33 research outputs found
Regulation of proteolysis during reloading of the unweighted soleus muscle
International audienc
Role of protein intake on protein synthesis and fiber distribution in the unweighted soleus muscle
International audienc
Essai d'interpretation des reactions metabolique et hormonale a l'effort prolonge. Tentative de correction pharmacologique
SIGLECNRS-CDST / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc
A high protein diet does not improve protein synthesis in the nonweight-bearing rat tibialis anterior muscle
International audienc
Altered response of protein synthesis to nutritional state and endurance training in old rats
International audienc
Entrainement physique et amelioration de la tolerance aux accelerations
SIGLECNRS RP 174 (212) / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc
Coordinate expression of the 19S regulatory complex and evidence for ubiquitin-dependent telethonin degradation in the unloaded soleus muscle
International audienceCatabolic stimuli induce a coordinate expression of the 20S proteasome subunits in skeletal muscles. However, contradictory data have been obtained for the 19S regulatory complex (RC) subunits, which could reflect differential regulation at the transcriptional and/or translational level. To address this point we used a well-established model of muscle atrophy (hindlimb suspension) and determined the mRNA levels for 19S subunits belonging to both the base (non-ATPase SI, ATPases S7 and S8) and the lid (S14) of the 19S RC. Concomitant increased mRNA levels were observed for all studied subunits in rat soleus muscles after 9 days of unloading. In addition, analysis of polysome profiles showed a similar proportion of actively translated mRNA (50%) in unloaded and control soleus muscle. Furthermore, the repressed pool of messenger ribonucleoparticles (mRNPs) was low in both control (14%) and unloaded (15%) animals. Our data show that representative 19S subunits (S7 and S8) were efficiently translated, suggesting a coordinate production of 19S RC subunits. The 19S RC is responsible for the binding of polyubiquitin conjugates that are subsequently degraded inside the 20S proteasome core particle. We observed that soleus muscle atrophy was accompanied by an accumulation of ubiquitin conjugates. Purification of ubiquitin conjugates using the S5a 19S subunit followed by feubiquitination identified telethonin as a 26S proteasome substrate. In conclusion, muscle atrophy induces a concomitant expression of 26S proteasome subunits. Substrates to be degraded include a protein required for maintaining the structural integrity of sarcomeres