Littérature scientifique sur le sujet « PH-Domain Inhibitor »
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Articles de revues sur le sujet "PH-Domain Inhibitor"
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Balasuriya, Nileeka, McShane McKenna, Xuguang Liu, Shawn Li et Patrick O’Donoghue. « Phosphorylation-Dependent Inhibition of Akt1 ». Genes 9, no 9 (7 septembre 2018) : 450. http://dx.doi.org/10.3390/genes9090450.
Texte intégralRésumé :
Protein kinase B (Akt1) is a proto-oncogene that is overactive in most cancers. Akt1 activation requires phosphorylation at Thr308; phosphorylation at Ser473 further enhances catalytic activity. Akt1 activity is also regulated via interactions between the kinase domain and the N-terminal auto-inhibitory pleckstrin homology (PH) domain. As it was previously difficult to produce Akt1 in site-specific phosphorylated forms, the contribution of each activating phosphorylation site to auto-inhibition was unknown. Using a combination of genetic code expansion and in vivo enzymatic phosphorylation, we produced Akt1 variants containing programmed phosphorylation to probe the interplay between Akt1 phosphorylation status and the auto-inhibitory function of the PH domain. Deletion of the PH domain increased the enzyme activity for all three phosphorylated Akt1 variants. For the doubly phosphorylated enzyme, deletion of the PH domain relieved auto-inhibition by 295-fold. We next found that phosphorylation at Ser473 provided resistance to chemical inhibition by Akti-1/2 inhibitor VIII. The Akti-1/2 inhibitor was most effective against pAkt1T308 and showed four-fold decreased potency with Akt1 variants phosphorylated at Ser473. The data highlight the need to design more potent Akt1 inhibitors that are effective against the doubly phosphorylated and most pathogenic form of Akt1.
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BARNETT, Stanley F., Deborah DEFEO-JONES, Sheng FU, Paula J. HANCOCK, Kathleen M. HASKELL, Raymond E. JONES, Jason A. KAHANA et al. « Identification and characterization of pleckstrin-homology-domain-dependent and isoenzyme-specific Akt inhibitors ». Biochemical Journal 385, no 2 (7 janvier 2005) : 399–408. http://dx.doi.org/10.1042/bj20041140.
Texte intégralRésumé :
We developed a high-throughput HTRF (homogeneous time-resolved fluorescence) assay for Akt kinase activity and screened approx. 270000 compounds for their ability to inhibit the three isoforms of Akt. Two Akt inhibitors were identified that exhibited isoenzyme specificity. The first compound (Akt-I-1) inhibited only Akt1 (IC50 4.6 μM) while the second compound (Akt-I-1,2) inhibited both Akt1 and Akt2 with IC50 values of 2.7 and 21 μM respectively. Neither compound inhibited Akt3 nor mutants lacking the PH (pleckstrin homology) domain at concentrations up to 250 μM. These compounds were reversible inhibitors, and exhibited a linear mixed-type inhibition against ATP and peptide substrate. In addition to inhibiting kinase activity of individual Akt isoforms, both inhibitors blocked the phosphorylation and activation of the corresponding Akt isoforms by PDK1 (phosphoinositide-dependent kinase 1). A model is proposed in which these inhibitors bind to a site formed only in the presence of the PH domain. Binding of the inhibitor is postulated to promote the formation of an inactive conformation. In support of this model, antibodies to the Akt PH domain or hinge region blocked the inhibition of Akt by Akt-I-1 and Akt-I-1,2. These inhibitors were found to be cell-active and to block phosphorylation of Akt at Thr308 and Ser473, reduce the levels of active Akt in cells, block the phosphorylation of known Akt substrates and promote TRAIL (tumour-necrosis-factor-related apoptosis-inducing ligand)-induced apoptosis in LNCap prostate cancer cells.
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Carón, Rubén W., Adly Yacoub, Min Li, Xiaoyu Zhu, Clint Mitchell, Young Hong, William Hawkins et al. « Activated forms of H-RAS and K-RAS differentially regulate membrane association of PI3K, PDK-1, and AKT and the effect of therapeutic kinase inhibitors on cell survival ». Molecular Cancer Therapeutics 4, no 2 (1 février 2005) : 257–70. http://dx.doi.org/10.1158/1535-7163.257.4.2.
Texte intégralRésumé :
Abstract The abilities of mutated active RAS proteins to modulate cell survival following exposure to ionizing radiation and small molecule kinase inhibitors were examined. Homologous recombination in HCT116 cells to delete the single allele of K-RAS D13 resulted in a cell line that exhibited an ∼75% reduction in basal extracellular signal-regulated kinase 1/2, AKT, and c-jun-NH2-kinase 1/2 activity. Transfection of cells lacking K-RAS D13 with H-RAS V12 restored extracellular signal-regulated kinase 1/2 and AKT activity to basal levels but did not restore c-jun-NH2-kinase 1/2 phosphorylation. In cells expressing H-RAS V12, radiation caused prolonged intense activation of AKT. Inhibition of H-RAS V12 function, blockade of phosphatidylinositol 3-kinase (PI3K) function using small interfering RNA/small-molecule inhibitors, or expression of dominant-negative AKT abolished radiation-induced AKT activation, and radiosensitized these cells. Inhibition of PI3K function did not significantly radiosensitize parental HCT116 cells. Inhibitors of the AKT PH domain including perifosine, SH-(5, 23-25) and ml-(14-16) reduced the plating efficiency of H-RAS V12 cells in a dose-dependent fashion. Inhibition of AKT function using perifosine enhanced radiosensitivity in H-RAS V12 cells, whereas the SH and ml series of AKT PH domain inhibitors failed to promote radiation toxicity. In HCT116 H-RAS V12 cells, PI3K, PDK-1, and AKT were membrane associated, whereas in parental cells expressing K-RAS D13, only PDK-1 was membrane bound. In H-RAS V12 cells, membrane associated PDK-1 was phosphorylated at Y373/376, which was abolished by the Src family kinase inhibitor PP2. Inhibition of PDK-1 function using the PH domain inhibitor OSU-03012 or using PP2 reduced the plating efficiency of H-RAS V12 cells and profoundly increased radiosensitivity. OSU-03012 and PP2 did not radiosensitize and had modest inhibitory effects on plating efficiency in parental cells. A small interfering RNA generated against PDK1 also radiosensitized HCT116 cells expressing H-RAS V12. Collectively, our data argue that molecular inhibition of AKT and PDK-1 signaling enhances the radiosensitivity of HCT116 cells expressing H-RAS V12 but not K-RAS D13. Small-molecule inhibitory agents that blocked stimulated and/or basal PDK-1 and AKT function profoundly reduced HCT116 cell survival but had variable effects at enhancing tumor cell radiosensitivity.
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NA, Byoung-Kuk, Bhaskar R. SHENAI, Puran S. SIJWALI, Youngchool CHOE, Kailash C. PANDEY, Ajay SINGH, Charles S. CRAIK et Philip J. ROSENTHAL. « Identification and biochemical characterization of vivapains, cysteine proteases of the malaria parasite Plasmodium vivax ». Biochemical Journal 378, no 2 (1 mars 2004) : 529–38. http://dx.doi.org/10.1042/bj20031487.
Texte intégralRésumé :
Cysteine proteases play important roles in the life cycles of malaria parasites. Cysteine protease inhibitors block haemoglobin hydrolysis and development in Plasmodium falciparum, suggesting that the cysteine proteases of this major human pathogen, termed falcipains, are appropriate therapeutic targets. To expand our understanding of plasmodial proteases to Plasmodium vivax, the other prevalent human malaria parasite, we identified and cloned genes encoding the P. vivax cysteine proteases, vivapain-2 and vivapain-3, and functionally expressed the proteases in Escherichia coli. The vivapain-2 and vivapain-3 genes predicted papain-family cysteine proteases, which shared a number of unusual features with falcipain-2 and falcipain-3, including large prodomains and short N-terminal extensions on the catalytic domain. Recombinant vivapain-2 and vivapain-3 shared properties with the falcipains, including acidic pH optima, requirements for reducing conditions for activity and hydrolysis of substrates with positively charged residues at P1 and Leu at P2. Both enzymes hydrolysed native haemoglobin at acidic pH and the erythrocyte cytoskeletal protein 4.1 at neutral pH, suggesting similar biological roles to the falcipains. Considering inhibitor profiles, the vivapains were inhibited by fluoromethylketone and vinyl sulphone inhibitors that also inhibited falcipains and have demonstrated potent antimalarial activity.
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Miyamoto, Seiji, Atsushi Iwasa, Masao Ishii, Kenji Okajima et Yu-ichi Kamikubo. « Purification and Characterization of Factor VII Inhibitor Found in a Patient with Life Threatening Bleeding ». Thrombosis and Haemostasis 83, no 01 (2000) : 60–64. http://dx.doi.org/10.1055/s-0037-1613758.
Texte intégralRésumé :
SummaryWe recently observed a patient with acquired inhibitor-induced F.VII deficiency whose plasma level of F.VII was < 1.0%. However, the biochemical nature of the inhibitor has not yet been clarified. In the present study, we purified the F.VII inhibitor from the patient’s plasma by using activated F.VII (F.VIIa)-conjugated gel and characterized the inhibitor. The results showed that the inhibitor comprised two kinds of antibodies: one was eluted with EDTA (antibody 1) and the other with glycine-HCl buffer (pH 2.3) (antibody 2) from the F.VIIa affinity gel. SDS-polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblotting analysis of these inhibitors demonstrated that both antibodies had features of immunoglobulin G1 (IgG1) with κ and λ-light chains. Antibody 1 bound to the immobilized F.VIIa with a high affinity in the presence of calcium ion, while antibody 2 bound to the F.VIIa very weakly and the binding was independent of calcium ion. Immunoblotting analysis demonstrated that antibody 1 bound to the light chain of F.VIIa after reduction with 2-mercaptoethanol, while it did not react with either the γ carboxyglutamic acid (Gla)-domainless light chain of F.VIIa or the heavy chain with the protease domain. Antibody 1 markedly inhibited the activity of tissue factor-F.VIIa complex. Based on these observations, it is suggested that F.VIIa autoantibody (antibody 1) recognizes the calcium-dependent conformation within or near the Gla domain and inhibits F.VIIa activity by interacting with the light chain.
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Königs, Christoph, Christoph Kessel, Sabine Scholz, Susanne Stumpf, Manuela Krause, Thomas Klingebiel et Wolfhart Kreuz. « Epitope Mapping of Inhibitors in Acquired Hemophilia by Phage Display. » Blood 106, no 11 (16 novembre 2005) : 3202. http://dx.doi.org/10.1182/blood.v106.11.3202.3202.
Texte intégralRésumé :
Abstract In acquired hemophilia polyclonal autoantibodies (inhibitors) to coagulation factor VIII are generated. Inhibitors functionally interfere with interaction of molecules involved in the coagulation cascade for example the interaction of FVIII and the von Willebrand factor. Inhibitors in acquired hemophilia have been reported to bind either to the A2 or to C2 domain of FVIII. Random peptide phage display libraries were screened with patient plasma to identify small peptides mimicking inhibitor epitopes. Peptide sequences were used to map the inhibitor epitope to the surface of FVIII. The phage libraries included libraries with linear or cyclic 7mer or 12mer inserts. Biopanning was performed including positive selections and also negative selections to deplete irrelevant binders. Phages bound to inhibitors were eluted by pH shift or by competition with FVIII. Single phage clones were tested for their specificity for inhibitor positive plasma by ELISA. For specific binders, the sequence of the inserts was identified by DNA sequencing. For one patient 33 phage clones were analysed from three libraries and 28 peptide sequences mimicking the inhibitor epitopemimotopes - were determined. The peptide sequences map to two conformational epitopes on the A2 and A1 domain of FVIII. Clusters of six and four amino acids are the proposed binding regions on the A2 and A1 domain respectively. The matching conformational motifs contain PPLRQ and PPLS. Synthetic peptides corresponding to the sequence displayed on phage were generated and binding of inhibitors to peptides was confirmed by different ELISA formats. Currently, functional studies with synthetic peptides are being performed to further analyse the epitopes. Additionally, more patient samples are being screened to analyse further epitopes and understand immuno dominant regions of FVIII in acquired haemophilia and compare them to the immune response in hemophilia A. The mimotopes isolated could be a basis for the development of ligand effector conjugates to target inhibitor specific B cells.
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Kimura, Shinya, Haruna Naito, Hidekazu Segawa, Junya Kuroda, Takeshi Yuasa, Kiyoshi Sato, Asumi Yokota et al. « NS-187, a potent and selective dual Bcr-Abl/Lyn tyrosine kinase inhibitor, is a novel agent for imatinib-resistant leukemia ». Blood 106, no 12 (1 décembre 2005) : 3948–54. http://dx.doi.org/10.1182/blood-2005-06-2209.
Texte intégralRésumé :
Although the Abelson (Abl) tyrosine kinase inhibitor imatinib mesylate has improved the treatment of breakpoint cluster region–Abl (Bcr-Abl)–positive leukemia, resistance is often reported in patients with advanced-stage disease. Although several Src inhibitors are more effective than imatinib and simultaneously inhibit Lyn, whose overexpression is associated with imatinib resistance, these inhibitors are less specific than imatinib. We have identified a specific dual Abl-Lyn inhibitor, NS-187 (elsewhere described as CNS-9), which is 25 to 55 times more potent than imatinib in vitro. NS-187 is also at least 10 times as effective as imatinib in suppressing the growth of Bcr-Abl–bearing tumors and markedly extends the survival of mice bearing such tumors. The inhibitory effect of NS-187 extends to 12 of 13 Bcr-Abl proteins with mutations in their kinase domain but not to T315I. NS-187 also inhibits Lyn without affecting the phosphorylation of Src, Blk, or Yes. These results suggest that NS-187 may be a potentially valuable novel agent to combat imatinib-resistant Philadelphia-positive (Ph+) leukemia.
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Kasap, Corynn, Nicholas Hertz, Debora Makino, Kevan Shokat, John Kuriyan et Neil P. Shah. « Beyond the Gatekeeper : Imatinib- and Dasatinib-Resistant BCR-ABL/F317 Mutations Confer Cross-Resistance to VX-680 but Are Sensitive to a Structural Derivative of VX-680 ». Blood 112, no 11 (16 novembre 2008) : 725. http://dx.doi.org/10.1182/blood.v112.11.725.725.
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Abstract The management of chronic phase CML has been revolutionized by selective ABL tyrosine kinase inhibitor (TKI) therapy. Despite the effectiveness of these targeted agents, long-term control of blast phase CML and Ph+ ALL has been elusive, where the majority of patients relapse within 6–12 months. For blast phase CML and Ph+ ALL, two TKIs are currently approved: imatinib and dasatinib. While head-to-head comparisons of these agents have not been performed, it is generally believed that dasatinib is the more active agent for these phases of disease. In most cases, loss of response to these agents is driven by BCR-ABL kinase domain mutations. While more than 70 mutations have been associated with clinical resistance to imatinib, dasatinib appears vulnerable primarily to five mutations: V299L, T315A, T315I, F317I, and F317L. Of these, T315I and F317L are cross-resistant to imatinib. For the achievement of long-term remissions in blast phase CML and Ph+ ALL, a combination of TKIs that can collectively suppress all resistant BCR-ABL kinase domain mutations holds therapeutic promise. The BCR-ABL/T315I mutation, which confers a high degree of resistance to all approved BCR-ABL TKIs, has been referred to as a “molecular gatekeeper”, as it restricts access to a deeper hydrophobic pocket within the ABL kinase domain and makes an important stabilizing H-bond with imatinib, dasatinib and nilotinib. The Aurora kinase inhibitor VX-680 was the first compound to have activity against BCR-ABL/T315I in vitro, as well as clinically. To determine the promise of a kinase inhibitor combination of dasatinib and VX-680, we assessed the activity of VX-680 against the five dasatinib-resistant mutations using a cell-based flow cytometric assay of BCR-ABL kinase activity. While three mutants are sensitive, mutations at F317 demonstrated a high degree of resistance. We tested a number of other Aurora kinase inhibitors of different chemotypes and found that each of these had similar difficulty at inhibiting the kinase activity of BCR-ABL/F317 mutants. Based upon the co-crystal structure of VX-680 complexed with ABL, we have performed structure-activity relationship studies of 12 VX-680 scaffold derivatives, and have successfully identified structural modifications that increase kinase inhibitory activity against F317 mutants. Moreover, one of these derivatives increases the selectivity for ABL relative to Aurora kinases, which may help reduce the likelihood of suppressing normal hematopoiesis, a dose-limiting toxicity of Aurora kinase inhibitors that may substantially limit their effectiveness for the management of hematologic malignancies such as blast phase CML and Ph+ ALL. Lastly, we have performed structural studies of ABL/F317 mutants complexed with select VX-680 derivatives in an effort to understand how F317 mutations confer resistance to a broad range of ABL and Aurora kinase inhibitors. Interestingly, a recent study reported the successful selection of Aurora kinase inhibitor-resistant clones derived from a human colon cancer cell line (Girdler et al, 2008). While no resistance-conferring mutations were isolated at L154, the Aurora kinase gatekeeper residue, mutations were detected at Y156 in Aurora B, which corresponds to F317 in ABL. Aurora B Y156 mutations were found to confer resistance to a number of Aurora kinase inhibitors, including VX-680. As Aurora kinase inhibitors are being studied in a variety of non-hematologic malignancies, there is an increasing need to understand and overcome the mechanisms whereby mutations at this residue confer resistance to these agents. It is hoped that our studies will lead not only to the development of an effective adjunctive kinase inhibitor for the treatment of blast phase CML and Ph+ ALL, but will also shed light on the growing problem of resistance conferred by mutations at residues that correspond to BCR-ABL/F317 in other kinases.
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Liao, Maofu, et Margaret Kielian. « Domain III from class II fusion proteins functions as a dominant-negative inhibitor of virus membrane fusion ». Journal of Cell Biology 171, no 1 (10 octobre 2005) : 111–20. http://dx.doi.org/10.1083/jcb.200507075.
Texte intégralRésumé :
Alphaviruses and flaviviruses infect cells through low pH-dependent membrane fusion reactions mediated by their structurally similar viral fusion proteins. During fusion, these class II viral fusion proteins trimerize and refold to form hairpin-like structures, with the domain III and stem regions folded back toward the target membrane-inserted fusion peptides. We demonstrate that exogenous domain III can function as a dominant-negative inhibitor of alphavirus and flavivirus membrane fusion and infection. Domain III binds stably to the fusion protein, thus preventing the foldback reaction and blocking the lipid mixing step of fusion. Our data reveal the existence of a relatively long-lived core trimer intermediate with which domain III interacts to initiate membrane fusion. These novel inhibitors of the class II fusion proteins show cross-inhibition within the virus genus and suggest that the domain III–core trimer interaction can serve as a new target for the development of antiviral reagents.
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NAGASE, Hideaki, Ko SUZUKI, Tim E. CAWSTON et K. BREW. « Involvement of a region near valine-69 of tissue inhibitor of metalloproteinases (TIMP)-1 in the interaction with matrix metalloproteinase 3 (stromelysin 1) ». Biochemical Journal 325, no 1 (1 juillet 1997) : 163–67. http://dx.doi.org/10.1042/bj3250163.
Texte intégralRésumé :
Tissue inhibitors of metalloproteinases (TIMPs) inhibit matrix metalloproteinases (MMPs) by forming a 1:1 stoichiometric complex, but the inhibition mechanism of these inhibitors is not known. Here we have investigated the reactive site of TIMP-1 by its proteinase susceptibility before and after forming a complex with MMP-3 (stromelysin 1). When TIMP-1 was allowed to react with human neutrophil elastase, its inhibitory activity was destroyed. This resulted from cleavage of the Val69–Cys70 bond. However, cleavage of this bond by neutrophil elastase was prevented when TIMP-1 formed a complex with the catalytic domain of MMP-3, and full TIMP-1 activity was restored after dissociation of the complex at pH 3.0 in the presence of EDTA. These results indicate that the region around Val69 closely associates with an active MMP. The three-dimensional structure of the N-terminal domain of TIMP-2 elucidated by NMR studies [Williamson, Martorell, Carr, Murphy, Docherty, Freedman and Feeney (1994) Biochemistry 33, 11745–11759] reveals that Val69 and Cys70 form part of an extended ridge that also includes the N-terminal section of the inhibitor. This region is probably involved in the interaction with the catalytic domains of MMPs.
Thèses sur le sujet "PH-Domain Inhibitor"
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CHISCI, RICCARDO. « Akt-Pka interaction in the modulation of cardiac excitation - contraction coupling ». Doctoral thesis, Università degli Studi di Milano-Bicocca, 2010. http://hdl.handle.net/10281/7484.
Texte intégralRésumé :
Derangement of sarcoplasmic reticulum (SR) function play a primary role in the pathogenesis of cardiac contractile deficit in heart failure (HF). The PI3K/AKT is a complex signalling pathway with a central role in the modulation of both cardiac function and structure; an imbalance in its components may contribute to contractile dysfunction and myocardial structural remodelling in HF. In particular, the cardiac contractility modulation, in which the PI3K/Akt pathway is involved, is mainly regulated by β-adrenergic signaling. The pleckstrin-homology (PH) domain is a highly conserved protein domain, involved in PI3K-mediated membrane recruitment, and subsequent activation, of signaling pathways, including Akt.
The diverse effects mediated by PI3K/Akt signalling in the heart clearly support an important biological and pathophysiological role for this signalling cascade. The PI3K/Akt signalling pathways are involved in a wide variety of diseases including myocardial hypertrophy and contractility, heart failure, and preconditioning.
The aim of this study was to further investigate the role of PI3K/Akt pathway on the modulation of the cardiac excitation-contraction coupling (ECC). We focused our attention on Akt, because the role of this kinase results still unclear.
To pursue this purpose we inhibited Akt through two experimental approaches: first, we used two chemical unrelated compounds (Compound A and B) able to interact with kineases PH-domain to prevent the recognition of the PIP3 inositol ring and subsequent activation; second, Akt gene silencing through RNA intereference technique. With these two methods, we were able to rule out compound-dependent effects due to their potential aspecificity and to assert the effective consequence of Akt activity ablation on the modulation of cardiac function.
PH-antagonism (PH-antag) increased baseline contractility, an effect inhibited by β1+β2-AR blockade. The effect of PH-antag was larger in the presence of ISO, abolished by β1+β2-AR blockade, but only partially reduced by selective blockade of either β1- or β2-AR. Basal twitch amplitude were increased in Akt1 silenced cells; both compounds did not affect twitch amplitude on transfected myocytes. Both PH-domain inhibitors stimulated SR function (NCX blockade) increasing the SR reloading steepness, the Ca2+ reuptake rate and the EC-coupling gain. Also increase calcium leakage without affecting SR content.
So we can conclude that PH-antag unmask the inhibitory effect of Akt acting trough SR system increasing SERCA and RyR activity.
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Hodakoski, Cindy Marie. « P-REX2 PH Domain Inhibition of PTEN Regulates Transformation, Insulin Signaling, and Glucose Homeostasis ». Thesis, 2012. https://doi.org/10.7916/D86T0TRZ.
Texte intégralRésumé :
PTEN, a tumor suppressor lost in multiple cancers, antagonizes PI3-kinase signaling by dephosphorylating the second messenger phosphatidylinositol (3,4,5) trisphophate. PTEN expression and enzymatic activity is regulated through various mechanisms, including oxidation, phosphorylation, and protein-protein interactions. Our lab has recently identified a PTEN interacting protein, the Rac GEF P-REX2, which inhibits PTEN phosphatase activity in a non-competitive manner. This thesis focuses on understanding the physiological relevance of this interaction in the regulation of PI3K signaling, as well as determining the mechanism of P-REX2 mediated PTEN inhibition.The first chapter focuses on the role of P-REX2 over expression in PI3K signaling, proliferation, and transformation. We first find that P-REX2 Rac GEF activity is dispensable for PTEN inhibition by utilizing a P-REX2 GEF dead mutant N212A. Next, we determined the effect of P-REX2 overexpression on PI3K signaling in normal mammary epithelial cells. Expression of P-REX2 or the DHPH inhibitory domain increased AKT phosphorylation, promoted cellular proliferation, and disrupted acini morphogenesis. Furthermore, P-REX2 cooperated with other oncogenes, including the PI3K E545K oncogenic mutant, c-MYC, and HER2 to promote proliferation, colony formation in soft agar, and tumor formation in mice. We also analyzed the effects of expression of P-REX2 cancer mutants, and discovered two transforming mutants, V432M and R498I that cooperated with PI3K E545K to increase anchorage independent growth and cellular proliferation.The next chapter examines the role of P-rex2 in PI3K signaling regulation in vivo. We generated Prex2 knockout mice using a gene trap method, and found that baseline signaling and proliferation in fibroblasts was not affected by P-rex2 deletion. However, insulin and IGF-1, but not PDGF or EGF stimulated PI3K signaling was reduced in Prex2-/- fibroblasts. The activity of PTEN from Prex2+/+ fibroblasts was reduced following insulin stimulation, but remained elevated in Prex2-/- cells, suggesting that insulin stimulated PTEN inhibition is dependent on P-rex2. Furthermore, P-REX2 interacted with phosphorylated insulin receptor and recruited PTEN to the membrane following insulin stimulation. Prex2-/- mice are intolerant to insulin and glucose, and have reduced PI3K signaling in the fat and liver following insulin stimulation. Furthermore, the activity of PTEN from Prex2-/- liver samples is elevated, and correlated with a decrease in cellular PIP3 levels. After uncovering an essential role for P-REX2 in PI3K signal transduction, we next examined the mechanism and regulation of P-REX2 mediated PTEN inhibition. We found that P-REX2 interacts with two different sites on PTEN. The PH domain of P-REX2 bound to the phosphatase and C2 domains of PTEN, while the inositol polyphosphate-4 phosphatase domain interacted with the PDZ-binding domain on the PTEN C-terminal tail. We discovered that the PH domain was the minimal domain that constitutively inhibited PTEN. However, the DHPH domain and full length P-REX2 required phosphorylation of the PTEN C-terminal tail for inhibition, suggesting the DH domain of P-REX2 restricts PH domain inhibition of PTEN when the C-terminal tail of PTEN is unphosphorylated. Furthermore, the PH domain of P-REX1 was not able to inhibit PTEN, and full length P-REX1 did not interact with PTEN, suggesting that there is a level of specificity involved in P-REX2 PH domain mediated phosphatase inhibition and binding. Overall, this thesis identifies P-REX2 as a dynamic inhibitor of PTEN phosphatase activity that regulates PI3K mediated cellular transformation, insulin signaling, and glucose metabolism.
Livres sur le sujet "PH-Domain Inhibitor"
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Hodakoski, Cindy Marie. P-REX2 PH Domain Inhibition of PTEN Regulates Transformation, Insulin Signaling, and Glucose Homeostasis. [New York, N.Y.?] : [publisher not identified], 2012.
Trouver le texte intégralActes de conférences sur le sujet "PH-Domain Inhibitor"
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Meuillet, Emmanuelle, Sylvester Moses, Jenny Johnson, Robert Lemos, Mena F. Abdelmelek, Garth Powis et Lynn Kirkpatrick. « Abstract A213 : Topical PHT-427, a dual AKT/PDPK1 PH domain inhibitor, for treatment of primary and metastatic skin cancer. » Dans Abstracts : AACR-NCI-EORTC International Conference : Molecular Targets and Cancer Therapeutics--Nov 12-16, 2011 ; San Francisco, CA. American Association for Cancer Research, 2011. http://dx.doi.org/10.1158/1535-7163.targ-11-a213.
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Berndt, Norbert, Hua Yang, Bernard Trinczek, Ziming Zhang, Bainan Wu, Nicholas J. Lawrence, Maurizio Pellechia, Ernst Schonbrunn, Jin Q. Cheng et Said M. Sebti. « Abstract 3680 : The Akt activation inhibitor TCN-P inhibits Akt phosphorylation by binding to the PH domain of Akt and blocking its recruitment to the plasma membrane ». Dans Proceedings : AACR 101st Annual Meeting 2010‐‐ Apr 17‐21, 2010 ; Washington, DC. American Association for Cancer Research, 2010. http://dx.doi.org/10.1158/1538-7445.am10-3680.
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Zhang, Shuxing, Emmanuelle Meuillet, Garth Powis et D. Lynn Kirkpatrick. « Abstract 1975 : PHuDock®, a computational discovery and development platform for novel PH domain-binding agents, identifies a novel antitumor AKT/PDPK1 inhibitor, PHT- 427 ». Dans Proceedings : AACR 101st Annual Meeting 2010‐‐ Apr 17‐21, 2010 ; Washington, DC. American Association for Cancer Research, 2010. http://dx.doi.org/10.1158/1538-7445.am10-1975.
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Higashiyama, S., I. Ohkubo, H. Ishiguro et M. Sasaki. « A NEW FUNCTION OF HUMAN KININOGENS : THE AMINO-TERMINAL REGION OF DOMAIN 1 INVOLVES AN EF HAND-LIKE STRACTURE FOR METAL BINDING ». Dans XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1642851.
Texte intégralRésumé :
Two types of kininogens in mammalian plasma, high molecular weight (HMW) and low molecular weight (LMW) kininogens, are the precursors of kinin. Especially, HMW kininogen circulates in the plasma as a complex with prekallikrein and factor XI, and functions as a cofactor in the initial phase reactions of intrinsic blood coagulation cascade. Recently, it has been found that the kininogens have inhibitory activity toward cysteine proteinases. The heavy chain portion, which is identical for HMW and LMW kininogens, is composed of three domains, domain 1, 2 and 3. Each the domain 2 and 3 has a reactive site as a cysteine proteinase inhibitor. However, physiological function of domain 1 remains still unknown. By using the antibody recognizing the interaction between HMW kininogen and Ca2+ (anti-HMW kininogen-Ca2+ antibody) as a probe, we newly found the Ca2+ binding site in the domain 1.Anti-HMW kininogen-Ca2+ antibody was isolated from anti-HMW kininogen antiserum as an antibody which bound to a HMW kininogen-Sepharose column equilibrated with 40 mM Tris-HCl buffer, pH 7.5, containing 1.0 M NaCl and 1 mM CaCl2, and was eluted with 3 mM EDTA. Resulting from the characterization by ELISA, this antibody specifically recognized the CB-1 region (CNBr-cleavage fragment 1: 1-160 amino acid sequence) of the heavy chain of kininogen molecules in the presence of Ca2+ or Mg2+. Furthermore, circular dichroism (CD) experiments showed that the conformational changes of HMW kininogen and heavy chain were induced by the addition of metal ions such as Ca2+ or Mg2+, and that this change was due to the conformational change of the CB-1 region. The dissociation constant (Kd) for heavy chain measured by Ca2+ titration analysis by CD at 214 nm was found to be 0.33 ± 0.09 mM. The number of Ca2+ binding sites of heavy chain calculated from Hill plot was 1.15 ± 0.04. The EF handlike structure found in the amino-terminal portion of the heavy chain of kininogen molecules strongly supported the above data. This indicates a possibility that kininogens play an important role as a Ca2+ binding protein.
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Church, F. C., R. E. Treanor et H. C. Whinna. « ACTIVATION OF HEPARIN COFACTOR II BY PHOSVITIN, A PHOSPHOGLYCO-PROTEIN, AND OTHER PHOSPHATE-CONTAINING POLYANIONS ». Dans XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1643867.
Texte intégralRésumé :
We are characterizing the specificity of the polyanion-binding domain of the heparin/dermatan sulfate-dependent plasma protease inhibitor, heparin cofactor II (HCII). Various phosphate-containing polyanions accelerate the HCII-catalyzed inhibition of thrombin (T). Phosvitin, a phosphoprotein, enhances the HCII/T reaction at 25°C and pH 8.0 with the apparent second-order rate constant value (K2) increasing from 5 × 104 M−1 min−1 (in the absence of phosvitin) to 8 x 10' M”1 min as phosvitin increased from 0.05 to 30 ug/ml and then decreases as phosvitin is increased above 30 ug/ml. Apparent dissociation constant values for phosvitin-HCII and phosvitin-T are 450 nM and 10 nM, respectively. Polynucleotides accelerate the HCII/T reaction and have the following specificity (concentrations examined from 1-200 ug/ml): poly(guanylic acid) >> poly(adeny-lic acid, guanylic acid) > poly(inosinic acid) > poly(guanylic acid, uridylic acid) > poly(uridylic acid) = poly(adenylic acid) > poly(cytidylic acid). Polyphosphate anions (phosphate chain length, n, ranging from 5-100) enhance the HCII/T reaction. When compared at an equimolar phosphate concentration (1 mM), the rate was saturated at n = 50 with a maximum V.2 of about 5 × 107 M−1 min−1. Ca2+ (or Mg2+)-phosvitin/polyphosphate anion complexes and salmon protamine-polynucleotide complexes have lost the ability to enhance the HCII/T reaction. Phospho-pyridoxylated-HCII (lysine modified), with greatly reduced heparin cofactor activity, has lost its accelerating effect with phosvitin, polynucleotides and the polyphosphate anions. None of the above mentioned polyphosphate-containing compounds are effective at accelerating either the HCII-catalyzed inhibition of chymotrypsin or the antithrombin Ill-catalyzed T reaction. Our results suggest that (i) HCII is activated by the multiple negative charges of phosphate polyanions but they alone are not sufficient; (ii) the effective phosphate polyanions must also possess a specific conformation for maximum activity; and (iii) the phosphoserine-containing protein, phosvitin, can serve as a "template" for HCII/T.
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Kirby, Edward P., Mary Ann Mascelli, Carol Silverman et Daniel W. Karl. « LOCALIZATION OF THE PLATELET-BINDING AND HEPARIN-BINDING DOMAINS OF BOVINE VON WILLEBRAND FACTOR ». Dans XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1644097.
Texte intégralRésumé :
Bovine von Willebrand Factor (vWF) binds directly to human platelets and also to heparin-agarose. Cleavage of vWF with Protease I, a metalloenzyme isolated from the venom of the western diamondback rattlesnake, produces two major fragments with apparent Mr of 250 kD and 200 kD. The 200 kD fragment competes with native vWF for binding to the GPIb-associated vWF receptor on formalin-fixed human platelets and has weak platelet-agglutinating activity. It is composed of three polypeptide chains of apparent Mr of 97 kD, 61 kD, and 35 kD. Monoclonal antibodies #2 and H-9, which inhibit binding of vWF to a GPIb-associated receptor of platelets, recognize the 200 kD fragment.Modification of vWF with ^5x-la.beled. Bolton-Hunter reagent (I*-BHR) causes inhibition of platelet-agglutinating activity at very low levels of incorporation. Modification of less than 2% of the amino groups in vWF causes 50% loss of platelet agglutinating activity and a decreased affinity of vWF for binding to platelets. Labeling with I*-BHR does not block binding to heparin-agarose, even when 5-10% of the amino groups are modified. Differential labeling at pH 7.0 and pH 8.5, followed by proteolytic fragmentation with Protease I, suggests that it is the modification of amino groups on the 200 kD fragment which is responsible fpr the decrease in platelet binding activity. Modification of the 97 kD peptide chain is best correlated with this loss of platelet binding activity.Heparin inhibits the agglutination of human platelets by bovine vWF. The 200 kD fragment of vWF binds both to platelets and to heparin-agarose. These observations suggest that the heparin-binding and platelet-binding domains of vWF, although distinct from one another, reside in the same region of the vWF molecule. The platelet-binding domain contains a small number of very reactive amino groups which are required for vWF binding to human platelets.These studies were supported by a grant from the National Institutes of Health (#HL27993).
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Meuillet, Emmanuelle J., Sylvestor A. Moses, Jana Jandova, Eugene A. Mash et Shuxing Zhang. « Abstract 5563 : Targeting the PH domain of TIAM1 to inhibit prostate cancer metastasis. » Dans Proceedings : AACR 104th Annual Meeting 2013 ; Apr 6-10, 2013 ; Washington, DC. American Association for Cancer Research, 2013. http://dx.doi.org/10.1158/1538-7445.am2013-5563.
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Moses, Sylvestor A., Zuohe Song, Lei Du-Cuny, Garth Powis, Eugene Mash, Shuxing Zhang et Emmanuelle J. Meuillet. « Abstract 1559 : Targeting the PH domain of Tiam-1 to inhibit breast cancer metastasis ». Dans Proceedings : AACR 101st Annual Meeting 2010‐‐ Apr 17‐21, 2010 ; Washington, DC. American Association for Cancer Research, 2010. http://dx.doi.org/10.1158/1538-7445.am10-1559.
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