Inhibition of DNA primase by sphingosine and its analogues parallels with their growth suppression of cultured human leukemic cells

Tamiya‐Koizumi, Keiko; Murate, Takashi; Suzuki, Motoshi; Simbulan, Cynthia Marie G.; Nakagawa, Masako; Takemura, Masaharu; Furuta, Keigo; Izuta, Shunji; Yoshida, Shonen

doi:10.1080/15216549700202271

Cited by 38 publications

(44 citation statements)

References 7 publications

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“…In this respect, the phytoceramide nature of the C. albicans PLM lipid moiety raises an important question (26). Although our knowledge of phytoceramide and phytosphingosine synthesis or hydrolysis is still embryonic, the presence of these molecules in mammalian cells has been demonstrated, and several studies have suggested that, like ceramide, phytosphingosine may play an important role in cell growth or death of eukaryotic cells (56,57). Due to their critical role in cell integrity, it is interesting to note that ceramide biosynthetic pathways are also critical for the establishment of fungal pathogens in the host.…”

Section: Discussionmentioning

confidence: 99%

Candida albicans Phospholipomannan Promotes Survival of Phagocytosed Yeasts through Modulation of Bad Phosphorylation and Macrophage Apoptosis

Ibata-Ombetta

Idziorek

Trinel

et al. 2003

Journal of Biological Chemistry

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The surface of the pathogenic yeast Candida albicans is coated with phospholipomannan (PLM), a phylogenetically unique glycolipid composed of ␤-1,2-oligomannosides and phytoceramide. This study compared the specific contribution of PLM to the modulation of signaling pathways linked to the survival of C. albicans in macrophages in contrast to Saccharomyces cerevisiae. C. albicans endocytosis by J774 and disregulation of the ERK1/2 signal transduction pathway was associated downstream with a reduction in Bad Ser-112 phosphorylation and disappearance of free Bcl-2. This suggested an apoptotic effect, which was confirmed by staining of phosphatidylserine in the macrophage outer membrane. The addition of PLM to macrophages incubated with S. cerevisiae mimicked each of the disregulation steps observed with C. albicans and promoted the survival of S. cerevisiae. Externalization of membranous phosphatidylserine, loss of mitochondrial integrity, and DNA fragmentation induced by PLM showed that this molecule promoted yeast survival by inducing host cell death. These findings suggest strongly that PLM is a virulence attribute of C. albicans and that elucidation of the relationship between structure and apoptotic activity is an innovative field of research.

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Section: Discussionmentioning

confidence: 99%

Candida albicans Phospholipomannan Promotes Survival of Phagocytosed Yeasts through Modulation of Bad Phosphorylation and Macrophage Apoptosis

Ibata-Ombetta

Idziorek

Trinel

et al. 2003

Journal of Biological Chemistry

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“…(23) Moreover, sphingosine inhibits RNA primers and DNA primers, but not DNA polymerases, to induce cell death. (19,24) However, the study of another sphingosine analog, phytosphingosine, has recently begun.In the present study, we therefore examined the precise mechanism of phytosphingosine-mediated apoptosis in T-cell lymphoma Jurkat cells in comparison with sphingosine. It was found that phytosphingosine, almost identically to sphingosine, significantly induces apoptosis in Jurkat cells.…”

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confidence: 99%

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confidence: 99%

Phytosphingosine induced mitochondria‐involved apoptosis

et al. 2005

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Sphingolipids are putative intracellular signal mediators in cell differentiation, growth inhibition, and apoptosis. Sphingosine, sphinganine, and phytosphingosine are structural analogs of sphingolipids and are classified as long-chain sphingoid bases. Sphingosine and sphinganine are known to play important roles in apoptosis. In the present study, we examined the phytosphingosineinduced apoptosis mechanism, focusing on mitochondria in human T-cell lymphoma Jurkat cells. Phytosphingosine significantly induced chromatin DNA fragmentation, which is a hallmark of apoptosis. Enzymatic activity measurements of caspases revealed that caspase-3 and caspase-9 are activated in phytosphingosineinduced apoptosis, but there is little activation of caspase-8 suggesting that phytosphingosine influences mitochondrial functions. In agreement with this hypothesis, a decrease in ∆ ∆ ∆ ∆Ψ Ψ Ψ Ψ m and the release of cytochrome c to the cytosol were observed upon phytosphingosine treatment. Furthermore, overexpression of mitochondria-localized anti-apoptotic protein Bcl-2 prevented phytosphingosine apoptotic stimuli. Western blot assays revealed that phytosphingosine decreases phosphorylated Akt and p70 O rganelle mitochondria play an important role in the induction of apoptosis machinery. Upon apoptosis, mitochondria undergo PT with the opening of an apoptosis-related pore called a mitochondrial PT pore complex, which is the basis for mitochondria-mediated apoptosis.(1) PT pore opening results in a reduction of ∆Ψ m and the release of AIF, Smac/ DIABLO, and cytochrome c to the cytosol.(2−6) Released AIF directly affects nuclei and triggers chromatin condensation.(4) Cytochrome c binds to Apaf-1 and then activates initiator caspase, caspase-9. Activated caspase-9 in turn activates the effector caspase, caspase-3, and activated caspase-3 cleaves a variety of substrates to execute apoptosis by means of chromatin DNA fragmentation, morphological changes, and a loss of cell volume. (7,8) Smac/ DIABLO promotes this cytochrome c-dependent caspase activation by binding to the inhibitor of apoptotic proteins, IAP.(5,6) The anti-apoptotic Bcl-2 family proteins, Bcl-2 and Bcl-x L , inhibit apoptosis by preventing opening of the PT pore.(1) Apoptotic signals are transmitted by many pathways to mitochondria. One such pathway induced by most anticancer drugs involves direct or indirect induction of PT by affecting mitochondria.(9,10) Another pathway involves inhibition of Bcl-2 and Bcl-x L anti-apoptotic effects by specific binding with the pro-apoptotic Bcl-2 family protein (e.g. Bax, Bid, and Bad) migrating from the cytosol. In p53-mediated apoptosis, cytosolic Bax is redistributed to the mitochondria to induce PT.(2) In Fas/ CD95-mediated apoptosis, caspase-8 is activated, followed by cleavage of Bid. Cleaved (activated) Bid translocates from the cytosol to the mitochondria and executes the postmitochondrial apoptotic pathway.(11) In the depletion of survival factormediated apoptosis, the PI 3-kinase pathway is attenuated. Ser/ Thr kinase Ak...

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“…DNA primase activity of pol α and the activities of T7 RNA polymerase, human DNA topoisomerases I and II, T4 polynucleotide kinase and bovine deoxyribonuclease I were measured using standard assays according to the manufacturer's specifications as described by Tamiya-Koizumi et al (28), Nakayama and Saneyoshi (29), Mizushina et al (30), Soltis and Uhlenbeck (31) and Lu and Sakaguchi (32), respectively.…”

Section: Methodsmentioning

confidence: 99%

The specific inhibitory effect of demethoxydehydroaltenusin, a derivative of dehydroaltenusin, on mammalian DNA polymerase α

Mizushina¹

1998

Int J Mol Med

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Abstract. In the screening of selective inhibitors of eukaryotic DNA polymerases (pols), dehydroaltenusin from the fungus Acremonium sp. was found to be an inhibitor of pol α. The present study succeeded in chemically synthesizing dehydroaltenusin, and the compound strongly inhibited calf pol α activity and weakly suppressed rat pol ß activity, with IC 50 values of 0.68 and 64 μM, respectively. We purified or synthesized various slightly modified derivatives of dehydroaltenusin, and using these, investigated the relationship between chemical structure and the inhibitory effects. These results suggest that the ketone group at the 5'-position in dehydroaltenusin is essential for pol inhibitory activity, and the group at the 5-position is important for the specificity of pol α inhibition. Demethoxydehydroaltenusin was found to be the most specific pol α inhibitor among the prepared derivatives, and the IC 50 values for pols α and ß were 0.24 and 89 μM, respectively. This compound did not influence the activities of other replicative pols such as pols δ and ε, and also demonstrated no effect on pol α activity from another vertebrate, fish and a plant species. Demethoxydehydroaltenusin also had no influence on the other pols and DNA metabolic enzymes tested. Therefore, demethoxydehydroaltenusin is of interest as a mammalian pol α-selective inhibitor as a 'chemical knockout agent' in vitro and in vivo. IntroductionThe human genome encodes 16 DNA polymerases (pols) that control cellular DNA synthesis (1). Eukaryotic cells reportedly contain three replicative types: pols α, δ and ε, mitochondrial pol γ, and at least twelve repair types: pols ß, δ, ε, ζ, η, θ, ι, κ, λ, μ, and σ and REV1 (2). Selective inhibitors of each pol are useful tools and molecular probes for distinguishing pols and for clarifying their biological and in vivo functions (3). For example, aphidicolin is a selective inhibitor of both pol α and eukaryotic DNA replicative pols δ and ε, indicating that these pols are essential for DNA replication (4), and this inhibitor has been very useful for studying the DNA replication system (5); however, aphidicolin is not capable of distinguishing pols α, δ and ε.Therefore, we established an assay method to detect pol inhibitors, and have screened for natural sources of inhibitors for more than 10 years. An inhibitor was isolated that selectively influences the activity of mammalian pol α, dehydroaltenusin, from a fungus (Acremonium sp.) collected from fields in the vicinity of Noda city in Chiba prefecture, Japan (6). A total chemical synthesis method was established for dehydroaltenusin and succeeded in completely synthesizing the compound (7-9).Subsequently, the slightly modified derivatives were purified or chemically synthesized to examine the structural relationship between dehydroaltenusin and pols. Dehydroaltenusin and its analogues represent a group of potentially useful agents to examine the precise role of each pol in vivo, and to develop a drug design strategy for cancer chemotherapy agents. The compou...

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Inhibition of DNA primase by sphingosine and its analogues parallels with their growth suppression of cultured human leukemic cells

Cited by 38 publications

References 7 publications

Candida albicans Phospholipomannan Promotes Survival of Phagocytosed Yeasts through Modulation of Bad Phosphorylation and Macrophage Apoptosis

Candida albicans Phospholipomannan Promotes Survival of Phagocytosed Yeasts through Modulation of Bad Phosphorylation and Macrophage Apoptosis

Phytosphingosine induced mitochondria‐involved apoptosis

The specific inhibitory effect of demethoxydehydroaltenusin, a derivative of dehydroaltenusin, on mammalian DNA polymerase α

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