Light, immediate-early genes, and circadian rhythms.
Many diverse behaviors exhibit clear circadian rhythms in their expression. In mammals, these rhythms originate from a neural circadian clock located in the suprachiasmatic nuclei (SCN). Recently, signaling pathways activated by light in the SCN have begun to be identified. A specific set of immediate-early genes is induced by light in the SCN, and their expression is correlated with the resetting of circadian behavioral rhythms. These light-regulated immediate-early genes offer multiple inroads into the biology of the SCN: first, they are functional markers for the activation of SCN neurons by light; second, they can direct us to the upstream light-activated (and clock-regulated) signal transduction pathways which mediate their induction; and finally, they encode transcription factor proteins which may play a role in the molecular mechanism of resetting the circadian clock.
Kornhauser
J M
JM
NSF Center for Biological Timing, Northwestern University, Evanston, Illinois 60208-3520, USA.
Mayo
K E
KE
Takahashi
J S
JS
D000818:Animals; D002940:Circadian Rhythm / Q000235:genetics*; D017362:Cyclic AMP Response Element-Binding Protein / Q000235:genetics; D017781:Genes, Immediate-Early / Q000235:genetics*; D006801:Humans; D008027:Light; D008967:Molecular Biology; D009474:Neurons / Q000502:physiology; D016760:Proto-Oncogene Proteins c-fos / Q000235:genetics; D015398:Signal Transduction / Q000235:genetics; D013493:Suprachiasmatic Nucleus / Q000502:physiology*
D017362:Cyclic AMP Response Element-Binding Protein; D016760:Proto-Oncogene Proteins c-fos