Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

---

Query: EC:2.7.10.2 (focal adhesion kinase)
44,029 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have investigated the intracellular mechanisms involved in microtubular remodelling by thrombin and its possible involvement in platelet aggregation and secretion. Platelet stimulation with thrombin induces a time- and concentration-dependent regulation of the microtubular content, which was found to be maximally effective at the concentration 0.1 U/ml. Thrombin (0.1 U/ml) evoked an initial decrease in the microtubule content detectable at 5 seconds (sec) and reached a minimum 10 sec after stimulation. The microtubular content then increased, exceeding basal levels again approximately 30 sec after stimulation. Inhibition of tyrosine phosphatases using vanadate abolished thrombin-induced microtubular depolymerisation while inhibition of tyrosine kinases by methyl-2,5-dihydroxycinnamate prevented microtubule polymerisation. Thrombin activates the cytosolic Bruton's tyrosine kinase (Btk) and Src proteins. Inhibition of Btk or Src by LFM-A13 or PP1, respectively, abolished thrombin-induced microtubular polymerisation, while maintaining intact its ability to induce initial depolymerisation. Microtubular disruption by colchicine significantly reduced thrombin-induced platelet aggregation and ATP secretion. Similar results were observed after inhibition of microtubular disassembly by paclitaxel. These findings indicate that thrombin induces microtubular remodelling by modifying the balance between protein tyrosine phosphorylation and dephosphorylation. The former seems to be required for microtubular polymerisation, while tyrosine dephosphorylation is required for microtubular depolymerisation. Both, initial microtubular disassembly and subsequent polymerisation are required for thrombin-induced platelet aggregation and secretion in human platelets.
...
PMID:Tyrosine phosphorylation / dephosphorylation balance is involved in thrombin-evoked microtubular reorganisation in human platelets. 1772 20

Lower CVD incidence is reported in Asian populations consuming soya-containing food. As polymorphonuclear leukocytes (PMN) are involved in the risk of CVD, we investigated the modulatory effect of soya isoflavones on several PMN functions and their molecular mechanisms in vitro. PMN, isolated from blood from healthy subjects, were tested upon activation with 1 microm- n-formyl-methyl-leucyl-phenylalanine (fMLP) for superoxide anion production (ferric cytochrome c reduction) and released elastase (chromogenic test). PMN homotypic aggregates stimulated by fMLP or P-selectin in dynamic conditions were detected by optical microscopy. PMN, mixed with thrombin-activated, washed platelets, formed cell aggregates, measured by flow cytometry. Phosphorylation of Pyk2, a focal adhesion kinase, was studied by immunoprecipitation and immunoblotting with specific antibodies. Genistein, daidzein and equol inhibited superoxide anion production (IC50 0.25 (sem 0.1), 21.0 (sem 4.2) and 13.0 (sem 2.8) microm, respectively); the release of elastase was prevented by genistein (IC50 63 (sem 17) microm). PMN homotypic aggregates, stimulated by fMLP, were significantly reduced (24 (sem 12) and 51 (sem 14) % of control) by 100 microm genistein and equol. P-selectin-induced aggregates were reduced to 19 (sem 6), 44 (sem 10) and 28 (sem 9) % of control by 100 microm genistein, daidzein and equol, respectively. Genistein, daidzein and equol also significantly reduced mixed platelet-PMN aggregates (IC50 4.0 (sem 0.9), 57 (sem 6) and 66 (sem 23) microm, respectively). In PMN challenged by fMLP or P-selectin, activation of Pyk2 was prevented by isoflavones. The cardioprotective effect of soya-containing food might be linked to reduction of PMN activation and PMN-platelet interaction, novel targets for the biological effects of soya isoflavones.
...
PMID:Inhibition by soya isoflavones of human polymorphonuclear leukocyte function: possible relevance for the beneficial effects of soya intake. 1784 35

Platelet and leukocyte activation has been demonstrated in polycythemia vera (PV) and essential thrombocythemia (ET), but such information is limited in primary myelofibrosis (PMF). Platelet, leukocyte, endothelial, and coagulation activation status was assessed in 26 PMF patients and compared with data from 22 age- and sex-matched healthy individuals. Study included flow cytometry assessment of platelet P-selectin expression [at baseline and after adenosine diphosphate (ADP), thrombin and arachidonic acid stimulation], platelet-neutrophil and platelet-monocyte complexes, and CD11b expression in neutrophils and monocytes. Additionally, soluble P-selectin, sCD40L, tissue factor, thrombomodulin, prothrombin fragment 1 + 2 (F1 + 2), and D-dimer were measured by enzyme-linked immunosorbent assays. The above parameters were correlated with the patients' clinical data and presence of the JAK2 V617F mutation. Compared with controls, PMF patients had increased baseline platelet activation, as shown by significantly higher levels of soluble and platelet P-selectin expression, and also higher percentages of platelet-monocyte complexes. Neutrophil and monocyte CD11b expression was significantly higher in patients with the JAK2 mutation than in those with wild-type allele or the controls. Endothelial and coagulation activation, as demonstrated by increased plasma levels of thrombomodulin and F1 + 2, was also found in PMF, with patients with the JAK2 mutation showing significantly higher values of F1 + 2 than those with wild-type allele. In conclusion, PMF patients have platelet, leukocyte, endothelial, and coagulation activation similar to that in PV and ET. CD11b overexpression and F1 + 2 are correlated with the presence of the JAK2 mutation.
...
PMID:Increased platelet, leukocyte, and coagulation activation in primary myelofibrosis. 1789 78

The present study was designed to explore the mechanisms involved in the anti-ischemic action of lumbrokinase (LK) in brain. The enzyme immunoassay, spectrofluorimeter and flow cytometry were used to detect the level of adenosine 3',5'-cyclic monophosphate (cAMP) and guanosine 3',5'-cyclic monophosphate (cGMP), the Ca(2+) mobilization, and human platelet surface antigen expression in order to elucidate the anti-platelet action involved in LK cerebroprotection. RT-PCR and western blot were used to identify the role of Intercellular adhesion molecule-1 (ICAM-1) and Janus Kinase1/Signal Transducers and Activators of Transcription1 (JAK1/STAT1) pathway in protecting brain against ischemic injury by anti-thrombosis and anti-apoptosis. Results showed that LK significantly potentiated the activity of adenylate cyclase (AC), increased the cAMP level in vivo, remarkably inhibited the rise of rat platelet intracellular Ca(2+) ([Ca(2+)](i)), and attenuated the expression of Glycoprotein IIB/IIIA (GPIIB/IIIA) and P-selectin in human platelet stimulated by thrombin in vitro. Furthermore, the expressions of ICAM-1 and JAK1/STAT1 were remarkably regulated by LK in Human Umbilical Vein Endothelial Cell (HUVEC) and ischemic cerebral tissues. These data indicated that the anti-ischemic activity of LK was due to its anti-platelet activity by elevating cAMP level and attenuating the calcium release from calcium stores, the anti-thrombosis action due to inhibiting of ICAM-1 expression, and the anti-apoptotic effect due to the activation of JAK1/STAT1 pathway.
...
PMID:Mechanisms of lumbrokinase in protection of cerebral ischemia. 1859 51

The present study shows that JAK2-STAT3 inflammatory signaling mediates thrombin-stimulated microglia activation. In rat primary microglia, thrombin rapidly activated JAK2 and induced phosphorylation of STAT3. In addition, thrombin increased transcription of the inflammation-associated genes tumor necrosis factor (TNF)-alpha, inducible nitric oxide synthase (iNOS), production of TNF-alpha, NO and induced neurodegeneration of dopaminergic neurons in mesencephalic cultures. AG490, a JAK inhibitor, markedly reduced activation of JAK2 and STAT3 in thrombin-treated microglia. AG490 also inhibited thrombin-induced transcription and expression of TNF-alpha, iNOS and/or NO release, moreover rescued dopaminergic neurons. These results suggest that JAK2-STAT3 signaling pathway plays a critical role in mediating thrombin-induced activation of microglia and degeneration of dopaminergic neurons.
...
PMID:JAK2-STAT3 signaling pathway mediates thrombin-induced proinflammatory actions of microglia in vitro. 1871 Jul 87

We used the thrombin generation assay to evaluate the hypercoagulable state according to JAK2(V617F) mutational status in essential thrombocythemia (ET) and polycythemia vera (PV) patients. Thrombin generation was determined in the presence and absence of activated protein C (APC), and APC resistance was expressed as normalized APC sensitivity ratio (nAPCsr). Tissue factor pathway inhibitor (TFPI), total and free protein S (PS), prothrombin (FII), factor V (FV), and neutrophil elastase were measured in plasma; CD11b was measured on neutrophils. Compared with normal controls, patients had a lower endogenous thrombin potential in the absence of APC but had a higher endogenous thrombin potential in the presence of APC, showing the occurrence of APC resistance. The nAPCsr increased in JAK2(V617F) carriers compared with noncarriers and was highest in JAK2(V617F) homozygous patients. FII, FV, free PS, and TFPI levels were reduced in patients, mainly in JAK2(V617F) carriers. Multiple regression analysis indicated the low free PS level as major determinant of the increased nAPCsr. Elastase was increased in patients and inversely correlated with free PS. In conclusion, these data indicate the occurrence of acquired APC resistance in ET and PV patients, probably because of a reduction in free PS levels. The APC-resistant phenotype is influenced by the JAK2(V617F) mutational load.
...
PMID:Thrombin generation and activated protein C resistance in patients with essential thrombocythemia and polycythemia vera. 1876 82

Platelet integrin alpha(IIb)beta(3) contains an acidic membrane distal motif, 1000LEEDDEEGE1008, in the cytoplasmic domain of the alpha(IIb) subunit. We showed that a lipid-modified peptide corresponding to the above region, palmitoyl-K-LEEDDEEGE (pal-K-1000-1008), is platelet permeable and has inhibited platelet aggregation induced by 0.4 U/ml of thrombin (IC50 = 164 microM). Moreover the peptide inhibited both Fibrinogen and PAC-1, binding to activated platelets. The non palmitoylated analog was inactive. A modified, scrambled acidic peptide (palmitoyl-K-GDDEELEEE), showed significant lower inhibitory activity than pal-K-1000-1008. A palmitoylated peptide corresponding to the membrane proximal cytoplasmic domain of alpha(IIb), 989KGVFFKR995 (pal-989-995), is known to specifically induce platelet aggregation. Pal-K-1000-1008 was an inhibitor of human washed platelet aggregation induced by pal-K-989-995 (IC50 = 15 microM). Moreover, pal-K-1000-1008 inhibited phosphorylation of ERK and FAK, two protein kinases involved in platelet activation and aggregation. Our results favour the assumption that the interaction of the membrane proximal sequence 989KGVFFKR995 of the cytoplasmic domain of alpha(IIb) with the acidic terminal 1000LEEDDEEGE1008 motif may be an important structural factor in platelet signaling, leading to platelet activation and aggregation.
...
PMID:A palmitoylated peptide, derived from the acidic carboxyl-terminal segment of the integrin alphaIIb cytoplasmic domain, inhibits platelet activation. 1897 62

The elevation of [cAMP](i) is an important mechanism of platelet inhibition and is regulated by the opposing activity of adenylyl cyclase and phosphodiesterase (PDE). In this study, we demonstrate that a variety of platelet agonists, including thrombin, significantly enhance the activity of PDE3A in a phosphorylation-dependent manner. Stimulation of platelets with the PAR-1 agonist SFLLRN resulted in rapid and transient phosphorylation of PDE3A on Ser(312), Ser(428), Ser(438), Ser(465), and Ser(492), in parallel with the PKC (protein kinase C) substrate, pleckstrin. Furthermore, phosphorylation and activation of PDE3A required the activation of PKC, but not of PI3K/PKB, mTOR/p70S6K, or ERK/RSK. Activation of PKC by phorbol esters also resulted in phosphorylation of the same PDE3A sites in a PKC-dependent, PKB-independent manner. This was further supported by the finding that IGF-1, which strongly activates PI3K/PKB, but not PKC, did not regulate PDE3A. Platelet activation also led to a PKC-dependent association between PDE3A and 14-3-3 proteins. In contrast, cAMP-elevating agents such as PGE(1) and forskolin-induced phosphorylation of Ser(312) and increased PDE3A activity, but did not stimulate 14-3-3 binding. Finally, complete antagonism of PGE(1)-evoked cAMP accumulation by thrombin required both G(i) and PKC activation. Together, these results demonstrate that platelet activation stimulates PKC-dependent phosphorylation of PDE3A on Ser(312), Ser(428), Ser(438), Ser(465), and Ser(492) leading to a subsequent increase in cAMP hydrolysis and 14-3-3 binding.
...
PMID:Protein kinase C-mediated phosphorylation and activation of PDE3A regulate cAMP levels in human platelets. 1926 11

Dasatinib is an oral potent adenosine triphosphate (ATP)-competitive inhibitor of BCR-ABL, cKIT, platelet-derived growth factor receptor, and SRC family kinases (SFKs), which has demonstrated high efficiency in patients with imatinib-resistant chronic myelogenous leukemia. Here, we show that dasatinib weakly affects platelet activation by thrombin or adenosine diphosphate but is a potent inhibitor of platelet signaling and functions initiated by collagen or FcgammaRIIA cross-linking, which require immunoreceptor tyrosine-based activation motif phosphorylation by SFKs. Accordingly, dasatinib treatment rapidly decreases the volume of thrombi formed under arterial flow conditions in whole blood from patients or mice perfused over a matrix of collagen. Moreover, treatment of mice with dasatinib increases the tail bleeding time in a dose-dependent manner. Interestingly, these effects are rapidly reversible after interruption of the treatment. Our data clearly demonstrate that, in contrast to imatinib, dasatinib affects platelet functions in vitro and in vivo, which has important implications in clinic and could explain increased risks of bleeding observed in patients. Moreover, dasatinib efficiently prevents platelet activation mediated by FcgammaRIIA cross-linking and by sera from patients with heparin-induced thrombocytopenia, suggesting that reversible antiplatelet agents acting as ATP-competitive inhibitors of SFKs may be of therapeutic interest in the treatment of this pathology.
...
PMID:The new tyrosine-kinase inhibitor and anticancer drug dasatinib reversibly affects platelet activation in vitro and in vivo. 1971 76

In addition to haemostasis, platelets mediate inflammation and clearance of bacteria from the bloodstream. As with platelet-platelet interactions, platelet-bacteria interactions involve cytoskeletal rearrangements and release of granular content. Stimulation of the immune Toll-like receptor 2 (TLR2) on the platelet surface, activates phosphoinositide-3-kinase (PI3K) and causes platelet activation and platelet-dependent thrombosis. It remains unknown if platelet activation by immune versus thrombotic pathways leads to the differential regulation of signal transduction, protein-protein interactions, and alpha-granule release, and the physiological relevance of these potential differences. We investigated these processes after immune versus thrombotic platelet stimulation. We examined selected signalling pathways and found that phosphorylation kinetics of Akt, ERK1/2 and p38 differed dramatically between agonists. Next, we investigated platelet protein-protein interactions by mass spectrometry (MS)-based proteomics specifically targeting cytosolic factor XIIIa (FXIIIa) because of its function as a cytoskeleton-crosslinking protein whose binding partners have limited characterisation. Four FXIIIa-binding proteins were identified, two of which are novel interactions: FXIIIa-focal adhesion kinase (FAK) and FXIIIa-gelsolin. The binding of FAK to FXIIIa was found to be altered differentially by immune versus thrombotic stimulation. Lastly, we studied the effect of thrombin versus Pam(3)CSK(4) stimulation on alpha-granule release and observed differential release patterns for selected granule proteins and decreased fibrin clot formation compared with thrombin. The inhibition of PI3K caused a decrease in protein release after Pam(3)CSK(4)- but not after thrombin-stimulation. In summary, stimulation of platelets by either thrombotic or immune receptors leads to markedly different signalling responses and granular protein release consistent with differential contribution to coagulation and thrombosis.
...
PMID:Immune versus thrombotic stimulation of platelets differentially regulates signalling pathways, intracellular protein-protein interactions, and alpha-granule release. 1957 74


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>

---