第995回生物科学セミナー
Balance between phase shift and coupling among the SCN neurons determines adaptation to ambient light dark condition
Dr. Satchidananda Panda（Salk Institute for Biological Studies La Jolla, California, USA）
2014年08月01日(金) 15:00～16:30 理学部3号館3階326号室
Coupling among cell autonomous circadian oscillator neurons ensures robust rhythm in rest-activity that is relatively resistant to abrupt change in ambient light. The master regulator for such intercellular coupling is unknown. We took a genomic approach to find coupling mechanism with the hypothesis that light induced phase shift weakens coupling among SCN neurons and makes them labile to phase shift. We found that phase-shifting pulse of light transiently down-regulates Lhx1 expression in the SCN and its target coupling factors. Mice with reduced expression of Lhx1 in the oscillator neurons of the Suprachiasmatic nucleus have intact cell autonomous oscillators, but weakened coupling. This renders the mice susceptible to large phase shifts with change in ambient light and under constant darkness the activity-rest cycle dampens to arrhythmicity.
