Severe impairment of leukocyte recruitment into inflamed tissue of ppGalNAcT1-deficient mice (94.1)

Abstract

Abstract P-selectin glycoprotein ligand-1 (PSGL-1) plays an important role in leukocyte recruitment. Its binding affinity to selectins is modulated by posttranslational modifications. The polypeptide N-acetylgalactosamine transferase-1 (ppGalNAcT1) initiates core-type protein O-glycosylation. To address whether the glycosylation of PSGL-1 by ppGalNAcT1 is important for leukocyte recruitment, we investigated leukocyte rolling and velocity in untreated and TNF-α treated cremaster muscles and autoperfused flow chambers comparing ppGalNAcT1-/-(Galnt1-/-) with WT mice. In untreated and TNF-α treated Galnt1-/- mice, leukocyte rolling was significantly reduced with markedly increased rolling velocity compared to control mice. Flow chamber experiments showed that Galnt1-/-- and WT-neutrophils had the same rolling velocity on E-selectin, but the rolling velocity of Galnt1-/--neutrophils on E-selectin/ICAM-1 was significantly elevated, suggesting that E-selectin-dependent neutrophil activation may be defective. Thioglycollate-induced peritonitis experiments with chimeric mice revealed that hematopoietic ppGalNAcT1 is important for leukocyte recruitment. These data show that the loss of ppGalNAcT1 led to reduced leukocyte rolling and recruitment and increased rolling velocity, suggesting a predominant role of ppGalNAcT1 in attaching functionally relevant O-linked glycans to PSGL-1.