Muscle accretion is affected by the difference
between protein synthesis and its degradation. Studies
on different species revealed that muscle proteolysis is
mediated by different pathways including the ubiquitinproteasome
pathway in which the ubiquitin protein ligases
play an important role. These muscle atrophy
associated ligases were not well studied in tilapia. In
this study, we characterized the ubiquitin protein ligases
MuRF1/2/3, Atrogin-1 and F-box25, members of the
ubiquitin-proteasome pathway in tilapia, Oreochromis
niloticus, and their expressions in the muscle of starved,
fed, refed, and control fish. Sequences of these genes
revealed presence of Ring finger, B-box, and Cos domains
in all MuRF genes, as well as F-box domain in
Atrogin-1 and F-box25 genes. Real-time qPCR data
analysis showed that expression of MuRF1/2/3,
Atrogin-1, F-box25, and proteasome complex genes
was significantly upregulated in starved fish compared
to fed fish. Concurrently, the proteasome activity was
1.7-folds elevated in the starved fish compared to fed
fish. These results confirm the important role of these
genes in muscle degradation and suggest potential usage
as markers of muscle accretion in tilapia.