Dual Functional Effects of Interleukin-1β on Purine Nucleotides and Insulin Secretion in Rat Islets and INS-1 Cells

Meredith, Melissa; Rabaglia, Mary E.; Corbett, John A.; Metz, Stewart A.

doi:10.2337/diab.45.12.1783

Cited by 21 publications

(10 citation statements)

References 37 publications

(90 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…8). Our results are consistent with a previous report of effects of proinflammatory cytokines to decrease ␤-cell ATP levels (28). However, both the lack of effect of cytokines on ATP levels in cytokine-resistant cell lines and the effect of camptothecin to increase ATP levels in ␤-cells are novel observations.…”

Section: Resultssupporting

confidence: 93%

Pro- and Antiapoptotic Proteins Regulate Apoptosis but Do Not Protect Against Cytokine-Mediated Cytotoxicity in Rat Islets and β-Cell Lines

Collier

Fueger²,

Hohmeier³

et al. 2006

Diabetes

View full text Add to dashboard Cite

Type 1 diabetes results from islet ␤-cell death and dysfunction induced by an autoimmune mechanism. Proinflammatory cytokines such as interleukin-1␤ and ␥-interferon are mediators of this ␤-cell cytotoxicity, but the mechanism by which damage occurs is not well understood. In the current study, we present multiple lines of evidence supporting the conclusion that cytokine-induced killing of rat ␤-cells occurs predominantly by a nonapoptotic mechanism, including the following: 1) A rat ␤-cell line selected for resistance to cytokine-induced cytotoxicity (833/15) is equally sensitive to killing by the apoptosis-inducing agents camptothecin and etoposide as a cytokine-sensitive cell line (832/ 13). 2) Overexpression of a constitutively active form of the antiapoptotic protein kinase Akt1 in 832/13 cells provides significant protection against cell killing induced by camptothecin and etoposide but no protection against cytokine-mediated damage. 3) Small interfering RNA-mediated suppression of the proapoptotic protein Bax enhances viability of 832/13 cells upon exposure to the known apoptosis-inducing drugs but not the inflammatory cytokines. 4) Exposure of primary rat islets or 832/13 cells to the inflammatory cytokines causes cell death as evidenced by the release of adenylate kinase activity into the cell medium, with no attendant increase in caspase 3 activation or annexin V staining. In contrast, camptothecin-and etoposide-induced killing is associated with robust increases in caspase 3 activation and annexin V staining. 5) Camptothecin increases cellular ATP levels, whereas inflammatory cytokines lower ATP levels in both ␤-cell lines and primary islets. We conclude that proinflammatory cytokines cause ␤-cell cytotoxicity primarily through a nonapoptotic mechanism linked to a decline in ATP levels.

show abstract

Section: Resultssupporting

confidence: 93%

Pro- and Antiapoptotic Proteins Regulate Apoptosis but Do Not Protect Against Cytokine-Mediated Cytotoxicity in Rat Islets and β-Cell Lines

Collier

Fueger²,

Hohmeier³

et al. 2006

Diabetes

View full text Add to dashboard Cite

show abstract

“…Our results indicate that more studies in vivo are required to determine whether, like antecedent generations of immunosuppressives, MPA is toxic to ␤-cells and could induce ␤-cell depletion, which, in turn, might lead to a recurrence of an insulin-dependent state over time in patients with insulin-dependent diabetes who received a pancreas or islet graft. Furthermore, interleukin-1␤ (which is widely accepted as a cytokine involved with ␤-cell death in type 1 diabetes) profoundly reduces GTP in ␤-cells (75) and induces apoptotic death (76). The current studies suggest that these events might be integrally related.…”

Section: Discussionmentioning

confidence: 64%

Prolonged Depletion of Guanosine Triphosphate Induces Death of Insulin-Secreting Cells by Apoptosis

1998

Endocrinology

View full text Add to dashboard Cite

Inhibitors of IMP dehydrogenase, such as mycophenolic acid (MPA) and mizoribine, which deplete cellular GTP, are used clinically as immunosuppressive drugs. The prolonged effect of such agents on insulin-secreting ␤-cells (HIT-T15 and INS-1) was investigated. Both MPA and mizoribine inhibited mitogenesis, as reflected by [3 H]thymidine incorporation. Cell number, DNA and protein contents, and cell (metabolic) viability were decreased by about 30%, 60%, and 80% after treatment of HIT cells with clinically relevant concentrations (e.g. 1 g/ml) of MPA for 1, 2, and 4 days, respectively. Mizoribine (48 h) similarly induced the death of HIT cells. INS-1 cells also were damaged by prolonged MPA treatment. MPA-treated HIT cells displayed a strong and localized staining with a DNA-binding dye (propidium iodide), suggesting condensation and fragmentation of DNA, which were confirmed by detection of DNA laddering in multiples of about 180 bp. DNA fragmentation was observed after 24-h MPA treatment and was dose dependent (29%, 49%, and 70% of cells were affected after 48-h exposure to 1, 3, and 10 g/ml MPA, respectively). Examination of MPA-treated cells by electron microscopy revealed typical signs of apoptosis: condensed and marginated chromatin, apoptotic bodies, cytosolic vacuolization, and loss of microvilli. MPAinduced cell death was almost totally prevented by supplementation with guanosine, but not with adenosine or deoxyguanosine, indicating a specific effect of GTP depletion. An inhibitor of protein isoprenylation (lovastatin, 10 -100 M for 2-3 days) induced cell death and DNA degradation similar to those induced by sustained GTP depletion, suggesting a mediatory role of posttranslationally modified GTPbinding proteins. Indeed, impeding the function of G proteins of the Rho family (via glucosylation using Clostridium difficile toxin B), although not itself inducing apoptosis, potentiated cell death induced by MPA or lovastatin. These findings indicate that prolonged depletion of GTP induces ␤-cell death compatible with apoptosis; this probably involves a direct impairment of GTP-dependent RNA-primed DNA synthesis, but also appears to be modulated by small GTPbinding proteins. Treatment of intact adult rat islets (the ␤-cells of which replicate slowly) induced a modest, but definite, death by apoptosis over 1-to 3-day periods. Thus, more prolonged use of the new generation of immunosuppressive agents exemplified by MPA might have deleterious effects on the survival of islet or pancreas grafts. (Endocrinology 139: 3752-3762, 1998) G TP IS required for many biological activities in the cell, e.g. synthesis of DNA, RNA, and proteins; nutrient metabolism; and cell signaling. It is well established that GTP-binding proteins play a diversity of roles as switches in cell growth, receptor activation, exocytosis, ion channel conductivity, and change in cell shape (1, 2).Over the past several years, the roles of GTP and GTPbinding proteins in the physiology of the normal pancreatic ␤-cell have been studied in our la...

show abstract

“…In addition, eliminating the ROS using antioxidants is protective, while inhibiting ROS scavenging enzymes, such as superoxide dismutase, enhances cell death [57]. This mechanism is reminiscent of β-cell death in response to cytokines: ROS levels accumulate [58], [59], mitochondrial function is impaired [60], ATP levels decrease [11], [61], and no detectable markers of apoptosis are present despite large increases in cell death [9], [11]; ROS destroying enzymes also provide protection against pro-inflammatory cytokines in pancreatic β-cells [62]. Thus, the data do not seem to support apoptosis as the predominant form of β-cell death in response to pro-inflammatory cytokines.…”

Section: Discussionmentioning

confidence: 99%

Pancreatic β-Cell Death in Response to Pro-Inflammatory Cytokines Is Distinct from Genuine Apoptosis

et al. 2011

View full text Add to dashboard Cite

A reduction in functional β-cell mass leads to both major forms of diabetes; pro-inflammatory cytokines, such as interleukin-1beta (IL-1β) and gamma-interferon (γ-IFN), activate signaling pathways that direct pancreatic β-cell death and dysfunction. However, the molecular mechanism of β-cell death in this context is not well understood. In this report, we tested the hypothesis that individual cellular death pathways display characteristic phenotypes that allow them to be distinguished by the precise biochemical and metabolic responses that occur during stimulus-specific initiation. Using 832/13 and INS-1E rat insulinoma cells and isolated rat islets, we provide evidence that apoptosis is unlikely to be the primary pathway underlying β-cell death in response to IL-1β+γ-IFN. This conclusion was reached via the experimental results of several different interdisciplinary strategies, which included: 1) tandem mass spectrometry to delineate the metabolic differences between IL-1β+γ-IFN exposure versus apoptotic induction by camptothecin and 2) pharmacological and molecular interference with either NF-κB activity or apoptosome formation. These approaches provided clear distinctions in cell death pathways initiated by pro-inflammatory cytokines and bona fide inducers of apoptosis. Collectively, the results reported herein demonstrate that pancreatic β-cells undergo apoptosis in response to camptothecin or staurosporine, but not pro-inflammatory cytokines.

show abstract

Dual Functional Effects of Interleukin-1β on Purine Nucleotides and Insulin Secretion in Rat Islets and INS-1 Cells

Cited by 21 publications

References 37 publications

Pro- and Antiapoptotic Proteins Regulate Apoptosis but Do Not Protect Against Cytokine-Mediated Cytotoxicity in Rat Islets and β-Cell Lines

Pro- and Antiapoptotic Proteins Regulate Apoptosis but Do Not Protect Against Cytokine-Mediated Cytotoxicity in Rat Islets and β-Cell Lines

Prolonged Depletion of Guanosine Triphosphate Induces Death of Insulin-Secreting Cells by Apoptosis

Pancreatic β-Cell Death in Response to Pro-Inflammatory Cytokines Is Distinct from Genuine Apoptosis

Contact Info

Product

Resources

About