Neurogenin 3 recruits CBP co-activator to facilitate histone H3/H4 acetylation in the target gene INSM1

INSM1 is a downstream target gene of neurogenin 3 (ngn3). A promoter construct containing the -426/+40bp region transiently co-transfected into NIH-3T3 cells with a ngn3 expression plasmid resulted in a 12-fold increase in promoter activity. The ngn3/E47 heterodimer selectively binds and activates the E-box3 of the INSM1 promoter. The endogenous ngn3 and CREB-binding protein (CBP) co-activator occupy the INSM1 promoter, resulting in hyper-acetylation of histone H3/H4 chromatin in a human neuroblastoma cell line, IMR-32. Additionally, adenoviral ngn3 can induce endogenous INSM-1 expression in pancreatic ductal carcinoma-1 cells through the recruitment of CBP to the INSM1 promoter and increase the acetylation of the INSM1 promoter region.