1
|
Hu M, Feng X, Liu Q, Liu S, Huang F, Xu H. The ion channels of endomembranes. Physiol Rev 2024; 104:1335-1385. [PMID: 38451235 DOI: 10.1152/physrev.00025.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Revised: 02/20/2024] [Accepted: 02/25/2024] [Indexed: 03/08/2024] Open
Abstract
The endomembrane system consists of organellar membranes in the biosynthetic pathway [endoplasmic reticulum (ER), Golgi apparatus, and secretory vesicles] as well as those in the degradative pathway (early endosomes, macropinosomes, phagosomes, autophagosomes, late endosomes, and lysosomes). These endomembrane organelles/vesicles work together to synthesize, modify, package, transport, and degrade proteins, carbohydrates, and lipids, regulating the balance between cellular anabolism and catabolism. Large ion concentration gradients exist across endomembranes: Ca2+ gradients for most endomembrane organelles and H+ gradients for the acidic compartments. Ion (Na+, K+, H+, Ca2+, and Cl-) channels on the organellar membranes control ion flux in response to cellular cues, allowing rapid informational exchange between the cytosol and organelle lumen. Recent advances in organelle proteomics, organellar electrophysiology, and luminal and juxtaorganellar ion imaging have led to molecular identification and functional characterization of about two dozen endomembrane ion channels. For example, whereas IP3R1-3 channels mediate Ca2+ release from the ER in response to neurotransmitter and hormone stimulation, TRPML1-3 and TMEM175 channels mediate lysosomal Ca2+ and H+ release, respectively, in response to nutritional and trafficking cues. This review aims to summarize the current understanding of these endomembrane channels, with a focus on their subcellular localizations, ion permeation properties, gating mechanisms, cell biological functions, and disease relevance.
Collapse
Affiliation(s)
- Meiqin Hu
- Department of Neurology and Department of Cardiology, The Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, People's Republic of China
- New Cornerstone Science Laboratory, Liangzhu Laboratory and School of Basic Medical Sciences, Zhejiang University, Hangzhou, People's Republic of China
| | - Xinghua Feng
- Department of Neurology and Department of Cardiology, The Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, People's Republic of China
- New Cornerstone Science Laboratory, Liangzhu Laboratory and School of Basic Medical Sciences, Zhejiang University, Hangzhou, People's Republic of China
| | - Qiang Liu
- New Cornerstone Science Laboratory, Liangzhu Laboratory and School of Basic Medical Sciences, Zhejiang University, Hangzhou, People's Republic of China
| | - Siyu Liu
- New Cornerstone Science Laboratory, Liangzhu Laboratory and School of Basic Medical Sciences, Zhejiang University, Hangzhou, People's Republic of China
| | - Fangqian Huang
- New Cornerstone Science Laboratory, Liangzhu Laboratory and School of Basic Medical Sciences, Zhejiang University, Hangzhou, People's Republic of China
| | - Haoxing Xu
- Department of Neurology and Department of Cardiology, The Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, People's Republic of China
- New Cornerstone Science Laboratory, Liangzhu Laboratory and School of Basic Medical Sciences, Zhejiang University, Hangzhou, People's Republic of China
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan, United States
| |
Collapse
|
2
|
Held A, Lapka J, Sargeant J, Hojanazarova J, Shaheen A, Galindo S, Madreiter-Sokolowski C, Malli R, Graier WF, Hay JC. Steady-state regulation of COPII-dependent secretory cargo sorting by inositol trisphosphate receptors, calcium, and penta EF hand proteins. J Biol Chem 2023; 299:105471. [PMID: 37979918 PMCID: PMC10750190 DOI: 10.1016/j.jbc.2023.105471] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2023] [Revised: 10/30/2023] [Accepted: 11/02/2023] [Indexed: 11/20/2023] Open
Abstract
Recently, we demonstrated that agonist-stimulated Ca2+ signaling involving IP3 receptors modulates ER export rates through activation of the penta-EF Hand proteins apoptosis-linked gene-2 (ALG-2) and peflin. It is unknown, however, whether IP3Rs and penta-EF proteins regulate ER export rates at steady state. Here we tested this idea in normal rat kidney epithelial cells by manipulation of IP3R isoform expression. Under standard growth conditions, spontaneous cytosolic Ca2+ oscillations occurred simultaneously in successive groups of contiguous cells, generating intercellular Ca2+ waves that moved across the monolayer periodically. Depletion of IP3R-3, typically the least promiscuous IP3R isoform, caused increased cell participation in intercellular Ca2+ waves in unstimulated cells. The increased spontaneous signaling was sufficient to cause increased ALG-2 and COPII coat subunit Sec31A and decreased peflin localization at ER exit sites, resulting in increased ER-to-Golgi transport of the COPII client cargo VSV-G. The elevated ER-to-Golgi transport caused greater concentration of VSV-G at ER exit sites and had reciprocal effects on transport of VSV-G and a bulk-flow cargo, though both cargos equally required Sec31A. Inactivation of client cargo sorting using 4-phenylbutyrate had opposing reciprocal effects on client and bulk-flow cargo and neutralized any effect of ALG-2 activation on transport. This work extends our knowledge of ALG-2 mechanisms and indicates that in normal rat kidney cells, IP3R isoforms regulate homeostatic Ca2+ signaling that helps determine the basal secretion rate and stringency of COPII-dependent cargo sorting.
Collapse
Affiliation(s)
- Aaron Held
- Division of Biological Sciences, Center for Structural & Functional Neuroscience, University of Montana, Missoula, Montana, USA
| | - Jacob Lapka
- Division of Biological Sciences, Center for Structural & Functional Neuroscience, University of Montana, Missoula, Montana, USA
| | - John Sargeant
- Division of Biological Sciences, Center for Structural & Functional Neuroscience, University of Montana, Missoula, Montana, USA
| | - Jennet Hojanazarova
- Division of Biological Sciences, Center for Structural & Functional Neuroscience, University of Montana, Missoula, Montana, USA
| | - Alaa Shaheen
- Division of Biological Sciences, Center for Structural & Functional Neuroscience, University of Montana, Missoula, Montana, USA
| | - Samuel Galindo
- Division of Biological Sciences, Center for Structural & Functional Neuroscience, University of Montana, Missoula, Montana, USA
| | - Corina Madreiter-Sokolowski
- Molecular Biology and Biochemistry, Gottfried Schatz Research Center, Medical University of Graz, Graz, Austria
| | - Roland Malli
- Molecular Biology and Biochemistry, Gottfried Schatz Research Center, Medical University of Graz, Graz, Austria
| | - Wolfgang F Graier
- Molecular Biology and Biochemistry, Gottfried Schatz Research Center, Medical University of Graz, Graz, Austria
| | - Jesse C Hay
- Division of Biological Sciences, Center for Structural & Functional Neuroscience, University of Montana, Missoula, Montana, USA.
| |
Collapse
|
3
|
Han S, Wang Q, Song Y, Pang M, Ren C, Wang J, Guan D, Xu W, Li F, Wang F, Zhou X, Fernández-Hernando C, Zhang H, Wu D, Ye Z. Lithium ameliorates Niemann-Pick C1 disease phenotypes by impeding STING/SREBP2 activation. iScience 2023; 26:106613. [PMID: 37128603 PMCID: PMC10148154 DOI: 10.1016/j.isci.2023.106613] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Revised: 11/18/2022] [Accepted: 03/31/2023] [Indexed: 05/03/2023] Open
Abstract
Niemann-Pick disease type C (NP-C) is a genetic lysosomal disorder associated with progressive neurodegenerative phenotypes. Its therapeutic options are very limited. Here, we show that lithium treatment improves ataxia and feeding phenotypes, attenuates cerebellar inflammation and degeneration, and extends survival in Npc1 mouse models. In addition, lithium suppresses STING activation, SREBP2 processing to its mature form and the expression of the target genes in the Npc1 mice and in Npc1-deficient fibroblasts. Lithium impedes STING/SREBP2 transport from the ER to the Golgi, a step required for STING activation and SREBP2 processing, probably by lowering cytosolic calcium concentrations. This effect of lithium on STING/SREBP2 transport provides a mechanistic explanation for lithium's effects on Npc1 mice. Thus, this study reveals a potential therapeutic option for NP-C patients as well as a strategy to reduce active STING/SREBP2 pathway.
Collapse
Affiliation(s)
- Shiqian Han
- Department of Tropical Medicine, Third Military Medical University (Army Medical University), Chongqing 400038, China
| | - Qijun Wang
- Vascular Biology and Therapeutics Program, Yale University School of Medicine, New Haven, CT06520, USA
- Departments of Pharmacology, Yale University School of Medicine, New Haven, CT06520, USA
- Shanghai Institute of Immunology, Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200092, China
| | - Yongfeng Song
- Vascular Biology and Therapeutics Program, Yale University School of Medicine, New Haven, CT06520, USA
- Departments of Pharmacology, Yale University School of Medicine, New Haven, CT06520, USA
| | - Mao Pang
- Laboratory Animal Research Center, Chongqing University School of Medicine, Chongqing 400044, China
| | - Chunguang Ren
- Vascular Biology and Therapeutics Program, Yale University School of Medicine, New Haven, CT06520, USA
- Departments of Pharmacology, Yale University School of Medicine, New Haven, CT06520, USA
| | - Jing Wang
- Department of Tropical Medicine, Third Military Medical University (Army Medical University), Chongqing 400038, China
| | - Dongwei Guan
- Laboratory Animal Research Center, Chongqing University School of Medicine, Chongqing 400044, China
| | - Wei Xu
- Biostatistics, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Fangyong Li
- Biostatistics, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Fengchao Wang
- Institute of Combined Injury, Third Military Medical University (Army Medical University), Chongqing 400038, China
| | - Xinyuan Zhou
- Department of Immunology, Third Military Medical University (Army Medical University), Chongqing 400038, China
| | - Carlos Fernández-Hernando
- Vascular Biology and Therapeutics Program, Yale University School of Medicine, New Haven, CT06520, USA
- Comparative Medicine and Pathology, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Huiwen Zhang
- Department of Pediatric Endocrinology and Genetics, Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200092, China
| | - Dianqing Wu
- Vascular Biology and Therapeutics Program, Yale University School of Medicine, New Haven, CT06520, USA
- Departments of Pharmacology, Yale University School of Medicine, New Haven, CT06520, USA
| | - Zhijia Ye
- Laboratory Animal Research Center, Chongqing University School of Medicine, Chongqing 400044, China
| |
Collapse
|
4
|
The role of CaMKK2 in Golgi-associated vesicle trafficking. Biochem Soc Trans 2023; 51:331-342. [PMID: 36815702 PMCID: PMC9987998 DOI: 10.1042/bst20220833] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2022] [Revised: 02/03/2023] [Accepted: 02/07/2023] [Indexed: 02/24/2023]
Abstract
Calcium/calmodulin-dependent protein kinase kinase 2 (CaMKK2) is a serine/threonine-protein kinase, that is involved in maintaining various physiological and cellular processes within the cell that regulate energy homeostasis and cell growth. CaMKK2 regulates glucose metabolism by the activation of downstream kinases, AMP-activated protein kinase (AMPK) and other calcium/calmodulin-dependent protein kinases. Consequently, its deregulation has a role in multiple human metabolic diseases including obesity and cancer. Despite the importance of CaMKK2, its signalling pathways and pathological mechanisms are not completely understood. Recent work has been aimed at broadening our understanding of the biological functions of CaMKK2. These studies have uncovered new interaction partners that have led to the description of new functions that include lipogenesis and Golgi vesicle trafficking. Here, we review recent insights into the role of CaMKK2 in membrane trafficking mechanisms and discuss the functional implications in a cellular context and for disease.
Collapse
|
5
|
Identification of a dihydropyridine scaffold that blocks ryanodine receptors. iScience 2022; 25:103706. [PMID: 35059610 PMCID: PMC8760560 DOI: 10.1016/j.isci.2021.103706] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2021] [Revised: 11/16/2021] [Accepted: 12/23/2021] [Indexed: 12/24/2022] Open
Abstract
Ryanodine receptors (RyRs) are large, intracellular ion channels that control Ca2+ release from the sarco/endoplasmic reticulum. Dysregulation of RyRs in skeletal muscle, heart, and brain has been implicated in various muscle pathologies, arrhythmia, heart failure, and Alzheimer's disease. Therefore, there is considerable interest in therapeutically targeting RyRs to normalize Ca2+ homeostasis in scenarios involving RyR dysfunction. Here, a simple invertebrate screening platform was used to discover new chemotypes targeting RyRs. The approach measured Ca2+ signals evoked by cyclic adenosine 5′-diphosphate ribose, a second messenger that sensitizes RyRs. From a 1,534-compound screen, FLI-06 (currently described as a Notch “inhibitor”) was identified as a potent blocker of RyR activity. Two closely related tyrosine kinase inhibitors that stimulate and inhibit Ca2+ release through RyRs were also resolved. Therefore, this simple screen yielded RyR scaffolds tractable for development and revealed an unexpected linkage between RyRs and trafficking events in the early secretory pathway. FLI-06 inhibits transport in the secretory pathway via an unknown mechanism An invertebrate screening platform revealed FLI-06 blocks intracellular Ca2+ release FLI-06 acts as a potent, cell-permeable ryanodine receptor (RyR) blocker The para-substituted dihydropyridine chemotype is a new scaffold for RyR modulation
Collapse
|
6
|
Sargeant J, Seiler DK, Costain T, Madreiter-Sokolowski CT, Gordon DE, Peden AA, Malli R, Graier WF, Hay JC. ALG-2 and peflin regulate COPII targeting and secretion in response to calcium signaling. J Biol Chem 2021; 297:101393. [PMID: 34762908 PMCID: PMC8671942 DOI: 10.1016/j.jbc.2021.101393] [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: 06/10/2021] [Revised: 11/01/2021] [Accepted: 11/05/2021] [Indexed: 02/05/2023] Open
Abstract
ER-to-Golgi transport is the first step in the constitutive secretory pathway, which, unlike regulated secretion, is believed to proceed nonstop independent of Ca2+ flux. However, here we demonstrate that penta-EF hand (PEF) proteins ALG-2 and peflin constitute a hetero-bifunctional COPII regulator that responds to Ca2+ signaling by adopting one of several distinct activity states. Functionally, these states can adjust the rate of ER export of COPII-sorted cargos up or down by ∼50%. We found that at steady-state Ca2+, ALG-2/peflin hetero-complexes bind to ER exit sites (ERES) through the ALG-2 subunit to confer a low, buffered secretion rate, while peflin-lacking ALG-2 complexes markedly stimulate secretion. Upon Ca2+ signaling, ALG-2 complexes lacking peflin can either increase or decrease the secretion rate depending on signaling intensity and duration-phenomena that could contribute to cellular growth and intercellular communication following secretory increases or protection from excitotoxicity and infection following decreases. In epithelial normal rat kidney (NRK) cells, the Ca2+-mobilizing agonist ATP causes ALG-2 to depress ER export, while in neuroendocrine PC12 cells, Ca2+ mobilization by ATP results in ALG-2-dependent enhancement of secretion. Furthermore, distinct Ca2+ signaling patterns in NRK cells produce opposing ALG-2-dependent effects on secretion. Mechanistically, ALG-2-dependent depression of secretion involves decreased levels of the COPII outer shell and increased peflin targeting to ERES, while ALG-2-dependent enhancement of secretion involves increased COPII outer shell and decreased peflin at ERES. These data provide insights into how PEF protein dynamics affect secretion of important physiological cargoes such as collagen I and significantly impact ER stress.
Collapse
Affiliation(s)
- John Sargeant
- Division of Biological Sciences, Center for Structural and Functional Neuroscience, University of Montana, Missoula, Montana, USA
| | - Danette Kowal Seiler
- Division of Biological Sciences, Center for Structural and Functional Neuroscience, University of Montana, Missoula, Montana, USA
| | - Tucker Costain
- Division of Biological Sciences, Center for Structural and Functional Neuroscience, University of Montana, Missoula, Montana, USA
| | | | - David E Gordon
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, California, USA
| | - Andrew A Peden
- Department of Biomedical Science and Centre for Membrane Interactions and Dynamics, The University of Sheffield, Sheffield, United Kingdom
| | - Roland Malli
- Molecular Biology and Biochemistry, Gottfried Schatz Research Center, Medical University of Graz, Graz, Austria
| | - Wolfgang F Graier
- Molecular Biology and Biochemistry, Gottfried Schatz Research Center, Medical University of Graz, Graz, Austria
| | - Jesse C Hay
- Division of Biological Sciences, Center for Structural and Functional Neuroscience, University of Montana, Missoula, Montana, USA.
| |
Collapse
|
7
|
Rauter T, Burgstaller S, Gottschalk B, Ramadani-Muja J, Bischof H, Hay JC, Graier WF, Malli R. ER-to-Golgi Transport in HeLa Cells Displays High Resilience to Ca 2+ and Energy Stresses. Cells 2020; 9:E2311. [PMID: 33080790 PMCID: PMC7603030 DOI: 10.3390/cells9102311] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Revised: 10/09/2020] [Accepted: 10/16/2020] [Indexed: 02/07/2023] Open
Abstract
One third of all human proteins are either transmembrane or soluble secretory proteins that first target the endoplasmic reticulum (ER). These proteins subsequently leave the ER and enter the Golgi apparatus via ER-Golgi intermediate vesicular structures. Live-cell imaging of cargos fused to fluorescent proteins (FPs) enables the high-resolution visualization and characterization of secretory transport processes. Here, we performed fluorescence time-lapse imaging to assess the Ca2+ and energy dependency of ER-to-Golgi transport in living HeLa cells, a cancer cell model which has been well investigated. Our data revealed that ER-to-Golgi transport remained highly efficient in the absence of ATP-generating substrates, despite clear reductions in cytosolic and mitochondrial ATP levels under these energy stress conditions. However, cell treatment with 2-deoxy-D-glucose (2-DG), which severely diminished subcellular ATP levels, abolished ER-to-Golgi transport. Interestingly, while 2-DG elevated cytosolic Ca2+ levels and reduced long-distance movements of glycosylphosphatidylinositol (GPI)-positive vesicles, robust short-term ER Ca2+ mobilizations, which strongly affected the motility of these vesicles, did not considerably impair ER-to-Golgi transport. In summary, we highlight that ER-to-Golgi transport in HeLa cells remains functional despite high energy and Ca2+ stress levels.
Collapse
Affiliation(s)
- Thomas Rauter
- Molecular Biology and Biochemistry, Gottfried Schatz Research Center, Medical University of Graz, Neue Stiftingtalstraße 6/6, 8010 Graz, Austria; (T.R.); (S.B.); (B.G.); (J.R.-M.); (H.B.); (W.F.G.)
| | - Sandra Burgstaller
- Molecular Biology and Biochemistry, Gottfried Schatz Research Center, Medical University of Graz, Neue Stiftingtalstraße 6/6, 8010 Graz, Austria; (T.R.); (S.B.); (B.G.); (J.R.-M.); (H.B.); (W.F.G.)
- Interfaculty Institute of Cell Biology, University of Tuebingen, Auf der Morgenstelle 15, 72076 Tuebingen, Germany
| | - Benjamin Gottschalk
- Molecular Biology and Biochemistry, Gottfried Schatz Research Center, Medical University of Graz, Neue Stiftingtalstraße 6/6, 8010 Graz, Austria; (T.R.); (S.B.); (B.G.); (J.R.-M.); (H.B.); (W.F.G.)
| | - Jeta Ramadani-Muja
- Molecular Biology and Biochemistry, Gottfried Schatz Research Center, Medical University of Graz, Neue Stiftingtalstraße 6/6, 8010 Graz, Austria; (T.R.); (S.B.); (B.G.); (J.R.-M.); (H.B.); (W.F.G.)
| | - Helmut Bischof
- Molecular Biology and Biochemistry, Gottfried Schatz Research Center, Medical University of Graz, Neue Stiftingtalstraße 6/6, 8010 Graz, Austria; (T.R.); (S.B.); (B.G.); (J.R.-M.); (H.B.); (W.F.G.)
- Department of Pharmacology, Toxicology and Clinical Pharmacy, Institute of Pharmacy, University of Tuebingen, Auf der Morgenstelle 8, 72076 Tuebingen, Germany
| | - Jesse C. Hay
- Division of Biological Sciences and Center for Structural and Functional Neuroscience, The University of Montana, 32 Campus Drive, HS 302A, Missoula, MT 59812-4824, USA;
| | - Wolfgang F. Graier
- Molecular Biology and Biochemistry, Gottfried Schatz Research Center, Medical University of Graz, Neue Stiftingtalstraße 6/6, 8010 Graz, Austria; (T.R.); (S.B.); (B.G.); (J.R.-M.); (H.B.); (W.F.G.)
- BioTechMed Graz, Mozartgasse 12/II, 8010 Graz, Austria
| | - Roland Malli
- Molecular Biology and Biochemistry, Gottfried Schatz Research Center, Medical University of Graz, Neue Stiftingtalstraße 6/6, 8010 Graz, Austria; (T.R.); (S.B.); (B.G.); (J.R.-M.); (H.B.); (W.F.G.)
- BioTechMed Graz, Mozartgasse 12/II, 8010 Graz, Austria
| |
Collapse
|
8
|
Takahara T, Inoue K, Arai Y, Kuwata K, Shibata H, Maki M. The calcium-binding protein ALG-2 regulates protein secretion and trafficking via interactions with MISSL and MAP1B proteins. J Biol Chem 2017; 292:17057-17072. [PMID: 28864773 DOI: 10.1074/jbc.m117.800201] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2017] [Revised: 08/31/2017] [Indexed: 01/12/2023] Open
Abstract
Mobilization of intracellular calcium is essential for a wide range of cellular processes, including signal transduction, apoptosis, and vesicular trafficking. Several lines of evidence have suggested that apoptosis-linked gene 2 (ALG-2, also known as PDCD6), a calcium-binding protein, acts as a calcium sensor linking calcium levels with efficient vesicular trafficking, especially at the endoplasmic reticulum (ER)-to-Golgi transport step. However, how ALG-2 regulates these processes remains largely unclear. Here, we report that MAPK1-interacting and spindle-stabilizing (MISS)-like (MISSL), a previously uncharacterized protein, interacts with ALG-2 in a calcium-dependent manner. Live-cell imaging revealed that upon a rise in intracellular calcium levels, GFP-tagged MISSL (GFP-MISSL) dynamically relocalizes in a punctate pattern and colocalizes with ALG-2. MISSL knockdown caused disorganization of the components of the ER exit site, the ER-Golgi intermediate compartment, and Golgi. Importantly, knockdown of either MISSL or ALG-2 attenuated the secretion of secreted alkaline phosphatase (SEAP), a model secreted cargo protein, with similar reductions in secretion by single- and double-protein knockdowns, suggesting that MISSL and ALG-2 act in the same pathway to regulate the secretion process. Furthermore, ALG-2 or MISSL knockdown delayed ER-to-Golgi transport of procollagen type I. We also found that ALG-2 and MISSL interact with microtubule-associated protein 1B (MAP1B) and that MAP1B knockdown reverts the reduced secretion of SEAP caused by MISSL or ALG-2 depletion. These results suggest that a change in the intracellular calcium level plays a role in regulation of the secretory pathway via interaction of ALG-2 with MISSL and MAP1B.
Collapse
Affiliation(s)
- Terunao Takahara
- From the Department of Applied Molecular Biosciences, Graduate School of Bioagricultural Sciences, and
| | - Kuniko Inoue
- From the Department of Applied Molecular Biosciences, Graduate School of Bioagricultural Sciences, and
| | - Yumika Arai
- From the Department of Applied Molecular Biosciences, Graduate School of Bioagricultural Sciences, and
| | - Keiko Kuwata
- the Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8601, Japan
| | - Hideki Shibata
- From the Department of Applied Molecular Biosciences, Graduate School of Bioagricultural Sciences, and
| | - Masatoshi Maki
- From the Department of Applied Molecular Biosciences, Graduate School of Bioagricultural Sciences, and
| |
Collapse
|
9
|
Konopka-Postupolska D, Clark G. Annexins as Overlooked Regulators of Membrane Trafficking in Plant Cells. Int J Mol Sci 2017; 18:E863. [PMID: 28422051 PMCID: PMC5412444 DOI: 10.3390/ijms18040863] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2016] [Revised: 04/03/2017] [Accepted: 04/06/2017] [Indexed: 12/11/2022] Open
Abstract
Annexins are an evolutionary conserved superfamily of proteins able to bind membrane phospholipids in a calcium-dependent manner. Their physiological roles are still being intensively examined and it seems that, despite their general structural similarity, individual proteins are specialized toward specific functions. However, due to their general ability to coordinate membranes in a calcium-sensitive fashion they are thought to participate in membrane flow. In this review, we present a summary of the current understanding of cellular transport in plant cells and consider the possible roles of annexins in different stages of vesicular transport.
Collapse
Affiliation(s)
- Dorota Konopka-Postupolska
- Plant Biochemistry Department, Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw 02-106, Poland.
| | - Greg Clark
- Molecular, Cell, and Developmental Biology, University of Texas, Austin, TX 78712, USA.
| |
Collapse
|
10
|
Eroglu E, Rost R, Bischof H, Blass S, Schreilechner A, Gottschalk B, Depaoli MR, Klec C, Charoensin S, Madreiter-Sokolowski CT, Ramadani J, Waldeck-Weiermair M, Graier WF, Malli R. Application of Genetically Encoded Fluorescent Nitric Oxide (NO•) Probes, the geNOps, for Real-time Imaging of NO• Signals in Single Cells. J Vis Exp 2017:55486. [PMID: 28362417 PMCID: PMC5408997 DOI: 10.3791/55486] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Nitric Oxide (NO•) is a small radical, which mediates multiple important cellular functions in mammals, bacteria and plants. Despite the existence of a large number of methods for detecting NO• in vivo and in vitro, the real-time monitoring of NO• at the single-cell level is very challenging. The physiological or pathological effects of NO• are determined by the actual concentration and dwell time of this radical. Accordingly, methods that allow the single-cell detection of NO• are highly desirable. Recently, we expanded the pallet of NO• indicators by introducing single fluorescent protein-based genetically encoded nitric oxide (NO•) probes (geNOps) that directly respond to cellular NO• fluctuations and, hence, addresses this need. Here we demonstrate the usage of geNOps to assess intracellular NO• signals in response to two different chemical NO•-liberating molecules. Our results also confirm that freshly prepared 3-(2-hydroxy-1-methyl-2-nitrosohydrazino)-N-methyl-1-propanamine (NOC-7) has a much higher potential to evoke change in intracellular NO• levels as compared with the inorganic NO• donor sodium nitroprusside (SNP). Furthermore, dual-color live-cell imaging using the green geNOps (G-geNOp) and the chemical Ca2+ indicator fura-2 was performed to visualize the tight regulation of Ca2+-dependent NO• formation in single endothelial cells. These representative experiments demonstrate that geNOps are suitable tools to investigate the real-time generation and degradation of single-cell NO• signals in diverse experimental setups.
Collapse
Affiliation(s)
- Emrah Eroglu
- Institute of Molecular Biology and Biochemistry, Medical University of Graz
| | - Rene Rost
- Institute of Molecular Biology and Biochemistry, Medical University of Graz
| | - Helmut Bischof
- Institute of Molecular Biology and Biochemistry, Medical University of Graz
| | - Sandra Blass
- Institute of Molecular Biology and Biochemistry, Medical University of Graz
| | - Anna Schreilechner
- Institute of Molecular Biology and Biochemistry, Medical University of Graz
| | | | - Maria R Depaoli
- Institute of Molecular Biology and Biochemistry, Medical University of Graz
| | - Christiane Klec
- Institute of Molecular Biology and Biochemistry, Medical University of Graz
| | | | | | - Jeta Ramadani
- Institute of Molecular Biology and Biochemistry, Medical University of Graz
| | | | - Wolfgang F Graier
- Institute of Molecular Biology and Biochemistry, Medical University of Graz
| | - Roland Malli
- Institute of Molecular Biology and Biochemistry, Medical University of Graz;
| |
Collapse
|
11
|
Enrich C, Rentero C, Meneses-Salas E, Tebar F, Grewal T. Annexins: Ca 2+ Effectors Determining Membrane Trafficking in the Late Endocytic Compartment. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 981:351-385. [PMID: 29594868 DOI: 10.1007/978-3-319-55858-5_14] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Despite the discovery of annexins 40 years ago, we are just beginning to understand some of the functions of these still enigmatic proteins. Defined and characterized by their ability to bind anionic membrane lipids in a Ca2+-dependent manner, each annexin has to be considered a multifunctional protein, with a multitude of cellular locations and diverse activities. Underlying causes for this considerable functional diversity include their capability to associate with multiple cytosolic and membrane proteins. In recent years, the increasingly recognized establishment of membrane contact sites between subcellular compartments opens a new scenario for annexins as instrumental players to link Ca2+ signalling with the integration of membrane trafficking in many facets of cell physiology. In this chapter, we review and discuss current knowledge on the contribution of annexins in the biogenesis and functioning of the late endocytic compartment, affecting endo- and exocytic pathways in a variety of physiological consequences ranging from membrane repair, lysosomal exocytosis, to cell migration.
Collapse
Affiliation(s)
- Carlos Enrich
- Departament de Biomedicina, Unitat de Biologia Cel·lular, Centre de Recerca Biomèdica (CELLEX), Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain. .,Facultat de Medicina i Ciències de la Salut, Universitat de Barcelona, Barcelona, Spain.
| | - Carles Rentero
- Departament de Biomedicina, Unitat de Biologia Cel·lular, Centre de Recerca Biomèdica (CELLEX), Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain.,Facultat de Medicina i Ciències de la Salut, Universitat de Barcelona, Barcelona, Spain
| | - Elsa Meneses-Salas
- Departament de Biomedicina, Unitat de Biologia Cel·lular, Centre de Recerca Biomèdica (CELLEX), Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain.,Facultat de Medicina i Ciències de la Salut, Universitat de Barcelona, Barcelona, Spain
| | - Francesc Tebar
- Departament de Biomedicina, Unitat de Biologia Cel·lular, Centre de Recerca Biomèdica (CELLEX), Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain.,Facultat de Medicina i Ciències de la Salut, Universitat de Barcelona, Barcelona, Spain
| | - Thomas Grewal
- Faculty of Pharmacy, University of Sydney, Sydney, Australia
| |
Collapse
|
12
|
Kanadome T, Shibata H, Kuwata K, Takahara T, Maki M. The calcium-binding protein ALG-2 promotes endoplasmic reticulum exit site localization and polymerization of Trk-fused gene (TFG) protein. FEBS J 2017; 284:56-76. [PMID: 27813252 DOI: 10.1111/febs.13949] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2016] [Revised: 09/28/2016] [Accepted: 11/01/2016] [Indexed: 12/27/2022]
Abstract
Apoptosis-linked gene 2 (ALG-2), which is a gene product of PDCD6, is a 22-kDa Ca2+ -binding protein. Accumulating evidence points to a role for ALG-2 as a Ca2+ -responsive adaptor protein. On binding to Ca2+ , ALG-2 undergoes a conformational change that facilitates its interaction with various proteins. It also forms a homodimer and heterodimer with peflin, a paralog of ALG-2. However, the differences in cellular roles for the ALG-2 homodimer and ALG-2/peflin heterodimer are unclear. In the present study, we found that Trk-fused gene (TFG) protein interacted with the ALG-2 homodimer. Immunostaining analysis revealed that TFG and ALG-2 partially overlapped at endoplasmic reticulum exit sites (ERES), a platform for COPII-mediated protein transport from the endoplasmic reticulum. Time-lapse live-cell imaging demonstrated that both green fluorescent protein-fused TFG and mCherry-fused ALG-2 are recruited to ERES after thapsigargin treatment, which raises intracellular Ca2+ levels. Furthermore, overexpression of ALG-2 induced the accumulation of TFG at ERES. TFG has an ALG-2-binding motif and deletion of the motif decreased TFG binding to ALG-2 and shortened its half-life at ERES, suggesting a critical role for ALG-2 in retaining TFG at ERES. We also demonstrated, by in vitro cross-linking assays, that ALG-2 promoted the polymerization of TFG in a Ca2+ -dependent manner. Collectively, the results suggest that ALG-2 acts as a Ca2+ -sensitive adaptor to concentrate and polymerize TFG at ERES, supporting a potential role for ALG-2 in COPII-dependent trafficking from the endoplasmic reticulum.
Collapse
Affiliation(s)
- Takashi Kanadome
- Department of Applied Molecular Biosciences, Graduate School of Bioagricultural Sciences, Nagoya University, Japan
| | - Hideki Shibata
- Department of Applied Molecular Biosciences, Graduate School of Bioagricultural Sciences, Nagoya University, Japan
| | - Keiko Kuwata
- Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University, Japan
| | - Terunao Takahara
- Department of Applied Molecular Biosciences, Graduate School of Bioagricultural Sciences, Nagoya University, Japan
| | - Masatoshi Maki
- Department of Applied Molecular Biosciences, Graduate School of Bioagricultural Sciences, Nagoya University, Japan
| |
Collapse
|
13
|
Ma J, Zhang X, Feng Y, Zhang H, Wang X, Zheng Y, Qiao W, Liu X. Structural and Functional Study of Apoptosis-linked Gene-2·Heme-binding Protein 2 Interactions in HIV-1 Production. J Biol Chem 2016; 291:26670-26685. [PMID: 27784779 DOI: 10.1074/jbc.m116.752444] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2016] [Revised: 10/01/2016] [Indexed: 01/10/2023] Open
Abstract
In the HIV-1 replication cycle, the endosomal sorting complex required for transport (ESCRT) machinery promotes viral budding and release in the late stages. In this process, the ESCRT proteins, ALIX and TSG101, are recruited through interactions with HIV-1 Gag p6. ALG-2, also known as PDCD6, interacts with both ALIX and TSG101 and bridges ESCRT-III and ESCRT-I. In this study, we show that ALG-2 affects HIV-1 production negatively at both the exogenous and endogenous levels. Through a yeast two-hybrid screen, we identified HEBP2 as the binding partner of ALG-2, and we solved the crystal structure of the ALG-2·HEBP2 complex. The function of ALG-2·HEBP2 complex in HIV-1 replication was further explored. ALG-2 inhibits HIV-1 production by affecting Gag expression and distribution, and HEBP2 might aid this process by tethering ALG-2 in the cytoplasm.
Collapse
Affiliation(s)
- Jing Ma
- From the State Key Laboratory of Medicinal Chemical Biology, College of Life Sciences, Nankai University, Tianjin 300071.,the Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, College of Life Sciences, Nankai University, Tianjin 300071, China
| | - Xianfeng Zhang
- the CAAS-Michigan State University Joint Laboratory of Innate Immunity, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150069, and
| | - Yanbin Feng
- From the State Key Laboratory of Medicinal Chemical Biology, College of Life Sciences, Nankai University, Tianjin 300071
| | - Hui Zhang
- From the State Key Laboratory of Medicinal Chemical Biology, College of Life Sciences, Nankai University, Tianjin 300071
| | - Xiaojun Wang
- the CAAS-Michigan State University Joint Laboratory of Innate Immunity, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150069, and
| | - Yonghui Zheng
- the CAAS-Michigan State University Joint Laboratory of Innate Immunity, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150069, and
| | - Wentao Qiao
- From the State Key Laboratory of Medicinal Chemical Biology, College of Life Sciences, Nankai University, Tianjin 300071, .,the Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, College of Life Sciences, Nankai University, Tianjin 300071, China
| | - Xinqi Liu
- From the State Key Laboratory of Medicinal Chemical Biology, College of Life Sciences, Nankai University, Tianjin 300071,
| |
Collapse
|
14
|
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.
Collapse
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.
| |
Collapse
|
15
|
Rayl M, Truitt M, Held A, Sargeant J, Thorsen K, Hay JC. Penta-EF-Hand Protein Peflin Is a Negative Regulator of ER-To-Golgi Transport. PLoS One 2016; 11:e0157227. [PMID: 27276012 PMCID: PMC4898701 DOI: 10.1371/journal.pone.0157227] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2016] [Accepted: 05/26/2016] [Indexed: 11/18/2022] Open
Abstract
Luminal calcium regulates vesicle transport early in the secretory pathway. In ER-to-Golgi transport, depletion of luminal calcium leads to significantly reduced transport and a buildup of budding and newly budded COPII vesicles and vesicle proteins. Effects of luminal calcium on transport may be mediated by cytoplasmic calcium sensors near ER exits sites (ERES). The penta-EF-hand (PEF) protein apoptosis-linked gene 2 (ALG-2) stabilizes sec31A at ER exit sites (ERES) and promotes the assembly of inner and outer shell COPII components. However, in vitro and intact cell approaches have not determined whether ALG-2 is a negative or positive regulator, or a regulator at all, under basal physiological conditions. ALG-2 interacts with another PEF protein, peflin, to form cytosolic heterodimers that dissociate in response to calcium. However, a biological function for peflin has not been demonstrated and whether peflin and the ALG-2/peflin interaction modulates transport has not been investigated. Using an intact, single cell, morphological assay for ER-to-Golgi transport in normal rat kidney (NRK) cells, we found that depletion of peflin using siRNA resulted in significantly faster transport of the membrane cargo VSV-G. Double depletion of peflin and ALG-2 blocked the increased transport resulting from peflin depletion, demonstrating a role for ALG-2 in the increased transport. Furthermore, peflin depletion caused increased targeting of ALG-2 to ERES and increased ALG-2/sec31A interactions, suggesting that peflin may normally inhibit transport by preventing ALG-2/sec31A interactions. This work identifies for the first time a clear steady state role for a PEF protein in ER-to-Golgi transport—peflin is a negative regulator of transport.
Collapse
Affiliation(s)
- Mariah Rayl
- Division of Biological Sciences and Center for Structural and Functional Neuroscience, The University of Montana, Missoula, MT, United States of America
| | - Mishana Truitt
- Division of Biological Sciences and Center for Structural and Functional Neuroscience, The University of Montana, Missoula, MT, United States of America
| | - Aaron Held
- Division of Biological Sciences and Center for Structural and Functional Neuroscience, The University of Montana, Missoula, MT, United States of America
| | - John Sargeant
- Division of Biological Sciences and Center for Structural and Functional Neuroscience, The University of Montana, Missoula, MT, United States of America
| | - Kevin Thorsen
- Division of Biological Sciences and Center for Structural and Functional Neuroscience, The University of Montana, Missoula, MT, United States of America
| | - Jesse C. Hay
- Division of Biological Sciences and Center for Structural and Functional Neuroscience, The University of Montana, Missoula, MT, United States of America
- * E-mail:
| |
Collapse
|
16
|
Schroeter S, Beckmann S, Schmitt HD. Coat/Tether Interactions-Exception or Rule? Front Cell Dev Biol 2016; 4:44. [PMID: 27243008 PMCID: PMC4868844 DOI: 10.3389/fcell.2016.00044] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2016] [Accepted: 04/25/2016] [Indexed: 12/02/2022] Open
Abstract
Coat complexes are important for cargo selection and vesicle formation. Recent evidence suggests that they may also be involved in vesicle targeting. Tethering factors, which form an initial bridge between vesicles and the target membrane, may bind to coat complexes. In this review, we ask whether these coat/tether interactions share some common mechanisms, or whether they are special adaptations to the needs of very specific transport steps. We compare recent findings in two multisubunit tethering complexes, the Dsl1 complex and the HOPS complex, and put them into context with the TRAPP I complex as a prominent example for coat/tether interactions. We explore where coat/tether interactions are found, compare their function and structure, and comment on a possible evolution from a common ancestor of coats and tethers.
Collapse
Affiliation(s)
- Saskia Schroeter
- Neurobiology, Max Planck Institute for Biophysical Chemistry Göttingen, Germany
| | - Sabrina Beckmann
- Neurobiology, Max Planck Institute for Biophysical Chemistry Göttingen, Germany
| | - Hans Dieter Schmitt
- Neurobiology, Max Planck Institute for Biophysical Chemistry Göttingen, Germany
| |
Collapse
|
17
|
Mukherjee I, Barlowe C. Overexpression of Sly41 suppresses COPII vesicle-tethering deficiencies by elevating intracellular calcium levels. Mol Biol Cell 2016; 27:1635-49. [PMID: 27030673 PMCID: PMC4865320 DOI: 10.1091/mbc.e15-10-0704] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2015] [Accepted: 03/22/2016] [Indexed: 11/29/2022] Open
Abstract
SLY41 is a multicopy suppressor of mutations in the essential Ypt1 GTPase. Overexpression of Sly41 elevates cytosolic Ca2+ concentration, which stimulates SNARE-dependent fusion of COPII vesicles with Golgi membranes and suppresses deficiencies in Ypt1-dependent vesicle tethering. Thus Ca2+ positively regulates vesicle fusion with Golgi membranes. SLY41 was identified as a multicopy suppressor of loss of Ypt1, a Rab GTPase essential for COPII vesicle tethering at the Golgi complex. SLY41 encodes a polytopic membrane protein with homology to a class of solute transporter proteins, but how overexpression suppresses vesicle-tethering deficiencies is not known. Here we show that Sly41 is efficiently packaged into COPII vesicles and actively cycles between the ER and Golgi compartments. SLY41 displays synthetic negative genetic interactions with PMR1, which encodes the major Golgi-localized Ca2+/Mn2+ transporter and suggests that Sly41 influences cellular Ca2+ and Mn2+ homeostasis. Experiments using the calcium probe aequorin to measure intracellular Ca2+ concentrations in live cells reveal that Sly41 overexpression significantly increases cytosolic calcium levels. Although specific substrates of the Sly41 transporter were not identified, our findings indicate that localized overexpression of Sly41 to the early secretory pathway elevates cytosolic calcium levels to suppress vesicle-tethering mutants. In vitro SNARE cross-linking assays were used to directly monitor the influence of Ca2+ on tethering and fusion of COPII vesicles with Golgi membranes. Strikingly, calcium at suppressive concentrations stimulated SNARE-dependent membrane fusion when vesicle-tethering activity was reduced. These results show that calcium positively regulates the SNARE-dependent fusion stage of ER–Golgi transport.
Collapse
Affiliation(s)
- Indrani Mukherjee
- Department of Biochemistry, Geisel School of Medicine at Dartmouth, Hanover, NH 03755
| | - Charles Barlowe
- Department of Biochemistry, Geisel School of Medicine at Dartmouth, Hanover, NH 03755
| |
Collapse
|
18
|
Saraste J, Marie M. Intermediate Compartment: A Sorting Station between the Endoplasmic Reticulum and the Golgi Apparatus. ENCYCLOPEDIA OF CELL BIOLOGY 2016. [PMCID: PMC7150006 DOI: 10.1016/b978-0-12-394447-4.20013-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
|
19
|
Suga K, Saito A, Mishima T, Akagawa K. ER and Golgi stresses increase ER-Golgi SNARE Syntaxin5: Implications for organelle stress and βAPP processing. Neurosci Lett 2015. [PMID: 26219982 DOI: 10.1016/j.neulet.2015.07.017] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Unresolved endoplasmic reticulum (ER) stress causes neuronal death and has been implicated in neurodegenerative conditions such as Alzheimer's disease (AD). However, the mechanisms by which stress signals propagate from the ER through the Golgi apparatus and their effects on the transport and processing of AD-related proteins, such as β-amyloid precursor protein (βAPP), are unknown. We recently found that in the NG108-15 cell line, ER stress upregulates ER-Golgi-soluble N-ethylmaleimide-sensitive factor-attachment protein receptors (ER-Golgi SNAREs) Syx5 and Bet1. In the present study, we examined the effects of apoptosis and ER stress inducers on the expression of ER-Golgi SNARE proteins and cell viability in a primary culture of rat hippocampal neurons. An apoptosis inducer significantly downregulated the expression of ER-Golgi SNARE Syx5. ER-stress inducers upregulated the expression of Syx5 isoforms and Bet1 proteins via de novo synthesis of their mRNA transcripts. Knockdown of Syx5 during apoptosis or ER stress induction enhanced vulnerability of neurons. Additionally, we examined the effects of Golgi stress on Syx5 expression and βAPP processing. Golgi stress also induced upregulation of ER-Golgi SNARE Syx5, and concomitantly, suppressed amyloid-β peptide secretion. These findings suggest that Syx5 is a potential stress responsive factor that participates in βAPP processing and the survival pathways of neuronal cells.
Collapse
Affiliation(s)
- Kei Suga
- Department of Cell Physiology, Kyorin University School of Medicine, Mitaka, Tokyo 181-8611, Japan.
| | - Ayako Saito
- Department of Cell Physiology, Kyorin University School of Medicine, Mitaka, Tokyo 181-8611, Japan
| | - Tatsuya Mishima
- Department of Cell Physiology, Kyorin University School of Medicine, Mitaka, Tokyo 181-8611, Japan
| | - Kimio Akagawa
- Department of Cell Physiology, Kyorin University School of Medicine, Mitaka, Tokyo 181-8611, Japan
| |
Collapse
|
20
|
Flanagan JJ, Mukherjee I, Barlowe C. Examination of Sec22 Homodimer Formation and Role in SNARE-dependent Membrane Fusion. J Biol Chem 2015; 290:10657-66. [PMID: 25750128 DOI: 10.1074/jbc.m114.626911] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2014] [Indexed: 11/06/2022] Open
Abstract
Soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) protein complexes play essential roles in catalyzing intracellular membrane fusion events although the assembly pathway and molecular arrangement of SNARE complexes in membrane fusion reactions are not well understood. Here we monitored interactions of the R-SNARE protein Sec22 through a cysteine scanning approach and detected efficient formation of cross-linked Sec22 homodimers in cellular membranes when cysteine residues were positioned in the SNARE motif or C terminus of the transmembrane domain. When specific Sec22 cysteine derivatives are present on both donor COPII vesicles and acceptor Golgi membranes, the formation of disulfide cross-links provide clear readouts on trans- and cis-SNARE arrangements during this fusion event. The Sec22 transmembrane domain was required for efficient homodimer formation and for membrane fusion suggesting a functional role for Sec22 homodimers. We propose that Sec22 homodimers promote assembly of higher-order SNARE complexes to catalyze membrane fusion. Sec22 is also reported to function in macroautophagy and in formation of endoplasmic reticulum-plasma membrane contact sites therefore homodimer assembly may regulate Sec22 activity across a range of cellular processes.
Collapse
Affiliation(s)
- John J Flanagan
- From the Department of Biochemistry, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire 03755
| | - Indrani Mukherjee
- From the Department of Biochemistry, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire 03755
| | - Charles Barlowe
- From the Department of Biochemistry, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire 03755
| |
Collapse
|
21
|
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.
Collapse
|
22
|
Wang T, Grabski R, Sztul E, Hay JC. p115-SNARE interactions: a dynamic cycle of p115 binding monomeric SNARE motifs and releasing assembled bundles. Traffic 2015; 16:148-71. [PMID: 25406594 DOI: 10.1111/tra.12242] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2013] [Revised: 11/17/2014] [Accepted: 11/17/2014] [Indexed: 11/30/2022]
Abstract
Tethering factors regulate the targeting of membrane-enclosed vesicles under the control of Rab GTPases. p115, a golgin family tether, has been shown to participate in multiple stages of ER/Golgi transport. Despite extensive study, the mechanism of action of p115 is poorly understood. SNARE proteins make up the machinery for membrane fusion, and strong evidence shows that function of p115 is directly linked to its interaction with SNAREs. Using a gel filtration binding assay, we have demonstrated that in solution p115 stably interacts with ER/Golgi SNAREs rbet1 and sec22b, but not membrin and syntaxin 5. These binding preferences stemmed from selectivity of p115 for monomeric SNARE motifs as opposed to SNARE oligomers. Soluble monomeric rbet1 can compete off p115 from coat protein II (COPII) vesicles. Furthermore, excess p115 inhibits p115 function in trafficking. We conclude that monomeric SNAREs are a major binding site for p115 on COPII vesicles, and that p115 dissociates from its SNARE partners upon SNAREpin assembly. Our results suggest a model in which p115 forms a mixed p115/SNARE helix bundle with a monomeric SNARE, facilitates the binding activity and/or concentration of the SNARE at prefusion sites and is subsequently ejected as SNARE complex formation and fusion proceed.
Collapse
Affiliation(s)
- Ting Wang
- Division of Biological Sciences and Center for Structural & Functional Neuroscience, The University of Montana, Missoula, MT, USA
| | | | | | | |
Collapse
|
23
|
Shibata H, Kanadome T, Sugiura H, Yokoyama T, Yamamuro M, Moss SE, Maki M. A new role for annexin A11 in the early secretory pathway via stabilizing Sec31A protein at the endoplasmic reticulum exit sites (ERES). J Biol Chem 2014; 290:4981-4993. [PMID: 25540196 DOI: 10.1074/jbc.m114.592089] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Exit of cargo molecules from the endoplasmic reticulum (ER) for transport to the Golgi is the initial step in intracellular vesicular trafficking. The coat protein complex II (COPII) machinery is recruited to specialized regions of the ER, called ER exit sites (ERES), where it plays a central role in the early secretory pathway. It has been known for more than two decades that calcium is an essential factor in vesicle trafficking from the ER to Golgi apparatus. However, the role of calcium in the early secretory pathway is complicated and poorly understood. We and others previously identified Sec31A, an outer cage component of COPII, as an interacting protein for the penta-EF-hand calcium-binding protein ALG-2. In this study, we show that another calcium-binding protein, annexin A11 (AnxA11), physically associates with Sec31A by the adaptor function of ALG-2. Depletion of AnxA11 or ALG-2 decreases the population of Sec31A that is stably associated with the ERES and causes scattering of juxtanuclear ERES to the cell periphery. The synchronous ER-to-Golgi transport of transmembrane cargoes is accelerated in AnxA11- or ALG-2-knockdown cells. These findings suggest that AnxA11 maintains architectural and functional features of the ERES by coordinating with ALG-2 to stabilize Sec31A at the ERES.
Collapse
Affiliation(s)
- Hideki Shibata
- From the Department of Applied Molecular Biosciences, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan and.
| | - Takashi Kanadome
- From the Department of Applied Molecular Biosciences, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan and
| | - Hirofumi Sugiura
- From the Department of Applied Molecular Biosciences, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan and
| | - Takeru Yokoyama
- From the Department of Applied Molecular Biosciences, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan and
| | - Minami Yamamuro
- From the Department of Applied Molecular Biosciences, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan and
| | - Stephen E Moss
- the Department of Cell Biology, UCL Institute of Ophthalmology, University College London, 11-43 Bath Street, London EC1V 9EL, United Kingdom
| | - Masatoshi Maki
- From the Department of Applied Molecular Biosciences, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan and
| |
Collapse
|
24
|
Zacharogianni M, Aguilera-Gomez A, Veenendaal T, Smout J, Rabouille C. A stress assembly that confers cell viability by preserving ERES components during amino-acid starvation. eLife 2014; 3. [PMID: 25386913 PMCID: PMC4270098 DOI: 10.7554/elife.04132] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2014] [Accepted: 11/10/2014] [Indexed: 11/29/2022] Open
Abstract
Nutritional restriction leads to protein translation attenuation that results in the storage and degradation of free mRNAs in cytoplasmic assemblies. In this study, we show in Drosophila S2 cells that amino-acid starvation also leads to the inhibition of another major anabolic pathway, the protein transport through the secretory pathway, and to the formation of a novel reversible non-membrane bound stress assembly, the Sec body that incorporates components of the ER exit sites. Sec body formation does not depend on membrane traffic in the early secretory pathway, yet requires both Sec23 and Sec24AB. Sec bodies have liquid droplet-like properties, and they act as a protective reservoir for ERES components to rebuild a functional secretory pathway after re-addition of amino-acids acting as a part of a survival mechanism. Taken together, we propose that the formation of these structures is a novel stress response mechanism to provide cell viability during and after nutrient stress. DOI:http://dx.doi.org/10.7554/eLife.04132.001 Proteins are needed by living cells to perform vital tasks and are made from building blocks called amino-acids. However, if a cell is starved of amino-acids, protein assembly comes to a halt, and if cells are deprived of amino acids for a long time, the cell may die. To survive short periods of amino-acid starvation, the cell has developed many protective mechanisms. For example, it can start to break down existing proteins, allowing the cell to scavenge and reuse the amino-acids to make other proteins that are more important for short-term survival. The cell may also temporarily halt certain processes: for example, newly constructed proteins may no longer be transported from the cell structure where they are made—called the endoplasmic reticulum—to their final destinations in the cell. However, the protein transport apparatus is also made of proteins and needs to be protected from being broken down so that once starvation ends, the cell can more quickly return to normal working order. Zacharogianni et al. identify a strategy cells use to store and protect part of their protein transport apparatus during times of stress. Starving fruit fly cells of amino-acids causes the cells to form protective stress assemblies incorporating the proteins associated with the ‘exit sites’ that release proteins from the endoplasmic reticulum. These assemblies are called Sec bodies, and when amino-acid starvation ends, these bodies release the exit site components unharmed. This allows the cell to quickly resume protein transport and so speeds the cell's recovery. If the Sec bodies do not form, the cells are more likely to die during amino-acid starvation. The Sec bodies are distinct from previously identified stress assemblies that form in the cell during stress, but they share features with them, such as being liquid droplets. Some of these assemblies have been linked to degenerative diseases like amyotrophic lateral sclerosis (ALS). Further research will be necessary to determine if there are any similar harmful side effects associated with the formation of Sec bodies. DOI:http://dx.doi.org/10.7554/eLife.04132.002
Collapse
Affiliation(s)
| | | | - Tineke Veenendaal
- Hubrecht Institute, Royal Netherlands Academy of Arts and Sciences, Utrecht, Netherlands
| | - Jan Smout
- Hubrecht Institute, Royal Netherlands Academy of Arts and Sciences, Utrecht, Netherlands
| | - Catherine Rabouille
- Hubrecht Institute, Royal Netherlands Academy of Arts and Sciences, Utrecht, Netherlands
| |
Collapse
|
25
|
Helm JR, Bentley M, Thorsen KD, Wang T, Foltz L, Oorschot V, Klumperman J, Hay JC. Apoptosis-linked gene-2 (ALG-2)/Sec31 interactions regulate endoplasmic reticulum (ER)-to-Golgi transport: a potential effector pathway for luminal calcium. J Biol Chem 2014; 289:23609-28. [PMID: 25006245 DOI: 10.1074/jbc.m114.561829] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Luminal calcium released from secretory organelles has been suggested to play a regulatory role in vesicle transport at several steps in the secretory pathway; however, its functional roles and effector pathways have not been elucidated. Here we demonstrate for the first time that specific luminal calcium depletion leads to a significant decrease in endoplasmic reticulum (ER)-to-Golgi transport rates in intact cells. Ultrastructural analysis revealed that luminal calcium depletion is accompanied by increased accumulation of intermediate compartment proteins in COPII buds and clusters of unfused COPII vesicles at ER exit sites. Furthermore, we present several lines of evidence suggesting that luminal calcium affected transport at least in part through calcium-dependent interactions between apoptosis-linked gene-2 (ALG-2) and the Sec31A proline-rich region: 1) targeted disruption of ALG-2/Sec31A interactions caused severe defects in ER-to-Golgi transport in intact cells; 2) effects of luminal calcium and ALG-2/Sec31A interactions on transport mutually required each other; and 3) Sec31A function in transport required luminal calcium. Morphological phenotypes of disrupted ALG-2/Sec31A interactions were characterized. We found that ALG-2/Sec31A interactions were not required for the localization of Sec31A to ER exit sites per se but appeared to acutely regulate the stability and trafficking of the cargo receptor p24 and the distribution of the vesicle tether protein p115. These results represent the first outline of a mechanism that connects luminal calcium to specific protein interactions regulating vesicle trafficking machinery.
Collapse
Affiliation(s)
- Jared R Helm
- From the Division of Biological Sciences and Center for Structural and Functional Neuroscience, University of Montana, Missoula, Montana 59812-4824 and
| | - Marvin Bentley
- From the Division of Biological Sciences and Center for Structural and Functional Neuroscience, University of Montana, Missoula, Montana 59812-4824 and
| | - Kevin D Thorsen
- From the Division of Biological Sciences and Center for Structural and Functional Neuroscience, University of Montana, Missoula, Montana 59812-4824 and
| | - Ting Wang
- From the Division of Biological Sciences and Center for Structural and Functional Neuroscience, University of Montana, Missoula, Montana 59812-4824 and
| | - Lauren Foltz
- From the Division of Biological Sciences and Center for Structural and Functional Neuroscience, University of Montana, Missoula, Montana 59812-4824 and
| | - Viola Oorschot
- the Cell Microscopy Center, Department of Cell Biology, University Medical Center Utrecht, AZU Room H02.313, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands
| | - Judith Klumperman
- the Cell Microscopy Center, Department of Cell Biology, University Medical Center Utrecht, AZU Room H02.313, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands
| | - Jesse C Hay
- From the Division of Biological Sciences and Center for Structural and Functional Neuroscience, University of Montana, Missoula, Montana 59812-4824 and
| |
Collapse
|
26
|
Le Corre S, Eyre D, Drummond IA. Modulation of the secretory pathway rescues zebrafish polycystic kidney disease pathology. J Am Soc Nephrol 2014; 25:1749-59. [PMID: 24627348 DOI: 10.1681/asn.2013101060] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
Mutations in polycystin 1 and polycystin 2 are responsible for autosomal dominant polycystic kidney disease, the most common heritable human disease. Polycystins function as calcium ion channels, but their impact on cell physiology is not fully known. Recent findings suggest that polycystins could function in the maintenance of extracellular matrix integrity. In zebrafish, polycystin 2 knockdown induces kidney cysts, hydrocephalus, left/right asymmetry defects, and strong dorsal axis curvature. Here, we show that increased notochord sheath collagen deposition in polycystin 2-deficient embryos is directly linked to axis defects. Increased collagen II protein accumulation did not associate with increased col2a1 mRNA or a decrease in matrix metalloproteinase activity but, instead, it associated with increased expression of the endoplasmic reticulum/Golgi transport coat protein complex II Sec proteins. sec24D knockdown prevented dorsal axis curvature and kidney cystogenesis in polycystin 2 morphants. Nontoxic doses of brefeldin A also prevented the dorsal axis curvature formation in polycystin 2 morphants and curly up polycystin 2 mutants. Brefeldin A treatment after the onset of polycystin deficiency phenotypes reversed the curved axis phenotype but not kidney cyst progression. Our results suggest that polycystin 2 deficiency causes increased collagen II synthesis with upregulation of secretory pathway coat protein complex II components. Restoration of normal rates of secretory protein synthesis and secretion may be a new target in the treatment of autosomal dominant polycystic kidney disease.
Collapse
Affiliation(s)
- Stéphanie Le Corre
- Nephrology Division, Massachusetts General Hospital, Charlestown, Massachusetts; and
| | - David Eyre
- Department of Orthopedics and Sports Medicine, University of Washington, Seattle, Washington
| | - Iain A Drummond
- Nephrology Division, Massachusetts General Hospital, Charlestown, Massachusetts; and
| |
Collapse
|
27
|
la Cour JM, Schindler AJ, Berchtold MW, Schekman R. ALG-2 attenuates COPII budding in vitro and stabilizes the Sec23/Sec31A complex. PLoS One 2013; 8:e75309. [PMID: 24069399 PMCID: PMC3777911 DOI: 10.1371/journal.pone.0075309] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2013] [Accepted: 08/14/2013] [Indexed: 11/18/2022] Open
Abstract
Coated vesicles mediate the traffic of secretory and membrane cargo proteins from the endoplasmic reticulum (ER) to the Golgi apparatus. The coat protein complex (COPII) involved in vesicle budding is constituted by a GTPase, Sar1, the inner coat components of Sec23/Sec24 and the components of the outer coat Sec13/Sec31A. The Ca(2+)-binding protein ALG-2 was recently identified as a Sec31A binding partner and a possible link to Ca(2+) regulation of COPII vesicle budding. Here we show that ALG-2/Ca(2+) is capable of attenuating vesicle budding in vitro through interaction with an ALG-2 binding domain in the proline rich region of Sec31A. Binding of ALG-2 to Sec31A and inhibition of COPII vesicle budding is furthermore dependent on an intact Ca(2+)-binding site at EF-hand 1 of ALG-2. ALG-2 increased recruitment of COPII proteins Sec23/24 and Sec13/31A to artificial liposomes and was capable of mediating binding of Sec13/31A to Sec23. These results introduce a regulatory role for ALG-2/Ca(2+) in COPII tethering and vesicle budding.
Collapse
Affiliation(s)
- Jonas M. la Cour
- From the Department of Biology, University of Copenhagen, Copenhagen, Denmark
- * E-mail:
| | - Adam J. Schindler
- From the Biology Department, Duke University, Durham, North Carolina, United States of America
| | - Martin W. Berchtold
- From the Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Randy Schekman
- From the Department of Cellular Biochemistry, University of California at Berkeley, Berkeley, California, United States of America
| |
Collapse
|
28
|
Zheng C, Page RC, Das V, Nix JC, Wigren E, Misra S, Zhang B. Structural characterization of carbohydrate binding by LMAN1 protein provides new insight into the endoplasmic reticulum export of factors V (FV) and VIII (FVIII). J Biol Chem 2013; 288:20499-509. [PMID: 23709226 DOI: 10.1074/jbc.m113.461434] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
LMAN1 (ERGIC-53) is a key mammalian cargo receptor responsible for the export of a subset of glycoproteins from the endoplasmic reticulum. Together with its soluble coreceptor MCFD2, LMAN1 transports coagulation factors V (FV) and VIII (FVIII). Mutations in LMAN1 or MCFD2 cause the genetic bleeding disorder combined deficiency of FV and FVIII (F5F8D). The LMAN1 carbohydrate recognition domain (CRD) binds to both glycoprotein cargo and MCFD2 in a Ca(2+)-dependent manner. To understand the biochemical basis and regulation of LMAN1 binding to glycoprotein cargo, we solved crystal structures of the LMAN1-CRD bound to Man-α-1,2-Man, the terminal carbohydrate moiety of high mannose glycans. Our structural data, combined with mutagenesis and in vitro binding assays, define the central mannose-binding site on LMAN1 and pinpoint histidine 178 and glycines 251/252 as critical residues for FV/FVIII binding. We also show that mannobiose binding is relatively independent of pH in the range relevant for endoplasmic reticulum-to-Golgi traffic, but is sensitive to lowered Ca(2+) concentrations. The distinct LMAN1/MCFD2 interaction is maintained at these lowered Ca(2+) concentrations. Our results suggest that compartmental changes in Ca(2+) concentration regulate glycoprotein cargo binding and release from the LMAN1·MCFD2 complex in the early secretory pathway.
Collapse
Affiliation(s)
- Chunlei Zheng
- Genomic Medicine Institute, Cleveland Clinic, Cleveland, Ohio 44195, USA
| | | | | | | | | | | | | |
Collapse
|
29
|
D'Arcangelo JG, Stahmer KR, Miller EA. Vesicle-mediated export from the ER: COPII coat function and regulation. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2013; 1833:2464-72. [PMID: 23419775 DOI: 10.1016/j.bbamcr.2013.02.003] [Citation(s) in RCA: 110] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2012] [Revised: 02/04/2013] [Accepted: 02/05/2013] [Indexed: 11/26/2022]
Abstract
Vesicle trafficking from the endoplasmic reticulum (ER) is a vital cellular process in all eukaryotes responsible for moving secretory cargoes from the ER to the Golgi apparatus. To accomplish this feat, the cell employs a set of conserved cytoplasmic coat proteins - the coat protein II (COPII) complex - that recruit cargo into nascent buds and deform the ER membrane to drive vesicle formation. While our understanding of COPII coat mechanics has developed substantially since its discovery, we have only recently begun to appreciate the factors that regulate this complex and, in turn, ER-to-Golgi trafficking. Here, we describe these factors and their influences on COPII vesicle formation. Properties intrinsic to the GTP cycle of the coat, as well as coat structure, have critical implications for COPII vesicle trafficking. Extrinsic factors in the cytosol can modulate COPII activity through direct interaction with the coat or with scaffolding components, or by changing composition of the ER membrane. Further, lumenal and membrane-bound cargoes and cargo receptors can influence COPII-mediated trafficking in equally profound ways. Together, these factors work in concert to ensure proper cargo movement in this first step of the secretory pathway. This article is part of a Special Issue entitled: Functional and structural diversity of endoplasmic reticulum.
Collapse
|
30
|
Peterson TA, Stamnes M. ARF1-regulated coatomer directs the steady-state localization of protein kinase C epsilon at the Golgi apparatus. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2012. [PMID: 23195223 DOI: 10.1016/j.bbamcr.2012.11.011] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Protein kinase C epsilon (PKCε) contributes to multiple signaling pathways affecting human disease. The function of PKCε requires it to undergo changes in subcellular distribution in response to signaling events. While the mechanisms underlying this translocation are incompletely understood, it involves the receptor for activated C kinase protein (RACK2/β'-COP). This receptor also functions as a vesicle coat protein in the secretory pathway where it is regulated by the small GTP-binding protein ADP-ribosylation factor, ARF1. We inhibited ARF1 activation to test the requirement for RACK2/β'-COP in PKCε localization in NIH3T3 fibroblasts. We found that steady-state localization of PKCε at the Golgi complex requires ARF1-regulated RACK2/β'-COP function. By contrast, we did not observe any defects in phorbol ester-induced translocation when ARF1 was inhibited. We also found that PKCε bound to isolated membranes through two distinct mechanisms. One mechanism was dependent upon RACK2/β'-COP while a second was RACK2/β'-COP-independent and stimulated by phorbol esters. Finally, we show that RACK2/β'-COP affects the subcellular distribution of a constitutively active form of PKCε, in a manner similar to what we observed for wild-type PKCε. Together, our data support a role for RACK2/β'-COP in the steady-state localization of PKCε at the Golgi apparatus, which may be independent of its role during PKCε translocation to the cell surface.
Collapse
Affiliation(s)
- Tabitha A Peterson
- Department of Molecular Physiology & Biophysics, Roy J. and Lucille A. Carver College of Medicine, The University of Iowa, Iowa City, IA 52242, USA
| | | |
Collapse
|
31
|
Waldeck-Weiermair M, Alam MR, Khan MJ, Deak AT, Vishnu N, Karsten F, Imamura H, Graier WF, Malli R. Spatiotemporal correlations between cytosolic and mitochondrial Ca(2+) signals using a novel red-shifted mitochondrial targeted cameleon. PLoS One 2012; 7:e45917. [PMID: 23029314 PMCID: PMC3448721 DOI: 10.1371/journal.pone.0045917] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2012] [Accepted: 08/23/2012] [Indexed: 01/11/2023] Open
Abstract
The transfer of Ca2+ from the cytosol into the lumen of mitochondria is a crucial process that impacts cell signaling in multiple ways. Cytosolic Ca2+ ([Ca2+]cyto) can be excellently quantified with the ratiometric Ca2+ probe fura-2, while genetically encoded Förster resonance energy transfer (FRET)-based fluorescent Ca2+ sensors, the cameleons, are efficiently used to specifically measure Ca2+ within organelles. However, because of a significant overlap of the fura-2 emission with the spectra of the cyan and yellow fluorescent protein of most of the existing cameleons, the measurement of fura-2 and cameleons within one given cell is a complex task. In this study, we introduce a novel approach to simultaneously assess [Ca2+]cyto and mitochondrial Ca2+ ([Ca2+]mito) signals at the single cell level. In order to eliminate the spectral overlap we developed a novel red-shifted cameleon, D1GO-Cam, in which the green and orange fluorescent proteins were used as the FRET pair. This ratiometric Ca2+ probe could be successfully targeted to mitochondria and was suitable to be used simultaneously with fura-2 to correlate [Ca2+]cyto and [Ca2+]mito within same individual cells. Our data indicate that depending on the kinetics of [Ca2+]cyto rises there is a significant lag between onset of [Ca2+]cyto and [Ca2+]mito signals, pointing to a certain threshold of [Ca2+]cyto necessary to activate mitochondrial Ca2+ uptake. The temporal correlation between [Ca2+]mito and [Ca2+]cyto as well as the efficiency of the transfer of Ca2+ from the cytosol into mitochondria varies between different cell types. Moreover, slow mitochondrial Ca2+ extrusion and a desensitization of mitochondrial Ca2+ uptake cause a clear difference in patterns of mitochondrial and cytosolic Ca2+ oscillations of pancreatic beta-cells in response to D-glucose.
Collapse
Affiliation(s)
- Markus Waldeck-Weiermair
- Institute of Molecular Biology and Biochemistry, Centre of Molecular Medicine, Medical University of Graz, Graz, Austria
| | - Muhammad Rizwan Alam
- Institute of Molecular Biology and Biochemistry, Centre of Molecular Medicine, Medical University of Graz, Graz, Austria
| | - Muhammad Jadoon Khan
- Institute of Molecular Biology and Biochemistry, Centre of Molecular Medicine, Medical University of Graz, Graz, Austria
| | - Andras T. Deak
- Institute of Molecular Biology and Biochemistry, Centre of Molecular Medicine, Medical University of Graz, Graz, Austria
| | - Neelanjan Vishnu
- Institute of Molecular Biology and Biochemistry, Centre of Molecular Medicine, Medical University of Graz, Graz, Austria
| | - Felix Karsten
- Institute of Molecular Biology and Biochemistry, Centre of Molecular Medicine, Medical University of Graz, Graz, Austria
| | - Hiromi Imamura
- Precursory Research for Embryonic Science, Japan Science and Technology Agency, Tokyo, Japan
| | - Wolfgang F. Graier
- Institute of Molecular Biology and Biochemistry, Centre of Molecular Medicine, Medical University of Graz, Graz, Austria
| | - Roland Malli
- Institute of Molecular Biology and Biochemistry, Centre of Molecular Medicine, Medical University of Graz, Graz, Austria
- * E-mail:
| |
Collapse
|
32
|
Moriya T, Kayano T, Kitamura N, Hosaka YZ, Asano A, Forostyak O, Verkhratsky A, Viero C, Dayanithi G, Toescu EC, Shibuya I. Vasopressin-induced intracellular Ca²⁺ concentration responses in non-neuronal cells of the rat dorsal root ganglion. Brain Res 2012; 1483:1-12. [PMID: 22975133 DOI: 10.1016/j.brainres.2012.08.028] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2012] [Revised: 08/10/2012] [Accepted: 08/15/2012] [Indexed: 01/03/2023]
Abstract
Arginine-vasopressin (AVP) is a nonapeptide of hypothalamic origin that has been shown to exert many important cognitive and physiological functions in neurons and terminals of both the central and peripheral nervous system (CNS and PNS). Here we report for the first time that AVP induced an increase in intracellular Ca²⁺ concentration ([Ca²⁺](i)) in non-neuronal cells isolated from the rat dorsal root ganglion (DRG) and cultured in vitro. The ratiometric [Ca²⁺](i) measurements showed that AVP evoked [Ca²⁺](i) responses in the non-neuronal cells and these concentration-dependent (100 pM to 1 μM) responses increased with days in vitro in culture, reaching a maximum amplitude after 4-5 day. Immunostaining by anti-S-100 antibody revealed that more than 70% of S-100 positive cells were AVP-responsive, indicating that glial cells responded to AVP and increased their [Ca²⁺](i). The responses were inhibited by depletion of the intracellular Ca²⁺ stores or in the presence of inhibitors of phospholipase C, indicating a metabotropic response involving inositol trisphosphate, and were mediated by the V₁ subclass of AVP receptors, as evidenced by the use of the specific blockers for V₁ and OT receptors, (d(CH₂)₅¹,Tyr(Me)²,Arg⁸)-Vasopressin and (d(CH₂)₅¹,Tyr(Me)²,Thr⁴,Orn⁸,des-Gly-NH₂⁹)-Vasotocin, respectively. V(1a) but not V(1b) receptor mRNA was expressed sustainably through the culture period in cultured DRG cells. These results suggest that AVP modulates the activity of DRG glial cells via activation of V(1a) receptor.
Collapse
Affiliation(s)
- Taiki Moriya
- Department of Veterinary Physiology, Faculty of Agriculture, Tottori University, Tottori 680-8553, Japan
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
33
|
Willer EA, Malli R, Bondarenko AI, Zahler S, Vollmar AM, Graier WF, Fürst R. The vascular barrier-protecting hawthorn extract WS® 1442 raises endothelial calcium levels by inhibition of SERCA and activation of the IP3 pathway. J Mol Cell Cardiol 2012; 53:567-77. [PMID: 22814436 DOI: 10.1016/j.yjmcc.2012.07.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/14/2012] [Accepted: 07/06/2012] [Indexed: 10/28/2022]
Abstract
WS® 1442 has been proven as an effective and safe therapeutical to treat mild forms of congestive heart failure. Beyond this action, we have recently shown that WS® 1442 protects against thrombin-induced vascular barrier dysfunction and the subsequent edema formation by affecting endothelial calcium signaling. The aim of the study was to analyze the influence of WS® 1442 on intracellular calcium concentrations [Ca(2+)](i) in the human endothelium and to investigate the underlying mechanisms. Using ratiometric calcium measurements and a FRET sensor, we found that WS® 1442 concentration-dependently increased basal [Ca(2+)](i) by depletion of the endoplasmic reticulum (ER) and inhibited a subsequent histamine-triggered rise of [Ca(2+)](i). Interestingly, the augmented [Ca(2+)](i) did neither trigger an activation of the contractile machinery nor led to a barrier breakdown (macromolecular permeability). It also did not impair endothelial cell viability. As assessed by patch clamp recordings, WS® 1442 did only slightly affect endothelial Na(+)/K(+)-ATPase, but increased [Ca(2+)](i) by inhibiting the sarcoplasmic/endoplasmic reticulum Ca(2+) ATPase (SERCA) and by activating the inositol 1,4,5-trisphosphate (IP(3)) pathway. Most importantly, WS® 1442 did not induce store-operated calcium entry (SOCE), but even irreversibly prevented histamine-induced SOCE. Taken together, WS® 1442 prevented the deleterious hyperpermeability-associated rise of [Ca(2+)](i) by a preceding, non-toxic release of Ca(2+) from the ER. WS® 1442 interfered with SERCA and the IP(3) pathway without inducing SOCE. The elucidation of this intriguing mechanism helps to understand the complex pharmacology of the cardiovascular drug WS® 1442.
Collapse
Affiliation(s)
- Elisabeth A Willer
- Department of Pharmacy, Centre for Drug Research, Pharmaceutical Biology, University of Munich, Butenandtstr. 5-13, 81377 Munich, Germany
| | | | | | | | | | | | | |
Collapse
|
34
|
Yoshibori M, Yorimitsu T, Sato K. Involvement of the penta-EF-hand protein Pef1p in the Ca2+-dependent regulation of COPII subunit assembly in Saccharomyces cerevisiae. PLoS One 2012; 7:e40765. [PMID: 22792405 PMCID: PMC3394733 DOI: 10.1371/journal.pone.0040765] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2012] [Accepted: 06/13/2012] [Indexed: 11/24/2022] Open
Abstract
Although it is well established that the coat protein complex II (COPII) mediates the transport of proteins and lipids from the endoplasmic reticulum (ER) to the Golgi apparatus, the regulation of the vesicular transport event and the mechanisms that act to counterbalance the vesicle flow between the ER and Golgi are poorly understood. In this study, we present data indicating that the penta-EF-hand Ca2+-binding protein Pef1p directly interacts with the COPII coat subunit Sec31p and regulates COPII assembly in Saccharomyces cerevisiae. ALG-2, a mammalian homolog of Pef1p, has been shown to interact with Sec31A in a Ca2+-dependent manner and to have a role in stabilizing the association of the Sec13/31 complex with the membrane. However, Pef1p displayed reversed Ca2+ dependence for Sec13/31p association; only the Ca2+-free form of Pef1p bound to the Sec13/31p complex. In addition, the influence on COPII coat assembly also appeared to be reversed; Pef1p binding acted as a kinetic inhibitor to delay Sec13/31p recruitment. Our results provide further evidence for a linkage between Ca2+-dependent signaling and ER-to-Golgi trafficking, but its mechanism of action in yeast seems to be different from the mechanism reported for its mammalian homolog ALG-2.
Collapse
Affiliation(s)
- Mariko Yoshibori
- Department of Life Sciences, Graduate School of Arts and Sciences, University of Tokyo, Komaba, Meguro-ku, Tokyo, Japan
| | - Tomohiro Yorimitsu
- Department of Life Sciences, Graduate School of Arts and Sciences, University of Tokyo, Komaba, Meguro-ku, Tokyo, Japan
| | - Ken Sato
- Department of Life Sciences, Graduate School of Arts and Sciences, University of Tokyo, Komaba, Meguro-ku, Tokyo, Japan
- * E-mail:
| |
Collapse
|
35
|
Abstract
Poliovirus (PV) requires membranes of the host cell's secretory pathway to generate replication complexes (RCs) for viral RNA synthesis. Recent work identified the intermediate compartment and the Golgi apparatus as the precursors of the replication "organelles" of PV (N. Y. Hsu et al., Cell 141:799-811, 2010). In this study, we examined the effect of PV on COPII vesicles, the secretory cargo carriers that bud from the endoplasmic reticulum and homotypically fuse to form the intermediate compartment that matures into the Golgi apparatus. We found that infection by PV results in a biphasic change in functional COPII vesicle biogenesis in cells, with an early enhancement and subsequent inhibition. Concomitant with the early increase in COPII vesicle formation, we found an increase in the membrane fraction of Sec16A, a key regulator of COPII vesicle formation. We suggest that the early burst in COPII vesicle formation detected benefits PV by increasing the precursor pool required for the formation of its RCs.
Collapse
|
36
|
Thayanidhi N, Liang Y, Hasegawa H, Nycz DC, Oorschot V, Klumperman J, Hay JC. R-SNARE ykt6 resides in membrane-associated protease-resistant protein particles and modulates cell cycle progression when over-expressed. Biol Cell 2012; 104:397-417. [DOI: 10.1111/boc.201100048] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2011] [Accepted: 03/08/2012] [Indexed: 12/11/2022]
|
37
|
Abstract
Protein traffic is necessary to maintain homeostasis in all eukaryotic organisms. All newly synthesized secretory proteins destined to the secretory and endolysosmal systems are transported from the endoplasmic reticulum to the Golgi before delivery to their final destinations. Here, we describe the COPII and COPI coating machineries that generate carrier vesicles and the tethers and SNAREs that mediate COPII and COPI vesicle fusion at the ER-Golgi interface.
Collapse
Affiliation(s)
- Tomasz Szul
- Department of Cell Biology, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | | |
Collapse
|
38
|
Zanetti G, Pahuja KB, Studer S, Shim S, Schekman R. COPII and the regulation of protein sorting in mammals. Nat Cell Biol 2011; 14:20-8. [PMID: 22193160 DOI: 10.1038/ncb2390] [Citation(s) in RCA: 276] [Impact Index Per Article: 21.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Secretory proteins are transported to the Golgi complex in vesicles that bud from the endoplasmic reticulum. The cytoplasmic coat protein complex II (COPII) is responsible for cargo sorting and vesicle morphogenesis. COPII was first described in Saccharomyces cerevisiae, but its basic function is conserved throughout all eukaryotes. Nevertheless, the COPII coat has adapted to the higher complexity of mammalian physiology, achieving more sophisticated levels of secretory regulation. In this review we cover aspects of mammalian COPII-mediated regulation of secretion, in particular related to the function of COPII paralogues, the spatial organization of cargo export and the role of accessory proteins.
Collapse
Affiliation(s)
- Giulia Zanetti
- Department of Molecular and Cell Biology and Howard Hughes Medical Institute, University of California at Berkeley, Berkeley, California 94720, USA
| | | | | | | | | |
Collapse
|
39
|
Maki M, Suzuki H, Shibata H. Structure and function of ALG-2, a penta-EF-hand calcium-dependent adaptor protein. SCIENCE CHINA-LIFE SCIENCES 2011; 54:770-9. [PMID: 21786200 DOI: 10.1007/s11427-011-4204-8] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2011] [Accepted: 06/05/2011] [Indexed: 12/29/2022]
Abstract
ALG-2 (a gene product of PDCD6) is a 22-kD protein containing five serially repetitive EF-hand structures and belongs to the penta-EF-hand (PEF) family, including the subunits of typical calpains. ALG-2 is the most conserved protein among the PEF family members and its homologs are widely found in eukaryotes. X-ray crystal structures of various PEF proteins including ALG-2 have common features: presence of eight α-helices and dimer formation via paired EF5s that are positioned in anti-parallel orientation. ALG-2 forms a homodimer and a heterodimer with its closest paralog peflin. Like calmodulin, a well-known four-EF-hand protein, ALG-2 interacts with various proteins in a Ca(2+)-dependent fashion, but the binding motifs are completely different. With some exceptions, ALG-2-interacting proteins commonly contain Pro-rich regions, and ALG-2 recognizes at least two distinct Pro-containing motifs: PPYP(X)nYP (X, variable; n=4 in ALIX and PLSCR3) and PXPGF (represented by Sec31A). A shorter alternatively spliced isoform, lacking two residues and designated ALG-2(ΔGF122), does not bind ALIX but maintains binding capacity to Sec31A. X-ray crystal structural analyses have revealed that binding of calcium ions induces the configuration of the side chain of R125 so that it opens Pocket 1, which accepts PPYP, but Pocket 1 remains closed in the case of ALG-2(ΔGF122). ALG-2 dimer has two ligand-binding sites, each in a monomer molecule, and appears to function as a Ca(2+)-dependent adaptor protein to either stabilize a preformed complex or to bridge two proteins on scaffolds in systems of the endosomal sorting complex required for transport (ESCRT) and ER-to-Golgi transport.
Collapse
Affiliation(s)
- Masatoshi Maki
- Department of Applied Molecular Biosciences, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Japan.
| | | | | |
Collapse
|
40
|
Affiliation(s)
- Devon Jensen
- Department of Molecular and Cell Biology, and Howard Hughes Medical Institute, University of California at Berkeley, Berkeley, CA 94720, USA
| | | |
Collapse
|
41
|
Sequential interactions with Sec23 control the direction of vesicle traffic. Nature 2011; 473:181-6. [PMID: 21532587 PMCID: PMC3093450 DOI: 10.1038/nature09969] [Citation(s) in RCA: 147] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2010] [Accepted: 02/23/2011] [Indexed: 11/24/2022]
Abstract
How the directionality of vesicle traffic is achieved remains an important unanswered question in cell biology. The Sec23p/Sec24p coat complex sorts the fusion machinery (SNAREs) into vesicles as they bud from the endoplasmic reticulum. Vesicle tethering to the Golgi begins when the tethering factor TRAPPI binds to Sec23p. Where the coat is released and how this event relates to membrane fusion is unknown. Here we use a yeast transport assay to demonstrate that an ER-derived vesicle retains its coat until it reaches the Golgi. A Golgi-associated kinase, Hrr25p (CK1δ ortholog), then phosphorylates the Sec23p/Sec24p complex. Coat phosphorylation and dephosphorylation are needed for vesicle fusion and budding, respectively. Additionally, we show that Sec23p interacts in a sequential manner with different binding partners, including TRAPPI and Hrr25p, to ensure the directionality of ER-Golgi traffic and prevent the back-fusion of a COPII vesicle with the ER. These events are conserved in mammalian cells.
Collapse
|
42
|
|
43
|
Fluorescent Genetically Encoded Calcium Indicators and Their In Vivo Application. FLUORESCENT PROTEINS II 2011. [DOI: 10.1007/4243_2011_29] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
|
44
|
Routledge KE, Gupta V, Balch WE. Emergent properties of proteostasis-COPII coupled systems in human health and disease. Mol Membr Biol 2010; 27:385-97. [DOI: 10.3109/09687688.2010.524894] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
|
45
|
The ALG-2 binding site in Sec31A influences the retention kinetics of Sec31A at the endoplasmic reticulum exit sites as revealed by live-cell time-lapse imaging. Biosci Biotechnol Biochem 2010; 74:1819-26. [PMID: 20834162 DOI: 10.1271/bbb.100215] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
ALG-2, a member of the penta-EF-hand protein family, interacts Ca²+-dependently with a COPII component, Sec31A. In this study, we first established HeLa cells stably expressing green fluorescent protein-fused ALG-2 (GFP-ALG-2) and red fluorescent protein-fused Sec31A (Sec31A-RFP). After inducing Ca²+-mobilization, the cytoplasmic distribution of GFP-ALG-2 changed from a diffuse to a punctate pattern, which extensively overlapped with the Sec31A-RFP-positive structures, indicating that ALG-2 is recruited to the endoplasmic reticulum exit sites (ERES) in living cells. Next, overlay experiments with biotin-labeled ALG-2 were done to dissect the ALG-2 binding site (ABS). They revealed that a sequence comprising amino acid residues 839-851 in the Pro-rich region was necessary and sufficient for direct binding to ALG-2. Finally, fluorescence recovery after photobleaching analysis indicated that the ABS deletion reduced the high-affinity population of Sec31A to the ERES, suggesting that the ABS is one of the key determinants of the retention kinetics of Sec31A at ERES.
Collapse
|
46
|
Angers CG, Merz AJ. New links between vesicle coats and Rab-mediated vesicle targeting. Semin Cell Dev Biol 2010; 22:18-26. [PMID: 20643221 DOI: 10.1016/j.semcdb.2010.07.003] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2010] [Revised: 07/07/2010] [Accepted: 07/09/2010] [Indexed: 12/24/2022]
Abstract
Vesicle trafficking is a highly regulated process that transports proteins and other cargoes through eukaryotic cells while maintaining cellular organization and compartmental identity. In order for cargo to reach the correct destination, each step of trafficking must impart specificity. During vesicle formation, this is achieved by coat proteins, which selectively incorporate cargo into the nascent vesicle. Classically, vesicle coats are thought to dissociate shortly after budding. However, recent studies suggest that coat proteins can remain on the vesicle en route to their destination, imparting targeting specificity by physically and functionally interacting with Rab-regulated tethering systems. This review focuses on how interactions among Rab GTPases, tethering factors, SNARE proteins, and vesicle coats contribute to vesicle targeting, fusion, and coat dynamics.
Collapse
Affiliation(s)
- Cortney G Angers
- Department of Biochemistry, University of Washington School of Medicine, Seattle, WA 98195-3750, USA
| | | |
Collapse
|
47
|
Trahey M, Hay JC. Transport vesicle uncoating: it's later than you think. F1000 BIOLOGY REPORTS 2010; 2:47. [PMID: 20706600 PMCID: PMC2919759 DOI: 10.3410/b2-47] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Transport vesicle coat proteins play active roles in vesicle cargo sorting as well as membrane deformation and fission during vesicle biogenesis. For years, it was assumed that this was the extent of the coats’ function and that the coats depolymerized immediately after vesicle budding, leaving the exposed fusion machinery free to find, dock, and fuse with the proper target membrane. Recently, however, it has become increasingly clear that the coat remains on transport vesicles during their post-budding life and in fact helps properly pair up the vesicle with its intended target membrane. These data have brought up urgent questions about exactly when vesicles do uncoat and how uncoating is regulated. Here, we summarize the latest round of evidence for post-budding roles for coats, including a few hints about how the uncoating process may be coupled to docking and fusion. We also speculate about the possibility of post-fusion functions for residual coats.
Collapse
Affiliation(s)
- Meg Trahey
- Division of Biological Sciences and Center for Structural and Functional Neuroscience, The University of Montana, 32 Campus Drive, HS104, Missoula, MT 59812-4824, USA
| | | |
Collapse
|