Molecular characterization of three peroxisome proliferator‐activated receptors from the sea bass (Dicentrarchus labrax)

Abstract

Peroxisome proliferator-activated receptors (PPAR) are nuclear hormone receptors that control the expression of genes involved in lipid homeostasis in mammals. We searched for PPAR in sea bass, a marine fish of particular interest to aquaculture, after hypothesizing that the physiological and molecular processes that regulate lipid metabolism in fish are similar to those in mammals. Here, we report the identification of complementary DNA and corresponding genomic sequences that encode three distinct PPAR from sea bass. The sea bass PPAR are the structural homologs of the mammalian PPAR alpha, beta/delta, and gamma isotypes. As revealed by RNase protection, the tissue expression profile of the fish PPAR appears to be very similar to that of the mammalian PPAR homologs. Thus, PPAR alpha is mainly expressed in the liver, PPAR gamma in adipose tissue, and PPAR beta in all tissues tested, with its highest levels in the liver, where it is also the dominant isotype expressed. Like mammalian PPAR, the sea bass isotypes recognize and bind to PPAR response elements of both mammalian and piscine origin, as heterodimers with the 9-cis retinoic acid receptor. Through the coactivator-dependent receptor ligand assay, we also demonstrated that natural FA and synthetic hypolipidemic compounds can act as ligands of the sea bass PPAR alpha and beta isotypes. This suggests that the sea bass PPAR act through similar mechanisms and perform the same critical lipid metabolism functions as mammalian PPAR.

Towards Fish Lipid Nutrigenomics: Current State and Prospects for Fin-Fish Aquaculture

“…Thus, the ability of PPARα to increase fatty acid β-oxidation is of considerable interest in aquaculture where fish are fed high fat diets in an effort to maximise the energy that can be supplied by dietary lipid, and so "spare" dietary protein for the synthesis of new tissue/flesh (Sargent and Tacon, 1999). PPARα subtype cDNAs have been characterized from sea bream, sea bass and plaice (Pleuronectes platessa) (Boukouvala et al 2004;Leaver et al 2005). These proteins bear high identity to mammalian PPARα and for reasons discussed below have been termed PPARα2.…”

“…Furthermore, information from the pufferfish, stickleback and medaka (also Acanthopterygia) genome sequencing projects show that these fish also possess a single PPARβ gene (Fig 4). In plaice, sea bream and sea bass the single PPARβ gene shares many of the characteristics of its mammalian counterpart, having a broad tissue expression profile and being activated by unsaturated fatty acids (Leaver et al 2005;Boukouvala et al 2004).…”

“…PPARγ was the first PPAR subype to be identified in fish, with cDNAs characterised from Atlantic salmon and plaice (Ruyter et al 1997;Leaver et al 1998). Subsequently the availability of genome information for zebrafish, stickleback, medaka and pufferfish has shown that, as in mammals, these fish possess a single PPARγ gene and studies on sea bream, sea bass and plaice also indicate the presence of a single gene (Fig 4; (Maglich et al 2003;Boukouvala et al 2004;Leaver et al 2005). There are no indications yet of alternatively spliced products and thus alternative PPARγ proteins in fish.…”

Molecular characterization of a gilthead sea bream (Sparus aurata) muscle tissue cDNA for carnitine palmitoyltransferase 1B (CPT1B)

“…The synthesis of the sea bream β-actin riboprobe has been previously described (Leaver et al, 2005). Riboprobes were labeled with [α-32 P]CTP (800 Ci/mmol, Amersham Biosciences Europe) and the RNase protection assay was performed as previously described (Boukouvala et al, 2004, Leaver et al, 2005 on 8 µg of total RNA from each tissue sample. The protected fragments were separated on a 6% polyacrylamide gel containing 7M urea.…”

Untitled

“…Sci. 17: 477-485 (2017) Misaki, Gelman, & Watabe, 2007), tilapia (Adeogun, Ibor, Regoli, & Aru kwe, 2016), sea bass (Boukouvala et al, 2004), orange-spotted grouper , g rass carp (He et al, 2012). Although there were some reports on PPARγ related to the fish nutrition, immune and environ ment (Liang, Zhao, Li, & Gao, 2015;Luo et al, 2015;Adeogun et al, 2016), the regulation and function of fish PPARγ remain unknown.…”