Alterations in contractile properties and expression of myofibrillar proteins in wobbler mouse muscles.
The purpose of this study was to characterize the alterations in muscle contractile (tension-pCa relationship) and biochemical (myosin heavy and light chains, troponin C content) properties in a hereditary motoneuron disease. The study was performed on wobbler mouse mutants which presented a neuronal degeneration. The time course of the disease was followed at 5 and 7 weeks in sternocleidomastoid (SCM) and soleus muscles. The wobbler disease was found to induce a shift from fast to slow myosin heavy-chain isoform expression in SCM and soleus muscles. The analysis of the myosin light-chain (MLC) composition revealed, for the SCM muscles, the appearance of the slow isoforms at 5 weeks and an increase in the regulatory MLC2 content at 7 weeks. A significant increase in the slow troponin C isoform content was found in both types of wobbler muscles at 7 weeks. The wobbler soleus and SCM muscles presented an age- and fiber-type-related atrophy, characterized by a decline in absolute maximal tension and fiber diameter. A decrease in calcium sensitivity was observed at 7 weeks for the soleus fibers and at both 5 and 7 weeks for the SCM. The results indicated fast-to-slow changes in contractile and biochemical properties of the wobbler soleus and SCM muscles, which occurred during the motoneuron degeneration process previously described in the wobbler pathology.
Toursel
T
T
Laboratoire de Plasticité Neuromusculaire, Université des Sciences et Technologies de Lille, Bât SN4, Villeneuve d'Ascq Cedex, F-59655, France.
Bastide
B
B
Stevens
L
L
Rieger
F
F
Mounier
Y
Y
D000818:Animals; D002118:Calcium / Q000378:metabolism; D066298:In Vitro Techniques; D051379:Mice; D008810:Mice, Inbred C57BL; D008818:Mice, Neurologic Mutants; D016472:Motor Neuron Disease / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology*; D009119:Muscle Contraction; D018656:Muscle Fibers, Fast-Twitch / Q000378:metabolism / Q000473:pathology; D018657:Muscle Fibers, Slow-Twitch / Q000378:metabolism / Q000473:pathology; D018482:Muscle, Skeletal / Q000378:metabolism* / Q000473:pathology; D009210:Myofibrils / Q000378:metabolism*; D018995:Myosin Heavy Chains / Q000096:biosynthesis; D018994:Myosin Light Chains / Q000096:biosynthesis; D020033:Protein Isoforms / Q000096:biosynthesis; D019209:Troponin C / Q000096:biosynthesis
D018994:Myosin Light Chains; D020033:Protein Isoforms; D019209:Troponin C; D018995:Myosin Heavy Chains; D002118:Calcium