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Shenkman BS, Tsaturyan AK, Vikhlyantsev IM, Kozlovskaya IB, Grigoriev AI. Molecular Mechanisms of Muscle Tone Impairment under Conditions of Real and Simulated Space Flight. Acta Naturae 2021; 13:85-97. [PMID: 34377559 PMCID: PMC8327152 DOI: 10.32607/actanaturae.10953] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Accepted: 08/04/2020] [Indexed: 01/08/2023] Open
Abstract
Kozlovskaya et al. [1] and Grigoriev et al. [2] showed that enormous loss of muscle stiffness (atonia) develops in humans under true (space flight) and simulated microgravity conditions as early as after the first days of exposure. This phenomenon is attributed to the inactivation of slow motor units and called reflectory atonia. However, a lot of evidence indicating that even isolated muscle or a single fiber possesses substantial stiffness was published at the end of the 20th century. This intrinsic stiffness is determined by the active component, i.e. the ability to form actin-myosin cross-bridges during muscle stretch and contraction, as well as by cytoskeletal and extracellular matrix proteins, capable of resisting muscle stretch. The main facts on intrinsic muscle stiffness under conditions of gravitational unloading are considered in this review. The data obtained in studies of humans under dry immersion and rodent hindlimb suspension is analyzed. The results and hypotheses regarding reduced probability of cross-bridge formation in an atrophying muscle due to increased interfilament spacing are described. The evidence of cytoskeletal protein (titin, nebulin, etc.) degradation during gravitational unloading is also discussed. The possible mechanisms underlying structural changes in skeletal muscle collagen and its role in reducing intrinsic muscle stiffness are presented. The molecular mechanisms of changes in intrinsic stiffness during space flight and simulated microgravity are reviewed.
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Affiliation(s)
- B. S. Shenkman
- State Scientific Center of Russian Federation – Institute of Biomedical Problems, Moscow, 123007 Russia
| | - A. K. Tsaturyan
- Lomonosov Moscow State University Research Institute of Mechanics, Moscow, 119192 Russia
| | - I. M. Vikhlyantsev
- Institute of Experimental and Theoretical Biophysics, Moscow Region, Pushchino, 142290 Russia
| | - I. B. Kozlovskaya
- State Scientific Center of Russian Federation – Institute of Biomedical Problems, Moscow, 123007 Russia
| | - A. I. Grigoriev
- State Scientific Center of Russian Federation – Institute of Biomedical Problems, Moscow, 123007 Russia
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2
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Pokusaev AS, Ogneva IV. A biophysical model of the contractile activity of muscle cells. Biophysics (Nagoya-shi) 2015. [DOI: 10.1134/s0006350915060202] [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] Open
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3
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Katzemich A, West RJH, Fukuzawa A, Sweeney ST, Gautel M, Sparrow J, Bullard B. Binding partners of the kinase domains in Drosophila obscurin and their effect on the structure of the flight muscle. J Cell Sci 2015; 128:3386-97. [PMID: 26251439 DOI: 10.1242/jcs.170639] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Accepted: 07/27/2015] [Indexed: 01/15/2023] Open
Abstract
Drosophila obscurin (Unc-89) is a titin-like protein in the M-line of the muscle sarcomere. Obscurin has two kinase domains near the C-terminus, both of which are predicted to be inactive. We have identified proteins binding to the kinase domains. Kinase domain 1 bound Bällchen (Ball, an active kinase), and both kinase domains 1 and 2 bound MASK (a 400-kDa protein with ankyrin repeats). Ball was present in the Z-disc and M-line of the indirect flight muscle (IFM) and was diffusely distributed in the sarcomere. MASK was present in both the M-line and the Z-disc. Reducing expression of Ball or MASK by siRNA resulted in abnormalities in the IFM, including missing M-lines and multiple Z-discs. Obscurin was still present, suggesting that the kinase domains act as a scaffold binding Ball and MASK. Unlike obscurin in vertebrate skeletal muscle, Drosophila obscurin is necessary for the correct assembly of the IFM sarcomere. We show that Ball and MASK act downstream of obscurin, and both are needed for development of a well defined M-line and Z-disc. The proteins have not previously been identified in Drosophila muscle.
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Affiliation(s)
- Anja Katzemich
- Department of Biology, University of York, York YO10 5DD, UK
| | - Ryan J H West
- Department of Biology, University of York, York YO10 5DD, UK
| | - Atsushi Fukuzawa
- King's College BHF Centre, Cardiovascular Division, London SE1 1UL, UK
| | - Sean T Sweeney
- Department of Biology, University of York, York YO10 5DD, UK
| | - Mathias Gautel
- King's College BHF Centre, Cardiovascular Division, London SE1 1UL, UK
| | - John Sparrow
- Department of Biology, University of York, York YO10 5DD, UK
| | - Belinda Bullard
- Department of Biology, University of York, York YO10 5DD, UK
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Caldwell TA, Sumner I, Wright NT. Mechanical dissociation of the M-band titin/obscurin complex is directionally dependent. FEBS Lett 2015; 589:1735-9. [PMID: 26001486 DOI: 10.1016/j.febslet.2015.05.023] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Revised: 05/08/2015] [Accepted: 05/11/2015] [Indexed: 11/29/2022]
Abstract
Titin and obscurin, two giant muscle proteins, bind to each other in an antiparallel Ig-Ig fashion at the M-band. This interaction must be able to withstand the mechanical strain that the M-band typically experiences and remain intact. The mechanical force on these domains is likely exerted along one of two axes: a longitudinal axis, resulting in a 'shearing' force, or a lateral axis, resulting in a 'peeling' force. Here we present molecular dynamics data suggesting that these forces result in distinct unraveling pathways of the titin/obscurin complex and that peeling the domains apart requires less work and force.
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Affiliation(s)
- Tracy A Caldwell
- Department of Chemistry and Biochemistry, James Madison University, 901 Carrier Dr., Harrisonburg, VA 22807, United States
| | - Isaiah Sumner
- Department of Chemistry and Biochemistry, James Madison University, 901 Carrier Dr., Harrisonburg, VA 22807, United States
| | - Nathan T Wright
- Department of Chemistry and Biochemistry, James Madison University, 901 Carrier Dr., Harrisonburg, VA 22807, United States.
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5
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Xiao S, Gräter F. Molecular basis of the mechanical hierarchy in myomesin dimers for sarcomere integrity. Biophys J 2015; 107:965-73. [PMID: 25140432 PMCID: PMC4142248 DOI: 10.1016/j.bpj.2014.06.043] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2014] [Revised: 05/26/2014] [Accepted: 06/16/2014] [Indexed: 01/08/2023] Open
Abstract
Myomesin is one of the most important structural molecules constructing the M-band in the force-generating unit of striated muscle, and a critical structural maintainer of the sarcomere. Using molecular dynamics simulations, we here dissect the mechanical properties of the structurally known building blocks of myomesin, namely α-helices, immunoglobulin (Ig) domains, and the dimer interface at myomesin's 13th Ig domain, covering the mechanically important C-terminal part of the molecule. We find the interdomain α-helices to be stabilized by the hydrophobic interface formed between the N-terminal half of these helices and adjacent Ig domains, and, interestingly, to show a rapid unfolding and refolding equilibrium especially under low axial forces up to ∼ 15 pN. These results support and yield atomic details for the notion of recent atomic-force microscopy experiments, namely, that the unique helices inserted between Ig domains in myomesin function as elastomers and force buffers. Our results also explain how the C-terminal dimer of two myomesin molecules is mechanically outperforming the helices and Ig domains in myomesin and elsewhere, explaining former experimental findings. This study provides a fresh view onto how myomesin integrates elastic helices, rigid immunoglobulin domains, and an extraordinarily resistant dimer into a molecular structure, to feature a mechanical hierarchy that represents a firm and yet extensible molecular anchor to guard the stability of the sarcomere.
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Affiliation(s)
- Senbo Xiao
- Heidelberg Institute for Theoretical Studies, Heidelberg, Germany
| | - Frauke Gräter
- Heidelberg Institute for Theoretical Studies, Heidelberg, Germany; Chinese Academy of Sciences-Max-Planck-Society Partner Institute and Key Laboratory for Computational Biology, Shanghai, China; Interdisciplinary Center for Scientific Computing, Heidelberg University, Heidelberg, Germany.
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6
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Smith DA. Electrostatic forces or structural scaffolding: What stabilizes the lattice spacing of relaxed skinned muscle fibers? J Theor Biol 2014; 355:53-60. [DOI: 10.1016/j.jtbi.2014.03.037] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2013] [Revised: 03/23/2014] [Accepted: 03/25/2014] [Indexed: 11/17/2022]
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7
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Biryukov NS, Ogneva IV. Interaction between muscle cell and external mechanical field: a model study. Biophysics (Nagoya-shi) 2013. [DOI: 10.1134/s0006350913030044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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Stahl SW, Puchner EM, Alexandrovich A, Gautel M, Gaub HE. A conditional gating mechanism assures the integrity of the molecular force-sensor titin kinase. Biophys J 2012; 101:1978-86. [PMID: 22004752 DOI: 10.1016/j.bpj.2011.09.027] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2011] [Revised: 08/11/2011] [Accepted: 09/06/2011] [Indexed: 12/16/2022] Open
Abstract
As more and more recent investigations point out, force plays an important role in cellular regulation mechanisms. Biological responses to mechanical stress are often based on force-induced conformational changes of single molecules. The force sensor, titin kinase, is involved in a signaling complex that regulates protein turnover and transcriptional adaptation in striated muscle. The structural architecture of such a force sensor determines its response to force and must assure both activity and mechanical integrity, which are prerequisites for its function. Here, we use single-molecule force-clamp spectroscopy to show that titin kinase is organized in such a way that the regulatory domains have to unfold before secondary structure elements that determine the overall fold and catalytic function. The stepwise unfolding over many barriers with a topologically determined sequence assures that the protein can react to force by conformational changes while maintaining its structural integrity.
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Affiliation(s)
- Stefan W Stahl
- Center for NanoScience, Ludwig-Maximilians-University Munich, Munich, Germany
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Voelkel T, Linke WA. Conformation-regulated mechanosensory control via titin domains in cardiac muscle. Pflugers Arch 2011; 462:143-54. [PMID: 21347754 PMCID: PMC3114084 DOI: 10.1007/s00424-011-0938-1] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2011] [Revised: 02/08/2011] [Accepted: 02/09/2011] [Indexed: 12/19/2022]
Abstract
The giant filamentous protein titin is ideally positioned in the muscle sarcomere to sense mechanical stimuli and transform them into biochemical signals, such as those triggering cardiac hypertrophy. In this review, we ponder the evidence for signaling hotspots along the titin filament involved in mechanosensory control mechanisms. On the way, we distinguish between stress and strain as triggers of mechanical signaling events at the cardiac sarcomere. Whereas the Z-disk and M-band regions of titin may be prominently involved in sensing mechanical stress, signaling hotspots within the elastic I-band titin segment may respond primarily to mechanical strain. Common to both stress and strain sensor elements is their regulation by conformational changes in protein domains.
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Affiliation(s)
- Tobias Voelkel
- Department of Cardiovascular Physiology, Institute of Physiology, Ruhr University Bochum, MA 3/56, 44780 Bochum, Germany
| | - Wolfgang A. Linke
- Department of Cardiovascular Physiology, Institute of Physiology, Ruhr University Bochum, MA 3/56, 44780 Bochum, Germany
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Gautel M. The sarcomeric cytoskeleton: who picks up the strain? Curr Opin Cell Biol 2010; 23:39-46. [PMID: 21190822 DOI: 10.1016/j.ceb.2010.12.001] [Citation(s) in RCA: 129] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2010] [Revised: 12/01/2010] [Accepted: 12/02/2010] [Indexed: 01/01/2023]
Abstract
In striated muscle sarcomeres, the contractile actin and myosin filaments are organised by a subset of specialised cytoskeletal proteins, the sarcomeric cytoskeleton. They include α-actinin, myomesin, and the giant proteins titin, obscurin and nebulin, which combine architectural, mechanical and signalling functions. Mechanics and signalling in the sarcomere appear tightly interdependent, but the exact contributions of the various sarcomeric cytoskeleton proteins to strain handling or signalling are only just emerging. General mechanisms of cytoskeletal mechanics and signalling may be gleaned from the sarcomere as a specialised actomyosin system. Recent work has led to insight into the interactions, structure, and mechanical stability of sarcomeric protein complexes that fulfil both structural and signalling roles.
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Affiliation(s)
- Mathias Gautel
- King's College London BHF Centre of Research Excellence, Cardiovascular Division and Randall Division for Cell and Molecular Biophysics, London SE1 1UL, United Kingdom.
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11
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Comparative biomechanics of thick filaments and thin filaments with functional consequences for muscle contraction. J Biomed Biotechnol 2010; 2010:473423. [PMID: 20625489 PMCID: PMC2896680 DOI: 10.1155/2010/473423] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2010] [Accepted: 03/26/2010] [Indexed: 02/02/2023] Open
Abstract
The scaffold of striated muscle is predominantly comprised of myosin and actin polymers known as thick filaments and thin filaments, respectively. The roles these filaments play in muscle contraction are well known, but the extent to which variations in filament mechanical properties influence muscle function is not fully understood. Here we review information on the material properties of thick filaments, thin filaments, and their primary constituents; we also discuss ways in which mechanical properties of filaments impact muscle performance.
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