Caffeine modulates CREB-dependent gene expression in developing cortical neurons

The Ca(2+)/cAMP response element binding protein CREB mediates transcription of genes essential for the development and function of the central nervous system. Here we investigated the ability of caffeine to stimulate CREB-dependent gene transcription in primary cultures of developing mouse cortical neurons. Using the CREB-dependent reporter gene CRE-luciferase we show that stimulation of CREB activity by caffeine exhibits a bell-shaped dose-response curve. Maximal stimulation occurred at 10mM caffeine, which is known to release Ca(2+) from ryanodine sensitive internal stores. In our immature neuronal cultures, 10mM caffeine was more effective at stimulating CREB activity than depolarization with high extracellular KCl (50mM). Quantitative real-time PCR analysis demonstrated that transcripts derived from endogenous CREB target genes, such as the gene encoding brain-derived neurotrophic factor BDNF, are increased following caffeine treatment. The dose-response curves of CREB target genes to caffeine exhibited gene-specificity, highlighting the importance of promoter structure in shaping genomic responses to Ca(2+) signaling. In the presence of a weak depolarizing stimulus (10mM KCl), concentrations of caffeine relevant for premature infants undergoing caffeine treatment increased CRE-luciferase activity and Bdnf transcript levels. The ability of caffeine to enhance activity-dependent Bdnf expression may contribute to the neurological benefit observed in infants receiving caffeine treatment.