Phase shifting the retinal circadian clock: xPer2 mRNA induction by light and dopamine.
A circadian clock is located in the retinal photoreceptors of the African clawed frog Xenopus laevis. These photoreceptor clocks are thought to govern a wide variety of output rhythms, including melatonin release and gene expression. Both light and dopamine phase shift the retinal clock in a phase-dependent manner. Two homologs of the Drosophila period gene have been cloned in Xenopus, and one of these (xPer2) is acutely regulated by light. Light and dopamine induce xPer2 mRNA in a similar manner. In addition, the increase of xPer2 mRNA in response to light and dopamine is the same at all times of day tested. In contrast, xPer1 mRNA exhibits circadian oscillations but is relatively insensitive to phase-shifting treatments of light or dopamine. Our data suggest that xPer2 functions as the molecular link between the light/dark cycle and the circadian clock.
Steenhard
B M
BM
Department of Cell Biology, Neurobiology, and Anatomy, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA.
Besharse
J C
JC
D015647:2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine / Q000494:pharmacology; D000818:Animals; D001683:Biological Clocks / Q000502:physiology*; D015152:Blotting, Northern; D002940:Circadian Rhythm / Q000502:physiology*; D004298:Dopamine / Q000378:metabolism* / Q000494:pharmacology; D018491:Dopamine Agonists / Q000494:pharmacology; D018492:Dopamine Antagonists / Q000494:pharmacology; D065127:Dopamine D2 Receptor Antagonists; D004330:Drosophila / Q000235:genetics; D029721:Drosophila Proteins; D005136:Eye Proteins / Q000235:genetics / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000187:drug effects / Q000502:physiology*; D066298:In Vitro Techniques; D008027:Light; D008297:Male; D009687:Nuclear Proteins / Q000235:genetics; D056950:Period Circadian Proteins; D010507:Periodicity; D020419:Photoreceptor Cells, Vertebrate / Q000378:metabolism; D019257:Quinpirole / Q000494:pharmacology; D012333:RNA, Messenger / Q000378:metabolism; D017447:Receptors, Dopamine D1 / Q000819:agonists; D017448:Receptors, Dopamine D2 / Q000819:agonists / Q000378:metabolism; D012160:Retina / Q000378:metabolism*; D012457:Salicylamides / Q000494:pharmacology; D029867:Xenopus Proteins; D014982:Xenopus laevis
D018491:Dopamine Agonists; D018492:Dopamine Antagonists; D065127:Dopamine D2 Receptor Antagonists; D029721:Drosophila Proteins; D005136:Eye Proteins; D009687:Nuclear Proteins; C539040:PER protein, Drosophila; C498845:Per2 protein, Xenopus; D056950:Period Circadian Proteins; D012333:RNA, Messenger; D017447:Receptors, Dopamine D1; D017448:Receptors, Dopamine D2; D012457:Salicylamides; D029867:Xenopus Proteins; D019257:Quinpirole; D015647:2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine; C045989:eticlopride; D004298:Dopamine