title: Ambient temperature signal feeds into the circadian clock transcriptional circuitry through the EC night-time repressor in Arabidopsis thaliana.
abstract: An interlocking multiloop model has been generally accepted to describe the transcriptional circuitry of core clock genes, through which robust circadian rhythms are generated in Arabidopsis thaliana. The circadian clock must have the ability to integrate ambient temperature signals into the clock transcriptional circuitry to regulate clock function properly. Clarification of the underlying mechanism is a longstanding subject in the field. Here, we provide evidence that temperature signals feed into the clock transcriptional circuitry through the evening complex (EC) night-time repressor consisting of EARLY FLOWERING 3 (ELF3, ELF4) and LUX ARRHYTHMO (LUX; also known as PCL1). Chromatin immunoprecipitation assays showed that PSEUDO-RESPONSE REGULATOR7 (PRR7), GIGANTEA (GI) and LUX are direct targets of the night-time repressor. Consequently, transcription of PRR9/PRR7, GI and LUX is commonly regulated through the night-time repressor in response to both moderate changes in temperature (Δ6°C) and differences in the steady-state growth-compatible temperature (16-28°C). A warmer temperature inhibits EC function more, whereas a cooler temperature stimulates it more. Consequently, the expression of these target genes is up-regulated in response to a warm temperature specifically during the dark period, whereas they are reversibly down-regulated in response to a cool temperature. Transcription of another EC target, the PIF4 (PHYTOCHROME-INTERACTING FACTOR 4) gene, is modulated through the same thermoregulatory mechanism. The last finding revealed the sophisticated physiological mechanism underlying the clock-controlled output pathway, which leads to the PIF4-mediated temperature-adaptive regulation of hypocotyl elongation.
authors: Laboratory of Molecular and Functional Genomics, School of Agriculture, Nagoya University, Furocho, Chikusa-ku, Nagoya, 464-8601 Japan.
authors: Takeshi
authors: T
authors: Mizuno
authors: Yuji
authors: Y
authors: Nomoto
authors: Haruka
authors: H
authors: Oka
authors: Miki
authors: M
authors: Kitayama
authors: Aya
authors: A
authors: Takeuchi
authors: Mayuka
authors: M
authors: Tsubouchi
authors: Takafumi
authors: T
authors: Yamashino
mesh_terms: D029681:Arabidopsis Proteins / Q000235:genetics*; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics; D057906:Circadian Clocks / Q000235:genetics*; D002940:Circadian Rhythm / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000235:genetics; D018506:Gene Expression Regulation, Plant; D008957:Models, Genetic; D030821:Plants, Genetically Modified; D011401:Promoter Regions, Genetic / Q000235:genetics; D012097:Repressor Proteins / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013696:Temperature; D013997:Time Factors; D014157:Transcription Factors / Q000235:genetics
chemical_list: D029681:Arabidopsis Proteins; D051792:Basic Helix-Loop-Helix Proteins; D004268:DNA-Binding Proteins; D012097:Repressor Proteins; D014157:Transcription Factors; C114425:CCA1 protein, Arabidopsis; C432430:At2g25930 protein, Arabidopsis; C465973:ELF4 protein, Arabidopsis; C121183:GI protein, Arabidopsis; C113192:LHY protein, Arabidopsis; C504848:Lux Arrhythmo protein, Arabidopsis; C459466:PIF4 protein, Arabidopsis; C523308:PRR7 protein, Arabidopsis; C514751:PRR9 protein, Arabidopsis
keywords: Arabidopsis thaliana; Circadian clock; Hypocotyl elongation; Pseudo-response regulator; Response to temperature; Transcription circuitry