Characterization of a mitogen-response unit in the mouse lactoferrin gene promoter.
Lactoferrin is present in a variety of tissues and biological fluids; however, the amount differs significantly due to differential expressions. We have previously demonstrated that the mouse lactoferrin gene is regulated by estrogen through an estrogen-response DNA element located at -349, upstream from the transcription start site (+1). In this report, we characterized by deletion and mutation analyses a cluster of mitogen-response elements located between -80 and -40 of the mouse lactoferrin promoter. We demonstrated that the chimeric chloramphenicol acetyltransferase reporter constructs (the -103 to +1 sequence of the mouse lactoferrin gene) containing the mitogen-response unit of the lactoferrin gene were stimulated by cAMP, forskolin, 12-O-tetradecanoylphorbol-13-acetate, and epidermal growth factor/recombinant transforming growth factor-alpha (EGF/TGF-alpha) in a time- and dose-dependent manner. The sequence at position -52 to -40 (mLF-CRE) of the gene conferred transcriptional activation in the presence of forskolin, cyclic AMP, and 12-O-tetradecanoylphorbol-13-acetate in transiently transfected human endometrium carcinoma RL95-2 cells, whereas the region at -80 to -60 responded to EGF/TGF-alpha stimulation. Overexpression of the catalytic unit of protein kinase C or protein kinase A in the RL95-2 cells elevated the chloramphenicol acetyl-transferase activity of the reporter construct 5-6-fold. The mobility shift assay suggested that AP1 and CREB or related proteins participated in complex formation with the mLF-CRE, whereas different proteins bound to the EGF/TGF-alpha-response element.
Shi
H
H
Laboratory of Reproductive and Developmental Toxicology, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina 27709.
Teng
C T
CT
D000818:Animals; D001483:Base Sequence; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D004247:DNA; D004815:Epidermal Growth Factor / Q000378:metabolism; D006801:Humans; D007781:Lactoferrin / Q000235:genetics*; D051379:Mice; D008934:Mitogens / Q000494:pharmacology*; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000378:metabolism; D011493:Protein Kinase C / Q000378:metabolism; D012045:Regulatory Sequences, Nucleic Acid; D014407:Tumor Cells, Cultured
D017362:Cyclic AMP Response Element-Binding Protein; D008934:Mitogens; D009687:Nuclear Proteins; D004815:Epidermal Growth Factor; D004247:DNA; D017868:Cyclic AMP-Dependent Protein Kinases; D011493:Protein Kinase C; D007781:Lactoferrin