Estrogen receptor-mediated repression of human hepatic lipase gene transcription.
Estrogen replacement therapy in women decreases hepatic lipase (HL) activity, which may account for the associated increase in HDL cholesterol. To investigate whether estrogen decreases HL transcription, transient cotransfection assays with HL promoter and estrogen receptor-alpha (ERalpha) expression constructs were performed in HepG2 cells. 17beta-estradiol (E(2)) decreased transcription driven by the -1557/+41 human HL promoter by up to 50% at 10(-7) M. Mutation of ERalpha by deletion of its transactivation domains or ligand-binding domain eliminated E(2)-induced repression of the promoter, whereas deletion of the DNA-binding domain of ERalpha resulted in a 7-fold activation by E(2). The E(2)-induced repression was maintained after mutation of a potential estrogen-response element in the promoter. The region of estrogen responsiveness was localized to -1557/-1175 of the HL promoter by deletion analysis. Mutation of an AP-1 site at -1493 resulted in a partial loss of E(2)-induced repression, similar to that caused by deletion of nucleotides -1557 to -1366. Gel shift assays with nuclear extracts from E(2)-treated HepG2 cells stably expressing ERalpha demonstrated an increase in binding to an AP-1 consensus oligonucleotide. The AP-1 activator, phorbol 12-myristate 13-acetate, inhibited the HL promoter by greater than 50%. Collectively, the data suggest that estrogen represses the transcription of the HL gene, possibly through an AP-1 pathway.
Jones
Daniel R
DR
Lilly Research Laboratories, Cardiovascular Research Division, Eli Lilly and Company, Indianapolis, IN 46285, USA.
Schmidt
Robert J
RJ
Pickard
Richard T
RT
Foxworthy
Patricia S
PS
Eacho
Patrick I
PI
D020121:5' Untranslated Regions / Q000235:genetics / Q000502:physiology; D001665:Binding Sites / Q000502:physiology; D002460:Cell Line; D008076:Cholesterol, HDL / Q000378:metabolism; D004794:Enzyme Repression / Q000502:physiology*; D047628:Estrogen Receptor alpha; D015914:Estrogen Replacement Therapy / Q000009:adverse effects; D004967:Estrogens / Q000502:physiology; D005260:Female; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology*; D022781:Hepatocytes / Q000737:chemistry / Q000201:enzymology / Q000378:metabolism; D006801:Humans; D008049:Lipase / Q000096:biosynthesis* / Q000235:genetics; D008099:Liver / Q000201:enzymology*; D011401:Promoter Regions, Genetic / Q000235:genetics / Q000502:physiology; D012333:RNA, Messenger / Q000378:metabolism; D011960:Receptors, Estrogen / Q000235:genetics / Q000502:physiology*; D018808:Transcription Factor AP-1 / Q000502:physiology; D014162:Transfection
D020121:5' Untranslated Regions; D008076:Cholesterol, HDL; D047628:Estrogen Receptor alpha; D004967:Estrogens; D012333:RNA, Messenger; D011960:Receptors, Estrogen; D018808:Transcription Factor AP-1; D008049:Lipase