Exit of GPI-Anchored Proteins from the ER Differs in Yeast and Mammalian Cells

Rivier, Anne-Sophie; Castillon, Guillaume A.; Michon, Laetitia; Fukasawa, Masayoshi; Romanova‐Michaelides, Maria; Jaensch, Nina; Hanada, Kentaro; Watanabe, Reika

doi:10.1111/j.1600-0854.2010.01081.x

Cited by 34 publications

(28 citation statements)

References 76 publications

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“…In GPI-deficient yeast, Tat2p and Fur4p fail to associate with DRM and are retained in the ER (Okamoto et al, 2006). Although DRM forms in the ER in yeast, in mammalian cells, it is likely that DRM formation occurs only after Golgi entry (Rivier et al, 2010). The reason for this is thought to be that GPI lipid remodeling occurs in different places: the ER in yeast and the Golgi body in mammalian cells (Rivier et al, 2010).…”

Section: Discussionmentioning

confidence: 99%

“…Although DRM forms in the ER in yeast, in mammalian cells, it is likely that DRM formation occurs only after Golgi entry (Rivier et al, 2010). The reason for this is thought to be that GPI lipid remodeling occurs in different places: the ER in yeast and the Golgi body in mammalian cells (Rivier et al, 2010). In mammalian cells, lipid rafts are postulated to concentrate some fractions of apically destined proteins owing to their affinity for the TGN (van Meer and Simons, 1988) or recycling endosomes (Rodriguez-Boulan et al, 2005).…”

Section: Discussionmentioning

confidence: 99%

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GPI biosynthesis is essential for rhodopsin sorting at the trans-Golgi network in Drosophila photoreceptors

et al. 2013

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SUMMARYSorting of integral membrane proteins plays crucial roles in establishing and maintaining the polarized structures of epithelial cells and neurons. However, little is known about the sorting mechanisms of newly synthesized membrane proteins at the trans-Golgi network (TGN). To identify which genes are essential for these sorting mechanisms, we screened mutants in which the transport of Rhodopsin 1 (Rh1), an apical integral membrane protein in Drosophila photoreceptors, was affected. We found that deficiencies in glycosylphosphatidylinositol (GPI) synthesis and attachment processes cause loss of the apical transport of Rh1 from the TGN and mis-sorting to the endolysosomal system. Moreover, Na + K + -ATPase, a basolateral membrane protein, and Crumbs (Crb), a stalk membrane protein, were mistransported to the apical rhabdomeric microvilli in GPI-deficient photoreceptors. These results indicate that polarized sorting of integral membrane proteins at the TGN requires the synthesis and anchoring of GPI-anchored proteins. Little is known about the cellular biological consequences of GPI deficiency in animals in vivo. Our results provide new insights into the importance of GPI synthesis and aid the understanding of pathologies involving GPI deficiency.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

GPI biosynthesis is essential for rhodopsin sorting at the trans-Golgi network in Drosophila photoreceptors

et al. 2013

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“…The membrane topology of the newly synthesized GPI-anchored proteins like CA IV is preserved on the vesicles bound to the cell surface (33,34). Previous studies showed that one can make a secretory form of CA IV by deleting the cleavage and anchoring sequence (35).…”

Section: Discussionmentioning

confidence: 99%

GPI-anchored carbonic anhydrase IV displays both intra- and extracellular activity in cRNA-injected oocytes and in mouse neurons

Schneider¹,

Alt²,

Klier

et al. 2013

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

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Soluble cytosolic carbonic anhydrases (CAs) are well known to participate in pH regulation of the cytoplasm of mammalian cells. Membrane-bound CA isoforms—such as isoforms IV, IX, XII, XIV, and XV—also catalyze the reversible conversion of carbon dioxide to protons and bicarbonate, but at the extracellular face of the cell membrane. When human CA isoform IV was heterologously expressed in Xenopus oocytes, we observed, by measuring H + at the outer face of the cell membrane and in the cytosol with ion-selective microelectrodes, not only extracellular catalytic CA activity but also robust intracellular activity. CA IV expression in oocytes was confirmed by immunocytochemistry, and CA IV activity measured by mass spectrometry. Extra- and intracellular catalytic activity of CA IV could be pharmacologically dissected using benzolamide, the CA inhibitor, which is relatively slowly membrane-permeable. In acute cerebellar slices of mutant mice lacking CA IV, cytosolic H + shifts of granule cells following CO 2 removal/addition were significantly slower than in wild-type mice. Our results suggest that membrane-associated CA IV contributes robust catalytic activity intracellularly, and that this activity participates in regulating H + dynamics in the cytosol, both in injected oocytes and in mouse neurons.

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“…In mammalian cells, it was shown that inhibition of sphingolipid biosynthesis affects apical targeting of GPI-anchored proteins in Madin-Darby canine kidney (MDCK) cells ( 13 ) and sorting of the axonal GPI-anchored protein Thy-1 in primary hippocampal neurons ( 14 ). However unlike yeast, ER-to-Golgi transport of GPI-anchored proteins in mammalian cells does not depend on de novo sphingolipid biosynthesis ( 15 ).…”

Section: Rna Isolation and Quantitative Rt-pcrmentioning

confidence: 99%

“…Constructs were verifi ed by sequencing. Vector pME-puroVenus-FLAG-CD59 ( 15 ) was obtained from the laboratory of Reika Watanabe (University of Geneva, Switzerland).…”

Section: 1/zeomentioning

confidence: 99%

Glycosylphosphatidylinositol anchors regulate glycosphingolipid levels

Loizides‐Mangold

David

Nesatyy

et al. 2012

Journal of Lipid Research

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This article is available online at http://www.jlr.org anchor has the core structure phosphatidylinositol (PI)-glucosamine (GlcN)-(Mannose) 3 -phosphoethanolamine (EtN-P), which is conserved among all species. After biosynthesis, the GPI anchor is attached posttranslationally to the newly generated C terminus of certain eukaryotic proteins destined for anchoring thereby tethering the protein to the membrane surface by the glycolipid moiety. GPI-anchored proteins can be released from the cell surface by phosphatidylinositol specifi c phospholipases and this cleavage event can induce major conformational changes on the GPIanchored protein itself ( 2 ).At least three organelles, the endoplasmic reticulum (ER), Golgi, and peroxisomes, are involved in the biosynthesis and remodeling of the GPI anchor. The biosynthesis is initiated on the outer side of the ER membrane. After the fi rst two reactions, the GPI anchor precursor is fl ipped and biosynthesis continues on the luminal side of the ER where the diacyl chains of phosphatidylinositol are then replaced by alkyl-acyl chains. This step is impaired in mutants of the peroxisomal alkyl phospholipid biosynthesis pathway ( 3 ).After protein attachment, the GPI anchor undergoes complex remodeling that begins in the ER with the removal of the inositol-linked acyl chain ( 4 ) and the remodeling of the GPI glycan part (5). Glycan remodeling is crucial for sorting GPI-anchored proteins into ER exit sites and their subsequent ER to Golgi transport ( 6 ). In mammalian cells, remodeling of the GPI anchor is then continued in the Golgi where the unsaturated fatty acid of the GPI anchor is replaced by a saturated fatty acid chain ( 7 ). Abstract Glycosylphosphatidylinositol (GPI) anchor biosynthesis takes place in the endoplasmic reticulum (ER).After protein attachment, the GPI anchor is transported to the Golgi where it undergoes fatty acid remodeling. The ER exit of GPI-anchored proteins is controlled by glycan remodeling and p24 complexes act as cargo receptors for GPI anchor sorting into COPII vesicles. In this study, we have characterized the lipid profi le of mammalian cell lines that have a defect in GPI anchor biosynthesis. Depending on which step of GPI anchor biosynthesis the cells were defective, we observed sphingolipid changes predominantly for very long chain monoglycosylated ceramides (HexCer). We found that the structure of the GPI anchor plays an important role in the control of HexCer levels. GPI anchordefi cient cells that generate short truncated GPI anchor intermediates showed a decrease in very long chain HexCer levels. Cells that synthesize GPI anchors but have a defect in GPI anchor remodeling in the ER have a general increase in HexCer levels. GPI-transamidase-defi cient cells that produce no GPI-anchored proteins but generate complete free GPI anchors had unchanged levels of HexCer. In contrast, sphingomyelin levels were mostly unaffected. We therefore propose a model in which the transport of very long chain ceramide from the ER to Golgi is regulated by...

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Exit of GPI-Anchored Proteins from the ER Differs in Yeast and Mammalian Cells

Cited by 34 publications

References 76 publications

GPI biosynthesis is essential for rhodopsin sorting at the trans-Golgi network in Drosophila photoreceptors

GPI biosynthesis is essential for rhodopsin sorting at the trans-Golgi network in Drosophila photoreceptors

GPI-anchored carbonic anhydrase IV displays both intra- and extracellular activity in cRNA-injected oocytes and in mouse neurons

Glycosylphosphatidylinositol anchors regulate glycosphingolipid levels

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