Requirements of SLP76 tyrosines in ITAM and integrin receptor signaling and in platelet function in vivo.
Src homology 2 domain-containing leukocyte phosphoprotein of 76 kD (SLP76), an adaptor that plays a critical role in platelet activation in vitro, contains three N-terminal tyrosine residues that are essential for its function. We demonstrate that mice containing complementary tyrosine to phenylalanine mutations in Y145 (Y145F) and Y112 and Y128 (Y112/128F) differentially regulate integrin and collagen receptor signaling. We show that mutation of Y145 leads to severe impairment of glycoprotein VI (GPVI)-mediated responses while preserving outside-in integrin signaling. Platelets from Y112/128F mice, although having mild defects in GPVI signaling, exhibit defective actin reorganization after GPVI or alpha IIb beta 3 engagement. The in vivo consequences of these signaling defects correlate with the mild protection from thrombosis seen in Y112/128F mice and the near complete protection observed in Y145F mice. Using genetic complementation, we further demonstrate that all three phosphorylatable tyrosines are required within the same SLP76 molecule to support platelet activation by GPVI.
Bezman
Natalie A
NA
Leonard and Madlyn Abramson Family Cancer Research Institute, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA.
Lian
Lurong
L
Abrams
Charles S
CS
Brass
Lawrence F
LF
Kahn
Mark L
ML
Jordan
Martha S
MS
Koretzky
Gary A
GA
D048868:Adaptor Proteins, Signal Transducing / Q000737:chemistry* / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D000077329:Agammaglobulinaemia Tyrosine Kinase; D019943:Amino Acid Substitution; D000818:Animals; D001792:Blood Platelets / Q000502:physiology*; D018955:CD36 Antigens / Q000502:physiology; D005260:Female; D005816:Genetic Complementation Test; D016023:Integrins / Q000502:physiology*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008817:Mice, Mutant Strains; D016297:Mutagenesis, Site-Directed; D051966:Phospholipase C gamma / Q000097:blood; D010750:Phosphoproteins / Q000737:chemistry* / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D010766:Phosphorylation; D010974:Platelet Aggregation / Q000235:genetics / Q000502:physiology; D019039:Platelet Glycoprotein GPIIb-IIIa Complex / Q000502:physiology; D011505:Protein-Tyrosine Kinases / Q000097:blood; D015398:Signal Transduction; D013927:Thrombosis / Q000097:blood / Q000209:etiology / Q000235:genetics; D014443:Tyrosine / Q000737:chemistry
D048868:Adaptor Proteins, Signal Transducing; D018955:CD36 Antigens; D016023:Integrins; D010750:Phosphoproteins; D019039:Platelet Glycoprotein GPIIb-IIIa Complex; C092947:SLP-76 signal Transducing adaptor proteins; D014443:Tyrosine; D011505:Protein-Tyrosine Kinases; D000077329:Agammaglobulinaemia Tyrosine Kinase; D051966:Phospholipase C gamma