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Title: Identification of Two Distinct Uncoupling Protein 2 (UCP2) Messenger RNAs and the Relationship between Expression, Food Intake, and Growth in Channel Catfish

Author
item KOBAYASHI, YASUHIRO - Fort Hays State University
item Peterson, Brian
item Waldbieser, Geoffrey - Geoff

Submitted to: Domestic Animal Endocrinology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/15/2014
Publication Date: 2/1/2015
Citation: Kobayashi, Y., Peterson, B.C., Waldbieser, G.C. 2015. Identification of Two Distinct Uncoupling Protein 2 (UCP2) Messenger RNAs and the Relationship between Expression, Food Intake, and Growth in Channel Catfish. Domestic Animal Endocrinology. 51:56-64.

Interpretive Summary: Uncoupling protein 2 is a member of the mitochondrial channel proteins that regulate the flow of hydrogen ions and ATP generation. We hypothesized that increased muscle growth in channel catfish is associated with levels of UCP2 gene expression. Objectives were to clone the UCP2 gene, examine tissue UCP2 mRNA distribution, and changes in the amount of UCP2 mRNA in relation to changes in food intake in channel catfish. Two distinct UCP2 transcripts were identified and named UCP2a and UCP2b, respectively. Nucleotide and protein sequence analysis revealed that these UCP2 transcripts were similar to each other (75%). Nucleotide and amino acid sequence of catfish UCP2 transcripts were highly similar to UCP2 from other fish and mammals (>75%). Thirty days of fasting increased levels of UCP2b mRNA in muscle. In a separate 21 week feeding study, fish that grew faster tended toward lower levels of UCP2b mRNA on day 60 of the experiment. These results suggest that, although levels of UCP2b mRNA in muscle are influenced by whole body nutrient status, increased muscle growth appears to be independent of UCP2b expression and UCP2-mediated mechanisms.

Technical Abstract: Uncoupling protein 2 is a member of the mitochondrial channel proteins that regulate the flow of hydrogen ions and ATP generation. The relationship between UCP2 and nutrient metabolism has been well-defined in humans but unclear in fish. We hypothesized that increased muscle growth in channel catfish is associated with levels of UCP2 gene expression. Objectives were to clone the UCP2 gene, examine tissue UCP2 mRNA distribution, and changes in the amount of UCP2 mRNA in relation to changes in food intake in channel catfish. Two distinct UCP2 transcripts were identified from a channel catfish expression tag sequence library and named UCP2a and UCP2b, respectively. Nucleotide and protein sequence analysis revealed that these UCP2 transcripts were similar to each other (75%). Nucleotide and amino acid sequence of catfish UCP2 transcripts were highly similar to UCP2 from other fish and mammals (>75 %). Expression of UCP2a mRNA was detectable at very low levels in various metabolically active tissues. In contrast, expression of UCP2b mRNA was readily detectable in skeletal muscle compared to other tissues examined. Thirty days of fasting increased levels of UCP2b mRNA in muscle (p<0.05). In a separate 21 week feeding study, fish that grew faster tended toward lower levels of UCP2b mRNA (p<0.10) on day 60 of the experiment. These results suggest that, although levels of UCP2b mRNA in muscle are influenced by whole body nutrient status, increased muscle growth appears to be independent of UCP2b expression and UCP2-mediated mechanisms.