Core Fucosylation of N-linked Glycans as a Regulator of CD8+ T cell Activation and Function

PROJECT SUMMARY/ABSTRACT Post-translational carbohydrate modifications are important mediators of several cellular processes including protein turnover, cell adhesion, signal transduction, modulating receptor affinity for ligand, and apoptosis.

However, in contrast to the well-established genetic code where biological information in DNA results in the generation of RNA which is then translated into protein, no such paradigm exists for predicting the vast array of possible post-translational glycosylation structures that could potentially decorate a given gene product.

One such glycan modification has been defined as ?core fucosylation? of N-linked glycans, which occurs when L- fucose is covalently linked via an a1,6 linkage to the initial N-acetylglucosamine that originates from the asparagine amino acid.

Although core fucosylation of N-linked glycans is necessary for normal development and physiology, whether these N-linked glycans are critical regulators of T cell activation and/or function is largely unknown.

Here, we show that CD8+ T cells are decorated with N-linked glycans containing a core fucose and that the abundance of this specialized glycan modification increases significantly following their activation both in vitro and in vivo.

Fucosyltransferase 8 (Fut8; a1,6-fucosyltransferase) is the only glycosyltransferase enzyme in the mammalian genome that can facilitate core fucosylation of N-linked glycans and we have now generated a novel Fut8 conditional knockout mouse that allows us to eliminate expression of Fut8 in a cell-specific manner.

Using a T cell-specific cre-recombinase, our preliminary data show that expression of Fut8 and the subsequent generation of core fucosylated N-linked glycans is essential to maintain antigen-specific CD8+ T cell function (e.g. production of cytokines) during chronic viral infection.

Here, we propose to use our new reagent to 1) identify the landscape of proteins expressed by activated CD8+ T cells that become decorated with core fucosylated N- linked glycans using a mass spectrometry approach and 2) to subsequently determine the biological relevance of this form of post-translational glycosylation in maintaining the function of antigen-specific CD8+ T cells during chronic viral infection.