Transcription factor Sp1 functions as an anchor protein in gene transcription of human 12(S)-lipoxygenase

The signal transduction of human 12(S)-lipoxygenase and the regulation of gene activation, induced by epidermal growth factor (EGF), are discussed in this review article. Treatment of human epidermoid carcinoma A431 cells with EGF induces the gene expression of human 12(S)-lipoxygenase, and two Sp1 binding sites residing at -158 to -150 bp and -123 to -114 bp are essential in the mediation of EGF induction of the 12(S)-lipoxygenase gene. EGF induces MAPK activation in cells, followed by the activation of AP1. Thus, the biosynthesis of c-Jun is enhanced, which subsequently interacts with Sp1. c-Jun on Sp1/c-Jun complex is then recruited to gene promoter through the binding of Sp1 to Sp1-binding sites on gene promoter. Subsequent transactivation of the promoter activation of the human 12(S)-lipoxygenase gene is induced. In addition to the functional role of Sp1 in gene regulation of 12(S)-lipoxygenase, recent studies have also demonstrated that Sp1 acting as an anchor protein to recruit transcription factor c-Jun is essential for growth factor and/or phorbol ester-induced expression of several genes.