Up‐regulation of matrix metalloproteinase‐1 expression in U937 cells by low‐density lipoprotein‐containing immune complexes requires the activator protein‐1 and the Ets motifs in the distal and the proximal promoter regions

• Published in: Immunology Vol. 109; no. 4; pp. 572 - 579
• Main Authors: Maldonado, Alejandro, Game, Bryan A., Song, Lanxi, Huang, Yan
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Science, Ltd 01-08-2003; Blackwell Science Inc
• Subjects: Antigen-Antibody Complex - immunology; Base Sequence; Blotting, Northern - methods; DNA - analysis; Electrophoretic Mobility Shift Assay - methods; Enzyme-Linked Immunosorbent Assay - methods; Gene Deletion; Humans; Lipoproteins, LDL - immunology; Matrix Metalloproteinase 1 - genetics; Matrix Metalloproteinase 1 - immunology; Mutation - genetics; Mutation - immunology; Original; Promoter Regions, Genetic - immunology; Proto-Oncogene Proteins - genetics; Proto-Oncogene Proteins - immunology; Proto-Oncogene Proteins c-ets; Transcription Factor AP-1 - immunology; Transcription Factors - genetics; Transcription Factors - immunology; Transcription, Genetic; Transfection; U937 Cells; Up-Regulation - immunology
• ISSN: 0019-2805; 1365-2567
• DOI: 10.1046/j.1365-2567.2003.01694.x

Summary
We reported previously that low‐density lipoprotein (LDL)‐containing immune complexes (LDL‐IC) stimulated matrix metalloproteinase‐1 (MMP‐1) expression in U937 histiocytes through Fc gamma receptor (FcγR)‐mediated extracellular signal‐regulated kinase pathway. The present study has explored the transcriptional mechanisms involved in the stimulation. Deletion analysis showed that LDL‐IC stimulated MMP‐1 promoter activity in cells transfected with the Construct 1 that contained a 4,334‐bp MMP‐1 promoter fragment, but had no effect in cells transfected with other constructs that had shorter MMP‐1 promoter (2685‐bp or less), suggesting that cis‐acting elements located between −4334 and −2685 are required for the promoter stimulation. The mutation study further indicated that the activator protein‐1 (AP‐1) (−3471) or Ets (−3836) motifs in this distal region were essential for the LDL‐IC‐stimulated MMP‐1 expression. Moreover, although above deletion analysis showed that LDL‐IC did not stimulate MMP‐1 promoter activity in cells transfected with constructs that contained the proximal AP‐1 (−72) and Ets (−88) in the promoter fragments that are 2685‐bp or less, the mutations of the −72 AP‐1 or the −88 Ets motif in the construct 1 abolished the stimulation of MMP‐1 expression by LDL‐IC, suggesting that a long promoter sequence is required for the −72 AP‐1 and −88 Ets motifs to be involved in the stimulation. Finally, electrophoretic mobility shift assay showed that LDL‐IC stimulated the activities of transcription factors AP‐1 and Ets. In conclusion, the present study shows that both the distal and proximal AP‐1 and Ets motifs are required for LDL‐IC‐stimulated MMP‐1 expression in U937 histiocytes.