2-Hydroxy-ceramide synthesis by ceramide synthase family: enzymatic basis for the preference of FA chain length

Mizutani, Yukiko; Kihara, Akio; Chiba, Hiroko; Tojo, Hiromasa; Igarashi, Yasuyuki

doi:10.1194/jlr.m800158-jlr200

Cited by 95 publications

(66 citation statements)

References 36 publications

(75 reference statements)

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“…The control siRNA and siRNAs for CERS2, CERS4, and CERS5 were purchased from Qiagen and have been described previously (21). The nucleotide sequences of ELOVL1 siRNA were 5′-CCUGUACUACGGAUUAU-CUGC-3′ (sense) and 5′-AGAUAAUCCGUAGUACAGGUA-3′ (antisense), and the corresponding duplex siRNA was purchased from Sigma.…”

Section: Methodsmentioning

confidence: 99%

ELOVL1 production of C24 acyl-CoAs is linked to C24 sphingolipid synthesis

Ohno

Suto

Yamanaka

et al. 2010

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

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Very long-chain fatty acids (VLCFAs) exert a variety of cellular functions and are associated with numerous diseases. However, the precise pathway behind their elongation has remained elusive. Moreover, few regulatory mechanisms for VLCFAs synthesis have been identified. Elongases catalyze the first of four steps in the VLCFA elongation cycle; mammals have seven elongases (ELO-VL1-7). In the present study, we determined the precise substrate specificities of all the ELOVLs by in vitro analyses. Particularly notable was the high activity exhibited by ELOVL1 toward saturated and monounsaturated C20-and C22-CoAs, and that it was essential for the production of C24 sphingolipids, which are unique in their capacity to interdigitate within the membrane as a result of their long chain length. We further established that ELOVL1 activity is regulated with the ceramide synthase CERS2, an enzyme essential for C24 sphingolipid synthesis. This regulation may ensure that the production of C24-CoA by elongation is coordinated with its utilization. Finally, knockdown of ELOVL1 caused a reduction in the activity of the Src kinase LYN, confirming that C24-sphingolipids are particularly important in membrane microdomain function.acyl-CoA | lipid metabolism | monounsaturated fatty acid | polyunsaturated fatty acid | saturated fatty acid

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Section: Methodsmentioning

confidence: 99%

ELOVL1 production of C24 acyl-CoAs is linked to C24 sphingolipid synthesis

Ohno

Suto

Yamanaka

et al. 2010

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

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305

354

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“…No enzyme that produces sphingolipid bases with two double bonds has yet been identified in any organism; however, the Drosophila genome contains a single homolog of fatty acid 2-hydroxylase (FA2H). This enzyme generates the a-hydroxy fatty acids present in some vertebrate sphingolipids (Maldonado et al, 2008;Mizutani et al, 2008;Uchida et al, 2007). To determine whether it has a similar activity in Drosophila, we altered its levels and measured the resulting changes in sphingolipid fatty acid hydroxylation.…”

Section: Sterol Depletion Alters Abundance Of Specific Sphingolipid Vmentioning

confidence: 99%

Survival strategies of a sterol auxotroph

et al. 2010

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SUMMARYThe high sterol concentration in eukaryotic cell membranes is thought to influence membrane properties such as permeability, fluidity and microdomain formation. Drosophila cannot synthesize sterols, but do require them for development. Does this simply reflect a requirement for sterols in steroid hormone biosynthesis, or is bulk membrane sterol also essential in Drosophila? If the latter is true, how do they survive fluctuations in sterol availability and maintain membrane homeostasis? Here, we show that Drosophila require both bulk membrane sterol and steroid hormones in order to complete adult development. When sterol availability is restricted, Drosophila larvae modulate their growth to maintain membrane sterol levels within tight limits. When dietary sterol drops below a minimal threshold, larvae arrest growth and development in a reversible manner. Strikingly, membrane sterol levels in arrested larvae are dramatically reduced (dropping sixfold on average) in most tissues except the nervous system. Thus, sterols are dispensable for maintaining the basic membrane biophysical properties required for cell viability; these functions can be performed by non-sterol lipids when sterols are unavailable. However, bulk membrane sterol is likely to have essential functions in specific tissues during development. In tissues in which sterol levels drop, the overall level of sphingolipids increases and the proportion of different sphingolipid variants is altered. These changes allow survival, but not growth, when membrane sterol levels are low. This relationship between sterols and sphingolipids could be an ancient and conserved principle of membrane homeostasis.

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“…Northern blot analyses by two groups showed that FA2H is expressed in many organs (20,21). In a recent study, Mizushima et al (38) reported that all six isoforms of ceramide synthase (LASS/CerS) can synthesize hFA-ceramide. In our unpublished studies, we have yet to encounter any biological samples (tissues, cells, or serum) with no FA2H or hFA, although their abundance could be diminutively low in some specimens.…”

Section: Discussionmentioning

confidence: 99%

“…In addition to C 16 fatty acid, many other fatty acids (C 14 -C 34 ) can be used. The N-acylation step is catalyzed by any of the six isoforms of ceramide synthase (38). GSL, glycosphingolipid; SM, sphingomyelin.…”

Section: Thymidine Incorporation Assaymentioning

confidence: 99%

Fatty acid 2-hydroxylase regulates cAMP-induced cell cycle exit in D6P2T Schwannoma cells

Alderson

Hama

2009

Journal of Lipid Research

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Sphingolipids are ubiquitous components of eukaryotic cells that regulate various cellular functions. In many cell types, a fraction of sphingolipids contain 2-hydroxy fatty acids, produced by fatty acid 2-hydroxylase (FA2H), as the N-acyl chain of ceramide [hydroxyl fatty acid (hFA)-sphingolipids]. FA2H is highly expressed in myelin-forming cells of the nervous system and in epidermal keratinocytes. While hFA-sphingolipids are thought to enhance the physical stability of specialized membranes produced by these cells, physiological significance of hFA-sphingolipids in many other cell types is unknown. In this study, we report novel roles for FA2H and hFA-sphingolipids in the regulation of the cell cycle. Treatment of D6P2T Schwannoma cells with dibutyrylcAMP (db-cAMP) induced exit from the cell cycle with concomitant upregulation of FA2H. Partial silencing of FA2H in D6P2T cells resulted in 60-70% reduction of hFA-dihydroceramide and hFA-ceramide, with no effect on nonhydroxy dihydroceramide and ceramide. Under these conditions, db-cAMP no longer induced cell cycle exit, and cells continued to grow and divide. Immunoblot analyses revealed that FA2H silencing prevented db-cAMP-induced upregulation of cyclin-dependent kinase inhibitors p21 and p27. These results provide evidence that FA2H is a negative regulator of the cell cycle and facilitates db-cAMP-induced cell cycle exit in D6P2T cells. Sphingolipids are a diverse group of lipids found in all eukaryotic cells. They are major structural components of cell membranes and involved in various cellular functions, such as cell adhesion, signaling, and membrane trafficking (1-3). The structural diversity of sphingolipids arises from .300 distinct carbohydrate head groups as well as modifications on the sphingoid base and the N-acyl chains of ceramide. The sphingoid base in mammalian sphingolipids is predominantly C 18 sphingosine, whereas the N-acyl chains are highly diverse with varying chain length (C 12 -C 34 ), desaturation, and hydroxylation. In mammals, sphingolipids containing 2-hydroxy fatty acids (hFA-sphingolipids) are present at high concentrations in the nervous system, comprising the major myelin lipids galactosylceramide and sulfatide (4). A number of nonneural tissues also contain various hFA-sphingolipids. Examples include hFA-ceramide in the epidermis (5); hFA-sphingomyelin in kidney, intestine, spermatozoa (6-8); and various hFA-glycosphingolipids in liver and intestine (9-12). In addition, aberrant hFAglycosphingolipids are present in various human tumors, including ovarian tumors (13), neuroblastomas (14), small cell lung carcinomas (15), and colon and liver adenocarcinomas (16,17). In some studies, a correlation was reported to exist between hFA-sphingolipid levels and the invasive or drug-resistant nature of tumor cells (18,19). Despite the welldocumented prevalence of hFA-sphingolipids, their specific cellular functions are unknown.The fatty acid 2-hydroxylase FA2H catalyzes the formation of precursors for hFA-sphingolipids, 2-hydroxy...

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2-Hydroxy-ceramide synthesis by ceramide synthase family: enzymatic basis for the preference of FA chain length

Cited by 95 publications

References 36 publications

ELOVL1 production of C24 acyl-CoAs is linked to C24 sphingolipid synthesis

ELOVL1 production of C24 acyl-CoAs is linked to C24 sphingolipid synthesis

Survival strategies of a sterol auxotroph

Fatty acid 2-hydroxylase regulates cAMP-induced cell cycle exit in D6P2T Schwannoma cells

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