Identification of ISC1 (YER019w) as Inositol Phosphosphingolipid Phospholipase C inSaccharomyces cerevisiae

Sawai, Hirofumi; Okamoto, Yasuo; Luberto, Chiara; Mao, Cungui; Bielawska, Alicja; Domae, Naochika; Hannun, Yusuf A.

doi:10.1074/jbc.m007721200

Cited by 152 publications

(173 citation statements)

References 31 publications

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“…In agreement, Isc1p protects the fungus Cryptococcus neoformans from the oxidative stress environment of macrophages (Shea et al, 2006). Interestingly, isc1⌬ cells accumulate IPC and M(IP) 2 C (Sawai et al, 2000), and other yeast mutants showed an inverse correlation between oxidative stress resistance or chronological lifespan and M(IP) 2 C levels (Aerts et al, 2006). Our results support the hypothesis that M(IP) 2 C levels influence oxidative stress resistance and chronological lifespan in yeast.…”

Section: Discussionsupporting

confidence: 78%

“…These complex sphingolipids are hydrolyzed by Isc1p, an inositolphosphosphingolipid-phospholipase C. Isc1p also has neutral sphingomyelinase activity and has 30% identity to mammalian neutral sphingomyelinase (nSMase2). Isc1p and nSMase2 share other common features, as both require Mg 2ϩ for optimal activity, are activated selectively by anionic phospholipids, such as phosphatidylserine, cardiolipin, and phosphatidylglycerol, and contain a P-loop-like domain that seems to be essential for catalysis and Mg 2ϩ binding Sawai et al, 2000). During exponential growth, Isc1p localizes to the endoplasmic reticulum, but it is posttranslationally activated in the postdiauxic phase by translocation into mitochondria (Vaena de Avalos et al, 2004).…”

Section: Introductionmentioning

confidence: 99%

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Isc1p Plays a Key Role in Hydrogen Peroxide Resistance and Chronological Lifespan through Modulation of Iron Levels and Apoptosis

Almeida

Marques

Mojžita

et al. 2008

MBoC

109

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The inositolphosphosphingolipid phospholipase C (Isc1p) of Saccharomyces cerevisiae belongs to the family of neutral sphingomyelinases that generates the bioactive sphingolipid ceramide. In this work the role of Isc1p in oxidative stress resistance and chronological lifespan was investigated. Loss of Isc1p resulted in a higher sensitivity to hydrogen peroxide that was associated with an increase in oxidative stress markers, namely intracellular oxidation, protein carbonylation, and lipid peroxidation. Microarray analysis showed that Isc1p deficiency up-regulated the iron regulon leading to increased levels of iron, which is known to catalyze the production of the highly reactive hydroxyl radicals via the Fenton reaction. In agreement, iron chelation suppressed hydrogen peroxide sensitivity of isc1⌬ mutants. Cells lacking Isc1p also displayed a shortened chronological lifespan associated with oxidative stress markers and aging of parental cells was correlated with a decrease in Isc1p activity. The analysis of DNA fragmentation and caspase-like activity showed that Isc1p deficiency increased apoptotic cell death associated with oxidative stress and aging. Furthermore, deletion of Yca1p metacaspase suppressed the oxidative stress sensitivity and premature aging phenotypes of isc1⌬ mutants. These results indicate that Isc1p plays an important role in the regulation of cellular redox homeostasis, through modulation of iron levels, and of apoptosis.

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Section: Discussionsupporting

confidence: 78%

Section: Introductionmentioning

confidence: 99%

Isc1p Plays a Key Role in Hydrogen Peroxide Resistance and Chronological Lifespan through Modulation of Iron Levels and Apoptosis

Almeida

Marques

Mojžita

et al. 2008

MBoC

109

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“…(C) IPC-PLC activity of the C. neoformans WT, ⌬isc1, and ⌬isc1 REC strains. (38). Extracted lipids were base-hydrolyzed with monomethylamine reagent (10), dried down, dissolved in chloroformmethanol-water (2:2:0.6), and separated on a Whatman K6 60A silica preparative thin-layer chromatograph (500 m thick; Fisher Scientific) using a solvent mixture containing chloroform, methanol, and 4.2 N ammonium hydroxide (9: 7:2).…”

Section: Fig 2 Deletion and Reconstitution Of Isc1 In C Neoformansmentioning

confidence: 99%

“…Extracted lipids were base-hydrolyzed with monomethylamine reagent (10), dried down, dissolved in chloroformmethanol-water (2:2:0.6), and separated on a Whatman K6 60A silica preparative thin-layer chromatograph (500 m thick; Fisher Scientific) using a solvent mixture containing chloroform, methanol, and 4.2 N ammonium hydroxide (9: 7:2). An inositol phosphorylceramide (IPC) standard was prepared essentially as described by Sawai et al (38). A mutant strain of S. cerevisiae lacking mannose inositol phosphoryl ceremide (MIPC) synthase (Sur1) (2) was labeled with [ 3 H]inositol, and total lipids were extracted, subjected to base hydrolysis, and separated by thin-layer chromatography as previously described for C. neoformans.…”

Section: Fig 2 Deletion and Reconstitution Of Isc1 In C Neoformansmentioning

confidence: 99%

“…After centrifugation at 2,500 ϫ g for 10 min at 4°C, supernatant (ϳ100 l) was transferred to a sterile 1.5-ml microcentrifuge tube for quantification of proteins by the Bradford method (4). Phospholipase C activity against IPC was performed as previously described (38). Briefly, cell lysates containing 100 g protein were incubated at 30°C for 30 min in 100 l of buffer containing 50 mM Tris (pH 7.5), 5 mM MgCl 2 , 5 mM dithiothreitol, 0.1% Triton X-100, 10 nmol of phosphatidylserine (Avanti Polar Lipids), 2 nmol of unlabeled IPC, and 30,000 dpm of myo-[2-3 H]inositol-labeled IPC.…”

Section: Fig 2 Deletion and Reconstitution Of Isc1 In C Neoformansmentioning

confidence: 99%

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The Cryptococcal Enzyme Inositol Phosphosphingolipid-Phospholipase C Confers Resistance to the Antifungal Effects of Macrophages and Promotes Fungal Dissemination to the Central Nervous System

Shea¹,

Kechichian²,

Luberto³

et al. 2006

Infect Immun

Self Cite

104

108

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In recent years, sphingolipids have emerged as critical molecules in the regulation of microbial pathogenesis. In fungi, the synthesis of complex sphingolipids is important for the regulation of pathogenicity, but the role of sphingolipid degradation in fungal virulence is not known. Here, we isolated and characterized the inositol phosphosphingolipid-phospholipase C1 (ISC1) gene from the fungal pathogen Cryptococcus neoformans and showed that it encodes an enzyme that metabolizes fungal inositol sphingolipids. Isc1 protects C. neoformans from acidic, oxidative, and nitrosative stresses, which are encountered by the fungus in the phagolysosomes of activated macrophages, through a Pma1-dependent mechanism(s). In an immunocompetent mouse model, the C. neoformans ⌬isc1 mutant strain is almost exclusively found extracellularly and in a hyperencapsulated form, and its dissemination to the brain is remarkably reduced compared to that of control strains. Interestingly, the dissemination of the C. neoformans ⌬isc1 strain to the brain is promptly restored in these mice when alveolar macrophages are pharmacologically depleted or when infecting an immunodeficient mouse in which macrophages are not efficiently activated. These studies suggest that Isc1 plays a key role in protecting C. neoformans from the intracellular environment of macrophages, whose activation is important for preventing fungal dissemination of the ⌬isc1 strain to the central nervous system and the development of meningoencephalitis.

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Sphingomyelinases and Their Interaction with Membrane Lipids

Goñi

Alonso

2004

Lipases and Phospholipases in Drug Development

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This chapter is devoted to sphingomyelinases, enzymes that catalyze the hydrolysis of sphingomyelin (ceramide phosphorylcholine) into ceramide and phosphorylcholine. The reaction is formally similar to that of a phospholipase C. Sphingomyelinases have long been known [1, 2], but the last decade has seen renewed interest after the discovery of the sphingomyelin signal transduction pathway [3][4][5][6]. Ceramide appears to be a lipid second messenger in programmed cell death (apoptosis), cell differentiation and cell proliferation [reviews in 7-12; for the opposite point of view see 13], and sphingomyelinase is probably a major source of ceramide in the cells, although this is also a debated point. This contribution is based on a recent review [14] that we have modified according to several suggestions and criticisms received, and to which we have added what we consider as the most significant novel data to have appeared since.Two main aspects of sphingomyelinases are covered here, one corresponds to "classical enzymology", with a description of the known sphingomyelinases, and of their properties. The second is more directly related to our experimental work, and describes the interaction of sphingomyelinases with phospholipid bilayers, and the mutual influence of enzyme and substrate properties. One important function of sphingomyelinases may be related to changing membrane properties (charge, fluidity, permeability) by transforming sphingomyelin into ceramide. The present work does not cover the cell physiological effects of sphingomyelinases and/or ceramides, which are described in detail in the above-mentioned reviews.

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Identification of ISC1 (YER019w) as Inositol Phosphosphingolipid Phospholipase C inSaccharomyces cerevisiae

Cited by 152 publications

References 31 publications

Isc1p Plays a Key Role in Hydrogen Peroxide Resistance and Chronological Lifespan through Modulation of Iron Levels and Apoptosis

Isc1p Plays a Key Role in Hydrogen Peroxide Resistance and Chronological Lifespan through Modulation of Iron Levels and Apoptosis

The Cryptococcal Enzyme Inositol Phosphosphingolipid-Phospholipase C Confers Resistance to the Antifungal Effects of Macrophages and Promotes Fungal Dissemination to the Central Nervous System

Sphingomyelinases and Their Interaction with Membrane Lipids

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