| 1. |
- Göransson, Olga, et al.
(författare)
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Ser-474 is the major target of insulin-mediated phosphorylation of protein kinase B beta in primary rat adipocytes.
- 2002
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Ingår i: Cellular Signalling. - 1873-3913. ; 14:2, s. 175-82
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Tidskriftsartikel (refereegranskat)abstract
- The mechanism of activation for protein kinase B (PKB), an important target for insulin signaling, has been scarcely investigated in primary cells. In this study, we have characterized the insulin-induced phosphorylation and activation of PKB beta in primary rat adipocytes. Insulin stimulation resulted in a translocation of PKB beta from cytosol to membranes, and phosphorylation and activation of PKB beta. Phosphoamino acid analysis and phosphopeptide mapping demonstrated that the phosphorylation occurred mainly on serines, also when using calyculin A, and that these were localized within one major phosphopeptide. Radiosequencing showed that the radioactivity was released in Cycle No. 7. In addition, the peptide was specifically immunoprecipitated from a tryptic digest of PKB beta using the anti-phospho-PKB (Ser-473) antibody. Taken together, these results show that rat adipocyte PKB beta mainly is phosphorylated on Ser-474 in response to insulin stimulation, in contrast to previous studies in human embryonic kidney (HEK) 293 cells demonstrating, in addition, phosphorylation of Thr-309.
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| 2. |
- Simonsson, Per, et al.
(författare)
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Bradykinin effects on phospholipid metabolism and its relation to arachidonic acid turnover in neuroblastoma x glioma hybrid cells (NG 108-15)
- 1989
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Ingår i: Cellular Signalling. - : Elsevier BV. - 1873-3913 .- 0898-6568. ; 1:6, s. 587-598
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Tidskriftsartikel (refereegranskat)abstract
- In neuroblastoma x glioma hybrid cells (NG 108-15) labelled with [32P]-trisodium phosphate, [3H]-inositol and [14C]-arachidonic acid, bradykinin stimulated the hydrolysis of phosphatidylinositol 4,5-bisphosphate (PIP2) while it had no effect on the release of [14C]-arachidonic acid (AA). The effect on PIP2 was time- and dose-dependent with a maximal effect on [3H]-inositol- and [32P]-labelled cells after 10-30 s of stimulation with 10(-6) M bradykinin. However, the hydrolysis of [14C]-AA labelled PIP2 was delayed compared to the effect on [3H]- and [14C]-PIP2 and was not detectable until after 60 s of stimulation. Bradykinin stimulation resulted in an increased formation of [3H]-inositol phosphates (IP) and [32P]- and [14C]-phosphatidic acid (PA) but the time course for PA formation did not follow the time-course for PIP2 hydrolysis. A reduced labelling of [32P]- and [14C]-phosphatidylcholine was also found in stimulated cells suggesting that PA may derive from other sources than PIP2. In conclusion, our results indicate that bradykinin activates phospholipase C, but not phospholipase A2, in NG 108-15 cells.
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| 3. |
- Aifa, Sami, et al.
(författare)
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Interactions between the juxtamembrane domain of the EGFR and calmodulin measured by surface plasmon resonance
- 2002
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Ingår i: Cellular Signalling. - 0898-6568 .- 1873-3913. ; 14:12, s. 1005-1013
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Tidskriftsartikel (refereegranskat)abstract
- One early response to epidermal growth factor receptor (EGFR) activation is an increase in intracellular calcium. We have used surface plasmon resonance (SPR) to study real-time interactions between the intracellular juxtamembrane (JM) region of EGFR and calmodulin. The EGFR-JM (Met644-Phe688) was expressed as a GST fusion protein and immobilised on a sensor chip surface. Calmodulin specifically interacts with EGFR-JM in a calcium-dependent manner with a high on and high off rate. Chemical modification of EGFR-JM by using arginine-selective phenylglyoxal or deletion of the basic segment Arg645-Arg657 inhibits the interaction. Phosphorylation of EGFR-JM by protein kinase C (PKC) or glutamate substitution of Thr654 inhibits the interaction, suggesting that PKC phosphorylation electrostatically interferes with calmodulin binding to basic arginine residues. Calmodulin binding was also inhibited by suramin. Our results suggest that EGFR-JM is essential for epidermal growth factor (EGF)-mediated calcium-calmodulin signalling and for signal integration between other signalling pathways.
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| 4. |
- Andersson, Tony, 1973-, et al.
(författare)
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Phosphoinositide 3-kinase is involved in Xenopus and Labrus melanophore aggregation
- 2003
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Ingår i: Cellular Signalling. - 0898-6568 .- 1873-3913. ; 15:12, s. 1119-1127
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Tidskriftsartikel (refereegranskat)abstract
- Melanophores are pigmented cells capable of quick colour changes through coordinated transport of their intracellular pigment granules. We demonstrate the involvement of phosphoinositide 3-kinase (PI3-K) in Xenopus and Labrus aggregation by the use of the PI3-K inhibitor, LY-294002. In Xenopus, wortmannin-insensitive PI3-K was found to be essential for the aggregation, mitogen-activated protein kinase (MAPK) activation and tyrosine phosphorylation of a 280-kDa protein, and for the maintenance of low cyclic adenosine 3':5'-monophosphate (cAMP) during the aggregated state. Pre-aggregated cells disperse completely to LY-294002 at 50-100 muM, involving a transient elevation in cAMP due to adenylate cyclase (AC) stimulation or to inhibition of cyclic nucleotide phosphodiesterase (PDE). The inactive analogue LY-303511 did not induce dispersion at the same concentrations. PDE4 and/or PDE2 was found to be involved in melanosome aggregation. The similar kinetics of LY-294002 and various PDE inhibitors indicates that the elevation of cAMP might be due to inhibition of PDE. In Labrus melanophores, LY-294002 had a less dramatic effect, probably due to less dependence on PDE in regulation of cAMP levels. In Xenopus aggregation, we suggest that melatonin stimulation of the Mel1c receptor via G(betagamma) activates PI3-K that, directly or indirectly via MAPK, activates PDE. (C) 2003 Elsevier Inc. All rights reserved.
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| 5. |
- Lavergne, Corinne, et al.
(författare)
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Control of SHB gene expression by protein phosphorylation
- 1996
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Ingår i: Cellular Signalling. - : Elsevier BV. - 0898-6568 .- 1873-3913. ; 8:1, s. 55-58
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Tidskriftsartikel (refereegranskat)abstract
- To increase our understanding of the role of the Src homology 2 (SH2) domain-containing protein Shb in the mitogenic signal transduction, Shb mRNA contents were determined in the fibroblast-like NIH3T3 cells and the insulin producing βTC-1 cells under various conditions. In NIH3T3 cells, the serine/ threonine phosphatase inhibitor okadaic acid and the tyrosine kinase inhibitor genistein increased Shb mRNA contents, the protein kinase C activating phorbol ester 12-O-tetradecanoyl 13-acetate (TPA) decreased the Shb mRNA content, whereas the tyrosine kinase inhibitor tyrphostin 25 and the mitogen platelet-derived growth factor (PDGF-BB) had no effect. In βTC-1 cells, okadaic acid and genistein increased the Shb mRNA content, whereas tyrphostin 25 and serum were without effect. Okadaic acid and genistein decreased the rates of βTC-1 cell DNA synthesis. It is concluded that expression of the SHB gene is under a complex mode of regulation involving at least three different protein kinases. As a consequence of this, it is likely that SHB gene expression is significantly modulated by conditions of specific activation of certain pathways, whereas its expression appears little influenced by serum and a mitogen.
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| 6. |
- Söderholm, Helena, 1969-, et al.
(författare)
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Activation of Ras, Raf-1 and protein kinase C in differentiating human neuroblastoma cells after treatment with phorbolester and NGF
- 2001
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Ingår i: Cellular Signalling. - : Elsevier. - 0898-6568 .- 1873-3913. ; 13:2, s. 95-104
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Tidskriftsartikel (refereegranskat)abstract
- The human neuroblastoma cell line SH-SY5Y/TrkA differentiates in vitro and acquires a sympathetic phenotype in response to phorbolester (activator of protein kinase C, PKC) in the presence of serum or growth factors, or nerve growth factor (NGF). We have now investigated to what extent phorbolester and NGF cause activation of Ras and Raf-1 and the involvement of PKC in this response in differentiating SH-SY5Y/TrkA cells. NGF stimulated increased accumulation of Ras-GTP and a threefold activation of Raf-1. In contrast, 12-O-tetradecanoylphorbol-13-acetate (TPA) had no effect on the amount of Ras-GTP but led to a smaller activation of Raf-1. NGF caused a limited increase in phosphorylation of Raf-1 compared with TPA, and NGF-induced Raf activity was independent of PKC. Analysis of phosphorylation of the endogenous PKC substrate myristoylated alanine-rich C-kinase substrate (MARCKS), and of subcellular distribution of PKC-alpha, -delta, and -epsilon revealed that NGF only caused a very small activation of PKC in SH-SY5Y/TrkA cells. The results identify Raf-1 as a target for both TPA- and NGF-induced signals in differentiating SH-SY5Y/TrkA cells and demonstrate that signalling to Raf-1 was mediated via distinct mechanisms.
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| 7. |
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| 8. |
- Attarha, Sanaz, et al.
(författare)
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Mast cells modulate proliferation, migration and sternness of glioma cells through downregulation of GSK3 beta expression and inhibition of STAT3 activation
- 2017
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Ingår i: Cellular Signalling. - : Elsevier BV. - 0898-6568 .- 1873-3913. ; 37, s. 81-92
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Tidskriftsartikel (refereegranskat)abstract
- Glioblastoma (GBM) heterogeneity is the main obstacle to efficient treatment due to the existence of sub population of cells with increased tumorigenicity and network of tumor associated parenchymal cells in the tumor microenvironment. We previously demonstrated that mast cells (MCs) infiltrate mouse and human gliomas in response to variety of signals in a glioma grade-dependent manner. However, the role of MCs in glioma development and the mechanisms behind MCs-glioma cells interaction remain unidentified. In the present study, we show that MCs upon activation by glioma cells produce soluble factors including IL-6, which are documented to be involved in cancer-related activities. We observe 'tumor educated' MCs decrease glioma cell proliferation and migration, reduce self-renewal capacity and expression of stemness markers but in turn promote glioma cell differentiation. 'Tumor educated' MC derived mediators exert these effects via inactivation of STAT3 signaling pathway through GSK3 beta down-regulation. We identified 'tumor educated' MC derived IL-6 as one of the contributors among the complex mixture of MCs mediators, to be partially involved in the observed MC induced biological effect on glioma cells. Thus, MC mediated abolition of STAT3 signaling hampers glioma cell proliferation and migration by suppressing their stemness and inducing differentiation via down-regulation of GSK3 beta expression. Targeting newly identified inflammatory MC-STAT3 axis could contribute to patient tailored therapy and unveil potential future therapeutic opportunities for patients.
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| 9. |
- Batool, Tahira, et al.
(författare)
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Upregulated BMP-Smad signaling activity in the glucuronyl C5-epimerase knock out MEF cells
- 2019
-
Ingår i: Cellular Signalling. - : Elsevier. - 0898-6568 .- 1873-3913. ; 54, s. 122-129
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Tidskriftsartikel (refereegranskat)abstract
- Glucuronyl C5-epimerase (Hsepi) catalyzes the conversion of glucuronic acid to iduronic acid in the process of heparan sulfate biosynthesis. Targeted interruption of the gene, Glce,in mice resulted in neonatal lethality with varied defects in organ development. To understand the molecular mechanisms of the phenotypes, we used mouse embryonic fibroblasts (MEF) as a model to examine selected signaling pathways. Our earlier studies found reduced activities of FGF-2, GDNF, but increased activity of sonic hedgehog in the mutant cells. In this study, we focused on the bone morphogenetic protein (BMP) signaling pathway. Western blotting detected substantially elevated endogenous Smad1/5/8 phosphorylation in the Hsepi mutant (KO) MEF cells, which is reverted by re-expression of the enzyme in the KO cells. The mutant cells displayed an enhanced proliferation and elevated alkaline phosphatase activity, marking higher differentiation, when cultured in osteogenic medium. The high level of Smad1/5/8 phosphorylation was also found in primary calvarial cells isolated from the KO mice. Analysis of the genes involved in the BMP signaling pathway revealed upregulation of a number of BMP ligands, but reduced expression of several Smads and BMP antagonist (Grem1) in the KO MEF cells. The results suggest that Hsepi expression modulates BMP signaling activity, which, at least partially, is associated with defected molecular structure of heparan sulfate expressed in the cells.
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| 10. |
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| 11. |
- Berggreen, Christine, et al.
(författare)
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cAMP-elevation mediated by β-adrenergic stimulation inhibits salt-inducible kinase (SIK) 3 activity in adipocytes.
- 2012
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Ingår i: Cellular Signalling. - : Elsevier BV. - 1873-3913 .- 0898-6568. ; 24:9, s. 1863-1871
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Tidskriftsartikel (refereegranskat)abstract
- Salt-inducible kinase (SIK) 3 is a virtually unstudied, ubiquitously expressed serine/threonine kinase, belonging to the AMP-activated protein kinase (AMPK)-related family of kinases, all of which are regulated by LKB1 phosphorylation of a threonine residue in their activation (T)-loops. Findings in adrenal cells have revealed a role for cAMP in the regulation of SIK1, and recent findings suggest that insulin can regulate an SIK isoform in Drosophila. As cAMP has important functions in adipocytes, mainly in the regulation of lipolysis, we have evaluated a potential role for cAMP, as well as for insulin, in the regulation of SIK3 in these cells. We establish that raised cAMP levels in response to forskolin and the β-adrenergic receptor agonist CL 316,243 induce a phosphorylation of SIK3 in HEK293 cells and primary adipocytes. This phosphorylation coincides with increased 14-3-3 binding to SIK3 in these cell types. Our findings also show that cAMP-elevation results in reduced SIK3 activity in adipocytes. Phosphopeptide mapping and site-directed mutagenesis reveal that the cAMP-mediated regulation of SIK3 appears to depend on three residues, T469, S551 and S674, that all contribute to some extent to the cAMP-induced phosphorylation and 14-3-3-binding. As the cAMP-induced regulation can be reversed with the protein kinase A (PKA) inhibitor H89, and a role for other candidate kinases, including PKB and RSK, could be excluded, we believe that PKA is the kinase responsible for SIK3 regulation in response to elevated cAMP levels. Our findings of cAMP-mediated regulation of SIK3 suggest that SIK3 may mediate some of the effects of this important second messenger in adipocytes.
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| 12. |
- Bergström Lind, Sara, et al.
(författare)
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Toward a comprehensive characterization of the phosphotyrosine proteome
- 2011
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Ingår i: Cellular Signalling. - : Elsevier BV. - 0898-6568 .- 1873-3913. ; 23:8, s. 1387-1395
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Tidskriftsartikel (refereegranskat)abstract
- Tyrosine phosphorylation (pTyr) regulates important cell functions and plays a key role in carcinogenesis. The purpose of this study was to perform a comprehensive study of the phosphotyrosine proteome. Immunoaffinity enriched pTyr proteins and peptides from K562 leukemia cells were analyzed with high-resolving liquid chromatography mass spectrometry. Two different antibodies selective for the pTyr modification were used in repeated enrichments to identify as many pTyr peptides as possible. Stringent verification of putative pTyr sites was performed to assure high reliability in the subsequent biological interpretation of the data. Identified pTyr proteins were subjected to pathway analysis by using different analytical tools. In total, 294 pTyr peptides belonging to 217 pTyr proteins were identified, 15 of which had not previously been reported to be modified by pTyr. The pTyr proteins were clustered in six major groups based on the biological functions "cellular signaling", "cell motility and shape", "cell cycle process", "transport", "RNA processing" and "protein processing". The pTyr proteins were mainly positioned in the following cellular compartments: cytoplasm, cytoskeleton, nucleus and ribonucleoprotein complexes. An interesting finding was that many proteins were related to RNA processing and were found to be heterogeneous nuclear ribonucleoproteins. Also, more than half of the novel pTyr proteins were localized to the nucleus, of which three (PBX2, TEAD1 and DIDO1) were classified as transcription factors and two (CENPC1 and MAD2L1) are associated with cell division control.
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| 13. |
- Bertran, Esther, et al.
(författare)
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Role of CXCR4/SDF-1 alpha in the migratory phenotype of hepatoma cells that have undergone epithelial-mesenchymal transition in response to the transforming growth factor-beta.
- 2009
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Ingår i: Cellular Signalling. - : Elsevier BV. - 0898-6568 .- 1873-3913. ; 21:11, s. 1595-1606
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Tidskriftsartikel (refereegranskat)abstract
- Treatment of FaO rat hepatoma cells with TGF-beta selects cells that survive to its apoptotic effect and undergo epithelial-mesenchymal transitions (EMT). We have established a cell line (T beta T-FaO, from TGF-beta-treated FaO) that shows a mesenchymal, de-differentiated, phenotype in the presence of TGF-beta and is refractory to its suppressor effects. In the absence of this cytokine, cells revert to an epithelial phenotype in 3-4 weeks and recover the response to TGF-beta. T beta T-FaO show higher capacity to migrate than that observed in the parental FaO cells. We found that FaO cells express low levels of CXCR4 and do not respond to SDF-1 alpha. However, TGF-beta up-regulates CXCR4, through a NF kappaB-dependent mechanism, and T beta T-FaO cells show elevated levels of CXCR4, which is located in the presumptive migration front. A specific CXCR4 antagonist (AMD3100) attenuates the migratory capacity of T beta T-FaO cells on collagen gels. Extracellular SDF-1 alpha activates the ERKs pathway in T beta T-FaO, but not in FaO cells, increasing cell scattering and protecting cells from apoptosis induced by serum deprivation. Targeted knock-down of CXCR4 with specific siRNA blocks the T beta T-FaO response to SDF-1 alpha. Thus, the SDF-1/CXCR4 axis might play an important role in mediating cell migration and survival after a TGF-beta-induced EMT in hepatoma cells.
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| 14. |
- Caja, Laia, et al.
(författare)
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Differential intracellular signalling induced by TGF-beta in rat adult hepatocytes and hepatoma cells : implications in liver carcinogenesis.
- 2007
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Ingår i: Cellular Signalling. - : Elsevier BV. - 0898-6568 .- 1873-3913. ; 19:4, s. 683-94
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Tidskriftsartikel (refereegranskat)abstract
- The transforming growth factor-beta (TGF-beta) regulates hepatocyte growth, inhibiting proliferation and inducing apoptosis. Indeed, escaping from the TGF-beta suppressor actions might be a prerequisite for liver tumour progression. In this work we show that TGF-beta plays a dual role in regulating apoptosis in FaO rat hepatoma cells, since, in addition to its pro-apoptotic effect, TGF-beta also activates survival signals, such as AKT, the epidermal growth factor receptor (EGFR) being required for its activation. TGF-beta induces the expression of the EGFR ligands transforming growth factor-alpha (TGF-alpha) and heparin-binding EGF-like growth factor (HB-EGF) and induces intracellular re-localization of the EGFR. Cells that overcome the apoptotic effects of TGF-beta undergo morphological changes reminiscent of an epithelial-mesenchymal transition (EMT) process. In contrast, TGF-beta does not activate AKT in adult hepatocytes, which correlates with lack of EGFR transactivation and no response to EGFR inhibitors. Although TGF-beta induces TGF-alpha and HB-EGF in adult hepatocytes, these cells show very low expression of TACE/ADAM 17 (TNF-alpha converting enzyme), which is required for EGFR ligand proteolysis and activation. Furthermore, adult hepatocytes do not undergo EMT processes in response to TGF-beta, which might be due, at least in part, to the fact that F-actin re-organization induced by TGF-beta in FaO cells require the EGFR pathway. Finally, results indicate that EGFR transactivation does not block TGF-beta-induced cell cycle arrest in FaO cells, but must be interfering with the pro-apoptotic signalling. In conclusion, TGF-beta is a suppressor factor for adult quiescent hepatocytes, but not for hepatoma cells, where it plays a dual role, both suppressing and promoting carcinogenesis.
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| 15. |
- Chisari, Andrea N, et al.
(författare)
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Lack of amino acids in mouse hepatocytes in culture induces the selection of preneoplastic cells.
- 2012
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Ingår i: Cellular Signalling. - : Elsevier BV. - 0898-6568 .- 1873-3913. ; 24:1, s. 325-32
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Tidskriftsartikel (refereegranskat)abstract
- Protein malnutrition occurs when there is insufficient protein to meet metabolic demands. Previous works have indicated that cycles of protein fasting/refeeding enhance the incidence of early lesions during chemical carcinogenesis in rat liver. The general objective of this work was to study the effect of aminoacids (Aa) deprivation on the proliferation and survival of hepatocytes, to understand its possible involvement in the generation of pre-neoplastic stages in the liver. Lack of Aa in the culture medium of an immortalized mice hepatocyte cell line induced loss in cell viability, correlating with apoptosis. However, a subpopulation of cells was able to survive, which showed a more proliferative phenotype and resistance to apoptotic stimuli. Escaping to Aa deprivation-induced death is coincident with an activated mTOR signaling and higher levels of phospho-AKT and phospho-ERKs, which correlated with increased activation of EGFR/SRC pathway and overexpression of EGFR ligands, such as TGF-α and HB-EGF. Lack of Aa induced a rapid increase in reactive oxygen species (ROS) production. However, cells that survived showed an enhancement in the levels of reduced glutathione and a higher expression of γ-GCS, the regulatory enzyme of glutathione synthesis, which can be interpreted as an adaptation of the cells to counteract the oxidative stress. In conclusion, results presented in this paper indicate that it is possible to isolate a subpopulation of hepatocytes that are able to grow in the absence of Aa, showing higher capacity to proliferate and survive, reminiscent of a preneoplastic phenotype.
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| 16. |
- Dedinszki, Dora, et al.
(författare)
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Inhibition of protein phosphatase-1 and -2A decreases the chemosensitivity of leukemic cells to chemotherapeutic drugs
- 2015
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Ingår i: Cellular Signalling. - : Elsevier BV. - 0898-6568 .- 1873-3913. ; 27:2, s. 363-372
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Tidskriftsartikel (refereegranskat)abstract
- The phosphorylation of key proteins balanced by protein kinases and phosphatases are implicated in the regulation of cell cycle and apoptosis of malignant cells and influences anticancer drug actions. The efficacy of daunorubicin (DNR) in suppression of leukemic cell survival was investigated in the presence of tautomycin (TM) and calyculin A (CIA), specific membrane permeable inhibitors of protein phosphatase-1 (PP1) and -2A (PP2A), respectively. CIA (50 nM) or TM (1 mu M) suppressed viability of THP-1 and KG-1 myeloid leukemia cell lines to moderate extents; however, they significantly increased survival upon DNR-induced cell death. CLA increased the phosphorylation level of Erk1/2 and PKB/Akt kinases, the retinoblastoma protein (pRb), decreased caspase3 activation by DNR and increased the phosphorylation level of the inhibitory sites (Thr696 and Thr853) in the myosin phosphatase (MP) target subunit (MYPT1) as well as in a 25 kDa kinase-enhanced phosphatase inhibitor (KEPI)-like protein. TM induced enhanced phosphorylation of pRb only, suggesting that this event may be a common factor upon CIA-induced PP2A and TM-induced PP1 inhibitory influences on cell survival. Silencing PP1 by siRNA in HeLa cells, or overexpression of Flag-KEPI in MCF-7 cells coupled with inducing its phosphorylation by PMA or CIA, resulted in increased phosphorylation of pRb. Our results indicate that PP1 directly dephosphorylates pRb, while PP2A might have an indirect influence via mediating the phosphorylation level of PP1 inhibitory proteins:These data imply the importance of PP1 inhibitory proteins in controlling the phosphorylation state of key proteins and regulating drug sensitivity and apoptosis in leukemic cells.
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| 17. |
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| 18. |
- Ducommun, Serge, et al.
(författare)
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Chemical genetic screen identifies Gapex-5/GAPVD1 and STBD1 as novel AMPK substrates
- 2019
-
Ingår i: Cellular Signalling. - : Elsevier BV. - 0898-6568 .- 1873-3913. ; 57, s. 45-57
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Tidskriftsartikel (refereegranskat)abstract
- AMP-activated protein kinase (AMPK) is a key regulator of cellular energy homeostasis, acting as a sensor of energy and nutrient status. As such, AMPK is considered a promising drug target for treatment of medical conditions particularly associated with metabolic dysfunctions. To better understand the downstream effectors and physiological consequences of AMPK activation, we have employed a chemical genetic screen in mouse primary hepatocytes in an attempt to identify novel AMPK targets. Treatment of hepatocytes with a potent and specific AMPK activator 991 resulted in identification of 65 proteins phosphorylated upon AMPK activation, which are involved in a variety of cellular processes such as lipid/glycogen metabolism, vesicle trafficking, and cytoskeleton organisation. Further characterisation and validation using mass spectrometry followed by immunoblotting analysis with phosphorylation site-specific antibodies identified AMPK-dependent phosphorylation of Gapex-5 (also known as GTPase-activating protein and VPS9 domain-containing protein 1 (GAPVD1)) on Ser902 in hepatocytes and starch-binding domain 1 (STBD1) on Ser175 in multiple cells/tissues. As new promising roles of AMPK as a key metabolic regulator continue to emerge, the substrates we identified could provide new mechanistic and therapeutic insights into AMPK-activating drugs in the liver.
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| 19. |
- Elvers, Margitta, et al.
(författare)
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A novel role for phospholipase D as an endogenous negative regulator of platelet sensitivity
- 2012
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Ingår i: Cellular Signalling. - New York, USA : Elsevier. - 0898-6568 .- 1873-3913. ; 24:9, s. 1743-52
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Tidskriftsartikel (refereegranskat)abstract
- Platelet aggregation, secretion and thrombus formation play a critical role in primary hemostasis to prevent excessive blood loss. On the other hand, uncontrolled platelet activation leads to pathological thrombus formation resulting in myocardial infarction or stroke. Stimulation of heterotrimeric G-proteins by soluble agonists or immunoreceptor tyrosine based activation motif-coupled receptors that interact with immobilized ligands such as the collagen receptor glycoprotein (GP) VI lead to the activation of phospholipases that cleave membrane phospholipids to generate soluble second messengers. Platelets contain the phospholipases (PL) D1 and D2 which catalyze the hydrolysis of phosphatidylcholine to generate the second messenger phosphatidic acid (PA). The production of PA is abrogated by primary alcohols that have been widely used for the analysis of PLD-mediated processes. However, it is not clear if primary alcohols effectively reduce PA generation or if they induce PLD-independent cellular effects. In the present study we made use of the specific PLD inhibitor 5-fluoro-2-indolyl des-chlorohalopemide (FIPI) and show for the first time, that FIPI enhances platelet dense granule secretion and aggregation of human platelets. Further, FIPI has no effect on cytosolic Ca(2+) activity but needs proper Rho kinase signaling to mediate FIPI-induced effects on platelet activation. Upon FIPI treatment the phosphorylation of the PKC substrate pleckstrin was prominently enhanced suggesting that FIPI affects PKC-mediated secretion and aggregation in platelets. Similar effects of FIPI were observed in platelets from mouse wild-type and Pld1(-/-) mice pointing to a new role for PLD2 as a negative regulator of platelet sensitivity.
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| 20. |
- Fukuda, Tomohiko, et al.
(författare)
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BMP2-induction of FN14 promotes protumorigenic signaling in gynecologic cancer cells
- 2021
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Ingår i: Cellular Signalling. - : Elsevier. - 0898-6568 .- 1873-3913. ; 87
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Tidskriftsartikel (refereegranskat)abstract
- We previously reported that bone morphogenetic protein (BMP) signaling promotes tumorigenesis in gynecologic cancer cells. BMP2 enhances proliferation of ovarian and endometrial cancer cells via c-KIT induction, and triggers epithelial-mesenchymal transition (EMT) by SNAIL and/or SLUG induction, leading to increased cell migration. However, the downstream effectors of BMP signaling in gynecological cancer cells have not been clearly elucidated. In this study, we performed RNA-sequencing of Ishikawa endometrial and SKOV3 ovarian cancer cells after BMP2 stimulation, and identified TNFRSF12A, encoding fibroblast growth factor-inducible 14 (FN14) as a common BMP2-induced gene. FN14 knockdown suppressed BMP2-induced cell proliferation and migration, confirmed by MTS and scratch assays, respectively. In addition, FN14 silencing augmented chemosensitivity of SKOV3 cells. As a downstream effector of BMP signaling, FN14 modulated both c-KIT and SNAIL expression, which are important for growth and migration of ovarian and endometrial cancer cells. These results support the notion that the tumor promoting effects of BMP signaling in gynecological cancers are partially attributed to FN14 induction.
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| 21. |
- Fälker, Knut, 1971-, et al.
(författare)
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Adrenoceptor α2A signalling countervails the taming effects of synchronous cyclic nucleotide-elevation on thrombin-induced human platelet activation and aggregation
- 2019
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Ingår i: Cellular Signalling. - : Elsevier. - 0898-6568 .- 1873-3913. ; 59, s. 96-109
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Tidskriftsartikel (refereegranskat)abstract
- The healthy vascular endothelium constantly releases autacoids which cause an increase of intracellular cyclic nucleotides to tame platelets from inappropriate activation. Elevating cGMP and cAMP, in line with previous reports, cooperated in the inhibition of isolated human platelet intracellular calcium-mobilization, dense granules secretion, and aggregation provoked by thrombin. Further, platelet alpha granules secretion and, most relevant, integrin αIIaβ3 activation in response to thrombin are shown to be prominently affected by the combined elevation of cGMP and cAMP. Since stress-related sympathetic nervous activity is associated with an increase in thrombotic events, we investigated the impact of epinephrine in this setting. We found that the assessed signalling events and functional consequences were to various extents restored by epinephrine, resulting in full and sustained aggregation of isolated platelets. The restoring effects of epinephrine were abolished by either interfering with intracellular calcium-elevation or with PI3-K signalling. Finally, we show that in our experimental setting epinephrine likewise reconstitutes platelet aggregation in heparinized whole blood, which may indicate that this mechanism could also apply in vivo.
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| 22. |
- Fälker, Knut, 1971-, et al.
(författare)
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The Toll-like receptor 2/1 (TLR2/1) complex initiates human platelet activation via the src/Syk/LAT/PLC gamma 2 signalling cascade
- 2014
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Ingår i: Cellular Signalling. - New York, USA : Elsevier. - 0898-6568 .- 1873-3913. ; 26:2, s. 279-286
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Tidskriftsartikel (refereegranskat)abstract
- The specific TLR2/1 complex activator Pam3CSK4 has been shown to provoke prominent activation and aggregation of human non-nucleated platelets. As Pam3CSK4-evoked platelet activation does not employ the major signalling pathway established in nucleated immune cells, we investigated if the TLR2/1 complex on platelets may initiate signalling pathways known to be induced by physiological agonists such as collagen via GPVI or thrombin via PARs. We found that triggering TLR2/1 complex-signalling with Pam3CSK4, in common with that induced via GPVI, and in contrast to that provoked by PARS, involves tyrosine phosphorylation of the adaptor protein LAT as well as of PLC gamma 2 in a src- and Syk-dependent manner. In this respect, we provide evidence that Pam3CSK4 does not cross-activate GPVI. Further, by the use of platelets from a Glanzmann's thrombasthenia patient lacking beta(3), in contrast to findings in nucleated immune cells, we show that the initiation of platelet activation by Pam3CSK4 does not involve integrin beta(3) signalling; whereas the latter, subsequent to intermediate TXA2 synthesis and signalling, was found to be indispensable for proper dense granule secretion and full platelet aggregation. Together, our findings reveal that triggering the TLR2/1 complex with Pam3CSK4 initiates human platelet activation by engaging tyrosine kinases of the src family and Syk, the adaptor protein LAT, as well as the key mediator PLC gamma 2. (C) 2013 Elsevier Inc. All rights reserved.
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- Grethe, Simone, et al.
(författare)
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p38 MAPK regulates phosphorylation of Bad via PP2A-dependent suppression of the MEK1/2-ERK1/2 survival pathway in TNF-alpha induced endothelial apoptosis.
- 2006
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Ingår i: Cellular Signalling. - : Elsevier BV. - 1873-3913 .- 0898-6568. ; 18:4, s. 531-540
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Tidskriftsartikel (refereegranskat)abstract
- We recently reported that p38 MAPK regulates TNF-induced endothelial apoptosis via phosphorylation and downregulation of Bcl-xL. Here, we describe that such apoptosis includes p38 NIAPK-mediated, protein phosphatase 2A (PP2A)-dependent, downregulation of the MEK-ERK pathway. Inhibition of PP2A with fostriecin or calyculin A significantly increased MEK phosphorylation, as did exposure to the p38 MAPK inhibitor SB203580. Inhibition of MEK potentiated TNF-induced caspase-3 activity and cell death, and both those events were suppressed by treatment with fostriecin or calyculin A. Immunoprecipitation experiments revealed an association between p38 MAPK, PP2A and MEK, and the results of a phosphatase assay suggested that PP2A is a downstream target of p38 MAPK. Importantly, phosphorylation of Bad at Ser-112 was found to be regulated by p38 MAPK and PP2A. In summary, the present findings indicate a novel p38 MAPK-mediated apoptosis pathway, involving activation of Bad via PP2A-dependent inhibition of the MEK-ERK pathway. (c) 2005 Elsevier Inc. All rights reserved.
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