Our recent work has identified a new state of myosin in relaxed muscle with a very slow ATP turnover rate, the """"""""super-relaxed state"""""""" (SRX). In skeletal muscle the SRX is proposed to play a role in determining thermogenesis by resting muscle. In cardiac ventricular muscle, where it has many similarities, but some important differences with the SRX in skeletal muscle, the SRX is proposed to play a cardio-protective role by efficiently de- creasing cardiac metabolism in times of stress. We have also shown that smooth muscle has a very stable SRX. Recent work has also demonstrated that in tarantula muscle the SRX has a very long duration, in agreement with previous EM data. The goal of the proposed research will be to determine the factors that modulate the SRX, particularly in skeletal, cardiac and smooth muscles. We have shown that the population of the SRX is modulated by RLC phosphorylation in fast skeletal muscle and in tarantula leg muscle. We will expand these studies to slow skeletal, cardiac and smooth muscles. Phosphorylation of myosin occurs in slow skeletal muscle;however its function remains unknown. The proposed research will explore a possible role in controlling the SRX and resting thermogenesis. In cardiac muscle, phosphorylation of myosin causes increased tension. Our recent work suggests that a role of the SRX in cardiac is to modulate tension, and we will explore the relationship between myosin phosphorylation, the population of the SRX and muscle tension. Observations in living, resting skeletal and cardiac muscle show that metabolism is dramatically decreased by fatigue and hypoxia. A high population of myosin in the SRX is a requirement for achieving the very low metabolic rate seen in resting skeletal muscle, and we propose also in cardiac. Thus we will explore the effect of conditions that mimic fatigue and hypoxia on the SRX. The studies will be extended to smooth muscle where phosphorylation also modulates function. These data will be complimented by structural studies of the SRX using EPR probes to monitor the structure of the thick filament and the conformation of the nucleotide pocket. Preliminary data suggest that nucleotide spin probes can report on the ordered structure of the thick filament. In collaboration with Roger Craig, spectroscopic probes will provide data that will be combined with EM visualization under identical conditions (phosphorylation, conditions of fatigue/hypoxia, etc.) to explore the structure of the SRX. These studies will vastly expand our very limited knowledge of this newly identified state of myosin. The studies will provide much of the fundamental biology whose understanding will be required to pursue our long-term goal, the development of the many obvious applications of the SRX for treating human health problems. Decreasing the population of the SRX in resting skeletal muscle could increase both muscle and whole body metabolism providing a new therapy for treating obesity and type 2 diabetes. Increasing the population of the SRX in resting and active cardiac muscle could lower the metabolic rate providing cardioprotection.

Public Health Relevance

We have recently discovered a new state of myosin in resting muscle, which has a very low rate for using its fuel, ATP. We will investigate the biological mechanisms that control the population and other properties of this state. Understanding these mechanisms and how to manipulate them in skeletal muscle will lead to new therapies for diabetes and obesity, and in cardiac muscle to new therapies for protecting the heart in times of stress.

Agency
National Institute of Health (NIH)
Institute
National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS)
Type
Research Project (R01)
Project #
1R01AR062279-01A1
Application #
8348651
Study Section
Skeletal Muscle and Exercise Physiology Study Section (SMEP)
Program Officer
Boyce, Amanda T
Project Start
2012-07-01
Project End
2017-04-30
Budget Start
2012-07-01
Budget End
2013-04-30
Support Year
1
Fiscal Year
2012
Total Cost
$504,236
Indirect Cost
$115,298
Name
Washington State University
Department
Engineering (All Types)
Type
Schools of Engineering
DUNS #
041485301
City
Pullman
State
WA
Country
United States
Zip Code
99164
Tolkatchev, Dmitri; Elnatan, Daniel; Nogara, Leonardo et al. (2018) Piperine, an alkaloid inhibiting the super-relaxed state of myosin, binds to the myosin regulatory light chain. Arch Biochem Biophys 659:75-84
Lee, Kyoung Hwan; Sulbarán, Guidenn; Yang, Shixin et al. (2018) Interacting-heads motif has been conserved as a mechanism of myosin II inhibition since before the origin of animals. Proc Natl Acad Sci U S A 115:E1991-E2000
Craig, Roger (2017) Molecular structure of muscle filaments determined by electron microscopy. Appl Microsc 47:226-232
Nogara, Leonardo; Naber, Nariman; Pate, Edward et al. (2016) Piperine's mitigation of obesity and diabetes can be explained by its up-regulation of the metabolic rate of resting muscle. Proc Natl Acad Sci U S A 113:13009-13014
Yang, Shixin; Woodhead, John L; Zhao, Fa-Qing et al. (2016) An approach to improve the resolution of helical filaments with a large axial rise and flexible subunits. J Struct Biol 193:45-54
Woodhead, John L; Craig, Roger (2015) Through Thick and Thin--Interfilament Communication in Muscle. Biophys J 109:665-7
Litvinov, Ivan V; Tetzlaff, Michael T; Rahme, Elham et al. (2015) Identification of geographic clustering and regions spared by cutaneous T-cell lymphoma in Texas using 2 distinct cancer registries. Cancer 121:1993-2003
Betz, Regina C; Petukhova, Lynn; Ripke, Stephan et al. (2015) Genome-wide meta-analysis in alopecia areata resolves HLA associations and reveals two new susceptibility loci. Nat Commun 6:5966
Wilson, Clyde; Naber, Nariman; Pate, Edward et al. (2014) The myosin inhibitor blebbistatin stabilizes the super-relaxed state in skeletal muscle. Biophys J 107:1637-46
Racki, Lisa R; Naber, Nariman; Pate, Ed et al. (2014) The histone H4 tail regulates the conformation of the ATP-binding pocket in the SNF2h chromatin remodeling enzyme. J Mol Biol 426:2034-44

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