Neural regulation of acetylcholinesterase-associated collagen Q in rat skeletal muscles.
Acetylcholinesterase-associated collagen Q is expressed also outside of neuromuscular junctions in the slow soleus muscle, but not in fast muscles. We examined the nerve dependence of muscle collagen Q expression and mechanisms responsible for these differences. Denervation decreased extrajunctional collagen Q mRNA levels in the soleus muscles and junctional levels in fast sternomastoid muscles to about one third. Cross-innervation of denervated soleus muscles by a fast muscle nerve, or electrical stimulation by 'fast' impulse pattern, reduced their extrajunctional collagen Q mRNA levels by 70-80%. In contrast, stimulation of fast muscles by 'slow' impulse pattern had no effect on collagen Q expression. Calcineurin inhibitors tacrolimus and cyclosporin A decreased collagen Q mRNA levels in the soleus muscles to about 35%, but did not affect collagen Q expression in denervated soleus muscles or the junctional expression in fast muscles. Therefore, high extrajunctional expression of collagen Q in the soleus muscle is maintained by its tonic nerve-induced activation pattern via the activated Ca(2+)-calcineurin signaling pathway. The extrajunctional collagen Q expression in fast muscles is independent of muscle activation pattern and seems irreversibly suppressed. The junctional expression of collagen Q in fast muscles is partly nerve-dependent, but does not encompass the Ca(2+)-calcineurin signaling pathway.
Trinkaus
Miha
M
Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia.
Pregelj
Peter
P
Trkov
Sasa
S
Sketelj
Janez
J
D000110:Acetylcholinesterase / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D019703:Calcineurin / Q000502:physiology; D020013:Calcium Signaling / Q000235:genetics / Q000502:physiology; D003094:Collagen / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D005786:Gene Expression Regulation; D008297:Male; D018656:Muscle Fibers, Fast-Twitch / Q000201:enzymology / Q000378:metabolism; D018657:Muscle Fibers, Slow-Twitch / Q000201:enzymology / Q000378:metabolism; D018482:Muscle, Skeletal / Q000201:enzymology* / Q000378:metabolism; D009469:Neuromuscular Junction / Q000201:enzymology / Q000378:metabolism; D009474:Neurons / Q000201:enzymology* / Q000378:metabolism; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D017208:Rats, Wistar
D012333:RNA, Messenger; D003094:Collagen; D000110:Acetylcholinesterase; C533412:ColQ protein, rat; D019703:Calcineurin