Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.10.1 (ERK)
 95,504 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The expression of receptors belonging to the epidermal growth factor receptor subfamily has been largely studied these last years in epithelial cells mainly as involved in cell proliferation and malignant progression. Although much work has focused on the role of these growth factor receptors in the differentiation of a variety of tissues, there is little information in regards to normal stromal cells. We investigated erbB2 expression in the murine fibroblast cell line Swiss 3T3L1, which naturally or hormonally induced undergoes adipocyte differentiation. We found that the Swiss 3T3-L1 fibroblasts express erbB2, in addition to EGFR, and in a quantity comparable to or even greater than the breast cancer cell line T47D. Proliferating cells increased erbB2 and EGFR levels when reaching confluence up to 4- and 10-fold, respectively. This expression showed a significant decrease when growth-arrested cells were stimulated to differentiate with dexamethasone and isobutyl-methylxanthine. Differentiated cells presented a decreased expression of both erbB2 and EGFR regardless of whether the cells were hormonally or spontaneously differentiated. EGF stimulation of serum-starved cells increased erbB2 tyrosine phosphorylation and retarded erbB2 migration in SDS-PAGE, suggesting receptor association and activation. Heregulin-alpha1 and -beta1, two EGF related factors, had no effect on erbB2 or EGFR phosphorylation. Although 3T3-L1 cells expressed heregulin, its specific receptors, erbB3 and erbB4, were not found. This is the first time in which erbB2 is reported to be expressed in an adipocytic cell line which does not depend on non EGF family growth factors (thyroid hormone, growth hormone, etc.) to accomplish adipose differentiation. Since erbB2 and EGFR expression were downmodulated as differentiation progressed it is conceivable that a mechanism of switching from a mitogenic to a differentiating signaling pathway may be involved, through regulation of the expression of these growth factor receptors.
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PMID:ErbB2 and EGFR are downmodulated during the differentiation of 3T3-L1 preadipocytes. 1452 90

The interaction of vessel endothelial cell growth factor (VEGF) and its receptors (flt-1, FLK-1/KDR) regulates tumor angiogenesis. Therefore, blocking the binding of VEGF and the corresponding receptor has become critical for antitumor angiogenesis biological therapy. Our study extracted sFLK-1 fragment from embryo mouse liver using RT-PCR, recombined it to retrovirus vector, and transfected it to tumor cell lines (S180 and B16) by the liposome mediated method, then we observed the biological behavior of transgenic cells in vivo. The results are: (1) Fragment (1034 bp) was extracted from E9, E11 embryo mouse liver tissue, which was identified by sequence analysis. (2) This fragment was cloned to retrovirus vector (PLXSN vector), which was further transfected to tumor cells lines (S180 and B16). SDS-PAGE indicated the suspension of transgenic cells present sVEGFR-2(sFLK-1) fragment; Western blot identified it. (3) In vivo study showed that the weight and size of tumor in the group of transgenic cells were smaller than in control groups. Microvessel density (MVD) and FLK-1 expression were obviously different between transgenic and control groups, but there were no differences in VEGF expression between transgenic and control groups. In short, the isolated soluble VEGFR2 fragment transfected to tumor cells can be secreted to extracellular suspension and can inhibit tumor angiogenesis in vivo.
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PMID:In vivo inhibition of tumor angiogenesis by a soluble VEGFR-2 fragment. 1501 Feb 91

Adipose tissue is a primary target of insulin, but knowledge about insulin signalling in human adipocytes is limited. We developed an electroporation technique for transfection of primary human adipocytes with a transfection efficiency of 15% +/- 5 (mean +/- S.D.). Human adipocytes were co-transfected with a mutant of IRS-3 (all four potential PI3-kinase binding motifs mutated: IRS-3F4) and HA-tagged protein kinase B (HA-PKB/Akt). HA-PKB/Akt was immunoprecipitated from cell lysates with anti-HA antibodies, resolved with SDS-PAGE, and immunoblotted with phospho-specific antibodies. We found that IRS-3F4 blocked insulin stimulation of HA-PKB/Akt phosphorylation and in further analyses also translocation of recombinant HA-tagged glucose transporter to the plasma membrane. IRS-3F4 also blocked insulin-induced activation of the transcription factor Elk-1. Our results demonstrate the critical importance of IRS for metabolic as well as mitogenic signalling by insulin. This method for transfection of primary human adipocytes will be useful for studying insulin signalling in human adipocytes with molecular biological techniques.
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PMID:Expression of a mutant IRS inhibits metabolic and mitogenic signalling of insulin in human adipocytes. 1522 27

Neural stem cells (NSCs) are multipotential progenitor cells that have self-renewal activity. Since the fates of the NSCs in situ depend on their niche containing growth factors and cytokines, we performed surface enhanced laser desorption/ionization time-of flight mass spectrometry (SELDI-TOF-MS) to screen for differentially secreted proteins in conditioned medium of neural stem cells and compared with that of NIH3T3 cells. A 15.3-kDa protein detected only in the conditioned medium of neural stem cells was determined as pleiotrophin (PTN) by SELDI-TOF-MS and ProteinChip-tandem MS systems. Identification of pleiotrophin was further confirmed by one-dimensional SDS gel electrophoresis and Edman degradation analysis. The mRNA transcripts of PTN and its receptors [receptor protein tyrosine phosphatase (RPTP) beta/zeta, N-syndecan and anaplastic lymphoma kinase (ALK)] were detected in neurosphere, suggesting that pleiotrophin signaling systems are present in the neural stem cells and are involved in the modulation of fate of neural stem cells.
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PMID:Identification of pleiotrophin in conditioned medium secreted from neural stem cells by SELDI-TOF and SELDI-tandem mass spectrometry. 1535 7

IL-2 stimulation of T lymphocytes induces the tyrosine phosphorylation and adaptor function of the insulin receptor substrate/Grb2-associated binder (Gab) family member, Gab2. In addition, Gab2 undergoes a marked decrease in its mobility in SDS-PAGE, characteristic of migration shifts induced by serine/threonine phosphorylations in many proteins. This migration shift was strongly diminished by treating cells with the MEK inhibitor U0126, indicating a possible role for ERK in Gab2 phosphorylation. Indeed, ERK phosphorylated Gab2 on a consensus phosphorylation site at serine 623, a residue located between tyrosine 614 and tyrosine 643 that are responsible for Gab2/Src homology 2 domain-containing tyrosine phosphatase (SHP)-2 interaction. We report that pretreatment of Kit 225 cells with U0126 increased Gab2/SHP-2 association and tyrosine phosphorylation of SHP-2 in response to IL-2, suggesting that ERK phosphorylation of serine 623 regulates the interaction between Gab2 and SHP-2, and consequently the activity of SHP-2. This hypothesis was confirmed by biochemical analysis of cells expressing Gab2 WT, Gab2 serine 623A or Gab2 tyrosine 614F, a mutant that cannot interact with SHP-2 in response to IL-2. Activation of the ERK pathway was indeed blocked by Gab2 tyrosine 614F and slightly increased by Gab2 serine 623A. In contrast, STAT5 activation was strongly enhanced by Gab2 tyrosine 614F, slightly reduced by Gab2 WT and strongly inhibited by Gab2 serine 623A. Analysis of the rate of proliferation of cells expressing these mutants of Gab2 demonstrated that tyrosine 614F mutation enhanced proliferation whereas serine 623A diminished it. These results demonstrate that ERK-mediated phosphorylation of Gab2 serine 623 is involved in fine tuning the proliferative response of T lymphocytes to IL-2.
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PMID:Phosphorylation of Grb2-associated binder 2 on serine 623 by ERK MAPK regulates its association with the phosphatase SHP-2 and decreases STAT5 activation. 1535 45

In this paper, the N-terminus of glycoprotein-41, the HIV-1 fusion peptide, was studied by molecular dynamics simulations in an explicit sodium dodecyl sulfate micelle. The simulation provides a detailed picture of the equilibrium structure and peptide stability as it interacts with the micelle. The equilibrium location of the peptide shows the peptide at the surface of the micelle with hydrophobic residues interacting with the micelle's core. At equilibrium, the peptide adopts an alpha-helical structure from residues 5-16 and a type-1 beta-turn from 17-20 with the other residues exhibiting more flexible conformations. The primary hydrophobic interactions with the micelle are from the leucine and phenylalanine residues (Leu-7, Phe-8, Leu-9, Phe-11, Leu-12) while the alanine and glycine residues (Ala-1, Gly-3, Gly-5, Ala-6, Gly-10, Gly-13, Ala-14, Ala-15, Gly-16, Gly-10, Ala-21) interact favorably with water molecules. The results suggest that Phe-8, part of the highly conserved FLG motif of the fusion peptide, plays a key role in the interaction of the peptide with membranes. Our simulations corroborate experimental investigations of the fusion peptide in SDS micelles, providing a high-resolution picture that explains the experimental findings.
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PMID:Simulation of the N-terminus of HIV-1 glycoprotein 41000 fusion peptide in micelles. 1563 57

A 35 kDa protein present in mammary tumors from Neu/ErbB2 transgenic mice was detected on the basis of its cross-reactivity with a phosphoserine-specific antibody against the transcription factor FKHR. To isolate this protein from cytosolic extracts derived from human breast carcinoma cells, we used free-flow electrophoresis in the first dimension to separate proteins according to their charge, followed by reversed-phase high-performance liquid chromatography (RP-HPLC) in the second and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) in the third dimension. Tryptic digests of Coomassie-stained bands were analyzed by nano-spray ionization-quadrupole quadrupole-time of flight-mass spectrometry identifying StarD10, a START domain containing protein, which cross-reacted with the anti-phospho-FKHR antibody. The site of phosphorylation was identified in immunoaffinity purified Flag-tagged StarD10 from 293T cells transiently expressing this protein. Tryptic phosphopeptides were enriched by immobilized metal affinity chromatography (IMAC) and StarD10 Ser-259-phosphate was identified by tandem mass spectrometry. Thus, free-flow electrophoresis is a powerful high-capacity complementary technique to RP-HPLC and SDS-PAGE for the purification of proteins from complex cell lysates.
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PMID:Breast cancer protein StarD10 identified by three-dimensional separation using free-flow electrophoresis, reversed-phase high-performance liquid chromatography, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. 1570 44

The epidermal growth factor receptors (erbB) constitute an important class of single pass transmembrane receptors involved in the transduction of signals important for cell proliferation and differentiation. Receptor association is a key event in the signal transduction process, but the molecular basis of this interaction is not fully understood. Previous biochemical and genetic studies have suggested that the single transmembrane helices of these receptor proteins might play a role in stabilizing the receptor complexes. To determine if the erbB transmembrane domains could provide a driving force to stabilize the receptor dimers, we carried out a thermodynamic study of these domains expressed as C-terminal fusion proteins with staphylococcal nuclease. Similar fusion constructs have been used successfully to investigate the oligomerization and association thermodynamics of a number of transmembrane sequences, including that of glycophorin A. Using SDS-PAGE analysis and sedimentation equilibrium analytical ultracentrifugation, we do not find strong, specific homo or hetero-interactions between the transmembrane domains of the erbB receptors in micellar solutions. Our results indicate that any preferential interactions between these domains in micellar solutions are extremely modest, of the order of 1 kcal mol(-1) or less. We applied a thermodynamic formalism to assess the effect of weakly interacting TM segments on the behavior of a covalently attached soluble domain. In the case of the ligand-bound EGFR ectodomain, we find that restriction of the ectodomain to the micellar phase by a hydrophobic TM, even in the absence of strong specific interactions, is largely sufficient to account for the previously reported increase in dimerization affinity.
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PMID:The transmembrane domains of ErbB receptors do not dimerize strongly in micelles. 1576 68

A new lectin with the potent mitogenic and in vitro anti-proliferative activity was isolated from the tubers of a wild monocotyledonous plant Sauromatum venosum (Schott), from the family Araceae, by affinity chromatography on the asialofetuin linked amino-activated silica beads. The apparent native molecular mass of S. venosum lectin (SVL), as determined by gel filtration chromatography, was 54 kDa. In HPLC, size exclusion and cation exchange chromatography, SVL gave a single peak and also a single band of 13.5 kDa in SDS-PAGE, pH 8.3, under reducing and non-reducing conditions, indicating that the lectin is composed of four identical subunits. S. venosum lectin agglutinated rabbit, rat, sheep and guinea pig erythrocytes but reacted with goat erythrocytes after the neuraminidase treatment. However, SVL was unable to agglutinate human ABO blood group erythrocytes even after treatment with neuraminidase. SVL was inhibited by N-acetyl-D-Lactosamine (LacNAc), which is an important marker in various carcinomas and a complex desialylated glycoprotein, asialofetuin. The amino acid composition showed that lectin contained a high amount of aspartic acid and glycine but totally devoid of cysteine. However, trace amounts of methionine was present. The lectin showed a potent mitogenic response towards BALB/c splenocytes and human lymphocytes. As the mitogenic stimulation was more than that of Con A, a standard well-known plant mitogen and the response of this lectin was almost double than that of Con A. This lectin is endowed with proliferation of T cells as revealed by IL-2 bioassay but showed no production of immunoglobulins thus indicating the non-stimulation of B cells. SVL significantly inhibited the proliferation of murine cancer cell-lines, i.e., WEHI-279 to 84.6%, J774 to 81%, P388D1 to 74% and A-20 to 47%. In addition, the in vitro anti-proliferative activity of SVL was also evaluated against nine human cancer cell lines representing different organs and tissues namely, T-47D (breast), SiHa (cervix), SK-N-MC (CNS), SK-N-SH (CNS), SW-620 (colon), HT-29 (colon), HEP-2 (liver), OVCAR-5 (ovary) and PC-3 (prostate). SVL showed a significant inhibition towards the entire cell lines except the cell lines from CNS, which showed partial response in comparison to a standard anticancer drug adriamycin which was used at a concentration of 5 x 10(-5) M. Thus the anti-proliferative ability of SVL may be helpful in identification of new lectin probes that can lead to better understanding in the detection and study of certain types of cancer.
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PMID:Mitogenic and anti-proliferative activity of a lectin from the tubers of Voodoo lily (Sauromatum venosum). 1578 50

The superantigen,such as staphylococcal enterotoxins, had been identified as possible anti-cancer molecules in many reports. In this paper, we cloned the entA gene encoding Staphylococcal enterotoxin A from the genomic DNA of Staphylococcus aureus(ATCC13565) by PCR, the sequence cloned was accordance with that reported in Genebank. The entA gene could be expressed effectively after inserted into plasmid pET-22b( + ), The rSEA was expressed as inclusion bodies when induced by IPTG at 37 degrees C and became soluble after induced at low temperature, the soluble part is about 55% of total rSEA products. Only one band was detected by western-blotting in expression product of BL-21 (DE3) with pET-SEA. The soluble rSEA was purified by Ni2+ chelating sepharose column. No other protein except rSEA was seen in SDS-PAGE gel stained by both Coomassie brilliant blue and silver salt, which showed that the rSEA was purified effectively. Homology modeling of rSEA determined the structure change was conducted, which indicated there was no apparent structure change between rSEA and native SEA. This result was also confirmed by proliferation assay of PBMC, for the rSEA could induced proliferation of PBMC as effectively as native SEA. The increasing anti-tumor activity of rSEA was also detected after the spleen cell activated in vivo by rSEA, which was accordance with others reports. This work paved the way for the further study of anti-cancer with rSEA.
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PMID:[Gene cloning, soluble expression and activity analysis of rSEA]. 1596 54


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