Lipid Raft is required for PSGL-1 ligation induced HL-60 cell adhesion on ICAM-1.

ABSTRACT: P-selectin glycoprotein ligand-1 (PSGL-1) and integrins are adhesion molecules that play critical roles in host defense and innate immunity. PSGL-1 mediates leukocyte rolling and primes leukocytes for integrin-mediated adhesion. However, the mechanism that PSGL-1 as a rolling receptor in regulating integrin activation has not been well characterized. Here, we investigate the function of lipid raft in regulating PSGL-1 induced ?2 integrin-mediated HL-60 cells adhesion. PSGL-1 ligation with antibody enhances the ?2 integrin activation and ?2 integrin-dependent adhesion to ICAM-1. Importantly, with the treatment of methyl-?-cyclodextrin (M?CD), we confirm the role of lipid raft in regulating the activation of ?2 integrin. Furthermore, we find that the protein level of PSGL-1 decreased in raft fractions in M?CD treated cells. PSGL-1 ligation induces the recruitment of spleen tyrosine kinase (Syk), a tyrosine kinase and Vav1 (the pivotal downstream effector of Syk signaling pathway involved in cytoskeleton regulation) to lipid raft. Inhibition of Syk activity with pharmacologic inhibitor strongly reduces HL-60 cells adhesion, implicating Syk is crucial for PSGL-1 mediated ?2 integrin activation. Taken together, we report that ligation of PSGL-1 on HL-60 cells activates ?2 integrin, for which lipid raft integrity and Syk activation are responsible. These ?ndings have shed new light on the mechanisms that connect leukocyte initial rolling with subsequent adhesion.

SUBMITTER: Xu T 

PROVIDER: S-EPMC3849276 | biostudies-literature | 2013

REPOSITORIES: biostudies-literature