Liver X receptor beta is the dominant LXR subtype in skeletal muscle
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ABSTRACT: Liver X receptors (LXRs) are important regulators of cholesterol, lipid and glucose metabolism and have been extensively studied in liver, macrophages and adipose tissue. However, their role in skeletal muscle is not yet fully elucidated and the functional role of each of the LXRM-NM-1 and LXRM-NM-2 subtypes in skeletal muscle is at present unknown. To study the importance of each of the receptor subtypes, myotube cultures derived from wild type (WT), LXRM-NM-1 and LXRM-NM-2 knockout (KO) mice were established. The present study shows that treatment with the unselective LXR agonist T0901317 increased mRNA levels of LXR target genes such as sterol regulatory element-binding transcription factor 1 (SREBF1), fatty acid synthase (FASN), stearoyl-CoA desaturase 1 (SCD1) and ATP-binding cassette transporter A1 (ABCA1) in myotubes established from WT and LXRM-NM-1 KO mice. However, only minor changes in expression level were observed for these genes after treatment with T0901317 in myotubes from LXRM-NM-2 KO mice. Gene expression analysis using Affymetrix NuGO Genechip arrays showed that few other genes than the classical, well known LXR target genes were regulated by LXR in skeletal muscle. Furthermore, functional studies using radiolabeled substrates showed that treatment with T0901317 increased lipogenesis and apoA1 dependent cholesterol efflux, in myotubes from WT and LXRM-NM-1 KO mice, but not LXRM-NM-2 KO mice. The data suggest that the lipogenic effects of LXRs, as well as the LXR-stimulated cholesterol efflux, are mainly mediated by LXRM-NM-2 in skeletal muscle. To study the importance of each of the receptor subtypes, myotube cultures derived from wild type (WT), LXRa and LXRb knockout (KO) mice were established. Sixteen samples were examined. Half the samples were treated with the unselective LXR agonist T0901317.
ORGANISM(S): Mus musculus
SUBMITTER: Guido Hooiveld
PROVIDER: E-GEOD-13192 | biostudies-arrayexpress |
REPOSITORIES: biostudies-arrayexpress
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