Identification of the Plasticity-Relevant Fucose-α(1-2)-Galactose Proteome from the Mouse Olfactory Bulb

Fucose-alpha(1-2)-galactose [Fuc alpha(1-2)Gal] sugars have been implicated in the molecular mechanisms that underlie neuronal development, learning, and memory, However, an understanding of their precise roles has been hampered by a lack of information regarding Fuc alpha(1-2)Gal glycoproteins. Here, we report the first proteomic studies of this plasticity-relevant epitope. We identify five classes of putative Fuc alpha(1-2)Gal glycoproteins: cell adhesion molecules, ion channels and solute carriers/transporters, ATP-binding proteins, synaptic vesicle-associated proteins, and mitochondrial proteins. In addition, we show that Fuc alpha(1-2)Gal glycoproteins are enriched in the developing mouse olfactory bulb (OB) and exhibit a distinct spatiotemporal expression that is consistent with the presence of a glycocode to help direct olfactory sensory neuron (OSN) axonal pathfinding. We find that expression of Fuc alpha(1-2)Gal sugars in the OB is regulated by the alpha(1-2)fucosyltransferase FUT1. FUT1-deficient mice exhibit developmental defects, including fewer and smaller glomeruli and a thinner olfactory nerve layer, suggesting that fucosylation contributes to OB development. Our findings significantly expand the number of Fuc alpha(1-2)Gal glycoproteins and provide new insights into the molecular mechanisms by which fucosyl sugars contribute to neuronal processes.