Circadian Rhythm

Not Following the Clock

Science's STKE  25 Sep 2001:
Vol. 2001, Issue 101, pp. tw348
DOI: 10.1126/stke.2001.101.tw348

Rodents and flies living in constant darkness are physically active for a period of time each ~24-hour period, a cycle that is driven by the animal's endogenous molecular clock. Williams et al. report that fruit flies with a null mutation in neurofibromatosis-1 (Nf1) show defects in rhythmic behavioral outputs and in the mitogen-activated protein kinase (MAPK) pathway, but not in the clock itself. The authors propose that one of the downstream genes of the clock in flies is Nf1, and that Nf1 signals through the Ras/MAPK pathway, possibly triggered by pigment-dispersing factor (PDF). These results, which now partly define the output pathway for the circadian clock in flies, may also illuminate the mechanism by which human Nf1 acts as a tumor suppressor.

J. A. Williams, H. S. Su, A. Bernards, J. Field, A. Sehgal, A circadian output in Drosophila mediated by Neurofibromatosis-1 and Ras/MAPK. Science 293, 2251-2256 (2001). [Abstract] [Full Text]