1
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Chung KP, Frieboese D, Waltz F, Engel BD, Bock R. Identification and characterization of the COPII vesicle-forming GTPase Sar1 in Chlamydomonas. PLANT DIRECT 2024; 8:e614. [PMID: 38887666 PMCID: PMC11180857 DOI: 10.1002/pld3.614] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/04/2024] [Accepted: 05/29/2024] [Indexed: 06/20/2024]
Abstract
Eukaryotic cells are highly compartmentalized, requiring elaborate transport mechanisms to facilitate the movement of proteins between membrane-bound compartments. Most proteins synthesized in the endoplasmic reticulum (ER) are transported to the Golgi apparatus through COPII-mediated vesicular trafficking. Sar1, a small GTPase that facilitates the formation of COPII vesicles, plays a critical role in the early steps of this protein secretory pathway. Sar1 was characterized in yeast, animals and plants, but no Sar1 homolog has been identified and functionally analyzed in algae. Here we identified a putative Sar1 homolog (CrSar1) in the model green alga Chlamydomonas reinhardtii through amino acid sequence similarity. We employed site-directed mutagenesis to generate a dominant-negative mutant of CrSar1 (CrSar1DN). Using protein secretion assays, we demonstrate the inhibitory effect of CrSar1DN on protein secretion. However, different from previously studied organisms, ectopic expression of CrSar1DN did not result in collapse of the ER-Golgi interface in Chlamydomonas. Nonetheless, our data suggest a largely conserved role of CrSar1 in the ER-to-Golgi protein secretory pathway in green algae.
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Affiliation(s)
- Kin Pan Chung
- Max‐Planck‐Institut für Molekulare PflanzenphysiologiePotsdamGermany
| | - Daniel Frieboese
- Max‐Planck‐Institut für Molekulare PflanzenphysiologiePotsdamGermany
| | | | | | - Ralph Bock
- Max‐Planck‐Institut für Molekulare PflanzenphysiologiePotsdamGermany
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2
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Ishiwata-Kimata Y, Kimata Y. Fundamental and Applicative Aspects of the Unfolded Protein Response in Yeasts. J Fungi (Basel) 2023; 9:989. [PMID: 37888245 PMCID: PMC10608004 DOI: 10.3390/jof9100989] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2023] [Revised: 10/03/2023] [Accepted: 10/04/2023] [Indexed: 10/28/2023] Open
Abstract
Upon the dysfunction or functional shortage of the endoplasmic reticulum (ER), namely, ER stress, eukaryotic cells commonly provoke a protective gene expression program called the unfolded protein response (UPR). The molecular mechanism of UPR has been uncovered through frontier genetic studies using Saccharomyces cerevisiae as a model organism. Ire1 is an ER-located transmembrane protein that directly senses ER stress and is activated as an RNase. During ER stress, Ire1 promotes the splicing of HAC1 mRNA, which is then translated into a transcription factor that induces the expression of various genes, including those encoding ER-located molecular chaperones and protein modification enzymes. While this mainstream intracellular UPR signaling pathway was elucidated in the 1990s, new intriguing insights have been gained up to now. For instance, various additional factors allow UPR evocation strictly in response to ER stress. The UPR machineries in other yeasts and fungi, including pathogenic species, are another important research topic. Moreover, industrially beneficial yeast strains carrying an enforced and enlarged ER have been produced through the artificial and constitutive induction of the UPR. In this article, we review canonical and up-to-date insights concerning the yeast UPR, mainly from the viewpoint of the functions and regulation of Ire1 and HAC1.
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Affiliation(s)
| | - Yukio Kimata
- Division of Biological Science, Graduate School of Science and Technology, Nara Institute of Science and Technology, Nara 630-0192, Japan
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3
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Bao X, Wang Y, Qi Y, Lei C, Wang Y, Pan T, Yu M, Zhang Y, Wu H, Zhang P, Ji Y, Yang H, Jiang X, Jing R, Yan M, Zhang B, Gu C, Zhu J, Hao Y, Lei J, Zhang S, Chen X, Chen R, Sun Y, Zhu Y, Zhang X, Jiang L, Visser RGF, Ren Y, Wang Y, Wan J. A deleterious Sar1c variant in rice inhibits export of seed storage proteins from the endoplasmic reticulum. PLANT MOLECULAR BIOLOGY 2023; 111:291-307. [PMID: 36469200 DOI: 10.1007/s11103-022-01327-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2022] [Accepted: 11/27/2022] [Indexed: 06/17/2023]
Abstract
We identified a dosage-dependent dominant negative form of Sar1c, which confirms the essential role of COPII system in mediating ER export of storage proteins in rice endosperm. Higher plants accumlate large amounts of seed storage proteins (SSPs). However, mechanisms underlying SSP trafficking are largely unknown, especially the ER-Golgi anterograde process. Here, we showed that a rice glutelin precursor accumulation13 (gpa13) mutant exhibited floury endosperm and overaccumulated glutelin precursors, which phenocopied the reported RNAi-Sar1abc line. Molecular cloning revealed that the gpa13 allele encodes a mutated Sar1c (mSar1c) with a deletion of two conserved amino acids Pro134 and Try135. Knockdown or knockout of Sar1c alone caused no obvious phenotype, while overexpression of mSar1c resulted in seedling lethality similar to the gpa13 mutant. Transient expression experiment in tobacco combined with subcellular fractionation experiment in gpa13 demonstrated that the expression of mSar1c affects the subcellular distribution of all Sar1 isoforms and Sec23c. In addition, mSar1c failed to interact with COPII component Sec23. Conversely, mSar1c competed with Sar1a/b/d to interact with guanine nucleotide exchange factor Sec12. Together, we identified a dosage-dependent dominant negative form of Sar1c, which confirms the essential role of COPII system in mediating ER export of storage proteins in rice endosperm.
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Affiliation(s)
- Xiuhao Bao
- State Key Laboratory for Crop Genetics and Germplasm Enhancement, Jiangsu Plant Gene Engineering Research Center, Nanjing Agricultural University, Nanjing, 210095, People's Republic of China
| | - Yongfei Wang
- State Key Laboratory for Crop Genetics and Germplasm Enhancement, Jiangsu Plant Gene Engineering Research Center, Nanjing Agricultural University, Nanjing, 210095, People's Republic of China
| | - Yanzhou Qi
- National Key Facility for Crop Gene Resources and Genetic Improvement, Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing, 100081, People's Republic of China
- Plant Breeding, Wageningen University & Research, PO Box 386, 6700 AJ, Wageningen, the Netherlands
| | - Cailin Lei
- National Key Facility for Crop Gene Resources and Genetic Improvement, Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing, 100081, People's Republic of China
| | - Yunlong Wang
- State Key Laboratory for Crop Genetics and Germplasm Enhancement, Jiangsu Plant Gene Engineering Research Center, Nanjing Agricultural University, Nanjing, 210095, People's Republic of China
| | - Tian Pan
- State Key Laboratory for Crop Genetics and Germplasm Enhancement, Jiangsu Plant Gene Engineering Research Center, Nanjing Agricultural University, Nanjing, 210095, People's Republic of China
| | - Mingzhou Yu
- State Key Laboratory for Crop Genetics and Germplasm Enhancement, Jiangsu Plant Gene Engineering Research Center, Nanjing Agricultural University, Nanjing, 210095, People's Republic of China
| | - Yu Zhang
- State Key Laboratory for Crop Genetics and Germplasm Enhancement, Jiangsu Plant Gene Engineering Research Center, Nanjing Agricultural University, Nanjing, 210095, People's Republic of China
| | - Hongming Wu
- State Key Laboratory for Crop Genetics and Germplasm Enhancement, Jiangsu Plant Gene Engineering Research Center, Nanjing Agricultural University, Nanjing, 210095, People's Republic of China
| | - Pengcheng Zhang
- State Key Laboratory for Crop Genetics and Germplasm Enhancement, Jiangsu Plant Gene Engineering Research Center, Nanjing Agricultural University, Nanjing, 210095, People's Republic of China
| | - Yi Ji
- State Key Laboratory for Crop Genetics and Germplasm Enhancement, Jiangsu Plant Gene Engineering Research Center, Nanjing Agricultural University, Nanjing, 210095, People's Republic of China
| | - Hang Yang
- State Key Laboratory for Crop Genetics and Germplasm Enhancement, Jiangsu Plant Gene Engineering Research Center, Nanjing Agricultural University, Nanjing, 210095, People's Republic of China
| | - Xiaokang Jiang
- State Key Laboratory for Crop Genetics and Germplasm Enhancement, Jiangsu Plant Gene Engineering Research Center, Nanjing Agricultural University, Nanjing, 210095, People's Republic of China
| | - Ruonan Jing
- State Key Laboratory for Crop Genetics and Germplasm Enhancement, Jiangsu Plant Gene Engineering Research Center, Nanjing Agricultural University, Nanjing, 210095, People's Republic of China
| | - Mengyuan Yan
- National Key Facility for Crop Gene Resources and Genetic Improvement, Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing, 100081, People's Republic of China
| | - Binglei Zhang
- National Key Facility for Crop Gene Resources and Genetic Improvement, Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing, 100081, People's Republic of China
| | - Chuanwei Gu
- State Key Laboratory for Crop Genetics and Germplasm Enhancement, Jiangsu Plant Gene Engineering Research Center, Nanjing Agricultural University, Nanjing, 210095, People's Republic of China
| | - Jianping Zhu
- State Key Laboratory for Crop Genetics and Germplasm Enhancement, Jiangsu Plant Gene Engineering Research Center, Nanjing Agricultural University, Nanjing, 210095, People's Republic of China
| | - Yuanyuan Hao
- State Key Laboratory for Crop Genetics and Germplasm Enhancement, Jiangsu Plant Gene Engineering Research Center, Nanjing Agricultural University, Nanjing, 210095, People's Republic of China
| | - Jie Lei
- State Key Laboratory for Crop Genetics and Germplasm Enhancement, Jiangsu Plant Gene Engineering Research Center, Nanjing Agricultural University, Nanjing, 210095, People's Republic of China
| | - Shuang Zhang
- National Key Facility for Crop Gene Resources and Genetic Improvement, Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing, 100081, People's Republic of China
| | - Xiaoli Chen
- State Key Laboratory for Crop Genetics and Germplasm Enhancement, Jiangsu Plant Gene Engineering Research Center, Nanjing Agricultural University, Nanjing, 210095, People's Republic of China
| | - Rongbo Chen
- State Key Laboratory for Crop Genetics and Germplasm Enhancement, Jiangsu Plant Gene Engineering Research Center, Nanjing Agricultural University, Nanjing, 210095, People's Republic of China
| | - Yinglun Sun
- State Key Laboratory for Crop Genetics and Germplasm Enhancement, Jiangsu Plant Gene Engineering Research Center, Nanjing Agricultural University, Nanjing, 210095, People's Republic of China
| | - Yun Zhu
- National Key Facility for Crop Gene Resources and Genetic Improvement, Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing, 100081, People's Republic of China
| | - Xin Zhang
- National Key Facility for Crop Gene Resources and Genetic Improvement, Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing, 100081, People's Republic of China
| | - Ling Jiang
- State Key Laboratory for Crop Genetics and Germplasm Enhancement, Jiangsu Plant Gene Engineering Research Center, Nanjing Agricultural University, Nanjing, 210095, People's Republic of China
| | - Richard G F Visser
- Plant Breeding, Wageningen University & Research, PO Box 386, 6700 AJ, Wageningen, the Netherlands
| | - Yulong Ren
- National Key Facility for Crop Gene Resources and Genetic Improvement, Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing, 100081, People's Republic of China.
| | - Yihua Wang
- State Key Laboratory for Crop Genetics and Germplasm Enhancement, Jiangsu Plant Gene Engineering Research Center, Nanjing Agricultural University, Nanjing, 210095, People's Republic of China.
| | - Jianmin Wan
- State Key Laboratory for Crop Genetics and Germplasm Enhancement, Jiangsu Plant Gene Engineering Research Center, Nanjing Agricultural University, Nanjing, 210095, People's Republic of China
- National Key Facility for Crop Gene Resources and Genetic Improvement, Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing, 100081, People's Republic of China
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4
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Liu Z, Yan M, Lei W, Jiang R, Dai W, Chen J, Wang C, Li L, Wu M, Nian X, Li D, Sun D, Lv X, Wang C, Xie C, Yao L, Wu C, Hu J, Xiao N, Mo W, Wang Z, Zhang L. Sec13 promotes oligodendrocyte differentiation and myelin repair through autocrine pleiotrophin signaling. J Clin Invest 2022; 132:155096. [PMID: 35143418 PMCID: PMC8970680 DOI: 10.1172/jci155096] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Accepted: 02/08/2022] [Indexed: 11/17/2022] Open
Abstract
Dysfunction of protein trafficking has been intensively associated with neurological diseases, including neurodegeneration, but whether and how protein transport contributes to oligodendrocyte (OL) maturation and myelin repair in white matter injury remains unclear. ER-to-Golgi trafficking of newly synthesized proteins is mediated by coat protein complex II (COPII). Here, we demonstrate that the COPII component Sec13 was essential for OL differentiation and postnatal myelination. Ablation of Sec13 in the OL lineage prevented OPC differentiation and inhibited myelination and remyelination after demyelinating injury in the central nervous system (CNS), while improving protein trafficking by tauroursodeoxycholic acid (TUDCA) or ectopic expression of COPII components accelerated myelination. COPII components were upregulated in OL lineage cells after demyelinating injury. Loss of Sec13 altered the secretome of OLs and inhibited the secretion of pleiotrophin (PTN), which was found to function as an autocrine factor to promote OL differentiation and myelin repair. These data suggest that Sec13-dependent protein transport is essential for OL differentiation and that Sec13-mediated PTN autocrine signaling is required for proper myelination and remyelination.
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Affiliation(s)
- Zhixiong Liu
- Department of Neuroscience, Institute of Neurosurgery, and Department of Neurosurgery, The First Affiliated Hospital, State Key Laboratory of Cellular Stress Biology, School of Medicine
- Xiamen Key Laboratory of Brain Center, The First Affiliated Hospital
- School of Life Sciences, Innovation Center for Cell Signaling Network, and
| | - Minbiao Yan
- Department of Neuroscience, Institute of Neurosurgery, and Department of Neurosurgery, The First Affiliated Hospital, State Key Laboratory of Cellular Stress Biology, School of Medicine
- Xiamen Key Laboratory of Brain Center, The First Affiliated Hospital
- School of Life Sciences, Innovation Center for Cell Signaling Network, and
| | - Wanying Lei
- Department of Neuroscience, Institute of Neurosurgery, and Department of Neurosurgery, The First Affiliated Hospital, State Key Laboratory of Cellular Stress Biology, School of Medicine
- Xiamen Key Laboratory of Brain Center, The First Affiliated Hospital
- School of Life Sciences, Innovation Center for Cell Signaling Network, and
| | - Rencai Jiang
- School of Life Sciences, Innovation Center for Cell Signaling Network, and
| | - Wenxiu Dai
- School of Life Sciences, Innovation Center for Cell Signaling Network, and
| | - Jialin Chen
- School of Life Sciences, Innovation Center for Cell Signaling Network, and
| | - Chaomeng Wang
- School of Life Sciences, Innovation Center for Cell Signaling Network, and
| | - Li Li
- School of Life Sciences, Innovation Center for Cell Signaling Network, and
| | - Mei Wu
- School of Life Sciences, Innovation Center for Cell Signaling Network, and
| | - Ximing Nian
- School of Life Sciences, Innovation Center for Cell Signaling Network, and
| | - Daopeng Li
- School of Life Sciences, Innovation Center for Cell Signaling Network, and
| | - Di Sun
- School of Life Sciences, Innovation Center for Cell Signaling Network, and
| | - Xiaoqi Lv
- School of Life Sciences, Innovation Center for Cell Signaling Network, and
| | - Chaoying Wang
- School of Life Sciences, Innovation Center for Cell Signaling Network, and
| | - Changchuan Xie
- School of Life Sciences, Innovation Center for Cell Signaling Network, and
| | - Luming Yao
- School of Life Sciences, Innovation Center for Cell Signaling Network, and
| | - Caiming Wu
- School of Life Sciences, Innovation Center for Cell Signaling Network, and
| | - Jin Hu
- School of Life Sciences, Innovation Center for Cell Signaling Network, and
| | - Naian Xiao
- Department of Neurology, The First Affiliated Hospital, Xiamen University, Fujian, China
| | - Wei Mo
- Department of Neuroscience, Institute of Neurosurgery, and Department of Neurosurgery, The First Affiliated Hospital, State Key Laboratory of Cellular Stress Biology, School of Medicine
- Xiamen Key Laboratory of Brain Center, The First Affiliated Hospital
- School of Life Sciences, Innovation Center for Cell Signaling Network, and
| | - Zhanxiang Wang
- Department of Neuroscience, Institute of Neurosurgery, and Department of Neurosurgery, The First Affiliated Hospital, State Key Laboratory of Cellular Stress Biology, School of Medicine
- Xiamen Key Laboratory of Brain Center, The First Affiliated Hospital
| | - Liang Zhang
- Department of Neuroscience, Institute of Neurosurgery, and Department of Neurosurgery, The First Affiliated Hospital, State Key Laboratory of Cellular Stress Biology, School of Medicine
- Xiamen Key Laboratory of Brain Center, The First Affiliated Hospital
- School of Life Sciences, Innovation Center for Cell Signaling Network, and
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5
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Aniento F, Sánchez de Medina Hernández V, Dagdas Y, Rojas-Pierce M, Russinova E. Molecular mechanisms of endomembrane trafficking in plants. THE PLANT CELL 2022; 34:146-173. [PMID: 34550393 PMCID: PMC8773984 DOI: 10.1093/plcell/koab235] [Citation(s) in RCA: 44] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2021] [Accepted: 09/12/2021] [Indexed: 05/10/2023]
Abstract
Endomembrane trafficking is essential for all eukaryotic cells. The best-characterized membrane trafficking organelles include the endoplasmic reticulum (ER), Golgi apparatus, early and recycling endosomes, multivesicular body, or late endosome, lysosome/vacuole, and plasma membrane. Although historically plants have given rise to cell biology, our understanding of membrane trafficking has mainly been shaped by the much more studied mammalian and yeast models. Whereas organelles and major protein families that regulate endomembrane trafficking are largely conserved across all eukaryotes, exciting variations are emerging from advances in plant cell biology research. In this review, we summarize the current state of knowledge on plant endomembrane trafficking, with a focus on four distinct trafficking pathways: ER-to-Golgi transport, endocytosis, trans-Golgi network-to-vacuole transport, and autophagy. We acknowledge the conservation and commonalities in the trafficking machinery across species, with emphasis on diversity and plant-specific features. Understanding the function of organelles and the trafficking machinery currently nonexistent in well-known model organisms will provide great opportunities to acquire new insights into the fundamental cellular process of membrane trafficking.
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Affiliation(s)
| | - Víctor Sánchez de Medina Hernández
- Gregor Mendel Institute, Austrian Academy of Sciences, Vienna BioCenter, 1030 Vienna, Austria
- Vienna BioCenter PhD Program, Doctoral School of the University of Vienna and Medical University of Vienna, A-1030, Vienna, Austria
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6
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Gorrell L, Omari S, Makareeva E, Leikin S. Noncanonical ER-Golgi trafficking and autophagy of endogenous procollagen in osteoblasts. Cell Mol Life Sci 2021; 78:8283-8300. [PMID: 34779895 DOI: 10.1007/s00018-021-04017-z] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Revised: 10/01/2021] [Accepted: 10/27/2021] [Indexed: 01/05/2023]
Abstract
Secretion and quality control of large extracellular matrix proteins remain poorly understood and debated, particularly transport intermediates delivering folded proteins from the ER to Golgi and misfolded ones to lysosomes. Discrepancies between different studies are related to utilization of exogenous cargo, off-target effects of experimental conditions and cell manipulation, and identification of transport intermediates without tracing their origin and destination. To address these issues, here we imaged secretory and degradative trafficking of type I procollagen in live MC3T3 osteoblasts by replacing a region encoding N-propeptide in endogenous Col1a2 gDNA with GFP cDNA. We selected clones that produced the resulting fluorescent procollagen yet had normal expression of key osteoblast and ER/cell stress genes, normal procollagen folding, and normal deposition and mineralization of extracellular matrix. Live-cell imaging of these clones revealed ARF1-dependent transport intermediates, which had no COPII coat and delivered procollagen from ER exit sites (ERESs) to Golgi without stopping at ER-Golgi intermediate compartment (ERGIC). It also confirmed ERES microautophagy, i.e., lysosomes engulfing ERESs containing misfolded procollagen. Beyond validating these trafficking models for endogenous procollagen, we uncovered a probable cause of noncanonical cell stress response to procollagen misfolding. Recognized and retained only at ERESs, misfolded procollagen does not directly activate the canonical UPR, yet it disrupts the ER lumen by blocking normal secretory export from the ER.
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Affiliation(s)
- Laura Gorrell
- Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), National Institutes of Health, Bethesda, MD, 20892, USA.,Rensselaer Polytechnic Institute, Troy, NY, 12180, USA
| | - Shakib Omari
- Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), National Institutes of Health, Bethesda, MD, 20892, USA.,Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA, 92037, USA
| | - Elena Makareeva
- Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), National Institutes of Health, Bethesda, MD, 20892, USA
| | - Sergey Leikin
- Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), National Institutes of Health, Bethesda, MD, 20892, USA.
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7
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Kandasamy S, Couto K, Thackeray J. A docked mutation phenocopies dumpy oblique alleles via altered vesicle trafficking. PeerJ 2021; 9:e12175. [PMID: 34721959 PMCID: PMC8520396 DOI: 10.7717/peerj.12175] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Accepted: 08/27/2021] [Indexed: 11/20/2022] Open
Abstract
The Drosophila extracellular matrix protein Dumpy (Dpy) is one of the largest proteins encoded by any animal. One class of dpy mutations produces a characteristic shortening of the wing blade known as oblique (dpyo ), due to altered tension in the developing wing. We describe here the characterization of docked (doc), a gene originally named because of an allele producing a truncated wing. We show that doc corresponds to the gene model CG5484, which encodes a homolog of the yeast protein Yif1 and plays a key role in ER to Golgi vesicle transport. Genetic analysis is consistent with a similar role for Doc in vesicle trafficking: docked alleles interact not only with genes encoding the COPII core proteins sec23 and sec13, but also with the SNARE proteins synaptobrevin and syntaxin. Further, we demonstrate that the strong similarity between the doc1 and dpyo wing phenotypes reflects a functional connection between the two genes; we found that various dpy alleles are sensitive to changes in dosage of genes encoding other vesicle transport components such as sec13 and sar1. Doc's effects on trafficking are not limited to Dpy; for example, reduced doc dosage disturbed Notch pathway signaling during wing blade and vein development. These results suggest a model in which the oblique wing phenotype in doc1 results from reduced transport of wild-type Dumpy protein; by extension, an additional implication is that the dpyo alleles can themselves be explained as hypomorphs.
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Affiliation(s)
- Suresh Kandasamy
- Department of Biology, Clark University, Worcester, Massachusetts, United States
| | - Kiley Couto
- Department of Biology, Clark University, Worcester, Massachusetts, United States
| | - Justin Thackeray
- Department of Biology, Clark University, Worcester, Massachusetts, United States
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8
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Marom R, Burrage LC, Venditti R, Clément A, Blanco-Sánchez B, Jain M, Scott DA, Rosenfeld JA, Sutton VR, Shinawi M, Mirzaa G, DeVile C, Roberts R, Calder AD, Allgrove J, Grafe I, Lanza DG, Li X, Joeng KS, Lee YC, Song IW, Sliepka JM, Batkovskyte D, Washington M, Dawson BC, Jin Z, Jiang MM, Chen S, Chen Y, Tran AA, Emrick LT, Murdock DR, Hanchard NA, Zapata GE, Mehta NR, Weis MA, Scott AA, Tremp BA, Phillips JB, Wegner J, Taylor-Miller T, Gibbs RA, Muzny DM, Jhangiani SN, Hicks J, Stottmann RW, Dickinson ME, Seavitt JR, Heaney JD, Eyre DR, Westerfield M, De Matteis MA, Lee B. COPB2 loss of function causes a coatopathy with osteoporosis and developmental delay. Am J Hum Genet 2021; 108:1710-1724. [PMID: 34450031 PMCID: PMC8456174 DOI: 10.1016/j.ajhg.2021.08.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Accepted: 08/04/2021] [Indexed: 02/08/2023] Open
Abstract
Coatomer complexes function in the sorting and trafficking of proteins between subcellular organelles. Pathogenic variants in coatomer subunits or associated factors have been reported in multi-systemic disorders, i.e., coatopathies, that can affect the skeletal and central nervous systems. We have identified loss-of-function variants in COPB2, a component of the coatomer complex I (COPI), in individuals presenting with osteoporosis, fractures, and developmental delay of variable severity. Electron microscopy of COPB2-deficient subjects' fibroblasts showed dilated endoplasmic reticulum (ER) with granular material, prominent rough ER, and vacuoles, consistent with an intracellular trafficking defect. We studied the effect of COPB2 deficiency on collagen trafficking because of the critical role of collagen secretion in bone biology. COPB2 siRNA-treated fibroblasts showed delayed collagen secretion with retention of type I collagen in the ER and Golgi and altered distribution of Golgi markers. copb2-null zebrafish embryos showed retention of type II collagen, disorganization of the ER and Golgi, and early larval lethality. Copb2+/- mice exhibited low bone mass, and consistent with the findings in human cells and zebrafish, studies in Copb2+/- mouse fibroblasts suggest ER stress and a Golgi defect. Interestingly, ascorbic acid treatment partially rescued the zebrafish developmental phenotype and the cellular phenotype in Copb2+/- mouse fibroblasts. This work identifies a form of coatopathy due to COPB2 haploinsufficiency, explores a potential therapeutic approach for this disorder, and highlights the role of the COPI complex as a regulator of skeletal homeostasis.
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Affiliation(s)
- Ronit Marom
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; Texas Children's Hospital, Houston, TX 77030, USA
| | - Lindsay C Burrage
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; Texas Children's Hospital, Houston, TX 77030, USA
| | | | - Aurélie Clément
- Institute of Neuroscience, University of Oregon, Eugene, OR 97403, USA
| | | | - Mahim Jain
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Daryl A Scott
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; Texas Children's Hospital, Houston, TX 77030, USA; Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Jill A Rosenfeld
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - V Reid Sutton
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; Texas Children's Hospital, Houston, TX 77030, USA
| | - Marwan Shinawi
- Department of Pediatrics, Division of Genetics and Genomic Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Ghayda Mirzaa
- Center for Integrative Brain Research, Seattle Children's Research Institute, and Department of Pediatrics, University of Washington, and Brotman Baty Institute for Precision Medicine, Seattle, WA 98105, USA
| | - Catherine DeVile
- Great Ormond Street Hospital for Children NHS Foundation Trust, London WC1N 3JH, UK
| | - Rowenna Roberts
- Great Ormond Street Hospital for Children NHS Foundation Trust, London WC1N 3JH, UK
| | - Alistair D Calder
- Great Ormond Street Hospital for Children NHS Foundation Trust, London WC1N 3JH, UK
| | - Jeremy Allgrove
- Great Ormond Street Hospital for Children NHS Foundation Trust, London WC1N 3JH, UK
| | - Ingo Grafe
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Denise G Lanza
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Xiaohui Li
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Kyu Sang Joeng
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Yi-Chien Lee
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - I-Wen Song
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Joseph M Sliepka
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Dominyka Batkovskyte
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Megan Washington
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Brian C Dawson
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Zixue Jin
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Ming-Ming Jiang
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Shan Chen
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Yuqing Chen
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Alyssa A Tran
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Lisa T Emrick
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; Texas Children's Hospital, Houston, TX 77030, USA; Department of Pediatrics, Section of Neurology and Developmental Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA
| | - David R Murdock
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX 77030, USA
| | - Neil A Hanchard
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; Texas Children's Hospital, Houston, TX 77030, USA; Laboratory for Translational Genomics, ARS/USDA Children's Nutrition Research Center, Baylor College of Medicine, Houston, TX 77030, USA
| | - Gladys E Zapata
- Laboratory for Translational Genomics, ARS/USDA Children's Nutrition Research Center, Baylor College of Medicine, Houston, TX 77030, USA
| | - Nitesh R Mehta
- Laboratory for Translational Genomics, ARS/USDA Children's Nutrition Research Center, Baylor College of Medicine, Houston, TX 77030, USA
| | - Mary Ann Weis
- Department of Orthopaedics and Sports Medicine, University of Washington, Seattle, WA 98195, USA
| | - Abbey A Scott
- Division of Genetic Medicine, Seattle Children's Hospital, Seattle, WA 98105, USA
| | - Brenna A Tremp
- Institute of Neuroscience, University of Oregon, Eugene, OR 97403, USA
| | | | - Jeremy Wegner
- Institute of Neuroscience, University of Oregon, Eugene, OR 97403, USA
| | | | - Richard A Gibbs
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX 77030, USA
| | - Donna M Muzny
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX 77030, USA
| | - Shalini N Jhangiani
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX 77030, USA
| | - John Hicks
- Texas Children's Hospital, Houston, TX 77030, USA; Department of Pathology, Texas Children's Hospital, and Department of Pathology and Immunology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Rolf W Stottmann
- Division of Human Genetics, and Division of Developmental Biology, and Department of Pediatrics, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA
| | - Mary E Dickinson
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX 77030, USA
| | - John R Seavitt
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Jason D Heaney
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - David R Eyre
- Department of Orthopaedics and Sports Medicine, University of Washington, Seattle, WA 98195, USA
| | - Monte Westerfield
- Institute of Neuroscience, University of Oregon, Eugene, OR 97403, USA
| | - Maria Antonietta De Matteis
- Telethon Institute of Genetics and Medicine, Naples 80078, Italy; Department of Molecular Medicine and Medical Biotechnology, University of Napoli Federico II, Naples 80078, Italy
| | - Brendan Lee
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; Texas Children's Hospital, Houston, TX 77030, USA.
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9
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Le QG, Kimata Y. Multiple Ways for Stress Sensing and Regulation of the Endoplasmic Reticulum-stress Sensors. Cell Struct Funct 2021; 46:37-49. [PMID: 33775971 PMCID: PMC10511038 DOI: 10.1247/csf.21015] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2021] [Accepted: 03/11/2021] [Indexed: 11/11/2022] Open
Abstract
Dysfunction of the endoplasmic reticulum (ER), so-called ER stress, is accompanied with accumulation of unfolded proteins in the ER. Eukaryotic cells commonly have an ER-located transmembrane protein, Ire1, which triggers cellular protective events against ER stress. In animal cells, PERK and ATF6 also initiate the ER-stress response. As a common strategy to control the activity of these ER-stress sensors, an ER-resident molecular chaperone, BiP, serves as their negative regulator, and dissociates from them in response to ER stress. Although it sounds reasonable that unfolded proteins and Ire1 compete for BiP association, some publications argue against this competition model. Moreover, yeast Ire1 (and possibly also the mammalian major Ire1 paralogue IRE1α) directly detects ER-accumulated unfolded proteins, and subsequently oligomerizes for its further activation. Apart from protein misfolding, the saturation of membrane phospholipids is another outcome of ER-stressing stimuli, which is sensed by the transmembrane domain of Ire1. This review describes the canonical and up-to-date insights concerning stress-sensing and regulatory mechanisms of yeast Ire1 and metazoan ER-stress sensors.Key words: endoplasmic reticulum, stress, unfolded protein response, molecular chaperone.
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Affiliation(s)
- Quynh Giang Le
- Institute of Biomedicine and Pharmacy, Vietnam Military Medical University, 222 Phung Hung, Ha Dong, Ha Noi, Vietnam
- Institute of Biotechnology, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet road, Cau Giay, Ha Noi, Vietnam
| | - Yukio Kimata
- Graduate School of Science and Technology, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma, Nara, 630-0192, Japan
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10
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Lu CL, Kim J. Craniofacial Diseases Caused by Defects in Intracellular Trafficking. Genes (Basel) 2021; 12:726. [PMID: 34068038 PMCID: PMC8152478 DOI: 10.3390/genes12050726] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Revised: 05/10/2021] [Accepted: 05/11/2021] [Indexed: 12/12/2022] Open
Abstract
Cells use membrane-bound carriers to transport cargo molecules like membrane proteins and soluble proteins, to their destinations. Many signaling receptors and ligands are synthesized in the endoplasmic reticulum and are transported to their destinations through intracellular trafficking pathways. Some of the signaling molecules play a critical role in craniofacial morphogenesis. Not surprisingly, variants in the genes encoding intracellular trafficking machinery can cause craniofacial diseases. Despite the fundamental importance of the trafficking pathways in craniofacial morphogenesis, relatively less emphasis is placed on this topic, thus far. Here, we describe craniofacial diseases caused by lesions in the intracellular trafficking machinery and possible treatment strategies for such diseases.
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Affiliation(s)
| | - Jinoh Kim
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA 50011, USA;
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11
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Cendrowski J, Kaczmarek M, Mazur M, Kuzmicz-Kowalska K, Jastrzebski K, Brewinska-Olchowik M, Kominek A, Piwocka K, Miaczynska M. Splicing variation of BMP2K balances abundance of COPII assemblies and autophagic degradation in erythroid cells. eLife 2020; 9:58504. [PMID: 32795391 PMCID: PMC7473771 DOI: 10.7554/elife.58504] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2020] [Accepted: 08/13/2020] [Indexed: 12/26/2022] Open
Abstract
Intracellular transport undergoes remodeling upon cell differentiation, which involves cell type-specific regulators. Bone morphogenetic protein 2-inducible kinase (BMP2K) has been potentially implicated in endocytosis and cell differentiation but its molecular functions remained unknown. We discovered that its longer (L) and shorter (S) splicing variants regulate erythroid differentiation in a manner unexplainable by their involvement in AP-2 adaptor phosphorylation and endocytosis. However, both variants interact with SEC16A and could localize to the juxtanuclear secretory compartment. Variant-specific depletion approach showed that BMP2K isoforms constitute a BMP2K-L/S regulatory system that controls the distribution of SEC16A and SEC24B as well as SEC31A abundance at COPII assemblies. Finally, we found L to promote and S to restrict autophagic degradation and erythroid differentiation. Hence, we propose that BMP2K-L and BMP2K-S differentially regulate abundance and distribution of COPII assemblies as well as autophagy, possibly thereby fine-tuning erythroid differentiation.
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Affiliation(s)
- Jaroslaw Cendrowski
- Laboratory of Cell Biology, International Institute of Molecular and Cell Biology, Warsaw, Poland
| | - Marta Kaczmarek
- Laboratory of Cell Biology, International Institute of Molecular and Cell Biology, Warsaw, Poland
| | - Michał Mazur
- Laboratory of Cell Biology, International Institute of Molecular and Cell Biology, Warsaw, Poland
| | | | - Kamil Jastrzebski
- Laboratory of Cell Biology, International Institute of Molecular and Cell Biology, Warsaw, Poland
| | | | - Agata Kominek
- Laboratory of Cytometry, Nencki Institute of Experimental Biology, Warsaw, Poland
| | - Katarzyna Piwocka
- Laboratory of Cytometry, Nencki Institute of Experimental Biology, Warsaw, Poland
| | - Marta Miaczynska
- Laboratory of Cell Biology, International Institute of Molecular and Cell Biology, Warsaw, Poland
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12
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ER-to-Golgi Transport: A Sizeable Problem. Trends Cell Biol 2019; 29:940-953. [DOI: 10.1016/j.tcb.2019.08.007] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Revised: 08/22/2019] [Accepted: 08/23/2019] [Indexed: 11/16/2022]
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13
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Anelli T, Panina-Bordignon P. How to Avoid a No-Deal ER Exit. Cells 2019; 8:cells8091051. [PMID: 31500301 PMCID: PMC6769657 DOI: 10.3390/cells8091051] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2019] [Revised: 08/28/2019] [Accepted: 09/06/2019] [Indexed: 01/01/2023] Open
Abstract
Efficiency and fidelity of protein secretion are achieved thanks to the presence of different steps, located sequentially in time and space along the secretory compartment, controlling protein folding and maturation. After entering into the endoplasmic reticulum (ER), secretory proteins attain their native structure thanks to specific chaperones and enzymes. Only correctly folded molecules are allowed by quality control (QC) mechanisms to leave the ER and proceed to downstream compartments. Proteins that cannot fold properly are instead retained in the ER to be finally destined to proteasomal degradation. Exiting from the ER requires, in most cases, the use of coated vesicles, departing at the ER exit sites, which will fuse with the Golgi compartment, thus releasing their cargoes. Protein accumulation in the ER can be caused by a too stringent QC or by ineffective transport: these situations could be deleterious for the organism, due to the loss of the secreted protein, and to the cell itself, because of abnormal increase of protein concentration in the ER. In both cases, diseases can arise. In this review, we will describe the pathophysiology of protein folding and transport between the ER and the Golgi compartment.
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Affiliation(s)
- Tiziana Anelli
- Vita-Salute San Raffaele University, 20132 Milan, Italy.
- Division of Genetics and Cell Biology, IRCCS Ospedale San Raffaele, 20132 Milan, Italy.
| | - Paola Panina-Bordignon
- Vita-Salute San Raffaele University, 20132 Milan, Italy.
- Division of Neuroscience, IRCCS Ospedale San Raffaele, 20132 Milan, Italy.
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14
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Di Martino R, Sticco L, Luini A. Regulation of cargo export and sorting at the trans‐Golgi network. FEBS Lett 2019; 593:2306-2318. [DOI: 10.1002/1873-3468.13572] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2019] [Revised: 08/02/2019] [Accepted: 08/06/2019] [Indexed: 12/28/2022]
Affiliation(s)
- Rosaria Di Martino
- Institute of Biochemistry and Cell Biology (IBBC) Italian National Research Council (CNR) Naples Italy
| | - Lucia Sticco
- Institute of Biochemistry and Cell Biology (IBBC) Italian National Research Council (CNR) Naples Italy
| | - Alberto Luini
- Institute of Biochemistry and Cell Biology (IBBC) Italian National Research Council (CNR) Naples Italy
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15
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Perrier A, Bonnin A, Desmarets L, Danneels A, Goffard A, Rouillé Y, Dubuisson J, Belouzard S. The C-terminal domain of the MERS coronavirus M protein contains a trans-Golgi network localization signal. J Biol Chem 2019; 294:14406-14421. [PMID: 31399512 PMCID: PMC6768645 DOI: 10.1074/jbc.ra119.008964] [Citation(s) in RCA: 73] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2019] [Revised: 08/06/2019] [Indexed: 11/23/2022] Open
Abstract
Coronavirus M proteins represent the major protein component of the viral
envelope. They play an essential role during viral assembly by interacting with
all of the other structural proteins. Coronaviruses bud into the endoplasmic
reticulum (ER)–Golgi intermediate compartment (ERGIC), but the mechanisms
by which M proteins are transported from their site of synthesis, the ER, to the
budding site remain poorly understood. Here, we investigated the intracellular
trafficking of the Middle East respiratory syndrome coronavirus (MERS-CoV) M
protein. Subcellular localization analyses revealed that the MERS-CoV M protein
is retained intracellularly in the trans-Golgi network (TGN),
and we identified two motifs in the distal part of the C-terminal domain as
being important for this specific localization. We identified the first motif as
a functional diacidic DxE ER export signal, because substituting Asp-211 and
Glu-213 with alanine induced retention of the MERS-CoV M in the ER. The second
motif, 199KxGxYR204, was responsible for retaining the M
protein in the TGN. Substitution of this motif resulted in MERS-CoV M leakage
toward the plasma membrane. We further confirmed the role of
199KxGxYR204 as a TGN retention signal by using
chimeras between MERS-CoV M and the M protein of infectious bronchitis virus
(IBV). Our results indicated that the C-terminal domains of both proteins
determine their specific localization, namely TGN and
ERGIC/cis-Golgi for MERS-M and IBV-M, respectively. Our
findings indicate that MERS-CoV M protein localizes to the TGN because of the
combined presence of an ER export signal and a TGN retention motif.
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Affiliation(s)
- Anabelle Perrier
- Université Lille, CNRS, INSERM, CHU Lille, Institut Pasteur de Lille, U1019-UMR 8204-CIIL-Center for Infection and Immunity of Lille, F-59000 Lille, France
| | - Ariane Bonnin
- Université Lille, CNRS, INSERM, CHU Lille, Institut Pasteur de Lille, U1019-UMR 8204-CIIL-Center for Infection and Immunity of Lille, F-59000 Lille, France
| | - Lowiese Desmarets
- Université Lille, CNRS, INSERM, CHU Lille, Institut Pasteur de Lille, U1019-UMR 8204-CIIL-Center for Infection and Immunity of Lille, F-59000 Lille, France
| | - Adeline Danneels
- Université Lille, CNRS, INSERM, CHU Lille, Institut Pasteur de Lille, U1019-UMR 8204-CIIL-Center for Infection and Immunity of Lille, F-59000 Lille, France
| | - Anne Goffard
- Université Lille, CNRS, INSERM, CHU Lille, Institut Pasteur de Lille, U1019-UMR 8204-CIIL-Center for Infection and Immunity of Lille, F-59000 Lille, France
| | - Yves Rouillé
- Université Lille, CNRS, INSERM, CHU Lille, Institut Pasteur de Lille, U1019-UMR 8204-CIIL-Center for Infection and Immunity of Lille, F-59000 Lille, France
| | - Jean Dubuisson
- Université Lille, CNRS, INSERM, CHU Lille, Institut Pasteur de Lille, U1019-UMR 8204-CIIL-Center for Infection and Immunity of Lille, F-59000 Lille, France
| | - Sandrine Belouzard
- Université Lille, CNRS, INSERM, CHU Lille, Institut Pasteur de Lille, U1019-UMR 8204-CIIL-Center for Infection and Immunity of Lille, F-59000 Lille, France
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16
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Coupling of COPII vesicle trafficking to nutrient availability by the IRE1α-XBP1s axis. Proc Natl Acad Sci U S A 2019; 116:11776-11785. [PMID: 31123148 DOI: 10.1073/pnas.1814480116] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
The cytoplasmic coat protein complex-II (COPII) is evolutionarily conserved machinery that is essential for efficient trafficking of protein and lipid cargos. How the COPII machinery is regulated to meet the metabolic demand in response to alterations of the nutritional state remains largely unexplored, however. Here, we show that dynamic changes of COPII vesicle trafficking parallel the activation of transcription factor X-box binding protein 1 (XBP1s), a critical transcription factor in handling cellular endoplasmic reticulum (ER) stress in both live cells and mouse livers upon physiological fluctuations of nutrient availability. Using live-cell imaging approaches, we demonstrate that XBP1s is sufficient to promote COPII-dependent trafficking, mediating the nutrient stimulatory effects. Chromatin immunoprecipitation (ChIP) coupled with high-throughput DNA sequencing (ChIP-seq) and RNA-sequencing analyses reveal that nutritional signals induce dynamic XBP1s occupancy of promoters of COPII traffic-related genes, thereby driving the COPII-mediated trafficking process. Liver-specific disruption of the inositol-requiring enzyme 1α (IRE1α)-XBP1s signaling branch results in diminished COPII vesicle trafficking. Reactivation of XBP1s in mice lacking hepatic IRE1α restores COPII-mediated lipoprotein secretion and reverses the fatty liver and hypolipidemia phenotypes. Thus, our results demonstrate a previously unappreciated mechanism in the metabolic control of liver protein and lipid trafficking: The IRE1α-XBP1s axis functions as a nutrient-sensing regulatory nexus that integrates nutritional states and the COPII vesicle trafficking.
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17
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Enkavi G, Javanainen M, Kulig W, Róg T, Vattulainen I. Multiscale Simulations of Biological Membranes: The Challenge To Understand Biological Phenomena in a Living Substance. Chem Rev 2019; 119:5607-5774. [PMID: 30859819 PMCID: PMC6727218 DOI: 10.1021/acs.chemrev.8b00538] [Citation(s) in RCA: 173] [Impact Index Per Article: 34.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
![]()
Biological
membranes are tricky to investigate. They are complex
in terms of molecular composition and structure, functional
over a wide range of time scales, and characterized
by nonequilibrium conditions. Because of all of these
features, simulations are a great technique to study biomembrane
behavior. A significant part of the functional processes
in biological membranes takes place at the molecular
level; thus computer simulations are the method of
choice to explore how their properties emerge from specific
molecular features and how the interplay among the numerous
molecules gives rise to function over spatial and
time scales larger than the molecular ones. In this
review, we focus on this broad theme. We discuss the current
state-of-the-art of biomembrane simulations that, until
now, have largely focused on a rather narrow picture
of the complexity of the membranes. Given this, we
also discuss the challenges that we should unravel in the
foreseeable future. Numerous features such as the actin-cytoskeleton
network, the glycocalyx network, and nonequilibrium
transport under ATP-driven conditions have so far
received very little attention; however, the potential
of simulations to solve them would be exceptionally high. A
major milestone for this research would be that one day
we could say that computer simulations genuinely research
biological membranes, not just lipid bilayers.
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Affiliation(s)
- Giray Enkavi
- Department of Physics , University of Helsinki , P.O. Box 64, FI-00014 Helsinki , Finland
| | - Matti Javanainen
- Department of Physics , University of Helsinki , P.O. Box 64, FI-00014 Helsinki , Finland.,Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences , Flemingovo naḿesti 542/2 , 16610 Prague , Czech Republic.,Computational Physics Laboratory , Tampere University , P.O. Box 692, FI-33014 Tampere , Finland
| | - Waldemar Kulig
- Department of Physics , University of Helsinki , P.O. Box 64, FI-00014 Helsinki , Finland
| | - Tomasz Róg
- Department of Physics , University of Helsinki , P.O. Box 64, FI-00014 Helsinki , Finland.,Computational Physics Laboratory , Tampere University , P.O. Box 692, FI-33014 Tampere , Finland
| | - Ilpo Vattulainen
- Department of Physics , University of Helsinki , P.O. Box 64, FI-00014 Helsinki , Finland.,Computational Physics Laboratory , Tampere University , P.O. Box 692, FI-33014 Tampere , Finland.,MEMPHYS-Center for Biomembrane Physics
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18
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Alvim MCT, Vital CE, Barros E, Vieira NM, da Silveira FA, Balbino TR, Diniz RHS, Brito AF, Bazzolli DMS, de Oliveira Ramos HJ, da Silveira WB. Ethanol stress responses of Kluyveromyces marxianus CCT 7735 revealed by proteomic and metabolomic analyses. Antonie van Leeuwenhoek 2019; 112:827-845. [DOI: 10.1007/s10482-018-01214-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2018] [Accepted: 12/10/2018] [Indexed: 10/27/2022]
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19
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McCaughey J, Stevenson NL, Cross S, Stephens DJ. ER-to-Golgi trafficking of procollagen in the absence of large carriers. J Cell Biol 2018; 218:929-948. [PMID: 30587510 PMCID: PMC6400576 DOI: 10.1083/jcb.201806035] [Citation(s) in RCA: 62] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2018] [Revised: 10/17/2018] [Accepted: 12/06/2018] [Indexed: 01/28/2023] Open
Abstract
Trafficking of procollagen is essential for normal cell function. Here, imaging of GFP-tagged type I procollagen reveals that it is transported from the endoplasmic reticulum to the Golgi, without the use of large carriers. Secretion and assembly of collagen are fundamental to the function of the extracellular matrix. Defects in the assembly of a collagen matrix lead to pathologies including fibrosis and osteogenesis imperfecta. Owing to the size of fibril-forming procollagen molecules it is assumed that they are transported from the endoplasmic reticulum to the Golgi in specialized large COPII-dependent carriers. Here, analyzing endogenous procollagen and a new engineered GFP-tagged form, we show that transport to the Golgi occurs in the absence of large (>350 nm) carriers. Large GFP-positive structures were observed occasionally, but these were nondynamic, are not COPII positive, and are labeled with markers of the ER. We propose a short-loop model of COPII-dependent ER-to-Golgi traffic that, while consistent with models of ERGIC-dependent expansion of COPII carriers, does not invoke long-range trafficking of large vesicular structures. Our findings provide an important insight into the process of procollagen trafficking and reveal a short-loop pathway from the ER to the Golgi, without the use of large carriers.
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Affiliation(s)
- Janine McCaughey
- Cell Biology Laboratories, School of Biochemistry, Faculty of Life Sciences, University of Bristol, Bristol, UK
| | - Nicola L Stevenson
- Cell Biology Laboratories, School of Biochemistry, Faculty of Life Sciences, University of Bristol, Bristol, UK
| | - Stephen Cross
- Wolfson Bioimaging Facility, Faculty of Biomedical Sciences, University of Bristol, Bristol, UK
| | - David J Stephens
- Cell Biology Laboratories, School of Biochemistry, Faculty of Life Sciences, University of Bristol, Bristol, UK
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20
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Hanna MG, Peotter JL, Frankel EB, Audhya A. Membrane Transport at an Organelle Interface in the Early Secretory Pathway: Take Your Coat Off and Stay a While: Evolution of the metazoan early secretory pathway. Bioessays 2018; 40:e1800004. [PMID: 29741780 PMCID: PMC6166410 DOI: 10.1002/bies.201800004] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2018] [Revised: 04/09/2018] [Indexed: 01/25/2023]
Abstract
Most metazoan organisms have evolved a mildly acidified and calcium diminished sorting hub in the early secretory pathway commonly referred to as the Endoplasmic Reticulum-Golgi intermediate compartment (ERGIC). These membranous vesicular-tubular clusters are found tightly juxtaposed to ER subdomains that are competent for the production of COPII-coated transport carriers. In contrast to many unicellular systems, metazoan COPII carriers largely transit just a few hundred nanometers to the ERGIC, prior to COPI-dependent transport on to the cis-Golgi. The mechanisms underlying formation and maintenance of ERGIC membranes are poorly defined. However, recent evidence suggests an important role for Trk-fused gene (TFG) in regulating the integrity of the ER/ERGIC interface. Moreover, in the absence of cytoskeletal elements to scaffold tracks on which COPII carriers might move, TFG appears to promote anterograde cargo transport by locally tethering COPII carriers adjacent to ERGIC membranes. This action, regulated in part by the intrinsically disordered domain of TFG, provides sufficient time for COPII coat disassembly prior to heterotypic membrane fusion and cargo delivery to the ERGIC.
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Affiliation(s)
- Michael G. Hanna
- Department of Biomolecular Chemistry, University of Wisconsin-Madison School of Medicine and Public Health 440 Henry Mall, Madison, WI 53706, USA,
| | - Jennifer L. Peotter
- Department of Biomolecular Chemistry, University of Wisconsin-Madison School of Medicine and Public Health 440 Henry Mall, Madison, WI 53706, USA,
| | - E. B. Frankel
- Department of Biomolecular Chemistry, University of Wisconsin-Madison School of Medicine and Public Health 440 Henry Mall, Madison, WI 53706, USA,
| | - Anjon Audhya
- Department of Biomolecular Chemistry, University of Wisconsin-Madison School of Medicine and Public Health 440 Henry Mall, Madison, WI 53706, USA,
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21
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Wang B, Joo JH, Mount R, Teubner BJW, Krenzer A, Ward AL, Ichhaporia VP, Adams EJ, Khoriaty R, Peters ST, Pruett-Miller SM, Zakharenko SS, Ginsburg D, Kundu M. The COPII cargo adapter SEC24C is essential for neuronal homeostasis. J Clin Invest 2018; 128:3319-3332. [PMID: 29939162 DOI: 10.1172/jci98194] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2017] [Accepted: 05/08/2018] [Indexed: 12/17/2022] Open
Abstract
SEC24 family members are components of the coat protein complex II (COPII) machinery that interact directly with cargo or with other adapters to ensure proper sorting of secretory cargo into COPII vesicles. SEC24C is 1 of 4 mammalian SEC24 paralogs (SEC24A-D), which segregate into 2 subfamilies on the basis of sequence homology (SEC24A/SEC24B and SEC24C/SEC24D). Here, we demonstrate that postmitotic neurons, unlike professional secretory cells in other tissues, are exquisitely sensitive to loss of SEC24C. Conditional KO of Sec24c in neural progenitors during embryogenesis caused perinatal mortality and microcephaly, with activation of the unfolded protein response and apoptotic cell death of postmitotic neurons in the murine cerebral cortex. The cell-autonomous function of SEC24C in postmitotic neurons was further highlighted by the loss of cell viability caused by disrupting Sec24c expression in forebrain neurons of mice postnatally and in differentiated neurons derived from human induced pluripotent stem cells. The neuronal cell death associated with Sec24c deficiency was rescued in knockin mice expressing Sec24d in place of Sec24c. These data suggest that SEC24C is a major cargo adapter for COPII-dependent transport in postmitotic neurons in developing and adult brains and that its functions overlap at least partially with those of SEC24D in mammals.
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Affiliation(s)
- Bo Wang
- Department of Pathology.,Department of Cell and Molecular Biology
| | - Joung Hyuck Joo
- Department of Pathology.,Department of Cell and Molecular Biology
| | - Rebecca Mount
- Department of Pathology.,Department of Cell and Molecular Biology
| | | | - Alison Krenzer
- Department of Pathology.,Department of Cell and Molecular Biology
| | - Amber L Ward
- Department of Pathology.,Department of Cell and Molecular Biology
| | - Viraj P Ichhaporia
- Department of Tumor Cell Biology, St. Jude Children's Research Hospital, Memphis, Tennessee, USA
| | - Elizabeth J Adams
- Program in Cellular and Molecular Biology, University of Michigan, Ann Arbor, Michigan, USA
| | - Rami Khoriaty
- Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan, USA
| | - Samuel T Peters
- Department of Cell and Molecular Biology.,Center for Advanced Genome Engineering, St. Jude Children's Research Hospital, Memphis, Tennessee, USA
| | - Shondra M Pruett-Miller
- Department of Cell and Molecular Biology.,Center for Advanced Genome Engineering, St. Jude Children's Research Hospital, Memphis, Tennessee, USA
| | | | - David Ginsburg
- Program in Cellular and Molecular Biology, University of Michigan, Ann Arbor, Michigan, USA.,Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan, USA.,Howard Hughes Medical Institute, Life Sciences Institute, and Departments of Human Genetics and Pediatrics, University of Michigan, Ann Arbor, Michigan, USA
| | - Mondira Kundu
- Department of Pathology.,Department of Cell and Molecular Biology
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22
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Laloux T, Junqueira B, Maistriaux LC, Ahmed J, Jurkiewicz A, Chaumont F. Plant and Mammal Aquaporins: Same but Different. Int J Mol Sci 2018; 19:E521. [PMID: 29419811 PMCID: PMC5855743 DOI: 10.3390/ijms19020521] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Revised: 01/31/2018] [Accepted: 02/01/2018] [Indexed: 02/06/2023] Open
Abstract
Aquaporins (AQPs) constitute an ancient and diverse protein family present in all living organisms, indicating a common ancient ancestor. However, during evolution, these organisms appear and evolve differently, leading to different cell organizations and physiological processes. Amongst the eukaryotes, an important distinction between plants and animals is evident, the most conspicuous difference being that plants are sessile organisms facing ever-changing environmental conditions. In addition, plants are mostly autotrophic, being able to synthesize carbohydrates molecules from the carbon dioxide in the air during the process of photosynthesis, using sunlight as an energy source. It is therefore interesting to analyze how, in these different contexts specific to both kingdoms of life, AQP function and regulation evolved. This review aims at highlighting similarities and differences between plant and mammal AQPs. Emphasis is given to the comparison of isoform numbers, their substrate selectivity, the regulation of the subcellular localization, and the channel activity.
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Affiliation(s)
- Timothée Laloux
- Institut des Sciences de la Vie, Université catholique de Louvain, Croix du Sud 4-L7.07.14, B-1348 Louvain-la Neuve, Belgium.
| | - Bruna Junqueira
- Institut des Sciences de la Vie, Université catholique de Louvain, Croix du Sud 4-L7.07.14, B-1348 Louvain-la Neuve, Belgium.
| | - Laurie C Maistriaux
- Institut des Sciences de la Vie, Université catholique de Louvain, Croix du Sud 4-L7.07.14, B-1348 Louvain-la Neuve, Belgium.
| | - Jahed Ahmed
- Institut des Sciences de la Vie, Université catholique de Louvain, Croix du Sud 4-L7.07.14, B-1348 Louvain-la Neuve, Belgium.
| | - Agnieszka Jurkiewicz
- Institut des Sciences de la Vie, Université catholique de Louvain, Croix du Sud 4-L7.07.14, B-1348 Louvain-la Neuve, Belgium.
| | - François Chaumont
- Institut des Sciences de la Vie, Université catholique de Louvain, Croix du Sud 4-L7.07.14, B-1348 Louvain-la Neuve, Belgium.
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23
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Bird IM, Kim SH, Schweppe DK, Caetano-Lopes J, Robling AG, Charles JF, Gygi SP, Warman ML, Smits PJ. The skeletal phenotype of achondrogenesis type 1A is caused exclusively by cartilage defects. Development 2018; 145:dev.156588. [PMID: 29180569 PMCID: PMC5825869 DOI: 10.1242/dev.156588] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2017] [Accepted: 11/16/2017] [Indexed: 12/12/2022]
Abstract
Inactivating mutations in the ubiquitously expressed membrane trafficking component GMAP-210 (encoded by Trip11) cause achondrogenesis type 1A (ACG1A). ACG1A is surprisingly tissue specific, mainly affecting cartilage development. Bone development is also abnormal, but as chondrogenesis and osteogenesis are closely coupled, this could be a secondary consequence of the cartilage defect. A possible explanation for the tissue specificity of ACG1A is that cartilage and bone are highly secretory tissues with a high use of the membrane trafficking machinery. The perinatal lethality of ACG1A prevents investigating this hypothesis. We therefore generated mice with conditional Trip11 knockout alleles and inactivated Trip11 in chondrocytes, osteoblasts, osteoclasts and pancreas acinar cells, all highly secretory cell types. We discovered that the ACG1A skeletal phenotype is solely due to absence of GMAP-210 in chondrocytes. Mice lacking GMAP-210 in osteoblasts, osteoclasts and acinar cells were normal. When we inactivated Trip11 in primary chondrocyte cultures, GMAP-210 deficiency affected trafficking of a subset of chondrocyte-expressed proteins rather than globally impairing membrane trafficking. Thus, GMAP-210 is essential for trafficking specific cargoes in chondrocytes but is dispensable in other highly secretory cells. Summary: Conditional inactivation of the cis-Golgin GMAP-210 reveals that the skeletal phenotype in achondrogenesis type-1A, which is caused by mutations in GMAP-210, is solely due to impaired protein trafficking by chondrocytes.
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Affiliation(s)
- Ian M Bird
- Orthopaedic Research Laboratories, Department of Orthopaedic Surgery, Boston Children's Hospital, Boston, MA 02115, USA
| | - Susie H Kim
- Orthopaedic Research Laboratories, Department of Orthopaedic Surgery, Boston Children's Hospital, Boston, MA 02115, USA
| | - Devin K Schweppe
- Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA
| | - Joana Caetano-Lopes
- Orthopaedic Research Laboratories, Department of Orthopaedic Surgery, Boston Children's Hospital, Boston, MA 02115, USA
| | - Alexander G Robling
- Department of Anatomy and Cell Biology, Indiana University, Indianapolis, IN 46202, USA
| | - Julia F Charles
- Department of Medicine, Brigham and Women's Hospital, Boston, MA 02115, USA
| | - Steven P Gygi
- Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA
| | - Matthew L Warman
- Orthopaedic Research Laboratories, Department of Orthopaedic Surgery, Boston Children's Hospital, Boston, MA 02115, USA.,Howard Hughes Medical Institute, Boston Children's Hospital, Boston, MA 02115, USA.,Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
| | - Patrick J Smits
- Orthopaedic Research Laboratories, Department of Orthopaedic Surgery, Boston Children's Hospital, Boston, MA 02115, USA
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24
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TFG facilitates outer coat disassembly on COPII transport carriers to promote tethering and fusion with ER-Golgi intermediate compartments. Proc Natl Acad Sci U S A 2017; 114:E7707-E7716. [PMID: 28851831 DOI: 10.1073/pnas.1709120114] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The conserved coat protein complex II (COPII) mediates the initial steps of secretory protein trafficking by assembling onto subdomains of the endoplasmic reticulum (ER) in two layers to generate cargo-laden transport carriers that ultimately fuse with an adjacent ER-Golgi intermediate compartment (ERGIC). Here, we demonstrate that Trk-fused gene (TFG) binds directly to the inner layer of the COPII coat. Specifically, the TFG C terminus interacts with Sec23 through a shared interface with the outer COPII coat and the cargo receptor Tango1/cTAGE5. Our findings indicate that TFG binding to Sec23 outcompetes these other associations in a concentration-dependent manner and ultimately promotes outer coat dissociation. Additionally, we demonstrate that TFG tethers vesicles harboring the inner COPII coat, which contributes to their clustering between the ER and ERGIC in cells. Together, our studies define a mechanism by which COPII transport carriers are retained locally at the ER/ERGIC interface after outer coat disassembly, which is a prerequisite for fusion with ERGIC membranes.
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25
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Tang BL. Sec16 in conventional and unconventional exocytosis: Working at the interface of membrane traffic and secretory autophagy? J Cell Physiol 2017; 232:3234-3243. [PMID: 28160489 DOI: 10.1002/jcp.25842] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Accepted: 02/03/2017] [Indexed: 12/22/2022]
Abstract
Sec16 is classically perceived to be a scaffolding protein localized to the transitional endoplasmic reticulum (tER) or the ER exit sites (ERES), and has a conserved function in facilitating coat protein II (COPII) complex-mediated ER exit. Recent findings have, however, pointed toward a role for Sec16 in unconventional exocytosis of certain membrane proteins, such as the Cystic fibrosis transmembrane conductance regulator (CFTR) in mammalian cells, and possibly also α-integrin in certain contexts of Drosophila development. In this regard, Sec16 interacts with components of a recently deciphered pathway of stress-induced unconventional exocytosis, which is dependent on the tether protein Golgi reassembly stacking proteins (GRASPs) and the autophagy pathway. Intriguingly, Sec16 also appears to be post-translationally modified by autophagy-related signaling processes. Sec16 is known to be phosphorylated by the atypical extracellular signal regulated kinase 7 (Erk7) upon serum and amino acid starvation, both represent conditions that trigger autophagy. Recent work has also shown that Sec16 is phosphorylated, and thus regulated by the prominent autophagy-initiating Unc-51-like autophagy activating kinase 1 (Ulk1), as well as another autophagy modulator Leucine-rich repeat kinase 2 (Lrrk2). The picture emerging from Sec16's network of physical and functional interactors allows the speculation that Sec16 is situated (and may in yet undefined ways function) at the interface between COPII-mediated exocytosis of conventional vesicular traffic and the GRASP/autophagy-dependent mode of unconventional exocytosis.
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Affiliation(s)
- Bor Luen Tang
- Departmentof Biochemistry, Yong Loo Lin School of Medicine, National University Health System, Singapore.,NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore
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26
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Rodrigues FF, Harris TJC. Key roles of Arf small G proteins and biosynthetic trafficking for animal development. Small GTPases 2017; 10:403-410. [PMID: 28410007 DOI: 10.1080/21541248.2017.1304854] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
Abstract
Although biosynthetic trafficking can function constitutively, it also functions specifically for certain developmental processes. These processes require either a large increase to biosynthesis or the biosynthesis and targeted trafficking of specific players. We review the conserved molecular mechanisms that direct biosynthetic trafficking, and discuss how their genetic disruption affects animal development. Specifically, we consider Arf small G proteins, such as Arf1 and Sar1, and their coat effectors, COPI and COPII, and how these proteins promote biosynthetic trafficking for cleavage of the Drosophila embryo, the growth of neuronal dendrites and synapses, extracellular matrix secretion for bone development, lumen development in epithelial tubes, notochord and neural tube development, and ciliogenesis. Specific need for the biosynthetic trafficking system is also evident from conserved CrebA/Creb3-like transcription factors increasing the expression of secretory machinery during several of these developmental processes. Moreover, dysfunctional trafficking leads to a range of developmental syndromes.
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Affiliation(s)
- Francisco F Rodrigues
- Department of Cell & Systems Biology, University of Toronto , Toronto , Ontario , Canada
| | - Tony J C Harris
- Department of Cell & Systems Biology, University of Toronto , Toronto , Ontario , Canada
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27
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Chung KP, Zeng Y, Jiang L. COPII Paralogs in Plants: Functional Redundancy or Diversity? TRENDS IN PLANT SCIENCE 2016; 21:758-769. [PMID: 27317568 DOI: 10.1016/j.tplants.2016.05.010] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2016] [Revised: 05/27/2016] [Accepted: 05/27/2016] [Indexed: 05/04/2023]
Abstract
In eukaryotes, the best-described mechanism of endoplasmic reticulum (ER) export is mediated by coat protein complex II (COPII) vesicles, which comprise five conserved cytosolic components [secretion-associated, Ras-related protein 1 (Sar1), Sec23-24, and Sec13-31]. In higher organisms, multiple paralogs of COPII components are created due to gene duplication. However, the functional diversity of plant COPII subunit isoforms remains largely elusive. Here we summarize and discuss the latest findings derived from studies of various arabidopsis COPII subunit isoforms and their functional diversity. We also put forward testable hypotheses on distinct populations of COPII vesicles performing unique functions in ER export in developmental and stress-related pathways in plants.
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Affiliation(s)
- Kin Pan Chung
- Centre for Cell and Developmental Biology and State Key Laboratory of Agrobiotechnology, School of Life Sciences, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong SAR, China
| | - Yonglun Zeng
- Centre for Cell and Developmental Biology and State Key Laboratory of Agrobiotechnology, School of Life Sciences, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong SAR, China
| | - Liwen Jiang
- Centre for Cell and Developmental Biology and State Key Laboratory of Agrobiotechnology, School of Life Sciences, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong SAR, China.
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28
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Yonemura Y, Li X, Müller K, Krämer A, Atigbire P, Mentrup T, Feuerhake T, Kroll T, Shomron O, Nohl R, Arndt HD, Hoischen C, Hemmerich P, Hirschberg K, Kaether C. Inhibition of cargo export at ER exit sites and the trans-Golgi network by the secretion inhibitor FLI-06. J Cell Sci 2016; 129:3868-3877. [PMID: 27587840 DOI: 10.1242/jcs.186163] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2016] [Accepted: 08/25/2016] [Indexed: 12/21/2022] Open
Abstract
Export out of the endoplasmic reticulum (ER) involves the Sar1 and COPII machinery acting at ER exit sites (ERES). Whether and how cargo proteins are recruited upstream of Sar1 and COPII is unclear. Two models are conceivable, a recruitment model where cargo is actively transported through a transport factor and handed over to the Sar1 and COPII machinery in ERES, and a capture model, where cargo freely diffuses into ERES where it is captured by the Sar1 and COPII machinery. Using the novel secretion inhibitor FLI-06, we show that recruitment of the cargo VSVG to ERES is an active process upstream of Sar1 and COPII. Applying FLI-06 before concentration of VSVG in ERES completely abolishes its recruitment. In contrast, applying FLI-06 after VSVG concentration in ERES does not lead to dispersal of the concentrated VSVG, arguing that it inhibits recruitment to ERES as opposed to capture in ERES. FLI-06 also inhibits export out of the trans-Golgi network (TGN), suggesting that similar mechanisms might orchestrate cargo selection and concentration at the ER and TGN. FLI-06 does not inhibit autophagosome biogenesis and the ER-peroxisomal transport route, suggesting that these rely on different mechanisms.
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Affiliation(s)
- Yoji Yonemura
- Leibniz Institut für Alternsforschung-Fritz Lipmann Institut, Jena 07745, Germany
| | - Xiaolin Li
- Leibniz Institut für Alternsforschung-Fritz Lipmann Institut, Jena 07745, Germany
| | - Katja Müller
- Leibniz Institut für Alternsforschung-Fritz Lipmann Institut, Jena 07745, Germany
| | - Andreas Krämer
- Leibniz Institut für Alternsforschung-Fritz Lipmann Institut, Jena 07745, Germany
| | - Paul Atigbire
- Leibniz Institut für Alternsforschung-Fritz Lipmann Institut, Jena 07745, Germany
| | - Torben Mentrup
- Leibniz Institut für Alternsforschung-Fritz Lipmann Institut, Jena 07745, Germany
| | - Talitha Feuerhake
- Leibniz Institut für Alternsforschung-Fritz Lipmann Institut, Jena 07745, Germany
| | - Torsten Kroll
- Leibniz Institut für Alternsforschung-Fritz Lipmann Institut, Jena 07745, Germany
| | - Olga Shomron
- Pathology Department, Sackler School of Medicine, Tel-Aviv University, Tel-Aviv 69978, Israel
| | - Richard Nohl
- Lehrstuhl für organische Chemie I, Friedrich-Schiller Universität, Jena 07743, Germany
| | - Hans-Dieter Arndt
- Lehrstuhl für organische Chemie I, Friedrich-Schiller Universität, Jena 07743, Germany
| | - Christian Hoischen
- Leibniz Institut für Alternsforschung-Fritz Lipmann Institut, Jena 07745, Germany
| | - Peter Hemmerich
- Leibniz Institut für Alternsforschung-Fritz Lipmann Institut, Jena 07745, Germany
| | - Koret Hirschberg
- Pathology Department, Sackler School of Medicine, Tel-Aviv University, Tel-Aviv 69978, Israel
| | - Christoph Kaether
- Leibniz Institut für Alternsforschung-Fritz Lipmann Institut, Jena 07745, Germany
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29
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Maki M, Takahara T, Shibata H. Multifaceted Roles of ALG-2 in Ca(2+)-Regulated Membrane Trafficking. Int J Mol Sci 2016; 17:ijms17091401. [PMID: 27571067 PMCID: PMC5037681 DOI: 10.3390/ijms17091401] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2016] [Revised: 08/18/2016] [Accepted: 08/19/2016] [Indexed: 12/15/2022] Open
Abstract
ALG-2 (gene name: PDCD6) is a penta-EF-hand Ca2+-binding protein and interacts with a variety of proteins in a Ca2+-dependent fashion. ALG-2 recognizes different types of identified motifs in Pro-rich regions by using different hydrophobic pockets, but other unknown modes of binding are also used for non-Pro-rich proteins. Most ALG-2-interacting proteins associate directly or indirectly with the plasma membrane or organelle membranes involving the endosomal sorting complex required for transport (ESCRT) system, coat protein complex II (COPII)-dependent ER-to-Golgi vesicular transport, and signal transduction from membrane receptors to downstream players. Binding of ALG-2 to targets may induce conformational change of the proteins. The ALG-2 dimer may also function as a Ca2+-dependent adaptor to bridge different partners and connect the subnetwork of interacting proteins.
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Affiliation(s)
- Masatoshi Maki
- Department of Applied Molecular Biosciences, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan.
| | - Terunao Takahara
- Department of Applied Molecular Biosciences, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan.
| | - Hideki Shibata
- Department of Applied Molecular Biosciences, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan.
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30
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Ugalde-Silva P, Gonzalez-Lugo O, Navarro-Garcia F. Tight Junction Disruption Induced by Type 3 Secretion System Effectors Injected by Enteropathogenic and Enterohemorrhagic Escherichia coli. Front Cell Infect Microbiol 2016; 6:87. [PMID: 27606286 PMCID: PMC4995211 DOI: 10.3389/fcimb.2016.00087] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2016] [Accepted: 08/10/2016] [Indexed: 12/18/2022] Open
Abstract
The intestinal epithelium consists of a single cell layer, which is a critical selectively permeable barrier to both absorb nutrients and avoid the entry of potentially harmful entities, including microorganisms. Epithelial cells are held together by the apical junctional complexes, consisting of adherens junctions, and tight junctions (TJs), and by underlying desmosomes. TJs lay in the apical domain of epithelial cells and are mainly composed by transmembrane proteins such as occludin, claudins, JAMs, and tricellulin, that are associated with the cytoplasmic plaque formed by proteins from the MAGUK family, such as ZO-1/2/3, connecting TJ to the actin cytoskeleton, and cingulin and paracingulin connecting TJ to the microtubule network. Extracellular bacteria such as EPEC and EHEC living in the intestinal lumen inject effectors proteins directly from the bacterial cytoplasm to the host cell cytoplasm, where they play a relevant role in the manipulation of the eukaryotic cell functions by modifying or blocking cell signaling pathways. TJ integrity depends on various cell functions such as actin cytoskeleton, microtubule network for vesicular trafficking, membrane integrity, inflammation, and cell survival. EPEC and EHEC effectors target most of these functions. Effectors encoded inside or outside of locus of enterocyte effacement (LEE) disrupt the TJ strands. EPEC and EHEC exploit the TJ dynamics to open this structure, for causing diarrhea. EPEC and EHEC secrete effectors that mimic host proteins to manipulate the signaling pathways, including those related to TJ dynamics. In this review, we focus on the known mechanisms exploited by EPEC and EHEC effectors for causing TJ disruption.
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Affiliation(s)
- Paul Ugalde-Silva
- Department of Cell Biology, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional México City, Mexico
| | - Octavio Gonzalez-Lugo
- Department of Cell Biology, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional México City, Mexico
| | - Fernando Navarro-Garcia
- Department of Cell Biology, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional México City, Mexico
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31
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Bustos-Morán E, Blas-Rus N, Martín-Cófreces NB, Sánchez-Madrid F. Orchestrating Lymphocyte Polarity in Cognate Immune Cell-Cell Interactions. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2016; 327:195-261. [PMID: 27692176 DOI: 10.1016/bs.ircmb.2016.06.004] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The immune synapse (IS) is a specialized structure established between different immune cells that fulfills several functions, including a role as a communication bridge. This intimate contact between a T cell and an antigen-presenting cell promotes the proliferation and differentiation of lymphocytes involved in the contact. T-cell activation requires the specific triggering of the T-cell receptor (TCR), which promotes the activation of different signaling pathways inducing the polarization of the T cell. During this process, different adhesion and signaling receptors reorganize at specialized membrane domains, concomitantly to the polarization of the tubulin and actin cytoskeletons, forming stable polarization platforms. The centrosome also moves toward the IS, driving the movement of different organelles, such as the biosynthetic, secretory, degrading machinery, and mitochondria, to sustain T-cell activation. A proper orchestration of all these events is essential for T-cell effector functions and the accomplishment of a complete immune response.
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Affiliation(s)
- Eugenio Bustos-Morán
- Vascular Pathophysiology Area, Spanish National Center of Cardiovascular Research (CNIC), Madrid, Spain
| | - Noelia Blas-Rus
- Department of Immunology, La Princesa Hospital, Autonomus University of Madrid (UAM), Health Research Institute of Princesa Hospital (ISS-IP), Madrid, Spain
| | - Noa Beatriz Martín-Cófreces
- Vascular Pathophysiology Area, Spanish National Center of Cardiovascular Research (CNIC), Madrid, Spain.,Department of Immunology, La Princesa Hospital, Autonomus University of Madrid (UAM), Health Research Institute of Princesa Hospital (ISS-IP), Madrid, Spain
| | - Francisco Sánchez-Madrid
- Vascular Pathophysiology Area, Spanish National Center of Cardiovascular Research (CNIC), Madrid, Spain.,Department of Immunology, La Princesa Hospital, Autonomus University of Madrid (UAM), Health Research Institute of Princesa Hospital (ISS-IP), Madrid, Spain
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32
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Maeda M, Saito K, Katada T. Distinct isoform-specific complexes of TANGO1 cooperatively facilitate collagen secretion from the endoplasmic reticulum. Mol Biol Cell 2016; 27:2688-96. [PMID: 27413011 PMCID: PMC5007089 DOI: 10.1091/mbc.e16-03-0196] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2016] [Accepted: 07/08/2016] [Indexed: 11/11/2022] Open
Abstract
The short isoform of TANGO1, termed TANGO1S, is necessary for collagen secretion from the ER independently of TANGO1L. TANGO1L and TANGO1S form individual complexes at ER exit sites and cooperatively participate in collagen export from the ER. Collagens synthesized within the endoplasmic reticulum (ER) are too large to fit in conventional COPII-coated transport vesicles; thus their export from the ER requires specialized factors. TANGO1 (L) is an integral membrane protein that binds to collagen and the coatomer of vesicles and is necessary for collagen secretion from the ER. Here we characterized the short isoform of TANGO1 (TANGO1S), lacking the collagen-binding domain, and found that it was independently required for collagen export from the ER. Moreover, we found that each of the TANGO1 isoforms forms a stable protein complex with factors involved in collagen secretion: TANGO1L/cTAGE5/Sec12 (900 kDa) and TANGO1S/cTAGE5/Sec12 (700 kDa). Of interest, TANGO1S and TANGO1L seemed to be interchangeable in exporting collagen from the ER. Our results suggest that mammalian ER exit sites possess two different-sized membrane-bound macromolecular complexes that specifically function in large-cargo export from the ER.
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Affiliation(s)
- Miharu Maeda
- Department of Physiological Chemistry, Graduate School of Pharmaceutical Sciences, University of Tokyo, Tokyo 113-0033, Japan
| | - Kota Saito
- Department of Physiological Chemistry, Graduate School of Pharmaceutical Sciences, University of Tokyo, Tokyo 113-0033, Japan
| | - Toshiaki Katada
- Department of Physiological Chemistry, Graduate School of Pharmaceutical Sciences, University of Tokyo, Tokyo 113-0033, Japan
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33
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TFG Promotes Organization of Transitional ER and Efficient Collagen Secretion. Cell Rep 2016; 15:1648-59. [PMID: 27184855 PMCID: PMC4885023 DOI: 10.1016/j.celrep.2016.04.062] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2016] [Revised: 03/16/2016] [Accepted: 04/15/2016] [Indexed: 12/30/2022] Open
Abstract
Collagen is the most abundant protein in the animal kingdom. It is of fundamental importance during development for cell differentiation and tissue morphogenesis as well as in pathological processes such as fibrosis and cancer cell migration. However, our understanding of the mechanisms of procollagen secretion remains limited. Here, we show that TFG organizes transitional ER (tER) and ER exit sites (ERESs) into larger structures. Depletion of TFG results in dispersion of tER elements that remain associated with individual ER-Golgi intermediate compartments (ERGICs) as largely functional ERESs. We show that TFG is not required for the transport and packaging of small soluble cargoes but is necessary for the export of procollagen from the ER. Our work therefore suggests a key relationship between the structure and function of ERESs and a central role for TFG in optimizing COPII assembly for procollagen export.
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34
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Hanadate Y, Saito-Nakano Y, Nakada-Tsukui K, Nozaki T. Endoplasmic reticulum-resident Rab8A GTPase is involved in phagocytosis in the protozoan parasite Entamoeba histolytica. Cell Microbiol 2016; 18:1358-73. [PMID: 26807810 PMCID: PMC5071775 DOI: 10.1111/cmi.12570] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2015] [Revised: 12/31/2015] [Accepted: 01/19/2016] [Indexed: 12/20/2022]
Abstract
Phagocytosis is indispensable for the pathogenesis of the intestinal protozoan parasite Entamoeba histolytica. Here, we showed that in E. histolytica Rab8A, which is generally involved in trafficking from the trans‐Golgi network to the plasma membrane in other organisms but was previously identified in phagosomes of the amoeba in the proteomic analysis, primarily resides in the endoplasmic reticulum (ER) and participates in phagocytosis. We demonstrated that down‐regulation of EhRab8A by small antisense RNA‐mediated transcriptional gene silencing remarkably reduced adherence and phagocytosis of erythrocytes, bacteria and carboxylated latex beads. Surface biotinylation followed by SDS‐PAGE analysis revealed that the surface expression of several proteins presumably involved in target recognition was reduced in the EhRab8A gene‐silenced strain. Further, overexpression of wild‐type EhRab8A augmented phagocytosis, whereas expression of the dominant‐negative form of EhRab8A resulted in reduced phagocytosis. These results indicated that EhRab8A regulates transport of surface receptor(s) for the prey from the ER to the plasma membrane. To our knowledge, this is the first report that the ER‐resident Rab GTPase is involved in phagocytosis through the regulation of trafficking of a surface receptor, supporting a premise of direct involvement of the ER in phagocytosis.
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Affiliation(s)
- Yuki Hanadate
- Department of Parasitology, National Institute of Infectious Diseases, 1-23-1 Toyama, Shinjuku-ku, Tokyo, 162-8640, Japan.,Graduate School of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8572, Japan
| | - Yumiko Saito-Nakano
- Department of Parasitology, National Institute of Infectious Diseases, 1-23-1 Toyama, Shinjuku-ku, Tokyo, 162-8640, Japan
| | - Kumiko Nakada-Tsukui
- Department of Parasitology, National Institute of Infectious Diseases, 1-23-1 Toyama, Shinjuku-ku, Tokyo, 162-8640, Japan
| | - Tomoyoshi Nozaki
- Department of Parasitology, National Institute of Infectious Diseases, 1-23-1 Toyama, Shinjuku-ku, Tokyo, 162-8640, Japan. .,Graduate School of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8572, Japan.
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35
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Hanna MG, Mela I, Wang L, Henderson RM, Chapman ER, Edwardson JM, Audhya A. Sar1 GTPase Activity Is Regulated by Membrane Curvature. J Biol Chem 2015; 291:1014-27. [PMID: 26546679 PMCID: PMC4714187 DOI: 10.1074/jbc.m115.672287] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2015] [Indexed: 12/15/2022] Open
Abstract
The majority of biosynthetic secretory proteins initiate their journey through the endomembrane system from specific subdomains of the endoplasmic reticulum. At these locations, coated transport carriers are generated, with the Sar1 GTPase playing a critical role in membrane bending, recruitment of coat components, and nascent vesicle formation. How these events are appropriately coordinated remains poorly understood. Here, we demonstrate that Sar1 acts as the curvature-sensing component of the COPII coat complex and highlight the ability of Sar1 to bind more avidly to membranes of high curvature. Additionally, using an atomic force microscopy-based approach, we further show that the intrinsic GTPase activity of Sar1 is necessary for remodeling lipid bilayers. Consistent with this idea, Sar1-mediated membrane remodeling is dramatically accelerated in the presence of its guanine nucleotide-activating protein (GAP), Sec23-Sec24, and blocked upon addition of guanosine-5′-[(β,γ)-imido]triphosphate, a poorly hydrolysable analog of GTP. Our results also indicate that Sar1 GTPase activity is stimulated by membranes that exhibit elevated curvature, potentially enabling Sar1 membrane scission activity to be spatially restricted to highly bent membranes that are characteristic of a bud neck. Taken together, our data support a stepwise model in which the amino-terminal amphipathic helix of GTP-bound Sar1 stably penetrates the endoplasmic reticulum membrane, promoting local membrane deformation. As membrane bending increases, Sar1 membrane binding is elevated, ultimately culminating in GTP hydrolysis, which may destabilize the bilayer sufficiently to facilitate membrane fission.
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Affiliation(s)
- Michael G Hanna
- From the Department of Biomolecular Chemistry, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin 53706
| | - Ioanna Mela
- the Department of Pharmacology, University of Cambridge, Tennis Court Road, CB2 1PD Cambridge, United Kingdom, and
| | - Lei Wang
- From the Department of Biomolecular Chemistry, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin 53706
| | - Robert M Henderson
- the Department of Pharmacology, University of Cambridge, Tennis Court Road, CB2 1PD Cambridge, United Kingdom, and
| | - Edwin R Chapman
- the Department of Neuroscience, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin 53705
| | - J Michael Edwardson
- the Department of Pharmacology, University of Cambridge, Tennis Court Road, CB2 1PD Cambridge, United Kingdom, and
| | - Anjon Audhya
- From the Department of Biomolecular Chemistry, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin 53706,
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36
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Saito K, Katada T. Mechanisms for exporting large-sized cargoes from the endoplasmic reticulum. Cell Mol Life Sci 2015; 72:3709-20. [PMID: 26082182 PMCID: PMC4565863 DOI: 10.1007/s00018-015-1952-9] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2015] [Revised: 05/18/2015] [Accepted: 06/08/2015] [Indexed: 12/14/2022]
Abstract
Cargo proteins exported from the endoplasmic reticulum to the Golgi apparatus are typically transported in coat protein complex II (COPII)-coated vesicles of 60–90 nm diameter. Several cargo molecules including collagens and chylomicrons form structures that are too large to be accommodated by these vesicles, but their secretion still requires COPII proteins. Here, we first review recent progress on large cargo secretions derived especially from animal models and human diseases, which indicate the importance of COPII proteins. We then discuss the recent isolation of specialized factors that modulate the process of COPII-dependent cargo formation to facilitate the exit of large-sized cargoes from the endoplasmic reticulum. Based on these findings, we propose a model that describes the importance of the GTPase cycle for secretion of oversized cargoes. Next, we summarize reports that describe the structures of COPII proteins and how these results provide insight into the mechanism of assembly of the large cargo carriers. Finally, we discuss what issues remain to be solved in the future.
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Affiliation(s)
- Kota Saito
- Department of Physiological Chemistry, Graduate School of Pharmaceutical Sciences, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan.
| | - Toshiaki Katada
- Department of Physiological Chemistry, Graduate School of Pharmaceutical Sciences, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan
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37
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Hedrich R, Sauer N, Neuhaus HE. Sugar transport across the plant vacuolar membrane: nature and regulation of carrier proteins. CURRENT OPINION IN PLANT BIOLOGY 2015; 25:63-70. [PMID: 26000864 DOI: 10.1016/j.pbi.2015.04.008] [Citation(s) in RCA: 81] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2014] [Revised: 04/16/2015] [Accepted: 04/30/2015] [Indexed: 05/06/2023]
Abstract
The ability of higher plants to store sugars is of crucial importance for plant development, adaption to endogenous or environmental cues and for the economic value of crop species. Sugar storage and accumulation, and its homeostasis in plant cells are managed by the vacuole. Although transport of sugars across the vacuolar membrane has been monitored for about four decades, the molecular entities of the transporters involved have been identified in the last 10 years only. Thus, it is just recently that our pictures of the transporters that channel the sugar load across the tonoplast have gained real shape. Here we describe the molecular nature and regulation of an important group of tonoplast sugar transporter (TST) allowing accumulation of sugars against large concentration gradients. In addition, we report on proton-driven tonoplast sugar exporters and on facilitators, which are also involved in balancing cytosolic and vacuolar sugar levels.
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Affiliation(s)
- Rainer Hedrich
- Molecular Plant Physiology and Biophysics, University of Würzburg, Germany
| | - Norbert Sauer
- Molecular Plant Physiology, University of Erlangen-Nuremberg, Germany
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38
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Hua R, Gidda SK, Aranovich A, Mullen RT, Kim PK. Multiple Domains in PEX16 Mediate Its Trafficking and Recruitment of Peroxisomal Proteins to the ER. Traffic 2015; 16:832-52. [PMID: 25903784 DOI: 10.1111/tra.12292] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2015] [Revised: 04/09/2015] [Accepted: 04/09/2015] [Indexed: 12/27/2022]
Abstract
Peroxisomes rely on a diverse array of mechanisms to ensure the specific targeting of their protein constituents. Peroxisomal membrane proteins (PMPs), for instance, are targeted by at least two distinct pathways: directly to peroxisomes from their sites of synthesis in the cytosol or indirectly via the endoplasmic reticulum (ER). However, the extent to which each PMP targeting pathway is involved in the maintenance of pre-existing peroxisomes is unclear. Recently, we showed that human PEX16 plays a critical role in the ER-dependent targeting of PMPs by mediating the recruitment of two other PMPs, PEX3 and PMP34, to the ER. Here, we extend these results by carrying out a comprehensive mutational analysis of PEX16 aimed at gaining insights into the molecular targeting signals responsible for its ER-to-peroxisome trafficking and the domain(s) involved in PMP recruitment function at the ER. We also show that the recruitment of PMPs to the ER by PEX16 is conserved in plants. The implications of these results in terms of the function of PEX16 and the role of the ER in peroxisome maintenance in general are discussed.
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Affiliation(s)
- Rong Hua
- Program in Cell Biology, Hospital for Sick Children, Toronto, ON, Canada M5G 0A4.,Department of Biochemistry, University of Toronto, Toronto, ON, Canada M5G 1A8
| | - Satinder K Gidda
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON, Canada N1G 2W1
| | - Alexander Aranovich
- Program in Cell Biology, Hospital for Sick Children, Toronto, ON, Canada M5G 0A4
| | - Robert T Mullen
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON, Canada N1G 2W1
| | - Peter K Kim
- Program in Cell Biology, Hospital for Sick Children, Toronto, ON, Canada M5G 0A4.,Department of Biochemistry, University of Toronto, Toronto, ON, Canada M5G 1A8
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39
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Daum S, Krüger D, Meister A, Auerswald J, Prinz S, Briggs JAG, Bacia K. Insights from reconstitution reactions of COPII vesicle formation using pure components and low mechanical perturbation. Biol Chem 2015; 395:801-12. [PMID: 25003385 DOI: 10.1515/hsz-2014-0117] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2014] [Accepted: 06/12/2014] [Indexed: 01/24/2023]
Abstract
As shape transformations of membranes are vital for intracellular trafficking, it is crucial to understand both the mechanics and the biochemistry of these processes. The interplay of these two factors constitutes an experimental challenge, however, because biochemical experiments are not tailored to the investigation of mechanical processes, and biophysical studies using model membranes are not capable of emulating native biological complexity. Reconstituted liposome-based model systems have been widely used for investigating the formation of transport vesicles by the COPII complex that naturally occurs at the endoplasmic reticulum. Here we have revisited these model systems, to address the influence of lipid composition, GTP hydrolyzing conditions and mechanical perturbation on the experimental outcome. We observed that the lipid-dependence of COPII-induced membrane remodeling differs from that predicted based on the lipid-dependence of COPII membrane binding. Under GTP non-hydrolyzing conditions, a structured coat was seen while GTP-hydrolyzing conditions yielded uncoated membranes as well as membranes coated by a thick protein coat of rather unstructured appearance. Detailed up-to-date protocols for purifications of Saccharomyces cerevisiae COPII proteins and for reconstituted reactions using these proteins with giant liposomes are also provided.
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40
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Kumichel A, Kapp K, Knust E. A Conserved Di-Basic Motif of Drosophila Crumbs Contributes to Efficient ER Export. Traffic 2015; 16:604-16. [PMID: 25753515 PMCID: PMC6681134 DOI: 10.1111/tra.12273] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2013] [Revised: 02/10/2015] [Accepted: 02/10/2015] [Indexed: 12/31/2022]
Abstract
The Drosophila type I transmembrane protein Crumbs is an apical determinant required for the maintenance of apico‐basal epithelial cell polarity. The level of Crumbs at the plasma membrane is crucial, but how it is regulated is poorly understood. In a genetic screen for regulators of Crumbs protein trafficking we identified Sar1, the core component of the coat protein complex II transport vesicles. sar1 mutant embryos show a reduced plasma membrane localization of Crumbs, a defect similar to that observed in haunted and ghost mutant embryos, which lack Sec23 and Sec24CD, respectively. By pulse‐chase assays in Drosophila Schneider cells and analysis of protein transport kinetics based on Endoglycosidase H resistance we identified an RNKR motif in Crumbs, which contributes to efficient ER export. The motif identified fits the highly conserved di‐basic RxKR motif and mediates interaction with Sar1. The RNKR motif is also required for plasma membrane delivery of transgene‐encoded Crumbs in epithelial cells of Drosophila embryos. Our data are the first to show that a di‐basic motif acts as a signal for ER exit of a type I plasma membrane protein in a metazoan organism.
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Affiliation(s)
- Alexandra Kumichel
- Max Planck Institute of Molecular Cell Biology and GeneticsPfotenhauerstr.10801307DresdenGermany
- Present address: Membrane Traffic and Cell Division, Institut Pasteur28 rue du Dr Roux75724 ParisFrance
| | - Katja Kapp
- Max Planck Institute of Molecular Cell Biology and GeneticsPfotenhauerstr.10801307DresdenGermany
| | - Elisabeth Knust
- Max Planck Institute of Molecular Cell Biology and GeneticsPfotenhauerstr.10801307DresdenGermany
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41
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Wang ZH, Rabouille C, Geisbrecht ER. Loss of a Clueless-dGRASP complex results in ER stress and blocks Integrin exit from the perinuclear endoplasmic reticulum in Drosophila larval muscle. Biol Open 2015; 4:636-48. [PMID: 25862246 PMCID: PMC4434815 DOI: 10.1242/bio.201511551] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Drosophila Clueless (Clu) and its conserved orthologs are known for their role in the prevention of mitochondrial clustering. Here, we uncover a new role for Clu in the delivery of integrin subunits in muscle tissue. In clu mutants, αPS2 integrin, but not βPS integrin, abnormally accumulates in a perinuclear endoplasmic reticulum (ER) subdomain, a site that mirrors the endogenous localization of Clu. Loss of components essential for mitochondrial distribution do not phenocopy the clu mutant αPS2 phenotype. Conversely, RNAi knockdown of the DrosophilaGolgi reassembly and stacking protein GRASP55/65 (dGRASP) recapitulates clu defects, including the abnormal accumulation of αPS2 and larval locomotor activity. Both Clu and dGRASP proteins physically interact and loss of Clu displaces dGRASP from ER exit sites, suggesting that Clu cooperates with dGRASP for the exit of αPS2 from a perinuclear subdomain in the ER. We also found that Clu and dGRASP loss of function leads to ER stress and that the stability of the ER exit site protein Sec16 is severely compromised in the clu mutants, thus explaining the ER accumulation of αPS2. Remarkably, exposure of clu RNAi larvae to chemical chaperones restores both αPS2 delivery and functional ER exit sites. We propose that Clu together with dGRASP prevents ER stress and therefore maintains Sec16 stability essential for the functional organization of perinuclear early secretory pathway. This, in turn, is essential for integrin subunit αPS2 ER exit in Drosophila larval myofibers.
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Affiliation(s)
- Zong-Heng Wang
- Division of Cell Biology and Biophysics, School of Biological Sciences, University of Missouri, Kansas City, MO 64110, USA
| | - Catherine Rabouille
- Hubrecht Institute-KNAW & University Medical Center Utrecht, 3584 CT Utrecht, The Netherlands The Department of Cell Biology, UMC Utrecht, 3584 CX Utrecht, The Netherlands
| | - Erika R Geisbrecht
- Division of Cell Biology and Biophysics, School of Biological Sciences, University of Missouri, Kansas City, MO 64110, USA Department of Biochemistry and Molecular Biophysics, Kansas State University, Manhattan, KS 66506, USA
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42
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Mutations in SEC24D, encoding a component of the COPII machinery, cause a syndromic form of osteogenesis imperfecta. Am J Hum Genet 2015; 96:432-9. [PMID: 25683121 DOI: 10.1016/j.ajhg.2015.01.002] [Citation(s) in RCA: 113] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2014] [Accepted: 01/05/2015] [Indexed: 11/23/2022] Open
Abstract
As a result of a whole-exome sequencing study, we report three mutant alleles in SEC24D, a gene encoding a component of the COPII complex involved in protein export from the ER: the truncating mutation c.613C>T (p.Gln205(∗)) and the missense mutations c.3044C>T (p.Ser1015Phe, located in a cargo-binding pocket) and c.2933A>C (p.Gln978Pro, located in the gelsolin-like domain). Three individuals from two families affected by a similar skeletal phenotype were each compound heterozygous for two of these mutant alleles, with c.3044C>T being embedded in a 14 Mb founder haplotype shared by all three. The affected individuals were a 7-year-old boy with a phenotype most closely resembling Cole-Carpenter syndrome and two fetuses initially suspected to have a severe type of osteogenesis imperfecta. All three displayed a severely disturbed ossification of the skull and multiple fractures with prenatal onset. The 7-year-old boy had short stature and craniofacial malformations including macrocephaly, midface hypoplasia, micrognathia, frontal bossing, and down-slanting palpebral fissures. Electron and immunofluorescence microscopy of skin fibroblasts of this individual revealed that ER export of procollagen was inefficient and that ER tubules were dilated, faithfully reproducing the cellular phenotype of individuals with cranio-lentico-sutural dysplasia (CLSD). CLSD is caused by SEC23A mutations and displays a largely overlapping craniofacial phenotype, but it is not characterized by generalized bone fragility and presented with cataracts in the original family described. The cellular and morphological phenotypes we report are in concordance with the phenotypes described for the Sec24d-deficient fish mutants vbi (medaka) and bulldog (zebrafish).
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43
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Structural analysis of the complex between penta-EF-hand ALG-2 protein and Sec31A peptide reveals a novel target recognition mechanism of ALG-2. Int J Mol Sci 2015; 16:3677-99. [PMID: 25667979 PMCID: PMC4346919 DOI: 10.3390/ijms16023677] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2015] [Accepted: 01/30/2015] [Indexed: 02/07/2023] Open
Abstract
ALG-2, a 22-kDa penta-EF-hand protein, is involved in cell death, signal transduction, membrane trafficking, etc., by interacting with various proteins in mammalian cells in a Ca2+-dependent manner. Most known ALG-2-interacting proteins contain proline-rich regions in which either PPYPXnYP (type 1 motif) or PXPGF (type 2 motif) is commonly found. Previous X-ray crystal structural analysis of the complex between ALG-2 and an ALIX peptide revealed that the peptide binds to the two hydrophobic pockets. In the present study, we resolved the crystal structure of the complex between ALG-2 and a peptide of Sec31A (outer shell component of coat complex II, COPII; containing the type 2 motif) and found that the peptide binds to the third hydrophobic pocket (Pocket 3). While amino acid substitution of Phe85, a Pocket 3 residue, with Ala abrogated the interaction with Sec31A, it did not affect the interaction with ALIX. On the other hand, amino acid substitution of Tyr180, a Pocket 1 residue, with Ala caused loss of binding to ALIX, but maintained binding to Sec31A. We conclude that ALG-2 recognizes two types of motifs at different hydrophobic surfaces. Furthermore, based on the results of serial mutational analysis of the ALG-2-binding sites in Sec31A, the type 2 motif was newly defined.
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44
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Johnson A, Bhattacharya N, Hanna M, Pennington JG, Schuh AL, Wang L, Otegui MS, Stagg SM, Audhya A. TFG clusters COPII-coated transport carriers and promotes early secretory pathway organization. EMBO J 2015; 34:811-27. [PMID: 25586378 DOI: 10.15252/embj.201489032] [Citation(s) in RCA: 78] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
In mammalian cells, cargo-laden secretory vesicles leave the endoplasmic reticulum (ER) en route to ER-Golgi intermediate compartments (ERGIC) in a manner dependent on the COPII coat complex. We report here that COPII-coated transport carriers traverse a submicron, TFG (Trk-fused gene)-enriched zone at the ER/ERGIC interface. The architecture of TFG complexes as determined by three-dimensional electron microscopy reveals the formation of flexible, octameric cup-like structures, which are able to self-associate to generate larger polymers in vitro. In cells, loss of TFG function dramatically slows protein export from the ER and results in the accumulation of COPII-coated carriers throughout the cytoplasm. Additionally, the tight association between ER and ERGIC membranes is lost in the absence of TFG. We propose that TFG functions at the ER/ERGIC interface to locally concentrate COPII-coated transport carriers and link exit sites on the ER to ERGIC membranes. Our findings provide a new mechanism by which COPII-coated carriers are retained near their site of formation to facilitate rapid fusion with neighboring ERGIC membranes upon uncoating, thereby promoting interorganellar cargo transport.
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Affiliation(s)
- Adam Johnson
- Department of Biomolecular Chemistry, University of Wisconsin-Madison School of Medicine and Public Health, Madison, WI, USA
| | | | - Michael Hanna
- Department of Biomolecular Chemistry, University of Wisconsin-Madison School of Medicine and Public Health, Madison, WI, USA
| | - Janice G Pennington
- Departments of Botany and Genetics, University of Wisconsin-Madison, Madison, WI, USA
| | - Amber L Schuh
- Department of Biomolecular Chemistry, University of Wisconsin-Madison School of Medicine and Public Health, Madison, WI, USA
| | - Lei Wang
- Department of Biomolecular Chemistry, University of Wisconsin-Madison School of Medicine and Public Health, Madison, WI, USA
| | - Marisa S Otegui
- Departments of Botany and Genetics, University of Wisconsin-Madison, Madison, WI, USA
| | - Scott M Stagg
- Institute of Molecular Biophysics, Florida State University, Tallahassee, FL, USA Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL, USA
| | - Anjon Audhya
- Department of Biomolecular Chemistry, University of Wisconsin-Madison School of Medicine and Public Health, Madison, WI, USA
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45
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The role of protein-protein interactions in the intracellular traffic of the potassium channels TASK-1 and TASK-3. Pflugers Arch 2015; 467:1105-20. [PMID: 25559843 DOI: 10.1007/s00424-014-1672-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2014] [Revised: 12/10/2014] [Accepted: 12/11/2014] [Indexed: 10/24/2022]
Abstract
The intracellular transport of membrane proteins is controlled by trafficking signals: Short peptide motifs that mediate the contact with COPI, COPII or various clathrin-associated coat proteins. In addition, many membrane proteins interact with accessory proteins that are involved in the sorting of these proteins to different intracellular compartments. In the K2P channels, TASK-1 and TASK-3, the influence of protein-protein interactions on sorting decisions has been studied in some detail. Both TASK paralogues interact with the adaptor protein 14-3-3; TASK-1 interacts, in addition, with the adaptor protein p11 (S100A10) and the endosomal SNARE protein syntaxin-8. The role of these interacting proteins in controlling the intracellular traffic of the channels and the underlying molecular mechanisms are summarised in this review. In the case of 14-3-3, the interacting protein masks a retention signal in the C-terminus of the channel; in the case of p11, the interacting protein carries a retention signal that localises the channel to the endoplasmic reticulum; and in the case of syntaxin-8, the interacting protein carries an endocytosis signal that complements an endocytosis signal of the channel. These examples illustrate some of the mechanisms by which interacting proteins may determine the itinerary of a membrane protein within a cell and suggest that the intracellular traffic of membrane proteins may be adapted to the specific functions of that protein by multiple protein-protein interactions.
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46
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Fox RM, Andrew DJ. Transcriptional regulation of secretory capacity by bZip transcription factors. ACTA ACUST UNITED AC 2014; 10:28-51. [PMID: 25821458 PMCID: PMC4374484 DOI: 10.1007/s11515-014-1338-7] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Cells of specialized secretory organs expand their secretory pathways to accommodate the increased protein load necessary for their function. The endoplasmic reticulum (ER), the Golgi apparatus and the secretory vesicles, expand not only the membrane components but also the protein machinery required for increased protein production and transport. Increased protein load causes an ER stress response akin to the Unfolded Protein Response (UPR). Recent work has implicated several bZip transcription factors in the regulation of protein components of the early secretory pathway necessary to alleviate this stress. Here, we highlight eight bZip transcription factors in regulating secretory pathway component genes. These include components of the three canonical branches of the UPR-ATF4, XBP1, and ATF6, as well as the five members of the Creb3 family of transcription factors.We review findings from both invertebrate and vertebrate model systems suggesting that all of these proteins increase secretory capacity in response to increased protein load. Finally, we propose that the Creb3 family of factors may have a dual role in secretory cell differentiation by also regulating the pathways necessary for cell cycle exit during terminal differentiation.
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Affiliation(s)
- Rebecca M Fox
- The Department of Cell Biology, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Deborah J Andrew
- The Department of Cell Biology, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
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47
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Parmar HB, Barry C, Duncan R. Polybasic trafficking signal mediates golgi export, ER retention or ER export and retrieval based on membrane-proximity. PLoS One 2014; 9:e94194. [PMID: 24714640 PMCID: PMC3979892 DOI: 10.1371/journal.pone.0094194] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2014] [Accepted: 03/11/2014] [Indexed: 12/25/2022] Open
Abstract
Trafficking of integral membrane proteins between the ER and Golgi complex, and protein sorting and trafficking between the TGN and endosomal/lysosomal compartments or plasma membranes, are dependent on cis-acting, linear amino acid sorting signals. Numerous sorting signals of this type have been identified in the cytoplasmic domains of membrane proteins, several of which rely on basic residues. A novel Golgi export signal that relies on a membrane-proximal polybasic motif (PBM) was recently identified in the reptilian reovirus p14 protein, a representative of an unusual group of bitopic fusion-associated small transmembrane (FAST) proteins encoded by fusogenic orthoreoviruses and responsible for cell-cell fusion and syncytium formation. Using immunofluorescence microscopy, cell surface immunofluorescence, and endoglycosidase H assays, we now show the p14 PBM can mediate several distinct trafficking functions depending on its proximity to the transmembrane domain (TMD). When present within 4-residues of the TMD it serves as a Golgi export signal, but when located at the C-terminus of the 68-residue p14 cytoplasmic endodomain it functions as an ER retention signal. The PBM has no effect on protein trafficking when located at an internal position in the cytoplasmic domain. When present in both membrane-proximal and -distal locations, the PBMs promote export to, and efficient retrieval from, the Golgi complex. Interestingly, the conflicting trafficking signals provided by two PBMs induces extensive ER tubulation and segregation of ER components. These studies highlight how a single trafficking signal in a simple transmembrane protein can have remarkably diverse, position-dependent effects on protein trafficking and ER morphogenesis.
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Affiliation(s)
- Hirendrasinh B. Parmar
- Department of Microbiology & Immunology, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Chris Barry
- Department of Microbiology & Immunology, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Roy Duncan
- Department of Microbiology & Immunology, Dalhousie University, Halifax, Nova Scotia, Canada
- Department of Biochemistry & Molecular Biology, Dalhousie University, Halifax, Nova Scotia, Canada
- Department of Pediatrics, Dalhousie University, Halifax, Nova Scotia, Canada
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