- Steering Siglec–Sialic Acid Interactions on Living Cells using Bioorthogonal Chemistry
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Sialic acid sugars that terminate cell-surface glycans form the ligands for the sialic acid binding immunoglobulin-like lectin (Siglec) family, which are immunomodulatory receptors expressed by immune cells. Interactions between sialic acid and Siglecs regulate the immune system, and aberrations contribute to pathologies like autoimmunity and cancer. Sialic acid/Siglec interactions between living cells are difficult to study owing to a lack of specific tools. Here, we report a glycoengineering approach to remodel the sialic acids of living cells and their binding to Siglecs. Using bioorthogonal chemistry, a library of cells with more than sixty different sialic acid modifications was generated that showed dramatically increased binding toward the different Siglec family members. Rational design reduced cross-reactivity and led to the discovery of three selective Siglec-5/14 ligands. Furthermore, glycoengineered cells carrying sialic acid ligands for Siglec-3 dampened the activation of Siglec-3+ monocytic cells through the NF-κB and IRF pathways.
- Büll, Christian,Heise, Torben,van Hilten, Niek,Pijnenborg, Johan F. A.,Bloemendal, Victor R. L. J.,Gerrits, Lotte,Kers-Rebel, Esther D.,Ritschel, Tina,den Brok, Martijn H.,Adema, Gosse J.,Boltje, Thomas J.
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supporting information
p. 3309 - 3313
(2017/03/17)
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- Copper-chelating azides for efficient click conjugation reactions in complex media
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The concept of chelation-assisted copper catalysis was employed for the development of new azides that display unprecedented reactivity in the copper(I)-catalyzed azide-alkyne [3+2] cycloaddition (CuAAC) reaction. Azides that bear strong copper-chelating moieties were synthesized; these functional groups allow the formation of azide copper complexes that react almost instantaneously with alkynes under diluted conditions. Efficient ligation occurred at low concentration and in complex media with only one equivalent of copper, which improves the biocompatibility of the CuAAC reaction. Furthermore, such a click reaction allowed the localization of a bioactive compound inside living cells by fluorescence measurements. Chelating azides were designed to form clickable copper complexes for efficient ligation with alkynes in complex biological media. Among a series of azides that bear nitrogen heterocycles, a bis(triazole) azide allowed ultra-fast click reactions with alkynes within seconds under diluted conditions. The reactivity and stability of this copper complex enabled efficient click reactions inside living cells.
- Bevilacqua, Valentina,King, Mathias,Chaumontet, Manon,Nothisen, Marc,Gabillet, Sandra,Buisson, David,Puente, Celine,Wagner, Alain,Taran, Frederic
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supporting information
p. 5872 - 5876
(2014/06/10)
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