1997 Articles
The Thrombopoietin Receptor Can Mediate Proliferation Without Activation of the Jak-STAT Pathway
Cytokine receptors of the hematopoietic receptor superfamily lack intrinsic tyrosine kinase domains for the intracellular transmission of their signals. Instead all members of this family associate with Jak family nonreceptor tyrosine kinases. Upon ligand stimulation of the receptors, Jaks are activated to phosphorylate target substrates. These include STAT (signal transducers and activators of transcription) proteins, which after phosphorylation translocate to the nucleus and modulate gene expression. The exact role of the Jak-STAT pathway in conveying growth and differentiation signals remains unclear. Here we describe a deletion mutant of the thrombopoietin receptor (c-mpl) that has completely lost the capacity to activate Jaks and STATs but retains its ability to induce proliferation. This mutant still mediates TPO-induced phosphorylation of Shc, Vav, mitogen-activated protein kinase (MAPK) and Raf-1 as well as induction of c-fos and c-myc, although at somewhat reduced levels. Furthermore, we show that both wild-type and mutant receptors activate phosphatidylinositol (PI) 3-kinase upon thrombopoietin stimulation and that thrombopoietin-induced proliferation is inhibited in the presence of the PI 3-kinase inhibitor wortmannin. These results demonstrate that the Jak-STAT pathway is dispensable for the generation of mitogenic signals by a cytokine receptor.
Subjects
Files
- J_Exp_Med-1997-Dorsch-1947-55.pdf application/pdf 333 KB Download File
Also Published In
- Title
- Journal of Experimental Medicine
- DOI
- https://doi.org/10.1084/jem.186.12.1947
More About This Work
- Academic Units
- Pathology and Cell Biology
- Biochemistry and Molecular Biophysics
- Cellular, Molecular, Structural, and Genetic Studies
- Medicine
- Microbiology and Immunology
- Publisher
- Rockefeller University Press
- Published Here
- August 19, 2014