Fasting-induced hepatic production of DHEA is regulated by PGC-1alpha, ERRalpha, and HNF4alpha.
The transcriptional coactivator peroxisome proliferator-activated receptor-gamma coactivator (PGC)-1alpha is involved in the coordinate induction of changes in gene expression in the liver that enable a homeostatic response to alterations in metabolic state, environmental cues, and nutrient availability. In exploring the specific pathways under PGC-1alpha regulation in the liver, we have made the surprising observation that this coactivator can induce the expression of CYP11A1 and CYP17A1, key rate-limiting enzymes involved in the initial steps of steroidogenesis. Both of these enzymes function to produce C(19)-steroids, converting cholesterol into pregnenolone, and then to dehydroepiandrosterone (DHEA). Estrogen-related receptor (ERR)-alpha mediates PGC-1alpha's induction of CYP11A1 and binds within the first intron of the CYP11A1 gene. Both ERR-alpha and hepatocyte nuclear factor-4alpha are required for PGC-1alpha-mediated induction of CYP17A1, and specific binding sites for these receptors have been identified in the regulatory regions of this gene. The potential physiological significance of these observations was highlighted in rats where fasting induced hepatic expression of PGC-1alpha and CYP17A1 and was associated with an increase in hepatic levels of DHEA. These data suggest that DHEA could be playing a role as an intracellular signaling molecule involved in modulating hepatic activity in response to fasting conditions.
Grasfeder
Linda L
LL
Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, North Carolina 27710, USA.
Gaillard
Stephanie
S
Hammes
Stephen R
SR
Ilkayeva
Olga
O
Newgard
Christopher B
CB
Hochberg
Richard B
RB
Dwyer
Mary A
MA
Chang
Ching-Yi
CY
McDonnell
Donald P
DP
D000818:Animals; D002786:Cholesterol Side-Chain Cleavage Enzyme / Q000378:metabolism; D003687:Dehydroepiandrosterone / Q000378:metabolism*; D005786:Gene Expression Regulation; D006367:HeLa Cells; D006360:Heat-Shock Proteins / Q000378:metabolism*; D051557:Hepatocyte Nuclear Factor 4 / Q000378:metabolism*; D022781:Hepatocytes / Q000378:metabolism; D006801:Humans; D008099:Liver / Q000378:metabolism*; D008297:Male; D000071248:Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha; D051381:Rats; D017208:Rats, Wistar; D011960:Receptors, Estrogen / Q000378:metabolism*; D015398:Signal Transduction; D013254:Steroid 17-alpha-Hydroxylase / Q000378:metabolism; D013256:Steroids / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism*; D000097983:ERRalpha Estrogen-Related Receptor
D002786:Cholesterol Side-Chain Cleavage Enzyme; D003687:Dehydroepiandrosterone; D006360:Heat-Shock Proteins; D051557:Hepatocyte Nuclear Factor 4; D000071248:Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha; D011960:Receptors, Estrogen; D013254:Steroid 17-alpha-Hydroxylase; D013256:Steroids; D014157:Transcription Factors; D000097983:ERRalpha Estrogen-Related Receptor; C496592:HNF4A protein, human; C486497:PPARGC1A protein, human; C501892:CYP17A1 protein, human