MAPK signaling and light-induced resetting of the circadian clock
Karl Obrietan (Department of Neuroscience, The Ohio State University)
(February 25, 2003 10:30 AM - 11:30 AM)
Circadian rhythms of behavior and physiology are observed in a variety of organisms. In mammals, the suprachiasmatic nuclei (SCN) of the hypothalamus function as the major biological clock. The inherent pacemaker activity of the SCN can be effectively regulated by changes in the environmental light cycle. This allows an animal to synchronize its internal clock with the ever-changing light cycle encountered over a seasonal/yearly basis. What are the cellular events that allow light to affect clock timing? Recent work has revealed that coordinated transcriptional oscillations are required for circadian rhythm generation and that light-activated signaling events entrain the clock by resetting transcriptional rhythms. Given these observations, a characterization of the intracellular signaling pathways and downstream transcription factors activated by light will be critical for understanding the functional properties of the circadian clock. I will present data examining the role of the p42/p44 mitogen-activated protein kinase (MAPK) signal transduction pathway as a cellular signaling intermediate that couples light to circadian clock entrainment. If there is time left over, I will also present data looking at mechanisms of Ca2+-induced gene expression in cortical neurons.