Abstract
In the cross-bridge theory, contractile force is produced by crossbridges that form between actin and myosin filaments. However, when a contracting muscle is stretched, its active force vastly exceeds the force that can be attributed to cross-bridges. This unexplained, enhanced force has been thought to originate in the giant protein titin, which becomes stiffer in actively compared with passively stretched sarcomeres by an unknown mechanism. We investigated this mechanism using a genetic mutation (mdm) with a small but crucial deletion in the titin protein. Myofibrils from normal and mdm micewere stretched from sarcomere lengths of 2.5 to 6.0 μm. Actively stretched myofibrils from normal mice were stiffer and generated more force than passively stretched myofibrils at all sarcomere lengths. No increase in stiffness and just a small increase in force were observed in actively compared with passively stretched mdm myofibrils. These results are in agreement with the idea that titin force enhancement stiffens and stabilizes the sarcomere during contraction and that this mechanism is lost with the mdm mutation.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 1311-1316 |
| Number of pages | 6 |
| Journal | Journal of Experimental Biology |
| Volume | 219 |
| Issue number | 9 |
| DOIs | |
| State | Published - May 1 2016 |
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Keywords
- Cross-bridges
- Eccentric contractions
- Muscular dystrophy with myositis
- Myofibrils
- Stiffness
ASJC Scopus subject areas
- Ecology, Evolution, Behavior and Systematics
- Physiology
- Medicine(all)
- Aquatic Science
- Animal Science and Zoology
- Molecular Biology
- Insect Science
Cite this
Decreased force enhancement in skeletal muscle sarcomeres with a deletion in titin. / Powers, Krysta; Nishikawa, Kiisa C; Joumaa, Venus; Herzog, Walter.
In: Journal of Experimental Biology, Vol. 219, No. 9, 01.05.2016, p. 1311-1316.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Decreased force enhancement in skeletal muscle sarcomeres with a deletion in titin
AU - Powers, Krysta
AU - Nishikawa, Kiisa C
AU - Joumaa, Venus
AU - Herzog, Walter
PY - 2016/5/1
Y1 - 2016/5/1
N2 - In the cross-bridge theory, contractile force is produced by crossbridges that form between actin and myosin filaments. However, when a contracting muscle is stretched, its active force vastly exceeds the force that can be attributed to cross-bridges. This unexplained, enhanced force has been thought to originate in the giant protein titin, which becomes stiffer in actively compared with passively stretched sarcomeres by an unknown mechanism. We investigated this mechanism using a genetic mutation (mdm) with a small but crucial deletion in the titin protein. Myofibrils from normal and mdm micewere stretched from sarcomere lengths of 2.5 to 6.0 μm. Actively stretched myofibrils from normal mice were stiffer and generated more force than passively stretched myofibrils at all sarcomere lengths. No increase in stiffness and just a small increase in force were observed in actively compared with passively stretched mdm myofibrils. These results are in agreement with the idea that titin force enhancement stiffens and stabilizes the sarcomere during contraction and that this mechanism is lost with the mdm mutation.
AB - In the cross-bridge theory, contractile force is produced by crossbridges that form between actin and myosin filaments. However, when a contracting muscle is stretched, its active force vastly exceeds the force that can be attributed to cross-bridges. This unexplained, enhanced force has been thought to originate in the giant protein titin, which becomes stiffer in actively compared with passively stretched sarcomeres by an unknown mechanism. We investigated this mechanism using a genetic mutation (mdm) with a small but crucial deletion in the titin protein. Myofibrils from normal and mdm micewere stretched from sarcomere lengths of 2.5 to 6.0 μm. Actively stretched myofibrils from normal mice were stiffer and generated more force than passively stretched myofibrils at all sarcomere lengths. No increase in stiffness and just a small increase in force were observed in actively compared with passively stretched mdm myofibrils. These results are in agreement with the idea that titin force enhancement stiffens and stabilizes the sarcomere during contraction and that this mechanism is lost with the mdm mutation.
KW - Cross-bridges
KW - Eccentric contractions
KW - Muscular dystrophy with myositis
KW - Myofibrils
KW - Stiffness
UR - http://www.scopus.com/inward/record.url?scp=84982078374&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84982078374&partnerID=8YFLogxK
U2 - 10.1242/jeb.132027
DO - 10.1242/jeb.132027
M3 - Article
C2 - 26944495
AN - SCOPUS:84982078374
VL - 219
SP - 1311
EP - 1316
JO - Journal of Experimental Biology
JF - Journal of Experimental Biology
SN - 0022-0949
IS - 9
ER -