title: Identification of an upstream enhancer in the mouse laminin alpha 1 gene defining its high level of expression in parietal endoderm cells.
abstract: Laminin-1 is the major component of the embryonic basement membrane and consists of alpha1, beta1, and gamma1 chains. The expression of laminin-1 is induced in mouse F9 embryonal carcinoma cells upon differentiation into parietal endoderm through transcriptional up-regulation of the genes encoding these subunits. Here, we identified a 435-bp enhancer in the 5'-flanking region of the mouse laminin alpha1 (LAMA1) gene that activated its transcription in a differentiation-dependent manner. This enhancer was also active in PYS-2 parietal yolk sac-derived cells but not in NIH/3T3 fibroblasts, indicating that it was a parietal endoderm-specific enhancer. This enhancer was also active in Engelbreth-Holm-Swarm (EHS) tumor-derived cells characterized by excessive production of laminin-1 and other basement membrane components, suggesting that EHS tumors have a transcriptional control mechanism similar to that of parietal endoderm cells. Electrophoretic mobility shift analyses revealed four protein binding sites (PBS1-PBS4) in the 435-bp region. However, these DNA-binding proteins were detected not only in parietal endoderm cells (i.e. differentiated F9 cells, PYS-2 cells, and EHS tumor-derived cells) but also in undifferentiated F9 cells and NIH/3T3 cells. Mutational analyses revealed that three of these binding sites (PBS2, PBS3, and PBS4) function synergistically to confer the parietal endoderm-specific enhancer activity. The proteins binding to PBS2 and PBS4 were identified as the Sp1/Sp3 family of transcription factors and YY1, respectively.
authors.affiliation: Sekiguchi Biomatrix Signaling Project, ERATO, Japan Science and Technology Corporation, Karimata, Yazako, Nagakute, Aichi 480-1195, Japan.
authors.forename: Tomoaki
authors.initials: T
authors.lastname: Niimi
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Hayashi
authors.forename: Kiyotoshi
authors.initials: K
authors.lastname: Sekiguchi
mesh_terms: D016475:3T3 Cells; D000818:Animals; D001483:Base Sequence; D002454:Cell Differentiation; D002467:Cell Nucleus / Q000378:metabolism; D004247:DNA / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism; D004707:Endoderm / Q000166:cytology*; D004742:Enhancer Elements, Genetic; D017930:Genes, Reporter; D007797:Laminin / Q000235:genetics*; D008156:Luciferases / Q000378:metabolism; D051379:Mice; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D010957:Plasmids / Q000378:metabolism; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D016329:Sp1 Transcription Factor / Q000378:metabolism; D051705:Sp3 Transcription Factor; D014157:Transcription Factors / Q000378:metabolism; D015533:Transcriptional Activation; D014162:Transfection; D014407:Tumor Cells, Cultured
chemical_list: D004268:DNA-Binding Proteins; D007797:Laminin; D016329:Sp1 Transcription Factor; C497122:Sp3 protein, mouse; D014157:Transcription Factors; D051705:Sp3 Transcription Factor; C084098:laminin A; D004247:DNA; D008156:Luciferases