The importance of subfragment 2 and C-terminus of myosin heavy chain for thick filament assembly in skeletal muscle cells

2014 ◽  
Vol 86 (4) ◽  
pp. 459-467 ◽  
Author(s):  
Koichi Ojima ◽  
Mika Oe ◽  
Ikuyo Nakajima ◽  
Masahiro Shibata ◽  
Susumu Muroya ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Muscle Cells ◽  
Thick Filament ◽  
Skeletal Muscle Cells ◽  
Filament Assembly ◽  
C Terminus

scholarly journals Mutated WWP1 Induces an Aberrant Expression of Myosin Heavy Chain Gene in C2C12 Skeletal Muscle Cells

2010 ◽  
Vol 47 (2) ◽  
pp. 115-119 ◽  
Author(s):  
Hirokazu Matsumoto ◽  
Yumi Inba ◽  
Shinji Sasazaki ◽  
Akira Fujiwara ◽  
Nobutsune Ichihara ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Muscle Cells ◽  
Skeletal Muscle Cells ◽  
Chain Gene ◽  
Heavy Chain Gene ◽  
Myosin Heavy Chain Gene ◽  
Aberrant Expression ◽  
C2c12 Skeletal Muscle Cells

IL-7 is expressed and secreted by human skeletal muscle cells

2010 ◽  
Vol 298 (4) ◽  
pp. C807-C816 ◽  
Author(s):  
Fred Haugen ◽  
Frode Norheim ◽  
Henrik Lian ◽  
Andreas J. Wensaas ◽  
Svein Dueland ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Myosin Heavy Chain ◽  
Real Time ◽  
Satellite Cells ◽  
Heavy Chain ◽  
Muscle Cells ◽  
Skeletal Muscle Cells ◽  
Rt Pcr ◽  
Human Myotubes

In addition to generating movement, skeletal muscle may have a function as a secretory organ. The aim of the present study was to identify novel proteins with signaling capabilities secreted from skeletal muscle cells. IL-7 was detected in media conditioned by primary cultures of human myotubes differentiated from satellite cells, and concentrations increased with incubation time. By immunoblotting and real-time RT-PCR IL-7 expression was confirmed at both protein and mRNA levels. Furthermore, with immunofluorescence and specific antisera, multinucleated myotubes were found to coexpress IL-7 and myosin heavy chain. During differentiation of human myotubes from satellite cells, IL-7 expression increased at mRNA and protein levels. In contrast, mRNA expression of the IL-7 receptor was 80% lower in myotubes compared with satellite cells. Incubations with recombinant IL-7 under differentiation conditions caused ∼35% reduction in mRNA for the terminal myogenic markers myosin heavy chain 2 (MYH2) and myogenin (MYOG), suggesting that IL-7 may act on satellite cells to inhibit development of the muscle fiber phenotype. Alternative routes of cell development were investigated, and IL-7 increased migration of satellite cells by 40% after 48 h in a Transwell system, whereas cell proliferation remained unchanged. In vivo, real-time RT-PCR analysis of musculus vastus lateralis ( n = 10) and musculus trapezius ( n = 7) biopsies taken from male individuals undergoing a strength training program demonstrated that after 11 wk mean IL-7 mRNA increased by threefold ( P = 0.01) and fourfold ( P = 0.04), respectively. In conclusion, we have demonstrated that IL-7 is a novel myokine regulated both in vitro and in vivo, and it may play a role in the regulation of muscle cell development.

scholarly journals Caenorhabditis elegans Unc-45 Is a Component of Muscle Thick Filaments and Colocalizes with Myosin Heavy Chain B, but Not Myosin Heavy Chain a

2000 ◽  
Vol 148 (2) ◽  
pp. 375-384 ◽  
Author(s):  
Wanyuan Ao ◽  
Dave Pilgrim
Keyword(s):  
Caenorhabditis Elegans ◽  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Body Wall ◽  
Thick Filament ◽  
The Body ◽  
Temperature Sensitive ◽  
Filament Assembly ◽  
Thick Filaments ◽  
Body Wall Muscles

In the nematode Caenorhabditis elegans, animals mutant in the gene encoding the protein product of the unc-45 gene (UNC-45) have disorganized muscle thick filaments in body wall muscles. Although UNC-45 contains tetratricopeptide repeats (TPR) as well as limited similarity to fungal proteins, no biochemical role has yet been found. UNC-45 reporters are expressed exclusively in muscle cells, and a functional reporter fusion is localized in the body wall muscles in a pattern identical to thick filament A-bands. UNC-45 colocalizes with myosin heavy chain (MHC) B in wild-type worms as well as in temperature-sensitive (ts) unc-45 mutants, but not in a mutant in which MHC B is absent. Surprisingly, UNC-45 localization is also not seen in MHC B mutants, in which the level of MHC A is increased, resulting in near-normal muscle thick filament structure. Thus, filament assembly can be independent of UNC-45. UNC-45 shows a localization pattern identical to and dependent on MHC B and a function that appears to be MHC B–dependent. We propose that UNC-45 is a peripheral component of muscle thick filaments due to its localization with MHC B. The role of UNC-45 in thick filament assembly seems restricted to a cofactor for assembly or stabilization of MHC B.

scholarly journals Adiponectin Upregulates Ferritin Heavy Chain in Skeletal Muscle Cells

Diabetes ◽  
2008 ◽  
Vol 58 (1) ◽  
pp. 61-70 ◽  
Author(s):  
Y. Ikegami ◽  
K. Inukai ◽  
K. Imai ◽  
Y. Sakamoto ◽  
H. Katagiri ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Heavy Chain ◽  
Muscle Cells ◽  
Skeletal Muscle Cells ◽  
Ferritin Heavy Chain

scholarly journals Dynamics of myosin replacement in skeletal muscle cells

2015 ◽  
Vol 309 (10) ◽  
pp. C669-C679 ◽  
Author(s):  
Koichi Ojima ◽  
Emi Ichimura ◽  
Yuya Yasukawa ◽  
Jun-ichi Wakamatsu ◽  
Takanori Nishimura
Keyword(s):  
Skeletal Muscle ◽  
Protein Synthesis ◽  
Dynamic Equilibrium ◽  
Muscle Cells ◽  
Thick Filament ◽  
Skeletal Muscle Cells ◽  
Myosin Molecule ◽  
Thick Filaments ◽  
Cultured Myotubes ◽  
Exchange Unit

Highly organized thick filaments in skeletal muscle cells are formed from ∼300 myosin molecules. Each thick-filament-associated myosin molecule is thought to be constantly exchanged. However, the mechanism of myosin replacement remains unclear, as does the source of myosin for substitution. Here, we investigated the dynamics of myosin exchange in the myofibrils of cultured myotubes by fluorescent recovery after photobleaching and found that myofibrillar myosin is actively replaced with an exchange half-life of ∼3 h. Myosin replacement was not disrupted by the absence of the microtubule system or by actomyosin interactions, suggesting that known cytoskeletal systems are dispensable for myosin substitution. Intriguingly, myosin replacement was independent of myosin binding protein C, which links myosin molecules together to form thick filaments. This implies that an individual myosin molecule rather than a thick filament functions as an exchange unit. Furthermore, the myosin substitution rate was decreased by the inhibition of protein synthesis, suggesting that newly synthesized myosin, as well as preexisting cytosolic myosin, contributes to myosin replacement in myofibrils. Notably, incorporation and release of myosin occurred simultaneously in myofibrils, but rapid myosin release from myofibrils was observed without protein synthesis. Collectively, our results indicate that myosin shuttles between myofibrils and the nonmyofibrillar cytosol to maintain a dynamic equilibrium in skeletal muscle cells.

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