{Reference Type}: Journal Article
{Title}: A systematic study of modulation of ADAM-mediated ectodomain shedding by site-specific O-glycosylation.
{Author}: Goth CK;Halim A;Khetarpal SA;Rader DJ;Clausen H;Schjoldager KT;
{Journal}: Proc Natl Acad Sci U S A
{Volume}: 112
{Issue}: 47
{Year}: Nov 2015 24
{Factor}: 12.779
{DOI}: 10.1073/pnas.1511175112
{Abstract}: Regulated shedding of the ectodomain of cell membrane proteins by proteases is a common process that releases the extracellular domain from the cell and activates cell signaling. Ectodomain shedding occurs in the immediate extracellular juxtamembrane region, which is also where O-glycosylation is often found and examples of crosstalk between shedding and O-glycosylation have been reported. Here, we systematically investigated the potential of site-specific O-glycosylation mediated by distinct polypeptide GalNAc-transferase (GalNAc-T) isoforms to coregulate ectodomain shedding mediated by the A Disintegrin And Metalloproteinase (ADAM) subfamily of proteases and in particular ADAM17. We analyzed 25 membrane proteins that are known to undergo ADAM17 shedding and where the processing sites included Ser/Thr residues within ± 4 residues that could represent O-glycosites. We used in vitro GalNAc-T enzyme and ADAM cleavage assays to demonstrate that shedding of at least 12 of these proteins are potentially coregulated by O-glycosylation. Using TNF-α as an example, we confirmed that shedding mediated by ADAM17 is coregulated by O-glycosylation controlled by the GalNAc-T2 isoform both ex vivo in isogenic cell models and in vivo in mouse Galnt2 knockouts. The study provides compelling evidence for a wider role of site-specific O-glycosylation in ectodomain shedding.