Flavoproteins are proteins that contain a nucleic acid derivative of riboflavin:flavin adenine dinucleotide(FAD)or flavin mononucleotide(FMN).Flavoproteins are involved in a wide array of biological processes,such as ...Flavoproteins are proteins that contain a nucleic acid derivative of riboflavin:flavin adenine dinucleotide(FAD)or flavin mononucleotide(FMN).Flavoproteins are involved in a wide array of biological processes,such as photosynthesis,DNA repair and natural product biosynthesis.It should be noted that 5%-10%of flavoproteins have a covalently linked flavin prosthetic group.Such covalent linkages benefit the holoenzyme in several ways including improving the stability and catalytic potency.During the past decade,significant progress has been made in covalent flavoproteins,especially with respect to enzyme-dependent biogenesis and discovery of novel linkage types.The present review gives a condensed overview of investigations published from March 2009 to December 2021,with emphasis on the discovery,biogenesis and their catalytic role in natural product biosynthesis.展开更多
<span style="font-family:;" "=""><span style="font-family:Verdana;">Methane production by archaea depends on tetrahydromethanopterin (H</span><sub><span st...<span style="font-family:;" "=""><span style="font-family:Verdana;">Methane production by archaea depends on tetrahydromethanopterin (H</span><sub><span style="font-family:Verdana;">4</span></sub><span style="font-family:Verdana;">MPT), a pterin-containing cofactor that carries one-carbon units. Two redox reactions within the nine steps of H</span><sub><span style="font-family:Verdana;">4</span></sub><span style="font-family:Verdana;">MPT side chain biosynthesis have been hypothesized. Biochemical assays have demonstrated that the archaeal iron-sulfur flavoprotein dihydromethanopterin reductase X (DmrX or MM1854) catalyzes the final reaction of the pathway, the reduction of dihydromethanopterin to H</span><sub><span style="font-family:Verdana;">4</span></sub><span style="font-family:Verdana;">MPT</span></span><span style="font-family:Verdana;">,</span><span style="font-family:;" "=""><span style="font-family:Verdana;"> using dithiothreitol (DTT) as an artificial electron donor. The crystal structure of DmrB, a bacterial DmrX homolog that lacks iron-sulfur clusters, has led to a proposed ping-pong mechanism of electron transfer between FMNH</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;"> and the FMN prosthetic group of DmrB. However, an enzymatic assay to test the hypothetical DmrB mechanism is lacking because a suitable electron donor has not previously been identified. Furthermore, a second uncharacterized archaeal flavoprotein (MM1853) has been hypothesized to function in H</span><sub><span style="font-family:Verdana;">4</span></sub><span style="font-family:Verdana;">MPT side chain biosynthesis. In this </span><span style="font-family:Verdana;">work, to facilitate the development of assays to elucidate the functions of DmrB </span><span style="font-family:Verdana;">and MM1853, we tested a variety of electron donors, including dithiothreitol, ferredoxin, and a system consisting of NADH and an NADH-dependent fla</span><span style="font-family:Verdana;">vin-reducing enzyme (Fre).</span><span style="font-family:Verdana;"> Reduction of the DmrB prosthetic group (FMN) was measured as a decrease in absorbance at 460 nm. NADPH, NADH, and </span><span style="font-family:Verdana;">DTT were unable to reduce DmrB. However, NADH/Fre was able to reduce </span><span style="font-family:Verdana;">DmrB within 70 min (initial rate of 1.3 μM/min), providing the basis for a future DmrB activity assay. Carbon monoxide (CO)/CO dehydrogenase/ferredoxin reduced DmrB more rapidly within 6 min. Both electr</span><span style="font-family:Verdana;">on transfer systems reduced a second flavin-containing archaeal protein MM1853, which is predicted to catalyze the third step of H</span><sub><span style="font-family:Verdana;">4</span></sub><span style="font-family:Verdana;">MPT biosynthesis. While NADH and NADPH were incapable of directly reducing the FMN cofactor of MM1853, DTT or NADH/Fre could eliminate the FMN peaks. These results establish the basis for new oxidoreductase assays that will facilitate testing several proposed DmrB mechanisms and defining the specific function of MM1853 in methanogen cofactor biosynthesis.</span></span>展开更多
Background： Lipid storage myopathy （LSM） is a genetically heterogeneous group with variable clinical phenotypes. Late-onset multiple acyl-coenzyme A dehydrogenation deficiency （MADD） is a rather common form of LS...Background： Lipid storage myopathy （LSM） is a genetically heterogeneous group with variable clinical phenotypes. Late-onset multiple acyl-coenzyme A dehydrogenation deficiency （MADD） is a rather common form of LSM in China. Diagnosis and clinical management of it remain challenging, especially without robust muscle biopsy result and genetic detection. As the noninvasion and convenience, muscle magnetic resonance imaging （MRI） is a helpful assistant, diagnostic tool for neuromuscular disorders. However, the disease-specific MRI patterns of muscle involved and its diagnostic value in late-onset MADD have not been systematic analyzed. Methods： We assessed the MRI pattern and fat infiltration degree of the lower limb muscles in 28 late-onset MADD patients, combined with detailed clinical features and gene spectrum. Fat infiltration degree of the thigh muscle was scored while that ofgluteus was described as obvious or not. Associated muscular atrophy was defined as obvious muscle bulk reduction. Results： The mean scores were significantly different among the anterior, medial, and posterior thigh muscle groups. The mean of fat infiltration scores on posterior thigh muscle group was significantly higher than either anterior or medial thigh muscle group （P 〈 0.00 l）. Moreover, the mean score on medial thigh muscle group was significantly higher than that of anterior thigh muscle group （P 〈 0.01）. About half of the patients displayed fat infiltration and atrophy in gluteus muscles. Of 28 patients, 12 exhibited atrophy in medial and/ or posterior thigh muscle groups, especially in posterior thigh muscle group. Muscle edema pattern was not found in all the patients. Conclusions： Late-onset MADD patients show a typical muscular imaging pattern of fat infiltration and atrophy on anterior, posterior, and medial thigh muscle groups, with major involvement of posterior thigh muscle group and gluteus muscles and a sparing involvement of anterior thigh compartment. Our findings also suggest that muscle MRI of lower limbs is a helpful tool in guiding clinical evaluation on late-onset MADD.展开更多
A membrane-bound protein was purified from rat liver mitochondria.After being di-gested with V8 protease,two peptides containing identical 14 amino acid residue sequences were obtained.Using the 14 amino acid peptide ...A membrane-bound protein was purified from rat liver mitochondria.After being di-gested with V8 protease,two peptides containing identical 14 amino acid residue sequences were obtained.Using the 14 amino acid peptide derived DNA sequence as gene specific primer,the cDNA of correspondent gene 5′-terminal and 3′-terminal were obtained by RACE technique.The full-length cDNA that encoded a protein of 616 amino acids was thus cloned,which included the above mentioned peptide sequence.The full length cDNA was highly homologous to that of human ETF-QO,indicating that it may be the cDNA of rat ETF-QO.ETF-QO is an iron sulfur protein located in mitochondria inner membrane containing two kinds of redox center:FAD and[4Fe-4S]center.After comparing the sequence from the cDNA of the 616 amino acids protein with that of the mature protein of rat liver mitochondria,it was found that the N terminal 32 amino acid residues did not exist in the mature protein,indicating that the cDNA was that of ETF-QOp.When the cDNA was expressed in Saccharomyces cerevisiae with inducible vectors,the protein product was enriched in mitochondrial fraction and exhibited electron transfer activity(NBT re-ductase activity)of ETF-QO.Results demonstrated that the 32 amino acid peptide was a mito-chondrial targeting peptide,and both FAD and iron-sulfur cluster were inserted properly into the expressed ETF-QO.ETF-QO had a high level expression in rat heart,liver and kidney.The fu-sion protein of GFP-ETF-QO co-localized with mitochondria in COS-7 cells.展开更多
Ferroptosis,a type of programmed cell death,represents a distinct paradigm in cell biology.It is characterized by the iron-dependent accumulation of reactive oxygen species,which induce lipid peroxidation(LPO),and is ...Ferroptosis,a type of programmed cell death,represents a distinct paradigm in cell biology.It is characterized by the iron-dependent accumulation of reactive oxygen species,which induce lipid peroxidation(LPO),and is orchestrated by the interplay between iron,lipid peroxides,and glutathione.In this review,we emphasize the frequently overlooked role of iron in LPO beyond the classical iron-driven Fenton reaction in several crucial processes that regulate cellular iron homeostasis,including iron intake and export as well as ferritinophagy,and the emerging roles of endoplasmic reticulum-resident flavoprotein oxidoreductases,especially P450 oxidoreductases,in modulating LPO.We summarize how various types of fatty acids(FAs),including saturated,monounsaturated,and polyunsaturated FAs,differentially influence ferroptosis when incorporated into phospholipids.Furthermore,we highlight the therapeutic potential of targeting LPO to mitigate ferroptosis and discuss the regulatory mechanisms of endogenous lipophilic radical-trapping antioxidants that confer resistance to ferroptosis,shedding light on therapeutic avenues for ferroptosis-associated diseases.展开更多
The relationship between the levels of renalase and changes in proteinuria, hypertension, renal function, renal tubular epithelial cell apoptosis and B-cell lymphoma-2 （Bcl-2） expression was investigated in patients...The relationship between the levels of renalase and changes in proteinuria, hypertension, renal function, renal tubular epithelial cell apoptosis and B-cell lymphoma-2 （Bcl-2） expression was investigated in patients （chronic nephritis, primary nephrotic syndrome or other kidney disease） that underwent renal biopsy. The study group comprised 72 patients undergoing renal biopsy. Patient profiles and renal function were collected. Concentrations of renalase and Bcl-2 were measured by immunohistochemistry. Tubular injury was detected by periodic acid Schiff staining （PAS） and renal tubular epithelial cell apoptosis was assessed by TUNEL assay. The expression of renalase was significantly lower in renal biopsy specimens than in normal kidney tissues. There was a positive linear relationship between renalase and some serum and cardiac indices; a negative correlation was found between age, eGFR, Ccr and 24-h urinary protein. Renal tubule injury index and tubular epithelial cell apoptosis index showed a negative linear correlation with renalase. The results showed that renalase probably increased the expression of Bel-2. By two independent samples t-test, renalase levels were significantly increased in the non-hypertension group than in the hypertension group. One-way ANOVA showed that renalase expression was higher in samples with Lee＇s grade Ⅲ than in those with Lee＇s grade V. The expression of renalase was significantly decreased in patients who underwent renal biopsy, and was also associated with blood and renal function. The research proved that renalase may reduce renal tubular injury and apoptosis of renal tubular epithelial cells through the mitochondrial apoptosis pathway, finally achieving the purpose of delaying the progress of renal failure.展开更多
Mitochondrial redox states provide important information about energy-linked biological processes and signaling events in tissues for various disease phenotypes including cancer.The redox scanning method developed at ...Mitochondrial redox states provide important information about energy-linked biological processes and signaling events in tissues for various disease phenotypes including cancer.The redox scanning method developed at the Chance laboratory about 30 years ago has allowed 3D highresolution(∼50×50×10µm^(3))imaging of mitochondrial redox state in tissue on the basis of the fluorescence of NADH(reduced nicotinamide adenine dinucleotide)and Fp(oxidized flavoproteins including flavin adenine dinucleotide,i.e.,FAD).In this review,we illustrate its basic principles,recent technical developments,and biomedical applications to cancer diagnostic and therapeutic studies in small animal models.Recently developed calibration procedures for the redox imaging using reference standards allow quantification of nominal NADH and Fp concentrations,and the concentration-based redox ratios,e.g.,Fp/(Fp+NADH)and NADH/(Fp+NADH)in tissues.This calibration facilitates the comparison of redox imaging results acquired for different metabolic states at different times and/or with different instrumental settings.A redox imager using a CCD detector has been developed to acquire 3D images faster and with a higher in-plane resolution down to 10µm.Ex vivo imaging and in vivo imaging of tissue mitochondrial redox status have been demonstrated with the CCD imager.Applications of tissue redox imaging in small animal cancer models include metabolic imaging of glioma and myc-induced mouse mammary tumors,predicting the metastatic potentials of human melanoma and breast cancer mouse xenografts,differentiating precancerous and normal tissues,and monitoring the tumor treatment response to photodynamic therapy.Possible future directions for the development of redox imaging are also discussed.展开更多
The fluorescence properties of reduced nicotinamide adenine dinucleotide(NADH)and oxidizedflavoproteins(Fp)including flavin adenine dinucleotide(FAD)in the respiratory chain are sensitive indicators of intracellular m...The fluorescence properties of reduced nicotinamide adenine dinucleotide(NADH)and oxidizedflavoproteins(Fp)including flavin adenine dinucleotide(FAD)in the respiratory chain are sensitive indicators of intracellular metabolic states and have been applied to the studies of mitochondrial function with energy-linked processes.The redox scanner,a three-dimensional(3D)low temperature imager previously developed by Chance et al.,measures the in vivo metabolicproperties of tissue samples by acquiring fluorescence images of NADH and Fp.The redox ratios,i.e.Fp/(Fp+NADH)and NADH/(Fp+NADH),provided a sensitive index of the mitochondrialredox state and were determined based on relative signal intensity ratios.Here we report thefurther development of the redox scanning technique by using a calibration method to quantifythe nominal concentration of the fluorophores in tissues.The redox scanner exhibited very goodlinear response in the range of NADH concentration between 165–1318µM and Fp between90–720µM using snap-frozen solution standards.Tissue samples such as human tumor mousexenografts and various mouse organs were redox-scanned together with adjacent NADH and Fpstandards of known concentration at liquid nitrogen temperature.The nominal NADH and Fpconcentrations as well as the redox ratios in the tissue samples were quantified by normalizing the tissue NADH and Fp fluorescence signal to that of the snap-frozen solution standards.This calibration procedure allows comparing redox images obtained at different time,independent of instrument settings.The quantitative multi-slice redox images revealed heterogeneity inmitochondrial redox state in the tissues.展开更多
基金supported by the National Natural Science Foundation of China(No.22077113)Zhejiang Provincial Basic Public Welfare Research Project(No.GF21H300005).
文摘Flavoproteins are proteins that contain a nucleic acid derivative of riboflavin:flavin adenine dinucleotide(FAD)or flavin mononucleotide(FMN).Flavoproteins are involved in a wide array of biological processes,such as photosynthesis,DNA repair and natural product biosynthesis.It should be noted that 5%-10%of flavoproteins have a covalently linked flavin prosthetic group.Such covalent linkages benefit the holoenzyme in several ways including improving the stability and catalytic potency.During the past decade,significant progress has been made in covalent flavoproteins,especially with respect to enzyme-dependent biogenesis and discovery of novel linkage types.The present review gives a condensed overview of investigations published from March 2009 to December 2021,with emphasis on the discovery,biogenesis and their catalytic role in natural product biosynthesis.
文摘<span style="font-family:;" "=""><span style="font-family:Verdana;">Methane production by archaea depends on tetrahydromethanopterin (H</span><sub><span style="font-family:Verdana;">4</span></sub><span style="font-family:Verdana;">MPT), a pterin-containing cofactor that carries one-carbon units. Two redox reactions within the nine steps of H</span><sub><span style="font-family:Verdana;">4</span></sub><span style="font-family:Verdana;">MPT side chain biosynthesis have been hypothesized. Biochemical assays have demonstrated that the archaeal iron-sulfur flavoprotein dihydromethanopterin reductase X (DmrX or MM1854) catalyzes the final reaction of the pathway, the reduction of dihydromethanopterin to H</span><sub><span style="font-family:Verdana;">4</span></sub><span style="font-family:Verdana;">MPT</span></span><span style="font-family:Verdana;">,</span><span style="font-family:;" "=""><span style="font-family:Verdana;"> using dithiothreitol (DTT) as an artificial electron donor. The crystal structure of DmrB, a bacterial DmrX homolog that lacks iron-sulfur clusters, has led to a proposed ping-pong mechanism of electron transfer between FMNH</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;"> and the FMN prosthetic group of DmrB. However, an enzymatic assay to test the hypothetical DmrB mechanism is lacking because a suitable electron donor has not previously been identified. Furthermore, a second uncharacterized archaeal flavoprotein (MM1853) has been hypothesized to function in H</span><sub><span style="font-family:Verdana;">4</span></sub><span style="font-family:Verdana;">MPT side chain biosynthesis. In this </span><span style="font-family:Verdana;">work, to facilitate the development of assays to elucidate the functions of DmrB </span><span style="font-family:Verdana;">and MM1853, we tested a variety of electron donors, including dithiothreitol, ferredoxin, and a system consisting of NADH and an NADH-dependent fla</span><span style="font-family:Verdana;">vin-reducing enzyme (Fre).</span><span style="font-family:Verdana;"> Reduction of the DmrB prosthetic group (FMN) was measured as a decrease in absorbance at 460 nm. NADPH, NADH, and </span><span style="font-family:Verdana;">DTT were unable to reduce DmrB. However, NADH/Fre was able to reduce </span><span style="font-family:Verdana;">DmrB within 70 min (initial rate of 1.3 μM/min), providing the basis for a future DmrB activity assay. Carbon monoxide (CO)/CO dehydrogenase/ferredoxin reduced DmrB more rapidly within 6 min. Both electr</span><span style="font-family:Verdana;">on transfer systems reduced a second flavin-containing archaeal protein MM1853, which is predicted to catalyze the third step of H</span><sub><span style="font-family:Verdana;">4</span></sub><span style="font-family:Verdana;">MPT biosynthesis. While NADH and NADPH were incapable of directly reducing the FMN cofactor of MM1853, DTT or NADH/Fre could eliminate the FMN peaks. These results establish the basis for new oxidoreductase assays that will facilitate testing several proposed DmrB mechanisms and defining the specific function of MM1853 in methanogen cofactor biosynthesis.</span></span>
基金grants from the National Natural Science Foundation of China，the National Key Clinical Specialty Discipline Construction Program,and Fujian Key Clinical Specialty Discipline Construction Program
文摘Background： Lipid storage myopathy （LSM） is a genetically heterogeneous group with variable clinical phenotypes. Late-onset multiple acyl-coenzyme A dehydrogenation deficiency （MADD） is a rather common form of LSM in China. Diagnosis and clinical management of it remain challenging, especially without robust muscle biopsy result and genetic detection. As the noninvasion and convenience, muscle magnetic resonance imaging （MRI） is a helpful assistant, diagnostic tool for neuromuscular disorders. However, the disease-specific MRI patterns of muscle involved and its diagnostic value in late-onset MADD have not been systematic analyzed. Methods： We assessed the MRI pattern and fat infiltration degree of the lower limb muscles in 28 late-onset MADD patients, combined with detailed clinical features and gene spectrum. Fat infiltration degree of the thigh muscle was scored while that ofgluteus was described as obvious or not. Associated muscular atrophy was defined as obvious muscle bulk reduction. Results： The mean scores were significantly different among the anterior, medial, and posterior thigh muscle groups. The mean of fat infiltration scores on posterior thigh muscle group was significantly higher than either anterior or medial thigh muscle group （P 〈 0.00 l）. Moreover, the mean score on medial thigh muscle group was significantly higher than that of anterior thigh muscle group （P 〈 0.01）. About half of the patients displayed fat infiltration and atrophy in gluteus muscles. Of 28 patients, 12 exhibited atrophy in medial and/ or posterior thigh muscle groups, especially in posterior thigh muscle group. Muscle edema pattern was not found in all the patients. Conclusions： Late-onset MADD patients show a typical muscular imaging pattern of fat infiltration and atrophy on anterior, posterior, and medial thigh muscle groups, with major involvement of posterior thigh muscle group and gluteus muscles and a sparing involvement of anterior thigh compartment. Our findings also suggest that muscle MRI of lower limbs is a helpful tool in guiding clinical evaluation on late-onset MADD.
基金This project was supported by the Knowledge Innovation Program of the Chinese Academy of Sciences.
文摘A membrane-bound protein was purified from rat liver mitochondria.After being di-gested with V8 protease,two peptides containing identical 14 amino acid residue sequences were obtained.Using the 14 amino acid peptide derived DNA sequence as gene specific primer,the cDNA of correspondent gene 5′-terminal and 3′-terminal were obtained by RACE technique.The full-length cDNA that encoded a protein of 616 amino acids was thus cloned,which included the above mentioned peptide sequence.The full length cDNA was highly homologous to that of human ETF-QO,indicating that it may be the cDNA of rat ETF-QO.ETF-QO is an iron sulfur protein located in mitochondria inner membrane containing two kinds of redox center:FAD and[4Fe-4S]center.After comparing the sequence from the cDNA of the 616 amino acids protein with that of the mature protein of rat liver mitochondria,it was found that the N terminal 32 amino acid residues did not exist in the mature protein,indicating that the cDNA was that of ETF-QOp.When the cDNA was expressed in Saccharomyces cerevisiae with inducible vectors,the protein product was enriched in mitochondrial fraction and exhibited electron transfer activity(NBT re-ductase activity)of ETF-QO.Results demonstrated that the 32 amino acid peptide was a mito-chondrial targeting peptide,and both FAD and iron-sulfur cluster were inserted properly into the expressed ETF-QO.ETF-QO had a high level expression in rat heart,liver and kidney.The fu-sion protein of GFP-ETF-QO co-localized with mitochondria in COS-7 cells.
基金supported by grants from the National Natural Science Foundation of China(22076104)the“Taishan Scholars”Program for Young Expert of Shandong Province(tsqn202103105).
文摘Ferroptosis,a type of programmed cell death,represents a distinct paradigm in cell biology.It is characterized by the iron-dependent accumulation of reactive oxygen species,which induce lipid peroxidation(LPO),and is orchestrated by the interplay between iron,lipid peroxides,and glutathione.In this review,we emphasize the frequently overlooked role of iron in LPO beyond the classical iron-driven Fenton reaction in several crucial processes that regulate cellular iron homeostasis,including iron intake and export as well as ferritinophagy,and the emerging roles of endoplasmic reticulum-resident flavoprotein oxidoreductases,especially P450 oxidoreductases,in modulating LPO.We summarize how various types of fatty acids(FAs),including saturated,monounsaturated,and polyunsaturated FAs,differentially influence ferroptosis when incorporated into phospholipids.Furthermore,we highlight the therapeutic potential of targeting LPO to mitigate ferroptosis and discuss the regulatory mechanisms of endogenous lipophilic radical-trapping antioxidants that confer resistance to ferroptosis,shedding light on therapeutic avenues for ferroptosis-associated diseases.
文摘The relationship between the levels of renalase and changes in proteinuria, hypertension, renal function, renal tubular epithelial cell apoptosis and B-cell lymphoma-2 （Bcl-2） expression was investigated in patients （chronic nephritis, primary nephrotic syndrome or other kidney disease） that underwent renal biopsy. The study group comprised 72 patients undergoing renal biopsy. Patient profiles and renal function were collected. Concentrations of renalase and Bcl-2 were measured by immunohistochemistry. Tubular injury was detected by periodic acid Schiff staining （PAS） and renal tubular epithelial cell apoptosis was assessed by TUNEL assay. The expression of renalase was significantly lower in renal biopsy specimens than in normal kidney tissues. There was a positive linear relationship between renalase and some serum and cardiac indices; a negative correlation was found between age, eGFR, Ccr and 24-h urinary protein. Renal tubule injury index and tubular epithelial cell apoptosis index showed a negative linear correlation with renalase. The results showed that renalase probably increased the expression of Bel-2. By two independent samples t-test, renalase levels were significantly increased in the non-hypertension group than in the hypertension group. One-way ANOVA showed that renalase expression was higher in samples with Lee＇s grade Ⅲ than in those with Lee＇s grade V. The expression of renalase was significantly decreased in patients who underwent renal biopsy, and was also associated with blood and renal function. The research proved that renalase may reduce renal tubular injury and apoptosis of renal tubular epithelial cells through the mitochondrial apoptosis pathway, finally achieving the purpose of delaying the progress of renal failure.
基金the Susan G.Komen Foundation Grant KG081069(PI:L.Z.Li)The Center for Magnietic Resonance and Optical Imaging,and an NIH supported research resource(P41-RR02305,PI:R.Reddy).
文摘Mitochondrial redox states provide important information about energy-linked biological processes and signaling events in tissues for various disease phenotypes including cancer.The redox scanning method developed at the Chance laboratory about 30 years ago has allowed 3D highresolution(∼50×50×10µm^(3))imaging of mitochondrial redox state in tissue on the basis of the fluorescence of NADH(reduced nicotinamide adenine dinucleotide)and Fp(oxidized flavoproteins including flavin adenine dinucleotide,i.e.,FAD).In this review,we illustrate its basic principles,recent technical developments,and biomedical applications to cancer diagnostic and therapeutic studies in small animal models.Recently developed calibration procedures for the redox imaging using reference standards allow quantification of nominal NADH and Fp concentrations,and the concentration-based redox ratios,e.g.,Fp/(Fp+NADH)and NADH/(Fp+NADH)in tissues.This calibration facilitates the comparison of redox imaging results acquired for different metabolic states at different times and/or with different instrumental settings.A redox imager using a CCD detector has been developed to acquire 3D images faster and with a higher in-plane resolution down to 10µm.Ex vivo imaging and in vivo imaging of tissue mitochondrial redox status have been demonstrated with the CCD imager.Applications of tissue redox imaging in small animal cancer models include metabolic imaging of glioma and myc-induced mouse mammary tumors,predicting the metastatic potentials of human melanoma and breast cancer mouse xenografts,differentiating precancerous and normal tissues,and monitoring the tumor treatment response to photodynamic therapy.Possible future directions for the development of redox imaging are also discussed.
基金the Susan G.Komen Foundation Grant KG081069(PI:L.Z.Li)an NIH supported research resource(P41-RR02305,PI:R.Reddy)+1 种基金the Network of Translational Research in Optical Imaging(NTROI)at the University of Pennsylvania(U54 CA105008,PI:W.S.El-Deiry)an NIH Grant UO1-CA105490(PI:L.A.Chodosh).
文摘The fluorescence properties of reduced nicotinamide adenine dinucleotide(NADH)and oxidizedflavoproteins(Fp)including flavin adenine dinucleotide(FAD)in the respiratory chain are sensitive indicators of intracellular metabolic states and have been applied to the studies of mitochondrial function with energy-linked processes.The redox scanner,a three-dimensional(3D)low temperature imager previously developed by Chance et al.,measures the in vivo metabolicproperties of tissue samples by acquiring fluorescence images of NADH and Fp.The redox ratios,i.e.Fp/(Fp+NADH)and NADH/(Fp+NADH),provided a sensitive index of the mitochondrialredox state and were determined based on relative signal intensity ratios.Here we report thefurther development of the redox scanning technique by using a calibration method to quantifythe nominal concentration of the fluorophores in tissues.The redox scanner exhibited very goodlinear response in the range of NADH concentration between 165–1318µM and Fp between90–720µM using snap-frozen solution standards.Tissue samples such as human tumor mousexenografts and various mouse organs were redox-scanned together with adjacent NADH and Fpstandards of known concentration at liquid nitrogen temperature.The nominal NADH and Fpconcentrations as well as the redox ratios in the tissue samples were quantified by normalizing the tissue NADH and Fp fluorescence signal to that of the snap-frozen solution standards.This calibration procedure allows comparing redox images obtained at different time,independent of instrument settings.The quantitative multi-slice redox images revealed heterogeneity inmitochondrial redox state in the tissues.
