title: Dawn- and dusk-phased circadian transcription rhythms coordinate anabolic and catabolic functions in Neurospora.
abstract: BACKGROUND
  Circadian clocks control rhythmic expression of a large number of genes in coordination with the 24 hour day-night cycle. The mechanisms generating circadian rhythms, their amplitude and circadian phase are dependent on a transcriptional network of immense complexity. Moreover, the contribution of post-transcriptional mechanisms in generating rhythms in RNA abundance is not known.
  
  
  RESULTS
  Here, we analyzed the clock-controlled transcriptome of Neurospora crassa together with temporal profiles of elongating RNA polymerase II. Our data indicate that transcription contributes to the rhythmic expression of the vast majority of clock-controlled genes (ccgs) in Neurospora. The ccgs accumulate in two main clusters with peak transcription and expression levels either at dawn or dusk. Dawn-phased genes are predominantly involved in catabolic and dusk-phased genes in anabolic processes, indicating a clock-controlled temporal separation of the physiology of Neurospora. Genes whose expression is strongly dependent on the core circadian activator WCC fall mainly into the dawn-phased cluster while rhythmic genes regulated by the glucose-dependent repressor CSP1 fall predominantly into the dusk-phased cluster. Surprisingly, the number of rhythmic transcripts increases about twofold in the absence of CSP1, indicating that rhythmic expression of many genes is attenuated by the activity of CSP1.
  
  
  CONCLUSIONS
  The data indicate that the vast majority of transcript rhythms in Neurospora are generated by dawn and dusk specific transcription. Our observations suggest a substantial plasticity of the circadian transcriptome with respect to the number of rhythmic genes as well as amplitude and phase of the expression rhythms and emphasize a major role of the circadian clock in the temporal organization of metabolism and physiology.
authors.affiliation: Heidelberg University Biochemistry Center, Heidelberg, Germany. cigdem.sancar@bzh.uni-heidelberg.de.
authors.forename: Cigdem
authors.initials: C
authors.lastname: Sancar
authors.affiliation: Heidelberg University Biochemistry Center, Heidelberg, Germany. gencer.sancar@bzh.uni-heidelberg.de.
authors.forename: Gencer
authors.initials: G
authors.lastname: Sancar
authors.affiliation: Heidelberg University Biochemistry Center, Heidelberg, Germany. nati.ha@bzh.uni-heidelberg.de.
authors.forename: Nati
authors.initials: N
authors.lastname: Ha
authors.affiliation: Heidelberg University Biochemistry Center, Heidelberg, Germany. francois.cesbron@bzh.uni-heidelberg.de.
authors.forename: François
authors.initials: F
authors.lastname: Cesbron
authors.affiliation: Heidelberg University Biochemistry Center, Heidelberg, Germany. michael.brunner@bzh.uni-heidelberg.de.|University of Heidelberg Biochemistry Center, Im Neuenheimer Feld 328, Heidelberg, D-69120, Germany. michael.brunner@bzh.uni-heidelberg.de.
authors.forename: Michael
authors.initials: M
authors.lastname: Brunner
mesh_terms: D056926:CLOCK Proteins / Q000235:genetics / Q000378:metabolism; D002480:Cellulase / Q000378:metabolism; D002940:Circadian Rhythm / Q000235:genetics*; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D015966:Gene Expression Regulation, Fungal; D008954:Models, Biological; D009492:Neurospora crassa / Q000235:genetics* / Q000378:metabolism*; D012319:RNA Polymerase II / Q000378:metabolism; D012331:RNA, Fungal / Q000235:genetics / Q000378:metabolism; D013997:Time Factors; D014158:Transcription, Genetic
chemical_list: D005656:Fungal Proteins; D012331:RNA, Fungal; D056926:CLOCK Proteins; D012319:RNA Polymerase II; D002480:Cellulase