Transcriptional regulation of the GluR2 gene: Neural-specific expression, multiple promoters, and regulatory elements

Abstract

To understand how neurons control the expression of the AMPA receptor subunit GluR2, we cloned the 5 � proximal region of the rat gene and investigated GluR2 promoter activity by transient transfection. RNase protection and primer extension of rat brain mRNA revealed multiple transcription initiation sites from �340 to �481 bases upstream of the GluR2 AUG codon. The relative use of 5 � start sites was different in cortex and cerebellum, indicating complexity of GluR2 transcript expression among different sets of neurons. When GluR2 promoter activity was investigated by plasmid transfection into cultured cortical neurons, cortical glia, and C6 glioma cells, the promoter construct with the strongest activity, per transfected cell, was 29.4-fold ( � 3.7) more active in neurons than in non-neural cells. Immunostaining of cortical cultures showed that �97 % of the luciferase-positive cells also expressed the neuronal marker