Ceramide synthases in biomedical research.

G Model CPL 4398 No. of Pages 8

Chemistry and Physics of Lipids xxx (2015) xxx–xxx

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Ceramide synthases in biomedical research Francesca Cingolania , Anthony H. Futermanb , Josefina Casasa,* a Research Unit on BioActive Molecules (RUBAM), Department of Biomedicinal Chemistry, Institute for Advanced Chemistry of Catalonia (IQAC-CSIC), Jordi Girona 18, 08034 Barcelona, Spain b Department of Biological Chemistry, Weizmann Institute of Science, Rehovot 76100, Israel

A R T I C L E I N F O

A B S T R A C T

Article history: Received 15 June 2015 Received in revised form 30 July 2015 Accepted 31 July 2015 Available online xxx

Sphingolipid metabolism consists of multiple metabolic pathways that converge upon ceramide, one of the key molecules among sphingolipids (SLs). In mammals, ceramide synthesis occurs via N-acylation of sphingoid backbones, dihydrosphingosine (dhSo) or sphingosine (So). The reaction is catalyzed by ceramide synthases (CerS), a family of enzymes with six different isoforms, with each one showing specificity towards a restricted group of acyl-CoAs, thus producing ceramides (Cer) and dihydroceramides (dhCer) with different fatty acid chain lengths. A large body of evidence documents the role of both So and dhSo as bioactive molecules, as well as the involvement of dhCer and Cer in physiological and pathological processes. In particular, the fatty acid composition of Cer has different effects in cell biology and in the onset and progression of different diseases. Therefore, modulation of CerS activity represents an attractive target in biomedical research and in finding new treatment modalities. In this review, we discuss functional, structural and biochemical features of CerS and examine CerS inhibitors that are currently available. ã 2015 Elsevier Ireland Ltd. All rights reserved.

Keywords: Sphingolipid Metabolism Inhibitors Dihydroceramides

1. CerS in sphingolipid metabolism Ceramide synthases (CerS) are a group of six enzymes that catalyse the formation of dhCer or Cer through N-acylation of the sphingoid bases, dihydrosphingosine (dhSo) or sphingosine (So) (Levy and Futerman, 2010; Mullen et al., 2012). DhSo is produced through a two step reaction in the de novo synthetic pathway of SLs. First the condensation of L-serine with palmitoyl-CoA to give 3-ketodihydrosphingosine (3-kdhSo) in a reaction catalyzed by serine palmitoyl transferase (SPT), then, the ketone group of 3kdhSo is reduced to a hydroxyl group to afford dhSo, by the action of a reductase. After N-acylation of dhSo, the resulting dhCer is metabolized by dihydroceramide desaturase (Des1) to Cer (Hannun and Obeid, 2008). So originates from more complex SL catabolism in the recycling pathway (Mullen et al., 2012). Cer represents a central molecule in SL metabolism: it can be further metabolized to sphingomyelin (SM) (Holthuis and Luberto, 2010) or glucosylceramide (GlcCer) (Gault et al., 2010). In addition, Cer can be degraded by ceramidases (CDase) (Mao and Obeid, 2008) or

Abbreviations: Cer, ceramides; Cer, Sceramide synthases; 1-deoxydhSo, 1deoxydihydrosphingosine; dhCer, dihydroceramide; dhSo, dihydrosphingosine; dhSo1P, dihydrosphigosine-1-phosphate; ER, endoplasmic reticulum; FB1, Fumonisin B1; SLs, sphingolipids; So, sphingosine; S1P, sphingosine-1-phosphate. * Corresponding author. Fax: +34 932055904. E-mail address: fi[email protected] (J. Casas).

phosphorylated, giving ceramide-1-phosphate (C1P). So and dhSo are also substrates of sphingosine kinase (SK), which produces sphingosine-1-phosphate (S1P) and dihydrosphigosine-1-phosphate (dhSo1P) (Wattenberg et al., 2006). The reverse reaction is catalyzed by sphingolsine-1-phosphate phosphatase (S1PP). Finally, S1P can be irreversible degraded by S1P lyase (S1PL) with the formation of hexadecenal and phosphoetanolamine (Gault et al., 2010) (Fig. 1). 2. Identification and characterization of mammalian CerS Each of the CerS is the product of a unique gene located on different chromosomes (Pewzner-Jung et al., 2006). The first gene responsible for Cer synthesis was identified as LAG1 in Saccharomyces cerevisiae (Egilmez et al., 1989), which was described as a longevity assurance gene (LASS) because its deletion promoted longer chronological lifespan in yeast (D’mello et al., 1994). Several years later, LAG1 and its homologue LAC1, were found to be necessary for the synthesis of very-long chain Cer (C26) in yeast (Guillas et al., 2001). In 1991, a mammalian gene, upstream of growth and differentiation factor-1 (UOG-1), was discovered (Lee, 1991) and it was able to functionally complement the LAG1 and LAC1 double deletion in yeast (Jiang et al., 1998). However, it was not until 2002 that UOG-1 overexpression in mammalian cells was demonstrated to result in increased Cer synthesis, leading to the confirmation that this gene codes a mammalian CerS

http://dx.doi.org/10.1016/j.chemphyslip.2015.07.026 0009-3084/ ã 2015 Elsevier Ireland Ltd. All rights reserved.

Please cite this article in press as: F. Cingolani, et al., Ceramide synthases in biomedical research, Chem. Phys. Lipids (2015), http://dx.doi.org/ 10.1016/j.chemphyslip.2015.07.026


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Fig. 1. CerS in SL metabolism. DhCer, dihydroceramide; Cer, ceramide, DhSo, dihydrosphingosine; So, sphingosine; DhSo1P, dihydrosphingosine-1.phosphate; So1P, sphingosine-1-phosphate; GlcCer, glucosylceramide; SM, sphingomyelin; C1P, ceramide-1-phosphate. CerS, ceramide synthase; CDase, ceramidase; Des1, dihydroceramide desaturase; SMase, sphingomyelinase; SMS, sphingomyelin synthase; CRS, cerebrosidase; GCS, glucosylceramide synthase;.CK ceramide kinase; C1PP, ceramide-1-phosptate phosphatase; SK, sphingosine kinase; S1PP, sphingosine-1-phopshate phosphatase.

(Venkataraman et al., 2002). Moreover, the Cer produced by UOG1 only contained a C18 fatty acid, demonstrating that this enzyme, now known as CerS1, specifically uses stearic acid for Cer synthesis. Subsequent bioinformatic analyses (Jiang et al., 1998; Venkataraman and Futerman, 2002; Winter and Ponting, 2002) revealed additional mammalian Lag homologues, originally characterized as translocating chain-associating membrane protein homologs (TRH). Overexpression of THR1 and THR4 (now known as CerS4 and CerS5, respectively) found that these genes confers increased CerS activity and sphingolipid synthesis in mammalian cells (Riebeling et al., 2003). Particularly, Cer synthesized by TRH1 was shown to contain stearic (C18) and arachidic (C20) acids, whereas Cer synthesized by TRH4-overexpressing cells were preferentially enriched in palmitic acid (C16). Two more mammalian homologues, Lass3 (CerS3) and Lass6 (CerS6), were subsequently identified and cloned (Mizutani et al., 2006; Weinmann et al., 2005). CerS2 was cloned as Lass2 in 2001 (Pan et al., 2001) however, it was in 2008 that Laviad and co-workers reported that long chain acyl- CoAs (C20–C26) are preferred by CerS2 for Cer synthesis (Laviad et al., 2008). 3. Subcellular localization and tissue distribution CerS are located in the endoplasmic reticulum (ER) (Hirschberg et al., 1993), although a subset of CerS have been partially purified from a mitochondria-enriched fraction (Shimeno et al., 1998). CerS are integral membrane proteins (Kageyama-Yahara and Riezman, 2006), with their active site probably facing the cytosol (Hirschberg et al., 1993). Although the transmembrane topology of the mammalian CerS has not been resolved experimentally, comparison of several prediction programs to assess topology suggested that the CerS have six membrane-spanning domains. However, significant disagreement between the various prediction programs was noted for the fourth putative transmembrane domain, in

which the Lag1p motif is located, with some programs suggesting one membrane-spanning domain in this region and others two (Tidhar et al., 2012). However an odd-number of trans-membrane domains is supported by recent experimental data (Laviad et al., 2012). A number of studies on the tissue distribution of mammalian CerS have shown that each tissue has a different profile of CerS expression and that this profile changes during development. CerS1 is mainly expressed in brain and at low levels in skeletal muscle and testis (Laviad et al., 2008). It was also shown that it is up-regulated postanatally, which may reflect the synthesis of neuronal plasma membranes (Becker et al., 2008). CerS2 is much more widely expressed than CerS1, and two different studies showed that CerS2 is abundant in many tissues, mainly kidney and liver (Cai et al., 2003; Laviad et al., 2008). CerS3 is found mainly in skin and testis (Mizutani et al., 2006), and is highly expressed in keratinocytes, with its expression increasing during differentiation (Mizutani et al., 2008). Less information is available about CerS4, which appears to be found at high levels in skin, leukocytes, heart and liver, although its mRNA expression levels in this tissue is lower than those of other CerS, such as CerS2 (Laviad et al., 2008). CerS5 is the main CerS detected in lung epithelia (Xu et al., 2005). In brain, CerS5 mRNA is detected in most cells within the gray and white matter (Becker et al., 2008). CerS6 shows high homology to CerS5, however much less is known about this isoform. CerS6 is found in intestine and kidney (Laviad et al., 2008). Decreased expression of CerS6, together with decreased expression of CerS2, occurs during mouse brain development, especially in myelin-producing cells (Becker et al., 2008). However, CerS mRNA expression does not always correlate with the sphingolipid acyl chain composition in a particular tissue, suggesting a variety of post-translation mechanisms, and other possible mechanisms, that may regulate CerS activity, which would determine levels of Cer containing specific acyl chains (Laviad et al., 2008).




4. Structural and functional features The Tram-Lag-CLN8 (TLC) domain, a region of 200 residues found in different proteins (Pewzner-Jung et al., 2006), is found in all mammalian CerS. Within this region, the Lag1p motif is a conserved sequence of 52 amino acids (Jiang et al., 1998) involved in CerS activity, with some conserved residues probably implicated in catalysis or substrate binding (Winter and Ponting, 2002). Moreover, all mammalian CerS, except for CerS1, have a homeobox (Hox)-like domain (Venkataraman and Futerman, 2002), of which the last 12 residues are functionally important for CerS activity since its modification or removal leads to a loss of CerS activity (Mesika et al., 2007). As stated above, each CerS utilizes a restricted subset of fatty acyl-CoAs to synthesize Cer with defined acyl chain lengths (Fig. 2). Recently, Tidhar et al. showed, in a structure-activity study based on the use of chimeric CerS, that a region of 150 residues within the TLC domain is sufficient for maintaining CerS specificity (Tidhar et al., 2012). Conversely, CerS show less specificity towards the sphingoid chain base, since they are able to N-acylate a variety of natural long chain bases (such as dhSo, So, phytosphingosine) (Gault et al., 2010) as well as their analogues, such as Fumonisin B1 (FB1) (Harrer et al., 2013), NBD-sphinganine (Kim et al., 2012) and FTY720 (Lahiri et al., 2009). 5. Regulation of CerS activity Although the regulation of CerS is not completely understood, several studies suggest regulation at different levels (Mullen et al., 2012). For instance, CerS can undergo hetero- and homo-interactions by the formation of hetero- and homodimers that modulate CerS activity (Laviad et al., 2012). In particular, CerS5 activity was inhibited in a dominant negative-fashion by co-expression with a catalytically inactive CerS5, while CerS2 activity was enhanced by co-expression with a catalytically active form of CerS5 or CerS6. Moreover in a constitutive heterodimer comprising CerS5 and CerS2, the activity of CerS2 depended on the catalytic activity of CerS5. The formation of

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CerS dimers is in agreement with previous studies that demonstrated co-immunoprecipitation of some CerS in both mammalian cells (Mesicek et al., 2010) and yeast (Vallée and Riezman, 2005). Moreover, CerS2, 5 and 6 are N-glycosylated (Mizutani et al., 2005), while CerS1 is phosphorylated (Sridevi et al., 2009). The involvement of kinases in regulating CerS activity was demonstrated. For instance, CerS1 turnover is regulated by the opposing functions of p38 MAP kinase and protein kinase C (PKC), with the first increasing CerS1 ubiquitination, and the latter increasing CerS1 proteasomal turnover (Sridevi et al., 2009). Moreover PKC is intimately involved in CerS1 translocation from the ER to the Golgi apparatus under conditions of drug-induced stress (Sridevi et al., 2010). In addition, the C-Jun N-terminal kinase 3 signalling pathway is involved in ischemia–reperfusion induced Cer generation by activating CerS activity (Yu et al., 2007). In yeast, CerS homologues require another protein, Lip1p for their activity (Vallée and Riezman, 2005), although its role is not completely understood. CerS activity can also be modulated by lipids; for instance CerS2 activity is inhibited by sphingosine-1-phosphate (Laviad et al., 2008), while reconstituted CerS5 requires phospholipids for its activity (Lahiri and Futerman, 2005). 6. Biological functions and involvement in disease CerSs are involved in the physiological regulation of de novo sphingolipid synthesis, via N-acylation of dhSo, to generate dhCer. CerSs and can also N-acylate sphingosine, which originates from the breakdown of complex SLs, producing Cer (Mullen et al., 2012). Considering that Cer, dihydroCer and the sphingoid bases trigger a variety of signals in cells, the role of CerS in physiological and pathological processes may be related to the modulation of the amount and subcellular localization of these molecules and their downstream signalling. The involvement of Cer in a variety of cellular process that includes apoptosis, cell growth arrest, senescence and cell differentiation has been reported (Saddoughi et al., 2008). Cer may initiate apoptotic signaling by downregulating the activity of the serine/threonine protein kinase Akt,

Fig. 2. CerS specificity. Different CerS use a restricted subset of acyl-CoAs, producing ceramides with specific fatty acid chain lengths. Less specificity is shown toward the sphingoid base: ceramide synthesis originates from dihydrosphingosine produced in the de novo synthetic pathway of SLs. Alternatively sphingosine, originating from more complex SLs degradation, and phytosphingosine represent other natural substrates of CerS.



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or by modulating Cer activated protein phosphatases (CAPP) (Truman et al., 2014). Moreover, the pro-apoptotic protein, Bax, is regulated by Cer, leading to mitochondrial outer membrane permeabilization (MOMP), one of the characteristic events of apoptosis (Lee et al., 2011). Cer levels also decrease in various cancers (Riboni et al., 2002; Selzner et al., 2001) which is in line with its anti-survival function. However, in the past few years, sphingolipidomic analysis by mass spectrometry (Merrill et al., 2005) has permitted study of the role of Cer with specific acyl chain lengths in cancer, allowing correlation of the chain length composition with specific effects and cellular alterations. For instance, in malignant breast cancer, elevation of total Cer was associated with specific elevation of C16-, C24- and C24:1-Cer (Schiffmann et al., 2009). In head and neck squamous cell carcinoma (HNSCC), low levels of C18-Cer are observed, and elevation of C18-Cer levels by transfection with CerS1 led to cell growth inhibition (Koybasi et al., 2004). The involvement of specific Cer species has also been related in other pathologies, such as multiple sclerosis (Barthelmes et al., 2015 Ferreiros et al., 2012) and obesity (Kolak et al., 2007; Kotronen et al., 2009; Turpin et al., 2014). At the cellular level, many studies have reported the effect of different Cer in regulating the balance between cell death and survival. Thus,

C18-Cer produced by CerS1, and C16-Cer produced by CerS5 were shown to play pro-survival and anti-apoptotic roles, respectively, in HNSCC (Senkal et al., 2010). In HeLa cells, CerS2 overexpression offered partial protection for irradiation-induced apoptosis, while CerS5 overexpression increased apoptosis (Mesicek et al., 2010). Moreover upregulation of CerS2 increased cell proliferation, whereas upregulation of CerS4 and 6 caused cell death in both breast and colon cancers (Hartmanna et al., 2012). The role of dihydroSLs in cell biology was recently reviewed (Fabrias et al., 2012), documenting that these lipids, which were previously thought to be inactive in signalling pathways, are indeed bioactive. Many studies have reported the involvement of dhCer in cell proliferation (Devlin et al., 2011; Gagliostro et al., 2012) and cell death processes (Noack et al., 2014; Separovic et al., 2009); thus, long-acyl chain dhCer is responsible for cytotoxicity in a leukemia cell line (Holliday et al., 2013). Increased levels of dhCer have also been associated with autophagy induction in cancer cells (Signorelli et al., 2009). Increases in dhCer appears to activate autophagy with a protective role against cytotoxic agents (Gagliostro et al., 2012). In contrast, elevation in dhCer levels and autophagy activation after fenretinide (Wang et al., 2008) and g -tocotrienol (Jiang et al., 2012) treatment trigger to cell death.

Fig. 3. Structures of CerS inhibitors.




The modulation of levels of sphingoid bases as a response to CerS regulation is also involved in a number of biological effects. So is as a mediator of cell growth arrest or apoptosis in many cell types (Cuvillier, 2003; Cuvillier et al., 2001; Lépine et al., 2002), including after treatment with the CerS inhibitor, FB1 (Schmelz et al., 1998). In a sphingosine kinase knockout mouse, sphingosine displays anti-tumour properties (Kohno et al., 2006). Some of the sphingosine targets consist of protein kinases such as protein kinase C (PKC) (Hannun and Bell, 1989; Smith et al., 1997), the mitogen activated kinase (MAPK) ERK1/2(Jarvis et al., 1997) and protein kinase B (PKB/AKT) (Chang et al., 2001). Moreover, So alters the integrity of intracellular membranes: it increases the permeability of lysosomes leading to activation of the lysosomal pathway of apoptosis (Kågedal et al., 2001), as well as of mitochondria, resulting in the release of cytochrome c and activation of the intrinsic pathway of apoptosis (Cuvillier et al., 2001). Similarly, So mediates TNFa-induced lysosomal membrane permeabilization in hepatoma cells, leading to apoptotic-like cell death (Ullio et al., 2012). The sphingoid base also causes Golgi fragmentation, leading to cell-growth arrest, defects in cell adhesion and anoikis (Hu et al., 2005). Similarly to So, dhSo also mediates cell growth arrest and apoptosis (Ahn et al., 2006; Ahn and Schroeder, 2002) when either applied exogenously (Solomon et al., 2003) or after its endogenous accumulation upon CerS inhibition (Tolleson et al., 1999). Moreover, the cytotoxic effect of the anticancer agent, fenretinide, is related to dhSo accumulation in different cell lines (Mao et al., 2010; Wang et al., 2008). More recently, increased levels of both dhSo and dhCer have been related to induction of apoptosis and autophagy by g -tocotrienol in prostate cancer cells (Jiang et al., 2012). Although the direct involvement of CerS in pathological processes is not completely understood, some examples of LASS mutations suggest their implication in human diseases. A genetic association study of rhegmatogenous retinal detachment, an important cause of vision loss, demonstrated an association with a missense coding single-nucleotide polymorphism located within the CerS2 gene (Kirin et al., 2013). Since the blockade of Cer synthesis was already shown to have a protective effect in a retinitis pigmentosa mouse model (Strettoi et al., 2010) and in light-induced degeneration of retina (Chen et al., 2013), it is possible that very-long chain Cer, or their corresponding metabolites, are involved in retina disorders. Moreover, genetic mutations in the CerS3 gene are related to a disturbance in the process of keratinisation, known as ichthyoses, demonstrating the importance of very-long Cer in the formation and function of the human epidermis (Eckl et al., 2013; Radner et al., 2013). Additional information about CerS biology has come from the generation of CerS null mice. The characteristics of these animal models, the alteration in their SL composition and the associated phenotype have been reviewed (Park et al., 2014). As expected, Cer generated by specific CerS are reduced in each mouse, but often levels of other Cer are elevated, by as yet unknown mechanisms; these changes lead to significant phenotypic differences between the various CerS null mouse, indicating the important roles played by specific Cer species in cell physiology. Recently, a CerS4 deficient mouse was generated (Ebel et al., 2014), which displays decreased levels of C18- and C20-Cer, higher levels of very-long chain Cer and age dependent hair loss. CerS4 has also been shown to play a vital role in epidermal stem/progenitor cell homeostasis and hair follicle cycling regulation (Peters et al., 2015). 7. CerS inhibitors At present, there are no specific inhibitors for the different CerS isoforms (Fig. 3). FB1 is the most widely used and well characterized CerS inhibitor and belongs to a family of toxins of

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fungal origin (Fusarium verticilloides) that display structural similarity to the sphingoid base of SLs. Fumonisins are food contaminants in cereals and cause liver and kidney toxicity, neurotoxicity, immunological disorders, and various cancers in both humans and other animals (Denli et al., 2015; Marasas, 2001; Thiel et al., 1992). The toxic effect of FB1 is directly related to its role as a CerS inhibitor, with the subsequent accumulation of sphingoid long chain bases (Merrill et al., 2001; Riley et al., 2001). In terms of its mode of inhibition, FB1 inhibit CerS via competitive-like inhibition towards both dihydrosphingosine and acyl-CoA (Merrill et al., 1993), with an IC50 value of 100 nM (Wang et al., 1991), causing accumulation of dihydrosphingosine and to a lesser extent, sphingosine. Cell cycle arrest (Ciacci-Zanella et al., 1998) and apoptosis (Ciacci-Zanella and Jones, 1999; Schmelz et al., 1998; Tolleson et al., 1999) are observed in a variety of cells lines after FB1 treatment which correlates with levels of accumulation of sphingoid bases. Due to the inhibition of CerS and the accumulation of sphingoid long chain bases, FB1 also causes elevation of levels of S1P (Smith and Merrill, 1995) and dyhydrosphingosine-1phosphate (Riley et al., 2001), and of fatty aldehyde and ethanolamine phosphate (Merrill et al., 2001), as well as the depletion of complex SLs (Merrill et al., 1993). Since FB1 may produce changes in the levels of different SLs, it is likely that its biological effects result from the interaction of different signals. The elevation of 1-deoxydihydrosphingosine (1-deoxydhSo), which is formed via the utilization of alanine instead of serine in the first step of the de novo synthesis of SLs and is found in very low amounts in different tissues, has been reported after FB1 treatment (Zitomer et al., 2009). The metabolite showed a cytotoxicity that is similar to the other sphingoid bases which are elevated by FB1, suggesting that the 1-deoxy derivatives might be involved in toxicity. Moreover, 1-deoxydhSo was shown to be acylated in intact cells and 1-deoxydihydroCer has been found in different tissues. In this context, we have recently reported the synthesis of 1-deoxydhSo and 1-deoxy-So stereoisomers and shown that these molecules might be useful to study the role of the different CerS and N-acyl(dihydro) Cer in cell physiology (Abad et al., 2013) (Fig. 3). From a structural point of view, FB1 is characterized by a linear amino pentahydroxyeicosane chain in which two of the hydroxyl groups are each ester bound to a tricarballylic acid molecule (Delgado et al., 2006). Several studies suggest that inhibition occurs because CerS recognizes the aminopentol moiety, which competes for binding to the sphingoid base, as well as the dicarboxylic acid side chains, which interfere with acyl CoA binding (Humpf et al., 1998; Merrill et al., 1993). Considering the opposite configuration between the C3-hydroxy group of natural SLs (3R) and the corresponding hydroxyl group in FB1 (3S), this model indicates the low stereo-selectivity of CerS toward the terminal amino alcohol end of FB1 (Delgado et al., 2013). The involvement of the tricarballylic acids in the inhibitory mechanism is confirmed by the decrease in CerS inhibition when the tricarballylic acidsgroups are removed. Moreover, the resulting aminopentol (AP1) becomes a CerS substrate, supporting the idea that tricarballylic acids affect acyl CoA binding. Interestingly, Nacylated-AP1 (PAP1) was shown to be more cytotoxic than FB1 or AP1 in human cancer cells (Humpf et al., 1998). Recently it has been shown that FB1 can also be N-acylated, with the formation of cytotoxic N-acyl-fumonisin B1 (Harrer et al., 2013, 2015). Other CerS inhibitors include alternaria aleternate toxin (AAT) and australifungin, which both originate from fungi. AAT, produced by Alternari alternate, produces plant diseases. It has been reported that AAT caused necrosis in 25 species of Solanaceae of the 200 species tested. The inhibition of CerS appears to be the basis of toxicity, but not the basis of host selectivity (Mesbah et al., 2000). The molecule is structural related to fumonisins and causes the accumulation of sphingoid bases (Abbas et al., 1994).



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Australiafungin is an antifungal compound from the fungus Sporormiella australis (Mandala et al., 1995) which has little structural similarity to SLs and is a potent inhibitor of CerS (50% inhibition at 0.04 mg/ml); nevertheless the presence of both the alpha-diketone and beta-ketoaldehyde functional groups limit its use due to their high chemical reactivity (Delgado et al., 2006). Another sphingoid base-like compound is FTY720, known also as Fingolimod. FTY720 is an immunosuppressant that is currently used in the treatment of multiple sclerosis (Pelletier and Hafler, 2012); its action is based on its phosphorylation by sphingosine kinase, generating phosphorylated FTY720 that acts as an agonist of sphingosine 1-phosphate receptors (Gräler and Goetzl, 2004). Study of other effects of FTY720 on sphingolipid metabolism revealed that it can inhibit CerS activity via noncompetitive inhibition towards acyl CoAs and uncompetitive inhibition towards sphinganine (Lahiri et al., 2009). CerS inhibition by FTY720 was also reported by Berdyshevet al (Berdyshev et al., 2009). A number of attempts have been made to modify the structure of FTY720 in order to specifically inhibit CerS isoforms (Schiffmann et al., 2012a,b). These (oxy) derivatives with amine variations in the FTY720 were shown to decrease levels of a restricted subset of (dihydro) Cer, indicating a preferential inhibition of CerS that use the corresponding acyl-CoAs. 8. Concluding remarks In this review we have discussed functional, structural and biochemical features of CerS. In particular, the fatty acid composition of Cer has different effects in cell biology and in the onset and progression of different diseases. We have also examined CerS inhibitors that are currently available. Further efforts are needed to selectively inhibit specific CerS in order to block the production of Cer with defined acyl chains length. Chemical modifications of known compounds, as well as screening new synthetic or natural products should be used in this regard. Moreover, CerS structure and the features of the active site are required for the specific design of new compounds. Finally, highthroughput screening (HTS) methods should be developed to test the inhibitory activity of large chemical libraries against CerS. Acknowledgments Partial financial support from the “Ministerio de Ciencia e Innovación”, Spain (Grants SAF2011-22444 and CTQ2014-54743-R) and Fundació Marató TV3 (Grant 112130 and 112132) are acknowledged. PhD fellowships from Agència de Gestio’ d’Ajuts Universitaris i de Recerca of Generalitat de Catalunya (FI-DRG2011 and FI-DRG2012) to FC are also acknowledged. Anthony H. Futerman is the Joseph Meyerhoff Professor of Biochemistry at the Weizmann Institute of Science. References Abad, J.L., Nieves, I., Rayo, P., Casas, J., Fabriàs, G., Delgado, A., 2013. Straightforward access to spisulosine and 4,5-dehydrospisulosine stereoisomers: probes for profiling ceramide synthase activities in intact cells. Org. Chem. 78 (12), 5858–5866. Abbas, H.K., Tanaka, T., Duke, S.O., Porter, J.K., Wray, E.M., Hodges, L., Sessions, A.E., Wang, E., Merrill Jr, A.H., Riley, R.T., 1994. Fumonisin- and AAL-toxin-induced disruption of sphingolipid metabolism with accumulation of free sphingoid bases. Plant Physiol. 106 (3), 1085–1093. Ahn, E.H., Schroeder, J.J., 2002. Sphingoid bases and ceramide induce apoptosis in HT-29 and HCT-116 human colon cancer cells. Exp. Biol. Med. (Maywood) 227 (5), 345–353. Ahn, E.H., Chang, C.-C., Schroeder, J.J., 2006. Evaluation of sphinganine and sphingosine as human breast cancer chemotherapeutic and chemopreventive agents. Exp. Biol. Med. (Maywood) 231 (10), 1664–1672. Barthelmes, J., de Bazo, A.M., Pewzner-Jung, Y., Schmitz, K., Mayer, C.A., Foerch, C., Eberle, M., Tafferner, N., Ferreirós, N., Henke, M., Geisslinger, G., Futerman, A.H., Grösch, S., Schiffmann, S., 2015. Lack of ceramide synthase 2 suppresses the

development of experimental autoimmune encephalomyelitis by impairing the migratory capacity of neutrophils. Brain Behav. Immun. doi:http://dx.doi.org/ 10.1016/j.bbi.2015.02.010. Becker, I., Wang-Eckhardt, L., Yaghootfam, A., Gieselmann, V., Eckhardt, M., 2008. Differential expression of (dihydro) ceramide synthases in mouse brain: oligodendrocyte-specific expression of CerS2/Lass2. Histochem. Cell Biol. 129 (2), 233–241. Berdyshev, E.V., Gorshkova, I., Skobeleva, A., Bittman, R., Lu, X., Dudek, S.M., Mirzapoiazova, T., Garcia, J.G., Natarajan, V., 2009. FTY720 inhibits ceramide synthases and up-regulates dihydrosphingosine 1-phosphate formation in human lung endothelial cells. J. Biol. Chem. 284 (9), 5467–5477. Cai, X.-F., Tao, Z., Yan, Z.-Q., Yang, S.-L., Gong, Y., 2003. Molecular cloning, characterisation and tissue-specific expression of human LAG3, a member of the novel Lag1 protein family. DNA Seq. J. DNA Seq. Mapp. 14 (2), 79–86. Chang, H.C., Tsai, L.H., Chuang, L.Y., Hung, W.C., 2001. Role of AKT kinase in sphingosine-induced apoptosis in human hepatoma cells. J. Cell. Physiol. 188 (2), 188–193. Chen, H., Tran, J.-T.A., Eckerd, A., Huynh, T.-P., Elliott, M.H., Brush, R.S., Mandal, N.A., 2013. Inhibition of de novo ceramide biosynthesis by FTY720 protects rat retina from light-induced degeneration. J. Lipid Res. 54 (6), 1616–1629. Ciacci-Zanella, J.R., Jones, C., 1999. Fumonisin B1, a mycotoxin contaminant of cereal grains, and inducer of apoptosis via the tumour necrosis factor pathway and caspase activation. Food Chem. Toxicol. 37 (7), 703–712. Ciacci-Zanella, J.R., Merrill, A.H., Wang, E., Jones, C., 1998. Characterization of cellcycle arrest by fumonisin B1 in CV-1 cells. Food Chem. Toxicol. 36 (9–10), 791–804. Cuvillier, O., 2003. Enzymes of sphingosine metabolism as potential pharmacological targets for therapeutic intervention in cancer. Pharmacol. Res. 47 (5), 439–445. Cuvillier, O., Nava, V.E., Murthy, S.K., Edsall, L.C., Levade, T., Milstien, S., Spiegel, S., 2001. Sphingosine generation, cytochrome c release, and activation of caspase7 in doxorubicin-induced apoptosis of MCF7 breast adenocarcinoma cells. Cell Death Differ. 8 (2), 162–171. D’mello, N.P., Childress, A.M., Franklin, D.S., Kale, S.P., Pinswasdi, C., Jazwinski, S.M., 1994. Cloning and characterization of LAG1, a longevity-assurance gene in yeast. J. Biol. Chem. 269 (22), 15451–15459. Delgado, A., Casas, J., Llebaria, A., Abad, J.L., Fabrias, G., 2006. Inhibitors of sphingolipid metabolism enzymes. Biochim. Biophys. Acta 1758 (12), 1957–1977. Delgado, A., Fabriàs, G., Casas, J., Abad, J.L., 2013. Natural products as platforms for the design of sphingolipid-related anticancer agents. Adv. Cancer Res. 117, 237–281. Denli, M., Blandon, J.C., Salado, S., Guynot, M.E., Casas, J., Pérez, J.F., 2015. Efficacy of AdiDetoxTM in reducing the toxicity of fumonisin B1 in rats. Food Chem. Toxicol. 78, 60–63. Devlin, C.M., Lahm, T., Hubbard, W.C., Van Demark, M., Wang, K.C., Wu, X., Bielawska, A., Obeid, L.M., Ivan, M., Petrache, I., 2011. Dihydroceramide-based response to hypoxia. J. Biol. Chem. 286 (44), 38069–38078. Ebel, P., Imgrund, S., Vom Dorp, K., Hofmann, K., Maier, H., Drake, H., Degen, J., Dörmann, P., Eckhardt, M., Franz, T., Willecke, K., 2014. Ceramide synthase 4 deficiency in mice causes lipid alterations in sebum and results in alopecia. Biochem. J. 461 (1), 147–158. Eckl, K.M., Tidhar, R., Thiele, H., Oji, V., Hausser, I., Brodesser, S., Preil, M.L., OnalAkan, A., Stock, F., Muller, D., Becker, K., Casper, R., Nurnberg, G., Altmuller, J., Nurnberg, P., Traupe, H., Futerman, A.H., Hennies, H.C., 2013. Impaired epidermal ceramide synthesis causes autosomal recessive congenital ichthyosis and reveals the importance of ceramide acyl chain length. J. Invest. Dermat. 133, 2202–2211. Egilmez, N.K., Chen, J.B., Jazwinski, S.M., 1989. Specific alterations in transcript prevalence during the yeast life span. J. Biol. Chem. 264 (24), 14312–14317. Fabrias, G., Muñoz-Olaya, J., Cingolani, F., Signorelli, P., Casas, J., Gagliostro, V., Ghidoni, R., 2012. Dihydroceramide desaturase and dihydrosphingolipids: debutant players in the sphingolipid arena. Prog. Lipid Res. 51 (2), 82–94. Gagliostro, V., Casas, J., Caretti, A., Abad, J.L., Tagliavacca, L., Ghidoni, R., Fabrias, G., Signorelli, P., 2012. Dihydroceramide delays cell cycle G1/S transition via activation of ER stress and induction of autophagy. Int. J. Biochem. Cell Biol. 44 (12), 2135–2143. Gault, C., Obeid, L., Hannun, Y.A., 2010. An overview of sphingolipid metabolism: from synthesis to breakdown. Adv. Exp. Med. Biol. 688, 1–23. Gräler, M.H., Goetzl, E.J., 2004. The immunosuppressant FTY720 down-regulates sphingosine 1-phosphate G-protein-coupled receptors. FASEB J. 18 (3), 551–553. Guillas, I., Kirchman, P.A., Chuard, R., Pfefferli, M., Jiang, J.C., Jazwinski, S.M., Conzelmann, A., 2001. C26-CoA-dependent ceramide synthesis of Saccharomyces cerevisiae is operated by Lag1p and Lac1p. EMBO J. 20 (11), 2655–2665. Hannun, Y.A., Obeid, L.M., 2008. Principles of bioactive lipid signalling: lessons from sphingolipids. Nat. Rev. Mol. Cell Biol. 9 (2), 139–150. Hannun, Y.A., Bell, R.M., 1989. Regulation of protein kinase C by sphingosine and lysosphingolipids. Clin. Chim. Acta 185 (3), 333–345. Harrer, H., Humpf, H.U., Voss, K.A., 2015. In vivo formation of N-acyl-fumonisin B1. Mycotoxin Res. 31 (1), 33–40. Harrer, H., Laviad, E.L., Humpf, H.U., Futerman, A.H., 2013. Identification of N-acylfumonisin B1 as new cytotoxic metabolites of fumonisin mycotoxins. Mol. Nutr. Food Res. 57 (3), 516–522. Hartmanna, D., Lucks, J., Fuchs, S., Schiffmann, S., Schreiber, Y., Ferreirós, N., Merkens, J., Marschalek, R., Geisslinger, G., Grösch, S., 2012. Long chain



F. Cingolani et al. / Chemistry and Physics of Lipids xxx (2015) xxx–xxx ceramides and very long chain ceramides have opposite effects on human breast and colon cancer cell growth. Int. J. Biochem. Cell Biol. 44 (4), 620–628. Hirschberg, K., Rodger, J., Futerman, A.H., 1993. The long-chain sphingoid base of sphingolipids is acylated at the cytosolic surface of the endoplasmic reticulum in rat liver. Biochem. J. 290 (Pt. 3), 751–757. Holliday, M.W., Cox, S.B., Kang, M.H., Maurer, B.J., 2013. C22:0- and C24:0dihydroceramides Confer Mixed Cytotoxicity in T-Cell Acute Lymphoblastic Leukemia Cell Lines. PloS One 8 (9), e74768. Holthuis, J.C.M., Luberto, C., 2010. Tales and mysteries of the enigmatic sphingomyelin synthase family. Adv. Exp. Med. Biol. 688, 72–85. Hu, W., Xu, R., Zhang, G., Jin, J., Szulc, Z.M., Bielawski, J., Hannun, Y.A., Obeid, L.M., Mao, C., 2005. Golgi fragmentation is associated with ceramide-induced cellular effects. Mol. Biol. Cell 16 (3), 1555–1567. Humpf, H.U., Schmelz, E.M., Meredith, F.I., Vesper, H., Vales, T.R., Wang, E., Merrill, A. H., 1998. Acylation of naturally occurring and synthetic 1-deoxysphinganines by ceramide synthase. Formation of N-palmitoyl-aminopentol produces a toxic metabolite of hydrolyzed fumonisin, AP1, and a new category of ceramide synthase inhibitor. J. Biol. Chem. 273 (30), 19060–19064. Jarvis, W.D., Fornari, F.A., Auer, K.L., Freemerman, A.J., Szabo, E., Birrer, M.J., Johnson, C.R., Barbour, S.E., Dent, P., Grant, S., 1997. Coordinate regulation of stress- and mitogen-activated protein kinases in the apoptotic actions of ceramide and sphingosine. Mol. Pharmacol. 52 (6), 935–947. Jiang, J.C., Kirchman, P.A., Zagulski, M., Hunt, J., Jazwinski, S.M., 1998. Homologs of the yeast longevity gene LAG1 in Caenorhabditis elegans and human. Genome Res. 8 (12), 1259–1272. Jiang, Q., Rao, X., Kim, C.Y., Freiser, H., Zhang, Q., Jiang, Z., Li, G., 2012. Gammatocotrienol induces apoptosis and autophagy in prostate cancer cells by increasing intracellular dihydrosphingosine and dihydroceramide. Int. J. Cancer 130 (3), 685–693. Kågedal, K., Zhao, M., Svensson, I., Brunk, U.T., 2001. Sphingosine-induced apoptosis is dependent on lysosomal proteases. Biochem. J. 359 (Pt. 2), 335–343. Kageyama-Yahara, N., Riezman, H., 2006. Transmembrane topology of ceramide synthase in yeast. Biochem. J. 398 (3), 585–593. Kim, H.J., Qiao, Q., Toop, H.D., Morris, J.C., Don, A.S., 2012. A fluorescent assay for ceramide synthase activity. J. Lipid Res. 53 (8), 1701–1707. Kirin, M., Chandra, A., Charteris, D.G., Hayward, C., Campbell, S., Celap, I., Mitry, D., 2013. Genome-wide association study identifies genetic risk underlying primary rhegmatogenous retinal detachment. Hum. Mol. Genet. 22 (15), 3174– 3185. Kohno, M., Momoi, M., Oo, M.L., Paik, J.-H., Lee, Y.-M., Venkataraman, K., Hla, T., 2006. Intracellular role for sphingosine kinase 1 in intestinal adenoma cell proliferation. Mol. Cell. Biol. 26 (19), 7211–7223. Kolak, M., Westerbacka, J., Velagapudi, V.R., Wågsäter, D., Yetukuri, L., Makkonen, J., Yki-Järvinen, H., 2007. Adipose tissue inflammation and increased ceramide content characterize subjects with high liver fat content independent of obesity. Diabetes 56 (8), 1960–1968. Kotronen, A., Seppänen-Laakso, T., Westerbacka, J., Kiviluoto, T., Arola, J., Ruskeepää, A.L., Yki-Järvinen, H., Oresic, M., 2009. Comparison of Lipid and Fatty Acid Composition of the Liver, Subcutaneous and Intra-abdominal Adipose Tissue, and Serum. Obesity 18 (5), 937–944. Koybasi, S., Senkal, C.E., Sundararaj, K., Spassieva, S., Bielawski, J., Osta, W., Ogretmen, B., 2004. Defects in cell growth regulation by C18:0-ceramide and longevity assurance gene 1 in human head and neck squamous cell carcinomas. J. Biol. Chem. 279 (43), 44311–44319. Lahiri, S., Futerman, A.H., 2005. LASS5 is a bona fide dihydroceramide synthase that selectively utilizes palmitoyl-CoA as acyl donor. J. Biol. Chem. 280 (40), 33735– 33738. Lahiri, S., Park, H., Laviad, E.L., Lu, X., Bittman, R., Futerman, A.H., 2009. Ceramide Synthesis Is Modulated by the Sphingosine Analog FTY720 via a Mixture of Uncompetitive an Noncompetitive Inhibition in a Acyl-CoA Chain Lenghtdependent Manner? J. Biol. Chem. 284 (24), 16090–16098. Laviad, E.L., Albee, L., Pankova-Kholmyansky, I., Epstein, S., Park, H., Merrill, A.H., Futerman, A.H., 2008. Characterization of ceramide synthase 2: tissue distribution, substrate specificity, and inhibition by sphingosine 1-phosphate. J. Biol. Chem. 283 (9), 5677–5684. Laviad, E.L., Kelly, S., Merrill, A.H., Futerman, A.H., 2012. Modulation of ceramide synthase activity via dimerization. J. Biol. Chem. 287 (25), 21025–21033. Lee, H., Rotolo, J.A., Mesicek, J., Penate-Medina, T., Rimner, A., Liao, W.-C., Kolesnick, R., 2011. Mitochondrial ceramide-rich macrodomains functionalize Bax upon irradiation. PloS One 6 (6), e19783. Lee, S.J., 1991. Expression of growth/differentiation factor 1 in the nervous system: conservation of a bicistronic structure. Proc. Natl. Acad. Sci. U.S.A. 88 (10), 4250– 4254. Lépine, S., Lakatos, B., Maziere, P., Courageot, M.-P., Sulpice, J.-C., Giraud, F., 2002. Involvement of sphingosine in dexamethasone-induced thymocyte apoptosis. Ann. N.Y. Acad. Sci. 973, 190–193. Levy, M., Futerman, A.H., 2010. Mammalian ceramide synthases. IUBMB Life 62 (5), 347–356. Mandala, S.M., Thornton, R.A., Frommer, B.R., Curotto, J.E., Rozdilsky, W., Kurtz, M.B., Giacobbe, R.A., Bills, G.F., Cabello, M.A., Martín, I., 1995. the discovery of australifungin, a novel inhibitor of sphinganine TV-acyltransferase from Sporormiella australis producing organism, fermentation, isolation, and biological activity. J. Antibiot. 48, 349–355. Mao, C., Obeid, L.M., 2008. Ceramidases: regulators of cellular responses mediated by ceramide, sphingosine, and sphingosine-1-phosphate. Biochim. Biophys. Acta 1781 (9), 424–434.

7

Mao, Z., Sun, W., Xu, R., Novgorodov, S., Szulc, Z.M., Bielawski, J., . . . Mao, C, 2010. Alkaline ceramidase 2 (ACER2) and its product dihydrosphingosine mediate the cytotoxicity of N-(4-hydroxyphenyl) retinamide in tumor cells. J. Biol. Chem. 285 (38), 29078–29090. Marasas, W.F., 2001. Discovery and occurrence of the fumonisins: a historical perspective. Environ. Health Perspect. 109, 239–243. Merrill, A.H., Sullards, M.C., Allegood, J.C., Kelly, S., Wang, E., 2005. Sphingolipidomics: high-throughput, structure-specific, and quantitative analysis of sphingolipids by liquid chromatography tandem mass spectrometry. Methods (San Diego, Calif.) 36 (2), 207–224. Merrill, A.H., Sullards, M.C., Wang, E., Voss, K.A., Riley, R.T., 2001. Sphingolipid metabolism: roles in signal transduction and disruption by fumonisins. Environ. Health Perspect. 109 (Suppl. (2)), 283–289. Merrill, A.H., van Echten, G., Wang, E., Sandhoff, K., 1993. Fumonisin B1 inhibits sphingosine (sphinganine) N-acyltransferase and de novo sphingolipid biosynthesis in cultured neurons in situ. J. Biol. Chem. 268 (36), 27299–27306. Mesbah, L.A., van der Weerden, G.M., Nijkamp, H.J.J., Hille, J., 2000. Sensitivity among species of Solanaceae to AAL toxins produced by Alternaria alternata f. sp. lycopersici. Plant Pathol. 49 (6), 734–741. Mesicek, J., Lee, H., Feldman, T., Jiang, X., Skobeleva, A., Berdyshev, E., Kolesnick, V., 2010. Ceramide synthases 2, 5, and 6 confer distinct roles in radiation-induced apoptosis in HeLa cells. Cell. Signal. (9), 1300–1307. Mesika, A., Ben-Dor, S., Laviad, E.L., Futerman, A.H., 2007. A new functional motif in Hox domain-containing ceramide synthases: identification of a novel region flanking the Hox and TLC domains essential for activity. J. Biol. Chem. 282 (37), 27366–27373. Mizutani, Y., Kihara, A., Chiba, H., Tojo, H., Igarashi, Y., 2008. 2-Hydroxy-ceramide synthesis by ceramide synthase family: enzymatic basis for the preference of FA chain length. J. Lipid Res. 49 (11), 2356–2364. Mizutani, Y., Kihara, A., Igarashi, Y., 2005. Mammalian Lass6 and its related family members regulate synthesis of specific ceramides. Biochem. J. 390 (Pt 1), 263– 271. Mizutani, Y., Kihara, A., Igarashi, Y., 2006. LASS3 (longevity assurance homologue 3) is a mainly testis-specific (dihydro) ceramide synthase with relatively broad substrate specificity. Biochem. J. 398 (3), 531–538. Mullen, T.D., Hannun, Y., a Obeid, L.M., 2012. Ceramide synthases at the centre of sphingolipid metabolism and biology. Biochem. J. 441 (3), 789–802. Noack, J., Choi, J., Richter, K., Kopp-Schneider, A., Régnier-Vigouroux, A., 2014. A sphingosine kinase inhibitor combined with temozolomide induces glioblastoma cell death through accumulation of dihydrosphingosine and dihydroceramide, endoplasmic reticulum stress and autophagy. Cell Death Dis. 5, e1425. Pan, H., Qin, W.X., Huo, K.K., Wan, D.F., Yu, Y., Xu, Z.G., Hu, Q.D., Gu, K.T., Zhou, X.M., Jiang, H.Q., Zhang, P.P., Huang, Y., Li, Y.Y., Gu, J.R., 2001. Cloning, mapping, and characterization of a human homologue of the yeast longevity assurance gene LAG1. Genomics 77 (1–2), 58–64. Park, J.-W., Park, W.-J., Futerman, A.H., 2014. Ceramide synthases as potential targets for therapeutic intervention in human diseases. Biochim. Biophys. Acta 1841 (5), 671–681. Pelletier, D., Hafler, D.A., 2012. Fingolimod for multiple sclerosis. New Engl. J. Med. 366 (4), 339–347. Peters, F., Vorhagen, S., Brodesser, S., Jakobshagen, K., Brüning, J.C., Niessen, C.M., Krönke, M., 2015. Ceramide Synthase 4 Regulates Stem Cell Homeostasis and Hair Follicle Cycling. J. Invest. Dermat. doi:http://dx.doi.org/10.1038/ jid.2015.60. Pewzner-Jung, Y., Ben-Dor, S., Futerman, A.H., 2006. When do Lasses (longevity assurance genes) become CerS (ceramide synthases) ?: Insights into the regulation of ceramide synthesis. J. Biol. Chem. 281 (35), 25001–25005. Radner, F.P., Marrakchi, S., Kirchmeier, P., Kim, G.J., Ribierre, F., Kamoun, B., Abid, L., Leipoldt, M., Turki, H., Schempp, W., Heilig, R., Lathrop, M., Fischer, J., 2013. Mutations in CERS3 cause autosomal recessive congenital ichthyosis in humans. PLoS Genet. 9 (6), e1003536. Riboni, L., Campanella, R., Bassi, R., Villani, R., Gaini, S.M., Martinelli-Boneschi, F., Viani, P., Tettamanti, G., 2002. Ceramide levels are inversely associated with malignant progression of human glial tumors. Glia 39 (2), 105–113. Riebeling, C., Allegood, J.C., Wang, E., Merrill, A.H., Futerman, A.H., 2003. Two mammalian longevity assurance gene (LAG1) family members, trh1 and trh4, regulate dihydroceramide synthesis using different fatty acyl-CoA donors. J. Biol. Chem. 278 (44), 43452–43459. Riley, R.T., Enongene, E., Voss, K.A., Norred, W.P., Meredith, F.I., Sharma, R.P., Spitsbergen, J., Williams, D.E., Carlson, D.B., Merrill Jr., A.H., 2001. Sphingolipid perturbations as mechanisms for fumonisin carcinogenesis. Environ. Health Perspect. 109 (Suppl. (2)), 301–308. Saddoughi, S.A., Song, P., Ogretmen, B., 2008. Roles of bioactive sphingolipids in cancer biology and therapeutics. SubCell.Biochem. 49, 413–440. Schiffmann, S., Ferreiros, N., Birod, K., Eberle, M., Schreiber, Y., Pfeilschifter, W., Geisslinger, G., 2012a. Ceramide synthase 6 plays a critical role in the development of experimental autoimmune encephalomyelitis. J. Immunol. (Baltimore, Md.: 1950) 188 (11), 5723–5733. Schiffmann, S., Hartmann, D., Fuchs, S., Birod, K., Ferreiròs, N., Schreiber, Y., Stark, H., 2012b. Inhibitors of specific ceramide synthases. Biochimie 94 (2), 558–565. Schiffmann, S., Sandner, J., Birod, K., Wobst, I., Angioni, C., Ruckhäberle, E., Kaufmann, M., Ackermann, H., Lötsch, J., Schmidt, H., Geisslinger, G., Grösch, S., 2009. Ceramide synthases and ceramide levels are increased in breast cancer tissue. Carcinogenesis .



8


Schmelz, E.M., Dombrink-Kurtzman, M.A., Roberts, P.C., Kozutsumi, Y., Kawasaki, T., Merrill, A.H., 1998. Induction of apoptosis by fumonisin B1 in HT29 cells is mediated by the accumulation of endogenous free sphingoid bases. Toxicol. Appl. Pharmacol. 148 (2), 252–260. Selzner, M., Bielawska, A., Morse, M.A., Rüdiger, H.A., Sindram, D., Hannun, Y.A., Clavien, P.A., 2001. Induction of apoptotic cell death and prevention of tumor growth by ceramide analogues in metastatic human colon cancer. Cancer Res. 61 (3), 1233–1240. Senkal, C.E., Ponnusamy, S., Bielawski, J., Hannun, Y.A., Ogretmen, B., 2010. Antiapoptotic roles of ceramide-synthase-6-generated C16-ceramide via selective regulation of the ATF6/CHOP arm of ER-stress-response pathways. FASEB J. 24 (1), 296–308. Separovic, D., Bielawski, J., Pierce, J.S., Merchant, S., Tarca, A.L., Ogretmen, B., Korbelik, M., 2009. Increased tumour dihydroceramide production after Photofrin-PDT alone and improved tumour response after the combination with the ceramide analogue LCL29. Evidence from mouse squamous cell carcinomas. Br. J. Cancer 100 (4), 626–632. Shimeno, H., Soeda, S., Sakamoto, M., Kouchi, T., Kowakame, T., Kihara, T., 1998. Partial purification and characterization of sphingosine N-acyltransferase (ceramide synthase) from bovine liver mitochondrion-rich fraction. Lipids 33 (6), 601–605. Signorelli, P., Munoz-Olaya, J.M., Gagliostro, V., Casas, J., Ghidoni, R., Fabriàs, G., 2009. Dihydroceramide intracellular increase in response to resveratrol treatment mediates autophagy in gastric cancer cells. Cancer Lett. 282 (2), 238–243. Smith, E.R., Jones, P.L., Boss, J.M., Merrill, A.H., 1997. Changing J774A. 1 cells to new medium perturbs multiple signaling pathways, including the modulation of protein kinase C by endogenous sphingoid bases. J. Biol. Chem. 272 (9), 5640–5646. Smith, E.R., Merrill, A.H., 1995. Differential roles of de novo sphingolipid biosynthesis and turnover in the burst of free sphingosine and sphinganine, and their 1-phosphates and N-acyl-derivatives, that occurs upon changing the medium of cells in culture. J. Biol. Chem. 270 (32), 18749–18758. Solomon, J.C., Sharma, K., Wei, L.X., Fujita, T., Shi, Y.F., 2003. A novel role for sphingolipid intermediates in activation-induced cell death in T cells. Cell Death Differ. 10 (2), 193–202. Sridevi, P., Alexander, H., Laviad, E.L., Min, J., Mesika, A., Hannink, M., Alexander, S., 2010. Stress-induced ER to Golgi translocation of ceramide synthase 1 is dependent on proteasomal processing. Exp.Cell Res. 316 (1), 78–91. Sridevi, P., Alexander, H., Laviad, E.L., Pewzner-Jung, Y., Hannink, M., Futerman, A.H., Alexander, S., 2009. Ceramide synthase 1 is regulated by proteasomal mediated turnover. Biochim. Biophys. Acta 1793 (7), 1218–1227. Strettoi, E., Gargini, C., Novelli, E., Sala, G., Piano, I., Gasco, P., Ghidoni, R., 2010. Inhibition of ceramide biosynthesis preserves photoreceptor structure and function in a mouse model of retinitis pigmentosa. Proc. Natl. Acad. Sci. U.S.A. 107 (43), 18706–18711. Thiel, P.G., Marasas, W.F., Sydenham, E.W., Shephard, G.S., Gelderblom, W.C., 1992. The implications of naturally occurring levels of fumonisins in corn for human and animal health. Mycopathologia 117 (1–2), 3–9. Tidhar, R., Ben-Dor, S., Wang, E., Kelly, S., Merrill, A.H., Futerman, A.H., 2012. Acyl chain specificity of ceramide synthases is determined within a region of 150 residues in the Tram-Lag-CLN8 (TLC) domain. J. Biol. Chem. 287 (5), 3197–3206. Tolleson, W.H., Couch, L.H., Melchior Jr, W.B., Jenkins, G.R., Muskhelishvili, M., Muskhelishvili, L., McGarrity, L.J., Domon, O., Morris, S.M., Howard, P.C., 1999.

Fumonisin B1 induces apoptosis in cultured human keratinocytes through sphinganine accumulation and ceramide depletion. Int. J. Oncol. 14 (5), 833–843. Truman, J.-P., García-Barros, M., Obeid, L.M., Hannun, Y.A., 2014. Evolving concepts in cancer therapy through targeting sphingolipid metabolism. Biochim. Biophys. Acta 1841, 1174–1188. Turpin, S.M., Nicholls, H.T., Willmes, D.M., Mourier, A., Brodesser, S., Wunderlich, C. M., Mauer, J., Xu, E., Hammerschmidt, P., Brönneke, H.S., Trifunovic, A., LoSasso, G., Wunderlich, F.T., Kornfeld, J.W., Blüher, M., Krönke, M., Brüning, J.C., 2014. Obesity-induced CerS6-dependent C16:0 ceramide production promotes weight gain and glucose intolerance. Cell Metab. 20 (4), 678–686. Ullio, C., Casas, J., Brunk, U.T., Sala, G., Fabriàs, G., Ghidoni, R., Bonelli, G., Baccino, F. M., Autelli, R., 2012. Sphingosine mediates TNFà-induced lysosomal membrane permeabilization and ensuing programmed cell death in hepatoma cells. J. Lipid Res. 53 (6), 1134–1143. Vallée, B., Riezman, H., 2005. Lip1p: a novel subunit of acyl-CoA ceramide synthase. EMBO J. 24 (4), 730–741. Venkataraman, K., Futerman, A.H., 2002. Do longevity assurance genes containing Hox domains regulate cell development via ceramide synthesis? FEBS Lett. 528 (1–3), 3–4. Venkataraman, K., Riebeling, C., Bodennec, J., Riezman, H., Allegood, J.C., Sullards, M. C., Merrill Jr, A.H., Futerman, A.H., 2002. Upstream of growth and differentiation factor 1 (uog1), a mammalian homolog of the yeast longevity assurance gene 1 (LAG1), regulates N-stearoyl-sphinganine (C18-(dihydro) ceramide) synthesis in a fumonisin B1-independent manner in mammalian cells. J. Biol. Chem. 277 (38), 35642–35649. Wang, E., Norred, W.P., Bacon, C.W., Riley, R.T., Merrill, A.H., 1991. Inhibition of sphingolipid biosynthesis by fumonisins. Implications for diseases associated with Fusarium moniliforme. J. Biol. Chem. 266 (22), 14486–14490. Wang, H., Maurer, B.J., Liu, Y.Y., Wang, E., Allegood, J.C., Kelly, S., Symolon, H., Liu, Y., Merrill Jr, A.H., Gouazé-Andersson, V., Yu, J.Y., Giuliano, A.E., Cabot, M.C., 2008. N-(4-Hydroxyphenyl) retinamide increases dihydroceramide and synergizes with dimethylsphingosine to enhance cancer cell killing. Mol. Cancer Ther. 7 (9), 2967–2976. Wattenberg, B.W., Pitson, S.M., Raben, D.M., 2006. The sphingosine and diacylglycerol kinase superfamily of signaling kinases: localization as a key to signaling function. J. Lipid Res. 47 (6), 1128–1139. Weinmann, A., Galle, P.R., Teufel, A., 2005. LASS6, an additional member of the longevity assurance gene family. Int. J. Mol. Med. 16 (5), 905–910. Winter, E., Ponting, C.P., 2002. TRAM, LAG1 and CLN8: members of a novel family of lipid-sensing domains? Trends Biochem. Sci. 27 (8), 381–383. Xu, Z., Zhou, J., McCoy, D.M., Mallampalli, R.K., 2005. LASS5 is the predominant ceramide synthase isoform involved in de novo sphingolipid synthesis in lung epithelia. J. Lipid Res. 46 (6), 1229–1238. Yu, J., Novgorodov, S.A., Chudakova, D., Zhu, H., Bielawska, A., Bielawski, J., Obeid, L. M., Kindy, M.S., Gudz, T.I., 2007. JNK3 signaling pathway activates ceramide synthase leading to mitochondrial dysfunction. J. Biol. Chem. 282 (35), 25940–25949. Zitomer, N.C., Mitchell, T., Voss, K.A., Bondy, G.S., Pruett, S.T., Garnier-Amblard, E.C., Liebeskind, L.S., Park, H., Wang, E., Sullards, M.C., Merrill Jr, A.H., Riley, R.T., 2009. Ceramide synthase inhibition by fumonisin B1 causes accumulation of 1deoxysphinganine: a novel category of bioactive 1-deoxysphingoid bases and 1deoxydihydroceramides biosynthesized by mammalian cell lines and animals. J. Biol. Chem. 284 (8), 4786–4795.


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