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Quintin S, Charvin G. Left-right asymmetry in oxidative stress sensing neurons in C. elegans. MicroPubl Biol 2022; 2022:10.17912/micropub.biology.000652. [PMID: 36338152 PMCID: PMC9631000 DOI: 10.17912/micropub.biology.000652] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/13/2022] [Revised: 09/21/2022] [Accepted: 10/18/2022] [Indexed: 11/15/2022]
Abstract
Perception of oxidative stress in nematodes involves specific neurons expressing antioxidant enzymes. Here, we carefully characterized GFP knock-in lines for C. elegans peroxiredoxin PRDX-2 and thioredoxin TRX-1, and uncovered that left and right I2, PHA and ASJ neurons reproducibly express an asymmetric level of each enzyme. We observed that high-expressing neurons are in most cases associated with a particular side, indicating a directional rather than stochastic type of asymmetry. We propose that the biological relevance of this left-right asymmetry is to fine-tune H 2 O 2 or light sensing, which remains to be investigated.
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Affiliation(s)
- Sophie Quintin
- IGBMC, Development and Stem Cells Department
,
CNRS UMR7104, INSERM U964, Université de Strasbourg, 67404 France
,
Correspondence to: Sophie Quintin (
)
| | - Gilles Charvin
- IGBMC, Development and Stem Cells Department
,
CNRS UMR7104, INSERM U964, Université de Strasbourg, 67404 France
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2
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Suman SK, Daday C, Ferraro T, Vuong-Brender T, Tak S, Quintin S, Robin F, Gräter F, Labouesse M. The plakin domain of C. elegans VAB-10/plectin acts as a hub in a mechanotransduction pathway to promote morphogenesis. Development 2019; 146:dev183780. [PMID: 31784459 PMCID: PMC7375825 DOI: 10.1242/dev.183780] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2019] [Accepted: 11/18/2019] [Indexed: 12/29/2022]
Abstract
Mechanical forces can elicit a mechanotransduction response through junction-associated proteins. In contrast to the wealth of knowledge available for focal adhesions and adherens junctions, much less is known about mechanotransduction at hemidesmosomes. Here, we focus on the C. elegans plectin homolog VAB-10A, the only evolutionary conserved hemidesmosome component. In C. elegans, muscle contractions induce a mechanotransduction pathway in the epidermis through hemidesmosomes. We used CRISPR to precisely remove spectrin repeats (SRs) or a partially hidden Src homology 3 (SH3) domain within the VAB-10 plakin domain. Deleting the SH3 or SR8 domains in combination with mutations affecting mechanotransduction, or just the part of SR5 shielding the SH3 domain, induced embryonic elongation arrest because hemidesmosomes collapse. Notably, recruitment of GIT-1, the first mechanotransduction player, requires the SR5 domain and the hemidesmosome transmembrane receptor LET-805. Furthermore, molecular dynamics simulations confirmed that forces acting on VAB-10 could make the central SH3 domain, otherwise in contact with SR4, available for interaction. Collectively, our data strongly indicate that the plakin domain plays a central role in mechanotransduction and raise the possibility that VAB-10/plectin might act as a mechanosensor.
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Affiliation(s)
- Shashi Kumar Suman
- Sorbonne Université, CNRS, Institut de Biologie Paris Seine, Laboratoire de Biologie du Développement/UMR7622,7 Quai St-Bernard, 75005 Paris, France
- Development and Stem Cells Program, IGBMC, CNRS (UMR7104), INSERM (U964), Université de Strasbourg, 1 rue Laurent Fries, BP10142, 67400 Illkirch, France
| | - Csaba Daday
- Interdisciplinary Center for Scientific Computing (IWR), Heidelberg University, Mathematikon, INF 205, 69120 Heidelberg, Germany
- Heidelberg Institute for Theoretical Studies, Schloß-Wolfsbrunnenweg 35, 69118 Heidelberg, Germany
| | - Teresa Ferraro
- Sorbonne Université, CNRS, Institut de Biologie Paris Seine, Laboratoire de Biologie du Développement/UMR7622,7 Quai St-Bernard, 75005 Paris, France
| | - Thanh Vuong-Brender
- Sorbonne Université, CNRS, Institut de Biologie Paris Seine, Laboratoire de Biologie du Développement/UMR7622,7 Quai St-Bernard, 75005 Paris, France
- Development and Stem Cells Program, IGBMC, CNRS (UMR7104), INSERM (U964), Université de Strasbourg, 1 rue Laurent Fries, BP10142, 67400 Illkirch, France
| | - Saurabh Tak
- Sorbonne Université, CNRS, Institut de Biologie Paris Seine, Laboratoire de Biologie du Développement/UMR7622,7 Quai St-Bernard, 75005 Paris, France
- Development and Stem Cells Program, IGBMC, CNRS (UMR7104), INSERM (U964), Université de Strasbourg, 1 rue Laurent Fries, BP10142, 67400 Illkirch, France
| | - Sophie Quintin
- Development and Stem Cells Program, IGBMC, CNRS (UMR7104), INSERM (U964), Université de Strasbourg, 1 rue Laurent Fries, BP10142, 67400 Illkirch, France
| | - François Robin
- Sorbonne Université, CNRS, Institut de Biologie Paris Seine, Laboratoire de Biologie du Développement/UMR7622,7 Quai St-Bernard, 75005 Paris, France
| | - Frauke Gräter
- Interdisciplinary Center for Scientific Computing (IWR), Heidelberg University, Mathematikon, INF 205, 69120 Heidelberg, Germany
- Heidelberg Institute for Theoretical Studies, Schloß-Wolfsbrunnenweg 35, 69118 Heidelberg, Germany
| | - Michel Labouesse
- Sorbonne Université, CNRS, Institut de Biologie Paris Seine, Laboratoire de Biologie du Développement/UMR7622,7 Quai St-Bernard, 75005 Paris, France
- Development and Stem Cells Program, IGBMC, CNRS (UMR7104), INSERM (U964), Université de Strasbourg, 1 rue Laurent Fries, BP10142, 67400 Illkirch, France
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Quintin S, Wang S, Pontabry J, Bender A, Robin F, Hyenne V, Landmann F, Gally C, Oegema K, Labouesse M. Correction: Non-centrosomal epidermal microtubules act in parallel to LET-502/ROCK to promote C. elegans elongation (doi:10.1242/dev.126615). Development 2018; 145:145/10/dev167262. [PMID: 29759977 DOI: 10.1242/dev.167262] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
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Paoletti C, Quintin S, Matifas A, Charvin G. Kinetics of Formation and Asymmetrical Distribution of Hsp104-Bound Protein Aggregates in Yeast. Biophys J 2016; 110:1605-1614. [PMID: 27074685 DOI: 10.1016/j.bpj.2016.02.034] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2015] [Revised: 02/17/2016] [Accepted: 02/23/2016] [Indexed: 02/05/2023] Open
Abstract
Budding yeast cells have a finite replicative life span; that is, a mother cell produces only a limited number of daughter cells before it slows division and dies. Despite the gradual aging of the mother cell, all daughters are born rejuvenated and enjoy a full replicative lifespan. It has been proposed that entry of mother cells into senescence is driven by the progressive accumulation and retention of damaged material, including protein aggregates. This additionally allows the daughter cells to be born damage free. However, the mechanism underlying such asymmetrical segregation of protein aggregates by mother and daughter cells remains controversial, in part because of the difficulties inherent in tracking the dynamics and fate of protein aggregates in vivo. To overcome such limitations, we have developed single-cell real-time imaging methodology to track the formation of heat-induced protein aggregates in otherwise unperturbed dividing cells. By combining the imaging data with a simple computational model of protein aggregation, we show that the establishment of asymmetrical partitioning of protein aggregates upon division is driven by the large bud-specific dilution rate associated with polarized growth and the absence of significant mother/bud exchange of protein aggregates during the budded phase of the cell cycle. To our knowledge, this study sheds new light on the mechanism of establishment of a segregation bias, which can be accounted for by simple physical arguments.
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Affiliation(s)
- Camille Paoletti
- Development and Stem Cells Department, IGBMC, CNRS UMR 7104, INSERM U964, Université de Strasbourg, Illkirch, France
| | - Sophie Quintin
- Development and Stem Cells Department, IGBMC, CNRS UMR 7104, INSERM U964, Université de Strasbourg, Illkirch, France
| | - Audrey Matifas
- Development and Stem Cells Department, IGBMC, CNRS UMR 7104, INSERM U964, Université de Strasbourg, Illkirch, France
| | - Gilles Charvin
- Development and Stem Cells Department, IGBMC, CNRS UMR 7104, INSERM U964, Université de Strasbourg, Illkirch, France.
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Quintin S, Gally C, Labouesse M. Noncentrosomal microtubules in C. elegans epithelia. Genesis 2016; 54:229-42. [PMID: 26789944 DOI: 10.1002/dvg.22921] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2015] [Revised: 01/12/2016] [Accepted: 01/14/2016] [Indexed: 11/12/2022]
Abstract
The microtubule cytoskeleton has a dual contribution to cell organization. First, microtubules help displace chromosomes and provide tracks for organelle transport. Second, microtubule rigidity confers specific mechanical properties to cells, which are crucial in cilia or mechanosensory structures. Here we review the recently uncovered organization and functions of noncentrosomal microtubules in C. elegans epithelia, focusing on how they contribute to nuclear positioning and protein transport. In addition, we describe recent data illustrating how the microtubule and actin cytoskeletons interact to achieve those functions.
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Affiliation(s)
- Sophie Quintin
- Development and Stem Cells Department, IGBMC - CNRS UMR 7104/INSERM U964/Université de Strasbourg, 1 Rue Laurent Fries, Illkirch, 67400, France
| | - Christelle Gally
- Development and Stem Cells Department, IGBMC - CNRS UMR 7104/INSERM U964/Université de Strasbourg, 1 Rue Laurent Fries, Illkirch, 67400, France
| | - Michel Labouesse
- Université Pierre Et Marie Curie, IBPS, CNRS UMR7622, 7 Quai St-Bernard, Paris, 75005, France
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Quintin S, Wang S, Pontabry J, Bender A, Robin F, Hyenne V, Landmann F, Gally C, Oegema K, Labouesse M. Non-centrosomal epidermal microtubules act in parallel to LET-502/ROCK to promote C. elegans elongation. J Cell Sci 2016. [DOI: 10.1242/jcs.185371] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
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7
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Quintin S, Wang S, Pontabry J, Bender A, Robin F, Hyenne V, Landmann F, Gally C, Oegema K, Labouesse M. Non-centrosomal epidermal microtubules act in parallel to LET-502/ROCK to promote C. elegans elongation. Development 2015; 143:160-73. [PMID: 26586219 PMCID: PMC6514414 DOI: 10.1242/dev.126615] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2015] [Accepted: 11/10/2015] [Indexed: 12/11/2022]
Abstract
C. elegans embryonic elongation is a morphogenetic event driven by actomyosin contractility and muscle-induced tension transmitted through hemidesmosomes. A role for the microtubule cytoskeleton has also been proposed, but its contribution remains poorly characterized. Here, we investigate the organization of the non-centrosomal microtubule arrays present in the epidermis and assess their function in elongation. We show that the microtubule regulators γ-tubulin and NOCA-1 are recruited to hemidesmosomes and adherens junctions early in elongation. Several parallel approaches suggest that microtubule nucleation occurs from these sites. Disrupting the epidermal microtubule array by overexpressing the microtubule-severing protein Spastin or by inhibiting the C. elegans ninein homolog NOCA-1 in the epidermis mildly affected elongation. However, microtubules were essential for elongation when hemidesmosomes or the activity of the Rho kinase LET-502/ROCK were partially compromised. Imaging of junctional components and genetic analyses suggest that epidermal microtubules function together with Rho kinase to promote the transport of E-cadherin to adherens junctions and myotactin to hemidesmosomes. Our results indicate that the role of LET-502 in junctional remodeling is likely to be independent of its established function as a myosin II activator, but requires a microtubule-dependent pathway involving the syntaxin SYX-5. Hence, we propose that non-centrosomal microtubules organized by epidermal junctions contribute to elongation by transporting junction remodeling factors, rather than having a mechanical role. Summary: During C. elegans embryonic elongation, microtubules nucleate at adjerens junctions and hemidesmosomes, and are important for the transport of junctional proteins.
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Affiliation(s)
- Sophie Quintin
- IGBMC - CNRS UMR 7104 - INSERM U964 - Université de Strasbourg, 1 rue Laurent Fries, BP 10142, Illkirch 67404, Cedex, France
| | - Shahoe Wang
- Ludwig Institute for Cancer Research, Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92037, USA
| | - Julien Pontabry
- IGBMC - CNRS UMR 7104 - INSERM U964 - Université de Strasbourg, 1 rue Laurent Fries, BP 10142, Illkirch 67404, Cedex, France
| | - Ambre Bender
- IGBMC - CNRS UMR 7104 - INSERM U964 - Université de Strasbourg, 1 rue Laurent Fries, BP 10142, Illkirch 67404, Cedex, France
| | - François Robin
- Institut de Biologie Paris Seine, IBPS FR3631, Université Pierre et Marie Curie, 7-9 Quai Saint Bernard, Paris 75005, France
| | - Vincent Hyenne
- IGBMC - CNRS UMR 7104 - INSERM U964 - Université de Strasbourg, 1 rue Laurent Fries, BP 10142, Illkirch 67404, Cedex, France
| | - Frédéric Landmann
- IGBMC - CNRS UMR 7104 - INSERM U964 - Université de Strasbourg, 1 rue Laurent Fries, BP 10142, Illkirch 67404, Cedex, France
| | - Christelle Gally
- IGBMC - CNRS UMR 7104 - INSERM U964 - Université de Strasbourg, 1 rue Laurent Fries, BP 10142, Illkirch 67404, Cedex, France
| | - Karen Oegema
- Ludwig Institute for Cancer Research, Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92037, USA
| | - Michel Labouesse
- IGBMC - CNRS UMR 7104 - INSERM U964 - Université de Strasbourg, 1 rue Laurent Fries, BP 10142, Illkirch 67404, Cedex, France Institut de Biologie Paris Seine, IBPS FR3631, Université Pierre et Marie Curie, 7-9 Quai Saint Bernard, Paris 75005, France
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8
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Wang S, Wu D, Quintin S, Green RA, Cheerambathur DK, Ochoa SD, Desai A, Oegema K. NOCA-1 functions with γ-tubulin and in parallel to Patronin to assemble non-centrosomal microtubule arrays in C. elegans. eLife 2015; 4:e08649. [PMID: 26371552 PMCID: PMC4608005 DOI: 10.7554/elife.08649] [Citation(s) in RCA: 99] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2015] [Accepted: 09/12/2015] [Indexed: 12/21/2022] Open
Abstract
Non-centrosomal microtubule arrays assemble in differentiated tissues to perform mechanical and transport-based functions. In this study, we identify Caenorhabditis elegans NOCA-1 as a protein with homology to vertebrate ninein. NOCA-1 contributes to the assembly of non-centrosomal microtubule arrays in multiple tissues. In the larval epidermis, NOCA-1 functions redundantly with the minus end protection factor Patronin/PTRN-1 to assemble a circumferential microtubule array essential for worm growth and morphogenesis. Controlled degradation of a γ-tubulin complex subunit in this tissue revealed that γ-tubulin acts with NOCA-1 in parallel to Patronin/PTRN-1. In the germline, NOCA-1 and γ-tubulin co-localize at the cell surface, and inhibiting either leads to a microtubule assembly defect. γ-tubulin targets independently of NOCA-1, but NOCA-1 targeting requires γ-tubulin when a non-essential putatively palmitoylated cysteine is mutated. These results show that NOCA-1 acts with γ-tubulin to assemble non-centrosomal arrays in multiple tissues and highlight functional overlap between the ninein and Patronin protein families. DOI:http://dx.doi.org/10.7554/eLife.08649.001 Microtubules are hollow, rigid filaments that are found in the cells of animals and other eukaryotes. These filaments are built from smaller building blocks called tubulin heterodimers; and in dividing animal cells, they mainly emerge from structures called centrosomes. When a cell is dividing, arrays of microtubules that originate from centrosomes help assemble the spindle-like structure that segregates the chromosomes. Many non-dividing or specialized cells—including neurons, skin cells and muscle fibers—assemble other arrays of microtubules that do not emerge from centrosomes, but nevertheless perform a variety of structural, mechanical and transport-based roles. Compared to the centrosomal arrays, much less is known about how these non-centrosomal microtubules are assembled. A vertebrate protein called ‘ninein’ had previously been shown to be involved in anchoring microtubules at centrosomes. Ninein can change its localization from centrosomes to the cell surface in mammalian skin cells, suggesting that it might also have a role in assembling the peripheral microtubule arrays that are found in these cells. Now, Wang et al. have identified a protein from worms called NOCA-1, which contains a region similar to the part of ninein that was previously shown to be needed to anchor microtubules at centrosomes. The experiments show that NOCA-1 guides the assembly of non-centrosomal microtubule arrays in multiple tissues in C. elegans worms. This includes in the outer layer of the worm's larvae, which is similar to mammalian skin. The results also highlight that NOCA-1 performs many of the same roles as a member of the Patronin family of proteins called PTRN-1, which interacts with the ‘minus’ end of a microtubule to prevent the microtubule from breaking apart. Wang et al. also found that NOCA-1 works with another protein called γ-tubulin, which helps new microtubules to form and also interacts with microtubule minus ends. In contrast, PTRN-1 works independently of γ-tubulin. This suggests that NOCA-1 works together with γ-tubulin to protect new microtubule ends or promote their assembly, a role similar to what has been proposed for Patronin family proteins. Overall, Wang et al.'s results highlight the importance of ninein-related proteins in the assembly of non-centrosomal microtubule arrays and suggest overlapping roles for the ninein and Patronin families of proteins. DOI:http://dx.doi.org/10.7554/eLife.08649.002
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Affiliation(s)
- Shaohe Wang
- Ludwig Institute for Cancer Research, Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, United States.,Biomedical Sciences Graduate Program, University of California, San Diego, La Jolla, United States
| | - Di Wu
- Ludwig Institute for Cancer Research, Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, United States
| | - Sophie Quintin
- Institut Génétique Biologie Moléculaire Ceasllulaire, Faculté de médecine, Université de Strasbourg, Strasbourg, France.,Institut Clinique de la Souris, Illkirch-Graffenstaden, France
| | - Rebecca A Green
- Ludwig Institute for Cancer Research, Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, United States
| | - Dhanya K Cheerambathur
- Ludwig Institute for Cancer Research, Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, United States
| | - Stacy D Ochoa
- Ludwig Institute for Cancer Research, Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, United States
| | - Arshad Desai
- Ludwig Institute for Cancer Research, Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, United States
| | - Karen Oegema
- Ludwig Institute for Cancer Research, Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, United States
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Kim HS, Murakami R, Quintin S, Mori M, Ohkura K, Tamai KK, Labouesse M, Sakamoto H, Nishiwaki K. VAB-10 spectraplakin acts in cell and nuclear migration in Caenorhabditis elegans. J Cell Sci 2011. [DOI: 10.1242/jcs.098855] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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Kim HS, Murakami R, Quintin S, Mori M, Ohkura K, Tamai KK, Labouesse M, Sakamoto H, Nishiwaki K. VAB-10 spectraplakin acts in cell and nuclear migration in Caenorhabditis elegans. Development 2011; 138:4013-23. [PMID: 21831923 PMCID: PMC3160096 DOI: 10.1242/dev.059568] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/05/2011] [Indexed: 11/20/2022]
Abstract
Cytoskeletal regulation is important in cell migration. The Caenorhabditis elegans gonadal distal tip cells (DTCs) offer a simple model with which to investigate the mechanism of cell migration in organogenesis. Here, we report that one of the spectraplakin isoforms, VAB-10B1, plays an essential role in cell and nuclear migration of DTCs by regulating the actin and microtubule (MT) cytoskeleton. In the vab-10(tk27) mutant, which lacks VAB-10B1, alignment of filamentous (F)-actin and MTs was weakly and severely disorganized, respectively, which resulted in a failure to translocate the DTC nucleus and a premature termination of DTC migration. An MT growing-tip marker, EBP-2-GFP, revealed that polarized outgrowth of MTs towards the nuclei of migrating DTCs was strikingly impaired in tk27 animals. A vab-10 mini-gene encoding only the actin- and MT-binding domains significantly rescued the gonadal defects, suggesting that VAB-10B1 has a role in linking actin and MT filaments. These results suggest that VAB-10B1/spectraplakin regulates the polarized alignment of MTs, possibly by linking F-actin and MTs, which enables normal nuclear translocation and cell migration of DTCs.
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Affiliation(s)
- Hon-Song Kim
- Department of Bioscience, Kwansei Gakuin University, 2-1 Gakuen, Sanda 669-1337, Japan
- RIKEN Center for Developmental Biology, Chuo-ku, Kobe 650-0047, Japan
| | - Ryoko Murakami
- RIKEN Center for Developmental Biology, Chuo-ku, Kobe 650-0047, Japan
- Department of Biology, Graduate School of Science, Kobe University, 1-1 Rokkodaicho, Nada-ku, Kobe 657-8501, Japan
| | - Sophie Quintin
- Development and Stem Cells program, IGBMC, CNRS UMR7104/INSERM U. 964//Université de Strasbourg, Illkirch, Cedex F-67404, France
| | - Masataka Mori
- Department of Bioscience, Kwansei Gakuin University, 2-1 Gakuen, Sanda 669-1337, Japan
| | - Kiyotaka Ohkura
- RIKEN Center for Developmental Biology, Chuo-ku, Kobe 650-0047, Japan
| | | | - Michel Labouesse
- Development and Stem Cells program, IGBMC, CNRS UMR7104/INSERM U. 964//Université de Strasbourg, Illkirch, Cedex F-67404, France
| | - Hiroshi Sakamoto
- Department of Biology, Graduate School of Science, Kobe University, 1-1 Rokkodaicho, Nada-ku, Kobe 657-8501, Japan
| | - Kiyoji Nishiwaki
- Department of Bioscience, Kwansei Gakuin University, 2-1 Gakuen, Sanda 669-1337, Japan
- RIKEN Center for Developmental Biology, Chuo-ku, Kobe 650-0047, Japan
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Gally C, Wissler F, Zahreddine H, Quintin S, Landmann F, Labouesse M. Myosin II regulation during C. elegans embryonic elongation: LET-502/ROCK, MRCK-1 and PAK-1, three kinases with different roles. Development 2009; 136:3109-19. [PMID: 19675126 DOI: 10.1242/dev.039412] [Citation(s) in RCA: 105] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Myosin II plays a central role in epithelial morphogenesis; however, its role has mainly been examined in processes involving a single cell type. Here we analyze the structure, spatial requirement and regulation of myosin II during C. elegans embryonic elongation, a process that involves distinct epidermal cells and muscles. We developed novel GFP probes to visualize the dynamics of actomyosin remodeling, and found that the assembly of myosin II filaments, but not actin microfilaments, depends on the myosin regulatory light chain (MLC-4) and essential light chain (MLC-5, which we identified herein). To determine how myosin II regulates embryonic elongation, we rescued mlc-4 mutants with various constructs and found that MLC-4 is essential in a subset of epidermal cells. We show that phosphorylation of two evolutionary conserved MLC-4 serine and threonine residues is important for myosin II activity and organization. Finally, in an RNAi screen for potential myosin regulatory light chain kinases, we found that the ROCK, PAK and MRCK homologs act redundantly. The combined loss of ROCK and PAK, or ROCK and MRCK, completely prevented embryonic elongation, but a constitutively active form of MLC-4 could only rescue a lack of MRCK. This result, together with systematic genetic epistasis tests with a myosin phosphatase mutation, suggests that ROCK and MRCK regulate MLC-4 and the myosin phosphatase. Moreover, we suggest that ROCK and PAK regulate at least one other target essential for elongation, in addition to MLC-4.
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Affiliation(s)
- Christelle Gally
- IGBMC, CNRS/ INSERM/ UdS, 1 rue Laurent Fries, BP.10142, 67400 Illkirch, France
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Gally C, Wissler F, Zahreddine H, Quintin S, Landmann F, Labouesse M. 03-P014 Myosin II regulation during embryonic elongation in C. elegans: LET-502/ROCK, PAK-1 and MRCK-1, three kinases with different roles. Mech Dev 2009. [DOI: 10.1016/j.mod.2009.06.067] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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13
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Quintin S, Gally C, Labouesse M. Epithelial morphogenesis in embryos: asymmetries, motors and brakes. Trends Genet 2008; 24:221-30. [PMID: 18375008 DOI: 10.1016/j.tig.2008.02.005] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2007] [Revised: 01/30/2008] [Accepted: 02/01/2008] [Indexed: 10/22/2022]
Abstract
Epithelial cells play a central role in many embryonic morphogenetic processes, during which they undergo highly coordinated cell shape changes. Here, we review some common principles that have recently emerged through genetic and cellular analyses performed mainly with invertebrate genetic models, focusing on morphogenetic processes involving epithelial sheets. All available data argue that myosin II is the main motor that induces cell shape changes during morphogenesis. We discuss the control of myosin II activity during epithelial morphogenesis, as well as the recently described involvement of microtubules in this process. Finally, we examine how forces unleashed by myosin II can be measured, how embryos use specific brakes to control molecular motors and the potential input of mechano-sensation in morphogenesis.
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Affiliation(s)
- Sophie Quintin
- IGBMC, CNRS/INSERM/ULP, BP. 10142, 67404 Illkirch Cedex, France
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Diogon M, Wissler F, Quintin S, Nagamatsu Y, Sookhareea S, Landmann F, Hutter H, Vitale N, Labouesse M. The RhoGAP RGA-2 and LET-502/ROCK achieve a balance of actomyosin-dependent forces inC. elegansepidermis to control morphogenesis. Development 2007; 134:2469-79. [PMID: 17537791 DOI: 10.1242/dev.005074] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Embryonic morphogenesis involves the coordinate behaviour of multiple cells and requires the accurate balance of forces acting within different cells through the application of appropriate brakes and throttles. In C. elegans, embryonic elongation is driven by Rho-binding kinase (ROCK) and actomyosin contraction in the epidermis. We identify an evolutionary conserved, actin microfilament-associated RhoGAP (RGA-2) that behaves as a negative regulator of LET-502/ROCK. The small GTPase RHO-1 is the preferred target of RGA-2 in vitro, and acts between RGA-2 and LET-502 in vivo. Two observations show that RGA-2 acts in dorsal and ventral epidermal cells to moderate actomyosin tension during the first half of elongation. First,time-lapse microscopy shows that loss of RGA-2 induces localised circumferentially oriented pulling on junctional complexes in dorsal and ventral epidermal cells. Second, specific expression of RGA-2 in dorsal/ventral, but not lateral, cells rescues the embryonic lethality of rga-2 mutants. We propose that actomyosin-generated tension must be moderated in two out of the three sets of epidermal cells surrounding the C. elegans embryo to achieve morphogenesis.
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Affiliation(s)
- Marie Diogon
- IGBMC, CNRS/INSERM/ULP, 1 rue Laurent Fries, BP.10142, 67400 Illkirch, France
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15
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Schlaitz AL, Srayko M, Dammermann A, Quintin S, Wielsch N, MacLeod I, de Robillard Q, Zinke A, Yates JR, Müller-Reichert T, Shevchenko A, Oegema K, Hyman AA. The C. elegans RSA complex localizes protein phosphatase 2A to centrosomes and regulates mitotic spindle assembly. Cell 2007; 128:115-27. [PMID: 17218259 PMCID: PMC2987564 DOI: 10.1016/j.cell.2006.10.050] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2006] [Revised: 09/28/2006] [Accepted: 10/20/2006] [Indexed: 01/08/2023]
Abstract
Microtubule behavior changes during the cell cycle and during spindle assembly. However, it remains unclear how these changes are regulated and coordinated. We describe a complex that targets the Protein Phosphatase 2A holoenzyme (PP2A) to centrosomes in C. elegans embryos. This complex includes Regulator of Spindle Assembly 1 (RSA-1), a targeting subunit for PP2A, and RSA-2, a protein that binds and recruits RSA-1 to centrosomes. In contrast to the multiple functions of the PP2A catalytic subunit, RSA-1 and RSA-2 are specifically required for microtubule outgrowth from centrosomes and for spindle assembly. The centrosomally localized RSA-PP2A complex mediates these functions in part by regulating two critical mitotic effectors: the microtubule destabilizer KLP-7 and the C. elegans regulator of spindle assembly TPXL-1. By regulating a subset of PP2A functions at the centrosome, the RSA complex could therefore provide a means of coordinating microtubule outgrowth from centrosomes and kinetochore microtubule stability during mitotic spindle assembly.
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Affiliation(s)
- Anne-Lore Schlaitz
- Max-Planck-Institute of Molecular Cell Biology and Genetics (MPI-CBG), Pfotenhauerstrasse 108, 01307 Dresden, Germany
| | - Martin Srayko
- Max-Planck-Institute of Molecular Cell Biology and Genetics (MPI-CBG), Pfotenhauerstrasse 108, 01307 Dresden, Germany
| | - Alexander Dammermann
- Department of Cellular and Molecular Medicine, Ludwig Institute for Cancer Research, University of California, San Diego School of Medicine, La Jolla, California 92093
| | - Sophie Quintin
- Max-Planck-Institute of Molecular Cell Biology and Genetics (MPI-CBG), Pfotenhauerstrasse 108, 01307 Dresden, Germany
| | - Natalie Wielsch
- Max-Planck-Institute of Molecular Cell Biology and Genetics (MPI-CBG), Pfotenhauerstrasse 108, 01307 Dresden, Germany
| | - Ian MacLeod
- Department of Cell Biology, The Scripps Research Institute, La Jolla, California 92037
| | - Quentin de Robillard
- Max-Planck-Institute of Molecular Cell Biology and Genetics (MPI-CBG), Pfotenhauerstrasse 108, 01307 Dresden, Germany
| | - Andrea Zinke
- Max-Planck-Institute of Molecular Cell Biology and Genetics (MPI-CBG), Pfotenhauerstrasse 108, 01307 Dresden, Germany
| | - John R. Yates
- Department of Cell Biology, The Scripps Research Institute, La Jolla, California 92037
| | - Thomas Müller-Reichert
- Max-Planck-Institute of Molecular Cell Biology and Genetics (MPI-CBG), Pfotenhauerstrasse 108, 01307 Dresden, Germany
| | - Andrei Shevchenko
- Max-Planck-Institute of Molecular Cell Biology and Genetics (MPI-CBG), Pfotenhauerstrasse 108, 01307 Dresden, Germany
| | - Karen Oegema
- Department of Cellular and Molecular Medicine, Ludwig Institute for Cancer Research, University of California, San Diego School of Medicine, La Jolla, California 92093
| | - Anthony A. Hyman
- Max-Planck-Institute of Molecular Cell Biology and Genetics (MPI-CBG), Pfotenhauerstrasse 108, 01307 Dresden, Germany
- To whom correspondence should be addressed, , Phone:+49 351 210 1700, Fax: +49 351 210 1289
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Landmann F, Quintin S, Labouesse M. Multiple regulatory elements with spatially and temporally distinct activities control the expression of the epithelial differentiation gene lin-26 in C. elegans. Dev Biol 2004; 265:478-90. [PMID: 14732406 DOI: 10.1016/j.ydbio.2003.09.009] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Epithelial differentiation is a very early event during development of most species. The nematode Caenorhabditis elegans, with its well-defined and invariant lineage, offers the possibility to link cell lineage, cell fate specification and gene regulation during epithelial differentiation. Here, we focus on the regulation of the gene lin-26, which is required for proper differentiation of epithelial cells in the ectoderm and mesoderm (somatic gonad). lin-26 expression starts in early embryos and remains on throughout development, in many cell types originating from different sublineages. Using GFP reporters and mutant rescue assays, we performed a molecular dissection of the lin-26 promoter and could identify almost all elements required to establish its complex spatial and temporal expression. Most of these elements act redundantly, or synergistically once combined, to drive expression in cells related by function. We also show that lin-26 promoter elements mediate activation in the epidermis (hypodermis) by the GATA factor ELT-1, or repression in the foregut (pharynx) by the FoxA protein PHA-4. Taken together, our data indicate that lin-26 regulation is achieved to a large extent through tissue-specific cis-regulatory elements.
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Affiliation(s)
- Frédéric Landmann
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, CNRS/INSERM/ULP, BP101423, F-67404 Illkirch Cedex, C.U. de Strasbourg, France
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17
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Affiliation(s)
- Sophie Quintin
- Max‐Planck‐Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108 D‐01307 Dresden Germany
- Genes and Development Research Group, Department of Biochemistry & Molecular Biology, University of Calgary 3330 Hospital Drive NW, Calgary Alberta Canada T2N 4N1
| | - Paul E Mains
- Max‐Planck‐Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108 D‐01307 Dresden Germany
- Genes and Development Research Group, Department of Biochemistry & Molecular Biology, University of Calgary 3330 Hospital Drive NW, Calgary Alberta Canada T2N 4N1
| | - Andrea Zinke
- Max‐Planck‐Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108 D‐01307 Dresden Germany
| | - Anthony A Hyman
- Max‐Planck‐Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108 D‐01307 Dresden Germany
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Quintin S, Mains PE, Zinke A, Hyman AA. The mbk-2 kinase is required for inactivation of MEI-1/katanin in the one-cell Caenorhabditis elegans embryo. EMBO Rep 2003; 4:1175-81. [PMID: 14634695 PMCID: PMC1326421 DOI: 10.1038/sj.embor.7400029] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2003] [Revised: 10/08/2003] [Accepted: 10/08/2003] [Indexed: 11/08/2022] Open
Abstract
The Caenorhabditis elegans early embryo is widely used to study the regulation of microtubule-related processes. In a screen for mutants affecting the first cell division, we isolated a temperature-sensitive mutation affecting pronuclear migration and spindle positioning, phenotypes typically linked to microtubule or centrosome defects. In the mutant, microtubules are shorter and chromosome segregation is impaired, while centrosome organization appears normal. The mutation corresponds to a strong loss of function in mbk-2, a conserved serine/threonine kinase. The microtubule-related defects are due to the postmeiotic persistence of MEI-1, a homologue of the microtubule-severing protein katanin. In addition, P-granule distribution is abnormal in mbk-2 mutants, consistent with genetic evidence that mbk-2 has other functions and with the requirement of mbk-2 activity at the one-cell stage. We propose that mbk-2 potentiates the degradation of MEI-1 and other proteins, possibly via direct phosphorylation.
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Affiliation(s)
- Sophie Quintin
- Max-Planck-Institute of Molecular Cell Biology and
Genetics, Pfotenhauerstrasse 108, D-01307 Dresden, Germany
- Genes and Development Research Group, Department of
Biochemistry & Molecular Biology, University of Calgary, 3330 Hospital
Drive NW, Calgary, Alberta, Canada T2N 4N1
| | - Paul E Mains
- Max-Planck-Institute of Molecular Cell Biology and
Genetics, Pfotenhauerstrasse 108, D-01307 Dresden, Germany
- Genes and Development Research Group, Department of
Biochemistry & Molecular Biology, University of Calgary, 3330 Hospital
Drive NW, Calgary, Alberta, Canada T2N 4N1
| | - Andrea Zinke
- Max-Planck-Institute of Molecular Cell Biology and
Genetics, Pfotenhauerstrasse 108, D-01307 Dresden, Germany
| | - Anthony A Hyman
- Max-Planck-Institute of Molecular Cell Biology and
Genetics, Pfotenhauerstrasse 108, D-01307 Dresden, Germany
- Tel: +49 351 210 1700; Fax: +49 351 210 1289;
E-mail:
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Srayko M, Quintin S, Schwager A, Hyman AA. Caenorhabditis elegans TAC-1 and ZYG-9 form a complex that is essential for long astral and spindle microtubules. Curr Biol 2003; 13:1506-11. [PMID: 12956952 DOI: 10.1016/s0960-9822(03)00597-9] [Citation(s) in RCA: 94] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
TACC (transforming acidic coiled-coil) proteins were first identified by their ability to transform cell lines [1], and links between human cancer and the overexpression of TACC proteins highlight the importance of understanding the biological function of this family of proteins. Herein, we describe the characterization of a new member of the TACC family of proteins in Caenorhabditis elegans, TAC-1. In other systems, TACC proteins associate with the XMAP215 family of microtubule-stabilizing proteins; however, it is unclear whether TACC proteins have microtubule-based functions distinct from XMAP215. We depleted both the XMAP215 ortholog ZYG-9 and TAC-1 via dsRNA-mediated interference (RNAi). We found that tac-1(RNAi) resulted in microtubule-based defects that were very similar to zyg-9(RNAi). Furthermore, TAC-1 and ZYG-9 are required for long astral microtubules in general and long spindle microtubules during spindle assembly. Loss of either protein did not affect the alpha-tubulin immunofluorescence intensity near centrosomes; this finding suggests that microtubule nucleation was not compromised. Both proteins localize to centrosomes and the kinetochore/microtubule region of chromosomes in metaphase and early anaphase. Furthermore, we found that ZYG-9 and TAC-1 physically interact in vivo, and this interaction is important for the efficient localization of the ZYG-9/TAC-1 complex to centrosomes.
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Affiliation(s)
- Martin Srayko
- Max-Planck-Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, D-01307, Dresden, Germany
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20
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Quintin S, Michaux G, McMahon L, Gansmuller A, Labouesse M. The Caenorhabditis elegans gene lin-26 can trigger epithelial differentiation without conferring tissue specificity. Dev Biol 2001; 235:410-21. [PMID: 11437447 DOI: 10.1006/dbio.2001.0294] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
How epithelial cell fates become specified is poorly understood. We have previously shown that the putative C2H2 zinc-finger transcription factor LIN-26 is required for the differentiation of ectodermal and mesodermal epithelial cells in Caenorhabditis elegans. Here, we report that ectopic LIN-26 expression during early gastrulation transforms most blastomeres into epithelial-like cells. Specifically, LIN-26 induced the expression of three epithelial markers: the adherens junction protein JAM-1; DLG-1, which is essential for the assembly of JAM-1 at junctions; and CHE-14, which is involved in apical trafficking. Furthermore, ultrastructural studies revealed that ectopic LIN-26 expression induced the formation of adherens-like junctions. However, ectopic lin-26 expression did not confer any tissue-specific cell fate, such as the epidermal cell fate, as evidenced from the observation that several epidermal-specific genes were not induced. Conversely, we show that epidermal cells displayed some polarity defects in lin-26 mutants. We conclude that lin-26 can induce epithelial differentiation and that epitheliogenesis is not a default pathway in C. elegans.
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Affiliation(s)
- S Quintin
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, CNRS/INSERM/ULP, F-67404 Illkirch Cedex, C.U. de Strasbourg, France
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21
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Abstract
Recently, a novel family of TATA binding protein (TBP)-like factors (TLFs) have been described in metazoan organisms; however, their function has not yet been elucidated. Using Caenorhabditis elegans (Ce) as a model, we demonstrate that CeTLF is required in vivo for zygotic transcription during embryogenesis. Elimination of CeTLF expression by RNA interference caused embryonic lethality either due to the lack of expression of early patterning genes or to their ectopic expression. Moreover, the absence of CeTLF in vivo prevented the correct soma-specific phosphorylation of RNA polymerase II (Pol II). Thus, CeTLF may positively or negatively regulate Pol II transcription, depending on the developmental stage of the embryo.
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Affiliation(s)
- J C Dantonel
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, CNRS/INSERM/ULP Illkirch, C.U. de Strasbourg, France
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22
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Dufourcq P, Chanal P, Vicaire S, Camut E, Quintin S, den Boer BG, Bosher JM, Labouesse M. lir-2, lir-1 and lin-26 encode a new class of zinc-finger proteins and are organized in two overlapping operons both in Caenorhabditis elegans and in Caenorhabditis briggsae. Genetics 1999; 152:221-35. [PMID: 10224256 PMCID: PMC1460593 DOI: 10.1093/genetics/152.1.221] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
lin-26, which encodes a unique Zn-finger protein, is required for differentiation of nonneuronal ectodermal cells in Caenorhabditis elegans. Here, we show that the two genes located immediately upstream of lin-26 encode LIN-26-like Zn-finger proteins; hence their names are lir-1 and lir-2 (lin-26 related). lir-2, lir-1, and lin-26 generate several isoforms by alternative splicing and/or trans-splicing at different positions. On the basis of their trans-splicing pattern, their intergenic distances, and their expression, we suggest that lir-2, lir-1, and lin-26 form two overlapping transcriptional operons. The first operon, which is expressed in virtually all cells, includes lir-2 and long lir-1 isoforms. The second operon, which is expressed in the nonneuronal ectoderm, includes short lir-1 isoforms, starting at exon 2 and lin-26. This unusual genomic organization has been conserved in C. briggsae, as shown by cloning the C. briggsae lir-2, lir-1, and lin-26 homologs. Particularly striking is the sequence conservation throughout the first lir-1 intron, which is very long in both species. Structural conservation is functionally meaningful as C. briggsae lin-26 is also expressed in the nonneuronal ectoderm and can complement a C. elegans lin-26 null mutation.
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Affiliation(s)
- P Dufourcq
- IGBMC, CNRS/INSERM/ULP, 67404 Illkirch Cedex, France
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Legouis R, Quintin S, Labouesse M. Séquençage du génome de C. elegans : les éclats du ver. Med Sci (Paris) 1999. [DOI: 10.4267/10608/1410] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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Horner MA, Quintin S, Domeier ME, Kimble J, Labouesse M, Mango SE. pha-4, an HNF-3 homolog, specifies pharyngeal organ identity in Caenorhabditis elegans. Genes Dev 1998; 12:1947-52. [PMID: 9649499 PMCID: PMC316969 DOI: 10.1101/gad.12.13.1947] [Citation(s) in RCA: 176] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/1998] [Accepted: 04/28/1998] [Indexed: 11/25/2022]
Abstract
To build complex organs, embryos have evolved mechanisms that integrate the development of cells unrelated to one another by cell type or ancestry. Here we show that the pha-4 locus establishes organ identity for the Caenorhabditis elegans pharynx. In pha-4 mutants, pharyngeal cells are transformed into ectoderm. Conversely, ectopic pha-4 expression produces excess pharyngeal cells. pha-4 encodes an HNF-3 homolog selectively expressed in the nascent digestive tract, including all pharynx precursors at the time they are restricted to a pharyngeal fate. We suggest that pha-4 is a key component of a transcription-based mechanism to endow cells with pharyngeal organ identity.
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Affiliation(s)
- M A Horner
- Huntsman Cancer Institute, Center for Children, Department of Oncological Sciences, University of Utah, Salt Lake City, Utah 84112 USA
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