Evidence for the requirement of ITAM domains but not SLP-76/Gads interaction for integrin signaling in hematopoietic cells.
Syk tyrosine kinase and Src homology 2 (SH2) domain-containing leukocyte-specific phosphoprotein of 76 kDa (SLP-76) are signaling mediators activated downstream of immunoreceptor tyrosine-based activation motif (ITAM)-containing immunoreceptors and integrins. While the signaling cascades descending from integrins are similar to immunoreceptors, the mechanism of Syk activation and SLP-76 recruitment remains unclear. We used an in vivo structure-function approach to study the requirements for the domains of Syk and SLP-76 in immunoreceptor and integrin signaling. We found that both SH2 domains and the kinase domain of Syk are required for immunoreceptor-dependent signaling and cellular response via integrins. While the Gads-binding domain of SLP-76 is needed for immunoreceptor signaling, it appears dispensable for integrin signaling. Syk and SLP-76 also are required for initiating and/or maintaining separation between the blood and lymphatic vasculature. Therefore, we correlated the signaling requirement of the various domains of Syk and SLP-76 to their requirement in regulating vascular separation. Our data suggest ITAMs are required in Syk-dependent integrin signaling, demonstrate the separation of the structural features of SLP-76 to selectively support immunoreceptor versus integrin signaling, and provide evidence that the essential domains of SLP-76 for ITAM signals are those which most efficiently support separation between lymphatic and blood vessels.
Abtahian
Farhad
F
Signal Transduction Program, Abramson Family Cancer Research Institute, University of Pennsylvania, 421 Curie Blvd., Philadelphia, PA 19104, USA.
Bezman
Natalie
N
Clemens
Regina
R
Sebzda
Eric
E
Cheng
Lan
L
Shattil
Sanford J
SJ
Kahn
Mark L
ML
Koretzky
Gary A
GA
D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism; D000818:Animals; D001808:Blood Vessels / Q000166:cytology / Q000473:pathology / Q000502:physiology; D016466:CHO Cells; D002462:Cell Membrane / Q000378:metabolism; D002478:Cells, Cultured; D006224:Cricetinae; D006413:Hematopoietic System / Q000166:cytology* / Q000378:metabolism*; D006801:Humans; D016023:Integrins / Q000378:metabolism*; D047908:Intracellular Signaling Peptides and Proteins / Q000172:deficiency; D051379:Mice; D009154:Mutation / Q000235:genetics; D010750:Phosphoproteins / Q000172:deficiency / Q000378:metabolism*; D019000:Phosphotyrosine / Q000378:metabolism; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011505:Protein-Tyrosine Kinases / Q000172:deficiency; D011971:Receptors, Immunologic / Q000378:metabolism; D015398:Signal Transduction; D000072377:Syk Kinase; D018909:src Homology Domains
D048868:Adaptor Proteins, Signal Transducing; C409587:GRAP2 protein, human; D016023:Integrins; D047908:Intracellular Signaling Peptides and Proteins; D010750:Phosphoproteins; D011971:Receptors, Immunologic; C092947:SLP-76 signal Transducing adaptor proteins; D019000:Phosphotyrosine; D011505:Protein-Tyrosine Kinases; C000606896:SYK protein, human; D000072377:Syk Kinase; C000606897:Syk protein, mouse