Activation of the mouse inositol 1,4,5-trisphosphate receptor type 1 promoter by AP-2

Inositol 1,4,5-trisphosphate receptor (IP3R) functions as a Ca2+ channel th at increases the intracellular Ca2+ upon binding to inositol trisphosphates . IP3R is expressed ubiquitously and consists of a multigene family. Since the type 1 IP3R (IP(3)R1) is highly expressed in the cerebellar Purkinje ce lls and moderately in hippocampus in the mammalian central nervous system ( CNS), it is regarded as a neural member of this gene family. In this work, we investigated transcriptional regulation of the mouse ip(3)r1 gene. A DNa seI footprinting assay demonstrated that a sequence from -95 to -75, design ated as box-II, was a binding site for a cerebellum-enriched factor. A cons ensus sequence for AP-2 was located in box-II. An electrophoretic mobility shift assay with anti-AP-2 antibody revealed that AP-2 is capable of bindin g to box-II. Deletion analysis of box-II showed that flanking sequences bes ide the box-II motif were required for the stable binding. We demonstrated by transient luciferase assay that exogenously expressed AP-2 activated box -II-dependent transcription. Moreover, we showed that endogenous AP-2 induc ed by retinoic acid also activated transcription via box-II in P19 cells. I n-situ hybridization of the mouse brain revealed that AP-2 was predominantl y expressed in the cerebellar Purkinje cells and hippocampal CAI region, wh ere IP(3)R1 is also highly expressed. From these observations, AP-2 binding to box-II is thought to be responsible for IP(3)R1 gene regulation in the CNS. (C) 1999 Elsevier Science B.V. All rights reserved.