Karacay Bahri, O'Dorisio M Sue, Summers Monica, Robinson Michael, Bonthius Daniel J
Division of Hematology/Oncology, Department of Pediatrics, University of Iowa Hospitals and Clinics, 200 Hawkins Drive-2526 JCP, Iowa City, IA 52242, USA.
Regul Pept. 2003 Nov 15;116(1-3):1-12. doi: 10.1016/s0167-0115(03)00170-8.
Vasoactive intestinal peptide (VIP) is a neurotransmitter with neurotropic effects. VIP functions through two distinct G-protein-coupled receptor subtypes (VPAC1 and VPAC2). We have demonstrated expression of VPAC1 in pediatric nervous system tumors, including medulloblastoma arising in the cerebellum and neuroblastoma arising in the adrenal medulla. More recently, we have reported the differentiation of neuroblastoma cells by upregulation of VIP type 1 receptor suggesting a role for VPAC1 in neuronal development. To understand the molecular mechanisms regulating VPAC1 expression in both cerebellum and adrenal medulla, we have cloned the human VPAC1 gene and sequenced 2.6-kb of the 5'-flanking sequence. Expression of the luciferase reporter gene under the control of this 2.6-kb human VPAC1 promoter was induced 35-fold in a human medulloblastoma cell line (DAOY) and 36-fold in a human neuroblastoma cell line (SKNSH). Analysis of 5'-unidirectional deletion derivatives of the 2.6-kb fragment demonstrated that a 241-bp sequence immediately upstream of the VPAC1 coding region retains high activity, suggesting that it contains the core promoter region. Quantitative RT-PCR analysis demonstrated that VPAC1 is expressed in mouse cerebellar and adrenal tissues. The VPAC1 promoter also directed expression of a reporter gene in cerebellum and adrenal medulla in transgenic mice. Along with our previous findings, these results suggest that VPAC1 may play a functional role in development of both cerebellum and adrenal medulla.
