Maitotoxin‐Induced Intracellular Calcium Rise in PC 12 Cells: Involvement of Dihydropyridine‐Sensitive and ω‐Conotoxin‐Sensitive Calcium Channels and Phosphoinositide Breakdown

Meucci, Olimpia; Grimaldi, M.; Scorziello, Antonella; Govoni, Stefano; Bergamaschi, S.; Yasumoto, Takeshi; Schettini, Gennaro

doi:10.1111/j.1471-4159.1992.tb09422.x

Cited by 20 publications

(12 citation statements)

References 38 publications

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“…MTX has been shown to activate both voltage-sensitive and ligand-gated calcium channels (43) and stimulate inositol phosphate produc- (44). In contrast to basal TG activity, the calcium-stimulated increases in in situ TG activity correlated with the observed increases in tTG levels (r 2 ϭ 0.758) after RA treatment (Fig.…”

Section: Effects Of Ra On Ttg Expression and In Vitro Tg Activity-mentioning

confidence: 83%

“…6, E and F), containing an abundance of ER membranes where calciumreleasing inositol 1,4,5-trisphosphate receptors are concentrated. Additionally, the MTX-elicited increase in intracellular calcium by activation of ligand and voltage-gated calcium channels (43) stimulates phospholipase activity and inositol phosphate production (44). Thus, it can be speculated that the transamidating activity of tTG is selectively increased by the release of intracellular calcium stores; however, further studies are required.…”

Section: Modulation Of Transglutaminase In Situ By Ca 2ϩ and Gtpmentioning

confidence: 99%

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Modulation of the in Situ Activity of Tissue Transglutaminase by Calcium and GTP

Zhang

Lesort

Guttmann

et al. 1998

Journal of Biological Chemistry

196

192

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Tissue transglutaminase (tTG) is a calcium-dependent enzyme that catalyzes the posttranslational modification of proteins by transamidation of specific polypeptide-bound glutamine residues. Previous in vitro studies have demonstrated that the transamidating activity of tTG requires calcium and is inhibited by GTP. To investigate the endogenous regulation of tTG, a quantitative in situ transglutaminase (TG) activity assay was developed. Treatment of human neuroblastoma SH-SY5Y cells with retinoic acid (RA) resulted in a significant increase in tTG levels and in vitro TG activity. In contrast, basal in situ TG activity did not increase concurrently with RA-induced increased tTG levels. However, stimulation of cells with the calcium-mobilizing drug maitotoxin (MTX) resulted in increases in in situ TG activity that correlated (r 2 ‫؍‬ 0.76) with increased tTG levels. To examine the effects of GTP on in situ TG activity, tiazofurin, a drug that selectively decreases GTP levels, was used. Depletion of GTP resulted in a significant increase in in situ TG activity; however, treatment of SH-SY5Y cells with a combination of MTX and tiazofurin resulted in significantly less in situ TG activity compared with treatment with MTX alone. This raised the possibility of calcium-dependent proteolysis due to the effects of tiazofurin, because in vitro GTP protects tTG against proteolysis by trypsin. Studies with a selective membrane permeable calpain inhibitor indicated that tTG is likely to be an endogenous substrate of calpain, and that depletion of GTP increases tTG degradation after elevation of intracellular calcium levels. TG activity was also increased in response to activation of muscarinic cholinergic receptors, which increases intracellular calcium through inositol 1,4,5-trisphosphate generation. The results of these experiments demonstrate that selective changes in calcium and GTP regulate the activity and levels of tTG in situ.

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Section: Effects Of Ra On Ttg Expression and In Vitro Tg Activity-mentioning

confidence: 83%

Section: Modulation Of Transglutaminase In Situ By Ca 2ϩ and Gtpmentioning

confidence: 99%

Modulation of the in Situ Activity of Tissue Transglutaminase by Calcium and GTP

Zhang

Lesort

Guttmann

et al. 1998

Journal of Biological Chemistry

196

192

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“…Closure of K ATP channels and opening of VDCCs play a crucial role in Ca 2+ influx that triggers GSIS upon high-glucose stimulation (11). KCl, a membrane depolarizer, and maitotoxin, a calcium channel opener, induce Ca 2+ influx and subsequent insulin secretion (11,(25)(26)(27)(28). Thus, we examined the effects of L-cysteine treatment on KCl-and maitotoxin-induced insulin secretion by MIN6 cells; this treatment had little effect on insulin secretion ( Fig.…”

Section: Resultsmentioning

confidence: 99%

l -cysteine reversibly inhibits glucose-induced biphasic insulin secretion and ATP production by inactivating PKM2

Nakatsu

Horiuchi

Kano

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

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Increase in the concentration of plasma L-cysteine is closely associated with defective insulin secretion from pancreatic β-cells, which results in type 2 diabetes (T2D). In this study, we investigated the effects of prolonged L-cysteine treatment on glucosestimulated insulin secretion (GSIS) from mouse insulinoma 6 (MIN6) cells and from mouse pancreatic islets, and found that the treatment reversibly inhibited glucose-induced ATP production and resulting GSIS without affecting proinsulin and insulin synthesis. Comprehensive metabolic analyses using capillary electrophoresis time-of-flight mass spectrometry showed that prolonged L-cysteine treatment decreased the levels of pyruvate and its downstream metabolites. In addition, methyl pyruvate, a membrane-permeable form of pyruvate, rescued L-cysteine-induced inhibition of GSIS. Based on these results, we found that both in vitro and in MIN6 cells, L-cysteine specifically inhibited the activity of pyruvate kinase muscle isoform 2 (PKM2), an isoform of pyruvate kinases that catalyze the conversion of phosphoenolpyruvate to pyruvate. L-cysteine also induced PKM2 subunit dissociation (tetramers to dimers/monomers) in cells, which resulted in impaired glucose-induced ATP production for GSIS. DASA-10 (NCGC00181061, a substituted N,N′-diarylsulfonamide), a specific activator for PKM2, restored the tetramer formation and the activity of PKM2, glucoseinduced ATP production, and biphasic insulin secretion in L-cysteinetreated cells. Collectively, our results demonstrate that impaired insulin secretion due to exposure to L-cysteine resulted from its direct binding and inactivation of PKM2 and suggest that PKM2 is a potential therapeutic target for T2D.A metabolite, L-cysteine, is found in blood plasma, and its concentration is closely associated with an increase in fat mass and the body-mass index. These values are used as an index of obesity (1, 2), which is a major risk factor for type 2 diabetes (T2D) (3). The relationship between L-cysteine and diabetes has attracted attention because there is increasing evidence for a positive correlation between increases in plasma L-cysteine concentrations and the development and progression of diabetes. For example, increased plasma L-cysteine concentrations were associated with T2D in African American women (4), renal insufficiency [reduced glomerular filtration rate (GFR)] in T2D patients (5), obstructive sleep apnea [a risk factor for diabetes (6, 7)], and insulin resistance among Europeans (8).Reduced insulin secretion from pancreatic β-cells is the major cause of T2D (9, 10). Many investigators have studied the molecular mechanisms of glucose-stimulated insulin secretion (GSIS), which have been elucidated in detail. Elevated extracellular glucose concentration results in the enhancement of ATP production, an increased ATP/ADP ratio, the closure of ATP-sensitive K channels (K ATP channels), and depolarization (11). The resulting activation of voltage-dependent Ca 2+ channels (VDCCs) induces an influx of calcium ions and elevated...

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“…MTX, a highly potent marine toxin isolated from the dinoflagellate gambierdiscus toxicus, is an important molecular tool for the study of oncotic (necrotic) cell death [49,50]. MTX, known for its ability to stimulate calcium influx into cells through a series of biochemical processes that include activation of both voltage-sensitive and receptor-operated calcium channels [51,52], initiates calpain activation which eventually leads to cell death via cell lysis [40]. In our study, we confirmed that total aII-spectrin was degraded into SBDP150 and SBDP145 by calpaindominant MTX-induced necrosis.…”

Section: Discussionmentioning

confidence: 99%

Multiple alphaII-spectrin breakdown products distinguish calpain and caspase dominated necrotic and apoptotic cell death pathways

et al. 2009

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Apoptosis and oncotic necrosis in neuronal and glial cells have been documented in many neurological diseases. Distinguishing between these two major types of cell death in different neurological diseases is needed in order to better reveal the injury mechanisms so as to open up opportunities for therapy development. Accumulating evidence suggests apoptosis and oncosis epitomize the extreme ends of a broad spectrum of morphological and biochemical events. Biochemical markers that can distinguish between the calpain and caspase dominated types of cell death would help in this process. In this study, three chemical agents, maitotoxin (MTX), staurosporine (STS) and thylenediaminetetraacetic acid (EDTA), were used to induce different types of cell death in PC12 neuronal-like cells. MTX-induced necrosis, as determined by the increased levels of calpain-specific cleaved fragments of spectrin by antibodies specific to the calpain-cleaved 150 kDa alphaII-spectrin breakdown product (SBDP150) and 145 kDa alphaII-spectrin breakdown product (SBDP145). In this paradigm, there were no detectable SBDP150i and SBDP120 fragments as determined by antibodies specific to the caspase-cleaved specific fragments similar to those seen in the EDTA-mediated apoptotic PC-12 cells. In contrast to the calpain specific MTX necrosis treatment and the caspase EDTA apoptotic treatment is the STS treatment which induced both proteases as shown by the increase in all the SBDP fragments. Furthermore, compared to SBDP150, SBDP145 appears to be a more specific and sensitive biomarker for calpain activation. Taken together, our results suggested calpains and caspases which dominate the two major types of cell death could be independently discriminated by specifically examining the multiple alphaII-spectrin cleavage breakdown products.

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Maitotoxin‐Induced Intracellular Calcium Rise in PC 12 Cells: Involvement of Dihydropyridine‐Sensitive and ω‐Conotoxin‐Sensitive Calcium Channels and Phosphoinositide Breakdown

Cited by 20 publications

References 38 publications

Modulation of the in Situ Activity of Tissue Transglutaminase by Calcium and GTP

Modulation of the in Situ Activity of Tissue Transglutaminase by Calcium and GTP

l -cysteine reversibly inhibits glucose-induced biphasic insulin secretion and ATP production by inactivating PKM2

Multiple alphaII-spectrin breakdown products distinguish calpain and caspase dominated necrotic and apoptotic cell death pathways

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