Abstract
Multiple studies have demonstrated an important role for the Src homology 2-containing tyrosine phosphatase 2 (SHP-2) in receptor tyrosine kinase-regulated cell proliferation and differentiation. Recent studies have identified potential SHP-2 substrates which mediate these effects. SHP-2 also is implicated in several cytokine receptor signaling pathways and in Bcr-Abl transformation. However, its precise role and targets in normal and abnormal hematopoietic cells remain to be determined. We identified two novel tyrosyl-phosphorylated proteins associated with SHP-2 in hematopoietic cells. The first, a 97-kDa cytosolic protein (p97), associates inducibly with SHP-2 upon cytokine stimulation and constitutively in Bcr-Abl-transformed cells. In contrast, p135, a 135-kDa transmembrane glycoprotein, forms a distinct complex with SHP-2, independent of cytokine stimulation or Bcr-Abl transformation. Far Western analysis reveals that SHP-2, via its Src homology 2 domains, can interact directly with either protein. In vitro dephosphorylation experiments, as well as transient transfection studies using wild type and mutant SHP-2 constructs, suggest that p97 and p135 also are SHP-2 substrates. Our results indicate that SHP-2 forms at least two separate complexes in hematopoietic cells and point to new potential SHP-2 targets.
Highlights
Many signaling pathways are initiated and/or regulated by tyrosyl phosphorylation, controlled by protein-tyrosine kinases (PTKs)1 and protein-tyrosine phosphatases (PTPs)
We examined SH2containing PTPs (SHPs)-2 phosphorylation and protein-protein interactions in response to IL3 stimulation by anti-Src homology 2-containing tyrosine phosphatase 2 (SHP-2) immunoprecipitations followed by anti-phosphotyrosine immunoblotting (Fig. 1A)
The other, p135, is a transmembrane glycoprotein that associates constitutively with SHP-2, independent of cytokine stimulation or Bcr-Abl transformation. These proteins appear to interact with the SHP-2 SH2 domains and to form distinct complexes with SHP-2
Summary
Many signaling pathways are initiated and/or regulated by tyrosyl phosphorylation, controlled by protein-tyrosine kinases (PTKs)1 and protein-tyrosine phosphatases (PTPs). The first, a 97-kDa cytosolic protein (p97), associates inducibly with SHP-2 upon cytokine stimulation and constitutively in Bcr-Abl-transformed cells. To further our understanding of SHP-2’s functions in hematopoietic cells, we searched for tyrosyl-phosphorylated proteins that associate with SHP-2 in response to cytokine stimulation and upon Bcr-Abl transformation.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.