Induction of the Mouse κ-Opioid Receptor Gene by Retinoic Acid in P19 Cells

Jinhua Li,Sung Wook Park,Horace H Loh,Li-Na Wei

doi:10.1074/jbc.m200840200

Abstract

The mouse kappa-opioid receptor (KOR) gene is expressed in mouse embryonal carcinoma P19 cells and induced by retinoic acid (RA) within 24 h. An RA-responsive cis-acting element is identified within promoter I of the KOR gene. This element contains a GC box, a putative binding site for transcription factor Sp1. Enhanced binding of Sp1 to this GC box correlates with RA induction of KOR gene. Phosphatase inhibitor (sodium pyrophosphate) decreases RA induction of this promoter, whereas hypophosphorylation of Sp1 results in an increase in its DNA binding affinity to this promoter as demonstrated by in vitro gel retardation and in vivo chromatin immunoprecipitation assays. Consistently, the inhibitor of MEK, PD98058, dose-dependently enhances RA induction of this promoter, suggesting that the ERK signaling pathway is negatively involved in the RA induction of mouse KOR gene activities. Collectively, enhanced binding of Sp1 to promoter I of the KOR gene as a result of inhibiting the ERK pathway contributes to RA induction of this gene in P19.

Highlights

The mouse ␬-opioid receptor (KOR) gene has been isolated in several laboratories [16]
retinoic acid (RA) Induces KOR Gene Activity in P19 Cells—Previously, we showed that RA was a potent suppressor of KOR gene expression in P19 cells after a long term treatment (3–5 days), and the negative regulatory sequence of the KOR was located in an element of intron I of this gene [20, 21]
We have previously reported that the repression of the mouse KOR gene by RA treatment for a long duration in P19 cells was mediated by an Ikaros binding site located within intron I of this gene

Summary

Introduction

The mouse ␬-opioid receptor (KOR) gene has been isolated in several laboratories [16]. We have previously reported the activities of dual promoters of mouse KOR gene in the P19 cell line [19].

Results

Conclusion