title: MRNA expression of genes regulating lipid metabolism in ringed seals (Pusa hispida) from differently polluted areas.
abstract: There is a growing concern about the ability of persistent organic pollutants (POPs) to influence lipid metabolism. Although POPs are found at high concentrations in some populations of marine mammals, for example in the ringed seal (Pusa hispida) from the Baltic Sea, little is known about the effects of POPs on their lipid metabolism. An optimal regulation of lipid metabolism is crucial for ringed seals during the fasting/molting season. This is a physiologically stressful period, during which they rely on the energy stored in their fat reserves. The mRNA expression levels for seven genes involved in lipid metabolism were analyzed in liver and/or blubber tissue from molting ringed seals from the polluted Baltic Sea and a less polluted reference location, Svalbard (Norway). mRNA expression of genes encoding peroxisome proliferator-activated receptors (PPAR) α and γ and their target genes acyl-coenzyme A oxidase 1 (ACOX1) and cluster of differentiation 36 (CD36) were analyzed in liver. mRNA expression level of genes encoding PPARβ, PPARγ and their target genes encoding fatty acid binding protein 4 (FABP4) and adiponectin (ADIPOQ) were measured in inner and middle blubber layers. In addition, we evaluated the influence of molting status on hepatic mRNA expression of genes encoding PPARs and their target genes in ringed seals from Svalbard. Our results show higher mRNA expression of genes encoding hepatic PPARγ and adipose PPARβ, FABP4, and ADIPOQ in the Baltic seals compared to the Svalbard seals. A positive relationship between mRNA expressions of genes encoding hepatic PPARγ, adipose FABP4, adipose ADIPOQ and ΣPOP concentrations was observed. These findings suggest that lipid metabolism may be affected by contaminant exposure in the Baltic population. mRNA expression of genes encoding PPARβ, PPARγ, FABP4 and ADIPOQ were similar between the mid and inner adipose layer. Hepatic mRNA expression of genes encoding PPARα and PPARγ was higher in the pre-molting individuals compared to the molting ones highlighting differential regulation of these metabolic sensors through the molting period.
authors: Norwegian Polar Institute, Fram Centre, 9296 Tromsø, Norway; University of Bergen, Department of Biology, 5020 Bergen, Norway.
authors: Martina Galatea
authors: MG
authors: Castelli
authors: University of Bergen, Department of Biology, 5020 Bergen, Norway.
authors: Marte
authors: M
authors: Rusten
authors: University of Bergen, Department of Biology, 5020 Bergen, Norway.
authors: Anders
authors: A
authors: Goksøyr
authors: Norwegian Polar Institute, Fram Centre, 9296 Tromsø, Norway. Electronic address: heli.routti@npolar.no.
authors: Heli
authors: H
authors: Routti
mesh_terms: D000273:Adipose Tissue / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism; D000818:Animals; D005260:Female; D005786:Gene Expression Regulation / Q000187:drug effects*; D050356:Lipid Metabolism / Q000235:genetics*; D008055:Lipids / Q000032:analysis; D008099:Liver / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism; D008297:Male; D047495:PPAR gamma / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D046048:Seals, Earless / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D008055:Lipids; D047495:PPAR gamma; D012333:RNA, Messenger; D014874:Water Pollutants, Chemical
keywords: ACOX1; ADIPOQ; Baltic Sea; CD36; FABP4; Lipid metabolism; NR; POPs; PPARα; PPARβ; PPARγ; Peroxisome proliferator-activated receptor; RXR; Ringed seal; TR; acyl-coenzyme A oxidase 1; adiponecin; cluster of differentiation 36; fatty acid binding protein 4; nuclear receptors; peroxisome proliferator-activated receptor alpha; peroxisome proliferator-activated receptor beta; peroxisome proliferator-activated receptor gamma; persistent organic pollutants; retinoid X receptor; thyroid hormone receptor