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Ortiz-Ramírez JA, Cuéllar-Cruz M, Villagómez-Castro JC, López-Romero E. Fungal Glycosidases in Sporothrix Species and Candida albicans. J Fungi (Basel) 2023; 9:919. [PMID: 37755027 PMCID: PMC10532485 DOI: 10.3390/jof9090919] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2023] [Revised: 08/30/2023] [Accepted: 09/06/2023] [Indexed: 09/28/2023] Open
Abstract
Glycoside hydrolases (GHs) are enzymes that participate in many biological processes of fungi and other organisms by hydrolyzing glycosidic linkages in glycosides. They play fundamental roles in the degradation of carbohydrates and the assembly of glycoproteins and are important subjects of studies in molecular biology and biochemistry. Based on amino acid sequence similarities and 3-dimensional structures in the carbohydrate-active enzyme (CAZy), they have been classified in 171 families. Members of some of these families also exhibit the activity of trans-glycosydase or glycosyl transferase (GT), i.e., they create a new glycosidic bond in a substrate instead of breaking it. Fungal glycosidases are important for virulence by aiding tissue adhesion and colonization, nutrition, immune evasion, biofilm formation, toxin release, and antibiotic resistance. Here, we review fungal glycosidases with a particular emphasis on Sporothrix species and C. albicans, two well-recognized human pathogens. Covered issues include a brief account of Sporothrix, sporotrichosis, the different types of glycosidases, their substrates, and mechanism of action, recent advances in their identification and characterization, their potential biotechnological applications, and the limitations and challenges of their study given the rather poor available information.
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Affiliation(s)
| | | | | | - Everardo López-Romero
- Departamento de Biología, División de Ciencias Naturales y Exactas, Universidad de Guanajuato, Guanajuato 36050, Mexico
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Cruz Marino T, Leblanc J, Pratte A, Tardif J, Thomas MJ, Fortin CA, Girard L, Bouchard L. Portrait of autosomal recessive diseases in the French-Canadian founder population of Saguenay-Lac-Saint-Jean. Am J Med Genet A 2023; 191:1145-1163. [PMID: 36786328 DOI: 10.1002/ajmg.a.63147] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Revised: 01/16/2023] [Accepted: 01/30/2023] [Indexed: 02/15/2023]
Abstract
The population of the Saguenay-Lac-Saint-Jean (SLSJ) region, located in the province of Quebec, Canada, is recognized as a founder population, where some rare autosomal recessive diseases show a high prevalence. Through the clinical and molecular study of 82 affected individuals from 60 families, this study outlines 12 diseases identified as recurrent in SLSJ. Their carrier frequency was estimated with the contribution of 1059 healthy individuals, increasing the number of autosomal recessive diseases with known carrier frequency in this region from 14 to 25. We review the main clinical and molecular features previously reported for these disorders. Five of the studied diseases have a potential lethal effect and three are associated with intellectual deficiency. Therefore, we believe that the provincial program for carrier screening should be extended to include these eight disorders. The high-carrier frequency, together with the absence of consanguinity in most of these unrelated families, suggest a founder effect and genetic drift for the 12 recurrent variants. We recommend further studies to validate this hypothesis, as well as to extend the present study to other regions in the province of Quebec, since some of these disorders could also be present in other French-Canadian families.
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Affiliation(s)
- Tania Cruz Marino
- Department of Laboratory Medicine, CIUSSS Saguenay-Lac-St-Jean, Quebec, Canada
| | - Josianne Leblanc
- Department of Laboratory Medicine, CIUSSS Saguenay-Lac-St-Jean, Quebec, Canada
| | - Annabelle Pratte
- Department of Laboratory Medicine, CIUSSS Saguenay-Lac-St-Jean, Quebec, Canada
| | - Jessica Tardif
- Department of Laboratory Medicine, CIUSSS Saguenay-Lac-St-Jean, Quebec, Canada
| | | | - Carol-Ann Fortin
- Department of Biochemistry and Functional Genomics, Faculty of Medicine and Health Sciences (FMHS), Université de Sherbrooke, Quebec, Canada
| | - Lysanne Girard
- Department of Biochemistry and Functional Genomics, Faculty of Medicine and Health Sciences (FMHS), Université de Sherbrooke, Quebec, Canada
| | - Luigi Bouchard
- Department of Laboratory Medicine, CIUSSS Saguenay-Lac-St-Jean, Quebec, Canada.,Department of Biochemistry and Functional Genomics, Faculty of Medicine and Health Sciences (FMHS), Université de Sherbrooke, Quebec, Canada
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3
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Calnexin, More Than Just a Molecular Chaperone. Cells 2023; 12:cells12030403. [PMID: 36766745 PMCID: PMC9913998 DOI: 10.3390/cells12030403] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Revised: 01/17/2023] [Accepted: 01/17/2023] [Indexed: 01/26/2023] Open
Abstract
Calnexin is a type I integral endoplasmic reticulum (ER) membrane protein with an N-terminal domain that resides in the lumen of the ER and a C-terminal domain that extends into the cytosol. Calnexin is commonly referred to as a molecular chaperone involved in the folding and quality control of membrane-associated and secreted proteins, a function that is attributed to its ER- localized domain with a structure that bears a strong resemblance to another luminal ER chaperone and Ca2+-binding protein known as calreticulin. Studies have discovered that the cytosolic C-terminal domain of calnexin undergoes distinct post-translational modifications and interacts with a variety of proteins. Here, we discuss recent findings and hypothesize that the post-translational modifications of the calnexin C-terminal domain and its interaction with specific cytosolic proteins play a role in coordinating ER functions with events taking place in the cytosol and other cellular compartments.
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Gorelik A, Illes K, Bui KH, Nagar B. Structures of the mannose-6-phosphate pathway enzyme, GlcNAc-1-phosphotransferase. Proc Natl Acad Sci U S A 2022; 119:e2203518119. [PMID: 35939698 PMCID: PMC9388126 DOI: 10.1073/pnas.2203518119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2022] [Accepted: 05/06/2022] [Indexed: 11/18/2022] Open
Abstract
The mannose-6-phosphate (M6P) pathway is responsible for the transport of hydrolytic enzymes to lysosomes. N-acetylglucosamine-1-phosphotransferase (GNPT) catalyzes the first step of tagging these hydrolases with M6P, which when recognized by receptors in the Golgi diverts them to lysosomes. Genetic defects in the GNPT subunits, GNPTAB and GNPTG, cause the lysosomal storage diseases mucolipidosis types II and III. To better understand its function, we determined partial three-dimensional structures of the GNPT complex. The catalytic domain contains a deep cavity for binding of uridine diphosphate-N-acetylglucosamine, and the surrounding residues point to a one-step transfer mechanism. An isolated structure of the gamma subunit of GNPT reveals that it can bind to mannose-containing glycans in different configurations, suggesting that it may play a role in directing glycans into the active site. These findings may facilitate the development of therapies for lysosomal storage diseases.
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Affiliation(s)
- Alexei Gorelik
- Department of Biochemistry, McGill University, Montreal, QC H3G 0B1, Canada
- Department of Anatomy and Cell Biology, McGill University, Montreal, QC H3A 0C7, Canada
| | - Katalin Illes
- Department of Biochemistry, McGill University, Montreal, QC H3G 0B1, Canada
| | - Khanh Huy Bui
- Department of Anatomy and Cell Biology, McGill University, Montreal, QC H3A 0C7, Canada
| | - Bhushan Nagar
- Department of Biochemistry, McGill University, Montreal, QC H3G 0B1, Canada
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Kuribara T, Totani K. Oligomannose-Type Glycan Processing in the Endoplasmic Reticulum and Its Importance in Misfolding Diseases. BIOLOGY 2022; 11:biology11020199. [PMID: 35205066 PMCID: PMC8869290 DOI: 10.3390/biology11020199] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Revised: 12/04/2021] [Accepted: 01/24/2022] [Indexed: 11/16/2022]
Abstract
Simple Summary Glycans play many roles in biological processes. For instance, they mediate cell–cell interaction, viral infection, and protein folding of glycoproteins. Glycoprotein folding in the endoplasmic reticulum (ER) is closely related to the onset of diseases such as misfolding diseases caused by accumulation of misfolded proteins in the ER. In this review, we focused on oligomannose-type glycan processing in the ER, which has central roles in glycoprotein folding in the ER, and we summarise relationship between oligomannose-type glycan processing and misfolding diseases arising from the disruption of ER homeostasis. Abstract Glycoprotein folding plays a critical role in sorting glycoprotein secretion and degradation in the endoplasmic reticulum (ER). Furthermore, relationships between glycoprotein folding and several diseases, such as type 2 diabetes and various neurodegenerative disorders, are indicated. Patients’ cells with type 2 diabetes, and various neurodegenerative disorders induce ER stress, against which the cells utilize the unfolded protein response for protection. However, in some cases, chronic and/or massive ER stress causes critical damage to cells, leading to the onset of ER stress-related diseases, which are categorized into misfolding diseases. Accumulation of misfolded proteins may be a cause of ER stress, in this respect, perturbation of oligomannose-type glycan processing in the ER may occur. A great number of studies indicate the relationships between ER stress and misfolding diseases, while little evidence has been reported on the connection between oligomannose-type glycan processing and misfolding diseases. In this review, we summarize alteration of oligomannose-type glycan processing in several ER stress-related diseases, especially misfolding diseases and show the possibility of these alteration of oligomannose-type glycan processing as indicators of diseases.
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Li H, Sun S. Protein Aggregation in the ER: Calm behind the Storm. Cells 2021; 10:cells10123337. [PMID: 34943844 PMCID: PMC8699410 DOI: 10.3390/cells10123337] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2021] [Revised: 11/19/2021] [Accepted: 11/22/2021] [Indexed: 02/06/2023] Open
Abstract
As one of the largest organelles in eukaryotic cells, the endoplasmic reticulum (ER) plays a vital role in the synthesis, folding, and assembly of secretory and membrane proteins. To maintain its homeostasis, the ER is equipped with an elaborate network of protein folding chaperones and multiple quality control pathways whose cooperative actions safeguard the fidelity of protein biogenesis. However, due to genetic abnormalities, the error-prone nature of protein folding and assembly, and/or defects or limited capacities of the protein quality control systems, nascent proteins may become misfolded and fail to exit the ER. If not cleared efficiently, the progressive accumulation of misfolded proteins within the ER may result in the formation of toxic protein aggregates, leading to the so-called “ER storage diseases”. In this review, we first summarize our current understanding of the protein folding and quality control networks in the ER, including chaperones, unfolded protein response (UPR), ER-associated protein degradation (ERAD), and ER-selective autophagy (ER-phagy). We then survey recent research progress on a few ER storage diseases, with a focus on the role of ER quality control in the disease etiology, followed by a discussion on outstanding questions and emerging concepts in the field.
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Affiliation(s)
- Haisen Li
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, MI 48201, USA;
| | - Shengyi Sun
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, MI 48201, USA;
- Department of Biochemistry, Microbiology and Immunology, Wayne State University School of Medicine, Detroit, MI 48201, USA
- Correspondence:
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Okamoto N, Ohto T, Enokizono T, Wada Y, Kohmoto T, Imoto I, Haga Y, Seino J, Suzuki T. Siblings with MAN1B1-CDG Showing Novel Biochemical Profiles. Cells 2021; 10:cells10113117. [PMID: 34831340 PMCID: PMC8618856 DOI: 10.3390/cells10113117] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Revised: 11/02/2021] [Accepted: 11/05/2021] [Indexed: 11/16/2022] Open
Abstract
Congenital disorders of glycosylation (CDG), inherited metabolic diseases caused by defects in glycosylation, are characterized by a high frequency of intellectual disability (ID) and various clinical manifestations. Two siblings with ID, dysmorphic features, and epilepsy were examined using mass spectrometry of serum transferrin, which revealed a CDG type 2 pattern. Whole-exome sequencing showed that both patients were homozygous for a novel pathogenic variant of MAN1B1 (NM_016219.4:c.1837del) inherited from their healthy parents. We conducted a HPLC analysis of sialylated N-linked glycans released from total plasma proteins and characterized the α1,2-mannosidase I activity of the lymphocyte microsome fraction. The accumulation of monosialoglycans was observed in MAN1B1-deficient patients, indicating N-glycan-processing defects. The enzymatic activity of MAN1B1 was compromised in patient-derived lymphocytes. The present patients exhibited unique manifestations including early-onset epileptic encephalopathy and cerebral infarction. They also showed coagulation abnormalities and hypertransaminasemia. Neither sibling had truncal obesity, which is one of the characteristic features of MAN1B1-CDG.
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Affiliation(s)
- Nobuhiko Okamoto
- Department of Medical Genetics, Osaka Women’s and Children’s Hospital, Izumi 594-1101, Japan
- Department of Molecular Medicine, Research Institute, Osaka Women’s and Children’s Hospital, Izumi 594-1101, Japan;
- Correspondence:
| | - Tatsuyuki Ohto
- Department of Pediatrics, Tsukuba University Faculty of Medicine, Tsukuba 305-8576, Japan; (T.O.); (T.E.)
| | - Takashi Enokizono
- Department of Pediatrics, Tsukuba University Faculty of Medicine, Tsukuba 305-8576, Japan; (T.O.); (T.E.)
| | - Yoshinao Wada
- Department of Molecular Medicine, Research Institute, Osaka Women’s and Children’s Hospital, Izumi 594-1101, Japan;
| | - Tomohiro Kohmoto
- Division of Molecular Genetics, Aichi Cancer Center Research Institute, Nagoya 464-8681, Japan; (T.K.); (I.I.)
- Department of Human Genetics, Graduate School of Biomedical Science, Tokushima University Graduate School, Tokushima 770-8503, Japan
| | - Issei Imoto
- Division of Molecular Genetics, Aichi Cancer Center Research Institute, Nagoya 464-8681, Japan; (T.K.); (I.I.)
- Department of Human Genetics, Graduate School of Biomedical Science, Tokushima University Graduate School, Tokushima 770-8503, Japan
| | - Yoshimi Haga
- Glycometabolic Biochemistry Laboratory, RIKEN Cluster for Pioneering Research (CPR), 2-1 Hirosawa, Wako 351-0198, Japan; (Y.H.); (J.S.); (T.S.)
- Cancer Proteomics Group, Cancer Precision Medicine Center, Japanese Foundation for Cancer Research, 3-8-31 Ariake, Koto-ku, Tokyo 135-8550, Japan
| | - Junichi Seino
- Glycometabolic Biochemistry Laboratory, RIKEN Cluster for Pioneering Research (CPR), 2-1 Hirosawa, Wako 351-0198, Japan; (Y.H.); (J.S.); (T.S.)
| | - Tadashi Suzuki
- Glycometabolic Biochemistry Laboratory, RIKEN Cluster for Pioneering Research (CPR), 2-1 Hirosawa, Wako 351-0198, Japan; (Y.H.); (J.S.); (T.S.)
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8
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Kemme L, Grüneberg M, Reunert J, Rust S, Park J, Westermann C, Wada Y, Schwartz O, Marquardt T. Translational balancing questioned: Unaltered glycosylation during disulfiram treatment in mannosyl-oligosaccharide alpha-1,2-mannnosidase-congenital disorders of glycosylation (MAN1B1-CDG). JIMD Rep 2021; 60:42-55. [PMID: 34258140 PMCID: PMC8260486 DOI: 10.1002/jmd2.12213] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Revised: 02/27/2021] [Accepted: 03/02/2021] [Indexed: 12/25/2022] Open
Abstract
MAN1B1-CDG is a multisystem disorder caused by mutations in MAN1B1, encoding the endoplasmic reticulum mannosyl-oligosaccharide alpha-1,2-mannnosidase. A defect leads to dysfunction within the degradation of misfolded glycoproteins. We present two additional patients with MAN1B1-CDG and a resulting defect in endoplasmic reticulum-associated protein degradation. One patient (P2) is carrying the previously undescribed p.E663K mutation. A therapeutic trial in patient 1 (P1) using disulfiram with the rationale to generate an attenuation of translation and thus a balanced, restored ER glycoprotein synthesis failed. No improvement of the transferrin glycosylation profile was seen.
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Affiliation(s)
- Lisa Kemme
- University Children's Hospital MünsterMuensterGermany
| | | | | | - Stephan Rust
- University Children's Hospital MünsterMuensterGermany
| | - Julien Park
- University Children's Hospital MünsterMuensterGermany
- Department of Clinical Sciences, NeurosciencesUmeå UniversityUmeåSweden
| | - Cordula Westermann
- Gerhard‐Domagk‐Institute of PathologyUniversity Hospital MuensterMuensterGermany
| | - Yoshinao Wada
- Osaka Medical Center and Research Institute for Maternal and Child HealthOsakaJapan
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9
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Ninagawa S. N-glycan Dependent Protein Quality Control System in the Endoplasmic Reticulum. TRENDS GLYCOSCI GLYC 2021. [DOI: 10.4052/tigg.2108.2e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Affiliation(s)
- Satoshi Ninagawa
- Department of Biophysics, Graduate School of Science, Kyoto University
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10
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Ninagawa S. N-glycan Dependent Protein Quality Control System in the Endoplasmic Reticulum. TRENDS GLYCOSCI GLYC 2021. [DOI: 10.4052/tigg.2108.2j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Affiliation(s)
- Satoshi Ninagawa
- Department of Biophysics, Graduate School of Science, Kyoto University
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11
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Kuribara T, Usui R, Totani K. Glycan structure-based perspectives on the entry and release of glycoproteins in the calnexin/calreticulin cycle. Carbohydr Res 2021; 502:108273. [PMID: 33713911 DOI: 10.1016/j.carres.2021.108273] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Revised: 02/16/2021] [Accepted: 02/23/2021] [Indexed: 12/16/2022]
Abstract
N-glycans are attached to newly synthesised polypeptides and are involved in the folding, secretion, and degradation of N-linked glycoproteins. In particular, the calnexin/calreticulin cycle, which is the central mechanism of the entry and release of N-linked glycoproteins depending on the folding sates, has been well studied. In addition to biological studies on the calnexin/calreticulin cycle, several studies have revealed complementary roles of in vitro chemistry-based research in the structure-based understanding of the cycle. In this mini-review, we summarise chemistry-based results and highlight their importance for further understanding of the cycle.
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Affiliation(s)
- Taiki Kuribara
- Department of Materials and Life Science, Faculty of Science and Technology, Seikei University, 3-3-1 Kichijoji-kitamachiMusashino-shi, Tokyo, 180-8633, Japan
| | - Ruchio Usui
- Department of Materials and Life Science, Faculty of Science and Technology, Seikei University, 3-3-1 Kichijoji-kitamachiMusashino-shi, Tokyo, 180-8633, Japan
| | - Kiichiro Totani
- Department of Materials and Life Science, Faculty of Science and Technology, Seikei University, 3-3-1 Kichijoji-kitamachiMusashino-shi, Tokyo, 180-8633, Japan.
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12
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Kang JA, Jeon YJ. How Is the Fidelity of Proteins Ensured in Terms of Both Quality and Quantity at the Endoplasmic Reticulum? Mechanistic Insights into E3 Ubiquitin Ligases. Int J Mol Sci 2021; 22:ijms22042078. [PMID: 33669844 PMCID: PMC7923238 DOI: 10.3390/ijms22042078] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Revised: 02/16/2021] [Accepted: 02/16/2021] [Indexed: 02/06/2023] Open
Abstract
The endoplasmic reticulum (ER) is an interconnected organelle that plays fundamental roles in the biosynthesis, folding, stabilization, maturation, and trafficking of secretory and transmembrane proteins. It is the largest organelle and critically modulates nearly all aspects of life. Therefore, in the endoplasmic reticulum, an enormous investment of resources, including chaperones and protein folding facilitators, is dedicated to adequate protein maturation and delivery to final destinations. Unfortunately, the folding and assembly of proteins can be quite error-prone, which leads to the generation of misfolded proteins. Notably, protein homeostasis, referred to as proteostasis, is constantly exposed to danger by flows of misfolded proteins and subsequent protein aggregates. To maintain proteostasis, the ER triages and eliminates terminally misfolded proteins by delivering substrates to the ubiquitin–proteasome system (UPS) or to the lysosome, which is termed ER-associated degradation (ERAD) or ER-phagy, respectively. ERAD not only eliminates misfolded or unassembled proteins via protein quality control but also fine-tunes correctly folded proteins via protein quantity control. Intriguingly, the diversity and distinctive nature of E3 ubiquitin ligases determine efficiency, complexity, and specificity of ubiquitination during ERAD. ER-phagy utilizes the core autophagy machinery and eliminates ERAD-resistant misfolded proteins. Here, we conceptually outline not only ubiquitination machinery but also catalytic mechanisms of E3 ubiquitin ligases. Further, we discuss the mechanistic insights into E3 ubiquitin ligases involved in the two guardian pathways in the ER, ERAD and ER-phagy. Finally, we provide the molecular mechanisms by which ERAD and ER-phagy conduct not only protein quality control but also protein quantity control to ensure proteostasis and subsequent organismal homeostasis.
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Affiliation(s)
- Ji An Kang
- Department of Biochemistry, College of Medicine, Chungnam National University, Daejeon 35015, Korea;
- Department of Medical Science, College of Medicine, Chungnam National University, Daejeon 35015, Korea
| | - Young Joo Jeon
- Department of Biochemistry, College of Medicine, Chungnam National University, Daejeon 35015, Korea;
- Department of Medical Science, College of Medicine, Chungnam National University, Daejeon 35015, Korea
- Correspondence:
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Abstract
Folding of proteins is essential so that they can exert their functions. For proteins that transit the secretory pathway, folding occurs in the endoplasmic reticulum (ER) and various chaperone systems assist in acquiring their correct folding/subunit formation. N-glycosylation is one of the most conserved posttranslational modification for proteins, and in eukaryotes it occurs in the ER. Consequently, eukaryotic cells have developed various systems that utilize N-glycans to dictate and assist protein folding, or if they consistently fail to fold properly, to destroy proteins for quality control and the maintenance of homeostasis of proteins in the ER.
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14
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Ninagawa S, George G, Mori K. Mechanisms of productive folding and endoplasmic reticulum-associated degradation of glycoproteins and non-glycoproteins. Biochim Biophys Acta Gen Subj 2020; 1865:129812. [PMID: 33316349 DOI: 10.1016/j.bbagen.2020.129812] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2020] [Revised: 12/09/2020] [Accepted: 12/09/2020] [Indexed: 12/22/2022]
Abstract
BACKGROUND The quality of proteins destined for the secretory pathway is ensured by two distinct mechanisms in the endoplasmic reticulum (ER): productive folding of newly synthesized proteins, which is assisted by ER-localized molecular chaperones and in most cases also by disulfide bond formation and transfer of an oligosaccharide unit; and ER-associated degradation (ERAD), in which proteins unfolded or misfolded in the ER are recognized and processed for delivery to the ER membrane complex, retrotranslocated through the complex with simultaneous ubiquitination, extracted by AAA-ATPase to the cytosol, and finally degraded by the proteasome. SCOPE OF REVIEW We describe the mechanisms of productive folding and ERAD, with particular attention to glycoproteins versus non-glycoproteins, and to yeast versus mammalian systems. MAJOR CONCLUSION Molecular mechanisms of the productive folding of glycoproteins and non-glycoproteins mediated by molecular chaperones and protein disulfide isomerases are well conserved from yeast to mammals. Additionally, mammals have gained an oligosaccharide structure-dependent folding cycle for glycoproteins. The molecular mechanisms of ERAD are also well conserved from yeast to mammals, but redundant expression of yeast orthologues in mammals has been encountered, particularly for components involved in recognition and processing of glycoproteins and components of the ER membrane complex involved in retrotranslocation and simultaneous ubiquitination of glycoproteins and non-glycoproteins. This may reflect an evolutionary consequence of increasing quantity or quality needs toward mammals. GENERAL SIGNIFICANCE The introduction of innovative genome editing technology into analysis of the mechanisms of mammalian ERAD, as exemplified here, will provide new insights into the pathogenesis of various diseases.
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Affiliation(s)
- Satoshi Ninagawa
- Department of Biophysics, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan.
| | - Ginto George
- Department of Biophysics, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
| | - Kazutoshi Mori
- Department of Biophysics, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan.
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The cytoplasmic tail of human mannosidase Man1b1 contributes to catalysis-independent quality control of misfolded alpha1-antitrypsin. Proc Natl Acad Sci U S A 2020; 117:24825-24836. [PMID: 32958677 DOI: 10.1073/pnas.1919013117] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The failure of polypeptides to achieve conformational maturation following biosynthesis can result in the formation of protein aggregates capable of disrupting essential cellular functions. In the secretory pathway, misfolded asparagine (N)-linked glycoproteins are selectively sorted for endoplasmic reticulum-associated degradation (ERAD) in response to the catalytic removal of terminal alpha-linked mannose units. Remarkably, ER mannosidase I/Man1b1, the first alpha-mannosidase implicated in this conventional N-glycan-mediated process, can also contribute to ERAD in an unconventional, catalysis-independent manner. To interrogate this functional dichotomy, the intracellular fates of two naturally occurring misfolded N-glycosylated variants of human alpha1-antitrypsin (AAT), Null Hong Kong (NHK), and Z (ATZ), in Man1b1 knockout HEK293T cells were monitored in response to mutated or truncated forms of transfected Man1b1. As expected, the conventional catalytic system requires an intact active site in the Man1b1 luminal domain. In contrast, the unconventional system is under the control of an evolutionarily extended N-terminal cytoplasmic tail. Also, N-glycans attached to misfolded AAT are not required for accelerated degradation mediated by the unconventional system, further demonstrating its catalysis-independent nature. We also established that both systems accelerate the proteasomal degradation of NHK in metabolic pulse-chase labeling studies. Taken together, these results have identified the previously unrecognized regulatory capacity of the Man1b1 cytoplasmic tail and provided insight into the functional dichotomy of Man1b1 as a component in the mammalian proteostasis network.
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Tax G, Lia A, Santino A, Roversi P. Modulation of ERQC and ERAD: A Broad-Spectrum Spanner in the Works of Cancer Cells? JOURNAL OF ONCOLOGY 2019; 2019:8384913. [PMID: 31662755 PMCID: PMC6791201 DOI: 10.1155/2019/8384913] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Accepted: 08/27/2019] [Indexed: 12/21/2022]
Abstract
Endoplasmic reticulum glycoprotein folding quality control (ERQC) and ER-associated degradation (ERAD) preside over cellular glycoprotein secretion and maintain steady glycoproteostasis. When cells turn malignant, cancer cell plasticity is affected and supported either by point mutations, preferential isoform selection, altered expression levels, or shifts to conformational equilibria of a secreted glycoprotein. Such changes are crucial in mediating altered extracellular signalling, metabolic behavior, and adhesion properties of cancer cells. It is therefore conceivable that interference with ERQC and/or ERAD can be used to selectively damage cancers. Indeed, inhibitors of the late stages of ERAD are already in the clinic against cancers such as multiple myeloma. Here, we review recent advances in our understanding of the complex relationship between glycoproteostasis and cancer biology and discuss the potential of ERQC and ERAD modulators for the selective targeting of cancer cell plasticity.
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Affiliation(s)
- Gábor Tax
- Leicester Institute of Structural and Chemical Biology, Department of Molecular and Cell Biology, University of Leicester, Henry Wellcome Building, Lancaster Road, Leicester LE1 7RH, UK
| | - Andrea Lia
- Leicester Institute of Structural and Chemical Biology, Department of Molecular and Cell Biology, University of Leicester, Henry Wellcome Building, Lancaster Road, Leicester LE1 7RH, UK
- Institute of Sciences of Food Production, C.N.R. Unit of Lecce, via Monteroni, I-73100 Lecce, Italy
| | - Angelo Santino
- Institute of Sciences of Food Production, C.N.R. Unit of Lecce, via Monteroni, I-73100 Lecce, Italy
| | - Pietro Roversi
- Leicester Institute of Structural and Chemical Biology, Department of Molecular and Cell Biology, University of Leicester, Henry Wellcome Building, Lancaster Road, Leicester LE1 7RH, UK
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A signal motif retains Arabidopsis ER-α-mannosidase I in the cis-Golgi and prevents enhanced glycoprotein ERAD. Nat Commun 2019; 10:3701. [PMID: 31420549 PMCID: PMC6697737 DOI: 10.1038/s41467-019-11686-9] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Accepted: 07/01/2019] [Indexed: 11/09/2022] Open
Abstract
The Arabidopsis ER-α-mannosidase I (MNS3) generates an oligomannosidic N-glycan structure that is characteristically found on ER-resident glycoproteins. The enzyme itself has so far not been detected in the ER. Here, we provide evidence that in plants MNS3 exclusively resides in the Golgi apparatus at steady-state. Notably, MNS3 remains on dispersed punctate structures when subjected to different approaches that commonly result in the relocation of Golgi enzymes to the ER. Responsible for this rare behavior is an amino acid signal motif (LPYS) within the cytoplasmic tail of MNS3 that acts as a specific Golgi retention signal. This retention is a means to spatially separate MNS3 from ER-localized mannose trimming steps that generate the glycan signal required for flagging terminally misfolded glycoproteins for ERAD. The physiological importance of the very specific MNS3 localization is demonstrated here by means of a structurally impaired variant of the brassinosteroid receptor BRASSINOSTEROID INSENSITIVE 1. The Arabidopsis ER-α-mannosidase I MNS3 generates N-glycan structures typical of ER-resident glycoproteins. Here Schoberer et al. identify a novel motif that anchors MNS3 to the cis-Golgi, spatially separating MNS3 from ER-localized mannose trimming associated with the ER-associated degradation pathway.
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18
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Shenkman M, Lederkremer GZ. Compartmentalization and Selective Tagging for Disposal of Misfolded Glycoproteins. Trends Biochem Sci 2019; 44:827-836. [PMID: 31133362 DOI: 10.1016/j.tibs.2019.04.012] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Revised: 04/18/2019] [Accepted: 04/24/2019] [Indexed: 01/08/2023]
Abstract
The ability of mammalian cells to correctly identify and degrade misfolded secretory proteins, most of them bearing N-glycans, is crucial for their correct function and survival. An inefficient disposal mechanism results in the accumulation of misfolded proteins and consequent endoplasmic reticulum (ER) stress. N-glycan processing creates a code that reveals the folding status of each molecule, enabling continued folding attempts or targeting of the doomed glycoprotein for disposal. We review here the main steps involved in the accurate processing of unfolded glycoproteins. We highlight recent data suggesting that the processing is not stochastic, but that there is selective accelerated glycan trimming on misfolded glycoprotein molecules.
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Affiliation(s)
- Marina Shenkman
- School of Molecular Cell Biology and Biotechnology, George Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel
| | - Gerardo Z Lederkremer
- School of Molecular Cell Biology and Biotechnology, George Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel.
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19
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Profiling Optimal Conditions for Capturing EDEM Proteins Complexes in Melanoma Using Mass Spectrometry. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1140:155-167. [PMID: 31347047 DOI: 10.1007/978-3-030-15950-4_9] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Endoplasmic reticulum (ER) resident and secretory proteins that fail to reach their native conformation are selected for degradation through the ER-Associated Degradation (ERAD) pathway. The ER degradation-enhancing alpha-mannosidase-like proteins (EDEMs) were shown to be involved in this pathway but their precise role is still under investigation. Mass spectrometry analysis has contributed significantly to the characterization of protein complexes in the last years. The recent advancements in instrumentation, especially within resolution and speed can provide unique insights concerning the molecular architecture of protein-protein interactions in systems biology. Previous reports have suggested that several protein complexes in ERAD are sensitive to the extraction conditions. Indeed, whilst EDEM proteins can be recovered in most detergents, some of their partners are not solubilized, which further emphasizes the importance of the experimental setup. Here, we define such dynamic interactions of EDEM proteins by employing offline protein fractionation, nanoLC-MS/MS and describe how mass spectrometry can contribute to the characterization of such complexes, particularly within a disease context like melanoma.
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20
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Moon HW, Han HG, Jeon YJ. Protein Quality Control in the Endoplasmic Reticulum and Cancer. Int J Mol Sci 2018; 19:E3020. [PMID: 30282948 PMCID: PMC6213883 DOI: 10.3390/ijms19103020] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2018] [Revised: 09/22/2018] [Accepted: 10/01/2018] [Indexed: 12/21/2022] Open
Abstract
The endoplasmic reticulum (ER) is an essential compartment of the biosynthesis, folding, assembly, and trafficking of secretory and transmembrane proteins, and consequently, eukaryotic cells possess specialized machineries to ensure that the ER enables the proteins to acquire adequate folding and maturation for maintaining protein homeostasis, a process which is termed proteostasis. However, a large variety of physiological and pathological perturbations lead to the accumulation of misfolded proteins in the ER, which is referred to as ER stress. To resolve ER stress and restore proteostasis, cells have evolutionary conserved protein quality-control machineries of the ER, consisting of the unfolded protein response (UPR) of the ER, ER-associated degradation (ERAD), and autophagy. Furthermore, protein quality-control machineries of the ER play pivotal roles in the control of differentiation, progression of cell cycle, inflammation, immunity, and aging. Therefore, severe and non-resolvable ER stress is closely associated with tumor development, aggressiveness, and response to therapies for cancer. In this review, we highlight current knowledge in the molecular understanding and physiological relevance of protein quality control of the ER and discuss new insights into how protein quality control of the ER is implicated in the pathogenesis of cancer, which could contribute to therapeutic intervention in cancer.
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Affiliation(s)
- Hye Won Moon
- Department of Biochemistry, Chungnam National University College of Medicine, Daejeon 35015, Korea.
- Department of Medical Science, Chungnam National University College of Medicine, Daejeon 35015, Korea.
| | - Hye Gyeong Han
- Department of Biochemistry, Chungnam National University College of Medicine, Daejeon 35015, Korea.
- Department of Medical Science, Chungnam National University College of Medicine, Daejeon 35015, Korea.
| | - Young Joo Jeon
- Department of Biochemistry, Chungnam National University College of Medicine, Daejeon 35015, Korea.
- Department of Medical Science, Chungnam National University College of Medicine, Daejeon 35015, Korea.
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21
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Watanabe Y, Raghwani J, Allen JD, Seabright GE, Li S, Moser F, Huiskonen JT, Strecker T, Bowden TA, Crispin M. Structure of the Lassa virus glycan shield provides a model for immunological resistance. Proc Natl Acad Sci U S A 2018; 115:7320-7325. [PMID: 29941589 PMCID: PMC6048489 DOI: 10.1073/pnas.1803990115] [Citation(s) in RCA: 81] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Lassa virus is an Old World arenavirus endemic to West Africa that causes severe hemorrhagic fever. Vaccine development has focused on the envelope glycoprotein complex (GPC) that extends from the virion envelope. The often inadequate antibody immune response elicited by both vaccine and natural infection has been, in part, attributed to the abundance of N-linked glycosylation on the GPC. Here, using a virus-like-particle system that presents Lassa virus GPC in a native-like context, we determine the composite population of each of the N-linked glycosylation sites presented on the trimeric GPC spike. Our analysis reveals the presence of underprocessed oligomannose-type glycans, which form punctuated clusters that obscure the proteinous surface of both the GP1 attachment and GP2 fusion glycoprotein subunits of the Lassa virus GPC. These oligomannose clusters are seemingly derived as a result of sterically reduced accessibility to glycan processing enzymes, and limited amino acid diversification around these sites supports their role protecting against the humoral immune response. Combined, our data provide a structure-based blueprint for understanding how glycans render the glycoprotein spikes of Lassa virus and other Old World arenaviruses immunologically resistant targets.
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Affiliation(s)
- Yasunori Watanabe
- Oxford Glycobiology Institute, Department of Biochemistry, University of Oxford, OX1 3QU Oxford, United Kingdom
- Division of Structural Biology, University of Oxford, OX3 7BN Oxford, United Kingdom
- Centre for Biological Sciences and Institute of Life Sciences, University of Southampton, SO17 1BJ Southampton, United Kingdom
| | - Jayna Raghwani
- Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, Nuffield Department of Medicine, University of Oxford, OX3 7LF Oxford, United Kingdom
| | - Joel D Allen
- Centre for Biological Sciences and Institute of Life Sciences, University of Southampton, SO17 1BJ Southampton, United Kingdom
| | - Gemma E Seabright
- Oxford Glycobiology Institute, Department of Biochemistry, University of Oxford, OX1 3QU Oxford, United Kingdom
- Centre for Biological Sciences and Institute of Life Sciences, University of Southampton, SO17 1BJ Southampton, United Kingdom
| | - Sai Li
- Division of Structural Biology, University of Oxford, OX3 7BN Oxford, United Kingdom
| | - Felipe Moser
- Division of Structural Biology, University of Oxford, OX3 7BN Oxford, United Kingdom
| | - Juha T Huiskonen
- Division of Structural Biology, University of Oxford, OX3 7BN Oxford, United Kingdom
- Helsinki Institute of Life Science and Molecular and Integrative Biosciences Research Program, University of Helsinki, 00014 Helsinki, Finland
| | - Thomas Strecker
- Institute of Virology, Philipps Universität Marburg, 35043 Marburg, Germany
| | - Thomas A Bowden
- Division of Structural Biology, University of Oxford, OX3 7BN Oxford, United Kingdom;
| | - Max Crispin
- Centre for Biological Sciences and Institute of Life Sciences, University of Southampton, SO17 1BJ Southampton, United Kingdom;
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22
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Yoo YS, Han HG, Jeon YJ. Unfolded Protein Response of the Endoplasmic Reticulum in Tumor Progression and Immunogenicity. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2017; 2017:2969271. [PMID: 29430279 PMCID: PMC5752989 DOI: 10.1155/2017/2969271] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/12/2017] [Accepted: 11/29/2017] [Indexed: 12/11/2022]
Abstract
The endoplasmic reticulum (ER) is a pivotal regulator of folding, quality control, trafficking, and targeting of secreted and transmembrane proteins, and accordingly, eukaryotic cells have evolved specialized machinery to ensure that the ER enables these proteins to acquire adequate folding and maturation in the presence of intrinsic and extrinsic insults. This adaptive capacity of the ER to intrinsic and extrinsic perturbations is important for maintaining protein homeostasis, which is termed proteostasis. Failure in adaptation to these perturbations leads to accumulation of misfolded or unassembled proteins in the ER, which is termed ER stress, resulting in the activation of unfolded protein response (UPR) of the ER and the execution of ER-associated degradation (ERAD) to restore homeostasis. Furthermore, both of the two axes play key roles in the control of tumor progression, inflammation, immunity, and aging. Therefore, understanding UPR of the ER and subsequent ERAD will provide new insights into the pathogenesis of many human diseases and contribute to therapeutic intervention in these diseases.
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Affiliation(s)
- Yoon Seon Yoo
- Department of Biochemistry, Chungnam National University School of Medicine, Daejeon 35015, Republic of Korea
- Department of Medical Science, Chungnam National University School of Medicine, Daejeon 35015, Republic of Korea
| | - Hye Gyeong Han
- Department of Biochemistry, Chungnam National University School of Medicine, Daejeon 35015, Republic of Korea
- Department of Medical Science, Chungnam National University School of Medicine, Daejeon 35015, Republic of Korea
| | - Young Joo Jeon
- Department of Biochemistry, Chungnam National University School of Medicine, Daejeon 35015, Republic of Korea
- Department of Medical Science, Chungnam National University School of Medicine, Daejeon 35015, Republic of Korea
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23
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Genetic Defects Underlie the Non-syndromic Autosomal Recessive Intellectual Disability (NS-ARID). Open Life Sci 2017. [DOI: 10.1515/biol-2017-0020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
AbstractIntellectual disability (ID) is a neurodevelopmental disorder which appears frequently as the result of genetic mutations and may be syndromic (S-ID) or non-syndromic (NS-ID). ID causes an important economic burden, for patient's family, health systems, and society. Identifying genes that cause S-ID can easily be evaluated due to the clinical symptoms or physical anomalies. However, in the case of NS-ID due to the absence of co-morbid features, the latest molecular genetic techniques can be used to understand the genetic defects that underlie it. Recent studies have shown that non-syndromic autosomal recessive (NS-ARID) is extremely heterogeneous and contributes much more than X-linked ID. However, very little is known about the genes and loci involved in NS-ARID relative to X-linked ID, and whose complete genetic etiology remains obscure. In this review article, the known genetic etiology of NS-ARID and possible relationships between genes and the associated molecular pathways of their encoded proteins has been reviewed which will enhance our understanding about the underlying genes and mechanisms in NS-ARID.
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24
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Kuribara T, Hirano M, Speciale G, Williams SJ, Ito Y, Totani K. Selective Manipulation of Discrete Mannosidase Activities in the Endoplasmic Reticulum by Using Reciprocally Selective Inhibitors. Chembiochem 2017; 18:1027-1035. [DOI: 10.1002/cbic.201700081] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2017] [Indexed: 12/20/2022]
Affiliation(s)
- Taiki Kuribara
- Department of Materials and Life Science Seikei University 3-3-1 Kichijoji-kitamachi, Musashino Tokyo 180–8633 Japan
| | - Makoto Hirano
- Department of Materials and Life Science Seikei University 3-3-1 Kichijoji-kitamachi, Musashino Tokyo 180–8633 Japan
| | - Gaetano Speciale
- School of Chemistry and Bio21 Molecular Science and Biotechnology Institute University of Melbourne 30 Flemington Road Parkville VIC 3010 Australia
| | - Spencer J. Williams
- School of Chemistry and Bio21 Molecular Science and Biotechnology Institute University of Melbourne 30 Flemington Road Parkville VIC 3010 Australia
| | - Yukishige Ito
- Synthetic Cellular Chemistry Laboratory RIKEN 2-1 Hirosawa Wako Saitama 351-0198 Japan
| | - Kiichiro Totani
- Department of Materials and Life Science Seikei University 3-3-1 Kichijoji-kitamachi, Musashino Tokyo 180–8633 Japan
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25
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Totani K, Yamaya K, Hirano M, Ito Y. Influence of aglycone structures on N -glycan processing reactions in the endoplasmic reticulum. Carbohydr Res 2017; 439:16-22. [DOI: 10.1016/j.carres.2016.12.008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2016] [Revised: 12/27/2016] [Accepted: 12/28/2016] [Indexed: 10/20/2022]
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26
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Quality control of glycoprotein folding and ERAD: the role of N-glycan handling, EDEM1 and OS-9. Histochem Cell Biol 2016; 147:269-284. [DOI: 10.1007/s00418-016-1513-9] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/20/2016] [Indexed: 02/03/2023]
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27
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Frabutt DA, Zheng YH. Arms Race between Enveloped Viruses and the Host ERAD Machinery. Viruses 2016; 8:v8090255. [PMID: 27657106 PMCID: PMC5035969 DOI: 10.3390/v8090255] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2016] [Revised: 09/12/2016] [Accepted: 09/12/2016] [Indexed: 12/12/2022] Open
Abstract
Enveloped viruses represent a significant category of pathogens that cause serious diseases in animals. These viruses express envelope glycoproteins that are singularly important during the infection of host cells by mediating fusion between the viral envelope and host cell membranes. Despite low homology at protein levels, three classes of viral fusion proteins have, as of yet, been identified based on structural similarities. Their incorporation into viral particles is dependent upon their proper sub-cellular localization after being expressed and folded properly in the endoplasmic reticulum (ER). However, viral protein expression can cause stress in the ER, and host cells respond to alleviate the ER stress in the form of the unfolded protein response (UPR); the effects of which have been observed to potentiate or inhibit viral infection. One important arm of UPR is to elevate the capacity of the ER-associated protein degradation (ERAD) pathway, which is comprised of host quality control machinery that ensures proper protein folding. In this review, we provide relevant details regarding viral envelope glycoproteins, UPR, ERAD, and their interactions in host cells.
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Affiliation(s)
- Dylan A Frabutt
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI 48824, USA.
| | - Yong-Hui Zheng
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI 48824, USA.
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28
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Benyair R, Lederkremer GZ. Common fixation–permeabilization methods cause artifactual localization of a type II transmembrane protein. Microscopy (Oxf) 2016; 65:517-521. [DOI: 10.1093/jmicro/dfw035] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2016] [Accepted: 08/03/2016] [Indexed: 12/31/2022] Open
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29
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Kaneko K, Takamatsu T, Inomata T, Oikawa K, Itoh K, Hirose K, Amano M, Nishimura SI, Toyooka K, Matsuoka K, Pozueta-Romero J, Mitsui T. N-Glycomic and Microscopic Subcellular Localization Analyses of NPP1, 2 and 6 Strongly Indicate that trans-Golgi Compartments Participate in the Golgi to Plastid Traffic of Nucleotide Pyrophosphatase/Phosphodiesterases in Rice. PLANT & CELL PHYSIOLOGY 2016; 57:1610-28. [PMID: 27335351 PMCID: PMC4970613 DOI: 10.1093/pcp/pcw089] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2015] [Accepted: 04/26/2016] [Indexed: 05/02/2023]
Abstract
Nucleotide pyrophosphatase/phosphodiesterases (NPPs) are widely distributed N-glycosylated enzymes that catalyze the hydrolytic breakdown of numerous nucleotides and nucleotide sugars. In many plant species, NPPs are encoded by a small multigene family, which in rice are referred to NPP1-NPP6 Although recent investigations showed that N-glycosylated NPP1 is transported from the endoplasmic reticulum (ER)-Golgi system to the chloroplast through the secretory pathway in rice cells, information on N-glycan composition and subcellular localization of other NPPs is still lacking. Computer-assisted analyses of the amino acid sequences deduced from different Oryza sativa NPP-encoding cDNAs predicted all NPPs to be secretory glycoproteins. Confocal fluorescence microscopy observation of cells expressing NPP2 and NPP6 fused with green fluorescent protein (GFP) revealed that NPP2 and NPP6 are plastidial proteins. Plastid targeting of NPP2-GFP and NPP6-GFP was prevented by brefeldin A and by the expression of ARF1(Q71L), a dominant negative mutant of ADP-ribosylation factor 1 that arrests the ER to Golgi traffic, indicating that NPP2 and NPP6 are transported from the ER-Golgi to the plastidial compartment. Confocal laser scanning microscopy and high-pressure frozen/freeze-substituted electron microscopy analyses of transgenic rice cells ectopically expressing the trans-Golgi marker sialyltransferase fused with GFP showed the occurrence of contact of Golgi-derived membrane vesicles with cargo and subsequent absorption into plastids. Sensitive and high-throughput glycoblotting/mass spectrometric analyses showed that complex-type and paucimannosidic-type glycans with fucose and xylose residues occupy approximately 80% of total glycans of NPP1, NPP2 and NPP6. The overall data strongly indicate that the trans-Golgi compartments participate in the Golgi to plastid trafficking and targeting mechanism of NPPs.
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Affiliation(s)
- Kentaro Kaneko
- Graduate School of Science and Technology, Niigata University, 2-8050 Ikarashi, Niigata, 950-2181 Japan
| | - Takeshi Takamatsu
- Graduate School of Science and Technology, Niigata University, 2-8050 Ikarashi, Niigata, 950-2181 Japan Department of Applied Biological Chemistry, Niigata University, 2-8050 Ikarashi, Niigata, 950-2181 Japan
| | - Takuya Inomata
- Graduate School of Science and Technology, Niigata University, 2-8050 Ikarashi, Niigata, 950-2181 Japan
| | - Kazusato Oikawa
- Department of Applied Biological Chemistry, Niigata University, 2-8050 Ikarashi, Niigata, 950-2181 Japan
| | - Kimiko Itoh
- Graduate School of Science and Technology, Niigata University, 2-8050 Ikarashi, Niigata, 950-2181 Japan Department of Applied Biological Chemistry, Niigata University, 2-8050 Ikarashi, Niigata, 950-2181 Japan
| | - Kazuko Hirose
- Graduate School of Advanced Life Science, Frontier Research Center for Post-genomic Science and Technology, Hokkaido University, Sapporo, 001-0021 Japan
| | - Maho Amano
- Graduate School of Advanced Life Science, Frontier Research Center for Post-genomic Science and Technology, Hokkaido University, Sapporo, 001-0021 Japan
| | - Shin-Ichiro Nishimura
- Graduate School of Advanced Life Science, Frontier Research Center for Post-genomic Science and Technology, Hokkaido University, Sapporo, 001-0021 Japan
| | - Kiminori Toyooka
- RIKEN Center for Sustainable Resource Science, Kanagawa, 230-0045 Japan
| | - Ken Matsuoka
- Laboratory of Plant Nutrition, Faculty of Agriculture, Kyushu University, Fukuoka, 812-8581 Japan
| | - Javier Pozueta-Romero
- Instituto de Agrobiotecnología (CSIC, UPNA, Gobierno de Navarra), Mutiloako etorbidea zenbaki gabe, 31192 Mutiloabeti, Nafarroa, Spain
| | - Toshiaki Mitsui
- Graduate School of Science and Technology, Niigata University, 2-8050 Ikarashi, Niigata, 950-2181 Japan Department of Applied Biological Chemistry, Niigata University, 2-8050 Ikarashi, Niigata, 950-2181 Japan
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30
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Zhou T, Frabutt DA, Moremen KW, Zheng YH. ERManI (Endoplasmic Reticulum Class I α-Mannosidase) Is Required for HIV-1 Envelope Glycoprotein Degradation via Endoplasmic Reticulum-associated Protein Degradation Pathway. J Biol Chem 2015. [PMID: 26205822 DOI: 10.1074/jbc.m115.675207] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Previously, we reported that the mitochondrial translocator protein (TSPO) induces HIV-1 envelope (Env) degradation via the endoplasmic reticulum (ER)-associated protein degradation (ERAD) pathway, but the mechanism was not clear. Here we investigated how the four ER-associated glycoside hydrolase family 47 (GH47) α-mannosidases, ERManI, and ER-degradation enhancing α-mannosidase-like (EDEM) proteins 1, 2, and 3, are involved in the Env degradation process. Ectopic expression of these four α-mannosidases uncovers that only ERManI inhibits HIV-1 Env expression in a dose-dependent manner. In addition, genetic knock-out of the ERManI gene MAN1B1 using CRISPR/Cas9 technology disrupts the TSPO-mediated Env degradation. Biochemical studies show that HIV-1 Env interacts with ERManI, and between the ERManI cytoplasmic, transmembrane, lumenal stem, and lumenal catalytic domains, the catalytic domain plays a critical role in the Env-ERManI interaction. In addition, functional studies show that inactivation of the catalytic sites by site-directed mutagenesis disrupts the ERManI activity. These studies identify ERManI as a critical GH47 α-mannosidase in the ER-associated protein degradation pathway that initiates the Env degradation and suggests that its catalytic domain and enzymatic activity play an important role in this process.
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Affiliation(s)
- Tao Zhou
- From the Harbin Veterinary Research Institute, CAAS-Michigan State University Joint Laboratory of Innate Immunity, State Key Laboratory of Veterinary Biotechnology, Chinese Academy of Agricultural Sciences, Harbin, 150001, China, BEACON Center for the Study of Evolution in Action and Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan 48824
| | - Dylan A Frabutt
- BEACON Center for the Study of Evolution in Action and Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan 48824
| | - Kelley W Moremen
- Complex Carbohydrate Research Center, University of Georgia, Athens, Georgia 30602, and
| | - Yong-Hui Zheng
- From the Harbin Veterinary Research Institute, CAAS-Michigan State University Joint Laboratory of Innate Immunity, State Key Laboratory of Veterinary Biotechnology, Chinese Academy of Agricultural Sciences, Harbin, 150001, China, BEACON Center for the Study of Evolution in Action and Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan 48824
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31
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Słomińska-Wojewódzka M, Sandvig K. The Role of Lectin-Carbohydrate Interactions in the Regulation of ER-Associated Protein Degradation. Molecules 2015; 20:9816-46. [PMID: 26023941 PMCID: PMC6272441 DOI: 10.3390/molecules20069816] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2015] [Revised: 05/20/2015] [Accepted: 05/21/2015] [Indexed: 01/08/2023] Open
Abstract
Proteins entering the secretory pathway are translocated across the endoplasmic reticulum (ER) membrane in an unfolded form. In the ER they are restricted to a quality control system that ensures correct folding or eventual degradation of improperly folded polypeptides. Mannose trimming of N-glycans on newly synthesized proteins plays an important role in the recognition and sorting of terminally misfolded glycoproteins for ER-associated protein degradation (ERAD). In this process misfolded proteins are retrotranslocated into the cytosol, polyubiquitinated, and eventually degraded by the proteasome. The mechanism by which misfolded glycoproteins are recognized and recruited to the degradation machinery has been extensively studied during last decade. In this review, we focus on ER degradation-enhancing α-mannosidase-like protein (EDEM) family proteins that seem to play a key role in the discrimination between proteins undergoing a folding process and terminally misfolded proteins directed for degradation. We describe interactions of EDEM proteins with other components of the ERAD machinery, as well as with various protein substrates. Carbohydrate-dependent interactions together with N-glycan-independent interactions seem to regulate the complex process of protein recognition and direction for proteosomal degradation.
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Affiliation(s)
| | - Kirsten Sandvig
- Department of Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital, The Norwegian Radium Hospital, 0379 Oslo, Norway.
- Centre for Cancer Biomedicine, Faculty of Medicine, University of Oslo, 0379 Oslo, Norway.
- Department of Biosciences, University of Oslo, 0316 Oslo, Norway.
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Benyair R, Ogen-Shtern N, Lederkremer GZ. Glycan regulation of ER-associated degradation through compartmentalization. Semin Cell Dev Biol 2015; 41:99-109. [DOI: 10.1016/j.semcdb.2014.11.006] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2014] [Revised: 11/13/2014] [Accepted: 11/14/2014] [Indexed: 12/20/2022]
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Ferris SP, Kodali VK, Kaufman RJ. Glycoprotein folding and quality-control mechanisms in protein-folding diseases. Dis Model Mech 2015; 7:331-41. [PMID: 24609034 PMCID: PMC3944493 DOI: 10.1242/dmm.014589] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Biosynthesis of proteins – from translation to folding to export – encompasses a complex set of events that are exquisitely regulated and scrutinized to ensure the functional quality of the end products. Cells have evolved to capitalize on multiple post-translational modifications in addition to primary structure to indicate the folding status of nascent polypeptides to the chaperones and other proteins that assist in their folding and export. These modifications can also, in the case of irreversibly misfolded candidates, signal the need for dislocation and degradation. The current Review focuses on the glycoprotein quality-control (GQC) system that utilizes protein N-glycosylation and N-glycan trimming to direct nascent glycopolypeptides through the folding, export and dislocation pathways in the endoplasmic reticulum (ER). A diverse set of pathological conditions rooted in defective as well as over-vigilant ER quality-control systems have been identified, underlining its importance in human health and disease. We describe the GQC pathways and highlight disease and animal models that have been instrumental in clarifying our current understanding of these processes.
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Affiliation(s)
- Sean P Ferris
- Department of Biological Chemistry and Medical Scientist Training Program, University of Michigan, Ann Arbor, MI 48109, USA
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Benyair R, Ogen-Shtern N, Mazkereth N, Shai B, Ehrlich M, Lederkremer GZ. Mammalian ER mannosidase I resides in quality control vesicles, where it encounters its glycoprotein substrates. Mol Biol Cell 2014; 26:172-84. [PMID: 25411339 PMCID: PMC4294666 DOI: 10.1091/mbc.e14-06-1152] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
ER mannosidase I (ERManI) was found recently in the Golgi. This result is found to arise artificially from membrane disturbance in immunofluorescence methods. ERManI is located in novel vesicles to which substrates traffic and that converge at the ER-derived quality control compartment under ER stress. Endoplasmic reticulum α1,2 mannosidase I (ERManI), a central component of ER quality control and ER-associated degradation (ERAD), acts as a timer enzyme, modifying N-linked sugar chains of glycoproteins with time. This process halts glycoprotein folding attempts when necessary and targets terminally misfolded glycoproteins to ERAD. Despite the importance of ERManI in maintenance of glycoprotein quality control, fundamental questions regarding this enzyme remain controversial. One such question is the subcellular localization of ERManI, which has been suggested to localize to the ER membrane, the ER-derived quality control compartment (ERQC), and, surprisingly, recently to the Golgi apparatus. To try to clarify this controversy, we applied a series of approaches that indicate that ERManI is located, at the steady state, in quality control vesicles (QCVs) to which ERAD substrates are transported and in which they interact with the enzyme. Both endogenous and exogenously expressed ERManI migrate at an ER-like density on iodixanol gradients, suggesting that the QCVs are derived from the ER. The QCVs are highly mobile, displaying dynamics that are dependent on microtubules and COP-II but not on COP-I vesicle machinery. Under ER stress conditions, the QCVs converge in a juxtanuclear region, at the ERQC, as previously reported. Our results also suggest that ERManI is turned over by an active autophagic process. Of importance, we found that membrane disturbance, as is common in immunofluorescence methods, leads to an artificial appearance of ERManI in a Golgi pattern.
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Affiliation(s)
- Ron Benyair
- Department of Cell Research and Immunology, George Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel
| | - Navit Ogen-Shtern
- Department of Cell Research and Immunology, George Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel
| | - Niv Mazkereth
- Department of Cell Research and Immunology, George Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel
| | - Ben Shai
- Department of Cell Research and Immunology, George Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel
| | - Marcelo Ehrlich
- Department of Cell Research and Immunology, George Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel
| | - Gerardo Z Lederkremer
- Department of Cell Research and Immunology, George Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel
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Ninagawa S, Okada T, Sumitomo Y, Kamiya Y, Kato K, Horimoto S, Ishikawa T, Takeda S, Sakuma T, Yamamoto T, Mori K. EDEM2 initiates mammalian glycoprotein ERAD by catalyzing the first mannose trimming step. ACTA ACUST UNITED AC 2014; 206:347-56. [PMID: 25092655 PMCID: PMC4121980 DOI: 10.1083/jcb.201404075] [Citation(s) in RCA: 108] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
All three mammalian EDEM family members possess mannosidase activity and are necessary for glycoprotein degradation, but EDEM2 performs a unique, rate-limiting, first mannose trimming step upstream of EDEM1 and EDEM3. Glycoproteins misfolded in the endoplasmic reticulum (ER) are subjected to ER-associated glycoprotein degradation (gpERAD) in which Htm1-mediated mannose trimming from the oligosaccharide Man8GlcNAc2 to Man7GlcNAc2 is the rate-limiting step in yeast. In contrast, the roles of the three Htm1 homologues (EDEM1/2/3) in mammalian gpERAD have remained elusive, with a key controversy being whether EDEMs function as mannosidases or as lectins. We therefore conducted transcription activator-like effector nuclease–mediated gene knockout analysis in human cell line and found that all endogenous EDEMs possess mannosidase activity. Mannose trimming from Man8GlcNAc2 to Man7GlcNAc2 is performed mainly by EDEM3 and to a lesser extent by EDEM1. Most surprisingly, the upstream mannose trimming from Man9GlcNAc2 to Man8GlcNAc2 is conducted mainly by EDEM2, which was previously considered to lack enzymatic activity. Based on the presence of two rate-limiting steps in mammalian gpERAD, we propose that mammalian cells double check gpERAD substrates before destruction by evolving EDEM2, a novel-type Htm1 homologue that catalyzes the first mannose trimming step from Man9GlcNAc2.
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Affiliation(s)
- Satoshi Ninagawa
- Department of Biophysics, Graduate School of Science, and Department of Radiation Genetics, Graduate School of Medicine, Kyoto University, Kyoto 606-8502, Japan Institute for Molecular Science and Okazaki Institute for Integrative Bioscience, National Institutes of Natural Sciences, Okazaki 444-8787, Japan
| | - Tetsuya Okada
- Department of Biophysics, Graduate School of Science, and Department of Radiation Genetics, Graduate School of Medicine, Kyoto University, Kyoto 606-8502, Japan
| | - Yoshiki Sumitomo
- Department of Biophysics, Graduate School of Science, and Department of Radiation Genetics, Graduate School of Medicine, Kyoto University, Kyoto 606-8502, Japan
| | - Yukiko Kamiya
- Institute for Molecular Science and Okazaki Institute for Integrative Bioscience, National Institutes of Natural Sciences, Okazaki 444-8787, Japan
| | - Koichi Kato
- Institute for Molecular Science and Okazaki Institute for Integrative Bioscience, National Institutes of Natural Sciences, Okazaki 444-8787, Japan Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya 467-8603, Japan
| | - Satoshi Horimoto
- Department of Biophysics, Graduate School of Science, and Department of Radiation Genetics, Graduate School of Medicine, Kyoto University, Kyoto 606-8502, Japan
| | - Tokiro Ishikawa
- Department of Biophysics, Graduate School of Science, and Department of Radiation Genetics, Graduate School of Medicine, Kyoto University, Kyoto 606-8502, Japan
| | - Shunichi Takeda
- Department of Biophysics, Graduate School of Science, and Department of Radiation Genetics, Graduate School of Medicine, Kyoto University, Kyoto 606-8502, Japan
| | - Tetsushi Sakuma
- Department of Mathematical and Life Sciences, Graduate School of Science, Hiroshima University, Hiroshima 739-8526, Japan
| | - Takashi Yamamoto
- Department of Mathematical and Life Sciences, Graduate School of Science, Hiroshima University, Hiroshima 739-8526, Japan
| | - Kazutoshi Mori
- Department of Biophysics, Graduate School of Science, and Department of Radiation Genetics, Graduate School of Medicine, Kyoto University, Kyoto 606-8502, Japan
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Iannotti MJ, Figard L, Sokac AM, Sifers RN. A Golgi-localized mannosidase (MAN1B1) plays a non-enzymatic gatekeeper role in protein biosynthetic quality control. J Biol Chem 2014; 289:11844-11858. [PMID: 24627495 DOI: 10.1074/jbc.m114.552091] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Conformation-based disorders are manifested at the level of protein structure, necessitating an accurate understanding of how misfolded proteins are processed by the cellular proteostasis network. Asparagine-linked glycosylation plays important roles for protein quality control within the secretory pathway. The suspected role for the MAN1B1 gene product MAN1B1, also known as ER mannosidase I, is to function within the ER similar to the yeast ortholog Mns1p, which removes a terminal mannose unit to initiate a glycan-based ER-associated degradation (ERAD) signal. However, we recently discovered that MAN1B1 localizes to the Golgi complex in human cells and uncovered its participation in ERAD substrate retention, retrieval to the ER, and subsequent degradation from this organelle. The objective of the current study was to further characterize the contribution of MAN1B1 as part of a Golgi-based quality control network. Multiple lines of experimental evidence support a model in which neither the mannosidase activity nor catalytic domain is essential for the retention or degradation of the misfolded ERAD substrate Null Hong Kong. Instead, a highly conserved, vertebrate-specific non-enzymatic decapeptide sequence in the luminal stem domain plays a significant role in controlling the fate of overexpressed Null Hong Kong. Together, these findings define a new functional paradigm in which Golgi-localized MAN1B1 can play a mannosidase-independent gatekeeper role in the proteostasis network of higher eukaryotes.
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Affiliation(s)
- Michael J Iannotti
- Interdepartmental Program in Cell and Molecular Biology, Baylor College of Medicine, Houston, Texas 77030; Department of Pathology and Immunology, Baylor College of Medicine, Houston, Texas 77030
| | - Lauren Figard
- Interdepartmental Program in Cell and Molecular Biology, Baylor College of Medicine, Houston, Texas 77030; Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas 77030
| | - Anna M Sokac
- Interdepartmental Program in Cell and Molecular Biology, Baylor College of Medicine, Houston, Texas 77030; Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas 77030
| | - Richard N Sifers
- Interdepartmental Program in Cell and Molecular Biology, Baylor College of Medicine, Houston, Texas 77030; Department of Pathology and Immunology, Baylor College of Medicine, Houston, Texas 77030; Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, Texas 77030; Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas 77030.
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Rymen D, Peanne R, Millón MB, Race V, Sturiale L, Garozzo D, Mills P, Clayton P, Asteggiano CG, Quelhas D, Cansu A, Martins E, Nassogne MC, Gonçalves-Rocha M, Topaloglu H, Jaeken J, Foulquier F, Matthijs G. MAN1B1 deficiency: an unexpected CDG-II. PLoS Genet 2013; 9:e1003989. [PMID: 24348268 PMCID: PMC3861123 DOI: 10.1371/journal.pgen.1003989] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2013] [Accepted: 10/09/2013] [Indexed: 11/18/2022] Open
Abstract
Congenital disorders of glycosylation (CDG) are a group of rare metabolic diseases, due to impaired protein and lipid glycosylation. In the present study, exome sequencing was used to identify MAN1B1 as the culprit gene in an unsolved CDG-II patient. Subsequently, 6 additional cases with MAN1B1-CDG were found. All individuals presented slight facial dysmorphism, psychomotor retardation and truncal obesity. Generally, MAN1B1 is believed to be an ER resident alpha-1,2-mannosidase acting as a key factor in glycoprotein quality control by targeting misfolded proteins for ER-associated degradation (ERAD). However, recent studies indicated a Golgi localization of the endogenous MAN1B1, suggesting a more complex role for MAN1B1 in quality control. We were able to confirm that MAN1B1 is indeed localized to the Golgi complex instead of the ER. Furthermore, we observed an altered Golgi morphology in all patients' cells, with marked dilatation and fragmentation. We hypothesize that part of the phenotype is associated to this Golgi disruption. In conclusion, we linked mutations in MAN1B1 to a Golgi glycosylation disorder. Additionally, our results support the recent findings on MAN1B1 localization. However, more work is needed to pinpoint the exact function of MAN1B1 in glycoprotein quality control, and to understand the pathophysiology of its deficiency. Glycosylation concerns the synthesis of sugar chains, their addition onto proteins and/or lipids, and their subsequent modifications. The resulting glycoproteins serve many critical roles in metabolism. The importance of this pathway is illustrated by a group of diseases called Congenital Disorders of Glycosylation (CDG). To date, over 60 distinct disorders have been described. In the present study, we demonstrated that mutations in MAN1B1, a gene formerly linked to non-syndromic intellectual disability, cause CDG. We described 7 patients with similar clinical features (developmental delay, intellectual disability, facial dysmorphism and obesity), defining MAN1B1-CDG as a syndrome. Furthermore, we confirmed that the MAN1B1 protein is localized into the Golgi apparatus instead of the endoplasmic reticulum, where it was assumed to reside for many years. Moreover, we showed that mutations in MAN1B1 lead to alterations of the Golgi structure.
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Affiliation(s)
- Daisy Rymen
- Center for Human Genetics, University of Leuven, Leuven, Belgium
- Center for Metabolic Diseases, University Hospital Gasthuisberg, Leuven, Belgium
| | - Romain Peanne
- Center for Human Genetics, University of Leuven, Leuven, Belgium
| | - María B. Millón
- Centro de Estudio Metabalopatías Congénitas, Faculdad de Ciencias Médicas, Universidad Nacional de Córdoba, Hospital de Niños de la Santísima Trinidad, Córdoba, Argentina
| | - Valérie Race
- Center for Human Genetics, University of Leuven, Leuven, Belgium
| | - Luisa Sturiale
- Institute of Chemistry and Technology of Polymers, CNR, Catania, Italy
| | - Domenico Garozzo
- Institute of Chemistry and Technology of Polymers, CNR, Catania, Italy
| | - Philippa Mills
- Clinical & Molecular Genetics Unit, Institute of Child Health, University College and Great Ormond Street Hospital for Children NHS Trust, London, United Kingdom
| | - Peter Clayton
- Clinical & Molecular Genetics Unit, Institute of Child Health, University College and Great Ormond Street Hospital for Children NHS Trust, London, United Kingdom
| | - Carla G. Asteggiano
- Centro de Estudio Metabalopatías Congénitas, Faculdad de Ciencias Médicas, Universidad Nacional de Córdoba, Hospital de Niños de la Santísima Trinidad, Córdoba, Argentina
| | - Dulce Quelhas
- Unidade de Genética Médica, Departamento de Genética Humana, Centro de Genética Médica - Dr. Jacinto Magalhães - INSA, IP. Porto, Portugal
| | - Ali Cansu
- Gazi University Faculty of Medicine, Department of Paediatric Neurology, Besevler/Ankara, Turkey
| | - Esmeralda Martins
- Unidade de Doenças Metabólicas, Hospital de Crianças Maria Pia, Porto, Portugal
| | - Marie-Cécile Nassogne
- Université Catholique de Louvain, Cliniques Universitaires Saint-Luc, Brussels, Belgium
| | - Miguel Gonçalves-Rocha
- Unidade de Genética Médica, Departamento de Genética Humana, Centro de Genética Médica - Dr. Jacinto Magalhães - INSA, IP. Porto, Portugal
| | - Haluk Topaloglu
- Department of Child Neurology, Hacettepe University Children's Hospital, Ankara, Turkey
| | - Jaak Jaeken
- Center for Metabolic Diseases, University Hospital Gasthuisberg, Leuven, Belgium
| | - François Foulquier
- Structural and Functional Glycobiology Unit, UMR CNRS/USTL 8576, IFR 147, University of Lille 1, Villeneuve d'Ascq, France
| | - Gert Matthijs
- Center for Human Genetics, University of Leuven, Leuven, Belgium
- * E-mail:
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Horimoto S, Ninagawa S, Okada T, Koba H, Sugimoto T, Kamiya Y, Kato K, Takeda S, Mori K. The unfolded protein response transducer ATF6 represents a novel transmembrane-type endoplasmic reticulum-associated degradation substrate requiring both mannose trimming and SEL1L protein. J Biol Chem 2013; 288:31517-27. [PMID: 24043630 DOI: 10.1074/jbc.m113.476010] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Proteins misfolded in the endoplasmic reticulum (ER) are cleared by the ubiquitin-dependent proteasome system in the cytosol, a series of events collectively termed ER-associated degradation (ERAD). It was previously shown that SEL1L, a partner protein of the E3 ubiquitin ligase HRD1, is required for degradation of misfolded luminal proteins (ERAD-Ls substrates) but not misfolded transmembrane proteins (ERAD-Lm substrates) in both mammalian and chicken DT40 cells. Here, we analyzed ATF6, a type II transmembrane glycoprotein that serves as a sensor/transducer of the unfolded protein response, as a potential ERAD-Lm substrate in DT40 cells. Unexpectedly, degradation of endogenous ATF6 and exogenously expressed chicken and human ATF6 by the proteasome required SEL1L. Deletion analysis revealed that the luminal region of ATF6 is a determinant for SEL1L-dependent degradation. Chimeric analysis showed that the luminal region of ATF6 confers SEL1L dependence on type I transmembrane protein as well. In contrast, degradation of other known type I ERAD-Lm substrates (BACE457, T-cell receptor-α, CD3-δ, and CD147) did not require SEL1L. Thus, ATF6 represents a novel type of ERAD-Lm substrate requiring SEL1L for degradation despite its transmembrane nature. In addition, endogenous ATF6 was markedly stabilized in wild-type cells treated with kifunensine, an inhibitor of α1,2-mannosidase in the ER, indicating that degradation of ATF6 requires proper mannose trimming. Our further analyses revealed that the five ERAD-Lm substrates examined are classified into three subgroups based on their dependence on mannose trimming and SEL1L. Thus, ERAD-Lm substrates are degraded through much more diversified mechanisms in higher eukaryotes than previously thought.
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Affiliation(s)
- Satoshi Horimoto
- From the Department of Biophysics, Graduate School of Science, Kyoto University, Kyoto 606-8502
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Olzmann JA, Kopito RR, Christianson JC. The mammalian endoplasmic reticulum-associated degradation system. Cold Spring Harb Perspect Biol 2013; 5:cshperspect.a013185. [PMID: 23232094 DOI: 10.1101/cshperspect.a013185] [Citation(s) in RCA: 250] [Impact Index Per Article: 22.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The endoplasmic reticulum (ER) is the site of synthesis for nearly one-third of the eukaryotic proteome and is accordingly endowed with specialized machinery to ensure that proteins deployed to the distal secretory pathway are correctly folded and assembled into native oligomeric complexes. Proteins failing to meet this conformational standard are degraded by ER-associated degradation (ERAD), a complex process through which folding-defective proteins are selected and ultimately degraded by the ubiquitin-proteasome system. ERAD proceeds through four tightly coupled steps involving substrate selection, dislocation across the ER membrane, covalent conjugation with polyubiquitin, and proteasomal degradation. The ERAD machinery shows a modular organization with central ER membrane-embedded ubiquitin ligases linking components responsible for recognition in the ER lumen to the ubiquitin-proteasome system in the cytoplasm. The core ERAD machinery is highly conserved among eukaryotes and much of our basic understanding of ERAD organization has been derived from genetic and biochemical studies of yeast. In this article we discuss how the core ERAD machinery is organized in mammalian cells.
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Affiliation(s)
- James A Olzmann
- Department of Biology, Stanford University, Stanford, California 94305, USA
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Pan S, Cheng X, Sifers RN. Golgi-situated endoplasmic reticulum α-1, 2-mannosidase contributes to the retrieval of ERAD substrates through a direct interaction with γ-COP. Mol Biol Cell 2013; 24:1111-21. [PMID: 23427261 PMCID: PMC3623633 DOI: 10.1091/mbc.e12-12-0886] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Abstract
Endoplasmic reticulum (ER) α-1, 2-mannosidase and γ-COP contribute to a Golgi-based quality control module that facilitates the retrieval of captured ER-associated protein degradation substrates back to the ER. Endoplasmic reticulum (ER) α-1, 2-mannosidase (ERManI) contributes to ER-associated protein degradation (ERAD) by initiating the formation of degradation signals on misfolded N-linked glycoproteins. Despite its inferred intracellular location, we recently discovered that the mammalian homologue is actually localized to the Golgi complex. In the present study, the functional role of Golgi-situated ERManI was investigated. Mass spectrometry analysis and coimmunoprecipitation (co-IP) identified a direct interaction between ERManI and γ-COP, the gamma subunit of coat protein complex I (COPI) that is responsible for Golgi-to-ER retrograde cargo transport. The functional relationship was validated by the requirement of both ERManI and γ-COP to support efficient intracellular clearance of the classical ERAD substrate, null Hong Kong (NHK). In addition, site-directed mutagenesis of suspected γ-COP–binding motifs in the cytoplasmic tail of ERManI was sufficient to disrupt the physical interaction and ablate NHK degradation. Moreover, a physical interaction between NHK, ERManI, and γ-COP was identified by co-IP and Western blotting. RNA interference–mediated knockdown of γ-COP enhanced the association between ERManI and NHK, while diminishing the efficiency of ERAD. Based on these findings, a model is proposed in which ERManI and γ-COP contribute to a Golgi-based quality control module that facilitates the retrieval of captured ERAD substrates back to the ER.
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Affiliation(s)
- Shujuan Pan
- Department of Pathology, Baylor College of Medicine, Houston, TX 77030, USA
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41
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Carvalho ND, Jørgensen TR, Arentshorst M, Nitsche BM, van den Hondel CA, Archer DB, Ram AF. Genome-wide expression analysis upon constitutive activation of the HacA bZIP transcription factor in Aspergillus niger reveals a coordinated cellular response to counteract ER stress. BMC Genomics 2012; 13:350. [PMID: 22846479 PMCID: PMC3472299 DOI: 10.1186/1471-2164-13-350] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2012] [Accepted: 07/09/2012] [Indexed: 01/07/2023] Open
Abstract
Background HacA/Xbp1 is a conserved bZIP transcription factor in eukaryotic cells which regulates gene expression in response to various forms of secretion stress and as part of secretory cell differentiation. In the present study, we replaced the endogenous hacA gene of an Aspergillus niger strain with a gene encoding a constitutively active form of the HacA transcription factor (HacACA). The impact of constitutive HacA activity during exponential growth was explored in bioreactor controlled cultures using transcriptomic analysis to identify affected genes and processes. Results Transcription profiles for the wild-type strain (HacAWT) and the HacACA strain were obtained using Affymetrix GeneChip analysis of three replicate batch cultures of each strain. In addition to the well known HacA targets such as the ER resident foldases and chaperones, GO enrichment analysis revealed up-regulation of genes involved in protein glycosylation, phospholipid biosynthesis, intracellular protein transport, exocytosis and protein complex assembly in the HacACA mutant. Biological processes over-represented in the down-regulated genes include those belonging to central metabolic pathways, translation and transcription. A remarkable transcriptional response in the HacACA strain was the down-regulation of the AmyR transcription factor and its target genes. Conclusions The results indicate that the constitutive activation of the HacA leads to a coordinated regulation of the folding and secretion capacity of the cell, but with consequences on growth and fungal physiology to reduce secretion stress.
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Affiliation(s)
- Neuza Dsp Carvalho
- Institute of Biology Leiden, Leiden University, Molecular Microbiology and Biotechnology, BE Leiden, The Netherlands
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42
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Wilson IBH. The class I α1,2-mannosidases of Caenorhabditis elegans. Glycoconj J 2012; 29:173-9. [PMID: 22535467 DOI: 10.1007/s10719-012-9378-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2012] [Revised: 04/07/2012] [Accepted: 04/10/2012] [Indexed: 11/26/2022]
Abstract
During the biosynthesis of N-glycans in multicellular eukaryotes, glycans with the compositions Man(5)GlcNAc(2-3) are key intermediates. However, to reach this 'decision point', these N-glycans are first processed from Glc(3)Man(9)GlcNAc(2) through to Man(5)GlcNAc(2) by a number of glycosidases, whereby up to four α1-2-linked mannose residues are removed by class I mannosidases (glycohydrolase family 47). Whereas in the yeast Saccharomyces cerevisiae there are maximally three members of this protein family, in higher organisms there are multiple class I mannosidases residing in the endoplasmic reticulum and Golgi apparatus. The genome of the model nematode Caenorhabditis elegans encodes seven members of this protein family, whereby four are predicted to be classical processing mannosidases and three are related proteins with roles in quality control. In this study, cDNAs encoding the four predicted mannosidases were cloned and expressed in Pichia pastoris and the activity of these enzymes, designated MANS-1, MANS-2, MANS-3 and MANS-4, was verified. The first two can, dependent on the incubation time, remove three to four residues from Man(9)GlcNAc(2), whereas the action of the other two results in the appearance of the B isomer of Man(8)GlcNAc(2); together the complementary activities of these enzymes result in processing to Man(5)GlcNAc(2). With these data, another gap is closed in our understanding of the N-glycan biosynthesis pathway of the nematode worm.
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Affiliation(s)
- Iain B H Wilson
- Department für Chemie, Universität für Bodenkultur, Muthgasse 18, 1190, Wien, Austria.
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Kamiya Y, Satoh T, Kato K. Molecular and structural basis for N-glycan-dependent determination of glycoprotein fates in cells. Biochim Biophys Acta Gen Subj 2012; 1820:1327-37. [PMID: 22240168 DOI: 10.1016/j.bbagen.2011.12.017] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2011] [Revised: 12/27/2011] [Accepted: 12/27/2011] [Indexed: 11/18/2022]
Abstract
BACKGROUND N-linked oligosaccharides operate as tags for protein quality control, consigning glycoproteins to different fates, i.e. folding in the endoplasmic reticulum (ER), vesicular transport between the ER and the Golgi complex, and ER-associated degradation of glycoproteins, by interacting with a panel of intracellular lectins in the early secretory pathway. SCOPE OF REVIEW This review summarizes the current state of knowledge regarding the molecular and structural basis for glycoprotein-fate determination in cells that is achieved through the actions of the intracellular lectins and its partner proteins. MAJOR CONCLUSIONS Cumulative frontal affinity chromatography (FAC) data demonstrated that the intracellular lectins exhibit distinct sugar-binding specificity profiles. The glycotopes recognized by these lectins as fate determinants are embedded in the triantennary structures of the high-mannose-type oligosaccharides and are exposed upon trimming of the outer glucose and mannose residues during the N-glycan processing pathway. Furthermore, recently emerged 3D structural data offer mechanistic insights into functional interplay between an intracellular lectin and its binding partner in the early secretory pathway. GENERAL SIGNIFICANCE Structural biology approaches in conjunction with FAC methods provide atomic pictures of the mechanisms behind the glycoprotein-fate determination in cells. This article is a part of a Special issue entitled: Glycoproteomics.
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Affiliation(s)
- Yukiko Kamiya
- Okazaki Institute for Integrative Bioscience and Institute for Molecular Science, National Institutes of Natural Sciences, 5-1 Higashiyama, Myodaiji, Okazaki, Aichi 444-8787, Japan
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Singh M, Chaudhry P, Parent S, Asselin E. Ubiquitin-proteasomal degradation of COX-2 in TGF-β stimulated human endometrial cells is mediated through endoplasmic reticulum mannosidase I. Endocrinology 2012; 153:426-37. [PMID: 22109885 DOI: 10.1210/en.2011-1438] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Cyclooxygenase (COX)-2 is a key regulatory enzyme in the production of prostaglandins (PG) during various physiological processes. Mechanisms of COX-2 regulation in human endometrial stromal cells (human endometrial stromal cells) are not fully understood. In this study, we investigate the role of TGF-β in the regulation of COX-2 in human uterine stromal cells. Each TGF-β isoform decreases COX-2 protein level in human uterine stromal cells in Smad2/3-dependent manner. The decrease in COX-2 is accompanied by a decrease in PG synthesis. Knockdown of Smad4 using specific small interfering RNA prevents the decrease in COX-2 protein, confirming that Smad pathway is implicated in the regulation of COX-2 expression in human endometrial stromal cells. Pretreatment with 26S proteasome inhibitor, MG132, significantly restores COX-2 protein and PG synthesis, indicating that COX-2 undergoes proteasomal degradation in the presence of TGF-β. In addition, each TGF-β isoform up-regulates endoplasmic reticulum (ER)-mannosidase I (ERManI) implying that COX-2 degradation is mediated through ER-associated degradation pathway in these cells. Furthermore, inhibition of ERManI activity using the mannosidase inhibitor (kifunensine), or small interfering RNA-mediated knockdown of ERManI, prevents TGF-β-induced COX-2 degradation. Taken together, these studies suggest that TGF-β promotes COX-2 degradation in a Smad-dependent manner by up-regulating the expression of ERManI and thereby enhancing ER-associated degradation and proteasomal degradation pathways.
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Affiliation(s)
- Mohan Singh
- Department of Chemistry-Biology, University of Québec at Trois-Rivières, 3351 Boulevard des Forges, Trois-Rivières, Québec, Canada
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Lack of endoplasmic reticulum 1,2-α-mannosidase activity that trims N-glycan Man9GlcNAc2 to Man8GlcNAc2 isomer B in a manE gene disruptant of Aspergillus oryzae. J Biosci Bioeng 2011; 113:438-41. [PMID: 22169093 DOI: 10.1016/j.jbiosc.2011.11.015] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2011] [Revised: 11/04/2011] [Accepted: 11/14/2011] [Indexed: 11/22/2022]
Abstract
The gene manE, encoding a probable class I endoplasmic reticulum 1,2-α-mannosidases (ER-Man), was identified from the filamentous fungus Aspergillus oryzae due to similarity to orthologs. It removes a single mannose residue from Man(9)GlcNAc(2), generating Man(8)GlcNAc(2) isomer B. Disruption of manE caused drastic decreases in ER-Man activity in A. oryzae microsomes.
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Aikawa JI, Matsuo I, Ito Y. In vitro mannose trimming property of human ER α-1,2 mannosidase I. Glycoconj J 2011; 29:35-45. [PMID: 22160784 DOI: 10.1007/s10719-011-9362-1] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2011] [Revised: 11/13/2011] [Accepted: 11/16/2011] [Indexed: 12/31/2022]
Abstract
Endoplasmic reticulum α-1,2 mannosidase I (ERManI) is an enzyme, which removes α(1-2) linked mannoses from asparagine-linked oligosaccharides on glycoproteins in the endoplasmic reticulum (ER). ERManI preferentially removes one α(1-2) linked mannose from B-chain of Man(9)GlcNAc(2). When glycoproteins fail to achieve properly folding, increased removal of α(1-2) linked mannoses on their oligosaccharides is induced and leads them to be disposed and degraded by ER-associated degradation pathway. However, it is still inconclusive whether accelerated removal of α(1-2) linked mannoses on those glycoproteins is catalyzed by the α-1,2 mannosidase I, proteins similar to mannosidase I [e.g. ER degradation-enhancing α-1,2 mannosidase-like protein (EDEM)], or both of them. Therefore, to approach this issue, we have investigated its in vitro activities using various oligosaccharides and glycoproteins as substrates. A recombinant form of human ERManI (hERManI) was prepared by using Escherichia coli. First, the enzyme generated Man(6)GlcNAc(2)-PA and Man(5)GlcNAc(2)-PA from 100 μM Man(9)GlcNAc(2)-PA after a one-hour reaction. Second, we have exposed bovine thyroglobulin and soybean agglutinin to denaturing conditions, e.g. 8 M urea, and used those glycoproteins as substrates. Sugar moieties were released from the reactant by PNGase F and their structures and amounts were elucidated by HPLC analysis. Intriguingly, the enzyme was shown to remove mannoses from bovine thyroglobulin and soybean agglutinin to larger extents when they were exposed to a denaturant. Therefore, our results suggested that hERManI could recognize tertiary and/or quaternary structures of glycoproteins and remove more α-1,2 linked mannoses from misfolded glycoproteins in living cells.
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Affiliation(s)
- Jun-ichi Aikawa
- RIKEN Advanced Science Institute, Hirosawa, Wako, Saitama, Japan.
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Rafiq MA, Kuss AW, Puettmann L, Noor A, Ramiah A, Ali G, Hu H, Kerio NA, Xiang Y, Garshasbi M, Khan MA, Ishak GE, Weksberg R, Ullmann R, Tzschach A, Kahrizi K, Mahmood K, Naeem F, Ayub M, Moremen KW, Vincent JB, Ropers HH, Ansar M, Najmabadi H. Mutations in the alpha 1,2-mannosidase gene, MAN1B1, cause autosomal-recessive intellectual disability. Am J Hum Genet 2011; 89:176-82. [PMID: 21763484 DOI: 10.1016/j.ajhg.2011.06.006] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2011] [Revised: 05/19/2011] [Accepted: 06/07/2011] [Indexed: 11/15/2022] Open
Abstract
We have used genome-wide genotyping to identify an overlapping homozygosity-by-descent locus on chromosome 9q34.3 (MRT15) in four consanguineous families affected by nonsyndromic autosomal-recessive intellectual disability (NS-ARID) and one in which the patients show additional clinical features. Four of the families are from Pakistan, and one is from Iran. Using a combination of next-generation sequencing and Sanger sequencing, we have identified mutations in the gene MAN1B1, encoding a mannosyl oligosaccharide, alpha 1,2-mannosidase. In one Pakistani family, MR43, a homozygous nonsense mutation (RefSeq number NM_016219.3: c.1418G>A [p.Trp473*]), segregated with intellectual disability and additional dysmorphic features. We also identified the missense mutation c. 1189G>A (p.Glu397Lys; RefSeq number NM_016219.3), which segregates with NS-ARID in three families who come from the same village and probably have shared inheritance. In the Iranian family, the missense mutation c.1000C>T (p.Arg334Cys; RefSeq number NM_016219.3) also segregates with NS-ARID. Both missense mutations are at amino acid residues that are conserved across the animal kingdom, and they either reduce k(cat) by ∼1300-fold or disrupt stable protein expression in mammalian cells. MAN1B1 is one of the few NS-ARID genes with an elevated mutation frequency in patients with NS-ARID from different populations.
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Affiliation(s)
- Muhammad Arshad Rafiq
- Molecular Neuropsychiatry and Development Lab, Neurogenetics Section, Centre for Addiction and Mental Health, Toronto, Ontario, Canada
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Pan S, Wang S, Utama B, Huang L, Blok N, Estes MK, Moremen KW, Sifers RN. Golgi localization of ERManI defines spatial separation of the mammalian glycoprotein quality control system. Mol Biol Cell 2011; 22:2810-22. [PMID: 21697506 PMCID: PMC3154878 DOI: 10.1091/mbc.e11-02-0118] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
The current study provides mechanistic insight into the overlapping dynamics by which glycoprotein folding and quality control use distinct intracellular compartments as part of the proteostasis network in mammalian cells. The Golgi complex has been implicated as a possible component of endoplasmic reticulum (ER) glycoprotein quality control, although the elucidation of its exact role is lacking. ERManI, a putative ER resident mannosidase, plays a rate-limiting role in generating a signal that targets misfolded N-linked glycoproteins for ER-associated degradation (ERAD). Herein we demonstrate that the endogenous human homologue predominantly resides in the Golgi complex, where it is subjected to O-glycosylation. To distinguish the intracellular site where the glycoprotein ERAD signal is generated, a COPI-binding motif was appended to the N terminus of the recombinant protein to facilitate its retrograde translocation back to the ER. Partial redistribution of the modified ERManI was observed along with an accelerated rate at which N-linked glycans of misfolded α1-antitrypsin variant NHK were trimmed. Despite these observations, the rate of NHK degradation was not accelerated, implicating the Golgi complex as the site for glycoprotein ERAD substrate tagging. Taken together, these data provide a potential mechanistic explanation for the spatial separation by which glycoprotein quality control components operate in mammalian cells.
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Affiliation(s)
- Shujuan Pan
- Departments of Pathology & Immunology, Baylor College of Medicine, Houston, TX 77030, USA
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Isoyama-Tanaka J, Dohi K, Misaki R, Fujiyama K. Improved expression and characterization of recombinant human Golgi α1,2-mannosidase I isoforms (IA2 and IC) by Escherichia coli. J Biosci Bioeng 2011; 112:14-9. [PMID: 21450520 DOI: 10.1016/j.jbiosc.2011.02.013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2010] [Revised: 02/02/2011] [Accepted: 02/23/2011] [Indexed: 10/18/2022]
Abstract
Golgi α1,2-mannosidase I is involved in the N-linked oligosaccharide processing pathway. In this study, two truncated genes encoding for human Golgi α1,2-mannosidase I (hManIA2: amino acids 127-626 and hManIC: amino acids 118-617) were expressed in Escherichia coli to characterize the enzymes. These genes were fused to a T7 protein tag and a histidine tag at the N- and C-terminal ends, respectively, and purified using Co(2+) affinity chromatography. The properties including optimal temperature, optimal pH, and substrate specificity of the purified enzymes were investigated by HPLC using pyridylamino (PA)-labeled oligosaccharides as substrates. The stability of hManIA2 was dependent on the presence of Ca(2+), which was also required for its activity. On the other hand, hManIC was stable in the absence of Ca(2+), even though Ca(2+) was also effective for the activity of hManIC. While the similarity of the amino acid sequences is over 60%, hManIA2 and hManIC showed different substrate specificities particularly toward M9A and M8C.
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Affiliation(s)
- Junko Isoyama-Tanaka
- International Center for Biotechnology, Osaka University, 2–1 Yamada-oka, Suita, Osaka 565–0871, Japan
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Roth J, Zuber C, Park S, Jang I, Lee Y, Kysela KG, Le Fourn V, Santimaria R, Guhl B, Cho JW. Protein N-glycosylation, protein folding, and protein quality control. Mol Cells 2010; 30:497-506. [PMID: 21340671 DOI: 10.1007/s10059-010-0159-z] [Citation(s) in RCA: 119] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2010] [Accepted: 11/11/2010] [Indexed: 11/27/2022] Open
Abstract
Quality control of protein folding represents a fundamental cellular activity. Early steps of protein N-glycosylation involving the removal of three glucose and some specific mannose residues in the endoplasmic reticulum have been recognized as being of importance for protein quality control. Specific oligosaccharide structures resulting from the oligosaccharide processing may represent a glycocode promoting productive protein folding, whereas others may represent glyco-codes for routing not correctly folded proteins for dislocation from the endoplasmic reticulum to the cytosol and subsequent degradation. Although quality control of protein folding is essential for the proper functioning of cells, it is also the basis for protein folding disorders since the recognition and elimination of non-native conformers can result either in loss-of-function or pathological-gain-of-function. The machinery for protein folding control represents a prime example of an intricate interactome present in a single organelle, the endoplasmic reticulum. Here, current views of mechanisms for the recognition and retention leading to productive protein folding or the eventual elimination of misfolded glycoproteins in yeast and mammalian cells are reviewed.
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Affiliation(s)
- Jürgen Roth
- Department of Integrated OMICs for Biomedical Sciences, WCU Program of Graduate School, Yonsei University, Seoul 120-749, Korea.
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