Expression of peroxisome proliferator activated receptors (PPARS) and its regulation by endogenous and exogenous factors in fish

Abstract

Up to date, three PPAR subtypes have been described in mammals, PPARalpha, -beta and -gamma, each with different tissue expression pattern and different physiological roles. The hypothesis we intend to demonstrate with this report is that PPAR subtypes are expressed differentially within the cells and tissues fish an that this expression is modulated under the influence of a variety of endogenous and exogenous factors including gender, developmental stage, treatment with known PPAR ligands and exposure to peroxisome proliferators environmental pollutants. All three PPAR subtypes are expressed in zebrafish and gray mullet and at least PPARalpha is expressed in atlantic cod. These PPAR subtypes are expressed differentially withing the cells and tissues of fish in relation with their different roles including regulation of lipid homeostasis, immune function and relation with their different roles including regulation of lipid homeostasis, immune function and development. Further, the expression of PPARs is modulated under the influence of a variety of endogenous and exogenous factors including gender, developmental stage, exposure to peroxisome proliferators environmental pollutants and treatment with known PPAR ligands. Zebrafish PPARs are less lingad-specific than the mammalian counterparts, suggesting a possible redundancy in PPAR functions.