Sphingolipid transport in eukaryotic cells

Meer, Gerrit van; Holthuis, Joost C. M.

doi:10.1016/s1388-1981(00)00054-8

Cited by 153 publications

(96 citation statements)

References 301 publications

(200 reference statements)

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“…Although mammalian SLs are known to reside mainly in the exoplasmic leaflet of the plasma membrane (Holthuis et al, 2001), ϳ20% of them are found in the cytoplasmic leaflet (Boon and Smith, 2002). Even if no data are currently available about the distribution of SLs over the two leaflets of the yeast plasma membrane (van Meer and Holthuis, 2000), it is thus conceivable that at least a small fraction of these lipids face the cytoplasm, in particular if they are forming a shell around transmembrane proteins. Because the cytosolic lysines 76, 87, and 91 of Gap1 are close to the membrane ( Figure 3F), they might be part of the region containing the SL head groups and thus be inaccessible to posttranslational modifications.…”

Section: Discussionmentioning

confidence: 99%

Evidence for Coupled Biogenesis of Yeast Gap1 Permease and Sphingolipids: Essential Role in Transport Activity and Normal Control by Ubiquitination

Lauwers

Großmann

André

2007

MBoC

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Current models for plasma membrane organization integrate the emerging concepts that membrane proteins tightly associate with surrounding lipids and that biogenesis of surface proteins and lipids may be coupled. We show here that the yeast general amino acid permease Gap1 synthesized in the absence of sphingolipid (SL) biosynthesis is delivered to the cell surface but undergoes rapid and unregulated down-regulation. Furthermore, the permease produced under these conditions but blocked at the cell surface is inactive, soluble in detergent, and more sensitive to proteases. We also show that SL biogenesis is crucial during Gap1 production and secretion but that it is dispensable once Gap1 has reached the plasma membrane. Moreover, the defects displayed by cell surface Gap1 neosynthesized in the absence of SL biosynthesis are not compensated by subsequent restoration of SL production. Finally, we show that down-regulation of Gap1 caused by lack of SL biogenesis involves the ubiquitination of the protein on lysines normally not accessible to ubiquitination and close to the membrane. We propose that coupled biogenesis of Gap1 and SLs would create an SL microenvironment essential to the normal conformation, function, and control of ubiquitination of the permease. INTRODUCTIONBiological membranes were long seen as a "fluid mosaic" of proteins simply dispersed in a homogeneous lipid bilayer (Singer and Nicholson, 1972). This view contrasts with current models of the plasma membrane that take into account the heterogeneity of lipids in length and structure and the very high density of intrinsic proteins, ϳ30,000 per m 2 (Jacobson et al., 2007). These models also integrate the important notion of lateral heterogeneity, i.e., that the plasma membrane contains domains of various lipid compositions and physical properties. Among these domains, lipid rafts have been the subject of many studies. Although the definition of rafts is still debated (Pike, 2006), they are generally viewed as small domains of various sizes (ϳ10 -200 nm in diameter) that are formed by the dynamic assembly of sphingolipids with sterols (Simons and Ikonen, 1997;Jacobson et al., 2007). These domains selectively include or exclude proteins, and they are thought to exist in a liquid-ordered phase distinct from the bulk liquid-disordered phase of the membrane (Brown and London, 1998). Their tightly packed state makes them more resistant to solubilization by nonionic detergents such as Triton X-100, so that they yield detergent-resistant membranes (DRMs) after detergent extraction in the cold (London and Brown, 2000). Despite the limitations of detergent-dependent methods and the caution that must be exerted when interpreting the resulting data, the isolation of DRMs remains a useful tool for investigating protein-lipid interactions and membrane domains (Brown and London, 1998;Shogomori and Brown, 2003;Lichtenberg et al., 2005). A complementary approach consists in visualizing raft components directly in the plasma membrane of living cells. In Saccharomyces ...

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Section: Discussionmentioning

confidence: 99%

Evidence for Coupled Biogenesis of Yeast Gap1 Permease and Sphingolipids: Essential Role in Transport Activity and Normal Control by Ubiquitination

Lauwers

Großmann

André

2007

MBoC

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“…Thus, Arv1p may function within one or both of these pathways in the ER-toGolgi transport of ceramide. Because ceramide is synthesized in the ER of animal cells and is transported to the Golgi for conversion to sphingomyelin (65), hArv1p may function in a similar fashion.…”

Section: Discussionmentioning

confidence: 99%

Yeast Cells Lacking the ARV1 Gene Harbor Defects in Sphingolipid Metabolism

Swain¹,

Stukey²,

McDonough³

et al. 2002

Journal of Biological Chemistry

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]dihydrosphingosine radiolabeling studies demonstrated that mutant cells had reduced rates of biosynthesis and lower steadystate levels of complex sphingolipids while accumulating certain hydroxylated ceramide species. Phospholipid radiolabeling studies showed that arv1⌬ cells harbored defects in the rates of biosynthesis and steadystate levels of phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine, and phosphatidylglycerol. Neutral lipid radiolabeling studies indicated that the rate of biosynthesis and steady-state levels of sterol ester were increased in arv1⌬ cells. Moreover, these same studies demonstrated that arv1⌬ cells had decreased rates of biosynthesis and steady-state levels of total fatty acid and fatty acid alcohols. Gas chromatography/mass spectrometry analyses examining different fatty acid species showed that arv1⌬ cells had decreased levels of C18:1 fatty acid. Additional gas chromatography/mass spectrometry analyses determining the levels of various molecular sterol species in arv1⌬ cells showed that mutant cells accumulated early sterol intermediates. Using fluorescence microscopy we found that GFP-Arv1p localizes to the endoplasmic reticulum and Golgi. Interestingly, the heterologous expression of the human ARV1 cDNA suppressed the sphingolipid metabolic defects of arv1⌬ cells. We hypothesize that in eukaryotic cells, Arv1p functions in the sphingolipid metabolic pathway perhaps as a transporter of ceramides between the endoplasmic reticulum and Golgi.Sphingolipids serve as constituents of membrane bilayers (1) and have emerged as potent signaling metabolites (2-5). Sphingolipid synthesis in eukaryotes begins with the condensation of serine and palmitoyl-CoA, a reaction catalyzed by the Lcb1p/ Lcb2p serine palmitoyltransferase subunits (Fig. 1) (6 -10). Ceramide serves as the backbone for all complex sphingolipids, and its biosynthesis is the point where animal and fungal sphingolipid biosynthesis begin to diverge (11). In higher eukaryotes, there are over three hundred different types of complex sphingolipids found in membranes (1), whereas in the yeast S. cerevisiae there are three, inositolphosphorylceramide (IPC), 1 mannose inositolphosphorylceramide (MIPC), and mannose diinositolphosphorylceramide (MIP 2 C). However, IPC, MIPC, and MIP 2 C lipids can differ in their hydroxylation state, giving rise to fifteen possible complex sphingolipids (11).The accumulation of free cholesterol in animal cells causes toxicity (12). One mechanism by which cells relieve this toxic effect is through the use of the membrane-associated SREBP transcription factors, which precisely regulate the genes that are required for sterol biosynthesis and LDL receptor expression (13,14). Worgall et al. (15) recently showed that SREBP activation was regulated by ceramide. Others have shown that animal cells regulate sphingolipid metabolism in response to subtle and transient changes in cholesterol (16,17). In S. cerevisiae, sphingolipid metabolism appears to be coordinately regulated with phospholipid an...

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“…Therefore, the transportation of sphingolipids from one organelle to others must be highly organized. The interorganelle trafficking of sphingolipids is mediated in either a vesicular or nonvesicular manner (2). For instance, in mammalian cells, a de novo synthesized ceramide in ER membranes is transported to the Golgi in a nonvesicular manner by an ER-to-Golgi specific ceramide transporter (CERT, also known as GPBP⌬26, a splicing variant of Goodpasture antigenbinding protein) (3,4).…”

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confidence: 99%

Structural Basis for the Golgi Association by the Pleckstrin Homology Domain of the Ceramide Trafficking Protein (CERT)

Sugiki

Takeuchi

Yamaji

et al. 2012

Journal of Biological Chemistry

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Background:The CERT PH domain is indispensable for the ER-to-Golgi ceramide transport. Results: The three-dimensional structure and interaction study revealed the Golgi recognition mode of the CERT PH domain. Conclusion:The basic groove in the CERT PH domain plays a critical role in the Golgi recognition. Significance: Conservation of the basic groove within lipid transporters uncovers functional significance of the structural motif.

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Sphingolipid transport in eukaryotic cells

Cited by 153 publications

References 301 publications

Evidence for Coupled Biogenesis of Yeast Gap1 Permease and Sphingolipids: Essential Role in Transport Activity and Normal Control by Ubiquitination

Evidence for Coupled Biogenesis of Yeast Gap1 Permease and Sphingolipids: Essential Role in Transport Activity and Normal Control by Ubiquitination

Yeast Cells Lacking the ARV1 Gene Harbor Defects in Sphingolipid Metabolism

Structural Basis for the Golgi Association by the Pleckstrin Homology Domain of the Ceramide Trafficking Protein (CERT)

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