Proximity Tagging Identifies the Glycan-Mediated Glycoprotein Interactors of Galectin‑1 in Muscle Stem Cells

Myogenic
differentiation, the irreversible developmental process
where precursor myoblast muscle stem cells become contractile myotubes,
is heavily regulated by glycosylation and glycan–protein interactions
at the cell surface and the extracellular matrix. The glycan-binding
protein galectin-1 has been found to be a potent activator of myogenic
differentiation. While it is being explored as a potential therapeutic
for muscle repair, a precise understanding of its glycoprotein interactors
is lacking. These gaps are due in part to the difficulties of capturing
glycan–protein interactions in live cells. Here, we demonstrate
the use of a proximity tagging strategy coupled with quantitative
mass-spectrometry-based proteomics to capture, enrich, and identify
the glycan-mediated glycoprotein interactors of galectin-1 in cultured
live mouse myoblasts. Our interactome dataset can serve as a resource
to aid the determination of mechanisms through which galectin-1 promotes
myogenic differentiation. Moreover, it can also facilitate the determination
of the physiological glycoprotein counter-receptors of galectin-1.
Indeed, we identify several known and novel glycan-mediated ligands
of galectin-1 as well as validate that galectin-1 binds the native
CD44 glycoprotein in a glycan-mediated manner.