title: Interaction between lck and syk family tyrosine kinases in Fc gamma receptor-initiated activation of natural killer cells.
abstract: Ligation of the Fc gamma R on natural killer (NK) cells results in the tyrosine phosphorylation of multiple substrates critical for intracellular signaling and activation of NK cell effector functions. However, it remains unclear which nonreceptor protein-tyrosine kinases (PTK) participate in this process. In this report we demonstrate that Fc gamma R ligation induced the tyrosine phosphorylation and increased the catalytic activities of both syk family PTKs, ZAP-70, and syk. The phosphorylation of ZAP-70 and syk was enhanced markedly by overexpression of wild-type lck but not by a kinase-inactive mutant, suggesting that early Fc gamma R-initiated activation of lck results in the subsequent regulation of syk family PTKs. The regulatory interplay between src and syk family PTKs was emphasized further by the observation that lck overexpression enhanced the association of ZAP-70 with the zeta chain of the Fc gamma R complex. Additional analyses indicated that lck induced the subsequent tyrosine phosphorylation of phospholipase C (PLC)-gamma 2. Interestingly, the regulatory effects of lck on ZAP-70, syk, and PLC-gamma 2 could not be replaced by overexpression of either fyn or src, demonstrating a selective role for lck in effectively coupling Fc gamma R stimulation to critical downstream signaling events. Taken together, our results suggest not only that Fc gamma R stimulation on NK cells is coupled to the intracellular activation of both ZAP-70 and syk, but that the src family member, lck, can selectively regulate this tyrosine kinase cascade.
authors.affiliation: Department of Immunology, Mayo Clinic and Foundation, Rochester, Minnesota 55905, USA.
authors.forename: A T
authors.initials: AT
authors.lastname: Ting
authors.forename: C J
authors.initials: CJ
authors.lastname: Dick
authors.forename: R A
authors.initials: RA
authors.lastname: Schoon
authors.forename: L M
authors.initials: LM
authors.lastname: Karnitz
authors.forename: R T
authors.initials: RT
authors.lastname: Abraham
authors.forename: P J
authors.initials: PJ
authors.lastname: Leibson
mesh_terms: D002460:Cell Line; D004792:Enzyme Precursors / Q000378:metabolism; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D007527:Isoenzymes / Q000378:metabolism; D007694:Killer Cells, Natural / Q000201:enzymology / Q000378:metabolism* / Q000821:virology; D008213:Lymphocyte Activation; D019860:Lymphocyte Specific Protein Tyrosine Kinase p56(lck); D051966:Phospholipase C gamma; D010766:Phosphorylation; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism; D051076:Proto-Oncogene Proteins c-fyn; D016392:Proto-Oncogene Proteins pp60(c-src) / Q000235:genetics / Q000378:metabolism; D017452:Receptors, IgG / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D015398:Signal Transduction; D000072377:Syk Kinase; D010738:Type C Phospholipases / Q000378:metabolism; D014616:Vaccinia virus / Q000235:genetics
chemical_list: D004792:Enzyme Precursors; D047908:Intracellular Signaling Peptides and Proteins; D007527:Isoenzymes; D011518:Proto-Oncogene Proteins; D017452:Receptors, IgG; D011994:Recombinant Proteins; D011505:Protein-Tyrosine Kinases; C494957:FYN protein, human; D019860:Lymphocyte Specific Protein Tyrosine Kinase p56(lck); D051076:Proto-Oncogene Proteins c-fyn; D016392:Proto-Oncogene Proteins pp60(c-src); C000606896:SYK protein, human; D000072377:Syk Kinase; D010738:Type C Phospholipases; D051966:Phospholipase C gamma