Project description:Trypanosomes expressing PTP-tagged EIF4E1 (PCF) or EIF4E6 (BSF) were used. The PTP-tagged proteins were purified on IgG columns, then eluted with TEV protease.
Project description:Although the consequences of genotoxic injury include cell cycle arrest and apoptosis, cell survival responses after genotoxic injury can produce intrinsic death-resistance and contribute to the development of a transformed phenotype. Protein tyrosine phosphatases (PTPs) are integral components of key survival pathways, and are responsible for their inactivation, while PTP inhibition is are often associated with enhanced cell proliferation. Our aim was to elucidate signaling events that modulate cell survival after genotoxin exposure. Diploid human lung fibroblasts (HLF) were treated with Cr(VI) (as Na2CrO4), a well known human respiratory carcinogen that induces a wide spectrum of DNA damage, in the presence and absence of a broad-range PTP inhibitor, sodium orthovanadate. Notably, PTP inhibition abrogated Cr(VI)-induced clonogenic lethality. The enhanced survival of Cr(VI)-exposed cells after PTP inhibition was predominantly due to a bypass of cell cycle arrest and was not due to decreased Cr uptake as evidenced by unchanged Cr-DNA adduct burden. Additionally, the bypass of Cr-induced growth arrest by PTP inhibition, was accompanied by a decrease in Cr(VI)-induced expression of cell cycle inhibiting genes, and an increase in the Cr(VI)-induced expression of cell cycle promoting genes. Importantly, PTP inhibition resulted in an increase in forward mutations at the HPRT locus, supporting the hypothesis that PTP inhibition in the presence of DNA damage may lead to genomic instability, via bypass of cell cycle checkpoints.
Project description:Although the consequences of genotoxic injury include cell cycle arrest and apoptosis, cell survival responses after genotoxic injury can produce intrinsic death-resistance and contribute to the development of a transformed phenotype. Protein tyrosine phosphatases (PTPs) are integral components of key survival pathways, and are responsible for their inactivation, while PTP inhibition is are often associated with enhanced cell proliferation. Our aim was to elucidate signaling events that modulate cell survival after genotoxin exposure. Diploid human lung fibroblasts (HLF) were treated with Cr(VI) (as Na2CrO4), a well known human respiratory carcinogen that induces a wide spectrum of DNA damage, in the presence and absence of a broad-range PTP inhibitor, sodium orthovanadate. Notably, PTP inhibition abrogated Cr(VI)-induced clonogenic lethality. The enhanced survival of Cr(VI)-exposed cells after PTP inhibition was predominantly due to a bypass of cell cycle arrest and was not due to decreased Cr uptake as evidenced by unchanged Cr-DNA adduct burden. Additionally, the bypass of Cr-induced growth arrest by PTP inhibition, was accompanied by a decrease in Cr(VI)-induced expression of cell cycle inhibiting genes, and an increase in the Cr(VI)-induced expression of cell cycle promoting genes. Importantly, PTP inhibition resulted in an increase in forward mutations at the HPRT locus, supporting the hypothesis that PTP inhibition in the presence of DNA damage may lead to genomic instability, via bypass of cell cycle checkpoints. Experiment Overall Design: Experimental factor was chemical treatment type (3 of them) Experiment Overall Design: (1) No: HLF 1-1, HLF 1-2, HLF 1-3, HLF 1-4 Experiment Overall Design: (2) 1uM Cr(VI): HLF 3-1, HLF 3-2, HLF 3-3, HLF 3-4 Experiment Overall Design: (3) 10uM SOV + 1uM Cr(VI): HLF 4-1, HLF 4-2, HLF 4-3, HLF 4-4 Experiment Overall Design: Biological replicates: 4 different RNA extractions from 4 different cell cultures=quadruplicate per chemical treatment type
Project description:The first bona fide PTP proto-oncogene was the Src-homology 2 domain-containing phosphatase SHP2 (encoded by PTPN11), an ubiquitously expressed PTP that transduces mitogenic, pro-survival, cell fate and/or pro-migratory signals from numerous growth factor-, cytokine- and extracellular matrix receptors. In malignancies, SHP2 is hyperactivated either downstream of oncoproteins or by mutations.We provide analysis of a primary triple-negative breast tumor grown as xenografts in the presence or absence of SHP2 for 30 days.
Project description:The first bona fide PTP proto-oncogene was the Src-homology 2 domain-containing phosphatase SHP2 (encoded by PTPN11), an ubiquitously expressed PTP that transduces mitogenic, pro-survival, cell fate and/or pro-migratory signals from numerous growth factor-, cytokine- and extracellular matrix receptors. In malignancies, SHP2 is hyperactivated either downstream of oncoproteins or by mutations.We provide analysis of the breast cancer cells BT474 grown as xenografts in the presence or absence of SHP2 for 30 days.
Project description:Vascular endothelial protein tyrosine phosphatase (VE-PTP, PTPRB) is a receptor type phosphatase that is crucial for the regulation of endothelial junctions and blood vessel development. VE-PTP regulates vascular integrity by dephosphorylating substrates which are key players in endothelial junction stability, such as the angiopoietin receptor TIE2, the endothelial adherens junction protein VE-cadherin and the vascular endothelial growth factor receptor VEGFR2. Here, we have systematically searched for novel substrates of VE-PTP in endothelial cells by utilizing two approaches. First, we studied changes in the endothelial phosphoproteome upon exposing cells to a highly VE-PTP-specific phosphatase inhibitor followed by affinity isolation and mass-spectrometric analysis of phosphorylated proteins by phosphotyrosine-specific antibodies. Second, we used a substrate trapping mutant of VE-PTP to pull down phosphorylated substrates in combination with SILAC-based quantitative mass spectrometry measurements. We identified a set of substrate candidates of VE-PTP, of which a remarkably large fraction is related to cell junctions (48/165; 29.1%). Several of those were found in both screens and displayed very high connectivity in predicted functional interaction networks. The receptor protein tyrosine kinase EPHB4 was the most prominently phosphorylated protein upon VE-PTP inhibition among those VE-PTP targets that were identified by both proteomic approaches. Further analysis revealed that EPHB4 forms a ternary complex with VE-PTP and TIE2 in endothelial cells. VE-PTP controls the phosphorylation of each of these two tyrosine kinase receptors. Despite of their simultaneous presence in a ternary complex, stimulating each of the receptors with their own specific ligand did not cross-activate the respective partner receptor. Our systematic approach has led to the identification of novel substrates of VE-PTP, of which many are relevant for the control of cellular junctions further promoting the importance of VE-PTP as a key player of junctional signalling.
Project description:The first bona fide PTP proto-oncogene was the Src-homology 2 domain-containing phosphatase SHP2 (encoded by PTPN11), an ubiquitously expressed PTP that transduces mitogenic, pro-survival, cell fate and/or pro-migratory signals from numerous growth factor-, cytokine- and extracellular matrix receptors. In malignancies, SHP2 is hyperactivated either downstream of oncoproteins or by mutations.We provide analysis of the human mesenchymal triple-negative breast cancer cell line SUM159 and grown in 2D cultures for 15 days in the presence or absence of SHP2.
Project description:The first bona fide PTP proto-oncogene was the Src-homology 2 domain-containing phosphatase SHP2 (encoded by PTPN11), an ubiquitously expressed PTP that transduces mitogenic, pro-survival, cell fate and/or pro-migratory signals from numerous growth factor-, cytokine- and extracellular matrix receptors. In malignancies, SHP2 is hyperactivated either downstream of oncoproteins or by mutations.We provide analysis of the mammary epithelial cells MCF10A overexpressing human HER2 and HER3 and grown in 3D cultures for 15 days in the presence or absence of SHP2.
Project description:Inhibition of VE-PTP, an endothelial receptor type tyrosine phosphatase, triggers phosphorylation of the tyrosine kinase receptor Tie-2, which leads to the suppression of inflammation-induced vascular permeability. Analyzing the underlying mechanism, we show here that inhibition of VE-PTP and activation of Tie-2 induce tyrosine phosphorylation of FGD5, a GTPase exchange factor (GEF) for Cdc42, and stimulate translocation of this GEF to cell contacts. Interfering with the expression of FGD5 blocked the junction stabilizing effect of VE-PTP inhibition in vitro and in vivo. Likewise, FGD5 was required for strengthening of cortical actin bundles and inhibiting radial stress fiber formation, which were each stimulated by VE-PTP inhibition. We identified Y820 of FGD5 as the direct substrate for VE-PTP. Inhibition of VE-PTP could no longer stabilize endothelial junctions or activate Cdc42 if endothelial cells expressed a Y820F point mutated version of FGD5. In contrast, FGD5-Y820F was still recruited to endothelial cell contacts. Thus, activation of FGD5 is a two-step process that comprises membrane recruitment and phosphorylation of Y820. These steps are necessary for the junction stabilizing effect that is stimulated by VE-PTP inhibition and Tie-2 activation.