title: Syk-dependent phosphorylation of CLEC-2: a novel mechanism of hem-immunoreceptor tyrosine-based activation motif signaling.
abstract: The C-type lectin-like receptor CLEC-2 signals via phosphorylation of a single cytoplasmic YXXL sequence known as a hem-immunoreceptor tyrosine-based activation motif (hemITAM). In this study, we show that phosphorylation of CLEC-2 by the snake toxin rhodocytin is abolished in the absence of the tyrosine kinase Syk but is not altered in the absence of the major platelet Src family kinases, Fyn, Lyn, and Src, or the tyrosine phosphatase CD148, which regulates the basal activity of Src family kinases. Further, phosphorylation of CLEC-2 by rhodocytin is not altered in the presence of the Src family kinase inhibitor PP2, even though PLCγ2 phosphorylation and platelet activation are abolished. A similar dependence of phosphorylation of CLEC-2 on Syk is also seen in response to stimulation by an IgG mAb to CLEC-2, although interestingly CLEC-2 phosphorylation is also reduced in the absence of Lyn. These results provide the first definitive evidence that Syk mediates phosphorylation of the CLEC-2 hemITAM receptor with Src family kinases playing a critical role further downstream through the regulation of Syk and other effector proteins, providing a new paradigm in signaling by YXXL-containing receptors.
authors.affiliation: Centre for Cardiovascular Sciences, Institute of Biomedical Research, College of Medical and Dental Sciences, University of Birmingham, Birmingham B15 2TT, United Kingdom.
authors.forename: Sonia
authors.initials: S
authors.lastname: Séverin
authors.forename: Alice Y
authors.initials: AY
authors.lastname: Pollitt
authors.forename: Leyre
authors.initials: L
authors.lastname: Navarro-Nuñez
authors.forename: Craig A
authors.initials: CA
authors.lastname: Nash
authors.forename: Diego
authors.initials: D
authors.lastname: Mourão-Sá
authors.forename: Johannes A
authors.initials: JA
authors.lastname: Eble
authors.forename: Yotis A
authors.initials: YA
authors.lastname: Senis
authors.forename: Steve P
authors.initials: SP
authors.lastname: Watson
mesh_terms: D020816:Amino Acid Motifs; D000818:Animals; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism*; D037181:Lectins, C-Type / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D051966:Phospholipase C gamma / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects / Q000502:physiology; D011505:Protein-Tyrosine Kinases / Q000235:genetics / Q000378:metabolism*; D011743:Pyrimidines / Q000494:pharmacology; D054631:Receptor-Like Protein Tyrosine Phosphatases, Class 3 / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D000072377:Syk Kinase; D014757:Viper Venoms / Q000494:pharmacology
chemical_list: C412373:AG 1879; C529518:CLEC-2 protein, mouse; D047908:Intracellular Signaling Peptides and Proteins; D037181:Lectins, C-Type; D011743:Pyrimidines; D014757:Viper Venoms; C112292:rhodocytin protein, Calloselasma rhodostoma; D011505:Protein-Tyrosine Kinases; D000072377:Syk Kinase; C000606897:Syk protein, mouse; C098066:Ptprj protein, mouse; D054631:Receptor-Like Protein Tyrosine Phosphatases, Class 3; D051966:Phospholipase C gamma