| First Author | Virolle T | Year | 1998 |
| Journal | J Biol Chem | Volume | 273 |
| Issue | 28 | Pages | 17318-25 |
| PubMed ID | 9651314 | Mgi Jnum | J:48729 |
| Mgi Id | MGI:1274922 | Doi | 10.1074/jbc.273.28.17318 |
| Citation | Virolle T, et al. (1998) Three activator protein-1-binding sites bound by the Fra-2.JunD complex cooperate for the regulation of murine laminin alpha3A (lama3A) promoter activity by transforming growth factor-beta. J Biol Chem 273(28):17318-25 |
| abstractText | Several lines of evidence suggest a role for laminin-5 in skin wound healing. We report here that transforming growth factor-beta (TGF-beta), which elicits various responses during cutaneous healing, stimulates transcription of the mouse laminin alpha3A (lama3A) gene. To identify the TGF-beta-responsive elements (TGFbeta-REs) on the lama3A promoter, we have generated a series of 5'-deletions of the promoter upstream of the beta-galactosidase reporter gene. Transient cell transfection assays using mouse PAM212 keratinocytes revealed that TGFbeta-REs lie between nucleotides -297 and -54 relative to the transcription start site. Insertion of the TGFbeta-RE in front of the unre-sponsive minimal SV40 promoter conferred TGF-beta inducibility. Computer analysis of the promoter sequence identified three canonical activator protein-1 (AP-1) sites located at nucleo- tides -277 (AP-1A), -125 (AP-1B), and -69 (AP-1C). Site-directed mutagenesis of either the AP-1A or AP-1C site did not drastically alter the basal activity of the lama3A promoter, but reduced TGF-beta responsiveness by 50%. Simultaneous mutation of these two AP-1 sites resulted in a 65% decline in the response to TGF-beta, suggesting a cooperative contribution of each site to the overall promoter activity. In contrast, mutation of the AP-1B site markedly reduced the basal activity of the lama3A promoter, indicating that this AP-1 site is essential for gene expression. Mobility shift assays demonstrated specific binding of Fra-2 and JunD to the AP-1 sites, suggesting for the first time a possible regulatory function for the Fra-2.JunD AP-1 complex in a basal keratinocyte-specific gene. |
