The 5′2 promoter of the neuronal nitric oxide synthase dual promoter complex mediates inducibility by nerve growth factor

Abstract

Neuronal nitric oxide synthase (nNOS) is induced by nerve growth factor (NGF) in pheochromocytoma PC12 cells. Previous studies from our laboratory identified two closely linked promoters (designated 5′1 and 5′2) that mediate transcription of the human nNOS gene in the brain [J. Xie, P. Roddy, T.K. Rife, F. Murad, A.P. Young, Two closely linked but separable promoters for human neuronal nitric oxide synthase gene transcription, Proc. Natl. Acad. Sci. U. S. A. 92 (1995) 1242–1246]. In this report, we demonstrate that luciferase fusion genes under transcriptional control by the 5′1 and 5′2 dual promoter complex are inducible by NGF in stably transformed PC12 cells. In sharp contrast, neither epidermal growth factor (EGF) nor fibroblast growth factor 2 (FGF2) are able to significantly enhance the expression of NOS–luciferase fusion genes. Deletion studies indicate that the 5′2 promoter plays a major role in mediating NGF inducibility. The 5′2 promoter contains six potential Ets binding sites as well as four potential AP1 binding sites. Thus, it is possible that activation of Ets and/or AP1 transcription factors by the Ras–Raf–MAP kinase cascade contributes to the NGF-mediated induction of nNOS.