1
|
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.
Collapse
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
| |
Collapse
|
2
|
Sharkova M, Aparicio G, Mouzaaber C, Zolessi FR, Hocking JC. Photoreceptor calyceal processes accompany the developing outer segment, adopting a stable length despite a dynamic core. J Cell Sci 2024; 137:jcs261721. [PMID: 38477343 PMCID: PMC11058337 DOI: 10.1242/jcs.261721] [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: 10/16/2023] [Accepted: 03/04/2024] [Indexed: 03/14/2024] Open
Abstract
Vertebrate photoreceptors detect light through a large cilium-based outer segment, which is filled with photopigment-laden membranous discs. Surrounding the base of the outer segment are microvilli-like calyceal processes (CPs). Although CP disruption has been associated with altered outer segment morphology and photoreceptor degeneration, the role of the CPs remains elusive. Here, we used zebrafish as a model to characterize CPs. We quantified CP parameters and report a strong disparity in outer segment coverage between photoreceptor subtypes. CP length is stable across light and dark conditions, yet heat-shock inducible expression of tagged actin revealed rapid turnover of the CP actin core. Detailed imaging of the embryonic retina uncovered substantial remodeling of the developing photoreceptor apical surface, including a transition from dynamic tangential processes to vertically oriented CPs immediately prior to outer segment formation. Remarkably, we also found a direct connection between apical extensions of the Müller glia and retinal pigment epithelium, arranged as bundles around the ultraviolet sensitive cones. In summary, our data characterize the structure, development and surrounding environment of photoreceptor microvilli in the zebrafish retina.
Collapse
Affiliation(s)
- Maria Sharkova
- Department of Cell Biology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - Gonzalo Aparicio
- Sección Biología Celular, Facultad de Ciencias, Universidad de la República, 11400, Uruguay
- Institut Pasteur Montevideo, Uruguay
| | - Constantin Mouzaaber
- Department of Cell Biology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - Flavio R. Zolessi
- Sección Biología Celular, Facultad de Ciencias, Universidad de la República, 11400, Uruguay
- Institut Pasteur Montevideo, Uruguay
| | - Jennifer C. Hocking
- Department of Cell Biology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
- Division of Anatomy, Department of Surgery, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta T6G 2H7, Canada
- Department of Medical Genetics, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
- Women and Children's Health Research Institute, University of Alberta, Edmonton, Alberta, Canada
| |
Collapse
|
3
|
Ciampi L, Serrano L, Irimia M. Unique transcriptomes of sensory and non-sensory neurons: insights from Splicing Regulatory States. Mol Syst Biol 2024; 20:296-310. [PMID: 38438733 PMCID: PMC10987577 DOI: 10.1038/s44320-024-00020-1] [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: 10/31/2023] [Revised: 01/04/2024] [Accepted: 01/12/2024] [Indexed: 03/06/2024] Open
Abstract
Alternative Splicing (AS) programs serve as instructive signals of cell type specificity, particularly within the brain, which comprises dozens of molecularly and functionally distinct cell types. Among them, retinal photoreceptors stand out due to their unique transcriptome, making them a particularly well-suited system for studying how AS shapes cell type-specific molecular functions. Here, we use the Splicing Regulatory State (SRS) as a novel framework to discuss the splicing factors governing the unique AS pattern of photoreceptors, and how this pattern may aid in the specification of their highly specialized sensory cilia. In addition, we discuss how other sensory cells with ciliated structures, for which data is much scarcer, also rely on specific SRSs to implement a proteome specialized in the detection of sensory stimuli. By reviewing the general rules of cell type- and tissue-specific AS programs, firstly in the brain and subsequently in specialized sensory neurons, we propose a novel paradigm on how SRSs are established and how they can diversify. Finally, we illustrate how SRSs shape the outcome of mutations in splicing factors to produce cell type-specific phenotypes that can lead to various human diseases.
Collapse
Affiliation(s)
- Ludovica Ciampi
- Center for Genomic Regulation, Barcelona Institute of Science and Technology, Barcelona, Spain.
| | - Luis Serrano
- Center for Genomic Regulation, Barcelona Institute of Science and Technology, Barcelona, Spain.
- Universitat Pompeu Fabra, Barcelona, Spain.
- ICREA, Barcelona, Spain.
| | - Manuel Irimia
- Center for Genomic Regulation, Barcelona Institute of Science and Technology, Barcelona, Spain.
- Universitat Pompeu Fabra, Barcelona, Spain.
- ICREA, Barcelona, Spain.
| |
Collapse
|
4
|
Mendia C, Peineau T, Zamani M, Felgerolle C, Yahiaoui N, Christophersen N, Papal S, Maudoux A, Maroofian R, Patni P, Nouaille S, Bowl MR, Delmaghani S, Galehdari H, Vona B, Dulon D, Vitry S, El-Amraoui A. Clarin-2 gene supplementation durably preserves hearing in a model of progressive hearing loss. Mol Ther 2024; 32:800-817. [PMID: 38243601 PMCID: PMC10928142 DOI: 10.1016/j.ymthe.2024.01.021] [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: 10/20/2023] [Revised: 12/22/2023] [Accepted: 01/12/2024] [Indexed: 01/21/2024] Open
Abstract
Hearing loss is a major health concern affecting millions of people worldwide with currently limited treatment options. In clarin-2-deficient Clrn2-/- mice, used here as a model of progressive hearing loss, we report synaptic auditory abnormalities in addition to the previously demonstrated defects of hair bundle structure and mechanoelectrical transduction. We sought an in-depth evaluation of viral-mediated gene delivery as a therapy for these hearing-impaired mice. Supplementation with either the murine Clrn2 or human CLRN2 genes preserved normal hearing in treated Clrn2-/- mice. Conversely, mutated forms of CLRN2, identified in patients with post-lingual moderate to severe hearing loss, failed to prevent hearing loss. The ectopic expression of clarin-2 successfully prevented the loss of stereocilia, maintained normal mechanoelectrical transduction, preserved inner hair cell synaptic function, and ensured near-normal hearing thresholds over time. Maximal hearing preservation was observed when Clrn2 was delivered prior to the loss of transducing stereocilia. Our findings demonstrate that gene therapy is effective for the treatment of post-lingual hearing impairment and age-related deafness associated with CLRN2 patient mutations.
Collapse
Affiliation(s)
- Clara Mendia
- Institut Pasteur, Université Paris Cité, INSERM AO06, Institut de l'Audition, Unit Progressive Sensory Disorders, Pathophysiology and Therapy, 63 rue de Charenton, 75012 Paris, France; Sorbonne Université, Collège Doctoral, 75005 Paris, France
| | - Thibault Peineau
- Institut de l'Audition and Université de Bordeaux, Laboratoire de Neurophysiologie de la Synapse Auditive, Bordeaux Neurocampus, 33076 Bordeaux, France
| | - Mina Zamani
- Department of Biology, Faculty of Science, Shahid Chamran University of Ahvaz, Ahvaz 6135783151, Iran
| | - Chloé Felgerolle
- Institut Pasteur, Université Paris Cité, INSERM AO06, Institut de l'Audition, Unit Progressive Sensory Disorders, Pathophysiology and Therapy, 63 rue de Charenton, 75012 Paris, France
| | - Nawal Yahiaoui
- Institut Pasteur, Université Paris Cité, INSERM AO06, Institut de l'Audition, Unit Progressive Sensory Disorders, Pathophysiology and Therapy, 63 rue de Charenton, 75012 Paris, France
| | - Nele Christophersen
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, 37075 Göttingen, Germany; Institute of Human Genetics, University Medical Center Göttingen, 37075 Göttingen, Germany
| | - Samantha Papal
- Institut Pasteur, Université Paris Cité, INSERM AO06, Institut de l'Audition, Unit Progressive Sensory Disorders, Pathophysiology and Therapy, 63 rue de Charenton, 75012 Paris, France
| | - Audrey Maudoux
- Institut Pasteur, Université Paris Cité, INSERM AO06, Institut de l'Audition, Unit Progressive Sensory Disorders, Pathophysiology and Therapy, 63 rue de Charenton, 75012 Paris, France
| | - Reza Maroofian
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, University College London, WC1E 6BT London, UK
| | - Pranav Patni
- Institut Pasteur, Université Paris Cité, INSERM AO06, Institut de l'Audition, Unit Progressive Sensory Disorders, Pathophysiology and Therapy, 63 rue de Charenton, 75012 Paris, France
| | - Sylvie Nouaille
- Institut Pasteur, Université Paris Cité, INSERM AO06, Institut de l'Audition, Unit Progressive Sensory Disorders, Pathophysiology and Therapy, 63 rue de Charenton, 75012 Paris, France
| | - Michael R Bowl
- UCL Ear Institute, University College London, 332 Gray's Inn Road, WC1X 8EE London, UK
| | - Sedigheh Delmaghani
- Institut Pasteur, Université Paris Cité, INSERM AO06, Institut de l'Audition, Unit Progressive Sensory Disorders, Pathophysiology and Therapy, 63 rue de Charenton, 75012 Paris, France
| | - Hamid Galehdari
- Department of Biology, Faculty of Science, Shahid Chamran University of Ahvaz, Ahvaz 6135783151, Iran
| | - Barbara Vona
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, 37075 Göttingen, Germany; Institute of Human Genetics, University Medical Center Göttingen, 37075 Göttingen, Germany
| | - Didier Dulon
- Institut de l'Audition and Université de Bordeaux, Laboratoire de Neurophysiologie de la Synapse Auditive, Bordeaux Neurocampus, 33076 Bordeaux, France
| | - Sandrine Vitry
- Institut Pasteur, Université Paris Cité, INSERM AO06, Institut de l'Audition, Unit Progressive Sensory Disorders, Pathophysiology and Therapy, 63 rue de Charenton, 75012 Paris, France.
| | - Aziz El-Amraoui
- Institut Pasteur, Université Paris Cité, INSERM AO06, Institut de l'Audition, Unit Progressive Sensory Disorders, Pathophysiology and Therapy, 63 rue de Charenton, 75012 Paris, France.
| |
Collapse
|
5
|
Hosawi MM, Cheng J, Fankhaenel M, Przewloka MR, Elias S. Interplay between the plasma membrane and cell-cell adhesion maintains epithelial identity for correct polarised cell divisions. J Cell Sci 2024; 137:jcs261701. [PMID: 37888135 PMCID: PMC10729819 DOI: 10.1242/jcs.261701] [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: 10/03/2023] [Accepted: 10/17/2023] [Indexed: 10/28/2023] Open
Abstract
Polarised epithelial cell divisions represent a fundamental mechanism for tissue maintenance and morphogenesis. Morphological and mechanical changes in the plasma membrane influence the organisation and crosstalk of microtubules and actin at the cell cortex, thereby regulating the mitotic spindle machinery and chromosome segregation. Yet, the precise mechanisms linking plasma membrane remodelling to cell polarity and cortical cytoskeleton dynamics to ensure accurate execution of mitosis in mammalian epithelial cells remain poorly understood. Here, we manipulated the density of mammary epithelial cells in culture, which led to several mitotic defects. Perturbation of cell-cell adhesion formation impairs the dynamics of the plasma membrane, affecting the shape and size of mitotic cells and resulting in defects in mitotic progression and the generation of daughter cells with aberrant architecture. In these conditions, F- actin-astral microtubule crosstalk is impaired, leading to mitotic spindle misassembly and misorientation, which in turn contributes to chromosome mis-segregation. Mechanistically, we identify S100 Ca2+-binding protein A11 (S100A11) as a key membrane-associated regulator that forms a complex with E-cadherin (CDH1) and the leucine-glycine-asparagine repeat protein LGN (also known as GPSM2) to coordinate plasma membrane remodelling with E-cadherin-mediated cell adhesion and LGN-dependent mitotic spindle machinery. Thus, plasma membrane-mediated maintenance of mammalian epithelial cell identity is crucial for correct execution of polarised cell divisions, genome maintenance and safeguarding tissue integrity.
Collapse
Affiliation(s)
- Manal M. Hosawi
- School of Biological Sciences, University of Southampton, Southampton SO17 1BJ, UK
- Institute for Life Sciences, University of Southampton, Southampton SO17 1BJ, UK
| | - Jiaoqi Cheng
- School of Biological Sciences, University of Southampton, Southampton SO17 1BJ, UK
- Institute for Life Sciences, University of Southampton, Southampton SO17 1BJ, UK
| | - Maria Fankhaenel
- School of Biological Sciences, University of Southampton, Southampton SO17 1BJ, UK
- Institute for Life Sciences, University of Southampton, Southampton SO17 1BJ, UK
| | - Marcin R. Przewloka
- School of Biological Sciences, University of Southampton, Southampton SO17 1BJ, UK
- Institute for Life Sciences, University of Southampton, Southampton SO17 1BJ, UK
| | - Salah Elias
- School of Biological Sciences, University of Southampton, Southampton SO17 1BJ, UK
- Institute for Life Sciences, University of Southampton, Southampton SO17 1BJ, UK
| |
Collapse
|
6
|
Goode BL, Eskin J, Shekhar S. Mechanisms of actin disassembly and turnover. J Cell Biol 2023; 222:e202309021. [PMID: 37948068 PMCID: PMC10638096 DOI: 10.1083/jcb.202309021] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2023] [Revised: 10/21/2023] [Accepted: 10/23/2023] [Indexed: 11/12/2023] Open
Abstract
Cellular actin networks exhibit a wide range of sizes, shapes, and architectures tailored to their biological roles. Once assembled, these filamentous networks are either maintained in a state of polarized turnover or induced to undergo net disassembly. Further, the rates at which the networks are turned over and/or dismantled can vary greatly, from seconds to minutes to hours or even days. Here, we review the molecular machinery and mechanisms employed in cells to drive the disassembly and turnover of actin networks. In particular, we highlight recent discoveries showing that specific combinations of conserved actin disassembly-promoting proteins (cofilin, GMF, twinfilin, Srv2/CAP, coronin, AIP1, capping protein, and profilin) work in concert to debranch, sever, cap, and depolymerize actin filaments, and to recharge actin monomers for new rounds of assembly.
Collapse
Affiliation(s)
- Bruce L. Goode
- Department of Biology, Rosenstiel Basic Medical Science Research Center, Brandeis University, Waltham, MA, USA
| | - Julian Eskin
- Department of Biology, Rosenstiel Basic Medical Science Research Center, Brandeis University, Waltham, MA, USA
| | - Shashank Shekhar
- Departments of Physics, Cell Biology and Biochemistry, Emory University, Atlanta, GA, USA
| |
Collapse
|
7
|
Lazzeri G, Biagioni F, Ferrucci M, Puglisi-Allegra S, Lenzi P, Busceti CL, Giannessi F, Fornai F. The Relevance of Autophagy within Inner Ear in Baseline Conditions and Tinnitus-Related Syndromes. Int J Mol Sci 2023; 24:16664. [PMID: 38068993 PMCID: PMC10706730 DOI: 10.3390/ijms242316664] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2023] [Revised: 11/07/2023] [Accepted: 11/21/2023] [Indexed: 12/18/2023] Open
Abstract
Tinnitus is the perception of noise in the absence of acoustic stimulation (phantom noise). In most patients suffering from chronic peripheral tinnitus, an alteration of outer hair cells (OHC) starting from the stereocilia (SC) occurs. This is common following ototoxic drugs, sound-induced ototoxicity, and acoustic degeneration. In all these conditions, altered coupling between the tectorial membrane (TM) and OHC SC is described. The present review analyzes the complex interactions involving OHC and TM. These need to be clarified to understand which mechanisms may underlie the onset of tinnitus and why the neuropathology of chronic degenerative tinnitus is similar, independent of early triggers. In fact, the fine neuropathology of tinnitus features altered mechanisms of mechanic-electrical transduction (MET) at the level of OHC SC. The appropriate coupling between OHC SC and TM strongly depends on autophagy. The involvement of autophagy may encompass degenerative and genetic tinnitus, as well as ototoxic drugs and acoustic trauma. Defective autophagy explains mitochondrial alterations and altered protein handling within OHC and TM. This is relevant for developing novel treatments that stimulate autophagy without carrying the burden of severe side effects. Specific phytochemicals, such as curcumin and berberin, acting as autophagy activators, may mitigate the neuropathology of tinnitus.
Collapse
Affiliation(s)
- Gloria Lazzeri
- Human Anatomy, Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, 56126 Pisa, PI, Italy; (G.L.); (M.F.); (P.L.); (F.G.)
| | - Francesca Biagioni
- IRCCS, Istituto di Ricovero e Cura a Carattere Scientifico, Neuromed, 86077 Pozzilli, IS, Italy; (F.B.); (S.P.-A.); (C.L.B.)
| | - Michela Ferrucci
- Human Anatomy, Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, 56126 Pisa, PI, Italy; (G.L.); (M.F.); (P.L.); (F.G.)
| | - Stefano Puglisi-Allegra
- IRCCS, Istituto di Ricovero e Cura a Carattere Scientifico, Neuromed, 86077 Pozzilli, IS, Italy; (F.B.); (S.P.-A.); (C.L.B.)
| | - Paola Lenzi
- Human Anatomy, Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, 56126 Pisa, PI, Italy; (G.L.); (M.F.); (P.L.); (F.G.)
| | - Carla Letizia Busceti
- IRCCS, Istituto di Ricovero e Cura a Carattere Scientifico, Neuromed, 86077 Pozzilli, IS, Italy; (F.B.); (S.P.-A.); (C.L.B.)
| | - Francesco Giannessi
- Human Anatomy, Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, 56126 Pisa, PI, Italy; (G.L.); (M.F.); (P.L.); (F.G.)
| | - Francesco Fornai
- Human Anatomy, Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, 56126 Pisa, PI, Italy; (G.L.); (M.F.); (P.L.); (F.G.)
- IRCCS, Istituto di Ricovero e Cura a Carattere Scientifico, Neuromed, 86077 Pozzilli, IS, Italy; (F.B.); (S.P.-A.); (C.L.B.)
| |
Collapse
|
8
|
Qu J, Qiu B, Zhang Y, Hu Y, Wang Z, Guan Z, Qin Y, Sui T, Wu F, Li B, Han W, Peng X. The tumor-enriched small molecule gambogic amide suppresses glioma by targeting WDR1-dependent cytoskeleton remodeling. Signal Transduct Target Ther 2023; 8:424. [PMID: 37935665 PMCID: PMC10630452 DOI: 10.1038/s41392-023-01666-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2022] [Revised: 09/17/2023] [Accepted: 09/30/2023] [Indexed: 11/09/2023] Open
Abstract
Glioma is the most prevalent brain tumor, presenting with limited treatment options, while patients with malignant glioma and glioblastoma (GBM) have poor prognoses. The physical obstacle to drug delivery imposed by the blood‒brain barrier (BBB) and glioma stem cells (GSCs), which are widely recognized as crucial elements contributing to the unsatisfactory clinical outcomes. In this study, we found a small molecule, gambogic amide (GA-amide), exhibited the ability to effectively penetrate the blood-brain barrier (BBB) and displayed a notable enrichment within the tumor region. Moreover, GA-amide exhibited significant efficacy in inhibiting tumor growth across various in vivo glioma models, encompassing transgenic and primary patient-derived xenograft (PDX) models. We further performed a genome-wide clustered regularly interspaced short palindromic repeats (CRISPR) knockout screen to determine the druggable target of GA-amide. By the combination of the cellular thermal shift assay (CETSA), the drug affinity responsive target stability (DARTS) approach, molecular docking simulation and surface plasmon resonance (SPR) analysis, WD repeat domain 1 (WDR1) was identified as the direct binding target of GA-amide. Through direct interaction with WDR1, GA-amide promoted the formation of a complex involving WDR1, MYH9 and Cofilin, which accelerate the depolymerization of F-actin to inhibit the invasion of patient-derived glioma cells (PDCs) and induce PDC apoptosis via the mitochondrial apoptotic pathway. In conclusion, our study not only identified GA-amide as an effective and safe agent for treating glioma but also shed light on the underlying mechanisms of GA-amide from the perspective of cytoskeletal homeostasis.
Collapse
Affiliation(s)
- Jiaorong Qu
- Department of Molecular Biology and Biochemistry, Institute of Basic Medical Sciences, Medical Primate Research Center, Neuroscience Center, Chinese Academy of Medical Sciences, School of Basic Medicine, Peking Union Medical College, Beijing, 100005, China
- State Key Laboratory of Common Mechanism Research for Major Diseases, Beijing, China
| | - Bojun Qiu
- Department of Molecular Biology and Biochemistry, Institute of Basic Medical Sciences, Medical Primate Research Center, Neuroscience Center, Chinese Academy of Medical Sciences, School of Basic Medicine, Peking Union Medical College, Beijing, 100005, China
- State Key Laboratory of Common Mechanism Research for Major Diseases, Beijing, China
| | - Yuxin Zhang
- Department of Molecular Biology and Biochemistry, Institute of Basic Medical Sciences, Medical Primate Research Center, Neuroscience Center, Chinese Academy of Medical Sciences, School of Basic Medicine, Peking Union Medical College, Beijing, 100005, China
- State Key Laboratory of Common Mechanism Research for Major Diseases, Beijing, China
| | - Yan Hu
- Department of Molecular Biology and Biochemistry, Institute of Basic Medical Sciences, Medical Primate Research Center, Neuroscience Center, Chinese Academy of Medical Sciences, School of Basic Medicine, Peking Union Medical College, Beijing, 100005, China
- State Key Laboratory of Common Mechanism Research for Major Diseases, Beijing, China
| | - Zhixing Wang
- Department of Molecular Biology and Biochemistry, Institute of Basic Medical Sciences, Medical Primate Research Center, Neuroscience Center, Chinese Academy of Medical Sciences, School of Basic Medicine, Peking Union Medical College, Beijing, 100005, China
- State Key Laboratory of Common Mechanism Research for Major Diseases, Beijing, China
| | - Zhiang Guan
- Department of Molecular Biology and Biochemistry, Institute of Basic Medical Sciences, Medical Primate Research Center, Neuroscience Center, Chinese Academy of Medical Sciences, School of Basic Medicine, Peking Union Medical College, Beijing, 100005, China
- State Key Laboratory of Common Mechanism Research for Major Diseases, Beijing, China
| | - Yiming Qin
- Department of Molecular Biology and Biochemistry, Institute of Basic Medical Sciences, Medical Primate Research Center, Neuroscience Center, Chinese Academy of Medical Sciences, School of Basic Medicine, Peking Union Medical College, Beijing, 100005, China
- State Key Laboratory of Common Mechanism Research for Major Diseases, Beijing, China
| | - Tongtong Sui
- Department of Molecular Biology and Biochemistry, Institute of Basic Medical Sciences, Medical Primate Research Center, Neuroscience Center, Chinese Academy of Medical Sciences, School of Basic Medicine, Peking Union Medical College, Beijing, 100005, China
- State Key Laboratory of Common Mechanism Research for Major Diseases, Beijing, China
| | - Fan Wu
- Department of Molecular Neuropathology, Beijing Neurosurgical Institute, Capital Medical University, Beijing, 100070, China
- Department of Neurosurgery, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Boyang Li
- Department of Molecular Biology and Biochemistry, Institute of Basic Medical Sciences, Medical Primate Research Center, Neuroscience Center, Chinese Academy of Medical Sciences, School of Basic Medicine, Peking Union Medical College, Beijing, 100005, China
- State Key Laboratory of Common Mechanism Research for Major Diseases, Beijing, China
| | - Wei Han
- Department of Molecular Biology and Biochemistry, Institute of Basic Medical Sciences, Medical Primate Research Center, Neuroscience Center, Chinese Academy of Medical Sciences, School of Basic Medicine, Peking Union Medical College, Beijing, 100005, China.
- State Key Laboratory of Common Mechanism Research for Major Diseases, Beijing, China.
| | - Xiaozhong Peng
- Department of Molecular Biology and Biochemistry, Institute of Basic Medical Sciences, Medical Primate Research Center, Neuroscience Center, Chinese Academy of Medical Sciences, School of Basic Medicine, Peking Union Medical College, Beijing, 100005, China.
- State Key Laboratory of Respiratory Health and Multimorbidity, Beijing, China.
- National Human Diseases Animal Model Resource Center, Beijing Engineering Research Center for Experimental Animal Models of Human Critical Diseases, Institute of Laboratory Animal Science, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, 100021, China.
| |
Collapse
|
9
|
Cortada M, Levano S, Hall MN, Bodmer D. mTORC2 regulates auditory hair cell structure and function. iScience 2023; 26:107687. [PMID: 37694145 PMCID: PMC10484995 DOI: 10.1016/j.isci.2023.107687] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2023] [Revised: 07/14/2023] [Accepted: 08/17/2023] [Indexed: 09/12/2023] Open
Abstract
mTOR broadly controls cell growth, but little is known about the role of mTOR complex 2 (mTORC2) in the inner ear. To investigate the role of mTORC2 in sensory hair cells (HCs), we generated HC-specific Rictor knockout (HC-RicKO) mice. HC-RicKO mice exhibited early-onset, progressive, and profound hearing loss. Increased DPOAE thresholds indicated outer HC dysfunction. HCs are lost, but this occurs after hearing loss. Ultrastructural analysis revealed stunted and absent stereocilia in outer HCs. In inner HCs, the number of synapses was significantly decreased and the remaining synapses displayed a disrupted actin cytoskeleton and disorganized Ca2+ channels. Thus, the mTORC2 signaling pathway plays an important role in regulating auditory HC structure and function via regulation of the actin cytoskeleton. These results provide molecular insights on a central regulator of cochlear HCs and thus hearing.
Collapse
Affiliation(s)
- Maurizio Cortada
- Department of Biomedicine, University of Basel, CH-4031 Basel, Switzerland
| | - Soledad Levano
- Department of Biomedicine, University of Basel, CH-4031 Basel, Switzerland
| | | | - Daniel Bodmer
- Department of Biomedicine, University of Basel, CH-4031 Basel, Switzerland
- Clinic for Otorhinolaryngology, Head and Neck Surgery, University of Basel Hospital, CH-4031 Basel, Switzerland
| |
Collapse
|
10
|
Park J, Bird JE. The actin cytoskeleton in hair bundle development and hearing loss. Hear Res 2023; 436:108817. [PMID: 37300948 PMCID: PMC10408727 DOI: 10.1016/j.heares.2023.108817] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/27/2023] [Revised: 05/18/2023] [Accepted: 05/25/2023] [Indexed: 06/12/2023]
Abstract
Inner ear hair cells assemble mechanosensitive hair bundles on their apical surface that transduce sounds and accelerations. Each hair bundle is comprised of ∼ 100 individual stereocilia that are arranged into rows of increasing height and width; their specific and precise architecture being necessary for mechanoelectrical transduction (MET). The actin cytoskeleton is fundamental to establishing this architecture, not only by forming the structural scaffold shaping each stereocilium, but also by composing rootlets and the cuticular plate that together provide a stable foundation supporting each stereocilium. In concert with the actin cytoskeleton, a large assortment of actin-binding proteins (ABPs) function to cross-link actin filaments into specific topologies, as well as control actin filament growth, severing, and capping. These processes are individually critical for sensory transduction and are all disrupted in hereditary forms of human hearing loss. In this review, we provide an overview of actin-based structures in the hair bundle and the molecules contributing to their assembly and functional properties. We also highlight recent advances in mechanisms driving stereocilia elongation and how these processes are tuned by MET.
Collapse
Affiliation(s)
- Jinho Park
- Department of Pharmacology and Therapeutics, University of Florida, Gainesville, FL 32610, United States; Myology Institute, University of Florida, Gainesville, FL 32610, United States
| | - Jonathan E Bird
- Department of Pharmacology and Therapeutics, University of Florida, Gainesville, FL 32610, United States; Myology Institute, University of Florida, Gainesville, FL 32610, United States.
| |
Collapse
|
11
|
Wagner EL, Im JS, Sala S, Nakahata MI, Imbery TE, Li S, Chen D, Nimchuk K, Noy Y, Archer DW, Xu W, Hashisaki G, Avraham KB, Oakes PW, Shin JB. Repair of noise-induced damage to stereocilia F-actin cores is facilitated by XIRP2 and its novel mechanosensor domain. eLife 2023; 12:e72681. [PMID: 37294664 PMCID: PMC10259482 DOI: 10.7554/elife.72681] [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: 08/01/2021] [Accepted: 05/17/2023] [Indexed: 06/11/2023] Open
Abstract
Prolonged exposure to loud noise has been shown to affect inner ear sensory hair cells in a variety of deleterious manners, including damaging the stereocilia core. The damaged sites can be visualized as 'gaps' in phalloidin staining of F-actin, and the enrichment of monomeric actin at these sites, along with an actin nucleator and crosslinker, suggests that localized remodeling occurs to repair the broken filaments. Herein, we show that gaps in mouse auditory hair cells are largely repaired within 1 week of traumatic noise exposure through the incorporation of newly synthesized actin. We provide evidence that Xin actin binding repeat containing 2 (XIRP2) is required for the repair process and facilitates the enrichment of monomeric γ-actin at gaps. Recruitment of XIRP2 to stereocilia gaps and stress fiber strain sites in fibroblasts is force-dependent, mediated by a novel mechanosensor domain located in the C-terminus of XIRP2. Our study describes a novel process by which hair cells can recover from sublethal hair bundle damage and which may contribute to recovery from temporary hearing threshold shifts and the prevention of age-related hearing loss.
Collapse
Affiliation(s)
- Elizabeth L Wagner
- Department of Neuroscience, University of VirginiaCharlottesvilleUnited States
- Department of Biochemistry & Molecular Genetics, University of VirginiaCharlottesvilleUnited States
| | - Jun-Sub Im
- Department of Neuroscience, University of VirginiaCharlottesvilleUnited States
| | - Stefano Sala
- Department of Cell & Molecular Physiology, Stritch School of Medicine, Loyola University ChicagoChicagoUnited States
| | - Maura I Nakahata
- Department of Neuroscience, University of VirginiaCharlottesvilleUnited States
| | - Terence E Imbery
- Department of Neuroscience, University of VirginiaCharlottesvilleUnited States
- Department of Otolaryngology-Head & Neck Surgery, University of VirginiaCharlottesvilleUnited States
| | - Sihan Li
- Department of Neuroscience, University of VirginiaCharlottesvilleUnited States
- Department of Biochemistry & Molecular Genetics, University of VirginiaCharlottesvilleUnited States
| | - Daniel Chen
- Department of Neuroscience, University of VirginiaCharlottesvilleUnited States
| | - Katherine Nimchuk
- Department of Neuroscience, University of VirginiaCharlottesvilleUnited States
| | - Yael Noy
- Department of Human Molecular Genetics and Biochemistry, Faculty of Medicine and Sagol School of Neuroscience, Tel Aviv UniversityTel AvivIsrael
| | - David W Archer
- Department of Neuroscience, University of VirginiaCharlottesvilleUnited States
| | - Wenhao Xu
- Genetically Engineered Murine Model (GEMM) Core, University of VirginiaCharlottesvilleUnited States
| | - George Hashisaki
- Department of Otolaryngology-Head & Neck Surgery, University of VirginiaCharlottesvilleUnited States
| | - Karen B Avraham
- Department of Human Molecular Genetics and Biochemistry, Faculty of Medicine and Sagol School of Neuroscience, Tel Aviv UniversityTel AvivIsrael
| | - Patrick W Oakes
- Department of Cell & Molecular Physiology, Stritch School of Medicine, Loyola University ChicagoChicagoUnited States
| | - Jung-Bum Shin
- Department of Neuroscience, University of VirginiaCharlottesvilleUnited States
- Department of Biochemistry & Molecular Genetics, University of VirginiaCharlottesvilleUnited States
- Department of Otolaryngology-Head & Neck Surgery, University of VirginiaCharlottesvilleUnited States
- Department of Cell Biology, University of VirginiaCharlottesvilleUnited States
| |
Collapse
|
12
|
Berkemeier F, Page K. Coupling dynamics of 2D Notch-Delta signalling. Math Biosci 2023; 360:109012. [PMID: 37142213 DOI: 10.1016/j.mbs.2023.109012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2023] [Revised: 04/21/2023] [Accepted: 04/22/2023] [Indexed: 05/06/2023]
Abstract
Understanding pattern formation driven by cell-cell interactions has been a significant theme in cellular biology for many years. In particular, due to their implications within many biological contexts, lateral-inhibition mechanisms present in the Notch-Delta signalling pathway led to an extensive discussion between biologists and mathematicians. Deterministic and stochastic models have been developed as a consequence of this discussion, some of which address long-range signalling by considering cell protrusions reaching non-neighbouring cells. The dynamics of such signalling systems reveal intricate properties of the coupling terms involved in these models. In this work, we investigate the advantages and drawbacks of a single-parameter long-range signalling model across diverse scenarios. By employing linear and multi-scale analyses, we discover that pattern selection is not only partially explained but also depends on nonlinear effects that extend beyond the scope of these analytical techniques.
Collapse
Affiliation(s)
| | - Karen Page
- Department of Mathematics and IPLS, University College London, UK
| |
Collapse
|
13
|
Krey JF, Chatterjee P, Halford J, Cunningham CL, Perrin BJ, Barr-Gillespie PG. Control of stereocilia length during development of hair bundles. PLoS Biol 2023; 21:e3001964. [PMID: 37011103 PMCID: PMC10101650 DOI: 10.1371/journal.pbio.3001964] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2022] [Revised: 04/13/2023] [Accepted: 03/14/2023] [Indexed: 04/05/2023] Open
Abstract
Assembly of the hair bundle, the sensory organelle of the inner ear, depends on differential growth of actin-based stereocilia. Separate rows of stereocilia, labeled 1 through 3 from tallest to shortest, lengthen or shorten during discrete time intervals during development. We used lattice structured illumination microscopy and surface rendering to measure dimensions of stereocilia from mouse apical inner hair cells during early postnatal development; these measurements revealed a sharp transition at postnatal day 8 between stage III (row 1 and 2 widening; row 2 shortening) and stage IV (final row 1 lengthening and widening). Tip proteins that determine row 1 lengthening did not accumulate simultaneously during stages III and IV; while the actin-bundling protein EPS8 peaked at the end of stage III, GNAI3 peaked several days later-in early stage IV-and GPSM2 peaked near the end of stage IV. To establish the contributions of key macromolecular assemblies to bundle structure, we examined mouse mutants that eliminated tip links (Cdh23v2J or Pcdh15av3J), transduction channels (TmieKO), or the row 1 tip complex (Myo15ash2). Cdh23v2J/v2J and Pcdh15av3J/av3J bundles had adjacent stereocilia in the same row that were not matched in length, revealing that a major role of these cadherins is to synchronize lengths of side-by-side stereocilia. Use of the tip-link mutants also allowed us to distinguish the role of transduction from effects of transduction proteins themselves. While levels of GNAI3 and GPSM2, which stimulate stereocilia elongation, were greatly attenuated at the tips of TmieKO/KO row 1 stereocilia, they accumulated normally in Cdh23v2J/v2J and Pcdh15av3J/av3J stereocilia. These results reinforced the suggestion that the transduction proteins themselves facilitate localization of proteins in the row 1 complex. By contrast, EPS8 concentrates at tips of all TmieKO/KO, Cdh23v2J/v2J, and Pcdh15av3J/av3J stereocilia, correlating with the less polarized distribution of stereocilia lengths in these bundles. These latter results indicated that in wild-type hair cells, the transduction complex prevents accumulation of EPS8 at the tips of shorter stereocilia, causing them to shrink (rows 2 and 3) or disappear (row 4 and microvilli). Reduced rhodamine-actin labeling at row 2 stereocilia tips of tip-link and transduction mutants suggests that transduction's role is to destabilize actin filaments there. These results suggest that regulation of stereocilia length occurs through EPS8 and that CDH23 and PCDH15 regulate stereocilia lengthening beyond their role in gating mechanotransduction channels.
Collapse
Affiliation(s)
- Jocelyn F. Krey
- Oregon Hearing Research Center and Vollum Institute, Oregon Health & Science University, Portland, Oregon, United States of America
| | - Paroma Chatterjee
- Oregon Hearing Research Center and Vollum Institute, Oregon Health & Science University, Portland, Oregon, United States of America
| | - Julia Halford
- Oregon Hearing Research Center and Vollum Institute, Oregon Health & Science University, Portland, Oregon, United States of America
| | - Christopher L. Cunningham
- Pittsburgh Hearing Research Center, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
| | - Benjamin J. Perrin
- Department of Biology, Indiana University-Purdue University Indianapolis, Indianapolis, Indiana, United States of America
| | - Peter G. Barr-Gillespie
- Oregon Hearing Research Center and Vollum Institute, Oregon Health & Science University, Portland, Oregon, United States of America
| |
Collapse
|
14
|
Sharkova M, Chow E, Erickson T, Hocking JC. The morphological and functional diversity of apical microvilli. J Anat 2023; 242:327-353. [PMID: 36281951 PMCID: PMC9919547 DOI: 10.1111/joa.13781] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Revised: 10/03/2022] [Accepted: 10/05/2022] [Indexed: 11/30/2022] Open
Abstract
Sensory neurons use specialized apical processes to perceive external stimuli and monitor internal body conditions. The apical apparatus can include cilia, microvilli, or both, and is adapted for the functions of the particular cell type. Photoreceptors detect light through a large, modified cilium (outer segment), that is supported by a surrounding ring of microvilli-like calyceal processes (CPs). Although first reported 150 years ago, CPs remain poorly understood. As a basis for future study, we therefore conducted a review of existing literature about sensory cell microvilli, which can act either as the primary sensory detector or as support for a cilia-based detector. While all microvilli are finger-like cellular protrusions with an actin core, the processes vary across cell types in size, number, arrangement, dynamics, and function. We summarize the current state of knowledge about CPs and the characteristics of the microvilli found on inner ear hair cells (stereocilia) and cerebral spinal fluid-contacting neurons, with comparisons to the brush border of the intestinal and renal epithelia. The structure, stability, and dynamics of the actin core are regulated by a complement of actin-binding proteins, which includes both common components and unique features when compared across cell types. Further, microvilli are often supported by lateral links, a glycocalyx, and a defined extracellular matrix, each adapted to the function and environment of the cell. Our comparison of microvillar features will inform further research into how CPs support photoreceptor function, and also provide a general basis for investigations into the structure and functions of apical microvilli found on sensory neurons.
Collapse
Affiliation(s)
- Maria Sharkova
- Department of Cell Biology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - Erica Chow
- Department of Cell Biology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - Timothy Erickson
- Department of Biology, University of New Brunswick, Fredericton, New Brunswick, Canada
| | - Jennifer C Hocking
- Department of Cell Biology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada.,Division of Anatomy, Department of Surgery, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada.,Department of Medical Genetics, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada.,Women and Children's Health Research Institute, University of Alberta, Edmonton, Alberta, Canada
| |
Collapse
|
15
|
Rajan S, Kudryashov DS, Reisler E. Actin Bundles Dynamics and Architecture. Biomolecules 2023; 13:450. [PMID: 36979385 PMCID: PMC10046292 DOI: 10.3390/biom13030450] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2022] [Revised: 02/16/2023] [Accepted: 02/20/2023] [Indexed: 03/04/2023] Open
Abstract
Cells use the actin cytoskeleton for many of their functions, including their division, adhesion, mechanosensing, endo- and phagocytosis, migration, and invasion. Actin bundles are the main constituent of actin-rich structures involved in these processes. An ever-increasing number of proteins that crosslink actin into bundles or regulate their morphology is being identified in cells. With recent advances in high-resolution microscopy and imaging techniques, the complex process of bundles formation and the multiple forms of physiological bundles are beginning to be better understood. Here, we review the physiochemical and biological properties of four families of highly conserved and abundant actin-bundling proteins, namely, α-actinin, fimbrin/plastin, fascin, and espin. We describe the similarities and differences between these proteins, their role in the formation of physiological actin bundles, and their properties-both related and unrelated to their bundling abilities. We also review some aspects of the general mechanism of actin bundles formation, which are known from the available information on the activity of the key actin partners involved in this process.
Collapse
Affiliation(s)
- Sudeepa Rajan
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA 90095, USA
| | - Dmitri S. Kudryashov
- Department of Chemistry and Biochemistry, Ohio State University, Columbus, OH 43210, USA
| | - Emil Reisler
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA 90095, USA
- Molecular Biology Institute, University of California, Los Angeles, CA 90095, USA
| |
Collapse
|
16
|
Chiereghin C, Robusto M, Lewis MA, Caetano S, Massa V, Castorina P, Ambrosetti U, Steel KP, Duga S, Asselta R, Soldà G. In-depth genetic and molecular characterization of diaphanous related formin 2 (DIAPH2) and its role in the inner ear. PLoS One 2023; 18:e0273586. [PMID: 36689403 PMCID: PMC9870134 DOI: 10.1371/journal.pone.0273586] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2022] [Accepted: 01/09/2023] [Indexed: 01/24/2023] Open
Abstract
Diaphanous related formins are regulatory cytoskeletal protein involved in actin elongation and microtubule stabilization. In humans, defects in two of the three diaphanous genes (DIAPH1 and DIAPH3) have been associated with different types of hearing loss. Here, we investigate the role of the third member of the family, DIAPH2, in nonsyndromic hearing loss, prompted by the identification, by exome sequencing, of a predicted pathogenic missense variant in DIAPH2. This variant occurs at a conserved site and segregated with nonsyndromic X-linked hearing loss in an Italian family. Our immunohistochemical studies indicated that the mouse ortholog protein Diaph2 is expressed during development in the cochlea, specifically in the actin-rich stereocilia of the sensory outer hair cells. In-vitro studies showed a functional impairment of the mutant DIAPH2 protein upon RhoA-dependent activation. Finally, Diaph2 knock-out and knock-in mice were generated by CRISPR/Cas9 technology and auditory brainstem response measurements performed at 4, 8 and 14 weeks. However, no hearing impairment was detected. Our findings indicate that DIAPH2 may play a role in the inner ear; further studies are however needed to clarify the contribution of DIAPH2 to deafness.
Collapse
Affiliation(s)
| | - Michela Robusto
- Experimental Therapeutics Program, IFOM ETS -The AIRC Institute of Molecular Oncology, Milan, Italy
| | - Morag A. Lewis
- Wolfson Centre for Age-Related Diseases, King’s College London, London, United Kingdom
| | - Susana Caetano
- Wolfson Centre for Age-Related Diseases, King’s College London, London, United Kingdom
| | - Valentina Massa
- Dipartimento di Scienze della Salute, Università degli Studi di Milano, Milano, Italy
| | | | - Umberto Ambrosetti
- Dipartimento di Scienze Cliniche e di Comunità, Università degli Studi di Milano and Fondazione IRCCS Cà Granda Ospedale Maggiore Policlinico, UO Audiologia, Milano, Italy
| | - Karen P. Steel
- Wolfson Centre for Age-Related Diseases, King’s College London, London, United Kingdom
| | - Stefano Duga
- IRCCS Humanitas Research Hospital, Rozzano, Milan, Italy
- Humanitas University, Department of Biomedical Sciences, Pieve Emanuele, Milan, Italy
| | - Rosanna Asselta
- IRCCS Humanitas Research Hospital, Rozzano, Milan, Italy
- Humanitas University, Department of Biomedical Sciences, Pieve Emanuele, Milan, Italy
| | - Giulia Soldà
- IRCCS Humanitas Research Hospital, Rozzano, Milan, Italy
- Humanitas University, Department of Biomedical Sciences, Pieve Emanuele, Milan, Italy
| |
Collapse
|
17
|
Moreland ZG, Bird JE. Myosin motors in sensory hair bundle assembly. Curr Opin Cell Biol 2022; 79:102132. [PMID: 36257241 DOI: 10.1016/j.ceb.2022.102132] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Revised: 09/02/2022] [Accepted: 09/07/2022] [Indexed: 01/31/2023]
Abstract
Mechanosensory hair bundles are assembled from actin-based stereocilia that project from the apical surface of hair cells in the inner ear. Stereocilia architecture is critical for the transduction of sound and accelerations, and structural defects in these mechano-sensors are a clinical cause of hearing and balance disorders in humans. Unconventional myosin motors are central to the assembly and shaping of stereocilia architecture. A sub-group of myosin motors with MyTH4-FERM domains (MYO7A, MYO15A) are particularly important in these processes, and hypothesized to act as transporters delivering structural and actin-regulatory cargos, in addition to generating force and tension. In this review, we summarize existing evidence for how MYO7A and MYO15A operate and how their dysfunction leads to stereocilia pathology. We further highlight emerging properties of the MyTH4/FERM myosin family and speculate how these new functions might contribute towards the acquisition and maintenance of mechano-sensitivity.
Collapse
Affiliation(s)
- Zane G Moreland
- Department of Pharmacology and Therapeutics, University of Florida, Gainesville, FL, 32610, USA; Myology Institute, University of Florida, Gainesville, FL, 32610, USA; Graduate Program in Biomedical Sciences, University of Florida, Gainesville, FL, 32610, USA
| | - Jonathan E Bird
- Department of Pharmacology and Therapeutics, University of Florida, Gainesville, FL, 32610, USA; Myology Institute, University of Florida, Gainesville, FL, 32610, USA.
| |
Collapse
|
18
|
Liu C, Luo N, Zhao B. Reducing Taperin Expression Restores Hearing in Grxcr2 Mutant Mice. Neuroscience 2022; 498:85-92. [PMID: 35752427 PMCID: PMC9420823 DOI: 10.1016/j.neuroscience.2022.06.030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2022] [Revised: 06/15/2022] [Accepted: 06/16/2022] [Indexed: 11/20/2022]
Abstract
Recessive mutations in GRXCR2 cause deafness in both humans and mice. In Grxcr2 null hair cells, the sensory receptors for sound in the inner ear, stereocilia are disorganized. Reducing the expression of taperin, a protein that interacts with GRXCR2 at the base of stereocilia, corrects the morphological defects of stereocilia and restores hearing in Grxcr2 null mice. To further validate this finding, this study generated two novel taperin mutant mouse lines that exhibit progressive hearing loss. Then Grxcr2 null mice were crossed with one of these taperin mutant mice. The following morphological analysis revealed that reducing taperin expression indeed corrected stereocilia morphological abnormalities in Grxcr2 null mice. Functional analysis further confirmed that reducing taperin expression partially restored hearing in Grxcr2 null mice.
Collapse
Affiliation(s)
- Chang Liu
- Department of Otolaryngology-Head and Neck Surgery, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Na Luo
- Department of Otolaryngology-Head and Neck Surgery, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Bo Zhao
- Department of Otolaryngology-Head and Neck Surgery, Indiana University School of Medicine, Indianapolis, IN 46202, USA.
| |
Collapse
|
19
|
Zhai X, Du H, Shen Y, Zhang X, Chen Z, Wang Y, Xu Z. FCHSD2 is required for stereocilia maintenance in mouse cochlear hair cells. J Cell Sci 2022; 135:jcs259912. [PMID: 35892293 DOI: 10.1242/jcs.259912] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2022] [Accepted: 07/15/2022] [Indexed: 11/20/2022] Open
Abstract
Stereocilia are F-actin-based protrusions on the apical surface of inner-ear hair cells and are indispensable for hearing and balance perception. The stereocilia of each hair cell are organized into rows of increasing heights, forming a staircase-like pattern. The development and maintenance of stereocilia are tightly regulated, and deficits in these processes lead to stereocilia disorganization and hearing loss. Previously, we showed that the F-BAR protein FCHSD2 is localized along the stereocilia of cochlear hair cells and cooperates with CDC42 to regulate F-actin polymerization and cell protrusion formation in cultured COS-7 cells. In the present work, Fchsd2 knockout mice were established to investigate the role of FCHSD2 in hearing. Our data show that stereocilia maintenance is severely affected in cochlear hair cells of Fchsd2 knockout mice, which leads to progressive hearing loss. Moreover, Fchsd2 knockout mice show increased acoustic vulnerability. Noise exposure causes robust stereocilia degeneration as well as enhanced hearing threshold elevation in Fchsd2 knockout mice. Lastly, Fchsd2/Cdc42 double knockout mice show more severe stereocilia deficits and hearing loss, suggesting that FCHSD2 and CDC42 cooperatively regulate stereocilia maintenance.
Collapse
Affiliation(s)
- Xiaoyan Zhai
- Shandong Provincial Key Laboratory of Animal Cell and Developmental Biology and Key Laboratory for Experimental Teratology of the Ministry of Education , School of Life Sciences, Shandong University, Qingdao, Shandong 266237, China
| | - Haibo Du
- Shandong Provincial Key Laboratory of Animal Cell and Developmental Biology and Key Laboratory for Experimental Teratology of the Ministry of Education , School of Life Sciences, Shandong University, Qingdao, Shandong 266237, China
| | - Yuxin Shen
- Shandong Provincial Key Laboratory of Animal Cell and Developmental Biology and Key Laboratory for Experimental Teratology of the Ministry of Education , School of Life Sciences, Shandong University, Qingdao, Shandong 266237, China
| | - Xiujuan Zhang
- Shandong Provincial Key Laboratory of Animal Cell and Developmental Biology and Key Laboratory for Experimental Teratology of the Ministry of Education , School of Life Sciences, Shandong University, Qingdao, Shandong 266237, China
| | - Zhengjun Chen
- State Key Laboratory of Cell Biology , Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences (CAS), Shanghai 200031, China
- School of Life Science and Technology, ShanghaiTech University, Shanghai 200031, China
| | - Yanfei Wang
- Shandong Provincial Key Laboratory of Animal Cell and Developmental Biology and Key Laboratory for Experimental Teratology of the Ministry of Education , School of Life Sciences, Shandong University, Qingdao, Shandong 266237, China
| | - Zhigang Xu
- Shandong Provincial Key Laboratory of Animal Cell and Developmental Biology and Key Laboratory for Experimental Teratology of the Ministry of Education , School of Life Sciences, Shandong University, Qingdao, Shandong 266237, China
- Shandong Provincial Collaborative Innovation Center of Cell Biology , Shandong Normal University, Jinan, Shandong 250014, China
| |
Collapse
|
20
|
Selective binding and transport of protocadherin 15 isoforms by stereocilia unconventional myosins in a heterologous expression system. Sci Rep 2022; 12:13764. [PMID: 35962067 PMCID: PMC9374675 DOI: 10.1038/s41598-022-17757-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Accepted: 07/30/2022] [Indexed: 11/09/2022] Open
Abstract
During hair cell development, the mechanoelectrical transduction (MET) apparatus is assembled at the stereocilia tips, where it coexists with the stereocilia actin regulatory machinery. While the myosin-based tipward transport of actin regulatory proteins is well studied, isoform complexity and built-in redundancies in the MET apparatus have limited our understanding of how MET components are transported. We used a heterologous expression system to elucidate the myosin selective transport of isoforms of protocadherin 15 (PCDH15), the protein that mechanically gates the MET apparatus. We show that MYO7A selectively transports the CD3 isoform while MYO3A and MYO3B transports the CD2 isoform. Furthermore, MYO15A showed an insignificant role in the transport of PCDH15, and none of the myosins tested transport PCDH15-CD1. Our data suggest an important role for MYO3A, MYO3B, and MYO7A in the MET apparatus formation and highlight the intricate nature of MET and actin regulation during development and functional maturation of the stereocilia bundle.
Collapse
|
21
|
Li J, Liu C, Zhao B. Collapsin Response Mediator Protein 1 (CRMP1) Is Required for High-Frequency Hearing. THE AMERICAN JOURNAL OF PATHOLOGY 2022; 192:805-812. [PMID: 35181334 PMCID: PMC9088201 DOI: 10.1016/j.ajpath.2022.01.011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2021] [Revised: 01/04/2022] [Accepted: 01/11/2022] [Indexed: 05/03/2023]
Abstract
Collapsin response mediator protein 1 (CRMP1), also known as dihydropyrimidinase-related protein 1, participates in cytoskeleton remodeling during axonal guidance and neuronal migration. In cochlear hair cells, the assembly and maintenance of the cytoskeleton is of great interest because it is crucial for the morphogenesis and maintenance of hair cells. Previous RNA sequencing analysis found that Crmp1 is highly expressed in cochlear hair cells. However, the expression profile and functions of CRMP1 in the inner ear remain unknown. In this study, the expression and localization of CRMP1 in hair cells was investigated using immunostaining, and was shown to be highly expressed in both outer and inner hair cells. Next, the stereocilia morphology of Crmp1-deficient mice was characterized. Abolishing CRMP1 did not affect the morphogenesis of hair cells. Interestingly, scanning electron microscopy detected hair cell loss at the basal cochlear region, an area responsible for high-frequency auditory perception, in Crmp1-deficient mice. Correspondingly, an auditory brainstem response test showed that mice lacking CRMP1 had progressive hearing loss at high frequencies. In summary, these data suggest that CRMP1 is required for high-frequency auditory perception.
Collapse
Affiliation(s)
- Jinan Li
- Department of Otolaryngology-Head and Neck Surgery, Indiana University School of Medicine, Indianapolis, Indiana
| | - Chang Liu
- Department of Otolaryngology-Head and Neck Surgery, Indiana University School of Medicine, Indianapolis, Indiana
| | - Bo Zhao
- Department of Otolaryngology-Head and Neck Surgery, Indiana University School of Medicine, Indianapolis, Indiana.
| |
Collapse
|
22
|
Molecular and cytological profiling of biological aging of mouse cochlear inner and outer hair cells. Cell Rep 2022; 39:110665. [PMID: 35417713 PMCID: PMC9069708 DOI: 10.1016/j.celrep.2022.110665] [Citation(s) in RCA: 30] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Revised: 02/08/2022] [Accepted: 03/21/2022] [Indexed: 12/12/2022] Open
Abstract
Age-related hearing loss (ARHL) negatively impacts quality of life in the elderly population. The prevalent cause of ARHL is loss of mechanosensitive cochlear hair cells (HCs). The molecular and cellular mechanisms of HC degeneration remain poorly understood. Using RNA-seq transcriptomic analyses of inner and outer HCs isolated from young and aged mice, we show that HC aging is associated with changes in key molecular processes, including transcription, DNA damage, autophagy, and oxidative stress, as well as genes related to HC specialization. At the cellular level, HC aging is characterized by loss of stereocilia, shrinkage of HC soma, and reduction in outer HC mechanical properties, suggesting that functional decline in mechanotransduction and cochlear amplification precedes HC loss and contributes to ARHL. Our study reveals molecular and cytological profiles of aging HCs and identifies genes such as Sod1, Sirt6, Jund, and Cbx3 as biomarkers and potential therapeutic targets for ameliorating ARHL. Using RNA-seq, advanced imaging, and electrophysiology, Liu et al. reveal molecular and cytological profiles of aging cochlear hair cells. Their study also suggests that a functional decline in mechanotransduction and cochlear amplification precedes hair cell loss and contributes to age-related hearing loss.
Collapse
|
23
|
Castaneda N, Feuillie C, Molinari M, Kang EH. Actin Bundle Nanomechanics and Organization Are Modulated by Macromolecular Crowding and Electrostatic Interactions. Front Mol Biosci 2021; 8:760950. [PMID: 34901154 PMCID: PMC8662701 DOI: 10.3389/fmolb.2021.760950] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Accepted: 11/02/2021] [Indexed: 11/21/2022] Open
Abstract
The structural and mechanical properties of actin bundles are essential to eukaryotic cells, aiding in cell motility and mechanical support of the plasma membrane. Bundle formation occurs in crowded intracellular environments composed of various ions and macromolecules. Although the roles of cations and macromolecular crowding in the mechanics and organization of actin bundles have been independently established, how changing both intracellular environmental conditions influence bundle mechanics at the nanoscale has yet to be established. Here we investigate how electrostatics and depletion interactions modulate the relative Young’s modulus and height of actin bundles using atomic force microscopy. Our results demonstrate that cation- and depletion-induced bundles display an overall reduction of relative Young’s modulus depending on either cation or crowding concentrations. Furthermore, we directly measure changes to cation- and depletion-induced bundle height, indicating that bundles experience alterations to filament packing supporting the reduction to relative Young’s modulus. Taken together, our work suggests that electrostatic and depletion interactions may act counteractively, impacting actin bundle nanomechanics and organization.
Collapse
Affiliation(s)
- Nicholas Castaneda
- NanoScience Technology Center, University of Central Florida, Orlando, FL, United States.,Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, FL, United States
| | - Cecile Feuillie
- Institute of Chemistry and Biology of Membranes and Nano-objects, CBMN CNRS UMR 5248, IPB, Université de Bordeaux, Pessac, France
| | - Michael Molinari
- Institute of Chemistry and Biology of Membranes and Nano-objects, CBMN CNRS UMR 5248, IPB, Université de Bordeaux, Pessac, France
| | - Ellen Hyeran Kang
- NanoScience Technology Center, University of Central Florida, Orlando, FL, United States.,Department of Physics, University of Central Florida, Orlando, FL, United States.,Department of Materials Science and Engineering, University of Central Florida, Orlando, FL, United States
| |
Collapse
|
24
|
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.
Collapse
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
| |
Collapse
|
25
|
Du H, Zhou H, Sun Y, Zhai X, Chen Z, Wang Y, Xu Z. The Rho GTPase Cell Division Cycle 42 Regulates Stereocilia Development in Cochlear Hair Cells. Front Cell Dev Biol 2021; 9:765559. [PMID: 34746154 PMCID: PMC8570139 DOI: 10.3389/fcell.2021.765559] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Accepted: 10/06/2021] [Indexed: 11/13/2022] Open
Abstract
Stereocilia are actin-based cell protrusions on the apical surface of inner ear hair cells, playing a pivotal role in hearing and balancing sensation. The development and maintenance of stereocilia is tightly regulated and deficits in this process usually lead to hearing or balancing disorders. The Rho GTPase cell division cycle 42 (CDC42) is a key regulator of the actin cytoskeleton. It has been reported to localize in the hair cell stereocilia and play important roles in stereocilia maintenance. In the present work, we utilized hair cell-specific Cdc42 knockout mice and CDC42 inhibitor ML141 to explore the role of CDC42 in stereocilia development. Our data show that stereocilia height and width as well as stereocilia resorption are affected in Cdc42-deficient cochlear hair cells when examined at postnatal day 8 (P8). Moreover, ML141 treatment leads to planar cell polarity (PCP) deficits in neonatal hair cells. We also show that overexpression of a constitutively active mutant CDC42 in cochlear hair cells leads to enhanced stereocilia developmental deficits. In conclusion, the present data suggest that CDC42 plays a pivotal role in regulating hair cell stereocilia development.
Collapse
Affiliation(s)
- Haibo Du
- Shandong Provincial Key Laboratory of Animal Cell and Developmental Biology, School of Life Sciences, Shandong University, Qingdao, China
| | - Hao Zhou
- Shandong Provincial Key Laboratory of Animal Cell and Developmental Biology, School of Life Sciences, Shandong University, Qingdao, China
| | - Yixiao Sun
- Shandong Provincial Key Laboratory of Animal Cell and Developmental Biology, School of Life Sciences, Shandong University, Qingdao, China
| | - Xiaoyan Zhai
- Shandong Provincial Key Laboratory of Animal Cell and Developmental Biology, School of Life Sciences, Shandong University, Qingdao, China
| | - Zhengjun Chen
- State Key Laboratory of Cell Biology, Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai, China.,School of Life Sciences and Technology, ShanghaiTech University, Shanghai, China
| | - Yanfei Wang
- Shandong Provincial Key Laboratory of Animal Cell and Developmental Biology, School of Life Sciences, Shandong University, Qingdao, China
| | - Zhigang Xu
- Shandong Provincial Key Laboratory of Animal Cell and Developmental Biology, School of Life Sciences, Shandong University, Qingdao, China.,Shandong Provincial Collaborative Innovation Center of Cell Biology, Shandong Normal University, Jinan, China
| |
Collapse
|
26
|
van Loon AP, Erofeev IS, Goryachev AB, Sagasti A. Stochastic contraction of myosin minifilaments drives evolution of microridge protrusion patterns in epithelial cells. Mol Biol Cell 2021; 32:1501-1513. [PMID: 34081537 PMCID: PMC8351741 DOI: 10.1091/mbc.e21-05-0258] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Accepted: 05/26/2021] [Indexed: 01/05/2023] Open
Abstract
Actin-based protrusions vary in morphology, stability, and arrangement on cell surfaces. Microridges are laterally elongated protrusions on mucosal epithelial cells, where they form evenly spaced, mazelike patterns that dynamically remodel by fission and fusion. To characterize how microridges form their highly ordered, subcellular patterns and investigate the mechanisms driving fission and fusion, we imaged microridges in the maturing skin of zebrafish larvae. After their initial development, microridge spacing and alignment became increasingly well ordered. Imaging F-actin and non-muscle myosin II (NMII) revealed that microridge fission and fusion were associated with local NMII activity in the apical cortex. Inhibiting NMII blocked fission and fusion rearrangements, reduced microridge density, and altered microridge spacing. High-resolution imaging allowed us to image individual NMII minifilaments in the apical cortex of cells in live animals, revealing that minifilaments are tethered to protrusions and often connect adjacent microridges. NMII minifilaments connecting the ends of two microridges fused them together, whereas minifilaments oriented perpendicular to microridges severed them or pulled them closer together. These findings demonstrate that as cells mature, cortical NMII activity orchestrates a remodeling process that creates an increasingly orderly microridge arrangement.
Collapse
Affiliation(s)
- Aaron P. van Loon
- Department of Molecular, Cell and Developmental Biology, and Molecular Biology Institute, University of California, Los Angeles, Los Angeles, CA
| | - Ivan S. Erofeev
- Centre for Synthetic and Systems Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, UK
| | - Andrew B. Goryachev
- Centre for Synthetic and Systems Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, UK
| | - Alvaro Sagasti
- Department of Molecular, Cell and Developmental Biology, and Molecular Biology Institute, University of California, Los Angeles, Los Angeles, CA
| |
Collapse
|
27
|
Miyoshi T, Belyantseva IA, Kitajiri SI, Miyajima H, Nishio SY, Usami SI, Kim BJ, Choi BY, Omori K, Shroff H, Friedman TB. Human deafness-associated variants alter the dynamics of key molecules in hair cell stereocilia F-actin cores. Hum Genet 2021; 141:363-382. [PMID: 34232383 DOI: 10.1007/s00439-021-02304-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Accepted: 06/15/2021] [Indexed: 12/16/2022]
Abstract
Stereocilia protrude up to 100 µm from the apical surface of vertebrate inner ear hair cells and are packed with cross-linked filamentous actin (F-actin). They function as mechanical switches to convert sound vibration into electrochemical neuronal signals transmitted to the brain. Several genes encode molecular components of stereocilia including actin monomers, actin regulatory and bundling proteins, motor proteins and the proteins of the mechanotransduction complex. A stereocilium F-actin core is a dynamic system, which is continuously being remodeled while maintaining an outwardly stable architecture under the regulation of F-actin barbed-end cappers, severing proteins and crosslinkers. The F-actin cores of stereocilia also provide a pathway for motor proteins to transport cargos including components of tip-link densities, scaffolding proteins and actin regulatory proteins. Deficiencies and mutations of stereocilia components that disturb this "dynamic equilibrium" in stereocilia can induce morphological changes and disrupt mechanotransduction causing sensorineural hearing loss, best studied in mouse and zebrafish models. Currently, at least 23 genes, associated with human syndromic and nonsyndromic hearing loss, encode proteins involved in the development and maintenance of stereocilia F-actin cores. However, it is challenging to predict how variants associated with sensorineural hearing loss segregating in families affect protein function. Here, we review the functions of several molecular components of stereocilia F-actin cores and provide new data from our experimental approach to directly evaluate the pathogenicity and functional impact of reported and novel variants of DIAPH1 in autosomal-dominant DFNA1 hearing loss using single-molecule fluorescence microscopy.
Collapse
Affiliation(s)
- Takushi Miyoshi
- Laboratory of Molecular Genetics, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Porter Neuroscience Research Center, Room 1F-143A, Bethesda, MD, 20892, USA. .,Department of Otolaryngology-Head and Neck Surgery, Graduate School of Medicine, Kyoto University, Kyoto, 606-8507, Japan.
| | - Inna A Belyantseva
- Laboratory of Molecular Genetics, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Porter Neuroscience Research Center, Room 1F-143A, Bethesda, MD, 20892, USA
| | - Shin-Ichiro Kitajiri
- Department of Hearing Implant Sciences, Shinshu University School of Medicine, 390-8621, Matsumoto, Japan
| | - Hiroki Miyajima
- Department of Otolaryngology, Shinshu University School of Medicine, Matsumoto, 390-8621, Japan.,Department of Otolaryngology, Aizawa Hospital, Matsumoto, 390-8510, Japan
| | - Shin-Ya Nishio
- Department of Hearing Implant Sciences, Shinshu University School of Medicine, 390-8621, Matsumoto, Japan
| | - Shin-Ichi Usami
- Department of Hearing Implant Sciences, Shinshu University School of Medicine, 390-8621, Matsumoto, Japan
| | - Bong Jik Kim
- Department of Otolaryngology-Head and Neck Surgery, Chungnam National University College of Medicine, Chungnam National University Sejong Hospital, Sejong, 30099, South Korea.,Brain Research Institute, Chungnam National University College of Medicine, Daejeon, 35015, South Korea
| | - Byung Yoon Choi
- Department of Otorhinolaryngology, Seoul National University Bundang Hospital, Seongnam, 13620, South Korea
| | - Koichi Omori
- Department of Otolaryngology-Head and Neck Surgery, Graduate School of Medicine, Kyoto University, Kyoto, 606-8507, Japan
| | - Hari Shroff
- Laboratory of High Resolution Optical Imaging, National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Thomas B Friedman
- Laboratory of Molecular Genetics, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Porter Neuroscience Research Center, Room 1F-143A, Bethesda, MD, 20892, USA
| |
Collapse
|
28
|
Rich SK, Baskar R, Terman JR. Propagation of F-actin disassembly via Myosin15-Mical interactions. SCIENCE ADVANCES 2021; 7:7/20/eabg0147. [PMID: 33980493 PMCID: PMC8115926 DOI: 10.1126/sciadv.abg0147] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Accepted: 03/23/2021] [Indexed: 06/12/2023]
Abstract
The F-actin cytoskeleton drives cellular form and function. However, how F-actin-based changes occur with spatiotemporal precision and specific directional orientation is poorly understood. Here, we identify that the unconventional class XV myosin [Myosin 15 (Myo15)] physically and functionally interacts with the F-actin disassembly enzyme Mical to spatiotemporally position cellular breakdown and reconstruction. Specifically, while unconventional myosins have been associated with transporting cargo along F-actin to spatially target cytoskeletal assembly, we now find they also target disassembly. Myo15 specifically positions this F-actin disassembly by associating with Mical and using its motor and MyTH4-FERM cargo-transporting functions to broaden Mical's distribution. Myo15's broadening of Mical's distribution also expands and directionally orients Mical-mediated F-actin disassembly and subsequent cellular remodeling, including in response to Semaphorin/Plexin cell surface activation signals. Thus, we identify a mechanism that spatiotemporally propagates F-actin disassembly while also proposing that other F-actin-trafficked-cargo is derailed by this disassembly to directionally orient rebuilding.
Collapse
Affiliation(s)
- Shannon K Rich
- Departments of Neuroscience and Pharmacology and Neuroscience Graduate Program, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Raju Baskar
- Departments of Neuroscience and Pharmacology and Neuroscience Graduate Program, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Jonathan R Terman
- Departments of Neuroscience and Pharmacology and Neuroscience Graduate Program, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
| |
Collapse
|
29
|
Castaneda N, Park J, Kang EH. Regulation of Actin Bundle Mechanics and Structure by Intracellular Environmental Factors. FRONTIERS IN PHYSICS 2021; 9:675885. [PMID: 34422787 PMCID: PMC8376200 DOI: 10.3389/fphy.2021.675885] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The mechanical and structural properties of actin cytoskeleton drive various cellular processes, including structural support of the plasma membrane and cellular motility. Actin monomers assemble into double-stranded helical filaments as well as higher-ordered structures such as bundles and networks. Cells incorporate macromolecular crowding, cation interactions, and actin-crosslinking proteins to regulate the organization of actin bundles. Although the roles of each of these factors in actin bundling have been well-known individually, how combined factors contribute to actin bundle assembly, organization, and mechanics is not fully understood. Here, we describe recent studies that have investigated the mechanisms of how intracellular environmental factors influence actin bundling. This review highlights the effects of macromolecular crowding, cation interactions, and actin-crosslinking proteins on actin bundle organization, structure, and mechanics. Understanding these mechanisms is important in determining in vivo actin biophysics and providing insights into cell physiology.
Collapse
Affiliation(s)
- Nicholas Castaneda
- NanoScience Technology Center, University of Central Florida, Orlando, FL, United States
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, FL, United States
| | - Jinho Park
- NanoScience Technology Center, University of Central Florida, Orlando, FL, United States
- Department of Materials Science and Engineering, University of Central Florida, Orlando, FL, United States
| | - Ellen Hyeran Kang
- NanoScience Technology Center, University of Central Florida, Orlando, FL, United States
- Department of Materials Science and Engineering, University of Central Florida, Orlando, FL, United States
- Department of Physics, University of Central Florida, Orlando, FL, United States
| |
Collapse
|
30
|
McGrath J, Tung CY, Liao X, Belyantseva IA, Roy P, Chakraborty O, Li J, Berbari NF, Faaborg-Andersen CC, Barzik M, Bird JE, Zhao B, Balakrishnan L, Friedman TB, Perrin BJ. Actin at stereocilia tips is regulated by mechanotransduction and ADF/cofilin. Curr Biol 2021; 31:1141-1153.e7. [PMID: 33400922 PMCID: PMC8793668 DOI: 10.1016/j.cub.2020.12.006] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Revised: 10/21/2020] [Accepted: 12/07/2020] [Indexed: 11/30/2022]
Abstract
Stereocilia on auditory sensory cells are actin-based protrusions that mechanotransduce sound into an electrical signal. These stereocilia are arranged into a bundle with three rows of increasing length to form a staircase-like morphology that is required for hearing. Stereocilia in the shorter rows, but not the tallest row, are mechanotransducing because they have force-sensitive channels localized at their tips. The onset of mechanotransduction during mouse postnatal development refines stereocilia length and width. However, it is unclear how actin is differentially regulated between stereocilia in the tallest row of the bundle and the shorter, mechanotransducing rows. Here, we show actin turnover is increased at the tips of mechanotransducing stereocilia during bundle maturation. Correspondingly, from birth to postnatal day 6, these stereocilia had increasing amounts of available actin barbed ends, where monomers can be added or lost readily, as compared with the non-mechanotransducing stereocilia in the tallest row. The increase in available barbed ends depended on both mechanotransduction and MYO15 or EPS8, which are required for the normal specification and elongation of the tallest row of stereocilia. We also found that loss of the F-actin-severing proteins ADF and cofilin-1 decreased barbed end availability at stereocilia tips. These proteins enriched at mechanotransducing stereocilia tips, and their localization was perturbed by the loss of mechanotransduction, MYO15, or EPS8. Finally, stereocilia lengths and widths were dysregulated in Adf and Cfl1 mutants. Together, these data show that actin is remodeled, likely by a severing mechanism, in response to mechanotransduction.
Collapse
Affiliation(s)
- Jamis McGrath
- Department of Biology, Indiana University-Purdue University Indianapolis, 723 West Michigan Street, Indianapolis, IN 46202, USA
| | - Chun-Yu Tung
- Department of Biology, Indiana University-Purdue University Indianapolis, 723 West Michigan Street, Indianapolis, IN 46202, USA
| | - Xiayi Liao
- Department of Biology, Indiana University-Purdue University Indianapolis, 723 West Michigan Street, Indianapolis, IN 46202, USA
| | - Inna A Belyantseva
- Laboratory of Molecular Genetics, National Institute on Deafness and Other Communication Disorders, NIH, 35A Convent Drive, Bethesda, MD 20892, USA
| | - Pallabi Roy
- Department of Biology, Indiana University-Purdue University Indianapolis, 723 West Michigan Street, Indianapolis, IN 46202, USA
| | - Oisorjo Chakraborty
- Department of Biology, Indiana University-Purdue University Indianapolis, 723 West Michigan Street, Indianapolis, IN 46202, USA
| | - Jinan Li
- Department of Otolaryngology-Head and Neck Surgery, Indiana University School of Medicine, 1160 West Michigan Street, Indianapolis, IN 46202, USA
| | - Nicolas F Berbari
- Department of Biology, Indiana University-Purdue University Indianapolis, 723 West Michigan Street, Indianapolis, IN 46202, USA
| | - Christian C Faaborg-Andersen
- Laboratory of Molecular Genetics, National Institute on Deafness and Other Communication Disorders, NIH, 35A Convent Drive, Bethesda, MD 20892, USA
| | - Melanie Barzik
- Section on Sensory Cell Biology, National Institute on Deafness and Other Communication Disorders, NIH, 35A Convent Drive, Bethesda, MD 20892, USA
| | - Jonathan E Bird
- Department of Pharmacology and Therapeutics, University of Florida, 1200 Newell Drive, Gainesville, FL 32610, USA
| | - Bo Zhao
- Department of Otolaryngology-Head and Neck Surgery, Indiana University School of Medicine, 1160 West Michigan Street, Indianapolis, IN 46202, USA
| | - Lata Balakrishnan
- Department of Biology, Indiana University-Purdue University Indianapolis, 723 West Michigan Street, Indianapolis, IN 46202, USA
| | - Thomas B Friedman
- Laboratory of Molecular Genetics, National Institute on Deafness and Other Communication Disorders, NIH, 35A Convent Drive, Bethesda, MD 20892, USA
| | - Benjamin J Perrin
- Department of Biology, Indiana University-Purdue University Indianapolis, 723 West Michigan Street, Indianapolis, IN 46202, USA.
| |
Collapse
|
31
|
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.
Collapse
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
| |
Collapse
|
32
|
Miyoshi T, Zhang Q, Miyake T, Watanabe S, Ohnishi H, Chen J, Vishwasrao HD, Chakraborty O, Belyantseva IA, Perrin BJ, Shroff H, Friedman TB, Omori K, Watanabe N. Semi-automated single-molecule microscopy screening of fast-dissociating specific antibodies directly from hybridoma cultures. Cell Rep 2021; 34:108708. [PMID: 33535030 PMCID: PMC7904085 DOI: 10.1016/j.celrep.2021.108708] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2020] [Revised: 07/16/2020] [Accepted: 01/08/2021] [Indexed: 11/18/2022] Open
Abstract
Fast-dissociating, specific antibodies are single-molecule imaging probes that transiently interact with their targets and are used in biological applications including image reconstruction by integrating exchangeable single-molecule localization (IRIS), a multiplexable super-resolution microscopy technique. Here, we introduce a semi-automated screen based on single-molecule total internal reflection fluorescence (TIRF) microscopy of antibody-antigen binding, which allows for identification of fast-dissociating monoclonal antibodies directly from thousands of hybridoma cultures. We develop monoclonal antibodies against three epitope tags (FLAG-tag, S-tag, and V5-tag) and two F-actin crosslinking proteins (plastin and espin). Specific antibodies show fast dissociation with half-lives ranging from 0.98 to 2.2 s. Unexpectedly, fast-dissociating yet specific antibodies are not so rare. A combination of fluorescently labeled Fab probes synthesized from these antibodies and light-sheet microscopy, such as dual-view inverted selective plane illumination microscopy (diSPIM), reveal rapid turnover of espin within long-lived F-actin cores of inner-ear sensory hair cell stereocilia, demonstrating that fast-dissociating specific antibodies can identify novel biological phenomena.
Collapse
Affiliation(s)
- Takushi Miyoshi
- Laboratory of Single-Molecule Cell Biology, Graduate School of Biostudies, Kyoto University, Kyoto 606-8501, Japan; Department of Pharmacology, Graduate School of Medicine, Kyoto University, Kyoto 606-8501, Japan; Department of Otolaryngology - Head and Neck Surgery, Graduate School of Medicine, Kyoto University, Kyoto 606-8507, Japan; Laboratory of Molecular Genetics, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD 20892, USA.
| | - Qianli Zhang
- Laboratory of Single-Molecule Cell Biology, Graduate School of Biostudies, Kyoto University, Kyoto 606-8501, Japan
| | - Takafumi Miyake
- Department of Pharmacology, Graduate School of Medicine, Kyoto University, Kyoto 606-8501, Japan; Department of Nephrology, Graduate School of Medicine, Kyoto University, Kyoto 606-8507, Japan
| | - Shin Watanabe
- Department of Pharmacology, Graduate School of Medicine, Kyoto University, Kyoto 606-8501, Japan
| | - Hiroe Ohnishi
- Department of Otolaryngology - Head and Neck Surgery, Graduate School of Medicine, Kyoto University, Kyoto 606-8507, Japan
| | - Jiji Chen
- Advanced Imaging and Microscopy Resource, National Institutes of Health, Bethesda, MD 20892, USA
| | - Harshad D Vishwasrao
- Advanced Imaging and Microscopy Resource, National Institutes of Health, Bethesda, MD 20892, USA
| | - Oisorjo Chakraborty
- Department of Biology, Indiana University-Purdue University Indianapolis, Indianapolis, IN 46202, USA
| | - Inna A Belyantseva
- Laboratory of Molecular Genetics, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD 20892, USA
| | - Benjamin J Perrin
- Department of Biology, Indiana University-Purdue University Indianapolis, Indianapolis, IN 46202, USA
| | - Hari Shroff
- Advanced Imaging and Microscopy Resource, National Institutes of Health, Bethesda, MD 20892, USA; Laboratory of High Resolution Optical Imaging, National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, Bethesda, MD 20892, USA
| | - Thomas B Friedman
- Laboratory of Molecular Genetics, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD 20892, USA
| | - Koichi Omori
- Department of Otolaryngology - Head and Neck Surgery, Graduate School of Medicine, Kyoto University, Kyoto 606-8507, Japan
| | - Naoki Watanabe
- Laboratory of Single-Molecule Cell Biology, Graduate School of Biostudies, Kyoto University, Kyoto 606-8501, Japan; Department of Pharmacology, Graduate School of Medicine, Kyoto University, Kyoto 606-8501, Japan.
| |
Collapse
|
33
|
Jiang F, Takagi Y, Shams A, Heissler SM, Friedman TB, Sellers JR, Bird JE. The ATPase mechanism of myosin 15, the molecular motor mutated in DFNB3 human deafness. J Biol Chem 2021; 296:100243. [PMID: 33372036 PMCID: PMC7948958 DOI: 10.1074/jbc.ra120.014903] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Revised: 12/23/2020] [Accepted: 12/28/2020] [Indexed: 11/18/2022] Open
Abstract
Cochlear hair cells each possess an exquisite bundle of actin-based stereocilia that detect sound. Unconventional myosin 15 (MYO15) traffics and delivers critical molecules required for stereocilia development and thus is essential for building the mechanosensory hair bundle. Mutations in the human MYO15A gene interfere with stereocilia trafficking and cause hereditary hearing loss, DFNB3, but the impact of these mutations is not known, as MYO15 itself is poorly characterized. To learn more, we performed a kinetic study of the ATPase motor domain to characterize its mechanochemical cycle. Using the baculovirus-Sf9 system, we purified a recombinant minimal motor domain (S1) by coexpressing the mouse MYO15 ATPase, essential and regulatory light chains that bind its IQ domains, and UNC45 and HSP90A chaperones required for correct folding of the ATPase. MYO15 purified with either UNC45A or UNC45B coexpression had similar ATPase activities (kcat = ∼ 6 s-1 at 20 °C). Using stopped-flow and quenched-flow transient kinetic analyses, we measured the major rate constants describing the ATPase cycle, including ATP, ADP, and actin binding; hydrolysis; and phosphate release. Actin-attached ADP release was the slowest measured transition (∼12 s-1 at 20 °C), although this did not rate-limit the ATPase cycle. The kinetic analysis shows the MYO15 motor domain has a moderate duty ratio (∼0.5) and weak thermodynamic coupling between ADP and actin binding. These findings are consistent with MYO15 being kinetically adapted for processive motility when oligomerized. Our kinetic characterization enables future studies into how deafness-causing mutations affect MYO15 and disrupt stereocilia trafficking necessary for hearing.
Collapse
Affiliation(s)
- Fangfang Jiang
- Department of Pharmacology and Therapeutics, and the Myology Institute, University of Florida College of Medicine, Gainesville, Florida, USA
| | - Yasuharu Takagi
- Laboratory of Molecular Physiology, Cell and Developmental Biology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Arik Shams
- Laboratory of Molecular Genetics, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, Maryland, USA
| | - Sarah M Heissler
- Department of Physiology and Cell Biology, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA
| | - Thomas B Friedman
- Laboratory of Molecular Genetics, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, Maryland, USA
| | - James R Sellers
- Laboratory of Molecular Physiology, Cell and Developmental Biology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Jonathan E Bird
- Department of Pharmacology and Therapeutics, and the Myology Institute, University of Florida College of Medicine, Gainesville, Florida, USA.
| |
Collapse
|
34
|
Park J, Lee M, Lee B, Castaneda N, Tetard L, Kang EH. Crowding tunes the organization and mechanics of actin bundles formed by crosslinking proteins. FEBS Lett 2020; 595:26-40. [PMID: 33020904 DOI: 10.1002/1873-3468.13949] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Revised: 09/14/2020] [Accepted: 09/21/2020] [Indexed: 01/05/2023]
Abstract
Fascin and α-actinin form higher-ordered actin bundles that mediate numerous cellular processes including cell morphogenesis and movement. While it is understood crosslinked bundle formation occurs in crowded cytoplasm, how crowding affects the bundling activities of the two crosslinking proteins is not known. Here, we demonstrate how solution crowding modulates the organization and mechanical properties of fascin- and α-actinin-induced bundles, utilizing total internal reflection fluorescence and atomic force microscopy imaging. Molecular dynamics simulations support the inference that crowding reduces binding interaction between actin filaments and fascin or the calponin homology 1 domain of α-actinin evidenced by interaction energy and hydrogen bonding analysis. Based on our findings, we suggest a mechanism of crosslinked actin bundle assembly and mechanics in crowded intracellular environments.
Collapse
Affiliation(s)
- Jinho Park
- NanoScience Technology Center, University of Central Florida, Orlando, FL, USA.,Department of Materials Science and Engineering, University of Central Florida, Orlando, FL, USA
| | - Myeongsang Lee
- NanoScience Technology Center, University of Central Florida, Orlando, FL, USA
| | - Briana Lee
- NanoScience Technology Center, University of Central Florida, Orlando, FL, USA
| | - Nicholas Castaneda
- NanoScience Technology Center, University of Central Florida, Orlando, FL, USA.,Burnett School of Biomedical Sciences, University of Central Florida, Orlando, FL, USA
| | - Laurene Tetard
- NanoScience Technology Center, University of Central Florida, Orlando, FL, USA.,Department of Physics, University of Central Florida, Orlando, FL, USA
| | - Ellen Hyeran Kang
- NanoScience Technology Center, University of Central Florida, Orlando, FL, USA.,Department of Materials Science and Engineering, University of Central Florida, Orlando, FL, USA.,Department of Physics, University of Central Florida, Orlando, FL, USA
| |
Collapse
|
35
|
Inaba Y, Chauhan V, van Loon AP, Choudhury LS, Sagasti A. Keratins and the plakin family cytolinker proteins control the length of epithelial microridge protrusions. eLife 2020; 9:58149. [PMID: 32894222 PMCID: PMC7535935 DOI: 10.7554/elife.58149] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Accepted: 09/04/2020] [Indexed: 02/06/2023] Open
Abstract
Actin filaments and microtubules create diverse cellular protrusions, but intermediate filaments, the strongest and most stable cytoskeletal elements, are not known to directly participate in the formation of protrusions. Here we show that keratin intermediate filaments directly regulate the morphogenesis of microridges, elongated protrusions arranged in elaborate maze-like patterns on the surface of mucosal epithelial cells. We found that microridges on zebrafish skin cells contained both actin and keratin filaments. Keratin filaments stabilized microridges, and overexpressing keratins lengthened them. Envoplakin and periplakin, plakin family cytolinkers that bind F-actin and keratins, localized to microridges, and were required for their morphogenesis. Strikingly, plakin protein levels directly dictate microridge length. An actin-binding domain of periplakin was required to initiate microridge morphogenesis, whereas periplakin-keratin binding was required to elongate microridges. These findings separate microridge morphogenesis into distinct steps, expand our understanding of intermediate filament functions, and identify microridges as protrusions that integrate actin and intermediate filaments.
Collapse
Affiliation(s)
- Yasuko Inaba
- Molecular, Cell and Developmental Biology Department and Molecular Biology Institute, University of California, Los Angeles, Los Angeles, United States
| | - Vasudha Chauhan
- Molecular, Cell and Developmental Biology Department and Molecular Biology Institute, University of California, Los Angeles, Los Angeles, United States
| | - Aaron Paul van Loon
- Molecular, Cell and Developmental Biology Department and Molecular Biology Institute, University of California, Los Angeles, Los Angeles, United States
| | - Lamia Saiyara Choudhury
- Molecular, Cell and Developmental Biology Department and Molecular Biology Institute, University of California, Los Angeles, Los Angeles, United States
| | - Alvaro Sagasti
- Molecular, Cell and Developmental Biology Department and Molecular Biology Institute, University of California, Los Angeles, Los Angeles, United States
| |
Collapse
|
36
|
Abstract
Mechanosensory bundles on auditory sensory cells are composed of stereocilia that grow in rows of decreasing height. This pattern depends on the specification of the eventual tallest row, then the assignment of distinct molecular identities to the shorter rows. Mechanotransduction refines and maintains row identity, thus instructing the form of the bundle.
Collapse
Affiliation(s)
- Jamis McGrath
- Department of Biology, Indiana University-Purdue University Indianapolis, Indianapolis, IN 46202, USA
| | - Benjamin J Perrin
- Department of Biology, Indiana University-Purdue University Indianapolis, Indianapolis, IN 46202, USA.
| |
Collapse
|
37
|
The integrity of cochlear hair cells is established and maintained through the localization of Dia1 at apical junctional complexes and stereocilia. Cell Death Dis 2020; 11:536. [PMID: 32678080 PMCID: PMC7366933 DOI: 10.1038/s41419-020-02743-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2020] [Revised: 07/01/2020] [Accepted: 07/03/2020] [Indexed: 02/07/2023]
Abstract
Dia1, which belongs to the diaphanous-related formin family, influences a variety of cellular processes through straight actin elongation activity. Recently, novel DIA1 mutants such as p.R1213X (p.R1204X) and p.A265S, have been reported to cause an autosomal dominant sensorineural hearing loss (DFNA1). Additionally, active DIA1 mutants induce progressive hearing loss in a gain-of-function manner. However, the subcellular localization and pathological function of DIA1(R1213X/R1204X) remains unknown. In the present study, we demonstrated the localization of endogenous Dia1 and the constitutively active DIA1 mutant in the cochlea, using transgenic mice expressing FLAG-tagged DIA1(R1204X) (DIA1-TG). Endogenous Dia1 and the DIA1 mutant were regionally expressed at the organ of Corti and the spiral ganglion from early life; alongside cochlear maturation, they became localized at the apical junctional complexes (AJCs) between hair cells (HCs) and supporting cells (SCs). To investigate HC vulnerability in the DIA1-TG mice, we exposed 4-week-old mice to moderate noise, which induced temporary threshold shifts with cochlear synaptopathy and ultrastructural changes in stereocilia 4 weeks post noise exposure. Furthermore, we established a knock-in (KI) mouse line expressing AcGFP-tagged DIA1(R1213X) (DIA1-KI) and confirmed mutant localization at AJCs and the tips of stereocilia in HCs. In MDCKAcGFP-DIA1(R1213X) cells with stable expression of AcGFP-DIA1(R1213X), AcGFP-DIA1(R1213X) revealed marked localization at microvilli on the apical surface of cells and decreased localization at cell-cell junctions. The DIA1-TG mice demonstrated hazy and ruffled circumferential actin belts at AJCs and abnormal stereocilia accompanied with HC loss at 5 months of age. In conclusion, Dia1 plays a pivotal role in the development and maintenance of AJCs and stereocilia, ensuring cochlear and HC integrity. Subclinical/latent vulnerability of HCs may be the cause of progressive hearing loss in DFNA1 patients, thus suggesting new therapeutic targets for preventing HC degeneration and progressive hearing loss associated with DFNA1.
Collapse
|
38
|
Sánchez-Benito D, Hyppolito MA, Alvarez-Morujo AJ, López DE, Gómez-Nieto R. Morphological and molecular correlates of altered hearing sensitivity in the genetically audiogenic seizure-prone hamster GASH/Sal. Hear Res 2020; 392:107973. [PMID: 32402894 DOI: 10.1016/j.heares.2020.107973] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/08/2020] [Revised: 03/30/2020] [Accepted: 04/07/2020] [Indexed: 02/08/2023]
Abstract
Rodent models of audiogenic seizures, in which seizures are precipitated by an abnormal response of the brain to auditory stimuli, are crucial to investigate the neural bases underlying ictogenesis. Despite significant advances in understanding seizure generation in the inferior colliculus, namely the epileptogenic nucleus, little is known about the contribution of lower auditory stations to the seizure-prone network. Here, we examined the cochlea and cochlear nucleus of the genetic audiogenic seizure hamster from Salamanca (GASH/Sal), a model of reflex epilepsy that exhibits generalized tonic-clonic seizures in response to loud sound. GASH/Sal animals under seizure-free conditions were compared with matched control hamsters in a multi-technical approach that includes auditory brainstem responses (ABR) testing, histology, scanning electron microscopy analysis, immunohistochemistry, quantitative morphometry and gene expression analysis (RT-qPCR). The cochlear histopathology of the GASH/Sal showed preservation of the sensory hair cells, but a significant loss of spiral ganglion neurons and mild atrophy of the stria vascularis. At the electron microscopy level, the reticular lamina exhibited disarray of stereociliary tufts with blebs, loss or elongated stereocilia as well as non-parallel rows of outer hair cells due to protrusions of Deiters' cells. At the molecular level, the abnormal gene expression patterns of prestin, cadherin 23, protocadherin 15, vesicular glutamate transporters 1 (Vglut1) and -2 (Vglut2) indicated that the hair-cell mechanotransduction and cochlear amplification were markedly altered. These were manifestations of a cochlear neuropathy that correlated to ABR waveform I alterations and elevated auditory thresholds. In the cochlear nucleus, the distribution of VGLUT2-immunolabeled puncta was differently affected in each subdivision, showing significant increases in magnocellular regions of the ventral cochlear nucleus and drastic reductions in the granule cell domain. This modified inputs lead to disruption of Vglut1 and Vglut2 gene expression in the cochlear nucleus. In sum, our study provides insight into the morphological and molecular traits associated with audiogenic seizure susceptibility in the GASH/Sal, suggesting an upward spread of abnormal glutamatergic transmission throughout the primary acoustic pathway to the epileptogenic region.
Collapse
Affiliation(s)
- David Sánchez-Benito
- Institute of Neuroscience of Castilla y León (INCYL), University of Salamanca, Salamanca, Spain; Institute of Biomedical Research of Salamanca (IBSAL), University of Salamanca, Salamanca, Spain
| | - Miguel A Hyppolito
- Laboratory of Neurobiology of Hearing, Department of Ophthalmology, Otorhinolaryngology, Head and Neck Surgery, Ribeirão Preto Medical School, University of São Paulo, São Paulo, Brazil
| | - Antonio J Alvarez-Morujo
- Institute of Neuroscience of Castilla y León (INCYL), University of Salamanca, Salamanca, Spain; Institute of Biomedical Research of Salamanca (IBSAL), University of Salamanca, Salamanca, Spain; Department of Human Anatomy and Histology, Faculty of Medicine, University of Salamanca, Salamanca, Spain
| | - Dolores E López
- Institute of Neuroscience of Castilla y León (INCYL), University of Salamanca, Salamanca, Spain; Institute of Biomedical Research of Salamanca (IBSAL), University of Salamanca, Salamanca, Spain; Department of Cell Biology and Pathology, Faculty of Medicine, University of Salamanca, Salamanca, Spain
| | - Ricardo Gómez-Nieto
- Institute of Neuroscience of Castilla y León (INCYL), University of Salamanca, Salamanca, Spain; Institute of Biomedical Research of Salamanca (IBSAL), University of Salamanca, Salamanca, Spain; Department of Cell Biology and Pathology, Faculty of Medicine, University of Salamanca, Salamanca, Spain.
| |
Collapse
|
39
|
Song J, Patterson R, Metlagel Z, Krey JF, Hao S, Wang L, Ng B, Sazzed S, Kovacs J, Wriggers W, He J, Barr-Gillespie PG, Auer M. A cryo-tomography-based volumetric model of the actin core of mouse vestibular hair cell stereocilia lacking plastin 1. J Struct Biol 2020; 210:107461. [PMID: 31962158 DOI: 10.1016/j.jsb.2020.107461] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2019] [Revised: 01/11/2020] [Accepted: 01/14/2020] [Indexed: 12/11/2022]
Abstract
Electron cryo-tomography allows for high-resolution imaging of stereocilia in their native state. Because their actin filaments have a higher degree of order, we imaged stereocilia from mice lacking the actin crosslinker plastin 1 (PLS1). We found that while stereocilia actin filaments run 13 nm apart in parallel for long distances, there were gaps of significant size that were stochastically distributed throughout the actin core. Actin crosslinkers were distributed through the stereocilium, but did not occupy all possible binding sites. At stereocilia tips, protein density extended beyond actin filaments, especially on the side of the tip where a tip link is expected to anchor. Along the shaft, repeating density was observed that corresponds to actin-to-membrane connectors. In the taper region, most actin filaments terminated near the plasma membrane. The remaining filaments twisted together to make a tighter bundle than was present in the shaft region; the spacing between them decreased from 13 nm to 9 nm, and the apparent filament diameter decreased from 6.4 to 4.8 nm. Our models illustrate detailed features of distinct structural domains that are present within the stereocilium.
Collapse
Affiliation(s)
- Junha Song
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Roma Patterson
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Zoltan Metlagel
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Jocelyn F Krey
- Oregon Hearing Research Center & Vollum Institute, Oregon Health & Science University, Portland, OR, USA
| | - Samantha Hao
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Linshanshan Wang
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Brian Ng
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Salim Sazzed
- Department of Computer Science, Old Dominion University, Norfolk, VA, USA
| | - Julio Kovacs
- Department of Mechanical and Aerospace Engineering, Old Dominion University, Norfolk, VA, USA
| | - Willy Wriggers
- Department of Mechanical and Aerospace Engineering, Old Dominion University, Norfolk, VA, USA
| | - Jing He
- Department of Computer Science, Old Dominion University, Norfolk, VA, USA
| | - Peter G Barr-Gillespie
- Oregon Hearing Research Center & Vollum Institute, Oregon Health & Science University, Portland, OR, USA.
| | - Manfred Auer
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
| |
Collapse
|
40
|
Myosin-XVa Controls Both Staircase Architecture and Diameter Gradation of Stereocilia Rows in the Auditory Hair Cell Bundles. J Assoc Res Otolaryngol 2020; 21:121-135. [PMID: 32152769 DOI: 10.1007/s10162-020-00745-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2019] [Accepted: 02/04/2020] [Indexed: 02/08/2023] Open
Abstract
Mammalian hair cells develop their mechanosensory bundles through consecutive phases of stereocilia elongation, thickening, and retraction of supernumerary stereocilia. Many molecules involved in stereocilia elongation have been identified, including myosin-XVa. Significantly less is known about molecular mechanisms of stereocilia thickening and retraction. Here, we used scanning electron microscopy (SEM) to quantify postnatal changes in number and diameters of the auditory hair cell stereocilia in shaker-2 mice (Myo15sh2) that lack both "long" and "short" isoforms of myosin-XVa, and in mice lacking only the "long" myosin-XVa isoform (Myo15∆N). Previously, we observed large mechanotransduction current in young postnatal inner (IHC) and outer (OHC) hair cells of both these strains. Stereocilia counts showed nearly identical developmental retraction of supernumerary stereocilia in control heterozygous, Myo15sh2/sh2, and Myo15∆N/∆N mice, suggesting that this retraction is largely unaffected by myosin-XVa deficiency. However, myosin-XVa deficiency does affect stereocilia diameters. In control, the first (tallest) and second row stereocilia grow in diameter simultaneously. However, the third row stereocilia in IHCs grow only until postnatal day 1-2 and then become thinner. In OHCs, they also grow slower than taller stereocilia, forming a stereocilia diameter gradation within a hair bundle. The sh2 mutation disrupts this gradation and makes all stereocilia nearly identical in thickness in both IHCs and OHCs, with only subtle residual diameter differences. All Myo15sh2/sh2 stereocilia grow postnatally including the third row, which is not a part of normal development. Serial sections with focused ion beam (FIB)-SEM confirmed that diameter changes of Myo15sh2/sh2 IHC and OHC stereocilia resulted from corresponding changes of their actin cores. In contrast to Myo15sh2/sh2, Myo15∆N/∆N hair cells develop prominent stereocilia diameter gradation. Thus, besides building the staircase, the short isoform of myosin-XVa is essential for controlling the diameter of the third row stereocilia and formation of the stereocilia diameter gradation in a hair bundle.
Collapse
|
41
|
Friedman TB, Belyantseva IA, Frolenkov GI. Myosins and Hearing. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2020; 1239:317-330. [DOI: 10.1007/978-3-030-38062-5_13] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
|
42
|
Bullen A, Forge A, Wright A, Richardson GP, Goodyear RJ, Taylor R. Ultrastructural defects in stereocilia and tectorial membrane in aging mouse and human cochleae. J Neurosci Res 2019; 98:1745-1763. [DOI: 10.1002/jnr.24556] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2019] [Revised: 10/24/2019] [Accepted: 10/28/2019] [Indexed: 12/14/2022]
Affiliation(s)
- Anwen Bullen
- UCL Ear Institute University College London London UK
| | - Andrew Forge
- UCL Ear Institute University College London London UK
| | | | - Guy P. Richardson
- Sussex Neuroscience School of Life Sciences University of Sussex Falmer, Brighton UK
| | - Richard J. Goodyear
- Sussex Neuroscience School of Life Sciences University of Sussex Falmer, Brighton UK
| | - Ruth Taylor
- UCL Ear Institute University College London London UK
| |
Collapse
|
43
|
Chandrasekaran A, Upadhyaya A, Papoian GA. Remarkable structural transformations of actin bundles are driven by their initial polarity, motor activity, crosslinking, and filament treadmilling. PLoS Comput Biol 2019; 15:e1007156. [PMID: 31287817 PMCID: PMC6615854 DOI: 10.1371/journal.pcbi.1007156] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Accepted: 06/06/2019] [Indexed: 12/12/2022] Open
Abstract
Bundled actin structures play a key role in maintaining cellular shape, in aiding force transmission to and from extracellular substrates, and in affecting cellular motility. Recent studies have also brought to light new details on stress generation, force transmission and contractility of actin bundles. In this work, we are primarily interested in the question of what determines the stability of actin bundles and what network geometries do unstable bundles eventually transition to. To address this problem, we used the MEDYAN mechano-chemical force field, modeling several micron-long actin bundles in 3D, while accounting for a comprehensive set of chemical, mechanical and transport processes. We developed a hierarchical clustering algorithm for classification of the different long time scale morphologies in our study. Our main finding is that initially unipolar bundles are significantly more stable compared with an apolar initial configuration. Filaments within the latter bundles slide easily with respect to each other due to myosin activity, producing a loose network that can be subsequently severely distorted. At high myosin concentrations, a morphological transition to aster-like geometries was observed. We also investigated how actin treadmilling rates influence bundle dynamics, and found that enhanced treadmilling leads to network fragmentation and disintegration, while this process is opposed by myosin and crosslinking activities. Interestingly, treadmilling bundles with an initial apolar geometry eventually evolve to a whole gamut of network morphologies based on relative positions of filament ends, such as sarcomere-like organization. We found that apolar bundles show a remarkable sensitivity to environmental conditions, which may be important in enabling rapid cytoskeletal structural reorganization and adaptation in response to intracellular and extracellular cues.
Collapse
Affiliation(s)
- Aravind Chandrasekaran
- Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland, United States of America
- Institute for Physical Science and Technology, University of Maryland, College Park, Maryland, United States of America
| | - Arpita Upadhyaya
- Institute for Physical Science and Technology, University of Maryland, College Park, Maryland, United States of America
- Department of Physics, University of Maryland, College Park, United States of America
| | - Garegin A. Papoian
- Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland, United States of America
- Institute for Physical Science and Technology, University of Maryland, College Park, Maryland, United States of America
| |
Collapse
|
44
|
Wagner EL, Shin JB. Mechanisms of Hair Cell Damage and Repair. Trends Neurosci 2019; 42:414-424. [PMID: 30992136 DOI: 10.1016/j.tins.2019.03.006] [Citation(s) in RCA: 62] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2019] [Revised: 03/04/2019] [Accepted: 03/13/2019] [Indexed: 01/22/2023]
Abstract
Sensory hair cells of the inner ear are exposed to continuous mechanical stress, causing damage over time. The maintenance of hair cells is further challenged by damage from a variety of other ototoxic factors, including loud noise, aging, genetic defects, and ototoxic drugs. This damage can manifest in many forms, from dysfunction of the hair cell mechanotransduction complex to loss of specialized ribbon synapses, and may even result in hair cell death. Given that mammalian hair cells do not regenerate, the repair of hair cell damage is important for continued auditory function throughout life. Here, we discuss how several key hair cell structures can be damaged, and what is known about how they are repaired.
Collapse
Affiliation(s)
- Elizabeth L Wagner
- Department of Neuroscience, University of Virginia-School of Medicine, Charlottesville, VA 22908, USA; Department of Biochemistry and Molecular Genetics, University of Virginia-School of Medicine, Charlottesville, VA 22908, USA
| | - Jung-Bum Shin
- Department of Neuroscience, University of Virginia-School of Medicine, Charlottesville, VA 22908, USA.
| |
Collapse
|
45
|
Tadenev ALD, Akturk A, Devanney N, Mathur PD, Clark AM, Yang J, Tarchini B. GPSM2-GNAI Specifies the Tallest Stereocilia and Defines Hair Bundle Row Identity. Curr Biol 2019; 29:921-934.e4. [PMID: 30827920 DOI: 10.1016/j.cub.2019.01.051] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2018] [Revised: 12/12/2018] [Accepted: 01/21/2019] [Indexed: 12/12/2022]
Abstract
The transduction compartment of inner ear hair cells, the hair bundle, is composed of stereocilia rows of graded height, a property essential for sensory function that remains poorly understood at the molecular level. We previously showed that GPSM2-GNAI is enriched at stereocilia distal tips and required for their postnatal elongation and bundle morphogenesis-two characteristics shared with MYO15A (short isoform), WHRN, and EPS8 proteins. Here we first performed a comprehensive genetic analysis of the mouse auditory epithelium to show that GPSM2, GNAI, MYO15A, and WHRN operate in series within the same pathway. To understand how these functionally disparate proteins act as an obligate complex, we then systematically analyzed their distribution in normal and mutant bundles over time. We discovered that WHRN-GPSM2-GNAI is an extra module recruited by and added to a pre-existing MYO15A-EPS8 stereocilia tip complex. This extended complex is only present in the first, tallest row, and is required to stabilize larger amounts of MYO15A-EPS8 than in shorter rows, which at tips harbor only MYO15A-EPS8. In the absence of GPSM2 or GNAI function, including in the epistatic Myo15a and Whrn mutants, bundles retain an embryonic-like organization that coincides with generic stereocilia at the molecular level. We propose that GPSM2-GNAI confers on the first row its unique tallest identity and participates in generating differential row identity across the hair bundle.
Collapse
Affiliation(s)
| | - Anil Akturk
- The Jackson Laboratory, Bar Harbor, ME 04609, USA
| | | | - Pranav Dinesh Mathur
- Department of Ophthalmology and Visual Sciences, Moran Eye Center, University of Utah, Salt Lake City, UT 84132, USA
| | - Anna M Clark
- Department of Ophthalmology and Visual Sciences, Moran Eye Center, University of Utah, Salt Lake City, UT 84132, USA
| | - Jun Yang
- Department of Ophthalmology and Visual Sciences, Moran Eye Center, University of Utah, Salt Lake City, UT 84132, USA; Department of Neurobiology and Anatomy, University of Utah, 20 North 1900 East, Salt Lake City, UT 84132, USA; Division of Otolaryngology, Department of Surgery, University of Utah, 50 North Medical Drive, Salt Lake City, UT 84132, USA
| | - Basile Tarchini
- The Jackson Laboratory, Bar Harbor, ME 04609, USA; Department of Medicine, Tufts University, Boston, MA 02111, USA; Graduate School of Biomedical Science and Engineering (GSBSE), University of Maine, Orono, ME 04469, USA.
| |
Collapse
|
46
|
Ueyama T. Rho-Family Small GTPases: From Highly Polarized Sensory Neurons to Cancer Cells. Cells 2019; 8:cells8020092. [PMID: 30696065 PMCID: PMC6406560 DOI: 10.3390/cells8020092] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2018] [Revised: 01/19/2019] [Accepted: 01/23/2019] [Indexed: 12/22/2022] Open
Abstract
The small GTPases of the Rho-family (Rho-family GTPases) have various physiological functions, including cytoskeletal regulation, cell polarity establishment, cell proliferation and motility, transcription, reactive oxygen species (ROS) production, and tumorigenesis. A relatively large number of downstream targets of Rho-family GTPases have been reported for in vitro studies. However, only a small number of signal pathways have been established at the in vivo level. Cumulative evidence for the functions of Rho-family GTPases has been reported for in vivo studies using genetically engineered mouse models. It was based on different cell- and tissue-specific conditional genes targeting mice. In this review, we introduce recent advances in in vivo studies, including human patient trials on Rho-family GTPases, focusing on highly polarized sensory organs, such as the cochlea, which is the primary hearing organ, host defenses involving reactive oxygen species (ROS) production, and tumorigenesis (especially associated with RAC, novel RAC1-GSPT1 signaling, RHOA, and RHOBTB2).
Collapse
Affiliation(s)
- Takehiko Ueyama
- Laboratory of Molecular Pharmacology, Biosignal Research Center, Kobe University, Kobe 657-8501, Japan.
| |
Collapse
|
47
|
Jansen S, Goode BL. Tropomyosin isoforms differentially tune actin filament length and disassembly. Mol Biol Cell 2019; 30:671-679. [PMID: 30650006 PMCID: PMC6589703 DOI: 10.1091/mbc.e18-12-0815] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Cellular actin networks exhibit diverse filamentous architectures and turnover dynamics, but how these differences are specified remains poorly understood. Here, we used multicolor total internal reflection fluorescence microscopy to ask how decoration of actin filaments by five biologically prominent Tropomyosin (TPM) isoforms influences disassembly induced by Cofilin alone, or by the collaborative effects of Cofilin, Coronin, and AIP1 (CCA). TPM decoration restricted Cofilin binding to pointed ends, while not interfering with Coronin binding to filament sides. Different isoforms of TPM provided variable levels of protection against disassembly, with the strongest protection by Tpm3.1 and the weakest by Tpm1.6. In biomimetic assays in which filaments were simultaneously assembled by formins and disassembled by CCA, these TPM isoform-specific effects persisted, giving rise to filaments with different lengths and treadmilling behavior. Together, our data reveal that TPM isoforms have quantitatively distinct abilities to tune actin filament length and turnover.
Collapse
Affiliation(s)
- Silvia Jansen
- Department of Cell Biology and Physiology, Washington University in St. Louis, St. Louis, MO 63110
| | - Bruce L Goode
- Department of Biology, Rosenstiel Basic Medical Science Research Center, Brandeis University, Waltham, MA 02454
| |
Collapse
|
48
|
Vélez-Ortega AC, Frolenkov GI. Building and repairing the stereocilia cytoskeleton in mammalian auditory hair cells. Hear Res 2019; 376:47-57. [PMID: 30638948 DOI: 10.1016/j.heares.2018.12.012] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/11/2018] [Revised: 12/19/2018] [Accepted: 12/28/2018] [Indexed: 10/27/2022]
Abstract
Despite all recent achievements in identification of the molecules that are essential for the structure and mechanosensory function of stereocilia bundles in the auditory hair cells of mammalian species, we still have only a rudimentary understanding of the mechanisms of stereocilia formation, maintenance, and repair. Important molecular differences distinguishing mammalian auditory hair cells from hair cells of other types and species have been recently revealed. In addition, we are beginning to solve the puzzle of the apparent life-long stability of the stereocilia bundles in these cells. New data link the stability of the cytoskeleton in the mammalian auditory stereocilia with the normal activity of mechanotransduction channels. These data suggest new ideas on how a terminally-differentiated non-regenerating hair cell in the mammalian cochlea may repair and tune its stereocilia bundle throughout the life span of the organism.
Collapse
Affiliation(s)
- A Catalina Vélez-Ortega
- Department of Physiology, University of Kentucky, 800 Rose St., Lexington, KY, 40536-0298, USA.
| | - Gregory I Frolenkov
- Department of Physiology, University of Kentucky, 800 Rose St., Lexington, KY, 40536-0298, USA.
| |
Collapse
|
49
|
Pelaseyed T, Bretscher A. Regulation of actin-based apical structures on epithelial cells. J Cell Sci 2018; 131:131/20/jcs221853. [PMID: 30333133 DOI: 10.1242/jcs.221853] [Citation(s) in RCA: 59] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Cells of transporting epithelia are characterized by the presence of abundant F-actin-based microvilli on their apical surfaces. Likewise, auditory hair cells have highly reproducible rows of apical stereocilia (giant microvilli) that convert mechanical sound into an electrical signal. Analysis of mutations in deaf patients has highlighted the critical components of tip links between stereocilia, and related structures that contribute to the organization of microvilli on epithelial cells have been found. Ezrin/radixin/moesin (ERM) proteins, which are activated by phosphorylation, provide a critical link between the plasma membrane and underlying actin cytoskeleton in surface structures. Here, we outline recent insights into how microvilli and stereocilia are built, and the roles of tip links. Furthermore, we highlight how ezrin is locally regulated by phosphorylation, and that this is necessary to maintain polarity. Localized phosphorylation is achieved through an intricate coincidence detection mechanism that requires the membrane lipid phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2] and the apically localized ezrin kinase, lymphocyte-oriented kinase (LOK, also known as STK10) or Ste20-like kinase (SLK). We also discuss how ezrin-binding scaffolding proteins regulate microvilli and how, despite these significant advances, it remains to be discovered how the cell polarity program ultimately interfaces with these processes.
Collapse
Affiliation(s)
- Thaher Pelaseyed
- Institute of Biomedicine, Department of Medical Biochemistry and Cell Biology, University of Gothenburg, SE-405 30 Gothenburg, Sweden
| | - Anthony Bretscher
- Weill Institute for Cell and Molecular Biology, Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, USA
| |
Collapse
|
50
|
Abstract
Sensory hair cells are specialized secondary sensory cells that mediate our senses of hearing, balance, linear acceleration, and angular acceleration (head rotation). In addition, hair cells in fish and amphibians mediate sensitivity to water movement through the lateral line system, and closely related electroreceptive cells mediate sensitivity to low-voltage electric fields in the aquatic environment of many fish species and several species of amphibian. Sensory hair cells share many structural and functional features across all vertebrate groups, while at the same time they are specialized for employment in a wide variety of sensory tasks. The complexity of hair cell structure is large, and the diversity of hair cell applications in sensory systems exceeds that seen for most, if not all, sensory cell types. The intent of this review is to summarize the more significant structural features and some of the more interesting and important physiological mechanisms that have been elucidated thus far. Outside vertebrates, hair cells are only known to exist in the coronal organ of tunicates. Electrical resonance, electromotility, and their exquisite mechanical sensitivity all contribute to the attractiveness of hair cells as a research subject.
Collapse
|