Dehydroepiandrosterone effects on the mRNA levels of peroxisome proliferator-activated receptors and their coactivators in human hepatoma HepG2 cells.
To investigate the effect of dehydroepiandrosterone (DHEA) on intracellular mRNA levels of peroxisome proliferator-activated receptors (PPARs) and PPAR-gamma coactivators (PGCs), we conducted a quantitative real-time RT-PCR study using HepG2 cells. Treatment with 100 micromol/l DHEA for 2-20 h caused a time-dependent elevation of mRNA levels in the cells. Upon 20 h, PPAR-alpha, -gamma1, and -gamma2 mRNAs and PGC-1alpha and -1beta mRNAs increased to 157, 161, 155, 656, and 475% of control levels, respectively (p < 0.05 each). Treatment with actinomycin D for 2.5-8 h revealed a significant stabilization effect of DHEA on PPAR-gamma1 and PGC-1alpha mRNAs at both 2.5 and 8 h incubation periods and a mild but significant stabilization effect on PGC-1beta mRNA at the 8 h incubation period suggesting that DHEA can modulate turnover of these mRNA transcripts. Basal mRNA levels of PPAR-alpha and PGC-1alpha were significantly suppressed upon 20 h treatment with cycloheximide, while those of PPAR-gamma1, -gamma2, and PGC-1beta were elevated. Cycloheximide also significantly reduced DHEA-induced accumulation of PPAR-alpha, -gamma1, -gamma2, and PGC-1alpha mRNAs, demonstrating the dependence of the DHEA action on de novo protein synthesis. The findings demonstrate that a supraphysiological concentration of DHEA can substantially influence gene expression of the PPAR signalling machinery at both transcriptional and posttranscriptional levels.
Poczatková
H
H
Department of Pathological Physiology, Medical Faculty, Palacky University, Hnevotínská 3, 775 15 Olomouc, Czech Republic. hanapoc@seznam.cz
Bogdanová
K
K
Uherková
L
L
Cervenková
K
K
Riegrová
D
D
Rypka
M
M
Veselý
J
J
D006528:Carcinoma, Hepatocellular / Q000235:genetics; D045744:Cell Line, Tumor; D003513:Cycloheximide / Q000494:pharmacology; D003609:Dactinomycin / Q000494:pharmacology; D003687:Dehydroepiandrosterone / Q000494:pharmacology*; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects*; D006801:Humans; D047492:Peroxisome Proliferator-Activated Receptors / Q000235:genetics*; D020033:Protein Isoforms / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism
D047492:Peroxisome Proliferator-Activated Receptors; D020033:Protein Isoforms; D012333:RNA, Messenger; D003609:Dactinomycin; D003687:Dehydroepiandrosterone; D003513:Cycloheximide