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The high selectivity and affinity of antibodies toward their antigens have made them a highly valuable tool in disease therapy, diagnosis, and basic research. A plethora of chemical and genetic approaches have been devised to make antibodies accessible to more "undruggable" targets and equipped with new functions of illustrating or regulating biological processes more precisely. In this Review, in addition to introducing how naked antibodies and various antibody conjugates (such as antibody-drug conjugates, antibody-oligonucleotide conjugates, antibody-enzyme conjugates, etc.) work in therapeutic applications, special attention has been paid to how chemistry tools have helped to optimize the therapeutic outcome (i.e., with enhanced efficacy and reduced side effects) or facilitate the multifunctionalization of antibodies, with a focus on emerging fields such as targeted protein degradation, real-time live-cell imaging, catalytic labeling or decaging with spatiotemporal control as well as the engagement of antibodies inside cells. With advances in modern chemistry and biotechnology, well-designed antibodies and their derivatives via size miniaturization or multifunctionalization together with efficient delivery systems have emerged, which have gradually improved our understanding of important biological processes and paved the way to pursue novel targets for potential treatments of various diseases.
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Anticuerpos , Inmunoconjugados , Anticuerpos/uso terapéutico , Inmunoconjugados/uso terapéutico , Biotecnología , OligonucleótidosRESUMEN
The overexpression of PDIA1 in cancer has spurred the quest for effective inhibitors. However, existing inhibitors often bind to only one active site, limiting their efficacy. In our study, we developed a PROTAC-mimetic probe dPA by combining PACMA31 (PA) analogs with cereblon-directed pomalidomide. Through protein profiling and analysis, we confirmed dPA's specific interaction with PDIA1's active site cysteines. We further synthesized PROTAC variants with a thiophene ring and various linkers to enhance degradation efficiency. Notably, H4, featuring a PEG linker, induced significant PDIA1 degradation and inhibited cancer cell proliferation similarly to PA. The biosafety profile of H4 is comparable to that of PA, highlighting its potential for further development in cancer therapy. Our findings highlight a novel strategy for PDIA1 inhibition via targeted degradation, offering promising prospects in cancer therapeutics. This approach may overcome limitations of conventional inhibitors, presenting new avenues for advancing anti-cancer interventions.
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Antineoplásicos , Proliferación Celular , Humanos , Antineoplásicos/farmacología , Antineoplásicos/química , Antineoplásicos/síntesis química , Línea Celular Tumoral , Proliferación Celular/efectos de los fármacos , Relación Dosis-Respuesta a Droga , Ensayos de Selección de Medicamentos Antitumorales , Sondas Moleculares/química , Sondas Moleculares/farmacología , Sondas Moleculares/síntesis química , Estructura Molecular , Procolágeno-Prolina Dioxigenasa , Proteína Disulfuro Isomerasas/antagonistas & inhibidores , Proteína Disulfuro Isomerasas/metabolismo , Relación Estructura-Actividad , Péptidos/química , Péptidos/farmacologíaRESUMEN
Cell-surface proteins are important drug targets but historically have posed big challenges for the complete elimination of their functions. Herein, we report antibody-peptide conjugates (Ab-CMAs) in which a peptide targeting chaperone-mediated autophagy (CMA) was conjugated with commercially available monoclonal antibodies for specific cell-surface protein degradation by taking advantage of lysosomal degradation pathways. Unique features of Ab-CMAs, including cell-surface receptor- and E3 ligase-independent degradation, feasibility towards different cell-surface proteins (e.g., epidermal growth factor receptor (EGFR), programmed cell death ligandâ 1 (PD-L1), human epidermal growth factor receptor 2 (HER2)) by a simple change of the antibody, and successful tumor inhibition in vivo, make them attractive protein degraders for biomedical research and therapeutic applications. As the first example employing CMA to degrade proteins from the outside in, our findings may also shed new light on CMA, a degradation pathway typically targeting cytosolic proteins.
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Autofagia Mediada por Chaperones , Neoplasias , Humanos , Autofagia/fisiología , Proteínas de la Membrana/metabolismo , Neoplasias/metabolismo , Péptidos/metabolismo , Lisosomas/metabolismoRESUMEN
Targeted degradation of the cell-surface and extracellular proteins via the endogenous lysosomal degradation pathways, such as lysosome-targeting chimeras (LYTACs), has recently emerged as an attractive tool to expand the scope of extracellular chemical biology. Herein, we report a series of recombinant proteins genetically fused to insulin-like growth factor 2 (IGF2), which we termed iLYTACs, that can be conveniently obtained in high yield by standard cloning and bacterial expression in a matter of days. We showed that both type-I iLYTACs, in which IGF2 was fused to a suitable affibody or nanobody capable of binding to a specific protein target, and type-II iLYTAC (or IGF2-Z), in which IGF2 was fused to the IgG-binding Z domain that served as a universal antibody-binding adaptor, could be used for effective lysosomal targeting and degradation of various extracellular and membrane-bound proteins-of-interest. These heterobifunctional iLYTACs are fully genetically encoded and can be produced on a large scale from conventional E. coli expression systems without any form of chemical modification. In the current study, we showed that iLYTACs successfully facilitated the cell uptake, lysosomal localization, and efficient lysosomal degradation of various disease-relevant protein targets from different mammalian cell lines, including EGFR, PD-L1, CD20, and α-synuclein. The antitumor properties of iLYTACs were further validated in a mouse xenograft model. Overall, iLYTACs represent a general and modular strategy for convenient and selective targeted protein degradation, thus expanding the potential applications of current LYTACs and related techniques.
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Escherichia coli , Proteínas de la Membrana , Humanos , Ratones , Animales , Proteínas de la Membrana/metabolismo , Escherichia coli/metabolismo , Transducción de Señal , Lisosomas/metabolismo , Línea Celular , Mamíferos/metabolismo , Factor II del Crecimiento Similar a la Insulina/metabolismo , Factor II del Crecimiento Similar a la Insulina/farmacologíaRESUMEN
C-Jun N-terminal kinase (JNK) is a key mediator involved in a variety of physiological processes. JNK activation is regulated in a complex manner by upstream kinases and phosphatases, and plays an important role in physiological processes such as the immune response and neuronal function. Therefore, JNK has become a therapeutic target for neurodegenerative diseases, ankylosing spondylitis, psoriasis, arthritis and other diseases. Inhibition of JNK activation in mitochondria holds great potential for Parkinson's disease (PD) therapy. However, no specific mitochondrial-targeted JNK inhibitor has been reported. We have developed a mitochondrial-targeted JNK inhibitor, P2, by linking a mitochondrial-specific cell-penetrating peptide to SP600125 (SP), a commercialized specific inhibitor of JNK. We found that P2 specifically inhibited mitochondrial JNK phosphorylation instead of nuclear JNK signaling. Further studies showed that P2 effectively rescued PD phenotypes both inâ vitro and inâ vivo, thus indicating that it is a potential therapeutic for PD.
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Enfermedad de Parkinson , Humanos , Enfermedad de Parkinson/tratamiento farmacológico , Enfermedad de Parkinson/metabolismo , Fosforilación , Sistema de Señalización de MAP Quinasas/fisiología , Proteínas Quinasas JNK Activadas por Mitógenos/metabolismo , Proteínas Quinasas JNK Activadas por Mitógenos/farmacología , Mitocondrias/metabolismoRESUMEN
Although lipids are not genetically encoded, they are fundamental building blocks of cell membranes and essential components of cell metabolites. Lipids regulate various biological processes, including energy storage, membrane trafficking, signal transduction, and protein secretion; therefore, their metabolic imbalances cause many diseases. Approximately 47â¯000 lipid species with diverse structures have been identified, but little is known about their crucial roles in cellular systems. Particularly the structural, metabolic, and signaling functions of lipids often arise from interactions with proteins. Lipids attach to proteins not only by covalent bonds but also through noncovalent interactions, which also influence protein functions and localization. Therefore, it is important to explore this lipid-protein "interactome" to understand its roles in health and disease, which may further provide insight for medicinal development. However, lipid structures are generally quite complicated, rendering the systematic characterization of lipid-protein interactions much more challenging.Chemoproteomics is a well-known chemical biology platform in which small-molecule chemical probes are utilized in combination with high-resolution, quantitative mass spectrometry to study protein-ligand interactions in living cells or organisms, and it has recently been applied to the study of protein-lipid interactions as well. The study of these complicated interactions has been advanced by the development of bifunctional lipid probes, which not only enable probes to form covalent cross-links with lipid-interacting proteins under UV irradiation, but are also capable of enriching these proteins through bioorthogonal reactions.In this Account, we will discuss recent developments in bifunctional lipid-derived, affinity-based probes (AfBP)s that have been developed to investigate lipid-protein interactions in live cell systems. First, we will give a brief introduction of fundamental techniques based on AfBPs which are related to lipid research. Then, we will focus on three aspects, including probes developed on the basis of lipidation, lipid-derived probes with different modification positions (e.g., hydrophobic or hydrophilic parts of a lipid), and, finally, in situ biosynthesis of probes through intrinsic metabolic pathways by using chemically modified building blocks. We will present some case studies to describe these probes' design principles and cellular applications. At the end, we will also highlight key limitations of current approaches so as to provide inspirations for future improvement. The lipid probes that have been constructed are only the tip of the iceberg, and there are still plenty of lipid species that have yet to be explored. We anticipate that AfBP-based chemoproteomics and its further advancement will pave the way for a deep understanding of lipid-protein interactions in the future.
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Proteínas , Transducción de Señal , Proteínas/química , Membrana Celular/metabolismo , Lípidos/químicaRESUMEN
Mitochondrial DNA (mtDNA) plays an essential role in maintaining normal cellular activities. Its heteroplasmic mutations are known to cause various genetic diseases. Current genetic engineering strategies, such as those based on RNA interference (RNAi) and antisense technology, are difficult to genetically alter mtDNA, however, due to the inability of highly negatively charged oligonucleotides to translocate across the double-membrane mitochondria. We report herein a universal mitochondria-targeted gene-delivery approach by using cell-penetrating poly(disulfide)s (CPDs). Novel CPD-based mitochondrial transporters, named Mito-CPDs, were synthesized by using triphenylphosphonium (TPP)-fused propagating monomers containing either disulfide or diselenide backbones. Upon spontaneous complex formation with an oligonucleotide (single- or double-stranded), the resulting nanoscale Mito-CPD@Oligo exhibited excellent properties in common biological media. While the intracellular gene-delivery efficiency of these Mito-CPDs was comparable to that of commercial transfection agents, their unique mitochondria-localized properties enabled effective release of the loaded cargo inside these organelles. Subsequent mitochondrial delivery of siRNA and antisense oligonucleotides against suitable mtDNA-encoded proteins showed successful down-regulation of target protein expression, leading to profound effects on mitochondrial functions. Mito-CPDs thus provide a useful tool for future investigations of mitochondrial biology and treatment of mitochondria-related diseases.
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ADN Mitocondrial , Mitocondrias , Mitocondrias/genética , Mitocondrias/metabolismo , ADN Mitocondrial/genética , Transfección , Técnicas de Transferencia de Gen , Silenciador del GenRESUMEN
Inducing cell ferroptosis by inactivating glutathione peroxidase 4 (GPX4) is a popular cancer treatment strategy. However, only few GPX4 inhibitors have been developed to date. PROteolysis Targeting Chimera (PROTAC) is a promising approach to provide new opportunities to overcome limitations of traditional therapeutics. Herein, a PROTAC-like activity-based probe PD-Q2 was first assembled using Ugi reaction, consisting of a known GPX4 inhibitor ML-162 homolog to the E3 ligase cereblon ligand-pomalidomide. Pull-down and immunoblotting analysis revealed that GPX4 was a covalent target of PD-Q2, but the degradation efficiency was weak. Therefore, a series of degraders was further synthesized by varying the linkers of heterofunctional PROTACs. Among these degraders, PD-4 and PD-P2 were found to promote effective GPX4 degradation via the ubiquitin-proteasome system and cause lipid ROS accumulation. PD-4 and PD-P2 showed potent inhibitory of colony formation and cell growth. Furthermore, we found that with pomalidomide, the degraders exhibit a high fluorescent signal that is mostly localized in the lysosome, which may affect the effectiveness of anti-cell proliferation. Overall, we provide GPX4 degraders for further exploring therapeutic potential of regulating ferroptosis.
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Quimera Dirigida a la Proteólisis , Ciclo Celular , Proliferación Celular , Fosfolípido Hidroperóxido Glutatión Peroxidasa , ProteolisisRESUMEN
Lysosome-targeting chimeras (LYTACs) have emerged as a promising technique to extend the scope of targeted protein degradation to extracellular proteins, e.g., secreted proteins and membrane-anchored proteins. However, up to now, only a small number of lysosomal targeting receptors (LTRs), such as cation-independent mannose 6-phosphate receptor (CI-M6PR) and asialoglycoprotein receptor (ASGPR), were reported to build LYTACs for degradation of extracellular proteins. Therefore, it is important to explore more functionalized ligands for the relevant LTRs to expand the LYTAC framework. Herein, we demonstrate a new LTR ligand-glucagon like peptide 1 (GLP-1) based targeted degradation platform, termed GLP-1 receptor-targeting chimeras (GLP-1-LYTAC). GLP-1-LYTACs are formed by conjugating GLP-1 with targeted binder (such as antibody) through Click Chemistry, showing efficiently lysosomal degradation of both extracellular proteins (GFP and Neutravidin) as well as cell membrane proteins (EGFR and PD-L1). We believe that this novel GLP-1-LYTAC will open up a new dimension for targeted protein breakdown.
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Péptido 1 Similar al Glucagón , ProteolisisRESUMEN
Chiral sulfones are recurrent motifs in pharmaceuticals and bioactive molecules. Although chemical methods have been developed to afford α- or ß- chiral sulfones, these protocols rely heavily on the pre-synthesis of structurally complicated starting materials and chiral metal complexes. Herein, we described a photoenzymatic approach for the radical-mediated stereoselective hydrosulfonylation. Engineered variants of ene reductases provide efficient biocatalysts for this transformation, enabling to achieve a series of ß-chiral sulfonyl compounds with high yields (up to 92 %) and excellent e.r. values (up to 99 : 1).
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Nitroreductase (NTR), one of the flavin-dependent enzymes and an upregulated enzyme under tumor hypoxia, has been studied for decades. Many fluorescent probes were developed to detect NTR activity; however, these probes tend to diffuse away from their reaction site (NTR) inevitably, leading to inappropriate sample fixation, lower accuracy of NTR localization, and weaker signal-to-noise ratio. Herein, we present the design, synthesis, in vitro evaluation, and biological applications of an NTR-activatable fluorogenic and labeling probe FY. By integrating with quinone methide (QM) proximity-based protein labeling, the additional fluoromethyl group on FY serves as a potential origin of QM. Compared with conventional fluorescent probes, this new NTR probe not only offers mitochondrial localizable and fluorogenic response but also achieves permanent retention on the site of activation with an enhanced spatial resolution to improve the detection sensitivity even after cell fixation. We believe our work could offer an expandable synthetic approach to develop these permanent labeling and imaging fluorescence probes for deciphering complex biological events.
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Colorantes Fluorescentes , Nitrorreductasas , Microscopía Fluorescente , Mitocondrias/metabolismo , Nitrorreductasas/metabolismo , Hipoxia TumoralRESUMEN
The mitochondrion is the core site of cell signaling, energy metabolism and biosynthesis. Here, taking advantage of activity-based probes, we synthesized two photocontrollable probes (YGH-1 and YGH-2), composed of a mitochondrial localization moiety "triphenylphosphonium", a photo-triggered group to achieve spatially and temporally controlled protein capture, and an alkyne group to enrich the labeled protein. Proteomic validation was further carried out to facilitate identification of the mitochondrial proteome in HeLa cells. The results show that half of the identified protein hits (â¼300) labeled by YGH-1 and YGH-2 belong to mitochondria, and are mostly localized in the mitochondrial matrix and inner mitochondrial membrane. Our results provide a new tool for spatial and temporal analysis of subcellular proteomes.
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Mitocondrias , Proteómica , Células HeLa , Humanos , Mitocondrias/metabolismo , Proteínas Mitocondriales/metabolismo , Proteoma/metabolismo , Proteómica/métodosRESUMEN
Atrazine (ATR) is a herbicide used widely worldwide. Because of its prolonged persistence in the environment and accumulation in the body, ATR exposure is a potential threat to human health. Our previous study showed that subacute exposure to ATR suppresses cellular immune function in mice. In this study, the effects of long-term exposure to ATR on rat immunological system function were measured. Four-week-old female Sprague-Dawley (SD) rats were treated with 0.4 µmol/L, 2 µmol/L and 10 µmol/L ATR for 24 weeks. The results showed that the spleen index increased, white blood cells decreased, and monocytes and eosinophils increased. No obvious changes were detected in the numbers of neutrophils and lymphocytes. Th1, Th2, and Th17 cells decreased significantly, while Treg cells increased after long-term ATR exposure. Moreover, serum levels of cytokines, including TNF-α, INF-γ, IL-6, and IL-12, decreased, while IL-1, IL-4, and IL-5 increased. Degenerative changes and cell apoptosis were found in the spleen; Caspase-3 and Caspase-9 were upregulated, and Bcl-2 was downregulated. These results suggested that long-term ATR exposure may inhibit immune system function.
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Apoptosis/efectos de los fármacos , Atrazina/toxicidad , Herbicidas/toxicidad , Bazo/efectos de los fármacos , Animales , Citocinas/genética , Citocinas/metabolismo , Femenino , Regulación de la Expresión Génica/efectos de los fármacos , Ratones , Ratas , Ratas Sprague-Dawley , Transducción de Señal/efectos de los fármacos , Bazo/citología , Linfocitos T Colaboradores-InductoresRESUMEN
Protein disulfide isomerase (PDI), a chaperone protein mostly in endoplasmic reticulum, catalyzes disulfide bond breakage, formation, and rearrangement to promote protein folding. PDI is regarded as a new target for treatment of several disorders. Here, based on the combination principle, we report a new PDI reversible modulator 16F16A-NO by replacing the reactive group in a known PDI inhibitor 16F16 with nitric oxide (NO) donor. Using molecular docking experiment, 16F16A-NO could embed into the active cavity of PDI. From newly developed fluorescent assay, 16F16A-NO showed rapid NO release. Furthermore, it is capable to moderately inhibit activity of PDI and S-nitrosylate the protein, indicating by insulin aggregation assay and biotin-switch technique. Finally, it displayed a dose-dependent antiproliferative activity against SH-SY5Y and HeLa tumor cells. Our designed hybrid compound 16F16A-NO showed a reasonable activity and might offer a promising avenue to develop novel PDI inhibitors for disease treatments.
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Diseño de Fármacos , Inhibidores Enzimáticos/síntesis química , Donantes de Óxido Nítrico/química , Óxido Nítrico/metabolismo , Proteína Disulfuro Isomerasas/antagonistas & inhibidores , Sitios de Unión , Dominio Catalítico , Línea Celular Tumoral , Proliferación Celular/efectos de los fármacos , Supervivencia Celular/efectos de los fármacos , Inhibidores Enzimáticos/metabolismo , Inhibidores Enzimáticos/farmacología , Humanos , Simulación del Acoplamiento Molecular , Donantes de Óxido Nítrico/metabolismo , Donantes de Óxido Nítrico/farmacología , Proteína Disulfuro Isomerasas/metabolismoRESUMEN
Activin A, a multifunctional cytokine of transforming growth factor-ß (TGF-ß) superfamily, can be produced by the diverse immune cells. NK cells in peripheral blood are one of the major immune cells applied to cancer therapy in recent years. However, whether activin A can be produced by natural killer (NK) cells and be involved in regulation of peripheral blood NK cells activities of mouse are not well characterized. Here, we found that activin type IIA and IIB receptors and signaling molecules Smad2, 3 were expressed in peripheral blood NK cells of mouse by flow cytometry and RT-PCR. The cultured blood NK cells of mouse not only produced activin ßA chain protein by intracellular cytokine staining, but also secreted mature activin A protein by enzyme-linked immunosorbent assay (ELISA), and the production was promoted by IL-2. In addition, IL-2 as a positive control obviously promoted IFNγ production of mouse blood NK cells in vitro. However, activin A suppressed IFNγ production, but enhanced IL-2 synthesis and did not alter IL-10 production. Moreover, we found that activin A significantly suppressed the ability of NK cells to lyse target cells. These data revealed that blood NK cells of mouse were not only the target cells in response to activin A, but also the source of activin A, suggesting that activin A may play an important role in regulation of NK cells activities of mouse in an autocrine / paracrine manner.
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Activinas/farmacología , Comunicación Autocrina , Células Asesinas Naturales/metabolismo , Comunicación Paracrina , Receptores de Activinas Tipo II/sangre , Receptores de Activinas Tipo II/genética , Receptores de Activinas Tipo II/metabolismo , Animales , Comunicación Autocrina/efectos de los fármacos , Muerte Celular/efectos de los fármacos , Proliferación Celular/efectos de los fármacos , Folistatina/farmacología , Subunidades beta de Inhibinas/sangre , Subunidades beta de Inhibinas/genética , Subunidades beta de Inhibinas/metabolismo , Interferón gamma/biosíntesis , Interleucina-10/biosíntesis , Interleucina-2/biosíntesis , Células Asesinas Naturales/efectos de los fármacos , Masculino , Ratones Endogámicos BALB C , Comunicación Paracrina/efectos de los fármacos , ARN Mensajero/genética , ARN Mensajero/metabolismo , Proteínas Smad/sangre , Proteínas Smad/genética , Proteínas Smad/metabolismoRESUMEN
The mitochondrion is one of the most important organelles in the eukaryotic cell. Characterization of the mitochondrial proteome is a prerequisite for understanding its cellular functions at the molecular level. Here we report a proteomics method based on mitochondrion-targeting groups and click chemistry. In our strategy, three different mitochondrion-targeting moieties were each augmented with a clickable handle and a cysteine-reactive group. Fluorescence-based bioimaging and fractionation experiments clearly showed that most signals arising from the labels were localized in the mitochondria of cells, as a result of covalent attachment between probe and target proteins. The three probes had distinct profiling characteristics. Furthermore, we successfully identified more than two hundred mitochondrial proteins. The results showed that different mitochondrion-targeting groups targeted distinct proteins with partial overlap. Most of the labeled proteins were localized in the mitochondrial matrix and inner mitochondrial membrane. Our results provide a tool for chemoproteomic analysis of mitochondrion-related proteins.
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Mitocondrias/química , Proteínas Mitocondriales/análisis , Sondas Moleculares/química , Proteoma/análisis , Alquinos/síntesis química , Alquinos/química , Cromatografía Liquida , Química Clic , Colorantes Fluorescentes/química , Células HeLa , Humanos , Proteínas Mitocondriales/química , Sondas Moleculares/síntesis química , Oligopéptidos/síntesis química , Oligopéptidos/química , Proteoma/química , Proteómica/métodos , Rodaminas/química , Espectrometría de Masas en TándemRESUMEN
Monoamine oxidase (MAO) is a membrane-bound mitochondrial enzyme that plays an important role by catalyzing oxidative deamination to maintain the homeostasis of neurotransmitters and other biogenic amines in living systems. MAO activity is critical for the brain and central nervous system. Its dysfunction is closely related with many neurological and psychiatric disorders. Fluorescent probes provide a useful approach to accurately detect MAO activity and assist to better elucidate their biological functions. Herein, in this Minireview, we summarize the recent advances in reaction based MAO type fluorescent probes and their imaging applications in living systems.
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Colorantes Fluorescentes/química , Monoaminooxidasa/análisis , Animales , Línea Celular Tumoral , Humanos , Estructura Molecular , Oxidación-ReducciónRESUMEN
"Minimalist" small molecule tagging (MSMT) is a promising approach that easily converts bioactive compounds into affinity-based probes (AfBPs) for proteomic studies. In this work, seven bioactive compounds targeting diversified protein classes were installed with "minimalist" linkers through common reactions to generate the corresponding AfBPs. These probes were evaluated for cell-based protein profiling and target validation. Among them, the entinostat-derived probe EN and the camptothecin-derived probe CA were further utilized in cellular imaging and SILAC-based large-scale target identification. Our extensive studies suggest that the "minimalist" small molecule tagging approach could be expanded to different classes of bioactive compounds for modification into AfBPs as a dual functional tool for both proteomics and cellular imaging.
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Camptotecina/análisis , Camptotecina/química , Proteínas de Neoplasias/análisis , Imagen Óptica , Proteómica , Bibliotecas de Moléculas Pequeñas/análisis , Bibliotecas de Moléculas Pequeñas/química , Camptotecina/síntesis química , Células Hep G2 , Humanos , Proteínas Recombinantes/análisis , Bibliotecas de Moléculas Pequeñas/síntesis químicaRESUMEN
In this study, a single fluorescent probe (DPFP) containing a 1,8-naphthalimide dye and a homoallylamino group for imaging pH and formaldehyde (FA) has been developed that exhibits significant blue fluorescence (λem at 455 nm) under acidic pH conditions (pH < 7.0) and green fluorescence (λem at 555 nm) in the presence of FA, respectively. Furthermore, probe DPFP was successfully applied to image acidic lysosomes and exogenous or endogenous FA in living HeLa cells.
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We report herein the first example of Cu(II)-catalyzed site selective azidation of aromatic amines via C-H functionalization in aqueous media. In our strategy, a mild reagent was utilized. H2O2 served as the oxidant, and sodium azide was used as the azidation reagent. This method could also be applied to late-stage functionalization of drugs that possess an aromatic amine moiety. In addition, we found that bromination or iodination on the ortho-position of aromatic amines could occur efficiently using this catalytic system.