Peptide LSARLAF induces integrin ?3 dependent outside-in signaling in platelets.

ABSTRACT: Peptide LSARLAF (LSA) can bind and activate integrin ?IIb?3 in the absence of 'inside-out' signal. The active ?IIb?3 mediates 'outside-in' signaling that elicits platelet aggregation, granule secretion and TxA2 production. Here we identify the membrane glycoproteins which mediate LSA-induced platelet activation other than ?IIb?3, and determine the roles of Src, PLC?2, FcR?-chain, and SLP-76 in LSA-induced platelet activation.Ligand-receptor binding assay was performed to study the effect of peptide LSA or its control peptide FRALASL (FRA) on integrins binding to their ligands. Spreading of CHO cells expressing ?IIb?3 or ?V?3 on immobilized fibrinogen was measured in the presence of LSA or FRA. Washed ?3, Src, FcR?-chain, LAT and SLP-76 deficient platelets aggregation and secretion were tested in response to LSA.Ligand-receptor binding assay indicated that LSA promoted the binding of multiple ligands to ?IIb?3 or ?V?3. LSA also enhanced CHO cells with ?IIb?3 or ?V?3 expression spreading on immobilized fibrinogen. ?3 deficient platelets failed to aggregate and secrete in response to LSA. The phosphorylation of PLC?2 and Syk was also ?3 dependent. Src, FcR?-chain, LAT and SLP-76 deficient platelets did not aggregate, secrete ATP or produce TxA2 in response to LSA.LSA-induced platelet activation is ?3 dependent, and signaling molecules Src, FcR?-chain, SLP-76 and LAT play crucial roles in LSA-induced ?3 mediated signaling.

SUBMITTER: Niu H 

PROVIDER: S-EPMC3393848 | biostudies-literature | 2012 Aug

REPOSITORIES: biostudies-literature