A short region containing an AP-1 binding site is essential for transforming growth factor-beta-induced c-jun gene expression in osteoblastic cells.
Transforming growth factor-beta (TGF-beta) is a multifunctional regulatory peptide that elicits different responses in different cell types. Much remains unknown about the pathway of intracellular TGF-beta signal transduction, but TGF-beta is known to induce expression of several genes by way of the transcription factor AP-1. We studied the mechanism that mediates TGF-beta-induced gene expression of c-jun, a component of AP-1, in MC3T3-E1 osteoblastic cells. To map in detail the corresponding responsive elements in the rat c-jun promoter, we generated a series of 5' deletion promoter/luciferase reporter gene constructs. Transient cell transfection assays identified the region located between positions -79 and -59 as being critical for the TGF-beta response and for the basal activity of the promoter. Gel mobility shift assays indicated specific binding of nuclear proteins to this 21-bp region of the c-jun promoter containing an AP-1 binding site. These results show that the AP-1-dependent mechanism is involved in TGF-beta-induced increase of c-jun induction, suggesting positive autoregulation of AP-1.
Hata
S
S
Shionogi Discovery Research Laboratories, Shionogi and Co., Ltd., Osaka, Japan. satoshi.hata@shionogi.co.jp
Shimizu
T
T
Fujimoto
M
M
D016475:3T3 Cells; D000818:Animals; D001665:Binding Sites; D002467:Cell Nucleus / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D017353:Gene Deletion; D016758:Genes, jun / Q000235:genetics*; D051379:Mice; D008957:Models, Genetic; D016297:Mutagenesis, Site-Directed; D010006:Osteoblasts / Q000378:metabolism*; D010957:Plasmids / Q000378:metabolism; D011401:Promoter Regions, Genetic; D016755:Proto-Oncogene Proteins c-jun / Q000378:metabolism*; D051381:Rats; D015398:Signal Transduction; D018808:Transcription Factor AP-1 / Q000378:metabolism*; D014162:Transfection; D016212:Transforming Growth Factor beta / Q000378:metabolism*
D016755:Proto-Oncogene Proteins c-jun; D018808:Transcription Factor AP-1; D016212:Transforming Growth Factor beta