In HepG2 the LXR-responsive elements (LXREs) in the promoters of fatty acid synthase (FAS) and its transcriptional activator, SREBP-1c, respond differently to RXR ligands

Karim Roder, Michael Schweizer

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

Treatment of the hepatoma cell line HepG2 with all-trans retinoc acid (RA) induced expression of both mRNA and protein of fatty acid synthase (FAS) and SREBP-1c, an important transcriptional activator for FAS. Transient transfection of HepG2 showed that the rat FAS and murine SREBP-1c promoters responded positively to 9 cis-RA and all-trans RA. Cotransfection experiments using a human expression vector for retinoid-X receptor α identified two cis-elements essential for the RA response of the FAS promoter: the NF-Y-binding CAAT-box at -100 and the SREBP/USF-binding element at –65, known to be involved in glucose/insulin and sterol regulation. A LXR/RXR heterodimer binding site (LXRE at -660) reported to be essential for FAS regulation during lipogenesis contributed marginally to the RA-dependent upregulation of the FAS promoter. However, the LXR/RXR heterodimer binding site at -234 (Yoshikawa T. et al., 2001) conferred the full RA response on the SREBP-1c promoter in HepG2. Our data clearly demonstrate the existence of functional differences in LXREs which may well imply different roles in vivo.
Original languageEnglish
Title of host publicationProceedings of The Physiological Society
Subtitle of host publicationLife Sciences 2007
PublisherThe Physiological Society
Publication statusPublished - 2007

Fingerprint Dive into the research topics of 'In HepG2 the LXR-responsive elements (LXREs) in the promoters of fatty acid synthase (FAS) and its transcriptional activator, SREBP-1c, respond differently to RXR ligands'. Together they form a unique fingerprint.

  • Cite this