1
|
Robaszkiewicz K, Wróbel J, Moraczewska J. Troponin and a Myopathy-Linked Mutation in TPM3 Inhibit Cofilin-2-Induced Thin Filament Depolymerization. Int J Mol Sci 2023; 24:16457. [PMID: 38003645 PMCID: PMC10671271 DOI: 10.3390/ijms242216457] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2023] [Revised: 11/10/2023] [Accepted: 11/13/2023] [Indexed: 11/26/2023] Open
Abstract
Uniform actin filament length is required for synchronized contraction of skeletal muscle. In myopathies linked to mutations in tropomyosin (Tpm) genes, irregular thin filaments are a common feature, which may result from defects in length maintenance mechanisms. The current work investigated the effects of the myopathy-causing p.R91C variant in Tpm3.12, a tropomyosin isoform expressed in slow-twitch muscle fibers, on the regulation of actin severing and depolymerization by cofilin-2. The affinity of cofilin-2 for F-actin was not significantly changed by either Tpm3.12 or Tpm3.12-R91C, though it increased two-fold in the presence of troponin (without Ca2+). Saturation of the filament with cofilin-2 removed both Tpm variants from the filament, although Tpm3.12-R91C was more resistant. In the presence of troponin (±Ca2+), Tpm remained on the filament, even at high cofilin-2 concentrations. Both Tpm3.12 variants inhibited filament severing and depolymerization by cofilin-2. However, the inhibition was more efficient in the presence of Tpm3.12-R91C, indicating that the pathogenic variant impaired cofilin-2-dependent actin filament turnover. Troponin (±Ca2+) further inhibited but did not completely stop cofilin-2-dependent actin severing and depolymerization.
Collapse
Affiliation(s)
| | | | - Joanna Moraczewska
- Department of Biochemistry and Cell Biology, Faculty of Biological Sciences, Kazimierz Wielki University in Bydgoszcz, 85-671 Bydgoszcz, Poland; (K.R.); (J.W.)
| |
Collapse
|
2
|
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.
Collapse
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
| |
Collapse
|
3
|
Karpicheva OE, Avrova SV, Bogdanov AL, Sirenko VV, Redwood CS, Borovikov YS. Molecular Mechanisms of Deregulation of Muscle Contractility Caused by the R168H Mutation in TPM3 and Its Attenuation by Therapeutic Agents. Int J Mol Sci 2023; 24:ijms24065829. [PMID: 36982903 PMCID: PMC10051413 DOI: 10.3390/ijms24065829] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Revised: 03/13/2023] [Accepted: 03/13/2023] [Indexed: 03/30/2023] Open
Abstract
The substitution for Arg168His (R168H) in γ-tropomyosin (TPM3 gene, Tpm3.12 isoform) is associated with congenital muscle fiber type disproportion (CFTD) and muscle weakness. It is still unclear what molecular mechanisms underlie the muscle dysfunction seen in CFTD. The aim of this work was to study the effect of the R168H mutation in Tpm3.12 on the critical conformational changes that myosin, actin, troponin, and tropomyosin undergo during the ATPase cycle. We used polarized fluorescence microscopy and ghost muscle fibers containing regulated thin filaments and myosin heads (myosin subfragment-1) modified with the 1,5-IAEDANS fluorescent probe. Analysis of the data obtained revealed that a sequential interdependent conformational-functional rearrangement of tropomyosin, actin and myosin heads takes place when modeling the ATPase cycle in the presence of wild-type tropomyosin. A multistep shift of the tropomyosin strands from the outer to the inner domain of actin occurs during the transition from weak to strong binding of myosin to actin. Each tropomyosin position determines the corresponding balance between switched-on and switched-off actin monomers and between the strongly and weakly bound myosin heads. At low Ca2+, the R168H mutation was shown to switch some extra actin monomers on and increase the persistence length of tropomyosin, demonstrating the freezing of the R168HTpm strands close to the open position and disruption of the regulatory function of troponin. Instead of reducing the formation of strong bonds between myosin heads and F-actin, troponin activated it. However, at high Ca2+, troponin decreased the amount of strongly bound myosin heads instead of promoting their formation. Abnormally high sensitivity of thin filaments to Ca2+, inhibition of muscle fiber relaxation due to the appearance of the myosin heads strongly associated with F-actin, and distinct activation of the contractile system at submaximal concentrations of Ca2+ can lead to muscle inefficiency and weakness. Modulators of troponin (tirasemtiv and epigallocatechin-3-gallate) and myosin (omecamtiv mecarbil and 2,3-butanedione monoxime) have been shown to more or less attenuate the negative effects of the tropomyosin R168H mutant. Tirasemtiv and epigallocatechin-3-gallate may be used to prevent muscle dysfunction.
Collapse
Affiliation(s)
- Olga E Karpicheva
- Institute of Cytology, Russian Academy of Sciences, 4 Tikhoretsky Av., St. Petersburg 194064, Russia
| | - Stanislava V Avrova
- Institute of Cytology, Russian Academy of Sciences, 4 Tikhoretsky Av., St. Petersburg 194064, Russia
| | - Andrey L Bogdanov
- Institute of Cytology, Russian Academy of Sciences, 4 Tikhoretsky Av., St. Petersburg 194064, Russia
| | - Vladimir V Sirenko
- Institute of Cytology, Russian Academy of Sciences, 4 Tikhoretsky Av., St. Petersburg 194064, Russia
| | - Charles S Redwood
- Radcliffe Department of Medicine, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DU, UK
| | - Yurii S Borovikov
- Institute of Cytology, Russian Academy of Sciences, 4 Tikhoretsky Av., St. Petersburg 194064, Russia
| |
Collapse
|
4
|
Keyt LK, Duran JM, Bui QM, Chen C, Miyamoto MI, Silva Enciso J, Tardiff JC, Adler ED. Thin filament cardiomyopathies: A review of genetics, disease mechanisms, and emerging therapeutics. Front Cardiovasc Med 2022; 9:972301. [PMID: 36158814 PMCID: PMC9489950 DOI: 10.3389/fcvm.2022.972301] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2022] [Accepted: 07/28/2022] [Indexed: 11/17/2022] Open
Abstract
All muscle contraction occurs due to the cyclical interaction between sarcomeric thin and thick filament proteins within the myocyte. The thin filament consists of the proteins actin, tropomyosin, Troponin C, Troponin I, and Troponin T. Mutations in these proteins can result in various forms of cardiomyopathy, including hypertrophic, restrictive, and dilated phenotypes and account for as many as 30% of all cases of inherited cardiomyopathy. There is significant evidence that thin filament mutations contribute to dysregulation of Ca2+ within the sarcomere and may have a distinct pathomechanism of disease from cardiomyopathy associated with thick filament mutations. A number of distinct clinical findings appear to be correlated with thin-filament mutations: greater degrees of restrictive cardiomyopathy and relatively less left ventricular (LV) hypertrophy and LV outflow tract obstruction than that seen with thick filament mutations, increased morbidity associated with heart failure, increased arrhythmia burden and potentially higher mortality. Most therapies that improve outcomes in heart failure blunt the neurohormonal pathways involved in cardiac remodeling, while most therapies for hypertrophic cardiomyopathy involve use of negative inotropes to reduce LV hypertrophy or septal reduction therapies to reduce LV outflow tract obstruction. None of these therapies directly address the underlying sarcomeric dysfunction associated with thin-filament mutations. With mounting evidence that thin filament cardiomyopathies occur through a distinct mechanism, there is need for therapies targeting the unique, underlying mechanisms tailored for each patient depending on a given mutation.
Collapse
Affiliation(s)
- Lucas K. Keyt
- Department of Internal Medicine, University of California, San Diego, San Diego, CA, United States
| | - Jason M. Duran
- Department of Cardiology, University of California, San Diego, San Diego, CA, United States
| | - Quan M. Bui
- Department of Cardiology, University of California, San Diego, San Diego, CA, United States
| | - Chao Chen
- Department of Cardiology, University of California, San Diego, San Diego, CA, United States
| | | | - Jorge Silva Enciso
- Department of Cardiology, University of California, San Diego, San Diego, CA, United States
| | - Jil C. Tardiff
- Department of Medicine and Biomedical Engineering, University of Arizona, Tucson, AZ, United States
| | - Eric D. Adler
- Department of Cardiology, University of California, San Diego, San Diego, CA, United States
| |
Collapse
|
5
|
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.
Collapse
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
| |
Collapse
|
6
|
Karpicheva OE. Hallmark Features of the Tropomyosin
Regulatory Function in Several Variants of Congenital Myopathy. J EVOL BIOCHEM PHYS+ 2021. [DOI: 10.1134/s0022093021030133] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
|
7
|
Mutations Q93H and E97K in TPM2 Disrupt Ca-Dependent Regulation of Actin Filaments. Int J Mol Sci 2021; 22:ijms22084036. [PMID: 33919826 PMCID: PMC8070786 DOI: 10.3390/ijms22084036] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Revised: 04/09/2021] [Accepted: 04/12/2021] [Indexed: 12/12/2022] Open
Abstract
Tropomyosin is a two-chain coiled coil protein, which together with the troponin complex controls interactions of actin with myosin in a Ca2+-dependent manner. In fast skeletal muscle, the contractile actin filaments are regulated by tropomyosin isoforms Tpm1.1 and Tpm2.2, which form homo- and heterodimers. Mutations in the TPM2 gene encoding isoform Tpm2.2 are linked to distal arthrogryposis and congenital myopathy-skeletal muscle diseases characterized by hyper- and hypocontractile phenotypes, respectively. In this work, in vitro functional assays were used to elucidate the molecular mechanisms of mutations Q93H and E97K in TPM2. Both mutations tended to decrease actin affinity of homo-and heterodimers in the absence and presence of troponin and Ca2+, although the effect of Q93H was stronger. Changes in susceptibility of tropomyosin to trypsin digestion suggested that the mutations diversified dynamics of tropomyosin homo- and heterodimers on the filament. The presence of Q93H in homo- and heterodimers strongly decreased activation of the actomyosin ATPase and reduced sensitivity of the thin filament to [Ca2+]. In contrast, the presence of E97K caused hyperactivation of the ATPase and increased sensitivity to [Ca2+]. In conclusion, the hypo- and hypercontractile phenotypes associated with mutations Q93H and E97K in Tpm2.2 are caused by defects in Ca2+-dependent regulation of actin-myosin interactions.
Collapse
|
8
|
Gonchar AD, Kopylova GV, Kochurova AM, Berg VY, Shchepkin DV, Koubasova NA, Tsaturyan AK, Kleymenov SY, Matyushenko AM, Levitsky DI. Effects of myopathy-causing mutations R91P and R245G in the TPM3 gene on structural and functional properties of slow skeletal muscle tropomyosin. Biochem Biophys Res Commun 2020; 534:8-13. [PMID: 33307294 DOI: 10.1016/j.bbrc.2020.11.103] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2020] [Accepted: 11/26/2020] [Indexed: 12/16/2022]
Abstract
Tropomyosin (Tpm) is an actin-binding protein that plays a crucial role in the regulation of muscle contraction. Numerous point mutations in the TPM3 gene encoding Tpm of slow skeletal muscles (Tpm 3.12 or γ-Tpm) are associated with the genesis of various congenital myopathies. Two of these mutations, R91P and R245G, are associated with congenital fiber-type disproportion (CFTD) characterized by hypotonia and generalized muscle weakness. We applied various methods to investigate how these mutations affect the structural and functional properties of γγ-Tpm homodimers. The results show that both these mutations lead to strong structural changes in the γγ-Tpm molecule and significantly impaired its functional properties. These changes in the Tpm properties caused by R91P and R245G mutations give insight into the molecular mechanism of the CFTD development and the weakness of slow skeletal muscles observed in this inherited disease.
Collapse
Affiliation(s)
- Anastasiia D Gonchar
- A.N. Bach Institute of Biochemistry, Research Center of Biotechnology, Russian Academy of Sciences, Moscow, 119071, Russia; Department of Biochemistry, School of Biology, Moscow State University, Moscow, 119234, Russia
| | - Galina V Kopylova
- Institute of Immunology and Physiology, The Russian Academy of Sciences, Yekaterinburg, 620049, Russia
| | - Anastasia M Kochurova
- Institute of Immunology and Physiology, The Russian Academy of Sciences, Yekaterinburg, 620049, Russia
| | - Valentina Y Berg
- Institute of Immunology and Physiology, The Russian Academy of Sciences, Yekaterinburg, 620049, Russia
| | - Daniil V Shchepkin
- Institute of Immunology and Physiology, The Russian Academy of Sciences, Yekaterinburg, 620049, Russia
| | | | | | - Sergey Y Kleymenov
- A.N. Bach Institute of Biochemistry, Research Center of Biotechnology, Russian Academy of Sciences, Moscow, 119071, Russia; Koltzov Institute of Developmental Biology of the Russian Academy of Sciences, 119334, Moscow, Russia
| | - Alexander M Matyushenko
- A.N. Bach Institute of Biochemistry, Research Center of Biotechnology, Russian Academy of Sciences, Moscow, 119071, Russia
| | - Dmitrii I Levitsky
- A.N. Bach Institute of Biochemistry, Research Center of Biotechnology, Russian Academy of Sciences, Moscow, 119071, Russia.
| |
Collapse
|
9
|
Looking for Targets to Restore the Contractile Function in Congenital Myopathy Caused by Gln 147Pro Tropomyosin. Int J Mol Sci 2020; 21:ijms21207590. [PMID: 33066566 PMCID: PMC7589864 DOI: 10.3390/ijms21207590] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2020] [Revised: 10/06/2020] [Accepted: 10/11/2020] [Indexed: 12/15/2022] Open
Abstract
We have used the technique of polarized microfluorimetry to obtain new insight into the pathogenesis of skeletal muscle disease caused by the Gln147Pro substitution in β-tropomyosin (Tpm2.2). The spatial rearrangements of actin, myosin and tropomyosin in the single muscle fiber containing reconstituted thin filaments were studied during simulation of several stages of ATP hydrolysis cycle. The angular orientation of the fluorescence probes bound to tropomyosin was found to be changed by the substitution and was characteristic for a shift of tropomyosin strands closer to the inner actin domains. It was observed both in the absence and in the presence of troponin, Ca2+ and myosin heads at all simulated stages of the ATPase cycle. The mutant showed higher flexibility. Moreover, the Gln147Pro substitution disrupted the myosin-induced displacement of tropomyosin over actin. The irregular positioning of the mutant tropomyosin caused premature activation of actin monomers and a tendency to increase the number of myosin cross-bridges in a state of strong binding with actin at low Ca2+.
Collapse
|
10
|
Matyushenko AM, Nefedova VV, Shchepkin DV, Kopylova GV, Berg VY, Pivovarova AV, Kleymenov SY, Bershitsky SY, Levitsky DI. Mechanisms of disturbance of the contractile function of slow skeletal muscles induced by myopathic mutations in the tropomyosin TPM3 gene. FASEB J 2020; 34:13507-13520. [PMID: 32797717 DOI: 10.1096/fj.202001318r] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2020] [Revised: 07/17/2020] [Accepted: 07/24/2020] [Indexed: 12/20/2022]
Abstract
Several congenital myopathies of slow skeletal muscles are associated with mutations in the tropomyosin (Tpm) TPM3 gene. Tropomyosin is an actin-binding protein that plays a crucial role in the regulation of muscle contraction. Two Tpm isoforms, γ (Tpm3.12) and β (Tpm2.2) are expressed in human slow skeletal muscles forming γγ-homodimers and γβ-heterodimers of Tpm molecules. We applied various methods to investigate how myopathy-causing mutations M9R, E151A, and K169E in the Tpm γ-chain modify the structure-functional properties of Tpm dimers, and how this affects the muscle functioning. The results show that the features of γγ-Tpm and γβ-Tpm with substitutions in the Tpm γ-chain vary significantly. The characteristics of the γγ-Tpm depend on whether these mutations located in only one or both γ-chains. The mechanism of the development of nemaline myopathy associated with the M9R mutation was revealed. At the molecular level, a cause-and-effect relationship has been established for the development of myopathy by the K169E mutation. Also, we described the structure-functional properties of the Tpm dimers with the E151A mutation, which explain muscle weakness linked to this substitution. The results demonstrate a diversity of the molecular mechanisms of myopathy pathogenesis induced by studied Tpm mutations.
Collapse
Affiliation(s)
- Alexander M Matyushenko
- Bach Institute of Biochemistry, Research Center of Biotechnology, Russian Academy of Sciences, Moscow, Russia
| | - Victoria V Nefedova
- Bach Institute of Biochemistry, Research Center of Biotechnology, Russian Academy of Sciences, Moscow, Russia
| | - Daniil V Shchepkin
- Institute of Immunology and Physiology, Ural Branch of the Russian Academy of Sciences, Yekaterinburg, Russia
| | - Galina V Kopylova
- Institute of Immunology and Physiology, Ural Branch of the Russian Academy of Sciences, Yekaterinburg, Russia
| | - Valentina Y Berg
- Institute of Immunology and Physiology, Ural Branch of the Russian Academy of Sciences, Yekaterinburg, Russia
| | - Anastasia V Pivovarova
- Bach Institute of Biochemistry, Research Center of Biotechnology, Russian Academy of Sciences, Moscow, Russia
| | - Sergey Y Kleymenov
- Bach Institute of Biochemistry, Research Center of Biotechnology, Russian Academy of Sciences, Moscow, Russia.,Koltzov Institute of Developmental Biology, Russian Academy of Sciences, Moscow, Russia
| | - Sergey Y Bershitsky
- Institute of Immunology and Physiology, Ural Branch of the Russian Academy of Sciences, Yekaterinburg, Russia
| | - Dmitrii I Levitsky
- Bach Institute of Biochemistry, Research Center of Biotechnology, Russian Academy of Sciences, Moscow, Russia
| |
Collapse
|
11
|
Regulation of Actin Filament Length by Muscle Isoforms of Tropomyosin and Cofilin. Int J Mol Sci 2020; 21:ijms21124285. [PMID: 32560136 PMCID: PMC7352323 DOI: 10.3390/ijms21124285] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Revised: 06/11/2020] [Accepted: 06/13/2020] [Indexed: 12/17/2022] Open
Abstract
In striated muscle the extent of the overlap between actin and myosin filaments contributes to the development of force. In slow twitch muscle fibers actin filaments are longer than in fast twitch fibers, but the mechanism which determines this difference is not well understood. We hypothesized that tropomyosin isoforms Tpm1.1 and Tpm3.12, the actin regulatory proteins, which are specific respectively for fast and slow muscle fibers, differently stabilize actin filaments and regulate severing of the filaments by cofilin-2. Using in vitro assays, we showed that Tpm3.12 bound to F-actin with almost 2-fold higher apparent binding constant (Kapp) than Tpm1.1. Cofilin2 reduced Kapp of both tropomyosin isoforms. In the presence of Tpm1.1 and Tpm3.12 the filaments were longer than unregulated F-actin by 25% and 40%, respectively. None of the tropomyosins affected the affinity of cofilin-2 for F-actin, but according to the linear lattice model both isoforms increased cofilin-2 binding to an isolated site and reduced binding cooperativity. The filaments decorated with Tpm1.1 and Tpm3.12 were severed by cofilin-2 more often than unregulated filaments, but depolymerization of the severed filaments was inhibited. The stabilization of the filaments by Tpm3.12 was more efficient, which can be attributed to lower dynamics of Tpm3.12 binding to actin.
Collapse
|
12
|
Matyushenko AM, Levitsky DI. Molecular Mechanisms of Pathologies of Skeletal and Cardiac Muscles Caused by Point Mutations in the Tropomyosin Genes. BIOCHEMISTRY (MOSCOW) 2020; 85:S20-S33. [PMID: 32087052 DOI: 10.1134/s0006297920140023] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The review is devoted to tropomyosin (Tpm) - actin-binding protein, which plays a crucial role in the regulation of contraction of skeletal and cardiac muscles. Special attention is paid to myopathies and cardiomyopathies - severe hereditary diseases of skeletal and cardiac muscles associated with point mutations in Tpm genes. The current views on the molecular mechanisms of these diseases and the effects of such mutations on the Tpm structure and functions are considered in detail. Besides, some part of the review is devoted to analysis of the properties of Tpm homodimers and heterodimers with myopathic substitutions of amino acid residues in only one of the two chains of the Tpm dimeric molecule.
Collapse
Affiliation(s)
- A M Matyushenko
- Bach Institute of Biochemistry, Federal Research Center on Fundamentals of Biotechnology, Russian Academy of Sciences, Moscow, 119071, Russia.
| | - D I Levitsky
- Bach Institute of Biochemistry, Federal Research Center on Fundamentals of Biotechnology, Russian Academy of Sciences, Moscow, 119071, Russia. .,Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119992, Russia
| |
Collapse
|
13
|
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.
Collapse
|
14
|
Abstract
Nemaline myopathy (NM) is among the most common non-dystrophic congenital myopathies (incidence 1:50.000). Hallmark features of NM are skeletal muscle weakness and the presence of nemaline bodies in the muscle fiber. The clinical phenotype of NM patients is quite diverse, ranging from neonatal death to normal lifespan with almost normal motor function. As the respiratory muscles are involved as well, severely affected patients are ventilator-dependent. The mechanisms underlying muscle weakness in NM are currently poorly understood. Therefore, no therapeutic treatment is available yet. Eleven implicated genes have been identified: ten genes encode proteins that are either components of thin filament, or are thought to contribute to stability or turnover of thin filament proteins. The thin filament is a major constituent of the sarcomere, the smallest contractile unit in muscle. It is at this level of contraction – thin-thick filament interaction – where muscle weakness originates in NM patients. This review focusses on how sarcomeric gene mutations directly compromise sarcomere function in NM. Insight into the contribution of sarcomeric dysfunction to muscle weakness in NM, across the genes involved, will direct towards the development of targeted therapeutic strategies.
Collapse
Affiliation(s)
| | - Coen A.C. Ottenheijm
- Correspondence to: Coen Ottenheijm, PhD, Department of Physiology, VU University Medical Center, O|2 building, 12W-51, De Boelelaan 1118, 1081 HV Amsterdam, The Netherlands. Tel.: +31 20 4448123; Fax: +31 20 4448124; E-mail:
| |
Collapse
|
15
|
Avrova SV, Karpicheva OE, Simonyan AO, Sirenko VV, Redwood CS, Borovikov YS. The molecular mechanisms of a high Ca 2+-sensitivity and muscle weakness associated with the Ala155Thr substitution in Tpm3.12. Biochem Biophys Res Commun 2019; 515:372-377. [PMID: 31155291 DOI: 10.1016/j.bbrc.2019.05.146] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2019] [Accepted: 05/23/2019] [Indexed: 12/24/2022]
Abstract
Substitution of Ala for Thr residue in 155th position in γ-tropomyosin (Tpm3.12) is associated with muscle weakness. To understand the mechanisms of this defect, we studied the Ca2+-sensitivity of thin filaments in solution and multistep changes in mobility and spatial arrangement of actin, Tpm, and myosin heads during the ATPase cycle in reconstituted muscle fibres, using the polarized fluorescence microscopy. It was shown that the Ala155Thr (A155T) mutation increased the Ca2+-sensitivity of the thin filaments in solution. In the absence of the myosin heads in the muscle fibres, the mutation did not alter the ability of troponin to switch the thin filaments on and off at high and low Ca2+, respectively. However, upon the binding of myosin heads to the thin filaments at low Ca2+, the mutant Tpm was found to be markedly closer to the open position, than the wild-type Tpm. In the presence of the mutant Tpm, switching on of actin monomers and formation of the strong-binding state of the myosin heads were observed at low Ca2+, which indicated a higher myofilament Ca2+-sensitivity. The mutation decreased the amount of myosin heads bound strongly to actin at high Ca2+ and increased the number of these heads at relaxation. It is suggested that direct binding of myosin to Tpm may be one оf the reasons for muscle weakness associated with the A155T mutation. The use of reagents that decrease the Ca2+-sensitivity of the troponin complex may not be adequate to restore muscle function in patients with the A155T mutation.
Collapse
Affiliation(s)
- Stanislava V Avrova
- Institute of Cytology, Russian Academy of Sciences, 4 Tikhoretsky Avenue, St. Petersburg, 194064, Russia
| | - Olga E Karpicheva
- Institute of Cytology, Russian Academy of Sciences, 4 Tikhoretsky Avenue, St. Petersburg, 194064, Russia
| | - Armen O Simonyan
- Institute of Cytology, Russian Academy of Sciences, 4 Tikhoretsky Avenue, St. Petersburg, 194064, Russia
| | - Vladimir V Sirenko
- Institute of Cytology, Russian Academy of Sciences, 4 Tikhoretsky Avenue, St. Petersburg, 194064, Russia
| | - Charles S Redwood
- Radcliffe Department of Medicine, University of Oxford, John Radcliffe Hospital, Oxford, OX3 9DU, United Kingdom
| | - Yurii S Borovikov
- Institute of Cytology, Russian Academy of Sciences, 4 Tikhoretsky Avenue, St. Petersburg, 194064, Russia.
| |
Collapse
|
16
|
Moraczewska J, Robaszkiewicz K, Śliwinska M, Czajkowska M, Ly T, Kostyukova A, Wen H, Zheng W. Congenital myopathy-related mutations in tropomyosin disrupt regulatory function through altered actin affinity and tropomodulin binding. FEBS J 2019; 286:1877-1893. [PMID: 30768849 PMCID: PMC7202179 DOI: 10.1111/febs.14787] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2018] [Revised: 12/28/2018] [Accepted: 02/13/2019] [Indexed: 11/28/2022]
Abstract
Tropomyosin (Tpm) binds along actin filaments and regulates myosin binding to control muscle contraction. Tropomodulin binds to the pointed end of a filament and regulates actin dynamics, which maintains the length of a thin filament. To define the structural determinants of these Tpm functions, we examined the effects of two congenital myopathy mutations, A4V and R91C, in the Tpm gene, TPM3, which encodes the Tpm3.12 isoform, specific for slow-twitch muscle fibers. Mutation A4V is located in the tropomodulin-binding, N-terminal region of Tpm3.12. R91C is located in the actin-binding period 3 and directly interacts with actin. The A4V and R91C mutations resulted in a 2.5-fold reduced affinity of Tpm3.12 homodimers for F-actin in the absence and presence of troponin, and a two-fold decrease in actomyosin ATPase activation in the presence of Ca2+ . Actomyosin ATPase inhibition in the absence of Ca2+ was not affected. The Ca2+ sensitivity of ATPase activity was decreased by R91C, but not by A4V. In vitro, R91C altered the ability of tropomodulin 1 (Tmod1) to inhibit actin polymerization at the pointed end of the filaments, which correlated with the reduced affinity of Tpm3.12-R91C for Tmod1. Molecular dynamics simulations of Tpm3.12 in complex with F-actin suggested that both mutations reduce the affinity of Tpm3.12 for F-actin binding by perturbing the van der Waals energy, which may be attributable to two different molecular mechanisms-a reduced flexibility of Tpm3.12-R91C and an increased flexibility of Tpm3.12-A4V.
Collapse
Affiliation(s)
- Joanna Moraczewska
- Department of Biochemistry and Cell Biology, Faculty of Natural Sciences, Kazimierz Wielki University, Bydgoszcz, Poland
| | - Katarzyna Robaszkiewicz
- Department of Biochemistry and Cell Biology, Faculty of Natural Sciences, Kazimierz Wielki University, Bydgoszcz, Poland
| | - Małgorzata Śliwinska
- Department of Biochemistry and Cell Biology, Faculty of Natural Sciences, Kazimierz Wielki University, Bydgoszcz, Poland
| | - Marta Czajkowska
- Department of Biochemistry and Cell Biology, Faculty of Natural Sciences, Kazimierz Wielki University, Bydgoszcz, Poland
| | - Thu Ly
- Voiland School of Chemical Engineering and Bioengineering, University of Washington, Pullman, WA, USA
| | - Alla Kostyukova
- Voiland School of Chemical Engineering and Bioengineering, University of Washington, Pullman, WA, USA
| | - Han Wen
- Department of Physics, University at Buffalo, SUNY, NY, USA
| | - Wenjun Zheng
- Department of Physics, University at Buffalo, SUNY, NY, USA
| |
Collapse
|
17
|
The Primary Causes of Muscle Dysfunction Associated with the Point Mutations in Tpm3.12; Conformational Analysis of Mutant Proteins as a Tool for Classification of Myopathies. Int J Mol Sci 2018; 19:ijms19123975. [PMID: 30544720 PMCID: PMC6321504 DOI: 10.3390/ijms19123975] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2018] [Revised: 11/29/2018] [Accepted: 12/07/2018] [Indexed: 12/28/2022] Open
Abstract
Point mutations in genes encoding isoforms of skeletal muscle tropomyosin may cause nemaline myopathy, cap myopathy (Cap), congenital fiber-type disproportion (CFTD), and distal arthrogryposis. The molecular mechanisms of muscle dysfunction in these diseases remain unclear. We studied the effect of the E173A, R90P, E150A, and A155T myopathy-causing substitutions in γ-tropomyosin (Tpm3.12) on the position of tropomyosin in thin filaments, and the conformational state of actin monomers and myosin heads at different stages of the ATPase cycle using polarized fluorescence microscopy. The E173A, R90P, and E150A mutations produced abnormally large displacement of tropomyosin to the inner domains of actin and an increase in the number of myosin heads in strong-binding state at low and high Ca2+, which is characteristic of CFTD. On the contrary, the A155T mutation caused a decrease in the amount of such heads at high Ca2+ which is typical for mutations associated with Cap. An increase in the number of the myosin heads in strong-binding state at low Ca2+ was observed for all mutations associated with high Ca2+-sensitivity. Comparison between the typical conformational changes in mutant proteins associated with different myopathies observed with α-, β-, and γ-tropomyosins demonstrated the possibility of using such changes as tests for identifying the diseases.
Collapse
|
18
|
Simonyan AO, Sirenko VV, Karpicheva OE, Robaszkiewicz K, Śliwinska M, Moraczewska J, Krutetskaya ZI, Borovikov YS. The primary cause of muscle disfunction associated with substitutions E240K and R244G in tropomyosin is aberrant behavior of tropomyosin and response of actin and myosin during ATPase cycle. Arch Biochem Biophys 2018; 644:17-28. [PMID: 29510086 DOI: 10.1016/j.abb.2018.03.002] [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: 06/26/2017] [Revised: 02/16/2018] [Accepted: 03/02/2018] [Indexed: 10/17/2022]
Abstract
Using the polarized photometry technique we have studied the effects of two amino acid replacements, E240K and R244G, in tropomyosin (Tpm1.1) on the position of Tpm1.1 on troponin-free actin filaments and the spatial arrangement of actin monomers and myosin heads at various mimicked stages of the ATPase cycle in the ghost muscle fibres. E240 and R244 are located in the C-terminal, seventh actin-binding period, in f and b positions of the coiled-coil heptapeptide repeat. Actin, Tpm1.1, and myosin subfragment-1 (S1) were fluorescently labeled: 1.5-IAEDANS was attached to actin and S1, 5-IAF was bound to Tpm1.1. The labeled proteins were incorporated in the ghost muscle fibres and changes in polarized fluorescence during the ATPase cycle have been measured. It was found that during the ATPase cycle both mutant tropomyosins occupied a position close to the inner domain of actin. The relative amount of the myosin heads in the strongly-bound conformations and of the switched on actin monomers increased at mimicking different stages of the ATPase cycle. This might be one of the reasons for muscle dysfunction in congenital fibre type disproportion caused by the substitutions E240K and R244G in tropomyosin.
Collapse
Affiliation(s)
- Armen O Simonyan
- Institute of Cytology of the Russian Academy of Sciences, Laboratory of Molecular Basis of Cell Motility, 4 Tikhoretsky Ave., 194064, Saint Petersburg, Russia; Saint Petersburg State University, Faculty of Biology, Department of Biophysics, 7/9 Universitetskaya Emb., 199034, Saint Petersburg, Russia
| | - Vladimir V Sirenko
- Institute of Cytology of the Russian Academy of Sciences, Laboratory of Molecular Basis of Cell Motility, 4 Tikhoretsky Ave., 194064, Saint Petersburg, Russia
| | - Olga E Karpicheva
- Institute of Cytology of the Russian Academy of Sciences, Laboratory of Molecular Basis of Cell Motility, 4 Tikhoretsky Ave., 194064, Saint Petersburg, Russia
| | - Katarzyna Robaszkiewicz
- Kazimierz Wielki University in Bydgoszcz, Institute of Experimental Biology, Department of Biochemistry and Cell Biology, Ks. J. Poniatowski 12 Str., 85-671, Bydgoszcz, Poland
| | - Małgorzata Śliwinska
- Kazimierz Wielki University in Bydgoszcz, Institute of Experimental Biology, Department of Biochemistry and Cell Biology, Ks. J. Poniatowski 12 Str., 85-671, Bydgoszcz, Poland
| | - Joanna Moraczewska
- Kazimierz Wielki University in Bydgoszcz, Institute of Experimental Biology, Department of Biochemistry and Cell Biology, Ks. J. Poniatowski 12 Str., 85-671, Bydgoszcz, Poland
| | - Zoya I Krutetskaya
- Saint Petersburg State University, Faculty of Biology, Department of Biophysics, 7/9 Universitetskaya Emb., 199034, Saint Petersburg, Russia
| | - Yurii S Borovikov
- Institute of Cytology of the Russian Academy of Sciences, Laboratory of Molecular Basis of Cell Motility, 4 Tikhoretsky Ave., 194064, Saint Petersburg, Russia.
| |
Collapse
|
19
|
Śliwinska M, Robaszkiewicz K, Czajkowska M, Zheng W, Moraczewska J. Functional effects of substitutions I92T and V95A in actin-binding period 3 of tropomyosin. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2018; 1866:558-568. [PMID: 29496559 DOI: 10.1016/j.bbapap.2018.02.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2017] [Revised: 02/12/2018] [Accepted: 02/23/2018] [Indexed: 01/10/2023]
Affiliation(s)
- Małgorzata Śliwinska
- Department of Biochemistry and Cell Biology, Faculty of Natural Sciences, Kazimierz Wielki University in Bydgoszcz, Ks. J. Poniatowskiego 12 Str., 85-671 Bydgoszcz, Poland
| | - Katarzyna Robaszkiewicz
- Department of Biochemistry and Cell Biology, Faculty of Natural Sciences, Kazimierz Wielki University in Bydgoszcz, Ks. J. Poniatowskiego 12 Str., 85-671 Bydgoszcz, Poland
| | - Marta Czajkowska
- Department of Biochemistry and Cell Biology, Faculty of Natural Sciences, Kazimierz Wielki University in Bydgoszcz, Ks. J. Poniatowskiego 12 Str., 85-671 Bydgoszcz, Poland
| | - Wenjun Zheng
- Department of Physics, University at Buffalo, SUNY, Buffalo, NY 14260, United States
| | - Joanna Moraczewska
- Department of Biochemistry and Cell Biology, Faculty of Natural Sciences, Kazimierz Wielki University in Bydgoszcz, Ks. J. Poniatowskiego 12 Str., 85-671 Bydgoszcz, Poland.
| |
Collapse
|
20
|
Borovikov YS, Rysev NA, Karpicheva OE, Sirenko VV, Avrova SV, Piers A, Redwood CS. Molecular mechanisms of dysfunction of muscle fibres associated with Glu139 deletion in TPM2 gene. Sci Rep 2017; 7:16797. [PMID: 29196649 PMCID: PMC5711931 DOI: 10.1038/s41598-017-17076-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Accepted: 11/22/2017] [Indexed: 01/01/2023] Open
Abstract
Deletion of Glu139 in β-tropomyosin caused by a point mutation in TPM2 gene is associated with cap myopathy characterized by high myofilament Ca2+-sensitivity and muscle weakness. To reveal the mechanism of these disorders at molecular level, mobility and spatial rearrangements of actin, tropomyosin and the myosin heads at different stages of actomyosin cycle in reconstituted single ghost fibres were investigated by polarized fluorescence microscopy. The mutation did not alter tropomyosin's affinity for actin but increased strongly the flexibility of tropomyosin and kept its strands near the inner domain of actin. The ability of troponin to switch actin monomers "on" and "off" at high and low Ca2+, respectively, was increased, and the movement of tropomyosin towards the blocked position at low Ca2+ was inhibited, presumably causing higher Ca2+-sensitivity. The mutation decreased also the amount of the myosin heads which bound strongly to actin at high Ca2+ and increased the number of these heads at relaxation; this may contribute to contractures and muscle weakness.
Collapse
Affiliation(s)
- Yurii S Borovikov
- Institute of Cytology, Russian Academy of Sciences, 4 Tikhoretsky Avenue, St. Petersburg, 194064, Russia.
| | - Nikita A Rysev
- Institute of Cytology, Russian Academy of Sciences, 4 Tikhoretsky Avenue, St. Petersburg, 194064, Russia
| | - Olga E Karpicheva
- Institute of Cytology, Russian Academy of Sciences, 4 Tikhoretsky Avenue, St. Petersburg, 194064, Russia
| | - Vladimir V Sirenko
- Institute of Cytology, Russian Academy of Sciences, 4 Tikhoretsky Avenue, St. Petersburg, 194064, Russia
| | - Stanislava V Avrova
- Institute of Cytology, Russian Academy of Sciences, 4 Tikhoretsky Avenue, St. Petersburg, 194064, Russia
| | - Adam Piers
- Radcliffe Department of Medicine, University of Oxford, John Radcliffe Hospital, Oxford, OX3 9DU, United Kingdom
| | - Charles S Redwood
- Radcliffe Department of Medicine, University of Oxford, John Radcliffe Hospital, Oxford, OX3 9DU, United Kingdom
| |
Collapse
|
21
|
Borovikov YS, Simonyan AO, Karpicheva OE, Avrova SV, Rysev NA, Sirenko VV, Piers A, Redwood CS. The reason for a high Ca 2+-sensitivity associated with Arg91Gly substitution in TPM2 gene is the abnormal behavior and high flexibility of tropomyosin during the ATPase cycle. Biochem Biophys Res Commun 2017; 494:681-686. [PMID: 29097206 DOI: 10.1016/j.bbrc.2017.10.161] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2017] [Accepted: 10/29/2017] [Indexed: 12/19/2022]
Abstract
Substitution of Arg for Gly residue in 91th position in β-tropomyosin caused by a point mutation in TPM2 gene is associated with distal arthrogryposis, characterized by a high Ca2+-sensitivity of myofilament and contracture syndrome. To understand the mechanisms of this defect, we studied multistep changes in mobility and spatial arrangement of tropomyosin, actin and myosin heads during the ATPase cycle in reconstituted ghost fibres, using the polarized fluorescence microscopy. The mutation was shown to markedly decrease the bending stiffness of β-tropomyosin in the thin filaments. In the absence of the myosin heads the mutation did not alter the ability of troponin to shift tropomyosin to the blocked position and to switch actin monomers off at low Ca2+. During the ATPase cycle the movement of the mutant tropomyosin is restrained, it is located near the open position, which allows strong binding of the myosin heads to actin even at low Ca2+. This may be the reason for both high Ca2+-sensitivity and contractures associated with the Arg91Gly mutation. The use of reagents that decrease the Ca2+sensitivity of the troponin complex may not be appropriate to restore muscle function in patients with this mutation.
Collapse
Affiliation(s)
- Yurii S Borovikov
- Institute of Cytology, Russian Academy of Sciences, 4 Tikhoretsky Avenue, St. Petersburg 194064, Russia.
| | - Armen O Simonyan
- Institute of Cytology, Russian Academy of Sciences, 4 Tikhoretsky Avenue, St. Petersburg 194064, Russia
| | - Olga E Karpicheva
- Institute of Cytology, Russian Academy of Sciences, 4 Tikhoretsky Avenue, St. Petersburg 194064, Russia
| | - Stanislava V Avrova
- Institute of Cytology, Russian Academy of Sciences, 4 Tikhoretsky Avenue, St. Petersburg 194064, Russia
| | - Nikita A Rysev
- Institute of Cytology, Russian Academy of Sciences, 4 Tikhoretsky Avenue, St. Petersburg 194064, Russia
| | - Vladimir V Sirenko
- Institute of Cytology, Russian Academy of Sciences, 4 Tikhoretsky Avenue, St. Petersburg 194064, Russia
| | - Adam Piers
- Radcliffe Department of Medicine, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DU, United Kingdom
| | - Charles S Redwood
- Radcliffe Department of Medicine, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DU, United Kingdom
| |
Collapse
|
22
|
Karpicheva OE, Sirenko VV, Rysev NA, Simonyan AO, Borys D, Moraczewska J, Borovikov YS. Deviations in conformational rearrangements of thin filaments and myosin caused by the Ala155Thr substitution in hydrophobic core of tropomyosin. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2017; 1865:1790-1799. [PMID: 28939420 DOI: 10.1016/j.bbapap.2017.09.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2017] [Revised: 09/14/2017] [Accepted: 09/18/2017] [Indexed: 12/28/2022]
Abstract
Effects of the Ala155Thr substitution in hydrophobic core of tropomyosin Tpm1.1 on conformational rearrangements of the components of the contractile system (Tpm1.1, actin and myosin heads) were studied by polarized fluorimetry technique at different stages of the actomyosin ATPase cycle. The proteins were labelled by fluorescent probes and incorporated into ghost muscle fibres. The substitution violated the blocked and closed states of thin filaments stimulating abnormal displacement of tropomyosin to the inner domains of actin, switching actin on and increasing the relative number of the myosin heads in strong-binding state. Furthermore, the mutant tropomyosin disrupted the major function of troponin to alter the distribution of the different functional states of thin filaments. At low Ca2+ troponin did not effectively switch thin filament off and the myosin head lost the ability to drive the spatial arrangement of the mutant tropomyosin. The information about tropomyosin flexibility obtained from the fluorescent probes at Cys190 indicates that this tropomyosin is generally more rigid, that obviously prevents tropomyosin to bend and adopt the appropriate conformation required for proper regulation.
Collapse
Affiliation(s)
- Olga E Karpicheva
- Laboratory of Mechanisms of Cell Motility, Institute of Cytology, Russian Academy of Sciences, 4 Tikhoretsky Av., 194064 St Petersburg, Russia
| | - Vladimir V Sirenko
- Laboratory of Mechanisms of Cell Motility, Institute of Cytology, Russian Academy of Sciences, 4 Tikhoretsky Av., 194064 St Petersburg, Russia
| | - Nikita A Rysev
- Laboratory of Mechanisms of Cell Motility, Institute of Cytology, Russian Academy of Sciences, 4 Tikhoretsky Av., 194064 St Petersburg, Russia
| | - Armen O Simonyan
- Laboratory of Mechanisms of Cell Motility, Institute of Cytology, Russian Academy of Sciences, 4 Tikhoretsky Av., 194064 St Petersburg, Russia; Saint Petersburg State University, 7/9 Universitetskaya nab, 199034 St Petersburg, Russia
| | - Danuta Borys
- Department of Biochemistry and Cell Biology, Faculty of Natural Sciences, Kazimierz Wielki University in Bydgoszcz, 12 Ks. J. Poniatowski St., 85-671 Bydgoszcz, Poland
| | - Joanna Moraczewska
- Department of Biochemistry and Cell Biology, Faculty of Natural Sciences, Kazimierz Wielki University in Bydgoszcz, 12 Ks. J. Poniatowski St., 85-671 Bydgoszcz, Poland
| | - Yurii S Borovikov
- Laboratory of Mechanisms of Cell Motility, Institute of Cytology, Russian Academy of Sciences, 4 Tikhoretsky Av., 194064 St Petersburg, Russia.
| |
Collapse
|
23
|
He Y, Song M, Zhang Y, Li X, Song J, Zhang Y, Yu Y. Whole-genome regulation analysis of histone H3 lysin 27 trimethylation in subclinical mastitis cows infected by Staphylococcus aureus. BMC Genomics 2016; 17:565. [PMID: 27503467 PMCID: PMC4977872 DOI: 10.1186/s12864-016-2947-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2015] [Accepted: 07/18/2016] [Indexed: 11/15/2022] Open
Abstract
Background S. aureus is one of the major etiological agents causing bovine subclinical mastitis. The regulatory effects of H3K27me3 on gene expression in subclinical S. aureus mastitis cows are unknown. This study aimed to profile genome-wide transcriptional changes regulated by H3K27me3 in bovine lymphocytes applied in subclinical S. aureus mastitis cows and healthy controls. Results A total of 61 differentially expressed genes (DEGs) were detected in subclinical S. aureus mastitis cows compared to the healthy controls, of which 25 DEGs are up-regulated and the rest are down-regulated genes in subclinical S.aureus mastitis cows. The up-regulated genes are mainly involved in the Jak-STAT signaling pathway, cytokine-cytokine receptor interaction, and T cell receptor-signaling pathway, while the down-regulated genes are related to metabolism pathways. Combination analysis of histone methylation and gene expression revealed that H3K27 trimethylation levels in silent genes were higher in subclinical S. aureus mastitis cattle than in healthy cows. The key regions of H3K27me3 target genes related to subclinical S. aureus mastitis were the upstream 2 kb regions of the DEGs relative to transcription start site (TSS). Conclusions The current study provides a novel insight into the interaction between S. aureus and lymphocytes in lactating cows by histone H3 methylation regulation. The differentially expressed genes in bovine lymphocytes regulated by H3K27me3 on upstream 2 kb regions (IL10, PTX3 and etc.) may relate to S. aureus mastitis susceptibility and could be considered as key candidate genes for anti- S. aureus mastitis study and breeding. Electronic supplementary material The online version of this article (doi:10.1186/s12864-016-2947-0) contains supplementary material, which is available to authorized users.
Collapse
Affiliation(s)
- Yanghua He
- Key Laboratory of Animal Genetics, Breeding and Reproduction, Ministry of Agriculture, National Engineering Laboratory for Animal Breeding, College of Animal Science and Technology, China Agricultural University, Beijing, 100193, People's Republic of China.,Department of Animal & Avian Sciences, University of Maryland, College Park, MD, 20742, USA
| | - Minyan Song
- Key Laboratory of Animal Genetics, Breeding and Reproduction, Ministry of Agriculture, National Engineering Laboratory for Animal Breeding, College of Animal Science and Technology, China Agricultural University, Beijing, 100193, People's Republic of China
| | - Yi Zhang
- Key Laboratory of Animal Genetics, Breeding and Reproduction, Ministry of Agriculture, National Engineering Laboratory for Animal Breeding, College of Animal Science and Technology, China Agricultural University, Beijing, 100193, People's Republic of China
| | - Xizhi Li
- Beijing Sanyuan Breeding Technology Co. Ltd., Capital Agribusiness Group, Beijing, China
| | - Jiuzhou Song
- Department of Animal & Avian Sciences, University of Maryland, College Park, MD, 20742, USA
| | - Yuan Zhang
- Key Laboratory of Animal Genetics, Breeding and Reproduction, Ministry of Agriculture, National Engineering Laboratory for Animal Breeding, College of Animal Science and Technology, China Agricultural University, Beijing, 100193, People's Republic of China
| | - Ying Yu
- Key Laboratory of Animal Genetics, Breeding and Reproduction, Ministry of Agriculture, National Engineering Laboratory for Animal Breeding, College of Animal Science and Technology, China Agricultural University, Beijing, 100193, People's Republic of China.
| |
Collapse
|
24
|
Robaszkiewicz K, Ostrowska Z, Marchlewicz K, Moraczewska J. Tropomyosin isoforms differentially modulate the regulation of actin filament polymerization and depolymerization by cofilins. FEBS J 2015; 283:723-37. [DOI: 10.1111/febs.13626] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2015] [Revised: 11/30/2015] [Accepted: 12/10/2015] [Indexed: 12/11/2022]
Affiliation(s)
- Katarzyna Robaszkiewicz
- Department of Biochemistry and Cell Biology; Faculty of Natural Sciences; Kazimierz Wielki University in Bydgoszcz; Poland
| | - Zofia Ostrowska
- Department of Biochemistry and Cell Biology; Faculty of Natural Sciences; Kazimierz Wielki University in Bydgoszcz; Poland
| | - Kamila Marchlewicz
- Department of Biochemistry and Cell Biology; Faculty of Natural Sciences; Kazimierz Wielki University in Bydgoszcz; Poland
| | - Joanna Moraczewska
- Department of Biochemistry and Cell Biology; Faculty of Natural Sciences; Kazimierz Wielki University in Bydgoszcz; Poland
| |
Collapse
|
25
|
Yuen M, Cooper ST, Marston SB, Nowak KJ, McNamara E, Mokbel N, Ilkovski B, Ravenscroft G, Rendu J, de Winter JM, Klinge L, Beggs AH, North KN, Ottenheijm CAC, Clarke NF. Muscle weakness in TPM3-myopathy is due to reduced Ca2+-sensitivity and impaired acto-myosin cross-bridge cycling in slow fibres. Hum Mol Genet 2015; 24:6278-92. [PMID: 26307083 DOI: 10.1093/hmg/ddv334] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2015] [Accepted: 08/10/2015] [Indexed: 11/13/2022] Open
Abstract
Dominant mutations in TPM3, encoding α-tropomyosinslow, cause a congenital myopathy characterized by generalized muscle weakness. Here, we used a multidisciplinary approach to investigate the mechanism of muscle dysfunction in 12 TPM3-myopathy patients. We confirm that slow myofibre hypotrophy is a diagnostic hallmark of TPM3-myopathy, and is commonly accompanied by skewing of fibre-type ratios (either slow or fast fibre predominance). Patient muscle contained normal ratios of the three tropomyosin isoforms and normal fibre-type expression of myosins and troponins. Using 2D-PAGE, we demonstrate that mutant α-tropomyosinslow was expressed, suggesting muscle dysfunction is due to a dominant-negative effect of mutant protein on muscle contraction. Molecular modelling suggested mutant α-tropomyosinslow likely impacts actin-tropomyosin interactions and, indeed, co-sedimentation assays showed reduced binding of mutant α-tropomyosinslow (R168C) to filamentous actin. Single fibre contractility studies of patient myofibres revealed marked slow myofibre specific abnormalities. At saturating [Ca(2+)] (pCa 4.5), patient slow fibres produced only 63% of the contractile force produced in control slow fibres and had reduced acto-myosin cross-bridge cycling kinetics. Importantly, due to reduced Ca(2+)-sensitivity, at sub-saturating [Ca(2+)] (pCa 6, levels typically released during in vivo contraction) patient slow fibres produced only 26% of the force generated by control slow fibres. Thus, weakness in TPM3-myopathy patients can be directly attributed to reduced slow fibre force at physiological [Ca(2+)], and impaired acto-myosin cross-bridge cycling kinetics. Fast myofibres are spared; however, they appear to be unable to compensate for slow fibre dysfunction. Abnormal Ca(2+)-sensitivity in TPM3-myopathy patients suggests Ca(2+)-sensitizing drugs may represent a useful treatment for this condition.
Collapse
Affiliation(s)
- Michaela Yuen
- Institute for Neuroscience and Muscle Research, The Children's Hospital at Westmead, Westmead, Australia, Discipline of Paediatrics and Child Health, University of Sydney, Sydney, Australia,
| | - Sandra T Cooper
- Institute for Neuroscience and Muscle Research, The Children's Hospital at Westmead, Westmead, Australia, Discipline of Paediatrics and Child Health, University of Sydney, Sydney, Australia
| | - Steve B Marston
- National Heart and Lung Institute, Imperial College London, London, UK
| | - Kristen J Nowak
- Harry Perkins Institute of Medical Research and the Centre for Medical Research, University of Western Australia, Nedlands, Australia
| | - Elyshia McNamara
- Harry Perkins Institute of Medical Research and the Centre for Medical Research, University of Western Australia, Nedlands, Australia
| | - Nancy Mokbel
- Institute for Neuroscience and Muscle Research, The Children's Hospital at Westmead, Westmead, Australia, Faculty of Health Sciences, St. George Health Complex, The University of Balamand, Beirut, Lebanon
| | - Biljana Ilkovski
- Institute for Neuroscience and Muscle Research, The Children's Hospital at Westmead, Westmead, Australia
| | - Gianina Ravenscroft
- Harry Perkins Institute of Medical Research and the Centre for Medical Research, University of Western Australia, Nedlands, Australia
| | - John Rendu
- Département de Biochimie Toxicologie et Pharmacologie, Département de Biochimie Génétique et Moléculaire, Centre Hospitalier Universitaire de Grenoble, Grenoble, France
| | - Josine M de Winter
- Department of Physiology, Institute for Cardiovascular Research, VU University Medical Center, Amsterdam, The Netherlands
| | - Lars Klinge
- Department of Pediatrics and Adolescent Medicine, Division of Pediatric Neurology, Faculty of Medicine, Georg August University, Göttingen, Germany
| | - Alan H Beggs
- Division of Genetics and Genomics, The Manton Center for Orphan Disease Research, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - Kathryn N North
- Institute for Neuroscience and Muscle Research, The Children's Hospital at Westmead, Westmead, Australia, Discipline of Paediatrics and Child Health, University of Sydney, Sydney, Australia, Murdoch Children's Research Institute, the Royal Children's Hospital, Parkville, Australia and Department of Paediatrics, University of Melbourne, Melbourne, Australia
| | - Coen A C Ottenheijm
- Department of Physiology, Institute for Cardiovascular Research, VU University Medical Center, Amsterdam, The Netherlands
| | - Nigel F Clarke
- Institute for Neuroscience and Muscle Research, The Children's Hospital at Westmead, Westmead, Australia, Discipline of Paediatrics and Child Health, University of Sydney, Sydney, Australia
| |
Collapse
|
26
|
Robaszkiewicz K, Ostrowska Z, Cyranka-Czaja A, Moraczewska J. Impaired tropomyosin-troponin interactions reduce activation of the actin thin filament. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2015; 1854:381-90. [PMID: 25603119 DOI: 10.1016/j.bbapap.2015.01.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2014] [Revised: 01/09/2015] [Accepted: 01/13/2015] [Indexed: 01/23/2023]
Abstract
Tropomyosin and troponin are bound to the actin filament to control the contraction of striated muscle in the Ca-dependent manner. The interactions between both regulatory proteins important for the regulation process are not fully understood. To gain more insight into the mechanisms of the thin filament regulation by skeletal α-tropomyosin and troponin, we analyzed effects of seven myopathy-related substitutions: Leu99Met, Ala155Thr, Arg167Gly, Arg167Cys, Arg167His, Lys168Glu, and Arg244Gly. All substitutions reduced Ca-dependent activation of the actomyosin ATPase. The effects of mutations in Arg167 and Lys168 were the most severe. The amino acid substitutions did not significantly affect troponin binding to the whole filament, but reduced 1.2-2.8 fold the affinity of troponin to tropomyosin alone. The excimer fluorescence of N-(1-pyrene)iodoacetamide, a probe attached to the central Cys190, demonstrated that substitutions located near the troponin core domain-binding region strongly affected conformational changes accompanying the tropomyosin-troponin interactions. The thermal stability of all tropomyosin mutants was lower than the stability of the wild type tropomyosin, with TM reduced by 5.3-8.5°C. Together the analyses demonstrated that the myopathy-causing mutations affected tropomyosin structure and led to changes in interactions between tropomyosin and troponin, which impaired the transition of the thin filament from the inactive off to the active on state.
Collapse
Affiliation(s)
- Katarzyna Robaszkiewicz
- Department of Biochemistry and Cell Biology, Faculty of Natural Sciences, Kazimierz Wielki University in Bydgoszcz, Chodkiewicz 30, Str., 85-064 Bydgoszcz, Poland
| | - Zofia Ostrowska
- Department of Biochemistry and Cell Biology, Faculty of Natural Sciences, Kazimierz Wielki University in Bydgoszcz, Chodkiewicz 30, Str., 85-064 Bydgoszcz, Poland
| | | | - Joanna Moraczewska
- Department of Biochemistry and Cell Biology, Faculty of Natural Sciences, Kazimierz Wielki University in Bydgoszcz, Chodkiewicz 30, Str., 85-064 Bydgoszcz, Poland.
| |
Collapse
|
27
|
Abstract
Nemaline myopathy (NM) is a genetically and clinically heterogeneous muscle disorder, defined by the presence of characteristic nemaline bodies on muscle biopsy. The disease has a wide spectrum of phenotypes, ranging from forms with neonatal onset and fatal outcome to asymptomatic forms. The neonatal form is severe and usually fatal. The clinical variability, with differing age of onset and severity of symptoms makes the diagnosis difficult during infancy. There is no curative treatment. L-tyrosine may prevent aspiration by reducing pharyngeal secretions and drooling. Most of the patients die from respiratory and cardiac failure. This article discusses a newborn infant who presented with generalized weakness and respiratory failure. Partial response to L-tyrosine treatment was noted. The case is worth presenting to remind clinicians of congenital myopathies in the differential diagnosis of floppy infant during neonatal period and to emphasize the importance of muscle biopsy in diagnosis.
Collapse
|
28
|
Lycans RM, Higgins CB, Tanner MS, Blough ER, Day BS. Plasma treatment of PDMS for applications of in vitro motility assays. Colloids Surf B Biointerfaces 2013; 116:687-94. [PMID: 24309136 DOI: 10.1016/j.colsurfb.2013.11.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2013] [Revised: 11/06/2013] [Accepted: 11/07/2013] [Indexed: 12/28/2022]
Abstract
In vitro motility assays are readily used to simplify the complex environments within the cell and in muscle tissue. These assays have afforded considerable insight into the fundamentals of their underlying biophysics, interactions with cargo, intracellular regulation, and motor cooperation/competition. Extension of the standard in vitro motility assay into a more automated and cost-effective fluidic design while providing availability to the scientific community without expertise in lithographic fabrication is critical for the continued advancement of the field. In this work, we utilized a standard plasma cleaner to oxidize the widely prevalent material polydimethylsiloxane (PDMS) to create flow cells that could be used for in vitro motility assays. Our analysis indicated that a 40 min pre-treatment of the PDMS with plasma exposure resulted in optimal bundle motility. This finding was attributed to the condition at which the least amount of oxygen permeates the PDMS slab, enters the motility buffer, and oxidizes the motor proteins. Based on these findings, we developed a method for constructing microfluidic devices from glass and plasma-treated PDMS molds in which motility could be observed.
Collapse
Affiliation(s)
- Rebecca M Lycans
- Department of Chemistry, Marshall University, Huntington, WV 25755, United States
| | - Catherine B Higgins
- Department of Chemistry, Marshall University, Huntington, WV 25755, United States
| | - Michael S Tanner
- Department of Chemistry, Marshall University, Huntington, WV 25755, United States
| | - Eric R Blough
- School of Pharmacy, Marshall University, Huntington, WV 25755, United States; Center for Diagnostic Nanosystems, Marshall University, Huntington, WV 25755, United States.
| | - B Scott Day
- Department of Chemistry, Marshall University, Huntington, WV 25755, United States; Center for Diagnostic Nanosystems, Marshall University, Huntington, WV 25755, United States.
| |
Collapse
|
29
|
Śliwińska M, Moraczewska J. Structural differences between C-terminal regions of tropomyosin isoforms. PeerJ 2013; 1:e181. [PMID: 24167776 PMCID: PMC3807590 DOI: 10.7717/peerj.181] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2013] [Accepted: 09/26/2013] [Indexed: 12/04/2022] Open
Abstract
Tropomyosins are actin-binding regulatory proteins which overlap end-to-end along the filament. High resolution structures of the overlap regions were determined for muscle and non-muscle tropomyosins in the absence of actin. Conformations of the junction regions bound to actin are unknown. In this work, orientation of the overlap on actin alone and on actin–myosin complex was evaluated by measuring FRET distances between a donor (AEDANS) attached to tropomyosin and an acceptor (DABMI) bound to actin’s Cys374. Donor was attached to the Cys residue introduced by site-directed mutagenesis near the C-terminal half of the overlap. The recombinant alpha-tropomyosin isoforms used in this study – skeletal muscle skTM, non-muscle TM2 and TM5a, and chimeric TM1b9a had various amino acid sequences of the N- and C-termini involved in the end-to-end overlap. The donor-acceptor distances calculated for each isoform varied between 36.4 Å and 48.1 Å. Rigor binding of myosin S1 increased the apparent FRET distances of skTM and TM2, but decreased the distances separating TM5a and TM1b9a from actin. The results show that isoform-specific sequences of the end-to-end overlaps determine orientations and dynamics of tropomyosin isoforms on actin. This can be important for specificity of tropomyosin in the regulation of actin filament diverse functions.
Collapse
Affiliation(s)
| | - Joanna Moraczewska
- Institute of Experimental Biology, Kazimierz Wielki University, Bydgoszcz, Poland
| |
Collapse
|
30
|
Combined cap disease and nemaline myopathy in the same patient caused by an autosomal dominant mutation in the TPM3 gene. Neuromuscul Disord 2013; 23:992-7. [PMID: 24095155 DOI: 10.1016/j.nmd.2013.07.003] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2013] [Revised: 07/02/2013] [Accepted: 07/09/2013] [Indexed: 11/23/2022]
Abstract
The slow α-tropomyosin gene (TPM3) has been associated with three distinct histological entities: nemaline myopathy (NM, NEM1), congenital fibre-type disproportion (CFTD), and cap disease (CD). Here we describe a patient presenting an early-onset congenital myopathy associated with a combination of well separated cap structures and nemaline bodies in his muscle biopsy. Exome sequencing analysis allowed us to identify a de novo missense mutation in the TPM3 gene. Our study confirms the extreme variability of morphological findings in TPM3-related myopathies, and proves that cap and nemaline bodies are two sides of the same 'coin'.
Collapse
|
31
|
Jurewicz E, Ostrowska Z, Jozwiak J, Redowicz MJ, Lesniak W, Moraczewska J, Filipek A. CacyBP/SIP as a novel modulator of the thin filament. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2012; 1833:761-6. [PMID: 23266554 DOI: 10.1016/j.bbamcr.2012.12.010] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 07/31/2012] [Revised: 12/13/2012] [Accepted: 12/14/2012] [Indexed: 01/21/2023]
Abstract
The CacyBP/SIP protein interacts with several targets, including actin. Since the majority of actin filaments are associated with tropomyosin, in this work we characterized binding of CacyBP/SIP to the actin-tropomyosin complex and examined the effects of CacyBP/SIP on actin filament functions. By using reconstituted filaments composed of actin and AEDANS-labeled tropomyosin, we observed that binding of CacyBP/SIP caused an increase in tropomyosin fluorescence intensity indicating the occurrence of conformational changes within the filament. We also found that CacyBP/SIP bound directly to tropomyosin and that these proteins did not compete with each other for binding to actin. Electron microscopy showed that in the absence of tropomyosin CacyBP/SIP destabilized actin filaments, but tropomyosin reversed this effect. Actin-activated myosin S1 ATPase activity assays, performed using a colorimetric method, indicated that CacyBP/SIP reduced ATPase activity and that the presence of tropomyosin enhanced this inhibitory effect. Thus, our results suggest that CacyBP/SIP, through its interaction with both actin and tropomyosin, regulates the organization and functional properties of the thin filament.
Collapse
|