A role for Bruton's tyrosine kinase (Btk) in platelet activation by collagen
| Autor: | J. Bolen, L.S. Quek, Steve P. Watson |
|---|---|
| Rok vydání: | 1998 |
| Předmět: |
Blood Platelets
Syk General Biochemistry Genetics and Molecular Biology Receptor tyrosine kinase Collagen receptor chemistry.chemical_compound Agammaglobulinemia hemic and lymphatic diseases Agammaglobulinaemia Tyrosine Kinase Bruton's tyrosine kinase Humans Platelet activation Phosphorylation biology Agricultural and Biological Sciences(all) Phospholipase C gamma Biochemistry Genetics and Molecular Biology(all) Tyrosine phosphorylation Protein-Tyrosine Kinases Platelet Activation Cell biology Enzyme Activation Isoenzymes chemistry Type C Phospholipases biology.protein Cancer research Tyrosine Collagen GPVI General Agricultural and Biological Sciences Tyrosine kinase |
| Zdroj: | Current Biology. 8(20):1137-S1 |
| ISSN: | 0960-9822 |
| DOI: | 10.1016/s0960-9822(98)70471-3 |
| Popis: | Bruton's tyrosine kinase (Btk) is essential for normal B-cell receptor signalling. The lack of expression of functional Btk in humans leads to the B-cell deficiency X-linked agammaglobulinaemia (XLA). We report here that Btk is also important for signalling via the collagen receptor glycoprotein VI (GPVI) in platelets. GPVI is coupled to the Fc receptor gamma chain (FcRgamma). The FcRgamma-chain contains a consensus sequence known as the immune-receptor tyrosine-based activation motif (ITAM). Tyrosine phosphorylation of the ITAM upon GPVI stimulation is the initial step in the regulation of phospholipase C gamma2 (PLCgamma2) isoforms via the tyrosine kinase p72(Syk) (Syk) in platelets. Here we show that collagen and a collagen-related peptide (CRP), which binds to GPVI but does not bind to the integrin alpha2beta1, induced Btk tyrosine phosphorylation in platelets. Aggregation, dense granule secretion and calcium mobilisation were significantly diminished but not completely abolished in platelets from XLA patients in response to collagen and CRP. These effects were associated with a reduction in tyrosine phosphorylation of PLCgamma2. In contrast, aggregation and secretion stimulated by thrombin in Btk-deficient platelets were not significantly altered. Our results demonstrate that Btk is important for collagen signalling via GPVI, but is not essential for thrombin-mediated platelet activation. |
| Databáze: | OpenAIRE |
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