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Liu M, Duan Y, Dong J, Zhang K, Jin X, Gao M, Jia H, Chen J, Liu M, Wei M, Zhong X. Early signs of neurodegenerative diseases: Possible mechanisms and targets for Golgi stress. Biomed Pharmacother 2024; 175:116646. [PMID: 38692058 DOI: 10.1016/j.biopha.2024.116646] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2024] [Revised: 04/17/2024] [Accepted: 04/24/2024] [Indexed: 05/03/2024] Open
Abstract
The Golgi apparatus plays a crucial role in mediating the modification, transport, and sorting of intracellular proteins and lipids. The morphological changes occurring in the Golgi apparatus are exceptionally important for maintaining its function. When exposed to external pressure or environmental stimulation, the Golgi apparatus undergoes adaptive changes in both structure and function, which are known as Golgi stress. Although certain signal pathway responses or post-translational modifications have been observed following Golgi stress, further research is needed to comprehensively summarize and understand the related mechanisms. Currently, there is evidence linking Golgi stress to neurodegenerative diseases; however, the role of Golgi stress in the progression of neurodegenerative diseases such as Alzheimer's disease remains largely unexplored. This review focuses on the structural and functional alterations of the Golgi apparatus during stress, elucidating potential mechanisms underlying the involvement of Golgi stress in regulating immunity, autophagy, and metabolic processes. Additionally, it highlights the pivotal role of Golgi stress as an early signaling event implicated in the pathogenesis and progression of neurodegenerative diseases. Furthermore, this study summarizes prospective targets that can be therapeutically exploited to mitigate neurodegenerative diseases by targeting Golgi stress. These findings provide a theoretical foundation for identifying novel breakthroughs in preventing and treating neurodegenerative diseases.
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Affiliation(s)
- Mengyu Liu
- School of Pharmacy, China Medical University, Shenyang, Liaoning 110122, China
| | - Ying Duan
- Liaoning Maternal and Child Health Hospital, Shayang, Liaoning 110005, China
| | - Jianru Dong
- School of Pharmacy, China Medical University, Shenyang, Liaoning 110122, China
| | - Kaisong Zhang
- School of Pharmacy, China Medical University, Shenyang, Liaoning 110122, China
| | - Xin Jin
- School of Pharmacy, China Medical University, Shenyang, Liaoning 110122, China
| | - Menglin Gao
- School of Pharmacy, China Medical University, Shenyang, Liaoning 110122, China
| | - Huachao Jia
- School of Pharmacy, China Medical University, Shenyang, Liaoning 110122, China
| | - Ju Chen
- School of Pharmacy, China Medical University, Shenyang, Liaoning 110122, China
| | - Mingyan Liu
- School of Pharmacy, China Medical University, Shenyang, Liaoning 110122, China.
| | - Minjie Wei
- School of Pharmacy, China Medical University, Shenyang, Liaoning 110122, China; Liaoning Medical Diagnosis and Treatment Center, Shenyang, Liaoning 110167, China.
| | - Xin Zhong
- School of Pharmacy, China Medical University, Shenyang, Liaoning 110122, China.
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2
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Liu L, Wang Z, Fang Y, Yang R, Pu Y, Meng X, Liu W. Small GTPase Rab7 is involved in stress adaptation to carbon starvation to ensure the induced cellulase biosynthesis in Trichoderma reesei. BIOTECHNOLOGY FOR BIOFUELS AND BIOPRODUCTS 2024; 17:55. [PMID: 38643207 PMCID: PMC11032611 DOI: 10.1186/s13068-024-02504-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2024] [Accepted: 04/12/2024] [Indexed: 04/22/2024]
Abstract
BACKGROUND The saprophytic filamentous fungus Trichoderma reesei represents one of the most prolific cellulase producers. The bulk production of lignocellulolytic enzymes by T. reesei not only relies on the efficient transcription of cellulase genes but also their efficient secretion after being translated. However, little attention has been paid to the functional roles of the involved secretory pathway in the high-level production of cellulases in T. reesei. Rab GTPases are key regulators in coordinating various vesicle trafficking associated with the eukaryotic secretory pathway. Specifically, Rab7 is a representative GTPase regulating the transition of the early endosome to the late endosome followed by its fusion to the vacuole as well as homotypic vacuole fusion. Although crosstalk between the endosomal/vacuolar pathway and the secretion pathway has been reported, the functional role of Rab7 in cellulase production in T. reesei remains unknown. RESULTS A TrRab7 was identified and characterized in T. reesei. TrRab7 was shown to play important roles in T. reesei vegetative growth and vacuole morphology. Whereas knock-down of Trrab7 significantly compromised the induced production of T. reesei cellulases, overexpression of the key transcriptional activator, Xyr1, restored the production of cellulases in the Trrab7 knock-down strain (Ptcu-rab7KD) on glucose, indicating that the observed defective cellulase biosynthesis results from the compromised cellulase gene transcription. Down-regulation of Trrab7 was also found to make T. reesei more sensitive to various stresses including carbon starvation. Interestingly, overexpression of Snf1, a serine/threonine protein kinase known as an energetic sensor, partially restored the cellulase production of Ptcu-rab7KD on Avicel, implicating that TrRab7 is involved in an energetic adaptation to carbon starvation which contributes to the successful cellulase gene expression when T. reesei is transferred from glucose to cellulose. CONCLUSIONS TrRab7 was shown to play important roles in T. reesei development and a stress response to carbon starvation resulting from nutrient shift. This adaptation may allow T. reesei to successfully initiate the inducing process leading to efficient cellulase production. The present study provides useful insights into the functional involvement of the endosomal/vacuolar pathway in T. reesei development and hydrolytic enzyme production.
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Affiliation(s)
- Lin Liu
- State Key Laboratory of Microbial Technology, Microbiology Technology Institute, Shandong University, No. 72 Binhai Road, Qingdao, 266237, People's Republic of China
| | - Zhixing Wang
- State Key Laboratory of Microbial Technology, Microbiology Technology Institute, Shandong University, No. 72 Binhai Road, Qingdao, 266237, People's Republic of China
| | - Yu Fang
- State Key Laboratory of Microbial Technology, Microbiology Technology Institute, Shandong University, No. 72 Binhai Road, Qingdao, 266237, People's Republic of China
| | - Renfei Yang
- State Key Laboratory of Microbial Technology, Microbiology Technology Institute, Shandong University, No. 72 Binhai Road, Qingdao, 266237, People's Republic of China
| | - Yi Pu
- State Key Laboratory of Microbial Technology, Microbiology Technology Institute, Shandong University, No. 72 Binhai Road, Qingdao, 266237, People's Republic of China
| | - Xiangfeng Meng
- State Key Laboratory of Microbial Technology, Microbiology Technology Institute, Shandong University, No. 72 Binhai Road, Qingdao, 266237, People's Republic of China.
| | - Weifeng Liu
- State Key Laboratory of Microbial Technology, Microbiology Technology Institute, Shandong University, No. 72 Binhai Road, Qingdao, 266237, People's Republic of China.
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Kankanamge D, Tennakoon M, Karunarathne A, Gautam N. G protein gamma subunit, a hidden master regulator of GPCR signaling. J Biol Chem 2022; 298:102618. [PMID: 36272647 PMCID: PMC9678972 DOI: 10.1016/j.jbc.2022.102618] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2022] [Revised: 10/10/2022] [Accepted: 10/14/2022] [Indexed: 11/21/2022] Open
Abstract
Heterotrimeric G proteins (αβγ subunits) that are activated by G protein-coupled receptors (GPCRs) mediate the biological responses of eukaryotic cells to extracellular signals. The α subunits and the tightly bound βγ subunit complex of G proteins have been extensively studied and shown to control the activity of effector molecules. In contrast, the potential roles of the large family of γ subunits have been less studied. In this review, we focus on present knowledge about these proteins. Induced loss of individual γ subunit types in animal and plant models result in strikingly distinct phenotypes indicating that γ subtypes play important and specific roles. Consistent with these findings, downregulation or upregulation of particular γ subunit types result in various types of cancers. Clues about the mechanistic basis of γ subunit function have emerged from imaging the dynamic behavior of G protein subunits in living cells. This shows that in the basal state, G proteins are not constrained to the plasma membrane but shuttle between membranes and on receptor activation βγ complexes translocate reversibly to internal membranes. The translocation kinetics of βγ complexes varies widely and is determined by the membrane affinity of the associated γ subtype. On translocating, some βγ complexes act on effectors in internal membranes. The variation in translocation kinetics determines differential sensitivity and adaptation of cells to external signals. Membrane affinity of γ subunits is thus a parsimonious and elegant mechanism that controls information flow to internal cell membranes while modulating signaling responses.
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Affiliation(s)
- Dinesh Kankanamge
- Department of Anesthesiology, Washington University School of Medicine, St Louis, Missouri, USA
| | - Mithila Tennakoon
- Department of Chemistry, St Louis University, St Louis, Missouri, USA
| | | | - N Gautam
- Department of Anesthesiology, Washington University School of Medicine, St Louis, Missouri, USA; Department of Genetics, Washington University School of Medicine, St Louis, Missouri, USA.
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Cui L, Li H, Xi Y, Hu Q, Liu H, Fan J, Xiang Y, Zhang X, Shui W, Lai Y. Vesicle trafficking and vesicle fusion: mechanisms, biological functions, and their implications for potential disease therapy. MOLECULAR BIOMEDICINE 2022; 3:29. [PMID: 36129576 PMCID: PMC9492833 DOI: 10.1186/s43556-022-00090-3] [Citation(s) in RCA: 26] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Accepted: 07/12/2022] [Indexed: 11/10/2022] Open
Abstract
Intracellular vesicle trafficking is the fundamental process to maintain the homeostasis of membrane-enclosed organelles in eukaryotic cells. These organelles transport cargo from the donor membrane to the target membrane through the cargo containing vesicles. Vesicle trafficking pathway includes vesicle formation from the donor membrane, vesicle transport, and vesicle fusion with the target membrane. Coat protein mediated vesicle formation is a delicate membrane budding process for cargo molecules selection and package into vesicle carriers. Vesicle transport is a dynamic and specific process for the cargo containing vesicles translocation from the donor membrane to the target membrane. This process requires a group of conserved proteins such as Rab GTPases, motor adaptors, and motor proteins to ensure vesicle transport along cytoskeletal track. Soluble N-ethyl-maleimide-sensitive factor (NSF) attachment protein receptors (SNARE)-mediated vesicle fusion is the final process for vesicle unloading the cargo molecules at the target membrane. To ensure vesicle fusion occurring at a defined position and time pattern in eukaryotic cell, multiple fusogenic proteins, such as synaptotagmin (Syt), complexin (Cpx), Munc13, Munc18 and other tethering factors, cooperate together to precisely regulate the process of vesicle fusion. Dysfunctions of the fusogenic proteins in SNARE-mediated vesicle fusion are closely related to many diseases. Recent studies have suggested that stimulated membrane fusion can be manipulated pharmacologically via disruption the interface between the SNARE complex and Ca2+ sensor protein. Here, we summarize recent insights into the molecular mechanisms of vesicle trafficking, and implications for the development of new therapeutics based on the manipulation of vesicle fusion.
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TRPP2 ion channels: The roles in various subcellular locations. Biochimie 2022; 201:116-127. [PMID: 35760123 DOI: 10.1016/j.biochi.2022.06.010] [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: 11/14/2021] [Revised: 06/14/2022] [Accepted: 06/22/2022] [Indexed: 11/21/2022]
Abstract
TRPP2 (PC2, PKD2 or Polycytin-2), encoded by PKD2 gene, belongs to the nonselective cation channel TRP family. Recently, the three-dimensional structure of TRPP2 was constructed. TRPP2 mainly functions in three subcellular compartments: endoplasmic reticulum, plasma membrane and primary cilia. TRPP2 can act as a calcium-activated intracellular calcium release channel on the endoplasmic reticulum. TRPP2 also interacts with other Ca2+ release channels to regulate calcium release, like IP3R and RyR2. TRPP2 acts as an ion channel regulated by epidermal growth factor through activation of downstream factors in the plasma membrane. TRPP2 binding to TRPC1 in the plasma membrane or endoplasmic reticulum is associated with mechanosensitivity. In cilium, TRPP2 was found to combine with PKD1 and TRPV4 to form a complex related to mechanosensitivity. Because TRPP2 is involved in regulating intracellular ion concentration, TRPP2 mutations often lead to autosomal dominant polycystic kidney disease, which may also be associated with cardiovascular disease. In this paper, we review the molecular structure of TRPP2, the subcellular localization of TRPP2, the related functions and mechanisms of TRPP2 at different sites, and the diseases related to TRPP2.
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6
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Noh SH, Kim YJ, Lee MG. Autophagy-Related Pathways in Vesicular Unconventional Protein Secretion. Front Cell Dev Biol 2022; 10:892450. [PMID: 35774225 PMCID: PMC9237382 DOI: 10.3389/fcell.2022.892450] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2022] [Accepted: 05/26/2022] [Indexed: 12/14/2022] Open
Abstract
Cellular proteins directed to the plasma membrane or released into the extracellular space can undergo a number of different pathways. Whereas the molecular mechanisms that underlie conventional ER-to-Golgi trafficking are well established, those associated with the unconventional protein secretion (UPS) pathways remain largely elusive. A pathway with an emerging role in UPS is autophagy. Although originally known as a degradative process for maintaining intracellular homeostasis, recent studies suggest that autophagy has diverse biological roles besides its disposal function and that it is mechanistically involved in the UPS of various secretory cargos including both leaderless soluble and Golgi-bypassing transmembrane proteins. Here, we summarize current knowledge of the autophagy-related UPS pathways, describing and comparing diverse features in the autophagy-related UPS cargos and autophagy machineries utilized in UPS. Additionally, we also suggest potential directions that further research in this field can take.
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Affiliation(s)
- Shin Hye Noh
- Severance Biomedical Science Institute, Yonsei University College of Medicine, Seoul, South Korea
| | - Ye Jin Kim
- Department of Pharmacology, Brain Korea 21 Project for Medical Science, Yonsei University College of Medicine, Seoul, South Korea
| | - Min Goo Lee
- Severance Biomedical Science Institute, Yonsei University College of Medicine, Seoul, South Korea
- Department of Pharmacology, Brain Korea 21 Project for Medical Science, Yonsei University College of Medicine, Seoul, South Korea
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7
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Nakano A. The Golgi Apparatus and its Next-Door Neighbors. Front Cell Dev Biol 2022; 10:884360. [PMID: 35573670 PMCID: PMC9096111 DOI: 10.3389/fcell.2022.884360] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2022] [Accepted: 03/28/2022] [Indexed: 12/20/2022] Open
Abstract
The Golgi apparatus represents a central compartment of membrane traffic. Its apparent architecture, however, differs considerably among species, from unstacked and scattered cisternae in the budding yeast Saccharomyces cerevisiae to beautiful ministacks in plants and further to gigantic ribbon structures typically seen in mammals. Considering the well-conserved functions of the Golgi, its fundamental structure must have been optimized despite seemingly different architectures. In addition to the core layers of cisternae, the Golgi is usually accompanied by next-door compartments on its cis and trans sides. The trans-Golgi network (TGN) can be now considered as a compartment independent from the Golgi stack. On the cis side, the intermediate compartment between the ER and the Golgi (ERGIC) has been known in mammalian cells, and its functional equivalent is now suggested for yeast and plant cells. High-resolution live imaging is extremely powerful for elucidating the dynamics of these compartments and has revealed amazing similarities in their behaviors, indicating common mechanisms conserved along the long course of evolution. From these new findings, I would like to propose reconsideration of compartments and suggest a new concept to describe their roles comprehensively around the Golgi and in the post-Golgi trafficking.
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8
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Del Giudice S, De Luca V, Parizadeh S, Russo D, Luini A, Di Martino R. Endogenous and Exogenous Regulatory Signaling in the Secretory Pathway: Role of Golgi Signaling Molecules in Cancer. Front Cell Dev Biol 2022; 10:833663. [PMID: 35399533 PMCID: PMC8984190 DOI: 10.3389/fcell.2022.833663] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2021] [Accepted: 03/03/2022] [Indexed: 11/29/2022] Open
Abstract
The biosynthetic transport route that constitutes the secretory pathway plays a fundamental role in the cell, providing to the synthesis and transport of around one third of human proteins and most lipids. Signaling molecules within autoregulatory circuits on the intracellular membranes of the secretory pathway regulate these processes, especially at the level of the Golgi complex. Indeed, cancer cells can hijack several of these signaling molecules, and therefore also the underlying regulated processes, to bolster their growth or gain more aggressive phenotypes. Here, we review the most important autoregulatory circuits acting on the Golgi, emphasizing the role of specific signaling molecules in cancer. In fact, we propose to draw awareness to highlight the Golgi-localized regulatory systems as potential targets in cancer therapy.
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Affiliation(s)
| | | | | | | | - Alberto Luini
- *Correspondence: Alberto Luini, ; Rosaria Di Martino,
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9
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Reyes-Alvarez E, Walker TJ, Mulligan LM. Evaluating Cell Membrane Localization and Intracellular Transport of Proteins by Biotinylation. Methods Mol Biol 2022; 2508:197-209. [PMID: 35737242 DOI: 10.1007/978-1-0716-2376-3_15] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Protein translocation to the cell membrane and transport through intracellular compartments are dynamic processes frequently altered in cancer cells. Abnormal protein localization can affect key cell functions, including transduction of extracellular signals and organization of the cytoskeleton, significantly affecting oncogenicity and therapeutic responses. In this chapter, we describe a surface protein biotinylation method that allows the study of membrane localization and endosomal transport of membrane-associated proteins. Surface biotinylation can be used to evaluate baseline protein levels at the membrane, and other processes such as internalization, recycling, and degradation of proteins in response to different treatments or as a consequence of oncogenic mutations. Further, the combination of this technique with other strategies, such as treatments with transport inhibitors, allows investigation of specific steps of protein trafficking through the cell.
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Affiliation(s)
- Eduardo Reyes-Alvarez
- Division of Cancer Biology and Genetics, Cancer Research Institute, Queen's University, Kingston, ON, Canada
| | - Timothy J Walker
- Division of Cancer Biology and Genetics, Cancer Research Institute, Queen's University, Kingston, ON, Canada
| | - Lois M Mulligan
- Division of Cancer Biology and Genetics, Cancer Research Institute, Queen's University, Kingston, ON, Canada.
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10
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Yamazaki Y, Eura Y, Kokame K. V-ATPase V0a1 promotes Weibel-Palade body biogenesis through the regulation of membrane fission. eLife 2021; 10:71526. [PMID: 34904569 PMCID: PMC8718113 DOI: 10.7554/elife.71526] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Accepted: 12/13/2021] [Indexed: 01/09/2023] Open
Abstract
Membrane fission, the division of a membrane-bound structure into two discrete compartments, is essential for diverse cellular events, such as endocytosis and vesicle/granule biogenesis; however, the process remains unclear. The hemostatic protein von Willebrand factor is produced in vascular endothelial cells and packaged into specialized secretory granules, Weibel–Palade bodies (WPBs) at the trans-Golgi network (TGN). Here, we reported that V0a1, a V-ATPase component, is required for the membrane fission of WPBs. We identified two V0a isoforms in distinct populations of WPBs in cultured endothelial cells, V0a1 and V0a2, on mature and nascent WPBs, respectively. Although WPB buds were formed, WPBs could not separate from the TGN in the absence of V0a1. Screening using dominant–negative forms of known membrane fission regulators revealed protein kinase D (PKD) as an essential factor in biogenesis of WPBs. Further, we showed that the induction of wild-type PKDs in V0a1-depleted cells does not support the segregation of WPBs from the TGN; suggesting a primary role of V0a1 in the membrane fission of WPBs. The identification of V0a1 as a new membrane fission regulator should facilitate the understanding of molecular events that enable membrane fission.
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Affiliation(s)
- Yasuo Yamazaki
- Department of Molecular Pathogenesis, National Cerebral and Cardiovascular Center, Osaka, Japan
| | - Yuka Eura
- Department of Molecular Pathogenesis, National Cerebral and Cardiovascular Center, Osaka, Japan
| | - Koichi Kokame
- Department of Molecular Pathogenesis, National Cerebral and Cardiovascular Center, Osaka, Japan
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11
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Ford C, Parchure A, von Blume J, Burd CG. Cargo sorting at the trans-Golgi network at a glance. J Cell Sci 2021; 134:jcs259110. [PMID: 34870705 PMCID: PMC8714066 DOI: 10.1242/jcs.259110] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The Golgi functions principally in the biogenesis and trafficking of glycoproteins and lipids. It is compartmentalized into multiple flattened adherent membrane sacs termed cisternae, which each contain a distinct repertoire of resident proteins, principally enzymes that modify newly synthesized proteins and lipids sequentially as they traffic through the stack of Golgi cisternae. Upon reaching the final compartments of the Golgi, the trans cisterna and trans-Golgi network (TGN), processed glycoproteins and lipids are packaged into coated and non-coated transport carriers derived from the trans Golgi and TGN. The cargoes of clathrin-coated vesicles are chiefly residents of endo-lysosomal organelles, while uncoated carriers ferry cargo to the cell surface. There are outstanding questions regarding the mechanisms of protein and lipid sorting within the Golgi for export to different organelles. Nonetheless, conceptual advances have begun to define the key molecular features of cargo clients and the mechanisms underlying their sorting into distinct export pathways, which we have collated in this Cell Science at a Glance article and the accompanying poster.
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Affiliation(s)
| | | | - Julia von Blume
- Department of Cell Biology, Yale School of Medicine, Yale University, New Haven, CT 06520, USA
| | - Christopher G. Burd
- Department of Cell Biology, Yale School of Medicine, Yale University, New Haven, CT 06520, USA
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12
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Backman APE, Mattjus P. Who moves the sphinx? An overview of intracellular sphingolipid transport. Biochim Biophys Acta Mol Cell Biol Lipids 2021; 1866:159021. [PMID: 34339859 DOI: 10.1016/j.bbalip.2021.159021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Revised: 06/24/2021] [Accepted: 06/27/2021] [Indexed: 11/28/2022]
Abstract
Lipid bilayers function as boundaries that enclose their content from the surrounding media, and the composition of different membrane types is accurately and dynamically tailored so that they can perform their function. To achieve this balance, lipid biosynthetic machinery and lipid trafficking events are intertwined into an elegant network. In this review, we focus on the intracellular movement of sphingolipids mediated by sphingolipid transfer proteins. Additionally, we will focus on the best characterized and understood mammalian sphingolipid transfer proteins and provide an overview of how they are hypothesized to function. Some are already well understood, while others remain enigmatic. A few are actual lipid transfer proteins, moving lipids from membrane to membrane, while others may have more of a sensor role, possibly reacting to changes in the concentrations of their ligands. Considering the substrates available for cytosolic sphingolipid transfer proteins, one open question that is discussed is whether galactosylceramide is a target. Another question is the exact mechanics by which sphingolipid transfer proteins are targeted to different organelles, such as how four phosphate adapter protein-2, FAPP2 is targeted to the endoplasmic reticulum. The aim of this review is to discuss what is known within the field today and to provide a basic understanding of how these proteins may work.
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Affiliation(s)
- Anders P E Backman
- Biochemistry, Faculty of Science and Engineering, Åbo Akademi University, Turku, Finland
| | - Peter Mattjus
- Biochemistry, Faculty of Science and Engineering, Åbo Akademi University, Turku, Finland.
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13
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The PKD-Dependent Biogenesis of TGN-to-Plasma Membrane Transport Carriers. Cells 2021; 10:cells10071618. [PMID: 34203456 PMCID: PMC8303525 DOI: 10.3390/cells10071618] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Revised: 06/14/2021] [Accepted: 06/24/2021] [Indexed: 01/30/2023] Open
Abstract
Membrane trafficking is essential for processing and transport of proteins and lipids and to establish cell compartmentation and tissue organization. Cells respond to their needs and control the quantity and quality of protein secretion accordingly. In this review, we focus on a particular membrane trafficking route from the trans-Golgi network (TGN) to the cell surface: protein kinase D (PKD)-dependent pathway for constitutive secretion mediated by carriers of the TGN to the cell surface (CARTS). Recent findings highlight the importance of lipid signaling by organelle membrane contact sites (MCSs) in this pathway. Finally, we discuss our current understanding of multiple signaling pathways for membrane trafficking regulation mediated by PKD, G protein-coupled receptors (GPCRs), growth factors, metabolites, and mechanosensors.
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14
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Tennakoon M, Senarath K, Kankanamge D, Ratnayake K, Wijayaratna D, Olupothage K, Ubeysinghe S, Martins-Cannavino K, Hébert TE, Karunarathne A. Subtype-dependent regulation of Gβγ signalling. Cell Signal 2021; 82:109947. [PMID: 33582184 PMCID: PMC8026654 DOI: 10.1016/j.cellsig.2021.109947] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Revised: 02/01/2021] [Accepted: 02/02/2021] [Indexed: 01/04/2023]
Abstract
G protein-coupled receptors (GPCRs) transmit information to the cell interior by transducing external signals to heterotrimeric G protein subunits, Gα and Gβγ subunits, localized on the inner leaflet of the plasma membrane. Though the initial focus was mainly on Gα-mediated events, Gβγ subunits were later identified as major contributors to GPCR-G protein signalling. A broad functional array of Gβγ signalling has recently been attributed to Gβ and Gγ subtype diversity, comprising 5 Gβ and 12 Gγ subtypes, respectively. In addition to displaying selectivity towards each other to form the Gβγ dimer, numerous studies have identified preferences of distinct Gβγ combinations for specific GPCRs, Gα subtypes and effector molecules. Importantly, Gβ and Gγ subtype-dependent regulation of downstream effectors, representing a diverse range of signalling pathways and physiological functions have been found. Here, we review the literature on the repercussions of Gβ and Gγ subtype diversity on direct and indirect regulation of GPCR/G protein signalling events and their physiological outcomes. Our discussion additionally provides perspective in understanding the intricacies underlying molecular regulation of subtype-specific roles of Gβγ signalling and associated diseases.
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Affiliation(s)
- Mithila Tennakoon
- Department of Chemistry and Biochemistry, The University of Toledo, Toledo, OH 43606, USA
| | - Kanishka Senarath
- Genetics and Molecular Biology Unit, University of Sri Jayewardenepura, Nugegoda, Sri Lanka
| | - Dinesh Kankanamge
- Department of Chemistry and Biochemistry, The University of Toledo, Toledo, OH 43606, USA
| | - Kasun Ratnayake
- Department of Chemistry and Biochemistry, The University of Toledo, Toledo, OH 43606, USA; Department of Pharmacology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Dhanushan Wijayaratna
- Department of Chemistry and Biochemistry, The University of Toledo, Toledo, OH 43606, USA
| | - Koshala Olupothage
- Department of Chemistry and Biochemistry, The University of Toledo, Toledo, OH 43606, USA
| | - Sithurandi Ubeysinghe
- Department of Chemistry and Biochemistry, The University of Toledo, Toledo, OH 43606, USA
| | | | - Terence E Hébert
- Department of Pharmacology and Therapeutics, McGill University, Montréal, QC H3G 1Y6, Canada.
| | - Ajith Karunarathne
- Department of Chemistry and Biochemistry, The University of Toledo, Toledo, OH 43606, USA.
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15
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Gurianov DS, Antonenko SV, Telegeev GD. Colocalization of BCR Protein with Clathrin, Actin, and Cortactin Suggests Its Possible Role in the Regulation of Actin Branching and Clathrin-Mediated Endocytosis. CYTOL GENET+ 2021. [DOI: 10.3103/s0095452721020055] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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16
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Hu J, Harris PC. Regulation of polycystin expression, maturation and trafficking. Cell Signal 2020; 72:109630. [PMID: 32275942 PMCID: PMC7269868 DOI: 10.1016/j.cellsig.2020.109630] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Revised: 04/03/2020] [Accepted: 04/04/2020] [Indexed: 12/26/2022]
Abstract
The major autosomal dominant polycystic kidney disease (ADPKD) genes, PKD1 and PKD2, are wildly expressed at the organ and tissue level. PKD1 encodes polycystin 1 (PC1), a large membrane associated receptor-like protein that can complex with the PKD2 product, PC2. Various cellular locations have been described for both PC1, including the plasma membrane and extracellular vesicles, and PC2, especially the endoplasmic reticulum (ER), but compelling evidence indicates that the primary cilium, a sensory organelle, is the key site for the polycystin complex to prevent PKD. As with other membrane proteins, the ER biogenesis pathway is key to appropriately folding, performing quality control, and exporting fully folded PC1 to the Golgi apparatus. There is a requirement for binding with PC2 and cleavage of PC1 at the GPS for this folding and export to occur. Six different monogenic defects in this pathway lead to cystic disease development, with PC1 apparently particularly sensitive to defects in this general protein processing pathway. Trafficking of membrane proteins, and the polycystins in particular, through the Golgi to the primary cilium have been analyzed in detail, but at this time, there is no clear consensus on a ciliary targeting sequence required to export proteins to the cilium. After transitioning though the trans-Golgi network, polycystin-bearing vesicles are likely sorted to early or recycling endosomes and then transported to the ciliary base, possibly via docking to transition fibers (TF). The membrane-bound polycystin complex then undergoes facilitated trafficking through the transition zone, the diffusion barrier at the base of the cilium, before entering the cilium. Intraflagellar transport (IFT) may be involved in moving the polycystins along the cilia, but data also indicates other mechanisms. The ciliary polycystin complex can be ubiquitinated and removed from cilia by internalization at the ciliary base and may be sent back to the plasma membrane for recycling or to lysosomes for degradation. Monogenic defects in processes regulating the protein composition of cilia are associated with syndromic disorders involving many organ systems, reflecting the pleotropic role of cilia during development and for tissue maintenance. Many of these ciliopathies have renal involvement, likely because of faulty polycystin signaling from cilia. Understanding the expression, maturation and trafficking of the polycystins helps understand PKD pathogenesis and suggests opportunities for therapeutic intervention.
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Affiliation(s)
- Jinghua Hu
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN, USA; Division of Nephrology and Hypertension, Mayo Clinic, Rochester, MN, USA.
| | - Peter C Harris
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN, USA; Division of Nephrology and Hypertension, Mayo Clinic, Rochester, MN, USA.
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17
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Kolczynska K, Loza-Valdes A, Hawro I, Sumara G. Diacylglycerol-evoked activation of PKC and PKD isoforms in regulation of glucose and lipid metabolism: a review. Lipids Health Dis 2020; 19:113. [PMID: 32466765 PMCID: PMC7257441 DOI: 10.1186/s12944-020-01286-8] [Citation(s) in RCA: 68] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2020] [Accepted: 05/14/2020] [Indexed: 12/15/2022] Open
Abstract
Protein kinase C (PKC) and Protein kinase D (PKD) isoforms can sense diacylglycerol (DAG) generated in the different cellular compartments in various physiological processes. DAG accumulates in multiple organs of the obese subjects, which leads to the disruption of metabolic homeostasis and the development of diabetes as well as associated diseases. Multiple studies proved that aberrant activation of PKCs and PKDs contributes to the development of metabolic diseases. DAG-sensing PKC and PKD isoforms play a crucial role in the regulation of metabolic homeostasis and therefore might serve as targets for the treatment of metabolic disorders such as obesity and diabetes.
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Affiliation(s)
- Katarzyna Kolczynska
- Nencki Institute of Experimental Biology, Polish Academy of Sciences, 3 Pasteur Street, 02-093, Warszawa, Poland
| | - Angel Loza-Valdes
- Nencki Institute of Experimental Biology, Polish Academy of Sciences, 3 Pasteur Street, 02-093, Warszawa, Poland
| | - Izabela Hawro
- Nencki Institute of Experimental Biology, Polish Academy of Sciences, 3 Pasteur Street, 02-093, Warszawa, Poland
| | - Grzegorz Sumara
- Nencki Institute of Experimental Biology, Polish Academy of Sciences, 3 Pasteur Street, 02-093, Warszawa, Poland.
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18
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Tao Y, Yang Y, Zhou R, Gong T. Golgi Apparatus: An Emerging Platform for Innate Immunity. Trends Cell Biol 2020; 30:467-477. [PMID: 32413316 DOI: 10.1016/j.tcb.2020.02.008] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Revised: 02/24/2020] [Accepted: 02/24/2020] [Indexed: 12/23/2022]
Abstract
The Golgi apparatus serves as a receiving station where proteins from the endoplasmic reticulum (ER) are further processed before being sent to other cellular compartments. In addition to its well-appreciated roles in vesicular trafficking and protein/lipid secretion, recent studies have demonstrated that the Golgi acts as a signaling platform to facilitate multiple innate immune pathways. Moreover, the membranous networks that connect the Golgi with the ER, mitochondria, endosomes, and autophagosomes provide convenient access to innate immune signal transduction and subsequent effector responses. Here, we review the emerging knowledge about the roles of the Golgi in the initiation and activation of innate immune signaling. Moreover, microbial hijacking strategies that inhibit Golgi-associated innate immune responses will also be discussed.
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Affiliation(s)
- Ye Tao
- Department of Otolaryngology-Head and Neck Surgery, the First Affiliated Hospital of Anhui Medical University, Hefei 230022, China; Hefei National Laboratory for Physical Sciences at Microscale, the CAS Key Laboratory of Innate Immunity and Chronic Disease, School of Basic Medical Science, Division of Life Science and Medicine, University of Science and Technology of China, Hefei 230027, China
| | - Yanqing Yang
- Department of Clinical Laboratory, the First Affiliated Hospital of Bengbu Medical College, Bengbu 233004, China
| | - Rongbin Zhou
- Hefei National Laboratory for Physical Sciences at Microscale, the CAS Key Laboratory of Innate Immunity and Chronic Disease, School of Basic Medical Science, Division of Life Science and Medicine, University of Science and Technology of China, Hefei 230027, China.
| | - Tao Gong
- Hefei National Laboratory for Physical Sciences at Microscale, the CAS Key Laboratory of Innate Immunity and Chronic Disease, School of Basic Medical Science, Division of Life Science and Medicine, University of Science and Technology of China, Hefei 230027, China.
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19
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Reinhardt R, Truebestein L, Schmidt HA, Leonard TA. It Takes Two to Tango: Activation of Protein Kinase D by Dimerization. Bioessays 2020; 42:e1900222. [PMID: 31997382 DOI: 10.1002/bies.201900222] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Revised: 01/10/2020] [Indexed: 12/23/2022]
Abstract
The recent discovery and structure determination of a novel ubiquitin-like dimerization domain in protein kinase D (PKD) has significant implications for its activation. PKD is a serine/threonine kinase activated by the lipid second messenger diacylglycerol (DAG). It is an essential and highly conserved protein that is implicated in plasma membrane directed trafficking processes from the trans-Golgi network. However, many open questions surround its mechanism of activation, its localization, and its role in the biogenesis of cargo transport carriers. In reviewing this field, the focus is primarily on the mechanisms that control the activation of PKD at precise locations in the cell. In light of the new structural findings, the understanding of the mechanisms underlying PKD activation is critically evaluated, with particular emphasis on the role of dimerization in PKD autophosphorylation, and the provenance and recognition of the DAG that activates PKD.
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Affiliation(s)
- Ronja Reinhardt
- Department of Structural and Computational Biology, Max Perutz Labs, Vienna Biocenter, 1030, Vienna, Austria.,Department of Medical Biochemistry, Medical University of Vienna, 1030, Vienna, Austria
| | - Linda Truebestein
- Department of Structural and Computational Biology, Max Perutz Labs, Vienna Biocenter, 1030, Vienna, Austria.,Department of Medical Biochemistry, Medical University of Vienna, 1030, Vienna, Austria
| | - Heiko A Schmidt
- Center for Integrative Bioinformatics Vienna, Max Perutz Labs, University of Vienna and Medical University of Vienna, Vienna Biocenter, 1030, Vienna, Austria
| | - Thomas A Leonard
- Department of Structural and Computational Biology, Max Perutz Labs, Vienna Biocenter, 1030, Vienna, Austria.,Department of Medical Biochemistry, Medical University of Vienna, 1030, Vienna, Austria
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20
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Dirck AT, Whyte ML, Hudson AW. HHV-7 U21 exploits Golgi quality control carriers to reroute class I MHC molecules to lysosomes. Mol Biol Cell 2019; 31:196-208. [PMID: 31851583 PMCID: PMC7001482 DOI: 10.1091/mbc.e19-07-0363] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
The human herpesvirus-7 (HHV-7) U21 glycoprotein binds to class I major histocompatibility complex (MHC) molecules in the endoplasmic reticulum (ER) and reroutes them to lysosomes. How this single viral glycoprotein efficiently redirects the U21/class I MHC complex to the lysosomal compartment is poorly understood. To investigate the trafficking of HHV-7 U21, we followed synchronous release of U21 from the ER as it traffics through the secretory system. Sorting of integral membrane proteins from the trans-Golgi network (TGN) has been shown to occur through tubular carriers that emanate from the TGN or through vesicular carriers that recruit GGA (Golgi-localized, γ-ear–containing, ARF-binding protein), clathrin adaptors, and clathrin. Here, we present evidence for the existence of a third type of Golgi-derived carrier that is vesicular, yet clathrin independent. This U21-containing carrier also carries a Golgi membrane protein engineered to form inducible oligomers. We propose that U21 employs the novel mechanism of forming oligomeric complexes with class I MHC molecules that result in sorting of the oligomeric U21/class I MHC complexes to Golgi-derived quality control carriers destined for lysosomes.
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Affiliation(s)
- Aaron T Dirck
- Department of Microbiology and Immunology, Medical College of Wisconsin, Milwaukee, WI 53226
| | - Melissa L Whyte
- Department of Microbiology and Immunology, Medical College of Wisconsin, Milwaukee, WI 53226
| | - Amy W Hudson
- Department of Microbiology and Immunology, Medical College of Wisconsin, Milwaukee, WI 53226
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21
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Elimination of fukutin reveals cellular and molecular pathomechanisms in muscular dystrophy-associated heart failure. Nat Commun 2019; 10:5754. [PMID: 31848331 PMCID: PMC6917736 DOI: 10.1038/s41467-019-13623-2] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2017] [Accepted: 11/11/2019] [Indexed: 01/06/2023] Open
Abstract
Heart failure is the major cause of death for muscular dystrophy patients, however, the molecular pathomechanism remains unknown. Here, we show the detailed molecular pathogenesis of muscular dystrophy-associated cardiomyopathy in mice lacking the fukutin gene (Fktn), the causative gene for Fukuyama muscular dystrophy. Although cardiac Fktn elimination markedly reduced α-dystroglycan glycosylation and dystrophin-glycoprotein complex proteins in sarcolemma at all developmental stages, cardiac dysfunction was observed only in later adulthood, suggesting that membrane fragility is not the sole etiology of cardiac dysfunction. During young adulthood, Fktn-deficient mice were vulnerable to pathological hypertrophic stress with downregulation of Akt and the MEF2-histone deacetylase axis. Acute Fktn elimination caused severe cardiac dysfunction and accelerated mortality with myocyte contractile dysfunction and disordered Golgi-microtubule networks, which were ameliorated with colchicine treatment. These data reveal fukutin is crucial for maintaining myocyte physiology to prevent heart failure, and thus, the results may lead to strategies for therapeutic intervention. Mutations in Ftkn cause Fukuyama muscular dystrophy, and heart failure is the main cause of death in thes patients. Here the authors show that acute elimination of Fktn in adult mice causes early mortality, and this is associated with myocyte dysfunction, with disorganised Golg-microtubule networks, and that the pathology can be ameliorated with colchicine treatment.
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22
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Elsner DJ, Siess KM, Gossenreiter T, Hartl M, Leonard TA. A ubiquitin-like domain controls protein kinase D dimerization and activation by trans-autophosphorylation. J Biol Chem 2019; 294:14422-14441. [PMID: 31406020 PMCID: PMC6768651 DOI: 10.1074/jbc.ra119.008713] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Revised: 07/30/2019] [Indexed: 11/25/2022] Open
Abstract
Protein kinase D (PKD) is an essential Ser/Thr kinase in animals and controls a variety of diverse cellular functions, including vesicle trafficking and mitogenesis. PKD is activated by recruitment to membranes containing the lipid second messenger diacylglycerol (DAG) and subsequent phosphorylation of its activation loop. Here, we report the crystal structure of the PKD N terminus at 2.2 Å resolution containing a previously unannotated ubiquitin-like domain (ULD), which serves as a dimerization domain. A single point mutation in the dimerization interface of the ULD not only abrogated dimerization in cells but also prevented PKD activation loop phosphorylation upon DAG production. We further show that the kinase domain of PKD dimerizes in a concentration-dependent manner and autophosphorylates on a single residue in its activation loop. We also provide evidence that PKD is expressed at concentrations 2 orders of magnitude below the ULD dissociation constant in mammalian cells. We therefore propose a new model for PKD activation in which the production of DAG leads to the local accumulation of PKD at the membrane, which drives ULD-mediated dimerization and subsequent trans-autophosphorylation of the kinase domain.
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Affiliation(s)
- Daniel J Elsner
- Department of Structural and Computational Biology, Max Perutz Labs, Campus Vienna Biocenter 5, 1030 Vienna, Austria.,Department of Medical Biochemistry, Medical University of Vienna, 1090 Vienna, Austria
| | - Katharina M Siess
- Department of Structural and Computational Biology, Max Perutz Labs, Campus Vienna Biocenter 5, 1030 Vienna, Austria.,Department of Medical Biochemistry, Medical University of Vienna, 1090 Vienna, Austria
| | - Thomas Gossenreiter
- Mass Spectrometry Facility, Max Perutz Labs, Dr. Bohr-Gasse 3, 1030 Vienna, Austria
| | - Markus Hartl
- Mass Spectrometry Facility, Max Perutz Labs, Dr. Bohr-Gasse 3, 1030 Vienna, Austria.,Department of Biochemistry and Cell Biology, Max Perutz Labs, University of Vienna, Vienna Biocenter, Dr. Bohr-Gasse 9, 1030 Vienna, Austria
| | - Thomas A Leonard
- Department of Structural and Computational Biology, Max Perutz Labs, Campus Vienna Biocenter 5, 1030 Vienna, Austria .,Department of Medical Biochemistry, Medical University of Vienna, 1090 Vienna, Austria
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23
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Yang X, Liao CY, Tang J, Bassham DC. Overexpression of trans-Golgi network t-SNAREs rescues vacuolar trafficking and TGN morphology defects in a putative tethering factor mutant. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2019; 99:703-716. [PMID: 31009161 DOI: 10.1111/tpj.14353] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2017] [Revised: 03/25/2019] [Accepted: 04/17/2019] [Indexed: 06/09/2023]
Abstract
The trans-Golgi network (TGN) is a major site for sorting of cargo to either the vacuole or apoplast. The TGN-localized coiled-coil protein TNO1 is a putative tethering factor that interacts with the TGN t-SNARE SYP41 and is required for correct localization of the SYP61 t-SNARE. An Arabidopsis thaliana tno1 mutant is hypersensitive to salt stress and partially mislocalizes vacuolar proteins to the apoplast, indicating a role in vacuolar trafficking. Here, we show that overexpression of SYP41 or SYP61 significantly increases SYP41-SYP61 complex formation in a tno1 mutant, and rescues the salt sensitivity and defective vacuolar trafficking of the tno1 mutant. The TGN is disrupted and vesicle budding from Golgi cisternae is reduced in the tno1 mutant, and these defects are also rescued by overexpression of SYP41 or SYP61. Our results suggest that the trafficking and Golgi morphology defects caused by loss of TNO1 can be rescued by increasing SYP41-SYP61 t-SNARE complex formation, implicating TNO1 as a tethering factor mediating efficient vesicle fusion at the TGN.
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Affiliation(s)
- Xiaochen Yang
- Department of Genetics, Development and Cell Biology, Iowa State University, Ames, IA, 50011, USA
| | - Ching-Yi Liao
- Department of Genetics, Development and Cell Biology, Iowa State University, Ames, IA, 50011, USA
| | - Jie Tang
- Department of Genetics, Development and Cell Biology, Iowa State University, Ames, IA, 50011, USA
| | - Diane C Bassham
- Department of Genetics, Development and Cell Biology, Iowa State University, Ames, IA, 50011, USA
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24
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von Blume J, Hausser A. Lipid-dependent coupling of secretory cargo sorting and trafficking at the trans-Golgi network. FEBS Lett 2019; 593:2412-2427. [PMID: 31344259 PMCID: PMC8048779 DOI: 10.1002/1873-3468.13552] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2019] [Revised: 07/10/2019] [Accepted: 07/22/2019] [Indexed: 12/17/2022]
Abstract
In eukaryotic cells, the trans-Golgi network (TGN) serves as a platform for secretory cargo sorting and trafficking. In recent years, it has become evident that a complex network of lipid–lipid and lipid–protein interactions contributes to these key functions. This review addresses the role of lipids at the TGN with a particular emphasis on sphingolipids and diacylglycerol. We further highlight how these lipids couple secretory cargo sorting and trafficking for spatiotemporal coordination of protein transport to the plasma membrane.
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Affiliation(s)
- Julia von Blume
- Department of Cell Biology, Yale School of Medicine, New Haven, CT, USA.,Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Angelika Hausser
- Institute of Cell Biology and Immunology, University of Stuttgart, Germany.,Stuttgart Research Center Systems Biology, University of Stuttgart, Germany
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25
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Kumagai K, Hanada K. Structure, functions and regulation of CERT, a lipid-transfer protein for the delivery of ceramide at the ER-Golgi membrane contact sites. FEBS Lett 2019; 593:2366-2377. [PMID: 31254361 DOI: 10.1002/1873-3468.13511] [Citation(s) in RCA: 53] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2019] [Revised: 06/26/2019] [Accepted: 06/26/2019] [Indexed: 12/17/2022]
Abstract
The inter-organelle transport of lipids must be regulated to ensure appropriate lipid composition of each organelle. In mammalian cells, ceramide synthesised in the endoplasmic reticulum (ER) is transported to the trans-Golgi regions, where ceramide is converted to sphingomyelin (SM) with the concomitant production of diacylglycerol. Ceramide transport protein (CERT) transports ceramide from the ER to the trans-Golgi regions at the ER-Golgi membrane contact sites (MCS). The function of CERT is down-regulated by multisite phosphorylation of a serine-repeat motif (SRM) and up-regulated by phosphorylation of serine 315 in CERT. Multisite phosphorylation of the SRM is primed by protein kinase D, which is activated by diacylglycerol. The function of CERT is regulated by a phosphorylation-dependent feedback mechanism in response to cellular requirements of SM. CERT-dependent ceramide transport is also affected by the pool of phosphatidylinositol (PtdIns)-4-phosphate (PtdIns(4)P) in the trans-Golgi regions, while the PtdIns(4)P pool is regulated by PtdIns-4-kinases and oxysterol-binding protein. The ER-Golgi MCS may serve as inter-organelle communication zones, in which many factors work in concert to serve as an extensive rheostat of SM, diacylglycerol, cholesterol and PtdIns(4)P.
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Affiliation(s)
- Keigo Kumagai
- Department of Biochemistry and Cell Biology, National Institute of Infectious Diseases, Tokyo, Japan
| | - Kentaro Hanada
- Department of Biochemistry and Cell Biology, National Institute of Infectious Diseases, Tokyo, Japan
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26
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Cellular Protein Kinase D Modulators Play a Role during Multiple Steps of Herpes Simplex Virus 1 Egress. J Virol 2018; 92:JVI.01486-18. [PMID: 30232182 DOI: 10.1128/jvi.01486-18] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2018] [Accepted: 09/14/2018] [Indexed: 12/12/2022] Open
Abstract
The assembly of new herpes simplex virus 1 (HSV-1) particles takes place in the nucleus. These particles then travel across the two nuclear membranes and acquire a final envelope from a cellular compartment. The contribution of the cell to the release of the virus is, however, little known. We previously demonstrated, using a synchronized infection, that the host protein kinase D and diacylglycerol, a lipid that recruits the kinase to the trans-Golgi network (TGN), promote the release of the virus from that compartment. Given the role this cellular protein plays in the herpes simplex virus 1 life cycle and the many molecules that modulate its activity, we aimed to determine to what extent this virus utilizes the protein kinase D pathway during a nonsynchronized infection. Several molecular protein kinase D (PKD) regulators were targeted by RNA interference and viral production monitored. Surprisingly, many of these modulators negatively impacted the extracellular release of the virus. Overexpression studies, the use of pharmacological reagents, and assays to monitor intracellular lipids implicated in the biology of PKD suggested that these effects were oddly independent of total intracellular diacylglycerol levels. Instead, mapping of the viral intermediates by electron microscopy suggested that some of these modulators could regulate distinct steps along the viral egress pathway, notably nuclear egress. Altogether, this suggests a more complex contribution of PKD to HSV-1 egress than originally anticipated and new research avenues to explore.IMPORTANCE Viruses are obligatory parasites that highjack numerous cellular functions. This is certainly true when it comes to transporting viral particles within the cell. Herpesviruses share the unique property of traveling through the two nuclear membranes by subsequent budding and fusion and acquiring their final envelope from a cellular organelle. Albeit disputed, the overall evidence from many laboratories points to the trans-Golgi network (TGN) as the source of that membrane. Moreover, past findings revealed that the host protein kinase D (PKD) plays an important role at that stage, which is significant given the known implication of that protein in vesicular transport. The present findings suggest that the PKD machinery not only affects the late stages of herpes simplex virus I egress but also modulates earlier steps, such as nuclear egress. This opens up new means to control these viruses.
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27
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Eisler SA, Curado F, Link G, Schulz S, Noack M, Steinke M, Olayioye MA, Hausser A. A Rho signaling network links microtubules to PKD controlled carrier transport to focal adhesions. eLife 2018; 7:35907. [PMID: 30028295 PMCID: PMC6070338 DOI: 10.7554/elife.35907] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2018] [Accepted: 07/19/2018] [Indexed: 12/22/2022] Open
Abstract
Protein kinase D (PKD) is a family of serine/threonine kinases that is required for the structural integrity and function of the Golgi complex. Despite its importance in the regulation of Golgi function, the molecular mechanisms regulating PKD activity are still incompletely understood. Using the genetically encoded PKD activity reporter G-PKDrep we now uncover a Rho signaling network comprising GEF-H1, the RhoGAP DLC3, and the Rho effector PLCε that regulate the activation of PKD at trans-Golgi membranes. We further show that this molecular network coordinates the formation of TGN-derived Rab6-positive transport carriers delivering cargo for localized exocytosis at focal adhesions.
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Affiliation(s)
- Stephan A Eisler
- Stuttgart Research Center Systems Biology, University of Stuttgart, Stuttgart, Germany
| | - Filipa Curado
- Institute of Cell Biology and Immunology, University of Stuttgart, Stuttgart, Germany
| | - Gisela Link
- Institute of Cell Biology and Immunology, University of Stuttgart, Stuttgart, Germany
| | - Sarah Schulz
- Institute of Cell Biology and Immunology, University of Stuttgart, Stuttgart, Germany
| | - Melanie Noack
- Stuttgart Research Center Systems Biology, University of Stuttgart, Stuttgart, Germany
| | - Maren Steinke
- Institute of Cell Biology and Immunology, University of Stuttgart, Stuttgart, Germany
| | - Monilola A Olayioye
- Stuttgart Research Center Systems Biology, University of Stuttgart, Stuttgart, Germany.,Institute of Cell Biology and Immunology, University of Stuttgart, Stuttgart, Germany
| | - Angelika Hausser
- Stuttgart Research Center Systems Biology, University of Stuttgart, Stuttgart, Germany.,Institute of Cell Biology and Immunology, University of Stuttgart, Stuttgart, Germany
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28
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Secretory Vesicle Polar Sorting, Endosome Recycling and Cytoskeleton Organization Require the AP-1 Complex in Aspergillus nidulans. Genetics 2018; 209:1121-1138. [PMID: 29925567 DOI: 10.1534/genetics.118.301240] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2018] [Accepted: 06/19/2018] [Indexed: 11/18/2022] Open
Abstract
The AP-1 complex is essential for membrane protein traffic via its role in the pinching-off and sorting of secretory vesicles (SVs) from the trans-Golgi and/or endosomes. While its essentiality is undisputed in metazoa, its role in simpler eukaryotes seems less clear. Here, we dissect the role of AP-1 in the filamentous fungus Aspergillus nidulans and show that it is absolutely essential for growth due to its role in clathrin-dependent maintenance of polar traffic of specific membrane cargoes toward the apex of growing hyphae. We provide evidence that AP-1 is involved in both anterograde sorting of RabERab11-labeled SVs and RabA/BRab5-dependent endosome recycling. Additionally, AP-1 is shown to be critical for microtubule and septin organization, further rationalizing its essentiality in cells that face the challenge of cytoskeleton-dependent polarized cargo traffic. This work also opens a novel issue on how nonpolar cargoes, such as transporters, are sorted to the eukaryotic plasma membrane.
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29
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A Golgi Lipid Signaling Pathway Controls Apical Golgi Distribution and Cell Polarity during Neurogenesis. Dev Cell 2018; 44:725-740.e4. [PMID: 29587143 DOI: 10.1016/j.devcel.2018.02.025] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Revised: 01/03/2018] [Accepted: 02/26/2018] [Indexed: 11/22/2022]
Abstract
Phosphatidylinositol (PtdIns) transfer proteins (PITPs) stimulate PtdIns-4-P synthesis and signaling in eukaryotic cells, but to what biological outcomes such signaling circuits are coupled remains unclear. Herein, we show that two highly related StART-like PITPs, PITPNA and PITPNB, act in a redundant fashion to support development of the embryonic mammalian neocortex. PITPNA/PITPNB do so by driving PtdIns-4-P-dependent recruitment of GOLPH3, and likely ceramide transfer protein (CERT), to Golgi membranes with GOLPH3 recruitment serving to promote MYO18A- and F-actin-directed loading of the Golgi network to apical processes of neural stem cells (NSCs). We propose the primary role for PITP/PtdIns-4-P/GOLPH3/CERT signaling in NSC Golgi is not in regulating bulk membrane trafficking but in optimizing apically directed membrane trafficking and/or apical membrane signaling during neurogenesis.
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30
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Raza S, Alvisi G, Shahin F, Husain U, Rabbani M, Yaqub T, Anjum AA, Sheikh AA, Nawaz M, Ali MA. Role of Rab GTPases in HSV-1 infection: Molecular understanding of viral maturation and egress. Microb Pathog 2018; 118:146-153. [PMID: 29551438 DOI: 10.1016/j.micpath.2018.03.028] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2017] [Revised: 03/14/2018] [Accepted: 03/15/2018] [Indexed: 12/17/2022]
Abstract
Most enveloped viruses exploit complex cellular pathways for assembly and egress from the host cell, and the large DNA virus Herpes simplex virus 1 (HSV-1) makes no exception, hijacking several cellular transport pathways for its glycoprotein trafficking and maturation, as well as for viral morphogenesis and egress according to the envelopment, de-envelopment and re-envelopment model. Importantly Rab GTPases, widely distributed master regulators of intracellular membrane trafficking pathways, have recently being tightly implicated in such process. Indeed, siRNA-mediated genetic ablation of specific Rab proteins differently affected HSV-1 production, suggesting a complex role of different Rab proteins in HSV-1 life cycle. In this review, we discuss how different Rabs can regulate HSV-1 assembly/egress and the potential therapeutic applications of such findings for the management of HSV-1 infections.
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Affiliation(s)
- Sohail Raza
- Department of Microbiology, University of Veterinary and Animal Sciences Lahore 54000, Pakistan.
| | - Gualtiero Alvisi
- Department of Molecular Medicine, University of Padua, 35121, Italy
| | - Farzana Shahin
- The State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, China; College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, China
| | - Urooj Husain
- Postgraduate Medical Institute Lahore 54000, Pakistan
| | - Masood Rabbani
- Department of Microbiology, University of Veterinary and Animal Sciences Lahore 54000, Pakistan
| | - Tahir Yaqub
- Department of Microbiology, University of Veterinary and Animal Sciences Lahore 54000, Pakistan
| | - Aftab Ahmad Anjum
- Department of Microbiology, University of Veterinary and Animal Sciences Lahore 54000, Pakistan
| | - Ali Ahmad Sheikh
- Department of Microbiology, University of Veterinary and Animal Sciences Lahore 54000, Pakistan
| | - Muhammad Nawaz
- Department of Microbiology, University of Veterinary and Animal Sciences Lahore 54000, Pakistan
| | - Muhammad Asad Ali
- Department of Microbiology, University of Veterinary and Animal Sciences Lahore 54000, Pakistan
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A Lipid Transfer Protein Signaling Axis Exerts Dual Control of Cell-Cycle and Membrane Trafficking Systems. Dev Cell 2018; 44:378-391.e5. [PMID: 29396115 DOI: 10.1016/j.devcel.2017.12.026] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2016] [Revised: 09/24/2017] [Accepted: 12/28/2017] [Indexed: 11/21/2022]
Abstract
Kes1/Osh4 is a member of the conserved, but functionally enigmatic, oxysterol binding protein-related protein (ORP) superfamily that inhibits phosphatidylinositol transfer protein (Sec14)-dependent membrane trafficking through the trans-Golgi (TGN)/endosomal network. We now report that Kes1, and select other ORPs, execute cell-cycle control activities as functionally non-redundant inhibitors of the G1/S transition when cells confront nutrient-poor environments and promote replicative aging. Kes1-dependent cell-cycle regulation requires the Greatwall/MASTL kinase ortholog Rim15, and is opposed by Sec14 activity in a mechanism independent of Kes1/Sec14 bulk membrane-trafficking functions. Moreover, the data identify Kes1 as a non-histone target for NuA4 through which this lysine acetyltransferase co-modulates membrane-trafficking and cell-cycle activities. We propose the Sec14/Kes1 lipid-exchange protein pair constitutes part of the mechanism for integrating TGN/endosomal lipid signaling with cell-cycle progression and hypothesize that ORPs define a family of stage-specific cell-cycle control factors that execute tumor-suppressor-like functions.
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Downregulation of a GPCR by β-Arrestin2-Mediated Switch from an Endosomal to a TGN Recycling Pathway. Cell Rep 2017; 17:2966-2978. [PMID: 27974210 DOI: 10.1016/j.celrep.2016.11.050] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2016] [Revised: 08/17/2016] [Accepted: 11/14/2016] [Indexed: 01/14/2023] Open
Abstract
Glucose-dependent insulinotropic polypeptide (GIP) is an incretin hormone involved in nutrient homeostasis. GIP receptor (GIPR) is constitutively internalized and returned to the plasma membrane, atypical behavior for a G-protein-coupled receptor (GPCR). GIP promotes GIPR downregulation from the plasma membrane by inhibiting recycling without affecting internalization. This transient desensitization is achieved by altered intracellular trafficking of activated GIPR. GIP stimulation induces a switch in GIPR recycling from a rapid endosomal to a slow trans-Golgi network (TGN) pathway. GPCR kinases and β-arrestin2 are required for this switch in recycling. A coding sequence variant of GIPR, which has been associated with metabolic alterations, has altered post-activation trafficking characterized by enhanced downregulation and prolonged desensitization. Downregulation of the variant requires β-arrestin2 targeting to the TGN but is independent of GPCR kinases. The single amino acid substitution in the variant biases the receptor to promote GIP-stimulated β-arrestin2 recruitment without receptor phosphorylation, thereby enhancing downregulation.
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Anton C, Zanolari B, Arcones I, Wang C, Mulet JM, Spang A, Roncero C. Involvement of the exomer complex in the polarized transport of Ena1 required for Saccharomyces cerevisiae survival against toxic cations. Mol Biol Cell 2017; 28:3672-3685. [PMID: 29021337 PMCID: PMC5706994 DOI: 10.1091/mbc.e17-09-0549] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2017] [Revised: 10/04/2017] [Accepted: 10/06/2017] [Indexed: 11/29/2022] Open
Abstract
Here we show that the TGN complex named exomer is required for alkali cation tolerance in yeast because of its roles in the sorting and polarization of the plasma membrane Na+-ATPase Ena1 and on the signal processing through the RIM101 pathway, thus widening the functional repertoire of the yeast exomer. Exomer is an adaptor complex required for the direct transport of a selected number of cargoes from the trans-Golgi network (TGN) to the plasma membrane in Saccharomyces cerevisiae. However, exomer mutants are highly sensitive to increased concentrations of alkali metal cations, a situation that remains unexplained by the lack of transport of any known cargoes. Here we identify several HAL genes that act as multicopy suppressors of this sensitivity and are connected to the reduced function of the sodium ATPase Ena1. Furthermore, we find that Ena1 is dependent on exomer function. Even though Ena1 can reach the plasma membrane independently of exomer, polarized delivery of Ena1 to the bud requires functional exomer. Moreover, exomer is required for full induction of Ena1 expression after cationic stress by facilitating the plasma membrane recruitment of the molecular machinery involved in Rim101 processing and activation of the RIM101 pathway in response to stress. Both the defective localization and the reduced levels of Ena1 contribute to the sensitivity of exomer mutants to alkali metal cations. Our work thus expands the spectrum of exomer-dependent proteins and provides a link to a more general role of exomer in TGN organization.
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Affiliation(s)
- Carlos Anton
- Instituto de Biología Funcional y Genómica (IBFG) and Departamento de Microbiología y Genética, CSIC-Universidad de Salamanca, 37007 Salamanca, Spain
| | - Bettina Zanolari
- Biozentrum, Growth & Development, University of Basel, CH-4056 Basel, Switzerland
| | - Irene Arcones
- Instituto de Biología Funcional y Genómica (IBFG) and Departamento de Microbiología y Genética, CSIC-Universidad de Salamanca, 37007 Salamanca, Spain
| | - Congwei Wang
- Biozentrum, Growth & Development, University of Basel, CH-4056 Basel, Switzerland
| | - Jose Miguel Mulet
- Instituto de Biología Molecular y Celular de Plantas, CSIC-Universitat Politécnica de Valencia, 46011 Valencia, Spain
| | - Anne Spang
- Biozentrum, Growth & Development, University of Basel, CH-4056 Basel, Switzerland
| | - Cesar Roncero
- Instituto de Biología Funcional y Genómica (IBFG) and Departamento de Microbiología y Genética, CSIC-Universidad de Salamanca, 37007 Salamanca, Spain
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Campelo F, van Galen J, Turacchio G, Parashuraman S, Kozlov MM, García-Parajo MF, Malhotra V. Sphingomyelin metabolism controls the shape and function of the Golgi cisternae. eLife 2017; 6. [PMID: 28500756 PMCID: PMC5462544 DOI: 10.7554/elife.24603] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2016] [Accepted: 05/04/2017] [Indexed: 12/11/2022] Open
Abstract
The flat Golgi cisterna is a highly conserved feature of eukaryotic cells, but how is this morphology achieved and is it related to its function in cargo sorting and export? A physical model of cisterna morphology led us to propose that sphingomyelin (SM) metabolism at the trans-Golgi membranes in mammalian cells essentially controls the structural features of a Golgi cisterna by regulating its association to curvature-generating proteins. An experimental test of this hypothesis revealed that affecting SM homeostasis converted flat cisternae into highly curled membranes with a concomitant dissociation of membrane curvature-generating proteins. These data lend support to our hypothesis that SM metabolism controls the structural organization of a Golgi cisterna. Together with our previously presented role of SM in controlling the location of proteins involved in glycosylation and vesicle formation, our data reveal the significance of SM metabolism in the structural organization and function of Golgi cisternae. DOI:http://dx.doi.org/10.7554/eLife.24603.001 The Golgi complex is a hub inside cells that transports many proteins to various parts of the cell. It also receives freshly made proteins and modifies them to help them mature into their final active forms. The complex is made up of a stack of disc-like membrane structures called cisternae. Are the shapes of the cisternae important for the Golgi complex to work properly? Membranes are made of mixtures of molecules known as lipids and proteins. Previous experiments show that when the mixture of lipids in the Golgi membranes changes in a specific manner, the cisternae curl into an onion-like shape and the Golgi cannot process or send out proteins anymore. Campelo et al. used mathematics and experimental approaches to investigate what causes the Golgi to change shape when the lipid mixture of the cisternae changes. A mathematical description of the shape of the Golgi predicted that some proteins keep the cisternae flat by holding the membrane rim that connects the two faces of a cisterna. To test this prediction, Campelo et al. performed experiments in human cells, which showed that when the mixture of lipids in the Golgi membranes changes, certain proteins jump from the rim, causing the cisternae to curl. These same proteins are also needed to transport cargo proteins out of the Golgi, meaning that there is a connection between the shape of the Golgi and the tasks it carries out. The shape of the Golgi complex is altered in Alzheimer’s disease and many other neurodegenerative diseases. The next challenges are to understand how these shape changes happen, how this affects cells, and if it could be possible to develop drugs that prevent these changes from occurring in patients. DOI:http://dx.doi.org/10.7554/eLife.24603.002
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Affiliation(s)
- Felix Campelo
- ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, Barcelona, Spain
| | - Josse van Galen
- Centre for Genomic Regulation, The Barcelona Institute of Science and Technology, Barcelona, Spain.,Universitat Pompeu Fabra, Barcelona, Spain
| | - Gabriele Turacchio
- Institute of Protein Biochemistry, National Research Council of Italy, Naples, Italy
| | | | - Michael M Kozlov
- Department of Physiology and Pharmacology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - María F García-Parajo
- ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, Barcelona, Spain.,Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona, Spain
| | - Vivek Malhotra
- Centre for Genomic Regulation, The Barcelona Institute of Science and Technology, Barcelona, Spain.,Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona, Spain.,Universitat Pompeu Fabra, Barcelona, Spain
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Cuenda A, Sanz-Ezquerro JJ. p38γ and p38δ: From Spectators to Key Physiological Players. Trends Biochem Sci 2017; 42:431-442. [PMID: 28473179 DOI: 10.1016/j.tibs.2017.02.008] [Citation(s) in RCA: 63] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Revised: 02/14/2017] [Accepted: 02/22/2017] [Indexed: 12/20/2022]
Abstract
Although the physiological roles of p38γ and p38δ signalling pathways are largely unknown, new genetic and pharmacological tools are providing groundbreaking information on the function of these two stress-activated protein kinases. Recent studies show the importance of p38γ and p38δ in the regulation of processes as diverse as cytokine production, protein synthesis, exocytosis, cell migration, gene expression, and neuron activity, which have an acute impact on the development of pathologies related to inflammation, diabetes, neurodegeneration, and cancer. These recent breakthroughs are resolving some of the questions that have long been asked regarding the function of p38γ and p38δ in biology and pathology.
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Affiliation(s)
- Ana Cuenda
- Department of Immunology and Oncology, Centro Nacional de Biotecnología/CSIC, Campus de Cantoblanco, 28049 Madrid, Spain.
| | - Juan José Sanz-Ezquerro
- Department of Molecular and Cellular Biology, Centro Nacional de Biotecnología/CSIC, Campus de Cantoblanco, 28049 Madrid, Spain
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36
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Lipid transfer proteins and the tuning of compartmental identity in the Golgi apparatus. Chem Phys Lipids 2016; 200:42-61. [DOI: 10.1016/j.chemphyslip.2016.06.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2016] [Revised: 06/21/2016] [Accepted: 06/22/2016] [Indexed: 11/23/2022]
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37
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Mani S, Thattai M. Stacking the odds for Golgi cisternal maturation. eLife 2016; 5. [PMID: 27542195 PMCID: PMC5012865 DOI: 10.7554/elife.16231] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2016] [Accepted: 08/18/2016] [Indexed: 12/28/2022] Open
Abstract
What is the minimal set of cell-biological ingredients needed to generate a Golgi apparatus? The compositions of eukaryotic organelles arise through a process of molecular exchange via vesicle traffic. Here we statistically sample tens of thousands of homeostatic vesicle traffic networks generated by realistic molecular rules governing vesicle budding and fusion. Remarkably, the plurality of these networks contain chains of compartments that undergo creation, compositional maturation, and dissipation, coupled by molecular recycling along retrograde vesicles. This motif precisely matches the cisternal maturation model of the Golgi, which was developed to explain many observed aspects of the eukaryotic secretory pathway. In our analysis cisternal maturation is a robust consequence of vesicle traffic homeostasis, independent of the underlying details of molecular interactions or spatial stacking. This architecture may have been exapted rather than selected for its role in the secretion of large cargo. DOI:http://dx.doi.org/10.7554/eLife.16231.001
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Affiliation(s)
- Somya Mani
- Simons Centre for the Study of Living Machines, National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore, India
| | - Mukund Thattai
- Simons Centre for the Study of Living Machines, National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore, India
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38
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Abstract
During apoptosis or activation, cells can release a subcellular structure, called a membrane microvesicle (also known as microparticle) into the extracellular environment. Microvesicles bud-off as a portion of cell membrane with its associated proteins and lipids surrounding a cytosolic core that contains intracellular proteins, lipids, and nucleic acids (DNA, RNA, siRNA, microRNA, lncRNA). Biologically active molecules on the microvesicle surface and encapsulated within can act on recipient cells as a novel mode of intercellular communication. Apoptosis has long been known to be involved in the development of diseases of autoimmunity. Abnormally persistent microvesicles, particularly apoptotic microvesicles, can accelerate autoimmune responses locally in specific organs and tissues as well as systemically. In this review, we focus on studies implicating microvesicles in the pathogenesis of autoimmune diseases and their complications.
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39
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Gadila SKG, Kim K. Cargo trafficking from the trans-Golgi network towards the endosome. Biol Cell 2016; 108:205-18. [DOI: 10.1111/boc.201600001] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2016] [Revised: 03/30/2016] [Accepted: 03/31/2016] [Indexed: 11/28/2022]
Affiliation(s)
| | - Kyoungtae Kim
- Department of Biology; Missouri State University; Springfield MO 65807 USA
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40
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Henmi Y, Morikawa Y, Oe N, Ikeda N, Fujita A, Takei K, Minogue S, Tanabe K. PtdIns4KIIα generates endosomal PtdIns(4)P and is required for receptor sorting at early endosomes. Mol Biol Cell 2016; 27:990-1001. [PMID: 26823017 PMCID: PMC4791142 DOI: 10.1091/mbc.e15-08-0564] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2015] [Accepted: 01/19/2016] [Indexed: 12/30/2022] Open
Abstract
PtdIns4KIIα has been implicated in the regulation of endosomal traffic, but the role of its enzymatic activity and the site of its action have not been elucidated. Depletion of PtdIns4KIIα significantly reduced the amount of vesicular PtdIns(4)P on early endosomes, leaving cells with an impaired ability to sort molecules from early endosomes. Phosphatidylinositol 4-kinase IIα (PtdIns4KIIα) localizes to the trans-Golgi network and endosomal compartments and has been implicated in the regulation of endosomal traffic, but the roles of both its enzymatic activity and the site of its action have not been elucidated. This study shows that PtdIns4KIIα is required for production of endosomal phosphatidylinositol 4-phosphate (PtdIns(4)P) on early endosomes and for the sorting of transferrin and epidermal growth factor receptor into recycling and degradative pathways. Depletion of PtdIns4KIIα with small interfering RNA significantly reduced the amount of vesicular PtdIns(4)P on early endosomes but not on Golgi membranes. Cells depleted of PtdIns4KIIα had an impaired ability to sort molecules destined for recycling from early endosomes. We further identify the Eps15 homology domain–containing protein 3 (EHD3) as a possible endosomal effector of PtdIns4KIIα. Tubular endosomes containing EHD3 were shortened and became more vesicular in PtdIns4KIIα-depleted cells. Endosomal PtdIns(4,5)P2 was also significantly reduced in PtdIns4KIIα-depleted cells. These results show that PtdIns4KIIα regulates receptor sorting at early endosomes through a PtdIns(4)P-dependent pathway and contributes substrate for the synthesis of endosomal PtdIns(4,5)P2.
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Affiliation(s)
- Yuji Henmi
- Medical Research Institute, Tokyo Women's Medical University, Tokyo 162-8666, Japan Department of Neuroscience, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama 700-8558, Japan
| | - Yoshiaki Morikawa
- Department of Neuroscience, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama 700-8558, Japan
| | - Natsuko Oe
- Medical Research Institute, Tokyo Women's Medical University, Tokyo 162-8666, Japan Department of Neuroscience, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama 700-8558, Japan
| | - Narumi Ikeda
- Department of Neuroscience, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama 700-8558, Japan
| | - Akikazu Fujita
- Field of Veterinary Pathobiology, Joint Faculty of Veterinary Medicine, Kagoshima University, Kagoshima 890-0065, Japan
| | - Kohji Takei
- Department of Neuroscience, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama 700-8558, Japan
| | - Shane Minogue
- Lipid and Membrane Biology Group, UCL Institute for Liver and Digestive Health, Division of Medicine, University College London, London NW3 2PF, United Kingdom
| | - Kenji Tanabe
- Medical Research Institute, Tokyo Women's Medical University, Tokyo 162-8666, Japan Department of Neuroscience, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama 700-8558, Japan
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Huranova M, Muruganandam G, Weiss M, Spang A. Dynamic assembly of the exomer secretory vesicle cargo adaptor subunits. EMBO Rep 2016; 17:202-19. [PMID: 26742961 DOI: 10.15252/embr.201540795] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2015] [Accepted: 11/27/2015] [Indexed: 12/30/2022] Open
Abstract
The trans-Golgi network (TGN) is the main secretory pathway sorting station, where cargoes are packed into appropriate transport vesicles targeted to specific destinations. Exomer is a cargo adaptor necessary for direct transport of a subset of cargoes from the TGN to the plasma membrane in yeast. Here, we show that unlike classical adaptor complexes, exomer is not recruited en bloc to the TGN, but rather assembles through a stepwise pathway, in which first the scaffold protein Chs5 and then the cargo-binding units, the ChAPs, are recruited. Although all ChAPs are able to assemble functional exomer complexes, they do so with different efficiencies. The mutual relationship between ChAPs varies from cooperation to competition depending on their expression levels and affinities to Chs5 allowing an optimized and efficient cargo transport. The multifactorial assembly pathway results in an exquisitely fine-tuned adaptor complex, enabling the cell to quickly respond and adapt to changes such as stress.
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Affiliation(s)
- Martina Huranova
- Growth & Development, Biozentrum, University of Basel, Basel, Switzerland
| | | | - Matthias Weiss
- Experimental Physics I, University of Bayreuth, Bayreuth, Germany
| | - Anne Spang
- Growth & Development, Biozentrum, University of Basel, Basel, Switzerland
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42
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Abstract
Secretion is the cellular process present in every organism that delivers soluble proteins and cargoes to the extracellular space. In eukaryotes, conventional protein secretion (CPS) is the trafficking route that secretory proteins undertake when are transported from the endoplasmic reticulum (ER) to the Golgi apparatus (GA), and subsequently to the plasma membrane (PM) via secretory vesicles or secretory granules. This book chapter recalls the fundamental steps in cell biology research contributing to the elucidation of CPS; it describes the most prominent examples of conventionally secreted proteins in eukaryotic cells and the molecular mechanisms necessary to regulate each step of this process.
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Hewavitharana T, Wedegaertner PB. PAQR3 regulates Golgi vesicle fission and transport via the Gβγ-PKD signaling pathway. Cell Signal 2015; 27:2444-51. [PMID: 26327583 PMCID: PMC4684484 DOI: 10.1016/j.cellsig.2015.08.017] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2015] [Revised: 08/21/2015] [Accepted: 08/26/2015] [Indexed: 01/06/2023]
Abstract
Heterotrimeric G proteins function at diverse subcellular locations, in addition to canonical signaling at the plasma membrane (PM). Gβγ signals at the Golgi, via protein kinase D (PKD), to regulate fission of PM-destined vesicles. However, the mechanism by which Gβγ is regulated at the Golgi in this process remains elusive. Recent studies have revealed that PAQR3 (Progestin and AdipoQ Receptor 3), also called RKTG (Raf Kinase Trapping to the Golgi), interacts with the Gβ subunit and localizes Gβ to the Golgi thereby inhibiting Gβγ signaling at the PM. Herein we show that, in contrast to this inhibition of canonical Gβγ signaling at the PM, PAQR3 promotes Gβγ signaling at the Golgi. Expression of PAQR3 causes fragmentation of the Golgi, while a Gβ binding-deficient mutant of PAQR3 does not cause Golgi fragmentation. Also, a C-terminal fragment of GRK2 (GRK2ct), which interacts with Gβγ and inhibits Gβγ signaling, and gallein, a small molecule inhibitor of Gβγ, are both able to inhibit PAQR3-mediated Golgi fragmentation. Furthermore, a dominant negative form of PKD (PKD-DN) and a pharmacological inhibitor of PKD, Gö6976, also inhibit PAQR3-mediated fragmentation of the Golgi. Importantly, expression of the Gβ binding-deficient mutant of PAQR3 inhibits the constitutive transport of the model cargo protein VSV-G from the Golgi to the PM, indicating the involvement of PAQR3 in Golgi-to PM vesicle transport and a dominant negative role for this mutant. Collectively, these results reveal a novel role for the newly characterized, Golgi-localized PAQR3 in regulating Gβγ at the non-canonical subcellular location of the Golgi and thus for controlling Golgi-to-PM protein transport via the Gβγ-PKD signaling pathway.
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Affiliation(s)
- Thamara Hewavitharana
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, 233 S. 10th St., 839 BLSB, Philadelphia, PA 19107, United States.
| | - Philip B Wedegaertner
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, 233 S. 10th St., 839 BLSB, Philadelphia, PA 19107, United States.
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44
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Abstract
COPII vesicles mediate export of secretory cargo from the endoplasmic reticulum (ER). However, a standard COPII vesicle with a diameter of 60-90 nm is too small to export collagens that are composed of rigid triple helices of up to 400 nm in length. How do cells pack and secrete such bulky molecules? This issue is fundamentally important, as collagens constitute approximately 25% of our dry body weight and are essential for almost all cell-cell interactions. Recently, a potential mechanism for the biogenesis of mega-transport carriers was identified, involving packing collagens and increasing the size of COPII coats. Packing is mediated by TANGO1, which binds procollagen VII in the lumen and interacts with the COPII proteins Sec23/Sec24 on the cytoplasmic side of the ER. Cullin3, an E3 ligase, and its specific adaptor protein, KLHL12, ubiquitinate Sec31, which could increase the size of COPII coats. Recruitment of these proteins and their specific interactors into COPII-mediated vesicle biogenesis may be all that is needed for the export of bulky collagens from the ER. Nonetheless, we present an alternative pathway in which TANGO1 and COPII cooperate to export collagens without generating a mega-transport carrier.
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45
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Xie S, Naslavsky N, Caplan S. Diacylglycerol kinases in membrane trafficking. CELLULAR LOGISTICS 2015; 5:e1078431. [PMID: 27057419 DOI: 10.1080/21592799.2015.1078431] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2015] [Revised: 07/22/2015] [Accepted: 07/24/2015] [Indexed: 10/23/2022]
Abstract
Diacylglycerol kinases (DGKs) belong to a family of cytosolic kinases that regulate the phosphorylation of diacylglycerol (DAG), converting it into phosphatidic acid (PA). There are 10 known mammalian DGK isoforms, each with a different tissue distribution and substrate specificity. These differences allow regulation of cellular responses by fine-tuning the delicate balance of cellular DAG and PA. DGK isoforms are best characterized as mediators of signal transduction and immune function. However, since recent studies reveal that DAG and PA are also involved in the regulation of endocytic trafficking, it is therefore anticipated that DGKs also plays an important role in membrane trafficking. In this review, we summarize the literature discussing the role of DGK isoforms at different stages of endocytic trafficking, including endocytosis, exocytosis, endocytic recycling, and transport from/to the Golgi apparatus. Overall, these studies contribute to our understanding of the involvement of PA and DAG in endocytic trafficking, an area of research that is drawing increasing attention in recent years.
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Affiliation(s)
- Shuwei Xie
- Department of Biochemistry and Molecular Biology and the Fred and Pamela Buffett Cancer Center; University of Nebraska Medical Center ; Omaha, NE USA
| | - Naava Naslavsky
- Department of Biochemistry and Molecular Biology and the Fred and Pamela Buffett Cancer Center; University of Nebraska Medical Center ; Omaha, NE USA
| | - Steve Caplan
- Department of Biochemistry and Molecular Biology and the Fred and Pamela Buffett Cancer Center; University of Nebraska Medical Center ; Omaha, NE USA
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46
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Paczkowski JE, Richardson BC, Fromme JC. Cargo adaptors: structures illuminate mechanisms regulating vesicle biogenesis. Trends Cell Biol 2015; 25:408-16. [PMID: 25795254 DOI: 10.1016/j.tcb.2015.02.005] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2014] [Revised: 02/11/2015] [Accepted: 02/19/2015] [Indexed: 12/29/2022]
Abstract
Cargo adaptors sort transmembrane protein cargos into nascent vesicles by binding directly to their cytosolic domains. Recent studies have revealed previously unappreciated roles for cargo adaptors and regulatory mechanisms governing their function. The adaptor protein (AP)-1 and AP-2 clathrin adaptors switch between open and closed conformations that ensure they function at the right place at the right time. The exomer cargo adaptor has a direct role in remodeling the membrane for vesicle fission. Several different cargo adaptors functioning in distinct trafficking pathways at the Golgi are similarly regulated through bivalent binding to the ADP-ribosylation factor 1 (Arf1) GTPase, potentially enabling regulation by a threshold concentration of Arf1. Taken together, these studies highlight that cargo adaptors do more than just adapt cargos.
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Affiliation(s)
- Jon E Paczkowski
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY 14853, USA
| | - Brian C Richardson
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY 14853, USA
| | - J Christopher Fromme
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY 14853, USA.
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The Road not Taken: Less Traveled Roads from the TGN to the Plasma Membrane. MEMBRANES 2015; 5:84-98. [PMID: 25764365 PMCID: PMC4384092 DOI: 10.3390/membranes5010084] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/03/2014] [Accepted: 02/27/2015] [Indexed: 12/22/2022]
Abstract
The trans-Golgi network functions in the distribution of cargo into different transport vesicles that are destined to endosomes, lysosomes and the plasma membrane. Over the years, it has become clear that more than one transport pathway promotes plasma membrane localization of proteins. In spite of the importance of temporal and spatial control of protein localization at the plasma membrane, the regulation of sorting into and the formation of different transport containers are still poorly understood. In this review different transport pathways, with a special emphasis on exomer-dependent transport, and concepts of regulation and sorting at the TGN are discussed.
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48
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Gendre D, Jonsson K, Boutté Y, Bhalerao RP. Journey to the cell surface--the central role of the trans-Golgi network in plants. PROTOPLASMA 2015; 252:385-98. [PMID: 25187082 DOI: 10.1007/s00709-014-0693-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2014] [Accepted: 08/21/2014] [Indexed: 05/11/2023]
Abstract
The secretion of proteins, lipids, and carbohydrates to the cell surface is essential for plant development and adaptation. Secreted substances synthesized at the endoplasmic reticulum pass through the Golgi apparatus and trans-Golgi network (TGN) en route to the plasma membrane via the conventional secretion pathway. The TGN is morphologically and functionally distinct from the Golgi apparatus. The TGN is located at the crossroads of many trafficking pathways and regulates a range of crucial processes including secretion to the cell surface, transport to the vacuole, and the reception of endocytic cargo. This review outlines the TGN's central role in cargo secretion, showing that its behavior is more complex and controlled than the bulk-flow hypothesis suggests. Its formation, structure, and maintenance are discussed along with the formation and release of secretory vesicles.
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Affiliation(s)
- Delphine Gendre
- Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, SE-901 83, Umeå, Sweden,
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Weber P, Hornjik M, Olayioye MA, Hausser A, Radde NE. A computational model of PKD and CERT interactions at the trans-Golgi network of mammalian cells. BMC SYSTEMS BIOLOGY 2015; 9:9. [PMID: 25889812 PMCID: PMC4349302 DOI: 10.1186/s12918-015-0147-1] [Citation(s) in RCA: 179] [Impact Index Per Article: 19.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/15/2014] [Accepted: 01/26/2015] [Indexed: 11/10/2022]
Abstract
BACKGROUND In mammalian cells protein-lipid interactions at the trans-Golgi network (TGN) determine the formation of vesicles, which transfer secretory proteins to the cellular membrane. This process is regulated by a complex molecular network including protein kinase D (PKD), which is directly involved in the fission of transport vesicles, and its interaction with the ceramide transfer protein CERT that transports ceramide from the endoplasmic reticulum to the TGN. RESULTS Here we present a novel quantitative kinetic model for the interactions of the key players PKD, phosphatidylinositol 4-kinase III beta (PI4KIII β) and CERT at the TGN membranes. We use sampling-based Bayesian analysis and perturbation experiments for model calibration and validation. CONCLUSIONS Our quantitative predictions of absolute molecular concentrations and reaction fluxes have major biological implications: Model comparison provides evidence that PKD and CERT interact in a cooperative manner to regulate ceramide transfer. Furthermore, we identify active PKD to be the dominant regulator of the network, especially of CERT-mediated ceramide transfer.
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Affiliation(s)
- Patrick Weber
- Institute for Systems Theory and Automatic Control, University of Stuttgart, Pfaffenwaldring 9, Stuttgart, 70569, Germany.
| | - Mariana Hornjik
- Institute of Cell Biology and Immunology, University of Stuttgart, Stuttgart, 70569, Germany.
| | - Monilola A Olayioye
- Institute of Cell Biology and Immunology, University of Stuttgart, Stuttgart, 70569, Germany.
| | - Angelika Hausser
- Institute of Cell Biology and Immunology, University of Stuttgart, Stuttgart, 70569, Germany.
| | - Nicole E Radde
- Institute for Systems Theory and Automatic Control, University of Stuttgart, Pfaffenwaldring 9, Stuttgart, 70569, Germany.
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Membrane trafficking in the yeast Saccharomyces cerevisiae model. Int J Mol Sci 2015; 16:1509-25. [PMID: 25584613 PMCID: PMC4307317 DOI: 10.3390/ijms16011509] [Citation(s) in RCA: 96] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2014] [Accepted: 12/19/2014] [Indexed: 11/29/2022] Open
Abstract
The yeast Saccharomyces cerevisiae is one of the best characterized eukaryotic models. The secretory pathway was the first trafficking pathway clearly understood mainly thanks to the work done in the laboratory of Randy Schekman in the 1980s. They have isolated yeast sec mutants unable to secrete an extracellular enzyme and these SEC genes were identified as encoding key effectors of the secretory machinery. For this work, the 2013 Nobel Prize in Physiology and Medicine has been awarded to Randy Schekman; the prize is shared with James Rothman and Thomas Südhof. Here, we present the different trafficking pathways of yeast S. cerevisiae. At the Golgi apparatus newly synthesized proteins are sorted between those transported to the plasma membrane (PM), or the external medium, via the exocytosis or secretory pathway (SEC), and those targeted to the vacuole either through endosomes (vacuolar protein sorting or VPS pathway) or directly (alkaline phosphatase or ALP pathway). Plasma membrane proteins can be internalized by endocytosis (END) and transported to endosomes where they are sorted between those targeted for vacuolar degradation and those redirected to the Golgi (recycling or RCY pathway). Studies in yeast S. cerevisiae allowed the identification of most of the known effectors, protein complexes, and trafficking pathways in eukaryotic cells, and most of them are conserved among eukaryotes.
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