Differential activation of the murine laminin B1 gene promoter by RAR alpha, ROR alpha, and AP-1.

RAR alpha, ROR alpha and AP-1 activated the transcription of the murine laminin B1 gene promoter, which consists of three core elements. Cotransfection experiments showed that AP-1-activated transcription is further stimulated by RAR alpha, but not by ROR alpha. Additionally, it was demonstrated by promoter mutagenesis that all of the three core elements are required for transactivation by RAR alpha and ROR alpha, while any one of them is dispensable for AP-1-activated transcription. These results suggest that the modes of transactivation of the laminin B1 promoter are different among the three transactivators.