain of MYO3A that disrupt its intrinsic motor properties have been associated with non-syndromic hearing loss, suggesting that the motor properties of MYO3A are critical for its function within stereocilia. In this study, we investigated the impact of a MYO3A hearing loss mutation, H442N, using both in vitro motor assays and cell biological studies. Our results demonstrate the mutation causes a dramatic increase in intrinsic motor properties, actin-activated ATPase and in vitro actin gliding velocity, as well as an increase in actin protrusion extension velocity. We propose that both "gain of function" and "loss of function" mutations in MYO3A can impair stereocilia length regulation, which is crucial for stereocilia formation during development and normal hearing. Furthermore, we generated chimeric MYO3A constructs that replace the MYO3A motor and neck domain with the motor and neck domain of other myosins. We found that duty ratio, fraction of ATPase cycle myosin is strongly bound to actin, is a critical motor property that dictates the ability to tip localize within filopodia. In addition, in vitro actin gliding velocities correlated extremely well with filopodial extension velocities over a wide range of gliding and extension velocities. Taken together, our data suggest a model in which tip-localized myosin motors exert force that slides the membrane tip-ward, which can combat membrane tension and enhance the actin polymerization rate that ultimately drives protrusion elongation.
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Affiliation(s)
- Joseph A Cirilo
- Department of Cellular and Molecular Physiology, Penn State College of Medicine, Hershey, Pennsylvania, USA
| | - Xiayi Liao
- Department of Biology, Indiana University - Purdue University, Indianapolis, Indiana, USA
| | - Benjamin J Perrin
- Department of Biology, Indiana University - Purdue University, Indianapolis, Indiana, USA
| | - Christopher M Yengo
- Department of Cellular and Molecular Physiology, Penn State College of Medicine, Hershey, Pennsylvania, USA.
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5
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Souissi A, Abdelmalek Driss D, Chakchouk I, Ben Said M, Ben Ayed I, Mosrati MA, Elloumi I, Tlili A, Aifa S, Masmoudi S. Molecular insights into MYO3A kinase domain variants explain variability in both severity and progression of DFNB30 hearing impairment. J Biomol Struct Dyn 2022; 40:10940-10951. [PMID: 34423747 DOI: 10.1080/07391102.2021.1953600] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Hereditary hearing impairment (HI) is a common disease with the highest incidence among sensory defects. Several genes have been identified to affect stereocilia structure causing HI, including the unconventional myosin3A. Interestingly, we noticed that variants in MYO3A gene have been previously found to cause variable HI onset and severity. Using clinical exome sequencing, we identified a novel pathogenic variant p.(Lys50Arg) in the MYO3A kinase domain (MYO3A-KD). Previous in vitro studies supported its damaging effect as a 'kinase-dead' mutant. We further analyzed this variation through molecular dynamics which predicts that changes in flexibility of MYO3A structure would influence the protein-ATP binding properties. This Lys50Arg mutation segregated with congenital profound non-syndromic HI. To better investigate this variability, we collected previously identified MYO3A-KDs variants, p.(Tyr129Cys), p.(His142Gln) and p.(Pro189Thr), and built both wild type and mutant 3 D MYO3A-KD models to assess their impact on the protein structure and function. Our results suggest that KD mutations could either cause a congenital profound form of HI, when particularly affecting the kinase activity and preventing the auto-phosphorylation of the motor, or a late onset and progressive form, when partially or completely inactivating the MYO3A protein. In conclusion, we report a novel pathogenic variant affecting the ATP-binding site within the MYO3A-KD causing congenital profound HI. Through computational approaches we provide a deeper understanding on the correlation between the effects of MYO3A-KD mutations and the variable hearing phenotypes. To the best of our knowledge this is the first study to correlate mutations' genotypes with the variable phenotypes of DFNB30.Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
- Amal Souissi
- Laboratory of Molecular and Cellular Screening Processes, Centre of Biotechnology of Sfax, University of Sfax, Sfax, Tunisia
| | - Dorra Abdelmalek Driss
- Laboratory of Molecular and Cellular Screening Processes, Centre of Biotechnology of Sfax, University of Sfax, Sfax, Tunisia
| | - Imen Chakchouk
- Department of Obstetrics and Gynecology, Baylor College of Medicine, Houston, TX, USA
| | - Mariem Ben Said
- Laboratory of Molecular and Cellular Screening Processes, Centre of Biotechnology of Sfax, University of Sfax, Sfax, Tunisia
| | - Ikhlas Ben Ayed
- Laboratory of Molecular and Cellular Screening Processes, Centre of Biotechnology of Sfax, University of Sfax, Sfax, Tunisia.,Medical Genetic Department, University Hedi Chaker Hospital of Sfax, Sfax, Tunisia
| | - Mohamed Ali Mosrati
- Laboratory of Molecular and Cellular Screening Processes, Centre of Biotechnology of Sfax, University of Sfax, Sfax, Tunisia
| | - Ines Elloumi
- Laboratory of Molecular and Cellular Screening Processes, Centre of Biotechnology of Sfax, University of Sfax, Sfax, Tunisia
| | - Abdelaziz Tlili
- Department of Applied Biology, College of Sciences, University of Sharjah, Sharjah, United Arab Emirates.,Human Genetics and Stem Cell Laboratory, Research Institute of Sciences and Engineering, University of Sharjah, Sharjah, United Arab Emirates
| | - Sami Aifa
- Laboratory of Molecular and Cellular Screening Processes, Centre of Biotechnology of Sfax, University of Sfax, Sfax, Tunisia
| | - Saber Masmoudi
- Laboratory of Molecular and Cellular Screening Processes, Centre of Biotechnology of Sfax, University of Sfax, Sfax, Tunisia
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6
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Gunther LK, Cirilo JA, Desetty R, Yengo CM. Deafness mutation in the MYO3A motor domain impairs actin protrusion elongation mechanism. Mol Biol Cell 2021; 33:ar5. [PMID: 34788109 PMCID: PMC8886822 DOI: 10.1091/mbc.e21-05-0232] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Class III myosins are actin-based motors proposed to transport cargo to the distal tips of stereocilia in the inner ear hair cells and/or to participate in stereocilia length regulation, which is especially important during development. Mutations in the MYO3A gene are associated with delayed onset deafness. A previous study demonstrated that L697W, a dominant deafness mutation, disrupts MYO3A ATPase and motor properties but does not impair its ability to localize to the tips of actin protrusions. In the current study, we characterized the transient kinetic mechanism of the L697W motor ATPase cycle. Our kinetic analysis demonstrates that the mutation slows the ADP release and ATP hydrolysis steps, which results in a slight reduction in the duty ratio and slows detachment kinetics. Fluorescence recovery after photobleaching (FRAP) of filopodia tip localized L697W and WT MYO3A in COS-7 cells revealed that the mutant does not alter turnover or average intensity at the actin protrusion tips. We demonstrate that the mutation slows filopodia extension velocity in COS-7 cells which correlates with its twofold slower in vitro actin gliding velocity. Overall, this work allowed us to propose a model for how the motor properties of MYO3A are crucial for facilitating actin protrusion length regulation.
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Affiliation(s)
- Laura K Gunther
- Department of Cellular and Molecular Physiology, College of Medicine, Pennsylvania State University, Hershey, PA, 17033
| | - Joseph A Cirilo
- Department of Cellular and Molecular Physiology, College of Medicine, Pennsylvania State University, Hershey, PA, 17033
| | - Rohini Desetty
- Department of Cellular and Molecular Physiology, College of Medicine, Pennsylvania State University, Hershey, PA, 17033
| | - Christopher M Yengo
- Department of Cellular and Molecular Physiology, College of Medicine, Pennsylvania State University, Hershey, PA, 17033
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7
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Cirilo JA, Gunther LK, Yengo CM. Functional Role of Class III Myosins in Hair Cells. Front Cell Dev Biol 2021; 9:643856. [PMID: 33718386 PMCID: PMC7947357 DOI: 10.3389/fcell.2021.643856] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Accepted: 02/01/2021] [Indexed: 11/14/2022] Open
Abstract
Cytoskeletal motors produce force and motion using the energy from ATP hydrolysis and function in a variety of mechanical roles in cells including muscle contraction, cargo transport, and cell division. Actin-based myosin motors have been shown to play crucial roles in the development and function of the stereocilia of auditory and vestibular inner ear hair cells. Hair cells can contain hundreds of stereocilia, which rely on myosin motors to elongate, organize, and stabilize their structure. Mutations in many stereocilia-associated myosins have been shown to cause hearing loss in both humans and animal models suggesting that each myosin isoform has a specific function in these unique parallel actin bundle-based protrusions. Here we review what is known about the classes of myosins that function in the stereocilia, with a special focus on class III myosins that harbor point mutations associated with delayed onset hearing loss. Much has been learned about the role of the two class III myosin isoforms, MYO3A and MYO3B, in maintaining the precise stereocilia lengths required for normal hearing. We propose a model for how class III myosins play a key role in regulating stereocilia lengths and demonstrate how their motor and regulatory properties are particularly well suited for this function. We conclude that ongoing studies on class III myosins and other stereocilia-associated myosins are extremely important and may lead to novel therapeutic strategies for the treatment of hearing loss due to stereocilia degeneration.
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Affiliation(s)
- Joseph A Cirilo
- Department of Cellular and Molecular Physiology, College of Medicine, Pennsylvania State University, Hershey, PA, United States
| | - Laura K Gunther
- Department of Cellular and Molecular Physiology, College of Medicine, Pennsylvania State University, Hershey, PA, United States
| | - Christopher M Yengo
- Department of Cellular and Molecular Physiology, College of Medicine, Pennsylvania State University, Hershey, PA, United States
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8
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Doll J, Hofrichter MAH, Bahena P, Heihoff A, Segebarth D, Müller T, Dittrich M, Haaf T, Vona B. A novel missense variant in MYO3A is associated with autosomal dominant high-frequency hearing loss in a German family. Mol Genet Genomic Med 2020; 8:e1343. [PMID: 32519820 PMCID: PMC7434730 DOI: 10.1002/mgg3.1343] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Revised: 05/16/2020] [Accepted: 05/19/2020] [Indexed: 12/30/2022] Open
Abstract
Background MYO3A, encoding the myosin IIIA protein, is associated with autosomal recessive and autosomal dominant nonsyndromic hearing loss. To date, only two missense variants located in the motor‐head domain of MYO3A have been described in autosomal dominant families with progressive, mild‐to‐profound sensorineural hearing loss. These variants alter the ATPase activity of myosin IIIA. Methods Exome sequencing of a proband from a three‐generation German family with prelingual, moderate‐to‐profound, high‐frequency hearing loss was performed. Segregation analysis confirmed a dominant inheritance pattern. Regression analysis of mean hearing level thresholds per individual and ear was performed at high‐, mid‐, and low‐frequencies. Results A novel heterozygous missense variant c.716T>C, p.(Leu239Pro) in the kinase domain of MYO3A was identified that is predicted in silico as disease causing. High‐frequency, progressive hearing loss was identified. Conclusion Correlation analysis of pure‐tone hearing thresholds revealed progressive hearing loss, especially in the high‐frequencies. In the present study, we report the first dominant likely pathogenic variant in MYO3A in a European family and further support MYO3A as an autosomal dominant hearing loss gene.
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Affiliation(s)
- Julia Doll
- Institute of Human Genetics, Julius Maximilians University, Würzburg, Germany
| | | | - Paulina Bahena
- Institute of Human Genetics, Julius Maximilians University, Würzburg, Germany
| | | | - Dennis Segebarth
- Institute of Clinical Neurobiology, University Hospital Würzburg, Würzburg, Germany
| | - Tobias Müller
- Institute of Bioinformatics, Julius Maximilians University, Würzburg, Germany
| | - Marcus Dittrich
- Institute of Human Genetics, Julius Maximilians University, Würzburg, Germany.,Institute of Bioinformatics, Julius Maximilians University, Würzburg, Germany
| | - Thomas Haaf
- Institute of Human Genetics, Julius Maximilians University, Würzburg, Germany
| | - Barbara Vona
- Institute of Human Genetics, Julius Maximilians University, Würzburg, Germany.,Tübingen Hearing Research Centre, Department of Otolaryngology - Head and Neck Surgery, Eberhard Karls University, Tübingen, Germany
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9
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Unconventional Myosins: How Regulation Meets Function. Int J Mol Sci 2019; 21:ijms21010067. [PMID: 31861842 PMCID: PMC6981383 DOI: 10.3390/ijms21010067] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2019] [Revised: 12/16/2019] [Accepted: 12/18/2019] [Indexed: 01/24/2023] Open
Abstract
Unconventional myosins are multi-potent molecular motors that are assigned important roles in fundamental cellular processes. Depending on their mechano-enzymatic properties and structural features, myosins fulfil their roles by acting as cargo transporters along the actin cytoskeleton, molecular anchors or tension sensors. In order to perform such a wide range of roles and modes of action, myosins need to be under tight regulation in time and space. This is achieved at multiple levels through diverse regulatory mechanisms: the alternative splicing of various isoforms, the interaction with their binding partners, their phosphorylation, their applied load and the composition of their local environment, such as ions and lipids. This review summarizes our current knowledge of how unconventional myosins are regulated, how these regulatory mechanisms can adapt to the specific features of a myosin and how they can converge with each other in order to ensure the required tight control of their function.
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10
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Characterization of a novel MYO3A missense mutation associated with a dominant form of late onset hearing loss. Sci Rep 2018; 8:8706. [PMID: 29880844 PMCID: PMC5992146 DOI: 10.1038/s41598-018-26818-2] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2017] [Accepted: 05/18/2018] [Indexed: 01/08/2023] Open
Abstract
Whole-exome sequencing of samples from affected members of two unrelated families with late-onset non-syndromic hearing loss revealed a novel mutation (c.2090 T > G; NM_017433) in MYO3A. The mutation was confirmed in 36 affected individuals, showing autosomal dominant inheritance. The mutation alters a single residue (L697W or p.Leu697Trp) in the motor domain of the stereocilia protein MYO3A, leading to a reduction in ATPase activity, motility, and an increase in actin affinity. MYO3A-L697W showed reduced filopodial actin protrusion initiation in COS7 cells, and a predominant tipward accumulation at filopodia and stereocilia when coexpressed with wild-type MYO3A and espin-1, an actin-regulatory MYO3A cargo. The combined higher actin affinity and duty ratio of the mutant myosin cause increased retention time at stereocilia tips, resulting in the displacement of the wild-type MYO3A protein, which may impact cargo transport, stereocilia length, and mechanotransduction. The dominant negative effect of the altered myosin function explains the dominant inheritance of deafness.
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11
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Abstract
The delivery of intracellular material within cells is crucial for maintaining normal function. Myosins transport a wide variety of cargo, ranging from vesicles to ribonuclear protein particles (RNPs), in plants, fungi, and metazoa. The properties of a given myosin transporter are adapted to move on different actin filament tracks, either on the disordered actin networks at the cell cortex or along highly organized actin bundles to distribute their cargo in a localized manner or move it across long distances in the cell. Transport is controlled by selective recruitment of the myosin to its cargo that also plays a role in activation of the motor.
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Affiliation(s)
- Margaret A Titus
- Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, Minnesota 55455
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12
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Swenson AM, Tang W, Blair CA, Fetrow CM, Unrath WC, Previs MJ, Campbell KS, Yengo CM. Omecamtiv Mecarbil Enhances the Duty Ratio of Human β-Cardiac Myosin Resulting in Increased Calcium Sensitivity and Slowed Force Development in Cardiac Muscle. J Biol Chem 2017; 292:3768-3778. [PMID: 28082673 DOI: 10.1074/jbc.m116.748780] [Citation(s) in RCA: 64] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2016] [Revised: 01/05/2017] [Indexed: 01/10/2023] Open
Abstract
The small molecule drug omecamtiv mecarbil (OM) specifically targets cardiac muscle myosin and is known to enhance cardiac muscle performance, yet its impact on human cardiac myosin motor function is unclear. We expressed and purified human β-cardiac myosin subfragment 1 (M2β-S1) containing a C-terminal Avi tag. We demonstrate that the maximum actin-activated ATPase activity of M2β-S1 is slowed more than 4-fold in the presence of OM, whereas the actin concentration required for half-maximal ATPase was reduced dramatically (30-fold). We find OM does not change the overall actin affinity. Transient kinetic experiments suggest that there are two kinetic pathways in the presence of OM. The dominant pathway results in a slow transition between actomyosin·ADP states and increases the time myosin is strongly bound to actin. However, OM also traps a population of myosin heads in a weak actin affinity state with slow product release. We demonstrate that OM can reduce the actin sliding velocity more than 100-fold in the in vitro motility assay. The ionic strength dependence of in vitro motility suggests the inhibition may be at least partially due to drag forces from weakly attached myosin heads. OM causes an increase in duty ratio examined in the motility assay. Experiments with permeabilized human myocardium demonstrate that OM increases calcium sensitivity and slows force development (ktr) in a concentration-dependent manner, whereas the maximally activated force is unchanged. We propose that OM increases the myosin duty ratio, which results in enhanced calcium sensitivity but slower force development in human myocardium.
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Affiliation(s)
- Anja M Swenson
- From the Department of Cellular and Molecular Physiology, Pennsylvania State University College of Medicine, Hershey, Pennsylvania 17033
| | - Wanjian Tang
- From the Department of Cellular and Molecular Physiology, Pennsylvania State University College of Medicine, Hershey, Pennsylvania 17033
| | - Cheavar A Blair
- the Department of Physiology and Division of Cardiovascular Medicine, University of Kentucky, Lexington, Kentucky 40536-0298, and
| | - Christopher M Fetrow
- From the Department of Cellular and Molecular Physiology, Pennsylvania State University College of Medicine, Hershey, Pennsylvania 17033
| | - William C Unrath
- From the Department of Cellular and Molecular Physiology, Pennsylvania State University College of Medicine, Hershey, Pennsylvania 17033
| | - Michael J Previs
- the Department of Molecular Physiology and Biophysics, Cardiovascular Research Institute, University of Vermont, Burlington, Vermont 05405
| | - Kenneth S Campbell
- the Department of Physiology and Division of Cardiovascular Medicine, University of Kentucky, Lexington, Kentucky 40536-0298, and
| | - Christopher M Yengo
- From the Department of Cellular and Molecular Physiology, Pennsylvania State University College of Medicine, Hershey, Pennsylvania 17033,
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13
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Tang W, Blair CA, Walton SD, Málnási-Csizmadia A, Campbell KS, Yengo CM. Modulating Beta-Cardiac Myosin Function at the Molecular and Tissue Levels. Front Physiol 2017; 7:659. [PMID: 28119616 PMCID: PMC5220080 DOI: 10.3389/fphys.2016.00659] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Accepted: 12/15/2016] [Indexed: 01/10/2023] Open
Abstract
Inherited cardiomyopathies are a common form of heart disease that are caused by mutations in sarcomeric proteins with beta cardiac myosin (MYH7) being one of the most frequently affected genes. Since the discovery of the first cardiomyopathy associated mutation in beta-cardiac myosin, a major goal has been to correlate the in vitro myosin motor properties with the contractile performance of cardiac muscle. There has been substantial progress in developing assays to measure the force and velocity properties of purified cardiac muscle myosin but it is still challenging to correlate results from molecular and tissue-level experiments. Mutations that cause hypertrophic cardiomyopathy are more common than mutations that lead to dilated cardiomyopathy and are also often associated with increased isometric force and hyper-contractility. Therefore, the development of drugs designed to decrease isometric force by reducing the duty ratio (the proportion of time myosin spends bound to actin during its ATPase cycle) has been proposed for the treatment of hypertrophic cardiomyopathy. Para-Nitroblebbistatin is a small molecule drug proposed to decrease the duty ratio of class II myosins. We examined the impact of this drug on human beta cardiac myosin using purified myosin motor assays and studies of permeabilized muscle fiber mechanics. We find that with purified human beta-cardiac myosin para-Nitroblebbistatin slows actin-activated ATPase and in vitro motility without altering the ADP release rate constant. In permeabilized human myocardium, para-Nitroblebbistatin reduces isometric force, power, and calcium sensitivity while not changing shortening velocity or the rate of force development (ktr). Therefore, designing a drug that reduces the myosin duty ratio by inhibiting strong attachment to actin while not changing detachment can cause a reduction in force without changing shortening velocity or relaxation.
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Affiliation(s)
- Wanjian Tang
- Department of Cellular and Molecular Physiology, Pennsylvania State University College of Medicine Hershey, PA, USA
| | - Cheavar A Blair
- Department of Physiology, University of Kentucky Lexington, KY, USA
| | - Shane D Walton
- Department of Cellular and Molecular Physiology, Pennsylvania State University College of Medicine Hershey, PA, USA
| | | | - Kenneth S Campbell
- Department of Physiology, University of KentuckyLexington, KY, USA; Division of Cardiovascular Medicine, University of KentuckyLexington, KY, USA
| | - Christopher M Yengo
- Department of Cellular and Molecular Physiology, Pennsylvania State University College of Medicine Hershey, PA, USA
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14
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Masters TA, Kendrick-Jones J, Buss F. Myosins: Domain Organisation, Motor Properties, Physiological Roles and Cellular Functions. Handb Exp Pharmacol 2017; 235:77-122. [PMID: 27757761 DOI: 10.1007/164_2016_29] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Myosins are cytoskeletal motor proteins that use energy derived from ATP hydrolysis to generate force and movement along actin filaments. Humans express 38 myosin genes belonging to 12 classes that participate in a diverse range of crucial activities, including muscle contraction, intracellular trafficking, cell division, motility, actin cytoskeletal organisation and cell signalling. Myosin malfunction has been implicated a variety of disorders including deafness, hypertrophic cardiomyopathy, Usher syndrome, Griscelli syndrome and cancer. In this chapter, we will first discuss the key structural and kinetic features that are conserved across the myosin family. Thereafter, we summarise for each member in turn its unique functional and structural adaptations, cellular roles and associated pathologies. Finally, we address the broad therapeutic potential for pharmacological interventions that target myosin family members.
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Affiliation(s)
- Thomas A Masters
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, CB2 0XY, UK.
| | | | - Folma Buss
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, CB2 0XY, UK
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15
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Raval MH, Quintero OA, Weck ML, Unrath WC, Gallagher JW, Cui R, Kachar B, Tyska MJ, Yengo CM. Impact of the Motor and Tail Domains of Class III Myosins on Regulating the Formation and Elongation of Actin Protrusions. J Biol Chem 2016; 291:22781-22792. [PMID: 27582493 PMCID: PMC5077211 DOI: 10.1074/jbc.m116.733741] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Revised: 08/29/2016] [Indexed: 11/06/2022] Open
Abstract
Class III myosins (MYO3A and MYO3B) are proposed to function as transporters as well as length and ultrastructure regulators within stable actin-based protrusions such as stereocilia and calycal processes. MYO3A differs from MYO3B in that it contains an extended tail domain with an additional actin-binding motif. We examined how the properties of the motor and tail domains of human class III myosins impact their ability to enhance the formation and elongation of actin protrusions. Direct examination of the motor and enzymatic properties of human MYO3A and MYO3B revealed that MYO3A is a 2-fold faster motor with enhanced ATPase activity and actin affinity. A chimera in which the MYO3A tail was fused to the MYO3B motor demonstrated that motor activity correlates with formation and elongation of actin protrusions. We demonstrate that removal of individual exons (30-34) in the MYO3A tail does not prevent filopodia tip localization but abolishes the ability to enhance actin protrusion formation and elongation in COS7 cells. Interestingly, our results demonstrate that MYO3A slows filopodia dynamics and enhances filopodia lifetime in COS7 cells. We also demonstrate that MYO3A is more efficient than MYO3B at increasing formation and elongation of stable microvilli on the surface of cultured epithelial cells. We propose that the unique features of MYO3A, enhanced motor activity, and an extended tail with tail actin-binding motif, allow it to play an important role in stable actin protrusion length and ultrastructure maintenance.
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Affiliation(s)
- Manmeet H Raval
- From the Department of Cellular and Molecular Physiology, Pennsylvania State University, College of Medicine, Hershey, Pennsylvania 17033
| | - Omar A Quintero
- the Department of Biology, University of Richmond, Richmond, Virginia 23173
| | - Meredith L Weck
- the Department of Cell and Developmental Biology, Vanderbilt University Medical Center, Nashville, Tennessee 37232
| | - William C Unrath
- From the Department of Cellular and Molecular Physiology, Pennsylvania State University, College of Medicine, Hershey, Pennsylvania 17033
| | - James W Gallagher
- the Department of Biology, Lincoln University, Philadelphia, Pennsylvania 19104, and
| | - Runjia Cui
- the Laboratory of Cell Structure and Dynamics, NIDCD, National Institutes of Health, Bethesda, Maryland 20892
| | - Bechara Kachar
- the Laboratory of Cell Structure and Dynamics, NIDCD, National Institutes of Health, Bethesda, Maryland 20892
| | - Matthew J Tyska
- the Department of Cell and Developmental Biology, Vanderbilt University Medical Center, Nashville, Tennessee 37232
| | - Christopher M Yengo
- From the Department of Cellular and Molecular Physiology, Pennsylvania State University, College of Medicine, Hershey, Pennsylvania 17033,
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16
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Baum P, Vogt MA, Gass P, Unsicker K, von Bohlen und Halbach O. FGF-2 deficiency causes dysregulation of Arhgef6 and downstream targets in the cerebral cortex accompanied by altered neurite outgrowth and dendritic spine morphology. Int J Dev Neurosci 2016; 50:55-64. [PMID: 26970009 DOI: 10.1016/j.ijdevneu.2016.03.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2016] [Revised: 03/01/2016] [Accepted: 03/01/2016] [Indexed: 01/13/2023] Open
Abstract
Fibroblast growth factor 2 (FGF-2) is an abundant growth factor in the brain and exerts multiple functions on neural cells ranging from cell division, cell fate determination to differentiation. However, many details of the molecular mechanisms underlying the diverse functions of FGF-2 are poorly understood. In a comparative microarray analysis of motor sensory cortex (MSC) tissue of adult knockout (FGF-2(-/-)) and control (FGF-2(+/+)) mice, we found a substantial number of regulated genes, which are implicated in cytoskeletal machinery dynamics. Specifically, we found a prominent downregulation of Arhgef6. Arhgef6 mRNA was significantly reduced in the FGF-2(-/-) cortex, and Arhgef6 protein virtually absent, while RhoA protein levels were massively increased and Cdc42 protein levels were reduced. Since Arhgef6 is localized to dendritic spines, we next analyzed dendritic spines of adult FGF2(-/-) and control mouse cortices. Spine densities were significantly increased, whereas mean length of spines on dendrites of layer V of MSC neurons in adult FGF-2(-/-) mice was significantly decreased as compared to respective controls. Furthermore, neurite length in dissociated cortical cultures from E18 FGF-2(-/-) mice was significantly reduced at DIV7 as compared to wildtype neurons. Despite the fact that altered neuronal morphology and alterations in dendritic spines were observed, FGF-2(-/-) mice behave relatively unsuspicious in several behavioral tasks. However, FGF-2(-/-) mice exhibited decreased thermal pain sensitivity in the hotplate-test.
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Affiliation(s)
- Philip Baum
- Institut für Anatomie und Zellbiologie, Universitätsmedizin Greifswald, Germany; Anatomy & Cell Biology, Department of Molecular Embryology, University of Freiburg, Germany
| | - Miriam A Vogt
- AG Animal Models in Psychiatry, Department of Psychiatry and Psychotherapy, Central Institute of Mental Health, Medical Faculty Mannheim/University of Heidelberg, Germany; RG Molecular Physiology of Hearing, Head and Neck Surgery Tübingen Hearing, Research Center (THRC),Department of Otolaryngology, University Hospital Tübingen, Germany
| | - Peter Gass
- AG Animal Models in Psychiatry, Department of Psychiatry and Psychotherapy, Central Institute of Mental Health, Medical Faculty Mannheim/University of Heidelberg, Germany
| | - Klaus Unsicker
- Anatomy & Cell Biology, Department of Molecular Embryology, University of Freiburg, Germany
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17
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Ebrahim S, Avenarius MR, Grati M, Krey JF, Windsor AM, Sousa AD, Ballesteros A, Cui R, Millis BA, Salles FT, Baird MA, Davidson MW, Jones SM, Choi D, Dong L, Raval MH, Yengo CM, Barr-Gillespie PG, Kachar B. Stereocilia-staircase spacing is influenced by myosin III motors and their cargos espin-1 and espin-like. Nat Commun 2016; 7:10833. [PMID: 26926603 PMCID: PMC4773517 DOI: 10.1038/ncomms10833] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2015] [Accepted: 01/25/2016] [Indexed: 12/12/2022] Open
Abstract
Hair cells tightly control the dimensions of their stereocilia, which are actin-rich protrusions with graded heights that mediate mechanotransduction in the inner ear. Two members of the myosin-III family, MYO3A and MYO3B, are thought to regulate stereocilia length by transporting cargos that control actin polymerization at stereocilia tips. We show that eliminating espin-1 (ESPN-1), an isoform of ESPN and a myosin-III cargo, dramatically alters the slope of the stereocilia staircase in a subset of hair cells. Furthermore, we show that espin-like (ESPNL), primarily present in developing stereocilia, is also a myosin-III cargo and is essential for normal hearing. ESPN-1 and ESPNL each bind MYO3A and MYO3B, but differentially influence how the two motors function. Consequently, functional properties of different motor-cargo combinations differentially affect molecular transport and the length of actin protrusions. This mechanism is used by hair cells to establish the required range of stereocilia lengths within a single cell.
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Affiliation(s)
- Seham Ebrahim
- Laboratory of Cell Structure and Dynamics, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Matthew R Avenarius
- Oregon Hearing Research Center and Vollum Institute, Oregon Health &Science University, Portland, Oregon 97239, USA
| | - M'hamed Grati
- Laboratory of Cell Structure and Dynamics, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Jocelyn F Krey
- Oregon Hearing Research Center and Vollum Institute, Oregon Health &Science University, Portland, Oregon 97239, USA
| | - Alanna M Windsor
- Laboratory of Cell Structure and Dynamics, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Aurea D Sousa
- Laboratory of Cell Structure and Dynamics, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Angela Ballesteros
- Laboratory of Cell Structure and Dynamics, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Runjia Cui
- Laboratory of Cell Structure and Dynamics, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Bryan A Millis
- Laboratory of Cell Structure and Dynamics, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Felipe T Salles
- Laboratory of Cell Structure and Dynamics, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Michelle A Baird
- National High Magnetic Field Laboratory and Department of Biological Science, Florida State University, Tallahassee, Florida 32310, USA
| | - Michael W Davidson
- National High Magnetic Field Laboratory and Department of Biological Science, Florida State University, Tallahassee, Florida 32310, USA
| | - Sherri M Jones
- Department of Special Education and Communication Disorders, University of Nebraska-Lincoln, Lincoln, Nebraska 68583, USA
| | - Dongseok Choi
- Department of Public Health and Preventive Medicine, Oregon Health and Science University, Portland, Oregon 97239, USA
| | - Lijin Dong
- Genetic Engineering Core, National Eye Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Manmeet H Raval
- Department of Cellular and Molecular Physiology, Penn State University College of Medicine, Hershey, Pennsylvania 17033, USA
| | - Christopher M Yengo
- Department of Cellular and Molecular Physiology, Penn State University College of Medicine, Hershey, Pennsylvania 17033, USA
| | - Peter G Barr-Gillespie
- Oregon Hearing Research Center and Vollum Institute, Oregon Health &Science University, Portland, Oregon 97239, USA
| | - Bechara Kachar
- Laboratory of Cell Structure and Dynamics, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, Maryland 20892, USA
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18
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Grati M, Yan D, Raval MH, Walsh T, Ma Q, Chakchouk I, Kannan-Sundhari A, Mittal R, Masmoudi S, Blanton SH, Tekin M, King MC, Yengo CM, Liu XZ. MYO3A Causes Human Dominant Deafness and Interacts with Protocadherin 15-CD2 Isoform. Hum Mutat 2016; 37:481-7. [PMID: 26841241 DOI: 10.1002/humu.22961] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2015] [Accepted: 01/15/2016] [Indexed: 01/10/2023]
Abstract
Hereditary hearing loss (HL) is characterized by both allelic and locus genetic heterogeneity. Both recessive and dominant forms of HL may be caused by different mutations in the same deafness gene. In a family with post-lingual progressive non-syndromic deafness, whole-exome sequencing of genomic DNA from five hearing-impaired relatives revealed a single variant, p.Gly488Glu (rs145970949:G>A) in MYO3A, co-segregating with HL as an autosomal dominant trait. This amino acid change, predicted to be pathogenic, alters a highly conserved residue in the motor domain of MYO3A. The mutation severely alters the ATPase activity and motility of the protein in vitro, and the mutant protein fails to accumulate in the filopodia tips in COS7 cells. However, the mutant MYO3A was able to reach the tips of organotypic inner ear culture hair cell stereocilia, raising the possibility of a local effect on positioning of the mechanoelectrical transduction (MET) complex at the stereocilia tips. To address this hypothesis, we investigated the interaction of MYO3A with the cytosolic tail of the integral tip-link protein protocadherin 15 (PCDH15), a core component of MET complex. Interestingly, we uncovered a novel interaction between MYO3A and PCDH15 shedding new light on the function of myosin IIIA at stereocilia tips.
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Affiliation(s)
- M'hamed Grati
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, Florida
| | - Denise Yan
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, Florida
| | - Manmeet H Raval
- Department of Cellular and Molecular Physiology, Pennsylvania State University College of Medicine, Hershey, Pennsylvania
| | - Tom Walsh
- Departments of Medicine and Genome Sciences, University of Washington, Seattle, Washington
| | - Qi Ma
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, Florida
| | - Imen Chakchouk
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, Florida.,Laboratoire Procédés de Criblage Moléculaire et Cellulaire, Centre de Biotechnologie de Sfax, Université de Sfax, Sfax, Tunisie
| | | | - Rahul Mittal
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, Florida
| | - Saber Masmoudi
- Laboratoire Procédés de Criblage Moléculaire et Cellulaire, Centre de Biotechnologie de Sfax, Université de Sfax, Sfax, Tunisie
| | - Susan H Blanton
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, Florida.,Dr. John T. Macdonald Foundation, Department of Human Genetics, and John P. Hussman Institute for Human Genomics, University of Miami, Miami, Florida
| | - Mustafa Tekin
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, Florida.,Dr. John T. Macdonald Foundation, Department of Human Genetics, and John P. Hussman Institute for Human Genomics, University of Miami, Miami, Florida
| | - Mary-Claire King
- Departments of Medicine and Genome Sciences, University of Washington, Seattle, Washington
| | - Christopher M Yengo
- Department of Cellular and Molecular Physiology, Pennsylvania State University College of Medicine, Hershey, Pennsylvania
| | - Xue Zhong Liu
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, Florida.,Dr. John T. Macdonald Foundation, Department of Human Genetics, and John P. Hussman Institute for Human Genomics, University of Miami, Miami, Florida.,Department of Otolaryngology, Xiangya Hospital, Central South University, Changsha, Hunan, China
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19
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Heissler SM, Sellers JR. Various Themes of Myosin Regulation. J Mol Biol 2016; 428:1927-46. [PMID: 26827725 DOI: 10.1016/j.jmb.2016.01.022] [Citation(s) in RCA: 84] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2015] [Revised: 01/12/2016] [Accepted: 01/19/2016] [Indexed: 10/24/2022]
Abstract
Members of the myosin superfamily are actin-based molecular motors that are indispensable for cellular homeostasis. The vast functional and structural diversity of myosins accounts for the variety and complexity of the underlying allosteric regulatory mechanisms that determine the activation or inhibition of myosin motor activity and enable precise timing and spatial aspects of myosin function at the cellular level. This review focuses on the molecular basis of posttranslational regulation of eukaryotic myosins from different classes across species by allosteric intrinsic and extrinsic effectors. First, we highlight the impact of heavy and light chain phosphorylation. Second, we outline intramolecular regulatory mechanisms such as autoinhibition and subsequent activation. Third, we discuss diverse extramolecular allosteric mechanisms ranging from actin-linked regulatory mechanisms to myosin:cargo interactions. At last, we briefly outline the allosteric regulation of myosins with synthetic compounds.
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Affiliation(s)
- Sarah M Heissler
- Laboratory of Molecular Physiology, National Heart, Lung and Blood Institute, National Institutes of Health, 50 South Drive, B50/3529, Bethesda, MD 20892-8015, USA.
| | - James R Sellers
- Laboratory of Molecular Physiology, National Heart, Lung and Blood Institute, National Institutes of Health, 50 South Drive, B50/3529, Bethesda, MD 20892-8015, USA
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20
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Liu H, Li J, Raval MH, Yao N, Deng X, Lu Q, Nie S, Feng W, Wan J, Yengo CM, Liu W, Zhang M. Myosin III-mediated cross-linking and stimulation of actin bundling activity of Espin. eLife 2016; 5. [PMID: 26785147 PMCID: PMC4758956 DOI: 10.7554/elife.12856] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2015] [Accepted: 01/18/2016] [Indexed: 11/13/2022] Open
Abstract
Class III myosins (Myo3) and actin-bundling protein Espin play critical roles in regulating the development and maintenance of stereocilia in vertebrate hair cells, and their defects cause hereditary hearing impairments. Myo3 interacts with Espin1 through its tail homology I motif (THDI), however it is not clear how Myo3 specifically acts through Espin1 to regulate the actin bundle assembly and stabilization. Here we discover that Myo3 THDI contains a pair of repeat sequences capable of independently and strongly binding to the ankyrin repeats of Espin1, revealing an unexpected Myo3-mediated cross-linking mechanism of Espin1. The structures of Myo3 in complex with Espin1 not only elucidate the mechanism of the binding, but also reveal a Myo3-induced release of Espin1 auto-inhibition mechanism. We also provide evidence that Myo3-mediated cross-linking can further promote actin fiber bundling activity of Espin1.
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Affiliation(s)
- Haiyang Liu
- Shenzhen Key Laboratory for Neuronal Structural Biology, Biomedical Research Institute, Shenzhen Peking University-The Hong Kong University of Science and Technology Medical Center, Shenzhen, China
| | - Jianchao Li
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Hong Kong, China
| | - Manmeet H Raval
- Department of Cellular and Molecular Physiology, Pennsylvania State University College of Medicine, Hershey, United States
| | - Ningning Yao
- Shenzhen Key Laboratory for Neuronal Structural Biology, Biomedical Research Institute, Shenzhen Peking University-The Hong Kong University of Science and Technology Medical Center, Shenzhen, China
| | - Xiaoying Deng
- Shenzhen Key Laboratory for Neuronal Structural Biology, Biomedical Research Institute, Shenzhen Peking University-The Hong Kong University of Science and Technology Medical Center, Shenzhen, China
| | - Qing Lu
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Hong Kong, China
| | - Si Nie
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Wei Feng
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Jun Wan
- Shenzhen Key Laboratory for Neuronal Structural Biology, Biomedical Research Institute, Shenzhen Peking University-The Hong Kong University of Science and Technology Medical Center, Shenzhen, China.,Division of Life Science, State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Hong Kong, China
| | - Christopher M Yengo
- Department of Cellular and Molecular Physiology, Pennsylvania State University College of Medicine, Hershey, United States
| | - Wei Liu
- Shenzhen Key Laboratory for Neuronal Structural Biology, Biomedical Research Institute, Shenzhen Peking University-The Hong Kong University of Science and Technology Medical Center, Shenzhen, China.,Division of Life Science, State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Hong Kong, China
| | - Mingjie Zhang
- Shenzhen Key Laboratory for Neuronal Structural Biology, Biomedical Research Institute, Shenzhen Peking University-The Hong Kong University of Science and Technology Medical Center, Shenzhen, China.,Division of Life Science, State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, 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, Hong Kong, China
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21
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Yochelis A, Ebrahim S, Millis B, Cui R, Kachar B, Naoz M, Gov NS. Self-organization of waves and pulse trains by molecular motors in cellular protrusions. Sci Rep 2015; 5:13521. [PMID: 26335545 PMCID: PMC4558574 DOI: 10.1038/srep13521] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2015] [Accepted: 07/29/2015] [Indexed: 11/13/2022] Open
Abstract
Actin-based cellular protrusions are an ubiquitous feature of cells, performing a variety of critical functions ranging from cell-cell communication to cell motility. The formation and maintenance of these protrusions relies on the transport of proteins via myosin motors, to the protrusion tip. While tip-directed motion leads to accumulation of motors (and their molecular cargo) at the protrusion tip, it is observed that motors also form rearward moving, periodic and isolated aggregates. The origins and mechanisms of these aggregates, and whether they are important for the recycling of motors, remain open puzzles. Motivated by novel myosin-XV experiments, a mass conserving reaction-diffusion-advection model is proposed. The model incorporates a non-linear cooperative interaction between motors, which converts them between an active and an inactive state. Specifically, the type of aggregate formed (traveling waves or pulse-trains) is linked to the kinetics of motors at the protrusion tip which is introduced by a boundary condition. These pattern selection mechanisms are found not only to qualitatively agree with empirical observations but open new vistas to the transport phenomena by molecular motors in general.
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Affiliation(s)
- A Yochelis
- Department of Solar Energy and Environmental Physics, Swiss Institute for Dryland Environmental and Energy Research, Blaustein Institutes for Desert Research (BIDR), Ben-Gurion University of the Negev, Sede Boqer Campus, Midreshet Ben-Gurion 84990, Israel
| | - S Ebrahim
- Laboratory of Cell Structure and Dynamics, NIDCD, National Institutes of Health, 50 South Drive, Bethesda, MD 20892-8027, USA
| | - B Millis
- Laboratory of Cell Structure and Dynamics, NIDCD, National Institutes of Health, 50 South Drive, Bethesda, MD 20892-8027, USA
| | - R Cui
- Laboratory of Cell Structure and Dynamics, NIDCD, National Institutes of Health, 50 South Drive, Bethesda, MD 20892-8027, USA
| | - B Kachar
- Laboratory of Cell Structure and Dynamics, NIDCD, National Institutes of Health, 50 South Drive, Bethesda, MD 20892-8027, USA
| | - M Naoz
- Department of Chemical Physics, Weizmann Institute of Science, P.O.B. 26, Rehovot, Israel 76100
| | - N S Gov
- Department of Chemical Physics, Weizmann Institute of Science, P.O.B. 26, Rehovot, Israel 76100
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22
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Hersch M, Hachet O, Dalessi S, Ullal P, Bhatia P, Bergmann S, Martin SG. Pom1 gradient buffering through intermolecular auto-phosphorylation. Mol Syst Biol 2015; 11:818. [PMID: 26150232 PMCID: PMC4547846 DOI: 10.15252/msb.20145996] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Concentration gradients provide spatial information for tissue patterning and cell organization, and their robustness under natural fluctuations is an evolutionary advantage. In rod-shaped Schizosaccharomyces pombe cells, the DYRK-family kinase Pom1 gradients control cell division timing and placement. Upon dephosphorylation by a Tea4-phosphatase complex, Pom1 associates with the plasma membrane at cell poles, where it diffuses and detaches upon auto-phosphorylation. Here, we demonstrate that Pom1 auto-phosphorylates intermolecularly, both in vitro and in vivo, which confers robustness to the gradient. Quantitative imaging reveals this robustness through two system's properties: The Pom1 gradient amplitude is inversely correlated with its decay length and is buffered against fluctuations in Tea4 levels. A theoretical model of Pom1 gradient formation through intermolecular auto-phosphorylation predicts both properties qualitatively and quantitatively. This provides a telling example where gradient robustness through super-linear decay, a principle hypothesized a decade ago, is achieved through autocatalysis. Concentration-dependent autocatalysis may be a widely used simple feedback to buffer biological activities.
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Affiliation(s)
- Micha Hersch
- Department of Medical Genetics, University of Lausanne, Lausanne, Switzerland Swiss Institute of Bioinformatics, Lausanne, Switzerland
| | - Olivier Hachet
- Department of Fundamental Microbiology, University of Lausanne, Lausanne, Switzerland
| | - Sascha Dalessi
- Department of Medical Genetics, University of Lausanne, Lausanne, Switzerland Swiss Institute of Bioinformatics, Lausanne, Switzerland
| | - Pranav Ullal
- Department of Fundamental Microbiology, University of Lausanne, Lausanne, Switzerland
| | - Payal Bhatia
- Department of Fundamental Microbiology, University of Lausanne, Lausanne, Switzerland
| | - Sven Bergmann
- Department of Medical Genetics, University of Lausanne, Lausanne, Switzerland Swiss Institute of Bioinformatics, Lausanne, Switzerland
| | - Sophie G Martin
- Department of Fundamental Microbiology, University of Lausanne, Lausanne, Switzerland
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23
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Mecklenburg KL, Freed SA, Raval M, Quintero OA, Yengo CM, O'Tousa JE. Invertebrate and vertebrate class III myosins interact with MORN repeat-containing adaptor proteins. PLoS One 2015; 10:e0122502. [PMID: 25822849 PMCID: PMC4379085 DOI: 10.1371/journal.pone.0122502] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2014] [Accepted: 02/18/2015] [Indexed: 12/22/2022] Open
Abstract
In Drosophila photoreceptors, the NINAC-encoded myosin III is found in a complex with a small, MORN-repeat containing, protein Retinophilin (RTP). Expression of these two proteins in other cell types showed NINAC myosin III behavior is altered by RTP. NINAC deletion constructs were used to map the RTP binding site within the proximal tail domain of NINAC. In vertebrates, the RTP ortholog is MORN4. Co-precipitation experiments demonstrated that human MORN4 binds to human myosin IIIA (MYO3A). In COS7 cells, MORN4 and MYO3A, but not MORN4 and MYO3B, co-localize to actin rich filopodia extensions. Deletion analysis mapped the MORN4 binding to the proximal region of the MYO3A tail domain. MYO3A dependent MORN4 tip localization suggests that MYO3A functions as a motor that transports MORN4 to the filopodia tips and MORN4 may enhance MYO3A tip localization by tethering it to the plasma membrane at the protrusion tips. These results establish conserved features of the RTP/MORN4 family: they bind within the tail domain of myosin IIIs to control their behavior.
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Affiliation(s)
- Kirk L. Mecklenburg
- Department of Biology, Indiana University South Bend, South Bend, Indiana, United States of America
| | - Stephanie A. Freed
- Department of Biological Sciences, University of Notre Dame, Notre Dame, Indiana, United States of America
| | - Manmeet Raval
- Department of Cellular and Molecular Physiology, Pennsylvania State University, College of Medicine, Hershey, Pennsylvania, United States of America
| | - Omar A. Quintero
- Department of Biology, University of Richmond, Richmond, Virginia, United States of America
| | - Christopher M. Yengo
- Department of Cellular and Molecular Physiology, Pennsylvania State University, College of Medicine, Hershey, Pennsylvania, United States of America
- * E-mail: (CY); (JO)
| | - Joseph. E. O'Tousa
- Department of Biological Sciences, University of Notre Dame, Notre Dame, Indiana, United States of America
- * E-mail: (CY); (JO)
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24
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Doherty K, Meere M, Piiroinen PT. Some mathematical models of intermolecular autophosphorylation. J Theor Biol 2015; 370:27-38. [PMID: 25636493 DOI: 10.1016/j.jtbi.2015.01.015] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2014] [Revised: 01/08/2015] [Accepted: 01/15/2015] [Indexed: 11/26/2022]
Abstract
Intermolecular autophosphorylation refers to the process whereby a molecule of an enzyme phosphorylates another molecule of the same enzyme. The enzyme thereby catalyses its own phosphorylation. In the present paper, we develop two generic models of intermolecular autophosphorylation that also include dephosphorylation by a phosphatase of constant concentration. The first of these, a solely time-dependent model, is written as one ordinary differential equation that relies upon mass-action and Michaelis-Menten kinetics. Beginning with the enzyme in its dephosphorylated state, it predicts a lag before the enzyme becomes significantly phosphorylated, for suitable parameter values. It also predicts that there exists a threshold concentration for the phosphorylation of enzyme and that for suitable parameter values, a continuous or discontinuous switch in the phosphorylation of enzyme are possible. The model developed here has the advantage that it is relatively easy to analyse compared with most existing models for autophosphorylation and can qualitatively describe many different systems. We also extend our time-dependent model of autophosphorylation to include a spatial dependence, as well as localised binding reactions. This spatio-temporal model consists of a system of partial differential equations that describe a soluble autophosphorylating enzyme in a spherical geometry. We use the spatio-temporal model to describe the phosphorylation of an enzyme throughout the cell due to an increase in local concentration by binding. Using physically realistic values for model parameters, our results provide a proof-of-concept of the process of activation by local concentration and suggest that, in the presence of a phosphatase, this activation can be irreversible.
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Affiliation(s)
- Kevin Doherty
- School of Mathematics, Statistics and Applied Mathematics, National University of Ireland, Galway, University Road, Galway, Ireland; AgroParisTech, CRNH-IdF, UMR914, Nutrition Physiology and Ingestive Behavior, F-75005 Paris, France; INRA, CRNH-IdF, UMR914 Nutrition Physiology and Ingestive Behavior, F-75005 Paris, France.
| | - Martin Meere
- School of Mathematics, Statistics and Applied Mathematics, National University of Ireland, Galway, University Road, Galway, Ireland.
| | - Petri T Piiroinen
- School of Mathematics, Statistics and Applied Mathematics, National University of Ireland, Galway, University Road, Galway, Ireland.
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25
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Lapin V, Shirdel EA, Wei X, Mason JM, Jurisica I, Mak TW. Kinome-wide screening of HER2+ breast cancer cells for molecules that mediate cell proliferation or sensitize cells to trastuzumab therapy. Oncogenesis 2014; 3:e133. [PMID: 25500906 PMCID: PMC4275559 DOI: 10.1038/oncsis.2014.45] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2014] [Accepted: 08/19/2014] [Indexed: 01/18/2023] Open
Abstract
Understanding the signaling differences that distinguish human HER2-amplified (HER2-positive (HER2+)) breast cancers from other breast cancer subtypes may help to identify protein drug targets for the specific treatment of HER2+ breast cancers. We performed two kinome-wide small interfering RNA (siRNA) screens on five HER2+ breast cancer cell lines, seven breast cancer cell lines in which HER2 was not amplified and two normal breast cell lines. To pinpoint the main kinases driving HER2 signaling, we performed a comprehensive siRNA screen that identified loss of the HER2/HER3 heterodimer as having the most prominent inhibitory effect on the growth of HER2+ breast cancer cells. In a second siRNA screen focused on identifying genes that could sensitize HER2+ cells to trastuzumab treatment, we found that loss of signaling members downstream of phosphatidylinositol 3 kinase (PI3K) potentiated the growth inhibitory effects of trastuzumab. Loss of HER2 and HER3, as well as proteins involved in mitogenic and environmental stress pathways inhibited the proliferation of HER2+ cells only in the absence of trastuzumab, suggesting that these pathways are inhibited by trastuzumab treatment. Loss of essential G2/M cell cycle mediators or proteins involved in vesicle organization exerted inhibitory effects on HER2+ cell growth that were unaffected by trastuzumab. Furthermore, the use of a sensitization index (SI) identified targeting the PI3K pathway to sensitize to trastuzumab treatment. Antagonism using the SI identified MYO3A, MYO3B and MPZL1 as antagonizers to trastuzumab treatment among HER2+ cell lines. Our results suggest that the dimerization partners of HER2 are important for determining the activation of downstream proliferation pathways. Understanding the complex layers of signaling triggered downstream of HER2 homodimers and heterodimers will facilitate the selection of better targets for combination therapies intended to treat HER2+ breast cancers.
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Affiliation(s)
- V Lapin
- 1] Campbell Family Institute for Breast Cancer Research, Toronto, Ontario, Canada [2] Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada
| | - E A Shirdel
- 1] Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada [2] Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario, Canada
| | - X Wei
- Campbell Family Institute for Breast Cancer Research, Toronto, Ontario, Canada
| | - J M Mason
- Campbell Family Institute for Breast Cancer Research, Toronto, Ontario, Canada
| | - I Jurisica
- 1] Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada [2] Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario, Canada
| | - T W Mak
- 1] Campbell Family Institute for Breast Cancer Research, Toronto, Ontario, Canada [2] Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada
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26
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An BC, Sakai T, Komaba S, Kishi H, Kobayashi S, Kim JY, Ikebe R, Ikebe M. Phosphorylation of the kinase domain regulates autophosphorylation of myosin IIIA and its translocation in microvilli. Biochemistry 2014; 53:7835-45. [PMID: 25402663 PMCID: PMC4270376 DOI: 10.1021/bi501247z] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
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Motor activity of myosin III is regulated
by autophosphorylation.
To investigate the role of the kinase activity on the transporter
function of myosin IIIA (Myo3A), we identified the phosphorylation
sites of kinase domain (KD), which is responsible for the regulation
of kinase activity and thus motor function. Using mass spectrometry,
we identified six phosphorylation sites in the KD, which are highly
conserved among class III myosins and Ste20-related misshapen (Msn)
kinases. Two predominant sites, Thr184 and Thr188, in KD are important for phosphorylation of the KD as well as the
motor domain, which regulates the affinity for actin. In the Caco2
cells, the full-length human Myo3A (hMyo3AFull) markedly enlarged
the microvilli, although it did not show discrete localization within
the microvilli. On the other hand, hMyo3AFull(T184A) and hMyo3AFull(T188A)
both showed clear localization at the microvilli tips. Our results
suggest that Myo3A induces large actin bundle formation to form microvilli,
and phosphorylation of KD at Thr184 and Thr188 is critical for the kinase activity of Myo3A, and regulation of
Myo3A translocation to the tip of microvilli. Retinal extracts potently
dephosphorylate both KD and motor domain without IQ motifs (MDIQo),
which was inhibited by okadaic acid (OA) with nanomolar range and
by tautomycetin (TMC) with micromolar range. The results suggest that
Myo3A phosphatase is protein phosphatase type 2A (PP2A). Supporting
this result, recombinant PP2Ac potently dephosphorylates both KD and
MDIQo. We propose that the phosphorylation–dephosphorylation
mechanism plays an essential role in mediating the transport and actin
bundle formation and stability functions of hMyo3A.
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Affiliation(s)
- Byung Chull An
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School , Worcester, Massachusetts 01605, United States
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27
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Effertz T, Scharr AL, Ricci AJ. The how and why of identifying the hair cell mechano-electrical transduction channel. Pflugers Arch 2014; 467:73-84. [PMID: 25241775 DOI: 10.1007/s00424-014-1606-z] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2014] [Revised: 08/28/2014] [Accepted: 09/01/2014] [Indexed: 01/10/2023]
Abstract
Identification of the auditory hair cell mechano-electrical transduction (hcMET) channel has been a major focus in the hearing research field since the 1980s when direct mechanical gating of a transduction channel was proposed (Corey and Hudspeth J Neurosci 3:962-976, 1983). To this day, the molecular identity of this channel remains controversial. However, many of the hcMET channel's properties have been characterized, including pore properties, calcium-dependent ion permeability, rectification, and single channel conductance. At this point, elucidating the molecular identity of the hcMET channel will provide new tools for understanding the mechanotransduction process. This review discusses the significance of identifying the hcMET channel, the difficulties associated with that task, as well as the establishment of clear criteria for this identification. Finally, we discuss potential candidate channels in light of these criteria.
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Affiliation(s)
- Thomas Effertz
- Department of Otolaryngology, School of Medicine, Stanford University, Stanford, CA, 94305, USA
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28
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Cox-Limpens KEM, Gavilanes AWD, Zimmermann LJI, Vles JSH. Endogenous brain protection: what the cerebral transcriptome teaches us. Brain Res 2014; 1564:85-100. [PMID: 24713346 DOI: 10.1016/j.brainres.2014.04.001] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2013] [Revised: 03/23/2014] [Accepted: 04/01/2014] [Indexed: 02/04/2023]
Abstract
Despite efforts to reduce mortality caused by stroke and perinatal asphyxia, these are still the 2nd largest cause of death worldwide in the age groups they affect. Furthermore, survivors of cerebral hypoxia-ischemia often suffer neurological morbidities. A better understanding of pathophysiological mechanisms in focal and global brain ischemia will contribute to the development of tailored therapeutic strategies. Similarly, insight into molecular pathways involved in preconditioning-induced brain protection will provide possibilities for future treatment. Microarray technology is a great tool for investigating large scale gene expression, and has been used in many experimental studies of cerebral ischemia and preconditioning to unravel molecular (patho-) physiology. However, the amount of data across microarray studies can be daunting and hard to interpret which is why we aim to provide a clear overview of available data in experimental rodent models. Findings for both injurious ischemia and preconditioning are reviewed under separate subtopics such as cellular stress, inflammation, cytoskeleton and cell signaling. Finally, we investigated the transcriptome signature of brain protection across preconditioning studies in search of transcripts that were expressed similarly across studies. Strikingly, when comparing genes discovered by single-gene analysis we observed only 15 genes present in two studies or more. We subjected these 15 transcripts to DAVID Annotation Clustering analysis to derive their shared biological meaning. Interestingly, the MAPK signaling pathway and more specifically the ERK1/2 pathway geared toward cell survival/proliferation was significantly enriched. To conclude, we advocate incorporating pathway analysis into all microarray data analysis in order to improve the detection of similarities between independently derived datasets.
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Affiliation(s)
- K E M Cox-Limpens
- School for Mental Health and Neuroscience (MHeNS), Maastricht University, Universiteitssingel 50, 6200 MD Maastricht, The Netherlands; Department of Pediatrics, Maastricht University Medical Center (MUMC), postbus 5800, 6202 AZ Maastricht, The Netherlands.
| | - A W D Gavilanes
- Department of Pediatrics, Maastricht University Medical Center (MUMC), postbus 5800, 6202 AZ Maastricht, The Netherlands.
| | - L J I Zimmermann
- Department of Pediatrics, Maastricht University Medical Center (MUMC), postbus 5800, 6202 AZ Maastricht, The Netherlands.
| | - J S H Vles
- Department of Pediatric Neurology, Maastricht University Medical Center (MUMC), P.Debyelaan 25, 6229 HX Maastricht, The Netherlands.
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29
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Quintero OA, Unrath WC, Stevens SM, Manor U, Kachar B, Yengo CM. Myosin 3A kinase activity is regulated by phosphorylation of the kinase domain activation loop. J Biol Chem 2013; 288:37126-37. [PMID: 24214986 DOI: 10.1074/jbc.m113.511014] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Class III myosins are unique members of the myosin superfamily in that they contain both a motor and kinase domain. We have found that motor activity is decreased by autophosphorylation, although little is known about the regulation of the kinase domain. We demonstrate by mass spectrometry that Thr-178 and Thr-184 in the kinase domain activation loop and two threonines in the loop 2 region of the motor domain are autophosphorylated (Thr-908 and Thr-919). The kinase activity of MYO3A 2IQ with the phosphomimic (T184E) or phosphoblock (T184A) mutations demonstrates that kinase activity is reduced 30-fold as a result of the T184A mutation, although the Thr-178 site only had a minor impact on kinase activity. Interestingly, the actin-activated ATPase activity of MYO3A 2IQ is slightly reduced as a result of the T178A and T184A mutations suggesting coupling between motor and kinase domains. Full-length GFP-tagged T184A and T184E MYO3A constructs transfected into COS7 cells do not disrupt the ability of MYO3A to localize to filopodia structures. In addition, we demonstrate that T184E MYO3A reduces filopodia elongation in the presence of espin-1, whereas T184A enhances filopodia elongation in a similar fashion to kinase-dead MYO3A. Our results suggest that as MYO3A accumulates at the tips of actin protrusions, autophosphorylation of Thr-184 enhances kinase activity resulting in phosphorylation of the MYO3A motor and reducing motor activity. The differential regulation of the kinase and motor activities allows for MYO3A to precisely self-regulate its concentration in the actin bundle-based structures of cells.
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Affiliation(s)
- Omar A Quintero
- From the Department of Cellular and Molecular Physiology, Pennsylvania State University College of Medicine, Hershey, Pennsylvania 17033
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30
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Preller M, Manstein D. Myosin Structure, Allostery, and Mechano-Chemistry. Structure 2013; 21:1911-22. [DOI: 10.1016/j.str.2013.09.015] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2013] [Revised: 09/19/2013] [Accepted: 09/25/2013] [Indexed: 01/10/2023]
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31
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Pinkoviezky I, Gov NS. Transport dynamics of molecular motors that switch between an active and inactive state. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2013; 88:022714. [PMID: 24032871 DOI: 10.1103/physreve.88.022714] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2013] [Revised: 06/11/2013] [Indexed: 06/02/2023]
Abstract
Molecular motors are involved in key transport processes in the cell. Many of these motors can switch from an active to a nonactive state, either spontaneously or depending on their interaction with other molecules. When active, the motors move processively along the filaments, while when inactive they are stationary. We treat here the simple case of spontaneously switching motors, between the active and inactive states, along an open linear track. We use our recent analogy with vehicular traffic, where we go beyond the mean-field description. We map the phase diagram of this system, and find that it clearly breaks the symmetry between the different phases, as compared to the standard total asymmetric exclusion process. We make several predictions that may be testable using molecular motors in vitro and in living cells.
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Affiliation(s)
- I Pinkoviezky
- Department of Chemical Physics, Weizmann Institute of Science, P.O. Box 26, Rehovot, Israel 76100
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32
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Ben Isaac E, Manor U, Kachar B, Yochelis A, Gov NS. Linking actin networks and cell membrane via a reaction-diffusion-elastic description of nonlinear filopodia initiation. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2013; 88:022718. [PMID: 24032875 DOI: 10.1103/physreve.88.022718] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2012] [Revised: 07/08/2013] [Indexed: 06/02/2023]
Abstract
Reaction-diffusion models have been used to describe pattern formation on the cellular scale, and traditionally do not include feedback between cellular shape changes and biochemical reactions. We introduce here a distinct reaction-diffusion-elasticity approach: The reaction-diffusion part describes bistability between two actin orientations, coupled to the elastic energy of the cell membrane deformations. This coupling supports spatially localized patterns, even when such solutions do not exist in the uncoupled self-inhibited reaction-diffusion system. We apply this concept to describe the nonlinear (threshold driven) initiation mechanism of actin-based cellular protrusions and provide support by several experimental observations.
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Affiliation(s)
- Eyal Ben Isaac
- Department of Chemical Physics, Weizmann Institute of Science, Rehovot 76100, Israel
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33
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Manor U, Grati M, Yengo CM, Kachar B, Gov NS. Competition and compensation: dissecting the biophysical and functional differences between the class 3 myosin paralogs, myosins 3a and 3b. BIOARCHITECTURE 2012; 2:171-4. [PMID: 22954581 PMCID: PMC3696061 DOI: 10.4161/bioa.21733] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Stereocilia are actin protrusions with remarkably well-defined lengths and organization. A flurry of recent papers has reported multiple myosin motor proteins involved in regulating stereocilia structures by transporting actin-regulatory cargo to the tips of stereocilia.1-13 In our recent paper, we show that two paralogous class 3 myosins — Myo3a and Myo3b — both transport the actin-regulatory protein Espin 1 (Esp1) to stereocilia and filopodia tips in a remarkably similar, albeit non-identical fashion.1 Here we present experimental and computational data that suggests that subtle differences between these two proteins’ biophysical and biochemical properties can help us understand how these myosin species target and regulate the lengths of actin protrusions.
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Affiliation(s)
- Uri Manor
- Laboratory of Cell Structure and Dynamics; National Institute on Deafness and Other Communication Disorders; National Institutes of Health; Bethesda, MD USA
| | - M'hamed Grati
- Laboratory of Cell Structure and Dynamics; National Institute on Deafness and Other Communication Disorders; National Institutes of Health; Bethesda, MD USA
| | - Christopher M Yengo
- Department of Cellular and Molecular Physiology; Penn State College of Medicine; Hershey, PA USA
| | - Bechara Kachar
- Laboratory of Cell Structure and Dynamics; National Institute on Deafness and Other Communication Disorders; National Institutes of Health; Bethesda, MD USA
| | - Nir S Gov
- Department of Chemical Physics; Weizmann Institute of Science; Rehovot, Israel
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34
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Myosin IIIB uses an actin-binding motif in its espin-1 cargo to reach the tips of actin protrusions. Curr Biol 2012; 22:320-5. [PMID: 22264607 DOI: 10.1016/j.cub.2011.12.053] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2011] [Revised: 11/01/2011] [Accepted: 12/22/2011] [Indexed: 11/22/2022]
Abstract
Myosin IIIA (MYO3A) targets actin protrusion tips using a motility mechanism dependent on both motor and tail actin-binding activity [1]. We show that myosin IIIB (MYO3B) lacks tail actin-binding activity and is unable to target COS7 cell filopodia tips, yet is somehow able to target stereocilia tips. Strikingly, when MYO3B is coexpressed with espin-1 (ESPN1), a MYO3A cargo protein endogenously expressed in stereocilia [2], MYO3B targets and carries ESPN1 to COS7 filopodia tips. We show that this tip localization is lost when we remove the ESPN1 C terminus actin-binding site. We also demonstrate that, like MYO3A [2], MYO3B can elongate filopodia by transporting ESPN1 to the polymerizing end of actin filaments. The mutual dependence of MYO3B and ESPN1 for tip localization reveals a novel mechanism for the cell to regulate myosin tip localization via a reciprocal relationship with cargo that directly participates in actin binding for motility. Our results are consistent with a novel form of motility for class III myosins that requires both motor and tail domain actin-binding activity and show that the actin-binding tail can be replaced by actin-binding cargo. This study also provides a framework to better understand the late-onset hearing loss phenotype in patients with MYO3A mutations.
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35
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Dalal JS, Stevens SM, Alvarez S, Munoz N, Kempler KE, Dosé AC, Burnside B, Battelle BA. Mouse class III myosins: kinase activity and phosphorylation sites. J Neurochem 2011; 119:772-84. [PMID: 21895655 DOI: 10.1111/j.1471-4159.2011.07468.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
As class III unconventional myosins are motor proteins with an N-terminal kinase domain, it seems likely they play a role in both signaling and actin based transport. A growing body of evidence indicates that the motor functions of human class IIIA myosin, which has been implicated in progressive hearing loss, are modulated by intermolecular autophosphorylation. However, the phosphorylation sites have not been identified. We studied the kinase activity and phosphorylation sites of mouse class III myosins, mMyo3A and 3B, which are highly similar to their human orthologs. We demonstrate that the kinase domains of mMyo3A and 3B are active kinases, and that they have similar, if not identical, substrate specificities. We show that the kinase domains of these proteins autophosphorylate, and that they can phosphorylate sites within their myosin and tail domains. Using liquid chromatography-mass spectrometry, we identified phosphorylated sites in the kinase, myosin motor and tail domains of both mMyo3A and 3B. Most of the phosphorylated sites we identified and their consensus phosphorylation motifs are highly conserved among vertebrate class III myosins, including human class III myosins. Our findings are a major step toward understanding how the functions of class III myosins are regulated by phosphorylation.
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Affiliation(s)
- Jasbir S Dalal
- Department of Molecular and Cell Biology, University of California, Berkeley, California, USA
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36
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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: 123] [Impact Index Per Article: 9.5] [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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