The Experts below are selected from a list of 46134 Experts worldwide ranked by ideXlab platform
Jason W Chin - One of the best experts on this subject based on the ideXlab platform.
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efficient multisite unnatural amino acid Incorporation in mammalian cells via optimized pyrrolysyl trna synthetase trna expression and engineered erf1
Journal of the American Chemical Society, 2014Co-Authors: Wolfgang H Schmied, Simon J Elsasser, Chayasith Uttamapinant, Jason W ChinAbstract:The efficient, site-specific introduction of unnatural amino acids into proteins in mammalian cells is an outstanding challenge in realizing the potential of genetic code expansion approaches. Addressing this challenge will allow the synthesis of modified recombinant proteins and augment emerging strategies that introduce new chemical functionalities into proteins to control and image their function with high spatial and temporal precision in cells. The Efficiency of unnatural amino acid Incorporation in response to the amber stop codon (UAG) in mammalian cells is commonly considered to be low. Here we demonstrate that tRNA levels can be limiting for unnatural amino acid Incorporation Efficiency, and we develop an optimized pyrrolysyl-tRNA synthetase/tRNACUA expression system, with optimized tRNA expression for mammalian cells. In addition, we engineer eRF1, that normally terminates translation on all three stop codons, to provide a substantial increase in unnatural amino acid Incorporation in response to...
Ning Jiang - One of the best experts on this subject based on the ideXlab platform.
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hesperetin and hesperidin improved β carotene Incorporation Efficiency intestinal cell uptake and retinoid concentrations in tissues
Journal of Agricultural and Food Chemistry, 2019Co-Authors: Meimei Nie, Zhongyuan Zhang, Chunquan Liu, Wuyang Huang, Chunju Liu, Ning JiangAbstract:Dietary constituents can influence the bioavailability of carotenoids. This study investigated the effect of citrus flavanones on β-carotene (Bc) bioavailability using four experimental models: in vitro digestion procedure, synthetic mixed micelles, Caco-2 cell monolayers, and gavage experiments in mice. The addition of hesperetin (Hes, 25 μM) and hesperidin (Hes-G, 25 μM) standards significantly increased the Incorporation Efficiency of the Bc standard to 68.7 ± 3.6 and 75.2 ± 7.5% ( p < 0.05), respectively. However, the addition of naringenin (Nar, 25 μM) and naringin (Nar-G, 25 μM) standards significantly reduced the Incorporation Efficiency of Bc by 23.8 and 26.4%, respectively ( p < 0.05). The increases in scavenger receptor class B type I (SR-BI) expression promoted by citrus flavanones played an important role in Bc cellular absorption in the Caco-2 cell model. Furthermore, after 3 days of gavage, four citrus flavanones (7.5 mg kg-1 day-1) increased the retinoid concentrations in tissues; in contrast, after 7 days of gavage, Nar and Nar-G significantly decreased hepatic retinoid concentrations ( p < 0.05). This finding suggested that the Incorporation Efficiency into micelles was the main step governing carotenoid bioavailability.
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Hesperetin and Hesperidin Improved β‑Carotene Incorporation Efficiency, Intestinal Cell Uptake, and Retinoid Concentrations in Tissues
2019Co-Authors: Meimei Nie, Zhongyuan Zhang, Chunquan Liu, Wuyang Huang, Chunju Liu, Ning JiangAbstract:Dietary constituents can influence the bioavailability of carotenoids. This study investigated the effect of citrus flavanones on β-carotene (Bc) bioavailability using four experimental models: in vitro digestion procedure, synthetic mixed micelles, Caco-2 cell monolayers, and gavage experiments in mice. The addition of hesperetin (Hes, 25 μM) and hesperidin (Hes-G, 25 μM) standards significantly increased the Incorporation Efficiency of the Bc standard to 68.7 ± 3.6 and 75.2 ± 7.5% (p < 0.05), respectively. However, the addition of naringenin (Nar, 25 μM) and naringin (Nar-G, 25 μM) standards significantly reduced the Incorporation Efficiency of Bc by 23.8 and 26.4%, respectively (p < 0.05). The increases in scavenger receptor class B type I (SR-BI) expression promoted by citrus flavanones played an important role in Bc cellular absorption in the Caco-2 cell model. Furthermore, after 3 days of gavage, four citrus flavanones (7.5 mg kg–1 day–1) increased the retinoid concentrations in tissues; in contrast, after 7 days of gavage, Nar and Nar-G significantly decreased hepatic retinoid concentrations (p < 0.05). This finding suggested that the Incorporation Efficiency into micelles was the main step governing carotenoid bioavailability
Jaeseung Hahn - One of the best experts on this subject based on the ideXlab platform.
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extrusion of rna from a dna origami based nanofactory
ACS Nano, 2020Co-Authors: Jaeseung Hahn, Leo Y T Chou, Rasmus S Sorensen, Richard Guerra, William M ShihAbstract:Cells often spatially organize biomolecules to regulate biological interactions. Synthetic mimicry of complex spatial organization may provide a route to similar levels of control for artificial systems. As a proof-of-principle, we constructed an RNA-extruding nanofactory using a DNA-origami barrel with an outer diameter of 60 nm as a chassis for integrated rolling-circle transcription and processing of RNA through spatial organization of DNA templates, RNA polymerases, and RNA endonucleases. The Incorporation Efficiency of molecular components was quantified to be roughly 50% on designed sites within the DNA-origami chassis. Each integrated nanofactory with RNA-producing units, composed of DNA templates and RNA polymerases, produced 100 copies of target RNA in 30 min on average. Further integration of RNA endonucleases that cleave rolling-circle transcripts from concatemers into monomers resulted in 30% processing Efficiency. Disabling spatial organization of molecular components on DNA origami resulted ...
Dong Wang - One of the best experts on this subject based on the ideXlab platform.
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epigenetic dna modification n6 methyladenine causes site specific rna polymerase ii transcriptional pausing
Journal of the American Chemical Society, 2017Co-Authors: Wei Wang, Jenny Chong, Dong WangAbstract:N6-Methyladenine (N6-mA or 6 mA) is an epigenetic DNA modification in eukaryotic genomes. In contrast to the well-established roles of 5-methylcytosine for epigenetic regulation of gene expression, the functional roles of N6-mA remain elusive. In particular, the impact of N6-mA modification of the DNA template on RNA polymerase II (pol II) transcription elongation is not known. In this work, using the Saccharomyces cerevisiae pol II transcriptional elongation system as a model, we investigated the molecular mechanism of pol II recognition and processing of N6-mA sites via both biochemical and structural approaches. We found that N6-mA causes site-specific pol II pausing/stalling. Structural analysis revealed that while N6-mA can reach the +1 template position, the stability of the N6-mA and UTP base pairing is compromised. Taken together, we reveal that the presence of the 6-methyl group on adenine reduces Incorporation Efficiency and promotes backtracking translocation. Our studies with yeast pol II prov...
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Epigenetic DNA Modification N6‑Methyladenine Causes Site-Specific RNA Polymerase II Transcriptional Pausing
2017Co-Authors: Wei Wang, Jenny Chong, Dong WangAbstract:N6-Methyladenine (N6-mA or 6 mA) is an epigenetic DNA modification in eukaryotic genomes. In contrast to the well-established roles of 5-methylcytosine for epigenetic regulation of gene expression, the functional roles of N6-mA remain elusive. In particular, the impact of N6-mA modification of the DNA template on RNA polymerase II (pol II) transcription elongation is not known. In this work, using the Saccharomyces cerevisiae pol II transcriptional elongation system as a model, we investigated the molecular mechanism of pol II recognition and processing of N6-mA sites via both biochemical and structural approaches. We found that N6-mA causes site-specific pol II pausing/stalling. Structural analysis revealed that while N6-mA can reach the +1 template position, the stability of the N6-mA and UTP base pairing is compromised. Taken together, we reveal that the presence of the 6-methyl group on adenine reduces Incorporation Efficiency and promotes backtracking translocation. Our studies with yeast pol II provide molecular insights into understanding the impacts of N6-mA on pol II transcription dynamics in different organisms
Wolfgang H Schmied - One of the best experts on this subject based on the ideXlab platform.
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efficient multisite unnatural amino acid Incorporation in mammalian cells via optimized pyrrolysyl trna synthetase trna expression and engineered erf1
Journal of the American Chemical Society, 2014Co-Authors: Wolfgang H Schmied, Simon J Elsasser, Chayasith Uttamapinant, Jason W ChinAbstract:The efficient, site-specific introduction of unnatural amino acids into proteins in mammalian cells is an outstanding challenge in realizing the potential of genetic code expansion approaches. Addressing this challenge will allow the synthesis of modified recombinant proteins and augment emerging strategies that introduce new chemical functionalities into proteins to control and image their function with high spatial and temporal precision in cells. The Efficiency of unnatural amino acid Incorporation in response to the amber stop codon (UAG) in mammalian cells is commonly considered to be low. Here we demonstrate that tRNA levels can be limiting for unnatural amino acid Incorporation Efficiency, and we develop an optimized pyrrolysyl-tRNA synthetase/tRNACUA expression system, with optimized tRNA expression for mammalian cells. In addition, we engineer eRF1, that normally terminates translation on all three stop codons, to provide a substantial increase in unnatural amino acid Incorporation in response to...
