scholarly journals Ceramide synthase 4 and de novo production of ceramides with specific N-acyl chain lengths are involved in glucolipotoxicity-induced apoptosis of INS-1 β-cells

2011 ◽  
Vol 438 (1) ◽  
pp. 177-189 ◽  
Author(s):  
Julien Véret ◽  
Nicolas Coant ◽  
Evgeny V. Berdyshev ◽  
Anastasia Skobeleva ◽  
Nicole Therville ◽  
...  
Keyword(s):  
Cell Apoptosis ◽  
De Novo ◽  
Acyl Chain ◽  
Fumonisin B1 ◽  
Ceramide Synthase ◽  
Β Cells ◽  
Β Cell ◽  
Induced Apoptosis ◽  
Synthase Inhibitor ◽  
Chain Lengths

Pancreatic β-cell apoptosis induced by palmitate requires high glucose concentrations. Ceramides have been suggested to be important mediators of glucolipotoxicity-induced β-cell apoptosis. In INS-1 β-cells, 0.4 mM palmitate with 5 mM glucose increased the levels of dihydrosphingosine and dihydroceramides, two lipid intermediates in the de novo biosynthesis of ceramides, without inducing apoptosis. Increasing glucose concentrations to 30 mM amplified palmitate-induced accumulation of dihydrosphingosine and the formation of (dihydro)ceramides. Of note, glucolipotoxicity specifically induced the formation of C18:0, C22:0 and C24:1 (dihydro)ceramide molecular species, which was associated with the up-regulation of CerS4 (ceramide synthase 4) levels. Fumonisin-B1, a ceramide synthase inhibitor, partially blocked apoptosis induced by glucolipotoxicity. In contrast, apoptosis was potentiated in the presence of D,L-threo-1-phenyl-2-palmitoylamino-3-morpholinopropan-1-ol, an inhibitor of glucosylceramide synthase. Moreover, overexpression of CerS4 amplified ceramide production and apoptosis induced by palmitate with 30 mM glucose, whereas down-regulation of CerS4 by siRNA (short interfering RNA) reduced apoptosis. CerS4 also potentiates ceramide accumulation and apoptosis induced by another saturated fatty acid: stearate. Collectively, our results suggest that glucolipotoxicity induces β-cell apoptosis through a dual mechanism involving de novo ceramide biosynthesis and the formation of ceramides with specific N-acyl chain lengths rather than an overall increase in ceramide content.

scholarly journals Nodal induces apoptosis through activation of the ALK7 signaling pathway in pancreatic INS-1 β-cells

2012 ◽  
Vol 303 (1) ◽  
pp. E132-E143 ◽  
Author(s):  
Fang Zhao ◽  
Fengjie Huang ◽  
Mengxiong Tang ◽  
Xiaoming Li ◽  
Nina Zhang ◽  
...  
Keyword(s):  
Signaling Pathway ◽  
Cell Apoptosis ◽  
Caspase 3 ◽  
Biological Effects ◽  
Cell Mass ◽  
Type I ◽  
Β Cells ◽  
Β Cell ◽  
Akt Phosphorylation ◽  
Induced Apoptosis

We demonstrated previously that the activation of ALK7 (activin receptor-like kinase-7), a member of the type I receptor serine/threonine kinases of the TGF-β superfamily, resulted in increased apoptosis and reduced proliferation through suppression of Akt signaling and the activation of Smad2-dependent signaling pathway in pancreatic β-cells. Here, we show that Nodal activates ALK7 signaling and regulates β-cell apoptosis. We detected Nodal expression in the clonal β-cell lines and rodent islet β-cells. Induction of β-cell apoptosis by treatment with high glucose, palmitate, or cytokines significantly increased Nodal expression in clonal INS-1 β-cells and isolated rat islets. The stimuli induced upregulation of Nodal expression levels were associated with elevation of ALK7 protein and enhanced phosphorylated Smad3 protein. Nodal treatment or overexpression of Nodal dose- or time-dependently increased active caspase-3 levels in INS-1 cells. Nodal-induced apoptosis was associated with decreased Akt phosphorylation and reduced expression level of X-linked inhibitor of apoptosis (XIAP). Remarkably, overexpression of XIAP or constitutively active Akt, or ablation of Smad2/3 activity partially blocked Nodal-induced apoptosis. Furthermore, siRNA-mediated ALK7 knockdown significantly attenuated Nodal-induced apoptosis of INS-1 cells. We suggest that Nodal-induced apoptosis in β-cells is mediated through ALK7 signaling involving the activation of Smad2/3-caspase-3 and the suppression of Akt and XIAP pathways and that Nodal may exert its biological effects on the modulation of β-cell survival and β-cell mass in an autocrine fashion.

scholarly journals A Novel Role of IGF1 in Apo2L/TRAIL-Mediated Apoptosis of Ewing Tumor Cells

Sarcoma ◽  
2012 ◽  
Vol 2012 ◽  
pp. 1-14 ◽  
Author(s):  
Frans van Valen ◽  
Henning Harrer ◽  
Marc Hotfilder ◽  
Uta Dirksen ◽  
Thomas Pap ◽  
...  
Keyword(s):  
De Novo ◽  
Fumonisin B1 ◽  
Chemotherapeutic Agents ◽  
Ceramide Synthase ◽  
Short Term ◽  
Igf1 Receptor ◽  
Induced Apoptosis ◽  
Survival Effect

Insulin-like growth factor 1 (IGF1) reputedly opposes chemotoxicity in Ewing sarcoma family of tumor (ESFT) cells. However, the effect of IGF1 on apoptosis induced by apoptosis ligand 2 (Apo2L)/tumor necrosis factor (TNF-) related apoptosis-inducing ligand (TRAIL) remains to be established. We find that opposite to the partial survival effect of short-term IGF1 treatment, long-term IGF1 treatment amplified Apo2L/TRAIL-induced apoptosis in Apo2L/TRAIL-sensitive but not resistant ESFT cell lines. Remarkably, the specific IGF1 receptor (IGF1R) antibodyα-IR3 was functionally equivalent to IGF1. Short-term IGF1 incubation of cells stimulated survival kinase AKT and increased X-linked inhibitor of apoptosis (XIAP) protein which was associated with Apo2L/TRAIL resistance. In contrast, long-term IGF1 incubation resulted in repression of XIAP protein through ceramide (Cer) formation derived from de novo synthesis which was associated with Apo2L/TRAIL sensitization. Addition of ceramide synthase (CerS) inhibitor fumonisin B1 during long-term IGF1 treatment reduced XIAP repression and Apo2L/TRAIL-induced apoptosis. Noteworthy, the resistance to conventional chemotherapeutic agents was maintained in cells following chronic IGF1 treatment. Overall, the results suggest that chronic IGF1 treatment renders ESFT cells susceptible to Apo2L/TRAIL-induced apoptosis and may have important implications for the biology as well as the clinical management of refractory ESFT.

scholarly journals High sensitivity of β-cell replication to the inhibitory effects of interleukin-1β: modulation by adenoviral overexpression of IGF2 in rat islets

2009 ◽  
Vol 203 (1) ◽  
pp. 55-63 ◽  
Author(s):  
Elisabet Estil.les ◽  
Noèlia Téllez ◽  
Joan Soler ◽  
Eduard Montanya
Keyword(s):  
Cell Proliferation ◽  
Cell Apoptosis ◽  
Interleukin 1Β ◽  
Complete Suppression ◽  
Cell Replication ◽  
Inhibitory Effects ◽  
Β Cells ◽  
Β Cell ◽  
Rat Islets ◽  
Induced Apoptosis

Interleukin-1β (IL1B) is an important contributor to the autoimmune destruction of β-cells in type 1 diabetes, and it has been recently related to the development of type 2 diabetes. IGF2 stimulates β-cell proliferation and survival. We have determined the effect of IL1B on β-cell replication, and the potential modulation by IGF2 and glucose. Control-uninfected and adenovirus encoding for IGF2 (Ad-IGF2)-infected rat islets were cultured at 5.5 or 22.2 mmol/l glucose with or without 1, 10, 30, and 50 U/ml of IL1B. β-Cell replication was markedly reduced by 10 U/ml of IL1B and was almost nullified with 30 or 50 U/ml of IL1B. Higher concentrations of IL1B were required to increase β-cell apoptosis. Although IGF2 overexpression had a strong mitogenic effect on β-cells, IGF2 could preserve β-cell proliferation only in islets cultured with 10 U/ml IL1B, and had no effect with 30 and 50 U/ml of IL1B. In contrast, IGF2 overexpression induced a clear protection against IL1B-induced apoptosis, and higher concentrations of the cytokine were needed to increase β-cell apoptosis in Ad-IGF2-infected islets. These results indicate that β-cell replication is highly sensitive to the deleterious effects of the IL1B as shown by the inhibition of replication by relatively low IL1B concentrations, and the almost complete suppression of β-cell replication with high IL1B concentrations. Likewise, the inhibitory effects of IL-β on β-cell replication were not modified by glucose, and were only modestly prevented by IGF2 overexpression, in contrast with the higher protection against IL1B-induced apoptosis afforded by glucose and by IGF2 overexpression.

scholarly journals Protein Kinase B/Akt Prevents Fatty Acid-induced Apoptosis in Pancreatic β-Cells (INS-1)

2002 ◽  
Vol 277 (51) ◽  
pp. 49676-49684 ◽  
Author(s):  
Christian E. Wrede ◽  
Lorna M. Dickson ◽  
Melissa K. Lingohr ◽  
Isabelle Briaud ◽  
Christopher J. Rhodes
Keyword(s):  
Growth Factor ◽  
Protein Kinase ◽  
Cell Apoptosis ◽  
Glycogen Synthase ◽  
Protein Kinase B ◽  
Glycogen Synthase Kinase ◽  
Pancreatic Β Cell ◽  
Β Cells ◽  
Β Cell ◽  
Induced Apoptosis

Free fatty acids (FFA) have been reported to reduce pancreatic β-cell mitogenesis and to increase apoptosis. Here we show that the FFA, oleic acid, increased apoptosis 16-fold in the pancreatic β-cell line, INS-1, over a 18-h period as assessed by Hoechst 33342/propidium iodide staining and caspase-3 and -9 activation, with negligible necrosis. A parallel analysis of the phosphorylation activation of protein kinase B (PKB) showed this was reduced in the presence of FFA that correlated with the incidence of apoptosis. At stimulatory 15 mmglucose and/or in the added presence of insulin-like growth factor 1, FFA-induced β-cell apoptosis was lessened compared with that at a basal 5 mmglucose. However, most strikingly, adenoviral mediated expression of a constitutively active PKB, but not a “kinase-dead” PKB variant, essentially prevented FFA-induced β-cell apoptosis under all glucose/insulin-like growth factor 1 conditions. Further analysis of pro-apoptotic downstream targets of PKB, implicated a role for PKB-mediated phosphorylation inhibition of glycogen synthase kinase-3α/β and the forkhead transcription factor, FoxO1, in protection of FFA-induced β-cell apoptosis. In addition, down-regulation of the pro-apoptotic tumor suppresser protein, p53, via PKB-mediated phosphorylation of MDM2 might also play a role in partially protecting β-cells from FFA-induced apoptosis. Adenoviral mediated expression of wild type p53 potentiated FFA-induced β-cell apoptosis, whereas expression of a dominant negative p53 partly inhibited β-cell apoptosis by ∼50%. Hence, these data demonstrate that PKB activation plays an important role in promoting pancreatic β-cell survival in part via inhibition of the pro-apoptotic proteins glycogen synthase kinase-3α/β, FoxO1, and p53. This, in turn, provides novel insight into the mechanisms involved in FFA-induced β-cell apoptosis.

scholarly journals Nitric Oxide Suppresses β-Cell Apoptosis by Inhibiting the DNA Damage Response

2016 ◽  
Vol 36 (15) ◽  
pp. 2067-2077 ◽  
Author(s):  
Bryndon J. Oleson ◽  
Katarzyna A. Broniowska ◽  
Aaron Naatz ◽  
Neil Hogg ◽  
Vera L. Tarakanova ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Dna Damage ◽  
Cell Survival ◽  
Dna Damage Response ◽  
Cell Apoptosis ◽  
Β Cells ◽  
Β Cell ◽  
Pancreatic Β Cells ◽  
Damage Response ◽  
Induced Apoptosis

Nitric oxide, produced in pancreatic β cells in response to proinflammatory cytokines, plays a dual role in the regulation of β-cell fate. While nitric oxide induces cellular damage and impairs β-cell function, it also promotes β-cell survival through activation of protective pathways that promote β-cell recovery. In this study, we identify a novel mechanism in which nitric oxide prevents β-cell apoptosis by attenuating the DNA damage response (DDR). Nitric oxide suppresses activation of the DDR (as measured by γH2AX formation and the phosphorylation of KAP1 and p53) in response to multiple genotoxic agents, including camptothecin, H2O2, and nitric oxide itself, despite the presence of DNA damage. While camptothecin and H2O2both induce DDR activation, nitric oxide suppresses only camptothecin-induced apoptosis and not H2O2-induced necrosis. The ability of nitric oxide to suppress the DDR appears to be selective for pancreatic β cells, as nitric oxide fails to inhibit DDR signaling in macrophages, hepatocytes, and fibroblasts, three additional cell types examined. While originally described as the damaging agent responsible for cytokine-induced β-cell death, these studies identify a novel role for nitric oxide as a protective molecule that promotes β-cell survival by suppressing DDR signaling and attenuating DNA damage-induced apoptosis.

scholarly journals Low- and High-Density Lipoproteins Modulate Function, Apoptosis, and Proliferation of Primary Human and Murine Pancreatic β-Cells

Endocrinology ◽  
2009 ◽  
Vol 150 (10) ◽  
pp. 4521-4530 ◽  
Author(s):  
Sabine Rütti ◽  
Jan A. Ehses ◽  
Rahel A. Sibler ◽  
Richard Prazak ◽  
Lucia Rohrer ◽  
...  
Keyword(s):  
Type 2 Diabetes ◽  
Insulin Secretion ◽  
Cell Apoptosis ◽  
Ldl Receptor ◽  
High Density ◽  
Apolipoprotein A1 ◽  
Β Cells ◽  
Β Cell ◽  
Induced Apoptosis

Abstract A low high-density lipoprotein (HDL) plasma concentration and the abundance of small dense low-density lipoproteins (LDL) are risk factors for developing type 2 diabetes. We therefore investigated whether HDL and LDL play a role in the regulation of pancreatic islet cell apoptosis, proliferation, and secretory function. Isolated mouse and human islets were exposed to plasma lipoproteins of healthy human donors. In murine and human β-cells, LDL decreased both proliferation and maximal glucose-stimulated insulin secretion. The comparative analysis of β-cells from wild-type and LDL receptor-deficient mice revealed that the inhibitory effect of LDL on insulin secretion but not proliferation requires the LDL receptor. HDL was found to modulate the survival of both human and murine islets by decreasing basal as well as IL-1β and glucose-induced apoptosis. IL-1β-induced β-cell apoptosis was also inhibited in the presence of either the delipidated protein or the deproteinated lipid moieties of HDL, apolipoprotein A1 (the main protein component of HDL), or sphingosine-1-phosphate (a bioactive sphingolipid mostly carried by HDL). In murine β-cells, the protective effect of HDL against IL-1β-induced apoptosis was also observed in the absence of the HDL receptor scavenger receptor class B type 1. Our data show that both LDL and HDL affect function or survival of β-cells and raise the question whether dyslipidemia contributes to β-cell failure and hence the manifestation and progression of type 2 diabetes mellitus.

scholarly journals Involvement of the Ca2+-responsive transactivator in high glucose-induced β-cell apoptosis

2012 ◽  
Vol 216 (2) ◽  
pp. 231-243 ◽  
Author(s):  
Xiuli Men ◽  
Liang Peng ◽  
Haiyan Wang ◽  
Wenjian Zhang ◽  
Shiqing Xu ◽  
...  
Keyword(s):  
High Glucose ◽  
Cell Apoptosis ◽  
Cell Function ◽  
Β Cells ◽  
Β Cell ◽  
Β Cell Function ◽  
Induced Apoptosis ◽  
Sirna Knockdown

The calcium-regulated transcription coactivator, Ca2+-responsive transactivator (CREST) was expressed in pancreatic β-cells. Moreover, CREST expression became significantly increased in pancreatic islets isolated from hyperglycemic Goto–Kakizaki rats compared with normoglycemic Wistar controls. In addition, culture of β-cells in the presence of high glucose concentrations also increased CREST expression in vitro. To further investigate the role of this transactivator in the regulation of β-cell function, we established a stable β-cell line with inducible CREST expression. Hence, CREST overexpression mimicked the glucotoxic effects on insulin secretion and cell growth in β-cells. Moreover, high glucose-induced apoptosis was aggravated by upregulation of the transactivator but inhibited when CREST expression was partially silenced by siRNA technology. Further investigation found that upregulation of Bax and downregulation of Bcl2 was indeed induced by its expression, especially under high glucose conditions. In addition, as two causing factors leading to β-cell apoptosis under diabetic conditions, endoplasmic reticulum stress and high free fatty acid, mimicked the high glucose effects on CREST upregulation and generation of apoptosis in β-cells, and these effects were specifically offset by the siRNA knockdown of CREST. These results indicated that CREST is implicated in β-cell apoptosis induced by culture in high glucose and hence that CREST may become a potential pharmacological target for the prevention and treatment of type 2 diabetes mellitus.

Dexamethasone induces pancreatic β-cell apoptosis through upregulation of TRAIL death receptor

2021 ◽  
Author(s):  
Kanchana Suksri ◽  
Namoiy Semprasert ◽  
Mutita Junking ◽  
Suchanoot Kutpruek ◽  
Thawornchai Limjindaporn ◽  
...  
Keyword(s):  
Cell Apoptosis ◽  
Molecular Mechanisms ◽  
Cultured Cells ◽  
Death Receptor ◽  
Caspase 8 ◽  
Pancreatic Β Cell ◽  
Β Cell ◽  
Apoptotic Protein ◽  
Induced Apoptosis ◽  
Trail Death Receptor

Long-term medication with dexamethasone (a synthetic glucocorticoid (GC) drug) results in hyperglycemia, or steroid-induced diabetes. Although recent studies revealed dexamethasone directly induces pancreatic β-cell apoptosis, its molecular mechanisms remain unclear. In our initial analysis of mRNA transcripts, we discovered the tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) pathway may be involved in dexamethasone-induced pancreatic β-cell apoptosis. In the present study, a mechanism of dexamethasone-induced pancreatic β-cell apoptosis through the TRAIL pathway was investigated in cultured cells and isolated mouse islets. INS-1 cells were cultured with and without dexamethasone in the presence or absence of a glucocorticoid receptor (GR) inhibitor, RU486. We found that dexamethasone induced pancreatic β-cell apoptosis in association with the upregulation of TRAIL mRNA and protein expression. Moreover, dexamethasone upregulated the TRAIL death receptor (DR5) protein but suppressed the decoy receptor (DcR1) protein. Similar findings were observed in mouse isolated islets: dexamethasone increased TRAIL and DR5 compared to that of control mice. Furthermore, dexamethasone stimulated pro-apoptotic signaling including superoxide production, caspase-8, -9, and -3 activities, NF-B, and Bax, but repressed the anti-apoptotic protein, Bcl-2. All these effects were inhibited by the GR-inhibitor, RU486. Furthermore, knock down DR5 decreased dexamethasone-induced caspase 3 activity. Caspase-8 and caspase-9 inhibitors protected pancreatic β-cells from dexamethasone-induced apoptosis. Taken together, dexamethasone induced pancreatic β-cell apoptosis by binding to the GR and inducing DR5 and TRAIL pathway.

scholarly journals Deficiency of VCP-Interacting Membrane Selenoprotein (VIMP) Leads to G1 Cell Cycle Arrest and Cell Death in MIN6 Insulinoma Cells

2018 ◽  
Vol 51 (5) ◽  
pp. 2185-2197 ◽  
Author(s):  
Lili Men ◽  
Juan Sun ◽  
Decheng Ren
Keyword(s):  
Cell Cycle ◽  
Cell Death ◽  
Insulin Secretion ◽  
Cell Apoptosis ◽  
Β Cells ◽  
Β Cell ◽  
Cycle Arrest ◽  
G1 Cell Cycle Arrest ◽  
Insulinoma Cells

Background/Aims: VCP-interacting membrane selenoprotein (VIMP), an ER resident selenoprotein, is highly expressed in β-cells, however, the role of VIMP in β-cells has not been characterized. In this study, we studied the relationship between VIMP deficiency and β-cell survival in MIN6 insulinoma cells. Methods: To determine the role of VIMP in β-cells, lentiviral VIMP shRNAs were used to knock down (KD) expression of VIMP in MIN6 cells. Cell death was quantified by propidium iodide (PI) staining followed by flow cytometric analyses using a FACS Caliber and FlowJo software. Cell apoptosis and proliferation were determined by TUNEL assay and Ki67 staining, respectively. Cell cycle was analyzed after PI staining. Results: The results show that 1) VIMP suppression induces β-cell apoptosis, which is associated with a decrease in Bcl-xL, and the β-cell apoptosis induced by VIMP suppression can be inhibited by overexpression of Bcl-xL; 2) VIMP knockdown (KD) decreases cell proliferation and G1 cell cycle arrest by accumulating p27 and decreasing E2F1; 3) VIMP KD suppresses unfolded protein response (UPR) activation by regulating the IRE1α and PERK pathways; 4) VIMP KD increases insulin secretion. Conclusion: These results suggest that VIMP may function as a novel regulator to modulate β-cell survival, proliferation, cell cycle, UPR and insulin secretion in MIN6 cells.

Differential activation of ER stress and apoptosis in response to chronically elevated free fatty acids in pancreatic β-cells

2008 ◽  
Vol 294 (3) ◽  
pp. E540-E550 ◽  
Author(s):  
Elida Lai ◽  
George Bikopoulos ◽  
Michael B. Wheeler ◽  
Maria Rozakis-Adcock ◽  
Allen Volchuk
Keyword(s):  
Er Stress ◽  
Cell Lines ◽  
Cell Apoptosis ◽  
Human Islets ◽  
Pancreatic Β Cell ◽  
Β Cell ◽  
Min6 Cells ◽  
Relative Contribution ◽  
Induced Apoptosis

Chronic exposure to elevated saturated free fatty acid (FFA) levels has been shown to induce endoplasmic reticulum (ER) stress that may contribute to promoting pancreatic β-cell apoptosis. Here, we compared the effects of FFAs on apoptosis and ER stress in human islets and two pancreatic β-cell lines, rat INS-1 and mouse MIN6 cells. Isolated human islets cultured in vitro underwent apoptosis, and markers of ER stress pathways were elevated by chronic palmitate exposure. Palmitate also induced apoptosis in MIN6 and INS-1 cells, although the former were more resistant to both apoptosis and ER stress. MIN6 cells were found to express significantly higher levels of ER chaperone proteins than INS-1 cells, which likely accounts for the ER stress resistance. We attempted to determine the relative contribution that ER stress plays in palmitate-induced β-cell apoptosis. Although overexpressing GRP78 in INS-1 cells partially reduced susceptibility to thapsigargin, this failed to reduce palmitate-induced ER stress or apoptosis. In INS-1 cells, palmitate induced apoptosis at concentrations that did not result in significant ER stress. Finally, MIN6 cells depleted of GRP78 were more susceptible to tunicamycin-induced apoptosis but not to palmitate-induced apoptosis compared with control cells. These results suggest that ER stress is likely not the main mechanism involved in palmitate-induced apoptosis in β-cell lines. Human islets and MIN6 cells were found to express high levels of stearoyl-CoA desaturase-1 compared with INS-1 cells, which may account for the decreased susceptibility of these cells to the cytotoxic effects of palmitate.

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