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Wu S, Zhang Y, Hou Y, Zhu J, Yang H, Cui Y. Research on the role of exosomes secreted by immortalized adipose-derived mesenchymal stem cells differentiated into pericytes in the repair of high glucose-induced retinal vascular endothelial cell damage. Exp Eye Res 2024; 247:110046. [PMID: 39147191 DOI: 10.1016/j.exer.2024.110046] [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: 06/20/2024] [Revised: 07/27/2024] [Accepted: 08/13/2024] [Indexed: 08/17/2024]
Abstract
Diabetic retinopathy, a leading cause of vision impairment, is marked by microvascular complications in the retina, including pericyte loss, a key indicator of early-stage disease. This study explores the therapeutic potential of exosomes derived from immortalized adipose-mesenchymal stem cells differentiated into pericyte-like cells in restoring the function of mouse retinal microvascular endothelial cells damaged by high glucose conditions, thereby contributing to the understanding of early diabetic retinopathy intervention strategies. To induce immortalized adipose-mesenchymal stem cells differentiation into pericyte-like cells, the study employed pericyte growth supplement. And confirmed the success of cell differentiation through the detection of α-smooth muscle actin and neural/glial antigen 2 expression by Western blot and immunofluorescence. Exosomes were isolated from the culture supernatant of immortalized adipose-mesenchymal stem cells using ultracentrifugation and characterized through Western blot for exosomal markers (CD9, CD81, and TSG101), transmission electron microscopy, and nanoparticle tracking analysis. Their influence on mouse retinal microvascular endothelial cells under high glucose stress was assessed through various functional assays. Findings revealed that exosomes, especially those from pericyte-like immortalized adipose-mesenchymal stem cells, were efficiently internalized by retinal microvascular endothelial cells and effectively counteracted high glucose-induced apoptosis. These exosomes also mitigated the rise in reactive oxygen species levels and suppressed the migratory and angiogenic properties of retinal microvascular endothelial cells, as demonstrated by Transwell and tube formation assays, respectively. Furthermore, they preserved endothelial barrier function, reducing hyperglycemia-induced permeability. At the molecular level, qRT-PCR analysis showed that exosome treatment modulated the expression of critical genes involved in angiogenesis (VEGF-A, ANG2, MMP9), inflammation (IL-1β, TNF-α), gap junction communication (CX43), and cytoskeletal regulation (ROCK1), with the most prominent effects seen with exosomes from pericyte-like immortalized adipose-mesenchymal stem cells. High glucose increased the expression of pro-angiogenic and pro-inflammatory markers, which were effectively normalized post-exosome treatment. In conclusion, this research highlights the reparative capacity of exosomes secreted by pericyte-like differentiated immortalized adipose-mesenchymal stem cells in reversing the detrimental effects of high glucose on retinal microvascular endothelial cells. By reducing apoptosis, oxidative stress, inflammation, and abnormal angiogenic behavior, these exosomes present a promising avenue for therapeutic intervention in early diabetic retinopathy. Future studies can focus on elucidating the precise molecular mechanisms and exploring their translational potential in vivo.
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Affiliation(s)
- Sihui Wu
- Department of Ophthalmology, Qilu Hospital of Shandong University, Shandong University, Jinan, Shandong Province, China; School of Medicine, Shandong University, Jinan, Shandong Province, China; NHC Key Laboratory of Otorhinolaryngology, Qilu Hospital of Shandong University, Jinan, Shandong Province, China; Laboratory of Basic Medical Sciences, Qilu Hospital of Shandong University, Jinan, Shandong Province, China
| | - Yunnan Zhang
- Department of Ophthalmology, Qilu Hospital of Shandong University, Shandong University, Jinan, Shandong Province, China; School of Medicine, Shandong University, Jinan, Shandong Province, China; NHC Key Laboratory of Otorhinolaryngology, Qilu Hospital of Shandong University, Jinan, Shandong Province, China; Laboratory of Basic Medical Sciences, Qilu Hospital of Shandong University, Jinan, Shandong Province, China
| | - Yaru Hou
- Department of Ophthalmology, Qilu Hospital of Shandong University, Shandong University, Jinan, Shandong Province, China; School of Medicine, Shandong University, Jinan, Shandong Province, China; NHC Key Laboratory of Otorhinolaryngology, Qilu Hospital of Shandong University, Jinan, Shandong Province, China; Laboratory of Basic Medical Sciences, Qilu Hospital of Shandong University, Jinan, Shandong Province, China
| | - Jing Zhu
- Department of Ophthalmology, Qilu Hospital of Shandong University, Shandong University, Jinan, Shandong Province, China
| | - Hongling Yang
- Department of Ophthalmology, Qilu Hospital of Shandong University, Shandong University, Jinan, Shandong Province, China
| | - Yan Cui
- Department of Ophthalmology, Qilu Hospital of Shandong University, Shandong University, Jinan, Shandong Province, China.
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2
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Lee C, Lepore D, Lee SH, Kim TG, Buwa N, Lee J, Munson M, Yoon TY. Exocyst stimulates multiple steps of exocytic SNARE complex assembly and vesicle fusion. Nat Struct Mol Biol 2024:10.1038/s41594-024-01388-2. [PMID: 39242980 DOI: 10.1038/s41594-024-01388-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2023] [Accepted: 08/13/2024] [Indexed: 09/09/2024]
Abstract
Exocyst is a large multisubunit tethering complex essential for targeting and fusion of secretory vesicles in eukaryotic cells. Although the assembled exocyst complex has been proposed to tether vesicles to the plasma membrane and activate soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs) for membrane fusion, the key biochemical steps that exocyst stimulates in SNARE-mediated fusion are undetermined. Here we use a combination of single-molecule and bulk fluorescence assays to investigate the roles of purified octameric yeast exocyst complexes in a reconstituted yeast exocytic SNARE assembly and vesicle fusion system. Exocyst had stimulatory roles in multiple distinct steps ranging from SNARE protein activation to binary and ternary complex assembly. Importantly, exocyst had a downstream role in driving membrane fusion and full content mixing of vesicle lumens. Our data suggest that exocyst provides extensive chaperoning functions across the entire process of SNARE complex assembly and fusion, thereby governing exocytosis at multiple steps.
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Affiliation(s)
- Chanwoo Lee
- School of Biological Sciences and Institute for Molecular Biology and Genetics, Seoul National University, Seoul, South Korea
| | - Dante Lepore
- Department of Biochemistry and Molecular Biotechnology, University of Massachusetts Medical School, Worcester, MA, USA
| | - Seung-Hak Lee
- School of Biological Sciences and Institute for Molecular Biology and Genetics, Seoul National University, Seoul, South Korea
| | - Tae Gyun Kim
- School of Biological Sciences and Institute for Molecular Biology and Genetics, Seoul National University, Seoul, South Korea
| | - Natasha Buwa
- Department of Biochemistry and Molecular Biotechnology, University of Massachusetts Medical School, Worcester, MA, USA
| | - Jongchan Lee
- School of Biological Sciences and Institute for Molecular Biology and Genetics, Seoul National University, Seoul, South Korea
| | - Mary Munson
- Department of Biochemistry and Molecular Biotechnology, University of Massachusetts Medical School, Worcester, MA, USA.
| | - Tae-Young Yoon
- School of Biological Sciences and Institute for Molecular Biology and Genetics, Seoul National University, Seoul, South Korea.
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Zuriegat Q, Abubakar YS, Wang Z, Chen M, Zhang J. Emerging Roles of Exocyst Complex in Fungi: A Review. J Fungi (Basel) 2024; 10:614. [PMID: 39330374 PMCID: PMC11433146 DOI: 10.3390/jof10090614] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2024] [Revised: 08/19/2024] [Accepted: 08/21/2024] [Indexed: 09/28/2024] Open
Abstract
The exocyst complex, an evolutionarily conserved octameric protein assembly, plays a central role in the targeted binding and fusion of vesicles at the plasma membrane. In fungal cells, this transport system is essential for polarized growth, morphogenesis, cell wall maintenance and virulence. Recent advances have greatly improved our understanding of the role and regulation of the exocyst complex in fungi. This review synthesizes these developments and focuses on the intricate interplay between the exocyst complex, specific fungal cargos and regulatory proteins. Insights into thestructure of the exocyst and its functional dynamics have revealed new dimensions of its architecture and its interactions with the cellular environment. Furthermore, the regulation of exocyst activity involves complex signaling pathways and interactions with cytoskeletal elements that are crucial for its role in vesicle trafficking. By exploring these emerging themes, this review provides a comprehensive overview of the multifaceted functions of the exocyst complex in fungal biology. Understanding these mechanisms offers potential avenues for novel therapeutic strategies against fungal pathogens and insights into the general principles of vesicle trafficking in eukaryotic cells. The review therefore highlights the importance of the exocyst complex in maintaining cellular functions and its broader implications in fungal pathogenicity and cell biology.
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Affiliation(s)
- Qussai Zuriegat
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Ministerial and Provincial Joint Innovation Centre for Safety Production of Cross-Strait Crops, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou 350002, China; (Q.Z.); (Y.S.A.); (Z.W.)
| | - Yakubu Saddeeq Abubakar
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Ministerial and Provincial Joint Innovation Centre for Safety Production of Cross-Strait Crops, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou 350002, China; (Q.Z.); (Y.S.A.); (Z.W.)
| | - Zonghua Wang
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Ministerial and Provincial Joint Innovation Centre for Safety Production of Cross-Strait Crops, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou 350002, China; (Q.Z.); (Y.S.A.); (Z.W.)
- Fujian Key Laboratory on Conservation and Sustainable Utilization of Marine Biodiversity, College of Materials and Chemical Engineering, Minjiang University, Fuzhou 350108, China
| | - Meilian Chen
- Fujian Key Laboratory on Conservation and Sustainable Utilization of Marine Biodiversity, College of Materials and Chemical Engineering, Minjiang University, Fuzhou 350108, China
| | - Jun Zhang
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Ministerial and Provincial Joint Innovation Centre for Safety Production of Cross-Strait Crops, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou 350002, China; (Q.Z.); (Y.S.A.); (Z.W.)
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4
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Wang Y, Xiao T, Zhao C, Li G. The Regulation of Exosome Generation and Function in Physiological and Pathological Processes. Int J Mol Sci 2023; 25:255. [PMID: 38203424 PMCID: PMC10779122 DOI: 10.3390/ijms25010255] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2023] [Revised: 12/16/2023] [Accepted: 12/21/2023] [Indexed: 01/12/2024] Open
Abstract
Exosomes, a type of extracellular vesicle with a diameter of approximately 100 nm that is secreted by all cells, regulate the phenotype and function of recipient cells by carrying molecules such as proteins, nucleic acids, and lipids and are important mediators of intercellular communication. Exosomes are involved in various physiological and pathological processes such as immunomodulation, angiogenesis, tumorigenesis, metastasis, and chemoresistance. Due to their excellent properties, exosomes have shown their potential application in the clinical diagnosis and treatment of disease. The functions of exosomes depend on their biogenesis, uptake, and composition. Thus, a deeper understanding of these processes and regulatory mechanisms can help to find new targets for disease diagnosis and therapy. Therefore, this review summarizes and integrates the recent advances in the regulatory mechanisms of the entire biological process of exosomes, starting from the formation of early-sorting endosomes (ESCs) by plasma membrane invagination to the release of exosomes by fusion of multivesicular bodies (MVBs) with the plasma membrane, as well as the regulatory process of the interactions between exosomes and recipient cells. We also describe and discuss the regulatory mechanisms of exosome production in tumor cells and the potential of exosomes used in cancer diagnosis and therapy.
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Affiliation(s)
| | | | | | - Guiying Li
- Key Laboratory for Molecular Enzymology and Engineering of the Ministry of Education, School of Life Sciences, Jilin University, Changchun 130012, China; (Y.W.); (T.X.); (C.Z.)
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5
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Wu KY, Ahmad H, Lin G, Carbonneau M, Tran SD. Mesenchymal Stem Cell-Derived Exosomes in Ophthalmology: A Comprehensive Review. Pharmaceutics 2023; 15:1167. [PMID: 37111652 PMCID: PMC10142951 DOI: 10.3390/pharmaceutics15041167] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2023] [Revised: 03/26/2023] [Accepted: 04/03/2023] [Indexed: 04/29/2023] Open
Abstract
Over the past decade, the field of mesenchymal stem cell (MSC) therapy has exhibited rapid growth. Due to their regenerative, reparatory, and immunomodulatory capacities, MSCs have been widely investigated as therapeutic agents in the cell-based treatment of chronic ophthalmic pathologies. However, the applicability of MSC-based therapy is limited by suboptimal biocompatibility, penetration, and delivery to the target ocular tissues. An emerging body of research has elucidated the role of exosomes in the biological functions of MSCs, and that MSC-derived extracellular vesicles (EVs) possess anti-inflammatory, anti-apoptotic, tissue repairing, neuroprotective, and immunomodulatory properties similar to MSCs. The recent advances in MSCs-derived exosomes can serve as solutions to the challenges faced by MSCs-therapy. Due to their nano-dimensions, MSC-derived exosomes can rapidly penetrate biological barriers and reach immune-privileged organs, allowing for efficient delivery of therapeutic factors such as trophic and immunomodulatory agents to ocular tissues that are typically challenging to target by conventional therapy and MSCs transplantation. In addition, the use of EVs minimizes the risks associated with mesenchymal stem cell transplantation. In this literature review, we focus on the studies published between 2017 and 2022, highlighting the characteristics of EVs derived from MSCs and their biological functions in treating anterior and posterior segment ocular diseases. Additionally, we discuss the potential use of EVs in clinical settings. Rapid advancements in regenerative medicine and exosome-based drug delivery, in conjunction with an increased understanding of ocular pathology and pharmacology, hold great promise for the treatment of ocular diseases. The potential of exosome-based therapies is exciting and can revolutionize the way we approach these ocular conditions.
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Affiliation(s)
- Kevin Y. Wu
- Department of Surgery—Division of Ophthalmology, University of Sherbrooke, Sherbrooke, QC J1G 2E8, Canada
| | - Hamza Ahmad
- Faculty of Medicine, McGill University, Montreal, QC H3A 0G4, Canada
| | - Grace Lin
- Faculty of Medicine, University of Montreal, Montreal, QC H3T 1J4, Canada
| | - Marjorie Carbonneau
- Department of Surgery—Division of Ophthalmology, University of Sherbrooke, Sherbrooke, QC J1G 2E8, Canada
| | - Simon D. Tran
- Faculty of Dental Medicine and Oral Health Sciences, McGill University, Montreal, QC H3A 1G1, Canada
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6
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Safavian D, Kim MS, Xie H, El-Zeiry M, Palander O, Dai L, Collins RF, Froese C, Shannon R, Nagata KI, Trimble WS. Septin-mediated RhoA activation engages the exocyst complex to recruit the cilium transition zone. J Cell Biol 2023; 222:e201911062. [PMID: 36912772 PMCID: PMC10039714 DOI: 10.1083/jcb.201911062] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2019] [Revised: 01/25/2022] [Accepted: 01/05/2023] [Indexed: 03/14/2023] Open
Abstract
Septins are filamentous GTPases that play important but poorly characterized roles in ciliogenesis. Here, we show that SEPTIN9 regulates RhoA signaling at the base of cilia by binding and activating the RhoA guanine nucleotide exchange factor, ARHGEF18. GTP-RhoA is known to activate the membrane targeting exocyst complex, and suppression of SEPTIN9 causes disruption of ciliogenesis and mislocalization of an exocyst subunit, SEC8. Using basal body-targeted proteins, we show that upregulating RhoA signaling at the cilium can rescue ciliary defects and mislocalization of SEC8 caused by global SEPTIN9 depletion. Moreover, we demonstrate that the transition zone components, RPGRIP1L and TCTN2, fail to accumulate at the transition zone in cells lacking SEPTIN9 or depleted of the exocyst complex. Thus, SEPTIN9 regulates the recruitment of transition zone proteins on Golgi-derived vesicles by activating the exocyst via RhoA to allow the formation of primary cilia.
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Affiliation(s)
- Darya Safavian
- Cell Biology Program, Hospital for Sick Children, Toronto, Ontario, Canada
| | - Moshe S. Kim
- Cell Biology Program, Hospital for Sick Children, Toronto, Ontario, Canada
| | - Hong Xie
- Cell Biology Program, Hospital for Sick Children, Toronto, Ontario, Canada
| | - Maha El-Zeiry
- Cell Biology Program, Hospital for Sick Children, Toronto, Ontario, Canada
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
| | - Oliva Palander
- Cell Biology Program, Hospital for Sick Children, Toronto, Ontario, Canada
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
| | - Lu Dai
- Cell Biology Program, Hospital for Sick Children, Toronto, Ontario, Canada
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
| | - Richard F. Collins
- Cell Biology Program, Hospital for Sick Children, Toronto, Ontario, Canada
| | - Carol Froese
- Cell Biology Program, Hospital for Sick Children, Toronto, Ontario, Canada
| | - Rachel Shannon
- Cell Biology Program, Hospital for Sick Children, Toronto, Ontario, Canada
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
| | - Koh-ichi Nagata
- Department of Molecular Neurobiology, Institute for Developmental Research, Aichi Human Service Center, Kasugai, Aichi, Japan
| | - William S. Trimble
- Cell Biology Program, Hospital for Sick Children, Toronto, Ontario, Canada
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
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7
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Ravindran P, Püschel AW. An isoform-specific function of Cdc42 in regulating mammalian Exo70 during axon formation. Life Sci Alliance 2023; 6:6/3/e202201722. [PMID: 36543541 PMCID: PMC9772827 DOI: 10.26508/lsa.202201722] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2022] [Revised: 12/09/2022] [Accepted: 12/09/2022] [Indexed: 12/24/2022] Open
Abstract
The highly conserved GTPase Cdc42 is an essential regulator of cell polarity and promotes exocytosis through the exocyst complex in budding yeast and Drosophila In mammals, this function is performed by the closely related GTPase TC10, whereas mammalian Cdc42 does not interact with the exocyst. Axon formation is facilitated by the exocyst complex that tethers vesicles before their fusion to expand the plasma membrane. This function depends on the recruitment of the Exo70 subunit to the plasma membrane. Alternative splicing generates two Cdc42 isoforms that differ in their C-terminal 10 amino acids. Our results identify an isoform-specific function of Cdc42 in neurons. We show that the brain-specific Cdc42b isoform, in contrast to the ubiquitous isoform Cdc42u, can interact with Exo70. Inactivation of Arhgef7 or Cdc42b interferes with the exocytosis of post-Golgi vesicles in the growth cone. Cdc42b regulates exocytosis and axon formation downstream of its activator Arhgef7. Thus, the function of Cdc42 in regulating exocytosis is conserved in mammals but specific to one isoform.
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Affiliation(s)
- Priyadarshini Ravindran
- Institut für Integrative Zellbiologie und Physiologie, Westfälische Wilhelms-Universität, Münster, Germany
| | - Andreas W Püschel
- Institut für Integrative Zellbiologie und Physiologie, Westfälische Wilhelms-Universität, Münster, Germany .,Cells-in-Motion Interfaculty Center, University of Münster, Münster, Germany
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8
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Miller BK, Rossi G, Hudson S, Cully D, Baker RW, Brennwald P. Allosteric regulation of exocyst: Discrete activation of tethering by two spatial signals. J Cell Biol 2023; 222:213852. [PMID: 36729146 PMCID: PMC9929655 DOI: 10.1083/jcb.202206108] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Revised: 11/17/2022] [Accepted: 01/05/2023] [Indexed: 02/03/2023] Open
Abstract
The exocyst imparts spatial control during exocytic vesicle tethering through its interactions with proteins and lipids on the vesicle and the plasma membrane. One such interaction is with the vesicle tether Sro7, although the outcome of this interaction is poorly understood. Here, we describe how Sro7 binding to the Exo84 subunit results in activation of the exocyst complex which leads to an increase in avidity for the Rab GTPase Sec4 and an increase in exocyst-mediated vesicle tethering. Gain-of-function (GOF) mutations in Exo84 that mimic Sro7 activation replicate these biochemical changes and result in allosteric changes within the complex. Direct comparison of GOF mutants which mimic Sro7- and Rho/Cdc42-activation of the exocyst reveals distinct mechanisms and outcomes. We propose a model by which these two activation pathways reside within the same tethering complex but remain insulated from one another. Structural modeling suggests a related mechanism for Sro7 activation of the exocyst in yeast and Ral GTPase activation of the exocyst in animal cells.
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Affiliation(s)
- Brittany K. Miller
- https://ror.org/0130frc33Department of Cell Biology and Physiology, School of Medicine, University of North Carolina, Chapel Hill, NC, USA
| | - Guendalina Rossi
- https://ror.org/0130frc33Department of Cell Biology and Physiology, School of Medicine, University of North Carolina, Chapel Hill, NC, USA
| | - Sara Hudson
- https://ror.org/0130frc33Department of Cell Biology and Physiology, School of Medicine, University of North Carolina, Chapel Hill, NC, USA
| | - David Cully
- https://ror.org/0130frc33Department of Cell Biology and Physiology, School of Medicine, University of North Carolina, Chapel Hill, NC, USA
| | - Richard W. Baker
- Department of Biochemistry and Biophysics, School of Medicine, University of North Carolina, Chapel Hill, NC, USA
| | - Patrick Brennwald
- https://ror.org/0130frc33Department of Cell Biology and Physiology, School of Medicine, University of North Carolina, Chapel Hill, NC, USA,Correspondence to Patrick Brennwald:
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9
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Wu KY, Kulbay M, Tanasescu C, Jiao B, Nguyen BH, Tran SD. An Overview of the Dry Eye Disease in Sjögren's Syndrome Using Our Current Molecular Understanding. Int J Mol Sci 2023; 24:1580. [PMID: 36675090 PMCID: PMC9866656 DOI: 10.3390/ijms24021580] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Revised: 01/10/2023] [Accepted: 01/11/2023] [Indexed: 01/15/2023] Open
Abstract
Sjögren's syndrome is a chronic and insidious auto-immune disease characterized by lymphocyte infiltration of exocrine glands. The patients typically present with ocular surface diseases related to dry eye and other systemic manifestations. However, due to the high prevalence of dry eye disease and the lack of objective and clinically reliable diagnostic tools, discriminating Sjögren's syndrome dry eye (SSDE) from non-Sjögren's syndrome dry eye (NSSDE) remains a challenge for clinicians. Diagnosing SS is important to improve the quality of life of patients through timely referral for systemic workups, as SS is associated with serious systemic complications such as lymphoma and other autoimmune diseases. The purpose of this article is to describe the current molecular understanding of Sjögren's syndrome and its implications for novel diagnostic modalities on the horizon. A literature review of the pre-clinical and clinical studies published between 2016 and 2022 was conducted. The SSDE pathophysiology and immunology pathways have become better understood in recent years. Novel diagnostic modalities, such as tear and saliva proteomics as well as exosomal biomarkers, provide hope on the horizon.
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Affiliation(s)
- Kevin Y. Wu
- Department of Surgery, Division of Ophthalmology, University of Sherbrooke, Sherbrooke, QC J1G 2E8, Canada
| | - Merve Kulbay
- Faculty of Medicine, University of Montreal, Montreal, QC H3T 1J4, Canada
| | - Cristina Tanasescu
- School of Optometry, University of Montreal, Montreal, QC H3T 1P1, Canada
| | - Belinda Jiao
- Department of Medicine, Division of Internal Medicine, University of Sherbrooke, Sherbrooke, QC J1G 2E8, Canada
| | - Bich H. Nguyen
- CHU Sainte Justine Hospital, Montreal, QC H3T 1C5, Canada
| | - Simon D. Tran
- Faculty of Dental Medicine and Oral Health Sciences, McGill University, Montreal, QC H3A 1G1, Canada
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10
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Sulpizio A, Herpin L, Gingras R, Liu W, Bretscher A. Generation and characterization of conditional yeast mutants affecting each of the 2 essential functions of the scaffolding proteins Boi1/2 and Bem1. G3 (BETHESDA, MD.) 2022; 12:jkac273. [PMID: 36218417 PMCID: PMC9713459 DOI: 10.1093/g3journal/jkac273] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/16/2022] [Accepted: 09/23/2022] [Indexed: 02/17/2024]
Abstract
Boi1 and Boi2 are closely related yeast scaffolding proteins, either of which can perform an essential function. Previous studies have suggested a role in cell polarity, interacting with lipids, components of the late secretory pathway, and actin nucleators. We report detailed studies of their localization, dynamics, and the generation and characterization of conditional mutants. Boi1/2 are present on the plasma membrane in dynamic patches, then at the bud neck during cytokinesis. These distributions are unaffected by perturbation of the actin cytoskeleton or the secretory pathway. We identify 2 critical aromatic residues, present in both Boi1 and Boi2, in the essential C-terminal Pleckstrin-Homology domain, that cause temperature-sensitive growth resulting in defects in polarized growth leading to cell lysis. The scaffolding protein, Bem1, colocalizes with Boi1 in patches at the growing bud, and at the bud neck, the latter requiring the N-terminal SH3 domain of Boi1p. Loss of function of Boi1-SH3 domain renders Bem1 essential, which can be fully replaced by a fusion of the SH3b and PB1 domains of Bem1. Thus, the 2 essential functions of the Boi1/2/Bem1 proteins can be satisfied by Bem1-SH3b-PB1 and Boi1-Pleckstrin-Homology. Generation and characterization of conditional mutations in the essential function of Bem1 reveal a slow onset of defects in polarized growth, which is difficult to define a specific initial defect. This study provides more details into the functions of Boi1/2 and their relationship with Bem1 and presents the generation of conditional mutants that will be useful for future genetic analysis.
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Affiliation(s)
- Abigail Sulpizio
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY 14853, USA
| | - Lancelot Herpin
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY 14853, USA
| | - Robert Gingras
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY 14853, USA
| | - Wenyu Liu
- BioAnalytical Sciences, Genentech Inc., South San Francisco, CA 94080, USA
| | - Anthony Bretscher
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY 14853, USA
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11
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Gingras RM, Sulpizio AM, Park J, Bretscher A. High-resolution secretory timeline from vesicle formation at the Golgi to fusion at the plasma membrane in S. cerevisiae. eLife 2022; 11:e78750. [PMID: 36331188 PMCID: PMC9671497 DOI: 10.7554/elife.78750] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2022] [Accepted: 11/03/2022] [Indexed: 11/06/2022] Open
Abstract
Most of the components in the yeast secretory pathway have been studied, yet a high-resolution temporal timeline of their participation is lacking. Here, we define the order of acquisition, lifetime, and release of critical components involved in late secretion from the Golgi to the plasma membrane. Of particular interest is the timing of the many reported effectors of the secretory vesicle Rab protein Sec4, including the myosin-V Myo2, the exocyst complex, the lgl homolog Sro7, and the small yeast-specific protein Mso1. At the trans-Golgi network (TGN) Sec4's GEF, Sec2, is recruited to Ypt31-positive compartments, quickly followed by Sec4 and Myo2 and vesicle formation. While transported to the bud tip, the entire exocyst complex, including Sec3, is assembled on to the vesicle. Before fusion, vesicles tether for 5 s, during which the vesicle retains the exocyst complex and stimulates lateral recruitment of Rho3 on the plasma membrane. Sec2 and Myo2 are rapidly lost, followed by recruitment of cytosolic Sro7, and finally the SM protein Sec1, which appears for just 2 s prior to fusion. Perturbation experiments reveal an ordered and robust series of events during tethering that provide insights into the function of Sec4 and effector exchange.
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Affiliation(s)
- Robert M Gingras
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell UniversityIthacaUnited States
| | - Abigail M Sulpizio
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell UniversityIthacaUnited States
| | - Joelle Park
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell UniversityIthacaUnited States
| | - Anthony Bretscher
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell UniversityIthacaUnited States
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12
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Li Q, Chen X, Lin L, Zhang L, Wang L, Bao J, Zhang D. Transcriptomic Dynamics of Active and Inactive States of Rho GTPase MoRho3 in Magnaporthe oryzae. J Fungi (Basel) 2022; 8:jof8101060. [PMID: 36294629 PMCID: PMC9605073 DOI: 10.3390/jof8101060] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2022] [Revised: 10/04/2022] [Accepted: 10/05/2022] [Indexed: 11/17/2022] Open
Abstract
The small Rho GTPase acts as a molecular switch in eukaryotic signal transduction, which plays a critical role in polar cell growth and vesicle trafficking. Previous studies demonstrated that constitutively active (CA) mutant strains, of MoRho3-CA were defective in appressorium formation. While dominant-negative (DN) mutant strains MoRho3-DN shows defects in polar growth. However, the molecular dynamics of MoRho3-mediated regulatory networks in the pathogenesis of Magnaporthe oryzae still needs to be uncovered. Here, we perform comparative transcriptomic profiling of MoRho3-CA and MoRho3-DN mutant strains using a high-throughput RNA sequencing approach. We find that genetic manipulation of MoRho3 significantly disrupts the expression of 28 homologs of Saccharomyces cerevisiae Rho3-interacting proteins, including EXO70, BNI1, and BNI2 in the MoRho3 CA, DN mutant strains. Functional enrichment analyses of up-regulated DEGs reveal a significant enrichment of genes associated with ribosome biogenesis in the MoRho3-CA mutant strain. Down-regulated DEGs in the MoRho3-CA mutant strains shows significant enrichment in starch/sucrose metabolism and the ABC transporter pathway. Moreover, analyses of down-regulated DEGs in the in MoRho3-DN reveals an over-representation of genes enriched in metabolic pathways. In addition, we observe a significant suppression in the expression levels of secreted proteins suppressed in both MoRho3-CA and DN mutant strains. Together, our results uncover expression dynamics mediated by two states of the small GTPase MoRho3, demonstrating its crucial roles in regulating the expression of ribosome biogenesis and secreted proteins.
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Affiliation(s)
- Qian Li
- Meishan Vocational Technical College, Ministerial and Provincial Joint Innovation Centre for Safety Production of Cross-Strait Crops, Fujian Agriculture and Forestry University, Fuzhou 350002, China
- Correspondence: (Q.L.); (D.Z.)
| | - Xi Chen
- State Key Laboratory for Ecological Pest Control of Fujian and Taiwan Crops, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Lianyu Lin
- State Key Laboratory for Ecological Pest Control of Fujian and Taiwan Crops, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Lianhu Zhang
- State Key Laboratory for Ecological Pest Control of Fujian and Taiwan Crops, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou 350002, China
- College of Agronomy, Jiangxi Agricultural University, Nanchang 330045, China
| | - Li Wang
- Meishan Vocational Technical College, Ministerial and Provincial Joint Innovation Centre for Safety Production of Cross-Strait Crops, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Jiandong Bao
- State Key Laboratory for Ecological Pest Control of Fujian and Taiwan Crops, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Dongmei Zhang
- State Key Laboratory for Ecological Pest Control of Fujian and Taiwan Crops, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou 350002, China
- Correspondence: (Q.L.); (D.Z.)
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13
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Cui X, Wang S, Huang Y, Ding X, Wang Z, Zheng L, Bi Y, Ge F, Zhu L, Yuan M, Yalovsky S, Fu Y. Arabidopsis SYP121 acts as an ROP2 effector in the regulation of root hair tip growth. MOLECULAR PLANT 2022; 15:1008-1023. [PMID: 35488430 DOI: 10.1016/j.molp.2022.04.008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2021] [Revised: 04/04/2022] [Accepted: 04/25/2022] [Indexed: 06/14/2023]
Abstract
Tip growth is an extreme form of polarized cell expansion that occurs in all eukaryotic kingdoms to generate highly elongated tubular cells with specialized functions, including fungal hyphae, animal neurons, plant pollen tubes, and root hairs (RHs). RHs are tubular structures that protrude from the root epidermis to facilitate water and nutrient uptake, microbial interactions, and plant anchorage. RH tip growth requires polarized vesicle targeting and active exocytosis at apical growth sites. However, how apical exocytosis is spatially and temporally controlled during tip growth remains elusive. Here, we report that the Qa-Soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) SYP121 acts as an effector of Rho of Plants 2 (ROP2), mediating the regulation of RH tip growth. We show that active ROP2 promotes SYP121 targeting to the apical plasma membrane. Moreover, ROP2 directly interacts with SYP121 and promotes the interaction between SYP121 and the R-SNARE VAMP722 to form a SNARE complex, probably by facilitating the release of the Sec1/Munc18 protein SEC11, which suppresses the function of SYP121. Thus, the ROP2-SYP121 pathway facilitates exocytic trafficking during RH tip growth. Our study uncovers a direct link between an ROP GTPase and vesicular trafficking and a new mechanism for the control of apical exocytosis, whereby ROP GTPase signaling spatially regulates SNARE complex assembly and the polar distribution of a Q-SNARE.
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Affiliation(s)
- Xiankui Cui
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Shuwei Wang
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Yaohui Huang
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Xuening Ding
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Zirong Wang
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Lidan Zheng
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Yujing Bi
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Fanghui Ge
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Lei Zhu
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100193, China; Joint Laboratory for International Cooperation in Crop Molecular Breeding, Ministry of Education, China Agricultural University, Beijing 100193, China
| | - Ming Yuan
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Shaul Yalovsky
- Department of Plant Sciences, Tel Aviv University, Tel Aviv 69978, Israel
| | - Ying Fu
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100193, China; Joint Laboratory for International Cooperation in Crop Molecular Breeding, Ministry of Education, China Agricultural University, Beijing 100193, China.
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14
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van Rees DJ, Bouti P, Klein B, Verkuijlen PJH, van Houdt M, Schornagel K, Tool ATJ, Venet D, Sotiriou C, El-Abed S, Izquierdo M, Guillaume S, Saura C, Di Cosimo S, Huober J, Roylance R, Kim SB, Kuijpers TW, van Bruggen R, van den Berg TK, Matlung HL. Cancer cells resist antibody-mediated destruction by neutrophils through activation of the exocyst complex. J Immunother Cancer 2022; 10:e004820. [PMID: 35728876 PMCID: PMC9214435 DOI: 10.1136/jitc-2022-004820] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/23/2022] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND Neutrophils kill antibody-opsonized tumor cells using trogocytosis, a unique mechanism of destruction of the target plasma. This previously unknown cytotoxic process of neutrophils is dependent on antibody opsonization, Fcγ receptors and CD11b/CD18 integrins. Here, we demonstrate that tumor cells can escape neutrophil-mediated cytotoxicity by calcium (Ca2+)-dependent and exocyst complex-dependent plasma membrane repair. METHODS We knocked down EXOC7 or EXOC4, two exocyst components, to evaluate their involvement in tumor cell membrane repair after neutrophil-induced trogocytosis. We used live cell microscopy and flow cytometry for visualization of the host and tumor cell interaction and tumor cell membrane repair. Last, we reported the mRNA levels of exocyst in breast cancer tumors in correlation to the response in trastuzumab-treated patients. RESULTS We found that tumor cells can evade neutrophil antibody-dependent cellular cytotoxicity (ADCC) by Ca2+-dependent cell membrane repair, a process induced upon neutrophil trogocytosis. Absence of exocyst components EXOC7 or EXOC4 rendered tumor cells vulnerable to neutrophil-mediated ADCC (but not natural killer cell-mediated killing), while neutrophil trogocytosis remained unaltered. Finally, mRNA levels of exocyst components in trastuzumab-treated patients were inversely correlated to complete response to therapy. CONCLUSIONS Our results support that neutrophil attack towards antibody-opsonized cancer cells by trogocytosis induces an active repair process by the exocyst complex in vitro. Our findings provide insight to the possible contribution of neutrophils in current antibody therapies and the tolerance mechanism of tumor cells and support further studies for potential use of the exocyst components as clinical biomarkers.
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Affiliation(s)
- Dieke J van Rees
- Department of Molecular Hematology, Sanquin Research, Amsterdam, The Netherlands
| | - Panagiota Bouti
- Department of Molecular Hematology, Sanquin Research, Amsterdam, The Netherlands
| | - Bart Klein
- Department of Molecular Hematology, Sanquin Research, Amsterdam, The Netherlands
| | - Paul J H Verkuijlen
- Department of Molecular Hematology, Sanquin Research, Amsterdam, The Netherlands
| | - Michel van Houdt
- Department of Molecular Hematology, Sanquin Research, Amsterdam, The Netherlands
| | - Karin Schornagel
- Department of Molecular Hematology, Sanquin Research, Amsterdam, The Netherlands
| | - Anton T J Tool
- Department of Molecular Hematology, Sanquin Research, Amsterdam, The Netherlands
| | - David Venet
- Breast Cancer Translational Research Laboratory JC Heuson, Institut Jules Bordet, Bruxelles, Belgium
| | - Christos Sotiriou
- Breast Cancer Translational Research Laboratory JC Heuson, Institut Jules Bordet, Bruxelles, Belgium
| | | | | | - Sébastien Guillaume
- Department of Psychiatric Emergency & Acute Care, Lapeyronie Hospital, Montpellier, France
| | - Cristina Saura
- SOLTI Innovative Breast Cancer Research, Vall d'Hebron Hospital Universitari, Barcelona, Spain
| | | | - Jens Huober
- Breast Center, University of Ulm, Ulm, Germany
| | - Rebecca Roylance
- Department of Oncology, University College London Hospitals NHS Foundation Trust and NIHR University College London Hospitals Biomedical Research Centre, London, UK
| | - Sung-Bae Kim
- Department of Oncology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, South Korea
| | - Taco W Kuijpers
- Department of Molecular Hematology, Sanquin Research, Amsterdam, The Netherlands
- Department of Pediatric Immunology and Infectious Diseases, Emma Children's Hospital, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Robin van Bruggen
- Department of Molecular Hematology, Sanquin Research, Amsterdam, The Netherlands
| | - Timo K van den Berg
- Department of Molecular Hematology, Sanquin Research, Amsterdam, The Netherlands
- Department of Molecular Cell Biology and Immunology, Amsterdam UMC, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
| | - Hanke L Matlung
- Department of Molecular Hematology, Sanquin Research, Amsterdam, The Netherlands
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15
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Jones JH, Minshall RD. Endothelial Transcytosis in Acute Lung Injury: Emerging Mechanisms and Therapeutic Approaches. Front Physiol 2022; 13:828093. [PMID: 35431977 PMCID: PMC9008570 DOI: 10.3389/fphys.2022.828093] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Accepted: 02/28/2022] [Indexed: 01/08/2023] Open
Abstract
Acute Lung Injury (ALI) is characterized by widespread inflammation which in its severe form, Acute Respiratory Distress Syndrome (ARDS), leads to compromise in respiration causing hypoxemia and death in a substantial number of affected individuals. Loss of endothelial barrier integrity, pneumocyte necrosis, and circulating leukocyte recruitment into the injured lung are recognized mechanisms that contribute to the progression of ALI/ARDS. Additionally, damage to the pulmonary microvasculature by Gram-negative and positive bacteria or viruses (e.g., Escherichia coli, SARS-Cov-2) leads to increased protein and fluid permeability and interstitial edema, further impairing lung function. While most of the vascular leakage is attributed to loss of inter-endothelial junctional integrity, studies in animal models suggest that transendothelial transport of protein through caveolar vesicles, known as transcytosis, occurs in the early phase of ALI/ARDS. Here, we discuss the role of transcytosis in healthy and injured endothelium and highlight recent studies that have contributed to our understanding of the process during ALI/ARDS. We also cover potential approaches that utilize caveolar transport to deliver therapeutics to the lungs which may prevent further injury or improve recovery.
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Affiliation(s)
- Joshua H. Jones
- Department of Pharmacology, University of Illinois College of Medicine at Chicago, Chicago, IL, United States
| | - Richard D. Minshall
- Department of Pharmacology, University of Illinois College of Medicine at Chicago, Chicago, IL, United States,Department of Anesthesiology, University of Illinois College of Medicine at Chicago, Chicago, IL, United States,*Correspondence: Richard D. Minshall,
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16
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Bai S, Hou W, Yao Y, Meng J, Wei Y, Hu F, Hu X, Wu J, Zhang N, Xu R, Tian F, Wang B, Liao H, Du Y, Fang H, He W, Liu Y, Shen B, Du J. Exocyst controls exosome biogenesis via Rab11a. MOLECULAR THERAPY. NUCLEIC ACIDS 2022; 27:535-546. [PMID: 35036064 PMCID: PMC8739877 DOI: 10.1016/j.omtn.2021.12.023] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Accepted: 12/15/2021] [Indexed: 12/24/2022]
Abstract
Tumor cells actively release large quantities of exosomes, which pivotally participate in the regulation of cancer biology, including head and neck cancer (HNC). Exosome biogenesis and release are complex and elaborate processes that are considered to be similar to the process of exocyst-mediated vesicle delivery. By analyzing the expression of exocyst subunits and their role in patients with HNC, we aimed to identify exocyst and its functions in exosome biogenesis and investigate the molecular mechanisms underlying the regulation of exosome transport in HNC cells. We observed that exocysts were highly expressed in HNC cells and could promote exosome secretion in these cells. In addition, downregulation of exocyst expression inhibited HN4 cell proliferation by reducing exosome secretion. Interestingly, immunofluorescence and electron microscopy revealed the accumulation of multivesicular bodies (MVBs) after the knockdown of exocyst. Autophagy, the major pathway of exosome degradation, is not activated by this intracellular accumulation of MVBs, but these MVBs are consumed when autophagy is activated under the condition of cell starvation. Rab11a, a small GTPase that is involved in MVB fusion, also interacted with the exocyst. These findings suggest that the exocyst can regulate exosome biogenesis and participate in the malignant behavior of tumor cells.
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Affiliation(s)
- Suwen Bai
- Longgang District People’s Hospital of Shenzhen & The Second Affiliated Hospital of The Chinese University of Hong Kong, Shenzhen, Guangdong 518172, China
- School of Basic Medical Sciences, Anhui Medical University, 81 Meishan Road, Hefei 230032, Anhui, China
| | - Wenxuan Hou
- School of Basic Medical Sciences, Anhui Medical University, 81 Meishan Road, Hefei 230032, Anhui, China
| | - Yanheng Yao
- School of Basic Medical Sciences, Anhui Medical University, 81 Meishan Road, Hefei 230032, Anhui, China
| | - Jialin Meng
- Department of Urology, The First Affiliated Hospital of Anhui Medical University, Institute of Urology, Anhui Medical University, Anhui Province Key Laboratory of Genitourinary Diseases, Anhui Medical University, Hefei 230022, China
| | - Yuan Wei
- Longgang District People’s Hospital of Shenzhen & The Second Affiliated Hospital of The Chinese University of Hong Kong, Shenzhen, Guangdong 518172, China
- School of Basic Medical Sciences, Anhui Medical University, 81 Meishan Road, Hefei 230032, Anhui, China
| | - Fangfang Hu
- School of Basic Medical Sciences, Anhui Medical University, 81 Meishan Road, Hefei 230032, Anhui, China
| | - Xianyu Hu
- Department of General Surgery, The First Affiliated Hospital of Anhui Medical University, Hefei 230022 Anhui, China
| | - Jing Wu
- Department of Otolaryngology, The First Affiliated Hospital of Anhui Medical University, Hefei 230022, Anhui Province, China
| | - Ning Zhang
- Department of General Surgery, The First Affiliated Hospital of Anhui Medical University, Hefei 230022 Anhui, China
| | - Ruihuan Xu
- Longgang District People’s Hospital of Shenzhen & The Second Affiliated Hospital of The Chinese University of Hong Kong, Shenzhen, Guangdong 518172, China
| | - Faqing Tian
- Longgang District People’s Hospital of Shenzhen & The Second Affiliated Hospital of The Chinese University of Hong Kong, Shenzhen, Guangdong 518172, China
| | - Benguo Wang
- Longgang District People’s Hospital of Shenzhen & The Second Affiliated Hospital of The Chinese University of Hong Kong, Shenzhen, Guangdong 518172, China
| | - Hailan Liao
- Longgang District People’s Hospital of Shenzhen & The Second Affiliated Hospital of The Chinese University of Hong Kong, Shenzhen, Guangdong 518172, China
| | - Yinan Du
- School of Basic Medical Sciences, Anhui Medical University, 81 Meishan Road, Hefei 230032, Anhui, China
| | - Haoshu Fang
- School of Basic Medical Sciences, Anhui Medical University, 81 Meishan Road, Hefei 230032, Anhui, China
| | - Wei He
- School of Basic Medical Sciences, Anhui Medical University, 81 Meishan Road, Hefei 230032, Anhui, China
| | - Yehai Liu
- Department of Otolaryngology, The First Affiliated Hospital of Anhui Medical University, Hefei 230022, Anhui Province, China
| | - Bing Shen
- School of Basic Medical Sciences, Anhui Medical University, 81 Meishan Road, Hefei 230032, Anhui, China
| | - Juan Du
- School of Medicine, The Chinese University of Hong Kong, Shenzhen, Guangdong 518172, China
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17
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Laquel P, Testet E, Tuphile K, Cullin C, Fouillen L, Bessoule JJ, Doignon F. Phosphoinositides containing stearic acid are required for interaction between Rho GTPases and the exocyst to control the late steps of polarised exocytosis. Traffic 2021; 23:120-136. [PMID: 34908215 DOI: 10.1111/tra.12829] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2021] [Revised: 11/18/2021] [Accepted: 12/07/2021] [Indexed: 11/27/2022]
Abstract
Cell polarity is achieved by regulators such as small G proteins, exocyst members and phosphoinositides, with the latter playing a key role when bound to the exocyst proteins Sec3p and Exo70p, and Rho GTPases. This ensures asymmetric growth via the routing of proteins and lipids to the cell surface using actin cables. Previously, using a yeast mutant for a lysophosphatidylinositol acyl transferase encoded by the PSI1 gene, we demonstrated the role of stearic acid in the acyl chain of phosphoinositides in cytoskeletal organisation and secretion. Here, we use a genetic approach to characterise the effect on late steps of the secretory pathway. The constitutive overexpression of PSI1 in mutants affecting kinases involved in the phosphoinositide pathway demonstrated the role of molecular species containing stearic acid in bypassing a lack of phosphatidylinositol-4-phosphate PI(4)P at the plasma membrane, which is essential for the function of the Cdc42p module. Decreasing the levels of stearic acid-containing phosphoinositides modifies the environment of the actors involved in the control of late steps in the secretory pathway. This leads to decreased interactions between Exo70p and Sec3p, with Cdc42p, Rho1p and Rho3p, due to disruption of the GTP/GDP ratio of at least Rho1p and Rho3p GTPases, thereby preventing activation of the exocyst.
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Affiliation(s)
- P Laquel
- Univ. Bordeaux, CNRS, Laboratoire de Biogenèse Membranaire, UMR 5200, F-33140 Villenave d'Ornon, France
| | - E Testet
- Univ. Bordeaux, CNRS, Laboratoire de Biogenèse Membranaire, UMR 5200, F-33140 Villenave d'Ornon, France
| | - K Tuphile
- Univ. Bordeaux, CNRS, Laboratoire de Biogenèse Membranaire, UMR 5200, F-33140 Villenave d'Ornon, France
| | - C Cullin
- Univ. Bordeaux, CNRS, Laboratoire de Chimie Biologie des Membranes & des Nano-objets, UMR 5248, Pessac, France
| | - L Fouillen
- Univ. Bordeaux, CNRS, Laboratoire de Biogenèse Membranaire, UMR 5200, F-33140 Villenave d'Ornon, France.,Metabolome Facility of Bordeaux, Functional Genomics Centre, F-33883 Villenave d'Ornon, France
| | - J J Bessoule
- Univ. Bordeaux, CNRS, Laboratoire de Biogenèse Membranaire, UMR 5200, F-33140 Villenave d'Ornon, France
| | - F Doignon
- Univ. Bordeaux, CNRS, Laboratoire de Biogenèse Membranaire, UMR 5200, F-33140 Villenave d'Ornon, France
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18
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Tunneling nanotubes and related structures: molecular mechanisms of formation and function. Biochem J 2021; 478:3977-3998. [PMID: 34813650 DOI: 10.1042/bcj20210077] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Revised: 10/12/2021] [Accepted: 11/01/2021] [Indexed: 12/13/2022]
Abstract
Tunneling nanotubes (TNTs) are F-actin-based, membrane-enclosed tubular connections between animal cells that transport a variety of cellular cargo. Over the last 15 years since their discovery, TNTs have come to be recognized as key players in normal cell communication and organism development, and are also exploited for the spread of various microbial pathogens and major diseases like cancer and neurodegenerative disorders. TNTs have also been proposed as modalities for disseminating therapeutic drugs between cells. Despite the rapidly expanding and wide-ranging relevance of these structures in both health and disease, there is a glaring dearth of molecular mechanistic knowledge regarding the formation and function of these important but enigmatic structures. A series of fundamental steps are essential for the formation of functional nanotubes. The spatiotemporally controlled and directed modulation of cortical actin dynamics would be required to ensure outward F-actin polymerization. Local plasma membrane deformation to impart negative curvature and membrane addition at a rate commensurate with F-actin polymerization would enable outward TNT elongation. Extrinsic tactic cues, along with cognate intrinsic signaling, would be required to guide and stabilize the elongating TNT towards its intended target, followed by membrane fusion to create a functional TNT. Selected cargoes must be transported between connected cells through the action of molecular motors, before the TNT is retracted or destroyed. This review summarizes the current understanding of the molecular mechanisms regulating these steps, also highlighting areas that deserve future attention.
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19
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Zhu YQ, Qiu L, Liu LL, Luo L, Han XP, Zhai YH, Wang WJ, Ren MZ, Xing YD. Identification and Comprehensive Structural and Functional Analyses of the EXO70 Gene Family in Cotton. Genes (Basel) 2021; 12:genes12101594. [PMID: 34680988 PMCID: PMC8536163 DOI: 10.3390/genes12101594] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Revised: 09/30/2021] [Accepted: 10/02/2021] [Indexed: 11/24/2022] Open
Abstract
The EXO70 gene is a vital component of the exocytosis complex and participates in biological processes ranging from plant cell division to polar growth. There are many EXO70 genes in plants and their functions are extensive, but little is known about the EXO70 gene family in cotton. Here, we analyzed four cotton sequence databases, identified 165 EXO70 genes, and divided them into eight subgroups (EXO70A–EXO70H) based on their phylogenetic relationships. EXO70A had the most exons (≥11), whereas the other seven each had only one or two exons. Hence, EXO70A may have many important functions. The 84 EXO70 genes in Asian and upland cotton were expressed in the roots, stems, leaves, flowers, fibers, and/or ovules. Full-length GhEXO70A1-A cDNA was homologously cloned from upland cotton (Gossypium hirsutum, G. hirsutum). Subcellular analysis revealed that GhEXO70A1-A protein was localized to the plasma membrane. A yeast two-hybrid assay revealed that GhEXO70A1-A interacted with GhEXO84A, GhEXO84B, and GhEXO84C. GhEXO70A1-A silencing significantly altered over 4000 genes and changed several signaling pathways related to metabolism. Thus, the EXO70 gene plays critical roles in the physiological functions of cotton.
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Affiliation(s)
- Ya-Qian Zhu
- Zhengzhou Research Base, State Key Laboratory of Cotton Biology, School of Agricultural Sciences, Zhengzhou University, Zhengzhou 450001, China; (Y.-Q.Z.); (L.Q.); (L.-L.L.); (L.L.); (X.-P.H.); (Y.-H.Z.); (W.-J.W.)
- State Key Laboratory of Cotton Biology, Institute of Cotton Research, Chinese Academy of Agricultural Sciences, Anyang 455000, China
| | - Lu Qiu
- Zhengzhou Research Base, State Key Laboratory of Cotton Biology, School of Agricultural Sciences, Zhengzhou University, Zhengzhou 450001, China; (Y.-Q.Z.); (L.Q.); (L.-L.L.); (L.L.); (X.-P.H.); (Y.-H.Z.); (W.-J.W.)
- School of Life Sciences, Zhengzhou University, Zhengzhou 450001, China
| | - Lu-Lu Liu
- Zhengzhou Research Base, State Key Laboratory of Cotton Biology, School of Agricultural Sciences, Zhengzhou University, Zhengzhou 450001, China; (Y.-Q.Z.); (L.Q.); (L.-L.L.); (L.L.); (X.-P.H.); (Y.-H.Z.); (W.-J.W.)
- State Key Laboratory of Cotton Biology, Institute of Cotton Research, Chinese Academy of Agricultural Sciences, Anyang 455000, China
| | - Lei Luo
- Zhengzhou Research Base, State Key Laboratory of Cotton Biology, School of Agricultural Sciences, Zhengzhou University, Zhengzhou 450001, China; (Y.-Q.Z.); (L.Q.); (L.-L.L.); (L.L.); (X.-P.H.); (Y.-H.Z.); (W.-J.W.)
- State Key Laboratory of Cotton Biology, Institute of Cotton Research, Chinese Academy of Agricultural Sciences, Anyang 455000, China
| | - Xin-Pei Han
- Zhengzhou Research Base, State Key Laboratory of Cotton Biology, School of Agricultural Sciences, Zhengzhou University, Zhengzhou 450001, China; (Y.-Q.Z.); (L.Q.); (L.-L.L.); (L.L.); (X.-P.H.); (Y.-H.Z.); (W.-J.W.)
- State Key Laboratory of Cotton Biology, Institute of Cotton Research, Chinese Academy of Agricultural Sciences, Anyang 455000, China
| | - Yao-Hua Zhai
- Zhengzhou Research Base, State Key Laboratory of Cotton Biology, School of Agricultural Sciences, Zhengzhou University, Zhengzhou 450001, China; (Y.-Q.Z.); (L.Q.); (L.-L.L.); (L.L.); (X.-P.H.); (Y.-H.Z.); (W.-J.W.)
- State Key Laboratory of Cotton Biology, Institute of Cotton Research, Chinese Academy of Agricultural Sciences, Anyang 455000, China
| | - Wen-Jing Wang
- Zhengzhou Research Base, State Key Laboratory of Cotton Biology, School of Agricultural Sciences, Zhengzhou University, Zhengzhou 450001, China; (Y.-Q.Z.); (L.Q.); (L.-L.L.); (L.L.); (X.-P.H.); (Y.-H.Z.); (W.-J.W.)
- State Key Laboratory of Cotton Biology, Institute of Cotton Research, Chinese Academy of Agricultural Sciences, Anyang 455000, China
| | - Mao-Zhi Ren
- State Key Laboratory of Cotton Biology, Institute of Cotton Research, Chinese Academy of Agricultural Sciences, Anyang 455000, China
- Correspondence: (M.-Z.R.); (Y.-D.X.)
| | - Ya-Di Xing
- Zhengzhou Research Base, State Key Laboratory of Cotton Biology, School of Agricultural Sciences, Zhengzhou University, Zhengzhou 450001, China; (Y.-Q.Z.); (L.Q.); (L.-L.L.); (L.L.); (X.-P.H.); (Y.-H.Z.); (W.-J.W.)
- Correspondence: (M.-Z.R.); (Y.-D.X.)
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20
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Abstract
The molecular mechanisms of cellular insulin action have been the focus of much investigation since the discovery of the hormone 100 years ago. Insulin action is impaired in metabolic syndrome, a condition known as insulin resistance. The actions of the hormone are initiated by binding to its receptor on the surface of target cells. The receptor is an α2β2 heterodimer that binds to insulin with high affinity, resulting in the activation of its tyrosine kinase activity. Once activated, the receptor can phosphorylate a number of intracellular substrates that initiate discrete signaling pathways. The tyrosine phosphorylation of some substrates activates phosphatidylinositol-3-kinase (PI3K), which produces polyphosphoinositides that interact with protein kinases, leading to activation of the kinase Akt. Phosphorylation of Shc leads to activation of the Ras/MAP kinase pathway. Phosphorylation of SH2B2 and of Cbl initiates activation of G proteins such as TC10. Activation of Akt and other protein kinases produces phosphorylation of a variety of substrates, including transcription factors, GTPase-activating proteins, and other kinases that control key metabolic events. Among the cellular processes controlled by insulin are vesicle trafficking, activities of metabolic enzymes, transcriptional factors, and degradation of insulin itself. Together these complex processes are coordinated to ensure glucose homeostasis.
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21
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Wang H, Ma ZH, Mao J, Chen BH. Genome-wide identification and expression analysis of the EXO70 gene family in grape ( Vitis vinifera L). PeerJ 2021; 9:e11176. [PMID: 33976971 PMCID: PMC8067907 DOI: 10.7717/peerj.11176] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Accepted: 03/08/2021] [Indexed: 12/14/2022] Open
Abstract
EXO70 is the pivotal protein subunit of exocyst, which has a very crucial role in enhancing the shielding effect of the cell wall, resisting abiotic and hormonal stresses. This experiment aims to identify family members of the EXO70 gene family in grape and predict the characteristics of this gene family, so as to lay the foundation of further exploring the mechanism of resisting abiotic and hormone stresses of VvEXO70s. Therefore, the Vitis vinifera ‘Red Globe’ tube plantlet were used as materials. Bioinformatics was used to inquire VvEXO70 genes family members, gene structure, system evolution, cis-acting elements, subcellular and chromosomal localization, collinearity, selective pressure, codon bias and tissue expression. All of VvEXO70s had the conserved pfam03081 domain which maybe necessary for interacting with other proteins. Microarray analysis suggested that most genes expressed to varying degrees in tendrils, leaves, seeds, buds, roots and stems. Quantitative Real-Time PCR (qRT-PCR) showed that the expression levels of all genes with 5 mM salicylic acid (SA), 0.1 mM methy jasmonate (MeJA), 20% PEG6000 and 4 °C for 24 h were higher than for 12 h. With 20% PEG6000 treatment about 24 h, the relative expression of VvEXO70-02 was significantly up-regulated and 361 times higher than CK. All genes’ relative expression was higher at 12 h than that at 24 h after treatment with 7 mM hydrogen peroxide (H2O2) and 0.1 mM ethylene (ETH). In conclusion, the expression levels of 14 VvEXO70 genes are distinguishing under these treatments, which play an important role in the regulation of anti-stress signals in grape. All of these test results provide a reference for the future research on the potential function analysis and plant breeding of VvEXO70 genes.
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Affiliation(s)
- Han Wang
- Department of Horticulture, Gansu Agricultural University, Lanzhou, China
| | - Zong-Huan Ma
- Department of Horticulture, Gansu Agricultural University, Lanzhou, China
| | - Juan Mao
- Department of Horticulture, Gansu Agricultural University, Lanzhou, China
| | - Bai-Hong Chen
- Department of Horticulture, Gansu Agricultural University, Lanzhou, China
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22
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Van Bergen NJ, Ahmed SM, Collins F, Cowley M, Vetro A, Dale RC, Hock DH, de Caestecker C, Menezes M, Massey S, Ho G, Pisano T, Glover S, Gusman J, Stroud DA, Dinger M, Guerrini R, Macara IG, Christodoulou J. Mutations in the exocyst component EXOC2 cause severe defects in human brain development. J Exp Med 2021; 217:151928. [PMID: 32639540 PMCID: PMC7537385 DOI: 10.1084/jem.20192040] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Revised: 02/03/2020] [Accepted: 04/03/2020] [Indexed: 12/30/2022] Open
Abstract
The exocyst, an octameric protein complex, is an essential component of the membrane transport machinery required for tethering and fusion of vesicles at the plasma membrane. We report pathogenic variants in an exocyst subunit, EXOC2 (Sec5). Affected individuals have severe developmental delay, dysmorphism, and brain abnormalities; variability associated with epilepsy; and poor motor skills. Family 1 had two offspring with a homozygous truncating variant in EXOC2 that leads to nonsense-mediated decay of EXOC2 transcript, a severe reduction in exocytosis and vesicle fusion, and undetectable levels of EXOC2 protein. The patient from Family 2 had a milder clinical phenotype and reduced exocytosis. Cells from both patients showed defective Arl13b localization to the primary cilium. The discovery of mutations that partially disable exocyst function provides valuable insight into this essential protein complex in neural development. Since EXOC2 and other exocyst complex subunits are critical to neuronal function, our findings suggest that EXOC2 variants are the cause of the patients’ neurological disorders.
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Affiliation(s)
- Nicole J Van Bergen
- Brain and Mitochondrial Research Group, Murdoch Children's Research Institute, Royal Children's Hospital, Melbourne, Victoria, Australia.,Department of Paediatrics, University of Melbourne, Melbourne, Victoria, Australia
| | - Syed Mukhtar Ahmed
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN
| | - Felicity Collins
- Western Sydney Genetics Program, Children's Hospital at Westmead, Sydney, New South Wales, Australia.,Medical Genomics Department, Royal Prince Alfred Hospital, Sydney, New South Wales, Australia
| | - Mark Cowley
- Kinghorn Centre for Clinical Genomics, Garvan Institute of Medical Research, Sydney, New South Wales, Australia.,St Vincent's Clinical School, University of New South Wales Sydney, Sydney, New South Wales, Australia.,Children's Cancer Institute, Kensington, New South Wales, Australia
| | - Annalisa Vetro
- Pediatric Neurology, Neurogenetics and Neurobiology Unit and Laboratories, Meyer Children's Hospital, University of Florence, Florence, Italy
| | - Russell C Dale
- Department of Paediatric Neurology, The Children's Hospital at Westmead, Sydney, New South Wales, Australia.,Kids Neuroscience Centre, Faculty of Medicine and Health, The University of Sydney, Sydney, New South Wales, Australia
| | - Daniella H Hock
- Department of Biochemistry and Molecular Biology and The Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Parkville, Victoria, Australia
| | - Christian de Caestecker
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN
| | - Minal Menezes
- Kids Research, The Children's Hospital at Westmead, Sydney, New South Wales, Australia
| | - Sean Massey
- Brain and Mitochondrial Research Group, Murdoch Children's Research Institute, Royal Children's Hospital, Melbourne, Victoria, Australia
| | - Gladys Ho
- Western Sydney Genetics Program, Children's Hospital at Westmead, Sydney, New South Wales, Australia
| | - Tiziana Pisano
- Pediatric Neurology, Neurogenetics and Neurobiology Unit and Laboratories, Meyer Children's Hospital, University of Florence, Florence, Italy
| | - Seana Glover
- Brain and Mitochondrial Research Group, Murdoch Children's Research Institute, Royal Children's Hospital, Melbourne, Victoria, Australia.,Department of Paediatrics, University of Melbourne, Melbourne, Victoria, Australia
| | - Jovanka Gusman
- Brain and Mitochondrial Research Group, Murdoch Children's Research Institute, Royal Children's Hospital, Melbourne, Victoria, Australia.,Department of Paediatrics, University of Melbourne, Melbourne, Victoria, Australia
| | - David A Stroud
- Department of Biochemistry and Molecular Biology and The Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Parkville, Victoria, Australia
| | - Marcel Dinger
- Kinghorn Centre for Clinical Genomics, Garvan Institute of Medical Research, Sydney, New South Wales, Australia.,School of Biotechnology and Biomolecular Sciences, University of New South Wales, Kensington Campus, Sydney, New South Wales, Australia
| | - Renzo Guerrini
- Pediatric Neurology, Neurogenetics and Neurobiology Unit and Laboratories, Meyer Children's Hospital, University of Florence, Florence, Italy
| | - Ian G Macara
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN
| | - John Christodoulou
- Brain and Mitochondrial Research Group, Murdoch Children's Research Institute, Royal Children's Hospital, Melbourne, Victoria, Australia.,Department of Paediatrics, University of Melbourne, Melbourne, Victoria, Australia.,Victorian Clinical Genetics Services, Royal Children's Hospital, Parkville, Victoria, Australia
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23
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Saccomanno A, Potocký M, Pejchar P, Hála M, Shikata H, Schwechheimer C, Žárský V. Regulation of Exocyst Function in Pollen Tube Growth by Phosphorylation of Exocyst Subunit EXO70C2. FRONTIERS IN PLANT SCIENCE 2021; 11:609600. [PMID: 33519861 PMCID: PMC7840542 DOI: 10.3389/fpls.2020.609600] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/23/2020] [Accepted: 12/22/2020] [Indexed: 06/12/2023]
Abstract
Exocyst is a heterooctameric protein complex crucial for the tethering of secretory vesicles to the plasma membrane during exocytosis. Compared to other eukaryotes, exocyst subunit EXO70 is represented by many isoforms in land plants whose cell biological and biological roles, as well as modes of regulation remain largely unknown. Here, we present data on the phospho-regulation of exocyst isoform EXO70C2, which we previously identified as a putative negative regulator of exocyst function in pollen tube growth. A comprehensive phosphoproteomic analysis revealed phosphorylation of EXO70C2 at multiple sites. We have now performed localization and functional studies of phospho-dead and phospho-mimetic variants of Arabidopsis EXO70C2 in transiently transformed tobacco pollen tubes and stably transformed Arabidopsis wild type and exo70C2 mutant plants. Our data reveal a dose-dependent effect of AtEXO70C2 overexpression on pollen tube growth rate and cellular architecture. We show that changes of the AtEXO70C2 phosphorylation status lead to distinct outcomes in wild type and exo70c2 mutant cells, suggesting a complex regulatory pattern. On the other side, phosphorylation does not affect the cytoplasmic localization of AtEXO70C2 or its interaction with putative secretion inhibitor ROH1 in the yeast two-hybrid system.
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Affiliation(s)
- Antonietta Saccomanno
- Laboratory of Cell Biology, Institute of Experimental Botany, Czech Academy of Sciences, Prague, Czechia
- Department of Experimental Plant Biology, Faculty of Science, Charles University, Prague, Czechia
| | - Martin Potocký
- Laboratory of Cell Biology, Institute of Experimental Botany, Czech Academy of Sciences, Prague, Czechia
- Department of Experimental Plant Biology, Faculty of Science, Charles University, Prague, Czechia
| | - Přemysl Pejchar
- Laboratory of Cell Biology, Institute of Experimental Botany, Czech Academy of Sciences, Prague, Czechia
- Department of Experimental Plant Biology, Faculty of Science, Charles University, Prague, Czechia
| | - Michal Hála
- Laboratory of Cell Biology, Institute of Experimental Botany, Czech Academy of Sciences, Prague, Czechia
- Department of Experimental Plant Biology, Faculty of Science, Charles University, Prague, Czechia
| | - Hiromasa Shikata
- Plant Systems Biology, Technische Universität München, Freising, Germany
| | | | - Viktor Žárský
- Laboratory of Cell Biology, Institute of Experimental Botany, Czech Academy of Sciences, Prague, Czechia
- Department of Experimental Plant Biology, Faculty of Science, Charles University, Prague, Czechia
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24
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Rossi G, Lepore D, Kenner L, Czuchra AB, Plooster M, Frost A, Munson M, Brennwald P. Exocyst structural changes associated with activation of tethering downstream of Rho/Cdc42 GTPases. J Cell Biol 2020; 219:133563. [PMID: 31904797 PMCID: PMC7041683 DOI: 10.1083/jcb.201904161] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2019] [Revised: 07/26/2019] [Accepted: 11/19/2019] [Indexed: 12/16/2022] Open
Abstract
The exocyst complex plays a critical role in determining both temporal and spatial dynamics of exocytic vesicle tethering and fusion with the plasma membrane. However, the mechanism by which the exocyst functions and how it is regulated remain poorly understood. Here we describe a novel biochemical assay for the examination of exocyst function in vesicle tethering. Importantly, the assay is stimulated by gain-of-function mutations in the Exo70 component of the exocyst, selected for their ability to bypass Rho/Cdc42 activation in vivo. Single-particle electron microscopy and 3D reconstructions of negatively stained exocyst complexes reveal a structural change in the mutant exocyst that exposes a binding site for the v-SNARE. We demonstrate a v-SNARE requirement in our tethering assay and increased v-SNARE binding to exocyst gain-of-function complexes. Together, these data suggest an allosteric mechanism for activation involving a conformational change in one subunit of the complex, which is relayed through the complex to regulate its biochemical activity in vitro, as well as overall function in vivo.
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Affiliation(s)
- Guendalina Rossi
- Department of Cell Biology and Physiology, University of North Carolina School of Medicine, Chapel Hill, NC
| | - Dante Lepore
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA
| | - Lillian Kenner
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA
| | - Alexander B Czuchra
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA
| | - Melissa Plooster
- Department of Cell Biology and Physiology, University of North Carolina School of Medicine, Chapel Hill, NC
| | - Adam Frost
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA.,Chan Zuckerberg Biohub, University of California, San Francisco, San Francisco, CA.,California Quantitative Biosciences Institute, University of California, San Francisco, San Francisco, CA
| | - Mary Munson
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA
| | - Patrick Brennwald
- Department of Cell Biology and Physiology, University of North Carolina School of Medicine, Chapel Hill, NC
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25
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Roles of the PH, coiled-coil and SAM domains of the yeast polarity protein Boi2 in polarity-site localization and function in polarized growth. Curr Genet 2020; 66:1101-1115. [PMID: 32656574 DOI: 10.1007/s00294-020-01093-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Revised: 06/29/2020] [Accepted: 07/03/2020] [Indexed: 10/23/2022]
Abstract
Boi1 and Boi2 are paralogous proteins essential for bud formation in budding yeast. So far, the domains that target Boi1/Boi2 to the polarity sites and function in bud formation are not well understood. Here, we report that a coiled-coil domain of Boi2 cooperates with the adjacent PH domain to confer Boi2's bud-cortex localization and major function in cell growth. The PH domain portion of the PH-CC bi-domain interacts with the Rho GTPases Cdc42 and Rho3 and both interactions are independent of the GTP/GDP-bound state of each GTPase. Interestingly, high-copy RHO3 and BOI2 but not CDC42 suppressed the growth defect of RGA1-C538 overexpression and the sec15-1 mutant and this BOI2 function depends on RHO3, suggesting that Boi2 may function in the Rho3 pathway. The SAM domain of Boi2 plays an essential role in high-copy suppression of the two mutants as well as in the early bud-neck localization of Boi2. The SAM domain and the CC domain also interact homotypically. They are likely involved in the formation of Boi2-containing protein complex. Our results provide new insights in the localization and function of Boi2 and highlight the importance of the PH-CC bi-domain and the SAM domain in Boi2's localization and function.
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26
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Pečenková T, Potocká A, Potocký M, Ortmannová J, Drs M, Janková Drdová E, Pejchar P, Synek L, Soukupová H, Žárský V, Cvrčková F. Redundant and Diversified Roles Among Selected Arabidopsis thaliana EXO70 Paralogs During Biotic Stress Responses. FRONTIERS IN PLANT SCIENCE 2020; 11:960. [PMID: 32676093 PMCID: PMC7333677 DOI: 10.3389/fpls.2020.00960] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2020] [Accepted: 06/11/2020] [Indexed: 05/28/2023]
Abstract
The heterooctameric vesicle-tethering complex exocyst is important for plant development, growth, and immunity. Multiple paralogs exist for most subunits of this complex; especially the membrane-interacting subunit EXO70 underwent extensive amplification in land plants, suggesting functional specialization. Despite this specialization, most Arabidopsis exo70 mutants are viable and free of developmental defects, probably as a consequence of redundancy among isoforms. Our in silico data-mining and modeling analysis, corroborated by transcriptomic experiments, pinpointed several EXO70 paralogs to be involved in plant biotic interactions. We therefore tested corresponding single and selected double mutant combinations (for paralogs EXO70A1, B1, B2, H1, E1, and F1) in their two biologically distinct responses to Pseudomonas syringae, root hair growth stimulation and general plant susceptibility. A shift in defense responses toward either increased or decreased sensitivity was found in several double mutants compared to wild type plants or corresponding single mutants, strongly indicating both additive and compensatory effects of exo70 mutations. In addition, our experiments confirm the lipid-binding capacity of selected EXO70s, however, without the clear relatedness to predicted C-terminal lipid-binding motifs. Our analysis uncovers that there is less of functional redundancy among isoforms than we could suppose from whole sequence phylogeny and that even paralogs with overlapping expression pattern and similar membrane-binding capacity appear to have exclusive roles in plant development and biotic interactions.
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Affiliation(s)
- Tamara Pečenková
- Institute of Experimental Botany, CAS, Prague, Czechia
- Department of Experimental Plant Biology, Faculty of Science, Charles University, Prague, Czechia
| | | | - Martin Potocký
- Institute of Experimental Botany, CAS, Prague, Czechia
- Department of Experimental Plant Biology, Faculty of Science, Charles University, Prague, Czechia
| | | | - Matěj Drs
- Institute of Experimental Botany, CAS, Prague, Czechia
- Department of Experimental Plant Biology, Faculty of Science, Charles University, Prague, Czechia
| | - Edita Janková Drdová
- Institute of Experimental Botany, CAS, Prague, Czechia
- Department of Experimental Plant Biology, Faculty of Science, Charles University, Prague, Czechia
| | - Přemysl Pejchar
- Institute of Experimental Botany, CAS, Prague, Czechia
- Department of Experimental Plant Biology, Faculty of Science, Charles University, Prague, Czechia
| | - Lukáš Synek
- Institute of Experimental Botany, CAS, Prague, Czechia
| | | | - Viktor Žárský
- Institute of Experimental Botany, CAS, Prague, Czechia
- Department of Experimental Plant Biology, Faculty of Science, Charles University, Prague, Czechia
| | - Fatima Cvrčková
- Department of Experimental Plant Biology, Faculty of Science, Charles University, Prague, Czechia
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27
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Ganesan SJ, Feyder MJ, Chemmama IE, Fang F, Rout MP, Chait BT, Shi Y, Munson M, Sali A. Integrative structure and function of the yeast exocyst complex. Protein Sci 2020; 29:1486-1501. [PMID: 32239688 DOI: 10.1002/pro.3863] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Revised: 03/25/2020] [Accepted: 03/27/2020] [Indexed: 12/13/2022]
Abstract
Exocyst is an evolutionarily conserved hetero-octameric tethering complex that plays a variety of roles in membrane trafficking, including exocytosis, endocytosis, autophagy, cell polarization, cytokinesis, pathogen invasion, and metastasis. Exocyst serves as a platform for interactions between the Rab, Rho, and Ral small GTPases, SNARE proteins, and Sec1/Munc18 regulators that coordinate spatial and temporal fidelity of membrane fusion. However, its mechanism is poorly described at the molecular level. Here, we determine the molecular architecture of the yeast exocyst complex by an integrative approach, based on a 3D density map from negative-stain electron microscopy (EM) at ~16 Å resolution, 434 disuccinimidyl suberate and 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride cross-links from chemical-crosslinking mass spectrometry, and partial atomic models of the eight subunits. The integrative structure is validated by a previously determined cryo-EM structure, cross-links, and distances from in vivo fluorescence microscopy. Our subunit configuration is consistent with the cryo-EM structure, except for Sec5. While not observed in the cryo-EM map, the integrative model localizes the N-terminal half of Sec3 near the Sec6 subunit. Limited proteolysis experiments suggest that the conformation of Exo70 is dynamic, which may have functional implications for SNARE and membrane interactions. This study illustrates how integrative modeling based on varied low-resolution structural data can inform biologically relevant hypotheses, even in the absence of high-resolution data.
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Affiliation(s)
- Sai J Ganesan
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, California, USA.,Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, California, USA
| | - Michael J Feyder
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts, USA
| | - Ilan E Chemmama
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, California, USA.,Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, California, USA
| | - Fei Fang
- Department of Cell Biology, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Michael P Rout
- Laboratory of Cellular and Structural Biology, The Rockefeller University, New York, New York, USA
| | - Brian T Chait
- Laboratory of Mass Spectrometry and Gaseous Ion Chemistry, The Rockefeller University, New York, New York, USA
| | - Yi Shi
- Department of Cell Biology, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Mary Munson
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts, USA
| | - Andrej Sali
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, California, USA.,Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, California, USA
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28
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Glomb O, Wu Y, Rieger L, Rüthnick D, Mulaw MA, Johnsson N. The cell polarity proteins Boi1 and Boi2 direct an actin nucleation complex to sites of exocytosis in Saccharomyces cerevisiae. J Cell Sci 2020; 133:jcs.237982. [PMID: 31964708 DOI: 10.1242/jcs.237982] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2019] [Accepted: 12/19/2019] [Indexed: 01/13/2023] Open
Abstract
Owing to the local enrichment of factors that influence its dynamics and organization, the actin cytoskeleton displays different shapes and functions within the same cell. In yeast cells, post-Golgi vesicles ride on long actin cables to the bud tip. The proteins Boi1 and Boi2 (Boi1/2) participate in tethering and docking these vesicles to the plasma membrane. Here, we show in Saccharomyces cerevisiae that Boi1/2 also recruit nucleation and elongation factors to form actin filaments at sites of exocytosis. Disrupting the connection between Boi1/2 and the nucleation factor Bud6 impairs filament formation, reduces the directed movement of the vesicles to the tip and shortens the vesicles' tethering time at the cortex. Transplanting Boi1 from the bud tip to the peroxisomal membrane partially redirects the actin cytoskeleton and the vesicular flow towards the peroxisome, and creates an alternative, rudimentary vesicle-docking zone. We conclude that Boi1/2, through interactions with Bud6 and Bni1, induce the formation of a cortical actin structure that receives and aligns incoming vesicles before fusion with the membrane.
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Affiliation(s)
- Oliver Glomb
- Institute of Molecular Genetics and Cell Biology, Department of Biology, Ulm University, James-Franck-Ring N27, D-89081 Ulm, Germany
| | - Yehui Wu
- Institute of Molecular Genetics and Cell Biology, Department of Biology, Ulm University, James-Franck-Ring N27, D-89081 Ulm, Germany
| | - Lucia Rieger
- Institute of Molecular Genetics and Cell Biology, Department of Biology, Ulm University, James-Franck-Ring N27, D-89081 Ulm, Germany
| | - Diana Rüthnick
- ZMBH, University of Heidelberg, Im Neuenheimer Feld 282, D-69120 Heidelberg, Germany
| | - Medhanie A Mulaw
- Comprehensive Cancer Center Ulm, Institute of Experimental Cancer Research, Ulm University, James-Franck-Ring N27, D-89081 Ulm, Germany
| | - Nils Johnsson
- Institute of Molecular Genetics and Cell Biology, Department of Biology, Ulm University, James-Franck-Ring N27, D-89081 Ulm, Germany
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29
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Peng L, Yu Q, Wei H, Zhu N, Ren T, Liang C, Xu J, Tian L, Li M. The TRP Ca2+ channel Yvc1 regulates hyphal reactive oxygen species gradient for maintenance of polarized growth in Candida albicans. Fungal Genet Biol 2019; 133:103282. [DOI: 10.1016/j.fgb.2019.103282] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2019] [Revised: 10/14/2019] [Accepted: 10/14/2019] [Indexed: 11/26/2022]
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30
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Guan W, Feng J, Wang R, Ma Z, Wang W, Wang K, Zhu T. Functional analysis of the exocyst subunit BcExo70 in Botrytis cinerea. Curr Genet 2019; 66:85-95. [PMID: 31183512 DOI: 10.1007/s00294-019-01002-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2019] [Revised: 05/30/2019] [Accepted: 06/01/2019] [Indexed: 01/27/2023]
Abstract
Botrytis cinerea is one of the most important saprophytic plant pathogenic fungi. The exocyst complex and exocytosis was demonstrated to be involved in fungal development and plant infection. Here, we investigated the function of an exocyst subunit gene Bcexo70 in B. cinerea. The results show that knockout of the Bcexo70 gene significantly reduced the fungal growth and hindered the production of conidia and sclerotia. The Bcexo70 deletion strains showed a severe decrease in virulence toward tomato leaves and reduced secretion of cell wall-degrading enzyme. Confocal and electronic microscopic observation showed that the vesicles in the Bcexo70 mutants were enlarged and scattered in the cytoplasm compared to the regular distribution in the hyphal tip in wild-type strain. This study showed that the exocyst gene Bcexo70 is crucial for fungal growth, conidiation and pathogenicity in B. cinerea.
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Affiliation(s)
- Wenqing Guan
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, Zhejiang, China
| | - Juan Feng
- Taizhou Vocational College of Science and Technology, Taizhou, Zhejiang, China
| | - Rongxia Wang
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, Zhejiang, China
| | - Zhiwei Ma
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, Zhejiang, China
| | - Weixia Wang
- State Key Lab of Rice Biology, China National Rice Research Institute, Hangzhou, Zhejiang, China.
| | - Kun Wang
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, Zhejiang, China.
| | - Tingheng Zhu
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, Zhejiang, China.
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31
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Liu Y, Zhang T, Sun D, Luo G. The Cdc42 effectors Gic1 and Gic2 regulate polarized post-Golgi secretion. Cell Biosci 2019; 9:33. [PMID: 30988896 PMCID: PMC6449940 DOI: 10.1186/s13578-019-0295-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Accepted: 03/29/2019] [Indexed: 11/10/2022] Open
Abstract
Background Cell polarity refers to spatial difference in morphology, structure, and function within different parts of a single cell, which plays important roles in a wide range of cellular processes. In eukaryotic cells, the small GTPase Cdc42 and phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P2) are critical components for cell polarity and required for polarized exocytosis and cell growth. Previous data showed that the GTPase-interacting components, Gic1 and Gic2, control cell polarity through its binding with Cdc42 and PtdIns(4,5)P2 in the plasma membrane in budding yeast. However, whether the Gic proteins regulate polarized exocytosis is unknown. Results In this study, we found that Gic2 co-immunoprecipitates with the exocyst complex, suggesting Gic proteins may be involved in exocytosis. Although we could not show the direct interaction between Gic2 and exocyst, we found gic1Δgic2Δ are synthetically sick with sec3ΔN. We demonstrated that Gic1 and Gic2 are required for polarized exocytosis in a yeast strain harboring the N-terminal domain deletion of Sec3, which is also known as an effector of Cdc42 GTPase. Gic proteins are required for polarized localization of exocyst, growth, and efficient secretion in sec3∆N mutant. In addition, we found that the N-terminal domain of both Gic2 and Sec3 share the similar binding sites of Cdc42. Surprisingly, not all the Sec3/Gic binding deficient cdc42 mutants displayed defects of growth and secretion, indicating that disruption of Cdc42 binding with Gic proteins and Sec3 does not necessarily show secretion defects in cdc42 mutants. Conclusions We conclude that Gic1/2 and Sec3 act in parallel to regulate polarized post-Golgi secretion, but this regulation is not solely controlled by their upstream factor Cdc42. Considering that N-terminal domain of Gic2 and Sec3 can bind to both Cdc42 and PtdIns(4,5)P2, the regulation of Gic protein and Sec3 on polarized secretion may also be controlled by PtdIns(4,5)P2. Further experiments need to be performed to test this hypothesis. Our findings provide important clues for understanding the molecular mechanism of cell polarity establishment in eukaryotic cells. Electronic supplementary material The online version of this article (10.1186/s13578-019-0295-x) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Ying Liu
- 1Department of Biochemistry and Molecular Biology, China Medical University, Shenyang, 110122 China
| | - Tianrui Zhang
- 1Department of Biochemistry and Molecular Biology, China Medical University, Shenyang, 110122 China
| | - Dong Sun
- 2Institute of Translational Medicine, China Medical University, Shenyang, 110122 China
| | - Guangzuo Luo
- 2Institute of Translational Medicine, China Medical University, Shenyang, 110122 China
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32
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Ahmed SM, Nishida-Fukuda H, Li Y, McDonald WH, Gradinaru CC, Macara IG. Exocyst dynamics during vesicle tethering and fusion. Nat Commun 2018; 9:5140. [PMID: 30510181 PMCID: PMC6277416 DOI: 10.1038/s41467-018-07467-5] [Citation(s) in RCA: 77] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2018] [Accepted: 11/01/2018] [Indexed: 11/15/2022] Open
Abstract
The exocyst is a conserved octameric complex that tethers exocytic vesicles to the plasma membrane prior to fusion. Exocyst assembly and delivery mechanisms remain unclear, especially in mammalian cells. Here we tagged multiple endogenous exocyst subunits with sfGFP or Halo using Cas9 gene-editing, to create single and double knock-in lines of mammary epithelial cells, and interrogated exocyst dynamics by high-speed imaging and correlation spectroscopy. We discovered that mammalian exocyst is comprised of tetrameric subcomplexes that can associate independently with vesicles and plasma membrane and are in dynamic equilibrium with octamer and monomers. Membrane arrival times are similar for subunits and vesicles, but with a small delay (~80msec) between subcomplexes. Departure of SEC3 occurs prior to fusion, whereas other subunits depart just after fusion. About 9 exocyst complexes are associated per vesicle. These data reveal the mammalian exocyst as a remarkably dynamic two-part complex and provide important insights into assembly/disassembly mechanisms. Exocyst complex tethers vesicles to plasma membranes, but assembly mechanisms remain unclear. Here, the authors use Cas9 gene editing to tag exocyst components in epithelial cells, and find that exocyst subcomplexes are recruited to membranes independently, but are both needed for vesicle fusion.
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Affiliation(s)
- Syed Mukhtar Ahmed
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN, 37240, USA.
| | - Hisayo Nishida-Fukuda
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN, 37240, USA.,Department of Biochemistry and Molecular Genetics, Ehime University Graduate School of Medicine, Toon, Ehime, 7910295, Japan.,Department of Hepato-Biliary-Pancreatic and Breast Surgery, Ehime University Graduate School of Medicine, Toon, Ehime, 7910295, Japan.,Department of Genome Editing, Institute of Biomedical Sciences, Kansai Medical University, Hirakata, 5731010, Japan
| | - Yuchong Li
- Department of Physics, University of Toronto, Toronto, ON, M5S 1A7, Canada.,Department of Chemical & Physical Sciences, University of Toronto Mississauga, Mississauga, ON, L5L 1C6, Canada
| | - W Hayes McDonald
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN, 37240, USA
| | - Claudiu C Gradinaru
- Department of Physics, University of Toronto, Toronto, ON, M5S 1A7, Canada.,Department of Chemical & Physical Sciences, University of Toronto Mississauga, Mississauga, ON, L5L 1C6, Canada
| | - Ian G Macara
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN, 37240, USA.
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33
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Moran KD, Kang H, Araujo AV, Zyla TR, Saito K, Tsygankov D, Lew DJ. Cell-cycle control of cell polarity in yeast. J Cell Biol 2018; 218:171-189. [PMID: 30459262 PMCID: PMC6314536 DOI: 10.1083/jcb.201806196] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2018] [Revised: 09/21/2018] [Accepted: 10/18/2018] [Indexed: 11/30/2022] Open
Abstract
In Saccharomyces cerevisiae, polarization of Cdc42 is regulated by the cell cycle, but the regulatory mechanisms are not well understood. Moran et al. show that G1 cyclin–dependent kinase activity enables localization of a subset of Cdc42 effectors to sites enriched for Cdc42. In many cells, morphogenetic events are coordinated with the cell cycle by cyclin-dependent kinases (CDKs). For example, many mammalian cells display extended morphologies during interphase but round up into more spherical shapes during mitosis (high CDK activity) and constrict a furrow during cytokinesis (low CDK activity). In the budding yeast Saccharomyces cerevisiae, bud formation reproducibly initiates near the G1/S transition and requires activation of CDKs at a point called “start” in G1. Previous work suggested that CDKs acted by controlling the ability of cells to polarize Cdc42, a conserved Rho-family GTPase that regulates cell polarity and the actin cytoskeleton in many systems. However, we report that yeast daughter cells can polarize Cdc42 before CDK activation at start. This polarization operates via a positive feedback loop mediated by the Cdc42 effector Ste20. We further identify a major and novel locus of CDK action downstream of Cdc42 polarization, affecting the ability of several other Cdc42 effectors to localize to the polarity site.
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Affiliation(s)
- Kyle D Moran
- Department of Pharmacology and Cancer Biology, Duke University, Durham, NC
| | - Hui Kang
- Department of Pharmacology and Cancer Biology, Duke University, Durham, NC
| | - Ana V Araujo
- Department of Pharmacology and Cancer Biology, Duke University, Durham, NC
| | - Trevin R Zyla
- Department of Pharmacology and Cancer Biology, Duke University, Durham, NC
| | - Koji Saito
- Department of Biosciences, School of Science, Kitasato University, Kitasato, Sagamihara, Kanagawa, Japan
| | - Denis Tsygankov
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University School of Medicine, Atlanta, GA
| | - Daniel J Lew
- Department of Pharmacology and Cancer Biology, Duke University, Durham, NC
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34
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Lepore DM, Martínez-Núñez L, Munson M. Exposing the Elusive Exocyst Structure. Trends Biochem Sci 2018; 43:714-725. [PMID: 30055895 PMCID: PMC6108956 DOI: 10.1016/j.tibs.2018.06.012] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2018] [Revised: 06/18/2018] [Accepted: 06/29/2018] [Indexed: 11/18/2022]
Abstract
A major challenge for a molecular understanding of membrane trafficking has been the elucidation of high-resolution structures of large, multisubunit tethering complexes that spatially and temporally control intracellular membrane fusion. Exocyst is a large hetero-octameric protein complex proposed to tether secretory vesicles at the plasma membrane to provide quality control of soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE)-mediated membrane fusion. Breakthroughs in methodologies, including sample preparation, biochemical characterization, fluorescence microscopy, and single-particle cryoelectron microscopy, are providing critical insights into the structure and function of the exocyst. These studies now pose more questions than answers for understanding fundamental functional mechanisms, and they open wide the door for future studies to elucidate interactions with protein and membrane partners, potential conformational changes, and molecular insights into tethering reactions.
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Affiliation(s)
- Dante M Lepore
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, 364 Plantation Street, Worcester, MA 01605, USA
| | - Leonora Martínez-Núñez
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, 364 Plantation Street, Worcester, MA 01605, USA
| | - Mary Munson
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, 364 Plantation Street, Worcester, MA 01605, USA.
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35
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Rossi G, Watson K, Kennedy W, Brennwald P. The tomosyn homologue, Sro7, is a direct effector of the Rab GTPase, Sec4, in post-Golgi vesicle tethering. Mol Biol Cell 2018; 29:1476-1486. [PMID: 29668350 PMCID: PMC6014100 DOI: 10.1091/mbc.e18-02-0138] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
The tomosyn/Sro7 family is thought to play an important role in cell surface trafficking both as an effector of Rab family GTPases and as a regulator of plasma-membrane SNARE function. Recent work has determined the binding site of GTP-bound Sec4 on Sro7. Here we examine the effect of mutations in Sro7 that block Sec4 binding in determining the role of this interaction in Sro7 function. Using an in vitro vesicle:vesicle tethering assay, we find that most of Sro7's ability to tether vesicles is blocked by mutations that disrupt binding to Sec4-GTP. Similarly, genetic analysis demonstrates that the interaction with Sec4 is important for most of Sro7's functions in vivo. The interaction of Sro7 with Sec4 appears to be particularly important when exocyst function is compromised. This provides strong evidence that Sro7 and the exocyst act as dual effector pathways downstream of Sec4. We also demonstrate that Sro7 tethering requires the presence of Sec4 on both opposing membranes and that homo-oligomerization of Sro7 occurs during vesicle tethering. This suggests a simple model for Sro7 function as a Rab effector in tethering post-Golgi vesicles to the plasma membrane in a pathway parallel to that of the exocyst complex.
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Affiliation(s)
- Guendalina Rossi
- Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
| | - Kelly Watson
- Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
| | - Wade Kennedy
- Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
| | - Patrick Brennwald
- Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
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36
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Kulich I, Vojtíková Z, Sabol P, Ortmannová J, Neděla V, Tihlaříková E, Žárský V. Exocyst Subunit EXO70H4 Has a Specific Role in Callose Synthase Secretion and Silica Accumulation. PLANT PHYSIOLOGY 2018; 176:2040-2051. [PMID: 29301954 PMCID: PMC5841730 DOI: 10.1104/pp.17.01693] [Citation(s) in RCA: 62] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2017] [Accepted: 01/02/2018] [Indexed: 05/20/2023]
Abstract
Biogenesis of the plant secondary cell wall involves many important aspects, such as phenolic compound deposition and often silica encrustation. Previously, we demonstrated the importance of the exocyst subunit EXO70H4 for biogenesis of the trichome secondary cell wall, namely for deposition of the autofluorescent and callose-rich cell wall layer. Here, we reveal that EXO70H4-driven cell wall biogenesis is constitutively active in the mature trichome, but also can be activated elsewhere upon pathogen attack, giving this study a broader significance with an overlap into phytopathology. To address the specificity of EXO70H4 among the EXO70 family, we complemented the exo70H4-1 mutant by 18 different Arabidopsis (Arabidopsis thaliana) EXO70 paralogs subcloned under the EXO70H4 promoter. Only EXO70H4 had the capacity to rescue the exo70H4-1 trichome phenotype. Callose deposition phenotype of exo70H4-1 mutant is caused by impaired secretion of PMR4, a callose synthase responsible for the synthesis of callose in the trichome. PMR4 colocalizes with EXO70H4 on plasma membrane microdomains that do not develop in the exo70H4-1 mutant. Using energy-dispersive x-ray microanalysis, we show that both EXO70H4- and PMR4-dependent callose deposition in the trichome are essential for cell wall silicification.
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Affiliation(s)
- Ivan Kulich
- Department of Experimental Plant Biology, Faculty of Sciences, Charles University, Prague, Czech Republic
| | - Zdeňka Vojtíková
- Department of Experimental Plant Biology, Faculty of Sciences, Charles University, Prague, Czech Republic
| | - Peter Sabol
- Department of Experimental Plant Biology, Faculty of Sciences, Charles University, Prague, Czech Republic
| | - Jitka Ortmannová
- Department of Experimental Plant Biology, Faculty of Sciences, Charles University, Prague, Czech Republic
- Institute of Experimental Botany, Academy of Sciences of the Czech Republic, Prague, Czech Republic
| | - Vilém Neděla
- Institute of Scientific Instruments of the Academy of Sciences of the Czech Republic, Brno, Czech Republic
| | - Eva Tihlaříková
- Institute of Scientific Instruments of the Academy of Sciences of the Czech Republic, Brno, Czech Republic
| | - Viktor Žárský
- Department of Experimental Plant Biology, Faculty of Sciences, Charles University, Prague, Czech Republic
- Institute of Experimental Botany, Academy of Sciences of the Czech Republic, Prague, Czech Republic
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37
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Polgar N, Fogelgren B. Regulation of Cell Polarity by Exocyst-Mediated Trafficking. Cold Spring Harb Perspect Biol 2018; 10:cshperspect.a031401. [PMID: 28264817 DOI: 10.1101/cshperspect.a031401] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
One requirement for establishing polarity within a cell is the asymmetric trafficking of intracellular vesicles to the plasma membrane. This tightly regulated process creates spatial and temporal differences in both plasma membrane composition and the membrane-associated proteome. Asymmetric membrane trafficking is also a critical mechanism to regulate cell differentiation, signaling, and physiology. Many eukaryotic cell types use the eight-protein exocyst complex to orchestrate polarized vesicle trafficking to certain membrane locales. Members of the exocyst were originally discovered in yeast while screening for proteins required for the delivery of secretory vesicles to the budding daughter cell. The same eight exocyst genes are conserved in mammals, in which the specifics of exocyst-mediated trafficking are highly cell-type-dependent. Some exocyst members bind to certain Rab GTPases on intracellular vesicles, whereas others localize to the plasma membrane at the site of exocytosis. Assembly of the exocyst holocomplex is responsible for tethering these vesicles to the plasma membrane before their soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE)-mediated exocytosis. In this review, we will focus on the role and regulation of the exocyst complex in targeted vesicular trafficking as related to the establishment and maintenance of cellular polarity. We will contrast exocyst function in apicobasal epithelial polarity versus front-back mesenchymal polarity, and the dynamic regulation of exocyst-mediated trafficking during cell phenotype transitions.
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Affiliation(s)
- Noemi Polgar
- Department of Anatomy, Biochemistry and Physiology, John A. Burns School of Medicine, University of Hawaii at Manoa, Honolulu, Hawaii 96813
| | - Ben Fogelgren
- Department of Anatomy, Biochemistry and Physiology, John A. Burns School of Medicine, University of Hawaii at Manoa, Honolulu, Hawaii 96813
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38
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Abstract
Polarized exocytosis is generally considered as the multistep vesicular trafficking process in which membrane-bounded carriers are transported from the Golgi or endosomal compartments to specific sites of the plasma membrane. Polarized exocytosis in cells is achieved through the coordinated actions of membrane trafficking machinery and cytoskeleton orchestrated by signaling molecules such as the Rho family of small GTPases. Elucidating the molecular mechanisms of polarized exocytosis is essential to our understanding of a wide range of pathophysiological processes from neuronal development to tumor invasion.
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Affiliation(s)
- Jingwen Zeng
- Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6018
| | - Shanshan Feng
- Key Laboratory for Regenerative Medicine of Ministry of Education and Department of Developmental & Regenerative Biology, Jinan University, Guangzhou 510632, P.R. China
| | - Bin Wu
- Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6018
| | - Wei Guo
- Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6018
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39
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Abstract
A conserved molecular machinery centered on the Cdc42 GTPase regulates cell polarity in diverse organisms. Here we review findings from budding and fission yeasts that reveal both a conserved core polarity circuit and several adaptations that each organism exploits to fulfill the needs of its lifestyle. The core circuit involves positive feedback by local activation of Cdc42 to generate a cluster of concentrated GTP-Cdc42 at the membrane. Species-specific pathways regulate the timing of polarization during the cell cycle, as well as the location and number of polarity sites.
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Affiliation(s)
- Jian-Geng Chiou
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, North Carolina 27710;
| | - Mohan K Balasubramanian
- Division of Biomedical Sciences, Warwick Medical School, University of Warwick, Coventry CV4 7AL, United Kingdom
| | - Daniel J Lew
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, North Carolina 27710;
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40
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Goryachev AB, Leda M. Many roads to symmetry breaking: molecular mechanisms and theoretical models of yeast cell polarity. Mol Biol Cell 2017; 28:370-380. [PMID: 28137950 PMCID: PMC5341721 DOI: 10.1091/mbc.e16-10-0739] [Citation(s) in RCA: 69] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2016] [Revised: 11/17/2016] [Accepted: 11/23/2016] [Indexed: 01/08/2023] Open
Abstract
Mathematical modeling has been instrumental in identifying common principles of cell polarity across diverse systems. These principles include positive feedback loops that are required to destabilize a spatially uniform state of the cell. The conserved small G-protein Cdc42 is a master regulator of eukaryotic cellular polarization. Here we discuss recent developments in studies of Cdc42 polarization in budding and fission yeasts and demonstrate that models describing symmetry-breaking polarization can be classified into six minimal classes based on the structure of positive feedback loops that activate and localize Cdc42. Owing to their generic system-independent nature, these model classes are also likely to be relevant for the G-protein–based symmetry-breaking systems of higher eukaryotes. We review experimental evidence pro et contra different theoretically plausible models and conclude that several parallel and non–mutually exclusive mechanisms are likely involved in cellular polarization of yeasts. This potential redundancy needs to be taken into consideration when interpreting the results of recent cell-rewiring studies.
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Affiliation(s)
- Andrew B Goryachev
- Center for Synthetic and Systems Biology, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3BF, United Kingdom
| | - Marcin Leda
- Center for Synthetic and Systems Biology, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3BF, United Kingdom
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41
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Masgrau A, Battola A, Sanmartin T, Pryszcz LP, Gabaldón T, Mendoza M. Distinct roles of the polarity factors Boi1 and Boi2 in the control of exocytosis and abscission in budding yeast. Mol Biol Cell 2017; 28:3082-3094. [PMID: 28904204 PMCID: PMC5662264 DOI: 10.1091/mbc.e17-06-0404] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2017] [Revised: 08/31/2017] [Accepted: 09/06/2017] [Indexed: 01/09/2023] Open
Abstract
The budding yeast cortical proteins Boi1 and Boi2 were previously implicated in polarized growth and in inhibition of cytokinesis as part of the NoCut abscission checkpoint. This report establishes an essential role of Boi1 and Boi2 in vesicle exocytosis during bud growth, whereas Boi2 (but not Boi1) is required for abscission inhibition. Boi1 and Boi2 (Boi1/2) are budding yeast plasma membrane proteins that function in polarized growth, and in cytokinesis inhibition in response to chromosome bridges via the NoCut abscission checkpoint. How Boi1/2 act in these two distinct processes is not understood. We demonstrate that Boi1/2 are required for a late step in the fusion of secretory vesicles with the plasma membrane of the growing bud. Cells lacking Boi1/2 accumulate secretory vesicles and are defective in bud growth. In contrast, Boi2 is specifically required for abscission inhibition in cells with chromatin bridges. The SH3 domain of Boi2, which is dispensable for bud growth and targets Boi2 to the site of abscission, is necessary and sufficient for abscission inhibition. Gain of function of the exocyst, a conserved protein complex involved in tethering of exocytic vesicles to the plasma membrane, rescued secretion and bud growth defects in boi mutant cells, and abrogated NoCut checkpoint function. Thus Boi2 functions redundantly with Boi1 to promote the fusion of secretory vesicles with the plasma membrane at sites of polarized growth, and acts as an abscission inhibitor during cytokinesis in response to chromatin bridges.
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Affiliation(s)
- Aina Masgrau
- Centre for Genomic Regulation, The Barcelona Institute of Science and Technology, 08003 Barcelona, Spain.,Universitat Pompeu Fabra, 08003 Barcelona, Spain
| | - Andrea Battola
- Centre for Genomic Regulation, The Barcelona Institute of Science and Technology, 08003 Barcelona, Spain.,Universitat Pompeu Fabra, 08003 Barcelona, Spain
| | - Trinidad Sanmartin
- Centre for Genomic Regulation, The Barcelona Institute of Science and Technology, 08003 Barcelona, Spain.,Universitat Pompeu Fabra, 08003 Barcelona, Spain
| | - Leszek P Pryszcz
- Centre for Genomic Regulation, The Barcelona Institute of Science and Technology, 08003 Barcelona, Spain.,Universitat Pompeu Fabra, 08003 Barcelona, Spain
| | - Toni Gabaldón
- Centre for Genomic Regulation, The Barcelona Institute of Science and Technology, 08003 Barcelona, Spain.,Universitat Pompeu Fabra, 08003 Barcelona, Spain.,Institució Catalana de Recerca i Estudis Avançats, 08010 Barcelona, Spain
| | - Manuel Mendoza
- Centre for Genomic Regulation, The Barcelona Institute of Science and Technology, 08003 Barcelona, Spain .,Universitat Pompeu Fabra, 08003 Barcelona, Spain
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42
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Monis WJ, Faundez V, Pazour GJ. BLOC-1 is required for selective membrane protein trafficking from endosomes to primary cilia. J Cell Biol 2017; 216:2131-2150. [PMID: 28576874 PMCID: PMC5496619 DOI: 10.1083/jcb.201611138] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2016] [Revised: 03/24/2017] [Accepted: 05/03/2017] [Indexed: 11/30/2022] Open
Abstract
Primary cilia perceive the extracellular environment through receptors localized in the ciliary membrane, but mechanisms directing specific proteins to this domain are poorly understood. To address this question, we knocked down proteins potentially important for ciliary membrane targeting and determined how this affects the ciliary trafficking of fibrocystin, polycystin-2, and smoothened. Our analysis showed that fibrocystin and polycystin-2 are dependent on IFT20, GMAP210, and the exocyst complex, while smoothened delivery is largely independent of these components. In addition, we found that polycystin-2, but not smoothened or fibrocystin, requires the biogenesis of lysosome-related organelles complex-1 (BLOC-1) for ciliary delivery. Consistent with the role of BLOC-1 in sorting from the endosome, we find that disrupting the recycling endosome reduces ciliary polycystin-2 and causes its accumulation in the recycling endosome. This is the first demonstration of a role for BLOC-1 in ciliary assembly and highlights the complexity of pathways taken to the cilium.
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Affiliation(s)
- William J Monis
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA
| | - Victor Faundez
- Department of Cell Biology, Emory University, Atlanta, GA
| | - Gregory J Pazour
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA
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43
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Lepore D, Spassibojko O, Pinto G, Collins RN. Cell cycle-dependent phosphorylation of Sec4p controls membrane deposition during cytokinesis. J Cell Biol 2017; 214:691-703. [PMID: 27621363 PMCID: PMC5021095 DOI: 10.1083/jcb.201602038] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2016] [Accepted: 08/04/2016] [Indexed: 11/22/2022] Open
Abstract
The GTPase Sec4p is a critical regulator of polarized membrane traffic. Lepore et al. show that the polo-like kinase Cdc5p phosphorylates Sec4p, which promotes coordinated membrane deposition during cytokinesis. Intracellular trafficking is an essential and conserved eukaryotic process. Rab GTPases are a family of proteins that regulate and provide specificity for discrete membrane trafficking steps by harnessing a nucleotide-bound cycle. Global proteomic screens have revealed many Rab GTPases as phosphoproteins, but the effects of this modification are not well understood. Using the Saccharomyces cerevisiae Rab GTPase Sec4p as a model, we have found that phosphorylation negatively regulates Sec4p function by disrupting the interaction with the exocyst complex via Sec15p. We demonstrate that phosphorylation of Sec4p is a cell cycle–dependent process associated with cytokinesis. Through a genomic kinase screen, we have also identified the polo-like kinase Cdc5p as a positive regulator of Sec4p phosphorylation. Sec4p spatially and temporally localizes with Cdc5p exclusively when Sec4p phosphorylation levels peak during the cell cycle, indicating Sec4p is a direct Cdc5p substrate. Our data suggest the physiological relevance of Sec4p phosphorylation is to facilitate the coordination of membrane-trafficking events during cytokinesis.
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Affiliation(s)
- Dante Lepore
- Field of Biochemistry, Molecular and Cellular Biology, Cornell University, Ithaca, NY 14853 Department of Molecular Medicine, Cornell University, Ithaca, NY 14853
| | - Olya Spassibojko
- Cornell Undergraduate Biology, Cornell University, Ithaca, NY 14853
| | - Gabrielle Pinto
- Cornell Undergraduate Biology, Cornell University, Ithaca, NY 14853
| | - Ruth N Collins
- Department of Molecular Medicine, Cornell University, Ithaca, NY 14853
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44
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Sekereš J, Pejchar P, Šantrůček J, Vukašinović N, Žárský V, Potocký M. Analysis of Exocyst Subunit EXO70 Family Reveals Distinct Membrane Polar Domains in Tobacco Pollen Tubes. PLANT PHYSIOLOGY 2017; 173:1659-1675. [PMID: 28082718 PMCID: PMC5338673 DOI: 10.1104/pp.16.01709] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2016] [Accepted: 01/10/2017] [Indexed: 05/05/2023]
Abstract
The vesicle-tethering complex exocyst is one of the crucial cell polarity regulators. The EXO70 subunit is required for the targeting of the complex and is represented by many isoforms in angiosperm plant cells. This diversity could be partly responsible for the establishment and maintenance of membrane domains with different composition. To address this hypothesis, we employed the growing pollen tube, a well-established cell polarity model system, and performed large-scale expression, localization, and functional analysis of tobacco (Nicotiana tabacum) EXO70 isoforms. Various isoforms localized to different regions of the pollen tube plasma membrane, apical vesicle-rich inverted cone region, nucleus, and cytoplasm. The overexpression of major pollen-expressed EXO70 isoforms resulted in growth arrest and characteristic phenotypic deviations of tip swelling and apical invaginations. NtEXO70A1a and NtEXO70B1 occupied two distinct and mutually exclusive plasma membrane domains. Both isoforms partly colocalized with the exocyst subunit NtSEC3a at the plasma membrane, possibly forming different exocyst complex subpopulations. NtEXO70A1a localized to the small area previously characterized as the site of exocytosis in the tobacco pollen tube, while NtEXO70B1 surprisingly colocalized with the zone of clathrin-mediated endocytosis. Both NtEXO70A1a and NtEXO70B1 colocalized to different degrees with markers for the anionic signaling phospholipids phosphatidylinositol 4,5-bisphosphate and phosphatidic acid. In contrast, members of the EXO70 C class, which are specifically expressed in tip-growing cells, exhibited exocytosis-related functional effects in pollen tubes despite the absence of apparent plasma membrane localization. Taken together, our data support the existence of multiple membrane-trafficking domains regulated by different EXO70-containing exocyst complexes within a single cell.
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Affiliation(s)
- Juraj Sekereš
- Institute of Experimental Botany, Czech Academy of Sciences, Prague 6, Czech Republic (J.S., P.P., N.V., V.Ž., M.P.)
- Department of Experimental Plant Biology, Faculty of Science, Charles University, Prague 2, Czech Republic (J.S., V.Ž.); and
- Department of Biochemistry and Microbiology, University of Chemistry and Technology, Prague 6, Czech Republic (J.Š.)
| | - Přemysl Pejchar
- Institute of Experimental Botany, Czech Academy of Sciences, Prague 6, Czech Republic (J.S., P.P., N.V., V.Ž., M.P.)
- Department of Experimental Plant Biology, Faculty of Science, Charles University, Prague 2, Czech Republic (J.S., V.Ž.); and
- Department of Biochemistry and Microbiology, University of Chemistry and Technology, Prague 6, Czech Republic (J.Š.)
| | - Jiří Šantrůček
- Institute of Experimental Botany, Czech Academy of Sciences, Prague 6, Czech Republic (J.S., P.P., N.V., V.Ž., M.P.)
- Department of Experimental Plant Biology, Faculty of Science, Charles University, Prague 2, Czech Republic (J.S., V.Ž.); and
- Department of Biochemistry and Microbiology, University of Chemistry and Technology, Prague 6, Czech Republic (J.Š.)
| | - Nemanja Vukašinović
- Institute of Experimental Botany, Czech Academy of Sciences, Prague 6, Czech Republic (J.S., P.P., N.V., V.Ž., M.P.)
- Department of Experimental Plant Biology, Faculty of Science, Charles University, Prague 2, Czech Republic (J.S., V.Ž.); and
- Department of Biochemistry and Microbiology, University of Chemistry and Technology, Prague 6, Czech Republic (J.Š.)
| | - Viktor Žárský
- Institute of Experimental Botany, Czech Academy of Sciences, Prague 6, Czech Republic (J.S., P.P., N.V., V.Ž., M.P.)
- Department of Experimental Plant Biology, Faculty of Science, Charles University, Prague 2, Czech Republic (J.S., V.Ž.); and
- Department of Biochemistry and Microbiology, University of Chemistry and Technology, Prague 6, Czech Republic (J.Š.)
| | - Martin Potocký
- Institute of Experimental Botany, Czech Academy of Sciences, Prague 6, Czech Republic (J.S., P.P., N.V., V.Ž., M.P.);
- Department of Experimental Plant Biology, Faculty of Science, Charles University, Prague 2, Czech Republic (J.S., V.Ž.); and
- Department of Biochemistry and Microbiology, University of Chemistry and Technology, Prague 6, Czech Republic (J.Š.)
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Kustermann J, Wu Y, Rieger L, Dedden D, Phan T, Walther P, Dünkler A, Johnsson N. The cell polarity proteins Boi1p and Boi2p stimulate vesicle fusion at the plasma membrane of yeast cells. J Cell Sci 2017; 130:2996-3008. [DOI: 10.1242/jcs.206334] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Accepted: 07/24/2017] [Indexed: 12/20/2022] Open
Abstract
Eukaryotic cells can direct secretion to defined regions of their plasma membrane. These regions are distinguished by an elaborate architecture of proteins and lipids that are specialized to capture and fuse post-Golgi vesicles. Here we show that the proteins Boi1p and Boi2p are important elements of this area of active exocytosis at the tip of growing yeast cells. Cells lacking Boi1p and Boi2p accumulate secretory vesicles in their bud. The essential PH domains of Boi1p and Boi2p interact with Sec1p, a protein required for SNARE complex formation and vesicle fusion. Sec1p loses its tip localization in cells depleted of Boi1p and Boi2p but can partially compensate for their loss upon overexpression. The capacity to simultaneously bind phospholipids, Sec1p, multiple subunits of the exocyst, Cdc42p, and the module for generating active Cdc42p identify Boi1p and Boi2p as essential mediators between exocytosis and polar growth.
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Affiliation(s)
- Jochen Kustermann
- Institute of Molecular Genetics and Cell Biology, Department of Biology, Ulm University, James-Franck-Ring N27, D-89081 Ulm, Germany
| | - Yehui Wu
- Institute of Molecular Genetics and Cell Biology, Department of Biology, Ulm University, James-Franck-Ring N27, D-89081 Ulm, Germany
| | - Lucia Rieger
- Institute of Molecular Genetics and Cell Biology, Department of Biology, Ulm University, James-Franck-Ring N27, D-89081 Ulm, Germany
| | - Dirk Dedden
- Institute of Molecular Genetics and Cell Biology, Department of Biology, Ulm University, James-Franck-Ring N27, D-89081 Ulm, Germany
| | - Tamara Phan
- Institute of Molecular Genetics and Cell Biology, Department of Biology, Ulm University, James-Franck-Ring N27, D-89081 Ulm, Germany
| | - Paul Walther
- Institute of Molecular Genetics and Cell Biology, Department of Biology, Ulm University, James-Franck-Ring N27, D-89081 Ulm, Germany
| | - Alexander Dünkler
- Institute of Molecular Genetics and Cell Biology, Department of Biology, Ulm University, James-Franck-Ring N27, D-89081 Ulm, Germany
| | - Nils Johnsson
- Institute of Molecular Genetics and Cell Biology, Department of Biology, Ulm University, James-Franck-Ring N27, D-89081 Ulm, Germany
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Tang H, Song M, He Y, Wang J, Wang S, Shen Y, Hou J, Bao X. Engineering vesicle trafficking improves the extracellular activity and surface display efficiency of cellulases in Saccharomyces cerevisiae. BIOTECHNOLOGY FOR BIOFUELS 2017; 10:53. [PMID: 28261326 PMCID: PMC5327580 DOI: 10.1186/s13068-017-0738-8] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2016] [Accepted: 02/17/2017] [Indexed: 05/12/2023]
Abstract
BACKGROUND Cellulase expression via extracellular secretion or surface display in Saccharomyces cerevisiae is one of the most frequently used strategies for a consolidated bioprocess (CBP) of cellulosic ethanol production. However, the inefficiency of the yeast secretory pathway often results in low production of heterologous proteins, which largely limits cellulase secretion or display. RESULTS In this study, the components of the vesicle trafficking from the endoplasmic reticulum (ER) to the Golgi and from the Golgi to the plasma membrane, involved in vesicle budding, tethering and fusion, were over-expressed in Clostridium thermocellum endoglucanase (CelA)- and Sacchromycopsis fibuligera β-glucosidase (BGL1)-secreting or -displaying strains. Engineering the targeted components in the ER to Golgi vesicle trafficking, including Sec12p, Sec13p, Erv25p and Bos1p, enhanced the extracellular activity of CelA. However, only Sec13p over-expression increased BGL1 secretion. By contrast, over-expression of the components in the Golgi to plasma membrane vesicle trafficking, including Sso1p, Snc2p, Sec1p, Exo70p, Ypt32p and Sec4p, showed better performance in increasing BGL1 secretion compared to CelA secretion, and the over-expression of these components all increased BGL1 extracellular activity. These results revealed that various cellulases showed different limitations in protein transport, and engineering vesicle trafficking has protein-specific effects. Importantly, we found that engineering the above vesicle trafficking components, particularly from the ER to the Golgi, also improved the display efficiency of CelA and BGL1 when a-agglutinin was used as surface display system. Further analyses illustrated that the display efficiency of a-agglutinin was increased by engineering vesicle trafficking, and the trend was consistent with displayed CelA and BGL1. These results indicated that fusion with a-agglutinin may affect the proteins' properties and alter the rate-limiting step in the vesicle trafficking. CONCLUSIONS We have demonstrated, for the first time, engineering vesicle trafficking from the ER to the Golgi and from the Golgi to the plasma membrane can enhance the protein display efficiency. We also found that different heterologous proteins had specific limitations in vesicle trafficking pathway and that engineering the vesicle trafficking resulted in a protein-specific effect. These results provide a new strategy to improve the extracellular secretion and surface display of cellulases in S. cerevisiae.
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Affiliation(s)
- Hongting Tang
- The School of Life Science, State Key Laboratory of Microbial Technology, Shandong University, Jinan, 250100 China
| | - Meihui Song
- The School of Life Science, State Key Laboratory of Microbial Technology, Shandong University, Jinan, 250100 China
| | - Yao He
- The School of Life Science, State Key Laboratory of Microbial Technology, Shandong University, Jinan, 250100 China
| | - Jiajing Wang
- The School of Life Science, State Key Laboratory of Microbial Technology, Shandong University, Jinan, 250100 China
| | - Shenghuan Wang
- The School of Life Science, State Key Laboratory of Microbial Technology, Shandong University, Jinan, 250100 China
| | - Yu Shen
- The School of Life Science, State Key Laboratory of Microbial Technology, Shandong University, Jinan, 250100 China
| | - Jin Hou
- The School of Life Science, State Key Laboratory of Microbial Technology, Shandong University, Jinan, 250100 China
| | - Xiaoming Bao
- The School of Life Science, State Key Laboratory of Microbial Technology, Shandong University, Jinan, 250100 China
- Shandong Provincial Key Laboratory of Microbial Engineering, Qi Lu University of Technology, Jinan, 250353 China
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Boehm CM, Obado S, Gadelha C, Kaupisch A, Manna PT, Gould GW, Munson M, Chait BT, Rout MP, Field MC. The Trypanosome Exocyst: A Conserved Structure Revealing a New Role in Endocytosis. PLoS Pathog 2017; 13:e1006063. [PMID: 28114397 PMCID: PMC5256885 DOI: 10.1371/journal.ppat.1006063] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2016] [Accepted: 11/14/2016] [Indexed: 01/10/2023] Open
Abstract
Membrane transport is an essential component of pathogenesis for most infectious organisms. In African trypanosomes, transport to and from the plasma membrane is closely coupled to immune evasion and antigenic variation. In mammals and fungi an octameric exocyst complex mediates late steps in exocytosis, but comparative genomics suggested that trypanosomes retain only six canonical subunits, implying mechanistic divergence. We directly determined the composition of the Trypanosoma brucei exocyst by affinity isolation and demonstrate that the parasite complex is nonameric, retaining all eight canonical subunits (albeit highly divergent at the sequence level) plus a novel essential subunit, Exo99. Exo99 and Sec15 knockdowns have remarkably similar phenotypes in terms of viability and impact on morphology and trafficking pathways. Significantly, both Sec15 and Exo99 have a clear function in endocytosis, and global proteomic analysis indicates an important role in maintaining the surface proteome. Taken together these data indicate additional exocyst functions in trypanosomes, which likely include endocytosis, recycling and control of surface composition. Knockdowns in HeLa cells suggest that the role in endocytosis is shared with metazoan cells. We conclude that, whilst the trypanosome exocyst has novel components, overall functionality appears conserved, and suggest that the unique subunit may provide therapeutic opportunities.
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Affiliation(s)
- Cordula M. Boehm
- Wellcome Trust Centre for Anti-Infectives Research, School of Life Sciences, University of Dundee, Dow Street, Dundee, United Kingdom
| | - Samson Obado
- The Rockefeller University, 1230 York Avenue, New York, NY, United States of America
| | - Catarina Gadelha
- School of Life Sciences, University of Nottingham, Nottingham, United Kingdom
| | - Alexandra Kaupisch
- Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Paul T. Manna
- Wellcome Trust Centre for Anti-Infectives Research, School of Life Sciences, University of Dundee, Dow Street, Dundee, United Kingdom
| | - Gwyn W. Gould
- Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Mary Munson
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA, United States of America
| | - Brian T. Chait
- The Rockefeller University, 1230 York Avenue, New York, NY, United States of America
| | - Michael P. Rout
- The Rockefeller University, 1230 York Avenue, New York, NY, United States of America
| | - Mark C. Field
- Wellcome Trust Centre for Anti-Infectives Research, School of Life Sciences, University of Dundee, Dow Street, Dundee, United Kingdom
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48
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Dubuke ML, Munson M. The Secret Life of Tethers: The Role of Tethering Factors in SNARE Complex Regulation. Front Cell Dev Biol 2016; 4:42. [PMID: 27243006 PMCID: PMC4860414 DOI: 10.3389/fcell.2016.00042] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2016] [Accepted: 04/25/2016] [Indexed: 02/03/2023] Open
Abstract
Trafficking in eukaryotic cells is a tightly regulated process to ensure correct cargo delivery to the proper destination organelle or plasma membrane. In this review, we focus on how the vesicle fusion machinery, the SNARE complex, is regulated by the interplay of the multisubunit tethering complexes (MTC) with the SNAREs and Sec1/Munc18 (SM) proteins. Although these factors are used in different stages of membrane trafficking, e.g., Golgi to plasma membrane transport vs. vacuolar fusion, and in a variety of diverse eukaryotic cell types, many commonalities between their functions are being revealed. We explore the various protein-protein interactions and findings from functional reconstitution studies in order to highlight both their common features and the differences in their modes of regulation. These studies serve as a starting point for mechanistic explorations in other systems.
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Affiliation(s)
- Michelle L Dubuke
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School Worcester, MA USA
| | - Mary Munson
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School Worcester, MA USA
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49
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Wei B, Hercyk BS, Mattson N, Mohammadi A, Rich J, DeBruyne E, Clark MM, Das M. Unique spatiotemporal activation pattern of Cdc42 by Gef1 and Scd1 promotes different events during cytokinesis. Mol Biol Cell 2016; 27:1235-45. [PMID: 26941334 PMCID: PMC4831878 DOI: 10.1091/mbc.e15-10-0700] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2015] [Accepted: 02/23/2016] [Indexed: 11/11/2022] Open
Abstract
The Rho-family GTPase Cdc42 regulates cell polarity and localizes to the cell division site. Cdc42 is activated by guanine nucleotide exchange factors (GEFs). We report that Cdc42 promotes cytokinesis via a unique spatiotemporal activation pattern due to the distinct action of its GEFs, Gef1 and Scd1, in fission yeast. Before cytokinetic ring constriction, Cdc42 activation, is Gef1 dependent, and after ring constriction, it is Scd1 dependent. Gef1 localizes to the actomyosin ring immediately after ring assembly and promotes timely onset of ring constriction. Gef1 is required for proper actin organization during cytokinesis, distribution of type V myosin Myo52 to the division site, and timely recruitment of septum protein Bgs1. In contrast, Scd1 localizes to the broader region of ingressing membrane during cytokinetic furrowing. Scd1 promotes normal septum formation, andscd1Δcells display aberrant septa with reduced Bgs1 localization. Thus we define unique roles of the GEFs Gef1 and Scd1 in the regulation of distinct events during cytokinesis. Gef1 localizes first to the cytokinetic ring and promotes timely constriction, whereas Scd1 localizes later to the ingressing membrane and promotes septum formation. Our findings are consistent with reports that complexity in GTPase signaling patterns enables exquisite precision over the control of cellular processes.
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Affiliation(s)
- Bin Wei
- Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee, Knoxville, TN 37996
| | - Brian S Hercyk
- Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee, Knoxville, TN 37996
| | - Nicholas Mattson
- Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee, Knoxville, TN 37996
| | - Ahmad Mohammadi
- Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee, Knoxville, TN 37996
| | - Julie Rich
- Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee, Knoxville, TN 37996
| | - Erica DeBruyne
- Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee, Knoxville, TN 37996
| | - Mikayla M Clark
- Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee, Knoxville, TN 37996
| | - Maitreyi Das
- Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee, Knoxville, TN 37996
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50
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Heider MR, Gu M, Duffy CM, Mirza AM, Marcotte LL, Walls AC, Farrall N, Hakhverdyan Z, Field MC, Rout MP, Frost A, Munson M. Subunit connectivity, assembly determinants and architecture of the yeast exocyst complex. Nat Struct Mol Biol 2016; 23:59-66. [PMID: 26656853 PMCID: PMC4752824 DOI: 10.1038/nsmb.3146] [Citation(s) in RCA: 87] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2015] [Accepted: 11/19/2015] [Indexed: 01/12/2023]
Abstract
The exocyst is a hetero-octameric complex that has been proposed to serve as the tethering complex for exocytosis, although it remains poorly understood at the molecular level. Here, we purified endogenous exocyst complexes from Saccharomyces cerevisiae and showed that they are stable and consist of all eight subunits with equal stoichiometry. Using a combination of biochemical and auxin induced-degradation experiments in yeast, we mapped the subunit connectivity, identified two stable four-subunit modules within the octamer and demonstrated that several known exocyst-binding partners are not necessary for exocyst assembly and stability. Furthermore, we visualized the structure of the yeast complex by using negative-stain electron microscopy; our results indicate that the exocyst exists predominantly as a stable, octameric complex with an elongated architecture that suggests that the subunits are contiguous helical bundles packed together into a bundle of long rods.
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Affiliation(s)
- Margaret R. Heider
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA, USA
| | - Mingyu Gu
- Department of Biochemistry, University of Utah, Salt Lake City, UT, USA
| | - Caroline M. Duffy
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA, USA
| | - Anne M. Mirza
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA, USA
| | - Laura L. Marcotte
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA, USA
| | - Alexandra C. Walls
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA, USA
| | - Nicholas Farrall
- Department of Biochemistry, University of Utah, Salt Lake City, UT, USA
| | - Zhanna Hakhverdyan
- Laboratory of Cellular and Structural Biology, The Rockefeller University, New York, NY, USA
| | - Mark C. Field
- Division of Biological Chemistry and Drug Discovery, University of Dundee, Dundee, UK
| | - Michael P. Rout
- Laboratory of Cellular and Structural Biology, The Rockefeller University, New York, NY, USA
| | - Adam Frost
- Department of Biochemistry, University of Utah, Salt Lake City, UT, USA
- Department of Biochemistry and Biophysics, University of California San Francisco, San Francisco, CA, USA
| | - Mary Munson
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA, USA
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