Regulation of c-Fes tyrosine kinase and biological activities by N-terminal coiled-coil oligomerization domains.
The cytoplasmic protein-tyrosine kinase Fes has been implicated in cytokine signal transduction, hematopoiesis, and embryonic development. Previous work from our laboratory has shown that active Fes exists as a large oligomeric complex in vitro. However, when Fes is expressed in mammalian cells, its kinase activity is tightly repressed. The Fes unique N-terminal sequence has two regions with strong homology to coiled-coil-forming domains often found in oligomeric proteins. Here we show that disruption or deletion of the first coiled-coil domain upregulates Fes tyrosine kinase and transforming activities in Rat-2 fibroblasts and enhances Fes differentiation-inducing activity in myeloid leukemia cells. Conversely, expression of a Fes truncation mutant consisting only of the unique N-terminal domain interfered with Rat-2 fibroblast transformation by an activated Fes mutant, suggesting that oligomerization is essential for Fes activation in vivo. Coexpression with the Fes N-terminal region did not affect the transforming activity of v-Src in Rat-2 cells, arguing against a nonspecific suppressive effect. Taken together, these findings suggest a model in which Fes activation may involve coiled-coil-mediated interconversion of monomeric and oligomeric forms of the kinase. Mutation of the first coiled-coil domain may activate Fes by disturbing intramolecular coiled-coil interaction, allowing for oligomerization via the second coiled-coil domain. Deletion of the second coiled-coil domain blocks fibroblast transformation by an activated form of c-Fes, consistent with this model. These results provide the first evidence for regulation of a nonreceptor protein-tyrosine kinase by coiled-coil domains.
Cheng
H
H
Eppley Institute for Research in Cancer, University of Nebraska Medical Center, Omaha, Nebraska.
Rogers
J A
JA
Dunham
N A
NA
Smithgall
T E
TE
D000818:Animals; D001665:Binding Sites; D002460:Cell Line; D002461:Cell Line, Transformed; D002471:Cell Transformation, Neoplastic; D005347:Fibroblasts / Q000166:cytology; D006801:Humans; D020014:K562 Cells; D016296:Mutagenesis; D015688:Oncogene Protein pp60(v-src) / Q000235:genetics; D017434:Protein Structure, Tertiary; D011505:Protein-Tyrosine Kinases / Q000235:genetics / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism*; D051578:Proto-Oncogene Proteins c-fes; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D015854:Up-Regulation
D011518:Proto-Oncogene Proteins; D011993:Recombinant Fusion Proteins; D011505:Protein-Tyrosine Kinases; C496645:FES protein, human; D015688:Oncogene Protein pp60(v-src); D051578:Proto-Oncogene Proteins c-fes