The intricate interplay between cellular circadian rhythms,primarily manifested in the chloroplast redox oscillations-characterized by diel hyperoxidation/reduction cycles of 2-Cys peroxiredoxins-and the nuclear trans...The intricate interplay between cellular circadian rhythms,primarily manifested in the chloroplast redox oscillations-characterized by diel hyperoxidation/reduction cycles of 2-Cys peroxiredoxins-and the nuclear transcription/translation feedback loop(TTFL)machinery within plant cells,demonstrates a remarkable temporal coherence.However,the molecular mechanisms underlying the integration of these circadian rhythms remain elusive.In this study,we reveal that the chloroplast redox protein,NADPH-dependent thioredoxin reductase type C(NTRC),modulates the integration of the chloroplast redox rhythms and nuclear circadian clocks by regulating intracellular levels of reactive oxygen species and sucrose.In NTRC-deficient ntrc mutants,the perturbed temporal dynamics of cytosolic metabolite pools substantially attenuate the amplitude of CIRCADIAN CLOCK ASSOCIATED 1(CCA1)mRNA oscillation while maintaining its inherent periodicity.In contrast,these fluctuations extend the period and greatly reduced the amplitude of GIGANTEA(GI).In alignment with its regulatory role,the chloroplast redox rhythm and TTFL-driven nuclear oscillators are severely disrupted in ntrc plants.The impairements are rescued by NTRC expression but not by the expression of catalytically inactive NTRC(C/S)mutant,indicating that NTRC’s redox activity is essential for synchronizing intracellular circadian rhythms.In return,the canonical nuclear clock component,TIMING OF CAB EXPRESSION 1(TOC1),regulates the diel chloroplast redox rhythm by controlling NTRC expression,as evidenced by the redox cycle of chloroplast 2-Cys peroxiredoxins.This reciprocal regulation suggests a tight coupling between chloroplast redox rhythms and nuclear oscillators.Collectively,our study has identified NTRC as a key circadian modulator,elucidating the intricate connection between the metabolite-dependent chloroplast redox rhythm and the temporal dynamics of nuclear canonical clocks.展开更多
Dehydrating stresses trigger the accumulation of abscisic acid(ABA),a key plant stress-signaling hormone that activates Snf1-Related Kinases(SnRK2s)to mount adaptive responses.However,the regulatory circuits that term...Dehydrating stresses trigger the accumulation of abscisic acid(ABA),a key plant stress-signaling hormone that activates Snf1-Related Kinases(SnRK2s)to mount adaptive responses.However,the regulatory circuits that terminate the SnRK2s signal relay after acclimation or post-stress conditions remain to be defined.Here,we show that the desensitization of the ABA signal is achieved by the regulation of OST1(SnRK2.6)protein stability via the E3-ubiquitin ligase HOS15.Upon ABA signal,HOS15-induced degradation of OST1 is inhibited and stabilized OST1 promotes the stress response.When the ABA signal terminates,protein phosphatases ABI1/2 promote rapid degradation of OST1 via HOS15.Notably,we found that even in the presence of ABA,OST1 levels are also depleted within hours of ABA signal onset.The unexpected dynamics of OST1 abundance are then resolved by systematic mathematical modeling,demonstrating a desensitizing feedback loop by which OST1-induced upregulation of ABI1/2 leads to the degradation of OST1.This model illustrates the complex rheostat dynamics underlying the ABA-induced stress response and desensitization.展开更多
Laser speckle imaging is a common technique to monitor blood flow.The fluctuations in speckle intensity can be related to the blood flow by calculating the speckle contrast,the ratio between the standard deviation of ...Laser speckle imaging is a common technique to monitor blood flow.The fluctuations in speckle intensity can be related to the blood flow by calculating the speckle contrast,the ratio between the standard deviation of speckle fluctuations and the average intensity.However,this simple statistic calculation is easily affected by motion artifacts.In this study,we applied sample entropy analysis instead of calculating standard deviations of the speckle fluctuations.Similar to the traditional method,sample entropy-based speckle contrast increases linearly with flow rate but was shown to be more immune to sudden movements during an upper arm occlusion test.展开更多
The phytohormone abscisic acid(ABA)regulates multiple physiological processes such as embryo morphogenesis,seed maturation and germination,leaf senescence,fruit ripening,and stress adaptation(Gupta et al.,2020).ABA le...The phytohormone abscisic acid(ABA)regulates multiple physiological processes such as embryo morphogenesis,seed maturation and germination,leaf senescence,fruit ripening,and stress adaptation(Gupta et al.,2020).ABA levels quickly rise in response to conditions leading to water deficit,including the developmental processes of seed drying and dormancy,as well as early post-germinative growth(Chen et al.,2020).Several proteins,commonly regarded as the ABA signaling core components,have been identified.展开更多
基金supported by the National Research Foundation of Korea(NRF)grants funded by the MSIT(grant nos.2021R1A2C1093478 and 2022R1A5A1031361 to S.Y.L.)by the Basic Science Research Program of NRF funded by the Ministry of Education(RS-2024-00462888 to S.K.P.+1 种基金NRF-2022R111A1A01065660 to H.B.C.RS-2023-00250106 to S.D.W.).
文摘The intricate interplay between cellular circadian rhythms,primarily manifested in the chloroplast redox oscillations-characterized by diel hyperoxidation/reduction cycles of 2-Cys peroxiredoxins-and the nuclear transcription/translation feedback loop(TTFL)machinery within plant cells,demonstrates a remarkable temporal coherence.However,the molecular mechanisms underlying the integration of these circadian rhythms remain elusive.In this study,we reveal that the chloroplast redox protein,NADPH-dependent thioredoxin reductase type C(NTRC),modulates the integration of the chloroplast redox rhythms and nuclear circadian clocks by regulating intracellular levels of reactive oxygen species and sucrose.In NTRC-deficient ntrc mutants,the perturbed temporal dynamics of cytosolic metabolite pools substantially attenuate the amplitude of CIRCADIAN CLOCK ASSOCIATED 1(CCA1)mRNA oscillation while maintaining its inherent periodicity.In contrast,these fluctuations extend the period and greatly reduced the amplitude of GIGANTEA(GI).In alignment with its regulatory role,the chloroplast redox rhythm and TTFL-driven nuclear oscillators are severely disrupted in ntrc plants.The impairements are rescued by NTRC expression but not by the expression of catalytically inactive NTRC(C/S)mutant,indicating that NTRC’s redox activity is essential for synchronizing intracellular circadian rhythms.In return,the canonical nuclear clock component,TIMING OF CAB EXPRESSION 1(TOC1),regulates the diel chloroplast redox rhythm by controlling NTRC expression,as evidenced by the redox cycle of chloroplast 2-Cys peroxiredoxins.This reciprocal regulation suggests a tight coupling between chloroplast redox rhythms and nuclear oscillators.Collectively,our study has identified NTRC as a key circadian modulator,elucidating the intricate connection between the metabolite-dependent chloroplast redox rhythm and the temporal dynamics of nuclear canonical clocks.
文摘Dehydrating stresses trigger the accumulation of abscisic acid(ABA),a key plant stress-signaling hormone that activates Snf1-Related Kinases(SnRK2s)to mount adaptive responses.However,the regulatory circuits that terminate the SnRK2s signal relay after acclimation or post-stress conditions remain to be defined.Here,we show that the desensitization of the ABA signal is achieved by the regulation of OST1(SnRK2.6)protein stability via the E3-ubiquitin ligase HOS15.Upon ABA signal,HOS15-induced degradation of OST1 is inhibited and stabilized OST1 promotes the stress response.When the ABA signal terminates,protein phosphatases ABI1/2 promote rapid degradation of OST1 via HOS15.Notably,we found that even in the presence of ABA,OST1 levels are also depleted within hours of ABA signal onset.The unexpected dynamics of OST1 abundance are then resolved by systematic mathematical modeling,demonstrating a desensitizing feedback loop by which OST1-induced upregulation of ABI1/2 leads to the degradation of OST1.This model illustrates the complex rheostat dynamics underlying the ABA-induced stress response and desensitization.
基金GIST Research Institute(GRI)funded by GIST in 2019 and 2020Brain Research Program(2016M3C7A1905475)+1 种基金Basic Research Program(2018R1A2B6006797)through the National Research Foundation of Korea(NRF)funded by Ministry of Science and ICTKBRI basic research program through Korea Brain Research Institute funded by Ministry of Science and ICT(21-BR-03-05)。
文摘Laser speckle imaging is a common technique to monitor blood flow.The fluctuations in speckle intensity can be related to the blood flow by calculating the speckle contrast,the ratio between the standard deviation of speckle fluctuations and the average intensity.However,this simple statistic calculation is easily affected by motion artifacts.In this study,we applied sample entropy analysis instead of calculating standard deviations of the speckle fluctuations.Similar to the traditional method,sample entropy-based speckle contrast increases linearly with flow rate but was shown to be more immune to sudden movements during an upper arm occlusion test.
基金supported by Next Generation Bio-Green21 Program,Rural Development Administration(RDA),Republic of Korea(SSAC,PJ01318201 to D.-J.Y.and PJ01318205 to J.M.P.)the National Research Foundation of Korea(NRF)funded by the Korean Government(2019R1A2C2084096)Global Research Lab(2017K1A1A2013146).
文摘The phytohormone abscisic acid(ABA)regulates multiple physiological processes such as embryo morphogenesis,seed maturation and germination,leaf senescence,fruit ripening,and stress adaptation(Gupta et al.,2020).ABA levels quickly rise in response to conditions leading to water deficit,including the developmental processes of seed drying and dormancy,as well as early post-germinative growth(Chen et al.,2020).Several proteins,commonly regarded as the ABA signaling core components,have been identified.
