scholarly journals The MAPK Kinase Kinase-1 Is Essential for Stress-Induced Pancreatic Islet Cell Death

Endocrinology ◽  
2008 ◽  
Vol 149 (6) ◽  
pp. 3046-3053 ◽  
Author(s):  
Dariush Mokhtari ◽  
Jason W. Myers ◽  
Nils Welsh
Keyword(s):  
Cell Death ◽  
Small Interfering Rna ◽  
Islet Cells ◽  
Β Cell ◽  
Pancreatic Islet Cell ◽  
Mapk Kinase ◽  
Transient Overexpression ◽  
Novel Therapeutic Strategies ◽  
Interfering Rna

The aim of the present investigation was to characterize the role of the MAPK kinase kinase-1 (MEKK-1) in stress-induced cell death of insulin producing cells. We observed that transient overexpression of the wild type MEKK-1 protein in the insulin-producing cell lines RIN-5AH and βTC-6 increased c-Jun N-terminal kinase (JNK) phosphorylation and augmented cell death induced by diethylenetriamine/nitroso-1-propylhydrazino)-1-propanamine (DETA/NO), streptozotocin (STZ), and hydrogen peroxide (H2O2). Furthermore, DETA/NO or STZ induced a rapid threonine phosphorylation of MEKK-1. Silencing of MEKK-1 gene expression in βTC-6 and human dispersed islet cells, using in vitro-generated diced small interfering RNA, resulted in protection from DETA/NO, STZ, H2O2, and tunicamycin induced cell death. Moreover, in DETA/NO-treated cells diced small interfering RNA-mediated down-regulation of MEKK-1 resulted in decreased activation of JNK but not p38 and ERK. Inhibition of JNK by treatment with SP600125 partially protected against DETA/NO- or STZ-induced cell death. In summary, our results support an essential role for MEKK-1 in JNK activation and stress-induced β-cell death. Increased understanding of the signaling pathways that augment or diminish β-cell MEKK-1 activity may aid in the generation of novel therapeutic strategies in the treatment of type 1 diabetes.

scholarly journals Transforming Growth Factor-β-Activated Protein Kinase 1-Binding Protein (TΑΒ)-1α, But Not ΤΑΒ1β, Mediates Cytokine-Induced p38 Mitogen-Activated Protein Kinase Phosphorylation and Cell Death in Insulin-Producing Cells

Endocrinology ◽  
2007 ◽  
Vol 149 (1) ◽  
pp. 302-309 ◽  
Author(s):  
Natalia Makeeva ◽  
Godfried M. Roomans ◽  
Jason W. Myers ◽  
Nils Welsh
Keyword(s):  
Cell Death ◽  
Protein Kinase ◽  
Small Interfering Rna ◽  
Transforming Growth Factor ◽  
Islet Cells ◽  
Binding Protein ◽  
Mitogen Activated Protein Kinase ◽  
Β Cell ◽  
Insulin Producing Cells ◽  
Interfering Rna

Previous studies have indicated that the p38 MAPK participates in signaling events that lead to the death of the insulin-producing β-cell. The aim of the present study was to elucidate the role of the TGF-β-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 β-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-1β + interferon-γ)-stimulated p38 phosphorylation was significantly increased by ΤΑΒ1α overexpression, but not ΤΑΒ1β overexpression, in β-TC6 cells. The ΤΑΒ1α-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-β-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 ΤΑΒ1α, but not ΤΑΒ1β, plays an important role in the activation of p38 in insulin-producing cells and therefore also in cytokine-induced β-cell death.

scholarly journals Protection of pancreatic β-cells by exendin-4 may involve the reduction of endoplasmic reticulum stress; in vivo and in vitro studies

2007 ◽  
Vol 193 (1) ◽  
pp. 65-74 ◽  
Author(s):  
Shin Tsunekawa ◽  
Naoki Yamamoto ◽  
Katsura Tsukamoto ◽  
Yuji Itoh ◽  
Yukiko Kaneko ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Death ◽  
Er Stress ◽  
Islet Cells ◽  
Binding Protein ◽  
Β Cells ◽  
Β Cell ◽  
Pancreatic Β Cells

The aim of this study was to investigate the in vivo and in vitro effects of exendin-4, a potent glucagon-like peptide 1 agonist, on the protection of the pancreatic β-cells against their cell death. In in vivo experiments, we used β-cell-specific calmodulin-overexpressing mice where massive apoptosis takes place in their β-cells, and we examined the effects of chronic treatment with exendin-4. Chronic and s.c. administration of exendin-4 reduced hyperglycemia. The treatment caused significant increases of the insulin contents of the pancreas and islets, and retained the insulin-positive area. Dispersed transgenic islet cells lived only shortly, and several endoplasmic reticulum (ER) stress-related molecules such as immunoglobulin-binding protein (Bip), inositol-requiring enzyme-1α, X-box-binding protein-1 (XBP-1), RNA-activated protein kinase-like endoplasmic reticulum kinase, activating transcription factor-4, and C/EBP-homologous protein (CHOP) were more expressed in the transgenic islets. We also found that the spliced form of XBP-1, a marker of ER stress, was also increased in β-cell-specific calmodulin-overexpressing transgenic islets. In the quantitative real-time PCR analyses, the expression levels of Bip and CHOP were reduced in the islets from the transgenic mice treated with exendin-4. These findings suggest that excess of ER stress occurs in the transgenic β-cells, and the suppression of ER stress and resultant protection against cell death may be involved in the anti-diabetic effects of exendin-4.

scholarly journals Ketamine Activates Cell Cycle Signaling and Apoptosis in the Neonatal Rat Brain

2010 ◽  
Vol 112 (5) ◽  
pp. 1155-1163 ◽  
Author(s):  
Sulpicio G. Soriano ◽  
Qian Liu ◽  
Jing Li ◽  
Jia-Ren Liu ◽  
Xiao Hui Han ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Death ◽  
Cyclin D1 ◽  
Small Interfering Rna ◽  
Caspase 3 ◽  
Primary Neurons ◽  
Cyclin Dependent Kinase ◽  
Cell Cycle Signaling ◽  
Interfering Rna

Background Prolonged exposure to ketamine results in accelerated neurodegeneration and neurocognitive deficits in the neonatal rats. Experimental models of neurodegeneration have implicated reentry of postmitotic neurons into the cell cycle, leading to cell death. The authors hypothesize that the ketamine-induced neuroapoptosis is partially due to aberrant cycle cell reentry. To explore this hypothesis, the authors characterized the effect of ketamine on the cell cycle signaling pathway in the developing rodent brain in vivo and in vitro. Methods Postnatal day 7 rat pups and primary neurons were used for the experiments. Each rat pup received five intraperitoneal doses of either saline or ketamine (5, 10, and 20 mg/kg/dose) at 90-min intervals over 6 h. Primary neurons were exposed to varying concentrations of ketamine to determine the dose and duration effects. The expression of cell cycle proteins (cyclin D1, cyclin-dependent kinase 4, and E2F1), Bcl2-interacting mediator of cell death (Bim), and activated caspase-3 was determined. The effect of cyclin D1 knockdown by small interfering RNA was also examined in primary neurons incubated in ketamine. Results Ketamine mediated a dose- and time-dependent increase in expression of cell cycle proteins and activated caspase-3. Cyclin D1, cyclin-dependent kinase 4, E2F1, Bim, and cleaved caspase-3 expression increased at 12 h and peaked at 24 h in vitro. Knockdown of cyclin D1 by small interfering RNA attenuated Bim and cleaved caspase-3 expression. Conclusion These findings support a model in which ketamine induces aberrant cell cycle reentry, leading to apoptotic cell death in the developing rat brain.

Small interfering RNA treatment can inhibit Cyprinid herpesvirus 3 associated cell death in vitro

2014 ◽  
Vol 17 (4) ◽  
pp. 733-735 ◽  
Author(s):  
M. Adamek ◽  
G. Rauch ◽  
G. Brogden ◽  
D. Steinhagen
Keyword(s):  
Cell Death ◽  
Rna Interference ◽  
Small Interfering Rna ◽  
Enzyme Synthesis ◽  
Small Interfering Rnas ◽  
Viral Dna ◽  
Cyprinid Herpesvirus 3 ◽  
Interfering Rna ◽  
Fibroblastic Cells

Abstract A Cyprinid herpesvirus 3 infection of carp induces a disease which causes substantial losses in carp culture. Here we present the use of a possible strategy for the management of the virus infection RNA interference based on small interfering RNAs. As a result of in vitro studies, we found that a mixture of short interfering RNAs specific for viral DNA enzyme synthesis and capsid proteins of the CyHV-3 can be a potential inhibitor of virus replication in fibroblastic cells. This gives the basis for the development of a combinatorial RNA interference strategy to treat CyHV-3 infections.

scholarly journals Muscle-specific microRNA miR-206 promotes muscle differentiation

2006 ◽  
Vol 174 (5) ◽  
pp. 677-687 ◽  
Author(s):  
Hak Kyun Kim ◽  
Yong Sun Lee ◽  
Umasundari Sivaprasad ◽  
Ankit Malhotra ◽  
Anindya Dutta
Keyword(s):  
Antisense Oligonucleotide ◽  
Small Interfering Rna ◽  
Degradation Process ◽  
Microrna Target ◽  
C2c12 Myoblasts ◽  
Target Sites ◽  
The Many ◽  
Interfering Rna ◽  
In Vitro Transfection

Three muscle-specific microRNAs, miR-206, -1, and -133, are induced during differentiation of C2C12 myoblasts in vitro. Transfection of miR-206 promotes differentiation despite the presence of serum, whereas inhibition of the microRNA by antisense oligonucleotide inhibits cell cycle withdrawal and differentiation, which are normally induced by serum deprivation. Among the many mRNAs that are down-regulated by miR-206, the p180 subunit of DNA polymerase α and three other genes are shown to be direct targets. Down-regulation of the polymerase inhibits DNA synthesis, an important component of the differentiation program. The direct targets are decreased by mRNA cleavage that is dependent on predicted microRNA target sites. Unlike small interfering RNA–directed cleavage, however, the 5′ ends of the cleavage fragments are distributed and not confined to the target sites, suggesting involvement of exonucleases in the degradation process. In addition, inhibitors of myogenic transcription factors, Id1-3 and MyoR, are decreased upon miR-206 introduction, suggesting the presence of additional mechanisms by which microRNAs enforce the differentiation program.

scholarly journals In vitro suppression of the MMP-3 gene in normal and cytokine-treated human chondrosarcoma using small interfering RNA

2009 ◽  
Vol 4 (1) ◽  
Author(s):  
Korakot Nganvongpanit ◽  
Patama Chaochird ◽  
Puntita Siengdee ◽  
Peraphan Pothacharoen ◽  
Kasisin Klunklin ◽  
...  
Keyword(s):  
Small Interfering Rna ◽  
Human Chondrosarcoma ◽  
Interfering Rna

scholarly journals Molecular Determinants of Oocyte Competence: Potential Functional Role for Maternal (Oocyte-Derived) Follistatin in Promoting Bovine Early Embryogenesis

Endocrinology ◽  
2009 ◽  
Vol 150 (5) ◽  
pp. 2463-2471 ◽  
Author(s):  
Kyung-Bon Lee ◽  
Anilkumar Bettegowda ◽  
Gabbine Wee ◽  
James J. Ireland ◽  
George W. Smith
Keyword(s):  
Small Interfering Rna ◽  
Functional Role ◽  
Early Embryogenesis ◽  
Type I ◽  
Blastocyst Development ◽  
Oocyte Competence ◽  
Cell Numbers ◽  
Positive Effects ◽  
Interfering Rna

Previous studies established a positive relationship between oocyte competence and follistatin mRNA abundance. Herein, we used the bovine model to test the hypothesis that follistatin plays a functional role in regulation of early embryogenesis. Treatment of early embryos with follistatin during in vitro culture (before embryonic genome activation) resulted in a dose-dependent decrease in time to first cleavage, increased numbers of blastocysts, and increased blastocyst total and trophectoderm cell numbers. To determine the requirement of endogenous follistatin for early embryogenesis, follistatin ablation/replacement studies were performed. Microinjection of follistatin small interfering RNA into zygotes reduced follistatin mRNA and protein and was accompanied by a reduction in number of embryos developing to eight- to 16-cell and blastocyst stages and reduced blastocyst total and trophectoderm cell numbers. Effects of follistatin ablation were rescued by culture of follistatin small interfering RNA-injected embryos in the presence of exogenous follistatin. To investigate whether follistatin regulation of early embryogenesis is potentially mediated via inhibition of endogenous activin activity, the effects of treatment of embryos with exogenous activin, SB-431542 (inhibitor of activin, TGF-β, and nodal type I receptor signaling) and follistatin plus SB-431542 were investigated. Activin treatment mimicked positive effects of follistatin on time to first cleavage and blastocyst development, whereas negative effects of SB-431542 treatment were observed. Stimulatory effects of follistatin on embryogenesis were not blocked by SB-431542 treatment. Results support a functional role for oocyte-derived follistatin in bovine early embryogenesis and suggest that observed effects of follistatin are likely not mediated by classical inhibition of activin activity.

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