title: Myosin heavy chain mRNA and protein expression in single fibers of the rat soleus following reinnervation.
abstract: Myosin heavy chain (MHC) expression is regulated by many factors including neural input. To gain a better understanding of myosin transformation following reinnervation we examined both MHC protein and mRNA in single fibers of the soleus. A midthigh sciatic nerve lesion resulted in reinnervation of the soleus by motoneurons from both original and foreign motor pools. MHC expression was examined in individual fibers 8 and 16 weeks post injury in situ histochemistry and immunohistochemistry. Following a sciatic nerve lesion, the reinnervated soleus underwent a transformation from slow toward fast based on physiologic and biochemical measurements. At 8 weeks, fast MHC mRNA isoforms (IIa and IIx) were upregulated and slow mRNA was downregulated, however, the predominant protein isoform was MHC I. At both 8 and 16 weeks, many fibers expressed multiple mRNA isoforms. At 16 weeks there was limited co-expression of slow and fast MHC mRNAs, but continued co-expression of fast MHC mRNAs. Sixteen weeks following reinnervation the predominant fast mRNA and protein in the soleus was IIx MHC.
authors.affiliation: Biomedical Sciences Program, VA Medical Center, La Jolla 92093-9151, USA.
authors.forename: S C
authors.initials: SC
authors.lastname: Bodine
authors.forename: D J
authors.initials: DJ
authors.lastname: Pierotti
mesh_terms: D000818:Animals; D005260:Female; D018485:Muscle Fibers, Skeletal / Q000378:metabolism*; D009124:Muscle Proteins / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000294:innervation* / Q000378:metabolism*; D018995:Myosin Heavy Chains / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D012584:Sciatic Nerve / Q000502:physiology
chemical_list: D009124:Muscle Proteins; D012333:RNA, Messenger; D018995:Myosin Heavy Chains