title: Circadian and photic regulation of phosphorylation of ERK1/2 and Elk-1 in the suprachiasmatic nuclei of the Syrian hamster.
abstract: In this study we investigated the circadian and photic regulation of phosphorylation of the extracellular signal-related kinase (ERK) 1/2, and the transcription factor Elk-1 in the suprachiasmatic nuclei of the Syrian hamster. We report that levels of phosphorylated ERK (P-ERK) are rhythmic, peaking during the mid subjective day, whereas phosphorylated Elk-1 (P-Elk-1) shows no distinct rhythm. Light pulses during the subjective night rapidly, but transiently, induce P-ERK, whereas P-Elk-1 is also induced, albeit with a slower time course. Application of the ERK pathway inhibitor U0126 attenuates photic induction of both P-ERK and P-Elk-1 and phase advances of wheel-running behavior. The NMDA receptor channel blocker, MK-801, also significantly attenuates photic induction of P-ERK and P-Elk-1. Taken together, these results indicate a role of the ERK cascade in the regulation of free-running circadian rhythms and of photic-resetting of these rhythms and suggest that in the mammalian suprachiasmatic nuclei, Elk-1 represents a novel molecular component of the photic-induction pathway.
authors.affiliation: School of Biological Sciences, University of Manchester, Manchester, United Kingdom M13 9PT.
authors.forename: Andrew N
authors.initials: AN
authors.lastname: Coogan
authors.forename: Hugh D
authors.initials: HD
authors.lastname: Piggins
mesh_terms: D000818:Animals; D001522:Behavior, Animal; D002070:Butadienes / Q000494:pharmacology; D002940:Circadian Rhythm; D006224:Cricetinae; D004268:DNA-Binding Proteins; D016291:Dizocilpine Maleate / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D008027:Light; D020935:MAP Kinase Signaling System; D008297:Male; D008647:Mesocricetus; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3; D020929:Mitogen-Activated Protein Kinase Kinases / Q000037:antagonists & inhibitors; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D009570:Nitriles / Q000494:pharmacology; D010766:Phosphorylation / Q000528:radiation effects; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism; D016194:Receptors, N-Methyl-D-Aspartate / Q000037:antagonists & inhibitors; D013493:Suprachiasmatic Nucleus / Q000201:enzymology / Q000378:metabolism* / Q000528:radiation effects; D014157:Transcription Factors; D050807:ets-Domain Protein Elk-1
chemical_list: D002070:Butadienes; D004268:DNA-Binding Proteins; D004791:Enzyme Inhibitors; D009570:Nitriles; D011518:Proto-Oncogene Proteins; D016760:Proto-Oncogene Proteins c-fos; D016194:Receptors, N-Methyl-D-Aspartate; D014157:Transcription Factors; C113580:U 0126; D050807:ets-Domain Protein Elk-1; D016291:Dizocilpine Maleate; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D020929:Mitogen-Activated Protein Kinase Kinases