Analysis of the Regulation of Target Genes by an<i>Arabidopsis</i>Heat Shock Transcription Factor, HsfA2

Nishizawa‐Yokoi, Ayako; Yoshida, Eriko; Yabuta, Yukinori; Shigeoka, Shigeru

doi:10.1271/bbb.80809

Cited by 64 publications

(50 citation statements)

References 27 publications

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“…A study of Hsf1's action on the circadian clock in mammalian cells was reported recently; however, the molecular mechanism remains unknown (44,45). In general, Hsfs have been described to target HSP genes via multiple HSE repeats in their promoters, and few studies exist where Hsfs regulate non-HSP genes (46)(47)(48). Importantly, mammalian Hsfs are known to control the expression of various developmental genes in addition to HSPs, and it recently has become clear that the stress-independent expression of HSF1 is crucial in oncogenesis (49, 50).…”

Section: Discussionmentioning

confidence: 99%

HsfB2b-mediated repression ofPRR7directs abiotic stress responses of the circadian clock

Kolmos

Chow

Pruneda‐Paz

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

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The circadian clock perceives environmental signals to reset to local time, but the underlying molecular mechanisms are not well understood. Here we present data revealing that a member of the heat shock factor (Hsf) family is involved in the input pathway to the plant circadian clock. Using the yeast one-hybrid approach, we isolated several Hsfs, including HEAT SHOCK FACTOR B2b (HsfB2b), a transcriptional repressor that binds the promoter of PSEUDO RESPONSE REGULATOR 7 (PRR7) at a conserved binding site. The constitutive expression of HsfB2b leads to severely reduced levels of the PRR7 transcript and late flowering and elongated hypocotyls. HsfB2b function is important during heat and salt stress because HsfB2b overexpression sustains circadian rhythms, and the hsfB2b mutant has a short circadian period under these conditions. HsfB2b is also involved in the regulation of hypocotyl growth under warm, short days. Our findings highlight the role of the circadian clock as an integrator of ambient abiotic stress signals important for the growth and fitness of plants.circadian clock | Hsf | heat compensation | salt tolerance T he circadian clock is an endogenous timing mechanism that ensures that daily rhythmic processes are synchronized with the environment. The circadian oscillator runs with a period of ∼24 h. It entrains to environmental signals, such as light and temperature, and in this way is able to anticipate daily environmental changes (1). Molecular genetics and modeling have revealed that the circadian system comprises several interconnected feedback loops involving multiple phase-specific gene products (2).In the model plant Arabidopsis, the morning feedback loops are composed of the major oscillator proteins CIRCADIAN CLOCK ASSOCIATED 1 (CCA1) and LATE ELONGATED HYPOCOTYL (LHY), which peak in abundance at dawn and activate the expression of early-late morning genes PSEUDO RESPONSE REGULATOR 9 (PRR9) and PRR7 (3). Pseudoresponse regulator (PRR) proteins are transcriptional repressors, and PRR9 and PRR7 close the morning loops by binding to the CCA1 and LHY promoters (4). The transcription of PRR9 is acutely activated by light, a feature that is not shared by PRR7 (3, 5). Disruption of either locus results in a mild clock phenotype, including an increased clock period of ∼1 h and an elongated hypocotyl (6-8). The double loss-of-function mutant exhibits a strong synergistic phenotype with free-running period lengths of up to 35 h and loss of temperature entrainment and compensation, indicating overlapping roles for PRR9 and PRR7 (3, 9, 10).The ambient environment influences the circadian clock in a number of different ways. Although the most well-studied input cue is light, temperature is a major zeitgeber as well (11). Brief pulses (from minutes to hours, depending on the intensity) result in acute responses from the clock. Importantly, the severity of such responses is time-dependent and gated by the oscillator (12-14). Longer durations of zeitgeber change can function as an entrainment signal and general...

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Section: Discussionmentioning

confidence: 99%

HsfB2b-mediated repression ofPRR7directs abiotic stress responses of the circadian clock

Kolmos

Chow

Pruneda‐Paz

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

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“…Two of these marker genes encode heat shock transcription factors HsfA2 and HsfB1, which are required for thermotolerance in vegetative tissues (Charng et al, 2007;Ikeda et al, 2011). The third was Bag6, which is one of the targets under the control of HsfA2 (Nishizawa-Yokoi et al, 2009) and implicated in pollen germination and tube growth in Arabidopsis (Cartagena et al, 2008). The inability to fully activate a transcriptional stress response provides a mechanistic explanation for the stress-sensitive pollen phenotype observed for cngc16 mutants.…”

Section: A Cngc16-dependent Transcriptional Responsementioning

confidence: 99%

A Cyclic Nucleotide-Gated Channel (CNGC16) in Pollen Is Critical for Stress Tolerance in Pollen Reproductive Development

et al. 2012

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Cyclic nucleotide-gated channels (CNGCs) have been implicated in diverse aspects of plant growth and development, including responses to biotic and abiotic stress, as well as pollen tube growth and fertility. Here, genetic evidence identifies CNGC16 in Arabidopsis (Arabidopsis thaliana) as critical for pollen fertility under conditions of heat stress and drought. Two independent transfer DNA disruptions of cngc16 resulted in a greater than 10-fold stress-dependent reduction in pollen fitness and seed set. This phenotype was fully rescued through pollen expression of a CNGC16 transgene, indicating that cngc16-1 and 16-2 were both loss-of-function null alleles. The most stress-sensitive period for cngc16 pollen was during germination and the initiation of pollen tube tip growth. Pollen viability assays indicate that mutant pollen are also hypersensitive to external calcium chloride, a phenomenon analogous to calcium chloride hypersensitivities observed in other cngc mutants. A heat stress was found to increase concentrations of 39,59-cyclic guanyl monophosphate in both pollen and leaves, as detected using an antibody-binding assay. A quantitative PCR analysis indicates that cngc16 mutant pollen have attenuated expression of several heat-stress response genes, including two heat shock transcription factor genes, HsfA2 and HsfB1. Together, these results provide evidence for a heat stress response pathway in pollen that connects a cyclic nucleotide signal, a Ca 2+ -permeable ion channel, and a signaling network that activates a downstream transcriptional heat shock response.

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“…117) Zat12 and HsfA2 regulate the expression of APX1 and APX2, respectively, through distinct routes, suggesting multiple routes even for the common pathway. 119,123,124) The expression of HsfA2 as well as its target genes, APX2 and heat shock protein 18.1-C1 (Hsp18.1-C1), is markedly low under non-stressed conditions, while it is rapidly and strongly induced by heat shock, HL, and ROS in Arabidopsis. 123) We recently found that the expression of HsfA2 was predominantly and directly regulated by two class A1 Hsf (HsfA1) isoforms, HsfA1d and HsfA1e, under heat shock and oxidative stress conditions.…”

Section: Common and Source-/kind-specific Ros Signaling Pathwaysmentioning

confidence: 99%

Cellular redox regulation, signaling, and stress response in plants

Shigeoka

Maruta

2014

Bioscience, Biotechnology, and Biochemistry

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Cellular and organellar redox states, which are characterized by the balance between oxidant and antioxidant pool sizes, play signaling roles in the regulation of gene expression and protein function in a wide variety of plant physiological processes including stress acclimation. Reactive oxygen species (ROS) and ascorbic acid (AsA) are the most abundant oxidants and antioxidants, respectively, in plant cells; therefore, the metabolism of these redox compounds must be strictly and spatiotemporally controlled. In this review, we provided an overview of our previous studies as well as recent advances in (1) the molecular mechanisms and regulation of AsA biosynthesis, (2) the molecular and genetic properties of ascorbate peroxidases, and (3) stress acclimation via ROS-derived oxidative/redox signaling pathways, and discussed future perspectives in this field.

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Analysis of the Regulation of Target Genes by anArabidopsisHeat Shock Transcription Factor, HsfA2

Cited by 64 publications

References 27 publications

HsfB2b-mediated repression ofPRR7directs abiotic stress responses of the circadian clock

HsfB2b-mediated repression ofPRR7directs abiotic stress responses of the circadian clock

A Cyclic Nucleotide-Gated Channel (CNGC16) in Pollen Is Critical for Stress Tolerance in Pollen Reproductive Development

Cellular redox regulation, signaling, and stress response in plants

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