Sphingomyelin-degrading pathways in human cells

Levade, Thierry; Andrieu‐Abadie, Nathalie; Ségui, Bruno; Augé, Nathalie; Chatelut, Martine; Jaffrézou, Jean‐Pierre; Salvayre, Robert

doi:10.1016/s0009-3084(99)00085-7

Cited by 34 publications

(23 citation statements)

References 86 publications

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“…SM is hydrolyzed by lysosomal acid sphingomyelinase (SMase) and in principle, degradation can be used to monitor the delivery of SMs to the hydrolytic compartments. However, the interpretation is complicated by the potential acyl chain selectivity of acid SMase and contribution of neutral SMases (Levade et al, 1999). To address the first issue, we determined the rate of hydrolysis of short-and long-chain PyrSMs by acid SMase in vitro.…”

Section: Lysosomal Degradation Of Pyrsmsmentioning

confidence: 99%

Endocytic Trafficking of Sphingomyelin Depends on Its Acyl Chain Length

Koivusalo

Jansen

Somerharju

et al. 2007

MBoC

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To study the principles of endocytic lipid trafficking, we introduced pyrene sphingomyelins (PyrSMs) with varying acyl chain lengths and domain partitioning properties into human fibroblasts or HeLa cells. We found that a long-chain, ordered-domain preferring PyrSM was targeted Hrs and Tsg101 dependently to late endosomal compartments and recycled to the plasma membrane in an NPC1-and cholesterol-dependent manner. A short-chain, disordered domain preferring PyrSM recycled more effectively, by using Hrs-, Tsg101-and NPC1-independent routing that was insensitive to cholesterol loading. Similar chain length-dependent recycling was observed for unlabeled sphingomyelins (SMs). The findings 1) establish acyl chain length as an important determinant in the endocytic trafficking of SMs, 2) implicate ESCRT complex proteins and NPC1 in the endocytic recycling of ordered domain lipids to the plasma membrane, and 3) introduce long-chain PyrSM as the first fluorescent lipid tracing this pathway. INTRODUCTIONSphingomyelin (SM) is the most abundant sphingolipid and one of the major phospholipids in the mammalian cell plasma membrane (PM). The acyl chain profile of SM differs from that of most other phospholipids, being enriched in saturated and either relatively short or very long chains. For example, in human primary fibroblasts SMs with a 16:0 or 24:0 acyl chain constitute ϳ70% of the total . The physiological significance of such bipartite acyl chain length distribution is not clear. SM is enriched in the PM, and it has a relatively long half-life suggesting that upon endocytosis, it is efficiently recycled to the PM, with only a small fraction targeted to lysosomes for degradation (Koval and Pagano, 1990;van Meer and Holthuis, 2000).SM has high affinity for cholesterol in model membranes, and it has been proposed to partition into liquid-ordered domains, termed lipid rafts in cells (Simons and Ikonen, 1997;Brown and London, 1998;Simons and Vaz, 2004). Endocytic organelles have been suggested to sort lipids based on their domain association. By using dialkylindocarbocyanine (DiI) probes, Mukherjee and Maxfield found that probes with a propensity to partition into domains of different fluidity were differentially sorted in endosomes. DiI analogs with short or unsaturated hydrocarbon chains that preferred disordered domains were targeted to the endocytic recycling compartment, whereas those with long and saturated chains preferring more ordered domains entered late endosomes (Mukherjee et al., 1999;Hao et al., 2004). Whether differential endocytic sorting based on domain partitioning applies to naturally occurring lipids has not been investigated. Moreover, the endosomal proteins involved have not been identified and the effect of such differential sorting on lipid degradation has not been studied.There is limited information on the mechanisms of SM internalization from the PM and subsequent intracellular targeting. Most of the data are based on studies with fluorescently labeled amino]caproyl])-sphingosylphosphorylcholine (C...

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Section: Lysosomal Degradation Of Pyrsmsmentioning

confidence: 99%

Endocytic Trafficking of Sphingomyelin Depends on Its Acyl Chain Length

Koivusalo

Jansen

Somerharju

et al. 2007

MBoC

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“…Recent cloning of human (6) and mouse (7) ASMase genes has elucidated additional significant physiological and pathophysiological functions of ASMase. Genetic studies using ASMase knock-out mouse or lymphocytes from Niemann-Pick disease type A patients lacking functional ASMase have implicated ASMase in the signal transduction of apoptosis (5,8,9). Recently, Langmann et al (10) reported that lysosomal ASMase activity was induced during monocytic differentiation of monocytic leukemia cell line, THP-1, by 12-O-tetradecanoylphorbol-13-acetate (TPA) or 1␣,25-dihydroxyvitamin D 3 (Vit D 3 ), and that up-regulation of ASMase gene expression was mediated through SP1 and AP2 sites on the 5Ј-promoter region (10).…”

mentioning

confidence: 99%

Up-regulation of Acid Sphingomyelinase during Retinoic Acid-induced Myeloid Differentiation of NB4, a Human Acute Promyelocytic Leukemia Cell Line

Murate

Suzuki²,

Hattori³

et al. 2002

Journal of Biological Chemistry

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All-trans-retinoic acid (ATRA) induces myeloid differentiation of a human promyelocytic leukemia cell line, NB4, but does not affect its subclone NB4/RA harboring a point-mutated ligand-binding domain (AF2) in retinoic acid receptor ␣ (RAR␣) gene. We found that ATRA induced the 4-fold elevation of acid sphingomyelinase (ASMase) activity 24 h after treatment in NB4 cells, but not in NB4/RA cells. ATRA did not affect neutral sphingomyelinase activity in either NB4 or NB4/RA. Upon treatment with ATRA, ceramide, the product of an ASMase reaction, accumulated in NB4 cells. Northern blot analysis showed a marked elevation of the ASMase mRNA 8 h after ATRA treatment, reaching a plateau at 24 h. Regulation of ASMase gene expression was studied by a promoter analysis using luciferase reporter assay. The 5-upstream flanking region of human ASMase gene (؊519/؉300) conjugated with the luciferase gene was introduced into COS-7 cells. Luciferase activity in transformed cells markedly increased in response to ATRA stimulation when the wild type RAR␣ or the PML/RAR␣ hybrid protein was co-expressed. Deletion experiments revealed that a short sequence at the 5-end (؊519/؊485) was indispensable for the ATRA response. Within this short region, two retinoic acid-responsive element-like motifs (TGCCCG and TCTCCT) and one AP2-like motif (CCCTTCCC) were identified. Deletion and base-substitution experiments showed that all three motifs are required for the full expression induced by ATRA. Electrophoresis mobility shift assays with the nuclear extract of ATRA-treated NB4 cells showed that proteins were bound specifically to the probe being mediated by all three motifs in the promoter sequence.

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“…Fibroblasts used in all lipid efflux experiments were loaded with 20 mg/ml LDL and 20 mg/ml cholesterol to enhance intracellular SM and cholesterol storage (16). Lipid efflux was determined as the percentage of 3 H radioactivity in the medium over the total 3 H radioactivity ( 3 H in medium 1 3 H in cells).…”

Section: Pl Effluxmentioning

confidence: 99%

“…Lipid efflux was determined as the percentage of 3 H radioactivity in the medium over the total 3 H radioactivity ( 3 H in medium 1 3 H in cells). In PL efflux experiments, cells were labeled with [ 3 H]choline as described previously (16). PL from the efflux medium and cells were extracted with chloroform-methanol (2:1, v/v) and hexaneisopropanol (3:2, v/v), respectively, and were fractionated by TLC developed in a chloroform-methanol-water (65:35:4, v/v/v) mixture.…”

Section: Pl Effluxmentioning

confidence: 99%

Increased sphingomyelin content impairs HDL biogenesis and maturation in human Niemann-Pick disease type B

Lee

Lesimple

Denis

et al. 2006

Journal of Lipid Research

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We previously reported that human Niemann-Pick Disease type B (NPD-B) is associated with low HDL. In this study, we investigated the pathophysiology of this HDL deficiency by examining both HDL samples from NPD-B patients and nascent high density lipoprotein (LpA-I) generated by incubation of lipid-free apolipoprotein A-I (apoA-I) with NPD-B fibroblasts. Interestingly, both LpA-I and HDL isolated from patient plasma had a significant increase in sphingomyelin (SM) mass (z50-100%). Analysis of LCAT kinetics parameters (V max and K m ) revealed that either LpA-I or plasma HDL from NPD-B, as well as reconstituted HDL enriched with SM, exhibited severely decreased LCAT-mediated cholesterol esterification. Importantly, we documented that SM enrichment of NPD-B LpA-I was not attributable to increased cellular mass transfer of SM or unesterified cholesterol to lipid-free apoA-I. Finally, we obtained evidence that the conditioned medium from HUVEC, THP-1, and normal fibroblasts, but not NPD-B fibroblasts, contained active secretory sphingomyelinase (S-SMase) that mediated the hydrolysis of [ 3 H]SM-labeled LpA-I and HDL 3 . Furthermore, expression of mutant SMase (DR608) in CHO cells revealed that DR608 was synthesized normally but had defective secretion and activity. Our data suggest that defective S-SMase in NPD leads to SM enrichment of HDL that impairs LCAT-mediated nascent HDL maturation and contributes to HDL deficiency. Thus, S-SMase and LCAT may act in concert and play a crucial role in the biogenesis and maturation of nascent HDL particles. Supplementary key words high density lipoprotein . nascent LpA-I . phospholipids . sphingomyelin phosphodiesterase-1 gene . sphingomyelinase Sphingomyelin (SM) plays an important role in the structural integrity of the cellular membranes. The constitutive degradation of SM occurs in the lysosomal compartments of the cell. Fragments of the plasma membrane containing SM targeted for degradation are endocytosed and traffic through the endosomal compartments to reach the lysosomes, where they are hydrolyzed by lysosomal sphingomyelinase. The cleaved fragments (i.e., the choline head group, the fatty acids, and the sphingoid bases) then leave the lysosome and reenter the biosynthetic pathway or can be further degraded. In Niemann-Pick type I disease, which includes types A and B (NPD-A/B), lysosomal SMase is deficient, resulting in a lysosomal accumulation of SM and a secondary increase in cholesterol (1).Earlier studies by Tall and colleagues (2) investigated the crucial role of phospholipids (PLs) and their plasma transfer proteins in the metabolic pathway of HDL. It is well accepted that SM plays an important role in plasma lipoprotein metabolism. SM is the second most abundant PL in mammalian plasma. It appears in all major lipoproteins, where it is part of the monolayer of polar lipids and cholesterol that surrounds a core of neutral lipids. Up to 18% of total plasma PL occurs as SM, and the ratio of SM-to-phosphatidylcholine (PC) varies widely among lipoprotein su...

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Sphingomyelin-degrading pathways in human cells

Cited by 34 publications

References 86 publications

Endocytic Trafficking of Sphingomyelin Depends on Its Acyl Chain Length

Endocytic Trafficking of Sphingomyelin Depends on Its Acyl Chain Length

Up-regulation of Acid Sphingomyelinase during Retinoic Acid-induced Myeloid Differentiation of NB4, a Human Acute Promyelocytic Leukemia Cell Line

Increased sphingomyelin content impairs HDL biogenesis and maturation in human Niemann-Pick disease type B

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