The relationship between skeletal muscle proteolysis and ubiquitin-proteasome proteolytic pathway in burned XXXX .

@entity1568 @entity535 @entity62132 @entity35 @entity2057 @entity130
Negative @entity1568 balance and accelerated muscle protein breakdown are characteristics of @entity130 . The mechanism by which muscle proteolysis occurs may be activation of the ubiquitin-proteasome pathway, but needs to be further elucidated. The aim of this study was to gain more insight into the role of ubiquitin-proteasome pathway in muscle proteolysis, after @entity130 in a @entity35 @entity130 model. The proteolytic rates and mRNA expression of ubiquitin, @entity62132 in extensor digital longus (EDL) and soleus (SOL) muscle were determined by @entity535 analyzer and Northern blot, respectively. The results were as follows: the total and myofibrillar proteolytic rate of EDL muscle increased markedly, especially at 12 and 24h post-burn. The levels of 2.4kb mRNA for ubiquitin, 1.2kb mRNA for @entity62132 (a rate-limiting and regulated enzyme for conjugation of ubiquitin with protein substrate) and mRNA for subunit RC2 (the largest subunit of 20S proteasome) predominantly increased in EDL muscle after the stimulation of @entity130 . No significant changes in proteolytic rate and transcription of ubiquitin, @entity62132 in SOL muscle were observed. There was a significantly positive correlation between the proteolytic rate and the levels of 2.4kb mRNA for ubiquitin, 1.2kb mRNA for @entity62132 , or mRNA for subunit RC2. The results indicated that @entity2057 after @entity130 was mainly due to the accelerated breakdown of myofibrils, and EDL muscle was more sensitive to @entity130 than SOL muscle. The activation of ubiquitin-proteasome pathway was one reason for the enhanced protein catabolism in skeletal muscle. This is the first demonstration of upregulated expression of @entity62132 in muscle, in response to @entity130 , and it provides a clue to reduce @entity2057 by specifically inhibiting the specific enzymes or subunits involved in the enhancement of the activity of ubiquitin-proteasome pathway after @entity130 .
