First published online June 4, 2008
Journal of Cell Science 121, 1203e (2008)
© The Company of Biologists Limited
β-Synemin muscles in
In skeletal muscle, intermediate filaments (IFs) help to maintain muscle function by anchoring myofibrils to costameres – plasma-membrane-associated foci that include, among other proteins, the muscular-dystrophy-associated proteins dystrophin and 
-dystrobrevin. The molecular basis of the link between costameres and IFs is poorly understood, although the crosslinker protein plectin 1 (which has binding sites for actin and the muscle IF protein desmin) is thought to have a central role. Now, Takao Hijikata and colleagues (p. 2062) show that β-synemin, which is best known as a muscle IF protein, interacts with plectin 1 both in vitro and in vivo. The authors identify three β-synemin-binding sites in the N-terminal domain of plectin 1 and show that β-synemin colocalises with plectin 1 and -dystrobrevin at costameres. Using immuno-EM, they show that the costameric and IF-associated pools of β-synemin are distinct. In vitro, β-synemin can bind to F-actin and -dystrobrevin, and plectin 1 binds to -dystrobrevin, F-actin and β-synemin. On the basis of these data, the authors propose a new model of the IF-costamere linkage. Their results have implications for the treatment of muscular dystrophies.
Related articles in JCS:
- Plectin 1 links intermediate filaments to costameric sarcolemma through β-synemin, -dystrobrevin and actin
- Takao Hijikata, Akio Nakamura, Keitaro Isokawa, Michihiro Imamura, Katsutoshi Yuasa, Ryoki Ishikawa, Kazuhiro Kohama, Shinichi Takeda, and Hiroshi Yorifuji
JCS 2008 121: 2062-2074.
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