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B cell antigen receptor signal strength and peripheral B cell development are regulated by a 9- O -acetyl sialic acid esterase

2008; Rockefeller University Press; Volume: 206; Issue: 1 Linguagem: Inglês

10.1084/jem.20081399

1540-9538

Annaiah Cariappa, Hiromu Takematsu, Haoyuan Liu, Sandra Diaz, K Haider, Cristian Boboilă, Geetika Kalloo, Michelle Connole, Hai Ning Shi, Nissi Varki, Ajit Varki, Shiv Pillai,

Carbohydrate Chemistry and Synthesis

We show that the enzymatic acetylation and deacetylation of a cell surface carbohydrate controls B cell development, signaling, and immunological tolerance. Mice with a mutation in sialate:O-acetyl esterase, an enzyme that specifically removes acetyl moieties from the 9-OH position of α2–6-linked sialic acid, exhibit enhanced B cell receptor (BCR) activation, defects in peripheral B cell development, and spontaneously develop antichromatin autoantibodies and glomerular immune complex deposits. The 9-O-acetylation state of sialic acid regulates the function of CD22, a Siglec that functions in vivo as an inhibitor of BCR signaling. These results describe a novel catalytic regulator of B cell signaling and underscore the crucial role of inhibitory signaling in the maintenance of immunological tolerance in the B lineage.