The Transcription Factor bHLH121 Interacts with bHLH105 (ILR3) and Its Closest Homologs to Regulate Iron Homeostasis in Arabidopsis

Gao, Fei; Robe, Kevin; Bettembourg, Mathilde; Navarro, Nathalia; Rofidal, Valérie; Santoni, Véronique; Gaymard, Frédéric; Vignols, Florence; Roschzttardtz, Hannetz; Izquierdo, Esther; Dubos, Christian

doi:10.1105/tpc.19.00541

Cited by 135 publications

(161 citation statements)

References 52 publications

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“…Therefore, it is plausible that bHLH11 directly represses the expression of IRT1 and FRO2 . Recently, Gao et al (2020) found that bHLH11 interacts with itself in yeast, implying that bHLH11 may function as a homodimer to regulate its target genes.…”

Section: Discussionmentioning

confidence: 99%

“…These four members regulate the expression of FER-LIKE IRON-DEFICIENCY-INDUCED TRANSCRIPTION FACTOR ( FIT ), bHLH Ib genes ( bHLH38 , bHLH39 , bHLH100 , and bHLH101 ) and POPEYE ( PYE ) (Zhang et al 2015; Li et al 2016; Liang et al 2017). Recently, three studies characterized the functions of bHLH121 (Kim et al 2019; Gao et al 2020; Lei et al 2020), and Lei et al (2020) found that bHLH121 is also directly regulated by bHLH IVc. FIT interacts with bHLH Ib TFs and they synergistically promote the expression of Fe-uptake associated genes IRT1 and FRO2 (Yuan et al 2008; Wang et al 2013).…”

Section: Introductionmentioning

confidence: 99%

“…bHLH105/ILR3 also functions as a negative regulator when it interacts with PYE (Tissot et al 2019). In contrast, bHLH121 is required for activation of numerous Fe deficiency responsive genes (Kim et al 2019; Gao et al 2020; Lei et al 2020). Moreover, both bHLH 121 and PYE interact with bHLH IVc to regulate Fe homeostasis in Arabidopisis (Long et al 2010; Selote et al 2015; Kim et al 2019; Tissot et al 2019; Gao et al 2020; Lei et al 2020).…”

Section: Introductionmentioning

confidence: 99%

“…In contrast, bHLH121 is required for activation of numerous Fe deficiency responsive genes (Kim et al 2019; Gao et al 2020; Lei et al 2020). Moreover, both bHLH 121 and PYE interact with bHLH IVc to regulate Fe homeostasis in Arabidopisis (Long et al 2010; Selote et al 2015; Kim et al 2019; Tissot et al 2019; Gao et al 2020; Lei et al 2020). There is also a similar Fe deficiency response signaling network in rice (Ogo et al 2007; Kobayashi 2013, 2019; Zhang et al 2017, 2020; Wang et al 2020; Li et al 2020).…”

Section: Introductionmentioning

confidence: 99%

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bHLH11 inhibits bHLH IVc proteins by recruiting the TOPLESS/TOPLESS-RELATED corepressors in Arabidopsis

Yang

Lei

et al. 2020

Preprint

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Iron (Fe) homeostasis is essential for plant growth and development. Although tremendous progress has been made in understanding the maintenance of Fe homeostasis in plants, the underlying molecular mechanisms remain elusive. Recently, bHLH11 was reported to function as a negative regulator. However, the molecular mechanism by which bHLH11 regulates Fe homeostasis is unclear. Here, we generated two bhlh11 loss-of-function mutants which displayed the enhanced sensitivity to excessive Fe. bHLH11 is located in the cytoplasm and nucleus due to lack of a nuclear location signal sequence, and its interaction partners, bHLH IVc transcription factors (TFs) (bHLH34, bHLH104, bHLH105 and bHLH115) facilitate its nuclear accumulation. bHLH11 exerts its negative regulation function by recruiting the corepressors TOPLESS/TOPLESS-RELATED. Moreover, bHLH11 antagonizes the transactivity of bHLH IVc TFs towards bHLH Ib genes (bHLH38, bHLH39, bHLH100 and bHLH101). This work indicates that bHLH11 is a crucial component of Fe homeostasis signaling network, playing a pivotal role in the fine-tuning of Fe homeostasis.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

bHLH11 inhibits bHLH IVc proteins by recruiting the TOPLESS/TOPLESS-RELATED corepressors in Arabidopsis

Yang

Lei

et al. 2020

Preprint

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“…A latest study found that AtFIT promotes the nuclear accumulation of AtbHLH39, an Arabidopsis homolog of OsIRO2, in Arabidopsis (Trofimov et al, 2019). Similarly, Arabidopsis bHLH IVc TFs promote the nuclear accumulation of AtbHLH121 which is required for the maintenance of Arabidopsis Fe homeostasis (Kim et al, 2019; Gao et al, 2020; Lei et al, 2020). Although we did not observe the localization change of OsIRO2 in response to Fe deficiency in our transient expression assays, the increased nuclear accumulation of OsIRO2 under Fe deficiency condition was observed by Wang et al (2020).…”

Section: Discussionmentioning

confidence: 99%

FER-LIKE FE DEFICIENCY-INDUCED TRANSCRIPTION FACTOR (OsFIT) interacts with OsIRO2 to regulate iron homeostasis

Liang

Zhang²,

et al. 2020

Preprint

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There are two Fe-uptake strategies for maintaining Fe homeostasis in plants. As a special graminaceous plant, rice applies both strategies. However, it remains unclear how these two strategies are regulated in rice. IRON-RELATED BHLH TRANSCRIPTION FACTOR 2 (OsIRO2) is critical for regulating Fe uptake in rice. In this study, we identified an interacting partner of OsIRO2, Oryza sativa FER-LIKE FE DEFICIENCY-INDUCED TRANSCRIPTION FACTOR (OsFIT), which encodes a bHLH transcription factor. The OsIRO2 protein is localized in the cytoplasm and nucleus, but OsFIT facilitates the accumulation of OsIRO2 in the nucleus. Loss-of-function mutations to OsFIT result in decreased Fe accumulation, severe Fe-deficiency symptoms, and disrupted expression of Fe-uptake genes. In contrast, OsFIT overexpression promotes Fe accumulation and the expression of Fe-uptake genes. Genetic analyses indicated that OsFIT and OsIRO2 function in the same genetic node. Further analysis suggested that OsFIT and OsIRO2 form a functional transcription activation complex to initiate the expression of Fe-uptake genes. Our findings provide a mechanism understanding of how rice maintains Fe homeostasis.One-sentence summaryOsFIT interacts with and facilitates the accumulation of OsIRO2 in the nucleus where the OsFIT-OsIRO2 transcription complex initiates the transcription of Fe deficiency responsive genes.

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Molecular Regulation of Iron Homeostasis in Plants

et al. 2023

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The Transcription Factor bHLH121 Interacts with bHLH105 (ILR3) and Its Closest Homologs to Regulate Iron Homeostasis in Arabidopsis

Cited by 135 publications

References 52 publications

bHLH11 inhibits bHLH IVc proteins by recruiting the TOPLESS/TOPLESS-RELATED corepressors in Arabidopsis

bHLH11 inhibits bHLH IVc proteins by recruiting the TOPLESS/TOPLESS-RELATED corepressors in Arabidopsis

FER-LIKE FE DEFICIENCY-INDUCED TRANSCRIPTION FACTOR (OsFIT) interacts with OsIRO2 to regulate iron homeostasis

Molecular Regulation of Iron Homeostasis in Plants

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