Sustained Enhancement of Ca2+ Influx by Glibenclamide Induces Apoptosis in RINm5F Cells

Iwakura, Toshio; Fujimoto, Shimpei; Kagimoto, Shinji; Inada, Akira; Kubota, Akira; Someya, Yoshimichi; Ihara, Yu; Yamada, Yoshio; Seino, Yutaka

doi:10.1006/bbrc.2000.2616

Cited by 55 publications

(48 citation statements)

References 30 publications

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“…A precise localization of the resveratrol-binding site and a better understanding of the correlation between resveratrol (or glibenclamide) binding and apoptosis induction by this substance should be the subjects of future investigations. In most of the studies that report an apoptotic effect of sulfonylureas (10,14,17), a mechanism involving blockade of complete functional K ATP channels and depolarization-induced Ca 2ϩ influx into the cell is discussed. However, according to Rustenbeck et al (15), ␤-cell toxicity is not necessarily linked to the ability of these drugs to act as K ATP channel blockers.…”

Section: Discussionmentioning

confidence: 99%

Resveratrol Binds to the Sulfonylurea Receptor (SUR) and Induces Apoptosis in a SUR Subtype-specific Manner

Hambrock

Franz

Hiller

et al. 2007

Journal of Biological Chemistry

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Sulfonylurea receptors (SURs) constitute the regulatory subunits of ATP-sensitive K ؉ channels (K ATP channels). SUR binds nucleotides and synthetic K ATP channel modulators, e.g. the antidiabetic sulfonylurea glibenclamide, which acts as a channel blocker. However, knowledge about naturally occurring ligands of SUR is very limited. In this study, we show that the plant phenolic compound trans-resveratrol can bind to SUR and displace binding of glibenclamide. Electrophysiological measurements revealed that resveratrol is a blocker of pancreatic SUR1/ K IR 6.2 K ATP channels. We further demonstrate that, like glibenclamide, resveratrol induces enhanced apoptosis. This was shown by analyzing different apoptotic parameters (cell detachment, nuclear condensation and fragmentation, and activities of different caspase enzymes). The observed apoptotic effect was specific to cells expressing the SUR1 isoform and was not mediated by the electrical activity of K ATP channels, as it was observed in human embryonic kidney 293 cells expressing SUR1 alone. Enhanced susceptibility to resveratrol was not observed in pancreatic ␤-cells from SUR1 knock-out mice or in cells expressing the isoform SUR2A or SUR2B or the mutant SUR1(M1289T). Resveratrol was much more potent than glibenclamide in inducing SUR1-specific apoptosis. Treatment with etoposide, a classical inducer of apoptosis, did not result in SUR isoform-specific apoptosis. In conclusion, resveratrol is a natural SUR ligand that can induce apoptosis in a SUR isoform-specific manner. Considering the tissue-specific expression patterns of SUR isoforms and the possible effects of SUR mutations on susceptibility to apoptosis, these observations could be important for diabetes and/or cancer research.Sulfonylurea receptors (SURs) 2 are members of the ATPbinding cassette protein family (subfamily C). SURs are known to be the important regulatory subunits of ATP-sensitive K ϩ channels (K ATP channels). These channels are heteromeric complexes composed of four SUR subunits that surround a central pore formed by four subunits from the K IR 6.x family. K ATP channels found in various tissues exhibit distinct physiological and pharmacological properties because of the combination of different subunit isoforms (reviewed in Ref. 1). In addition to two nucleotide-binding domains, SUR possesses binding sites for synthetic K ATP channel modulators. The binding sites for blockers and openers are different, but they are linked via complex allosteric interactions (2, 3).Because of their nucleotide sensitivity, K ATP channels couple the energy metabolism of a cell to the membrane potential. This is important in the pancreatic ␤-cell, in which closure of K ATP channels triggers insulin secretion via membrane depolarization in response to changes in blood glucose levels (4 -6). K ATP channel-blocking drugs such as the sulfonylureas and the glinides can promote insulin secretion and are used in the treatment of diabetes type 2. Insulin secretion is also modulated and amplified by other pathways...

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Section: Discussionmentioning

confidence: 99%

Resveratrol Binds to the Sulfonylurea Receptor (SUR) and Induces Apoptosis in a SUR Subtype-specific Manner

Hambrock

Franz

Hiller

et al. 2007

Journal of Biological Chemistry

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“…There is also compelling evidence that Ca 2+ , released through select sources such as the IP3 regulated release, is preferentially taken up by mitochondria, possibly due to proximity of the mitochondrial import sites with the ER release sites (Szalai et al, 1999). In fact, mitochondrial uptake of large amounts of Ca 2+ is thought to be an important factor in apoptosis (Andreyev and Fiskum, 1999;Gutierrez et al, 1999;Stridh et al, 1999;Iwakura et al, 2000). Recent studies show that disruption of Dc m also induces mitochondrial permeability pore transition, a major site of mitochondrial Ca 2+ transport.…”

Section: Discussionmentioning

confidence: 99%

Mitochondrial stress-induced calcium signaling, phenotypic changes and invasive behavior in human lung carcinoma A549 cells

Amuthan

Biswas

Ananadatheerthavarada

et al. 2002

Oncogene

227

271

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We have investigated mechanisms of mitochondrial stressinduced phenotypic changes and cell invasion in tumorigenic but poorly invasive human pulmonary carcinoma A549 cells that were partly depleted of mitochondrial DNA (mtDNA). Depletion of mtDNA (genetic stress) caused a markedly lower electron transport-coupled ATP synthesis, loss of mitochondrial membrane potential, elevation of steady state [Ca 2+ ] c , and notably induction of both glycolysis and gluconeogenic pathway enzymes. Markers of tumor invasion, cathepsin L and TGFb1, were overexpressed; calcium-dependent MAP kinases (ERK1 and ERK2) and calcineurin were activated. The levels of anti-apoptotic proteins Bcl2 and Bcl-X L were increased, and the cellular levels of pro-apoptotic proteins Bid and Bax were reduced. Both mtDNA-depleted cells (genetic stress) and control cells treated with carbonyl cyanide m-chlorophenylhydrazone (metabolic stress) exhibited higher invasive behavior than control cells in a Matrigel basement membrane matrix assay system. MtDNA-depleted cells stably expressing anti-sense cathepsin L RNA, TGFb1 RNA, or treated with specific inhibitors showed reduced invasion. Reverted cells with 80% of control cell mtDNA exhibited marker protein levels, cell morphology and invasive property closer to control cells. Our results suggest that the mitochondriato-nucleus signaling pathway operating through increased [Ca 2+ ] c plays an important role in cancer progression and metastasis. Oncogene (2002Oncogene ( ) 21, 7839 -7849. doi:10.1038 Keywords: mitochondria; calcium signaling; cathepsin L; TGFb; tumor invasion; MAP kinases IntroductionThe role of mitochondria in carcinogenesis was initially suggested by Warburg et al. (1926;Warburg, 1956), based on the observation that number of experimentally induced rodent tumors exhibit reduced respiration-coupled oxidative metabolism and increased glycolysis. Since then, altered mitochondrial morphology, as well as changes in mitochondrial enzyme patterns and membrane transport systems, have been described in several tumor types (Zafar et al., 1982). Cell fusion studies (Jonasson et al., 1977;Howell and Sager, 1978;Giguere and Morais, 1981) also suggest that unknown cytoplasmic elements may play roles in carcinogenesis. Fusion between normal cytoplasm and karyoplasts from malignant phenotypes resulted in the ablation of tumorigenicity (Israel and Schaeffer, 1987) and conversely, the cytoplasm of the malignant phenotype could transfer the malignancy to the karyoplasts from normal cells (Israel and Schaeffer, 1988). Studies using mitochondrial DNA (mtDNA)-depleted tumor cells to evaluate the role of mtDNA, and thus mitochondrial function in tumorigenicity have yielded mixed results (Giguere and Morais, 1981;Morais et al., 1994;Cavalli et al., 1997;Cavalli and Liang, 1998;Hofhaus and Gattermann, 1999). Cavalli et al. (1997) found diminished tumor formation by glioblastoma cells following depletion of mtDNA (r 0 cells) with ethidium bromide treatment, while Morais et al. (1994) found increased capacity to p...

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“…In this context, modulation of the ␤-cell ATPsensitive K ϩ (K ATP ) channel (K ATP channels are octamers composed of four inwardly rectifying K ϩ channels [Kir 6.2] and four sulfonylurea receptors [SUR1]) appears particularly interesting. Indeed, closure of the K ATP channels by the sulfonylureas tolbutamide and glibenclamide may induce Ca 2ϩ -dependent ␤-cell apoptosis in rodent and human islets (12,69,70). This effect was observed only in vitro and not consistently (71).…”

Section: Anti-diabetic Drugs: Beneficial or Harmful?mentioning

confidence: 99%

Mechanisms of β-Cell Death in Type 2 Diabetes

et al. 2005

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A decrease in the number of functional insulin-producing ␤-cells contributes to the pathophysiology of type 2 diabetes. Opinions diverge regarding the relative contribution of a decrease in ␤-cell mass versus an intrinsic defect in the secretory machinery. Here we review the evidence that glucose, dyslipidemia, cytokines, leptin, autoimmunity, and some sulfonylureas may contribute to the maladaptation of ␤-cells. With respect to these causal factors, we focus on Fas, the ATP-sensitive K ؉ channel, insulin receptor substrate 2, oxidative stress, nuclear factor-B, endoplasmic reticulum stress, and mitochondrial dysfunction as their respective mechanisms of action. Interestingly, most of these factors are involved in inflammatory processes in addition to playing a role in both the regulation of ␤-cell secretory function and cell turnover. Thus, the mechanisms regulating ␤-cell proliferation, apoptosis, and function are inseparable processes. Diabetes 54 (Suppl. 2):S108 -S113, 2005 F or many years, the contribution of a reduction in ␤-cell mass to the development of type 2 diabetes was heavily debated. Recently, several publications have convincingly confirmed this hypothesis (1-3), leading to a rapid overemphasis of this etiological factor. Indeed, other mechanisms contributing to the failure of the ␤-cell to produce enough insulin appear more and more neglected. While we strongly believe that ␤-cell destruction is an important etiological factor in the development and progression of type 2 diabetes, in this review, we will highlight evidence that this is not dissociable from an intrinsic secretory defect. We will show that pathways regulating ␤-cell turnover are also implicated in ␤-cell insulin secretory function. It follows that adaptive mechanisms of function and mass share common regulatory pathways and will therefore act in concert. Depending on the prevailing concentration and the intracellular pathways activated, some factors may be deleterious to ␤-cell mass while enhancing insulin secretion, protective to the ␤-cell while inhibiting function, or even protective to the ␤-cell while enhancing function. It will become apparent that the failure of the ␤-cell in type 2 diabetes is akin to a multifactorial equation, with an overall negative result.Thus, although we will review the factors and mechanisms regulating ␤-cell mass individually, only in a minority of diabetic patients does one single etiological factor underlie the failure of the ␤-cell. In addition to maturityonset diabetes of the young, another example of this is autoimmune-mediated destruction of ␤-cells in young lean individuals. However, given that the incidence of type 1 diabetes increases with obesity (4), that insulin resistance is a risk factor for the progression of this condition (5), and that ϳ50% of the general population carry the same genetic predisposition (6), this example already implicates multiple etiological factors. Recognition of ␤-cell destruction not only in type 1 but also in type 2 diabetes led us to recently propose a unif...

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Sustained Enhancement of Ca2+ Influx by Glibenclamide Induces Apoptosis in RINm5F Cells

Cited by 55 publications

References 30 publications

Resveratrol Binds to the Sulfonylurea Receptor (SUR) and Induces Apoptosis in a SUR Subtype-specific Manner

Resveratrol Binds to the Sulfonylurea Receptor (SUR) and Induces Apoptosis in a SUR Subtype-specific Manner

Mitochondrial stress-induced calcium signaling, phenotypic changes and invasive behavior in human lung carcinoma A549 cells

Mechanisms of β-Cell Death in Type 2 Diabetes

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