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Amyloid β (Aβ) peptides accumulating in the brain are proposed to trigger Alzheimers disease (AD). However, molecular cascades underlying their toxicity are poorly defined. Here, we explored a novel hypothesis for Aβ42 toxicity that arises from its proven affinity for γ-secretases. We hypothesized that the reported increases in Aβ42, particularly in the endolysosomal compartment, promote the establishment of a product feedback inhibitory mechanism on γ-secretases, and thereby impair downstream signaling events. We conducted kinetic analyses of γ-secretase activity in cell-free systems in the presence of Aβ, as well as cell-based and ex vivo assays in neuronal cell lines, neurons, and brain synaptosomes to assess the impact of Aβ on γ-secretases. We show that human Aβ42 peptides, but neither murine Aβ42 nor human Aβ17-42 (p3), inhibit γ-secretases and trigger accumulation of unprocessed substrates in neurons, including C-terminal fragments (CTFs) of APP, p75, and pan-cadherin. Moreover, Aβ42 treatment dysregulated cellular homeostasis, as shown by the induction of p75-dependent neuronal death in two distinct cellular systems. Our findings raise the possibility that pathological elevations in Aβ42 contribute to cellular toxicity via the γ-secretase inhibition, and provide a novel conceptual framework to address Aβ toxicity in the context of γ-secretase-dependent homeostatic signaling.

PIP3-dependent Rac exchanger 1 (P-Rex1) is abundantly expressed in neutrophils and plays central roles in chemotaxis and cancer metastasis by serving as a guanine-nucleotide exchange factor (GEF) for Rac. The enzyme is synergistically activated by PIP3 and heterotrimeric Gβγ subunits, but mechanistic details remain poorly understood. While investigating the regulation of P-Rex1 by PIP3, we discovered that Ins(1,3,4,5)P4 (IP4) inhibits P-Rex1 activity and induces large decreases in backbone dynamics in diverse regions of the protein. Cryo-electron microscopy analysis of the P-Rex1·IP4 complex revealed a conformation wherein the pleckstrin homology (PH) domain occludes the active site of the Dbl homology (DH) domain. This configuration is stabilized by interactions between the first DEP domain (DEP1) and the DH domain and between the PH domain and a 4-helix bundle (4HB) subdomain that extends from the C-terminal domain of P-Rex1. Disruption of the DH-DEP1 interface in a DH/PH-DEP1 fragment enhanced activity and led to a more extended conformation in solution, whereas mutations that constrain the occluded conformation led to decreased GEF activity. Variants of full-length P-Rex1 in which the DH-DEP1 and PH-4HB interfaces were disturbed exhibited enhanced activity during chemokine-induced cell migration, confirming that the observed structure represents the autoinhibited state in living cells. Interactions with PIP3-containing liposomes led to disruption of these interfaces and increased dynamics protein-wide. Our results further suggest that inositol phosphates such as IP4 help to inhibit basal P-Rex1 activity in neutrophils, similar to their inhibitory effects on phosphatidylinositol-3-kinase.

Chitin is an abundant biopolymer and pathogen-associated molecular pattern that stimulates a host innate immune response. Mammals express chitin-binding and chitin-degrading proteins to remove chitin from the body. One of these proteins, Acidic Mammalian Chitinase (AMCase), is an enzyme known for its ability to function under acidic conditions in the stomach but is also active in tissues with more neutral pHs, such as the lung. Here, we used a combination of biochemical, structural, and computational modeling approaches to examine how the mouse homolog (mAMCase) can act in both acidic and neutral environments. We measured kinetic properties of mAMCase activity across a broad pH range, quantifying its unusual dual activity optima at pH 2 and 7. We also solved high-resolution crystal structures of mAMCase in complex with oligomeric GlcNAcn, the building block of chitin, where we identified extensive conformational ligand heterogeneity. Leveraging these data, we conducted molecular dynamics simulations that suggest how a key catalytic residue could be protonated via distinct mechanisms in each of the two environmental pH ranges. These results integrate structural, biochemical, and computational approaches to deliver a more complete understanding of the catalytic mechanism governing mAMCase activity at different pH. Engineering proteins with tunable pH optima may provide new opportunities to develop improved enzyme variants, including AMCase, for therapeutic purposes in chitin degradation.

Photolysis of aryl azides offers a versatile approach to achieve more sophisticated functionalization, for instance in the field of chemical biology. In this study, a photoactivatable aryl azide named Pcp‐Az is presented that forms three distinct emissive molecules after irradiation. Computational studies unveiled that the photolysis of Pcp‐Az in aqueous medium undergoes different reaction channels, leading to the three mentioned distinct products. When the photoreaction is performed using the supramolecular host cucurbit[8]uril(CB8) for Pcp‐Az, the reaction is found to be tuned and accelerated. Finally, the potential application of the photoproducts are showcased in bioimaging, and also the time‐dependent photoactivating imaging. [ABSTRACT FROM AUTHOR]

Photolysis of aryl azides is a convenient method to approach more functionalized systems in chemical biology. Here, we present a set of photoactivatable aryl azides that undergo controlled reaction pathways within the cucurbit[7]uril (CB7) cavity upon photolysis. The fluorescence turn-on process is utilized for bioimaging. [ABSTRACT FROM AUTHOR]

1,2,3-triazoles have emerged as important structural motifs in chemical biology, attracting increasing focus in recent years because of their wide range of uses. These compounds can be efficiently synthesized using click reactions. Its versatility makes it valuable in drug discovery and materials science. Significant advancements have been made in recent years in the process of making 1,2,3-triazoles, reflecting the growing curiosity and investment in the area of research. The catalytic performance of transition metals Cu, Ir, Rh, Ru, Ni, Pd, Au, Ag, and Zn, which were used as ligands and salts in the azide–alkyne cycloaddition method of 1,2,3-triazole synthesis, has been covered in this review. Cu-complexes and salts were found to be more effective for selective synthesis among all transition metals. Furthermore, it is determined that some azide–alkyne reactions are entirely catalytic in nature and cannot be carried out as such by switching transition metals. [ABSTRACT FROM AUTHOR]

Protein homeostasis in bacteria is regulated by proteases such as the tetradecameric caseinolytic protease P (ClpP). Although substrates of ClpP have been successfully deciphered in genetically engineered cells, methods which directly trap processed proteins within native cells remain elusive. Here, we introduce an in situ trapping strategy which utilizes trifunctional probes that bind to the active site serine of ClpP and capture adjacent substrates with an attached photocrosslinking moiety. After enrichment using an alkyne handle, substrate deconvolution by mass spectrometry (MS) is performed. We show that our two traps bind substoichiometrically to ClpP, retain protease activity, exhibit unprecedented selectivity for Staphylococcus aureus ClpP in living cells and capture numerous known and novel substrates. The exemplary validation of trapped hits using a targeted proteomics approach confirmed the fidelity of this technology. In conclusion, we provide a novel chemical platform suited for the discovery of serine protease substrates beyond genetic engineering. [ABSTRACT FROM AUTHOR]

Deuterium-labeled molecules play a crucial role in numerous areas, from medicinal chemistry to chemical biology, providing a unique opportunity to improve ADMET properties and study the biological fate of bioactive molecules. Herein, we present an electromigratory reductive deuteration of terminal alkynes to access a diverse array of enamides with more than 3 deuteriums incorporated per molecule, using CD3CN as a deuterium source. The reaction proceeds under mild neutral conditions, does not require precious transition metals, and shows broad substrate scope with excellent E-selectivity. We envision that this on-demand high deuterium incorporation will provide considerable opportunities in therapeutics and biological research. [ABSTRACT FROM AUTHOR]

Reversible covalent electrophiles with the advantages of both reversible and covalent interactions receive much attention in the fields of chemical biology and medicinal chemistry. Here, we report two electron-deficient olefins activated by amide and ester, amide-substituted acrylamide and methyl ester-substituted acrylamide, targeting thiols in a reversible covalent manner. [ABSTRACT FROM AUTHOR]

Peptide nucleic acids (PNAs) combine the programmability of native nucleic acids with the robustness and ease of synthesis of a peptide backbone. These designer biomolecules have demonstrated tremendous utility across a broad range of applications, from the formation of bespoke biosupramolecular architectures to biosensing and gene regulation. Herein, we explore some of the key developments in the application of PNA in chemical biology and biotechnology in the last 5 years and present anticipated key areas of future development. [ABSTRACT FROM AUTHOR]

Interactions between ADP-ribose (ADPr) modifications and their readers play an essential role in various biological processes, and the toolbox for probing these interactions is expanding. Many methods for the discovery of ADPr readers rely on the activity of poly-ADPr (PAR) polymerase 1 (PARP1) to enzymatically synthesize PAR. Recent advances using (chemo)enzymatic methods include the incorporation of functional groups such as a photo-activatable azido group and/or the incorporation of a biotin-handle for affinity purifications. Chemically synthesized probes with a well-defined structure enable, for the first time, identification of mono-ADPr (MAR) and linear PAR-specific readers. An in-depth knowledge on ADPr modifications and their readers will aid in the discovery of novel therapeutic targets for multiple ADPr-associated pathologies. ADP-ribosylation regulates numerous fundamental cellular processes in health and disease. However, the limited availability of suitable tools and methods prevents the identification and characterization of certain components of the ADP-ribosylation signaling network and, consequently, efficient utilization of their biomedical potential. Identification of ADP-ribose (ADPr) readers has been particularly impeded by challenges associated with the development of ADPr-based enrichment probes. These difficulties were finally overcome in several recent studies describing various approaches to identifying ADPr readers in an unbiased, proteome-wide manner. In this review we discuss these different strategies and their limitations, benefits and drawbacks, and summarize how these technologies contribute to a dissection of ADP-ribosylation signaling networks. We also address unmet technological needs and future directions to investigate interactions with ADPr linkages. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Journal of Inorganic Analytical Chemistry / Zhongguo Wuji Fenxi Huaxue is the property of Beijing Research Institute of Mining & Metallurgy Technology Group and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

High‐resolution nuclear magnetic resonance (NMR) spectroscopy represents a key methodology for studying biomolecules and their interplay with other molecules. Recent developments in labeling strategies have made it possible to incorporate fluorine into proteins and peptides reliably, with manageable efforts and, importantly, in a highly site‐specific manner. Paired with its excellent NMR spectroscopic properties and absence in most biological systems, fluorine has enabled scientists to investigate a rather wide range of scientific objectives, including protein folding, protein dynamics and drug discovery. Furthermore, NMR spectroscopic experiments can be conducted in complex environments, such as cell lysate or directly inside living cells. This review presents selected studies demonstrating how 19F NMR spectroscopic approaches enable to contribute to the understanding of biomolecular processes. Thereby the focus has been set to labeling strategies available and specific NMR experiments performed to answer the underlying scientific objective. [ABSTRACT FROM AUTHOR]

This feature article delves into the realm of α- L -threose nucleic acid (TNA), an artificial nucleic acid analog characterized by a backbone comprising an unconventional four-carbon sugar, α- L -threose, with phosphodiester linkages connecting at the 2′ and 3′ vicinal positions of the sugar ring. Within this article, we encapsulate the potential, progress, current state of the art, and persisting challenges within TNA research. Kicking off with a historical overview of xeno nucleic acids (XNAs), the discussion transitions to the compelling attributes and structure–property relationships of TNAs as advanced tools when contrasted with natural nucleic acids. Noteworthy aspects such as their advantageous spatial arrangements of functional groups around the sugar ring, stable Watson–Crick base pairing, high binding affinity, biostability, biocompatibility, and in vivo bio-safety are highlighted. Moreover, the narrative unfolds the latest advancements in chemical and biological methodologies for TNA synthesis, spanning from monomer and oligomer synthesis to polymerization, alongside cutting-edge developments in enzyme engineering aimed at bolstering large-scale TNA synthesis for in vitro selection initiatives. The article sheds light on the evolution of TNA aptamers over time, expounding on the tools and selection techniques engineered to unearth superior binding aptamers and TNA catalysts. Furthermore, the article accentuates the recent applications of TNAs across diverse domains such as molecular detection, immunotherapy, gene therapy, synthetic biology, and molecular computing. In conclusion, we summarize the key aspects of recent TNA research, address persisting gaps and challenges, and provide crucial insights and future perspectives in the dynamic domain of TNA research. [ABSTRACT FROM AUTHOR]

Synthetic molecular photoswitches have taken center stage as high‐precision tools to introduce light‐responsiveness at the smallest scales. Today they are found in all areas of applied chemistry, covering materials research, chemical biology, catalysis, or nanotechnology. For a next step of applicability truly orthogonal photoswitching is highly desirable but to date such independent addressability of different photoswitches remains highly challenging. Herein we present the first example of all‐visible, all‐light responsive, and path‐ independent orthogonal photoswitching. By combining two recently developed indigoid photoswitches ‐ peri‐anthracenethioindigo and a rhodanine‐based chromophore ‐ a four‐state system is established and each state can be accessed in high yields completely independently and also with visible light irradiation only. The four states give rise to four different colors, which can be transferred to a solid polymer matrix to yield a versatile multi‐state photochromic material. Further, combination with a fluorescent dye as a third component is possible, demonstrating the applicability of this orthogonal photoswitching system in all‐photonic molecular logic behavior and information processing. [ABSTRACT FROM AUTHOR]

Immune checkpoint blockade targeting the CD47/SIRPα axis represents an alluring avenue for cancer immunotherapy. However, the compromised efficacy and safety concerns in vivo of conventional anti‐CD47 antibodies impede their wide clinical applications. Here we introduced a single type of high‐mannose glycans into the nanobody against CD47 (HM‐nCD47) and subsequently displayed HM‐nCD47 on cellular vesicles (CVs) for enhanced cancer immunotherapy. In this platform, the CVs significantly improved the circulation time of HM‐nCD47‐CVs, the nCD47 enabled the blockade of the CD47/SIRPα axis, and the HM enhanced recognition of mannose‐binding lectin, all synergistically activating the macrophage‐mediated antitumor immunity. In both subcutaneous and metastatic murine tumor models, the HM‐nCD47‐CVs possessed significantly extended half‐lives and increased accumulation at the tumor site, resulting in a remarkable macrophage‐dependent inhibition of tumor growth, a transcriptomic remodeling of the immune response, and an increase in survival time. By integrating the chemical biology toolbox with cell membrane nanotechnology, the HM‐nCD47‐CVs represent a new immunotherapeutic platform for cancer and other diseases. [ABSTRACT FROM AUTHOR]

The intricate nature of carbohydrate structures has prompted the scientific community to seek efficient protocols for their manipulation. Lengthy synthetic pathways, often necessary to achieve complex sugar structures, pose challenges not only in terms of time and cost but also regarding environmental sustainability. Consequently, domino transformations serve as valuable tools in streamlining drug discovery processes. Sequential procedures involving fewer steps and minimal isolation/purification steps are particularly appealing to organic chemists in the field of carbohydrate chemistry. This review highlights several examples of domino transformations applied to carbohydrates, aiming to summarize their chemical potential in delivering sugar‐based compounds with significant applications in the generation of new chemical scaffolds for drug discovery and chemical biology. [ABSTRACT FROM AUTHOR]

Ubiquitylation of histone H2A at lysines 13 and 15 by the E3 ligase RNF168 plays a key role in orchestrating DNA double‐strand break (DSB) repair, which is often deregulated in cancer. RNF168 activity is triggered by DSB signaling cascades, reportedly through K63‐linked poly‐ubiquitylation of linker histone H1. However, direct experimental evidence of this mechanism has been elusive, primarily due to the lack of methods to specifically poly‐ubiquitylate H1. Here, we developed a versatile click chemistry approach to covalently link multiple proteins in a site‐specific, controlled, and stepwise manner. Applying this method, we synthesized H1 constructs bearing triazole‐linked di‐ubiquitin on four DNA repair‐associated ubiquitylation hotspots (H1KxUb2, at K17, 46, 64 and 96). Integrated into nucleosome arrays, the H1KxUb2 variants stimulated H2A ubiquitylation by RNF168 in a position‐dependent manner, with H1K17Ub2 showing the strongest RNF168 activation effect. Moreover, we show that di‐ubiquitin binding is the driving force underlying RNF168 recruitment, introducing H1K17Ub2 into living U‐2 OS cells. Together, our results support the hypothesis of poly‐ubiquitylated H1 guiding RNF168 recruitment to DSB sites. Moreover, we demonstrate how the streamlined synthesis of H1KxUb2 variants enables mechanistic studies into RNF168 regulation, with potential implications for its inhibition in susceptible cancers. [ABSTRACT FROM AUTHOR]

Our study introduces a streamlined oxidative method for synthesizing 1,3‐diarylphenanthro[9,10‐c]thiophenes, and their subsequent oxidative cleavage to yield 9,10‐diaroylphenanthrenes. Harnessing an optimized aerobic photochemical transformation, we showcase broad substrate scope and tolerance to various photosensitive functional groups. Our mechanistic investigations unveil the pivotal role of singlet oxygen, providing intriguing insights into the reaction pathway. The synthesized 9,10‐diaroylphenanthrenes serve as versatile building blocks for nitrogen‐containing heterocycles, dibenzoannulated phthalazines, that are promising compounds with diverse functionalities. Offering mild conditions, and broad applicability, our synthetic strategy is useful for organic synthesis and chemical biology exploration. [ABSTRACT FROM AUTHOR]

Site‐selective chemical modifications of proteins have emerged as a potent technology in chemical biology, materials science, and medicine, facilitating precise manipulation of proteins with tailored functionalities for basic biology research and developing innovative therapeutics. Compared to traditional recombinant expression methods, one of the prominent advantages of chemical protein modification lies in its capacity to decorate proteins with a wide range of functional moieties, including non‐genetically encoded ones, enabling the generation of novel protein conjugates with enhanced or previously unexplored properties. Among these, approaches for dual or multiple modifications of proteins are increasingly garnering attention, as it has been found that single modification of proteins is inadequate to meet current demands. Therefore, in light of the rapid developments in this field, this review provides a timely and comprehensive overview of the latest advancements in chemical and biological approaches for dual functionalization of proteins. It further discusses their advantages, limitations, and potential future directions in this relatively nascent area. [ABSTRACT FROM AUTHOR]

Proteins, which are ubiquitous in cells and critical to almost all cellular functions, are indispensable for life. Fluorescence imaging of proteins is key to understanding their functions within their native milieu, as it provides insights into protein localization, dynamics, and trafficking in living systems. Consequently, the selective labeling of target proteins with fluorophores has emerged as a highly active research area, encompassing bioorganic chemistry, chemical biology, and cell biology. Various methods for selectively labeling proteins with fluorophores in cells and tissues have been established and are continually being developed to visualize and characterize proteins. This review highlights research findings reported since 2018, with a focus on the selective labeling of cellular proteins with small organic fluorophores and their biological applications in studying protein-associated biological events. We also discuss the strengths and weaknesses of each labeling approach for their utility in living systems. [ABSTRACT FROM AUTHOR]

This paper presents the construction of the "Chemical Biology Experiment", a core course within the Chemistry "101 Program". Highlighting the interdisciplinary characteristics of chemical biology, the critical importance of laboratory courses in advancing interdisciplinary research, and the overarching goals of the Chemistry "101 Program", this paper systematically summarizes and introduces the course development philosophy, the textbook content, and the features of its compilation. [ABSTRACT FROM AUTHOR]

Chemical biology is one of the 12 core courses developed under the "101 Plan" for chemistry. As an emerging interdisciplinary field that explores the chemical basis and molecular foundations of life processes, chemical biology encompasses a broad range of topics and extensive knowledge. With ongoing advancements in the field, establishing a systematic curriculum that addresses the diverse needs of students from various disciplines presents a significant challenge for textbook design and construction. To address this, the authors have investigated and compared the content and curriculum design of different chemical biology textbooks, summarized the key modules and knowledge areas, and developed a teaching framework based on three main aspects: the molecular basis of chemical biology, core technologies, and applications. The textbook aims to showcase innovative features in knowledge integration, content depth, and practical orientation. By aligning with the development of interdisciplinary subjects and national strategic needs, the textbook seeks to provide a cross-disciplinary integration of chemistry, biology, and medicine, offering students a challenging and insightful learning experience. [ABSTRACT FROM AUTHOR]

Interactions between plants and soil microbial communities that benefit plant growth and enhance nutrient acquisition are driven by the selective release of metabolites from plant roots, or root exudation. To investigate these plant-microbe interactions, we developed a photoaffinity probe based on sorgoleone (sorgoleone diazirine alkyne for photoaffinity labeling, SoDA-PAL), a hydrophobic secondary metabolite and allelochemical produced in Sorghum bicolor root exudates. We applied SoDA-PAL to the identification of sorgoleone-binding proteins in Acinetobacter pittii SO1, a potential plant growth-promoting microbe isolated from sorghum rhizosphere soil. Competitive photoaffinity labeling of A. pittii whole cell lysates with SoDA-PAL identified 137 statistically enriched proteins, including putative transporters, transcriptional regulators, and a subset of proteins with predicted enzymatic functions. We performed computational protein modeling and docking with sorgoleone to prioritize candidates for experimental validation and then confirmed binding of sorgoleone to four of these proteins in vitro: the a/ß fold hydrolase SrgB (OH685_09420), a fumarylacetoacetase (OH685_02300), a lysophospholipase (OH685_14215), and an unannotated hypothetical protein (OH685_18625). Our application of this specialized sorgoleone-based probe coupled with structural bioinformatics streamlines the identification of microbial proteins involved in metabolite recognition, metabolism, and toxicity, widening our understanding of the range of cellular pathways that can be affected by a plant secondary metabolite. IMPORTANCE Here, we demonstrate that a photoaffinity-based chemical probe modeled after sorgoleone, an important secondary metabolite released by sorghum roots, can be used to identify microbial proteins that directly interact with sorgoleone. We applied this probe to the sorghum-associated bacterium Acinetobacter pittii and showed that probe labeling is dose-dependent and sensitive to competition with purified sorgoleone. Coupling the probe with proteomics and computational analysis facilitated the identification of putative sorgoleone binders, including a protein implicated in a conserved pathway essential for sorgoleone catabolism. We anticipate that discoveries seeded by this workflow will expand our understanding of the molecular mechanisms by which specific metabolites in root exudates shape the sorghum rhizosphere microbiome. [ABSTRACT FROM AUTHOR]

Photoregulation of biomolecules has become crucial tools in chemical biology, because light enables access under mild conditions and with delicate spatiotemporal control. The control of enzyme activity in a reversible way is a challenge. To achieve it, a facile approach is to use photoswitchable inhibitors. This review highlights recent progress in photoswitchable inhibitors based on azobenzenes units. The progress suggests that the incorporation of an azobenzene unit to a known inhibitor is an effective method for preparing a photoswitchable inhibitor, and with these photoswitchable inhibitors, the activity of enzymes can be regulated by optical control, which is valuable in both basic science and therapeutic applications. [ABSTRACT FROM AUTHOR]

In recent years, improving the pharmaceutical properties of drug delivery for anti‐cancer treatment has become increasingly important. This is necessary to address challenges related to absorption, distribution, and stability. One potential approach solution is to attach the drug to a carrier system, such as functional noble nanomaterials, in order to improve the control of drug release and stability. Core‐satellite nanoparticles (CSN) with an anisotropic morphology have enormous potential for targeted drug delivery and cancer treatment because of their large surface area, exceptional stability, and biocompatibility. We used a simple seed‐mediated approach to synthesize urchin‐like gold nanoparticles (ULGNPs) with a high aspect ratio and a dense network of 49 nm‐sized branches, using seed solution, silver nitrate, and ascorbic acid. The ULGNPs were synthesized without a surfactant and then encapsulated with thin layers of amorphous TiO2 (ULGNPs@TiO2), resulting in an average overall size of 136±15 nm with a 27.5 nm TiO2 layer. Doxorubicin (Dox) was chosen as a model drug to assess the distribution carrier ability of ULGNPs@TiO2 core‐satellite nanoparticles. The results showed 86.5 % Dox loading and 72.3 % release capacity at pH 5. The anti‐cancer ability of ULGNPs@TiO2‐Dox was meticulously assessed using breast cancer MCF‐7 cells in the WST‐1 assay. The results revealed that ULGNPs@TiO2‐Dox exhibited approximately 92 % toxicity in MCF‐7 cells compared to the free Dox of 89.6 % at low concentrations (5 ppm). Based on the simulation results for loading ULGNPs@TiO2 with Dox, it was observed that a structure containing five layers of Au (111) with three fixed bottom layers and two relaxed top layers, in addition to six TiO2 (100) layers, was analyzed using Grimme's DFT−D3 dispersion corrections (Scheme 1). The density functional theory (DFT) adsorption energy (Eads) shows that the amorphous TiO2 increases the Dox loading activity of ULGNPs, with Eads=−3.85 eV, negatively higher than isolated ULGNPs (Eads=−2.87 eV) and TiO2 alone (Eads=−3.61 eV). This drug carrier design has the potential to revolutionize anti‐cancer treatment. [ABSTRACT FROM AUTHOR]

The development of efficient methodologies for the controlled manufacture of specific stereoisomers bearing quaternary stereocenters has prompted advances in a variety of scientific disciplines including pharmaceutical chemistry, materials science, and chemical biology. However, complete control of the absolute and relative stereochemical configurations of alkyne derivatives remains an unmet synthetic challenge. Herein, a Ni/Cu dual‐catalyzed asymmetric propargylic substitution reaction is presented to produce propargylated products with all‐carbon quaternary stereocenters in high yields with significant diastereo‐ and enantioselectivities (up to >20:1 dr, >99% ee). The synthesis of all stereochemical variants of methohexital, a widely used sedative‐hypnotic drug, exemplifies the efficacy of dual‐catalyzed stereodivergent propargylation. [ABSTRACT FROM AUTHOR]

The development of innovative strategies for cell membranes engineering is of prime interest to explore and manipulate cell–cell interactions. Herein, an enzyme‐sensitive recognition marker that can be introduced on cell surface via bioorthogonal chemistry is designed. Once functionalized in this fashion, the cells gain the ability to assemble with cell partners coated with the complementary marker through non‐covalent click chemistry. The artificial cell adhesion induces natural biological processes associated with cell proximity such as inhibiting cancer cell proliferation and migration. On the other hand, the enzymatic activation of the stimuli‐responsive marker triggers the disassembly of cells, thereby restoring the tumor cell proliferation and migration rates. Thus, the study shows that the ready‐to‐use complementary markers are valuable tools for controlling the formation and the breaking of bonds between cells, offering an easy way to investigate biological processes associated to cell proximity. [ABSTRACT FROM AUTHOR]

DNA-based nanostructures and nanodevices have recently been employed for a broad range of applications in modulating the assemblies and interaction patterns of different cell membrane receptors. These versatile nanodevices can be rationally designed with modular structures, easily programmed and tweaked such that they may act as smart chemical biology and cell biology tools to reveal insights into complicated cellular signaling processes. Their outstanding in vitro and cellular features have also begun to be further validated for some in vivo applications and demonstrated their great biomedical potential. In this review, we will highlight some key current advances in the molecular engineering and biological applications of DNA-based functional nanodevices, with a focus on how these tools have been used to respond and modulate membrane receptor dimerizations and/or oligomerizations, as a way to control cellular signaling processes. Some current challenges and future directions to further develop and apply these DNA nanodevices will also be discussed. [ABSTRACT FROM AUTHOR]

For the celebration of the 30th anniversary of Cell Chemical Biology , in the September special issue, we asked former and current advisory board members and former editors to reflect on the advancements in chemical biology, changes in the field, and their insights into Cell Chemical Biology (originally Chemistry & Biology). [Display omitted] For the celebration of the 30th anniversary of Cell Chemical Biology , in the September special issue we asked former and current advisory board members and former editors to reflect on the advancements in chemical biology, changes in the field, and their insights into Cell Chemical Biology (originally Chemistry & Biology). [ABSTRACT FROM AUTHOR]

Since its inception, the chemical biology field has undergone significant evolution, with its definition varying greatly based on individual perspectives. For the September 30th anniversary special issue of Cell Chemical Biology , we asked our readers from a range of backgrounds, what is chemical biology? [Display omitted] Since its inception, chemical biology has undergone significant evolution, with its definition varying greatly based on individual perspectives. For the September 30th anniversary special issue of Cell Chemical Biology , we asked our readers from a range of backgrounds, what is chemical biology? [ABSTRACT FROM AUTHOR]

Cynanchum acutum L. (Asclepiadaceae) is a perennial vine weed widespread in the Mediterranean region. In Israel, it is native to areas such as the Golan Heights, Galilee, and the northern Negev. Recently, its range has expanded to the Arava Valley in the southern part of Israel. In this study, we investigate the biology and phenology of C. acutum plants originating from both native and invasive populations. To achieve this, we utilized rhizomes from the invasive area in the southern region characterized by a hyper-arid desert climate (Yahel), and from the northern region characterized by a temperate climate (Gvat). Additionally, we examine chemical-based weed management approaches for controlling C. acutum. Rhizomes collected from the northern region showed higher emergence rates at temperatures between 15-30°C, whereas at 35°C, rhizomes from the southern region exhibited a higher emergence rate. Phenology experiments conducted simultaneously at southern and northern locations revealed that plants from the northern location flowered first at both sites. However, flowering initiation occurred ~20 days earlier on average when plants from both populations were grown at the southern site. Pre-emergence herbicide treatments using indaziflam and pyroxasulfone were effective in inhibiting C. acutum root formation. According to the percentage of emergence, pendimethalin showed higher emergence (93% and 100%) in comparison to indaziflam (10% and 93%) and pyroxasulfone (72% and 70%) (2020 and 2021, respectively). Treatments including the herbicide fluroxypyr, as well as the treatment of glyphosate + saflufenacil + surfactant were highly effective in controlling C. acutum plants. These results offer valuable insights into effective weed management strategies for addressing C. acutum infestations. Moreover, our findings underscore the remarkable plasticity of this species and shed light on how populations originating from diverse habitats may have adapted to distinct environmental conditions. [ABSTRACT FROM AUTHOR]

Macrocycles are essential in protein‐protein interactions and the preferential intake of bioactive scaffolds. Macrocycles are commonly synthesized by late‐stage macrolactonizations, macrolactamizations, transition metal‐catalyzed ring‐closing metathesis, S−S bond‐forming reactions, and copper‐catalyzed alkyne–azide cycloaddition. Recently, transition metal‐catalyzed C−H activation strategies have gained significant interest among chemists to synthesize macrocycles. This article provides a comprehensive overview of the transition metal‐catalyzed macrocyclization via C−H bond functionalization of heterocycle‐containing peptides, annulations, and heterocycle‐ring construction through direct C−H bond functionalization. In the first part, palladium salt catalyzed coupling with indolyl C(sp3)−H and C(sp2)−H bonds for macrocyclization is reported. The second part summarizes rhodium‐catalyzed macrocyclizations via site‐selective C−H bond functionalization. Earth‐abundant, less toxic 3d metal salt Mn‐catalyzed cyclizations are reported in the latter part. This summary is expected to spark interest in emerging methods of macrocycle production among organic synthesis and chemical biology practitioners, helping to develop the discipline. We hope that this mini‐review will also inspire synthetic chemists to explore new and broadly applicable C−C bond‐forming strategies for macrocyclization via intramolecular C−H activation. [ABSTRACT FROM AUTHOR]

Inducible dimerization systems, such as rapamycin‐induced dimerization of FK506 binding protein (FKBP) and FKBP–rapamycin binding (FRB) domain, are widely employed chemical biology tools to manipulate cellular functions. We previously advanced an inducible dimerization system into an inducible oligomerization system by developing a bivalent fusion protein, FRB–FKBP, which forms large oligomers upon rapamycin addition and can be used to manipulate cells. However, the oligomeric structure of FRB–FKBP remains unclear. Here, we report that FRB–FKBP forms a rotationally symmetric trimer in crystals, but a larger oligomer in solution, primarily tetramers and pentamers, which maintain similar inter‐subunit contacts as in the crystal trimer. These findings expand the applications of the FRB–FKBP oligomerization system in diverse biological events. [ABSTRACT FROM AUTHOR]

Developing effective inhibitors of the DNA repair enzyme tyrosyl-DNA phosphodiesterase 1 (TDP1) has been challenging because of the enzyme shallow catalytic pocket and non-specific substrate binding interactions. Recently, we discovered a quinolone-binding hot spot in TDP1's active site proximal to the evolutionary conserved Y204 and F259 residues that position DNA. Sulfur (VI) fluoride exchange (SuFEx) is a biocompatible click chemistry reaction that enables acylation of protein residues, including tyrosine. Selective protein modifications can provide insights into the biological roles of proteins and inform ligand design. As we report herein, we used SuFEx chemistries to prepare covalent TDP1-bound binders showing site-specific covalent bonds with Y204. Our work presents the first application of SuFEx chemistries to TDP1 ligands. It validates the ability to covalently modify specific TDP1 residues by designed targeting and adds to the chemical biology resource toolbox for studying TDP1. Developing effective inhibitors of the DNA repair enzyme tyrosyl-DNA phosphodiesterase 1 (TDP1) is challenging because of the enzyme's shallow catalytic pocket and non-specific substrate binding interactions. Here, the authors use Sulfur (VI) fluoride exchange chemistries to prepare covalent TDP1-bound binders showing site-specific covalent bonds with the Y204 residue that position DNA. [ABSTRACT FROM AUTHOR]

Supramolecular chemistry focuses on the study of species joined by non-covalent interactions, and therefore on dynamic and relatively ill-defined structures. Despite being a well-developed field, it has to face important challenges when dealing with the selective recognition of biomolecules in highly competitive biomimetic media. However, supramolecular interactions reside at the core of chemical biology systems, since many processes in nature are governed by weak, non-covalent, strongly dynamic contacts. Therefore, there is a natural connection between these two research fields, which are not frequently related or share interests. In this feature article, I will highlight our most recent results in the molecular recognition of biologically relevant species, following different conceptual approaches from the most conventional design of elaborated receptors to the less popular dynamic combinatorial chemistry methodology. Selected illustrative examples from other groups will be also included. The discussion has been focused mainly on systems with potential biomedical applications. [ABSTRACT FROM AUTHOR]

Multi-functional cysteine-targeting covalent warheads possess significant therapeutic potential in medicinal chemistry and chemical biology. Herein, we present novel unsaturated and asymmetric ketone (oxazolinosene) scaffolds that selectively conjugate cysteine residues of peptides and bovine serum albumin under normal physiological conditions. This unsaturated saccharide depletes GSH in NCI-H1299 cells, leading to anti-tumor effects in vitro. The acetyl group of the ketal moiety on the saccharide ring can be converted to other carboxylic acids in a one-pot synthesis. In this way, the loaded acid can be click-released during cysteine conjugation, making the oxazolinosene a potential multifunctional therapeutic agent. The reaction kinetic model for oxazolinosene conjugation to GSH is well established and was used to evaluate oxazolinosene reactivity. The aforementioned oxazolinosenes were stereoselectively synthesized via a one-step reaction of nitriles with saccharides and conveniently converted into a series of α, β-unsaturated ketone N-glycosides as prevalent synthetic building blocks. The reaction mechanisms of oxazolinosene synthesis were investigated through calculations and validated with control experiments. Overall, these oxazolinosenes can be easily synthesized and developed as cysteine-targeted covalent warheads carrying useful click-releasing groups. Multifunctional cysteine targeting covalent warheads possess significant therapeutic potential in medicinal chemistry and chemical biology. Here, the authors develop an oxazolinosene scaffold from nitrile groups and saccharides that can selectively conjugate cysteine residues within peptides and proteins under physiological conditions, as well as deplete glutathione in cancer cells. [ABSTRACT FROM AUTHOR]

Peptide therapeutics play an increasingly important role in modern drug discovery. Improving the pharmacokinetic profile of bioactive peptides has been effectively achieved with chemical modifications, especially macrocyclisation reactions. Consequently, there is a great demand for highly constrained compounds such as bicyclic peptides. In our previous research, we introduced peptide–bismuth bicycles and peptide–arsenic bicycles as new classes of constrained peptides. In this work, we extend our peptide bicyclisation strategy towards antimony. Similar to arsenic and bismuth, antimony(III) selectively binds to three cysteine residues in peptides, enabling the in situ formation of stable bicycles. The bicyclisation reaction occurs instantaneously under biocompatible conditions at physiological pH. Antimony–peptide bicycles remain largely intact in the presence of the common metal chelator ethylenediaminetetraacetic acid (EDTA) and the main endogenous thiol competitor glutathione (GSH). Furthermore, when challenged with bismuth(III) from water-soluble gastrodenol (bismuth tripotassium dicitrate), antimony–peptide bicycles convert into the corresponding bismuth–peptide bicycle, highlighting the superior thiophilicity of bismuth over other pnictogens. Our study further expands the toolbox of peptide multicyclisation with main group elements previously underexplored in chemical biology. Cyclic peptide drugs are important therapeutics. Previously, bismuth and arsenic were introduced to create peptide bicycles by binding three cysteines. Now, antimony complements this set of elements to form stable bicyclic peptides. These remain stable in the presence of a common metal chelator and glutathione. Bismuth outcompetes antimony as the core atom in peptide bicycles. (Image credit: Lani Davies.) This article belongs to the 10th Anniversary Collection of RACI and AAS Award papers. [ABSTRACT FROM AUTHOR]

Bioorthogonal click chemistry has played a transformative role in many research fields, including chemistry, biology, and medicine. Click reactions are crucial to produce increasingly complex bioconjugates, to visualize and manipulate biomolecules in living systems and for various applications in bioengineering and drug delivery. As biological (model) systems grow more complex, researchers have an increasing need for using multiple orthogonal click reactions simultaneously. In this review, we will introduce the most common bioorthogonal reactions and discuss their orthogonal use on the basis of their mechanism and electronic or steric tuning. We provide an overview of strategies to create reaction orthogonality and show recent examples of mutual orthogonal chemistry used for simultaneous biomolecule labeling. We end by discussing some considerations for the type of chemistry needed for labeling biomolecules in a system of choice. [ABSTRACT FROM AUTHOR]

Antibodies are critical reagents to detect and characterize proteins. It is commonly understood that many commercial antibodies do not recognize their intended targets, but information on the scope of the problem remains largely anecdotal, and as such, feasibility of the goal of at least one potent and specific antibody targeting each protein in a proteome cannot be assessed. Focusing on antibodies for human proteins, we have scaled a standardized characterization approach using parental and knockout cell lines (Laflamme et al., 2019) to assess the performance of 614 commercial antibodies for 65 neuroscience-related proteins. Side-by-side comparisons of all antibodies against each target, obtained from multiple commercial partners, have demonstrated that: (i) more than 50% of all antibodies failed in one or more applications, (ii) yet, ~50-75% of the protein set was covered by at least one high-performing antibody, depending on application, suggesting that coverage of human proteins by commercial antibodies is significant; and (iii) recombinant antibodies performed better than monoclonal or polyclonal antibodies. The hundreds of underperforming antibodies identified in this study were found to have been used in a large number of published articles, which should raise alarm. Encouragingly, more than half of the underperforming commercial antibodies were reassessed by the manufacturers, and many had alterations to their recommended usage or were removed from the market. This first study helps demonstrate the scale of the antibody specificity problem but also suggests an efficient strategy toward achieving coverage of the human proteome; mine the existing commercial antibody repertoire, and use the data to focus new renewable antibody generation efforts.

We have devised a single pot, low-cost method to add azide groups to unmodified nucleic acids without the need for enzymes or chemically modified nucleoside triphosphates. This involves reacting an azide-containing sulfinate salt with the nucleic acid, leading to replacement of C-H bonds on the nucleobase aromatic rings with C-R, where R is the azide-containing linker derived from the original sulfinate salt. With the addition of azide functional groups, the modified nucleic acid can easily be reacted with any alkyne-labeled compound of interest, including fluorescent dyes as shown in this work. This methodology enables the fluorescent labeling of a wide variety of nucleic acids, including natively folded RNAs, under mild conditions with minimal effects upon biochemical function and ribozyme catalysis. To demonstrate this, we show that a pair of labeled complementary ssDNA oligonucleotides (oligos) can hybridize to form dsDNA, even when labeled with multiple fluorophores per oligo. In addition, we also demonstrate that two different group II introns can splice when prelabeled internally with fluorophores, using our method. Broadly, this demonstrates that sulfinate modification of RNA is compatible with ribozyme function and Watson-Crick pairing, while preserving the labile backbone.

Sulfonyl fluorides hold significant importance as highly valued intermediates in chemical biology due to their optimal balance of biocompatibility with both aqueous stability and protein reactivity. The Cornella group introduced a one‐pot strategy for synthesizing aryl sulfonyl fluorides via Bi(III) redox‐neutral catalysis, which facilitates the transmetallation and direct insertion of SO2 into the BiC(sp2) bond giving the aryl sulfonyl fluorides. We report herein a comprehensive computational investigation of the redox‐neutral Bi(III) catalytic mechanism, disclose the critical role of the Bi(III) catalyst and base (i.e., K3PO4), and uncover the origin of SO2 insertion into the Bi(III)C(sp2) bond. The entire catalysis can be characterized via three stages: (i) transmetallation generating the Bi(III)‐phenyl intermediate IM3 facilitated by K3PO4. (ii) SO2 insertion into IM3 leading to the formation of Bi(III)‐OSOAr intermediate IM5. (iii) IM5 undergoes S(IV)‐oxidation yielding the aryl sulfonyl fluoride product 4 and liberating the Bi(III) catalyst for the next catalytic cycle. Each stage is kinetically and thermodynamically feasible. Moreover, we explored other some small molecules (NO2, CO2, H2O, N2O, etc.) insertion reactions mediated by the Bi(III)‐complex, and found that NO2 insertions could be easily achieved due to the low insertion barriers (i.e., 17.5 kcal/mol). Based on the detailed mechanistic study, we further rationally designed additional Bi(III) and Sb(III) catalysts, and found that some of which exhibit promising potential for experimental realization due to their low barriers (<16.4 kcal/mol). In this regard, our study contributes significantly to enhancing current Bi(III)‐catalytic systems and paving the way for novel Bi(III)‐catalyzed aryl sulfonyl fluoride formation reactions. [ABSTRACT FROM AUTHOR]

In recent years, impairing mitochondria in cancer cells gained attention as alternative cancer therapy. In this context, non‐steroidal anti‐inflammatory (NSAID) drugs are interesting candidates to damage mitochondria in cancer cells. However, routing NSAIDs specifically into the mitochondria remained a major challenge and less explored. Herein, we have synthesized a small library of Meclofenamic acid and Naproxen derivatives having ester and amide linkage with substituted triphenylphosphonium cations for mitochondria targeting. Screening in cervical cancer (HeLa), breast cancer (MCF7) and colon cancer (HCT‐116) cells revealed a Meclofenamic acid derivative having ester linkage with tri (4‐methoxyphenyl) phosphonium cation (8A3) which induced mitochondrial damage through mitochondrial outer membrane permeabilization (MOMP) followed by generation of reactive oxygen species (ROS) in the HCT‐116 cells. This 8A3‐mediated mitochondrial impairment triggered apoptosis by inhibiting Cox‐2, reduction in Bcl‐2/Bcl‐xl expression and Caspase‐3/9 cleavage leading to remarkable HCT‐116 cell death. This novel mitochondrion targeted Meclofenamic acid derivative has the potential to be used as a chemical biology tool to understand the role of NSAIDs in mitochondria towards cancer therapy. [ABSTRACT FROM AUTHOR]

Recently, the introduction of fluorosulfonyl (−SO2F) groups have attracted considerable research interests, as this moiety could often afford enhanced activities and new functions in the context of chemical biology and drug discovery. Herein, we report the design and synthesis of 1‐fluorosulfamoyl‐pyridinium (FSAP) salts, which could serve as an effective photoredox‐active precursor to fluorosulfamoyl radicals and enable the direct radical C−H fluorosulfonamidation of a variety of (hetero)arenes. This method features mild conditions, visible light, broad substrate scope, good group tolerance, etc. and a metal‐free protocol is also viable by using organic photocatalysts. Further, FSAP can also be applied to the radical functionalization of alkenes via 1,2‐difunctionalization, radical distal migration, tandem radical‐polar crossover reactions, etc. In addition, a formal C−H methylamination of (hetero)arenes by combining this radical C−H fluorosulfonamidation with subsequent hydrolysis as well as product derivatization are also demonstrated. [ABSTRACT FROM AUTHOR]

Nitrile‐aminothiol conjugation (NATC) stands out as a promising biocompatible ligation technique due to its high chemo‐selectivity. Herein we investigated the reactivity and substrate scope of NAT conjugation chemistry, thus developing a novel pH dependent orthogonal NATC as a valuable tool for chemical biology. The study of reaction kinetics elucidated that the combination of heteroaromatic nitrile and aminothiol groups led to the formation of an optimal bioorthogonal pairing, which is pH dependent. This pairing system was effectively utilized for sequential and dual conjugation. Subsequently, these rapid (≈1 h) and high yield (>90 %) conjugation strategies were successfully applied to a broad range of complex biomolecules, including oligonucleotides, chelates, small molecules and peptides. The effectiveness of this conjugation chemistry was demonstrated by synthesizing a fluorescently labelled antimicrobial peptide‐oligonucleotide complex as a dual conjugate to imaging in live cells. This first‐of‐its‐kind sequential NATC approach unveils unprecedented opportunities in modern chemical biology, showcasing exceptional adaptability in rapidly creating structurally complex bioconjugates. Furthermore, the results highlight its potential for versatile applications across fundamental and translational biomedical research. [ABSTRACT FROM AUTHOR]

Hydrogen selenide (H2Se) is an emerging biomolecule of interest with similar properties to that of other gaseous signaling molecules (i.e., gasotransmitters that include nitric oxide, carbon monoxide, and hydrogen sulfide). H2Se is enzymatically generated in humans where it serves as a key metabolic intermediate in the production of selenoproteins and other selenium-containing biomolecules. However, beyond its participation in biosynthetic pathways, its involvement in cellular signaling or other biological mechanisms remains unclear. To uncover its true biological significance, H2Se-specific chemical tools capable of functioning under physiological conditions are required but lacking in comparison to those that exist for other gasotransmitters. Recently, researchers have begun to fill this unmet need by developing new H2Se-releasing compounds, along with pioneering methods for selenide detection and quantification. In combination, the chemical tools highlighted in this review have the potential to spark groundbreaking explorations into the chemical biology of H2Se, which may lead to its branding as the fourth official gasotransmitter. [ABSTRACT FROM AUTHOR]

Sulfur(VI)‐based functional groups are popular scaffolds in a wide variety of research fields including synthetic and medicinal chemistry, as well as chemical biology. The growing interest in sulfur(VI)‐containing molecules has motivated the scientific community to explore new methods to synthesize and modify them. Here, photocatalysis plays a key role granting access to new types of reactivity under mild reaction conditions. In this Perspective, we present a selection of works reported in the last six years focused on the photocatalytic assembly and reactivity of sulfones, sulfonamides, and sulfoximines. We addressed the key synthetic intermediates for each transformation, while discussing limitations and strength points of the protocols. Future directions of the field are finally presented. [ABSTRACT FROM AUTHOR]

Simple Summary: Human beings are always associated with small molecules throughout their lives. Chemical proteomics, which selectively identifies small-molecule targets, is an emerging approach for unraveling the mechanism of action of small molecules for therapeutic target identification and drug discovery. This review attempts to introduce representative techniques of chemical proteomics and summarizes examples of identifying small-molecule targets. Throughout the human lifespan, from conception to the end of life, small molecules have an intrinsic relationship with numerous physiological processes. The investigation into small-molecule targets holds significant implications for pharmacological discovery. The determination of the action sites of small molecules provide clarity into the pharmacodynamics and toxicological mechanisms of small-molecule drugs, assisting in the elucidation of drug off-target effects and resistance mechanisms. Consequently, innovative methods to study small-molecule targets have proliferated in recent years, with chemical proteomics standing out as a vanguard development in chemical biology in the post-genomic age. Chemical proteomics can non-selectively identify unknown targets of compounds within complex biological matrices, with both probe and non-probe modalities enabling effective target identification. This review attempts to summarize methods and illustrative examples of small-molecule target identification via chemical proteomics. It delves deeply into the interactions between small molecules and human biology to provide pivotal directions and strategies for the discovery and comprehension of novel pharmaceuticals, as well as to improve the evaluation of drug safety. [ABSTRACT FROM AUTHOR]

This paper presents a comprehensive experiment within the interdisciplinary field of chemical biology, closely aligned with the cutting-edge of the discipline, deeply integrating science and education. Utilizing both chemical and biological methods within an in vitro biochemical reaction system, this study investigates effects of the natural antioxidant quercetin on the redox cycle of myeloperoxidase (MPO) within biological organisms. The mechanism of quercetin affecting the chlorination activity of MPO is clarified through molecular docking techiniques and a series of UV-Vis absorption spectroscopy. The implementation of this experiment aids in broadening students’ perspectives, igniting their interest in scientific research, and enhancing their comprehensive experimental abilities. It offers valuable insights and examples for the development of multidisciplinary innovative talents in chemistry-related majors. [ABSTRACT FROM AUTHOR]

Introduction: Ovarian and other peritoneal cancers have a strong tendency to metastasize into the surrounding adipose tissue. This study describes an effect of the adipose microenvironment on upregulation of sialic acid-containing glycans in ovarian cancer (OC). Heterogeneous populations of glycosylated OC tumors converged to a highly sialylated cell state that regulates tumorigenesis in an immune-dependent manner. Methods: We modeled the adipose microenvironment by conditioning growth media with human patient-derived adipose tissue. OC cell lines grown in the presence vs. absence of adipose conditioned media (ACM) were characterized by transcriptomics, western blotting, and chemical biology glycan labeling methods. Fluorescence-activated cell sorting was used to separate adipose-driven upregulation of hypersialylated ("SNA-high") vs. hyposialylated ("SNA-low") OC subpopulations. The two subpopulations were characterized by further transcriptomic and quantitative polymerase chain reaction analyses, then injected into a syngeneic mouse model. Immune system involvement was implicated using wild type and athymic nude mice with a primary endpoint of overall survival. Results: Adipose conditioning resulted in upregulation of sialyltransferases ST3GAL1, ST6GAL1, ST6GALNAC3, and ST8Sia1. In culture, OC cells displayed two distinct sialylated subpopulations that were stable for up to 9 passages, suggesting inherent heterogeneity in sialylation that is maintained throughout cell division and media changes. OC tumors that implanted in the omental adipose tissue exclusively reprogrammed to the highly sialylated subpopulation. In wild type C57BL/6 mice, only the hypersialylated SNA-high subpopulation implanted in the adipose, whereas the hyposialylated SNA-low subpopulation failed to be tumorigenic (p=0.023, n=5). In the single case where SNA-low established a tumor, post-mortem analysis revealed reprogramming of the tumor to the SNA-high state in vivo. In athymic nude mice, both subpopulations rapidly formed tumors, implicating a role of the adaptive immune system. Conclusions: These findings suggest a model of glycan-dependent tumor evolution wherein the adipose microenvironment reprograms OC to a tumorigenic state that resists the adaptive immune system. Mechanistically, adipose factors upregulate sialyltransferases. To our knowledge, this is the first demonstration of the effect of adipose microenvironment on OC tumor sialylation. Our results set the stage for translational applications targeting sialic acid pathways in OC and other peritoneal cancer tumorigenesis and metastasis. [ABSTRACT FROM AUTHOR]