1
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Liu J, Murray JI. Mechanisms of lineage specification in Caenorhabditis elegans. Genetics 2023; 225:iyad174. [PMID: 37847877 DOI: 10.1093/genetics/iyad174] [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: 08/26/2023] [Accepted: 09/18/2023] [Indexed: 10/19/2023] Open
Abstract
The studies of cell fate and lineage specification are fundamental to our understanding of the development of multicellular organisms. Caenorhabditis elegans has been one of the premiere systems for studying cell fate specification mechanisms at single cell resolution, due to its transparent nature, the invariant cell lineage, and fixed number of somatic cells. We discuss the general themes and regulatory mechanisms that have emerged from these studies, with a focus on somatic lineages and cell fates. We next review the key factors and pathways that regulate the specification of discrete cells and lineages during embryogenesis and postembryonic development; we focus on transcription factors and include numerous lineage diagrams that depict the expression of key factors that specify embryonic founder cells and postembryonic blast cells, and the diverse somatic cell fates they generate. We end by discussing some future perspectives in cell and lineage specification.
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Affiliation(s)
- Jun Liu
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, USA
| | - John Isaac Murray
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
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2
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Townley R, Deniaud A, Stacy KS, Torres CSR, Cheraghi F, Wicker NB, de la Cova CC. The E3/E4 ubiquitin ligase UFD-2 suppresses normal and oncogenic signaling mediated by a Raf ortholog in Caenorhabditis elegans. Sci Signal 2023; 16:eabq4355. [PMID: 37643243 PMCID: PMC10656100 DOI: 10.1126/scisignal.abq4355] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2022] [Accepted: 08/10/2023] [Indexed: 08/31/2023]
Abstract
Signaling by the kinase cascade composed of Raf, MEK, and ERK is critical for animal development and is often inappropriately activated in human malignancies. We sought to identify factors that control signaling mediated by the Caenorhabditis elegans Raf ortholog LIN-45. A genetic screen showed that the degradation of LIN-45 required the E3/E4 ubiquitin ligase UFD-2. Both UFD-2 and its partner, the ATP-dependent segregase CDC-48, were required for the developmental regulation of LIN-45 protein abundance. We showed that UFD-2 acted in the same pathway as the E3 ubiquitin ligase SCFSEL-10 to decrease LIN-45 abundance in cells in which Raf-MEK-ERK signaling was most highly active. UFD-2 also reduced the protein abundance of activated LIN-45 carrying a mutation equivalent to the cancer-associated BRAF(V600E) variant. Our structure-function studies showed that the disruption of LIN-45 domains that mediate protein-protein interactions, including the conserved cysteine-rich domain and 14-3-3 binding motifs, were required for UFD-2-independent degradation of LIN-45. We propose a model in which UFD-2 and CDC-48 act downstream of SCFSEL-10 to remove LIN-45 from its protein interaction partners and facilitate proteasomal targeting and degradation. These findings imply that UFD-2 and CDC-48 may be important for Raf degradation during normal and oncogenic Ras and MAPK signaling in mammalian cells.
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Affiliation(s)
- Robert Townley
- Department of Biological Sciences, University of Wisconsin-Milwaukee; Milwaukee, Wisconsin, 53201 USA
| | - Augustin Deniaud
- Department of Biological Sciences, University of Wisconsin-Milwaukee; Milwaukee, Wisconsin, 53201 USA
| | - Kennedy S. Stacy
- Department of Biological Sciences, University of Wisconsin-Milwaukee; Milwaukee, Wisconsin, 53201 USA
| | | | - Fatemeh Cheraghi
- Department of Biological Sciences, University of Wisconsin-Milwaukee; Milwaukee, Wisconsin, 53201 USA
| | - Nicole B. Wicker
- Department of Biological Sciences, University of Wisconsin-Milwaukee; Milwaukee, Wisconsin, 53201 USA
| | - Claire C. de la Cova
- Department of Biological Sciences, University of Wisconsin-Milwaukee; Milwaukee, Wisconsin, 53201 USA
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3
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Jayadev R, Chi Q, Sherwood DR. Post-embryonic endogenous expression and localization of LET-60/Ras in C. elegans. MICROPUBLICATION BIOLOGY 2023; 2023:10.17912/micropub.biology.000931. [PMID: 37692087 PMCID: PMC10492041 DOI: 10.17912/micropub.biology.000931] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Subscribe] [Scholar Register] [Received: 07/21/2023] [Revised: 08/17/2023] [Accepted: 08/25/2023] [Indexed: 09/12/2023]
Abstract
Ras GTPases regulate many developmental and physiological processes and mutations in Ras are associated with numerous human cancers. Here, we report the function, levels, and localization of an N-terminal knock-in of mNeonGreen (mNG) into C. elegans LET-60 /Ras. mNG:: LET-60 interferes with some but not all LET-60 /Ras functions. mNG:: LET-60 is broadly present in tissues, found at different levels in cells, and concentrates in distinct subcellular compartments, including the nucleolus, nucleus, intracellular region, and plasma membrane. These results suggest that mNG:: LET-60 can be a useful tool for determining LET-60 levels and localization once its functionality in a developmental or physiological process is established.
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Affiliation(s)
| | - Qiuyi Chi
- Department of Biology, Duke University, Durham, NC, USA
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4
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Li K, Huo Q, Li BY, Yokota H. The Double-Edged Proteins in Cancer Proteomes and the Generation of Induced Tumor-Suppressing Cells (iTSCs). Proteomes 2023; 11:proteomes11010005. [PMID: 36810561 PMCID: PMC9944087 DOI: 10.3390/proteomes11010005] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2022] [Revised: 01/15/2023] [Accepted: 01/16/2023] [Indexed: 01/20/2023] Open
Abstract
Unlike a prevalent expectation that tumor cells secrete tumor-promoting proteins and stimulate the progression of neighboring tumor cells, accumulating evidence indicates that the role of tumor-secreted proteins is double-edged and context-dependent. Some of the oncogenic proteins in the cytoplasm and cell membranes, which are considered to promote the proliferation and migration of tumor cells, may inversely act as tumor-suppressing proteins in the extracellular domain. Furthermore, the action of tumor-secreted proteins by aggressive "super-fit" tumor cells can be different from those derived from "less-fit" tumor cells. Tumor cells that are exposed to chemotherapeutic agents could alter their secretory proteomes. Super-fit tumor cells tend to secrete tumor-suppressing proteins, while less-fit or chemotherapeutic agent-treated tumor cells may secrete tumor-promotive proteomes. Interestingly, proteomes derived from nontumor cells such as mesenchymal stem cells and peripheral blood mononuclear cells mostly share common features with tumor cell-derived proteomes in response to certain signals. This review introduces the double-sided functions of tumor-secreted proteins and describes the proposed underlying mechanism, which would possibly be based on cell competition.
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Affiliation(s)
- Kexin Li
- Department of Pharmacology, School of Pharmacy, Harbin Medical University, Harbin 150081, China
- Department of Biomedical Engineering, Indiana University Purdue University Indianapolis, Indianapolis, IN 46202, USA
| | - Qingji Huo
- Department of Pharmacology, School of Pharmacy, Harbin Medical University, Harbin 150081, China
- Department of Biomedical Engineering, Indiana University Purdue University Indianapolis, Indianapolis, IN 46202, USA
| | - Bai-Yan Li
- Department of Pharmacology, School of Pharmacy, Harbin Medical University, Harbin 150081, China
- Correspondence: (B.-Y.L.); (H.Y.)
| | - Hiroki Yokota
- Department of Biomedical Engineering, Indiana University Purdue University Indianapolis, Indianapolis, IN 46202, USA
- Indiana Center for Musculoskeletal Health, Indiana University School of Medicine, Indianapolis, IN 46202, USA
- Indiana University Simon Comprehensive Cancer Center, Indianapolis, IN 46202, USA
- Correspondence: (B.-Y.L.); (H.Y.)
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5
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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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6
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O'Keeffe C, Greenwald I. EGFR signal transduction is downregulated in C. elegans vulval precursor cells during dauer diapause. Development 2022; 149:dev201094. [PMID: 36227589 PMCID: PMC9793418 DOI: 10.1242/dev.201094] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2022] [Accepted: 10/04/2022] [Indexed: 11/05/2022]
Abstract
Caenorhabditis elegans larvae display developmental plasticity in response to environmental conditions: in adverse conditions, second-stage larvae enter a reversible, long-lived dauer stage instead of proceeding to reproductive adulthood. Dauer entry interrupts vulval induction and is associated with a reprogramming-like event that preserves the multipotency of vulval precursor cells (VPCs), allowing vulval development to reinitiate if conditions improve. Vulval induction requires the LIN-3/EGF-like signal from the gonad, which activates EGFR-Ras-ERK signal transduction in the nearest VPC, P6.p. Here, using a biosensor and live imaging we show that EGFR-Ras-ERK activity is downregulated in P6.p in dauers. We investigated this process using gene mutations or transgenes to manipulate different steps of the pathway, and by analyzing LET-23/EGFR subcellular localization during dauer life history. We found that the response to EGF is attenuated at or upstream of Ras activation, and discuss potential membrane-associated mechanisms that could achieve this. We also describe other findings pertaining to the maintenance of VPC competence and quiescence in dauer larvae. Our analysis indicates that VPCs have L2-like and unique dauer stage features rather than features of L3 VPCs in continuous development.
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Affiliation(s)
- Catherine O'Keeffe
- Department of Biological Sciences, Columbia University, New York, NY 10027, USA
| | - Iva Greenwald
- Department of Biological Sciences, Columbia University, New York, NY 10027, USA
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7
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Knox J, Joly N, Linossi EM, Carmona-Negrón JA, Jura N, Pintard L, Zuercher W, Roy PJ. A survey of the kinome pharmacopeia reveals multiple scaffolds and targets for the development of novel anthelmintics. Sci Rep 2021; 11:9161. [PMID: 33911106 PMCID: PMC8080662 DOI: 10.1038/s41598-021-88150-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2020] [Accepted: 04/08/2021] [Indexed: 11/10/2022] Open
Abstract
Over one billion people are currently infected with a parasitic nematode. Symptoms can include anemia, malnutrition, developmental delay, and in severe cases, death. Resistance is emerging to the anthelmintics currently used to treat nematode infection, prompting the need to develop new anthelmintics. Towards this end, we identified a set of kinases that may be targeted in a nematode-selective manner. We first screened 2040 inhibitors of vertebrate kinases for those that impair the model nematode Caenorhabditis elegans. By determining whether the terminal phenotype induced by each kinase inhibitor matched that of the predicted target mutant in C. elegans, we identified 17 druggable nematode kinase targets. Of these, we found that nematode EGFR, MEK1, and PLK1 kinases have diverged from vertebrates within their drug-binding pocket. For each of these targets, we identified small molecule scaffolds that may be further modified to develop nematode-selective inhibitors. Nematode EGFR, MEK1, and PLK1 therefore represent key targets for the development of new anthelmintic medicines.
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Affiliation(s)
- Jessica Knox
- Department of Molecular Genetics, University of Toronto, Toronto, ON, M5S 1A8, Canada.,The Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, ON, M5S 3E1, Canada
| | - Nicolas Joly
- Programme Équipe Labellisée Ligue Contre Le Cancer, Institut Jacques Monod, UMR7592, Université de Paris, CNRS, Paris, France
| | - Edmond M Linossi
- Cardiovascular Research Institute, University of California San Francisco, San Francisco, CA, 94158, USA
| | - José A Carmona-Negrón
- Cardiovascular Research Institute, University of California San Francisco, San Francisco, CA, 94158, USA
| | - Natalia Jura
- Cardiovascular Research Institute, University of California San Francisco, San Francisco, CA, 94158, USA.,Department of Cellular and Molecular Pharmacology, University of California San Francisco, San Francisco, CA, 94158, USA
| | - Lionel Pintard
- Programme Équipe Labellisée Ligue Contre Le Cancer, Institut Jacques Monod, UMR7592, Université de Paris, CNRS, Paris, France
| | - William Zuercher
- School of Pharmacy, UNC Eshelman, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
| | - Peter J Roy
- Department of Molecular Genetics, University of Toronto, Toronto, ON, M5S 1A8, Canada. .,The Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, ON, M5S 3E1, Canada. .,Department of Pharmacology and Toxicology, University of Toronto, Toronto, ON, M5S 1A8, Canada.
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8
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Gauthier KD, Rocheleau CE. Golgi localization of the LIN-2/7/10 complex points to a role in basolateral secretion of LET-23 EGFR in the Caenorhabditiselegans vulval precursor cells. Development 2021; 148:dev194167. [PMID: 33526581 PMCID: PMC10692275 DOI: 10.1242/dev.194167] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Accepted: 01/25/2021] [Indexed: 12/28/2022]
Abstract
The evolutionarily conserved LIN-2 (CASK)/LIN-7 (Lin7A-C)/LIN-10 (APBA1) complex plays an important role in regulating spatial organization of membrane proteins and signaling components. In Caenorhabditiselegans, the complex is essential for the development of the vulva by promoting the localization of the sole Epidermal growth factor receptor (EGFR) ortholog LET-23 to the basolateral membrane of the vulva precursor cells where it can specify the vulval cell fate. To understand how the LIN-2/7/10 complex regulates receptor localization, we determined its expression and localization during vulva development. We found that LIN-7 colocalizes with LET-23 EGFR at the basolateral membrane, whereas the LIN-2/7/10 complex colocalizes with LET-23 EGFR at cytoplasmic punctae that mostly overlap with the Golgi. Furthermore, LIN-10 recruits LIN-2, which in turn recruits LIN-7. We demonstrate that the complex forms in vivo with a particularly strong interaction and colocalization between LIN-2 and LIN-7, consistent with them forming a subcomplex. Thus, the LIN-2/7/10 complex forms on the Golgi on which it likely targets LET-23 EGFR trafficking to the basolateral membrane rather than functioning as a tether.
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Affiliation(s)
- Kimberley D Gauthier
- Division of Endocrinology and Metabolism, Department of Medicine, and Department of Anatomy and Cell Biology, McGill University; and the Metabolic Disorders and Complications Program, Centre for Translational Biology, Research Institute of the McGill University Health Centre, Montreal, QC H4A 3J1, Canada
| | - Christian E Rocheleau
- Division of Endocrinology and Metabolism, Department of Medicine, and Department of Anatomy and Cell Biology, McGill University; and the Metabolic Disorders and Complications Program, Centre for Translational Biology, Research Institute of the McGill University Health Centre, Montreal, QC H4A 3J1, Canada
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9
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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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10
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Abstract
During multicellular organism development, complex structures are sculpted to form organs and tissues, which are maintained throughout adulthood. Many of these processes require cells to fuse with one another, or with themselves. These plasma membrane fusions merge endoplasmic cellular content across external, exoplasmic, space. In the nematode Caenorhabditis elegans, such cell fusions serve as a unique sculpting force, involved in the embryonic morphogenesis of the skin-like multinuclear hypodermal cells, but also in refining delicate structures, such as valve openings and the tip of the tail. During post-embryonic development, plasma membrane fusions continue to shape complex neuron structures and organs such as the vulva, while during adulthood fusion participates in cell and tissue repair. These processes rely on two fusion proteins (fusogens): EFF-1 and AFF-1, which are part of a broader family of structurally related membrane fusion proteins, encompassing sexual reproduction, viral infection, and tissue remodeling. The established capabilities of these exoplasmic fusogens are further expanded by new findings involving EFF-1 and AFF-1 in endocytic vesicle fission and phagosome sealing. Tight regulation by cell-autonomous and non-cell autonomous mechanisms orchestrates these diverse cell fusions at the correct place and time-these processes and their significance are discussed in this review.
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11
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Lant B, Pal S, Chapman EM, Yu B, Witvliet D, Choi S, Zhao L, Albiges-Rizo C, Faurobert E, Derry WB. Interrogating the ccm-3 Gene Network. Cell Rep 2019; 24:2857-2868.e4. [PMID: 30208312 DOI: 10.1016/j.celrep.2018.08.039] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2018] [Revised: 06/27/2018] [Accepted: 08/15/2018] [Indexed: 01/29/2023] Open
Abstract
Cerebral cavernous malformations (CCMs) are neurovascular lesions caused by mutations in one of three genes (CCM1-3). Loss of CCM3 causes the poorest prognosis, and little is known about how it regulates vascular integrity. The C. elegans ccm-3 gene regulates the development of biological tubes that resemble mammalian vasculature, and in a genome-wide reverse genetic screen, we identified more than 500 possible CCM-3 pathway genes. With a phenolog-like approach, we generated a human CCM signaling network and identified 29 genes in common, of which 14 are required for excretory canal extension and membrane integrity, similar to ccm-3. Notably, depletion of the MO25 ortholog mop-25.2 causes severe defects in tube integrity by preventing CCM-3 localization to apical membranes. Furthermore, loss of MO25 phenocopies CCM3 ablation by causing stress fiber formation in endothelial cells. This work deepens our understanding of how CCM3 regulates vascular integrity and may help identify therapeutic targets for treating CCM3 patients.
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Affiliation(s)
- Benjamin Lant
- Developmental and Stem Cell Biology Program, The Hospital for Sick Children, Peter Gilgan Centre for Research and Learning, 686 Bay Street, Toronto, ON M5G 0A4, Canada
| | - Swati Pal
- Developmental and Stem Cell Biology Program, The Hospital for Sick Children, Peter Gilgan Centre for Research and Learning, 686 Bay Street, Toronto, ON M5G 0A4, Canada
| | - Eric Michael Chapman
- Developmental and Stem Cell Biology Program, The Hospital for Sick Children, Peter Gilgan Centre for Research and Learning, 686 Bay Street, Toronto, ON M5G 0A4, Canada; Department of Molecular Genetics, University of Toronto, 1 King's College Circle, Toronto, ON M5S 1A8, Canada
| | - Bin Yu
- Developmental and Stem Cell Biology Program, The Hospital for Sick Children, Peter Gilgan Centre for Research and Learning, 686 Bay Street, Toronto, ON M5G 0A4, Canada
| | - Daniel Witvliet
- Department of Molecular Genetics, University of Toronto, 1 King's College Circle, Toronto, ON M5S 1A8, Canada; Lunenfeld-Tanenbaum Research Institute at Mount Sinai Hospital, 600 University Avenue, Toronto, ON M5G 1X5, Canada
| | - Soo Choi
- Developmental and Stem Cell Biology Program, The Hospital for Sick Children, Peter Gilgan Centre for Research and Learning, 686 Bay Street, Toronto, ON M5G 0A4, Canada
| | - Lisa Zhao
- Department of Molecular Genetics, University of Toronto, 1 King's College Circle, Toronto, ON M5S 1A8, Canada
| | - Corinne Albiges-Rizo
- Institute for Advanced Biosciences, CNRS UMR 5309, INSERM U1209, University Grenoble Alpes, Allée des Alpes, 38700 La Tronche, France
| | - Eva Faurobert
- Institute for Advanced Biosciences, CNRS UMR 5309, INSERM U1209, University Grenoble Alpes, Allée des Alpes, 38700 La Tronche, France
| | - W Brent Derry
- Developmental and Stem Cell Biology Program, The Hospital for Sick Children, Peter Gilgan Centre for Research and Learning, 686 Bay Street, Toronto, ON M5G 0A4, Canada; Department of Molecular Genetics, University of Toronto, 1 King's College Circle, Toronto, ON M5S 1A8, Canada.
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12
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Rothman J, Jarriault S. Developmental Plasticity and Cellular Reprogramming in Caenorhabditis elegans. Genetics 2019; 213:723-757. [PMID: 31685551 PMCID: PMC6827377 DOI: 10.1534/genetics.119.302333] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2019] [Accepted: 07/25/2019] [Indexed: 12/28/2022] Open
Abstract
While Caenorhabditis elegans was originally regarded as a model for investigating determinate developmental programs, landmark studies have subsequently shown that the largely invariant pattern of development in the animal does not reflect irreversibility in rigidly fixed cell fates. Rather, cells at all stages of development, in both the soma and germline, have been shown to be capable of changing their fates through mutation or forced expression of fate-determining factors, as well as during the normal course of development. In this chapter, we review the basis for natural and induced cellular plasticity in C. elegans We describe the events that progressively restrict cellular differentiation during embryogenesis, starting with the multipotency-to-commitment transition (MCT) and subsequently through postembryonic development of the animal, and consider the range of molecular processes, including transcriptional and translational control systems, that contribute to cellular plasticity. These findings in the worm are discussed in the context of both classical and recent studies of cellular plasticity in vertebrate systems.
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Affiliation(s)
- Joel Rothman
- Department of MCD Biology and Neuroscience Research Institute, University of California, Santa Barbara, California 93111, and
| | - Sophie Jarriault
- IGBMC (Institut de Génétique et de Biologie Moléculaire et Cellulaire), Department of Development and Stem Cells, CNRS UMR7104, Inserm U1258, Université de Strasbourg, 67404 Illkirch CU Strasbourg, France
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13
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A Receptor Tyrosine Kinase Network Regulates Neuromuscular Function in Response to Oxidative Stress in Caenorhabditis elegans. Genetics 2019; 211:1283-1295. [PMID: 30782598 DOI: 10.1534/genetics.119.302026] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Accepted: 02/14/2019] [Indexed: 11/18/2022] Open
Abstract
The transcription factor Nrf2 plays a critical role in the organism-wide regulation of the antioxidant stress response. The Nrf2 homolog SKN-1 functions in the intestinal cells nonautonomously to negatively regulate neuromuscular junction (NMJ) function in Caenorhabditis elegans To identify additional molecules that mediate SKN-1 signaling to the NMJ, we performed a candidate screen for suppressors of aldicarb resistance caused by acute treatment with the SKN-1 activator arsenite. We identified two receptor tyrosine kinases, EGL-15 (fibroblast growth factor receptor, FGFR) and DAF-2 (insulin-like peptide receptor), that are required for NMJ regulation in response to stress. Through double-mutant analysis, we found that EGL-15 functions downstream of, or parallel to, SKN-1 and SPHK-1 (sphingosine kinase), and that the EGL-15 ligand EGL-17 FGF and canonical EGL-15 effectors are required for oxidative stress-mediated regulation of NMJ function. DAF-2 also functions downstream of or parallel to SKN-1 to regulate NMJ function. Through tissue-specific rescue experiments, we found that FGFR signaling functions primarily in the hypodermis, whereas insulin-like peptide receptor signaling is required in multiple tissues. Our results support the idea that the regulation of NMJ function by SKN-1 occurs via a complex organism-wide signaling network involving receptor tyrosine kinase signaling in multiple tissues.
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14
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Cohen JD, Flatt KM, Schroeder NE, Sundaram MV. Epithelial Shaping by Diverse Apical Extracellular Matrices Requires the Nidogen Domain Protein DEX-1 in Caenorhabditis elegans. Genetics 2019; 211:185-200. [PMID: 30409789 PMCID: PMC6325709 DOI: 10.1534/genetics.118.301752] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2018] [Accepted: 11/05/2018] [Indexed: 02/06/2023] Open
Abstract
The body's external surfaces and the insides of biological tubes, like the vascular system, are lined by a lipid-, glycoprotein-, and glycosaminoglycan-rich apical extracellular matrix (aECM). aECMs are the body's first line of defense against infectious agents and promote tissue integrity and morphogenesis, but are poorly described relative to basement membranes and stromal ECMs. While some aECM components, such as zona pellucida (ZP) domain proteins, have been identified, little is known regarding the overall composition of the aECM or the mechanisms by which different aECM components work together to shape epithelial tissues. In Caenorhabditis elegans, external epithelia develop in the context of an ill-defined ZP-containing aECM that precedes secretion of the collagenous cuticle. C. elegans has 43 genes that encode at least 65 unique ZP proteins, and we show that some of these comprise distinct precuticle aECMs in the embryo. Previously, the nidogen- and EGF-domain protein DEX-1 was shown to anchor dendrites to the C. elegans nose tip in concert with the ZP protein DYF-7 Here, we identified a new, strong loss-of-function allele of dex-1, cs201dex-1 mutants die as L1 larvae and have a variety of tissue distortion phenotypes, including excretory defects, pharyngeal ingression, alae defects, and a short and fat body shape, that strongly resemble those of genes encoding ZP proteins. DEX-1 localizes to ZP-containing aECMs in the tissues that show defects in dex-1 mutants. Our studies suggest that DEX-1 is a component of multiple distinct embryonic aECMs that shape developing epithelia, and a potential partner of multiple ZP proteins.
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Affiliation(s)
- Jennifer D Cohen
- Department of Genetics, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania 19104
| | - Kristen M Flatt
- Program in Neuroscience, University of Illinois at Urbana-Champaign, Illinois 61801-4730
| | - Nathan E Schroeder
- Program in Neuroscience, University of Illinois at Urbana-Champaign, Illinois 61801-4730
- Department of Crop Sciences, University of Illinois at Urbana-Champaign, Illinois 61801-4730
| | - Meera V Sundaram
- Department of Genetics, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania 19104
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15
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Rasmussen NR, Dickinson DJ, Reiner DJ. Ras-Dependent Cell Fate Decisions Are Reinforced by the RAP-1 Small GTPase in Caenorhabditiselegans. Genetics 2018; 210:1339-1354. [PMID: 30257933 PMCID: PMC6283165 DOI: 10.1534/genetics.118.301601] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2018] [Accepted: 09/15/2018] [Indexed: 12/15/2022] Open
Abstract
The notoriety of the small GTPase Ras as the most mutated oncoprotein has led to a well-characterized signaling network largely conserved across metazoans. Yet the role of its close relative Rap1 (Ras Proximal), which shares 100% identity between their core effector binding sequences, remains unclear. A long-standing controversy in the field is whether Rap1 also functions to activate the canonical Ras effector, the S/T kinase Raf. We used the developmentally simpler Caenorhabditis elegans, which lacks the extensive paralog redundancy of vertebrates, to examine the role of RAP-1 in two distinct LET-60/Ras-dependent cell fate patterning events: induction of 1° vulval precursor cell (VPC) fate and of the excretory duct cell. Fluorescence-tagged endogenous RAP-1 is localized to plasma membranes and is expressed ubiquitously, with even expression levels across the VPCs. RAP-1 and its activating GEF PXF-1 function cell autonomously and are necessary for maximal induction of 1° VPCs. Critically, mutationally activated endogenous RAP-1 is sufficient both to induce ectopic 1°s and duplicate excretory duct cells. Like endogenous RAP-1, before induction GFP expression from the pxf-1 promoter is uniform across VPCs. However, unlike endogenous RAP-1, after induction GFP expression is increased in presumptive 1°s and decreased in presumptive 2°s. We conclude that RAP-1 is a positive regulator that promotes Ras-dependent inductive fate decisions. We hypothesize that PXF-1 activation of RAP-1 serves as a minor parallel input into the major LET-60/Ras signal through LIN-45/Raf.
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Affiliation(s)
- Neal R Rasmussen
- Institute of Biosciences and Technology, College of Medicine, Texas A&M University, Houston, Texas 77030
| | - Daniel J Dickinson
- Department of Molecular Biosciences, University of Texas, Austin, Texas 78705
| | - David J Reiner
- Institute of Biosciences and Technology, College of Medicine, Texas A&M University, Houston, Texas 77030
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16
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The AFF-1 exoplasmic fusogen is required for endocytic scission and seamless tube elongation. Nat Commun 2018; 9:1741. [PMID: 29717108 PMCID: PMC5931541 DOI: 10.1038/s41467-018-04091-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2017] [Accepted: 04/03/2018] [Indexed: 12/28/2022] Open
Abstract
Many membranes must merge during cellular trafficking, but fusion and fission events initiating at exoplasmic (non-cytosolic) membrane surfaces are not well understood. Here we show that the C. elegans cell-cell fusogen anchor-cell fusion failure 1 (AFF-1) is required for membrane trafficking events during development of a seamless unicellular tube. EGF-Ras-ERK signaling upregulates AFF-1 expression in the excretory duct tube to promote tube auto-fusion and subsequent lumen elongation. AFF-1 is required for scission of basal endocytic compartments and for apically directed exocytosis to extend the apical membrane. Lumen elongation also requires the transcytosis factor Rab11, but occurs independently of dynamin and clathrin. These results support a transcytosis model of seamless tube lumen growth and show that cell-cell fusogens also can play roles in intracellular membrane trafficking events.
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Abstract
Cell-cell fusion is essential for fertilization and organ development. Dedicated proteins known as fusogens are responsible for mediating membrane fusion. However, until recently, these proteins either remained unidentified or were poorly understood at the mechanistic level. Here, we review how fusogens surmount multiple energy barriers to mediate cell-cell fusion. We describe how early preparatory steps bring membranes to a distance of ∼10 nm, while fusogens act in the final approach between membranes. The mechanical force exerted by cell fusogens and the accompanying lipidic rearrangements constitute the hallmarks of cell-cell fusion. Finally, we discuss the relationship between viral and eukaryotic fusogens, highlight a classification scheme regrouping a superfamily of fusogens called Fusexins, and propose new questions and avenues of enquiry.
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Affiliation(s)
- Javier M Hernández
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, D-44227 Dortmund, Germany
| | - Benjamin Podbilewicz
- Department of Biology, Technion - Israel Institute of Technology, Haifa 32000, Israel
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18
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Rapti G, Li C, Shan A, Lu Y, Shaham S. Glia initiate brain assembly through noncanonical Chimaerin-Furin axon guidance in C. elegans. Nat Neurosci 2017; 20:1350-1360. [PMID: 28846083 PMCID: PMC5614858 DOI: 10.1038/nn.4630] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2017] [Accepted: 07/19/2017] [Indexed: 01/08/2023]
Abstract
Brain assembly is hypothesized to begin when pioneer axons extend over non-neuronal cells, forming tracts guiding follower axons. Yet pioneer-neuron identities, their guidance substrates, and their interactions are not well understood. Here, using time-lapse embryonic imaging, genetics, protein-interaction, and functional studies, we uncover the early events of C. elegans brain assembly. We demonstrate that C. elegans glia are key for assembly initiation, guiding pioneer and follower axons using distinct signals. Pioneer sublateral neurons, with unique growth properties, anatomy, and innervation, cooperate with glia to mediate follower-axon guidance. We further identify a Chimaerin (CHIN-1)- Furin (KPC-1) double-mutant that severely disrupts assembly. CHIN-1 and KPC-1 function noncanonically, in glia and pioneer neurons, for guidance-cue trafficking. We exploit this bottleneck to define roles for glial Netrin and Semaphorin in pioneer- and follower-axon guidance, respectively, and for glial and pioneer-neuron Flamingo (CELSR) in follower-axon navigation. Taken together, our studies reveal previously undescribed glial roles in pioneer-axon guidance, suggesting conserved principles of brain assembly.
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Affiliation(s)
- Georgia Rapti
- Laboratory of Developmental Genetics, The Rockefeller University, 1230 York Avenue, New York, NY 10065 USA
| | - Chang Li
- Laboratory of Developmental Genetics, The Rockefeller University, 1230 York Avenue, New York, NY 10065 USA
- These authors contributed equally to this work
| | - Alan Shan
- Laboratory of Developmental Genetics, The Rockefeller University, 1230 York Avenue, New York, NY 10065 USA
- These authors contributed equally to this work
| | - Yun Lu
- Laboratory of Developmental Genetics, The Rockefeller University, 1230 York Avenue, New York, NY 10065 USA
| | - Shai Shaham
- Laboratory of Developmental Genetics, The Rockefeller University, 1230 York Avenue, New York, NY 10065 USA
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19
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Hall DH. Gap junctions in C. elegans: Their roles in behavior and development. Dev Neurobiol 2017; 77:587-596. [PMID: 27294317 PMCID: PMC5412865 DOI: 10.1002/dneu.22408] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2016] [Revised: 06/08/2016] [Accepted: 06/08/2016] [Indexed: 01/07/2023]
Abstract
The nematode Caenorhabditis elegans utilizes gap junctions in different fashions in virtually all of its cells. This model animal has a surprisingly large number of innexin genes within its genome, and many nematode cell types can express multiple innexins at once, leading to the formation of diverse junction types and enough redundancy to limit the effect of single gene knockdowns on animal development or behavioral phenotypes. Here, we review the general properties of these junctions, their expression patterns, and their known roles in tissue development and in the animal's connectome. © 2016 Wiley Periodicals, Inc. Develop Neurobiol 77: 587-596, 2017.
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Affiliation(s)
- David H Hall
- Department of Neuroscience, Center for C. elegans Anatomy, Albert Einstein College of Medicine, Bronx, New York, 10461
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20
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Pu P, Stone CE, Burdick JT, Murray JI, Sundaram MV. The Lipocalin LPR-1 Cooperates with LIN-3/EGF Signaling To Maintain Narrow Tube Integrity in Caenorhabditis elegans. Genetics 2017; 205:1247-1260. [PMID: 28040739 PMCID: PMC5340336 DOI: 10.1534/genetics.116.195156] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2016] [Accepted: 12/21/2016] [Indexed: 11/18/2022] Open
Abstract
Lipocalins are secreted cup-shaped glycoproteins that bind sterols, fatty acids, and other lipophilic molecules. Lipocalins have been implicated in a wide array of processes related to lipophilic cargo transport, sequestration, and signaling, and several are used as biomarkers for human disease, but the functions of most lipocalins remain poorly understood. Here we show that the Caenorhabditis elegans lipocalin LPR-1 is required to maintain apical membrane integrity and a continuous lumen in two narrow unicellular tubes, the excretory duct and pore, during a period of rapid lumen elongation. LPR-1 fusion protein is expressed by the duct and pore and accumulates both intracellularly and in apical extracellular compartments, but it can also function cell nonautonomously when provided from outside of the excretory system. lpr-1 mutant defects can be rescued by increased signaling through the epidermal growth factor (EGF)-Ras-extracellular signal regulated kinase (ERK) pathway, which promotes the more elongated duct vs. less elongated pore tube fate. Spatial and temporal rescue experiments indicate that Ras signaling acts within the duct and pore tubes during or prior to cell fate determination to bypass the requirement for LPR-1 lpr-1 mutations did not disrupt LIN-3/EGF-dependent duct-fate specification, prevent functioning of any specific LIN-3/EGF isoform, or alter LET-23/EGFR localization, and reduced signaling did not phenocopy or enhance lpr-1 mutant defects. These data suggest that LPR-1 protects lumen integrity through a LIN-3/EGF-independent mechanism, but that increased signaling upregulates some target(s) that can compensate for lpr-1 absence.
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Affiliation(s)
- Pu Pu
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - Craig E Stone
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - Joshua T Burdick
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - John I Murray
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - Meera V Sundaram
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104
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The Caenorhabditis elegans Excretory System: A Model for Tubulogenesis, Cell Fate Specification, and Plasticity. Genetics 2017; 203:35-63. [PMID: 27183565 DOI: 10.1534/genetics.116.189357] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Accepted: 03/07/2016] [Indexed: 12/12/2022] Open
Abstract
The excretory system of the nematode Caenorhabditis elegans is a superb model of tubular organogenesis involving a minimum of cells. The system consists of just three unicellular tubes (canal, duct, and pore), a secretory gland, and two associated neurons. Just as in more complex organs, cells of the excretory system must first adopt specific identities and then coordinate diverse processes to form tubes of appropriate topology, shape, connectivity, and physiological function. The unicellular topology of excretory tubes, their varied and sometimes complex shapes, and the dynamic reprogramming of cell identity and remodeling of tube connectivity that occur during larval development are particularly fascinating features of this organ. The physiological roles of the excretory system in osmoregulation and other aspects of the animal's life cycle are only beginning to be explored. The cellular mechanisms and molecular pathways used to build and shape excretory tubes appear similar to those used in both unicellular and multicellular tubes in more complex organs, such as the vertebrate vascular system and kidney, making this simple organ system a useful model for understanding disease processes.
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22
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Nagasawa-Masuda A, Terai K. ERK activation in endothelial cells is a novel marker during neovasculogenesis. Genes Cells 2016; 21:1164-1175. [PMID: 27696620 DOI: 10.1111/gtc.12438] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2016] [Accepted: 08/16/2016] [Indexed: 01/01/2023]
Abstract
Vasculogenesis is essential during early development to construct networks transporting oxygen, blood and nutrients. Tip and stalk cells are specialized endothelial cells involved in novel vessel formation because of their behavior such as sprouting as a leading cell and following tip cell. However, the spatiotemporal details determining the emergence of these cells are unknown. Here, we first show that the ERK activity in endothelial cells represents the precursor of tip and stalk cells for vasculogenesis in zebrafish. We identified that tip and stalk cells for intersegmental vessel (ISV) formation were already specialized in the dorsal aorta (DA) before sprouting. Furthermore, similar specialization was observed in tip cells during parachordal vessel (PAV) formation in lymphangiogenesis. We also identified that the ERK activity was required for specialized cells to emerge from existing blood vessels. Our data show that the ERK activity is a novel marker for determining the emergence of cells in both angiogenesis and lymphangiogenesis.
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Affiliation(s)
- Ayumi Nagasawa-Masuda
- Laboratory of Function and Morphology, Institute of Molecular and Cellular Biosciences, The University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo, 113-0032, Japan
| | - Kenta Terai
- Laboratory of Function and Morphology, Institute of Molecular and Cellular Biosciences, The University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo, 113-0032, Japan
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23
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Gill HK, Cohen JD, Ayala-Figueroa J, Forman-Rubinsky R, Poggioli C, Bickard K, Parry JM, Pu P, Hall DH, Sundaram MV. Integrity of Narrow Epithelial Tubes in the C. elegans Excretory System Requires a Transient Luminal Matrix. PLoS Genet 2016; 12:e1006205. [PMID: 27482894 PMCID: PMC4970718 DOI: 10.1371/journal.pgen.1006205] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2015] [Accepted: 06/28/2016] [Indexed: 02/07/2023] Open
Abstract
Most epithelial cells secrete a glycoprotein-rich apical extracellular matrix that can have diverse but still poorly understood roles in development and physiology. Zona Pellucida (ZP) domain glycoproteins are common constituents of these matrices, and their loss in humans is associated with a number of diseases. Understanding of the functions, organization and regulation of apical matrices has been hampered by difficulties in imaging them both in vivo and ex vivo. We identified the PAN-Apple, mucin and ZP domain glycoprotein LET-653 as an early and transient apical matrix component that shapes developing epithelia in C. elegans. LET-653 has modest effects on shaping of the vulva and epidermis, but is essential to prevent lumen fragmentation in the very narrow, unicellular excretory duct tube. We were able to image the transient LET-653 matrix by both live confocal imaging and transmission electron microscopy. Structure/function and fluorescence recovery after photobleaching studies revealed that LET-653 exists in two separate luminal matrix pools, a loose fibrillar matrix in the central core of the lumen, to which it binds dynamically via its PAN domains, and an apical-membrane-associated matrix, to which it binds stably via its ZP domain. The PAN domains are both necessary and sufficient to confer a cyclic pattern of duct lumen localization that precedes each molt, while the ZP domain is required for lumen integrity. Ectopic expression of full-length LET-653, but not the PAN domains alone, could expand lumen diameter in the developing gut tube, where LET-653 is not normally expressed. Together, these data support a model in which the PAN domains regulate the ability of the LET-653 ZP domain to interact with other factors at the apical membrane, and this ZP domain interaction promotes expansion and maintenance of lumen diameter. These data identify a transient apical matrix component present prior to cuticle secretion in C. elegans, demonstrate critical roles for this matrix component in supporting lumen integrity within narrow bore tubes such as those found in the mammalian microvasculature, and reveal functional importance of the evolutionarily conserved ZP domain in this tube protecting activity. Most organs in the body are made up of networks of tubes that transport fluids or gases. These tubes come in many different sizes and shapes, with some narrow capillaries being only one cell in diameter. As tubes develop and take their final shapes, they secrete various glycoproteins into their hollow interior or lumen. The functions of these luminal proteins are not well understood, but there is increasing evidence that they are important for lumen shaping and that their loss can contribute to diseases such as cardiovascular disease and chronic kidney disease. Through studies of the nematode C. elegans, we identified a luminal glycoprotein, LET-653, that is transiently expressed in multiple developing tube types but is particularly critical to maintain integrity of the narrowest, unicellular tubes. We identified protein domains that direct LET-653 to specific apical matrix compartments and mediate its oscillatory pattern of lumen localization. Furthermore, we showed that the LET-653 tube-protecting activity depends on a Zona Pellucida (ZP) domain similar to that found in the mammalian egg-coat and in many other luminal or sensory matrix proteins involved in human disease.
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Affiliation(s)
- Hasreet K. Gill
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Jennifer D. Cohen
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Jesus Ayala-Figueroa
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Rachel Forman-Rubinsky
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Corey Poggioli
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Kevin Bickard
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Jean M. Parry
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
- Department of Biology, Georgian Court University, Lakewood, New Jersey, United States of America
| | - Pu Pu
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - David H. Hall
- Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York, United States of America
| | - Meera V. Sundaram
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
- * E-mail:
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24
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Soulavie F, Sundaram MV. Auto-fusion and the shaping of neurons and tubes. Semin Cell Dev Biol 2016; 60:136-145. [PMID: 27436685 DOI: 10.1016/j.semcdb.2016.07.018] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2016] [Revised: 07/15/2016] [Accepted: 07/15/2016] [Indexed: 12/14/2022]
Abstract
Cells adopt specific shapes that are necessary for specific functions. For example, some neurons extend elaborate arborized dendrites that can contact multiple targets. Epithelial and endothelial cells can form tiny seamless unicellular tubes with an intracellular lumen. Recent advances showed that cells can auto-fuse to acquire those specific shapes. During auto-fusion, a cell merges two parts of its own plasma membrane. In contrast to cell-cell fusion or macropinocytic fission, which result in the merging or formation of two separate membrane bound compartments, auto-fusion preserves one compartment, but changes its shape. The discovery of auto-fusion in C. elegans was enabled by identification of specific protein fusogens, EFF-1 and AFF-1, that mediate cell-cell fusion. Phenotypic characterization of eff-1 and aff-1 mutants revealed that fusogen-mediated fusion of two parts of the same cell can be used to sculpt dendritic arbors, reconnect two parts of an axon after injury, or form a hollow unicellular tube. Similar auto-fusion events recently were detected in vertebrate cells, suggesting that auto-fusion could be a widely used mechanism for shaping neurons and tubes.
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Affiliation(s)
- Fabien Soulavie
- Department of Genetics, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA 19104,United States
| | - Meera V Sundaram
- Department of Genetics, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA 19104,United States.
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25
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Sundaram MV, Cohen JD. Time to make the doughnuts: Building and shaping seamless tubes. Semin Cell Dev Biol 2016; 67:123-131. [PMID: 27178486 DOI: 10.1016/j.semcdb.2016.05.006] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2015] [Revised: 05/04/2016] [Accepted: 05/06/2016] [Indexed: 10/21/2022]
Abstract
A seamless tube is a very narrow-bore tube that is composed of a single cell with an intracellular lumen and no adherens or tight junctions along its length. Many capillaries in the vertebrate vascular system are seamless tubes. Seamless tubes also are found in invertebrate organs, including the Drosophila trachea and the Caenorhabditis elegans excretory system. Seamless tube cells can be less than a micron in diameter, and they can adopt very simple "doughnut-like" shapes or very complex, branched shapes comparable to those of neurons. The unusual topology and varied shapes of seamless tubes raise many basic cell biological questions about how cells form and maintain such structures. The prevalence of seamless tubes in the vascular system means that answering such questions has significant relevance to human health. In this review, we describe selected examples of seamless tubes in animals and discuss current models for how seamless tubes develop and are shaped, focusing particularly on insights that have come from recent studies in Drosophila and C. elegans.
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Affiliation(s)
- Meera V Sundaram
- Dept. of Genetics, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA.
| | - Jennifer D Cohen
- Dept. of Genetics, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA
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26
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Zacharias AL, Walton T, Preston E, Murray JI. Quantitative Differences in Nuclear β-catenin and TCF Pattern Embryonic Cells in C. elegans. PLoS Genet 2015; 11:e1005585. [PMID: 26488501 PMCID: PMC4619327 DOI: 10.1371/journal.pgen.1005585] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Accepted: 09/16/2015] [Indexed: 12/22/2022] Open
Abstract
The Wnt signaling pathway plays a conserved role during animal development in transcriptional regulation of distinct targets in different developmental contexts but it remains unclear whether quantitative differences in the nuclear localization of effector proteins TCF and β-catenin contribute to context-specific regulation. We investigated this question in Caenorhabditis elegans embryos by quantifying nuclear localization of fluorescently tagged SYS-1/β-catenin and POP-1/TCF and expression of Wnt ligands at cellular resolution by time-lapse microscopy and automated lineage tracing. We identified reproducible, quantitative differences that generate a subset of Wnt-signaled cells with a significantly higher nuclear concentration of the TCF/β-catenin activating complex. Specifically, β-catenin and TCF are preferentially enriched in nuclei of daughter cells whose parents also had high nuclear levels of that protein, a pattern that could influence developmental gene expression. Consistent with this, we found that expression of synthetic reporters of POP-1-dependent activation is biased towards cells that had high nuclear SYS-1 in consecutive divisions. We identified new genes whose embryonic expression patterns depend on pop-1. Most of these require POP-1 for either transcriptional activation or repression, and targets requiring POP-1 for activation are more likely to be expressed in the cells with high nuclear SYS-1 in consecutive divisions than those requiring POP-1 for repression. Taken together, these results indicate that SYS-1 and POP-1 levels are influenced by the parent cell’s SYS-1/POP-1 levels and this may provide an additional mechanism by which POP-1 regulates distinct targets in different developmental contexts. The Wnt signaling pathway is active during the development of all multi-cellular animals and also improperly re-activated in many cancers. Here, we use time-lapse microscopy to quantify the nuclear localization of several proteins in response to Wnt signaling throughout early embryonic development in the nematode worm, C. elegans. We find that cells that received a Wnt signal in the previous division respond more strongly to a Wnt signal in the next division, in part by localizing more of the regulator β-catenin to the nucleus. This causes the relative enrichment of Wnt pathway proteins in the nuclei of repeatedly signaled cells, which we show likely impacts the activation of Wnt target genes. This represents a novel mechanism for the regulation of Wnt pathway targets in development and disease.
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Affiliation(s)
- Amanda L. Zacharias
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Travis Walton
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Elicia Preston
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - John Isaac Murray
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
- * E-mail:
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27
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Geary JF, Lovato R, Wanji S, Guderian R, O'Neill M, Specht S, Madrill N, Geary TG, Mackenzie CD. A histochemical study of the Nras/let-60 activity in filarial nematodes. Parasit Vectors 2015; 8:353. [PMID: 26130134 PMCID: PMC4493820 DOI: 10.1186/s13071-015-0947-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2015] [Accepted: 06/10/2015] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Control and elimination of filarial pathogens is a central focus of major global health efforts directed at parasitic diseases of developing countries. Accomplishment of these goals would be markedly enhanced by the enhanced destruction of the adult stage of filariae. The identification of new, more quantitative biomarkers that correlate with mortality or chemotherapeutic damage to adult filariae, would greatly facilitate, for example, the development of new macrofilaricides. METHODS An immunocytochemical approach using an antibody against human Nras was used to identify and detect changes in the nematode homolog let-60 that is associated with cell growth and maintenance. Single Onchocerca volvulus nodules were removed from each of 13 patients treated with ivermectin (as part of a community-wide mass drug administration programme), and from each of 13 untreated individuals; these 26 nodules were stained with the anti-Nras antibody. The localization and degree of positivity of Nras/let-60 staining were assessed subjectively and compared between the two groups; the positivity of staining was also quantified, using image analysis, in a subgroup of these nodules. In addition, the specific morphological association between Nras/let-60 and the Wolbachia endosymbiont present in these parasites was also observed in 4 additional filarial species using an anti-Wolbachia surface protein (WSP) antibody under light and confocal microscopy. RESULTS Nras/let-60 is present in many structures within the adult female worms. A statistically significant decrease in the general staining intensity of Nras/let-60 was observed in adult female O. volvulus treated with ivermectin when compared with parasites from untreated patients. Nras/let-60 staining was frequently observed to be co-localized with WSP in O.volvulus, Brugia malayi, Litomosoides sigmodontis and Dirofilaria immitis. Nras/let60 is also present in Onchocerca ochengi. CONCLUSION Nras/let-60, as detected by immunocytochemical staining, is decreased in ivermectin-treated adult female O. volvulus relative to untreated control specimens, suggesting a suppressive effect of ivermectin on the overall biochemical activity of these parasites. Co-localization of Nras/let-60 and WSP suggests the possibility that the endosymbiont utilizes this nematode protein as part of a mutualistic relationship. Nras/let60 appears to be a useful biomarker for assessing the health of filariae.
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Affiliation(s)
- James F Geary
- Department of Pathobiology and Diagnostic Investigation, Michigan State University, East Lansing, MI, 48824, USA.
| | - Raquel Lovato
- Ecuadorian Onchocerciasis Control Program, Ministry of Health, Quito, Ecuador.
| | - Samuel Wanji
- Research Foundation for Tropical Diseases and Environment, P.O. Box, 474, Buea, Cameroon.
| | - Ron Guderian
- Ecuadorian Onchocerciasis Control Program, Ministry of Health, Quito, Ecuador.
- Hospital Vozandes, Quito, Ecuador.
| | - Maeghan O'Neill
- Institute of Parasitology, Macdonald Campus, McGill University, Ste-Anne-de-Bellevue, QC, H9X 3V9, Canada.
| | - Sabine Specht
- Institute for Medical Microbiology, University Hospital Bonn, Bonn, Germany.
| | - Nicole Madrill
- Department of Pathobiology and Diagnostic Investigation, Michigan State University, East Lansing, MI, 48824, USA.
| | - Timothy G Geary
- Institute of Parasitology, Macdonald Campus, McGill University, Ste-Anne-de-Bellevue, QC, H9X 3V9, Canada.
| | - Charles D Mackenzie
- Department of Pathobiology and Diagnostic Investigation, Michigan State University, East Lansing, MI, 48824, USA.
- Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L35QA, UK.
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Hench J, Henriksson J, Abou-Zied AM, Lüppert M, Dethlefsen J, Mukherjee K, Tong YG, Tang L, Gangishetti U, Baillie DL, Bürglin TR. The Homeobox Genes of Caenorhabditis elegans and Insights into Their Spatio-Temporal Expression Dynamics during Embryogenesis. PLoS One 2015; 10:e0126947. [PMID: 26024448 PMCID: PMC4448998 DOI: 10.1371/journal.pone.0126947] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2015] [Accepted: 04/09/2015] [Indexed: 11/18/2022] Open
Abstract
Homeobox genes play crucial roles for the development of multicellular eukaryotes. We have generated a revised list of all homeobox genes for Caenorhabditis elegans and provide a nomenclature for the previously unnamed ones. We show that, out of 103 homeobox genes, 70 are co-orthologous to human homeobox genes. 14 are highly divergent, lacking an obvious ortholog even in other Caenorhabditis species. One of these homeobox genes encodes 12 homeodomains, while three other highly divergent homeobox genes encode a novel type of double homeodomain, termed HOCHOB. To understand how transcription factors regulate cell fate during development, precise spatio-temporal expression data need to be obtained. Using a new imaging framework that we developed, Endrov, we have generated spatio-temporal expression profiles during embryogenesis of over 60 homeobox genes, as well as a number of other developmental control genes using GFP reporters. We used dynamic feedback during recording to automatically adjust the camera exposure time in order to increase the dynamic range beyond the limitations of the camera. We have applied the new framework to examine homeobox gene expression patterns and provide an analysis of these patterns. The methods we developed to analyze and quantify expression data are not only suitable for C. elegans, but can be applied to other model systems or even to tissue culture systems.
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Affiliation(s)
- Jürgen Hench
- Dept. of Biosciences and Nutrition & Center for Biosciences, Karolinska Institutet, Hälsovägen 7, Novum, SE-141 83, Huddinge, Sweden
- School of Life Sciences, Södertörns Högskola, Huddinge, Sweden
| | - Johan Henriksson
- Dept. of Biosciences and Nutrition & Center for Biosciences, Karolinska Institutet, Hälsovägen 7, Novum, SE-141 83, Huddinge, Sweden
- School of Life Sciences, Södertörns Högskola, Huddinge, Sweden
| | - Akram M. Abou-Zied
- Dept. of Biosciences and Nutrition & Center for Biosciences, Karolinska Institutet, Hälsovägen 7, Novum, SE-141 83, Huddinge, Sweden
- School of Life Sciences, Södertörns Högskola, Huddinge, Sweden
| | - Martin Lüppert
- Dept. of Biosciences and Nutrition & Center for Biosciences, Karolinska Institutet, Hälsovägen 7, Novum, SE-141 83, Huddinge, Sweden
- School of Life Sciences, Södertörns Högskola, Huddinge, Sweden
| | - Johan Dethlefsen
- Dept. of Biosciences and Nutrition & Center for Biosciences, Karolinska Institutet, Hälsovägen 7, Novum, SE-141 83, Huddinge, Sweden
- School of Life Sciences, Södertörns Högskola, Huddinge, Sweden
| | - Krishanu Mukherjee
- Dept. of Biosciences and Nutrition & Center for Biosciences, Karolinska Institutet, Hälsovägen 7, Novum, SE-141 83, Huddinge, Sweden
- School of Life Sciences, Södertörns Högskola, Huddinge, Sweden
| | - Yong Guang Tong
- Dept. of Biosciences and Nutrition & Center for Biosciences, Karolinska Institutet, Hälsovägen 7, Novum, SE-141 83, Huddinge, Sweden
- School of Life Sciences, Södertörns Högskola, Huddinge, Sweden
| | - Lois Tang
- Dept. of Biosciences and Nutrition & Center for Biosciences, Karolinska Institutet, Hälsovägen 7, Novum, SE-141 83, Huddinge, Sweden
- School of Life Sciences, Södertörns Högskola, Huddinge, Sweden
| | - Umesh Gangishetti
- Dept. of Biosciences and Nutrition & Center for Biosciences, Karolinska Institutet, Hälsovägen 7, Novum, SE-141 83, Huddinge, Sweden
| | - David L. Baillie
- Dept. of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, British Columbia, V5A 1S6, Canada
| | - Thomas R. Bürglin
- Dept. of Biosciences and Nutrition & Center for Biosciences, Karolinska Institutet, Hälsovägen 7, Novum, SE-141 83, Huddinge, Sweden
- School of Life Sciences, Södertörns Högskola, Huddinge, Sweden
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29
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Shaye DD, Greenwald I. The disease-associated formin INF2/EXC-6 organizes lumen and cell outgrowth during tubulogenesis by regulating F-actin and microtubule cytoskeletons. Dev Cell 2015; 32:743-55. [PMID: 25771894 DOI: 10.1016/j.devcel.2015.01.009] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2014] [Revised: 12/02/2014] [Accepted: 01/13/2015] [Indexed: 10/23/2022]
Abstract
We investigate how outgrowth at the basolateral cell membrane is coordinated with apical lumen formation in the development of a biological tube by characterizing exc-6, a gene required for C. elegans excretory cell (EC) tubulogenesis. We show that EXC-6 is orthologous to the human formin INF2, which polymerizes filamentous actin (F-actin) and binds microtubules (MTs) in vitro. Dominant INF2 mutations cause focal segmental glomerulosclerosis (FSGS), a kidney disease, and FSGS+Charcot-Marie-Tooth neuropathy. We show that activated INF2 can substitute for EXC-6 in C. elegans and that disease-associated mutations cause constitutive activity. Using genetic analysis and live imaging, we show that exc-6 regulates MT and F-actin accumulation at EC tips and dynamics of basolateral-localized MTs, indicating that EXC-6 organizes F-actin and MT cytoskeletons during tubulogenesis. The pathology associated with INF2 mutations is believed to reflect misregulation of F-actin, but our results suggest alternative or additional mechanisms via effects on MT dynamics.
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Affiliation(s)
- Daniel D Shaye
- Howard Hughes Medical Institute, Columbia University, College of Physicians and Surgeons, New York, NY 10032, USA.
| | - Iva Greenwald
- Howard Hughes Medical Institute, Columbia University, College of Physicians and Surgeons, New York, NY 10032, USA; Department of Biochemistry and Molecular Biophysics, Columbia University, College of Physicians and Surgeons, New York, NY 10032, USA; Department of Genetics and Development, Columbia University, College of Physicians and Surgeons, New York, NY 10032, USA.
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30
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Walton T, Preston E, Nair G, Zacharias AL, Raj A, Murray JI. The Bicoid class homeodomain factors ceh-36/OTX and unc-30/PITX cooperate in C. elegans embryonic progenitor cells to regulate robust development. PLoS Genet 2015; 11:e1005003. [PMID: 25738873 PMCID: PMC4349592 DOI: 10.1371/journal.pgen.1005003] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2014] [Accepted: 01/14/2015] [Indexed: 01/30/2023] Open
Abstract
While many transcriptional regulators of pluripotent and terminally differentiated states have been identified, regulation of intermediate progenitor states is less well understood. Previous high throughput cellular resolution expression studies identified dozens of transcription factors with lineage-specific expression patterns in C. elegans embryos that could regulate progenitor identity. In this study we identified a broad embryonic role for the C. elegans OTX transcription factor ceh-36, which was previously shown to be required for the terminal specification of four neurons. ceh-36 is expressed in progenitors of over 30% of embryonic cells, yet is not required for embryonic viability. Quantitative phenotyping by computational analysis of time-lapse movies of ceh-36 mutant embryos identified cell cycle or cell migration defects in over 100 of these cells, but most defects were low-penetrance, suggesting redundancy. Expression of ceh-36 partially overlaps with that of the PITX transcription factor unc-30. unc-30 single mutants are viable but loss of both ceh-36 and unc-30 causes 100% lethality, and double mutants have significantly higher frequencies of cellular developmental defects in the cells where their expression normally overlaps. These factors are also required for robust expression of the downstream developmental regulator mls-2/HMX. This work provides the first example of genetic redundancy between the related yet evolutionarily distant OTX and PITX families of bicoid class homeodomain factors and demonstrates the power of quantitative developmental phenotyping in C. elegans to identify developmental regulators acting in progenitor cells.
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Affiliation(s)
- Travis Walton
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Elicia Preston
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Gautham Nair
- Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Amanda L. Zacharias
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Arjun Raj
- Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - John Isaac Murray
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
- Penn Genome Frontiers Institute, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
- * E-mail:
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31
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Parry JM, Sundaram MV. A non-cell-autonomous role for Ras signaling in C. elegans neuroblast delamination. Development 2015; 141:4279-84. [PMID: 25371363 DOI: 10.1242/dev.112045] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Receptor tyrosine kinase (RTK) signaling through Ras influences many aspects of normal cell behavior, including epithelial-to-mesenchymal transition, and aberrant signaling promotes both tumorigenesis and metastasis. Although many such effects are cell-autonomous, here we show a non-cell-autonomous role for RTK-Ras signaling in the delamination of a neuroblast from an epithelial organ. The C. elegans renal-like excretory organ is initially composed of three unicellular epithelial tubes, namely the canal, duct and G1 pore cells; however, the G1 cell later delaminates from the excretory system to become a neuroblast and is replaced by the G2 cell. G1 delamination and G2 intercalation involve cytoskeletal remodeling, interconversion of autocellular and intercellular junctions and migration over a luminal extracellular matrix, followed by G1 junction loss. LET-23/EGFR and SOS-1, an exchange factor for Ras, are required for G1 junction loss but not for initial cytoskeletal or junction remodeling. Surprisingly, expression of activated LET-60/Ras in the neighboring duct cell, but not in the G1 or G2 cells, is sufficient to rescue sos-1 delamination defects, revealing that Ras acts non-cell-autonomously to permit G1 delamination. We suggest that, similarly, oncogenic mutations in cells within a tumor might help create a microenvironment that is permissive for other cells to detach and ultimately metastasize.
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Affiliation(s)
- Jean M Parry
- Department of Genetics, University of Pennsylvania Perelman School of Medicine, 415 Curie Boulevard, Philadelphia, PA 19104, USA Department of Biology, Georgian Court University, 900 Lakewood Avenue, Lakewood, NJ 08701, USA
| | - Meera V Sundaram
- Department of Genetics, University of Pennsylvania Perelman School of Medicine, 415 Curie Boulevard, Philadelphia, PA 19104, USA
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32
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Wang X, Piccolo CW, Cohen BM, Buttner EA. Transient receptor potential melastatin (TRPM) channels mediate clozapine-induced phenotypes in Caenorhabditis elegans. J Neurogenet 2014; 28:86-97. [PMID: 24564792 DOI: 10.3109/01677063.2013.879717] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The molecular mechanisms of action of antipsychotic drugs (APDs) are not fully understood. Here, we characterize phenotypes of missense and knockout mutations in the Caenorhabditis elegans transient receptor potential melastatin (TRPM) channel ortholog gtl-2, a candidate APD target identified in a genome-wide RNAi (RNA interference) screen for Suppressors of Clozapine-induced Larval Arrest (scla genes). We then employ the developmental phenotypes of gtl-2(lf) mutants to validate our previous gtl-2(RNAi) result. GTL-2 acts in the excretory canal cell to regulate Mg(2+) homeostasis. Using exc (excretory canal abnormal) gene mutants, we demonstrate that excretory canal cell function is necessary for clozapine-induced developmental delay and lethality. Moreover, cell-specific promoter-driven expression studies reveal that GTL-2 function in the excretory canal cell is important for its role in the SCLA phenotype. We then investigate the mechanism by which GTL-2 function in the excretory canal cell impacts clozapine-induced phenotypes. gtl-2(lf) mutations cause hypermagnesemia, and we show that exposure of the wild-type strain to high Mg(2+) phenocopies gtl-2(lf) with respect to suppression of clozapine-induced developmental delay and lethality. Our results suggest that GTL-2 TRPM channel function in the excretory canal cell is important for clozapine's developmental effects. TRP channels are expressed in mammalian brain and are implicated in the pathogenesis of mental illnesses but have not been previously implicated in APD action.
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Affiliation(s)
- Xin Wang
- Department of Psychiatry, Harvard Medical School , Boston, Massachusetts , USA
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33
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Efficient single-cell transgene induction in Caenorhabditis elegans using a pulsed infrared laser. G3-GENES GENOMES GENETICS 2013; 3:1827-32. [PMID: 23979939 PMCID: PMC3789807 DOI: 10.1534/g3.113.007682] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The coupling of transgenes to heat shock promoters is a widely applied method for regulating gene expression. In C. elegans, gene induction can be controlled temporally through timing of heat shock and spatially via targeted rescue in heat shock mutants. Here, we present a method for evoking gene expression in arbitrary cells, with single-cell resolution. We use a focused pulsed infrared laser to locally induce a heat shock response in specific cells. Our method builds on and extends a previously reported method using a continuous-wave laser. In our technique, the pulsed laser illumination enables a much higher degree of spatial selectivity because of diffusion of heat between pulses. We apply our method to induce transient and long-term transgene expression in embryonic, larval, and adult cells. Our method allows highly selective spatiotemporal control of transgene expression and is a powerful tool for model organism biology.
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34
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Masoudi N, Fancsalszky L, Pourkarimi E, Vellai T, Alexa A, Reményi A, Gartner A, Mehta A, Takács-Vellai K. The NM23-H1/H2 homolog NDK-1 is required for full activation of Ras signaling in C. elegans. Development 2013; 140:3486-95. [PMID: 23900546 PMCID: PMC3737725 DOI: 10.1242/dev.094011] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/17/2013] [Indexed: 11/21/2022]
Abstract
The group I members of the Nm23 (non-metastatic) gene family encode nucleoside diphosphate kinases (NDPKs) that have been implicated in the regulation of cell migration, proliferation and differentiation. Despite their developmental and medical significance, the molecular functions of these NDPKs remain ill defined. To minimize confounding effects of functional compensation between closely related Nm23 family members, we studied ndk-1, the sole Caenorhabditis elegans ortholog of group I NDPKs, and focused on its role in Ras/mitogen-activated protein kinase (MAPK)-mediated signaling events during development. ndk-1 inactivation leads to a protruding vulva phenotype and affects vulval cell fate specification through the Ras/MAPK cascade. ndk-1 mutant worms show severe reduction of activated, diphosphorylated MAPK in somatic tissues, indicative of compromised Ras/MAPK signaling. A genetic epistasis analysis using the vulval induction system revealed that NDK-1 acts downstream of LIN-45/Raf, but upstream of MPK-1/MAPK, at the level of the kinase suppressors of ras (KSR-1/2). KSR proteins act as scaffolds facilitating Ras signaling events by tethering signaling components, and we suggest that NDK-1 modulates KSR activity through direct physical interaction. Our study reveals that C. elegans NDK-1/Nm23 influences differentiation by enhancing the level of Ras/MAPK signaling. These results might help to better understand how dysregulated Nm23 in humans contributes to tumorigenesis.
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Affiliation(s)
- Neda Masoudi
- Department of Genetics, Eötvös Loránd University, Pázmány Péter stny. 1/C, H-1117 Budapest, Hungary
- Wellcome Trust Centre for Gene Regulation and Expression, University of Dundee, Dow Street, Dundee DD1 5EH, UK
| | - Luca Fancsalszky
- Department of Genetics, Eötvös Loránd University, Pázmány Péter stny. 1/C, H-1117 Budapest, Hungary
| | - Ehsan Pourkarimi
- Department of Genetics, Eötvös Loránd University, Pázmány Péter stny. 1/C, H-1117 Budapest, Hungary
- Wellcome Trust Centre for Gene Regulation and Expression, University of Dundee, Dow Street, Dundee DD1 5EH, UK
| | - Tibor Vellai
- Department of Genetics, Eötvös Loránd University, Pázmány Péter stny. 1/C, H-1117 Budapest, Hungary
| | - Anita Alexa
- Department of Biochemistry, Eötvös Loránd University, Pázmány Péter stny. 1/C, H-1117 Budapest, Hungary
- Institute of Molecular Pharmacology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Pusztaszeri út 59-67, H-1025 Budapest, Hungary
| | - Attila Reményi
- Department of Biochemistry, Eötvös Loránd University, Pázmány Péter stny. 1/C, H-1117 Budapest, Hungary
- Institute of Molecular Pharmacology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Pusztaszeri út 59-67, H-1025 Budapest, Hungary
| | - Anton Gartner
- Wellcome Trust Centre for Gene Regulation and Expression, University of Dundee, Dow Street, Dundee DD1 5EH, UK
| | - Anil Mehta
- Division of Medical Sciences, Centre for CVS and Lung Biology, Ninewells Hospital Medical School, Dundee DD1 9SY, UK
| | - Krisztina Takács-Vellai
- Department of Genetics, Eötvös Loránd University, Pázmány Péter stny. 1/C, H-1117 Budapest, Hungary
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35
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Abstract
Receptor Tyrosine Kinase (RTK)-Ras-Extracellular signal-regulated kinase (ERK) signaling pathways control many aspects of C. elegans development and behavior. Studies in C. elegans helped elucidate the basic framework of the RTK-Ras-ERK pathway and continue to provide insights into its complex regulation, its biological roles, how it elicits cell-type appropriate responses, and how it interacts with other signaling pathways to do so. C. elegans studies have also revealed biological contexts in which alternative RTK- or Ras-dependent pathways are used instead of the canonical pathway.
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Affiliation(s)
- Meera V Sundaram
- Dept. of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104-6145, USA.
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36
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Choe KP. Physiological and molecular mechanisms of salt and water homeostasis in the nematode Caenorhabditis elegans. Am J Physiol Regul Integr Comp Physiol 2013; 305:R175-86. [PMID: 23739341 DOI: 10.1152/ajpregu.00109.2013] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Intracellular salt and water homeostasis is essential for all cellular life. Extracellular salt and water homeostasis is also important for multicellular organisms. Many fundamental mechanisms of compensation for osmotic perturbations are well defined and conserved. Alternatively, molecular mechanisms of detecting salt and water imbalances and regulating compensatory responses are generally poorly defined for animals. Throughout the last century, researchers studying vertebrates and vertebrate cells made critical contributions to our understanding of osmoregulation, especially mechanisms of salt and water transport and organic osmolyte accumulation. Researchers have more recently started using invertebrate model organisms with defined genomes and well-established methods of genetic manipulation to begin defining the genes and integrated regulatory networks that respond to osmotic stress. The nematode Caenorhabditis elegans is well suited to these studies. Here, I introduce osmoregulatory mechanisms in this model, discuss experimental advantages and limitations, and review important findings. Key discoveries include defining genetic mechanisms of osmolarity sensing in neurons, identifying protein damage as a sensor and principle determinant of hypertonic stress resistance, and identification of a putative sensor for hypertonic stress associated with the extracellular matrix. Many of these processes and pathways are conserved and, therefore, provide new insights into salt and water homeostasis in other animals, including mammals.
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Affiliation(s)
- Keith P Choe
- Department of Biology and Genetics Institute, University of Florida, Gainesville, FL 32611, USA.
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37
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Khan LA, Zhang H, Abraham N, Sun L, Fleming JT, Buechner M, Hall DH, Gobel V. Intracellular lumen extension requires ERM-1-dependent apical membrane expansion and AQP-8-mediated flux. Nat Cell Biol 2013; 15:143-56. [PMID: 23334498 PMCID: PMC4091717 DOI: 10.1038/ncb2656] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2012] [Accepted: 11/16/2012] [Indexed: 01/29/2023]
Abstract
Many unicellular tubes such as capillaries form lumens intracellularly, a process that is not well understood. Here we show that the cortical membrane organizer ERM-1 is required to expand the intracellular apical/lumenal membrane and its actin undercoat during single-cell C.elegans excretory canal morphogenesis. We characterize AQP-8, identified in an ERM-1 overexpression (ERM-1[++]) suppressor screen, as a canalicular aquaporin that interacts with ERM-1 in lumen extension in a mercury-sensitive manner, implicating water-channel activity. AQP-8 is transiently recruited to the lumen by ERM-1, co-localizing in peri-lumenal cuffs interspaced along expanding canals. An ERM-1[++]-mediated increase in the number of lumen-associated canaliculi is reversed by AQP-8 depletion. We propose that the ERM-1-AQP-8 interaction propels lumen extension by translumenal flux, suggesting a direct morphogenetic effect of water-channel-regulated fluid pressure.
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Affiliation(s)
- Liakot A Khan
- Department of Pediatrics, Massachusetts General Hospital, Boston, 02114, USA
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38
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Coordinated lumen contraction and expansion during vulval tube morphogenesis in Caenorhabditis elegans. Dev Cell 2013; 23:494-506. [PMID: 22975323 DOI: 10.1016/j.devcel.2012.06.019] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2011] [Revised: 04/06/2012] [Accepted: 06/29/2012] [Indexed: 11/20/2022]
Abstract
Morphogenesis is a developmental phase during which cell fates are executed. Mechanical forces shaping individual cells play a key role during tissue morphogenesis. By investigating morphogenesis of the Caenorhabditis elegans hermaphrodite vulva, we show that the force-generating actomyosin network is differentially regulated by NOTCH and EGFR/RAS/MAPK signaling to shape the vulval tube. NOTCH signaling activates expression of the RHO kinase LET-502 in the secondary cell lineage through the ETS-family transcription factor LIN-1. LET-502 induces actomyosin-mediated contraction of the apical lumen in the secondary toroids, thereby generating a dorsal pushing force. In contrast, MAPK signaling in the primary lineage downregulates LET-502 RHO kinase expression to prevent toroid contraction and allow the gonadal anchor cell to expand the dorsal lumen of the primary toroids. The antagonistic action of the MAPK and NOTCH pathways thus controls vulval tube morphogenesis linking cell fate specification to morphogenesis.
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39
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40
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Denning DP, Hatch V, Horvitz HR. Programmed elimination of cells by caspase-independent cell extrusion in C. elegans. Nature 2012; 488:226-30. [PMID: 22801495 PMCID: PMC3416925 DOI: 10.1038/nature11240] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2011] [Accepted: 05/17/2012] [Indexed: 12/27/2022]
Abstract
The elimination of unnecessary or defective cells from metazoans occurs during normal development and tissue homeostasis, as well as in response to infection or cellular damage. Although many cells are removed through caspase-mediated apoptosis followed by phagocytosis by engulfing cells, other mechanisms of cell elimination occur, including the extrusion of cells from epithelia through a poorly understood, possibly caspase-independent, process. Here we identify a mechanism of cell extrusion that is caspase independent and that can eliminate a subset of the Caenorhabditis elegans cells programmed to die during embryonic development. In wild-type animals, these cells die soon after their generation through caspase-mediated apoptosis. However, in mutants lacking all four C. elegans caspase genes, these cells are eliminated by being extruded from the developing embryo into the extra-embryonic space of the egg. The shed cells show apoptosis-like cytological and morphological characteristics, indicating that apoptosis can occur in the absence of caspases in C. elegans. We describe a kinase pathway required for cell extrusion involving PAR-4, STRD-1 and MOP-25.1/-25.2, the C. elegans homologues of the mammalian tumour-suppressor kinase LKB1 and its binding partners STRADα and MO25α. The AMPK-related kinase PIG-1, a possible target of the PAR-4–STRD-1–MOP-25 kinase complex, is also required for cell shedding. PIG-1 promotes shed-cell detachment by preventing the cell-surface expression of cell-adhesion molecules. Our findings reveal a mechanism for apoptotic cell elimination that is fundamentally distinct from that of canonical programmed cell death.
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Affiliation(s)
- Daniel P Denning
- Howard Hughes Medical Institute and Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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41
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Abdus-Saboor I, Stone CE, Murray JI, Sundaram MV. The Nkx5/HMX homeodomain protein MLS-2 is required for proper tube cell shape in the C. elegans excretory system. Dev Biol 2012; 366:298-307. [PMID: 22537498 DOI: 10.1016/j.ydbio.2012.03.015] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2012] [Revised: 03/26/2012] [Accepted: 03/28/2012] [Indexed: 01/20/2023]
Abstract
Cells perform wide varieties of functions that are facilitated, in part, by adopting unique shapes. Many of the genes and pathways that promote cell fate specification have been elucidated. However, relatively few transcription factors have been identified that promote shape acquisition after fate specification. Here we show that the Nkx5/HMX homeodomain protein MLS-2 is required for cellular elongation and shape maintenance of two tubular epithelial cells in the C. elegans excretory system, the duct and pore cells. The Nkx5/HMX family is highly conserved from sea urchins to humans, with known roles in neuronal and glial development. MLS-2 is expressed in the duct and pore, and defects in mls-2 mutants first arise when the duct and pore normally adopt unique shapes. MLS-2 cooperates with the EGF-Ras-ERK pathway to turn on the LIN-48/Ovo transcription factor in the duct cell during morphogenesis. These results reveal a novel interaction between the Nkx5/HMX family and the EGF-Ras pathway and implicate a transcription factor, MLS-2, as a regulator of cell shape.
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Affiliation(s)
- Ishmail Abdus-Saboor
- Department of Genetics, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA
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42
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Mancuso VP, Parry JM, Storer L, Poggioli C, Nguyen KCQ, Hall DH, Sundaram MV. Extracellular leucine-rich repeat proteins are required to organize the apical extracellular matrix and maintain epithelial junction integrity in C. elegans. Development 2012; 139:979-90. [PMID: 22278925 PMCID: PMC3274359 DOI: 10.1242/dev.075135] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/20/2011] [Indexed: 12/13/2022]
Abstract
Epithelial cells are linked by apicolateral junctions that are essential for tissue integrity. Epithelial cells also secrete a specialized apical extracellular matrix (ECM) that serves as a protective barrier. Some components of the apical ECM, such as mucins, can influence epithelial junction remodeling and disassembly during epithelial-to-mesenchymal transition (EMT). However, the molecular composition and biological roles of the apical ECM are not well understood. We identified a set of extracellular leucine-rich repeat only (eLRRon) proteins in C. elegans (LET-4 and EGG-6) that are expressed on the apical surfaces of epidermal cells and some tubular epithelia, including the excretory duct and pore. A previously characterized paralog, SYM-1, is also expressed in epidermal cells and secreted into the apical ECM. Related mammalian eLRRon proteins, such as decorin or LRRTM1-3, influence stromal ECM or synaptic junction organization, respectively. Mutants lacking one or more of the C. elegans epithelial eLRRon proteins show multiple defects in apical ECM organization, consistent with these proteins contributing to the embryonic sheath and cuticular ECM. Furthermore, epithelial junctions initially form in the correct locations, but then rupture at the time of cuticle secretion and remodeling of cell-matrix interactions. This work identifies epithelial eLRRon proteins as important components and organizers of the pre-cuticular and cuticular apical ECM, and adds to the small but growing body of evidence linking the apical ECM to epithelial junction stability. We propose that eLRRon-dependent apical ECM organization contributes to cell-cell adhesion and may modulate epithelial junction dynamics in both normal and disease situations.
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Affiliation(s)
- Vincent P. Mancuso
- Department of Genetics, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA 19104, USA
| | - Jean M. Parry
- Department of Genetics, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA 19104, USA
| | - Luke Storer
- Department of Genetics, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA 19104, USA
| | - Corey Poggioli
- Department of Genetics, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA 19104, USA
| | - Ken C. Q. Nguyen
- Department of Neuroscience, Center for C. elegans Anatomy, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - David H. Hall
- Department of Neuroscience, Center for C. elegans Anatomy, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Meera V. Sundaram
- Department of Genetics, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA 19104, USA
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In brief. Nat Rev Mol Cell Biol 2011. [DOI: 10.1038/nrm3181] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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