Open AccessStructural and functional analysis of the promoter of the hepatic lipase gene
Author(s) -
Chang ShauFeng,
Scharf JensGerd,
Will Hans
Publication year - 1997
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1997.00148.x
Subject(s) - promoter , microbiology and biotechnology , biology , transcription factor , hepatocyte nuclear factors , transcription (linguistics) , gene , response element , hepatocyte , hepatocyte nuclear factor 4 , gene expression , genetics , in vitro , nuclear receptor , linguistics , philosophy
Hepatic lipase (HL) gene transcription is almost exclusively limited to hepatocytes. Here we have studied sequences and transcription factors regulating basal and hepatocyte‐restricted HL promoter activity. Sequencing of a cloned 3.4‐kb HL promoter fragment revealed three Alu repeat sequences and a consensus hepatocyte‐enriched nuclear transcription factor 1 (HNF1) binding site located upstream of one major and one minor transcription initiation site. By transfection of cell lines of hepatic and non‐hepatic origin and of primary hepatocyte cultures, sequences controlling basic HL promoter activity and negative elements located downstream and upstream thereof which extinguish or enhance this activity were defined. Some HL‐promoter fragments with internal deletions were active only in primary hepatocyte cultures. Human HNF1 protein was shown to bind to the HL‐specific HNF1 response element and the activity of a heterologous promoter was enhanced by HL‐HNF1 in rat primary hepatocyte cultures but not in the context of the authentic 3.4‐kb HL promoter sequences. In cell lines the presence of HNF4 but not of HNF1 and vHNF1 mRNA was found to correlate with HL gene expression although no perfect consensus HNF4 binding motif was detected in the promoter region tested. Taken together, these data indicate that hepatocyte‐specific HL gene transcription is controlled by positive and negative transcription regulatory proteins which bind to sequence motifs within and outside of the proximal 3.4‐kb promoter fragment studied. For the elucidation of the control of HL promoter activity in vivo the use of primary hepatocyte cultures is essential.