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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
Author(s) -
Maldonado Alejandro,
Game Bryan A.,
Song Lanxi,
Huang Yan
Publication year - 2003
Publication title -
immunology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.297
H-Index - 133
eISSN - 1365-2567
pISSN - 0019-2805
DOI - 10.1046/j.1365-2567.2003.01694.x
Subject(s) - u937 cell , promoter , transfection , microbiology and biotechnology , activator (genetics) , transcription factor , matrix metalloproteinase , chemistry , stimulation , low density lipoprotein , electrophoretic mobility shift assay , receptor , biology , cell culture , gene expression , gene , biochemistry , endocrinology , genetics , cholesterol
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.