Manumycin A and Its Analogues Are Irreversible Inhibitors of Neutral Sphingomyelinase

Arenz, Christoph; Thutewohl, Michael; Block, Oliver; Waldmann, Herbert; Altenbach, Hans‐Josef; Giannis, Athanassios

doi:10.1002/1439-7633(20010202)2:2<141::aid-cbic141>3.0.co;2-p

Cited by 72 publications

(44 citation statements)

References 33 publications

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“…1 A, dashed lines). NGF-induced motor neuron death was blocked by manumycin A (10 nM) and GW4869 (100 nM), specific inhibitors of nSMase (Arenz et al, 2001;Luberto et al, 2002) (Fig. 1 A).…”

Section: Resultsmentioning

confidence: 86%

Mitochondrial Superoxide Production and Nuclear Factor Erythroid 2-Related Factor 2 Activation in p75 Neurotrophin Receptor-Induced Motor Neuron Apoptosis

Pehar

Vargas²,

Robinson³

et al. 2007

J. Neurosci.

111

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Nerve growth factor (NGF) can induce apoptosis by signaling through the p75 neurotrophin receptor (p75 NTR ) in several nerve cell populations. Cultured embryonic motor neurons expressing p75 NTR are not vulnerable to NGF unless they are exposed to an exogenous flux of nitric oxide ( ⅐ NO). In the present study, we show that p75 NTR -mediated apoptosis in motor neurons involved neutral sphingomyelinase activation, increased mitochondrial superoxide production, and cytochrome c release to the cytosol. The mitochondria-targeted antioxidants mitoQ and mitoCP prevented neuronal loss, further evidencing the role of mitochondria in NGF-induced apoptosis. In motor neurons overexpressing the amyotrophic lateral sclerosis (ALS)-linked superoxide dismutase 1 G93A (SOD1 G93A ) mutation, NGF induced apoptosis even in the absence of an external source of ⅐ NO. The increased susceptibility of SOD1 G93A motor neurons to NGF was associated to decreased nuclear factor erythroid 2-related factor 2 (Nrf2) expression and downregulation of the enzymes involved in glutathione biosynthesis. In agreement, depletion of glutathione in nontransgenic motor neurons reproduced the effect of SOD1 G93A expression, increasing their sensitivity to NGF. In contrast, rising antioxidant defenses by Nrf2 activation prevented NGF-induced apoptosis. Together, our data indicate that p75 NTR -mediated motor neuron apoptosis involves ceramide-dependent increased mitochondrial superoxide production. This apoptotic pathway is facilitated by the expression of ALS-linked SOD1 mutations and critically modulated by Nrf2 activity.

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Section: Resultsmentioning

confidence: 86%

Mitochondrial Superoxide Production and Nuclear Factor Erythroid 2-Related Factor 2 Activation in p75 Neurotrophin Receptor-Induced Motor Neuron Apoptosis

Pehar

Vargas²,

Robinson³

et al. 2007

J. Neurosci.

111

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“…To inhibit A-Smase, we used imipramine, which induces proteolysis of the enzyme (Hurwitz et al, 1994;Grassmé et al, 1997;Jensen et al, 1999), and D609, a potent inhibitor of the phosphatidylcholine-specific phospholipase C, an enzyme known to be involved in A-SMase activation by TNF-␣, and other stimuli, through generation of diacylglycerol (Mü llerDecker, 1989;Schü tze et al, 1992;Wiegmann et al, 1994;Grassmé et al, 1997). Inhibition of N-SMase was obtained using two specific, direct inhibitors (i.e., scyphostatin and manumycin A) (Tanaka et al, 1997;Arenz et al, 2001). We tested the specificity of these compounds in our cell model.…”

Section: Resultsmentioning

confidence: 98%

Activation of Endothelial Nitric-Oxide Synthase by Tumor Necrosis Factor-α: A Novel Pathway Involving Sequential Activation of Neutral Sphingomyelinase, Phosphatidylinositol-3′ kinase, and Akt

Barsacchi¹,

Perrotta²,

Bulotta³

et al. 2003

Mol Pharmacol

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Activation of endothelial nitric-oxide synthase (eNOS) has been shown to occur through various pathways involving increases in the cytosolic Ca 2ϩ concentration, activation of the phosphatidylinositol-3Ј kinase/Akt pathway, as well as regulation by other kinases and by protein-protein interactions. We have recently reported that eNOS, expressed in an inducible HeLa Tet-off cell line, is activated by tumor necrosis factor-␣ (TNF-␣) in a previously undescribed pathway that involves the lipid messenger ceramide. We have now characterized this pathway. We report here that eNOS activation in response to TNF-␣ correlated with phosphorylation of Akt at Ser 473 and of eNOS itself at Ser 1179. Akt and eNOS phosphorylation, as well as eNOS activation, were blocked by inhibitors of both phosphatidylinositol-3Ј kinase and neutral sphingomyelinase. In contrast, although acid sphingomyelinase was also stimulated by TNF-␣, its inhibition was without effect. The activation of neutral sphingomyelinase triggered by TNF-␣ was insensitive to phosphatidylinositol-3Ј kinase inhibitors. Taken together, these results indicate that eNOS activation by TNF-␣ occurs through sequential activation of neutral sphingomyelinase and of the phosphatidylinositol-3Ј kinase/Akt pathway. The time course of eNOS activation induced through this pathway was markedly different from that triggered by ATP and epidermal growth factor, which activate eNOS through an increase in intracellular Ca 2ϩ concentration and through a sphingomyelinase-independent stimulation of the phosphatidylinositol-3Ј kinase/Akt pathway, respectively. The novel pathway of activation of eNOS described here may have broad biological relevance because neutral sphingomyelinase is activated not only by TNF-␣ but also by a variety of other physiological and pathological stimuli.

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“…To inhibit A-SMase, we used imipramine, which induces proteolysis of the enzyme (31,(33)(34)(35), and D609, which inhibits the phosphatidylcholine-specific phospholipase C, an enzyme known to be involved in A-SMase activation by LPS and other stimuli through generation of diacylglycerol (22,23,31,33,39,43). As controls of specificity we used scyphostatin and manumycin A, which are inhibitors of the neutral SMase (39,44,45). When administered alone, none of the compounds had any effect on basal sphingomyelin hydrolysis (not shown).…”

Section: Lps Activates A-smase and Generates Ceramide In Immature Hummentioning

confidence: 99%

Activation of Acid Sphingomyelinase and Its Inhibition by the Nitric Oxide/Cyclic Guanosine 3′,5′-Monophosphate Pathway: Key Events in Escherichia coli-Elicited Apoptosis of Dendritic Cells

Falcone

Perrotta

Palma

et al. 2004

The Journal of Immunology

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Depletion of dendritic cells (DCs) via apoptosis contributes to sepsis-induced immune suppression. The mechanisms leading to DC apoptosis during sepsis are not known. In this study we report that immature DCs undergo apoptosis when treated with high numbers of Escherichia coli. This effect was mimicked by high concentrations of LPS. Apoptosis was accompanied by generation of ceramide through activation of acid sphingomyelinase (A-SMase), was prevented by inhibitors of this enzyme, and was restored by exogenous ceramide. Compared with immature DCs, mature DCs expressed significantly reduced levels of A-SMase, did not generate ceramide in response to E. coli or LPS, and were insensitive to E. coli- and LPS-triggered apoptosis. However, sensitivity to apoptosis was restored by addition of exogenous A-SMase or ceramide. Furthermore, inhibition of A-SMase activation and ceramide generation was found to be the mechanism through which the immune-modulating messenger NO protects immature DCs from the apoptogenic effects of E. coli and LPS. NO acted through formation of cGMP and stimulation of the cGMP-dependent protein kinase. The relevance of A-SMase and its inhibition by NO/cGMP were confirmed in a mouse model of LPS-induced sepsis. DC apoptosis was significantly higher in inducible NO synthase-deficient mice than in wild-type animals and was significantly reduced by treatment ex vivo with NO, cGMP, or the A-SMase inhibitor imipramine. Thus, A-SMase plays a central role in E. coli/LPS-induced DC apoptosis and its inhibition by NO, and it might be a target of new therapeutic approaches to sepsis.

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Manumycin A and Its Analogues Are Irreversible Inhibitors of Neutral Sphingomyelinase

Cited by 72 publications

References 33 publications

Mitochondrial Superoxide Production and Nuclear Factor Erythroid 2-Related Factor 2 Activation in p75 Neurotrophin Receptor-Induced Motor Neuron Apoptosis

Mitochondrial Superoxide Production and Nuclear Factor Erythroid 2-Related Factor 2 Activation in p75 Neurotrophin Receptor-Induced Motor Neuron Apoptosis

Activation of Endothelial Nitric-Oxide Synthase by Tumor Necrosis Factor-α: A Novel Pathway Involving Sequential Activation of Neutral Sphingomyelinase, Phosphatidylinositol-3′ kinase, and Akt

Activation of Acid Sphingomyelinase and Its Inhibition by the Nitric Oxide/Cyclic Guanosine 3′,5′-Monophosphate Pathway: Key Events in Escherichia coli-Elicited Apoptosis of Dendritic Cells

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