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Needham PG, Brodsky JL. How early studies on secreted and membrane protein quality control gave rise to the ER associated degradation (ERAD) pathway: the early history of ERAD. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2013; 1833:2447-57. [PMID: 23557783 DOI: 10.1016/j.bbamcr.2013.03.018] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2012] [Revised: 03/18/2013] [Accepted: 03/21/2013] [Indexed: 12/31/2022]
Abstract
All newly synthesized proteins are subject to quality control check-points, which prevent aberrant polypeptides from harming the cell. For proteins that ultimately reside in the cytoplasm, components that also reside in the cytoplasm were known for many years to mediate quality control. Early biochemical and genetic data indicated that misfolded proteins were selected by molecular chaperones and then targeted to the proteasome (in eukaryotes) or to proteasome-like particles (in bacteria) for degradation. What was less clear was how secreted and integral membrane proteins, which in eukaryotes enter the endoplasmic reticulum (ER), were subject to quality control decisions. In this review, we highlight early studies that ultimately led to the discovery that secreted and integral membrane proteins also utilize several components that constitute the cytoplasmic quality control machinery. This component of the cellular quality control pathway is known as ER associated degradation, or ERAD. This article is part of a Special Issue entitled: Functional and structural diversity of endoplasmic reticulum.
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Affiliation(s)
- Patrick G Needham
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260, USA
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Peric D, Durrant-Arico C, Delenda C, Dupré T, De Lonlay P, de Baulny HO, Pelatan C, Bader-Meunier B, Danos O, Chantret I, Moore SEH. The compartmentalisation of phosphorylated free oligosaccharides in cells from a CDG Ig patient reveals a novel ER-to-cytosol translocation process. PLoS One 2010; 5:e11675. [PMID: 20652024 PMCID: PMC2907391 DOI: 10.1371/journal.pone.0011675] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2010] [Accepted: 06/14/2010] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Biosynthesis of the dolichol linked oligosaccharide (DLO) required for protein N-glycosylation starts on the cytoplasmic face of the ER to give Man(5)GlcNAc(2)-PP-dolichol, which then flips into the ER for further glycosylation yielding mature DLO (Glc(3)Man(9)GlcNAc(2)-PP-dolichol). After transfer of Glc(3)Man(9)GlcNAc(2) onto protein, dolichol-PP is recycled to dolichol-P and reused for DLO biosynthesis. Because de novo dolichol synthesis is slow, dolichol recycling is rate limiting for protein glycosylation. Immature DLO intermediates may also be recycled by pyrophosphatase-mediated cleavage to yield dolichol-P and phosphorylated oligosaccharides (fOSGN2-P). Here, we examine fOSGN2-P generation in cells from patients with type I Congenital Disorders of Glycosylation (CDG I) in which defects in the dolichol cycle cause accumulation of immature DLO intermediates and protein hypoglycosylation. METHODS AND PRINCIPAL FINDINGS In EBV-transformed lymphoblastoid cells from CDG I patients and normal subjects a correlation exists between the quantities of metabolically radiolabeled fOSGN2-P and truncated DLO intermediates only when these two classes of compounds possess 7 or less hexose residues. Larger fOSGN2-P were difficult to detect despite an abundance of more fully mannosylated and glucosylated DLO. When CDG Ig cells, which accumulate Man(7)GlcNAc(2)-PP-dolichol, are permeabilised so that vesicular transport and protein synthesis are abolished, the DLO pool required for Man(7)GlcNAc(2)-P generation could be depleted by adding exogenous glycosylation acceptor peptide. Under conditions where a glycotripeptide and neutral free oligosaccharides remain predominantly in the lumen of the ER, Man(7)GlcNAc(2)-P appears in the cytosol without detectable generation of ER luminal Man(7)GlcNAc(2)-P. CONCLUSIONS AND SIGNIFICANCE The DLO pools required for N-glycosylation and fOSGN2-P generation are functionally linked and this substantiates the hypothesis that pyrophosphatase-mediated cleavage of DLO intermediates yields recyclable dolichol-P. The kinetics of cytosolic fOSGN2-P generation from a luminally-generated DLO intermediate demonstrate the presence of a previously undetected ER-to-cytosol translocation process for either fOSGN2-P or DLO.
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Affiliation(s)
- Delphine Peric
- INSERM U773 CRB3, Paris, France
- Université Denis Diderot, Paris 7, Paris, France
| | | | | | - Thierry Dupré
- INSERM U773 CRB3, Paris, France
- Université Denis Diderot, Paris 7, Paris, France
- AP-HP, Hôpital Bichat-Claude Bernard, Biochimie Métabolique et Cellulaire, Paris, France
| | - Pascale De Lonlay
- Département de Pédiatrie, Hôpital Necker-Enfants Malades, Paris, France
| | | | - Cécile Pelatan
- Centre Hospitalier, Service de Pédiatrie, Le Mans, France
| | | | - Olivier Danos
- Généthon: Evry, France
- INSERM U781, Hôpital Necker-Enfants Malades, Paris, France
| | - Isabelle Chantret
- INSERM U773 CRB3, Paris, France
- Université Denis Diderot, Paris 7, Paris, France
| | - Stuart E. H. Moore
- INSERM U773 CRB3, Paris, France
- Université Denis Diderot, Paris 7, Paris, France
- * E-mail:
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Haga Y, Totani K, Ito Y, Suzuki T. Establishment of a real-time analytical method for free oligosaccharide transport from the ER to the cytosol. Glycobiology 2009; 19:987-94. [PMID: 19494346 DOI: 10.1093/glycob/cwp075] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
During N-glycosylation of proteins, significant amounts of free unconjugated glycans are also generated in the lumen of the endoplasmic reticulum (ER). These ER-derived free glycans are translocated into the cytosol by a putative transporter on the ER membrane for further processing. However, the molecular nature of the transporter remains to be determined. Here, we report the establishment of a novel assay method for free oligosaccharide transport from the ER lumen using chemically synthesized fluorescence-labeled N-glycan derivatives. In this method, fluorescence-labeled glycan substrates were encapsulated inside mouse liver microsomes, followed by incubation with the cytosol and a fluorescence-quenching agent (anti-fluorophore antibody). The rate of substrate efflux was then monitored in real time by the decrease in the fluorescence intensity. The present data clearly demonstrated that the oligosaccharide transport activity under the current assay conditions was both ATP and cytosol dependent. The transporter activity was also found to be glycan structure specific because free glucosylated glycans were unable to be transported out of the microsomes. This new assay method will be a useful tool for identifying the transporter protein on the ER membrane.
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Affiliation(s)
- Yoshimi Haga
- Glycometabolome Team, RIKEN Advanced Science Institute, Wako, Saitama 351-0198, Japan
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Ali BRS, Edwards LC, Field MC. Reconstitution of glycopeptide export in mixed detergent-solubilised and resealed microsomes depleted of lumenal components. JOURNAL OF BIOCHEMICAL AND BIOPHYSICAL METHODS 2005; 62:1-12. [PMID: 15656939 DOI: 10.1016/j.jbbm.2004.01.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2003] [Revised: 12/22/2003] [Accepted: 01/01/2004] [Indexed: 02/05/2023]
Abstract
Export of macromolecules from the endoplasmic reticulum (ER) lumen into the cytosol is a major aspect of the quality control systems operating within the early secretory system. Glycopeptides are exported from the ER by an ATP- and GTP-dependent pathway, which shares many similarities to the protein export system. Significantly, for glycopeptides, there is no requirement for cytosolic factors, biochemically distinguishing the glycopeptide and protein paths and probably reflecting the lower conformational complexity of the former substrate. Genetic studies in yeast, and biochemical data from higher eukaryotes, indicate that glycopeptides utilise the Sec61 translocon. Here, we report a new system allowing access to lumenal ER components, facilitating assessment of their importance in glycopeptide retrotranslocation and potentially other processes. Saponin, in combination with CHAPS, but not saponin alone, facilitated removal of >95% of lumenal protein disulphide isomerase (PDI) and BiP. Upon resealing, these microsomes retained glycopeptide export competence. These data suggest that the majority of lumenal components of the ER are most likely nonessential for glycopeptide export. In addition, export competence was highly sensitive to the addition of external protease, indicating a role for protein factors with cytoplasmically exposed determinants.
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Affiliation(s)
- Bassam R S Ali
- Department of Biological Sciences, Imperial College, London, SW7 2AY, UK
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Suzuki T, Lennarz WJ. Glycopeptide export from the endoplasmic reticulum into cytosol is mediated by a mechanism distinct from that for export of misfolded glycoprotein. Glycobiology 2002; 12:803-11. [PMID: 12499402 DOI: 10.1093/glycob/cwf095] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
When glycoproteins formed in the endoplasmic reticulum (ER) are misfolded, they are generally translocated into the cytosol for ubiquitination and are subsequently degraded by the proteasome. This system, the so-called ER-associated glycoprotein degradation, is important for eukaryotes to maintain the quality of glycoproteins generated in the ER. It has been established in yeast that several distinct proteins are involved in this translocation and degradation processes. Small glycopeptides formed in the ER are exported to the cytosol in a similar manner. This glycopeptide export system is conserved from yeast to mammalian cells, suggesting its basic biological significance for eukaryotic cells. These two export systems (for misfolded glycoproteins and glycopeptides) share some properties, such as a requirement for ATP and involvement of Sec61p, a central membrane protein presumably forming a dislocon channel for export of proteins. However, the machinery of glycopeptide export is poorly understood. In this study, various mutants known to have an effect on export/degradation of misfolded glycoproteins were examined for glycopeptide export activity with a newly established assay method. Surprisingly, most of the mutants were found not to exhibit a defect in glycopeptide export. The only gene that was found to be required on efficient export of both types of substrates was PMR1, the gene encoding the medial-Golgi Ca(2+)/Mn(2+)-ion pump. These results provide evidence that although the systems involved in export of misfolded glycoproteins and glycopeptides share some properties, they have exhibited distinct differences.
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Affiliation(s)
- Tadashi Suzuki
- Department of Biophysics and Biochemistry, Graduate School of Science, University of Tokyo and PRESTO, Japan Science and Technology Corporation (JST), Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033, Japan
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Nair JS, DaFonseca CJ, Tjernberg A, Sun W, Darnell JE, Chait BT, Zhang JJ. Requirement of Ca2+ and CaMKII for Stat1 Ser-727 phosphorylation in response to IFN-gamma. Proc Natl Acad Sci U S A 2002; 99:5971-6. [PMID: 11972023 PMCID: PMC122886 DOI: 10.1073/pnas.052159099] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
In response to IFN-gamma, the latent cytoplasmic protein signal transducers and activators of transcription 1 (Stat1) becomes phosphorylated on Y701, dimerizes, and accumulates in the nucleus to activate transcription of IFN-gamma-responsive genes. For maximal gene activation, S727 in the transcription activation domain of Stat1 also is inducibly phosphorylated by IFN-gamma. We previously purified a group of nuclear proteins that interact specifically with the Stat1 transcription activation domain. In this report, we identified one of them as the multifunctional Ca(2+)/calmodulin-dependent kinase (CaMK) II. We demonstrate that IFN-gamma mobilizes a Ca(2+) flux in cells and activates CaMKII. CaMKII can interact directly with Stat1 and phosphorylate Stat1 on S727 in vitro. Inhibition of Ca(2+) flux or CaMKII results in a lack of S727 phosphorylation and Stat1-dependent gene activation, suggesting in vivo phosphorylation of Stat1 S727 by CaMKII. Thus two different cellular signaling events, IFN-gamma receptor occupation and Ca(2+) flux, are required for Stat1 to achieve maximal transcriptional activation through regulation of phosphorylation.
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Affiliation(s)
- Jayasree S Nair
- Department of Pathology, Weill Medical College of Cornell University, 1300 York Avenue, New York, NY 10021, USA
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Chen LM, Skinner ML, Kauffman SW, Chao J, Chao L, Thaler CD, Chai KX. Prostasin is a glycosylphosphatidylinositol-anchored active serine protease. J Biol Chem 2001; 276:21434-42. [PMID: 11274175 DOI: 10.1074/jbc.m011423200] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
A recombinant human prostasin serine protease was expressed in several human cell lines. Subcellular fractionation showed that this serine protease is synthesized as a membrane-bound protein while a free-form prostasin is secreted into the culture medium. Prostasin was identified in nuclear and membrane fractions. Membrane-bound prostasin can be released by phosphatidylinositol-specific phospholipase C treatment, or labeled by [(3)H]ethanolamine, indicating a glycosylphosphatidylinositol anchorage. A prostasin-binding protein was identified in mouse and human seminal vesicle fluid. Both the secreted and the membrane-bound prostasin were able to form a covalently linked 82-kDa complex when incubated with seminal vesicle fluid. The complex formation between prostasin and the prostasin-binding protein was inhibited by a prostasin antibody, heparin, and serine protease inhibitors. Prostasin's serine protease activity was inhibited when bound to the prostasin-binding protein in mouse seminal vesicle fluid. This study indicates that prostasin is an active serine protease in its membrane-bound form.
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Affiliation(s)
- L M Chen
- Department of Molecular Biology, University of Central Florida, Orlando, Florida 32816, USA
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