Transcriptional regulation of lysosomal acid lipase in differentiating monocytes is mediated by transcription factors Sp1 and AP-2.
Human lysosomal acid lipase (LAL) is a hydrolase required for the cleavage of cholesteryl esters and triglycerides derived from plasma lipoproteins. It is shown here that during monocyte to macrophage differentiation, the expression of LAL-mRNA is induced. This induction is dependent on protein kinase C activity and protein synthesis. The cell type-specific increase in LAL expression is further investigated in the THP-1 cell line with respect to transcriptional regulation. The human monocytic leukemia cell line THP-1 differentiates into macrophage-like cells when treated with phorbol esters. In order to determine the cis-acting elements necessary for both basal and phorbol 12-myristate-13 acetate (PMA)-enhanced promoter activity, we performed deletion analysis and reporter gene assays. A PMA responsive element has been identified between -182 bp and -107 bp upstream of the major transcription start site. Gel mobility shift assays demonstrated that binding of Sp1 and AP-2 to the LAL promoter is increased by PMA in THP-1 cells. Co-transfections with expression plasmids for Sp1 and AP-2 further emphasized the important role of these transcription factors in both basal and PMA-enhanced LAL expression. Our data suggest that differentiation dependent increase of lysosomal acid lipase (LAL) expression in THP-1 cells is mediated by a concerted action of Sp1 and AP-2.
Ries
S
S
Institute for Clinical Chemistry and Laboratory Medicine, University of Regensburg, D-93042 Regensburg, Germany.
Büchler
C
C
Langmann
T
T
Fehringer
P
P
Aslanidis
C
C
Schmitz
G
G
D002454:Cell Differentiation / Q000187:drug effects; D002460:Cell Line; D002874:Chromosome Mapping; D004268:DNA-Binding Proteins / Q000502:physiology*; D004789:Enzyme Activation; D015971:Gene Expression Regulation, Enzymologic; D006801:Humans; D008264:Macrophages / Q000166:cytology* / Q000187:drug effects / Q000201:enzymology; D009000:Monocytes / Q000166:cytology* / Q000187:drug effects / Q000201:enzymology; D011401:Promoter Regions, Genetic; D011493:Protein Kinase C / Q000378:metabolism; D011499:Protein Processing, Post-Translational; D012333:RNA, Messenger / Q000378:metabolism; D016329:Sp1 Transcription Factor / Q000502:physiology*; D002787:Sterol Esterase / Q000096:biosynthesis / Q000235:genetics*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D050656:Transcription Factor AP-2; D014157:Transcription Factors / Q000502:physiology*; D014158:Transcription, Genetic; D015854:Up-Regulation
D004268:DNA-Binding Proteins; D012333:RNA, Messenger; D016329:Sp1 Transcription Factor; D050656:Transcription Factor AP-2; D014157:Transcription Factors; D011493:Protein Kinase C; D002787:Sterol Esterase; D013755:Tetradecanoylphorbol Acetate