4 research outputs found
Cell-Selective Metabolic Glycan Labeling Based on Ligand-Targeted Liposomes
A cell-specific metabolic glycan labeling strategy has
been developed using azidosugars encapsulated in ligand-targeted liposomes.
The ligands are designed to bind specific cell-surface receptors that
are only expressed or up-regulated in target cells, which mediates
the intracellular delivery of azidosugars. The delivered azidosugars
are metabolically incorporated into cell-surface glycans, which are
then imaged via a bioorthogonal reaction
Bifunctional Unnatural Sialic Acids for Dual Metabolic Labeling of Cell-Surface Sialylated Glycans
Sialic acid analogues
containing a unique chemical functionality
or chemical reporter have been metabolically incorporated into sialylated
glycans. This process, termed metabolic glycan labeling, has emerged
as a powerful tool for studying sialylation as well as other types
of glycosylation. Currently, this technique can install only a single
functionality. Here we describe a strategy for dual labeling of sialylated
glycans using a new class of bifunctional sialic acid analogues containing
two distinct chemical reporters at the <i>N</i>-acyl and
C9 positions. These bifunctional unnatural sialic acids were metabolically
incorporated into cellular glycans, where the two chemical reporters
exerted their distinct functions. This approach expands the capability
of metabolic glycan labeling to probe sialylation and glycan–protein
interactions
Glycan Imaging in Intact Rat Hearts and Glycoproteomic Analysis Reveal the Upregulation of Sialylation during Cardiac Hypertrophy
In
the heart, glycosylation is involved in a variety of physiological
and pathological processes. Cardiac glycosylation is dynamically regulated,
which remains challenging to monitor <i>in vivo</i>. Here
we describe a chemical approach for analyzing the dynamic cardiac
glycome by metabolically labeling the cardiac glycans with azidosugars
in living rats. The azides, serving as a chemical reporter, are chemoselectively
conjugated with fluorophores using copper-free click chemistry for
glycan imaging; derivatizing azides with affinity tags allows enrichment
and proteomic identification of glycosylated cardiac proteins. We
demonstrated this methodology by visualization of the cardiac sialylated
glycans in intact hearts and identification of more than 200 cardiac
proteins modified with sialic acids. We further applied this methodology
to investigate the sialylation in hypertrophic hearts. The imaging
results revealed an increase of sialic acid biosynthesis upon the
induction of cardiac hypertrophy. Quantitative proteomic analysis
identified multiple sialylated proteins including neural cell adhesion
molecule 1, T-kininogens, and α<sub>2</sub>-macroglobulin that
were upregulated during hypertrophy. The methodology may be further
extended to other types of glycosylation, as exemplified by the mucin-type
O-linked glycosylation. Our results highlight the applications of
metabolic glycan labeling coupled with bioorthogonal chemistry in
probing the biosynthesis and function of cardiac glycome during pathophysiological
responses
Glycan Imaging in Intact Rat Hearts and Glycoproteomic Analysis Reveal the Upregulation of Sialylation during Cardiac Hypertrophy
In
the heart, glycosylation is involved in a variety of physiological
and pathological processes. Cardiac glycosylation is dynamically regulated,
which remains challenging to monitor <i>in vivo</i>. Here
we describe a chemical approach for analyzing the dynamic cardiac
glycome by metabolically labeling the cardiac glycans with azidosugars
in living rats. The azides, serving as a chemical reporter, are chemoselectively
conjugated with fluorophores using copper-free click chemistry for
glycan imaging; derivatizing azides with affinity tags allows enrichment
and proteomic identification of glycosylated cardiac proteins. We
demonstrated this methodology by visualization of the cardiac sialylated
glycans in intact hearts and identification of more than 200 cardiac
proteins modified with sialic acids. We further applied this methodology
to investigate the sialylation in hypertrophic hearts. The imaging
results revealed an increase of sialic acid biosynthesis upon the
induction of cardiac hypertrophy. Quantitative proteomic analysis
identified multiple sialylated proteins including neural cell adhesion
molecule 1, T-kininogens, and α<sub>2</sub>-macroglobulin that
were upregulated during hypertrophy. The methodology may be further
extended to other types of glycosylation, as exemplified by the mucin-type
O-linked glycosylation. Our results highlight the applications of
metabolic glycan labeling coupled with bioorthogonal chemistry in
probing the biosynthesis and function of cardiac glycome during pathophysiological
responses