Hydrogen peroxide （H2O2） operates as a signaling molecule in eukaryotes, but the specificity of its signal- ing capacities remains largely unrevealed. Here, we analyzed whether a moderate production of H2O2 from two...Hydrogen peroxide （H2O2） operates as a signaling molecule in eukaryotes, but the specificity of its signal- ing capacities remains largely unrevealed. Here, we analyzed whether a moderate production of H2O2 from two different plant cellular compartments has divergent effects on the plant transcriptome. Arabidopsis thaliana overexpressing glycolate oxidase in the chloroplast （Fahnenstich et al., 2008; Balazadeh et al., 2012） and plants deficient in peroxisomal catalase （Queval et al., 2007; Inze et al., 2012） were grown under non-photorespiratory conditions and then transferred to photorespiratory conditions to foster the production of H202 in both organelles. We show that H202 originating in a specific organelle induces two types of responses： one that integrates signals independently from the subcellular site of H202 production and another that is dependent on the H2O2 production site. H2O2 produced in peroxisomes induces transcripts involved in protein repair responses, while H2O2 produced in chloroplasts induces early signaling responses, including transcription factors and biosynthetic genes involved in production of secondary signaling messengers. There is a significant bias towards the induction of genes involved in responses to wounding and pathogen attack by chloroplas- tic-produced H202, including indolic glucosinolates-, camalexin-, and stigmasterol-biosynthetic genes. These transcriptional responses were accompanied by the accumulation of 4-methoxy-indol-3-ylmethyl glucosinolate and stigmasterol.展开更多
The sessile life style of plants creates the need to deal with an often adverse environment, in which water availability can change on a daily basis, challenging the cellular physiology and integrity. Changes in os- m...The sessile life style of plants creates the need to deal with an often adverse environment, in which water availability can change on a daily basis, challenging the cellular physiology and integrity. Changes in os- motic conditions disrupt the equilibrium of the plasma membrane： hypoosmotic conditions increase and hyperosmotic environment decrease the cell volume. Here, we show that short-term extracellular osmotic treatments are closely followed by a shift in the balance between endocytosis and exocytosis in root mer- istem cells. Acute hyperosmotic treatments （ionic and nonionic） enhance clathrin-mediated endocytosis simultaneously attenuating exocytosis, whereas hypoosmotic treatments have the opposite effects. In addition to clathrin recruitment to the plasma membrane, components of early endocytic trafficking are essential during hyperosmotic stress responses. Consequently, growth of seedlings defective in elements of clathrin or early endocytic machinery is more sensitive to hyperosmotic treatments. We also found that the endocytotic response to a change of osmotic status in the environment is dominant over the presum- ably evolutionary more recent regulatory effect of plant hormones, such as auxin. These results imply that osmotic perturbation influences the balance between endocytosis and exocytosis acting through clathrin- mediated endocytosis. We propose that tension on the plasma membrane determines the addition or removal of membranes at the cell surface, thus preserving cell integrity.展开更多
Intracellular protein routing is mediated by vesicular transport which is tightly regulated in eukaryotes. The protein and lipid homeostasis depends on coordinated delivery of de novo synthesized or recycled cargoes t...Intracellular protein routing is mediated by vesicular transport which is tightly regulated in eukaryotes. The protein and lipid homeostasis depends on coordinated delivery of de novo synthesized or recycled cargoes to the plasma membrane by exocytosis and their subsequent removal by rerouting them for recycling or degradation. Here, we report the characterization of protein affected trafficking 3 （pat3） mutant that we identified by an epifluorescence-based for- ward genetic screen for mutants defective in subcellular distribution of Arabidopsis auxin transporter PIN1-GFR While pat3 displays largely normal plant morphology and development in nutrient-rich conditions, it shows strong ectopic intracellular accumulations of different plasma membrane cargoes in structures that resemble prevacuolar compart- ments （PVC） with an aberrant morphology. Genetic mapping revealed that pat3 is defective in vacuolar protein sorting 35A （VPS35A）, a putative subunit of the retromer complex that mediates retrograde trafficking between the PVC and trans-Golgi network. Similarly, a mutant defective in another retromer subunit, vps29, shows comparable subcellular defects in PVC morphology and protein accumulation. Thus, our data provide evidence that the retromer components VPS35A and VPS29 are essential for normal PVC morphology and normal trafficking of plasma membrane proteins in plants. In addition, we show that, out of the three VPS35 retromer subunits present in Arabidopsis thaliana genome, the VPS35 homolog A plays a prevailing role in trafficking to the lyric vacuole, presenting another level of complexity in the retromer-dependent vacuolar sorting.展开更多
Auxin, one of the plant hormones, is a key regulator of plant growth and development. At the cellular level, it controls different processes, such as cell expansion, division, and differentiation that are reflected by...Auxin, one of the plant hormones, is a key regulator of plant growth and development. At the cellular level, it controls different processes, such as cell expansion, division, and differentiation that are reflected by its regulatory role in a plethora of developmental mechanisms. An important feature of the auxin action is its differential distribution within tissues mediated by the polar auxin transport machinery, which can be dynamically regulated in response to internal and external stimuli. Receptors at the cell surface or cell interior are needed to sense and interpret fluctuations in the auxin distribution.展开更多
文摘Hydrogen peroxide （H2O2） operates as a signaling molecule in eukaryotes, but the specificity of its signal- ing capacities remains largely unrevealed. Here, we analyzed whether a moderate production of H2O2 from two different plant cellular compartments has divergent effects on the plant transcriptome. Arabidopsis thaliana overexpressing glycolate oxidase in the chloroplast （Fahnenstich et al., 2008; Balazadeh et al., 2012） and plants deficient in peroxisomal catalase （Queval et al., 2007; Inze et al., 2012） were grown under non-photorespiratory conditions and then transferred to photorespiratory conditions to foster the production of H202 in both organelles. We show that H202 originating in a specific organelle induces two types of responses： one that integrates signals independently from the subcellular site of H202 production and another that is dependent on the H2O2 production site. H2O2 produced in peroxisomes induces transcripts involved in protein repair responses, while H2O2 produced in chloroplasts induces early signaling responses, including transcription factors and biosynthetic genes involved in production of secondary signaling messengers. There is a significant bias towards the induction of genes involved in responses to wounding and pathogen attack by chloroplas- tic-produced H202, including indolic glucosinolates-, camalexin-, and stigmasterol-biosynthetic genes. These transcriptional responses were accompanied by the accumulation of 4-methoxy-indol-3-ylmethyl glucosinolate and stigmasterol.
文摘The sessile life style of plants creates the need to deal with an often adverse environment, in which water availability can change on a daily basis, challenging the cellular physiology and integrity. Changes in os- motic conditions disrupt the equilibrium of the plasma membrane： hypoosmotic conditions increase and hyperosmotic environment decrease the cell volume. Here, we show that short-term extracellular osmotic treatments are closely followed by a shift in the balance between endocytosis and exocytosis in root mer- istem cells. Acute hyperosmotic treatments （ionic and nonionic） enhance clathrin-mediated endocytosis simultaneously attenuating exocytosis, whereas hypoosmotic treatments have the opposite effects. In addition to clathrin recruitment to the plasma membrane, components of early endocytic trafficking are essential during hyperosmotic stress responses. Consequently, growth of seedlings defective in elements of clathrin or early endocytic machinery is more sensitive to hyperosmotic treatments. We also found that the endocytotic response to a change of osmotic status in the environment is dominant over the presum- ably evolutionary more recent regulatory effect of plant hormones, such as auxin. These results imply that osmotic perturbation influences the balance between endocytosis and exocytosis acting through clathrin- mediated endocytosis. We propose that tension on the plasma membrane determines the addition or removal of membranes at the cell surface, thus preserving cell integrity.
文摘Intracellular protein routing is mediated by vesicular transport which is tightly regulated in eukaryotes. The protein and lipid homeostasis depends on coordinated delivery of de novo synthesized or recycled cargoes to the plasma membrane by exocytosis and their subsequent removal by rerouting them for recycling or degradation. Here, we report the characterization of protein affected trafficking 3 （pat3） mutant that we identified by an epifluorescence-based for- ward genetic screen for mutants defective in subcellular distribution of Arabidopsis auxin transporter PIN1-GFR While pat3 displays largely normal plant morphology and development in nutrient-rich conditions, it shows strong ectopic intracellular accumulations of different plasma membrane cargoes in structures that resemble prevacuolar compart- ments （PVC） with an aberrant morphology. Genetic mapping revealed that pat3 is defective in vacuolar protein sorting 35A （VPS35A）, a putative subunit of the retromer complex that mediates retrograde trafficking between the PVC and trans-Golgi network. Similarly, a mutant defective in another retromer subunit, vps29, shows comparable subcellular defects in PVC morphology and protein accumulation. Thus, our data provide evidence that the retromer components VPS35A and VPS29 are essential for normal PVC morphology and normal trafficking of plasma membrane proteins in plants. In addition, we show that, out of the three VPS35 retromer subunits present in Arabidopsis thaliana genome, the VPS35 homolog A plays a prevailing role in trafficking to the lyric vacuole, presenting another level of complexity in the retromer-dependent vacuolar sorting.
文摘Auxin, one of the plant hormones, is a key regulator of plant growth and development. At the cellular level, it controls different processes, such as cell expansion, division, and differentiation that are reflected by its regulatory role in a plethora of developmental mechanisms. An important feature of the auxin action is its differential distribution within tissues mediated by the polar auxin transport machinery, which can be dynamically regulated in response to internal and external stimuli. Receptors at the cell surface or cell interior are needed to sense and interpret fluctuations in the auxin distribution.
