Transcriptional regulation of uncoupling protein-2 gene expression in L6 myotubes.
OBJECTIVE
To increase the understanding of the transcriptional regulation of UCP2 gene expression in skeletal muscle cells, we examined the effect of all-trans-retinoic acid (tRA), a ligand (after the conversion to 9-cis-RA) of the retinoid X receptor (RXR), and linolenic acid, a polyunsaturated fatty acid and peroxisome proliferator-activated receptors (PPARs) ligand, on the expression of UCP2 mRNA in cultured L6 myotubes.


METHODS
UCP2 gene expression in L6 myotubes was confirmed by Northern blot analysis. The time- and concentration-dependency of tRA and linolenic acid on UCP2 gene expression was assessed by dot blot quantification. The mRNA levels of PPAR subtypes (alpha, gamma and delta) were determined by RT-PCR.


RESULTS
tRA induced UCP2 gene expression in a time- and concentration-dependent manner. Similar to tRA, UCP2 mRNA was markedly increased by 0.5 mM linolenic acid. In L6 myotubes, PPARdelta mRNA was abundant, whereas PPARalpha mRNA was lower and PPARgamma mRNA was minimal.


CONCLUSIONS
UCP2 mRNA expression in L6 myotubes is up-regulated by tRA and linolenic acid, possibly through a mechanism involving PPAR and RXRs.
Hatakeyama
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Y
Department of Metabolic Diseases, Medicinal Biology Research Laboratories, Fujisawa Pharmaceutical Co. Ltd, Osaka, Japan. yoshifumi_hatakeyama@po.fujisawa.co.jp
Scarpace
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PJ
D000818:Animals; D015152:Blotting, Northern; D002478:Cells, Cultured; D017931:DNA Primers; D004305:Dose-Response Relationship, Drug; D005786:Gene Expression Regulation; D007473:Ion Channels; D026901:Membrane Transport Proteins; D024101:Mitochondrial Proteins; D018482:Muscle, Skeletal / Q000166:cytology*; D011506:Proteins / Q000235:genetics*; D012333:RNA, Messenger / Q000187:drug effects / Q000235:genetics; D051381:Rats; D018160:Receptors, Cytoplasmic and Nuclear / Q000008:administration & dosage; D018168:Receptors, Retinoic Acid / Q000187:drug effects / Q000235:genetics; D047488:Retinoid X Receptors; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014157:Transcription Factors / Q000008:administration & dosage / Q000187:drug effects / Q000235:genetics / Q000494:pharmacology; D014158:Transcription, Genetic; D014212:Tretinoin / Q000008:administration & dosage / Q000494:pharmacology; D000071246:Uncoupling Protein 2; D017962:alpha-Linolenic Acid / Q000008:administration & dosage / Q000494:pharmacology
D017931:DNA Primers; D007473:Ion Channels; D026901:Membrane Transport Proteins; D024101:Mitochondrial Proteins; D011506:Proteins; D012333:RNA, Messenger; D018160:Receptors, Cytoplasmic and Nuclear; D018168:Receptors, Retinoic Acid; D047488:Retinoid X Receptors; D014157:Transcription Factors; C000604391:Ucp2 protein, rat; D000071246:Uncoupling Protein 2; D017962:alpha-Linolenic Acid; D014212:Tretinoin