Regulation of the rat p75 neurotrophin receptor promoter by GC element binding proteins.

Human and rat p75 neurotrophin receptor genes contain four conserved GC elements within their proximal promoter regions. These motifs are potentially recognized by many transcription factors. Here, we show that this proximal region of the rat gene is responsible for basal promoter function in both neuronal and non-neuronal cells. Coexpression of Wilms' tumor suppressor WT1 represses, whereas transcription factor Sp1 activates p75 promoter constructs in kidney cells. Furthermore, purified Sp1 protein binds with high affinity to p75 promoter elements as assayed by DNase I footprinting. These findings suggest an important role for the GC element binding proteins in the regulation of p75 promoter function.