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Schoberer J, Shin YJ, Vavra U, Veit C, Strasser R. Analysis of Protein Glycosylation in the ER. Methods Mol Biol 2024; 2772:221-238. [PMID: 38411817 DOI: 10.1007/978-1-0716-3710-4_16] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/28/2024]
Abstract
Protein N-glycosylation is an essential posttranslational modification which is initiated in the endoplasmic reticulum (ER). In plants, the N-glycans play a pivotal role in protein folding and quality control. Through the interaction of glycan processing and binding reactions mediated by ER-resident glycosidases and specific carbohydrate-binding proteins, the N-glycans contribute to the adoption of a native protein conformation. Properly folded glycoproteins are released from these processes and allowed to continue their transit to the Golgi where further processing and maturation of N-glycans leads to the formation of more complex structures with different functions. Incompletely folded glycoproteins are removed from the ER by a highly conserved degradation process to prevent the accumulation or secretion of misfolded proteins and maintain ER homeostasis. Here, we describe methods to analyze the N-glycosylation status and the glycan-dependent ER-associated degradation process in plants.
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Affiliation(s)
- Jennifer Schoberer
- Department of Applied Genetics and Cell Biology, University of Natural Resources and Life Sciences, Vienna, Austria
| | - Yun-Ji Shin
- Department of Applied Genetics and Cell Biology, University of Natural Resources and Life Sciences, Vienna, Austria
| | - Ulrike Vavra
- Department of Applied Genetics and Cell Biology, University of Natural Resources and Life Sciences, Vienna, Austria
| | - Christiane Veit
- Department of Applied Genetics and Cell Biology, University of Natural Resources and Life Sciences, Vienna, Austria
| | - Richard Strasser
- Department of Applied Genetics and Cell Biology, University of Natural Resources and Life Sciences, Vienna, Austria.
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Nweke AB, Nagasato D, Matsuoka K. Secreted arabinogalactan protein from salt-adapted tobacco BY-2 cells appears to be glycosylphosphatidyl inositol-anchored and associated with lipophilic moieties. Biosci Biotechnol Biochem 2023; 87:1274-1284. [PMID: 37573142 DOI: 10.1093/bbb/zbad112] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2023] [Accepted: 08/02/2023] [Indexed: 08/14/2023]
Abstract
Arabinogalactan proteins (AGPs) are plant extracellular proteoglycans associated with the plasma membrane by a glycosylphosphatidylinositol (GPI) anchor. This moiety is thought to be cleaved by phospholipase for secretion. Salt-adapted tobacco BY-2 cells were reported to secrete large amounts of AGPs into the medium. To investigate this mechanism, we expressed a fusion protein of tobacco sweet potato sporamin and AGP (SPO-AGP) in BY-2 cells and analyzed its fate after salt-adapting the cells. A two-phase separation analysis using Triton X-114 indicated that a significant proportion of SPO-AGP in the medium was recovered in the detergent phase, suggesting that this protein is GPI-anchored. Differential ultracentrifugation and a gradient density fractionation implicated extracellular vesicles or particles with SPO-AGP in the medium. Endogenous AGP secreted from salt-adapted and nontransgenic BY-2 cells behaved similarly to SPO-AGP. These results suggest that a part of the secreted AGPs from salt-adapted tobacco BY-2 cells are GPI-anchored and associated with particles or vesicles.
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Affiliation(s)
- Arinze Boniface Nweke
- Department of Bioscience and Biotechnology, Graduate School of Bioresource and Bioenvironmental Sciences, Kyushu University, Fukuoka, Japan
| | - Daiki Nagasato
- Department of Bioscience and Biotechnology, Graduate School of Bioresource and Bioenvironmental Sciences, Kyushu University, Fukuoka, Japan
| | - Ken Matsuoka
- Department of Bioscience and Biotechnology, Graduate School of Bioresource and Bioenvironmental Sciences, Kyushu University, Fukuoka, Japan
- Department of Bioscience and Biotechnology, Faculty of Agriculture, Kyushu University, Fukuoka, Japan
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Quan N, Eguchi Y, Geiler-Samerotte K. Intra- FCY1: a novel system to identify mutations that cause protein misfolding. Front Genet 2023; 14:1198203. [PMID: 37745845 PMCID: PMC10512024 DOI: 10.3389/fgene.2023.1198203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Accepted: 08/22/2023] [Indexed: 09/26/2023] Open
Abstract
Protein misfolding is a common intracellular occurrence. Most mutations to coding sequences increase the propensity of the encoded protein to misfold. These misfolded molecules can have devastating effects on cells. Despite the importance of protein misfolding in human disease and protein evolution, there are fundamental questions that remain unanswered, such as, which mutations cause the most misfolding? These questions are difficult to answer partially because we lack high-throughput methods to compare the destabilizing effects of different mutations. Commonly used systems to assess the stability of mutant proteins in vivo often rely upon essential proteins as sensors, but misfolded proteins can disrupt the function of the essential protein enough to kill the cell. This makes it difficult to identify and compare mutations that cause protein misfolding using these systems. Here, we present a novel in vivo system named Intra-FCY1 that we use to identify mutations that cause misfolding of a model protein [yellow fluorescent protein (YFP)] in Saccharomyces cerevisiae. The Intra-FCY1 system utilizes two complementary fragments of the yeast cytosine deaminase Fcy1, a toxic protein, into which YFP is inserted. When YFP folds, the Fcy1 fragments associate together to reconstitute their function, conferring toxicity in media containing 5-fluorocytosine and hindering growth. But mutations that make YFP misfold abrogate Fcy1 toxicity, thus strains possessing misfolded YFP variants rise to high frequency in growth competition experiments. This makes such strains easier to study. The Intra-FCY1 system cancels localization of the protein of interest, thus can be applied to study the relative stability of mutant versions of diverse cellular proteins. Here, we confirm this method can identify novel mutations that cause misfolding, highlighting the potential for Intra-FCY1 to illuminate the relationship between protein sequence and stability.
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Affiliation(s)
- N. Quan
- Biodesign Center for Mechanisms of Evolution, Arizona State University, Tempe, AZ, United States
- School of Life Sciences, Arizona State University, Tempe, AZ, United States
| | - Y. Eguchi
- Biodesign Center for Mechanisms of Evolution, Arizona State University, Tempe, AZ, United States
| | - K. Geiler-Samerotte
- Biodesign Center for Mechanisms of Evolution, Arizona State University, Tempe, AZ, United States
- School of Life Sciences, Arizona State University, Tempe, AZ, United States
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Lemus L, Hegde RS, Goder V. New frontiers in quality control: the case of GPI-anchored proteins. Nat Rev Mol Cell Biol 2023; 24:599-600. [PMID: 37231113 DOI: 10.1038/s41580-023-00616-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Affiliation(s)
- Leticia Lemus
- Department of Genetics, University of Seville, Seville, Spain.
| | - Ramanujan S Hegde
- Cell Biology Division, MRC Laboratory of Molecular Biology, Cambridge, UK
| | - Veit Goder
- Department of Genetics, University of Seville, Seville, Spain.
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Wu T, Jiang Y, Shi W, Wang Y, Li T. Endoplasmic reticulum stress: a novel targeted approach to repair bone defects by regulating osteogenesis and angiogenesis. J Transl Med 2023; 21:480. [PMID: 37464413 PMCID: PMC10353205 DOI: 10.1186/s12967-023-04328-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2023] [Accepted: 07/06/2023] [Indexed: 07/20/2023] Open
Abstract
Bone regeneration therapy is clinically important, and targeted regulation of endoplasmic reticulum (ER) stress is important in regenerative medicine. The processing of proteins in the ER controls cell fate. The accumulation of misfolded and unfolded proteins occurs in pathological states, triggering ER stress. ER stress restores homeostasis through three main mechanisms, including protein kinase-R-like ER kinase (PERK), inositol-requiring enzyme 1ɑ (IRE1ɑ) and activating transcription factor 6 (ATF6), collectively known as the unfolded protein response (UPR). However, the UPR has both adaptive and apoptotic effects. Modulation of ER stress has therapeutic potential for numerous diseases. Repair of bone defects involves both angiogenesis and bone regeneration. Here, we review the effects of ER stress on osteogenesis and angiogenesis, with emphasis on ER stress under high glucose (HG) and inflammatory conditions, and the use of ER stress inducers or inhibitors to regulate osteogenesis and angiogenesis. In addition, we highlight the ability for exosomes to regulate ER stress. Recent advances in the regulation of ER stress mediated osteogenesis and angiogenesis suggest novel therapeutic options for bone defects.
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Affiliation(s)
- Tingyu Wu
- Department of Joint Surgery, The Affiliated Hospital of Qingdao University, No. 59, Haier Road, Qingdao, 266003, China
| | - Yaping Jiang
- Department of Oral Implantology, The Affiliated Hospital of Qingdao University, Qingdao, 266003, China
| | - Weipeng Shi
- Department of Joint Surgery, The Affiliated Hospital of Qingdao University, No. 59, Haier Road, Qingdao, 266003, China
| | - Yingzhen Wang
- Department of Joint Surgery, The Affiliated Hospital of Qingdao University, No. 59, Haier Road, Qingdao, 266003, China
| | - Tao Li
- Department of Joint Surgery, The Affiliated Hospital of Qingdao University, No. 59, Haier Road, Qingdao, 266003, China.
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Gupta MK, Randhawa PK, Masternak MM. Role of BAG5 in Protein Quality Control: Double-Edged Sword? FRONTIERS IN AGING 2022; 3:844168. [PMID: 35821856 PMCID: PMC9261338 DOI: 10.3389/fragi.2022.844168] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/27/2021] [Accepted: 02/08/2022] [Indexed: 11/15/2022]
Abstract
Cardiovascular disorder is the major health burden and cause of death among individuals worldwide. As the cardiomyocytes lack the ability for self-renewal, it is utmost necessary to surveil the protein quality in the cells. The Bcl-2 associated anthanogene protein (BAG) family and molecular chaperones (HSP70, HSP90) actively participate in maintaining cellular protein quality control (PQC) to limit cellular dysfunction in the cells. The BAG family contains a unique BAG domain which facilitates their interaction with the ATPase domain of the heat shock protein 70 (HSP70) to assist in protein folding. Among the BAG family members (BAG1-6), BAG5 protein is unique since it has five domains in tandem, and the binding of BD5 induces certain conformational changes in the nucleotide-binding domain (NBD) of HSP70 such that it loses its affinity for binding to ADP and results in enhanced protein refolding activity of HSP70. In this review, we shall describe the role of BAG5 in modulating mitophagy, endoplasmic stress, and cellular viability. Also, we have highlighted the interaction of BAG5 with other proteins, including PINK, DJ-1, CHIP, and their role in cellular PQC. Apart from this, we have described the role of BAG5 in cellular metabolism and aging.
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Skelly MJ. Dropping anchor: stringent quality control prevents GPI anchoring of severely misfolded proteins in plants. PLANT PHYSIOLOGY 2021; 186:1757-1759. [PMID: 34618114 PMCID: PMC8331156 DOI: 10.1093/plphys/kiab257] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Accepted: 05/17/2021] [Indexed: 06/13/2023]
Affiliation(s)
- Michael J Skelly
- Institute of Molecular Plant Sciences, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3BF, UK
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