254 results on '"Young-Tae Chang"'
Search Results
2. Reduced dynamicity and increased high-order protein assemblies in dense fibrillar component of the nucleolus under cellular senescence
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Minjeong Jo, Soomin Kim, Jeongeun Park, Young-Tae Chang, and Youngdae Gwon
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Nucleolus ,Cellular senescence ,Fibrillarin ,RNA-Protein interaction ,Protein aggregation ,Medicine (General) ,R5-920 ,Biology (General) ,QH301-705.5 - Abstract
Cellular senescence, which is triggered by various stressors, manifests as irreversible cell cycle arrest, resulting in the disruption of multiple nuclear condensates. One of the affected structures is the nucleolus, whose tripartite layout, separated into distinct liquid phases, allows for the stepwise progression of ribosome biogenesis. The dynamic properties of dense fibrillar components, a sub-nucleolar phase, are crucial for mediating pre-rRNA processing. However, the mechanistic link between the material properties of dense fibrillar components and cellular senescence remains unclear. We established a significant association between cellular senescence and alterations in nucleolar materiality and characteristics, including the number, size, and sphericity of individual subphases of the nucleolus. Senescent cells exhibit reduced fibrillarin dynamics, aberrant accumulation of high-order protein assemblies, such as oligomers and fibrils, and increased dense fibrillar component density. Intriguingly, the addition of RNA-interacting entities mirrored the diminished diffusion of fibrillarin in the nucleolus during cellular senescence. Thus, our findings contribute to a broader understanding of the intricate changes in the materiality of the nucleolus associated with cellular senescence and shed light on nucleolar dynamics in the context of aging and cellular stress.
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- 2024
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3. Osseointegrative and immunomodulative 3D-Printing Ti6Al4V-based implants embedded with biogenic hydroxyapatite
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Sangbae Park, Juo Lee, Jong-Jin Kim, Moongi Ji, Eunbee Cho, Hyun Bo Sim, Young-Tae Chang, Jong Hoon Chung, Man-Jeong Paik, Jungsil Kim, and Hoon Seonwoo
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Ti6Al4V implants ,Biogenic hydroxyapatite ,Selective laser melting ,Osseointegration ,Immunomodulation ,Materials of engineering and construction. Mechanics of materials ,TA401-492 - Abstract
Although titanium-based metal implants have become a game changer in dental and orthopedic therapies, they still have several problems such as late osseointegration and immune response. In this study, we present a novel strategy to develop Ti6Al4V-based implants embedded with biogenic hydroxyapatite derived from equine bone to overcome these problems. A selective laser melting technique was employed for facile fabrication with flexible fusing feedstock and regular uniform distribution of equine bone. The physicochemical characteristics, cell attachment and proliferation, osteogenic differentiation, osseointegration, inflammatory response, and metabolomics of the developed Ti6Al4V/equine bone composite were then investigated. The Ti6Al4V-based composite integrated with equine bone at a certain concentration has improved the crystalline structure (β-Ti) suitable for implantation and exhibited higher hydrophilicity and protein adsorption. They significantly promoted cell attachment, osteogenic differentiation, and anti-inflammatory effects in vitro. In vivo study confirmed the osseointegration and alleviated inflammatory responses. Furthermore, the Ti6Al4V-based implants integrated with equine bone significantly reduced metabolites associated with inflammatory responses both in vitro and in vivo. The observed reduction in inflammatory responses suggests a subsequent promotion of osteogenesis. These promising results position the Ti6Al4V-based implant integrated with equine bone as a potential candidate for replacing conventional dental and orthopedic implants.
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- 2024
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4. Improved tropoelastin synthesis in the skin by codon optimization and nucleotide modification of tropoelastin-encoding synthetic mRNA
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Sonia Golombek, Thomas Hoffmann, Ludmilla Hann, Markus Mandler, Sabine Schmidhuber, Josefin Weber, Young-Tae Chang, Roman Mehling, Andrea Ladinig, Christian Knecht, Johanna Leyens, Christian Schlensak, Hans Peter Wendel, Achim Schneeberger, and Meltem Avci-Adali
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MT: Oligonucleotides: Therapies and Applications ,synthetic mRNA ,tropoelastin ,protein replacement therapy ,tissue regeneration ,mRNA optimization ,Therapeutics. Pharmacology ,RM1-950 - Abstract
Loss of elastin due to aging, disease, or injury can lead to impaired tissue function. In this study, de novo tropoelastin (TE) synthesis is investigated in vitro and in vivo using different TE-encoding synthetic mRNA variants after codon optimization and nucleotide modification. Codon optimization shows a strong effect on protein synthesis without affecting cell viability in vitro, whereas nucleotide modifications strongly modulate translation and reduce cell toxicity. Selected TE mRNA variants (3, 10, and 30 μg) are then analyzed in vivo in porcine skin after intradermal application. Administration of 30 μg of native TE mRNA with a me1 Ψ modification or 10 and 30 μg of unmodified codon-optimized TE mRNA is required to increase TE protein expression in vivo. In contrast, just 3 μg of a codon-optimized TE mRNA variant with the me1 Ψ modification is able to increase protein expression. Furthermore, skin toxicity is investigated in vitro by injecting 30 μg of mRNA of selected TE mRNA variants into a human full-thickness skin model, and no toxic effects are observed. Thereby, for the first time, an increased dermal TE synthesis by exogenous administration of synthetic mRNA is demonstrated in vivo. Codon optimization of a synthetic mRNA can significantly increase protein expression and therapeutic outcome.
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- 2023
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5. Mitochondrial temperature homeostasis resists external metabolic stresses
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Mügen Terzioglu, Kristo Veeroja, Toni Montonen, Teemu O Ihalainen, Tiina S Salminen, Paule Bénit, Pierre Rustin, Young-Tae Chang, Takeharu Nagai, and Howard T Jacobs
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thermogenesis ,mitochondria ,organelle ,temperature ,OXPHOS ,bioenergetics ,Medicine ,Science ,Biology (General) ,QH301-705.5 - Abstract
Based on studies with a fluorescent reporter dye, Mito Thermo Yellow (MTY), and the genetically encoded gTEMP ratiometric fluorescent temperature indicator targeted to mitochondria, the temperature of active mitochondria in four mammalian and one insect cell line was estimated to be up to 15°C above that of the external environment to which the cells were exposed. High mitochondrial temperature was maintained in the face of a variety of metabolic stresses, including substrate starvation or modification, decreased ATP demand due to inhibition of cytosolic protein synthesis, inhibition of the mitochondrial adenine nucleotide transporter and, if an auxiliary pathway for electron transfer was available via the alternative oxidase, even respiratory poisons acting downstream of oxidative phosphorylation (OXPHOS) complex I. We propose that the high temperature of active mitochondria is an inescapable consequence of the biochemistry of OXPHOS and is homeostatically maintained as a primary feature of mitochondrial metabolism.
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- 2023
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6. Visualization of Metastatic Lung Cancer with TiNIR
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Seul-Ki Mun, Hyun Bo Sim, Ji Yeon Han, Hyeongyeong Kim, Dae-Han Park, Dong-Jo Chang, Sung-Tae Yee, Young-Tae Chang, and Jong-Jin Kim
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heme oxygenase 2 (HO2) ,TiNIR ,metastatic lung cancer ,biomarkers ,probe ,Computer applications to medicine. Medical informatics ,R858-859.7 - Abstract
The development of efficient biomarkers and probes for monitoring and treating cancer, specifically metastatic cancer, is a critical research area that can have a significant impact on both patient outcomes and drug discovery. In this context, TiNIR has been developed to detect tumor-initiating cells (TICs), with heme oxygenase 2 (HO2) as a promising therapeutic biomarker for tumor-initiating cells. In this study, TiNIR has demonstrated its effectiveness as an in vivo metastatic lung cancer tracker, highlighting its potential as a valuable tool in cancer research and therapy. The development of innovative approaches that selectively target metastatic cancers represents a promising avenue for improving survival rates and enhancing the quality of life of cancer patients.
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- 2023
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7. Novel Fluorescent Strategy for Discriminating T and B Lymphocytes Using Transport System
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Heewon Cho, Na-Kyeong Hong, and Young-Tae Chang
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fluorescent carbohydrate library ,high-throughput phenotypic screening ,gating-oriented live-cell distinction ,solute carrier ,B cell-specific probe ,Pharmacy and materia medica ,RS1-441 - Abstract
Fluorescent bioprobes are invaluable tools for visualizing live cells and deciphering complex biological processes by targeting intracellular biomarkers without disrupting cellular functions. In addition to protein-binding concepts, fluorescent probes utilize various mechanisms, including membrane, metabolism, and gating-oriented strategies. This study introduces a novel fluorescent mechanism distinct from existing ways. Here, we developed a B cell selective probe, CDrB, with unique transport mechanisms. Through SLC-CRISPRa screening, we identified two transporters, SLCO1B3 and SLC25A41, by sorting out populations exhibiting higher and lower fluorescence intensities, respectively, demonstrating contrasting activities. We confirmed that SLCO1B3, with comparable expression levels in T and B cells, facilitates the transport of CDrB into cells, while SLC25A41, overexpressed in T lymphocytes, actively exports CDrB. This observation suggests that SLC25A41 plays a crucial role in discriminating between T and B lymphocytes. Furthermore, it reveals the potential for the reversible localization of SLC25A41 to demonstrate its distinct activity. This study is the first report to unveil a novel strategy of SLC by exporting the probe. We anticipate that this research will open up new avenues for developing fluorescent probes.
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- 2024
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8. Visualizing inflammation with an M1 macrophage selective probe via GLUT1 as the gating target
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Heewon Cho, Haw-Young Kwon, Amit Sharma, Sun Hyeok Lee, Xiao Liu, Naoki Miyamoto, Jong-Jin Kim, Sin-Hyeog Im, Nam-Young Kang, and Young-Tae Chang
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Science - Abstract
Studying the specific roles of macrophage subsets has been hampered by a lack of subset-specific probes. Here the authors report an M1 selective fluorescent probe named CDr17, and demonstrate the suitability of this probe for tracking M1 macrophages in vivo.
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- 2022
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9. Neuroprotective effects of ex vivo-expanded regulatory T cells on trimethyltin-induced neurodegeneration in mice
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Seon-Young Park, HyeJin Yang, Minsook Ye, Xiao Liu, Insop Shim, Young-Tae Chang, and Hyunsu Bae
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Regulatory T cells ,Hippocampal neurodegeneration ,Trimethyltin ,Cell therapy ,Microglia ,Neurology. Diseases of the nervous system ,RC346-429 - Abstract
Abstract Background Trimethyltin (TMT) is a potent neurotoxicant that leads to hippocampal neurodegeneration. Regulatory T cells (Tregs) play an important role in maintaining the immune balance in the central nervous system (CNS), but their activities are impaired in neurodegenerative diseases. In this study, we aimed to determine whether adoptive transfer of Tregs, as a living drug, ameliorates hippocampal neurodegeneration in TMT-intoxicated mice. Methods CD4+CD25+ Tregs were expanded in vitro and adoptively transferred to TMT-treated mice. First, we explored the effects of Tregs on behavioral deficits using the Morris water maze and elevated plus maze tests. Biomarkers related to memory formation, such as cAMP response element-binding protein (CREB), protein kinase C (PKC), neuronal nuclear protein (NeuN), nerve growth factor (NGF), and ionized calcium binding adaptor molecule 1 (Iba1) in the hippocampus were examined by immunohistochemistry after killing the mouse. To investigate the neuroinflammatory responses, the polarization status of microglia was examined in vivo and in vitro using real-time reverse transcription polymerase chain reaction (rtPCR) and Enzyme-linked immunosorbent assay (ELISA). Additionally, the inhibitory effects of Tregs on TMT-induced microglial activation were examined using time-lapse live imaging in vitro with an activation-specific fluorescence probe, CDr20. Results Adoptive transfer of Tregs improved spatial learning and memory functions and reduced anxiety in TMT-intoxicated mice. Additionally, adoptive transfer of Tregs reduced neuronal loss and recovered the expression of neurogenesis enhancing molecules in the hippocampi of TMT-intoxicated mice. In particular, Tregs inhibited microglial activation and pro-inflammatory cytokine release in the hippocampi of TMT-intoxicated mice. The inhibitory effects of TMT were also confirmed via in vitro live time-lapse imaging in a Treg/microglia co-culture system. Conclusions These data suggest that adoptive transfer of Tregs ameliorates disease progression in TMT-induced neurodegeneration by promoting neurogenesis and modulating microglial activation and polarization.
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- 2022
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10. A palette of site-specific organelle fluorescent thermometers
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Xiao Liu, Takeru Yamazaki, Haw-Young Kwon, Satoshi Arai, and Young-Tae Chang
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Fluorescence ,Temperature ,Molecular rotor ,Organelle ,Thermometers ,Medicine (General) ,R5-920 ,Biology (General) ,QH301-705.5 - Abstract
Intracellular micro-temperature is closely related to cellular processes. Such local temperature inside cells can be measured by fluorescent thermometers, which are a series of fluorescent materials that convert the temperature information to detectable fluorescence signals. To investigate the intracellular temperature fluctuation in various organelles, it is essential to develop site-specific organelle thermometers. In this study, we develop a new series of fluorescent thermometers, Thermo Greens (TGs), to visualize the temperature change in almost all typical organelles. Through fluorescence lifetime-based cell imaging, it was proven that TGs allow the organelle-specific monitoring of temperature gradients created by external heating. The fluorescence lifetime-based thermometry shows that each organelle experiences a distinct temperature increment which depends on the distance away from the heat source. TGs are further demonstrated in the quantitative imaging of heat production at different organelles such as mitochondria and endoplasmic reticulum in brown adipocytes. To date, TGs are the first palette batch of small molecular fluorescent thermometers that can cover almost all typical organelles. These findings can inspire the development of new fluorescent thermometers and enhance the understanding of thermal biology in the future.
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- 2022
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11. Applicability and Limitations of Fluorescence Intensity-Based Thermometry Using a Palette of Organelle Thermometers
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Takeru Yamazaki, Xiao Liu, Young-Tae Chang, and Satoshi Arai
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intracellular thermometry ,organelle thermometer ,BODIPY rotor ,FLIM ,fluorescence ,Biochemistry ,QD415-436 - Abstract
Fluorescence thermometry is a microscopy technique in which a fluorescent temperature sensor records temperature changes as alterations of fluorescence signals. Fluorescence lifetime imaging (FLIM) is a promising method for quantitative analysis of intracellular temperature. Recently, we developed small-molecule thermometers, termed Organelle Thermo Greens, that target various organelles and achieved quantitative temperature mapping using FLIM. Despite its highly quantitative nature, FLIM-based thermometry cannot be used widely due to expensive instrumentation. Here, we investigated the applicability and limitations of fluorescence intensity (FI)-based analysis, which is more commonly used than FLIM-based thermometry. Temperature gradients generated by artificial heat sources and physiological heat produced by brown adipocytes were visualized using FI- and FLIM-based thermometry. By comparing the two thermometry techniques, we examined how the shapes of organelles and cells affect the accuracy of the temperature measurements. Based on the results, we concluded that FI-based thermometry could be used for “qualitative”, rather than quantitative, thermometry under the limited condition that the shape change and the dye leakage from the target organelle were not critical.
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- 2023
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12. Mechanism assay of interaction between blood vessels-near infrared probe and cell surface marker proteins of endothelial cells
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Muhammad Asri Abdul Sisak, Fiona Louis, Tomoyuki Miyao, Sun Hyeok Lee, Young-Tae Chang, and Michiya Matsusaki
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Fluorescent probes ,Endothelial cells ,CD133 protein ,Live imaging ,Medicine (General) ,R5-920 ,Biology (General) ,QH301-705.5 - Abstract
In vivo blood vessels imaging is crucial to study blood vessels related diseases in real-time. For this purpose, fluorescent based imaging is one of the utmost techniques for imaging a living system. The discovery of a new near-infrared probe (CyA-B2) by screening chemical probe library in our previous report which showed the most specific binding on the blood capillaries of the 3D-tissue models give us interest to study more about the binding site of this probe to the surface of endothelial cells main component cell of blood capillaries. By studying the competition assays of CyA-B2 using several potential surface markers of endothelial cells found through the chemical database (ChEMBL) and manually selected, CD133 gave the lowest IC50 (half maximal inhibitory concentration) value. Hence, CD133 protein which is expressed on the endothelial cell membrane was postulated to be the binding site due to the suppression of CyA-B2 on the blood capillaries by the competition assays. Since, CD133 is also expressed on many types of cancer cells, it would be useful to use CyA-B2 as a bioprobe to monitor or diagnostic tumor growth.
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- 2022
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13. Quantitative Structure-Activity Relationship of Fluorescent Probes and Their Intracellular Localizations
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Seong-Hyeon Park, Hong-Guen Lee, Xiao Liu, Sung Kwang Lee, and Young-Tae Chang
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machine learning ,QSAR ,fluorescent probes ,organelle tracker ,Biochemistry ,QD415-436 - Abstract
The development of organelle-specific fluorescent probes has been impeded by the absence of a comprehensive understanding of the relationship between the physicochemical properties of fluorescent probes and their selectivity towards specific organelles. Although a few machine learning models have suggested several physicochemical parameters that control the target organelle of the probes and have attempted to predict the target organelles, they have been challenged by low accuracy and a limited range of applicable organelles. Herein, we report a multi-organelle prediction QSAR model that is capable of predicting the destination of probes among nine categories, including cytosol, endoplasmic reticulum, Golgi body, lipid droplet, lysosome, mitochondria, nucleus, plasma membrane, and no entry. The model is trained using the Random Forest algorithm with a dataset of 350 organelle-specific fluorescent probes and 786 descriptors, and it is able to predict the target organelles of fluorescent probes with an accuracy of 75%. The MDI analysis of the model identifies 38 key parameters that have a significant impact on the organelle selectivity of the probes, including LogD, pKa, hydrophilic-lipophilic balance (HLB), and topological polar surface area (TPSA). This prediction model may be useful in developing new organelle-specific fluorescent probes by providing crucial variables that determine the destination of the probes.
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- 2023
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14. Distinctive Labeling of Live Monocytes and Neutrophils with a Single Fluorescent Molecule
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Songhui Kim, Masahiro Fukuda, Jung Yeol Lee, Young-Tae Chang, H. Shawn Je, and Beomsue Kim
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small-molecule fluorescent chemosensors ,differential cell counting ,immune cell typing ,UGT ,ABC transporters ,cell-type-specific fluorescence labeling ,Biochemistry ,QD415-436 - Abstract
(1) Background: a small-molecule fluorescent chemosensor, CDr20, tracks the resident macrophages based on the UGT1A7C activity in the brain, raising the possibility that additional immune cells expressing the UGT1A7C can be labeled with CDr20. (2) Methods: we applied CDr20 to various types of blood cells derived from hematopoietic organs (spleen and bone marrow) as well as peripheral blood to test the degree and selectivity of labeling of CDr20 in these cell types; (3) Results: CDr20 fluorescently labels monocytes/macrophages and neutrophils as a result of glucuronidation reaction (CDr20-Gluc), which is mediated with UGT1A7C. The selectivity of CDr20 labeling highly correlates with the Ugt1a7c expression level in immune cells. Moreover, CDr20-Gluc is exported from cells by a mechanism of how glucuronides within cells are excreted into extracellular space. Interestingly, the exportation of CDr20-Gluc is mainly observed in monocytes, potentially due to the monocyte-specific expression of ABCC transporters and this resulted in large differences in the degree of fluorescence retention in neutrophils (CDr20bright), compared to monocytes (CDr20dim) upon one hour of CDr20 incubation; (4) Conclusions: CDr20 can differentially label monocytes and neutrophils due to the variance in two different cellular enzymatic activities of UGT1A7C and ABCC. By using this property, CDr20 can be used to distinguish specific cell types within blood.
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- 2023
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15. Novel live cell fluorescent probe for human-induced pluripotent stem cells highlights early reprogramming population
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Sandhya Sriram, Nam-Young Kang, Subha Subramanian, Tannistha Nandi, Samydurai Sudhagar, Qiaorui Xing, Gerine Jin-Ling Tong, Allen Kuan-Liang Chen, Thekkeparambil Chandrabose Srijaya, Patrick Tan, Yuin-Han Loh, Young-Tae Chang, and Shigeki Sugii
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DOFLA library fluorescence dye ,Human induced pluripotent stem cell (hiPSC) ,Early stage pluripotency ,Mesenchymal-epithelial transition (MET) ,Adipose-derived stromal cell (ASC) ,Dental pulp stem cell (DPSC) ,Medicine (General) ,R5-920 ,Biochemistry ,QD415-436 - Abstract
Abstract Background Despite recent rapid progress in method development and biological understanding of induced pluripotent stem (iPS) cells, there has been a relative shortage of tools that monitor the early reprogramming process into human iPS cells. Methods We screened the in-house built fluorescent library compounds that specifically bind human iPS cells. After tertiary screening, the selected probe was analyzed for its ability to detect reprogramming cells in the time-dependent manner using high-content imaging analysis. The probe was compared with conventional dyes in different reprogramming methods, cell types, and cell culture conditions. Cell sorting was performed with the fluorescent probe to analyze the early reprogramming cells for their pluripotent characteristics and genome-wide gene expression signatures by RNA-seq. Finally, the candidate reprogramming factor identified was investigated for its ability to modulate reprogramming efficiency. Results We identified a novel BODIPY-derived fluorescent probe, BDL-E5, which detects live human iPS cells at the early reprogramming stage. BDL-E5 can recognize authentic reprogramming cells around 7 days before iPS colonies are formed and stained positive with conventional pluripotent markers. Cell sorting of reprogrammed cells with BDL-E5 allowed generation of an increased number and higher quality of iPS cells. RNA sequencing analysis of BDL-E5-positive versus negative cells revealed early reprogramming patterns of gene expression, which notably included CREB1. Reprogramming efficiency was significantly increased by overexpression of CREB1 and decreased by knockdown of CREB1. Conclusion Collectively, BDL-E5 offers a valuable tool for delineating the early reprogramming pathway and clinically applicable commercial production of human iPS cells.
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- 2021
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16. A mouse ear skin model to study the dynamics of innate immune responses against Staphylococcus aureus biofilms
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Aizat Iman Abdul Hamid, Laurence Nakusi, Mickael Givskov, Young-Tae Chang, Claire Marquès, and Pascale Gueirard
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Staphylococcus aureus ,Biofilm ,Planktonic form ,Inflammation ,Mouse ,Intravital imaging ,Microbiology ,QR1-502 - Abstract
Abstract Background Staphylococcus aureus is a human pathogen that is a common cause of nosocomial infections and infections on indwelling medical devices, mainly due to its ability to shift between the planktonic and the biofilm/sessile lifestyle. Biofilm infections present a serious problem in human medicine as they often lead to bacterial persistence and thus to chronic infections. The immune responses elicited by biofilms have been described as specific and ineffective. In the few experiments performed in vivo, the importance of neutrophils and macrophages as a first line of defence against biofilm infections was clearly established. However, the bilateral interactions between biofilms and myeloid cells remain poorly studied and analysis of the dynamic processes at the cellular level in tissues inoculated with biofilm bacteria is still an unexplored field. It is urgent, therefore, to develop biologically sound experimental approaches in vivo designed to extract specific immune signatures from the planktonic and biofilm forms of bacteria. Results We propose an in vivo transgenic mouse model, used in conjunction with intravital confocal microscopy to study the dynamics of host inflammatory responses to bacteria. Culture conditions were created to prepare calibrated inocula of fluorescent planktonic and biofilm forms of bacteria. A confocal imaging acquisition and analysis protocol was then drawn up to study the recruitment of innate immune cells in the skin of LysM-EGFP transgenic mice. Using the mouse ear pinna model, we showed that inflammatory responses to S. aureus can be quantified over time and that the dynamics of innate immune cells after injection of either the planktonic or biofilm form can be characterized. First results showed that the ability of phagocytic cells to infiltrate the injection site and their motility is not the same in planktonic and biofilm forms of bacteria despite the cells being considerably recruited in both cases. Conclusion We developed a mouse model of infection to compare the dynamics of the inflammatory responses to planktonic and biofilm bacteria at the tissue and cellular levels. The mouse ear pinna model is a powerful imaging system to analyse the mechanisms of biofilm tolerance to immune attacks.
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- 2020
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17. Human-T-Cell-Selective Fluorescent Probe
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Min Gao and Young-Tae Chang
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cell recognition ,fluorescent probes ,high-throughput screening ,mitochondria ,Cytology ,QH573-671 - Abstract
The identification of T and B lymphocytes has relied on using antibodies against different biomarkers as the gold standard. Emerging small molecule-based fluorescent probes have the potential to replace antibodies. Herein, we report the first human-T-cell-selective fluorescent probe, Mito thermo yellow (MTY), achieving the live T cells’ distinction from B cells, which was previously impossible without the help of antibodies. The unexpected cell selectivity of MTY is attributed to the higher mitochondria mass and membrane potential of T cells over B cells. This study enriches the toolbox for live cell distinction from complex cell communities.
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- 2022
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18. Imaging inflammation using an activated macrophage probe with Slc18b1 as the activation-selective gating target
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Sung-Jin Park, Beomsue Kim, Sejong Choi, Sivaraman Balasubramaniam, Sung-Chan Lee, Jung Yeol Lee, Heon Seok Kim, Jun-Young Kim, Jong-Jin Kim, Yong-An Lee, Nam-Young Kang, Jin-Soo Kim, and Young-Tae Chang
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Science - Abstract
Attempts to image activated macrophages in vivo have been hampered by selectivity and delivery problems. Here the authors develop a small molecule fluorescent probe specific to activated M1 and M2 macrophages, identify the orphan receptor Slc18b1/SLC18B1 as the mechanism of uptake, and use it to image atherosclerosis in mice.
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- 2019
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19. Optimal emission control under public port rivalry: A comparison of competitive and cooperative policy
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Kevin Hyosoo Park, Young-Tae Chang, and Jasmine Siu Lee Lam
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Emission control ,Public ports ,Port competition ,Negative externality ,Port pricing ,Shipment of goods. Delivery of goods ,HF5761-5780 - Abstract
This study examines the optimal emission control at two competing public ports. We first develop a two-stage duopoly model in which governments determine the emission standard that restrains shipping operators’ fuel quality and ports are involved in price competition, taking the emission standards as given. Then, non-cooperative and cooperative emission control cases are analyzed. The main result of this study is surprising. The results suggest that shipping operators bear fuel cost, congestion externality cost, and port price. The port price comprises markups from market power, congestion externality, and emission externality cost. Regardless of cooperation and governments’ knowledge of port pricing, the emission standard is optimal if and only if shipping operators’ fuel cost equals the emission externality cost.
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- 2020
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20. Optical visualisation of thermogenesis in stimulated single-cell brown adipocytes
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Rókus Kriszt, Satoshi Arai, Hideki Itoh, Michelle H. Lee, Anna G. Goralczyk, Xiu Min Ang, Aaron M. Cypess, Andrew P. White, Farnaz Shamsi, Ruidan Xue, Jung Yeol Lee, Sung-Chan Lee, Yanyan Hou, Tetsuya Kitaguchi, Thankiah Sudhaharan, Shin’ichi Ishiwata, E. Birgitte Lane, Young-Tae Chang, Yu-Hua Tseng, Madoka Suzuki, and Michael Raghunath
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Medicine ,Science - Abstract
Abstract The identification of brown adipose deposits in adults has led to significant interest in targeting this metabolically active tissue for treatment of obesity and diabetes. Improved methods for the direct measurement of heat production as the signature function of brown adipocytes (BAs), particularly at the single cell level, would be of substantial benefit to these ongoing efforts. Here, we report the first application of a small molecule-type thermosensitive fluorescent dye, ERthermAC, to monitor thermogenesis in BAs derived from murine brown fat precursors and in human brown fat cells differentiated from human neck brown preadipocytes. ERthermAC accumulated in the endoplasmic reticulum of BAs and displayed a marked change in fluorescence intensity in response to adrenergic stimulation of cells, which corresponded to temperature change. ERthermAC fluorescence intensity profiles were congruent with mitochondrial depolarisation events visualised by the JC-1 probe. Moreover, the averaged fluorescence intensity changes across a population of cells correlated well with dynamic changes such as thermal power, oxygen consumption, and extracellular acidification rates. These findings suggest ERthermAC as a promising new tool for studying thermogenic function in brown adipocytes of both murine and human origins.
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- 2017
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21. Estimating socio-economic impact from ship emissions at the Port of Incheon
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Young-Tae Chang, Eunbee Kim, Ahhyun Jo, and Hyosoo Park
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Commerce ,HF1-6182 - Abstract
Ports create harmful effects on their adjacent population because ships discharge noxious gases like SOX, NOX, and particulate matter (PM). To tackle this problem, some ports started to control emission through regulations such as Emission Control Areas (ECA) and Reduced Speed Zone (RSZ). This paper estimates the social cost of ship emission and eco-efficiency at the Port of Incheon (POI). We further examine how the ECA and RSZ designation can reduce the social cost. The estimation is based on the activity-based approach, where ship type, engine, and movement are used to measure fuel consumption and then emission. Results suggest that the social cost of ship emission at the POI amounts to $90,805,478. The eco-efficiency of the POI, compared to the one at the Port of Las Palmas in another study, is substantially better. Under RSZ, the corresponding emission abatement values are $4,485,308, $2,642,009 and $21,932,435 from SO2, NOX and PM reduction, respectively. If 1.0% and 0.1% sulfur fuel are used complying with rules of the ECA, the social cost savings amount to $8,174,947 and $12,868,842 from SO2 reduction.
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- 2017
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22. Photodynamic Approach for Teratoma-Free Pluripotent Stem Cell Therapy Using CDy1 and Visible Light
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Seung-Ju Cho, So-Yeon Kim, Soon-Jung Park, Naree Song, Haw-Young Kwon, Nam-Young Kang, Sung-Hwan Moon, Young-Tae Chang, and Hyuk-Jin Cha
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Chemistry ,QD1-999 - Published
- 2016
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23. Dynamic Changes in Maritime Research Capability in Chinese Universities
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Young-Tae Chang, Ahhyun Jo, and Kyoung-Suk Choi
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Transportation engineering ,TA1001-1280 ,Transportation and communications ,HE1-9990 - Abstract
This study determines the top fifty authors in China and their university affiliations in the maritime transportation field, compared to their world ranking. We refer to China in the broad sense of the Chinese economies, including not only mainland China and Hong Kong, but also Chinese Taipei (Taiwan) and Singapore. This study analyzes sixty-five SSCI and SCI journals in the field of maritime and transportation between the years 2000 and 2015. In terms of ranking, three indicators are employed: total number of articles, weighted score (indication of author contribution), and the impact score. With the exception of Shanghai Jiao Tong University, no other universities selected in the first phase of Project 985, which received billions of dollars in government support/aid, were listed in the world ranking. Star authors are deemed to have contributed greatly to the rankings of their affiliated universities. The future of China’s rankings is bright in view of the increasing number of papers being published by Chinese authors and universities and their strong grounding in quantitative methodologies.
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- 2019
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24. Pitfalls in Monitoring Mitochondrial Temperature Using Charged Thermosensitive Fluorophores
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Dominique Chrétien, Paule Bénit, Christine Leroy, Riyad El-Khoury, Sunyou Park, Jung Yeol Lee, Young-Tae Chang, Guy Lenaers, Pierre Rustin, and Malgorzata Rak
- Subjects
mitochondria ,temperature ,thermosensitive fluorescent probes ,MitoThermo Yellow ,Biochemistry ,QD415-436 - Abstract
Mitochondria are the source of internal heat which influences all cellular processes. Hence, monitoring mitochondrial temperature provides a unique insight into cell physiology. Using a thermosensitive fluorescent probe MitoThermo Yellow (MTY), we have shown recently that mitochondria within human cells are maintained at close to 50 °C when active, increasing their temperature locally by about 10 °C. Initially reported in the HEK293 cell line, we confirmed this finding in the HeLa cell line. Delving deeper, using MTY and MTX (MitoThermo X), a modified version of MTY, we unraveled some caveats related to the nature of these charged fluorophores. While enabling the assessment of mitochondrial temperature in HEK and HeLa cell lines, the reactivity of MTY to membrane potential variations in human primary skin fibroblasts precluded local temperature monitoring in these cells. Chemical modification of MTY into MTX did not result in a temperature probe unresponsive to membrane potential variations that could be universally used in any cell type to determine mitochondrial temperature. Thus, the cell-type dependence of MTY in measuring mitochondrial temperature, which is likely due to the variable binding of this dye to specific internal mitochondrial components, should imply cautiousness while using these nanothermometers for mitochondrial temperature analysis.
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- 2020
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25. Development of background-free tame fluorescent probes for intracellular live cell imaging
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Samira Husen Alamudi, Rudrakanta Satapathy, Jihyo Kim, Dongdong Su, Haiyan Ren, Rajkumar Das, Lingna Hu, Enrique Alvarado-Martínez, Jung Yeol Lee, Christian Hoppmann, Eduardo Peña-Cabrera, Hyung-Ho Ha, Hee-Sung Park, Lei Wang, and Young-Tae Chang
- Subjects
Science - Abstract
The success of a fluorescent dye as a molecular probe to monitor the intracellular activity of biomolecules depends on its physicochemical characteristics. Here, the authors use a predictive model to identify key features that allow them to design cell permeable, background-free fluorescent probes.
- Published
- 2016
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26. RNAi Reveals Phase-Specific Global Regulators of Human Somatic Cell Reprogramming
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Cheng-Xu Delon Toh, Jun-Wei Chan, Zheng-Shan Chong, Hao Fei Wang, Hong Chao Guo, Sandeep Satapathy, Dongrui Ma, Germaine Yen Lin Goh, Ekta Khattar, Lin Yang, Vinay Tergaonkar, Young-Tae Chang, James J. Collins, George Q. Daley, Keng Boon Wee, Chadi A. EL Farran, Hu Li, Yoon-Pin Lim, Frederic A. Bard, and Yuin-Han Loh
- Subjects
human somatic cell reprogramming ,genome-wide siRNA screen ,SFRS11 ,reprogramming specific alternative splicing ,ZNF207 ,Biology (General) ,QH301-705.5 - Abstract
Incomplete knowledge of the mechanisms at work continues to hamper efforts to maximize reprogramming efficiency. Here, we present a systematic genome-wide RNAi screen to determine the global regulators during the early stages of human reprogramming. Our screen identifies functional repressors and effectors that act to impede or promote the reprogramming process. Repressors and effectors form close interacting networks in pathways, including RNA processing, G protein signaling, protein ubiquitination, and chromatin modification. Combinatorial knockdown of five repressors (SMAD3, ZMYM2, SFRS11, SAE1, and ESET) synergistically resulted in ∼85% TRA-1-60-positive cells. Removal of the novel splicing factor SFRS11 during reprogramming is accompanied by rapid acquisition of pluripotency-specific spliced forms. Mechanistically, SFRS11 regulates exon skipping and mutually exclusive splicing of transcripts in genes involved in cell differentiation, mRNA splicing, and chromatin modification. Our study provides insights into the reprogramming process, which comprises comprehensive and multi-layered transcriptional, splicing, and epigenetic machineries.
- Published
- 2016
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27. Fabrication of Blood Capillary Models for Live Imaging Microarray Analysis
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Muhammad Asri Abdul Sisak, Fiona Louis, Sun Hyeok Lee, Young-Tae Chang, and Michiya Matsusaki
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blood capillary models ,fibrin gels ,collagen microfibers ,Mechanical engineering and machinery ,TJ1-1570 - Abstract
Conventional microarray analysis usually deals with the monolayer or two-dimensional (2D) assays for the high-throughput screening applications. Even though these cell-based assays are effective for preliminary screening at least to have information on cytotoxicity, they do not adequately re-create the in vivo complexity of three-dimensional (3D) tissues. In this study, 3D-blood capillary models were constructed by using physiological collagen microfibers (CMF), which provide the extracellular matrix in the complex tissue. Micro-droplets of fibrin gels containing CMF, endothelial cells, and fibroblasts were cultured for five days in 48-wells plate to provide a medium-throughput system for screening applications. Blood capillaries networks were formed by optimizing the concentration of CMF used and the number of cells. Finally, this screening method was a powerful assay for the application on the selection of not only a specific chemical probe for blood capillary live-imaging, but also a drug, aptamer, and peptide with potential blood vessel targeting property.
- Published
- 2020
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28. Mitochondria are physiologically maintained at close to 50 °C.
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Dominique Chrétien, Paule Bénit, Hyung-Ho Ha, Susanne Keipert, Riyad El-Khoury, Young-Tae Chang, Martin Jastroch, Howard T Jacobs, Pierre Rustin, and Malgorzata Rak
- Subjects
Biology (General) ,QH301-705.5 - Abstract
In endothermic species, heat released as a product of metabolism ensures stable internal temperature throughout the organism, despite varying environmental conditions. Mitochondria are major actors in this thermogenic process. Part of the energy released by the oxidation of respiratory substrates drives ATP synthesis and metabolite transport, but a substantial proportion is released as heat. Using a temperature-sensitive fluorescent probe targeted to mitochondria, we measured mitochondrial temperature in situ under different physiological conditions. At a constant external temperature of 38 °C, mitochondria were more than 10 °C warmer when the respiratory chain (RC) was fully functional, both in human embryonic kidney (HEK) 293 cells and primary skin fibroblasts. This differential was abolished in cells depleted of mitochondrial DNA or treated with respiratory inhibitors but preserved or enhanced by expressing thermogenic enzymes, such as the alternative oxidase or the uncoupling protein 1. The activity of various RC enzymes was maximal at or slightly above 50 °C. In view of their potential consequences, these observations need to be further validated and explored by independent methods. Our study prompts a critical re-examination of the literature on mitochondria.
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- 2018
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29. A Chemical Probe that Labels Human Pluripotent Stem Cells
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Nao Hirata, Masato Nakagawa, Yuto Fujibayashi, Kaori Yamauchi, Asako Murata, Itsunari Minami, Maiko Tomioka, Takayuki Kondo, Ting-Fang Kuo, Hiroshi Endo, Haruhisa Inoue, Shin-ichi Sato, Shin Ando, Yoshinori Kawazoe, Kazuhiro Aiba, Koh Nagata, Eihachiro Kawase, Young-Tae Chang, Hirofumi Suemori, Koji Eto, Hiromitsu Nakauchi, Shinya Yamanaka, Norio Nakatsuji, Kazumitsu Ueda, and Motonari Uesugi
- Subjects
Biology (General) ,QH301-705.5 - Abstract
A small-molecule fluorescent probe specific for human pluripotent stem cells would serve as a useful tool for basic cell biology research and stem cell therapy. Screening of fluorescent chemical libraries with human induced pluripotent stem cells (iPSCs) and subsequent evaluation of hit molecules identified a fluorescent compound (Kyoto probe 1 [KP-1]) that selectively labels human pluripotent stem cells. Our analyses indicated that the selectivity results primarily from a distinct expression pattern of ABC transporters in human pluripotent stem cells and from the transporter selectivity of KP-1. Expression of ABCB1 (MDR1) and ABCG2 (BCRP), both of which cause the efflux of KP-1, is repressed in human pluripotent stem cells. Although KP-1, like other pluripotent markers, is not absolutely specific for pluripotent stem cells, the identified chemical probe may be used in conjunction with other reagents.
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- 2014
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30. The Development of Novel Near-Infrared (NIR) Tetraarylazadipyrromethene Fluorescent Dyes
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Young-Tae Chang, Parag Mukherjee, Sung-Chan Lee, and Duanting Zhai
- Subjects
Near Infra-Red ,fluorescent ,aza-BODIPY ,Technology ,Electrical engineering. Electronics. Nuclear engineering ,TK1-9971 ,Engineering (General). Civil engineering (General) ,TA1-2040 ,Microscopy ,QH201-278.5 ,Descriptive and experimental mechanics ,QC120-168.85 - Abstract
Novel structures of an near-infrared (NIR) tetraarylazadipyrromethene (aza-BODIPY) series have been prepared. We designed the core structure containing two amido groups at the para-position of the aromatic rings. The amido group was incorporated to secure insensitivity to pH and to ensure a bathochromic shift to the NIR region. Forty members of aza-BODIPY compounds were synthesized by substitution of the acetyl group with commercial amines on the alpha bromide. The physicochemical properties and photostability were investigated and the fluorescence emission maxima (745~755 nm) were found to be in the near infrared (NIR) range of fluorescence.
- Published
- 2013
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31. Container port selection factors: heterogeneity among major market players
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Sang-Yoon Lee, Young-Tae Chang, and Paul Tae-Woo Lee
- Subjects
Commerce ,HF1-6182 - Abstract
This study explores the main factors considered when shippers and container shipping lines select their import/export and transshipment ports. In the present study, 38 container port selection indices were chosen from the previous research and field interviews. The scores of the 38 items were collected via survey to the three major maritime/port market players: shippers, shipping lines, and container terminal operators. In order to analyze the different priorities imposed on the port selection factors by the three market players, the ANOVA method has been employed. The empirical test shows the different perceptions about port selection attributes among service suppliers and demanders. In addition, the 38 items have been categorized into seven key factors through an exploratory factor analysis. The ANOVA technique was employed again to analyze the perspective differences for the port selection factors among the market players. The results show that there are significant differences among the players assessing the importance of the three port choice factors: liners and terminal operators give more weight to ‘hinterland and terminal basic conditions’ than shippers; terminal operators do not take ‘line operation’ as seriously as carriers and shippers; the factor of ‘terminal operation’ is more significantly considered by liners and terminal operators than by shippers.
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- 2010
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32. Overview of interport competition: Issues and methods
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Young-Tae Chang and Paul T.W. Lee
- Subjects
Commerce ,HF1-6182 - Abstract
Port competition attracted much scholarly attention in Northwest Europe during the 1980s. Following the rise of powerful economies in East Asia, particularly during the 1980s and 1990s, port competition has become an important phenomenon with the top five container ports in the world being located in the region. This paper aims to overview major port competition issues and outlines and analyzes the main alternative methodologies that researchers have employed to address them, referring to 70 items, mostly papers but including a few books and reports
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- 2007
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33. The Vital Dye CDr10b Labels the Zebrafish Mid-Intestine and Lumen
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Veronika Sander, Shantanu Patke, Jung Y. Lee, Young-Tae Chang, and Alan J. Davidson
- Subjects
zebrafish ,gut development ,mid-intestine ,CDr10b ,vital dye ,laser ablation ,Organic chemistry ,QD241-441 - Abstract
We describe the use of the fluorescent reporter compound CDr10b to label mid-intestinal structures in zebrafish larvae after simple immersion. CDr10b is deposited into the gut where it initially fills the lumen and is excreted. Using laser-mediated injury of the intestine, we show that CDr10b provides a useful readout of the integrity and repair of the epithelial cell barrier. In addition, CDr10b specifically labels the absorptive mid-intestine segment that is analogous to the mammalian small intestine. By perturbing retinoic acid signaling, which regulates the size of the mid-intestine segment, we show that CDr10b is a valuable tool to rapidly assess developmental malformations of the intestine in live animals.
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- 2017
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34. In vivo detection of macrophage recruitment in hind-limb ischemia using a targeted near-infrared fluorophore.
- Author
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Jung Sun Yoo, Raj Kumar Das, Zhi Yen Jow, and Young-Tae Chang
- Subjects
Medicine ,Science - Abstract
Macrophages are an essential component of the immune system and have protective and pathogenic functions in various diseases. Imaging of macrophages in vivo could furnish new tools to advance evaluation of disease and therapies. Critical limb ischemia is a disease in which macrophages have considerable pathogenic roles, and are potential targets for cell-based immunotherapy. We sought to develop a new near-infrared fluorescence (NIRF) imaging probe to target macrophages specifically in vivo in various pathological states, including hind-limb ischemia. We rapidly screened the photostable cyanine-based NIRF library against different blood cell lines. The identified monocyte/macrophage-selective hit was tested in vitro in live-cell labeling assay. Non-invasive NIRF imaging was performed with murine models of paw inflammation by lipopolysaccharide challenge and hind-limb ischemia with femoral artery ligation. in vivo macrophage targeting was further evaluated using intravital microscopy with Csf1r-EGFP transgenic mice and immunofluorescent staining with macrophage-specific markers. We discovered MF800, a Macrophage-specific near-infrared Fluorophore, which showed selective live-cell imaging performance in a panel of cell lines and primary human blood samples. MF800 outperforms the clinically-available NIRF contrast agent ICG for in vivo specificity in paw inflammation and hind-limb ischemia models. We observed a marked overlap of MF800-labeled cells and EGFP-expressing macrophages in intravital imaging of Csf1r-EGFP transgenic mice. In the histologic analysis, MF800-positive cells also expressed the macrophage markers CD68 and CD169. NIRF imaging showcased the potential of using MF800 to understand macrophage behavior in vivo, characterize macrophage-associated diseases, and may help in assessing therapeutic responses in the clinic.
- Published
- 2014
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35. A Simple BODIPY-Based Viscosity Probe for Imaging of Cellular Viscosity in Live Cells
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Dongdong Su, Chai Lean Teoh, Nengyue Gao, Qing-Hua Xu, and Young-Tae Chang
- Subjects
BODIPY ,fluorescent probes ,sensors ,viscosity ,FLIM ,cell imaging ,Chemical technology ,TP1-1185 - Abstract
Intracellular viscosity is a fundamental physical parameter that indicates the functioning of cells. In this work, we developed a simple boron-dipyrromethene (BODIPY)-based probe, BTV, for cellular mitochondria viscosity imaging by coupling a simple BODIPY rotor with a mitochondria-targeting unit. The BTV exhibited a significant fluorescence intensity enhancement of more than 100-fold as the solvent viscosity increased. Also, the probe showed a direct linear relationship between the fluorescence lifetime and the media viscosity, which makes it possible to trace the change of the medium viscosity. Furthermore, it was demonstrated that BTV could achieve practical applicability in the monitoring of mitochondrial viscosity changes in live cells through fluorescence lifetime imaging microscopy (FLIM).
- Published
- 2016
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36. Identification of fluorescent compounds with non-specific binding property via high throughput live cell microscopy.
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Sangeeta Nath, Virginia A Spencer, Ju Han, Hang Chang, Kai Zhang, Gerald V Fontenay, Charles Anderson, Joel M Hyman, Marit Nilsen-Hamilton, Young-Tae Chang, and Bahram Parvin
- Subjects
Medicine ,Science - Abstract
INTRODUCTION: Compounds exhibiting low non-specific intracellular binding or non-stickiness are concomitant with rapid clearing and in high demand for live-cell imaging assays because they allow for intracellular receptor localization with a high signal/noise ratio. The non-stickiness property is particularly important for imaging intracellular receptors due to the equilibria involved. METHOD: Three mammalian cell lines with diverse genetic backgrounds were used to screen a combinatorial fluorescence library via high throughput live cell microscopy for potential ligands with high in- and out-flux properties. The binding properties of ligands identified from the first screen were subsequently validated on plant root hair. A correlative analysis was then performed between each ligand and its corresponding physiochemical and structural properties. RESULTS: The non-stickiness property of each ligand was quantified as a function of the temporal uptake and retention on a cell-by-cell basis. Our data shows that (i) mammalian systems can serve as a pre-screening tool for complex plant species that are not amenable to high-throughput imaging; (ii) retention and spatial localization of chemical compounds vary within and between each cell line; and (iii) the structural similarities of compounds can infer their non-specific binding properties. CONCLUSION: We have validated a protocol for identifying chemical compounds with non-specific binding properties that is testable across diverse species. Further analysis reveals an overlap between the non-stickiness property and the structural similarity of compounds. The net result is a more robust screening assay for identifying desirable ligands that can be used to monitor intracellular localization. Several new applications of the screening protocol and results are also presented.
- Published
- 2012
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37. Identification of cancer cell-line origins using fluorescence image-based phenomic screening.
- Author
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Jun-Seok Lee, Yun Kyung Kim, Han Jo Kim, Siti Hajar, Yee Ling Tan, Nam-Young Kang, Shin Hui Ng, Chang No Yoon, and Young-Tae Chang
- Subjects
Medicine ,Science - Abstract
Universal phenotyping techniques that can discriminate among various states of biological systems have great potential. We applied 557 fluorescent library compounds to NCI's 60 human cancer cell-lines (NCI-60) to generate a systematic fluorescence phenotypic profiling data. By the kinetic fluorescence intensity analysis, we successfully discriminated the organ origin of all the 60 cell-lines.
- Published
- 2012
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38. Styryl-based and tricyclic compounds as potential anti-prion agents.
- Author
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Erika Chung, Frances Prelli, Stephen Dealler, Woo Sirl Lee, Young-Tae Chang, and Thomas Wisniewski
- Subjects
Medicine ,Science - Abstract
Prion diseases currently have no effective therapy. These illnesses affect both animal and human populations, and are characterized by the conformational change of a normal self protein PrP(C) (C for cellular) to a pathological and infectious conformer, PrP(Sc) (Sc for scrapie). We used a well characterized tissue culture model of prion infection, where mouse neuroblastoma cells (N2a) were infected with 22L PrP(Sc), to screen compounds for anti-prion activity. In a prior study we designed a library of styryl based, potential imaging compounds which were selected for high affinity binding to Alzheimer's disease β-amyloid plaques and good blood-brain barrier permeability. In the current study we screened this library for activity in the N2a/22L tissue culture system. We also tested the anti-prion activity of two clinically used drugs, trimipramine and fluphenazine, in the N2a/22L system. These were selected based on their structural similarity to quinacrine, which was previously reported to have anti-prion activity. All the compounds were also screened for toxicity in tissue culture and their ability to disaggregate amyloid fibrils composed of PrP and β-amyloid synthetic peptides in vitro. Two of the imaging agents, 23I and 59, were found to be both effective at inhibiting prion infection in N2a/22L tissue culture and to be non-toxic. These two compounds, as well as trimipramine and fluphenazine were evaluated in vivo using wild-type CD-1 mice infected peripherally with 139A PrP(Sc). All four agents significantly prolonged the asymptomatic incubation period of prion infection (p
- Published
- 2011
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39. Α-galactosylceramide analogs with weak agonist activity for human iNKT cells define new candidate anti-inflammatory agents.
- Author
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Gabriel Bricard, Manjunatha M Venkataswamy, Karl O A Yu, Jin S Im, Rachel M Ndonye, Amy R Howell, Natacha Veerapen, Petr A Illarionov, Gurdyal S Besra, Qian Li, Young-Tae Chang, and Steven A Porcelli
- Subjects
Medicine ,Science - Abstract
CD1d-restricted natural killer T cells with invariant T cell receptor α chains (iNKT cells) are a unique lymphocyte subset that responds to recognition of specific lipid and glycolipid antigens. They are conserved between mice and humans and exert various immunoregulatory functions through their rapid secretion of a variety of cytokines and secondary activation of dendritic cells, B cells and NK cells. In the current study, we analyzed the range of functional activation states of human iNKT cells using a library of novel analogs of α-galactosylceramide (αGalCer), the prototypical iNKT cell antigen. Measurement of cytokines secreted by human iNKT cell clones over a wide range of glycolipid concentrations revealed that iNKT cell ligands could be classified into functional groups, correlating with weak versus strong agonistic activity. The findings established a hierarchy for induction of different cytokines, with thresholds for secretion being consistently lowest for IL-13, higher for interferon-γ (IFNγ), and even higher for IL-4. These findings suggested that human iNKT cells can be intrinsically polarized to selective production of IL-13 by maintaining a low level of activation using weak agonists, whereas selective polarization to IL-4 production cannot be achieved through modulating the strength of the activating ligand. In addition, using a newly designed in vitro system to assess the ability of human iNKT cells to transactivate NK cells, we found that robust secondary induction of interferon-γ secretion by NK cells was associated with strong but not weak agonist ligands of iNKT cells. These results indicate that polarization of human iNKT cell responses to Th2-like or anti-inflammatory effects may best be achieved through selective induction of IL-13 and suggest potential discrepancies with findings from mouse models that may be important in designing iNKT cell-based therapies in humans.
- Published
- 2010
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40. Theranostics application of tumor-initiating cell probe TiY in non-small cell lung cancer
- Author
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Yong-An Lee, Chee Chong Jonathan Lek, Gao Rong, Zhengwei Wu, S Shathishwaran, Jia Hui Jane Lee, Wai Leong Tam, Torsten Wuestefeld, Sung-Jin Park, Sangyong Jung, Beomsue Kim, Nam-Young Kang, and Young-Tae Chang
- Subjects
Medicine (miscellaneous) ,Pharmacology, Toxicology and Pharmaceutics (miscellaneous) - Published
- 2023
41. Applicability and Limitations of Fluorescence Intensity-Based Thermometry Using a Palette of Organelle Thermometers
- Author
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Arai, Takeru Yamazaki, Xiao Liu, Young-Tae Chang, and Satoshi
- Subjects
intracellular thermometry ,organelle thermometer ,BODIPY rotor ,FLIM ,fluorescence - Abstract
Fluorescence thermometry is a microscopy technique in which a fluorescent temperature sensor records temperature changes as alterations of fluorescence signals. Fluorescence lifetime imaging (FLIM) is a promising method for quantitative analysis of intracellular temperature. Recently, we developed small-molecule thermometers, termed Organelle Thermo Greens, that target various organelles and achieved quantitative temperature mapping using FLIM. Despite its highly quantitative nature, FLIM-based thermometry cannot be used widely due to expensive instrumentation. Here, we investigated the applicability and limitations of fluorescence intensity (FI)-based analysis, which is more commonly used than FLIM-based thermometry. Temperature gradients generated by artificial heat sources and physiological heat produced by brown adipocytes were visualized using FI- and FLIM-based thermometry. By comparing the two thermometry techniques, we examined how the shapes of organelles and cells affect the accuracy of the temperature measurements. Based on the results, we concluded that FI-based thermometry could be used for “qualitative”, rather than quantitative, thermometry under the limited condition that the shape change and the dye leakage from the target organelle were not critical.
- Published
- 2023
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42. Data from A Macrophage-Specific Fluorescent Probe for Intraoperative Lymph Node Staging
- Author
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Young-Tae Chang, Pamela Yun Xiang Koh, Zhi Yen Jow, Sung-Chan Lee, and Jung Sun Yoo
- Abstract
Successful identification of nodal metastases in patients with cancer is crucial to prescribe suitable treatment regimens that can improve recurrence-free survival. Although some new imaging technologies for nodal staging have been developed, such as nanoparticle-enhanced MRI and quantum-dot–based fluorescence imaging, sound technologies for intraoperative differentiation of metastatic and inflamed lymph nodes remain lacking. In this study, we illustrate the feasibility of using a macrophage-specific fluorescent probe (MFP) to visualize sentinel lymph nodes during surgery, highlighting abnormalities related to inflammation and tumor infiltration with signal enhancement and reduction methods using this technology. MFP was identified by high-throughput screening of fluorescent small-molecule libraries synthesized with a diversity-oriented approach. It selectively visualized monocyte and macrophage cell populations in vitro, by live-cell imaging and flow cytometry, as well as in vivo, for imaging-guided surgery. Collectively, this study provides preclinical proof of concept for an intraoperative imaging platform to accurately assess lymph node status, eliminating the need for invasive nodal dissections that can contribute to complications of cancer therapy. Cancer Res; 74(1); 44–55. ©2013 AACR.
- Published
- 2023
43. Supplementary Methods, Figures 1 - 13 from A Macrophage-Specific Fluorescent Probe for Intraoperative Lymph Node Staging
- Author
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Young-Tae Chang, Pamela Yun Xiang Koh, Zhi Yen Jow, Sung-Chan Lee, and Jung Sun Yoo
- Abstract
PDF file - 5664K, Supplementary Figure 1: Overview of high-throughput screening, Supplementary Figure 2: Synthesis scheme for MFP, Supplementary Figure 3: Identification spectra of MFP obtained by using 1H-NMR and 13C-NMR, Supplementary Figure 4: Identification LC-MS spectrum of MFP, Supplementary Figure 5: Physiochemical properties of MFP, Supplementary Figure 6: Macrophage differentiation with the U-937 cell line by using PMA stimulation, Supplementary Figure 7: Selective macrophage staining with MFP for different concentrations and incubation times, Supplementary Figure 8: Effect of MFP on cell viability, Supplementary Figure 9: Enrichment of T lymphocytes, monocytes and granulocytes from human blood, Supplementary Figure 10: Macrophage differentiation with peripheral blood monocytes, Supplementary Figure 11: Characterization of MFP+ cells in inflamed lymph nodes, Supplementary Figure 12: Characterization of MFP+ cells in metastatic lymph nodes, Supplementary Figure 13: Structural selectivity test with several analogues of MFP, Supplementary Methods.
- Published
- 2023
44. Target identification of mouse stem cell probe CDy1 as ALDH2 and Abcb1b through live-cell affinity-matrix and ABC CRISPRa library†
- Author
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Young-Hyun Go, Naoki Miyamoto, Xuezhi Bi, Larissa Miasiro Ciaramicoli, Heon Seok Kim, Haw-Young Kwon, Young Hyun Yu, Nam-Young Kang, Hyung-Ho Ha, Jin-Soo Kim, Seong-Wook Yun, Beomsue Kim, Young-Tae Chang, and Hyuk-Jin Cha
- Subjects
Mechanism (biology) ,Regeneration (biology) ,Cell ,ATP-binding cassette transporter ,Biology ,Biochemistry, Genetics and Molecular Biology (miscellaneous) ,Biochemistry ,Embryonic stem cell ,Cell biology ,Chemistry ,medicine.anatomical_structure ,Chemistry (miscellaneous) ,medicine ,Identification (biology) ,Stem cell ,Molecular Biology ,Reprogramming - Abstract
CDy1 is a powerful tool to distingusih embryonic stem cells for reprogramming studies and regeneration medicine. However, the stem cell selectivity mechanism of CDy1 has not been fully understood. Here, we report ALDH2 and ABCB1 as the molecular targets of CDy1, elucidated by live-cell affinity-matrix and ABC transporter CRISPRa library screening. The two unique orthogonal mechanisms provide the potential of multi-demensional cellular distinction of specific cell types., CDy1 is a powerful tool to distingusih embryonic stem cells for reprogramming studies and regeneration medicine.
- Published
- 2021
45. Adoptive therapy with amyloid-β specific regulatory T cells alleviates Alzheimer's disease
- Author
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HyeJin Yang, Seon-Young Park, Hyunjung Baek, Chanju Lee, Geehoon Chung, Xiao Liu, Ji Hwan Lee, Byungkyu Kim, Minjin Kwon, Hyojung Choi, Hyung Joon Kim, Jae Yoon Kim, Younsub Kim, Ye-Seul Lee, Gaheon Lee, Sun Kwang Kim, Jin Su Kim, Young-Tae Chang, Woo Sang Jung, Kyung Hwa Kim, and Hyunsu Bae
- Subjects
Inflammation ,Mice ,Amyloid beta-Peptides ,Alzheimer Disease ,Medicine (miscellaneous) ,Animals ,Cognitive Dysfunction ,Pharmacology, Toxicology and Pharmaceutics (miscellaneous) ,T-Lymphocytes, Regulatory - Published
- 2022
46. Lipid-Oriented Live-Cell Distinction of B and T Lymphocytes
- Author
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Young-Tae Chang, Stuart N. Berry, Jae Won Lee, Justin Kok Soon Tan, Yun-Kyu Choi, Kangkyun Baek, Solip Park, Jae-Seong Yang, Gun Tae Jung, Kwang Pyo Kim, Soohyun Park, H. W. Lee, Haw-Young Kwon, Sangho Kim, Ki Hean Kim, Raj Kumar Das, Kyeng Min Park, Kimoon Kim, Sun Hyeok Lee, Nam-Young Kang, National Research Foundation of Korea, Government of South Korea, Institute for Basic Science (South Korea), Pohang University of Science and Technology, and Ministry of Education (South Korea)
- Subjects
Cell type ,T-Lymphocytes ,Cell ,Bone Marrow Cells ,010402 general chemistry ,01 natural sciences ,Biochemistry ,Catalysis ,Cell membrane ,Mice ,Colloid and Surface Chemistry ,medicine ,Animals ,Progenitor cell ,Fluorescent Dyes ,B-Lymphocytes ,biology ,Chemistry ,Cell Membrane ,Lymphocyte differentiation ,Cell Differentiation ,General Chemistry ,Complex cell ,Flow Cytometry ,0104 chemical sciences ,Cell biology ,Multicellular organism ,medicine.anatomical_structure ,Lipidomics ,biology.protein ,Antibody - Abstract
The identification of each cell type is essential for understanding multicellular communities. Antibodies set as biomarkers have been the main toolbox for cell-type recognition, and chemical probes are emerging surrogates. Herein we report the first small-molecule probe, CDgB, to discriminate B lymphocytes from T lymphocytes, which was previously impossible without the help of antibodies. Through the study of the origin of cell specificity, we discovered an unexpected novel mechanism of membrane-oriented live-cell distinction. B cells maintain higher flexibility in their cell membrane than T cells and accumulate the lipid-like probe CDgB more preferably. Because B and T cells share common ancestors, we tracked the cell membrane changes of the progenitor cells and disclosed the dynamic reorganization of the membrane properties over the lymphocyte differentiation progress. This study casts an orthogonal strategy for the small-molecule cell identifier and enriches the toolbox for live-cell distinction from complex cell communities., This research was supported by the Institute for Basic Science (IBS) (IBS-R007-A1), the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIT) (no. 2020R1A2C2009776), the Ministry of Education (no. 2020R1A6A1A03047902), and the intramural fund of POSTECH (Pohang University of Science and Technology).
- Published
- 2021
47. Abstract GS3-10: Partitioning of cancer therapeutics in nuclear condensates
- Author
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Arup K. Chakraborty, John Mantiega, Anthony A. Hyman, Ann Boija, Mrityunjoy Kar, Patrick M. McCall, Jesse M. Platt, Charles H. Li, Mengyang Fan, Victoria E. Clark, Tong Lee, Alessandra Dall’Agnese, Jonathan E. Henninger, Krishna Shrinivas, Ido Sagi, Phillip A. Sharp, Dylan J. Taatjes, Tim-Michael Decker, Tinghu Zhang, Jing-Ke Weng, Eliot L. Coffey, Lena K. Afeyan, Alicia V. Zamudio, Nathanael S. Gray, Benjamin R. Sabari, Isaac A. Klein, Richard A. Young, Nancy M. Hannett, Young-Tae Chang, Ozgur Oksuz, Yang Guo, and Susana Wilson Hawken
- Subjects
Cisplatin ,Cancer Research ,Chemistry ,Cell ,Small molecule ,In vitro ,MED1 ,Cell biology ,chemistry.chemical_compound ,medicine.anatomical_structure ,Oncology ,Live cell imaging ,In vivo ,medicine ,DNA ,medicine.drug - Abstract
The molecules of the cell are compartmentalized into membrane- and non-membrane-bound organelles. Many non-membrane-bound organelles are phase-separated biomolecular condensates with distinct physicochemical properties that can absorb and concentrate specific proteins and nucleic acids involved in discrete biochemical processes. We reasoned that selective condensate partitioning might also occur with small molecule drugs whose targets occur within condensates, and that the therapeutic index and efficacy of such compounds might therefore relate to their ability to partition into condensates. To test this idea, we focused our study on nuclear condensates reported in cell lines, demonstrated they occur in normal human and malignant breast cancer, and developed assays to test clinically active antineoplastic small molecule drugs relative to these condensates.To study the behavior of drugs within condensates, these were modeled in vitro with purified proteins and visualized by fluorescent confocal microscopy. We found that cisplatin, tamoxifen, JQ1, THZ1, and mitoxantrone are concentrated in specific protein condensates in vitro, and that this occurs through physicochemical properties independent of the drug target. For each drug, the small molecule partitioned into the same condensate in vitro in which its established target resides in vivo. A screen of a chemically diverse fluorescent probes and mutant-protein condensates demonstrated that pi-system interactions between aromatic moieties in the protein and small molecule govern concentration in condensates. These results show that clinically important drugs partition into specific protein condensates in vitro by virtue of defined chemical properties, thereby altering their local concentration.Alkylating agents are a class of commonly used antineoplastic compounds, of which cisplatin is a prominent example. In vitro droplet assays revealed that cisplatin is selectively concentrated in transcriptional condensates, and that this ability is required for efficient platination of target DNA. In cell studies revealed that cisplatin preferentially targets DNA contained within MED1 condensates, and disrupts the genetic regulatory elements that compose phase-separated transcriptional condensates. Live cell imaging demonstrated that transcriptional condensates are dissolved by cisplatin, whereas other condensates remain intact. Thus, we conclude that cisplatin preferentially modifies transcriptional condensate-associated DNA in cells, and that this causes selective condensate disruption. The mechanisms that produce drug resistance can provide clues to drug activity in the clinical setting. Investigating the behavior of tamoxifen within ER transcriptional condensates demonstrated that it disrupts these condensates in vitro and on oncogenes in cells; hormonal therapy resistant ESR1 mutations render these condensates resistant. MED1 overexpression, a poorly understood mechanism of tamoxifen resistance, increased the size of ER-MED1 condensates, thereby rending tamoxifen more dilute and ineffective when concentrated therein. This suggest that altering the size and nature of transcription condensates in breast cancer can mediate drug resistance in the clinical setting.Our results show that antineoplastic drugs partition selectively into condensates, that this can occur through physicochemical properties independent of their molecular targets, and that resistance to drugs may occur through condensate altering mechanisms. These results have implications for development of efficacious cancer therapeutics; effective target engagement will depend on factors such as drug partitioning in condensates. Assays of the type described here may thus help optimize condensate partitioning, target engagement, and the therapeutic index of drugs for cancer treatment. Citation Format: Isaac Klein, Ann Boija, Lena Afeyan, Susana Wilson Hawken, Mengyang Fan, Alessandra Dall'Agnese, Ozgur Oksuz, Jonathan Henninger, Krishna Shrinivas, Benjamin Sabari, Ido Sagi, Victoria Clark, Jesse Platt, Mrityunjoy Kar, Patrick McCall, Alicia Zamudio, John Mantiega, Eliot Coffey, Charles Li, Nancy Hannett, Yang Guo, Tim-Michael Decker, Tong Lee, Tinghu Zhang, Jing-Ke Weng, Dylan Taatjes, Arup Chakraborty, Phillip Sharp, Young Tae Chang, Anthony Hyman, Nathanael Gray, Richard Young. Partitioning of cancer therapeutics in nuclear condensates [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr GS3-10.
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- 2021
48. Novel live cell fluorescent probe for human-induced pluripotent stem cells highlights early reprogramming population
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Subha Subramanian, Gerine Jin-Ling Tong, Yuin-Han Loh, Shigeki Sugii, Thekkeparambil Chandrabose Srijaya, Tannistha Nandi, Qiao Rui Xing, Nam-Young Kang, Sandhya Sriram, Allen Chen, Samydurai Sudhagar, Patrick Tan, and Young-Tae Chang
- Subjects
0301 basic medicine ,Cell type ,Induced Pluripotent Stem Cells ,Cell ,Population ,Adipose-derived stromal cell (ASC) ,Method ,Medicine (miscellaneous) ,Biology ,Biochemistry, Genetics and Molecular Biology (miscellaneous) ,lcsh:Biochemistry ,03 medical and health sciences ,0302 clinical medicine ,Human induced pluripotent stem cell (hiPSC) ,medicine ,Dental pulp stem cell (DPSC) ,Tra-1-60 ,Humans ,lcsh:QD415-436 ,Induced pluripotent stem cell ,education ,cAMP responsive element binding protein (CREB) ,Mesenchymal-epithelial transition (MET) ,Cells, Cultured ,Fluorescent Dyes ,DOFLA library fluorescence dye ,education.field_of_study ,lcsh:R5-920 ,Three-dimensional (3D) microcarrier-based culture system ,Golgi marker ,Cell Biology ,Cell sorting ,Cellular Reprogramming ,Cell biology ,030104 developmental biology ,medicine.anatomical_structure ,Cell culture ,Early stage pluripotency ,Molecular Medicine ,Stem cell ,Transcriptome ,lcsh:Medicine (General) ,Reprogramming ,030217 neurology & neurosurgery - Abstract
Background Despite recent rapid progress in method development and biological understanding of induced pluripotent stem (iPS) cells, there has been a relative shortage of tools that monitor the early reprogramming process into human iPS cells. Methods We screened the in-house built fluorescent library compounds that specifically bind human iPS cells. After tertiary screening, the selected probe was analyzed for its ability to detect reprogramming cells in the time-dependent manner using high-content imaging analysis. The probe was compared with conventional dyes in different reprogramming methods, cell types, and cell culture conditions. Cell sorting was performed with the fluorescent probe to analyze the early reprogramming cells for their pluripotent characteristics and genome-wide gene expression signatures by RNA-seq. Finally, the candidate reprogramming factor identified was investigated for its ability to modulate reprogramming efficiency. Results We identified a novel BODIPY-derived fluorescent probe, BDL-E5, which detects live human iPS cells at the early reprogramming stage. BDL-E5 can recognize authentic reprogramming cells around 7 days before iPS colonies are formed and stained positive with conventional pluripotent markers. Cell sorting of reprogrammed cells with BDL-E5 allowed generation of an increased number and higher quality of iPS cells. RNA sequencing analysis of BDL-E5-positive versus negative cells revealed early reprogramming patterns of gene expression, which notably included CREB1. Reprogramming efficiency was significantly increased by overexpression of CREB1 and decreased by knockdown of CREB1. Conclusion Collectively, BDL-E5 offers a valuable tool for delineating the early reprogramming pathway and clinically applicable commercial production of human iPS cells.
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- 2021
49. SAMHD1 controls innate immunity by regulating condensation of immunogenic self RNA
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Shovamayee Maharana, Stefanie Kretschmer, Susan Hunger, Xiao Yan, David Kuster, Sofia Traikov, Thomas Zillinger, Marc Gentzel, Nagaraja Chappidi, Nadja Lucas, Katharina Isabell Maser, Henrike Maatz, Alexander Rapp, Virginie Marchand, K. Venkatesan Iyer, Akshita Chhabra, Young-Tae Chang, Yuri Motorin, Norbert Hubner, Gunther Hartmann, Anthony Hyman, Simon Alberti, and Min Ae Lee-Kirsch
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Exonucleases ,SAM Domain and HD Domain-Containing Protein 1 ,Autoimmune Diseases of the Nervous System ,Interferon Type I ,Humans ,Cell Biology ,Nervous System Malformations ,Molecular Biology ,Antiviral Agents ,Immunity, Innate ,RNA, Double-Stranded - Abstract
Recognition of pathogen-derived foreign nucleic acids is central to innate immune defense. This requires discrimination between structurally highly similar self and nonself nucleic acids to avoid aberrant inflammatory responses as in the autoinflammatory disorder Aicardi-Goutières syndrome (AGS). How vast amounts of self RNA are shielded from immune recognition to prevent autoinflammation is not fully understood. Here we show that SAM domain and HD domain-containing protein 1 (SAMHD1), one of the AGS-causing genes, functions as a single-stranded RNA (ssRNA) 3’exonuclease, the lack of which causes cellular RNA accumulation. Increased ssRNA in cells leads to dissolution of RNA-protein condensates, which sequester immunogenic double-stranded RNA (dsRNA). Release of sequestered dsRNA from condensates triggers activation of antiviral type I interferon via retinoic acid-inducible gene I-like receptors. Our results establish SAMHD1 as a key regulator of cellular RNA homeostasis and demonstrate that buffering of immunogenic self RNA by condensates regulates innate immune responses.
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- 2021
50. Neuroprotective Effects of Ex Vivo Expanded Regulatory T Cells on Trimethyltin Induced Neurodegeneration in Mice
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HyeJin Yang, Insop Shim, Seon-Young Park, Hyunsu Bae, Xiao Liu, Young-Tae Chang, and Minsook Ye
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nervous system ,Chemistry ,Neurodegeneration ,medicine ,Pharmacology ,medicine.disease ,Neuroprotection ,Ex vivo - Abstract
BackgroundTrimethyltin (TMT) is a potent neurotoxicant that leads to hippocampal neurodegeneration. Regulatory T cells (Tregs) play an important role in maintaining the immune balance in the central nervous system (CNS), but their activities are impaired in neurodegenerative diseases. In this study, we aimed to determine whether adoptive transfer of Tregs, as a living drug, ameliorates hippocampal neurodegeneration in TMT-intoxicated mice.MethodsCD4+CD25+ Tregs were expanded in vitro and adoptively transferred to TMT-treated mice. First, we explored the effects of Tregs on behavioral deficits using the Morris water maze and elevated plus maze tests. Biomarkers related to memory formation, such as cAMP response element-binding protein (CREB), protein kinase C (PKC), neuronal nuclear protein (NeuN), nerve growth factor (NGF), and ionized calcium binding adaptor molecule 1 (Iba1) in the hippocampus were examined by immunohistochemistry after mouse sacrifice. To investigate the neuroinflammatory responses, the polarization status of microglia was examined in vivo and in vitro using real-time reverse transcription polymerase chain reaction (rtPCR) and Enzyme-linked immunosorbent assy (ELISA). Additionally, the inhibitory effects of Tregs on TMT-induced microglial activation were examined using time-lapse live imaging in vitro with an activation-specific fluorescence probe, CDr20.ResultsAdoptive transfer of Tregs improved spatial learning and memory functions and reduced anxiety in TMT-intoxicated mice. Additionally, adoptive transfer of Tregs reduced neuronal loss and recovered the expression of neurogenesis enhancing molecules in the hippocampi of TMT-intoxicated mice. In particular, Tregs inhibited microglial activation and pro-inflammatory cytokine release in the hippocampi of TMT-intoxicated mice. The inhibitory effects of TMT were also confirmed via in vitro live time lapse imaging in a Treg/microglia co-culture system.ConclusionsThese data suggest that adoptive transfer of Tregs ameliorates disease progression in TMT-induced neurodegeneration by promoting neurogenesis and modulating microglial activation and polarization.
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- 2021
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