The aromatic amino acids phenylalanine, tyrosine, and tryptophan in plants are not only essential components of protein synthesis, but also serve as precursors for a wide range of secondary metabolites that are import...The aromatic amino acids phenylalanine, tyrosine, and tryptophan in plants are not only essential components of protein synthesis, but also serve as precursors for a wide range of secondary metabolites that are important for plant growth as well as for human nutrition and health. The aromatic amino acids are synthesized via the shikimate pathway followed by the branched aromatic amino acids biosynthesis pathway, with chorismate serving as a major intermediate branch point metabolite. Yet, the regulation and coordination of synthesis of these amino acids are still far from being understood. Recent studies on these pathways identified a number of alternative cross-regulated biosynthesis routes with unique evolutionary origins. Although the major route of Phe and Tyr biosynthesis in plants occurs via the intermediate metabolite arogenate, recent studies suggest that plants can also synthesize phenylalanine via the intermediate metabolite phenylpyruvate （PPY）, similarly to many microorganisms. Recent studies also identified a number of transcription factors regulating the expression of genes encoding enzymes of the shikimate and aromatic amino acids pathways as well as of multiple secondary metabolites derived from them in Arabidopsis and in other plant species. .展开更多
Carotenoids are indispensable to plants and critical in human diets. Plastids are the organelles for carotenoid biosynthesis and storage in plant cells. They exist in various types, which include proplastids, etioplas...Carotenoids are indispensable to plants and critical in human diets. Plastids are the organelles for carotenoid biosynthesis and storage in plant cells. They exist in various types, which include proplastids, etioplasts, chloroplasts, amyloplasts, and chromoplasts. These plastids have dramatic differences in their capacity to synthesize and sequester carotenoids. Clearly, plastids play a central role in governing carotenogenic activity, carotenoid stability, and pigment diversity. Understanding of carotenoid metabolism and accumulation in various plastids expands our view on the multifaceted regulation of carotenogenesis and facilitates our efforts toward developing nutrient-enriched food crops. In this review, we provide a comprehensive overview of the impact of various types of plastids on carotenoid biosynthesis and accumulation, and discuss recent advances in our understanding of the regulatory control of carotenogenesis and metabolic engineering of carotenoids in light of plastid types in plants.展开更多
Among plant secondary metabolites terpenolds are a structurally most diverse group; they function as phytoalexins In plant direct defense, or as signals In Indirect defense responses which involves herbivores and thei...Among plant secondary metabolites terpenolds are a structurally most diverse group; they function as phytoalexins In plant direct defense, or as signals In Indirect defense responses which involves herbivores and their natural enemies. In recent years, more and more attention has been paid to the Investigation of the ecological role of plant terpenolds. The biosynthesis pathways of monoterpenes, sesquiterpenes, and diterpenes Include the synthesis of C5 precursor isopentenyl diphosphate （IPP） and Its allylic isomer dlmethylallyl dlphosphate （DMAPP）, the synthesis of the immediate diphosphate precursors, and the formation of the diverse terpenoids. Terpene synthases （TPSs） play a key role In volatile terpene synthesis. By expression of the TPS genes, significant achievements have been made on metabolic engineering to Increase terpenoid production. This review mainly summarizes the recent research progress In elucidating the ecological role of terpenoids and characterization of the enzymes Involved in the terpenold biosynthesis. Spatial and temporal regulations of terpenoids metabolism are also discussed.展开更多
Amino acids have various prominent functions in plants. Besides their usage during protein biosynthesis, they also represent building blocks for several other biosynthesis pathways and play pivotal roles during signal...Amino acids have various prominent functions in plants. Besides their usage during protein biosynthesis, they also represent building blocks for several other biosynthesis pathways and play pivotal roles during signaling processes as well as in plant stress response. In general, pool sizes of the 20 amino acids differ strongly and change dynamically depending on the developmental and physiological state of the plant cell. Besides amino acid biosynthesis, which has already been investigated in great detail, the catabolism of amino acids is of central importance for adjusting their pool sizes but so far has drawn much less attention. The degradation of amino acids can also contribute substantially to the energy state of plant cells under certain physiological conditions, e.g. carbon starvation. In this review, we discuss the biological role of amino acid catabolism and summarize current knowledge on amino acid degradation pathways and their regulation in the context of plant cell physiology.展开更多
Carotenoids are indispensable to plants and play a critical role in human nutrition and health. Significant progress has been made in our understanding of carotenoid metabolism in plants. The biosynthetic pathway has ...Carotenoids are indispensable to plants and play a critical role in human nutrition and health. Significant progress has been made in our understanding of carotenoid metabolism in plants. The biosynthetic pathway has been extensively studied. Nearly all the genes encoding the biosynthetic enzymes have been isolated and characterized from various organisms. In recent years, there is an increasing body of work on the signaling pathways and plastid development, which might provide global control of carotenoid biosynthesis and accumulation. Herein, we will highlight recent progress on the biosynthesis, regulation, and metabolic engineering of carotenoids in plants, as well as the future research towards elucidating the regulatory mechanisms and metabolic network that control carotenoid metabolism.展开更多
AIM: To construct subtracted cDNA libraries and further identify differentially expressed genes that are related to the development of colorectal carcinoma(CRC). METHODS: Suppression subtractive hybridization(SSH) was...AIM: To construct subtracted cDNA libraries and further identify differentially expressed genes that are related to the development of colorectal carcinoma(CRC). METHODS: Suppression subtractive hybridization(SSH) was done on cDNAs of normal mucosa, adenoma and adenocarcinoma tissues from the same patient. Three subtracted cDNA libraries were constructed and then hybridized with forward and backward subtracted probes for differential screening. Positive clones from each subtracted cDNA library were selected for sequencing and BLAST analysis. Finally, virtual Northern Blot confirmed such differential expression. RESULTS: By this way, there were about 3-4 X 10(2) clones identified in each subtracted cDNA library, in which about 85% positive clones were differentially screened. Sequencing and BLAST homology search revealed some clones containing sequences of known gene fragments and several possibly novel genes showing few or no sequence homologies with any known sequences in the database. CONCLUSION: All results confirmed the effectiveness and sensitivity of SSH. The differentially expressed genes during the development of CRC can be used to shed light on the pathogenesis of CRC and be useful genetic markers for early diagnosis and therapy.展开更多
AIM: To study the effects of hypoxia, hyperoxia on the regulation of expression and activity of matrix metalloproteinase-2 (MMP-2) in hepatic stellate cells (HSC). METHODS: The expressions of MMP-2, tissue inhibitor o...AIM: To study the effects of hypoxia, hyperoxia on the regulation of expression and activity of matrix metalloproteinase-2 (MMP-2) in hepatic stellate cells (HSC). METHODS: The expressions of MMP-2, tissue inhibitor of matrix metalloproteinase-2 (TIMP-2) and membrane type matrix metalloproteinase-1 (MT1-MMP) in cultured rat HSC were detected by immunocytochemistry (ICC) and in situ hybridization (ISH). The contents of MMP-2 and TIMP-2 in culture supernatant were detected with ELISA and the activity of MMP-2 in supernatant was revealed by zymography. RESULTS: In the situation of hypoxia for 12h, the expression of MMP-2 protein was enhanced (hypoxia group positive indexes: 5.7 +/- 2.0, n=10; control: 3.2 +/- 1.0, n = 7; P【0.05), while TIMP-2 protein was decreased in HSC (hypoxia group positive indexes: 2.5 +/- 0.7, n = 10; control: 3.6 +/- 1.0, n = 7; P 【 0.05), and the activity (total A) of MMP-2 in supernatant declined obviously (hypoxia group: 7.334 +/- 1.922, n = 9; control: 17.277 +/- 7.424, n = 11; P 【 0.01). Compared the varied duration of hypoxia, the changes of expressions including mRNA and protein level as well as activity of MMP-2 were most notable in 6h group. The highest value(A(hypoxia)-A(control)) of the protein and the most intense signal of mRNA were in the period of hypoxia for 6h, along with the lowest activity of MMP-2. In the situation of hyperoxia for 12h, the contents (A(450)) of MMP-2 and TIMP-2 in supernatant were both higher than those in the control, especially the TIMP-2 (hyperoxia group: 0.0499 +/- 0.0144, n = 16; control: 0.0219 +/- 0.0098, n = 14; P 【 0.01), and so was the activity of MMP-2 (hyperoxia group: 5.252 +/- 0.771, n = 14; control: 4.304 +/- 1.083, n = 12; P 【 0.05), and the expression of MT1-MMP was increased. CONCLUSION: HSC is sensitive to the oxygen, hypoxia enhances the expression of MMP-2 and the effect is more marked at the early stage; hyperoxia mainly raises the activity of MMP-2.展开更多
The nuclear receptor PPARs are fundamentally important for energy homeostasis. Through their distinct yet overlapping functions and tissue distribution, the PPARs regulate many aspects of energy metabolism at the tran...The nuclear receptor PPARs are fundamentally important for energy homeostasis. Through their distinct yet overlapping functions and tissue distribution, the PPARs regulate many aspects of energy metabolism at the transcriptional level. Functional impairment or dysregulation of these receptors leads to a variety of metabolic diseases, while their ligands offer many metabolic benefits. Studies of these receptors have advanced our knowledge of the transcriptional basis of energy metabolism and helped us understand the pathogenic mechanisms of metabolic syndrome.展开更多
Plant take up the essential nutrient sulfur as sulfate from the soil, reduce it, and assimilate into bioorganic compounds, with cysteine being the first product. Both sulfate uptake and assimilation are highly regulat...Plant take up the essential nutrient sulfur as sulfate from the soil, reduce it, and assimilate into bioorganic compounds, with cysteine being the first product. Both sulfate uptake and assimilation are highly regulated by the demand for the reduced sulfur, by availability of nutrients, and by environmental conditions. In the last decade, great prog- ress has been achieved in dissecting the regulation of sulfur metabolism. Sulfate uptake and reduction of activated sulfate, adenosine 5＇-phosphosulfate （APS）, to sulfite by APS reductase appear to be the key regulatory steps. Here, we review the current knowledge on regulation of these processes, with special attention given to similarities and differences.展开更多
Jasmonates （JAs） orchestrate immune responses upon wound/herbivore injury or infection by necrotro- phic pathogens. Elucidation of catabolic routes has revealed new complexity in jasmonate metabolism. Two integrated...Jasmonates （JAs） orchestrate immune responses upon wound/herbivore injury or infection by necrotro- phic pathogens. Elucidation of catabolic routes has revealed new complexity in jasmonate metabolism. Two integrated pathways attenuate signaling by turning over the active hormone jasmonoyl-isoleucine （JA-Ile） through w-oxidation or deconjugation, and define an indirect route forming the derivative 12OH-JA. Here, we provide evidence for a second 12OH-JA formation pathway by direct jasmonic acid （JA） oxidation. Three jasmonic acid oxidases （JAOs） of the 2-oxoglutarate dioxygenase family catalyze spe- cific oxidation of JA to 12OH-JA, and their genes are induced by wounding or infection by the fungus Botrytis cinerea. JA02 exhibits the highest basal expression, and its deficiency in jao2 mutants strongly enhanced antifungal resistance. The resistance phenotype resulted from constitutive expression of antimi- crobial markers rather than from their higher induction in infected jao2 plants and could be reversed by ectopic expression of any of the three JAOs injao2. Elevated defense injao2 was dependent on the activity of JASMONATE RESPONSE 1 （JAR1） and CORONATINE-INSENSITIVE 1 （COI1） but was not correlated with erihanced JA-Ile accumulation. Instead, jao2 mutant lines displayed altered accumulation of several JA species in healthy and challenged plants, suggesting elevated metabolic flux through JA-Ile. Collectively, these data identify the missing enzymes hydroxylating JA and uncover an important metabolic diversion mechanism for repressing basal JA defense responses.展开更多
文摘The aromatic amino acids phenylalanine, tyrosine, and tryptophan in plants are not only essential components of protein synthesis, but also serve as precursors for a wide range of secondary metabolites that are important for plant growth as well as for human nutrition and health. The aromatic amino acids are synthesized via the shikimate pathway followed by the branched aromatic amino acids biosynthesis pathway, with chorismate serving as a major intermediate branch point metabolite. Yet, the regulation and coordination of synthesis of these amino acids are still far from being understood. Recent studies on these pathways identified a number of alternative cross-regulated biosynthesis routes with unique evolutionary origins. Although the major route of Phe and Tyr biosynthesis in plants occurs via the intermediate metabolite arogenate, recent studies suggest that plants can also synthesize phenylalanine via the intermediate metabolite phenylpyruvate （PPY）, similarly to many microorganisms. Recent studies also identified a number of transcription factors regulating the expression of genes encoding enzymes of the shikimate and aromatic amino acids pathways as well as of multiple secondary metabolites derived from them in Arabidopsis and in other plant species. .
文摘Carotenoids are indispensable to plants and critical in human diets. Plastids are the organelles for carotenoid biosynthesis and storage in plant cells. They exist in various types, which include proplastids, etioplasts, chloroplasts, amyloplasts, and chromoplasts. These plastids have dramatic differences in their capacity to synthesize and sequester carotenoids. Clearly, plastids play a central role in governing carotenogenic activity, carotenoid stability, and pigment diversity. Understanding of carotenoid metabolism and accumulation in various plastids expands our view on the multifaceted regulation of carotenogenesis and facilitates our efforts toward developing nutrient-enriched food crops. In this review, we provide a comprehensive overview of the impact of various types of plastids on carotenoid biosynthesis and accumulation, and discuss recent advances in our understanding of the regulatory control of carotenogenesis and metabolic engineering of carotenoids in light of plastid types in plants.
基金Supported by the Knowledge Innovation Program of the Chinese Academy of Sciences （KSCX2-SW-329）, Shanghai Basic Research Programs （03DJ14016）, and the National Natural Science Foundation of China （30370122）.
文摘Among plant secondary metabolites terpenolds are a structurally most diverse group; they function as phytoalexins In plant direct defense, or as signals In Indirect defense responses which involves herbivores and their natural enemies. In recent years, more and more attention has been paid to the Investigation of the ecological role of plant terpenolds. The biosynthesis pathways of monoterpenes, sesquiterpenes, and diterpenes Include the synthesis of C5 precursor isopentenyl diphosphate （IPP） and Its allylic isomer dlmethylallyl dlphosphate （DMAPP）, the synthesis of the immediate diphosphate precursors, and the formation of the diverse terpenoids. Terpene synthases （TPSs） play a key role In volatile terpene synthesis. By expression of the TPS genes, significant achievements have been made on metabolic engineering to Increase terpenoid production. This review mainly summarizes the recent research progress In elucidating the ecological role of terpenoids and characterization of the enzymes Involved in the terpenold biosynthesis. Spatial and temporal regulations of terpenoids metabolism are also discussed.
文摘Amino acids have various prominent functions in plants. Besides their usage during protein biosynthesis, they also represent building blocks for several other biosynthesis pathways and play pivotal roles during signaling processes as well as in plant stress response. In general, pool sizes of the 20 amino acids differ strongly and change dynamically depending on the developmental and physiological state of the plant cell. Besides amino acid biosynthesis, which has already been investigated in great detail, the catabolism of amino acids is of central importance for adjusting their pool sizes but so far has drawn much less attention. The degradation of amino acids can also contribute substantially to the energy state of plant cells under certain physiological conditions, e.g. carbon starvation. In this review, we discuss the biological role of amino acid catabolism and summarize current knowledge on amino acid degradation pathways and their regulation in the context of plant cell physiology.
基金the National Natural Science Foundation of China (30771167)the State Key Basic Research and Development Plan of China(2007CB108802)the USDA National Research Initiative Competitive Grants (2007-35318-17794 and 2001-35318-11136)
文摘Carotenoids are indispensable to plants and play a critical role in human nutrition and health. Significant progress has been made in our understanding of carotenoid metabolism in plants. The biosynthetic pathway has been extensively studied. Nearly all the genes encoding the biosynthetic enzymes have been isolated and characterized from various organisms. In recent years, there is an increasing body of work on the signaling pathways and plastid development, which might provide global control of carotenoid biosynthesis and accumulation. Herein, we will highlight recent progress on the biosynthesis, regulation, and metabolic engineering of carotenoids in plants, as well as the future research towards elucidating the regulatory mechanisms and metabolic network that control carotenoid metabolism.
基金This study is supported by Science Foundation of the Education Department of Zhejiang Province.
文摘AIM: To construct subtracted cDNA libraries and further identify differentially expressed genes that are related to the development of colorectal carcinoma(CRC). METHODS: Suppression subtractive hybridization(SSH) was done on cDNAs of normal mucosa, adenoma and adenocarcinoma tissues from the same patient. Three subtracted cDNA libraries were constructed and then hybridized with forward and backward subtracted probes for differential screening. Positive clones from each subtracted cDNA library were selected for sequencing and BLAST analysis. Finally, virtual Northern Blot confirmed such differential expression. RESULTS: By this way, there were about 3-4 X 10(2) clones identified in each subtracted cDNA library, in which about 85% positive clones were differentially screened. Sequencing and BLAST homology search revealed some clones containing sequences of known gene fragments and several possibly novel genes showing few or no sequence homologies with any known sequences in the database. CONCLUSION: All results confirmed the effectiveness and sensitivity of SSH. The differentially expressed genes during the development of CRC can be used to shed light on the pathogenesis of CRC and be useful genetic markers for early diagnosis and therapy.
基金Supported by the Scientific Research Fund for Doctorate Education,State Educational Commission,No.9837
文摘AIM: To study the effects of hypoxia, hyperoxia on the regulation of expression and activity of matrix metalloproteinase-2 (MMP-2) in hepatic stellate cells (HSC). METHODS: The expressions of MMP-2, tissue inhibitor of matrix metalloproteinase-2 (TIMP-2) and membrane type matrix metalloproteinase-1 (MT1-MMP) in cultured rat HSC were detected by immunocytochemistry (ICC) and in situ hybridization (ISH). The contents of MMP-2 and TIMP-2 in culture supernatant were detected with ELISA and the activity of MMP-2 in supernatant was revealed by zymography. RESULTS: In the situation of hypoxia for 12h, the expression of MMP-2 protein was enhanced (hypoxia group positive indexes: 5.7 +/- 2.0, n=10; control: 3.2 +/- 1.0, n = 7; P【0.05), while TIMP-2 protein was decreased in HSC (hypoxia group positive indexes: 2.5 +/- 0.7, n = 10; control: 3.6 +/- 1.0, n = 7; P 【 0.05), and the activity (total A) of MMP-2 in supernatant declined obviously (hypoxia group: 7.334 +/- 1.922, n = 9; control: 17.277 +/- 7.424, n = 11; P 【 0.01). Compared the varied duration of hypoxia, the changes of expressions including mRNA and protein level as well as activity of MMP-2 were most notable in 6h group. The highest value(A(hypoxia)-A(control)) of the protein and the most intense signal of mRNA were in the period of hypoxia for 6h, along with the lowest activity of MMP-2. In the situation of hyperoxia for 12h, the contents (A(450)) of MMP-2 and TIMP-2 in supernatant were both higher than those in the control, especially the TIMP-2 (hyperoxia group: 0.0499 +/- 0.0144, n = 16; control: 0.0219 +/- 0.0098, n = 14; P 【 0.01), and so was the activity of MMP-2 (hyperoxia group: 5.252 +/- 0.771, n = 14; control: 4.304 +/- 1.083, n = 12; P 【 0.05), and the expression of MT1-MMP was increased. CONCLUSION: HSC is sensitive to the oxygen, hypoxia enhances the expression of MMP-2 and the effect is more marked at the early stage; hyperoxia mainly raises the activity of MMP-2.
文摘The nuclear receptor PPARs are fundamentally important for energy homeostasis. Through their distinct yet overlapping functions and tissue distribution, the PPARs regulate many aspects of energy metabolism at the transcriptional level. Functional impairment or dysregulation of these receptors leads to a variety of metabolic diseases, while their ligands offer many metabolic benefits. Studies of these receptors have advanced our knowledge of the transcriptional basis of energy metabolism and helped us understand the pathogenic mechanisms of metabolic syndrome.
文摘Plant take up the essential nutrient sulfur as sulfate from the soil, reduce it, and assimilate into bioorganic compounds, with cysteine being the first product. Both sulfate uptake and assimilation are highly regulated by the demand for the reduced sulfur, by availability of nutrients, and by environmental conditions. In the last decade, great prog- ress has been achieved in dissecting the regulation of sulfur metabolism. Sulfate uptake and reduction of activated sulfate, adenosine 5＇-phosphosulfate （APS）, to sulfite by APS reductase appear to be the key regulatory steps. Here, we review the current knowledge on regulation of these processes, with special attention given to similarities and differences.
文摘Jasmonates （JAs） orchestrate immune responses upon wound/herbivore injury or infection by necrotro- phic pathogens. Elucidation of catabolic routes has revealed new complexity in jasmonate metabolism. Two integrated pathways attenuate signaling by turning over the active hormone jasmonoyl-isoleucine （JA-Ile） through w-oxidation or deconjugation, and define an indirect route forming the derivative 12OH-JA. Here, we provide evidence for a second 12OH-JA formation pathway by direct jasmonic acid （JA） oxidation. Three jasmonic acid oxidases （JAOs） of the 2-oxoglutarate dioxygenase family catalyze spe- cific oxidation of JA to 12OH-JA, and their genes are induced by wounding or infection by the fungus Botrytis cinerea. JA02 exhibits the highest basal expression, and its deficiency in jao2 mutants strongly enhanced antifungal resistance. The resistance phenotype resulted from constitutive expression of antimi- crobial markers rather than from their higher induction in infected jao2 plants and could be reversed by ectopic expression of any of the three JAOs injao2. Elevated defense injao2 was dependent on the activity of JASMONATE RESPONSE 1 （JAR1） and CORONATINE-INSENSITIVE 1 （COI1） but was not correlated with erihanced JA-Ile accumulation. Instead, jao2 mutant lines displayed altered accumulation of several JA species in healthy and challenged plants, suggesting elevated metabolic flux through JA-Ile. Collectively, these data identify the missing enzymes hydroxylating JA and uncover an important metabolic diversion mechanism for repressing basal JA defense responses.
