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- Hägerkvist, Robert, et al.
(författare)
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Imatinib mesylate (Gleevec) protects against streptozotocin-induced diabetes and islet cell death in vitro
- 2006
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Ingår i: Cell Biology International. - : Wiley. - 1065-6995 .- 1095-8355. ; 30:12, s. 1013-1017
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Tidskriftsartikel (refereegranskat)abstract
- The tyrosine kinase inhibitor imatinib mesylate (Gleevec) has been demonstrated to protect various cell types from death by inhibition of Abelson tyrosine kinase (c-Abl). The aim of the present study was to establish whether imatinib protects the insulin producing β-cell from the different apoptosis promoting agents in vitro and whether imatinib counteracts streptozotocin-induced diabetes in NMRI mice. We observe that imatinib attenuated the actions of several different death promoting substances. In addition, mice injected with streptozotocin did not develop diabetes when given imatinib. The beneficial effects of imatinib may be related to inhibition of the pro-apoptotic MAP kinase JNK. We conclude that imatinib protects against β-cell death and that this may contribute to the previously reported anti-diabetic actions of imatinib.
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| 2. |
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| 3. |
- Makeeva, Natalia, 1977-
(författare)
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Role of MAP Kinases in the Life and Death of Beta-cells
- 2006
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The development of diabetes mellitus depends on the balance between beta-cell proliferation and death. As mitogen-activated protein kinases (MAPK) may control this balance, the aim of this study was to investigate the events leading to MAPK activation in beta-cells and the consequences of these events. Overexpression of the SH2-domain containing adaptor protein Shb resulted in the assembly and activation of multiunit complex consisting of at least Shb, IRS-1, IRS-2, FAK and PI3K. Consequently, the phosphorylation of Akt was enhanced under basal conditions in Shb overexpression cells. This was paralleled by an attenuated activation of the MAP kinases ERK1/2. Thus, Shb-induced alterations in the IRS-1/PI3K/Akt/ERK pathway might explain the increased proliferation and apoptosis of beta-cells overexpressing Shb.The importance of the MAP kinase p38 in nitric oxide- and cytokine-induced beta-cell death was also investigated. Knock-down of p38 expression resulted in a lowered cell death rate in response to a nitric oxide donor. In transient transfections MKK3 over-expression resulted in increased p38 phosphorylation in RIN-5AH cells. In addition, a short-term MKK3 expression resulted in increased cytokine-induced cell death. A nitric oxide synthase inhibitor abolished the MKK3-potentiating effect on cytokine-induced cell death and inhibitors of phosphatases enhanced MKK3-stimulated p38 phosphorylation. Finally, as the dominant negative mutant of MKK3 did not affect cytokine-induced p38 phosphorylation, and as wild type MKK3 did not influence p38 autophosphorylation, it may be that p38 is activated by MKK3/6-independent pathways in response to cytokines and nitric oxide.In further support for an MKK3/6-indepedent mechanism, the adaptor protein TAB1 significantly increased the cytokine- and nitric oxide-stimulated phosphorylation of p38. The TAB1-mediated activation of p38 was paralleled by a compensatory inhibition of ERK and JNK. In summary, p38 MAPK, activated mainly by TAB1, promotes, at least in part, beta-cell death in response to cytokines or nitric oxide.
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| 5. |
- Makeeva, Natalia, et al.
(författare)
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Role of TAB1 in nitric oxide-induced p38 activation in insulin-producing cells
- 2007
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Ingår i: International Journal of Biological Sciences. - 1449-2288. ; 3:2, s. 71-76
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Tidskriftsartikel (refereegranskat)abstract
- The aim of present study was to elucidate the role of TAB1 in nitric oxide-induced activation of p38 MAPK. For this purpose we over-expressed TAB1 in insulin-producing beta-TC6 cells. We observed in cells transiently over-expressing TAB1 that p38 activation was enhanced in response to DETA/NONOate. A lowering of TAB1 levels, using the siRNA technique, resulted in the opposite effect. The DETA/NONOate-induced cell death rate was increased in cells transiently overexpressing TAB1. In stable beta-TC6 cell clones with very high TAB1 levels p38 phosphorylation was enhanced also at basal conditions. DETA/NONOate increased also the phosphorylation of JNK and ERK in beta-TC6 cells, but these events were not affected by TAB1. Interestingly, the inhibitory effect of SB203580 on p38 phosphorylation was paralleled by a stimulatory effect on JNK phosphorylation and an inhibitory effect on ERK phosphorylation. In summary, we propose that TAB1 promotes nitric oxide-induced p38 autophosphorylation. In addition, nitric oxide-induced p38 activation seems to promote JNK inhibition and ERK activation, but this effect appears to not require TAB1. A better understanding of how the TAB1/p38 pathway promotes beta-cell death in response to nitric oxide might help in the development of novel pharmacological approaches in the treatment of diabetes.
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| 6. |
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| 7. |
- Makeeva, Natalia, et al.
(författare)
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Transforming growth factor-beta-activated protein kinase 1-binding protein (TAB)-1alpha, but not TAB1beta, mediates cytokine-induced p38 mitogen-activated protein kinase phosphorylation and cell death in insulin-producing cells
- 2008
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Ingår i: Endocrinology. - : The Endocrine Society. - 0013-7227 .- 1945-7170. ; 149:1, s. 302-309
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Tidskriftsartikel (refereegranskat)abstract
- Previous studies have indicated that the p38 MAPK participates in signaling events that lead to the death of the insulin-producing beta-cell. The aim of the present study was to elucidate the role of the TGF-beta-activated protein kinase 1-binding protein 1 (TAB1) in the cytokine-induced activation of p38. Levels of TAB1 mRNA and protein were analyzed by real-time PCR and immunoblotting, and TAB1 expression in mouse and human islet cells was down-regulated using lipofection of diced-small interfering RNA. TAB1 overexpression in beta-TC6 cells was achieved by transient transfections followed by fluorescence activated cell sorting. Phosphorylation of p38, c-Jun N-terminal kinase, and ERK was assessed by immunoblotting, and viability was determined using vital staining with bisbenzimide and propidium iodide. We observed that TAB1 is expressed in insulin-producing cells. Cytokine (IL-1beta + interferon-gamma)-stimulated p38 phosphorylation was significantly increased by TAB1alpha overexpression, but not TAB1beta overexpression, in beta-TC6 cells. The TAB1alpha-augmented p38 phosphorylation was paralleled by an increased cell death rate. Treatment of islet cells with diced-small interfering RNA specific for TAB1, but not for TGF-beta-activated kinase 1, resulted in lowered cytokine-induced p38 phosphorylation and protection against cell death. The cytokine-induced phosphorylation of c-Jun N-terminal kinase and ERK was not affected by changes in TAB1 levels. Finally, TAB1 phosphorylation was decreased by the p38 inhibitor SB203580. We conclude that TAB1alpha, but not TAB1beta, plays an important role in the activation of p38 in insulin-producing cells and therefore also in cytokine-induced beta-cell death.
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| 10. |
- Welsh, Nils, et al.
(författare)
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Overexpression of the Shb SH2 domain-protein in insulin-producing cells leads to altered signaling through the IRS-1 and IRS-2 proteins
- 2002
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Ingår i: Molecular Medicine. ; 8:11, s. 695-704
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Tidskriftsartikel (refereegranskat)abstract
- BackgroundOverexpression of the Src homology 2 domain protein Shb in _-cells of transgenic mice has been shown to promote an increased _-cell mass. To investigate the mechanisms by which Shb controls the _-cell mass, we have presently studied the effects of Shb overexpression on the IRS-1–induced signaling pathway in mouse islet _-cells and in insulin-producing RINm5F cells and correlated these effects to growth and death patterns.Materials and MethodsShb overexpression was achieved in RINm5F cells by selection of stable clones or by FACS purification of transiently transfected cells. For Shb overexpression in primary mouse islet cells, a Shb-transgene mouse was used. Cell proliferation and death rates were determined using flow cytometry. Serum-, insulin-, and IGF-1-stimulated signaling events were studied by immunoblot, immunoprecipitation, and in vitro kinase procedures.ResultsTransient Shb overexpression in RINm5F cells resulted in increased proliferation. Both Shb-overexpressing RINm5F cells and islet cells from transgenic mice (islet Shb) exhibited increased basal tyrosine phosphorylation of IRS-1. Shb overexpression resulted also in the assembly and activation of a multiunit complex consisting of at least Shb, IRS-1, IRS-2, FAK, and PI3K. Consequently, the phosphorylation of Akt was enhanced under basal conditions in Shb overexpressing cells. Finally, Shb overexpression did not affect insulin-induced phosphorylation of the PI3K-antagonist PTEN.ConclusionIt is concluded that the Shb-induced alterations in the IRS-1/PI3K/Akt pathway may be relevant to the understanding of growth and death patterns of insulin-producing cells.
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