Unique signal transduction of Eyk: constitutive stimulation of the JAK-STAT pathway by an oncogenic receptor-type tyrosine kinase.
The proto-oncogene c-eyk, the cellular counterpart of a transforming oncogene, v-eyk, encodes a receptor protein tyrosine kinase with a distinctive extracellular region. We now demonstrate that c-Eyk can be constitutively activated through dimerization, and that the active Eyk displays a unique signaling pattern. When the kinase domain of c-Eyk was fused to the extracellular and transmembrane domains of CD8, the resulting chimera showed elevated kinase activity and caused cellular transformation. We found that the activated Eyk kinases, both v- and c-Eyk, constitutively stimulate the JAK-STAT pathway, while exerting little effect on other signaling routes such as the Ras-MAP kinase and the JNK pathways. The activated Eyk kinases specifically stimulate tyrosine phosphorylation of STAT1, STAT3 and JAK1. These downstream molecules also co-immunoprecipitate with the constitutively dimerized form of Eyk. The Eyk kinase activity is required for STAT1 stimulation. We found that the activation of STAT1 but not STAT3 correlates well with cellular transformation. In constitutively stimulating the JAK-STAT pathway, particularly STAT1, Eyk is unique in its downstream signaling and may be dependent on this pathway for cellular transformation.
Laboratory of Molecular Oncology, The Rockefeller University, New York, NY 10021-6399, USA.
C
C
Zong
R
R
Yan
A
A
August
J E
JE
Darnell
H
H
Hanafusa
D000818:Animals; D001704:Biopolymers; D019556:COS Cells; D002461:Cell Line, Transformed; D002642:Chick Embryo; D004268:DNA-Binding Proteins / Q000378:metabolism*; D053613:Janus Kinase 1; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D000090063:Proto-Oncogene Mas; D051381:Rats; D020794:Receptor Protein-Tyrosine Kinases / Q000235:genetics / Q000378:metabolism*; D011956:Receptors, Cell Surface / Q000235:genetics / Q000378:metabolism*; D050794:STAT1 Transcription Factor; D050796:STAT3 Transcription Factor; D015398:Signal Transduction; D015534:Trans-Activators / Q000378:metabolism*; D014162:Transfection
D001704:Biopolymers; D004268:DNA-Binding Proteins; C000715470:MAS1 protein, human; D000090063:Proto-Oncogene Mas; D011956:Receptors, Cell Surface; D050794:STAT1 Transcription Factor; D050796:STAT3 Transcription Factor; C494081:Stat1 protein, rat; C494088:Stat3 protein, rat; D015534:Trans-Activators; D011505:Protein-Tyrosine Kinases; C080836:RYK protein, human; D020794:Receptor Protein-Tyrosine Kinases; C507904:JAK1 protein, human; C507906:Jak1 protein, rat; D053613:Janus Kinase 1