scholarly journals Myofibre Hyper-Contractility in Horses Expressing the Myosin Heavy Chain Myopathy Mutation, MYH1E321G

Cells ◽  
2021 ◽  
Vol 10 (12) ◽  
pp. 3428
Author(s):  
Julien Ochala ◽  
Carrie J. Finno ◽  
Stephanie J. Valberg
Keyword(s):  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Clinical Signs ◽  
Force Production ◽  
Cellular Mechanisms ◽  
Head Region ◽  
Muscle Disorders ◽  
Heavy Chains ◽  
Genes Encoding ◽  
Skeletal Myosin

Myosinopathies are defined as a group of muscle disorders characterized by mutations in genes encoding myosin heavy chains. Their exact molecular and cellular mechanisms remain unclear. In the present study, we have focused our attention on a MYH1-related E321G amino acid substitution within the head region of the type IIx skeletal myosin heavy chain, associated with clinical signs of atrophy, inflammation and/or profound rhabdomyolysis, known as equine myosin heavy chain myopathy. We performed Mant-ATP chase experiments together with force measurements on isolated IIx myofibres from control horses (MYH1E321G−/−) and Quarter Horses homozygous (MYH1E321G+/+) or heterozygous (MYH1E321G+/−) for the E321G mutation. The single residue replacement did not affect the relaxed conformations of myosin molecules. Nevertheless, it significantly increased its active behaviour as proven by the higher maximal force production and Ca2+ sensitivity for MYH1E321G+/+ in comparison with MYH1E321G+/− and MYH1E321G−/− horses. Altogether, these findings indicate that, in the presence of the E321G mutation, a molecular and cellular hyper-contractile phenotype occurs which could contribute to the development of the myosin heavy chain myopathy.

scholarly journals Qualitative analysis of skeletal myosin as substrate of Ca2+-activated neutral protease: comparison of filamentous and soluble, native, and L2-deficient myosin.

1984 ◽  
Vol 99 (6) ◽  
pp. 2297-2308 ◽  
Author(s):  
S M Pemrick ◽  
R C Grebenau
Keyword(s):  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Prolonged Exposure ◽  
Neutral Protease ◽  
Cleavage Sites ◽  
Head Region ◽  
Molecular Weights ◽  
Hydrolytic Activities ◽  
Skeletal Myosin ◽  
High Concentrations

Ca2+ -activated neutral protease (CAF) was capable of degrading myosin over a 200-fold range of protease concentrations. CAF selected the heavy chain of myosin, although either prolonged exposure to or high concentrations of the protease degraded the L1, but not the L2 or L3, light chains of myosin. The following results indicated that during the first hour of digestion, under conditions where native myosin was the substrate, CAF selected for the "head" region of the myosin heavy chain: (a) large heavy chain fragments of identical molecular weight were produced from filamentous and from soluble myosin; (b) light meromyosin was not a substrate; (c) agents known to bind to the head of myosin (actin, MgATP, and L2) had both a qualitative and quantitative effect on degradation; and (d) similar cleavage sites could be demonstrated for myosin and for heavy meromyosin (HMM) despite the fact that HMM was a much poorer substrate than myosin. This observation is interpreted as an indication that the conformation of myosin heavy chain is altered in the preparation of HMM. The principal cleavage sites on the heavy chain of myosin were 20,000, 35,000 and 50,000 D from the N-terminus, producing large fragments with molecular weights of 180,000, 165,000, and 150,000 which comprised a "nicked" species of myosin. This nicked species retained both normal solubility properties and normal hydrolytic activities. For this reason, it is concluded that "nicked myosin" is an important pathophysiological species.

scholarly journals Myosins and pathology: genetics and biology.

2002 ◽  
Vol 49 (4) ◽  
pp. 789-804 ◽  
Author(s):  
Maria Jolanta Redowicz
Keyword(s):  
Hypertrophic Cardiomyopathy ◽  
Myosin Heavy Chain ◽  
Inner Ear ◽  
Heavy Chain ◽  
Hair Cells ◽  
Familial Hypertrophic Cardiomyopathy ◽  
Light Chains ◽  
Myosin Isoforms ◽  
Cardiac Myosin ◽  
Genes Encoding

This article summarizes current knowledge on the genetics and possible molecular mechanisms of Human pathologies resulted from mutations within the genes encoding several myosin isoforms. Mutations within the genes encoding some myosin isoforms have been found to be responsible for blindness (myosins III and VIIA), deafness (myosins I, IIA, IIIA, VI, VIIA and XV) and familial hypertrophic cardiomyopathy (beta cardiac myosin heavy chain and both the regulatory and essential light chains). Myosin III localizes predominantly to photoreceptor cells and is proved to be engaged in the vision process in Drosophila. In the inner ear, myosin I is postulated to play a role as an adaptive motor in the tip links of stereocilia of hair cells, myosin IIA seems to be responsible for stabilizing the contacts between adjacent inner ear hair cells, myosin VI plays a role as an intracellular motor transporting membrane structures within the hair cells while myosin VIIA most probably participates in forming links between neighbouring stereocilia and myosin XV probably stabilizes the stereocilia structure. About 30% of patients with familial hypertrophic cardiomyopathy have mutations within the genes encoding the beta cardiac myosin heavy chain and both light chains that are grouped within the regions of myosin head crucial for its functions. The alterations lead to the destabilization of sarcomeres and to a decrease of the myosin ATPase activity and its ability to move actin filaments.

Molecular characterization of a developmentally regulated porcine skeletal myosin heavy chain gene and its 5′ regulatory region

1995 ◽  
Vol 108 (4) ◽  
pp. 1779-1789 ◽  
Author(s):  
K.C. Chang ◽  
K. Fernandes ◽  
M.J. Dauncey
Keyword(s):  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Transcriptional Start Site ◽  
Regulatory Region ◽  
Chain Gene ◽  
Specific Expression ◽  
Slow Fibre ◽  
Skeletal Myosin

Members of the myosin heavy chain (MyHC) gene family show developmental stage- and spatial-specificity of expression. We report on the characterization and identification of a porcine skeletal fast MyHC gene, including its corresponding 5′ end cDNA and 5′ regulatory region. This MyHC isoform was found exclusively in skeletal muscles from about the last quarter of gestation through to adulthood. Expression of this isoform was higher postnatally and its spatial distribution resembled a rosette cluster; each with a ring of fast fibres surrounding a central slow fibre. This rosette pattern was absent in the adult diaphragm but about 20% of the fibres continued to express this MyHC isoform. Further in vivo expression studies, in a variety of morphologically and functionally diverse muscles, showed that this particular skeletal MyHC isoform was expressed in fast oxidative-glycolytic fibres, suggesting that it was the equivalent of the fast IIA isoform. Two domains in the upstream regulatory region were found to confer differentiation-specific expression on C2 myotubes (−1007 to -828 and -455 to -101), based on in vitro transient expression assays using the chloramphenicol acetyltransferase (CAT) reporter gene. Interestingly, for high levels of CAT expression to occur, a 3′ region, extending from the transcriptional start site to part. of intron 2, must be present in all the DNA constructs used.

Isolation and localization of the skeletal myosin heavy chain 2X gene on pig chromosome 12q1.4-q1.5

1998 ◽  
Vol 9 (5) ◽  
pp. 412-413 ◽  
Author(s):  
Carla Zijlstra ◽  
Roberta Davoli ◽  
Luca Fontanesi ◽  
Paolo Zambonelli ◽  
Anneke A. Bosma ◽  
...  
Keyword(s):  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Skeletal Myosin

scholarly journals Organization of the human skeletal myosin heavy chain gene cluster.

1992 ◽  
Vol 89 (24) ◽  
pp. 12078-12082 ◽  
Author(s):  
S. J. Yoon ◽  
S. H. Seiler ◽  
R. Kucherlapati ◽  
L. Leinwand
Keyword(s):  
Myosin Heavy Chain ◽  
Gene Cluster ◽  
Heavy Chain ◽  
Chain Gene ◽  
Heavy Chain Gene ◽  
Myosin Heavy Chain Gene ◽  
Skeletal Myosin
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