Proteasome production in human muscle during nutritional inhibition of myofibrillar protein degradation. Metabolism 2004 Mar;53(3):340-7
Date
03/12/2004Pubmed ID
15015147DOI
10.1016/j.metabol.2003.10.015Scopus ID
2-s2.0-2542438679 (requires institutional sign-in at Scopus site) 10 CitationsAbstract
Protein undernutrition inhibits adenosine triphosphate (ATP)-dependent muscle protein degradation-a hallmark of the proteasome system. Here we report decreased myofibrillar protein degradation during dietary protein restriction without a concomitant decrease in proteasome gene expression, proteasome protein abundance, or proteasome in vivo fractional synthesis rate. Healthy human subjects consuming the average minimum adult protein requirement (0.71 g x kg(-1) fat-free mass x d(-1)) exhibited substantially lower (68%) excretion of 3-methylhistidine, an indicator of myofibrillar protein breakdown, when compared with subjects consuming an ample, American-style protein intake (1.67 g x kg(-1) fat-free mass x d(-1)). However, they displayed no difference in the expression of mRNA for proteasome subunits C2 or C3, in the content of C2 protein, or in the rate of incorporation of stable isotopically labeled l-[1-(13)C]-leucine into proteasome proteins. The results demonstrate that nutritional inhibition of myofibrillar protein degradation does not involve suppression in vivo of proteasome production in man. This suggests that other elements of the ubiquitin-proteasome system, such as ubiquitination pathways, are more important than proteasome abundance in the nutritional regulation of skeletal muscle mass.
Author List
Brodsky IG, Suzara D, Furman M, Goldspink P, Ford GC, Nair KS, Kukowski J, Bedno SMESH terms used to index this publication - Major topics in bold
AdolescentAdult
Blood Urea Nitrogen
Cysteine Endopeptidases
Diet
Electrophoresis, Polyacrylamide Gel
Female
Humans
Immunoblotting
Kinetics
Leucine
Male
Methylhistidines
Multienzyme Complexes
Muscle Proteins
Muscle, Skeletal
Myofibrils
Peptide Hydrolases
Proteasome Endopeptidase Complex
RNA, Messenger
Reverse Transcriptase Polymerase Chain Reaction
