SyntheticN-Acetyl-d-glucosamine Based Fully Branched Tetrasaccharide, a Mimetic of the Endogenous Ligand for CD69, Activates CD69⁺Killer Lymphocytes upon Dimerization via a Hydrophilic Flexible Linker

Abstract

On the basis of the highly branched ovomucoid-type undecasaccharide that had been shown previously to be an endogenous ligand for CD69 leukocyte receptor, a systematic investigation of smaller oligosaccharide mimetics was performed based on linear and branched N-acetyl-d-hexosamine homooligomers prepared synthetically using hitherto unexplored reaction schemes. The systematic structure-activity studies revealed the tetrasaccharide GlcNAcbeta1-3(GlcNAcbeta1-4)(GlcNAcbeta1-6)GlcNAc (compound 52) and its alpha-benzyl derivative 49 as the best ligand for CD69 with IC(50) as high as 10(-9) M. This compound thus approaches the affinity of the classical high-affinity neoglycoprotein ligand GlcNAc(23)BSA. Compound 68, GlcNAc tetrasaccharide 52 dimerized through a hydrophilic flexible linker, turned out to be effective in activating CD69(+) lymphocytes. It also proved efficient in enhancing natural killing in vitro, decreasing the growth of tumors in vivo, and activating the CD69(+) tumor infiltrating lymphocytes examined ex vivo. This compound is thus a candidate for carbohydrate-based immunomodulators with promising antitumor potential.

Resolving the α-glycosidic linkage of arginine-rhamnosylated translation elongation factor P triggers generation of the first ArgRha specific antibody

“…27 Next, glycosyl thiourea 5 was prepared via ammoniation of 4 in tetrahydrofuran (99% yield). 28 Finally, a two-step, one-pot procedure converted 5 into 6 in the presence of ethyl iodide and tert -butoxycarbonyl anhydride (75% yield). 29 Taken together from 2 to 6 we ended up with an efficiency of about 44%.…”

Guarding the perimeter: protection of the mucosa by tissue-resident memory T cells

“…58,91 The natural ligands for CD69 have not been conclusively identified, but are thought to include complex oligosaccharides. 115 Earlier studies show that overexpression of CD69 slows the rate at which naive T cells exit the thymus, 116,117 whereas CD69-deficient T cells exit peripheral LNs more rapidly than their wild-type counterparts after activation with poly-I:C or viral infection. 118 The lipid sphingosine-1-phosphate (S1P) has an essential role in lymphocyte migration 119 and evidence of interacions between CD69 and the S1P receptor 1 (S1P1) may provide clues to CD69 function in tissue retention of Trms.…”

Re-Evaluation of Binding Properties of Recombinant Lymphocyte Receptors NKR-P1A and CD69 to Chemically Synthesized Glycans and Peptides

“…This observation contradicted previous reports that the presence of Ca 2+ in the buffer during analysis is essential [16]. In later studies, one of the tested branched N -acetyl- d -hexosamines prepared synthetically exhibited K d = 3.4 nM, indicating significant potential as a glycomimetic in antitumor therapy [19]. None of above compounds have been patented and no clinical trials have been started.…”

“…In the previous articles by Bezouška and coworkers, the binding activity was mainly documented using plate binding assays with the proteins labeled with fluorescent or radioactive probes. In a few publications, equilibrium dialysis and NMR titrations were performed by Bezouška’s co-workers [18,19], however during the NMR titrations, only the signal of the free saccharide was analyzed in a 1D spectrum. Therefore, we decided to investigate the receptor-ligand interaction using more accurate techniques such as isothermal titration calorimetry and NMR titrations, monitoring the signals of the protein in 1 H- 15 N HSQC spectra.…”