An RNA aptamer restores defective bone growth in FGFR3-related skeletal dysplasia in mice.

Achondroplasia is the most prevalent genetic form of dwarfism in humans and is caused by activating mutations in FGFR3 tyrosine kinase. The clinical need for a safe and effective inhibitor of FGFR3 is unmet, leaving achondroplasia currently incurable. Here, we evaluated RBM-007, an RNA aptamer previously developed to neutralize the FGFR3 ligand FGF2, for its activity against FGFR3.

Structural basis for specific inhibition of Autotaxin by a DNA aptamer.

ATX is a plasma lysophospholipase D that hydrolyzes lysophosphatidylcholine (LPC) and produces lysophosphatidic acid. To date, no ATX-inhibition-mediated treatment strategies for human diseases have been established. Here, we report anti-ATX DNA aptamers that inhibit ATX with high specificity and efficacy.

High Throughput ELISAs to Measure a Unique Glycan on Transferrin in Cerebrospinal Fluid: A Possible Extension toward Alzheimer's Disease Biomarker Development.

We have established high-throughput lectin-antibody ELISAs to measure different glycans on transferrin (Tf) in cerebrospinal fluid (CSF) using lectins and an anti-transferrin antibody (TfAb). Lectin blot and precipitation analysis of CSF revealed that PVL (Psathyrella velutina lectin) bound an unique N-acetylglucosamine-terminated N-glycans on "CSF-type" Tf whereas SSA (Sambucus sieboldiana agglutinin) bound α2,6-N-acetylneuraminic acid-terminated N-glycans on "serum-type" Tf. PVL-TfAb ELISA of 0.

High affinity sialoside ligands of myelin associated glycoprotein.

Myelin associated glycoprotein (Siglec-4) is a myelin adhesion receptor, that is, well established for its role as an inhibitor of axonal outgrowth in nerve injury, mediated by binding to sialic acid containing ligands on the axonal membrane. Because disruption of myelin-ligand interactions promotes axon outgrowth, we have sought to develop potent ligand based inhibitors using natural ligands as scaffolds. Although natural ligands of MAG are glycolipids terminating in the sequence NeuAcα2-3Galβ1-3(±NeuAcα2-6)GalNAcβ-R, we previously established that synthetic O-linked glycoprotein glycans with the same sequence α-linked to Thr exhibited ∼1000-fold increased affinity (∼1μM).

A unique N-glycan on human transferrin in CSF: a possible biomarker for iNPH.

Idiopathic normal pressure hydrocephalus (iNPH) is an elderly dementia caused by abnormal metabolism in the cerebrospinal fluid (CSF). The tap test is the current basis for confirming iNPH, but it shows very low sensitivity, indicating that many patients who might be cured by a shunt operation will be missed. On sodium dodecyl sulfate-polyacrylamide gel electrophoresis, we found two transferrin isoforms: one had a unique N-glycan (Tf-1) whereas the other had N-glycan similar to that of serum transferrin (Tf-2).

Alpha2,6-sialic acid on platelet endothelial cell adhesion molecule (PECAM) regulates its homophilic interactions and downstream antiapoptotic signaling.

Antiangiogenesis therapies are now part of the standard repertoire of cancer therapies, but the mechanisms for the proliferation and survival of endothelial cells are not fully understood. Although endothelial cells are covered with a glycocalyx, little is known about how endothelial glycosylation regulates endothelial functions. Here, we show that alpha2,6-sialic acid is necessary for the cell-surface residency of platelet endothelial cell adhesion molecule (PECAM), a member of the immunoglobulin superfamily that plays multiple roles in cell adhesion, mechanical stress sensing, antiapoptosis, and angiogenesis.

Molecular insights into beta-galactoside alpha2,6-sialyltransferase secretion in vivo.

Beta-galactoside alpha2,6-sialyltransferase (ST6Gal I), which is highly expressed in the liver, is mainly cleaved by Alzheimer's beta-site amyloid precursor protein-cleaving enzyme 1 (BACE1) and secreted into the serum. During our studies to elucidate the molecular mechanism underlying the cleavage and secretion of ST6Gal I, we hypothesized that plasma ST6Gal I may represent a sensitive biomarker for hepatopathological situations. In the present study, we used recently developed sandwich ELISA systems that specifically detect the soluble cleaved form of ST6Gal I in plasma.

Development of sandwich enzyme-linked immunosorbent assay systems for plasma beta-galactoside alpha2,6-sialyltransferase, a possible hepatic disease biomarker.

Previous reports, including our work, have shown that plasma beta-galactoside alpha2,6-sialyltransferase (ST6Gal I) activity is significantly increased in particular hepatopathological situations, suggesting that it may represent a sensitive biomarker for diagnosing hepatic diseases. So far, activity of ST6Gal I have been measured by using radioactive tracer method in place of measuring amount of ST6Gal I. However, this method is tangled and cannot exclude other sialyltransferase activities.

Sialoside analogue arrays for rapid identification of high affinity siglec ligands.

The siglec family of sialic acid binding proteins participates in diverse cell surface biology that includes regulation of immune cell signaling and the interaction of neuronal cells with glial cells. The weak intrinsic affinity of the natural sialoside ligands has hampered the development of synthetic ligand based probes needed to elucidate their roles in siglec function. In this report, we describe a glycan microarray comprising a library of 9-acyl-substituted sialic acids incorporated into sialosides containing the Neu5Acalpha2-3Gal and Neu5Acalpha-6Gal linkages commonly recognized by the siglecs.

Beta-galactoside alpha2,6-sialyltransferase I cleavage by BACE1 enhances the sialylation of soluble glycoproteins. A novel regulatory mechanism for alpha2,6-sialylation.

BACE1 (beta-site amyloid precursor protein-cleaving enzyme-1) is a membrane-bound aspartic protease that cleaves amyloid precursor protein to produce a neurotoxic peptide, amyloid beta-peptide, and has been implicated in triggering the pathogenesis of Alzheimer disease. We showed previously that BACE1 cleaves beta-galactoside alpha2,6-sialyltransferase I (ST6Gal I) to initiate its secretion, but it remained unclear how BACE1 affects the cellular level of alpha2,6-sialylation. Here, we found that BACE1 overexpression in Hep3B cells increased the sialylation of soluble secreted glycoproteins, but did not affect cell-surface sialylation.