Changes in protein levels of elongation factors, eEF1A-1 and eEF1A-2/S1, in long-term denervated rat muscle.
OBJECTIVE
This study was designed to determine whether the quantitative relationship between the levels of the eEF1A-1(developmental) and eEF1A-2/S1 (adult) isoforms of peptide elongation factor remains stable after denervation of skeletal muscle or whether in response to denervation the relative amount of the developmental form would increase. In normal postnatal rat muscle, eEF1A-2/S1 is the dominant form represented, and levels of eEF1A-1 are extremely low.


METHODS
One hind limb in young adult rats was permanently denervated. Denervated and corresponding contralateral control muscles were removed for biochemical and morphological analysis from 2 days to 25 months after denervation.


RESULTS
By one month after denervation, relative levels of eEF1A-1 rose dramatically in relation to those of eEF1A-2/S1, and they remained high throughout the remainder of the 25-month denervation period. Ultrastructural analysis showed a complex mix of muscle fiber atrophy, dying muscle nuclei and muscle fibers, and newly forming muscle fibers in the same tissue.


CONCLUSIONS
As during muscle regeneration, levels of the developmental eEF1A-1 isoform of peptide elongation factor greatly increased relative to those of the adult eEF1A-2/S1 adult isoform following denervation in rat muscles. However, in contrast to regeneration, the elevated level of eEF1A-1 did not return to the basal minimal level. Since switching from eEF1A-1 to eEF1A-2/S1 is an indicator that terminal differentiated is completed, the failure of eEF1A-1 to return to basal level may be indicative of the persistence of an unstable tissue environment that includes muscle fiber atrophy, degeneration and neomyogenesis. The specific cellular basis for the increase in eEF1A-1 could not be determined from this study.
Khalyfa
Abdelnaby
A
Departments of Biochemistry and Molecular Biology, University of Louisville, Louisville, KY, USA.
Carlson
Bruce M
BM
Dedkov
Eduard I
EI
Wang
Eugenia
E
D000818:Animals; D000906:Antibodies / Q000378:metabolism; D015153:Blotting, Western; D003720:Densitometry; D008297:Male; D008855:Microscopy, Electron, Scanning; D009121:Muscle Denervation; D018482:Muscle, Skeletal / Q000294:innervation / Q000378:metabolism* / Q000648:ultrastructure; D020648:Peptide Elongation Factor 1 / Q000378:metabolism*; D010446:Peptide Fragments / Q000276:immunology; D020033:Protein Isoforms / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D013997:Time Factors
D000906:Antibodies; C503236:Eef1a2 protein, rat; D020648:Peptide Elongation Factor 1; D010446:Peptide Fragments; D020033:Protein Isoforms