The membrane-associated transcription factor, bZlP28, is relocated from the endoplasmic reticulum （ER） to the Golgi and proteolytically released from the membrane mediated by two proteases, SlP and S2P, in response ...The membrane-associated transcription factor, bZlP28, is relocated from the endoplasmic reticulum （ER） to the Golgi and proteolytically released from the membrane mediated by two proteases, SlP and S2P, in response to ER stress in Arabidopsis. The activated N-terminal domain recruits nuclear factor Y （NF-Y） subunits in the nucleus to regulate ER stress downstream genes. Little is known about the functions of the bZIP28 C-terminal lumen-facing domain. Here, we provide novel insights into how the ER lumen-facing domain affects the biological function and organelle-to-organelle movement of bZIP28 in the ER stress response. First, we demonstrated the functional redundancy of bZlP28 and bZIP60 by generation and analysis of the bZIP28 and bZIP60 double mutant zip28zip60. Subsequent genetic complementation experiments in zip28zip60 background with deletions on bZlP28 lumen-facing domain highlighted the importance of lumen-facing domain for its in vivo function of bZIP28 in the ER stress response. The protein subcellular localization and Western blotting results further revealed that the bZIP28 lumen-facing domain contains ER retention signal which is important for the proteolytic activation of bZIP28. Thus, the bZIP28 lumen-facing C-terminus plays important roles in the ER-to-Golgi movement of bZlP28, which may contribute to the sensing of the ER stress.展开更多
The endoplasmic reticulum(ER)is a cellular organelle responsible for protein synthesis and folding.When its protein folding capacity is exceeded,unfolded or misfolded proteins accumulate,causing ER stress and triggeri...The endoplasmic reticulum(ER)is a cellular organelle responsible for protein synthesis and folding.When its protein folding capacity is exceeded,unfolded or misfolded proteins accumulate,causing ER stress and triggering the unfolded protein response(UPR)to restore ER proteostasis.Although UPR gene expression in plants follows a diel cycle,the mechanisms by which the circadian clock regulates these genes remain unclear.Here,we demonstrate that sensitivity to ER stress in root growth exhibits time-of-day phases and that the circadian clock regulates UPR target gene expression during ER stress.Notably,mutations in the core morning clock component CIRCADIAN CLOCK ASSOCIATED 1(CCA1)impair ER stress recovery.CCA1 forms a complex with the UPR modulator basic leucine zipper 28(bZIP28)and acts as an upstream regulator of ER stress recovery.Upon ER stress,CCA1 is stabilized and associates with bZIP28 at the ER stress response element within the BiP3 promoter,enhancing the ER stress response.Thus,CCA1 and bZIP28 coordinate a time-dependent adaptive response to ER stress to maintain ER proteostasis.Our re-sults suggest that the circadian clock primes the timing and levels of ER chaperone expression to enhance ER stress tolerance.展开更多
Vicinal oxygen chelate(VOC)proteins are members of an enzyme superfamily with dioxygenase or non-dioxygenase activities.However,the biological functions of VOC proteins in plants are poorly understood.Here,we show tha...Vicinal oxygen chelate(VOC)proteins are members of an enzyme superfamily with dioxygenase or non-dioxygenase activities.However,the biological functions of VOC proteins in plants are poorly understood.Here,we show that a VOC in Nicotiana benthamiana(NbVOC1)facilitates viral infection.NbVOC1 was significantly induced by infection by beet necrotic yellow vein virus(BNYVV).Transient overexpression of NbVOC1 or its homolog from Beta vulgaris(BvVOC1)enhanced BNYVV infection in N.benthamiana,which required the nuclear localization of VOC1.Consistent with this result,overexpressing NbVOC1 facilitated BNYVV infection,whereas,knockdown and knockout of NbVOC1 inhibited BNYVV infection in transgenic N.benthamiana plants.NbVOC1 interacts with the basic leucine zipper transcription factors bZIP17/28,which enhances their self-interaction and DNA binding to the promoters of unfolded protein response(UPR)-related genes.We propose that bZIP17/28 directly binds to the NbVOC1 promoter and induces its transcription,forming a positive feedback loop to induce the UPR and facilitating BNYVV infection.Collectively,our results demonstrate that NbVOC1 positively regulates the UPR that enhances viral infection in plants.展开更多
Transcription factors constitute numerous signal transduction networks and play a central role in gene expression regulation. Recent studies have shown that a limited portion of transcription factors are anchored in t...Transcription factors constitute numerous signal transduction networks and play a central role in gene expression regulation. Recent studies have shown that a limited portion of transcription factors are anchored in the cellular membrane, storing as dormant forms. Upon exposure to environmental and developmental cues, these transcription factors are released from the membrane and translocated to the nucleus, where they regulate associated target genes. As this process skips both transcriptional and translational regulations, it guarantees prompt response to external and internal signals. Membrane- bound transcription factors （MTFs） undergo several unique steps that are not involved in the action of canonical nuclear transcription factors： proteolytic processing and intracellular movement. Recently, alternative splicing has also emerged as a mechanism to liberate MTFs from the cellular membranes, establishing an additional activation scheme independent of proteolytic processing. Multiple layers of MTF regulation add complexity to transcriptional regulatory scheme and ensure elaborate action of MTFs. In this review, we provide an overview of recent findings on MTFs in plants and highlight the molecular mechanisms underlying MTF liberation from cellular membranes with an emphasis on intracellular movement.展开更多
基金This study was financially supported by grants from the National Basic Research Program of China （973 Program, 2012CB910500）, the National Natural Science Foundation of China （#31171157 #31070233 #31222008）, and the Shanghai Pujiang Talent Program （11PJ1400700）. No conflict of interest declared.
文摘The membrane-associated transcription factor, bZlP28, is relocated from the endoplasmic reticulum （ER） to the Golgi and proteolytically released from the membrane mediated by two proteases, SlP and S2P, in response to ER stress in Arabidopsis. The activated N-terminal domain recruits nuclear factor Y （NF-Y） subunits in the nucleus to regulate ER stress downstream genes. Little is known about the functions of the bZIP28 C-terminal lumen-facing domain. Here, we provide novel insights into how the ER lumen-facing domain affects the biological function and organelle-to-organelle movement of bZIP28 in the ER stress response. First, we demonstrated the functional redundancy of bZlP28 and bZIP60 by generation and analysis of the bZIP28 and bZIP60 double mutant zip28zip60. Subsequent genetic complementation experiments in zip28zip60 background with deletions on bZlP28 lumen-facing domain highlighted the importance of lumen-facing domain for its in vivo function of bZIP28 in the ER stress response. The protein subcellular localization and Western blotting results further revealed that the bZIP28 lumen-facing domain contains ER retention signal which is important for the proteolytic activation of bZIP28. Thus, the bZIP28 lumen-facing C-terminus plays important roles in the ER-to-Golgi movement of bZlP28, which may contribute to the sensing of the ER stress.
基金supported by National Research Foundation of Korea(NRF)grants funded by the Korean government(RS-2020-NR049332 and RS-2022-NR070837 to W.-Y.K.and RS-2024-00358746 to G.A.).
文摘The endoplasmic reticulum(ER)is a cellular organelle responsible for protein synthesis and folding.When its protein folding capacity is exceeded,unfolded or misfolded proteins accumulate,causing ER stress and triggering the unfolded protein response(UPR)to restore ER proteostasis.Although UPR gene expression in plants follows a diel cycle,the mechanisms by which the circadian clock regulates these genes remain unclear.Here,we demonstrate that sensitivity to ER stress in root growth exhibits time-of-day phases and that the circadian clock regulates UPR target gene expression during ER stress.Notably,mutations in the core morning clock component CIRCADIAN CLOCK ASSOCIATED 1(CCA1)impair ER stress recovery.CCA1 forms a complex with the UPR modulator basic leucine zipper 28(bZIP28)and acts as an upstream regulator of ER stress recovery.Upon ER stress,CCA1 is stabilized and associates with bZIP28 at the ER stress response element within the BiP3 promoter,enhancing the ER stress response.Thus,CCA1 and bZIP28 coordinate a time-dependent adaptive response to ER stress to maintain ER proteostasis.Our re-sults suggest that the circadian clock primes the timing and levels of ER chaperone expression to enhance ER stress tolerance.
基金supported by the National Natural Science Foundation of China(32270165 and 31872921)in part by China Agricultural Industry Technology System(Grant No.CARS-170304).
文摘Vicinal oxygen chelate(VOC)proteins are members of an enzyme superfamily with dioxygenase or non-dioxygenase activities.However,the biological functions of VOC proteins in plants are poorly understood.Here,we show that a VOC in Nicotiana benthamiana(NbVOC1)facilitates viral infection.NbVOC1 was significantly induced by infection by beet necrotic yellow vein virus(BNYVV).Transient overexpression of NbVOC1 or its homolog from Beta vulgaris(BvVOC1)enhanced BNYVV infection in N.benthamiana,which required the nuclear localization of VOC1.Consistent with this result,overexpressing NbVOC1 facilitated BNYVV infection,whereas,knockdown and knockout of NbVOC1 inhibited BNYVV infection in transgenic N.benthamiana plants.NbVOC1 interacts with the basic leucine zipper transcription factors bZIP17/28,which enhances their self-interaction and DNA binding to the promoters of unfolded protein response(UPR)-related genes.We propose that bZIP17/28 directly binds to the NbVOC1 promoter and induces its transcription,forming a positive feedback loop to induce the UPR and facilitating BNYVV infection.Collectively,our results demonstrate that NbVOC1 positively regulates the UPR that enhances viral infection in plants.
基金supported by Basic Science Research Program through the National Research Foundation of Korea(NRF)funded by the Ministry of Education(NRF-2013R1A1A1004831)research funds of Chonbuk National University in 2012
文摘Transcription factors constitute numerous signal transduction networks and play a central role in gene expression regulation. Recent studies have shown that a limited portion of transcription factors are anchored in the cellular membrane, storing as dormant forms. Upon exposure to environmental and developmental cues, these transcription factors are released from the membrane and translocated to the nucleus, where they regulate associated target genes. As this process skips both transcriptional and translational regulations, it guarantees prompt response to external and internal signals. Membrane- bound transcription factors （MTFs） undergo several unique steps that are not involved in the action of canonical nuclear transcription factors： proteolytic processing and intracellular movement. Recently, alternative splicing has also emerged as a mechanism to liberate MTFs from the cellular membranes, establishing an additional activation scheme independent of proteolytic processing. Multiple layers of MTF regulation add complexity to transcriptional regulatory scheme and ensure elaborate action of MTFs. In this review, we provide an overview of recent findings on MTFs in plants and highlight the molecular mechanisms underlying MTF liberation from cellular membranes with an emphasis on intracellular movement.
