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Regulation of LXR by fatty acids, insulin, growth hormone and tumor necrosis factor-α in rainbow trout myocytes.
Cruz-Garcia, Lourdes; Sánchez-Gurmaches, Joan; Gutiérrez, Joaquim; Navarro, Isabel.
Afiliação
  • Cruz-Garcia L; Departament de Fisiologia, Facultat de Biologia, Universitat de Barcelona, 08028 Barcelona, Spain. lourdescruzg@gmail.com
Article em En | MEDLINE | ID: mdl-21635958
ABSTRACT
The liver X receptor (LXR) has recently been described in salmonids. In mammals, this receptor is already known as a transcriptional factor that regulates diverse aspects of cholesterol, fatty acid and carbohydrate metabolism in various tissues, including muscle. Here we examined LXR in trout myocytes. For this purpose, we analyzed LXR target gene expression and gene profile during myocyte development. In addition, we studied the transcriptional regulation of LXR by hormones, a pro-inflammatory mediator and unsaturated fatty acids. Trout myocytes were incubated with LXR agonists (T091317, 22(R)-hydroxycholesterol) and unsaturated fatty acids for 24h. Furthermore, differentiated myocytes were incubated with insulin and growth hormone (GH) for 3h, 6h and 18h, and with tumor necrosis factor-α (TNFα) for 24h. Samples were also obtained in various stages of cell differentiation. Our results demonstrate that lipoprotein lipase (LPL), fatty acid synthase (FAS), ATP-binding cassette transporter A1 (ABCA1), peroxisome proliferator-activated receptor-α and ß (PPARα, ß) are target genes of LXR in trout muscle. LXR agonists increased LXR expression, thereby indicating that this receptor is autoregulated. Unsaturated fatty acids downregulated LXR gene expression. This observation suggests a regulatory mechanism of these molecules on LXR-mediated fatty acid synthesis and uptake. TNFα did not modulate LXR gene transcription. Expression of the LXR gene was activated by insulin and GH. These results suggest that LXR may play a lipogenic role through insulin stimulation and a tendency to promote anabolic effects through GH on trout myocytes.
Assuntos

Texto completo: 1 Base de dados: MEDLINE Assunto principal: Hormônio do Crescimento / Fator de Necrose Tumoral alfa / Oncorhynchus mykiss / Fibras Musculares Esqueléticas / Ácidos Graxos / Receptores Nucleares Órfãos / Insulina Limite: Animals Idioma: En Ano de publicação: 2011 Tipo de documento: Article

Texto completo: 1 Base de dados: MEDLINE Assunto principal: Hormônio do Crescimento / Fator de Necrose Tumoral alfa / Oncorhynchus mykiss / Fibras Musculares Esqueléticas / Ácidos Graxos / Receptores Nucleares Órfãos / Insulina Limite: Animals Idioma: En Ano de publicação: 2011 Tipo de documento: Article