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Ronconi-Krüger N, Müller YMR, Nazari EM. Exploring developmental MeHg impact on extraembryonic and cardiac vessels and its effect on cardiomyocyte contractility. J Appl Toxicol 2024. [PMID: 38978343 DOI: 10.1002/jat.4661] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2024] [Revised: 06/06/2024] [Accepted: 06/10/2024] [Indexed: 07/10/2024]
Abstract
The toxicity of methylmercury (MeHg) during embryonic development is a relevant issue that remains unclear and deserves investigation. In this sense, there is evidence that links the intake of contaminated food with cardiovascular pathologies in human adults and children. Thus, this study aimed to verify the impact of MeHg on the structure and integrity of extraembryonic and cardiac blood vessels and the contractile function of cardiomyocytes, also evaluating embryonic weight and the cardiosomatic index (CSI). Thus, chicken embryos, used as an experimental model, were exposed to a single dose of 0.1 μg MeHg/50 μl saline at E1.5 and analyzed at E10. After exposure, an increase in the number of extraembryonic blood vessels and the veins of the cardiac tissue was observed. These increases were accompanied by a reduction in the content of VEGF and VCAM proteins related to vessel growth and adhesiveness. Together, these results were related to reduced nitrite (NOx) levels. Furthermore, MeHg reduces the number of sarcomeres and increases the content of cardiac troponin I (cTnI), a protein that regulates contraction. In general, exposure to MeHg affected the integrity of extraembryonic and cardiac vessels and the contractile function of cardiomyocytes, which had a systemic impact evidenced by the reduction in embryonic weight gain and CSI.
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Affiliation(s)
- Nathália Ronconi-Krüger
- Departamento de Biologia Celular, Embriologia e Genética, Universidade Federal de Santa Catarina, Florianópolis, Santa Catarina, Brazil
| | - Yara Maria Rauh Müller
- Departamento de Biologia Celular, Embriologia e Genética, Universidade Federal de Santa Catarina, Florianópolis, Santa Catarina, Brazil
| | - Evelise Maria Nazari
- Departamento de Biologia Celular, Embriologia e Genética, Universidade Federal de Santa Catarina, Florianópolis, Santa Catarina, Brazil
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2
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Yeganeh FA, Summerill C, Hu Z, Rahmani H, Taylor DW, Taylor KA. The cryo-EM 3D image reconstruction of isolated Lethocerus indicus Z-discs. J Muscle Res Cell Motil 2023; 44:271-286. [PMID: 37661214 PMCID: PMC10843718 DOI: 10.1007/s10974-023-09657-1] [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: 02/14/2023] [Accepted: 08/14/2023] [Indexed: 09/05/2023]
Abstract
The Z-disk of striated muscle defines the ends of the sarcomere, which repeats many times within the muscle fiber. Here we report application of cryoelectron tomography and subtomogram averaging to Z-disks isolated from the flight muscles of the large waterbug Lethocerus indicus. We use high salt solutions to remove the myosin containing filaments and use gelsolin to remove the actin filaments of the A- and I-bands leaving only the thin filaments within the Z-disk which were then frozen for cryoelectron microscopy. The Lethocerus Z-disk structure is similar in many ways to the previously studied Z-disk of the honeybee Apis mellifera. At the corners of the unit cell are positioned trimers of paired antiparallel F-actins defining a large solvent channel, whereas at the trigonal positions are positioned F-actin trimers converging slowly towards their (+) ends defining a small solvent channel through the Z-disk. These near parallel F-actins terminate at different Z-heights within the Z-disk. The two types of solvent channel in Lethocerus are similar in size compared to those of Apis which are very different in size. Two types of α-actinin crosslinks were observed between oppositely oriented actin filaments. In one of these, the α-actinin long axis is almost parallel to the F-actins it crosslinks. In the other, the α-actinins are at a small but distinctive angle with respect to the crosslinked actin filaments. The utility of isolated Z-disks for structure determination is discussed.
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Affiliation(s)
- Fatemeh Abbasi Yeganeh
- Institute of Molecular Biophysics, Florida State University, Tallahassee, FL, 32306-4380, USA
| | - Corinne Summerill
- Institute of Molecular Biophysics, Florida State University, Tallahassee, FL, 32306-4380, USA
- Department of Life and Earth Sciences, Perimeter College, Georgia State University, 33 Gilmer Street SE, Atlanta, GA, 30303, USA
| | - Zhongjun Hu
- Institute of Molecular Biophysics, Florida State University, Tallahassee, FL, 32306-4380, USA
- Facebook, Inc, 1 Hacker Way, Menlo Park, CA, 94025, USA
| | - Hamidreza Rahmani
- Institute of Molecular Biophysics, Florida State University, Tallahassee, FL, 32306-4380, USA
- The Scripps Research Institute, La Jolla, CA, 92037, USA
| | - Dianne W Taylor
- Institute of Molecular Biophysics, Florida State University, Tallahassee, FL, 32306-4380, USA
| | - Kenneth A Taylor
- Institute of Molecular Biophysics, Florida State University, Tallahassee, FL, 32306-4380, USA.
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3
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Rodriguez Garcia M, Schmeckpeper J, Landim-Vieira M, Coscarella IL, Fang X, Ma W, Spran PA, Yuan S, Qi L, Kahmini AR, Shoemaker MB, Atkinson JB, Kekenes-Huskey PM, Irving TC, Chase PB, Knollmann BC, Pinto JR. Disruption of Z-Disc Function Promotes Mechanical Dysfunction in Human Myocardium: Evidence for a Dual Myofilament Modulatory Role by Alpha-Actinin 2. Int J Mol Sci 2023; 24:14572. [PMID: 37834023 PMCID: PMC10572656 DOI: 10.3390/ijms241914572] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2023] [Revised: 09/19/2023] [Accepted: 09/20/2023] [Indexed: 10/15/2023] Open
Abstract
The ACTN2 gene encodes α-actinin 2, located in the Z-disc of the sarcomeres in striated muscle. In this study, we sought to investigate the effects of an ACTN2 missense variant of unknown significance (p.A868T) on cardiac muscle structure and function. Left ventricular free wall samples were obtained at the time of cardiac transplantation from a heart failure patient with the ACTN2 A868T heterozygous variant. This variant is in the EF 3-4 domain known to interact with titin and α-actinin. At the ultrastructural level, ACTN2 A868T cardiac samples presented small structural changes in cardiomyocytes when compared to healthy donor samples. However, contractile mechanics of permeabilized ACTN2 A868T variant cardiac tissue displayed higher myofilament Ca2+ sensitivity of isometric force, reduced sinusoidal stiffness, and faster rates of tension redevelopment at all Ca2+ levels. Small-angle X-ray diffraction indicated increased separation between thick and thin filaments, possibly contributing to changes in muscle kinetics. Molecular dynamics simulations indicated that while the mutation does not significantly impact the structure of α-actinin on its own, it likely alters the conformation associated with titin binding. Our results can be explained by two Z-disc mediated communication pathways: one pathway that involves α-actinin's interaction with actin, affecting thin filament regulation, and the other pathway that involves α-actinin's interaction with titin, affecting thick filament activation. This work establishes the role of α-actinin 2 in modulating cross-bridge kinetics and force development in the human myocardium as well as how it can be involved in the development of cardiac disease.
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Affiliation(s)
| | - Jeffrey Schmeckpeper
- Department of Medicine, Division of Cardiovascular Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | | | | | - Xuan Fang
- Department of Cell & Molecular Physiology, Loyola University, Chicago, IL 60660, USA
| | - Weikang Ma
- BioCAT, Department of Biological Sciences, Illinois Institute of Technology, Chicago, IL 60616, USA
| | - Payton A. Spran
- Department of Biological Science, Florida State University, Tallahassee, FL 32306, USA
| | - Shengyao Yuan
- BioCAT, Department of Biological Sciences, Illinois Institute of Technology, Chicago, IL 60616, USA
| | - Lin Qi
- BioCAT, Department of Biological Sciences, Illinois Institute of Technology, Chicago, IL 60616, USA
| | - Aida Rahimi Kahmini
- Department of Nutrition and Integrative Physiology, Florida State University, Tallahassee, FL 32306, USA;
| | - M. Benjamin Shoemaker
- Department of Medicine, Division of Cardiovascular Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - James B. Atkinson
- Department of Pathology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | | | - Thomas C. Irving
- BioCAT, Department of Biological Sciences, Illinois Institute of Technology, Chicago, IL 60616, USA
| | - Prescott Bryant Chase
- Department of Biological Science, Florida State University, Tallahassee, FL 32306, USA
| | - Björn C. Knollmann
- Department of Medicine, Division of Cardiovascular Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Jose Renato Pinto
- Biomedical Sciences, Florida State University, Tallahassee, FL 32306, USA
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4
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Schöck F, González-Morales N. The insect perspective on Z-disc structure and biology. J Cell Sci 2022; 135:277280. [PMID: 36226637 DOI: 10.1242/jcs.260179] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Myofibrils are the intracellular structures formed by actin and myosin filaments. They are paracrystalline contractile cables with unusually well-defined dimensions. The sliding of actin past myosin filaments powers contractions, and the entire system is held in place by a structure called the Z-disc, which anchors the actin filaments. Myosin filaments, in turn, are anchored to another structure called the M-line. Most of the complex architecture of myofibrils can be reduced to studying the Z-disc, and recently, important advances regarding the arrangement and function of Z-discs in insects have been published. On a very small scale, we have detailed protein structure information. At the medium scale, we have cryo-electron microscopy maps, super-resolution microscopy and protein-protein interaction networks, while at the functional scale, phenotypic data are available from precise genetic manipulations. All these data aim to answer how the Z-disc works and how it is assembled. Here, we summarize recent data from insects and explore how it fits into our view of the Z-disc, myofibrils and, ultimately, muscles.
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Affiliation(s)
- Frieder Schöck
- Department of Biology, McGill University, Montreal, Quebec, H3A 1B1, Canada
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5
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Kardum Hjort C, Paris JR, Olsson P, Herbertsson L, de Miranda JR, Dudaniec RY, Smith HG. Genomic divergence and a lack of recent introgression between commercial and wild bumblebees ( Bombus terrestris). Evol Appl 2022; 15:365-382. [PMID: 35386397 PMCID: PMC8965379 DOI: 10.1111/eva.13346] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2021] [Revised: 12/08/2021] [Accepted: 01/17/2022] [Indexed: 11/27/2022] Open
Abstract
The global movement of bees for agricultural pollination services can affect local pollinator populations via hybridization. When commercial bumblebees are of the same species but of different geographic origin, intraspecific hybridization may result in beneficial integration of new genetic variation, or alternatively may disrupt locally adapted gene complexes. However, neither the existence nor the extent of genomic introgression and evolutionary divergence between wild and commercial bumblebees is fully understood. We obtained whole-genome sequencing data from wild and commercial Bombus terrestris collected from sites in Southern Sweden with and without long-term use of commercially imported B. terrestris. We search for evidence of introgression, dispersal and genome-wide differentiation in a comparative genomic analysis of wild and commercial bumblebees. Commercial B. terrestris were found in natural environments near sites where commercial bumblebees were used, as well as drifting wild B. terrestris in commercial bumblebee colonies. However, we found no evidence for widespread, recent genomic introgression of commercial B. terrestris into local wild conspecific populations. We found that wild B. terrestris had significantly higher nucleotide diversity (Nei's pi, π), while the number of segregating sites (Watterson's theta, θw) was higher in commercial B. terrestris. A highly divergent region on chromosome 11 was identified in commercial B. terrestris and found to be enriched with structural variants. The genes present in this region are involved in flight muscle contraction and structure and pathogen immune response, providing evidence for differing evolutionary processes operating in wild and commercial B. terrestris. We did not find evidence for recent introgression, suggesting that co-occurring commercial B. terrestris have not disrupted evolutionary processes in wild B. terrestris populations.
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Affiliation(s)
- Cecilia Kardum Hjort
- Department of BiologyLund UniversityLundSweden
- School of Natural SciencesMacquarie UniversitySydneyAustralia
| | - Josephine R. Paris
- BiosciencesCollege of Life and Environmental ScienceUniversity of ExeterExeterUK
| | | | - Lina Herbertsson
- Centre for Environmental and Climate ScienceLund UniversityLundSweden
| | | | | | - Henrik G. Smith
- Department of BiologyLund UniversityLundSweden
- Centre for Environmental and Climate ScienceLund UniversityLundSweden
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6
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Oda T, Yanagisawa H. Cryo-electron tomography of cardiac myofibrils reveals a 3D lattice spring within the Z-discs. Commun Biol 2020; 3:585. [PMID: 33067529 PMCID: PMC7567829 DOI: 10.1038/s42003-020-01321-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2020] [Accepted: 09/25/2020] [Indexed: 01/29/2023] Open
Abstract
The Z-disc forms a boundary between sarcomeres, which constitute structural and functional units of striated muscle tissue. Actin filaments from adjacent sarcomeres are cross-bridged by α-actinin in the Z-disc, allowing transmission of tension across the myofibril. Despite decades of studies, the 3D structure of Z-disc has remained elusive due to the limited resolution of conventional electron microscopy. Here, we observed porcine cardiac myofibrils using cryo-electron tomography and reconstructed the 3D structures of the actin-actinin cross-bridging complexes within the Z-discs in relaxed and activated states. We found that the α-actinin dimers showed contraction-dependent swinging and sliding motions in response to a global twist in the F-actin lattice. Our observation suggests that the actin-actinin complex constitutes a molecular lattice spring, which maintains the integrity of the Z-disc during the muscle contraction cycle.
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Affiliation(s)
- Toshiyuki Oda
- Department of Anatomy and Structural Biology, Graduate School of Medicine, University of Yamanashi, 1110 Shimokato, Chuo, Yamanashi, 409-3898, Japan.
| | - Haruaki Yanagisawa
- Department of Cell Biology and Anatomy, Graduate School of Medicine, the University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan
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7
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Szikora S, Gajdos T, Novák T, Farkas D, Földi I, Lenart P, Erdélyi M, Mihály J. Nanoscopy reveals the layered organization of the sarcomeric H-zone and I-band complexes. J Cell Biol 2020; 219:132617. [PMID: 31816054 PMCID: PMC7039190 DOI: 10.1083/jcb.201907026] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2019] [Revised: 10/04/2019] [Accepted: 10/22/2019] [Indexed: 01/18/2023] Open
Abstract
Sarcomeres are extremely highly ordered macromolecular assemblies where structural organization is intimately linked to their functionality as contractile units. Although the structural basis of actin and Myosin interaction is revealed at a quasiatomic resolution, much less is known about the molecular organization of the I-band and H-zone. We report the development of a powerful nanoscopic approach, combined with a structure-averaging algorithm, that allowed us to determine the position of 27 sarcomeric proteins in Drosophila melanogaster flight muscles with a quasimolecular, ∼5- to 10-nm localization precision. With this protein localization atlas and template-based protein structure modeling, we have assembled refined I-band and H-zone models with unparalleled scope and resolution. In addition, we found that actin regulatory proteins of the H-zone are organized into two distinct layers, suggesting that the major place of thin filament assembly is an M-line-centered narrow domain where short actin oligomers can form and subsequently anneal to the pointed end.
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Affiliation(s)
- Szilárd Szikora
- Institute of Genetics, Biological Research Centre, Hungarian Academy of Sciences, Szeged, Hungary.,Department of Optics and Quantum Electronics, University of Szeged, Szeged, Hungary
| | - Tamás Gajdos
- Department of Optics and Quantum Electronics, University of Szeged, Szeged, Hungary
| | - Tibor Novák
- Department of Optics and Quantum Electronics, University of Szeged, Szeged, Hungary
| | - Dávid Farkas
- Institute of Genetics, Biological Research Centre, Hungarian Academy of Sciences, Szeged, Hungary.,Doctoral School in Biology, Faculty of Science and Informatics, University of Szeged, Szeged, Hungary
| | - István Földi
- Institute of Genetics, Biological Research Centre, Hungarian Academy of Sciences, Szeged, Hungary
| | - Peter Lenart
- Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Miklós Erdélyi
- Department of Optics and Quantum Electronics, University of Szeged, Szeged, Hungary
| | - József Mihály
- Institute of Genetics, Biological Research Centre, Hungarian Academy of Sciences, Szeged, Hungary.,Department of Optics and Quantum Electronics, University of Szeged, Szeged, Hungary
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8
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Khadangi A, Hanssen E, Rajagopal V. Automated segmentation of cardiomyocyte Z-disks from high-throughput scanning electron microscopy data. BMC Med Inform Decis Mak 2019; 19:272. [PMID: 31856827 PMCID: PMC6921388 DOI: 10.1186/s12911-019-0962-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
Background With the advent of new high-throughput electron microscopy techniques such as serial block-face scanning electron microscopy (SBF-SEM) and focused ion-beam scanning electron microscopy (FIB-SEM) biomedical scientists can study sub-cellular structural mechanisms of heart disease at high resolution and high volume. Among several key components that determine healthy contractile function in cardiomyocytes are Z-disks or Z-lines, which are located at the lateral borders of the sarcomere, the fundamental unit of striated muscle. Z-disks play the important role of anchoring contractile proteins within the cell that make the heartbeat. Changes to their organization can affect the force with which the cardiomyocyte contracts and may also affect signaling pathways that regulate cardiomyocyte health and function. Compared to other components in the cell, such as mitochondria, Z-disks appear as very thin linear structures in microscopy data with limited difference in contrast to the remaining components of the cell. Methods In this paper, we propose to generate a 3D model of Z-disks within single adult cardiac cells from an automated segmentation of a large serial-block-face scanning electron microscopy (SBF-SEM) dataset. The proposed fully automated segmentation scheme is comprised of three main modules including “pre-processing”, “segmentation” and “refinement”. We represent a simple, yet effective model to perform segmentation and refinement steps. Contrast stretching, and Gaussian kernels are used to pre-process the dataset, and well-known “Sobel operators” are used in the segmentation module. Results We have validated our model by comparing segmentation results with ground-truth annotated Z-disks in terms of pixel-wise accuracy. The results show that our model correctly detects Z-disks with 90.56% accuracy. We also compare and contrast the accuracy of the proposed algorithm in segmenting a FIB-SEM dataset against the accuracy of segmentations from a machine learning program called Ilastik and discuss the advantages and disadvantages that these two approaches have. Conclusions Our validation results demonstrate the robustness and reliability of our algorithm and model both in terms of validation metrics and in terms of a comparison with a 3D visualisation of Z-disks obtained using immunofluorescence based confocal imaging.
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Affiliation(s)
- Afshin Khadangi
- Cell Structure and Mechanobiology Group, Department of Biomedical Engineering, Melbourne School of Engineering, The University of Melbourne, Melbourne, Australia.
| | - Eric Hanssen
- Advanced Microscopy Facility, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Melbourne, Australia
| | - Vijay Rajagopal
- Cell Structure and Mechanobiology Group, Department of Biomedical Engineering, Melbourne School of Engineering, The University of Melbourne, Melbourne, Australia
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9
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González-Morales N, Xiao YS, Schilling MA, Marescal O, Liao KA, Schöck F. Myofibril diameter is set by a finely tuned mechanism of protein oligomerization in Drosophila. eLife 2019; 8:50496. [PMID: 31746737 PMCID: PMC6910826 DOI: 10.7554/elife.50496] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2019] [Accepted: 11/18/2019] [Indexed: 11/13/2022] Open
Abstract
Myofibrils are huge cytoskeletal assemblies embedded in the cytosol of muscle cells. They consist of arrays of sarcomeres, the smallest contractile unit of muscles. Within a muscle type, myofibril diameter is highly invariant and contributes to its physiological properties, yet little is known about the underlying mechanisms setting myofibril diameter. Here we show that the PDZ and LIM domain protein Zasp, a structural component of Z-discs, mediates Z-disc and thereby myofibril growth through protein oligomerization. Oligomerization is induced by an interaction of its ZM domain with LIM domains. Oligomerization is terminated upon upregulation of shorter Zasp isoforms which lack LIM domains at later developmental stages. The balance between these two isoforms, which we call growing and blocking isoforms sets the stereotyped diameter of myofibrils. If blocking isoforms dominate, myofibrils become smaller. If growing isoforms dominate, myofibrils and Z-discs enlarge, eventually resulting in large pathological aggregates that disrupt muscle function.
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Affiliation(s)
| | - Yu Shu Xiao
- Department of Biology, McGill University, Montreal, Canada
| | | | | | - Kuo An Liao
- Department of Biology, McGill University, Montreal, Canada
| | - Frieder Schöck
- Department of Biology, McGill University, Montreal, Canada
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10
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Bradshaw M, Paul DM. After the revolution: how is Cryo-EM contributing to muscle research? J Muscle Res Cell Motil 2019; 40:93-98. [PMID: 31302812 PMCID: PMC6726666 DOI: 10.1007/s10974-019-09537-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2019] [Accepted: 07/02/2019] [Indexed: 12/21/2022]
Abstract
The technique of electron microscopy (EM) has been fundamental to muscle research since the days of Huxley and Hanson. Direct observation of how proteins in the sarcomere are arranged and visualising the changes that occur upon activation have greatly increased our understanding of function. In the 1980s specimen preparation techniques for biological EM moved away from traditional fixing and staining. The technique known as cryo-electron microscopy (Cryo-EM) was developed, which involves rapidly freezing proteins in liquid ethane which maintains them in a near native state. Within the last 5 years there has been a step change in the achievable resolution using Cryo-EM. This ‘resolution revolution’ can be attributed to advances in detector technology, microscope automation and maximum likelihood image processing. In this article we look at how Cryo-EM has contributed to the field of muscle research in this post revolution era, focussing on recently published high resolution structures of sarcomeric proteins.
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Affiliation(s)
- Marston Bradshaw
- Department of Physiology & Pharmacology, University of Bristol, Bristol, BS8 1TD, UK
| | - Danielle M Paul
- Department of Physiology & Pharmacology, University of Bristol, Bristol, BS8 1TD, UK.
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11
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Hu G, Taylor DW, Liu J, Taylor KA. Identification of interfaces involved in weak interactions with application to F-actin-aldolase rafts. J Struct Biol 2017; 201:199-209. [PMID: 29146292 DOI: 10.1016/j.jsb.2017.11.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2017] [Revised: 11/09/2017] [Accepted: 11/12/2017] [Indexed: 10/18/2022]
Abstract
Macromolecular interactions occur with widely varying affinities. Strong interactions form well defined interfaces but weak interactions are more dynamic and variable. Weak interactions can collectively lead to large structures such as microvilli via cooperativity and are often the precursors of much stronger interactions, e.g. the initial actin-myosin interaction during muscle contraction. Electron tomography combined with subvolume alignment and classification is an ideal method for the study of weak interactions because a 3-D image is obtained for the individual interactions, which subsequently are characterized collectively. Here we describe a method to characterize heterogeneous F-actin-aldolase interactions in 2-D rafts using electron tomography. By forming separate averages of the two constituents and fitting an atomic structure to each average, together with the alignment information which relates the raw motif to the average, an atomic model of each crosslink is determined and a frequency map of contact residues is computed. The approach should be applicable to any large structure composed of constituents that interact weakly and heterogeneously.
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Affiliation(s)
- Guiqing Hu
- Institute of Molecular Biophysics, Florida State University, Tallahassee, FL 32306-4380, United States
| | - Dianne W Taylor
- Institute of Molecular Biophysics, Florida State University, Tallahassee, FL 32306-4380, United States
| | - Jun Liu
- Institute of Molecular Biophysics, Florida State University, Tallahassee, FL 32306-4380, United States
| | - Kenneth A Taylor
- Institute of Molecular Biophysics, Florida State University, Tallahassee, FL 32306-4380, United States.
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