Dynamics of PPARs, fatty acid metabolism genes and lipid classes in eggs and early larvae of a teleost

Abstract

Dietary long chain polyunsaturated fatty acids (FA) have been recognized of crucial importance in early development of vertebrates, contributing to the impressive morphological and physiological changes both as building blocks and to energy production. The importance of lipids along development depends on ontogenetic, phylogenetic and environmental parameters. The expression patterns of FA metabolism genes have not been characterized in developing fish embryos nor compared to lipid class profiles. Full lipid metabolism only occurred after hatching, as revealed by alterations in lipid profiles and FA gene expression. Nonetheless, transcriptional changes of some FA genes were already present in embryos at notochord formation. Many genes displayed an expression profile opposed to the decrease of lipids along the development, while others responded solely to starvation. Transcription of most genes involved in FA metabolism had a strong correlation to PPARs' mRNA levels (α1, α2, β, γ). The comparison of mRNA expression of the genes with the lipid profiles produced new insights into the FA metabolism and regulation during the development of turbot larvae, providing the basis for future studies including comparative approaches with other vertebrate species.

Regulation of FADS2 transcription by SREBP-1 and PPAR-α influences LC-PUFA biosynthesis in fish

“…Moreover, replacement with vegetable oil significantly up-regulated the transcription level of SREBP-1 in most cases, consistent with previous studies3354. Interestingly, in Japanese seabass fed vegetable oil, the two isotypes of PPAR-α showed different responses, which may indicate that functional differentiation has occurred since the gene duplication3355. In addition, the transcription level of PPAR-α was not significantly influenced by the dietary fatty acids in large yellow croaker.…”

Cloning and characterization of SREBP-1 and PPAR-α in Japanese seabass Lateolabrax japonicus, and their gene expressions in response to different dietary fatty acid profiles

“…This indicated the possible functional differentiation between Japanese seabass PPAR-α1 and PPAR-α2. The tissues with high PPAR-α1 expression are the main places for LC-PUFA synthesis in fish, indicating the possible involvement of fish PPAR-α1 in LC-PUFA synthesis, while the tissue expression pattern of PPAR-α2 could be related to its roles in hydrolysis of triglyceride and phospholipid (Cunha et al, 2013).…”

“…However, the DNA-binding domain, which determines the target gene and consequently the function of PPAR, was highly conserved between Japanese seabass PPAR-α1 and PPAR-α2, indicating that even a slight variation in the critical area of gene sequence may lead to functional distributions of PPAR-α proteins. The studies on turbot larvae also suggested that the different transcription profile observed in the two PPARα isoforms is probably indicative of a gene sub-functionalization (Cunha et al, 2013).…”

“…The critical roles of SREBP-1 and PPAR-α in lipid/fatty acid homeostasis makes the study on fish SREBP-1 and PPAR-α indispensable for the research into lipid and fatty acid nutrition of fish (Chinetti et al, 2000;Horton, 2002;Horton et al, 2002;Ibabe et al, 2002;Nakamura et al, 2004;Minghetti et al, 2011;Cunha et al, 2013).…”

Effects of the PPARα agonist WY-14,643 on plasma lipids, enzymatic activities and mRNA expression of lipid metabolism genes in a marine flatfish, Scophthalmus maximus

“…Genes involved in the fatty acid metabolism and in lipid transport were characterized in the early developmental stages of turbot larvae, and showed early mRNA expression related to the pattern of lipid class variation and a potential regulation by various PPAR receptors (Cunha et al, 2013). In the present exposure experiment with turbot juveniles, overall, few genes of the fatty acid and lipid metabolism were responsive to the treatment and the majority of genes remained unchanged, which is in accordance to the refractory response of rainbow trout to clofibric acid (Sovadinova et al, 2014).…”