title: HsfA1d and HsfA1e involved in the transcriptional regulation of HsfA2 function as key regulators for the Hsf signaling network in response to environmental stress.
abstract: Heat shock transcription factor A2 (HsfA2) acts as a key component of the Hsf signaling network involved in cellular responses to various types of environmental stress. However, the mechanism governing the regulation of HsfA2 expression is still largely unknown. We demonstrated here that a heat shock element (HSE) cluster in the 5'-flanking region of the HsfA2 gene is involved in high light (HL)-inducible HsfA2 expression. Accordingly, to identify the Hsf regulating the expression of HsfA2, we analyzed the effect of loss-of-function mutations of class A Hsfs on the expression of HsfA2 in response to HL stress. Overexpression of an HsfA1d or HsfA1e chimeric repressor and double knockout of HsfA1d and HsfA1e Arabidopsis mutants (KO-HsfA1d/A1e) significantly suppressed the induction of HsfA2 expression in response to HL and heat shock (HS) stress. Transient reporter assays showed that HsfA1d and HsfA1e activate HsfA2 transcription through the HSEs in the 5'-flanking region of HsfA2. In the KO-HsfA1d/A1e mutants, 560 genes, including a number of stress-related genes and several Hsf genes, HsfA7a, HsfA7b, HsfB1 and HsfB2a, were down-regulated compared with those in the wild-type plants under HL stress. The PSII activity of KO-HsfA1d/A1e mutants decreased under HL stress, while the activity of wild-type plants remained high. Furthermore, double knockout of HsfA1d and HsfA1e impaired tolerance to HS stress. These findings indicated that HsfA1d and HsfA1e not only regulate HsfA2 expression but also function as key regulators of the Hsf signaling network in response to environmental stress.
authors.affiliation: Department of Advanced Bioscience, Faculty of Agriculture, Kinki University, 3327-204 Nakamachi, Nara 631-8505, Japan.
authors.forename: Ayako
authors.initials: A
authors.lastname: Nishizawa-Yokoi
authors.forename: Ryota
authors.initials: R
authors.lastname: Nosaka
authors.forename: Hideki
authors.initials: H
authors.lastname: Hayashi
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Tainaka
authors.forename: Takanori
authors.initials: T
authors.lastname: Maruta
authors.forename: Masahiro
authors.initials: M
authors.lastname: Tamoi
authors.forename: Miho
authors.initials: M
authors.lastname: Ikeda
authors.forename: Masaru
authors.initials: M
authors.lastname: Ohme-Takagi
authors.forename: Kazuya
authors.initials: K
authors.lastname: Yoshimura
authors.forename: Yukinori
authors.initials: Y
authors.lastname: Yabuta
authors.forename: Shigeru
authors.initials: S
authors.lastname: Shigeoka
mesh_terms: D000064:Acclimatization / Q000528:radiation effects; D017360:Arabidopsis / Q000235:genetics* / Q000502:physiology / Q000528:radiation effects; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D004269:DNA, Bacterial / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism*; D004777:Environment; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant / Q000528:radiation effects; D055786:Gene Knockout Techniques; D017343:Genes, Plant / Q000235:genetics; D000076249:Heat Shock Transcription Factors; D006360:Heat-Shock Proteins / Q000235:genetics* / Q000378:metabolism*; D018869:Heat-Shock Response / Q000528:radiation effects; D008027:Light; D008954:Models, Biological; D016254:Mutagenesis, Insertional / Q000235:genetics / Q000528:radiation effects; D045332:Photosystem II Protein Complex / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism*; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism; D020218:Response Elements / Q000235:genetics; D015398:Signal Transduction / Q000235:genetics* / Q000528:radiation effects; D013312:Stress, Physiological / Q000528:radiation effects; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism*; D014158:Transcription, Genetic / Q000528:radiation effects; D015533:Transcriptional Activation / Q000235:genetics / Q000528:radiation effects
chemical_list: D029681:Arabidopsis Proteins; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins; C000620134:HSFA2 protein, Arabidopsis; C000620135:HSFB1 protein, Arabidopsis; D000076249:Heat Shock Transcription Factors; D006360:Heat-Shock Proteins; C000620133:HsfA1e protein, Arabidopsis; D045332:Photosystem II Protein Complex; D010940:Plant Proteins; D012097:Repressor Proteins; C036483:T-DNA; D014157:Transcription Factors