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United States Department of Agriculture

Agricultural Research Service

Research Project: IDENTIFICATION AND CHARACTERIZATION OF GENES AFFECTING COOL AND COLD WATER AQUACULTURE PRODUCTION Title: Molecular characterization of the MuRF genes in rainbow trout: potential role in muscle degradation

Authors
item Wang, Jiannan -
item Salem, Mohamed -
item Kenney, P. Brett -
item Rexroad, Caird
item Yao, Jianbo -

Submitted to: Comparative Biochemistry and Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 25, 2010
Publication Date: March 1, 2011
Citation: Wang, J., Salem, M., Kenney, P., Rexroad III, C.E., Yao, J. 2011. Molecular characterization of the MuRF genes in rainbow trout: potential role in muscle degradation. Comparative Biochemistry and Physiology. 158(3):208-215.

Interpretive Summary: Constituting 60-65% of fish weight, muscle is the edible part of the fish that is a source of protein and trace nutrients required for human health. Limited knowledge of molecular regulation of muscle growth and flesh quality hinders genetic improvement of these important traits in fish for aquaculture production efficiency and consumer satisfaction. Muscle growth is determined primarily by the balance between protein synthesis and degradation. When rates of protein synthesis are similar, protein degradation is critical in explaining differences in growth efficiency. To this end we identified and characterized the rainbow trout complement of MuRF genes, which are associated with protein breakdown in mammals, confirming that they retain a similar function in trout. Our results suggest that these genes have an important role in fish muscle protein degradation and can potentially impact growth and fillet quality.

Technical Abstract: As United States and world seafood demand increases, aquaculture production becomes more important. Limited knowledge of molecular regulation of muscle growth and flesh quality hinders genetic improvement of these important traits in fish for aquaculture production efficiency and consumer satisfaction. Muscle growth is determined primarily by the balance between protein synthesis and degradation. When rates of protein synthesis are similar, protein degradation is critical in explaining differences in growth efficiency. In mammals muscle atrophy results from increased protein breakdown, and is associated with activation of the ubiquitin proteasome pathway, including induction of the muscle-specific ubiquitin protein ligase, MuRF-1. Animals lacking MuRF-1 are resistant to muscle atrophy. In fish, little is known about the role of the proteasome/MuRF pathway in muscle degradation. Our objectives were to: 1) clone and characterize MuRF genes in rainbow trout; and 2) determine expression of MuRF genes in association with starvation- and vitellogenesis-induced muscle atrophy in rainbow trout. We have identified full-length cDNA sequences for three MuRF genes (MuRF-1, MuRF-2, and MuRF-3). These genes encode proteins with typical MuRF structural domains, including a RING-finger, a B-box and a Leucine-rich coiled-coil domain. RT-PCR analysis showed that MuRF 1, 2, and 3 are predominantly expressed in muscle and heart tissues. Real time PCR analysis revealed that expression of all MuRF genes is up-regulated during starvation- and egg growth and development. These results suggest that MuRF genes have an important role in fish muscle protein degradation.

Last Modified: 10/20/2014
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