The N-terminal SH2 domain of the tyrosine phosphatase, SHP-2, is essential for Jak2-dependent signaling via the angiotensin II type AT1 receptor

Previous work has suggested that the protein tyrosine phosphatase, SHP-2, may act to facilitate angiotensin II (Ang II)-mediated, Jak2-dependent signaling. However, the mechanisms by which this occurs are not known. Here, Ang II-mediated, Jak2-dependent signaling was analyzed in a fibroblast cell line lacking the N-terminal, SH2 domain of SHP-2 (SHP-2Δ46-110). While the SHP-2Δ46-110 cells were capable of activating Jak2 tyrosine kinase, they were unable to facilitate AT1 receptor/Jak2 co-association, STAT activation and subsequent Ang II-mediated gene transcription when compared to wild type control cells. These data therefore suggested that the N-terminal SH2 domain of SHP-2 was acting to recruit Jak2 to the AT1 receptor signaling complex. We found that the N-terminal SH2 domain of SHP-2 binds Jak2 predominantly, but not exclusively at tyrosine 201. Mass spectrometry analysis confirmed that this tyrosine residue is in fact phosphorylated. When this tyrosine was converted to phenylalanine, the ability of Jak2 to activate subsequent downstream signaling events was reduced. In summary, we have identified a novel site of Jak2 tyrosine autophosphorylation; namely, tyrosine 201. Our data suggest that the N-terminal SH2 domain of SHP-2 binds this amino acid residue. The functional consequence of this interaction is to recruit Jak2 to the AT1 receptor signaling complex and in turn promote downstream Jak2-dependent signaling.