Molecular characterization of peroxisome proliferator-activated receptors (PPARs) and their gene expression in the differentiating adipocytes of red sea bream Pagrus major

Abstract

To investigate the molecular mechanism of fish adipocyte differentiation, the three subtypes of PPAR genes (alpha, beta and gamma) were characterized in a marine teleost red sea bream (Pagrus major). The primary structures of red sea bream PPARs exhibited high degrees of similarities to their mammalian counterparts, and their gene expression was detected in various tissues including adipose tissue, heart and hepatopancreas. During the differentiation of primary cultured red sea bream adipocytes, three PPARs showed distinct expression patterns: The alpha subtype showed a transient increase and the beta gene expression tended to increase during adipocyte differentiation whereas the gene expression level of PPARgamma did not change. These results suggest that they play distinct roles in adipocyte differentiation in red sea bream. In the differentiating red sea bream adipocytes, mammalian PPAR agonists, 15-deoxy-Delta(12,14)-prostaglandin J(2), ciglitazone and fenofibrate did not show clear effects on the adipogenic gene expression. However, 2-bromopalmitate increased the PPARgamma and related adipogenic gene expression levels, suggesting the gamma subtype plays a central role in red sea bream adipocyte differentiation and in addition, fatty acid metabolites can be used as modulators of adipocyte function. Thus our study highlighted the roles of PPARs in fish adipocyte differentiation and provided information on the molecular mechanisms of fish adipocyte development.

Morphology, mitochondrial development and adipogenic-related genes expression during adipocytes differentiation in grass carp (Ctenopharyngodon idellus)

“…Studies in mammals have indicated that PPAR a is involved in the early phase of adipocyte differentiation [32]. In fish, PPAR a showed a transient increase during the induction period [11]. In this result, the level of PPAR a showed a transient increase after inducing for 1 day, which agrees with findings in mammals and other fish [11,32] (Fig.…”

“…It has been reported that FAS and SCD are all induced during differentiation in 3T3-L1 adipocyte [40,41]. In red sea bream, FAS and SCD were only induced in the later stage of differentiation [11]. In Atlantic salmon, however, the level of SCD was highest from the middle stage to the later stage [17].…”

“…Numerous studies in mammals and fish have demonstrated that adipocyte differentiation is regulated by a complex network of molecular events [1,11]. As reported in many studies, the transcription factors PPAR c and CCAAT/enhancer-binding proteins a (C/EBP a) are believed necessary for the differentiation of preadipocytes into mature adipocytes, both in mammals and in fish [3,5,12].…”

Ontogeny and nutritional control of adipogenesis in zebrafish (Danio rerio)

“…4A-C ). Previous in vitro analysis in other teleost species (i.e., Pagrus major ) revealed that pparg is expressed in cultured preadipocytes as well as adipocytes ( 34 ). Although we are unable to exclude the possibility that zebrafi sh preadipocytes express pparg below our applied level of detection, zebrafi sh pparg appears to be robustly expressed only in mature adipocytes after the onset of neutral lipid deposition.…”

Melatonin and Peripheral Circuitries: Insights on Appetite and Metabolism in Danio Rerio

“…Three subtypes of PPARs, termed a, b (d), and c, have been identified in mammals' liver as well as in fish. The overall features including the primary structure and tissue distribution are similar to those of their mammalian counterparts, 34,35 resulting a good tool in fish metabolism studies. Concerning SREBP, this sterol-sensitive transcription factor is synthesized as a membrane-bound precursor protein that in the liver is cleaved to its mature form when cellular sterols are depleted.…”