Ca2+ oscillation frequency regulates agonist-stimulated gene expression in vascular endothelial cells

A physiological membrane-receptor agonist typically stimulates oscillations, of varying frequencies, in cytosolic Ca(2+) concentration ([ Ca(2+)](i)). Whether and how [ Ca(2+)](i) oscillation frequency regulates agonist-stimulated downstream events, such as gene expression, in non-excitable cells remain unknown. By precisely manipulating [ Ca(2+)](i) oscillation frequency in histamine-stimulated vascular endothelial cells ( ECs), we demonstrate that the gene expression of vascular cell adhesion molecule 1 ( VCAM1) critically depends on [ Ca(2+)](i) oscillation frequency in the presence, as well as the absence, of histamine stimulation. However, histamine stimulation enhanced the efficiency of [ Ca(2+)](i)-oscillation-frequency-regulated VCAM1 gene expression, versus [ Ca(2+)](i) oscillations alone in the absence of histamine stimulation. Furthermore, a [ Ca(2+)](i) oscillation frequency previously observed to be the mean frequency in histamine-stimulated ECs was found to optimize VCAM1 mRNA expression. All the above effects were abolished or attenuated by blocking histamine-stimulated generation of intracellular reactive oxygen species ( ROS), another intracellular signaling pathway, and were restored by supplementary application of a low level of H(2)O(2). Endogenous NF-kappa B activity is similarly regulated by [ Ca(2+)](i) oscillation frequency, as well as its cooperation with ROS during histamine stimulation. This study shows that [ Ca(2+)](i) oscillation frequency cooperates with ROS to efficiently regulate agonist-stimulated gene expression, and provides a novel and general strategy for studying [ Ca(2+)](i) signal kinetics in agonist-stimulated downstream events.