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Grande V, Schuld J, van der Ven PFM, Gruss OJ, Fürst DO. Filamin-A-interacting protein 1 (FILIP1) is a dual compartment protein linking myofibrils and microtubules during myogenic differentiation and upon mechanical stress. Cell Tissue Res 2023:10.1007/s00441-023-03776-4. [PMID: 37178194 DOI: 10.1007/s00441-023-03776-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Accepted: 04/19/2023] [Indexed: 05/15/2023]
Abstract
Variations in the gene encoding filamin-A-interacting protein 1 (FILIP1) were identified to be associated with a combination of neurological and muscular symptoms. While FILIP1 was shown to regulate motility of brain ventricular zone cells, a process important for corticogenesis, the function of the protein in muscle cells has been less well characterized. The expression of FILIP1 in regenerating muscle fibres predicted a role in early muscle differentiation. Here we analysed expression and localization of FILIP1 and its binding partners filamin-C (FLNc) and microtubule plus-end-binding protein EB3 in differentiating cultured myotubes and adult skeletal muscle. Prior to the development of cross-striated myofibrils, FILIP1 is associated with microtubules and colocalizes with EB3. During further myofibril maturation its localization changes, and FILIP1 localizes to myofibrillar Z-discs together with the actin-binding protein FLNc. Forced contractions of myotubes by electrical pulse stimulation (EPS) induce focal disruptions in myofibrils and translocation of both proteins from Z-discs to these lesions, suggesting a role in induction and/or repair of these structures. The immediate proximity of tyrosylated, dynamic microtubules and EB3 to lesions implies that also these play a role in these processes. This implication is supported by the fact that in nocodazole-treated myotubes that lack functional microtubules, the number of lesions induced by EPS is significantly reduced. In summary, we here show that FILIP1 is a cytolinker protein that is associated with both microtubules and actin filaments, and might play a role in the assembly of myofibrils and their stabilization upon mechanical stress to protect them from damage.
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Affiliation(s)
- Valentina Grande
- Institute for Cell Biology, University of Bonn, Ulrich-Haberland-Str. 61a, 53121, Bonn, Germany
| | - Julia Schuld
- Institute for Cell Biology, University of Bonn, Ulrich-Haberland-Str. 61a, 53121, Bonn, Germany
| | - Peter F M van der Ven
- Institute for Cell Biology, University of Bonn, Ulrich-Haberland-Str. 61a, 53121, Bonn, Germany
| | - Oliver J Gruss
- Institute of Genetics, University of Bonn, Karlrobert-Kreiten-Str. 13, 53115, Bonn, Germany
| | - Dieter O Fürst
- Institute for Cell Biology, University of Bonn, Ulrich-Haberland-Str. 61a, 53121, Bonn, Germany.
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2
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Wang J, Fan Y, Wang C, Dube S, Poiesz BJ, Dube DK, Ma Z, Sanger JM, Sanger JW. Inhibitors of the Ubiquitin Proteasome System block myofibril assembly in cardiomyocytes derived from chick embryos and human pluripotent stem cells. Cytoskeleton (Hoboken) 2022; 78:461-491. [PMID: 35502133 DOI: 10.1002/cm.21697] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Revised: 04/14/2022] [Accepted: 04/19/2022] [Indexed: 11/06/2022]
Abstract
Details of sarcomeric protein assembly during de novo myofibril formation closely resemble myofibrillogenesis in skeletal and cardiac myocytes in birds, rodents and zebrafish. The arrangement of proteins during myofibrillogenesis follows a three-step process: beginning with premyofibrils, followed by nascent myofibrils, and concluding with mature myofibrils (reviewed in Sanger et al., 2017). Our aim is to determine if the same pathway is followed in human cardiomyocytes derived from human inducible pluripotent stem cells. We found that the human cardiomyocytes developed patterns of protein organization identical to the three-step series seen in the model organisms cited above. Further experiments showed that myofibril assembly can be blocked at the nascent myofibril by five different inhibitors of the Ubiquitin Proteasome System (UPS) stage in both avian and human cardiomyocytes. With the exception of Carfilzomib, removal of the UPS inhibitors allows nascent myofibrils to proceed to mature myofibrils. Some proteasomal inhibitors, such as Bortezomib and Carfilzomib, used to treat multiple myeloma patients, have off-target effects of damage to hearts in three to six percent of these patients. These cardiovascular adverse events may result from prevention of mature myofibril formation in the cardiomyocytes. In summary, our results support a common three-step model for the formation of myofibrils ranging from avian to human cardiomyocytes. The Ubiquitin Proteasome System is required for progression from nascent myofibrils to mature myofibrils. Our experiments suggest a possible explanation for the cardiac and skeletal muscle off-target effects reported in multiple myeloma patients treated with proteasome inhibitors. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Jushuo Wang
- Department of Cell and Developmental Biology, SUNY Upstate Medical University, Syracuse, NY
| | - Yingli Fan
- Department of Cell and Developmental Biology, SUNY Upstate Medical University, Syracuse, NY
| | - Chenyan Wang
- Department of Biomedical & Chemical Engineering, The BioInspired Institute for Materials and Living Systems, Syracuse University, Syracuse, NY
| | - Syamalima Dube
- Department of Medicine, SUNY Upstate Medical University, Syracuse, NY
| | - Bernard J Poiesz
- Department of Medicine, SUNY Upstate Medical University, Syracuse, NY
| | - Dipak K Dube
- Department of Medicine, SUNY Upstate Medical University, Syracuse, NY
| | - Zhen Ma
- Department of Biomedical & Chemical Engineering, The BioInspired Institute for Materials and Living Systems, Syracuse University, Syracuse, NY
| | - Jean M Sanger
- Department of Cell and Developmental Biology, SUNY Upstate Medical University, Syracuse, NY
| | - Joseph W Sanger
- Department of Cell and Developmental Biology, SUNY Upstate Medical University, Syracuse, NY
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Kilic-Erkek O, Caner V, Abban-Mete G, Baris IC, Bor-Kucukatay M. Determination of the pathways of potential muscle damage and regeneration in response to acute and long-term swimming exercise in mice. Life Sci 2021; 272:119265. [PMID: 33626393 DOI: 10.1016/j.lfs.2021.119265] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Revised: 02/15/2021] [Accepted: 02/15/2021] [Indexed: 01/22/2023]
Abstract
The objective of the current study was examining early and late (3, 24 h) responses to acute, chronic swimming exercise as muscle damage and regeneration in gastrocnemius-soleus muscle complexes. We also aimed to reveal the signaling pathways involved. 8-12 weeks old mice were grouped as control, exercise. Exercising groups were firstly divided into two as acute and chronic, later every group was again divided in terms of time (3, 24 h) passed from the last exercise session until exsanguination. Acute exercise groups swam 30 min, while chronic swimming groups exercised 30 min/day, 5 days/week, 6 weeks. Histological investigations were performed to determine muscle damage and regeneration. Whole-genome expression analysis was applied to total RNA samples. Microarray data was confirmed by quantitative real-time PCR. Exercising mice muscle revealed enhanced damage, leukocyte infiltration. Increments in acute and chronic 3 h groups were statistically significant. Car3, Neb, Obscn, Ttn, Igfbp5, Igfbp7, Gsk3β, and Usp2 were down-regulated in muscles of swimming mice. The exercise-induced signaling pathways involved in muscle damage and regeneration were drawn. Our findings demonstrate that swimming induces muscle damage. Samples were obtained at 3 and 24 h following exercise, this time duration seems not sufficient for the development of myofibrillogenesis.
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Russell B, Solís C. Mechanosignaling pathways alter muscle structure and function by post-translational modification of existing sarcomeric proteins to optimize energy usage. J Muscle Res Cell Motil 2021; 42:367-380. [PMID: 33595762 DOI: 10.1007/s10974-021-09596-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2020] [Accepted: 01/04/2021] [Indexed: 12/29/2022]
Abstract
A transduced mechanical signal arriving at its destination in muscle alters sarcomeric structure and function. A major question addressed is how muscle mass and tension generation are optimized to match actual performance demands so that little energy is wasted. Three cases for improved energy efficiency are examined: the troponin complex for tuning force production, control of the myosin heads in a resting state, and the Z-disc proteins for sarcomere assembly. On arrival, the regulation of protein complexes is often controlled by post-translational modification (PTM), of which the most common are phosphorylation by kinases, deacetylation by histone deacetylases and ubiquitination by E3 ligases. Another branch of signals acts not through peptide covalent bonding but via ligand interactions (e.g. Ca2+ and phosphoinositide binding). The myosin head and the regulation of its binding to actin by the troponin complex is the best and earliest example of signal destinations that modify myofibrillar contractility. PTMs in the troponin complex regulate both the efficiency of the contractile function to match physiologic demand for work, and muscle mass via protein degradation. The regulation of sarcomere assembly by integration of incoming signaling pathways causing the same PTMs or ligand binding are discussed in response to mechanical loading and unloading by the Z-disc proteins CapZ, α-actinin, telethonin, titin N-termini, and others. Many human mutations that lead to cardiomyopathy and heart disease occur in the proteins discussed above, which often occur at their PTM or ligand binding sites.
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Affiliation(s)
- Brenda Russell
- Department of Physiology and Biophysics, College of Medicine, University of Illinois at Chicago, Chicago, IL, 60612, USA.
| | - Christopher Solís
- Department of Physiology and Biophysics, College of Medicine, University of Illinois at Chicago, Chicago, IL, 60612, USA
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Abstract
Class XVIII myosins represent a branch of the myosin family tree characterized by the presence of large N- and C-terminal extensions flanking a generic myosin core. These myosins display the highest sequence similarity to conventional class II muscle myosins and are compatible with but not restricted to myosin-2 contractile structures. Instead, they fulfill their functions at diverse localities, such as lamella, actomyosin bundles, the Golgi apparatus, focal adhesions, the cell membrane, and within sarcomeres. Sequence comparison of active-site residues and biochemical data available thus far indicate that this myosin class lacks active ATPase-driven motor activity, suggesting that its members function as structural myosins. An emerging body of evidence indicates that this structural capability is essential for the organization, maturation, and regulation of the contractile machinery in both muscle and nonmuscle cells. This is supported by the clear association of myosin-18A (Myo18A) and myosin-18B (Myo18B) dysregulation with diseases such as cancer and various myopathies.
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Wang J, Fan Y, Sanger JM, Sanger JW. Nonmuscle myosin II in cardiac and skeletal muscle cells. Cytoskeleton (Hoboken) 2019; 75:339-351. [PMID: 29781105 DOI: 10.1002/cm.21454] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2018] [Revised: 04/27/2018] [Accepted: 05/05/2018] [Indexed: 11/08/2022]
Abstract
De novo assembly of contractile myofibrils begins with the formation of premyofibrils where filaments of non-muscle myosin (NM II), and actin organize in sarcomeric patterns with Z-Bodies containing muscle-specific alpha-actinin. Interactions of muscle specific myosin (MM II) with NM II occur in a nascent myofibril stage that precedes the assembly of mature myofibrils. By the final stage of myofibrillogenesis, the only myosin II present in the mature myofibrils is MM II. In this current study of myofibril assembly, the three vertebrate isoforms of NM II (A, B, and C) and sarcomeric alpha-actinin, ligated to GFP family proteins, were coexpressed in avian embryonic skeletal and cardiac muscle cells. Each isoform of NM II localized only in the mini-A-Bands of premyofibrils and nascent myofibrils. There was no evidence of localization of NM II in Z-Bodies of premyofibrils and nascent myofibrils or in Z-Bands of mature myofibrils. Fluorescence Recovery After Photobleaching (FRAP) experiments indicated similar exchange rates in premyofibrils for NM II isoforms A and B, whereas the IIC isoform was significantly less dynamic. Fluorescence Resonance Energy Transfer (FRET) measurements of colocalized fluorescent pairs of different NM II isoforms yielded signals similar to identical pairs, indicating copolymerization of the different NM II pairs. The role of NM II may reside in establishing the future sarcomere pattern in mature myofibrils by binding to the oppositely polarized actin filaments that extend between pairs of Z-Bodies along premyofibrils prior to their transformation into mature myofibrils.
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Affiliation(s)
- Jushuo Wang
- Department of Cell and Developmental Biology, SUNY Upstate Medical University, Syracuse, New York, 13210
| | - Yingli Fan
- Department of Cell and Developmental Biology, SUNY Upstate Medical University, Syracuse, New York, 13210
| | - Jean M Sanger
- Department of Cell and Developmental Biology, SUNY Upstate Medical University, Syracuse, New York, 13210
| | - Joseph W Sanger
- Department of Cell and Developmental Biology, SUNY Upstate Medical University, Syracuse, New York, 13210
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Xu QH, Guan P, Zhang T, Lu C, Li G, Liu JX. Silver nanoparticles impair zebrafish skeletal and cardiac myofibrillogenesis and sarcomere formation. Aquat Toxicol 2018; 200:102-113. [PMID: 29729476 DOI: 10.1016/j.aquatox.2018.04.018] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2018] [Revised: 04/24/2018] [Accepted: 04/25/2018] [Indexed: 06/08/2023]
Abstract
Metal nanoparticles from industries contaminate the environment and affect the normal development of fish even human health. However, little is known about their biological effects on fish embryogenesis and the potential mechanisms. In this study, zebrafish embryos exposed to/injected with silver nanopaticles (AgNPs) exhibited shorter body, reduced heartbeats, and dysfunctional movements. Less, loose, and unassembled myofibrils were observed in AgNPs-treated embryos, and genes in myofibrillogenesis and sarcomere formation were found to be down-regulated in treated embryos. Down-regulated calcium (Ca2+) signaling and loci-specific DNA methylation in specific muscle genes, such as bves, shroom1, and arpc1a, occurred in AgNPs-treated embryos, which might result in the down-regulated expression of myofibrillogenesis genes and muscle dysfunctions in the treated embryos. Our results for the first time reveal that through down-regulating Ca2+ signaling and myogenic loci-specific DNA methylation in zebrafish embryos, AgNPs might induce defects of myofibril assembly and sarcomere formation via their particles mostly, which may subsequently cause heartbeat reduction and behavior dysfunctions.
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Affiliation(s)
- Qin-Han Xu
- College of Fisheries, Key Laboratory of Freshwater Animal Breeding, Ministry of Agriculture, Huazhong Agricultural University, Wuhan, 430070, China.
| | - PengPeng Guan
- College of Informatics, Agricultural Bioinformatics Key Laboratory of Hubei Province, Huazhong Agricultural University, Wuhan, 430070, China.
| | - Ting Zhang
- College of Fisheries, Key Laboratory of Freshwater Animal Breeding, Ministry of Agriculture, Huazhong Agricultural University, Wuhan, 430070, China.
| | - Chang Lu
- College of Fisheries, Key Laboratory of Freshwater Animal Breeding, Ministry of Agriculture, Huazhong Agricultural University, Wuhan, 430070, China.
| | - GuoLiang Li
- College of Informatics, Agricultural Bioinformatics Key Laboratory of Hubei Province, Huazhong Agricultural University, Wuhan, 430070, China.
| | - Jing-Xia Liu
- College of Fisheries, Key Laboratory of Freshwater Animal Breeding, Ministry of Agriculture, Huazhong Agricultural University, Wuhan, 430070, China; Collaborative Innovation Center for Efficient and Health Production of Fisheries in Hunan Province, Hunan, Changde, 415000, China.
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8
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Berkholz J, Eberle R, Boller K, Munz B. siRNA-mediated inhibition of skNAC and Smyd1 expression disrupts myofibril organization: Immunofluorescence and electron microscopy study in C2C12 cells. Micron 2018; 108:6-10. [PMID: 29499397 DOI: 10.1016/j.micron.2018.02.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2017] [Revised: 02/22/2018] [Accepted: 02/23/2018] [Indexed: 11/30/2022]
Abstract
skNAC (skeletal and heart muscle-specific variant of nascent polypeptide-associated complex) and Smyd1 (SET and MYND domain-containing 1) form a protein dimer which is specific for striated muscle cells. Its function is largely unknown. On the one hand, skNAC-Smyd1 appears to control transcriptional processes in the nucleus, on the other hand, specifically at later stages of myogenic differentiation, both proteins translocate to the sarcoplasm and at least Smyd1 specifically associates with sarcomeric structures and might control myofibrillogenesis and/or sarcomere architecture. Here, using immunofluorescence and electron microscopy, we analyzed sarcomere formation and myofibril organization after siRNA-mediated knockdown of skNAC or Smyd1 expression in murine C2C12 skeletal muscle cells. We found that inhibition of skNAC or Smyd1 expression indeed prevents myofibrillogenesis and sarcomere formation, leading to a disorganized array of myofilaments predominantly within the region immediately beneath the plasma membrane.
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Affiliation(s)
- Janine Berkholz
- Charité - University Medicine Berlin, Institute of Physiology, Charitéplatz 1, D-10117 Berlin, Germany
| | - Regina Eberle
- Paul-Ehrlich-Institute, Paul-Ehrlich-Str. 51-59, D-63225 Langen, Germany
| | - Klaus Boller
- Paul-Ehrlich-Institute, Paul-Ehrlich-Str. 51-59, D-63225 Langen, Germany
| | - Barbara Munz
- University Hospital Tubingen - Medical Clinic - Department of Sports Medicine, Hoppe-Seyler-Str. 6, D-72076 Tubingen, Germany.
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Lainé J, Skoglund G, Fournier E, Tabti N. Development of the excitation-contraction coupling machinery and its relation to myofibrillogenesis in human iPSC-derived skeletal myocytes. Skelet Muscle 2018; 8:1. [PMID: 29304851 PMCID: PMC5756430 DOI: 10.1186/s13395-017-0147-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2017] [Accepted: 12/08/2017] [Indexed: 01/25/2023] Open
Abstract
Background Human induced pluripotent stem cells-derived myogenic progenitors develop functional and ultrastructural features typical of skeletal muscle when differentiated in culture. Besides disease-modeling, such a system can be used to clarify basic aspects of human skeletal muscle development. In the present study, we focus on the development of the excitation-contraction (E-C) coupling, a process that is essential both in muscle physiology and as a tool to differentiate between the skeletal and cardiac muscle. The occurrence and maturation of E-C coupling structures (Sarcoplasmic Reticulum-Transverse Tubule (SR-TT) junctions), key molecular components, and Ca2+ signaling were examined, along with myofibrillogenesis. Methods Pax7+-myogenic progenitors were differentiated in culture, and developmental changes were examined from a few days up to several weeks. Ion channels directly involved in the skeletal muscle E-C coupling (RyR1 and Cav1.1 voltage-gated Ca2+ channels) were labeled using indirect immunofluorescence. Ultrastructural changes of differentiating cells were visualized by transmission electron microscopy. On the functional side, depolarization-induced intracellular Ca2+ transients mediating E-C coupling were recorded using Fura-2 ratiometric Ca2+ imaging, and myocyte contraction was captured by digital photomicrography. Results We show that the E-C coupling machinery occurs and operates within a few days post-differentiation, as soon as the myofilaments align. However, Ca2+ transients become effective in triggering myocyte contraction after 1 week of differentiation, when nascent myofibrils show alternate A-I bands. At later stages, myofibrils become fully organized into adult-like sarcomeres but SR-TT junctions do not reach their triadic structure and typical A-I location. This is mirrored by the absence of cross-striated distribution pattern of both RyR1 and Cav1.1 channels. Conclusions The E-C coupling machinery occurs and operates within the first week of muscle cells differentiation. However, while early development of SR-TT junctions is coordinated with that of nascent myofibrils, their respective maturation is not. Formation of typical triads requires other factors/conditions, and this should be taken into account when using in-vitro models to explore skeletal muscle diseases, especially those affecting E-C coupling. Electronic supplementary material The online version of this article (10.1186/s13395-017-0147-5) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Jeanne Lainé
- Département de Physiologie, Faculté de Médecine Pierre & Marie Curie site Pitié-Salpêtrière, UPMC, 91, Bd de l'Hôpital, 75013, Paris, France
| | - Gunnar Skoglund
- Département de Physiologie, Faculté de Médecine Pierre & Marie Curie site Pitié-Salpêtrière, UPMC, 91, Bd de l'Hôpital, 75013, Paris, France
| | - Emmanuel Fournier
- Département de Physiologie, Faculté de Médecine Pierre & Marie Curie site Pitié-Salpêtrière, UPMC, 91, Bd de l'Hôpital, 75013, Paris, France
| | - Nacira Tabti
- Département de Physiologie, Faculté de Médecine Pierre & Marie Curie site Pitié-Salpêtrière, UPMC, 91, Bd de l'Hôpital, 75013, Paris, France. .,UPEC, Créteil, France.
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10
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Kelu JJ, Webb SE, Parrington J, Galione A, Miller AL. Ca 2+ release via two-pore channel type 2 (TPC2) is required for slow muscle cell myofibrillogenesis and myotomal patterning in intact zebrafish embryos. Dev Biol 2017; 425:109-129. [PMID: 28390800 DOI: 10.1016/j.ydbio.2017.03.031] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2016] [Revised: 03/30/2017] [Accepted: 03/31/2017] [Indexed: 01/14/2023]
Abstract
We recently demonstrated a critical role for two-pore channel type 2 (TPC2)-mediated Ca2+ release during the differentiation of slow (skeletal) muscle cells (SMC) in intact zebrafish embryos, via the introduction of a translational-blocking morpholino antisense oligonucleotide (MO). Here, we extend our study and demonstrate that knockdown of TPC2 with a non-overlapping splice-blocking MO, knockout of TPC2 (via the generation of a tpcn2dhkz1a mutant line of zebrafish using CRISPR/Cas9 gene-editing), or the pharmacological inhibition of TPC2 action with bafilomycin A1 or trans-ned-19, also lead to a significant attenuation of SMC differentiation, characterized by a disruption of SMC myofibrillogenesis and gross morphological changes in the trunk musculature. When the morphants were injected with tpcn2-mRNA or were treated with IP3/BM or caffeine (agonists of the inositol 1,4,5-trisphosphate receptor (IP3R) and ryanodine receptor (RyR), respectively), many aspects of myofibrillogenesis and myotomal patterning (and in the case of the pharmacological treatments, the Ca2+ signals generated in the SMCs), were rescued. STED super-resolution microscopy revealed a close physical relationship between clusters of RyR in the terminal cisternae of the sarcoplasmic reticulum (SR), and TPC2 in lysosomes, with a mean estimated separation of ~52-87nm. Our data therefore add to the increasing body of evidence, which indicate that localized Ca2+ release via TPC2 might trigger the generation of more global Ca2+ release from the SR via Ca2+-induced Ca2+ release.
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MESH Headings
- Animals
- Base Sequence
- Behavior, Animal/drug effects
- Body Patterning/drug effects
- CRISPR-Cas Systems/genetics
- Caffeine/pharmacology
- Calcium/metabolism
- Calcium Channels/metabolism
- Calcium Signaling/drug effects
- Cell Death/drug effects
- Cells, Cultured
- Embryo, Nonmammalian/drug effects
- Embryo, Nonmammalian/metabolism
- Gene Knockdown Techniques
- Gene Knockout Techniques
- Inositol 1,4,5-Trisphosphate Receptors/metabolism
- Kinesins/metabolism
- Macrolides/pharmacology
- Models, Biological
- Morpholinos/pharmacology
- Motor Activity/drug effects
- Muscle Cells/cytology
- Muscle Cells/drug effects
- Muscle Cells/metabolism
- Muscle Development/drug effects
- Muscle Fibers, Slow-Twitch/cytology
- Muscle Fibers, Slow-Twitch/drug effects
- Muscle Fibers, Slow-Twitch/metabolism
- Phenotype
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Ryanodine Receptor Calcium Release Channel/metabolism
- Sarcomeres/drug effects
- Sarcomeres/metabolism
- Zebrafish/embryology
- Zebrafish/metabolism
- Zebrafish Proteins/metabolism
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Affiliation(s)
- Jeffrey J Kelu
- Division of Life Science & State Key Laboratory of Molecular Neuroscience, HKUST, Clear Water Bay, Hong Kong, PR China
| | - Sarah E Webb
- Division of Life Science & State Key Laboratory of Molecular Neuroscience, HKUST, Clear Water Bay, Hong Kong, PR China
| | - John Parrington
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford, UK
| | - Antony Galione
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford, UK
| | - Andrew L Miller
- Division of Life Science & State Key Laboratory of Molecular Neuroscience, HKUST, Clear Water Bay, Hong Kong, PR China; Marine Biological Laboratory, Woods Hole, MA, USA.
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11
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Weitkunat M, Brasse M, Bausch AR, Schnorrer F. Mechanical tension and spontaneous muscle twitching precede the formation of cross-striated muscle in vivo. Development 2017; 144:1261-1272. [PMID: 28174246 PMCID: PMC5399620 DOI: 10.1242/dev.140723] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2016] [Accepted: 01/28/2017] [Indexed: 02/05/2023]
Abstract
Muscle forces are produced by repeated stereotypical actomyosin units called sarcomeres. Sarcomeres are chained into linear myofibrils spanning the entire muscle fiber. In mammalian body muscles, myofibrils are aligned laterally, resulting in their typical cross-striated morphology. Despite this detailed textbook knowledge about the adult muscle structure, it is still unclear how cross-striated myofibrils are built in vivo. Here, we investigate the morphogenesis of Drosophila abdominal muscles and establish them as an in vivo model for cross-striated muscle development. By performing live imaging, we find that long immature myofibrils lacking a periodic actomyosin pattern are built simultaneously in the entire muscle fiber and then align laterally to give mature cross-striated myofibrils. Interestingly, laser micro-lesion experiments demonstrate that mechanical tension precedes the formation of the immature myofibrils. Moreover, these immature myofibrils do generate spontaneous Ca2+-dependent contractions in vivo, which, when chemically blocked, result in cross-striation defects. Taken together, these results suggest a myofibrillogenesis model in which mechanical tension and spontaneous muscle twitching synchronize the simultaneous self-organization of different sarcomeric protein complexes to build highly regular cross-striated myofibrils spanning the length of large muscle fibers. Summary: In Drosophila, immature myofibrils are built simultaneously across an entire muscle fiber, and then self-organize in a manner dependent on spontaneous contractions and mechanical tension.
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Affiliation(s)
- Manuela Weitkunat
- Muscle Dynamics Group, Max Planck Institute of Biochemistry, Am Klopferspitz 18, Martinsried 82152, Germany
| | - Martina Brasse
- Lehrstuhl für Biophysik E27, Technische Universität München, James-Franck-Straße 1, Garching 85748, Germany
| | - Andreas R Bausch
- Lehrstuhl für Biophysik E27, Technische Universität München, James-Franck-Straße 1, Garching 85748, Germany
| | - Frank Schnorrer
- Muscle Dynamics Group, Max Planck Institute of Biochemistry, Am Klopferspitz 18, Martinsried 82152, Germany .,Developmental Biology Institute of Marseille (IBDM), CNRS, UMR 7288, Aix-Marseille Université, Case 907, Parc Scientifique de Luminy, Marseille 13288, France
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12
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Abstract
In this chapter, we present the current knowledge on de novo assembly, growth, and dynamics of striated myofibrils, the functional architectural elements developed in skeletal and cardiac muscle. The data were obtained in studies of myofibrils formed in cultures of mouse skeletal and quail myotubes, in the somites of living zebrafish embryos, and in mouse neonatal and quail embryonic cardiac cells. The comparative view obtained revealed that the assembly of striated myofibrils is a three-step process progressing from premyofibrils to nascent myofibrils to mature myofibrils. This process is specified by the addition of new structural proteins, the arrangement of myofibrillar components like actin and myosin filaments with their companions into so-called sarcomeres, and in their precise alignment. Accompanying the formation of mature myofibrils is a decrease in the dynamic behavior of the assembling proteins. Proteins are most dynamic in the premyofibrils during the early phase and least dynamic in mature myofibrils in the final stage of myofibrillogenesis. This is probably due to increased interactions between proteins during the maturation process. The dynamic properties of myofibrillar proteins provide a mechanism for the exchange of older proteins or a change in isoforms to take place without disassembling the structural integrity needed for myofibril function. An important aspect of myofibril assembly is the role of actin-nucleating proteins in the formation, maintenance, and sarcomeric arrangement of the myofibrillar actin filaments. This is a very active field of research. We also report on several actin mutations that result in human muscle diseases.
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Affiliation(s)
- Joseph W Sanger
- Department of Cell and Developmental Biology, SUNY Upstate Medical University, 766 Irving Avenue, Syracuse, NY, 13224, USA.
| | - Jushuo Wang
- Department of Cell and Developmental Biology, SUNY Upstate Medical University, 766 Irving Avenue, Syracuse, NY, 13224, USA
| | - Yingli Fan
- Department of Cell and Developmental Biology, SUNY Upstate Medical University, 766 Irving Avenue, Syracuse, NY, 13224, USA
| | - Jennifer White
- Department of Cell and Developmental Biology, SUNY Upstate Medical University, 766 Irving Avenue, Syracuse, NY, 13224, USA
| | - Lei Mi-Mi
- Department of Cell and Developmental Biology, SUNY Upstate Medical University, 766 Irving Avenue, Syracuse, NY, 13224, USA
| | - Dipak K Dube
- Department of Cell and Developmental Biology, SUNY Upstate Medical University, 766 Irving Avenue, Syracuse, NY, 13224, USA
| | - Jean M Sanger
- Department of Cell and Developmental Biology, SUNY Upstate Medical University, 766 Irving Avenue, Syracuse, NY, 13224, USA
| | - David Pruyne
- Department of Cell and Developmental Biology, SUNY Upstate Medical University, 766 Irving Avenue, Syracuse, NY, 13224, USA.
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13
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Berger J, Tarakci H, Berger S, Li M, Hall TE, Arner A, Currie PD. Loss of Tropomodulin4 in the zebrafish mutant träge causes cytoplasmic rod formation and muscle weakness reminiscent of nemaline myopathy. Dis Model Mech 2014; 7:1407-15. [PMID: 25288681 PMCID: PMC4257009 DOI: 10.1242/dmm.017376] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Nemaline myopathy is an inherited muscle disease that is mainly diagnosed by the presence of nemaline rods in muscle biopsies. Of the nine genes associated with the disease, five encode components of striated muscle sarcomeres. In a genetic zebrafish screen, the mutant träge (trg) was isolated based on its reduction in muscle birefringence, indicating muscle damage. Myofibres in trg appeared disorganised and showed inhomogeneous cytoplasmic eosin staining alongside malformed nuclei. Linkage analysis of trg combined with sequencing identified a nonsense mutation in tropomodulin4 (tmod4), a regulator of thin filament length and stability. Accordingly, although actin monomers polymerize to form thin filaments in the skeletal muscle of tmod4trg mutants, thin filaments often appeared to be dispersed throughout myofibres. Organised myofibrils with the typical striation rarely assemble, leading to severe muscle weakness, impaired locomotion and early death. Myofibrils of tmod4trg mutants often featured thin filaments of various lengths, widened Z-disks, undefined H-zones and electron-dense aggregations of various shapes and sizes. Importantly, Gomori trichrome staining and the lattice pattern of the detected cytoplasmic rods, together with the reactivity of rods with phalloidin and an antibody against actinin, is reminiscent of nemaline rods found in nemaline myopathy, suggesting that misregulation of thin filament length causes cytoplasmic rod formation in tmod4trg mutants. Although Tropomodulin4 has not been associated with myopathy, the results presented here implicateTMOD4 as a novel candidate for unresolved nemaline myopathies and suggest that the tmod4trg mutant will be a valuable tool to study human muscle disorders.
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Affiliation(s)
- Joachim Berger
- Australian Regenerative Medicine Institute, Monash University, Clayton, VIC 3800, Australia
| | - Hakan Tarakci
- Australian Regenerative Medicine Institute, Monash University, Clayton, VIC 3800, Australia
| | - Silke Berger
- Australian Regenerative Medicine Institute, Monash University, Clayton, VIC 3800, Australia
| | - Mei Li
- Department of Physiology and Pharmacology, Karolinska Institute, Stockholm, SE 17177, Sweden
| | - Thomas E Hall
- Institute for Molecular Bioscience, University of Queensland, St Lucia, QLD 4072, Australia
| | - Anders Arner
- Department of Physiology and Pharmacology, Karolinska Institute, Stockholm, SE 17177, Sweden
| | - Peter D Currie
- Australian Regenerative Medicine Institute, Monash University, Clayton, VIC 3800, Australia
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14
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Abstract
Myofibrils in vertebrate cardiac and skeletal muscles are characterized by groups of proteins arranged in contractile units or sarcomeres, which consist of four major components – thin filaments, thick filaments, titin and Z-bands. The thin actin/tropomyosin-containing filaments are embedded in the Z-bands and interdigitate with the myosin-containing thick filaments aligned in A-bands. Titin is attached to the Z-band and extends upto the middle of the A-Band. In this mini review, we have addressed the mechanism of myofibril assembly as well as the dynamics and maintenance of the myofibrils in cardiac and skeletal muscle cells. Evidence from our research as well as from other laboratories favors the premyofibril model of myofibrillogenesis. This three-step model (premyofibril to nascent myofibril to mature myofibril) not only provides a reasonable mechanism for sequential interaction of various proteins during assembly of myofibrils, but also suggests why the dynamics of a thin filament protein like tropomyosin is higher in cardiac muscle than in skeletal muscles. The dynamics of tropomyosin not only varies in different muscle types (cardiac vs. skeletal), but also varies during myofibrillogenesis, for example, premyofibril versus mature myofibrils in skeletal muscle. One of the major differences in protein composition between cardiac and skeletal muscle is nebulin localized along the thin filaments (two nebulins/thin filament) of mature myofibrils in skeletal muscle cells, but which is expressed in a minimal quantity (one nebulin/50 actin filaments) in ventricular cardiomyocytes. Interestingly, nebulin is not associated with premyofibrils in skeletal muscle. Our FRAP(Fluorescence Recovery After Photobleaching) results suggest that tropomyosin is more dynamic in premyofibrils than in mature myofibrils in skeletal muscle, and also, the dynamics of tropomyosin in mature myofibrils is significantly higher in cardiac muscle compared to skeletal muscle. Our working hypothesis is that the association of nebulin in mature myofibrils renders tropomyosin less dynamic in skeletal muscle.
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Affiliation(s)
- D K Dube
- Department of Cell and Developmental Biology, SUNY Upstate Medical University, 750 East Adams Street, Syracuse, NY, USA
| | - J Wang
- Department of Cell and Developmental Biology, SUNY Upstate Medical University, 750 East Adams Street, Syracuse, NY, USA
| | - Y Fan
- Department of Cell and Developmental Biology, SUNY Upstate Medical University, 750 East Adams Street, Syracuse, NY, USA
| | - J M Sanger
- Department of Cell and Developmental Biology, SUNY Upstate Medical University, 750 East Adams Street, Syracuse, NY, USA
| | - J W Sanger
- Department of Cell and Developmental Biology, SUNY Upstate Medical University, 750 East Adams Street, Syracuse, NY, USA
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15
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Molt S, Bührdel JB, Yakovlev S, Schein P, Orfanos Z, Kirfel G, Winter L, Wiche G, van der Ven PFM, Rottbauer W, Just S, Belkin AM, Fürst DO. Aciculin interacts with filamin C and Xin and is essential for myofibril assembly, remodeling and maintenance. J Cell Sci 2014; 127:3578-92. [PMID: 24963132 DOI: 10.1242/jcs.152157] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Filamin C (FLNc) and Xin actin-binding repeat-containing proteins (XIRPs) are multi-adaptor proteins that are mainly expressed in cardiac and skeletal muscles and which play important roles in the assembly and repair of myofibrils and their attachment to the membrane. We identified the dystrophin-binding protein aciculin (also known as phosphoglucomutase-like protein 5, PGM5) as a new interaction partner of FLNc and Xin. All three proteins colocalized at intercalated discs of cardiac muscle and myotendinous junctions of skeletal muscle, whereas FLNc and aciculin also colocalized in mature Z-discs. Bimolecular fluorescence complementation experiments in developing cultured mammalian skeletal muscle cells demonstrated that Xin and aciculin also interact in FLNc-containing immature myofibrils and areas of myofibrillar remodeling and repair induced by electrical pulse stimulation (EPS). Fluorescence recovery after photobleaching (FRAP) experiments showed that aciculin is a highly dynamic and mobile protein. Aciculin knockdown in myotubes led to failure in myofibril assembly, alignment and membrane attachment, and a massive reduction in myofibril number. A highly similar phenotype was found upon depletion of aciculin in zebrafish embryos. Our results point to a thus far unappreciated, but essential, function of aciculin in myofibril formation, maintenance and remodeling.
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Affiliation(s)
- Sibylle Molt
- Institute for Cell Biology, University of Bonn, 53121 Bonn, Germany
| | - John B Bührdel
- Department of Internal Medicine II, University of Ulm, 89081 Ulm, Germany
| | - Sergiy Yakovlev
- University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Peter Schein
- Institute for Cell Biology, University of Bonn, 53121 Bonn, Germany
| | | | - Gregor Kirfel
- Institute for Cell Biology, University of Bonn, 53121 Bonn, Germany
| | - Lilli Winter
- Department of Biochemistry and Molecular Cell Biology, Max F. Perutz Laboratories, University of Vienna, 1030 Vienna, Austria
| | - Gerhard Wiche
- Department of Biochemistry and Molecular Cell Biology, Max F. Perutz Laboratories, University of Vienna, 1030 Vienna, Austria
| | | | - Wolfgang Rottbauer
- Department of Internal Medicine II, University of Ulm, 89081 Ulm, Germany
| | - Steffen Just
- Department of Internal Medicine II, University of Ulm, 89081 Ulm, Germany
| | - Alexey M Belkin
- University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Dieter O Fürst
- Institute for Cell Biology, University of Bonn, 53121 Bonn, Germany
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16
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Hotchkiss A, Feridooni T, Zhang F, Pasumarthi KBS. The effects of calcium channel blockade on proliferation and differentiation of cardiac progenitor cells. Cell Calcium 2014; 55:238-51. [PMID: 24680380 DOI: 10.1016/j.ceca.2014.02.018] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2013] [Revised: 02/16/2014] [Accepted: 02/26/2014] [Indexed: 12/20/2022]
Abstract
Cardiogenesis depends on a tightly regulated balance between proliferation and differentiation of cardiac progenitor cells (CPCs) and their cardiomyocyte descendants. While exposure of early mouse embryos to Ca(2+) channel antagonists has been associated with abnormal cardiac morphogenesis, less is known about the consequences of Ca(2+) channel blockade on proliferation and differentiation of CPCs at the cellular level. Here we showed that at embryonic day (E) 11.5, the murine ventricles express several L-type and T-type Ca(2+) channel isoforms, and that the dihydropyridine Ca(2+) channel antagonist, nifedipine, blunts isoproterenol induced increases in intracellular Ca(2+). Nifedipine mediated Ca(2+) channel blockade was associated with a reduction in cell cycle activity of E11.5 CPCs and impaired assembly of the cardiomyocyte contractile apparatus. Furthermore, in cell transplantation experiments, systemic administration of nifedipine to adult mice receiving transplanted E11.5 ventricular cells (containing CPCs and cardiomyocytes) was associated with smaller graft sizes compared to vehicle treated control animals. These data suggest that intracellular Ca(2+) is a critical regulator of the balance between CPC proliferation and differentiation and demonstrate that interactions between pharmacological drugs and transplanted cells could have a significant impact on the effectiveness of cell based therapies for myocardial repair.
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Affiliation(s)
- Adam Hotchkiss
- Department of Pharmacology, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Tiam Feridooni
- Department of Pharmacology, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Feixiong Zhang
- Department of Pharmacology, Dalhousie University, Halifax, Nova Scotia, Canada
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17
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Myhre JL, Hills JA, Prill K, Wohlgemuth SL, Pilgrim DB. The titin A-band rod domain is dispensable for initial thick filament assembly in zebrafish. Dev Biol 2013; 387:93-108. [PMID: 24370452 DOI: 10.1016/j.ydbio.2013.12.020] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2013] [Revised: 12/11/2013] [Accepted: 12/13/2013] [Indexed: 01/19/2023]
Abstract
The sarcomeres of skeletal and cardiac muscle are highly structured protein arrays, consisting of thick and thin filaments aligned precisely to one another and to their surrounding matrix. The contractile mechanisms of sarcomeres are generally well understood, but how the patterning of sarcomeres is initiated during early skeletal muscle and cardiac development remains uncertain. Two of the most widely accepted hypotheses for this process include the "molecular ruler" model, in which the massive protein titin defines the length of the sarcomere and provides a scaffold along which the myosin thick filament is assembled, and the "premyofibril" model, which proposes that thick filament formation does not require titin, but that a "premyofibril" consisting of non-muscle myosin, α-actinin and cytoskeletal actin is used as a template. Each model posits a different order of necessity of the various components, but these have been difficult to test in vivo. Zebrafish motility mutants with developmental defects in sarcomere patterning are useful for the elucidation of such mechanisms, and here we report the analysis of the herzschlag mutant, which shows deficits in both cardiac and skeletal muscle. The herzschlag mutant produces a truncated titin protein, lacking the C-terminal rod domain that is proposed to act as a thick filament scaffold, yet muscle patterning is still initiated, with grossly normal thick and thin filament assembly. Only after embryonic muscle contraction begins is breakdown of sarcomeric myosin patterning observed, consistent with the previously noted role of titin in maintaining the contractile integrity of mature sarcomeres. This conflicts with the "molecular ruler" model of early sarcomere patterning and supports a titin-independent model of thick filament organization during sarcomerogenesis. These findings are also consistent with the symptoms of human titin myopathies that exhibit a late onset, such as tibial muscular dystrophy.
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Affiliation(s)
- J Layne Myhre
- Department of Biological Sciences, CW405, Biological Sciences Building, University of Alberta, Edmonton, Canada AB T6G 2E9
| | - Jordan A Hills
- Department of Biological Sciences, CW405, Biological Sciences Building, University of Alberta, Edmonton, Canada AB T6G 2E9
| | - Kendal Prill
- Department of Biological Sciences, CW405, Biological Sciences Building, University of Alberta, Edmonton, Canada AB T6G 2E9
| | - Serene L Wohlgemuth
- Department of Biological Sciences, CW405, Biological Sciences Building, University of Alberta, Edmonton, Canada AB T6G 2E9
| | - David B Pilgrim
- Department of Biological Sciences, CW405, Biological Sciences Building, University of Alberta, Edmonton, Canada AB T6G 2E9.
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18
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Fero K, Bergeron SA, Horstick EJ, Codore H, Li GH, Ono F, Dowling JJ, Burgess HA. Impaired embryonic motility in dusp27 mutants reveals a developmental defect in myofibril structure. Dis Model Mech 2013; 7:289-98. [PMID: 24203884 PMCID: PMC3917250 DOI: 10.1242/dmm.013235] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
An essential step in muscle fiber maturation is the assembly of highly ordered myofibrils that are required for contraction. Much remains unknown about the molecular mechanisms governing the formation of the contractile apparatus. We identified an early embryonic motility mutant in zebrafish caused by integration of a transgene into the pseudophosphatase dual specificity phosphatase 27 (dusp27) gene. dusp27 mutants exhibit near complete paralysis at embryonic and larval stages, producing extremely low levels of spontaneous coiling movements and a greatly diminished touch response. Loss of dusp27 does not prevent somitogenesis but results in severe disorganization of the contractile apparatus in muscle fibers. Sarcomeric structures in mutants are almost entirely absent and only rare triads are observed. These findings are the first to implicate a functional role of dusp27 as a gene required for myofiber maturation and provide an animal model for analyzing the mechanisms governing myofibril assembly.
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Affiliation(s)
- Kandice Fero
- Program in Genomics of Differentiation, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, MD 20892, USA
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19
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Nworu CU, Krieg PA, Gregorio CC. Preparation of developing Xenopus muscle for sarcomeric protein localization by high-resolution imaging. Methods 2013; 66:370-9. [PMID: 23806641 DOI: 10.1016/j.ymeth.2013.06.015] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2013] [Revised: 06/12/2013] [Accepted: 06/13/2013] [Indexed: 11/16/2022] Open
Abstract
Mutations in several sarcomeric proteins have been linked to various human myopathies. Therefore, having an in vivo developmental model available that develops quickly and efficiently is key for investigators to elucidate the critical steps, components and signaling pathways involved in building a myofibril; this is the pivotal foundation for deciphering disease mechanisms as well as the development of myopathy-related therapeutics. Although striated muscle cell culture studies have been extremely informative in providing clues to both the distribution and functions of sarcomeric proteins, myocytes in vivo develop in an irreproducible 3D environment. Xenopus laevis (frog) embryos are cost effective, compliant to protein level manipulations and develop relatively quickly (⩽ a week) in a petri dish, thus providing a powerful system for de novo myofibrillogenesis studies. Although fluorophore-conjugated phalloidin labeling is the gold standard approach for investigating actin-thin filament architecture, it is well documented that phalloidin-labeling can be challenging and inconsistent within Xenopus embryos. Therefore we highlight several techniques that can be utilized to preserve both antibody and fluorophore-conjugated phalloidin labeling within Xenopus embryos for high-resolution fluorescence microscopy.
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Affiliation(s)
- Chinedu U Nworu
- Department of Cellular and Molecular Medicine and The Sarver Molecular Cardiovascular Research Program, The University of Arizona, Tucson, AZ 85724, USA
| | - Paul A Krieg
- Department of Cellular and Molecular Medicine and The Sarver Molecular Cardiovascular Research Program, The University of Arizona, Tucson, AZ 85724, USA
| | - Carol C Gregorio
- Department of Cellular and Molecular Medicine and The Sarver Molecular Cardiovascular Research Program, The University of Arizona, Tucson, AZ 85724, USA.
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20
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Kan-O M, Takeya R, Abe T, Kitajima N, Nishida M, Tominaga R, Kurose H, Sumimoto H. Mammalian formin Fhod3 plays an essential role in cardiogenesis by organizing myofibrillogenesis. Biol Open 2012; 1:889-96. [PMID: 23213483 PMCID: PMC3507241 DOI: 10.1242/bio.20121370] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2012] [Accepted: 06/18/2012] [Indexed: 11/20/2022] Open
Abstract
Heart development requires organized integration of actin filaments into the sarcomere, the contractile unit of myofibrils, although it remains largely unknown how actin filaments are assembled during myofibrillogenesis. Here we show that Fhod3, a member of the formin family of proteins that play pivotal roles in actin filament assembly, is essential for myofibrillogenesis at an early stage of heart development. Fhod3−/− mice appear normal up to embryonic day (E) 8.5, when the developing heart, composed of premyofibrils, initiates spontaneous contraction. However, these premyofibrils fail to mature and myocardial development does not continue, leading to embryonic lethality by E11.5. Transgenic expression of wild-type Fhod3 in the heart restores myofibril maturation and cardiomyogenesis, which allow Fhod3−/− embryos to develop further. Moreover, cardiomyopathic changes with immature myofibrils are caused in mice overexpressing a mutant Fhod3, defective in binding to actin. These findings indicate that actin dynamics, regulated by Fhod3, participate in sarcomere organization during myofibrillogenesis and thus play a crucial role in heart development.
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Affiliation(s)
- Meikun Kan-O
- Department of Biochemistry, Kyushu University Graduate School of Medical Sciences , 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582 , Japan
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21
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Dwyer J, Iskratsch T, Ehler E. Actin in striated muscle: recent insights into assembly and maintenance. Biophys Rev 2011; 4:17-25. [PMID: 28510000 DOI: 10.1007/s12551-011-0062-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2011] [Accepted: 11/17/2011] [Indexed: 01/28/2023] Open
Abstract
Striated muscle cells are characterised by a para-crystalline arrangement of their contractile proteins actin and myosin in sarcomeres, the basic unit of the myofibrils. A multitude of proteins is required to build and maintain the structure of this regular arrangement as well as to ensure regulation of contraction and to respond to alterations in demand. This review focuses on the actin filaments (also called thin filaments) of the sarcomere and will discuss how they are assembled during myofibrillogenesis and in hypertrophy and how their integrity is maintained in the working myocardium.
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Affiliation(s)
- Joseph Dwyer
- The Randall Division of Cell and Molecular Biophysics and The Cardiovascular Division, King's College London, British Heart Foundation Centre of Research Excellence, New Hunt's House, Guy's Campus, London, SE1 1UL, UK
| | - Thomas Iskratsch
- The Randall Division of Cell and Molecular Biophysics and The Cardiovascular Division, King's College London, British Heart Foundation Centre of Research Excellence, New Hunt's House, Guy's Campus, London, SE1 1UL, UK.,Biological Sciences, Columbia University, 713 Fairchild Center, New York, NY, 10027, USA
| | - Elisabeth Ehler
- The Randall Division of Cell and Molecular Biophysics and The Cardiovascular Division, King's College London, British Heart Foundation Centre of Research Excellence, New Hunt's House, Guy's Campus, London, SE1 1UL, UK.
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