Complex I （the NADH：ubiquinone oxidoreductase） of the mitochondrial respiratory chain is a complicated, multi-subunit, membrane- bound assembly and contains more than 40 different proteins in higher plants. In this...Complex I （the NADH：ubiquinone oxidoreductase） of the mitochondrial respiratory chain is a complicated, multi-subunit, membrane- bound assembly and contains more than 40 different proteins in higher plants. In this paper, we characterize the Arabidopsis homologue （designated as AtCIB22） of the B22 subunit of eukaryotic mitochondriai Complex I. AtCIB22 is a single-copy gene and is highly con- served throughout eukaryotes. AtCIB22 protein is located in mitochondria and the AtC1B22 gene is widely expressed in different tissues. Mutant Arabidopsis plants with a disrupted AtC1B22 gene display pleiotropic phenotypes including shorter roots, smaller plants and de- layed flowering. Stress analysis indicates that the AtC1B22 mutants＇ seed germination and early seedling growth are severely inhibited by sucrose deprivation stress but more tolerant to ethanol stress. Molecular analysis reveals that in moderate knockdown AtCIB22 mutants, genes including cell redox proteins and stress related proteins are significantly up-regulated, and that in severe knockdown AtCIB22 mu- tants, the alternative respiratory pathways including NDA1, NDB2, AOXla and AtPUMP1 are remarkably elevated. These data demon- strate that AtCIB22 is essential for plant development and mitochondrial electron transport chains in Arabidopsis. Our findings also en- hance our understanding about the physiological role of Complex I in plants.展开更多
BACKGROUND： During the cellular aging process, the number of mitochondria, generation of adenosine triphosphate （ATP）, activity of respiratory chain enzyme complex 1 and 4, and oxidation decrease. OBJECTIVE： To ob...BACKGROUND： During the cellular aging process, the number of mitochondria, generation of adenosine triphosphate （ATP）, activity of respiratory chain enzyme complex 1 and 4, and oxidation decrease. OBJECTIVE： To observe the effects of aqueous and spirituous extract, as well as polysaccharides from Fructus schizandrae （Magnolia Vine） on energy metabolism and mitochondrial anti-oxidation in cranial nerve cells of a D-gal-induced aging mouse model. DESIGN, TIME AND SETTING： A randomized, controlled, animal study. The experiment was conducted at the Department of Biochemistry, Qiqihar Medical College between March and July 2006. MATERIALS： Fifty healthy, Kunming mice of both sexes, aged 2 3 months old and weighing 18 22 g, were used for the present study. Fructus schizandrae was purchased from the Medical College of Jiamusi University. Aqueous extracts, spirituous extracts, and polysaccharides from Fructus schizandrae were prepared. D-galactose （D-gal） is a product of the Second Reagent Factory, Shanghai City, China. Mn-superoxide dismutase （Mn-SOD） kit, malonaldehyde （MDA） kit, protein quantification kit, and inorganic phosphorus testing kit were purchased from Jian Cheng Bioeng. Co., China. METHODS： Fifty mice were randomly divided into five groups, with 10 mice in each group： young control, aging model, aqueous Fructus schizandrae extract, spirituous Fructus schizandrae extract, and Fructus schizandrae polysaccharides. Over a course of 30 days, mice in aging model, aqueous Fructus schizandrae extract, spirituous Fructus schizandrae extract, and Fructus schizandrae polysaccharides groups were injected subcutaneously with D-gal （100 mg/kg） into the nape of the neck daily, and administered intragastrically with an equal volume of sterile, warm water （aging model）, aqueous Fructus schizandrae extract （2 g/kg）, spirituous Fructus schizandrae extract （2 g/kg）, or Fructus schizandrae polysaccharides （0.2 g/kg）, respectively. Mice in the young control group were injected into the nape of the neck with physiological saline and administered intragastrically with sterile, warm water. MAIN OUTCOME MEASURES： Respiratory chain complex I and H^＋-ATP enzyme activities, as well as Mn-SOD and MDA levels, were determined by the Coomassie brilliant blue method. RESULTS： All fifty mice were included in the final analysis. In mitochondria fiom cranial nerve cells of the aging mouse group MDA levels were significantly increased, compared with young control group （P 〈 0.01）; however, Mn-SOD levels, as well as respiratory chain complex I and H＋-ATP enzyme activity, were remarkably decreased （P 〈 0.01 ）. In each Fructus schizandrae group, Mn-SOD levels, as well as respiratory chain complex I and H＋-ATP enzyme activity was enhanced to various extents （P 〈 0.05, P 〈 0.01）, and MDA levels were decreased （P 〈 0.01）, compared with the aging model group. CONCLUSION： Aqueous and spirituous Fructus schizandrae extracts, as well as Fructus schizandrae polysaccharides delayed changes in mitochondrial energy metabolism, increased Mn-SOD levels, and decreased MDA levels in cranial nerve cell mitochondria of an aging mouse model. Fructus schizandrae polysaccharides were particularly capable of protecting mitochondria from oxidative injury.展开更多
Other than the respiratory chain components, most mitochondrial proteins are synthesized in the cytosol and imported into the mitochondria. Many mitochondrial proteins therefore have at least a transient cytosolic app...Other than the respiratory chain components, most mitochondrial proteins are synthesized in the cytosol and imported into the mitochondria. Many mitochondrial proteins therefore have at least a transient cytosolic appearance, and several have a dual mitochondrial-cytosol functional localization. However, recent work has revealed several proteins, one of which is a large protein complex, with dual mitochondrial and nuclear localizations. The enzyme fumarase which catalyzes the reversible hydration/dehydration of fumarate to malate is part of the mitochondria matrix tricarboxylic acid (TCA) cycle. It could, however, be recruited from the cytosol to the nucleus in response to DNA damage, where it is important for DNA repair. The pyruvate dehydrogenase complex (PDC) generates acetyl-CoA from pyruvate, and is recently shown to translocate from the mitochondrial matrix into the nuclear under mitogenic and stress conditions to generate acetyl–CoA within the nucleus. The mitochondrial monooxygenase CLK-1/COQ7 responsible for the synthesis of ubiquinone is most recently found to have a nuclear isoform with an uncleaved amino terminus, where it affects transcriptional changes associated with mitochondrial reactive oxygen species (ROS) generation. In this review, we highlight these unusual cases of nuclear localization of classically mitochondrial proteins, and discuss their possible functions in the nucleus.展开更多
Distribution and activity of mitochondda are key factors in neuronal development, synaptic plasticity and axogenesis. The majority of energy sources, necessary for cellular functions, originate from oxidative phosphor...Distribution and activity of mitochondda are key factors in neuronal development, synaptic plasticity and axogenesis. The majority of energy sources, necessary for cellular functions, originate from oxidative phosphorylation located in the inner mitochondrial membrane. The adenosine-5＇- triphosphate production is regulated by many control mechanism-firstly by oxygen, substrate level, adenosine-5＇-diphosphate level, mitochondrial membrane potential, and rate of coupling and proton leak. Recently, these mechanisms have been implemented by ＂second control mechanisms,＂ such as reversible phosphorylation of the tricarboxylic acid cycle enzymes and electron transport chain complexes, aUosteric inhibition of cytochrome c oxidase, thyroid hormones, effects of fatty acids and uncoupling proteins. Impaired function of mitochondria is implicated in many diseases ranging from mitochondrial myopathies to bipolar disorder and schizophrenia. Mitochondrial dysfunctions are usually related to the ability of mitochondria to generate adenosine-5＇-triphosphate in response to energy demands. Large amounts of reactive oxygen species are released by defective mitochondria similarly, decline of antioxidative enzyme activities （e.g. in the elderly） enhances reactive oxygen species production. We reviewed data concerning neuroplasticity, physiology, and control of mitochondrial oxidative phosphorylation and reactive oxygen species production.展开更多
基金supported by the National Basic Research Program of China (No. 2009CB941503)
文摘Complex I （the NADH：ubiquinone oxidoreductase） of the mitochondrial respiratory chain is a complicated, multi-subunit, membrane- bound assembly and contains more than 40 different proteins in higher plants. In this paper, we characterize the Arabidopsis homologue （designated as AtCIB22） of the B22 subunit of eukaryotic mitochondriai Complex I. AtCIB22 is a single-copy gene and is highly con- served throughout eukaryotes. AtCIB22 protein is located in mitochondria and the AtC1B22 gene is widely expressed in different tissues. Mutant Arabidopsis plants with a disrupted AtC1B22 gene display pleiotropic phenotypes including shorter roots, smaller plants and de- layed flowering. Stress analysis indicates that the AtC1B22 mutants＇ seed germination and early seedling growth are severely inhibited by sucrose deprivation stress but more tolerant to ethanol stress. Molecular analysis reveals that in moderate knockdown AtCIB22 mutants, genes including cell redox proteins and stress related proteins are significantly up-regulated, and that in severe knockdown AtCIB22 mu- tants, the alternative respiratory pathways including NDA1, NDB2, AOXla and AtPUMP1 are remarkably elevated. These data demon- strate that AtCIB22 is essential for plant development and mitochondrial electron transport chains in Arabidopsis. Our findings also en- hance our understanding about the physiological role of Complex I in plants.
文摘BACKGROUND： During the cellular aging process, the number of mitochondria, generation of adenosine triphosphate （ATP）, activity of respiratory chain enzyme complex 1 and 4, and oxidation decrease. OBJECTIVE： To observe the effects of aqueous and spirituous extract, as well as polysaccharides from Fructus schizandrae （Magnolia Vine） on energy metabolism and mitochondrial anti-oxidation in cranial nerve cells of a D-gal-induced aging mouse model. DESIGN, TIME AND SETTING： A randomized, controlled, animal study. The experiment was conducted at the Department of Biochemistry, Qiqihar Medical College between March and July 2006. MATERIALS： Fifty healthy, Kunming mice of both sexes, aged 2 3 months old and weighing 18 22 g, were used for the present study. Fructus schizandrae was purchased from the Medical College of Jiamusi University. Aqueous extracts, spirituous extracts, and polysaccharides from Fructus schizandrae were prepared. D-galactose （D-gal） is a product of the Second Reagent Factory, Shanghai City, China. Mn-superoxide dismutase （Mn-SOD） kit, malonaldehyde （MDA） kit, protein quantification kit, and inorganic phosphorus testing kit were purchased from Jian Cheng Bioeng. Co., China. METHODS： Fifty mice were randomly divided into five groups, with 10 mice in each group： young control, aging model, aqueous Fructus schizandrae extract, spirituous Fructus schizandrae extract, and Fructus schizandrae polysaccharides. Over a course of 30 days, mice in aging model, aqueous Fructus schizandrae extract, spirituous Fructus schizandrae extract, and Fructus schizandrae polysaccharides groups were injected subcutaneously with D-gal （100 mg/kg） into the nape of the neck daily, and administered intragastrically with an equal volume of sterile, warm water （aging model）, aqueous Fructus schizandrae extract （2 g/kg）, spirituous Fructus schizandrae extract （2 g/kg）, or Fructus schizandrae polysaccharides （0.2 g/kg）, respectively. Mice in the young control group were injected into the nape of the neck with physiological saline and administered intragastrically with sterile, warm water. MAIN OUTCOME MEASURES： Respiratory chain complex I and H^＋-ATP enzyme activities, as well as Mn-SOD and MDA levels, were determined by the Coomassie brilliant blue method. RESULTS： All fifty mice were included in the final analysis. In mitochondria fiom cranial nerve cells of the aging mouse group MDA levels were significantly increased, compared with young control group （P 〈 0.01）; however, Mn-SOD levels, as well as respiratory chain complex I and H＋-ATP enzyme activity, were remarkably decreased （P 〈 0.01 ）. In each Fructus schizandrae group, Mn-SOD levels, as well as respiratory chain complex I and H＋-ATP enzyme activity was enhanced to various extents （P 〈 0.05, P 〈 0.01）, and MDA levels were decreased （P 〈 0.01）, compared with the aging model group. CONCLUSION： Aqueous and spirituous Fructus schizandrae extracts, as well as Fructus schizandrae polysaccharides delayed changes in mitochondrial energy metabolism, increased Mn-SOD levels, and decreased MDA levels in cranial nerve cell mitochondria of an aging mouse model. Fructus schizandrae polysaccharides were particularly capable of protecting mitochondria from oxidative injury.
文摘Other than the respiratory chain components, most mitochondrial proteins are synthesized in the cytosol and imported into the mitochondria. Many mitochondrial proteins therefore have at least a transient cytosolic appearance, and several have a dual mitochondrial-cytosol functional localization. However, recent work has revealed several proteins, one of which is a large protein complex, with dual mitochondrial and nuclear localizations. The enzyme fumarase which catalyzes the reversible hydration/dehydration of fumarate to malate is part of the mitochondria matrix tricarboxylic acid (TCA) cycle. It could, however, be recruited from the cytosol to the nucleus in response to DNA damage, where it is important for DNA repair. The pyruvate dehydrogenase complex (PDC) generates acetyl-CoA from pyruvate, and is recently shown to translocate from the mitochondrial matrix into the nuclear under mitogenic and stress conditions to generate acetyl–CoA within the nucleus. The mitochondrial monooxygenase CLK-1/COQ7 responsible for the synthesis of ubiquinone is most recently found to have a nuclear isoform with an uncleaved amino terminus, where it affects transcriptional changes associated with mitochondrial reactive oxygen species (ROS) generation. In this review, we highlight these unusual cases of nuclear localization of classically mitochondrial proteins, and discuss their possible functions in the nucleus.
基金supported by grant NoMSM0021620849 given by the Ministry of Education,Youth and Sports of the Czech Republicby project PRVOUK-P26/LF1/4given by Charles University in Prague+1 种基金by grant No. SVV-2012-264514 from Charles University in Pragueby grant No.41310 given by the Grant Agency of Charles University in Prague,Czech Republic
文摘Distribution and activity of mitochondda are key factors in neuronal development, synaptic plasticity and axogenesis. The majority of energy sources, necessary for cellular functions, originate from oxidative phosphorylation located in the inner mitochondrial membrane. The adenosine-5＇- triphosphate production is regulated by many control mechanism-firstly by oxygen, substrate level, adenosine-5＇-diphosphate level, mitochondrial membrane potential, and rate of coupling and proton leak. Recently, these mechanisms have been implemented by ＂second control mechanisms,＂ such as reversible phosphorylation of the tricarboxylic acid cycle enzymes and electron transport chain complexes, aUosteric inhibition of cytochrome c oxidase, thyroid hormones, effects of fatty acids and uncoupling proteins. Impaired function of mitochondria is implicated in many diseases ranging from mitochondrial myopathies to bipolar disorder and schizophrenia. Mitochondrial dysfunctions are usually related to the ability of mitochondria to generate adenosine-5＇-triphosphate in response to energy demands. Large amounts of reactive oxygen species are released by defective mitochondria similarly, decline of antioxidative enzyme activities （e.g. in the elderly） enhances reactive oxygen species production. We reviewed data concerning neuroplasticity, physiology, and control of mitochondrial oxidative phosphorylation and reactive oxygen species production.
