Article

High-throughput phosphotyrosine profiling using SH2 domains.

Raymond and Beverly Sackler Laboratory of Genetics and Molecular Medicine, Department of Genetics and Developmental Biology, University of Connecticut Health Center, Farmington, CT 06030, USA.
Molecular Cell (Impact Factor: 14.46). 07/2007; 26(6):899-915. DOI: 10.1016/j.molcel.2007.05.031
Source: PubMed

ABSTRACT Protein tyrosine phosphorylation controls many aspects of signaling in multicellular organisms. One of the major consequences of tyrosine phosphorylation is the creation of binding sites for proteins containing Src homology 2 (SH2) domains. To profile the global tyrosine phosphorylation state of the cell, we have developed proteomic binding assays encompassing nearly the full complement of human SH2 domains. Here we provide a global view of SH2 domain binding to cellular proteins based on large-scale far-western analyses. We also use reverse-phase protein arrays to generate comprehensive, quantitative SH2 binding profiles for phosphopeptides, recombinant proteins, and entire proteomes. As an example, we profiled the adhesion-dependent SH2 binding interactions in fibroblasts and identified specific focal adhesion complex proteins whose tyrosine phosphorylation and binding to SH2 domains are modulated by adhesion. These results demonstrate that high-throughput comprehensive SH2 profiling provides valuable mechanistic insights into tyrosine kinase signaling pathways.

1 Follower
 · 
449 Views
  • [Show abstract] [Hide abstract]
    ABSTRACT: Purpose: Irreversible EGFR-tyrosine kinase inhibitors (TKIs) are thought to be one strategy to overcome EGFR-TKI resistance induced by T790M gate-keeper mutations in non-small cell lung cancer (NSCLC), yet they display limited clinical efficacy. We hypothesized that additional resistance mechanisms that cooperate with T790M could be identified by profiling tyrosine phosphorylation in NSCLC cells with acquired resistance to reversible EGFR-TKI and harboring T790M. Experimental Design: We profiled PC9 cells with TKI-sensitive EGFR mutation and paired EGFR-TKI-resistant PC9GR (gefitinib-resistant) cells with T790M using immunoaffinity purification of tyrosine-phosphorylated peptides and mass-spectrometry-based identification/quantification. Profiles of erlotinib perturbations were examined. Results: We observed a large fraction of the tyrosine phosphoproteome was more abundant in PC9- and PC9GR-erlotinib treated cells, including phosphopeptides corresponding to MET, IGF, and AXL signaling. Activation of these receptor tyrosine kinases by growth factors could protect PC9GR cells against the irreversible EGFR-TKI afatinib. We identified a Src-family kinase (SFK) network as EGFR-independent and confirmed that neither erlotinib nor afatinib affected Src phosphorylation at the activation site. The SFK-inhibitor dasatinib plus afatinib abolished Src phosphorylation and completely suppressed downstream phosphorylated Akt and Erk. Dasatinib further enhanced anti-tumor activity of afatinib or T790M-selective EGFR-TKI (WZ4006) in proliferation and apoptosis assays in multiple NSCLC cell lines with T790M mediated resistance. This translated into tumor regression in PC9GR xenograft studies with combined afatinib and dasatinib. Conclusions: Our results identified both co-drivers of resistance along with T790M and support further studies of irreversible or T790M-selective EGFR inhibitors combined with dasatinib in NSCLC patients with acquired T790M.
    Clinical Cancer Research 06/2014; 20(15). DOI:10.1158/1078-0432.CCR-13-1559 · 8.19 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Cell signaling depends on dynamic protein-protein interaction (PPI) networks, often assembled through modular domains each interacting with multiple peptide motifs. This complexity raises a conceptual challenge, namely to define whether a particular cellular response requires assembly of the complete PPI network of interest or can be driven by a specific interaction. To address this issue, we designed variants of the Grb2 SH2 domain ("pY-clamps") whose specificity is highly biased toward a single phosphotyrosine (pY) motif among many potential pYXNX Grb2-binding sites. Surprisingly, directing Grb2 predominantly to a single pY site of the Ptpn11/Shp2 phosphatase, but not other sites tested, was sufficient for differentiation of the essential primitive endoderm lineage from embryonic stem cells. Our data suggest that discrete connections within complex PPI networks can underpin regulation of particular biological events. We propose that this directed wiring approach will be of general utility in functionally annotating specific PPIs.
    Molecular Cell 06/2014; 54(6):1034–1041. DOI:10.1016/j.molcel.2014.05.002 · 14.46 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Chronic myeloid leukemia (CML) is characterized by a genomic translocation generating a permanently active BCR-ABL oncogene with a complex pattern of atypically tyrosine-phosphorylated proteins that drive the malignant phenotype of CML. Recently, the LIM and SH3 domain protein 1 (LASP1) was identified as a component of a six gene signature that is strongly predictive for disease progression and relapse in CML patients. However, the underlying mechanisms why LASP1 expression correlates with dismal outcome remained unresolved. Here, we identified LASP1 as a novel and overexpressed direct substrate of BCR-ABL in CML. We demonstrate that LASP1 is specifically phosphorylated by BCR-ABL at tyrosine-171 in CML patients, which is abolished by tyrosine kinase inhibitor therapy. Further studies revealed that LASP1 phosphorylation results in an association with CRKL – another specific BCR-ABL substrate and bona fide biomarker for BCR-ABL activity. pLASP1-Y171 binds to non-phosphorylated CRKL at its SH2 domain. Accordingly, the BCR-ABL-mediated pathophysiological hyper-phosphorylation of LASP1 in CML disrupts normal regulation of CRKL and LASP1, which likely has implications on downstream BCR-ABL signaling. Collectively, our results suggest that LASP1 phosphorylation might serve as an additional candidate biomarker for assessment of BCR-ABL activity and provide a first step toward a molecular understanding of LASP1 function in CML.
    Oncotarget 06/2014; 5(14). · 6.63 Impact Factor

Full-text (2 Sources)

Download
82 Downloads
Available from
Jun 4, 2014