Proteasome activities in the rectus abdominis muscle of young and older individuals.
Sarcopenia is one of the most striking effects of age, the causes and the pathogenic mechanisms being largely unknown. Unfortunately, there is limited information on the effect of aging on muscle protein breakdown in basal conditions. The present study aimed at investigating if skeletal muscle ubiquitn mRNA levels and proteasome activities vary with age in healthy individuals. Ub mRNA levels were measured by northern blot analysis whereas proteasome activities were determined by evaluating the cleavage of specific fluorogenic substrates in the rectus abdominis muscle of 14 healthy male individuals. Patients were divided in three groups according to the age: (1) 20-30 years (N = 3); (2) 31-64 years (N = 5); (3) > or = 65 years (N = 6). Quantitation of the ubiquitin mRNA levels (expressed in arbitrary units) (mean (SD) showed no differences among the three groups of age (20-30 years: 1352 +/- 441; 31-64 years: 1324 +/- 439; > or = 65 years: 884 +/- 400; P = 0.33). The correlation between age and muscle ubiquitin mRNA levels was not statistically significant (r = -0.4, P = 0.26). The three proteasome activities, chymotrypsin-like (CTL), trypsin-like (TL) and peptidyl-gutamyl-peptidase (PGP), expressed as nkatal x 10(-3)/mg protein, were similar in the three groups of patients stratified according to the age. There was no correlation between age with either CTL (r = 0.22, P = 0.4), PGP (r = 0.002, P = 0.9), and TL (r = 0.28, P = 0.33) activities. In conclusion, the present study shows that the skeletal muscle proteasome activities do not differ with age in healthy male individuals.
Bossola
Maurizio
M
Istituto di Clinica Chirurgica, Università Cattolica del Sacro Cuore, Largo A. Gemelli, 8, 00168, Rome, Italy. maubosso@tin.it
Pacelli
Fabio
F
Costelli
Paola
P
Tortorelli
Antonio
A
Rosa
Fausto
F
Doglietto
Giovan Battista
GB
D000328:Adult; D017677:Age Distribution; D000367:Age Factors; D000368:Aged; D000375:Aging / Q000378:metabolism*; D053818:Chymases / Q000378:metabolism; D010450:Endopeptidases / Q000378:metabolism; D006801:Humans; D008297:Male; D008875:Middle Aged; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D017568:Rectus Abdominis / Q000201:enzymology*; D053802:Tryptases / Q000378:metabolism; D025801:Ubiquitin / Q000235:genetics / Q000378:metabolism
D012333:RNA, Messenger; D025801:Ubiquitin; D010450:Endopeptidases; D053818:Chymases; D053802:Tryptases; D046988:Proteasome Endopeptidase Complex; C114177:peptidylglutamylpeptide hydrolase