Identification and organ expression of peroxisome proliferator activated receptors in brown trout (Salmo trutta f. fario)

Although widely studied in mammals, little information about fish peroxisome proliferator activated receptors (PPARs) is yet available. As a baseline for future studies, the three PPAR isotypes were identified in brown trout (Salmo trutta f. fario) and their organ distribution pattern was established. The cDNA fragments encoding PPARs alpha, beta and gamma were amplified by PCR, and the deduced sequences of the correspondent peptides were compared with other species sequences. Both the 183 amino acid sequence from PPAR alpha and the 103 amino acid sequence from PPAR beta shared high levels of homology with the correspondent peptides of other fishes and terrestrial vertebrates, whereas PPAR gamma 108 amino acid sequence showed much less similarity with non-fish PPAR gamma. According to both semi-quantitative RT-PCR and real-time RT-PCR, PPAR alpha mRNA predominates in white muscle, heart and liver and PPAR beta is more expressed in testis, heart, liver, white muscle and trunk kidney. PPAR gamma was only detected in trunk kidney and liver by real-time RT-PCR and also in spleen by semi-quantitative RT-PCR. PPAR beta seems to be the most strongly expressed isotype, whereas PPAR gamma shows a much weaker global expression. (c) 2005 Elsevier B.V. All rights reserved.