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Ceron RH, Báez-Cruz FA, Palmer NJ, Carman PJ, Boczkowska M, Heuckeroth RO, Ostap EM, Dominguez R. Molecular mechanisms linking missense ACTG2 mutations to visceral myopathy. SCIENCE ADVANCES 2024; 10:eadn6615. [PMID: 38820162 PMCID: PMC11141634 DOI: 10.1126/sciadv.adn6615] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2023] [Accepted: 04/29/2024] [Indexed: 06/02/2024]
Abstract
Visceral myopathy is a life-threatening disease characterized by muscle weakness in the bowel, bladder, and uterus. Mutations in smooth muscle γ-actin (ACTG2) are the most common cause of the disease, but the mechanisms by which the mutations alter muscle function are unknown. Here, we examined four prevalent ACTG2 mutations (R40C, R148C, R178C, and R257C) that cause different disease severity and are spread throughout the actin fold. R178C displayed premature degradation, R148C disrupted interactions with actin-binding proteins, R40C inhibited polymerization, and R257C destabilized filaments. Because these mutations are heterozygous, we also analyzed 50/50 mixtures with wild-type (WT) ACTG2. The WT/R40C mixture impaired filament nucleation by leiomodin 1, and WT/R257C produced filaments that were easily fragmented by smooth muscle myosin. Smooth muscle tropomyosin isoform Tpm1.4 partially rescued the defects of R40C and R257C. Cryo-electron microscopy structures of filaments formed by R40C and R257C revealed disrupted intersubunit contacts. The biochemical and structural properties of the mutants correlate with their genotype-specific disease severity.
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Affiliation(s)
- Rachel H. Ceron
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
- The Children’s Hospital of Philadelphia Research Institute, Philadelphia, PA 19104, USA
| | - Faviolla A. Báez-Cruz
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
- Biochemistry and Molecular Biophysics Graduate Group, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Nicholas J. Palmer
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
- Biochemistry and Molecular Biophysics Graduate Group, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Peter J. Carman
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
- Biochemistry and Molecular Biophysics Graduate Group, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Malgorzata Boczkowska
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Robert O. Heuckeroth
- The Children’s Hospital of Philadelphia Research Institute, Philadelphia, PA 19104, USA
- Department of Pediatrics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - E. Michael Ostap
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
- Biochemistry and Molecular Biophysics Graduate Group, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Roberto Dominguez
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
- Biochemistry and Molecular Biophysics Graduate Group, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
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2
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Mooren OL, McConnell P, DeBrecht JD, Jaysingh A, Cooper JA. Reconstitution of Arp2/3-Nucleated Actin Assembly with CP, V-1 and CARMIL. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.13.593916. [PMID: 38798690 PMCID: PMC11118340 DOI: 10.1101/2024.05.13.593916] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2024]
Abstract
Actin polymerization is often associated with membrane proteins containing capping-protein-interacting (CPI) motifs, such as CARMIL, CD2AP, and WASHCAP/Fam21. CPI motifs bind directly to actin capping protein (CP), and this interaction weakens the binding of CP to barbed ends of actin filaments, lessening the ability of CP to functionally cap those ends. The protein V-1 / myotrophin binds to the F-actin binding site on CP and sterically blocks CP from binding barbed ends. CPI-motif proteins also weaken the binding between V-1 and CP, which decreases the inhibitory effects of V-1, thereby freeing CP to cap barbed ends. Here, we address the question of whether CPI-motif proteins on a surface analogous to a membrane lead to net activation or inhibition of actin assembly nucleated by Arp2/3 complex. Using reconstitution with purified components, we discovered that CARMIL at the surface promotes and enhances actin assembly, countering the inhibitory effects of V-1 and thus activating CP. The reconstitution involves the presence of an Arp2/3 activator on the surface, along with Arp2/3 complex, V-1, CP, profilin and actin monomers in solution, recreating key features of cell physiology.
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Affiliation(s)
- Olivia L Mooren
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO
| | - Patrick McConnell
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO
| | - James D DeBrecht
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO
| | - Anshuman Jaysingh
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO
| | - John A Cooper
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO
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3
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Garg A, Jansen S, Zhang R, Lavine KJ, Greenberg MJ. Dilated cardiomyopathy-associated skeletal muscle actin (ACTA1) mutation R256H disrupts actin structure and function and causes cardiomyocyte hypocontractility. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.10.583979. [PMID: 38559046 PMCID: PMC10979883 DOI: 10.1101/2024.03.10.583979] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/04/2024]
Abstract
Skeletal muscle actin (ACTA1) mutations are a prevalent cause of skeletal myopathies consistent with ACTA1's high expression in skeletal muscle. Rare de novo mutations in ACTA1 associated with combined cardiac and skeletal myopathies have been reported, but ACTA1 represents only ~20% of the total actin pool in cardiomyocytes, making its role in cardiomyopathy controversial. Here we demonstrate how a mutation in an actin isoform expressed at low levels in cardiomyocytes can cause cardiomyopathy by focusing on a unique ACTA1 mutation, R256H. We previously identified this mutation in multiple family members with dilated cardiomyopathy (DCM), who had reduced systolic function without clinical skeletal myopathy. Using a battery of multiscale biophysical tools, we show that R256H has potent functional effects on ACTA1 function at the molecular scale and in human cardiomyocytes. Importantly, we demonstrate that R256H acts in a dominant manner, where the incorporation of small amounts of mutant protein into thin filaments is sufficient to disrupt molecular contractility, and that this effect is dependent on the presence of troponin and tropomyosin. To understand the structural basis of this change in regulation, we resolved a structure of R256H filaments using Cryo-EM, and we see alterations in actin's structure that have the potential to disrupt interactions with tropomyosin. Finally, we show that ACTA1R256H/+ human induced pluripotent stem cell cardiomyocytes demonstrate reduced contractility and sarcomeric disorganization. Taken together, we demonstrate that R256H has multiple effects on ACTA1 function that are sufficient to cause reduced contractility and establish a likely causative relationship between ACTA1 R256H and clinical cardiomyopathy.
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Affiliation(s)
- Ankit Garg
- Division of Cardiology, Department of Medicine Johns Hopkins University Baltimore MD USA
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri, USA
- Cardiovascular Division, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Silvia Jansen
- Department of Cell Biology and Physiology, Washington University in St. Louis, St. Louis, MO, United States
| | - Rui Zhang
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Kory J. Lavine
- Cardiovascular Division, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO
| | - Michael J. Greenberg
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri, USA
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4
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Ono S. Segregated localization of two calponin-related proteins within sarcomeric thin filaments in Caenorhabditis elegans striated muscle. Cytoskeleton (Hoboken) 2024; 81:127-140. [PMID: 37792405 PMCID: PMC11249056 DOI: 10.1002/cm.21794] [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: 03/01/2023] [Revised: 09/14/2023] [Accepted: 09/15/2023] [Indexed: 10/05/2023]
Abstract
The calponin family proteins are expressed in both muscle and non-muscle cells and involved in the regulation of cytoskeletal dynamics and cell contractility. In the nematode Caenorhabditis elegans, UNC-87 and CLIK-1 are calponin-related proteins with 42% identical amino acid sequences containing seven calponin-like motifs. Genetic studies demonstrated that UNC-87 and CLIK-1 have partially redundant function in regulating actin cytoskeletal organization in striated and non-striated muscle cells. However, biochemical studies showed that UNC-87 and CLIK-1 are different in their ability to bundle actin filaments. In this study, I extended comparison between UNC-87 and CLIK-1 and found additional differences in vitro and in vivo. Although UNC-87 and CLIK-1 bound to actin filaments similarly, UNC-87, but not CLIK-1, bound to myosin and inhibited actomyosin ATPase in vitro. In striated muscle, UNC-87 and CLIK-1 were segregated into different subregions within sarcomeric actin filaments. CLIK-1 was concentrated near the actin pointed ends, whereas UNC-87 was enriched toward the actin barbed ends. Restricted localization of UNC-87 was not altered in a clik-1-null mutant, suggesting that their segregated localization is not due to competition between the two related proteins. These results suggest that the two calponin-related proteins have both common and distinct roles in regulating actin filaments.
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Affiliation(s)
- Shoichiro Ono
- Departments of Pathology and Cell Biology, Emory University School of Medicine, Atlanta, Georgia 30322, USA
- Winship Cancer Institute, Emory University School of Medicine, Atlanta, Georgia 30322, USA
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5
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Vasilescu C, Colpan M, Ojala TH, Manninen T, Mutka A, Ylänen K, Rahkonen O, Poutanen T, Martelius L, Kumari R, Hinterding H, Brilhante V, Ojanen S, Lappalainen P, Koskenvuo J, Carroll CJ, Fowler VM, Gregorio CC, Suomalainen A. Recessive TMOD1 mutation causes childhood cardiomyopathy. Commun Biol 2024; 7:7. [PMID: 38168645 PMCID: PMC10761686 DOI: 10.1038/s42003-023-05670-9] [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: 04/20/2023] [Accepted: 12/04/2023] [Indexed: 01/05/2024] Open
Abstract
Familial cardiomyopathy in pediatric stages is a poorly understood presentation of heart disease in children that is attributed to pathogenic mutations. Through exome sequencing, we report a homozygous variant in tropomodulin 1 (TMOD1; c.565C>T, p.R189W) in three individuals from two unrelated families with childhood-onset dilated and restrictive cardiomyopathy. To decipher the mechanism of pathogenicity of the R189W mutation in TMOD1, we utilized a wide array of methods, including protein analyses, biochemistry and cultured cardiomyocytes. Structural modeling revealed potential defects in the local folding of TMOD1R189W and its affinity for actin. Cardiomyocytes expressing GFP-TMOD1R189W demonstrated longer thin filaments than GFP-TMOD1wt-expressing cells, resulting in compromised filament length regulation. Furthermore, TMOD1R189W showed weakened activity in capping actin filament pointed ends, providing direct evidence for the variant's effect on actin filament length regulation. Our data indicate that the p.R189W variant in TMOD1 has altered biochemical properties and reveals a unique mechanism for childhood-onset cardiomyopathy.
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Affiliation(s)
- Catalina Vasilescu
- Research Programs Unit, Stem Cells and Metabolism, Biomedicum-Helsinki, University of Helsinki, 00290, Helsinki, Finland
| | - Mert Colpan
- Department of Cellular and Molecular Medicine and Sarver Molecular Cardiovascular Research Program, The University of Arizona, Tucson, AZ, 85724, USA
| | - Tiina H Ojala
- Department of Pediatric Cardiology, Helsinki University Hospital and University of Helsinki, 00290, Helsinki, Finland
| | - Tuula Manninen
- Research Programs Unit, Stem Cells and Metabolism, Biomedicum-Helsinki, University of Helsinki, 00290, Helsinki, Finland
| | - Aino Mutka
- Department of Pathology, Helsinki University Hospital and University of Helsinki, 00290, Helsinki, Finland
| | - Kaisa Ylänen
- Tampere Center for Child, Adolescent and Maternal Health Research, Faculty of Medicine and Health Technology, Tampere University and University Hospital, 33521, Tampere, Finland
| | - Otto Rahkonen
- Department of Pediatric Cardiology, Helsinki University Hospital and University of Helsinki, 00290, Helsinki, Finland
| | - Tuija Poutanen
- Tampere Center for Child, Adolescent and Maternal Health Research, Faculty of Medicine and Health Technology, Tampere University and University Hospital, 33521, Tampere, Finland
| | - Laura Martelius
- Department of Pediatric Radiology, Helsinki University Hospital and University of Helsinki, 00290, Helsinki, Finland
| | - Reena Kumari
- HiLIFE Institute of Biotechnology, University of Helsinki, 00014, Helsinki, Finland
| | - Helena Hinterding
- Research Programs Unit, Stem Cells and Metabolism, Biomedicum-Helsinki, University of Helsinki, 00290, Helsinki, Finland
| | - Virginia Brilhante
- Research Programs Unit, Stem Cells and Metabolism, Biomedicum-Helsinki, University of Helsinki, 00290, Helsinki, Finland
| | - Simo Ojanen
- Research Programs Unit, Stem Cells and Metabolism, Biomedicum-Helsinki, University of Helsinki, 00290, Helsinki, Finland
| | - Pekka Lappalainen
- HiLIFE Institute of Biotechnology, University of Helsinki, 00014, Helsinki, Finland
| | | | - Christopher J Carroll
- Research Programs Unit, Stem Cells and Metabolism, Biomedicum-Helsinki, University of Helsinki, 00290, Helsinki, Finland
- Molecular and Clinical Sciences, St. George's, University of London, London, United Kingdom
| | - Velia M Fowler
- Department of Biological Sciences, University of Delaware, Newark, DE, 19711, USA
| | - Carol C Gregorio
- Department of Cellular and Molecular Medicine and Sarver Molecular Cardiovascular Research Program, The University of Arizona, Tucson, AZ, 85724, USA.
- Cardiovascular Research Institute, Department of Medicine, Icahn School of Medicine, New York, NY, 10029, USA.
| | - Anu Suomalainen
- Research Programs Unit, Stem Cells and Metabolism, Biomedicum-Helsinki, University of Helsinki, 00290, Helsinki, Finland.
- HUSlab, Helsinki University Hospital, University of Helsinki, 00290, Helsinki, Finland.
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6
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Farkas D, Szikora S, Jijumon AS, Polgár TF, Patai R, Tóth MÁ, Bugyi B, Gajdos T, Bíró P, Novák T, Erdélyi M, Mihály J. Peripheral thickening of the sarcomeres and pointed end elongation of the thin filaments are both promoted by SALS and its formin interaction partners. PLoS Genet 2024; 20:e1011117. [PMID: 38198522 PMCID: PMC10805286 DOI: 10.1371/journal.pgen.1011117] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2023] [Revised: 01/23/2024] [Accepted: 12/27/2023] [Indexed: 01/12/2024] Open
Abstract
During striated muscle development the first periodically repeated units appear in the premyofibrils, consisting of immature sarcomeres that must undergo a substantial growth both in length and width, to reach their final size. Here we report that, beyond its well established role in sarcomere elongation, the Sarcomere length short (SALS) protein is involved in Z-disc formation and peripheral growth of the sarcomeres. Our protein localization data and loss-of-function studies in the Drosophila indirect flight muscle strongly suggest that radial growth of the sarcomeres is initiated at the Z-disc. As to thin filament elongation, we used a powerful nanoscopy approach to reveal that SALS is subject to a major conformational change during sarcomere development, which might be critical to stop pointed end elongation in the adult muscles. In addition, we demonstrate that the roles of SALS in sarcomere elongation and radial growth are both dependent on formin type of actin assembly factors. Unexpectedly, when SALS is present in excess amounts, it promotes the formation of actin aggregates highly resembling the ones described in nemaline myopathy patients. Collectively, these findings helped to shed light on the complex mechanisms of SALS during the coordinated elongation and thickening of the sarcomeres, and resulted in the discovery of a potential nemaline myopathy model, suitable for the identification of genetic and small molecule inhibitors.
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Affiliation(s)
- Dávid Farkas
- Institute of Genetics, Biological Research Centre, Szeged, Hungary
| | - Szilárd Szikora
- Institute of Genetics, Biological Research Centre, Szeged, Hungary
| | - A S Jijumon
- Institute of Genetics, Biological Research Centre, Szeged, Hungary
| | - Tamás F Polgár
- Institute of Biophysics, Biological Research Centre, Szeged, Hungary
- Doctoral School of Theoretical Medicine, University of Szeged, Szeged, Hungary
| | - Roland Patai
- Institute of Biophysics, Biological Research Centre, Szeged, Hungary
| | - Mónika Ágnes Tóth
- University of Pécs, Medical School, Department of Biophysics, Pécs, Hungary
| | - Beáta Bugyi
- University of Pécs, Medical School, Department of Biophysics, Pécs, Hungary
| | - Tamás Gajdos
- Department of Optics and Quantum Electronics, University of Szeged, Szeged, Hungary
| | - Péter Bíró
- Department of Optics and Quantum Electronics, University of Szeged, Szeged, Hungary
| | - Tibor Novák
- Department of Optics and Quantum Electronics, University of Szeged, Szeged, Hungary
| | - Miklós Erdélyi
- Department of Optics and Quantum Electronics, University of Szeged, Szeged, Hungary
| | - József Mihály
- Institute of Genetics, Biological Research Centre, Szeged, Hungary
- University of Szeged, Department of Genetics, Szeged, Hungary
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7
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Schultz LE, Colpan M, Smith GE, Mayfield RM, Larrinaga TM, Kostyukova AS, Gregorio CC. A nemaline myopathy-linked mutation inhibits the actin-regulatory functions of tropomodulin and leiomodin. Proc Natl Acad Sci U S A 2023; 120:e2315820120. [PMID: 37956287 PMCID: PMC10665800 DOI: 10.1073/pnas.2315820120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2023] [Accepted: 10/06/2023] [Indexed: 11/15/2023] Open
Abstract
Actin is a highly expressed protein in eukaryotic cells and is essential for numerous cellular processes. In particular, efficient striated muscle contraction is dependent upon the precise regulation of actin-based thin filament structure and function. Alterations in the lengths of actin-thin filaments can lead to the development of myopathies. Leiomodins and tropomodulins are members of an actin-binding protein family that fine-tune thin filament lengths, and their dysfunction is implicated in muscle diseases. An Lmod3 mutation [G326R] was previously identified in patients with nemaline myopathy (NM), a severe skeletal muscle disorder; this residue is conserved among Lmod and Tmod isoforms and resides within their homologous leucine-rich repeat (LRR) domain. We mutated this glycine to arginine in Lmod and Tmod to determine the physiological function of this residue and domain. This G-to-R substitution disrupts Lmod and Tmod's LRR domain structure, altering their binding interface with actin and destroying their abilities to regulate thin filament lengths. Additionally, this mutation renders Lmod3 nonfunctional in vivo. We found that one single amino acid is essential for folding of Lmod and Tmod LRR domains, and thus is essential for the opposing actin-regulatory functions of Lmod (filament elongation) and Tmod (filament shortening), revealing a mechanism underlying the development of NM.
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Affiliation(s)
- Lauren E. Schultz
- Department of Cellular and Molecular Medicine and Sarver Molecular Cardiovascular Research Program, The University of Arizona, Tucson, AZ85724
| | - Mert Colpan
- Department of Cellular and Molecular Medicine and Sarver Molecular Cardiovascular Research Program, The University of Arizona, Tucson, AZ85724
| | - Garry E. Smith
- Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman, WA99164
| | - Rachel M. Mayfield
- Department of Cellular and Molecular Medicine and Sarver Molecular Cardiovascular Research Program, The University of Arizona, Tucson, AZ85724
| | - Tania M. Larrinaga
- Department of Cellular and Molecular Medicine and Sarver Molecular Cardiovascular Research Program, The University of Arizona, Tucson, AZ85724
| | - Alla S. Kostyukova
- Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman, WA99164
| | - Carol C. Gregorio
- Department of Cellular and Molecular Medicine and Sarver Molecular Cardiovascular Research Program, The University of Arizona, Tucson, AZ85724
- Department of Medicine, Cardiovascular Research Institute, Icahn School of Medicine, New York, NY10029
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8
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Endo T. Postnatal skeletal muscle myogenesis governed by signal transduction networks: MAPKs and PI3K-Akt control multiple steps. Biochem Biophys Res Commun 2023; 682:223-243. [PMID: 37826946 DOI: 10.1016/j.bbrc.2023.09.048] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2023] [Revised: 09/06/2023] [Accepted: 09/18/2023] [Indexed: 10/14/2023]
Abstract
Skeletal muscle myogenesis represents one of the most intensively and extensively examined systems of cell differentiation, tissue formation, and regeneration. Muscle regeneration provides an in vivo model system of postnatal myogenesis. It comprises multiple steps including muscle stem cell (or satellite cell) quiescence, activation, migration, myogenic determination, myoblast proliferation, myocyte differentiation, myofiber maturation, and hypertrophy. A variety of extracellular signaling and subsequent intracellular signal transduction pathways or networks govern the individual steps of postnatal myogenesis. Among them, MAPK pathways (the ERK, JNK, p38 MAPK, and ERK5 pathways) and PI3K-Akt signaling regulate multiple steps of myogenesis. Ca2+, cytokine, and Wnt signaling also participate in several myogenesis steps. These signaling pathways often control cell cycle regulatory proteins or the muscle-specific MyoD family and the MEF2 family of transcription factors. This article comprehensively reviews molecular mechanisms of the individual steps of postnatal skeletal muscle myogenesis by focusing on signal transduction pathways or networks. Nevertheless, no or only a partial signaling molecules or pathways have been identified in some responses during myogenesis. The elucidation of these unidentified signaling molecules and pathways leads to an extensive understanding of the molecular mechanisms of myogenesis.
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Affiliation(s)
- Takeshi Endo
- Department of Biology, Graduate School of Science, Chiba University, Yayoicho, Inageku, Chiba, Chiba 263-8522, Japan.
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9
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Lambert MR, Gussoni E. Tropomyosin 3 (TPM3) function in skeletal muscle and in myopathy. Skelet Muscle 2023; 13:18. [PMID: 37936227 PMCID: PMC10629095 DOI: 10.1186/s13395-023-00327-x] [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: 08/11/2023] [Accepted: 10/10/2023] [Indexed: 11/09/2023] Open
Abstract
The tropomyosin genes (TPM1-4) contribute to the functional diversity of skeletal muscle fibers. Since its discovery in 1988, the TPM3 gene has been recognized as an indispensable regulator of muscle contraction in slow muscle fibers. Recent advances suggest that TPM3 isoforms hold more extensive functions during skeletal muscle development and in postnatal muscle. Additionally, mutations in the TPM3 gene have been associated with the features of congenital myopathies. The use of different in vitro and in vivo model systems has leveraged the discovery of several disease mechanisms associated with TPM3-related myopathy. Yet, the precise mechanisms by which TPM3 mutations lead to muscle dysfunction remain unclear. This review consolidates over three decades of research about the role of TPM3 in skeletal muscle. Overall, the progress made has led to a better understanding of the phenotypic spectrum in patients affected by mutations in this gene. The comprehensive body of work generated over these decades has also laid robust groundwork for capturing the multiple functions this protein plays in muscle fibers.
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Affiliation(s)
- Matthias R Lambert
- Division of Genetics and Genomics, Boston Children's Hospital, 300 Longwood Ave., Boston, MA, 02115, USA.
- Department of Pediatrics, Harvard Medical School, Boston, MA, 02115, USA.
| | - Emanuela Gussoni
- Division of Genetics and Genomics, Boston Children's Hospital, 300 Longwood Ave., Boston, MA, 02115, USA
- Department of Pediatrics, Harvard Medical School, Boston, MA, 02115, USA
- The Stem Cell Program, Boston Children's Hospital, Boston, MA, 02115, USA
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10
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Raghavan R, Coppola U, Wu Y, Ihewulezi C, Negrón-Piñeiro LJ, Maguire JE, Hong J, Cunningham M, Kim HJ, Albert TJ, Ali AM, Saint-Jeannet JP, Ristoratore F, Dahia CL, Di Gregorio A. Gene expression in notochord and nuclei pulposi: a study of gene families across the chordate phylum. BMC Ecol Evol 2023; 23:63. [PMID: 37891482 PMCID: PMC10605842 DOI: 10.1186/s12862-023-02167-1] [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: 06/04/2023] [Accepted: 08/08/2023] [Indexed: 10/29/2023] Open
Abstract
The transition from notochord to vertebral column is a crucial milestone in chordate evolution and in prenatal development of all vertebrates. As ossification of the vertebral bodies proceeds, involutions of residual notochord cells into the intervertebral discs form the nuclei pulposi, shock-absorbing structures that confer flexibility to the spine. Numerous studies have outlined the developmental and evolutionary relationship between notochord and nuclei pulposi. However, the knowledge of the similarities and differences in the genetic repertoires of these two structures remains limited, also because comparative studies of notochord and nuclei pulposi across chordates are complicated by the gene/genome duplication events that led to extant vertebrates. Here we show the results of a pilot study aimed at bridging the information on these two structures. We have followed in different vertebrates the evolutionary trajectory of notochord genes identified in the invertebrate chordate Ciona, and we have evaluated the extent of conservation of their expression in notochord cells. Our results have uncovered evolutionarily conserved markers of both notochord development and aging/degeneration of the nuclei pulposi.
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Affiliation(s)
- Rahul Raghavan
- Hospital for Special Surgery, Orthopedic Soft Tissue Research Program, New York, NY, 10021, USA
| | - Ugo Coppola
- Stazione Zoologica 'A. Dohrn', Villa Comunale 1, 80121, Naples, Italy
- Present Address: Molecular Cardiovascular Biology Division and Heart Institute, Cincinnati Children's Research Foundation, Cincinnati, OH, 45229, USA
| | - Yushi Wu
- Department of Molecular Pathobiology, New York University College of Dentistry, New York, NY, 10010, USA
| | - Chibuike Ihewulezi
- Department of Molecular Pathobiology, New York University College of Dentistry, New York, NY, 10010, USA
| | - Lenny J Negrón-Piñeiro
- Department of Molecular Pathobiology, New York University College of Dentistry, New York, NY, 10010, USA
| | - Julie E Maguire
- Department of Molecular Pathobiology, New York University College of Dentistry, New York, NY, 10010, USA
| | - Justin Hong
- Hospital for Special Surgery, Orthopedic Soft Tissue Research Program, New York, NY, 10021, USA
| | - Matthew Cunningham
- Hospital for Special Surgery, New York, NY, 10021, USA
- Weill Cornell Medical College, New York, NY, 10065, USA
| | - Han Jo Kim
- Hospital for Special Surgery, New York, NY, 10021, USA
- Weill Cornell Medical College, New York, NY, 10065, USA
| | - Todd J Albert
- Hospital for Special Surgery, New York, NY, 10021, USA
- Weill Cornell Medical College, New York, NY, 10065, USA
| | - Abdullah M Ali
- Department of Medicine, Columbia University Irving Medical Center, New York, NY, 10032, USA
| | - Jean-Pierre Saint-Jeannet
- Department of Molecular Pathobiology, New York University College of Dentistry, New York, NY, 10010, USA
| | | | - Chitra L Dahia
- Hospital for Special Surgery, Orthopedic Soft Tissue Research Program, New York, NY, 10021, USA.
- Department of Cell and Developmental Biology, Weill Cornell Medicine, Graduate School of Medical Science, New York, NY, 10065, USA.
| | - Anna Di Gregorio
- Department of Molecular Pathobiology, New York University College of Dentistry, New York, NY, 10010, USA.
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11
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Nguyen MT, Dash R, Jeong K, Lee W. Role of Actin-Binding Proteins in Skeletal Myogenesis. Cells 2023; 12:2523. [PMID: 37947600 PMCID: PMC10650911 DOI: 10.3390/cells12212523] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2023] [Revised: 10/22/2023] [Accepted: 10/23/2023] [Indexed: 11/12/2023] Open
Abstract
Maintenance of skeletal muscle quantity and quality is essential to ensure various vital functions of the body. Muscle homeostasis is regulated by multiple cytoskeletal proteins and myogenic transcriptional programs responding to endogenous and exogenous signals influencing cell structure and function. Since actin is an essential component in cytoskeleton dynamics, actin-binding proteins (ABPs) have been recognized as crucial players in skeletal muscle health and diseases. Hence, dysregulation of ABPs leads to muscle atrophy characterized by loss of mass, strength, quality, and capacity for regeneration. This comprehensive review summarizes the recent studies that have unveiled the role of ABPs in actin cytoskeletal dynamics, with a particular focus on skeletal myogenesis and diseases. This provides insight into the molecular mechanisms that regulate skeletal myogenesis via ABPs as well as research avenues to identify potential therapeutic targets. Moreover, this review explores the implications of non-coding RNAs (ncRNAs) targeting ABPs in skeletal myogenesis and disorders based on recent achievements in ncRNA research. The studies presented here will enhance our understanding of the functional significance of ABPs and mechanotransduction-derived myogenic regulatory mechanisms. Furthermore, revealing how ncRNAs regulate ABPs will allow diverse therapeutic approaches for skeletal muscle disorders to be developed.
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Affiliation(s)
- Mai Thi Nguyen
- Department of Biochemistry, Dongguk University College of Medicine, 123 Dongdae-ro, Gyeongju 38066, Republic of Korea; (M.T.N.); (K.J.)
| | - Raju Dash
- Department of Anatomy, Dongguk University College of Medicine, 123 Dongdae-ro, Gyeongju 38066, Republic of Korea;
- Department of New Biology, Daegu Gyeongbuk Institute of Science & Technology (DGIST), Daegu 42988, Republic of Korea
| | - Kyuho Jeong
- Department of Biochemistry, Dongguk University College of Medicine, 123 Dongdae-ro, Gyeongju 38066, Republic of Korea; (M.T.N.); (K.J.)
| | - Wan Lee
- Department of Biochemistry, Dongguk University College of Medicine, 123 Dongdae-ro, Gyeongju 38066, Republic of Korea; (M.T.N.); (K.J.)
- Channelopathy Research Center, Dongguk University College of Medicine, 32 Dongguk-ro, Ilsan Dong-gu, Goyang 10326, Republic of Korea
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12
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Barrie KR, Carman PJ, Dominguez R. Conformation of actin subunits at the barbed and pointed ends of F-actin with and without capping proteins. Cytoskeleton (Hoboken) 2023; 80:309-312. [PMID: 37632366 PMCID: PMC10592188 DOI: 10.1002/cm.21770] [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: 07/17/2023] [Accepted: 07/18/2023] [Indexed: 08/28/2023]
Abstract
Advances in cryo-electron microscopy have made possible the determination of structures of the barbed and pointed ends of F-actin, both in the absence and the presence of capping proteins that block subunit exchange. The conformation of the two exposed protomers at the barbed end resembles the "flat" conformation of protomers in the middle of F-actin. The barbed end changes little upon binding of CapZ, which in turn undergoes a major conformational change. At the pointed end, however, protomers have the "twisted" conformation characteristic of G-actin, whereas tropomodulin binding forces a flat conformation upon the second subunit. The structures provide a mechanistic understanding for the asymmetric addition/dissociation of actin subunits at the ends of F-actin and open the way to future studies of other regulators of filament end dynamics.
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Affiliation(s)
- Kyle R. Barrie
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania; Philadelphia, Pennsylvania, USA
- Biochemistry and Molecular Biophysics Graduate Group, Perelman School of Medicine, University of Pennsylvania; Philadelphia, Pennsylvania, USA
| | - Peter J. Carman
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania; Philadelphia, Pennsylvania, USA
- Biochemistry and Molecular Biophysics Graduate Group, Perelman School of Medicine, University of Pennsylvania; Philadelphia, Pennsylvania, USA
| | - Roberto Dominguez
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania; Philadelphia, Pennsylvania, USA
- Biochemistry and Molecular Biophysics Graduate Group, Perelman School of Medicine, University of Pennsylvania; Philadelphia, Pennsylvania, USA
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13
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Carman PJ, Barrie KR, Rebowski G, Dominguez R. Structures of the free and capped ends of the actin filament. Science 2023; 380:1287-1292. [PMID: 37228182 PMCID: PMC10880383 DOI: 10.1126/science.adg6812] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Accepted: 05/17/2023] [Indexed: 05/27/2023]
Abstract
The barbed and pointed ends of the actin filament (F-actin) are the sites of growth and shrinkage and the targets of capping proteins that block subunit exchange, including CapZ at the barbed end and tropomodulin at the pointed end. We describe cryo-electron microscopy structures of the free and capped ends of F-actin. Terminal subunits at the free barbed end adopt a "flat" F-actin conformation. CapZ binds with minor changes to the barbed end but with major changes to itself. By contrast, subunits at the free pointed end adopt a "twisted" monomeric actin (G-actin) conformation. Tropomodulin binding forces the second subunit into an F-actin conformation. The structures reveal how the ends differ from the middle in F-actin and how these differences control subunit addition, dissociation, capping, and interactions with end-binding proteins.
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Affiliation(s)
- Peter J. Carman
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania; Philadelphia, Pennsylvania, USA
- Biochemistry and Molecular Biophysics Graduate Group, Perelman School of Medicine, University of Pennsylvania; Philadelphia, Pennsylvania, USA
| | - Kyle R. Barrie
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania; Philadelphia, Pennsylvania, USA
- Biochemistry and Molecular Biophysics Graduate Group, Perelman School of Medicine, University of Pennsylvania; Philadelphia, Pennsylvania, USA
| | - Grzegorz Rebowski
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania; Philadelphia, Pennsylvania, USA
| | - Roberto Dominguez
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania; Philadelphia, Pennsylvania, USA
- Biochemistry and Molecular Biophysics Graduate Group, Perelman School of Medicine, University of Pennsylvania; Philadelphia, Pennsylvania, USA
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14
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Sono R, Larrinaga TM, Huang A, Makhlouf F, Kang X, Su J, Lau R, Arboleda VA, Biniwale R, Fishbein GA, Khanlou N, Si MS, Satou GM, Halnon N, Van Arsdell GS, Gregorio CC, Nelson S, Touma M. Whole-Exome Sequencing Identifies Homozygote Nonsense Variants in LMOD2 Gene Causing Infantile Dilated Cardiomyopathy. Cells 2023; 12:1455. [PMID: 37296576 PMCID: PMC10252268 DOI: 10.3390/cells12111455] [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: 12/17/2022] [Revised: 05/07/2023] [Accepted: 05/09/2023] [Indexed: 06/12/2023] Open
Abstract
As an essential component of the sarcomere, actin thin filament stems from the Z-disk extend toward the middle of the sarcomere and overlaps with myosin thick filaments. Elongation of the cardiac thin filament is essential for normal sarcomere maturation and heart function. This process is regulated by the actin-binding proteins Leiomodins (LMODs), among which LMOD2 has recently been identified as a key regulator of thin filament elongation to reach a mature length. Few reports have implicated homozygous loss of function variants of LMOD2 in neonatal dilated cardiomyopathy (DCM) associated with thin filament shortening. We present the fifth case of DCM due to biallelic variants in the LMOD2 gene and the second case with the c.1193G>A (p.W398*) nonsense variant identified by whole-exome sequencing. The proband is a 4-month male infant of Hispanic descent with advanced heart failure. Consistent with previous reports, a myocardial biopsy exhibited remarkably short thin filaments. However, compared to other cases of identical or similar biallelic variants, the patient presented here has an unusually late onset of cardiomyopathy during infancy. Herein, we present the phenotypic and histological features of this variant, confirm the pathogenic impact on protein expression and sarcomere structure, and discuss the current knowledge of LMOD2-related cardiomyopathy.
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Affiliation(s)
- Reiri Sono
- Department of Pathology and Laboratory Medicine, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA
| | - Tania M. Larrinaga
- Department of Cellular and Molecular Medicine and Sarver Molecular Cardiovascular Research Program, The University of Arizona, Tucson, AZ 85721, USA; (T.M.L.); (C.C.G.)
| | - Alden Huang
- Department of Pathology and Laboratory Medicine, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA
| | - Frank Makhlouf
- Neonatal Congenital Heart Laboratory, Department of Pediatrics, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA
| | - Xuedong Kang
- Neonatal Congenital Heart Laboratory, Department of Pediatrics, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA
| | - Jonathan Su
- Department of Pediatrics, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA
| | - Ryan Lau
- Department of Pathology and Laboratory Medicine, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA
| | - Valerie A. Arboleda
- Department of Pathology and Laboratory Medicine, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA
- Department of Human Genetics, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA
- Molecular Biology Institute, University of California, Los Angeles, CA 90095, USA
- Eli and Edyth Broad Stem Cell Research Center, University of California, Los Angeles, CA 90095, USA
| | - Reshma Biniwale
- Department of Pediatrics, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA
- Department of Surgery, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA
| | - Gregory A. Fishbein
- Department of Pathology and Laboratory Medicine, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA
| | - Negar Khanlou
- Department of Pathology and Laboratory Medicine, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA
| | - Ming-Sing Si
- Department of Surgery, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA
| | - Gary M. Satou
- Department of Pediatrics, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA
| | - Nancy Halnon
- Department of Pediatrics, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA
| | | | - Glen S. Van Arsdell
- Department of Pediatrics, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA
- Department of Surgery, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA
| | - Carol C. Gregorio
- Department of Cellular and Molecular Medicine and Sarver Molecular Cardiovascular Research Program, The University of Arizona, Tucson, AZ 85721, USA; (T.M.L.); (C.C.G.)
- Department of Medicine and Cardiovascular Research Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Stanly Nelson
- Department of Pathology and Laboratory Medicine, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA
- Department of Pediatrics, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA
- Department of Human Genetics, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA
| | - Marlin Touma
- Neonatal Congenital Heart Laboratory, Department of Pediatrics, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA
- Department of Pediatrics, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA
- Molecular Biology Institute, University of California, Los Angeles, CA 90095, USA
- Eli and Edyth Broad Stem Cell Research Center, University of California, Los Angeles, CA 90095, USA
- Children’s Discovery and Innovation Institute, University of California, Los Angeles, CA 90095, USA
- Cardiovascular Research Laboratories, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA
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15
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Kuwabara Y, York AJ, Lin SC, Sargent MA, Grimes KM, Pirruccello JP, Molkentin JD. A human FLII gene variant alters sarcomeric actin thin filament length and predisposes to cardiomyopathy. Proc Natl Acad Sci U S A 2023; 120:e2213696120. [PMID: 37126682 PMCID: PMC10175844 DOI: 10.1073/pnas.2213696120] [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: 08/09/2022] [Accepted: 04/07/2023] [Indexed: 05/03/2023] Open
Abstract
To better understand the genetic basis of heart disease, we identified a variant in the Flightless-I homolog (FLII) gene that generates a R1243H missense change and predisposes to cardiac remodeling across multiple previous human genome-wide association studies (GWAS). Since this gene is of unknown function in the mammalian heart we generated gain- and loss-of-function genetically altered mice, as well as knock-in mice with the syntenic R1245H amino acid substitution, which showed that Flii protein binds the sarcomeric actin thin filament and influences its length. Deletion of Flii from the heart, or mice with the R1245H amino acid substitution, show cardiomyopathy due to shortening of the actin thin filaments. Mechanistically, Flii is a known actin binding protein that we show associates with tropomodulin-1 (TMOD1) to regulate sarcomere thin filament length. Indeed, overexpression of leiomodin-2 in the heart, which lengthens the actin-containing thin filaments, partially rescued disease due to heart-specific deletion of Flii. Collectively, the identified FLII human variant likely increases cardiomyopathy risk through an alteration in sarcomere structure and associated contractile dynamics, like other sarcomere gene-based familial cardiomyopathies.
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Affiliation(s)
- Yasuhide Kuwabara
- Department of Pediatrics, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH45229
| | - Allen J. York
- Department of Pediatrics, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH45229
| | - Suh-Chin Lin
- Department of Pediatrics, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH45229
| | - Michelle A. Sargent
- Department of Pediatrics, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH45229
| | - Kelly M. Grimes
- Department of Pediatrics, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH45229
| | - James P. Pirruccello
- Division of Cardiology, University of California San Francisco, San Francisco, CA94158
| | - Jeffery D. Molkentin
- Department of Pediatrics, Cincinnati Children’s Hospital and the University of Cincinnati, Cincinnati, OH45229
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16
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Zapater I Morales C, Carman PJ, Soffar DB, Windner SE, Dominguez R, Baylies MK. Drosophila Tropomodulin is required for multiple actin-dependent processes within developing myofibers. Development 2023; 150:dev201194. [PMID: 36806912 PMCID: PMC10112908 DOI: 10.1242/dev.201194] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Accepted: 02/09/2023] [Indexed: 02/22/2023]
Abstract
Proper muscle contraction requires the assembly and maintenance of sarcomeres and myofibrils. Although the protein components of myofibrils are generally known, less is known about the mechanisms by which they individually function and together synergize for myofibril assembly and maintenance. For example, it is unclear how the disruption of actin filament (F-actin) regulatory proteins leads to the muscle weakness observed in myopathies. Here, we show that knockdown of Drosophila Tropomodulin (Tmod), results in several myopathy-related phenotypes, including reduction of muscle cell (myofiber) size, increased sarcomere length, disorganization and misorientation of myofibrils, ectopic F-actin accumulation, loss of tension-mediating proteins at the myotendinous junction, and misshaped and internalized nuclei. Our findings support and extend the tension-driven self-organizing myofibrillogenesis model. We show that, like its mammalian counterpart, Drosophila Tmod caps F-actin pointed-ends, and we propose that this activity is crucial for cellular processes in different locations within the myofiber that directly and indirectly contribute to the maintenance of muscle function. Our findings provide significant insights to the role of Tmod in muscle development, maintenance and disease.
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Affiliation(s)
- Carolina Zapater I Morales
- Biochemistry, Cell & Developmental Biology, and Molecular Biology (BCMB) program, Weill Cornell Graduate School of Medical Sciences, New York, NY 10065, USA
- Developmental Biology Program, Sloan Kettering Institute, Memorial Sloan Kettering, Cancer Center, New York, NY 10065, USA
| | - Peter J Carman
- Biochemistry and Molecular Biophysics Graduate Group, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - David B Soffar
- Developmental Biology Program, Sloan Kettering Institute, Memorial Sloan Kettering, Cancer Center, New York, NY 10065, USA
| | - Stefanie E Windner
- Developmental Biology Program, Sloan Kettering Institute, Memorial Sloan Kettering, Cancer Center, New York, NY 10065, USA
| | - Roberto Dominguez
- Biochemistry and Molecular Biophysics Graduate Group, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Mary K Baylies
- Biochemistry, Cell & Developmental Biology, and Molecular Biology (BCMB) program, Weill Cornell Graduate School of Medical Sciences, New York, NY 10065, USA
- Developmental Biology Program, Sloan Kettering Institute, Memorial Sloan Kettering, Cancer Center, New York, NY 10065, USA
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17
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Chen B, Wang M, Qiu J, Liao K, Zhang W, Lv Q, Ma C, Qian Z, Shi Z, Liang R, Lin Y, Ye J, Qiu Y, Lin Y. Cleavage of tropomodulin-3 by asparagine endopeptidase promotes cancer malignancy by actin remodeling and SND1/RhoA signaling. J Exp Clin Cancer Res 2022; 41:209. [PMID: 35765111 PMCID: PMC9238189 DOI: 10.1186/s13046-022-02411-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2022] [Accepted: 06/07/2022] [Indexed: 12/12/2022] Open
Abstract
Abstract
Background
Abnormal proliferation and migration of cells are hallmarks of cancer initiation and malignancy. Asparagine endopeptidase (AEP) has specific substrate cleavage ability and plays a pro-cancer role in a variety of cancers. However, the underlying mechanism of AEP in cancer proliferation and migration still remains unclear.
Methods
Co-immunoprecipitation and following mass spectrometry were used to identify the substrate of AEP. Western blotting was applied to measure the expression of proteins. Single cell/nuclear-sequences were done to detect the heterogeneous expression of Tmod3 in tumor tissues. CCK-8 assay, flow cytometry assays, colony formation assay, Transwell assay and scratch wound-healing assay were performed as cellular functional experiments. Mouse intracranial xenograft tumors were studied in in vivo experiments.
Results
Here we showed that AEP cleaved a ubiquitous cytoskeleton regulatory protein, tropomodulin-3 (Tmod3) at asparagine 157 (N157) and produced two functional truncations (tTmod3-N and tTmod3-C). Truncated Tmod3 was detected in diverse tumors and was found to be associated with poor prognosis of high-grade glioma. Functional studies showed that tTmod3-N and tTmod3-C enhanced cancer cell migration and proliferation, respectively. Animal models further revealed the tumor-promoting effects of AEP truncated Tmod3 in vivo. Mechanistically, tTmod3-N was enriched in the cell cortex and competitively inhibited the pointed-end capping effect of wild-type Tmod3 on filamentous actin (F-actin), leading to actin remodeling. tTmod3-C translocated to the nucleus, where it interacted with Staphylococcal Nuclease And Tudor Domain Containing 1 (SND1), facilitating the transcription of Ras Homolog Family Member A/Cyclin Dependent Kinases (RhoA/CDKs).
Conclusion
The newly identified AEP-Tmod3 protease signaling axis is a novel “dual-regulation” mechanism of tumor cell proliferation and migration. Our work provides new clues to the underlying mechanisms of cancer proliferation and invasive progression and evidence for targeting AEP or Tmod3 for therapy.
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18
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Li Y, Wang D, Ge H, Güngör C, Gong X, Chen Y. Cytoskeletal and Cytoskeleton-Associated Proteins: Key Regulators of Cancer Stem Cell Properties. Pharmaceuticals (Basel) 2022; 15:1369. [PMID: 36355541 PMCID: PMC9698833 DOI: 10.3390/ph15111369] [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] [Received: 10/09/2022] [Revised: 11/02/2022] [Accepted: 11/06/2022] [Indexed: 08/08/2023] Open
Abstract
Cancer stem cells (CSCs) are a subpopulation of cancer cells possessing stemness characteristics that are closely associated with tumor proliferation, recurrence and resistance to therapy. Recent studies have shown that different cytoskeletal components and remodeling processes have a profound impact on the behavior of CSCs. In this review, we outline the different cytoskeletal components regulating the properties of CSCs and discuss current and ongoing therapeutic strategies targeting the cytoskeleton. Given the many challenges currently faced in targeted cancer therapy, a deeper comprehension of the molecular events involved in the interaction of the cytoskeleton and CSCs will help us identify more effective therapeutic strategies to eliminate CSCs and ultimately improve patient survival.
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Affiliation(s)
- Yuqiang Li
- Department of General Surgery, Xiangya Hospital, Central South University, Changsha 410008, China
- National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha 410008, China
- NHC Key Laboratory of Cancer Proteomics, Laboratory of Structural Biology, Xiangya Hospital, Central South University, Changsha 410008, China
| | - Dan Wang
- Department of General Surgery, Xiangya Hospital, Central South University, Changsha 410008, China
- National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha 410008, China
- Department of General Visceral and Thoracic Surgery, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
| | - Heming Ge
- Department of General Surgery, Xiangya Hospital, Central South University, Changsha 410008, China
- National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha 410008, China
- Department of General Visceral and Thoracic Surgery, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
| | - Cenap Güngör
- Department of General Visceral and Thoracic Surgery, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
| | - Xuejun Gong
- Department of General Surgery, Xiangya Hospital, Central South University, Changsha 410008, China
- National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha 410008, China
| | - Yongheng Chen
- National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha 410008, China
- NHC Key Laboratory of Cancer Proteomics, Laboratory of Structural Biology, Xiangya Hospital, Central South University, Changsha 410008, China
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19
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Alqassim SS. Functional Mimicry of Eukaryotic Actin Assembly by Pathogen Effector Proteins. Int J Mol Sci 2022; 23:ijms231911606. [PMID: 36232907 PMCID: PMC9569871 DOI: 10.3390/ijms231911606] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Revised: 09/21/2022] [Accepted: 09/22/2022] [Indexed: 11/16/2022] Open
Abstract
The actin cytoskeleton lies at the heart of many essential cellular processes. There are hundreds of proteins that cells use to control the size and shape of actin cytoskeletal networks. As such, various pathogens utilize different strategies to hijack the infected eukaryotic host actin dynamics for their benefit. These include the control of upstream signaling pathways that lead to actin assembly, control of eukaryotic actin assembly factors, encoding toxins that distort regular actin dynamics, or by encoding effectors that directly interact with and assemble actin filaments. The latter class of effectors is unique in that, quite often, they assemble actin in a straightforward manner using novel sequences, folds, and molecular mechanisms. The study of these mechanisms promises to provide major insights into the fundamental determinants of actin assembly, as well as a deeper understanding of host-pathogen interactions in general, and contribute to therapeutic development efforts targeting their respective pathogens. This review discusses mechanisms and highlights shared and unique features of actin assembly by pathogen effectors that directly bind and assemble actin, focusing on eukaryotic actin nucleator functional mimics Rickettsia Sca2 (formin mimic), Burkholderia BimA (Ena/VASP mimic), and Vibrio VopL (tandem WH2-motif mimic).
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Affiliation(s)
- Saif S Alqassim
- College of Medicine, Mohammed Bin Rashid University of Medicine and Health Sciences, Building 14, Dubai Health Care City, Dubai P.O. Box 505055, United Arab Emirates
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20
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Tolkatchev D, Gregorio CC, Kostyukova AS. The role of leiomodin in actin dynamics: a new road or a secret gate. FEBS J 2022; 289:6119-6131. [PMID: 34273242 PMCID: PMC8761783 DOI: 10.1111/febs.16128] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Revised: 05/10/2021] [Accepted: 07/16/2021] [Indexed: 12/29/2022]
Abstract
Leiomodin is an important emerging regulator of thin filaments. As novel molecular, cellular, animal model, and human data accumulate, the mechanisms of its action become clearer. Structural studies played a significant part in understanding the functional significance of leiomodin's interacting partners and functional domains. In this review, we present the current state of knowledge on the structural and cellular properties of leiomodin which has led to two proposed mechanisms of its function. Although it is known that leiomodin is essential for life, numerous domains within leiomodin remain unstudied and as such, we outline future directions for investigations that we predict will provide evidence that leiomodin is a multifunctional protein.
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Affiliation(s)
- Dmitri Tolkatchev
- Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman, WA 99164, USA
| | - Carol C. Gregorio
- Department of Cellular and Molecular Medicine and Sarver Molecular Cardiovascular Research Program, The University of Arizona, Tucson, AZ 85724, USA
| | - Alla S. Kostyukova
- Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman, WA 99164, USA
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21
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Smith GE, Tolkatchev D, Risi C, Little M, Gregorio CC, Galkin VE, Kostyukova AS. Ca 2+ attenuates nucleation activity of leiomodin. Protein Sci 2022; 31:e4358. [PMID: 35762710 PMCID: PMC9207750 DOI: 10.1002/pro.4358] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Revised: 04/25/2022] [Accepted: 05/14/2022] [Indexed: 11/10/2022]
Abstract
A transient increase in Ca2+ concentration in sarcomeres is essential for their proper function. Ca2+ drives striated muscle contraction via binding to the troponin complex of the thin filament to activate its interaction with the myosin thick filament. In addition to the troponin complex, the myosin essential light chain and myosin-binding protein C were also found to be Ca2+ sensitive. However, the effects of Ca2+ on the function of the tropomodulin family proteins involved in regulating thin filament formation have not yet been studied. Leiomodin, a member of the tropomodulin family, is an actin nucleator and thin filament elongator. Using pyrene-actin polymerization assay and transmission electron microscopy, we show that the actin nucleation activity of leiomodin is attenuated by Ca2+ . Using circular dichroism and nuclear magnetic resonance spectroscopy, we demonstrate that the mostly disordered, negatively charged region of leiomodin located between its first two actin-binding sites binds Ca2+ . We propose that Ca2+ binding to leiomodin results in the attenuation of its nucleation activity. Our data provide further evidence regarding the role of Ca2+ as an ultimate regulator of the ensemble of sarcomeric proteins essential for muscle function. SUMMARY STATEMENT: Ca2+ fluctuations in striated muscle sarcomeres modulate contractile activity via binding to several distinct families of sarcomeric proteins. The effects of Ca2+ on the activity of leiomodin-an actin nucleator and thin filament length regulator-have remained unknown. In this study, we demonstrate that Ca2+ binds directly to leiomodin and attenuates its actin nucleating activity. Our data emphasizes the ultimate role of Ca2+ in the regulation of the sarcomeric protein interactions.
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Affiliation(s)
- Garry E. Smith
- Voiland School of Chemical Engineering and BioengineeringWashington State UniversityPullmanWashingtonUSA
| | - Dmitri Tolkatchev
- Voiland School of Chemical Engineering and BioengineeringWashington State UniversityPullmanWashingtonUSA
| | - Cristina Risi
- Department of Physiological SciencesEastern Virginia Medical SchoolNorfolkVirginiaUSA
| | - Madison Little
- Voiland School of Chemical Engineering and BioengineeringWashington State UniversityPullmanWashingtonUSA
| | - Carol C. Gregorio
- Department of Cellular and Molecular Medicine and Sarver Molecular Cardiovascular Research ProgramUniversity of ArizonaTucsonArizonaUSA
| | - Vitold E. Galkin
- Department of Physiological SciencesEastern Virginia Medical SchoolNorfolkVirginiaUSA
| | - Alla S. Kostyukova
- Voiland School of Chemical Engineering and BioengineeringWashington State UniversityPullmanWashingtonUSA
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22
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Mob4-dependent STRIPAK involves the chaperonin TRiC to coordinate myofibril and microtubule network growth. PLoS Genet 2022; 18:e1010287. [PMID: 35737712 PMCID: PMC9258817 DOI: 10.1371/journal.pgen.1010287] [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: 02/02/2022] [Revised: 07/06/2022] [Accepted: 06/08/2022] [Indexed: 11/19/2022] Open
Abstract
Myofibrils of the skeletal muscle are comprised of sarcomeres that generate force by contraction when myosin-rich thick filaments slide past actin-based thin filaments. Surprisingly little is known about the molecular processes that guide sarcomere assembly in vivo, despite deficits within this process being a major cause of human disease. To overcome this knowledge gap, we undertook a forward genetic screen coupled with reverse genetics to identify genes required for vertebrate sarcomere assembly. In this screen, we identified a zebrafish mutant with a nonsense mutation in mob4. In Drosophila, mob4 has been reported to play a role in spindle focusing as well as neurite branching and in planarians mob4 was implemented in body size regulation. In contrast, zebrafish mob4geh mutants are characterised by an impaired actin biogenesis resulting in sarcomere defects. Whereas loss of mob4 leads to a reduction in the amount of myofibril, transgenic expression of mob4 triggers an increase. Further genetic analysis revealed the interaction of Mob4 with the actin-folding chaperonin TRiC, suggesting that Mob4 impacts on TRiC to control actin biogenesis and thus myofibril growth. Additionally, mob4geh features a defective microtubule network, which is in-line with tubulin being the second main folding substrate of TRiC. We also detected similar characteristics for strn3-deficient mutants, which confirmed Mob4 as a core component of STRIPAK and surprisingly implicates a role of the STRIPAK complex in sarcomerogenesis.
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23
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Zhou R, Han B, Nowak R, Lu Y, Heller E, Xia C, Chishti AH, Fowler VM, Zhuang X. Proteomic and functional analyses of the periodic membrane skeleton in neurons. Nat Commun 2022; 13:3196. [PMID: 35680881 PMCID: PMC9184744 DOI: 10.1038/s41467-022-30720-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Accepted: 05/09/2022] [Indexed: 12/29/2022] Open
Abstract
Actin, spectrin, and associated molecules form a membrane-associated periodic skeleton (MPS) in neurons. The molecular composition and functions of the MPS remain incompletely understood. Here, using co-immunoprecipitation and mass spectrometry, we identified hundreds of potential candidate MPS-interacting proteins that span diverse functional categories. We examined representative proteins in several of these categories using super-resolution imaging, including previously unknown MPS structural components, as well as motor proteins, cell adhesion molecules, ion channels, and signaling proteins, and observed periodic distributions characteristic of the MPS along the neurites for ~20 proteins. Genetic perturbations of the MPS and its interacting proteins further suggested functional roles of the MPS in axon-axon and axon-dendrite interactions and in axon diameter regulation, and implicated the involvement of MPS interactions with cell adhesion molecules and non-muscle myosin in these roles. These results provide insights into the interactome of the MPS and suggest previously unknown functions of the MPS in neurons.
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Affiliation(s)
- Ruobo Zhou
- Howard Hughes Medical Institute, Harvard University, Cambridge, MA, 02138, USA.
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, 02138, USA.
- Department of Physics, Harvard University, Cambridge, MA, 02138, USA.
- Department of Chemistry, The Pennsylvania State University, University Park, PA, 16802, USA.
| | - Boran Han
- Howard Hughes Medical Institute, Harvard University, Cambridge, MA, 02138, USA
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, 02138, USA
- Department of Physics, Harvard University, Cambridge, MA, 02138, USA
| | - Roberta Nowak
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA, 92307, USA
| | - Yunzhe Lu
- Department of Developmental, Molecular, and Chemical Biology, Tufts University School of Medicine, Boston, MA, 02111, USA
| | - Evan Heller
- Howard Hughes Medical Institute, Harvard University, Cambridge, MA, 02138, USA
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, 02138, USA
- Department of Physics, Harvard University, Cambridge, MA, 02138, USA
| | - Chenglong Xia
- Howard Hughes Medical Institute, Harvard University, Cambridge, MA, 02138, USA
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, 02138, USA
- Department of Physics, Harvard University, Cambridge, MA, 02138, USA
| | - Athar H Chishti
- Department of Developmental, Molecular, and Chemical Biology, Tufts University School of Medicine, Boston, MA, 02111, USA
| | - Velia M Fowler
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA, 92307, USA
- Department of Biological Sciences, The University of Delaware, Newark, DE, 19716, USA
| | - Xiaowei Zhuang
- Howard Hughes Medical Institute, Harvard University, Cambridge, MA, 02138, USA.
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, 02138, USA.
- Department of Physics, Harvard University, Cambridge, MA, 02138, USA.
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24
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Szikora S, Görög P, Mihály J. The Mechanisms of Thin Filament Assembly and Length Regulation in Muscles. Int J Mol Sci 2022; 23:5306. [PMID: 35628117 PMCID: PMC9140763 DOI: 10.3390/ijms23105306] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Revised: 05/05/2022] [Accepted: 05/06/2022] [Indexed: 02/01/2023] Open
Abstract
The actin containing tropomyosin and troponin decorated thin filaments form one of the crucial components of the contractile apparatus in muscles. The thin filaments are organized into densely packed lattices interdigitated with myosin-based thick filaments. The crossbridge interactions between these myofilaments drive muscle contraction, and the degree of myofilament overlap is a key factor of contractile force determination. As such, the optimal length of the thin filaments is critical for efficient activity, therefore, this parameter is precisely controlled according to the workload of a given muscle. Thin filament length is thought to be regulated by two major, but only partially understood mechanisms: it is set by (i) factors that mediate the assembly of filaments from monomers and catalyze their elongation, and (ii) by factors that specify their length and uniformity. Mutations affecting these factors can alter the length of thin filaments, and in human cases, many of them are linked to debilitating diseases such as nemaline myopathy and dilated cardiomyopathy.
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Affiliation(s)
- Szilárd Szikora
- Institute of Genetics, Biological Research Centre, H-6726 Szeged, Hungary;
| | - Péter Görög
- Institute of Genetics, Biological Research Centre, H-6726 Szeged, Hungary;
- Doctoral School of Multidisciplinary Medical Science, Faculty of Medicine, University of Szeged, H-6725 Szeged, Hungary
| | - József Mihály
- Institute of Genetics, Biological Research Centre, H-6726 Szeged, Hungary;
- Department of Genetics, University of Szeged, H-6726 Szeged, Hungary
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25
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Ono S, Lewis M, Ono K. Mutual dependence between tropomodulin and tropomyosin in the regulation of sarcomeric actin assembly in Caenorhabditis elegans striated muscle. Eur J Cell Biol 2022; 101:151215. [PMID: 35306452 PMCID: PMC9081161 DOI: 10.1016/j.ejcb.2022.151215] [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: 12/07/2021] [Revised: 02/24/2022] [Accepted: 03/14/2022] [Indexed: 11/25/2022] Open
Abstract
Tropomodulin and tropomyosin are important components of sarcomeric thin filaments in striated muscles. Tropomyosin decorates the side of actin filaments and enhances tropomodulin capping at the pointed ends of the filaments. Their functional relationship has been extensively characterized in vitro, but in vivo and cellular studies in mammals are often complicated by the presence of functionally redundant isoforms. Here, we used the nematode Caenorhabditis elegans, which has a relatively simple composition of tropomodulin and tropomyosin genes, and demonstrated that tropomodulin (unc-94) and tropomyosin (lev-11) are mutually dependent on each other in their sarcomere localization and regulation of sarcomeric actin assembly. Mutation of tropomodulin caused sarcomere disorganization with formation of actin aggregates. However, the actin aggregation was suppressed when tropomyosin was depleted in the tropomodulin mutant. Tropomyosin was mislocalized to the actin aggregates in the tropomodulin mutants, while sarcomere localization of tropomodulin was lost when tropomyosin was depleted. These results indicate that tropomodulin and tropomyosin are interdependent in the regulation of organized sarcomeric assembly of actin filaments in vivo.
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Affiliation(s)
- Shoichiro Ono
- Departments of Pathology and Cell Biology, Emory University School of Medicine, Atlanta, GA, USA; Winship Cancer Institute, Emory University School of Medicine, Atlanta, GA, USA.
| | - Mario Lewis
- Departments of Pathology and Cell Biology, Emory University School of Medicine, Atlanta, GA, USA; Winship Cancer Institute, Emory University School of Medicine, Atlanta, GA, USA
| | - Kanako Ono
- Departments of Pathology and Cell Biology, Emory University School of Medicine, Atlanta, GA, USA; Winship Cancer Institute, Emory University School of Medicine, Atlanta, GA, USA
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26
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Liu K, Lu L, Chen S, Gu B, Cai H, Wang Y, Cai W. Loss-of-function variants within LMOD1 actin-binding site 2 cause pediatric intestinal pseudo-obstruction by impairing protein stability and actin nucleation. FASEB J 2022; 36:e22194. [PMID: 35170814 DOI: 10.1096/fj.202101395r] [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: 09/02/2021] [Revised: 01/12/2022] [Accepted: 01/21/2022] [Indexed: 11/11/2022]
Abstract
The leiomodin1 (LMOD1) gene, encoding a potent actin nucleator, was recently reported as a potential pathogenic gene of megacystis-microcolon-intestinal hypoperistalsis syndrome (MMIHS, OMIM 619362). However, only a single patient has been reported to have LMOD1 mutations, and the underlying pathogenic mechanism remains unknown. Here, we described a male infant with LMOD1 mutations presenting typical symptoms of pediatric intestinal pseudo-obstruction (PIPO) but without megacystis and microcolon. Two compound heterozygous missense variants (c.1106C>T, p.T369M; c.1262G>A, p.R421H) were identified, both affecting highly conserved amino acid residues within the second actin-binding site (ABS2) domain of LMOD1. Expression analysis showed that both variants resulted in significantly reduced protein amounts, especially for p.T369M, which was almost undetectable. The reduction was only partially rescued by the proteasome inhibitor MG-132, indicating that there might be proteasome-independent pathways involved in the degradation of the mutant proteins. Molecular modeling showed that variant p.T369M impaired the local protein conformation of the ABS2 domain, while variant p.R421H directly impaired the intermolecular interaction between ABS2 and actin. Accordingly, both variants significantly damaged LMOD1-mediated actin nucleation. These findings provide further human genetic evidence supporting LMOD1 as a pathogenic gene underlying visceral myopathy including PIPO and MMIHS, strengthen the critical role of ABS2 domain in LMOD1-mediated actin nucleation, and moreover, reveal an unrecognized role of ABS2 in protein stability.
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Affiliation(s)
- Keqiang Liu
- Division of Pediatric Gastroenterology and Nutrition, Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.,Shanghai Institute for Pediatric Research, Shanghai, China.,Shanghai Key Laboratory of Pediatric Gastroenterology and Nutrition, Shanghai, China
| | - Lina Lu
- Division of Pediatric Gastroenterology and Nutrition, Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Shanshan Chen
- Division of Pediatric Gastroenterology and Nutrition, Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Beilin Gu
- Shanghai Institute for Pediatric Research, Shanghai, China
| | - Hui Cai
- Division of Pediatric Gastroenterology and Nutrition, Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Ying Wang
- Division of Pediatric Gastroenterology and Nutrition, Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.,Shanghai Key Laboratory of Pediatric Gastroenterology and Nutrition, Shanghai, China
| | - Wei Cai
- Division of Pediatric Gastroenterology and Nutrition, Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.,Shanghai Institute for Pediatric Research, Shanghai, China.,Shanghai Key Laboratory of Pediatric Gastroenterology and Nutrition, Shanghai, China.,Department of Pediatric Surgery, Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
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27
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Berger J, Berger S, Mok YSG, Li M, Tarakci H, Currie PD. Genetic dissection of novel myopathy models reveals a role of CapZα and Leiomodin 3 during myofibril elongation. PLoS Genet 2022; 18:e1010066. [PMID: 35148320 PMCID: PMC8870547 DOI: 10.1371/journal.pgen.1010066] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2021] [Revised: 02/24/2022] [Accepted: 02/01/2022] [Indexed: 12/18/2022] Open
Abstract
Myofibrils within skeletal muscle are composed of sarcomeres that generate force by contraction when their myosin-rich thick filaments slide past actin-based thin filaments. Although mutations in components of the sarcomere are a major cause of human disease, the highly complex process of sarcomere assembly is not fully understood. Current models of thin filament assembly highlight a central role for filament capping proteins, which can be divided into three protein families, each ascribed with separate roles in thin filament assembly. CapZ proteins have been shown to bind the Z-disc protein α-actinin to form an anchoring complex for thin filaments and actin polymerisation. Subsequent thin filaments extension dynamics are thought to be facilitated by Leiomodins (Lmods) and thin filament assembly is concluded by Tropomodulins (Tmods) that specifically cap the pointed end of thin filaments. To study thin filament assembly in vivo, single and compound loss-of-function zebrafish mutants within distinct classes of capping proteins were analysed. The generated lmod3- and capza1b-deficient zebrafish exhibited aspects of the pathology caused by variations in their human orthologs. Although loss of the analysed main capping proteins of the skeletal muscle, capza1b, capza1a, lmod3 and tmod4, resulted in sarcomere defects, residual organised sarcomeres were formed within the assessed mutants, indicating that these proteins are not essential for the initial myofibril assembly. Furthermore, detected similarity and location of myofibril defects, apparent at the peripheral ends of myofibres of both Lmod3- and CapZα-deficient mutants, suggest a function in longitudinal myofibril growth for both proteins, which is molecularly distinct to the function of Tmod4. The force-generating contractile apparatus is a highly organised structure mainly composed of thick and thin filaments of uniform length. Three families of capping proteins are described to play a role in the regulation of thin filament length. Current models suggest that thin filament assembly is initiated by CapZ, extended by Leiomodins (Lmods) and concluded by Tropomodulins (Tmods). To better understand the role of these capping proteins, we analysed single and double loss-of-function zebrafish mutants for these capping proteins. We find that lmod3- and capza1b-deficient zebrafish model aspects of the human disorders caused by variations in their orthologs. Surprisingly, although pivotal for sarcomere formation, our results reveal that none of the analysed capping proteins, capza1b, capza1a, lmod3 and tmod4, are absolutely required for thin filament assembly, as suggested by current models. Our study further indicates that the roles of CapZ and Lmod3 are distinct from Tmod4. Both Lmod3- as well as CapZα-deficient mutants feature specific defects at the peripheral ends of muscle cells. We conclude that, in addition to their non-essential role during thin filament assembly, both Lmod3- and CapZα proteins may function in the longitudinal growth of the contractile apparatus.
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Affiliation(s)
- Joachim Berger
- Australian Regenerative Medicine Institute, Monash University, Clayton, Australia
- Victoria Node, EMBL Australia, Clayton, Australia
- * E-mail: (JB); (PDC)
| | - Silke Berger
- Australian Regenerative Medicine Institute, Monash University, Clayton, Australia
- Victoria Node, EMBL Australia, Clayton, Australia
| | - Yu Shan G. Mok
- Australian Regenerative Medicine Institute, Monash University, Clayton, Australia
- Victoria Node, EMBL Australia, Clayton, Australia
| | - Mei Li
- Australian Regenerative Medicine Institute, Monash University, Clayton, Australia
- Victoria Node, EMBL Australia, Clayton, Australia
| | - Hakan Tarakci
- Australian Regenerative Medicine Institute, Monash University, Clayton, Australia
- Victoria Node, EMBL Australia, Clayton, Australia
| | - Peter D. Currie
- Australian Regenerative Medicine Institute, Monash University, Clayton, Australia
- Victoria Node, EMBL Australia, Clayton, Australia
- * E-mail: (JB); (PDC)
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28
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Rust MB, Marcello E. Disease association of cyclase-associated protein (CAP): Lessons from gene-targeted mice and human genetic studies. Eur J Cell Biol 2022; 101:151207. [PMID: 35150966 DOI: 10.1016/j.ejcb.2022.151207] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Revised: 02/04/2022] [Accepted: 02/07/2022] [Indexed: 11/03/2022] Open
Abstract
Cyclase-associated protein (CAP) is an actin binding protein that has been initially described as partner of the adenylyl cyclase in yeast. In all vertebrates and some invertebrate species, two orthologs, named CAP1 and CAP2, have been described. CAP1 and CAP2 are characterized by a similar multidomain structure, but different expression patterns. Several molecular studies clarified the biological function of the different CAP domains, and they shed light onto the mechanisms underlying CAP-dependent regulation of actin treadmilling. However, CAPs are crucial elements not only for the regulation of actin dynamics, but also for signal transduction pathways. During recent years, human genetic studies and the analysis of gene-targeted mice provided important novel insights into the physiological roles of CAPs and their involvement in the pathogenesis of several diseases. In the present review, we summarize and discuss recent progress in our understanding of CAPs' physiological functions, focusing on heart, skeletal muscle and central nervous system as well as their involvement in the mechanisms controlling metabolism. Remarkably, loss of CAPs or impairment of CAPs-dependent pathways can contribute to the pathogenesis of different diseases. Overall, these studies unraveled CAPs complexity highlighting their capability to orchestrate structural and signaling pathways in the cells.
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Affiliation(s)
- Marco B Rust
- Molecular Neurobiology Group, Institute of Physiological Chemistry, Philipps-University of Marburg, 35032 Marburg, Germany; Center for Mind, Brain and Behavior (CMBB), University of Marburg and Justus-Liebig-University Giessen, 35032 Marburg, Germany; DFG Research Training Group 'Membrane Plasticity in Tissue Development and Remodeling', GRK 2213, Philipps-University of Marburg, 35032 Marburg, Germany.
| | - Elena Marcello
- Department of Pharmacological and Biomolecular Sciences, Università degli Studi di Milano, 20133 Milan, Italy.
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29
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Iwanski J, Gregorio CC, Colpan M. Redefining actin dynamics of the pointed-end complex in striated muscle. Trends Cell Biol 2021; 31:708-711. [PMID: 34266732 DOI: 10.1016/j.tcb.2021.06.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Revised: 06/14/2021] [Accepted: 06/16/2021] [Indexed: 11/15/2022]
Abstract
Striated muscle is intricately designed to provide efficient and powerful muscle contractions. Recently, a long sought-after missing component of the thin filament pointed-end machinery was discovered: cyclase-associated protein 2 (CAP2). CAP2 was identified as a crucial contributor to actin polymerization, striated muscle development, and severe muscle disease when mutated.
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Affiliation(s)
- Jessika Iwanski
- Department of Cellular and Molecular Medicine, and Sarver Molecular Cardiovascular Research Program, The University of Arizona, Tucson, AZ 85724, USA
| | - Carol C Gregorio
- Department of Cellular and Molecular Medicine, and Sarver Molecular Cardiovascular Research Program, The University of Arizona, Tucson, AZ 85724, USA.
| | - Mert Colpan
- Department of Cellular and Molecular Medicine, and Sarver Molecular Cardiovascular Research Program, The University of Arizona, Tucson, AZ 85724, USA
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30
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Abstract
Arit Ghosh and Velia Fowler introduce the structural features and functions of tropomodulins - actin-binding proteins that cap the slow-growing (pointed) ends of actin filaments.
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Affiliation(s)
- Arit Ghosh
- Department of Biological Sciences, University of Delaware, 105 The Grn, 118 Wolf Hall, Newark, DE 19716, USA
| | - Velia M Fowler
- Department of Biological Sciences, University of Delaware, 105 The Grn, 118 Wolf Hall, Newark, DE 19716, USA.
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31
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Colpan M, Iwanski J, Gregorio CC. CAP2 is a regulator of actin pointed end dynamics and myofibrillogenesis in cardiac muscle. Commun Biol 2021; 4:365. [PMID: 33742108 PMCID: PMC7979805 DOI: 10.1038/s42003-021-01893-w] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2020] [Accepted: 02/22/2021] [Indexed: 01/31/2023] Open
Abstract
The precise assembly of actin-based thin filaments is crucial for muscle contraction. Dysregulation of actin dynamics at thin filament pointed ends results in skeletal and cardiac myopathies. Here, we discovered adenylyl cyclase-associated protein 2 (CAP2) as a unique component of thin filament pointed ends in cardiac muscle. CAP2 has critical functions in cardiomyocytes as it depolymerizes and inhibits actin incorporation into thin filaments. Strikingly distinct from other pointed-end proteins, CAP2's function is not enhanced but inhibited by tropomyosin and it does not directly control thin filament lengths. Furthermore, CAP2 plays an essential role in cardiomyocyte maturation by modulating pre-sarcomeric actin assembly and regulating α-actin composition in mature thin filaments. Identification of CAP2's multifunctional roles provides missing links in our understanding of how thin filament architecture is regulated in striated muscle and it reveals there are additional factors, beyond Tmod1 and Lmod2, that modulate actin dynamics at thin filament pointed ends.
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Affiliation(s)
- Mert Colpan
- Department of Cellular and Molecular Medicine and Sarver Molecular Cardiovascular Research Program, The University of Arizona, Tucson, AZ, USA
| | - Jessika Iwanski
- Department of Cellular and Molecular Medicine and Sarver Molecular Cardiovascular Research Program, The University of Arizona, Tucson, AZ, USA
| | - Carol C Gregorio
- Department of Cellular and Molecular Medicine and Sarver Molecular Cardiovascular Research Program, The University of Arizona, Tucson, AZ, USA.
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32
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Solís C, Solaro RJ. Novel insights into sarcomere regulatory systems control of cardiac thin filament activation. J Gen Physiol 2021; 153:211903. [PMID: 33740037 PMCID: PMC7988513 DOI: 10.1085/jgp.202012777] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Accepted: 02/23/2021] [Indexed: 12/11/2022] Open
Abstract
Our review focuses on sarcomere regulatory mechanisms with a discussion of cardiac-specific modifications to the three-state model of thin filament activation from a blocked to closed to open state. We discuss modulation of these thin filament transitions by Ca2+, by crossbridge interactions, and by thick filament–associated proteins, cardiac myosin–binding protein C (cMyBP-C), cardiac regulatory light chain (cRLC), and titin. Emerging evidence supports the idea that the cooperative activation of the thin filaments despite a single Ca2+ triggering regulatory site on troponin C (cTnC) cannot be considered in isolation of other functional domains of the sarcomere. We discuss long- and short-range interactions among these domains with the regulatory units of thin filaments, including proteins at the barbed end at the Z-disc and the pointed end near the M-band. Important to these discussions is the ever-increasing understanding of the role of cMyBP-C, cRLC, and titin filaments. Detailed knowledge of these control processes is critical to the understanding of mechanisms sustaining physiological cardiac state with varying hemodynamic load, to better defining genetic and acquired cardiac disorders, and to developing targets for therapies at the level of the sarcomeres.
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Affiliation(s)
- Christopher Solís
- University of Illinois at Chicago, College of Medicine, Department of Physiology and Biophysics and Center for Cardiovascular Research, Chicago, IL
| | - R John Solaro
- University of Illinois at Chicago, College of Medicine, Department of Physiology and Biophysics and Center for Cardiovascular Research, Chicago, IL
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33
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Role of Actin Cytoskeleton in E-cadherin-Based Cell–Cell Adhesion Assembly and Maintenance. J Indian Inst Sci 2021. [DOI: 10.1007/s41745-020-00214-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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34
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Abstract
Simple Summary Cell migration is an essential process from embryogenesis to cell death. This is tightly regulated by numerous proteins that help in proper functioning of the cell. In diseases like cancer, this process is deregulated and helps in the dissemination of tumor cells from the primary site to secondary sites initiating the process of metastasis. For metastasis to be efficient, cytoskeletal components like actin, myosin, and intermediate filaments and their associated proteins should co-ordinate in an orderly fashion leading to the formation of many cellular protrusions-like lamellipodia and filopodia and invadopodia. Knowledge of this process is the key to control metastasis of cancer cells that leads to death in 90% of the patients. The focus of this review is giving an overall understanding of these process, concentrating on the changes in protein association and regulation and how the tumor cells use it to their advantage. Since the expression of cytoskeletal proteins can be directly related to the degree of malignancy, knowledge about these proteins will provide powerful tools to improve both cancer prognosis and treatment. Abstract Successful metastasis depends on cell invasion, migration, host immune escape, extravasation, and angiogenesis. The process of cell invasion and migration relies on the dynamic changes taking place in the cytoskeletal components; actin, tubulin and intermediate filaments. This is possible due to the plasticity of the cytoskeleton and coordinated action of all the three, is crucial for the process of metastasis from the primary site. Changes in cellular architecture by internal clues will affect the cell functions leading to the formation of different protrusions like lamellipodia, filopodia, and invadopodia that help in cell migration eventually leading to metastasis, which is life threatening than the formation of neoplasms. Understanding the signaling mechanisms involved, will give a better insight of the changes during metastasis, which will eventually help targeting proteins for treatment resulting in reduced mortality and longer survival.
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Kiss B, Gohlke J, Tonino P, Hourani Z, Kolb J, Strom J, Alekhina O, Smith JE, Ottenheijm C, Gregorio C, Granzier H. Nebulin and Lmod2 are critical for specifying thin-filament length in skeletal muscle. SCIENCE ADVANCES 2020; 6:6/46/eabc1992. [PMID: 33177085 PMCID: PMC7673738 DOI: 10.1126/sciadv.abc1992] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2020] [Accepted: 09/23/2020] [Indexed: 06/07/2023]
Abstract
Regulating the thin-filament length in muscle is crucial for controlling the number of myosin motors that generate power. The giant protein nebulin forms a long slender filament that associates along the length of the thin filament in skeletal muscle with functions that remain largely obscure. Here nebulin's role in thin-filament length regulation was investigated by targeting entire super-repeats in the Neb gene; nebulin was either shortened or lengthened by 115 nm. Its effect on thin-filament length was studied using high-resolution structural and functional techniques. Results revealed that thin-filament length is strictly regulated by the length of nebulin in fast muscles. Nebulin's control is less tight in slow muscle types where a distal nebulin-free thin-filament segment exists, the length of which was found to be regulated by leiomodin-2 (Lmod2). We propose that strict length control by nebulin promotes high-speed shortening and that dual-regulation by nebulin/Lmod2 enhances contraction efficiency.
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Affiliation(s)
- Balázs Kiss
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ 85721, USA
| | - Jochen Gohlke
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ 85721, USA
| | - Paola Tonino
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ 85721, USA
| | - Zaynab Hourani
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ 85721, USA
| | - Justin Kolb
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ 85721, USA
| | - Joshua Strom
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ 85721, USA
| | - Olga Alekhina
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ 85721, USA
| | - John E Smith
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ 85721, USA
| | - Coen Ottenheijm
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ 85721, USA
| | - Carol Gregorio
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ 85721, USA
| | - Henk Granzier
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ 85721, USA.
- Allan and Alfie Endowed Chair for Heart Disease in Women Research, Sarver Molecular Cardiovascular Research Program, University of Arizona, Tucson, AZ 85721, USA
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36
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Tolkatchev D, Smith GE, Schultz LE, Colpan M, Helms GL, Cort JR, Gregorio CC, Kostyukova AS. Leiomodin creates a leaky cap at the pointed end of actin-thin filaments. PLoS Biol 2020; 18:e3000848. [PMID: 32898131 PMCID: PMC7500696 DOI: 10.1371/journal.pbio.3000848] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2020] [Revised: 09/18/2020] [Accepted: 08/17/2020] [Indexed: 01/26/2023] Open
Abstract
Improper lengths of actin-thin filaments are associated with altered contractile activity and lethal myopathies. Leiomodin, a member of the tropomodulin family of proteins, is critical in thin filament assembly and maintenance; however, its role is under dispute. Using nuclear magnetic resonance data and molecular dynamics simulations, we generated the first atomic structural model of the binding interface between the tropomyosin-binding site of cardiac leiomodin and the N-terminus of striated muscle tropomyosin. Our structural data indicate that the leiomodin/tropomyosin complex only forms at the pointed end of thin filaments, where the tropomyosin N-terminus is not blocked by an adjacent tropomyosin protomer. This discovery provides evidence supporting the debated mechanism where leiomodin and tropomodulin regulate thin filament lengths by competing for thin filament binding. Data from experiments performed in cardiomyocytes provide additional support for the competition model; specifically, expression of a leiomodin mutant that is unable to interact with tropomyosin fails to displace tropomodulin at thin filament pointed ends and fails to elongate thin filaments. Together with previous structural and biochemical data, we now propose a molecular mechanism of actin polymerization at the pointed end in the presence of bound leiomodin. In the proposed model, the N-terminal actin-binding site of leiomodin can act as a "swinging gate" allowing limited actin polymerization, thus making leiomodin a leaky pointed-end cap. Results presented in this work answer long-standing questions about the role of leiomodin in thin filament length regulation and maintenance.
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Affiliation(s)
- Dmitri Tolkatchev
- Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman, Washington, United States of America
| | - Garry E. Smith
- Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman, Washington, United States of America
| | - Lauren E. Schultz
- Department of Cellular and Molecular Medicine and Sarver Molecular Cardiovascular Research Program, The University of Arizona, Tucson, Arizona, United States of America
| | - Mert Colpan
- Department of Cellular and Molecular Medicine and Sarver Molecular Cardiovascular Research Program, The University of Arizona, Tucson, Arizona, United States of America
| | - Gregory L. Helms
- The Center for NMR Spectroscopy, Washington State University, Pullman, Washington, United States of America
| | - John R. Cort
- Earth and Biological Sciences Directorate, Pacific Northwest National Laboratory, Richland, Washington, United States of America
- Institute of Biological Chemistry, Washington State University, Pullman, Washington, United States of America
| | - Carol C. Gregorio
- Department of Cellular and Molecular Medicine and Sarver Molecular Cardiovascular Research Program, The University of Arizona, Tucson, Arizona, United States of America
| | - Alla S. Kostyukova
- Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman, Washington, United States of America
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37
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Triggering typical nemaline myopathy with compound heterozygous nebulin mutations reveals myofilament structural changes as pathomechanism. Nat Commun 2020; 11:2699. [PMID: 32483185 PMCID: PMC7264197 DOI: 10.1038/s41467-020-16526-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Accepted: 05/06/2020] [Indexed: 12/26/2022] Open
Abstract
Nebulin is a giant protein that winds around the actin filaments in the skeletal muscle sarcomere. Compound-heterozygous mutations in the nebulin gene (NEB) cause typical nemaline myopathy (NM), a muscle disorder characterized by muscle weakness with limited treatment options. We created a mouse model with a missense mutation p.Ser6366Ile and a deletion of NEB exon 55, the Compound-Het model that resembles typical NM. We show that Compound-Het mice are growth-retarded and have muscle weakness. Muscles have a reduced myofibrillar fractional-area and sarcomeres are disorganized, contain rod bodies, and have longer thin filaments. In contrast to nebulin-based severe NM where haplo-insufficiency is the disease driver, Compound-Het mice express normal amounts of nebulin. X-ray diffraction revealed that the actin filament is twisted with a larger radius, that tropomyosin and troponin behavior is altered, and that the myofilament spacing is increased. The unique disease mechanism of nebulin-based typical NM reveals novel therapeutic targets. Nebulin-based nemaline myopathy is a heterogenous disease with unclear pathological mechanisms. Here, the authors generate a mouse model that mimics the most common genetic cause of the disease and demonstrate that muscle weakness in this model is associated with twisted actin filaments and altered tropomyosin and troponin behaviour.
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38
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Kumari R, Jiu Y, Carman PJ, Tojkander S, Kogan K, Varjosalo M, Gunning PW, Dominguez R, Lappalainen P. Tropomodulins Control the Balance between Protrusive and Contractile Structures by Stabilizing Actin-Tropomyosin Filaments. Curr Biol 2020; 30:767-778.e5. [PMID: 32037094 DOI: 10.1016/j.cub.2019.12.049] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2019] [Revised: 11/06/2019] [Accepted: 12/16/2019] [Indexed: 02/08/2023]
Abstract
Eukaryotic cells have diverse protrusive and contractile actin filament structures, which compete with one another for a limited pool of actin monomers. Numerous actin-binding proteins regulate the dynamics of actin structures, including tropomodulins (Tmods), which cap the pointed end of actin filaments. In striated muscles, Tmods prevent actin filaments from overgrowing, whereas in non-muscle cells, their function has remained elusive. Here, we identify two Tmod isoforms, Tmod1 and Tmod3, as key components of contractile stress fibers in non-muscle cells. Individually, Tmod1 and Tmod3 can compensate for one another, but their simultaneous depletion results in disassembly of actin-tropomyosin filaments, loss of force-generating stress fibers, and severe defects in cell morphology. Knockout-rescue experiments reveal that Tmod's interaction with tropomyosin is essential for its role in the stabilization of actin-tropomyosin filaments in cells. Thus, in contrast to their role in muscle myofibrils, in non-muscle cells, Tmods bind actin-tropomyosin filaments to protect them from depolymerizing, not elongating. Furthermore, loss of Tmods shifts the balance from linear actin-tropomyosin filaments to Arp2/3 complex-nucleated branched networks, and this phenotype can be partially rescued by inhibiting the Arp2/3 complex. Collectively, the data reveal that Tmods are essential for the maintenance of contractile actomyosin bundles and that Tmod-dependent capping of actin-tropomyosin filaments is critical for the regulation of actin homeostasis in non-muscle cells.
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Affiliation(s)
- Reena Kumari
- HiLIFE Institute of Biotechnology, University of Helsinki, PO Box 56, 00014 Helsinki, Finland
| | - Yaming Jiu
- HiLIFE Institute of Biotechnology, University of Helsinki, PO Box 56, 00014 Helsinki, Finland; CAS Key Laboratory of Molecular Virology and Immunology, Institute Pasteur of Shanghai, Chinese Academy of Sciences, Life Science Research Building 320, Yueyang Road, Xuhui District, 200031 Shanghai, China; University of Chinese Academy of Sciences, Yuquan Road No.19(A), Shijingshan District, 100049 Beijing, China
| | - Peter J Carman
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, 728 Clinical Research Bldg, 415 Curie Boulevard, Philadelphia, PA 19104, USA; Graduate Group in Biochemistry and Molecular Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Sari Tojkander
- Department of Veterinary Biosciences, Faculty of Veterinary Medicine, University of Helsinki, Agnes Sjöberginkatu 2, 00014 Helsinki, Finland
| | - Konstantin Kogan
- HiLIFE Institute of Biotechnology, University of Helsinki, PO Box 56, 00014 Helsinki, Finland
| | - Markku Varjosalo
- HiLIFE Institute of Biotechnology, University of Helsinki, PO Box 56, 00014 Helsinki, Finland
| | - Peter W Gunning
- School of Medical Sciences, UNSW, Sydney, Wallace Wurth Building, Sydney, NSW 2052, Australia
| | - Roberto Dominguez
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, 728 Clinical Research Bldg, 415 Curie Boulevard, Philadelphia, PA 19104, USA
| | - Pekka Lappalainen
- HiLIFE Institute of Biotechnology, University of Helsinki, PO Box 56, 00014 Helsinki, Finland.
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Mi-Mi L, Farman GP, Mayfield RM, Strom J, Chu M, Pappas CT, Gregorio CC. In vivo elongation of thin filaments results in heart failure. PLoS One 2020; 15:e0226138. [PMID: 31899774 PMCID: PMC6941805 DOI: 10.1371/journal.pone.0226138] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2019] [Accepted: 11/20/2019] [Indexed: 12/20/2022] Open
Abstract
A novel cardiac-specific transgenic mouse model was generated to identify the physiological consequences of elongated thin filaments during post-natal development in the heart. Remarkably, increasing the expression levels in vivo of just one sarcomeric protein, Lmod2, results in ~10% longer thin filaments (up to 26% longer in some individual sarcomeres) that produce up to 50% less contractile force. Increasing the levels of Lmod2 in vivo (Lmod2-TG) also allows us to probe the contribution of Lmod2 in the progression of cardiac myopathy because Lmod2-TG mice present with a unique cardiomyopathy involving enlarged atrial and ventricular lumens, increased heart mass, disorganized myofibrils and eventually, heart failure. Turning off of Lmod2 transgene expression at postnatal day 3 successfully prevents thin filament elongation, as well as gross morphological and functional disease progression. We show here that Lmod2 has an essential role in regulating cardiac contractile force and function.
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Affiliation(s)
- Lei Mi-Mi
- Department of Cellular and Molecular Medicine and Sarver Molecular Cardiovascular Research Program, The University of Arizona, Tucson, AZ, United States of America
| | - Gerrie P. Farman
- Department of Cellular and Molecular Medicine and Sarver Molecular Cardiovascular Research Program, The University of Arizona, Tucson, AZ, United States of America
| | - Rachel M. Mayfield
- Department of Cellular and Molecular Medicine and Sarver Molecular Cardiovascular Research Program, The University of Arizona, Tucson, AZ, United States of America
| | - Joshua Strom
- Department of Cellular and Molecular Medicine and Sarver Molecular Cardiovascular Research Program, The University of Arizona, Tucson, AZ, United States of America
| | - Miensheng Chu
- Department of Cellular and Molecular Medicine and Sarver Molecular Cardiovascular Research Program, The University of Arizona, Tucson, AZ, United States of America
| | - Christopher T. Pappas
- Department of Cellular and Molecular Medicine and Sarver Molecular Cardiovascular Research Program, The University of Arizona, Tucson, AZ, United States of America
| | - Carol C. Gregorio
- Department of Cellular and Molecular Medicine and Sarver Molecular Cardiovascular Research Program, The University of Arizona, Tucson, AZ, United States of America
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40
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Ahrens-Nicklas RC, Pappas CT, Farman GP, Mayfield RM, Larrinaga TM, Medne L, Ritter A, Krantz ID, Murali C, Lin KY, Berger JH, Yum SW, Carreon CK, Gregorio CC. Disruption of cardiac thin filament assembly arising from a mutation in LMOD2: A novel mechanism of neonatal dilated cardiomyopathy. SCIENCE ADVANCES 2019; 5:eaax2066. [PMID: 31517052 PMCID: PMC6726455 DOI: 10.1126/sciadv.aax2066] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2019] [Accepted: 07/31/2019] [Indexed: 05/10/2023]
Abstract
Neonatal heart failure is a rare, poorly-understood presentation of familial dilated cardiomyopathy (DCM). Exome sequencing in a neonate with severe DCM revealed a homozygous nonsense variant in leiomodin 2 (LMOD2, p.Trp398*). Leiomodins (Lmods) are actin-binding proteins that regulate actin filament assembly. While disease-causing mutations in smooth (LMOD1) and skeletal (LMOD3) muscle isoforms have been described, the cardiac (LMOD2) isoform has not been previously associated with human disease. Like our patient, Lmod2-null mice have severe early-onset DCM and die before weaning. The infant's explanted heart showed extraordinarily short thin filaments with isolated cardiomyocytes displaying a large reduction in maximum calcium-activated force production. The lack of extracardiac symptoms in Lmod2-null mice, and remarkable morphological and functional similarities between the patient and mouse model informed the decision to pursue cardiac transplantation in the patient. To our knowledge, this is the first report of aberrant cardiac thin filament assembly associated with human cardiomyopathy.
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Affiliation(s)
- Rebecca C. Ahrens-Nicklas
- Division of Human Genetics, The Children’s Hospital of Philadelphia, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA
| | - Christopher T. Pappas
- Department of Cellular and Molecular Medicine and Sarver Molecular Cardiovascular Research Program, The University of Arizona, Tucson, AZ, USA
| | - Gerrie P. Farman
- Department of Cellular and Molecular Medicine and Sarver Molecular Cardiovascular Research Program, The University of Arizona, Tucson, AZ, USA
| | - Rachel M. Mayfield
- Department of Cellular and Molecular Medicine and Sarver Molecular Cardiovascular Research Program, The University of Arizona, Tucson, AZ, USA
| | - Tania M. Larrinaga
- Department of Cellular and Molecular Medicine and Sarver Molecular Cardiovascular Research Program, The University of Arizona, Tucson, AZ, USA
| | - Livija Medne
- Division of Human Genetics, The Children’s Hospital of Philadelphia, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA
| | - Alyssa Ritter
- Division of Human Genetics, The Children’s Hospital of Philadelphia, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA
| | - Ian D. Krantz
- Division of Human Genetics, The Children’s Hospital of Philadelphia, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA
| | - Chaya Murali
- Division of Human Genetics, The Children’s Hospital of Philadelphia, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA
| | - Kimberly Y. Lin
- Division of Pediatric Cardiology, The Children’s Hospital of Philadelphia, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA
| | - Justin H. Berger
- Division of Pediatric Cardiology, The Children’s Hospital of Philadelphia, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA
| | - Sabrina W. Yum
- Division of Pediatric Neurology, The Children’s Hospital of Philadelphia, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA
| | - Chrystalle Katte Carreon
- Department of Pathology, The Children’s Hospital of Philadelphia, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA
| | - Carol C. Gregorio
- Department of Cellular and Molecular Medicine and Sarver Molecular Cardiovascular Research Program, The University of Arizona, Tucson, AZ, USA
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41
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Yamashiro S, Watanabe N. Quantitative high-precision imaging of myosin-dependent filamentous actin dynamics. J Muscle Res Cell Motil 2019; 41:163-173. [PMID: 31313218 DOI: 10.1007/s10974-019-09541-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2019] [Accepted: 07/10/2019] [Indexed: 12/20/2022]
Abstract
Over recent decades, considerable effort has been made to understand how mechanical stress applied to the actin network alters actin assembly and disassembly dynamics. However, there are conflicting reports concerning the issue both in vitro and in cells. In this review, we discuss concerns regarding previous quantitative live-cell experiments that have attempted to evaluate myosin regulation of filamentous actin (F-actin) turnover. In particular, we highlight an error-generating mechanism in quantitative live-cell imaging, namely convection-induced misdistribution of actin-binding probes. Direct observation of actin turnover at the single-molecule level using our improved electroporation-based Single-Molecule Speckle (eSiMS) microscopy technique overcomes these concerns. We introduce our recent single-molecule analysis that unambiguously demonstrates myosin-dependent regulation of F-actin stability in live cells. We also discuss the possible application of eSiMS microscopy in the analysis of actin remodeling in striated muscle cells.
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Affiliation(s)
- Sawako Yamashiro
- Laboratory of Single-Molecule Cell Biology, Kyoto University Graduate School of Biostudies, Yoshida Konoe-cho, Sakyo-ku, Kyoto, 606-8501, Japan. .,Department of Pharmacology, Kyoto University Graduate School of Medicine, Kyoto, Japan.
| | - Naoki Watanabe
- Laboratory of Single-Molecule Cell Biology, Kyoto University Graduate School of Biostudies, Yoshida Konoe-cho, Sakyo-ku, Kyoto, 606-8501, Japan.,Department of Pharmacology, Kyoto University Graduate School of Medicine, Kyoto, Japan
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42
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Thin filament dysfunctions caused by mutations in tropomyosin Tpm3.12 and Tpm1.1. J Muscle Res Cell Motil 2019; 41:39-53. [PMID: 31270709 PMCID: PMC7109180 DOI: 10.1007/s10974-019-09532-y] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Accepted: 06/26/2019] [Indexed: 12/14/2022]
Abstract
Tropomyosin is the major regulator of the thin filament. In striated muscle its function is to bind troponin complex and control the access of myosin heads to actin in a Ca2+-dependent manner. It also participates in the maintenance of thin filament length by regulation of tropomodulin and leiomodin, the pointed end-binding proteins. Because the size of the overlap between actin and myosin filaments affects the number of myosin heads which interact with actin, the filament length is one of the determinants of force development. Numerous point mutations in genes encoding tropomyosin lead to single amino acid substitutions along the entire length of the coiled coil that are associated with various types of cardiomyopathy and skeletal muscle disease. Specific regions of tropomyosin interact with different binding partners; therefore, the mutations affect diverse tropomyosin functions. In this review, results of studies on mutations in the genes TPM1 and TPM3, encoding Tpm1.1 and Tpm3.12, are described. The paper is particularly focused on mutation-dependent alterations in the mechanisms of actin-myosin interactions and dynamics of the thin filament at the pointed end.
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43
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Viita T, Kyheröinen S, Prajapati B, Virtanen J, Frilander MJ, Varjosalo M, Vartiainen MK. Nuclear actin interactome analysis links actin to KAT14 histone acetyl transferase and mRNA splicing. J Cell Sci 2019; 132:jcs226852. [PMID: 30890647 PMCID: PMC6503952 DOI: 10.1242/jcs.226852] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2018] [Accepted: 03/05/2019] [Indexed: 12/25/2022] Open
Abstract
In addition to its essential functions within the cytoskeleton, actin also localizes to the cell nucleus, where it is linked to many important nuclear processes from gene expression to maintenance of genomic integrity. However, the molecular mechanisms by which actin operates in the nucleus remain poorly understood. Here, we have used two complementary mass spectrometry (MS) techniques, AP-MS and BioID, to identify binding partners for nuclear actin. Common high-confidence interactions highlight the role of actin in chromatin-remodeling complexes and identify the histone-modifying complex human Ada-Two-A-containing (hATAC) as a novel actin-containing nuclear complex. Actin binds directly to the hATAC subunit KAT14, and modulates its histone acetyl transferase activity in vitro and in cells. Transient interactions detected through BioID link actin to several steps of transcription as well as to RNA processing. Alterations in nuclear actin levels disturb alternative splicing in minigene assays, likely by affecting the transcription elongation rate. This interactome analysis thus identifies both novel direct binding partners and functional roles for nuclear actin, as well as forms a platform for further mechanistic studies on how actin operates during essential nuclear processes.This article has an associated First Person interview with the first author of the paper.
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Affiliation(s)
- Tiina Viita
- Institute of Biotechnology, University of Helsinki, Helsinki 00014, Finland
- Helsinki Institute of Life Science, University of Helsinki, Helsinki 00014, Finland
| | - Salla Kyheröinen
- Institute of Biotechnology, University of Helsinki, Helsinki 00014, Finland
- Helsinki Institute of Life Science, University of Helsinki, Helsinki 00014, Finland
| | - Bina Prajapati
- Institute of Biotechnology, University of Helsinki, Helsinki 00014, Finland
- Helsinki Institute of Life Science, University of Helsinki, Helsinki 00014, Finland
| | - Jori Virtanen
- Institute of Biotechnology, University of Helsinki, Helsinki 00014, Finland
- Helsinki Institute of Life Science, University of Helsinki, Helsinki 00014, Finland
| | - Mikko J Frilander
- Institute of Biotechnology, University of Helsinki, Helsinki 00014, Finland
- Helsinki Institute of Life Science, University of Helsinki, Helsinki 00014, Finland
| | - Markku Varjosalo
- Institute of Biotechnology, University of Helsinki, Helsinki 00014, Finland
- Helsinki Institute of Life Science, University of Helsinki, Helsinki 00014, Finland
- Proteomics Unit, University of Helsinki, Helsinki 00014, Finland
| | - Maria K Vartiainen
- Institute of Biotechnology, University of Helsinki, Helsinki 00014, Finland
- Helsinki Institute of Life Science, University of Helsinki, Helsinki 00014, Finland
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44
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Role of intrinsic disorder in muscle sarcomeres. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2019; 166:311-340. [PMID: 31521234 DOI: 10.1016/bs.pmbts.2019.03.014] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The role and utility of intrinsically disordered regions (IDRs) is reviewed for two groups of sarcomeric proteins, such as members of tropomodulin/leiomodin (Tmod/Lmod) protein homology group and myosin binding protein C (MyBP-C). These two types of sarcomeric proteins represent very different but strongly interdependent functions, being responsible for maintaining structure and operation of the muscle sarcomere. The role of IDRs in the formation of complexes between thin filaments and Tmods/Lmods is discussed within the framework of current understanding of the thin filament length regulation. For MyBP-C, the function of IDRs is discussed in the context of MYBP-C-dependent sarcomere contraction and actomyosin activation.
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45
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Nucleotide-dependent conformational changes in the actin filament: Subtler than expected. Proc Natl Acad Sci U S A 2019; 116:3959-3961. [PMID: 30782816 DOI: 10.1073/pnas.1900799116] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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46
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Parreno J, Fowler VM. Multifunctional roles of tropomodulin-3 in regulating actin dynamics. Biophys Rev 2018; 10:1605-1615. [PMID: 30430457 DOI: 10.1007/s12551-018-0481-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Accepted: 11/08/2018] [Indexed: 12/12/2022] Open
Abstract
Tropomodulins (Tmods) are proteins that cap the slow-growing (pointed) ends of actin filaments (F-actin). The basis for our current understanding of Tmod function comes from studies in cells with relatively stable and highly organized F-actin networks, leading to the view that Tmod capping functions principally to preserve F-actin stability. However, not only is Tmod capping dynamic, but it also can play major roles in regulating diverse cellular processes involving F-actin remodeling. Here, we highlight the multifunctional roles of Tmod with a focus on Tmod3. Like other Tmods, Tmod3 binds tropomyosin (Tpm) and actin, capping pure F-actin at submicromolar and Tpm-coated F-actin at nanomolar concentrations. Unlike other Tmods, Tmod3 can also bind actin monomers and its ability to bind actin is inhibited by phosphorylation of Tmod3 by Akt2. Tmod3 is ubiquitously expressed and is present in a diverse array of cytoskeletal structures, including contractile structures such as sarcomere-like units of actomyosin stress fibers and in the F-actin network encompassing adherens junctions. Tmod3 participates in F-actin network remodeling in lamellipodia during cell migration and in the assembly of specialized F-actin networks during exocytosis. Furthermore, Tmod3 is required for development, regulating F-actin mesh formation during meiosis I of mouse oocytes, erythroblast enucleation in definitive erythropoiesis, and megakaryocyte morphogenesis in the mouse fetal liver. Thus, Tmod3 plays vital roles in dynamic and stable F-actin networks in cell physiology and development, with further research required to delineate the mechanistic details of Tmod3 regulation in the aforementioned processes, or in other yet to be discovered processes.
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Affiliation(s)
- Justin Parreno
- Department of Molecular Medicine, The Scripps Research Institute, 10550 N. Torrey Pines Road, La Jolla, CA, 92037, USA
| | - Velia M Fowler
- Department of Molecular Medicine, The Scripps Research Institute, 10550 N. Torrey Pines Road, La Jolla, CA, 92037, USA.
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Tropomodulin Isoform-Specific Regulation of Dendrite Development and Synapse Formation. J Neurosci 2018; 38:10271-10285. [PMID: 30301754 DOI: 10.1523/jneurosci.3325-17.2018] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2017] [Revised: 09/25/2018] [Accepted: 10/02/2018] [Indexed: 11/21/2022] Open
Abstract
Neurons of the CNS elaborate highly branched dendritic arbors that host numerous dendritic spines, which serve as the postsynaptic platform for most excitatory synapses. The actin cytoskeleton plays an important role in dendrite development and spine formation, but the underlying mechanisms remain incompletely understood. Tropomodulins (Tmods) are a family of actin-binding proteins that cap the slow-growing (pointed) end of actin filaments, thereby regulating the stability, length, and architecture of complex actin networks in diverse cell types. Three members of the Tmod family, Tmod1, Tmod2, and Tmod3 are expressed in the vertebrate CNS, but their function in neuronal development is largely unknown. In this study, we present evidence that Tmod1 and Tmod2 exhibit distinct roles in regulating spine development and dendritic arborization, respectively. Using rat hippocampal tissues from both sexes, we find that Tmod1 and Tmod2 are expressed with distinct developmental profiles: Tmod2 is expressed early during hippocampal development, whereas Tmod1 expression coincides with synaptogenesis. We then show that knockdown of Tmod2, but not Tmod1, severely impairs dendritic branching. Both Tmod1 and Tmod2 are localized to a distinct subspine region where they regulate local F-actin stability. However, the knockdown of Tmod1, but not Tmod2, disrupts spine morphogenesis and impairs synapse formation. Collectively, these findings demonstrate that regulation of the actin cytoskeleton by different members of the Tmod family plays an important role in distinct aspects of dendrite and spine development.SIGNIFICANCE STATEMENT The Tropomodulin family of molecules is best known for controlling the length and stability of actin myofilaments in skeletal muscles. While several Tropomodulin members are expressed in the brain, fundamental knowledge about their role in neuronal function is limited. In this study, we show the unique expression profile and subcellular distribution of Tmod1 and Tmod2 in hippocampal neurons. While both Tmod1 and Tmod2 regulate F-actin stability, we find that they exhibit isoform-specific roles in dendrite development and synapse formation: Tmod2 regulates dendritic arborization, whereas Tmod1 is required for spine development and synapse formation. These findings provide novel insight into the actin regulatory mechanisms underlying neuronal development, thereby shedding light on potential pathways disrupted in a number of neurological disorders.
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Pappas CT, Farman GP, Mayfield RM, Konhilas JP, Gregorio CC. Cardiac-specific knockout of Lmod2 results in a severe reduction in myofilament force production and rapid cardiac failure. J Mol Cell Cardiol 2018; 122:88-97. [PMID: 30102883 DOI: 10.1016/j.yjmcc.2018.08.009] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Revised: 07/30/2018] [Accepted: 08/10/2018] [Indexed: 11/29/2022]
Abstract
Leiomodin-2 (Lmod2) is a striated muscle-specific actin binding protein that is implicated in assembly of thin filaments. The necessity of Lmod2 in the adult mouse and role it plays in the mechanics of contraction are unknown. To answer these questions, we generated cardiac-specific conditional Lmod2 knockout mice (cKO). These mice die within a week of induction of the knockout with severe left ventricular systolic dysfunction and little change in cardiac morphology. Cardiac trabeculae isolated from cKO mice have a significant decrease in maximum force production and a blunting of myofilament length-dependent activation. Thin filaments are non-uniform and substantially reduced in length in cKO hearts, affecting the functional overlap of the thick and thin filaments. Remarkably, we also found that Lmod2 levels are directly linked to thin filament length and cardiac function in vivo, with a low amount (<20%) of Lmod2 necessary to maintain cardiac function. Thus, Lmod2 plays an essential role in maintaining proper cardiac thin filament length in adult mice, which in turn is necessary for proper generation of contractile force. Dysregulation of thin filament length in the absence of Lmod2 contributes to heart failure.
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Affiliation(s)
- Christopher T Pappas
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ, USA; Department of Physiology and Sarver Molecular Cardiovascular Research Program, University of Arizona, Tucson, AZ, USA.
| | - Gerrie P Farman
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ, USA; Department of Physiology and Sarver Molecular Cardiovascular Research Program, University of Arizona, Tucson, AZ, USA
| | - Rachel M Mayfield
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ, USA; Department of Physiology and Sarver Molecular Cardiovascular Research Program, University of Arizona, Tucson, AZ, USA
| | - John P Konhilas
- Department of Physiology and Sarver Molecular Cardiovascular Research Program, University of Arizona, Tucson, AZ, USA
| | - Carol C Gregorio
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ, USA; Department of Physiology and Sarver Molecular Cardiovascular Research Program, University of Arizona, Tucson, AZ, USA
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Rottner K, Faix J, Bogdan S, Linder S, Kerkhoff E. Actin assembly mechanisms at a glance. J Cell Sci 2018; 130:3427-3435. [PMID: 29032357 DOI: 10.1242/jcs.206433] [Citation(s) in RCA: 195] [Impact Index Per Article: 32.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The actin cytoskeleton and associated motor proteins provide the driving forces for establishing the astonishing morphological diversity and dynamics of mammalian cells. Aside from functions in protruding and contracting cell membranes for motility, differentiation or cell division, the actin cytoskeleton provides forces to shape and move intracellular membranes of organelles and vesicles. To establish the many different actin assembly functions required in time and space, actin nucleators are targeted to specific subcellular compartments, thereby restricting the generation of specific actin filament structures to those sites. Recent research has revealed that targeting and activation of actin filament nucleators, elongators and myosin motors are tightly coordinated by conserved protein complexes to orchestrate force generation. In this Cell Science at a Glance article and the accompanying poster, we summarize and discuss the current knowledge on the corresponding protein complexes and their modes of action in actin nucleation, elongation and force generation.
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Affiliation(s)
- Klemens Rottner
- Division of Molecular Cell Biology, Zoological Institute, Technische Universität Braunschweig, 38106 Braunschweig, Germany.,Department of Cell Biology, Helmholtz Centre for Infection Research, 38124 Braunschweig, Germany
| | - Jan Faix
- Institute for Biophysical Chemistry, Hannover Medical School, 30625 Hannover, Germany
| | - Sven Bogdan
- Institute for Physiology and Pathophysiology, Department of Molecular Cell Physiology, Philipps-University of Marburg, 35032 Marburg, Germany
| | - Stefan Linder
- Institute for Medical Microbiology, Virology and Hygiene, University Medical Center Eppendorf, 20246 Hamburg, Germany
| | - Eugen Kerkhoff
- Department of Neurology, University Hospital Regensburg, 93053 Regensburg, Germany
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50
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Ehler E. Actin-associated proteins and cardiomyopathy-the 'unknown' beyond troponin and tropomyosin. Biophys Rev 2018; 10:1121-1128. [PMID: 29869751 PMCID: PMC6082317 DOI: 10.1007/s12551-018-0428-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Accepted: 05/18/2018] [Indexed: 02/06/2023] Open
Abstract
It has been known for several decades that mutations in genes that encode for proteins involved in the control of actomyosin interactions such as the troponin complex, tropomyosin and MYBP-C and thus regulate contraction can lead to hereditary hypertrophic cardiomyopathy. In recent years, it has become apparent that actin-binding proteins not directly involved in the regulation of contraction also can exhibit changed expression levels, show altered subcellular localisation or bear mutations that might lead to hereditary cardiomyopathies. The aim of this review is to look beyond the troponin/tropomyosin mechanism and to give an overview of the different types of actin-associated proteins and their potential roles in cardiomyocytes. It will then discuss recent findings relevant to their involvement in heart disease.
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Affiliation(s)
- Elisabeth Ehler
- Randall Centre for Cell and Molecular Biophysics (School of Basic and Medical Biosciences), London, UK. .,School of Cardiovascular Medicine and Sciences, British Heart Foundation Research Excellence Centre, King's College London, Room 3.26A, New Hunt's House, Guy's Campus, London, SE1 1UL, UK.
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