The circadian clock: a manager of biochemical processes within the organism.
The periodic succession of night and day has influenced life on earth for millions of years. Many organisms have "internalized" this periodic change in the form of the circadian clock. Its main function is to organize the time course of biochemical, physiological and behavioural processes thereby optimizing an organism's performance in anticipating changing environmental conditions. Therefore, it is important to understand the underlying mechanisms that connect the core pacemaker, which is located in the suprachiasmatic nuclei (SCN) of the hypothalamus, with peripheral organs. Several laboratories set out to identify genes that are under the influence of the circadian clock. It appears that the circadian clock coordinates transcription of key metabolic pathways thereby orchestrating the time course of physiological and behavioural processes. We review these investigations and put our experiments, the comparison of gene expression in SCN tissue of Per2 mutant and wild-type mice, in the context of these findings.
Holzberg
D
D
Max-Planck-Institute for Experimental Endocrinology, Hannover, Germany.
Albrecht
U
U
D000818:Animals; D001683:Biological Clocks / Q000235:genetics*; D056926:CLOCK Proteins; D018797:Cell Cycle Proteins; D002478:Cells, Cultured / Q000502:physiology; D002940:Circadian Rhythm / Q000235:genetics*; D005347:Fibroblasts / Q000502:physiology; D005786:Gene Expression Regulation / Q000235:genetics* / Q000502:physiology; D008099:Liver / Q000502:physiology; D008322:Mammals; D051379:Mice; D008817:Mice, Mutant Strains / Q000235:genetics; D009206:Myocardium / Q000378:metabolism; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D056950:Period Circadian Proteins; D051381:Rats; D013493:Suprachiasmatic Nucleus / Q000502:physiology; D014018:Tissue Distribution / Q000235:genetics; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors
D018797:Cell Cycle Proteins; D009687:Nuclear Proteins; C513312:Per2 protein, mouse; C513311:Per2 protein, rat; D056950:Period Circadian Proteins; D015534:Trans-Activators; D014157:Transcription Factors; D056926:CLOCK Proteins; C538944:Clock protein, mouse; C538945:Clock protein, rat