Switching of actin isoforms in skeletal muscle differentiation using mouse ES cells.
Among six actin isoforms, alpha-skeletal and alpha-cardiac actins have similar amino acid components and are highly conserved. Although skeletal muscles essentially express alpha-skeletal actins in the adult tissue, alpha-cardiac isoform actin is prominent in the embryonic muscle tissue. Switching of actin isoforms from alpha-cardiac to alpha-skeletal actin occurs during skeletal muscle differentiation. The cardiac type alpha-actin is expressed in the regeneration and patho-physiological states of the skeletal muscles as well. In the present study, we demonstrate the morphological switching of alpha-type actin isoforms from alpha-cardiac to alpha-skeletal actin in vitro using mouse ES cells for the first time. Immunofluorescent double staining with two specific antibodies revealed that alpha-cardiac actin appeared first in myoblasts. After cell fusion to form myotubes, the cardiac type actin decreased and alpha-skeletal actin conversely increased. Finally, the alpha-skeletal isoform remained as a main actin component in the fully mature skeletal muscle fibers. The exchange of isoforms is not directly linked to the sarcomere formation. As a result, ES cells provide a useful in vitro system for exploring skeletal muscle differentiation.
Mizuno
Yota
Y
Department of Physical Therapy, Nagoya University School of Health Sciences, Nagoya, Japan.
Suzuki
Mayu
M
Nakagawa
Hiroki
H
Ninagawa
Nana
N
Torihashi
Shigeko
S
D000199:Actins / Q000032:analysis* / Q000235:genetics; D000818:Animals; D002454:Cell Differentiation; D053595:Embryonic Stem Cells / Q000166:cytology*; D051379:Mice; D018485:Muscle Fibers, Skeletal; D018482:Muscle, Skeletal / Q000166:cytology*; D032446:Myoblasts; D020033:Protein Isoforms / Q000032:analysis; D012518:Sarcomeres
D000199:Actins; D020033:Protein Isoforms