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:2.7.10.1 (ERK)
95,504 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

During the lyophilization process, formulations containing protein, bulking agent, or lyoprotectant form a dry product layer that can affect the transport of sublimed water vapor. We carried out an investigation of the primary drying segment of lyophilization to evaluate the relationship between the resistance to water vapor flow through the dried layer and the microstructure of the dried cake. Recombinant humanized antibody HER2 (rhuMAb HER2) formulated in trehalose was studied, as were protein-free formulations containing trehalose and sucrose. Sublimation rate and product temperature data were used to compute the resistance to mass transfer. Dried cake structure was examined by scanning electron microscopy and a novel fluorescence microscopy method. Collapse temperatures were determined by freeze-drying microscopy. Mass transfer resistance was found to decrease with increases in temperature for each material. Resistance also depended on composition, decreasing in the formulation series, rhuMAb HER2, trehalose, sucrose. The lyophilized material consisted of porous cakes, with a distinct denser region at the top. Formulation and temperature affected the microstructure of the dried cakes. The formulated trehalose and sucrose were seen, by both microscopy techniques, to possess small (2-20 microm) holes in their platelike structures after lyophilization. The quantity of holes was higher for material dried at higher temperature. The collapse temperature (Tc) of a material appeared to play a role in the process, as lower Tc was correlated with lower resistance and a greater extent of holes. Our results are consistent with the theory that lower resistance to water vapor flow in the primary drying stage of lyophilization may be due to small-scale product collapse.
...
PMID:Lyophilization of protein formulations in vials: investigation of the relationship between resistance to vapor flow during primary drying and small-scale product collapse. 1039 66

Neuropilin-1 (NRP1) is a receptor for two unrelated ligands with disparate activities, vascular endothelial growth factor-165 (VEGF165), an angiogenesis factor, and semaphorin/collapsins, mediators of neuronal guidance. To determine whether semaphorin/collapsins could interact with NRP1 in nonneuronal cells, the effects of recombinant collapsin-1 on endothelial cells (EC) were examined. Collapsin-1 inhibited the motility of porcine aortic EC (PAEC) expressing NRP1 alone; coexpressing KDR and NRP1 (PAEC/KDR/NRP1), but not parental PAEC; or PAEC expressing KDR alone. The motility of PAEC expressing NRP1 was inhibited by 65-75% and this inhibition was abrogated by anti-NRP1 antibody. In contrast, VEGF165 stimulated the motility of PAEC/KDR/NRP1. When VEGF165 and collapsin-1 were added simultaneously to PAEC/KDR/NRP1, dorsal root ganglia (DRG), and COS-7/NRP1 cells, they competed with each other in EC motility, DRG collapse, and NRP1-binding assays, respectively, suggesting that the two ligands have overlapping NRP1 binding sites. Collapsin-1 rapidly disrupted the formation of lamellipodia and induced depolymerization of F-actin in an NRP1-dependent manner. In an in vitro angiogenesis assay, collapsin-1 inhibited the capillary sprouting of EC from rat aortic ring segments. These results suggest that collapsin-1 can inhibit EC motility as well as axon motility, that these inhibitory effects on motility are mediated by NRP1, and that VEGF165 and collapsin-1 compete for NRP1-binding sites.
...
PMID:Neuropilin-1 mediates collapsin-1/semaphorin III inhibition of endothelial cell motility: functional competition of collapsin-1 and vascular endothelial growth factor-165. 1040 73

Neuropilin (NRP) is a 140 kDa membrane protein, with a large extracellular domain and a short cytoplasmic tail, that was isolated in 1987 from the optic tactum of Xenopus laevis. About 10 years after its isolation, NRP was identified as a receptor for semaphorin, a family of axonal chemorepellent proteins and for vascular endothelial growth factor (VEGF), a family of potent angiogenic factors. In the nervous system, NRP forms a high affinity semaphorin-binding complex with a receptor tyrosine kinase, plexin, that mediates semaphorin-induced growth cone collapse. On the endothelium, NRP is expressed together with KDR, a VEGF receptor tyrosine kinase. We have shown that NRP potentiated KDR-mediated endothelial cell migration and proliferation. Some tumor cells can express high levels of NRP, which is typically their only VEGF receptor, but do not seem to respond to VEGF directly. Possible use of NRP as a target for VEGF antagonists, in the context of antiangiogenic therapy, are described.
...
PMID:Neuropilin in the midst of cell migration and retraction. 1131 12

Peripheral nerve growth is regulated by the coordinated action of numerous external stimuli, including positively acting neurotrophin-derived growth cues and restrictive semaphorin cues. Here, we show that Semaphorin 3F (Sema 3F) can antagonize nerve growth factor (NGF)-stimulated TrkA (tyrosine receptor kinase A) signaling in sympathetic neurons, thereby apparently contributing to growth cone collapse. Sema 3F suppressed NGF-induced activation of the phosphatidylinositol 3 (PI3)-kinase-Akt and MEK (mitogen-activated protein kinase kinase)-ERK (extracellular signal-regulated kinase) pathways, both of which we show to be required to maintain growth cone structure. Sema 3F-induced growth cone collapse was partially reversed by sustained activation of the PI3-kinase and MEK pathways, which was achieved by overexpression of the Gab-1 (growth-associated binder 1) docking protein. These data indicate that a novel mechanism used by Sema 3F to collapse growth cones in sympathetic neurons is to dampen neurotrophin signaling, providing an intracellular mechanism for cross talk between positive and negative axon growth cues.
...
PMID:Semaphorin 3F antagonizes neurotrophin-induced phosphatidylinositol 3-kinase and mitogen-activated protein kinase kinase signaling: a mechanism for growth cone collapse. 1293 Jul 99

Understanding the detailed mechanisms of a chemotherapeutic agent action on cancer cells is essential for planning the clinical applications because drug effects are often tissue and cell type specific. This study set out to elucidate the molecular pathways of Taxol effects in human anaplastic thyroid cancer cells using as an experimental model four cell lines, ARO, KTC-2, KTC-3 (anaplastic thyroid cancer), and FRO (undifferentiated follicular cancer), and primary thyrocytes. All cell lines were sensitive to Taxol, although to different extent. In primary thyrocytes the drug displayed substantially lower cytotoxicity. In thyroid cancer cells, Taxol-induced changes characteristic to apoptosis such as poly (ADP-ribose) polymerase and procaspase cleavage and alteration of membrane asymmetry only within a narrow concentration range, from 6 to 50 nm. At higher concentration, other form(s) of cell death perhaps associated with mitochondrial collapse was observed. Low doses of Taxol enhanced Bcl2 phosphorylation and led to its degradation observed on the background of a sustained or increasing Bax level and accumulation of survivin and X-chromosome-linked inhibitor of apoptosis. c-jun-NH(2) terminal kinase activation was essential for the apoptosis in anaplastic thyroid cancer cells, whereas Raf/MAPK kinase/ERK and phosphatidylinositol-3-OH kinase/Akt were likely to comprise main survival mechanisms. Our results suggest an importance of cautious interpreting of biological effects of Taxol in laboratory studies and for determining optimal doses of Taxol to achieve the desired therapeutic effect in anaplastic thyroid cancers.
...
PMID:Molecular mechanisms of the effects of low concentrations of taxol in anaplastic thyroid cancer cells. 1504 68

Vascular endothelial growth factor (VEGF) displays neurotrophic and neuroprotective activities, but the mechanisms underlying these effects have not been defined. Neuropilin-1 (NP-1) is a receptor for VEGF165 and placental growth factor-2 (PlGF-2), but the role of NP-1 in VEGF-dependent neurotrophic actions is unclear. Dorsal root ganglion (DRG) neurons expressed high levels of NP-1 mRNA and protein, much lower levels of KDR, and no detectable Flt-1. VEGF165 and PlGF-2 promoted DRG growth cone formation with an effect similar to that of nerve growth factor, whereas the Flt-1-specific ligand, PlGF-1, and the KDR/Flt-4 ligand, VEGF-D, had no effect. The chemorepellent NP-1 ligand, semaphorin 3A, antagonized the response to VEGF and PlGF-2. The specific KDR inhibitor, SU5614, did not affect the anti-chemorepellent effects of VEGF and PlGF-2, whereas a novel, specific antagonist of VEGF binding to NP-1, called EG3287, prevented inhibition of growth cone collapse. VEGF stimulated prostacyclin and prostaglandin E2 production in DRG cultures that was blocked by inhibitors of cyclooxygenases; the anti-chemorepellent activities of VEGF and PlGF-2 were abrogated by cyclooxygenase inhibitors, and a variety of prostacyclin analogues and prostaglandins strikingly inhibited growth cone collapse. These findings support a specific role for NP-1 in mediating neurotrophic actions of VEGF family members and also identify a novel role for prostanoids in the inhibition of neuronal chemorepulsion.
...
PMID:Anti-chemorepulsive effects of vascular endothelial growth factor and placental growth factor-2 in dorsal root ganglion neurons are mediated via neuropilin-1 and cyclooxygenase-derived prostanoid production. 1512 2

The thrombin mutant D221A/D222K (ARK) does not bind Na+ and has interesting functional properties intermediate between those of the slow and fast forms of wild type. We solved the X-ray crystal structure of ARK bound at exosite I with a fragment of hirudin at 2.4-A resolution. The structure shows a slight collapse of the 186 and 220 loops into the Na+ binding site due to disruption of the Asp222:Arg187 ion-pair. The backbone O atoms of Arg221a and Lys224 are shifted into conformations that eliminate optimal interaction with Na+. A paucity of solvent molecules in the Na+ binding site is also noted, by analogy to what is seen in the structure of the slow form. These findings reinforce the crucial role of the Asp222:Arg187 ion-pair in stabilizing the fast form of thrombin.
...
PMID:Crystal structure of the thrombin mutant D221A/D222K: the Asp222:Arg187 ion-pair stabilizes the fast form. 1557 56

17beta-estradiol (17beta-E2) protects against H2O2-mediated depletion of intracellular ATP and lessens the degree of depolarization of mitochondrial membrane potential (DeltaPsi(m)) in cultured lens epithelial cells consequential to oxidative insult. We now report that 17beta-E2 acts as a positive regulator of the survival signal transduction pathway, MAPK which, in turn, acts to stabilize DeltaPsi(m) in effect, attenuating the extent of depolarization of mitochondrial membrane potential in the face of acute oxidative stress. The SV-40 viral transformed human cell line, HLE-B3 was treated with 17beta-E2 over a time course of 60 min and phosphorylation of ERK1/2 was analyzed by Western blot. ERK1/2 was phosphorylated within 5-15 min in the presence of 17beta-E2. Cell cultures were exposed to the MEK1/2 inhibitor, UO126, subsequent to H2O2+/-17beta-E2 treatment and the DeltaPsi(m) examined using JC-1, a potentiometric dye which serves as an indicator for the state of mitochondrial membrane potential. UO126 treatment attenuated ERK1/2 phosphorylation irrespective of whether estradiol was administered. Mitochondrial membrane depolarization resulting from H2O2 stress was substantially greater in the presence of UO126. The greater the extent of depolarization, the less effective 17beta-E2 treatment was in checking mitochondrial membrane depolarization, indicating that the relative degree of ERK phosphorylation influences mitochondrial stability with oxidative insult. The data support a positive correlation between 17beta-E2 stimulation of ERK1/2 phosphorylation and mitochondrial stabilization that would otherwise cause a complete collapse of DeltaPsi(m).
...
PMID:17beta-estradiol stimulates MAPK signaling pathway in human lens epithelial cell cultures preventing collapse of mitochondrial membrane potential during acute oxidative stress. 1605 Sep 86

A common limitation of using polymeric nanoparticles in aqueous suspension is due to their poor chemical and physical stability when conserved for a long time. Therefore, freeze drying of these colloidal systems is an alternative method to achieve long-term stability. Nanocapsules have thin and fragile shell structure, which may not resist to the stress of such process. The aim of this study is to investigate the formulation and process parameters in order to ensure the stability of polycaprolactone nanocapsules (PCL NC) by freeze drying. In this paper, we studied the freeze drying of PCL NC prepared by the emulsion-diffusion method and stabilized by poly(vinyl alcohol) (PVA). Different parameters have been tested throughout the freeze-thawing study including PVA and PCL concentration, cooling rate, cryoprotectant concentrations, nature of encapsulated oil and NC purification. On the other hand, nanocapsules have been freeze dried both before and after purification. Freeze dried purified PCL NC were characterized by particle size measurement, collapse temperature, T'g determination, scanning electron microscope observation, environmental scanning electron microscope imaging and residual humidity quantification. Finally, the effect of annealing on the NC stability and the sublimation rate has been well explored. The results suggest that PCL NC could be freeze dried without a cryoprotectant if the concentration of PVA stabilizer is sufficient (5%), while for the purified NC the addition of 5% of cryoprotectant seems to be necessary to ensure the stability of NC. The type of cryoprotectants had practically negligible effects on the size and the rehydration of freeze dried nanocapsules. The annealing process could accelerate the sublimation with the conservation of nanocapsules size.
...
PMID:A pilot study of freeze drying of poly(epsilon-caprolactone) nanocapsules stabilized by poly(vinyl alcohol): formulation and process optimization. 1632 53

Although bradykinin has been demonstrated to protect the heart at reperfusion, the detailed cellular and molecular mechanisms that mediate the protection remain elusive. Here we aimed to determine whether bradykinin protects the heart at reperfusion by modulating the mitochondrial permeability transition pore (mPTP) opening through glycogen synthase kinase 3beta (GSK-3beta). Bradykinin given at reperfusion reduced infarct size in isolated rat hearts subjected to 30 min regional ischemia followed by 2 h of reperfusion. The infarct-limiting effect of bradykinin was reversed by atractyloside, an opener of the mPTP, suggesting that bradykinin may protect the heart at reperfusion by modulating the mPTP opening. In support of this observation, bradykinin prevented the collapse of mitochondrial membrane potential (DeltaPsi(m)), an index of the mPTP opening. Bradykinin increased GSK-3beta phosphorylation at reperfusion, and the selective inhibitor of GSK-3beta SB216763 reduced infarct size and prevented the loss of DeltaPsi(m) by mimicking the effect of bradykinin. The effect of bradykinin on GSK-3beta phosphorylation was blocked by wortmannin and LY294002, and bradykinin increased Akt phosphorylation at reperfusion. Further experiments showed that the MEK inhibitor PD98059 prevented the effect of bradykinin on GSK-3beta. However, the mTOR/p70s6K pathway inhibitor rapamycin did not alter bradykinin-induced GSK-3beta phosphorylation and bradykinin failed to alter phosphorylation of either mTOR or p70s6K at reperfusion. Taken together, these data suggest that bradykinin protects the heart at reperfusion by modulating the mPTP opening through inhibition of GSK-3beta. The PI3-kinase/Akt pathway and ERK, but not the mTOR/p70s6K pathway account for the suppression of GSK-3beta by bradykinin.
...
PMID:Bradykinin prevents reperfusion injury by targeting mitochondrial permeability transition pore through glycogen synthase kinase 3beta. 1651 18


1 2 3 4 5 6 7 8 Next >>

---