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Shaping subcellular tubes through vesicle trafficking: Common and distinct pathways. Semin Cell Dev Biol 2023; 133:74-82. [PMID: 35365398 DOI: 10.1016/j.semcdb.2022.03.024] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Revised: 03/18/2022] [Accepted: 03/20/2022] [Indexed: 11/23/2022]
Abstract
Cells with subcellular lumens form some of the most miniature tubes in the tubular organs of animals. These are often crucial components of the system, executing functions at remote body locations. Unlike tubes formed by intercellular or autocellular junctions, the cells with junctionless subcellular lumens face unique challenges in modifying the cell shape and plasma membrane organization to incorporate a membrane-bound tube within, often associated with dramatic cellular growth and extensions. Results in the recent years have shown that membrane dynamics, including both the primary delivery and recycling, is crucial in providing the cell with the flexibility to face these challenges. A significant portion of this information has come from two in vivo invertebrate models; the Drosophila tracheal terminal cells and the C. elegans excretory cell. This review focuses on the data obtained from these systems in the recent past about how trafficking pathways influence subcellular tube and branching morphogenesis. Given that such tubes occur in vertebrate vasculature, these insights are relevant to human health, and we contrast our conclusions with the less understood subcellular tubes of angiogenesis.
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Abstract
As multi-cellular organisms evolved from small clusters of cells to complex metazoans, biological tubes became essential for life. Tubes are typically thought of as mainly playing a role in transport, with the hollow space (lumen) acting as a conduit to distribute nutrients and waste, or for gas exchange. However, biological tubes also provide a platform for physiological, mechanical, and structural functions. Indeed, tubulogenesis is often a critical aspect of morphogenesis and organogenesis. C. elegans is made up of tubes that provide structural support and protection (the epidermis), perform the mechanical and enzymatic processes of digestion (the buccal cavity, pharynx, intestine, and rectum), transport fluids for osmoregulation (the excretory system), and execute the functions necessary for reproduction (the germline, spermatheca, uterus and vulva). Here we review our current understanding of the genetic regulation, molecular processes, and physical forces involved in tubulogenesis and morphogenesis of the epidermal, digestive and excretory systems in C. elegans.
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Affiliation(s)
- Daniel D Shaye
- Department of Physiology and Biophysics, University of Illinois at Chicago-College of Medicine, Chicago, IL, United States.
| | - Martha C Soto
- Department of Pathology and Laboratory Medicine, Rutgers-Robert Wood Johnson Medical School, Piscataway, NJ, United States.
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Yang Z, Mattingly BC, Hall DH, Ackley BD, Buechner M. Terminal web and vesicle trafficking proteins mediate nematode single-cell tubulogenesis. J Cell Biol 2020; 219:e202003152. [PMID: 32860501 PMCID: PMC7594493 DOI: 10.1083/jcb.202003152] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2020] [Revised: 06/15/2020] [Accepted: 08/03/2020] [Indexed: 11/22/2022] Open
Abstract
Single-celled tubules represent a complicated structure that forms during development, requiring extension of a narrow cytoplasm surrounding a lumen exerting osmotic pressure that can burst the luminal membrane. Genetic studies on the excretory canal cell of Caenorhabditis elegans have revealed many proteins that regulate the cytoskeleton, vesicular transport, and physiology of the narrow canals. Here, we show that βH-spectrin regulates the placement of intermediate filament proteins forming a terminal web around the lumen, and that the terminal web in turn retains a highly conserved protein (EXC-9/CRIP1) that regulates apical endosomal trafficking. EXC-1/IRG, the binding partner of EXC-9, is also localized to the apical membrane and affects apical actin placement and RAB-8-mediated vesicular transport. The results suggest that an intermediate filament protein acts in a novel pathway to direct the traffic of vesicles to locations of lengthening apical surface during single-celled tubule development.
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Affiliation(s)
- Zhe Yang
- Department of Molecular Biosciences, University of Kansas, Lawrence, KS
| | | | - David H. Hall
- Center for C. elegans Anatomy, Albert Einstein College of Medicine, Bronx, NY
| | - Brian D. Ackley
- Department of Molecular Biosciences, University of Kansas, Lawrence, KS
| | - Matthew Buechner
- Department of Molecular Biosciences, University of Kansas, Lawrence, KS
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Buechner M, Yang Z, Al-Hashimi H. A Series of Tubes: The C. elegans Excretory Canal Cell as a Model for Tubule Development. J Dev Biol 2020; 8:jdb8030017. [PMID: 32906663 PMCID: PMC7557474 DOI: 10.3390/jdb8030017] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2020] [Revised: 08/31/2020] [Accepted: 09/02/2020] [Indexed: 12/25/2022] Open
Abstract
Formation and regulation of properly sized epithelial tubes is essential for multicellular life. The excretory canal cell of C. elegans provides a powerful model for investigating the integration of the cytoskeleton, intracellular transport, and organismal physiology to regulate the developmental processes of tube extension, lumen formation, and lumen diameter regulation in a narrow single cell. Multiple studies have provided new understanding of actin and intermediate filament cytoskeletal elements, vesicle transport, and the role of vacuolar ATPase in determining tube size. Most of the genes discovered have clear homologues in humans, with implications for understanding these processes in mammalian tissues such as Schwann cells, renal tubules, and brain vasculature. The results of several new genetic screens are described that provide a host of new targets for future studies in this informative structure.
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Affiliation(s)
- Matthew Buechner
- Department of Molecular Biosciences, University of Kansas, Lawrence, KS 66045, USA;
- Correspondence:
| | - Zhe Yang
- Department of Molecular Biosciences, University of Kansas, Lawrence, KS 66045, USA;
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Wong SQ, Kumar AV, Mills J, Lapierre LR. C. elegans to model autophagy-related human disorders. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2020; 172:325-373. [PMID: 32620247 DOI: 10.1016/bs.pmbts.2020.01.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Autophagy is a highly conserved degradation process that clears damaged intracellular macromolecules and organelles in order to maintain cellular health. Dysfunctional autophagy is fundamentally linked to the development of various human disorders and pathologies. The use of the nematode Caenorhabditis elegans as a model system to study autophagy has improved our understanding of its regulation and function in organismal physiology. Here, we review the genetic, functional, and regulatory conservation of the autophagy pathway in C. elegans and we describe tools to quantify and study the autophagy process in this incredibly useful model organism. We further discuss how these nematodes have been modified to model autophagy-related human diseases and underscore the important insights obtained from such models. Altogether, we highlight the strengths of C. elegans as an exceptional tool to understand the genetic and molecular foundations underlying autophagy-related human diseases.
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Affiliation(s)
- Shi Quan Wong
- Department of Molecular Biology, Cell Biology, and Biochemistry, Brown University, Providence, RI, United States
| | - Anita V Kumar
- Department of Molecular Biology, Cell Biology, and Biochemistry, Brown University, Providence, RI, United States
| | - Joslyn Mills
- Department of Molecular Biology, Cell Biology, and Biochemistry, Brown University, Providence, RI, United States
| | - Louis R Lapierre
- Department of Molecular Biology, Cell Biology, and Biochemistry, Brown University, Providence, RI, United States.
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Novel exc Genes Involved in Formation of the Tubular Excretory Canals of Caenorhabditis elegans. G3-GENES GENOMES GENETICS 2019; 9:1339-1353. [PMID: 30885922 PMCID: PMC6505153 DOI: 10.1534/g3.119.200626] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Regulation of luminal diameter is critical to the function of small single-celled tubes, of which the seamless tubular excretory canals of Caenorhabditis elegans provide a tractable genetic model. Mutations in several sets of genes exhibit the Exc phenotype, in which canal luminal growth is visibly altered. Here, a focused reverse genomic screen of genes highly expressed in the canals found 18 genes that significantly affect luminal outgrowth or diameter. These genes encode novel proteins as well as highly conserved proteins involved in processes including gene expression, cytoskeletal regulation, and vesicular and transmembrane transport. In addition, two genes act as suppressors on a pathway of conserved genes whose products mediate vesicle movement from early to recycling endosomes. The results provide new tools for understanding the integration of cytoplasmic structure and physiology in forming and maintaining the narrow diameter of single-cell tubules.
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Tubular Excretory Canal Structure Depends on Intermediate Filaments EXC-2 and IFA-4 in Caenorhabditis elegans. Genetics 2018; 210:637-652. [PMID: 29945901 DOI: 10.1534/genetics.118.301078] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2018] [Accepted: 05/23/2018] [Indexed: 12/28/2022] Open
Abstract
The excretory canals of Caenorhabditis elegans are a model for understanding the maintenance of apical morphology in narrow single-celled tubes. Light and electron microscopy shows that mutants in exc-2 start to form canals normally, but these swell to develop large fluid-filled cysts that lack a complete terminal web at the apical surface, and accumulate filamentous material in the canal lumen. Here, whole-genome sequencing and gene rescue show that exc-2 encodes intermediate filament protein IFC-2 EXC-2/IFC-2 protein, fluorescently tagged via clustered regularly interspaced short palindromic repeats/Cas9, is located at the apical surface of the canals independently of other intermediate filament proteins. EXC-2 is also located in several other tissues, though the tagged isoforms are not seen in the larger intestinal tube. Tagged EXC-2 binds via pulldown to intermediate filament protein IFA-4, which is also shown to line the canal apical surface. Overexpression of either protein results in narrow but shortened canals. These results are consistent with a model whereby three intermediate filaments in the canals-EXC-2, IFA-4, and IFB-1-restrain swelling of narrow tubules in concert with actin filaments that guide the extension and direction of tubule outgrowth, while allowing the tube to bend as the animal moves.
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Kumar S, Jain A, Farzam F, Jia J, Gu Y, Choi SW, Mudd MH, Claude-Taupin A, Wester MJ, Lidke KA, Rusten TE, Deretic V. Mechanism of Stx17 recruitment to autophagosomes via IRGM and mammalian Atg8 proteins. J Cell Biol 2018; 217:997-1013. [PMID: 29420192 PMCID: PMC5839791 DOI: 10.1083/jcb.201708039] [Citation(s) in RCA: 97] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2017] [Revised: 11/12/2017] [Accepted: 12/22/2017] [Indexed: 12/13/2022] Open
Abstract
Autophagy is a conserved eukaryotic process with metabolic, immune, and general homeostatic functions in mammalian cells. Mammalian autophagosomes fuse with lysosomes in a SNARE-driven process that includes syntaxin 17 (Stx17). How Stx17 translocates to autophagosomes is unknown. In this study, we show that the mechanism of Stx17 recruitment to autophagosomes in human cells entails the small guanosine triphosphatase IRGM. Stx17 directly interacts with IRGM, and efficient Stx17 recruitment to autophagosomes requires IRGM. Both IRGM and Stx17 directly interact with mammalian Atg8 proteins, thus being guided to autophagosomes. We also show that Stx17 is significant in defense against infectious agents and that Stx17-IRGM interaction is targeted by an HIV virulence factor Nef.
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Affiliation(s)
- Suresh Kumar
- Autophagy Inflammation and Metabolism Center of Biomedical Research Excellence, University of New Mexico Health Sciences Center, Albuquerque, NM.,Department of Molecular Genetics and Microbiology, University of New Mexico Health Sciences Center, Albuquerque, NM
| | - Ashish Jain
- Department of Molecular Cell Biology, Centre for Cancer Biomedicine, University of Oslo and Institute for Cancer Research, The Norwegian Radium Hospital, Oslo, Norway
| | - Farzin Farzam
- Department of Physics and Astronomy, University of New Mexico, Albuquerque, NM
| | - Jingyue Jia
- Autophagy Inflammation and Metabolism Center of Biomedical Research Excellence, University of New Mexico Health Sciences Center, Albuquerque, NM.,Department of Molecular Genetics and Microbiology, University of New Mexico Health Sciences Center, Albuquerque, NM
| | - Yuexi Gu
- Autophagy Inflammation and Metabolism Center of Biomedical Research Excellence, University of New Mexico Health Sciences Center, Albuquerque, NM.,Department of Molecular Genetics and Microbiology, University of New Mexico Health Sciences Center, Albuquerque, NM
| | - Seong Won Choi
- Autophagy Inflammation and Metabolism Center of Biomedical Research Excellence, University of New Mexico Health Sciences Center, Albuquerque, NM.,Department of Molecular Genetics and Microbiology, University of New Mexico Health Sciences Center, Albuquerque, NM
| | - Michal H Mudd
- Autophagy Inflammation and Metabolism Center of Biomedical Research Excellence, University of New Mexico Health Sciences Center, Albuquerque, NM.,Department of Molecular Genetics and Microbiology, University of New Mexico Health Sciences Center, Albuquerque, NM
| | - Aurore Claude-Taupin
- Autophagy Inflammation and Metabolism Center of Biomedical Research Excellence, University of New Mexico Health Sciences Center, Albuquerque, NM.,Department of Molecular Genetics and Microbiology, University of New Mexico Health Sciences Center, Albuquerque, NM
| | - Michael J Wester
- Department of Mathematics and Statistics, University of New Mexico, Albuquerque, NM
| | - Keith A Lidke
- Department of Physics and Astronomy, University of New Mexico, Albuquerque, NM
| | - Tor-Erik Rusten
- Department of Molecular Cell Biology, Centre for Cancer Biomedicine, University of Oslo and Institute for Cancer Research, The Norwegian Radium Hospital, Oslo, Norway
| | - Vojo Deretic
- Autophagy Inflammation and Metabolism Center of Biomedical Research Excellence, University of New Mexico Health Sciences Center, Albuquerque, NM .,Department of Molecular Genetics and Microbiology, University of New Mexico Health Sciences Center, Albuquerque, NM
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