1
|
Lim YW, Wen FL, Shankar P, Shibata T, Motegi F. A balance between antagonizing PAR proteins specifies the pattern of asymmetric and symmetric divisions in C. elegans embryogenesis. Cell Rep 2021; 36:109326. [PMID: 34233197 DOI: 10.1016/j.celrep.2021.109326] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Revised: 03/05/2021] [Accepted: 06/08/2021] [Indexed: 10/20/2022] Open
Abstract
Coordination between cell differentiation and proliferation during development requires the balance between asymmetric and symmetric modes of cell division. However, the cellular intrinsic cue underlying the choice between these two division modes remains elusive. Here, we show evidence in Caenorhabditis elegans that the invariable lineage of the division modes is specified by the balance between antagonizing complexes of partitioning-defective (PAR) proteins. By uncoupling unequal inheritance of PAR proteins from that of fate determinants during cell division, we demonstrate that changes in the balance between PAR-2 and PAR-6 can be sufficient to re-program the division modes from symmetric to asymmetric and vice versa in two daughter cells. The division mode adopted occurs independently of asymmetry in cytoplasmic fate determinants, cell-size asymmetry, and cell-cycle asynchrony between sister cells. We propose that the balance between PAR proteins represents an intrinsic self-organizing cue for the specification of the two division modes during development.
Collapse
Affiliation(s)
- Yen Wei Lim
- Temasek Life-sciences Laboratory, Singapore 117604, Singapore; Department of Biological Sciences, National University of Singapore, Singapore 117583, Singapore
| | - Fu-Lai Wen
- RIKEN Center for Biosystems Dynamics Research, Kobe 650-0047, Japan
| | - Prabhat Shankar
- RIKEN Center for Biosystems Dynamics Research, Kobe 650-0047, Japan
| | - Tatsuo Shibata
- RIKEN Center for Biosystems Dynamics Research, Kobe 650-0047, Japan.
| | - Fumio Motegi
- Temasek Life-sciences Laboratory, Singapore 117604, Singapore; Department of Biological Sciences, National University of Singapore, Singapore 117583, Singapore; Mechanobiology Institute, National University of Singapore, Singapore 117411, Singapore; Institute for Genetic Medicine, Hokkaido University, Sapporo 060-0815, Japan.
| |
Collapse
|
2
|
Nomoto Y, Kubota Y, Ohnishi Y, Kasahara K, Tomita A, Oshime T, Yamashita H, Fahmi M, Ito M. Gene Cascade Finder: A tool for identification of gene cascades and its application in Caenorhabditis elegans. PLoS One 2019; 14:e0215187. [PMID: 31504044 PMCID: PMC6736238 DOI: 10.1371/journal.pone.0215187] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2019] [Accepted: 08/06/2019] [Indexed: 11/24/2022] Open
Abstract
Obtaining a comprehensive understanding of the gene regulatory networks, or gene cascades, involved in cell fate determination and cell lineage segregation in Caenorhabditis elegans is a long-standing challenge. Although RNA-sequencing (RNA-Seq) is a promising technique to resolve these questions, the bioinformatics tools to identify associated gene cascades from RNA-Seq data remain inadequate. To overcome these limitations, we developed Gene Cascade Finder (GCF) as a novel tool for building gene cascades by comparison of mutant and wild-type RNA-Seq data along with integrated information of protein-protein interactions, expression timing, and domains. Application of GCF to RNA-Seq data confirmed that SPN-4 and MEX-3 regulate the canonical Wnt pathway during embryonic development. Moreover, lin-35, hsp-3, and gpa-12 were found to be involved in MEX-1-dependent neurogenesis, and MEX-3 was found to control the gene cascade promoting neurogenesis through lin-35 and apl-1. Thus, GCF could be a useful tool for building gene cascades from RNA-Seq data.
Collapse
Affiliation(s)
- Yusuke Nomoto
- Advanced Life Sciences Program, Graduate School of Life Sciences, Ritsumeikan University, Kusatsu, Shiga, Japan
| | - Yukihiro Kubota
- Department of Bioinformatics, College of Life Sciences, Ritsumeikan University, Kusatsu, Shiga, Japan
| | - Yuto Ohnishi
- Advanced Life Sciences Program, Graduate School of Life Sciences, Ritsumeikan University, Kusatsu, Shiga, Japan
| | - Kota Kasahara
- Department of Bioinformatics, College of Life Sciences, Ritsumeikan University, Kusatsu, Shiga, Japan
| | - Aimi Tomita
- Advanced Life Sciences Program, Graduate School of Life Sciences, Ritsumeikan University, Kusatsu, Shiga, Japan
| | - Takehiro Oshime
- Advanced Life Sciences Program, Graduate School of Life Sciences, Ritsumeikan University, Kusatsu, Shiga, Japan
| | - Hiroki Yamashita
- Advanced Life Sciences Program, Graduate School of Life Sciences, Ritsumeikan University, Kusatsu, Shiga, Japan
| | - Muhamad Fahmi
- Department of Bioinformatics, College of Life Sciences, Ritsumeikan University, Kusatsu, Shiga, Japan
| | - Masahiro Ito
- Advanced Life Sciences Program, Graduate School of Life Sciences, Ritsumeikan University, Kusatsu, Shiga, Japan
- Department of Bioinformatics, College of Life Sciences, Ritsumeikan University, Kusatsu, Shiga, Japan
- * E-mail:
| |
Collapse
|
3
|
Davies T, Kim HX, Romano Spica N, Lesea-Pringle BJ, Dumont J, Shirasu-Hiza M, Canman JC. Cell-intrinsic and -extrinsic mechanisms promote cell-type-specific cytokinetic diversity. eLife 2018; 7:36204. [PMID: 30028292 PMCID: PMC6054530 DOI: 10.7554/elife.36204] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2018] [Accepted: 06/10/2018] [Indexed: 01/05/2023] Open
Abstract
Cytokinesis, the physical division of one cell into two, is powered by constriction of an actomyosin contractile ring. It has long been assumed that all animal cells divide by a similar molecular mechanism, but growing evidence suggests that cytokinetic regulation in individual cell types has more variation than previously realized. In the four-cell Caenorhabditis elegans embryo, each blastomere has a distinct cell fate, specified by conserved pathways. Using fast-acting temperature-sensitive mutants and acute drug treatment, we identified cell-type-specific variation in the cytokinetic requirement for a robust forminCYK-1-dependent filamentous-actin (F-actin) cytoskeleton. In one cell (P2), this cytokinetic variation is cell-intrinsically regulated, whereas in another cell (EMS) this variation is cell-extrinsically regulated, dependent on both SrcSRC-1 signaling and direct contact with its neighbor cell, P2. Thus, both cell-intrinsic and -extrinsic mechanisms control cytokinetic variation in individual cell types and can protect against division failure when the contractile ring is weakened. The successful division of one cell into two is essential for all organisms to live, grow and reproduce. For an animal cell, the nucleus – the compartment containing the genetic material – must divide before the surrounding material. The rest of the cell, called the cytoplasm, physically separates later in a process known as cytokinesis. Cytokinesis in animal cells is driven by the formation of a ring in the middle of the dividing cell. The ring is composed of myosin motor proteins and filaments made of a protein called actin. The movements of the motor proteins along the filaments cause the ring to contract and tighten. This pulls the cell membrane inward and physically pinches the cell into two. For a long time, the mechanism of cytokinesis was assumed to be same across different types of animal cell, but later evidence suggested otherwise. For example, in liver, heat and bone cells, cytokinesis naturally fails during development to create cells with two or more nuclei. If a similar ‘failure’ happened in other cell types, it could lead to diseases such as cancers or blood disorders. This raised the question: what are the molecular mechanisms that allow cytokinesis to happen differently in different cell types? Davies et al. investigated this question using embryos of the worm Caenorhabditis elegans at a stage in their development when they consist of just four cells. The proteins forming the contractile ring in this worm are the same as those in humans. However, in the worm, the contractile ring can easily be damaged using chemical inhibitors or by mutating the genes that encode its proteins. Davies et al. show that when the contractile ring was damaged, two of the four cells in the worm embryo still divided successfully. This result indicates the existence of new mechanisms to divide the cytoplasm that allow division even with a weak contractile ring. In a further experiment, the embryos were dissected to isolate each of the four cells. Davies et al. saw that one of the two dividing cells could still divide on its own, while the other cell could not. This shows that this new method of cytokinesis is regulated both by factors inherent to the dividing cell and by external signals from other cells. Moreover, one of these extrinsic signals was found to be a signaling protein that had previously been implicated in human cancers. Future work will determine if these variations in cytokinesis between the different cell types found in the worm apply to humans too; and, more importantly from a therapeutic standpoint, if these new mechanisms exist in human cancers.
Collapse
Affiliation(s)
- Tim Davies
- Department of Pathology and Cell Biology, Columbia University Medical Center, New York, United States
| | - Han X Kim
- Department of Pathology and Cell Biology, Columbia University Medical Center, New York, United States.,Department of Genetics and Development, Columbia University Medical Center, New York, United States
| | - Natalia Romano Spica
- Department of Pathology and Cell Biology, Columbia University Medical Center, New York, United States
| | - Benjamin J Lesea-Pringle
- Department of Pathology and Cell Biology, Columbia University Medical Center, New York, United States
| | - Julien Dumont
- Institut Jacques Monod, CNRS UMR 7592, Université Paris Diderot, Paris, France
| | - Mimi Shirasu-Hiza
- Department of Genetics and Development, Columbia University Medical Center, New York, United States
| | - Julie C Canman
- Department of Pathology and Cell Biology, Columbia University Medical Center, New York, United States
| |
Collapse
|
4
|
Kadekar P, Chaouni R, Clark E, Kazanets A, Roy R. Genome-wide surveys reveal polarity and cytoskeletal regulators mediate LKB1-associated germline stem cell quiescence. BMC Genomics 2018; 19:462. [PMID: 29907081 PMCID: PMC6003023 DOI: 10.1186/s12864-018-4847-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Accepted: 05/31/2018] [Indexed: 12/22/2022] Open
Abstract
Background Caenorhabditis elegans can endure long periods of environmental stress by altering their development to execute a quiescent state called “dauer”. Previous work has implicated LKB1 - the causative gene in the autosomal dominant, cancer pre-disposing disease called Peutz-Jeghers Syndrome (PJS), and its downstream target AMPK, in the establishment of germline stem cell (GSC) quiescence during the dauer stage. Loss of function mutations in both LKB1/par-4 and AMPK/aak(0) result in untimely GSC proliferation during the onset of the dauer stage, although the molecular mechanism through which these factors regulate quiescence remains unclear. Curiously, the hyperplasia observed in par-4 mutants is more severe than AMPK-compromised dauer larvae, suggesting that par-4 has alternative downstream targets in addition to AMPK to regulate germline quiescence. Results We conducted three genome-wide RNAi screens to identify potential downstream targets of the protein kinases PAR-4 and AMPK that mediate dauer-dependent GSC quiescence. First, we screened to identify genes that phenocopy the par-4-dependent hyperplasia when compromised by RNAi. Two additional RNAi screens were performed to identify genes that suppressed the germline hyperplasia in par-4 and aak(0) dauer larvae, respectively. Interestingly, a subset of the candidates we identified are involved in the regulation of cell polarity and cytoskeletal function downstream of par-4, in an AMPK-independent manner. Moreover, we show that par-4 temporally regulates actin cytoskeletal organization within the dauer germ line at the rachis-adjacent membrane, in an AMPK-independent manner. Conclusion Our data suggest that the regulation of the cytoskeleton and cell polarity may contribute significantly to the tumour suppressor function of LKB1/par-4. Electronic supplementary material The online version of this article (10.1186/s12864-018-4847-y) contains supplementary material, which is available to authorized users.
Collapse
Affiliation(s)
- Pratik Kadekar
- Department of Biology, McGill University, 1205 avenue Docteur Penfield, Montreal, Quebec, H3A 1B1, Canada
| | - Rita Chaouni
- Department of Biology, McGill University, 1205 avenue Docteur Penfield, Montreal, Quebec, H3A 1B1, Canada
| | - Emily Clark
- Department of Biology, McGill University, 1205 avenue Docteur Penfield, Montreal, Quebec, H3A 1B1, Canada
| | - Anna Kazanets
- Department of Biology, McGill University, 1205 avenue Docteur Penfield, Montreal, Quebec, H3A 1B1, Canada
| | - Richard Roy
- Department of Biology, McGill University, 1205 avenue Docteur Penfield, Montreal, Quebec, H3A 1B1, Canada.
| |
Collapse
|
5
|
Gerhold AR, Poupart V, Labbé JC, Maddox PS. Spindle assembly checkpoint strength is linked to cell fate in the Caenorhabditis elegans embryo. Mol Biol Cell 2018; 29:1435-1448. [PMID: 29688794 PMCID: PMC6014101 DOI: 10.1091/mbc.e18-04-0215] [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] [Indexed: 12/20/2022] Open
Abstract
The spindle assembly checkpoint (SAC) is a conserved mitotic regulator that preserves genome stability by monitoring kinetochore-microtubule attachments and blocking anaphase onset until chromosome biorientation is achieved. Despite its central role in maintaining mitotic fidelity, the ability of the SAC to delay mitotic exit in the presence of kinetochore-microtubule attachment defects (SAC "strength") appears to vary widely. How different cellular aspects drive this variation remains largely unknown. Here we show that SAC strength is correlated with cell fate during development of Caenorhabditis elegans embryos, with germline-fated cells experiencing longer mitotic delays upon spindle perturbation than somatic cells. These differences are entirely dependent on an intact checkpoint and only partially attributable to differences in cell size. In two-cell embryos, cell size accounts for half of the difference in SAC strength between the larger somatic AB and the smaller germline P1 blastomeres. The remaining difference requires asymmetric cytoplasmic partitioning downstream of PAR polarity proteins, suggesting that checkpoint-regulating factors are distributed asymmetrically during early germ cell divisions. Our results indicate that SAC activity is linked to cell fate and reveal a hitherto unknown interaction between asymmetric cell division and the SAC.
Collapse
Affiliation(s)
- Abigail R Gerhold
- Institute for Research in Immunology and Cancer (IRIC), Université de Montréal, Succ. Centre-ville, Montréal, QC H3C 3J7, Canada
| | - Vincent Poupart
- Institute for Research in Immunology and Cancer (IRIC), Université de Montréal, Succ. Centre-ville, Montréal, QC H3C 3J7, Canada
| | - Jean-Claude Labbé
- Institute for Research in Immunology and Cancer (IRIC), Université de Montréal, Succ. Centre-ville, Montréal, QC H3C 3J7, Canada.,Department of Pathology and Cell Biology, Université de Montréal, Succ. Centre-ville, Montréal, QC H3C 3J7, Canada
| | - Paul S Maddox
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
| |
Collapse
|
6
|
Kaymak E, Farley BM, Hay SA, Li C, Ho S, Hartman DJ, Ryder SP. Efficient generation of transgenic reporter strains and analysis of expression patterns in Caenorhabditis elegans using library MosSCI. Dev Dyn 2016; 245:925-36. [PMID: 27294288 PMCID: PMC4981527 DOI: 10.1002/dvdy.24426] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2016] [Revised: 05/09/2016] [Accepted: 06/03/2016] [Indexed: 01/03/2023] Open
Abstract
BACKGROUND In C. elegans, germline development and early embryogenesis rely on posttranscriptional regulation of maternally transcribed mRNAs. In many cases, the 3' untranslated region (UTR) is sufficient to govern the expression patterns of these transcripts. Several RNA-binding proteins are required to regulate maternal mRNAs through the 3'UTR. Despite intensive efforts to map RNA-binding protein-mRNA interactions in vivo, the biological impact of most binding events remains unknown. Reporter studies using single copy integrated transgenes are essential to evaluate the functional consequences of interactions between RNA-binding proteins and their associated mRNAs. RESULTS In this report, we present an efficient method of generating reporter strains with improved throughput by using a library variant of MosSCI transgenesis. Furthermore, using RNA interference, we identify the suite of RNA-binding proteins that control the expression pattern of five different maternal mRNAs. CONCLUSIONS The results provide a generalizable and efficient strategy to assess the functional relevance of protein-RNA interactions in vivo, and reveal new regulatory connections between key RNA-binding proteins and their maternal mRNA targets. Developmental Dynamics 245:925-936, 2016. © 2016 Wiley Periodicals, Inc.
Collapse
Affiliation(s)
- Ebru Kaymak
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA, 01605, USA
| | - Brian M. Farley
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, 94720, USA
| | - Samantha A. Hay
- Virginia Commonwealth University School of Medicine, VA, USA
| | - Chihua Li
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA, 01605, USA
| | - Samantha Ho
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA, 01605, USA
| | | | - Sean P. Ryder
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA, 01605, USA
| |
Collapse
|
7
|
Calderón-Urrea A, Vanholme B, Vangestel S, Kane SM, Bahaji A, Pha K, Garcia M, Snider A, Gheysen G. Early development of the root-knot nematode Meloidogyne incognita. BMC DEVELOPMENTAL BIOLOGY 2016; 16:10. [PMID: 27122249 PMCID: PMC4848817 DOI: 10.1186/s12861-016-0109-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/08/2016] [Accepted: 04/15/2016] [Indexed: 11/15/2022]
Abstract
BACKGROUND Detailed descriptions of the early development of parasitic nematodes are seldom available. The embryonic development of the plant-parasitic nematode Meloidogyne incognita was studied, focusing on the early events. RESULTS A fixed pattern of repeated cell cleavages was observed, resulting in the appearance of the six founder cells 3 days after the first cell division. Gastrulation, characterized by the translocation of cells from the ventral side to the center of the embryo, was seen 1 day later. Approximately 10 days after the first cell division a rapidly elongating two-fold stage was reached. The fully developed second stage juvenile hatched approximately 21 days after the first cell division. CONCLUSIONS When compared to the development of the free-living nematode Caenorhabditis elegans, the development of M. incognita occurs approximately 35 times more slowly. Furthermore, M. incognita differs from C. elegans in the order of cell divisions, and the early cleavage patterns of the germ line cells. However, cytoplasmic ruffling and nuclear migration prior to the first cell division as well as the localization of microtubules are similar between C. elegans and M. incognita.
Collapse
Affiliation(s)
- Alejandro Calderón-Urrea
- />Department of Biology, College of Science and Mathematics, California State University, 2555 East San Ramon Avenue, Fresno, CA 93740 USA
| | - Bartel Vanholme
- />Department of Plant Systems Biology, VIB, Technologiepark 927, B-9052 Ghent, Belgium
- />Department of Plant Biotechnology and Bioinformatics, Ghent University, Technologiepark 927, B-9052 Ghent, Belgium
| | - Sandra Vangestel
- />Faculty of Sciences, Department of Biology, Ghent University, K.L. Ledeganckstraat 35, B-9000 Ghent, Belgium
| | - Saben M. Kane
- />Department of Biology, College of Science and Mathematics, California State University, 2555 East San Ramon Avenue, Fresno, CA 93740 USA
| | - Abdellatif Bahaji
- />Instituto de Agrobiotecnologia (CSIC/UPNA/Gobierno de Navarra), Ctra. de mutilva baja, s/n 31192, Mutilva Baja, Navarra Spain
| | - Khavong Pha
- />Biochemistry, Molecular, Cell, and Developmental Biology Graduate Group, Department of Microbiology and Molecular Genetics, University of California, 1 Shields Avenue, Davis, CA 95616 USA
| | - Miguel Garcia
- />Department of Biology, James H. Clark Center, Stanford University, 318 Campus Drive, W200, Stanford, CA 94305 USA
| | - Alyssa Snider
- />IVIGEN Los Angeles, 406 Amapola Ave. Suite 215, Torrance, CA 90501 USA
| | - Godelieve Gheysen
- />Faculty of Bioscience Engineering, Department of Molecular Biotechnology, BW14, Ghent University, Coupure links 653, B-9000 Ghent, Belgium
| |
Collapse
|
8
|
Wong MK, Guan D, Ng KHC, Ho VWS, An X, Li R, Ren X, Zhao Z. Timing of Tissue-specific Cell Division Requires a Differential Onset of Zygotic Transcription during Metazoan Embryogenesis. J Biol Chem 2016; 291:12501-12513. [PMID: 27056332 DOI: 10.1074/jbc.m115.705426] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2015] [Indexed: 12/20/2022] Open
Abstract
Metazoan development demands not only precise cell fate differentiation but also accurate timing of cell division to ensure proper development. How cell divisions are temporally coordinated during development is poorly understood. Caenorhabditis elegans embryogenesis provides an excellent opportunity to study this coordination due to its invariant development and widespread division asynchronies. One of the most pronounced asynchronies is a significant delay of cell division in two endoderm progenitor cells, Ea and Ep, hereafter referred to as E2, relative to its cousins that mainly develop into mesoderm organs and tissues. To unravel the genetic control over the endoderm-specific E2 division timing, a total of 822 essential and conserved genes were knocked down using RNAi followed by quantification of cell cycle lengths using in toto imaging of C. elegans embryogenesis and automated lineage. Intriguingly, knockdown of numerous genes encoding the components of general transcription pathway or its regulatory factors leads to a significant reduction in the E2 cell cycle length but an increase in cell cycle length of the remaining cells, indicating a differential requirement of transcription for division timing between the two. Analysis of lineage-specific RNA-seq data demonstrates an earlier onset of transcription in endoderm than in other germ layers, the timing of which coincides with the birth of E2, supporting the notion that the endoderm-specific delay in E2 division timing demands robust zygotic transcription. The reduction in E2 cell cycle length is frequently associated with cell migration defect and gastrulation failure. The results suggest that a tissue-specific transcriptional activation is required to coordinate fate differentiation, division timing, and cell migration to ensure proper development.
Collapse
Affiliation(s)
- Ming-Kin Wong
- Department of Biology, Hong Kong Baptist University, Hong Kong Baptist University, Hong Kong, China
| | - Daogang Guan
- Department of Biology, Hong Kong Baptist University, Hong Kong Baptist University, Hong Kong, China
| | - Kaoru Hon Chun Ng
- Department of Biology, Hong Kong Baptist University, Hong Kong Baptist University, Hong Kong, China
| | - Vincy Wing Sze Ho
- Department of Biology, Hong Kong Baptist University, Hong Kong Baptist University, Hong Kong, China
| | - Xiaomeng An
- Department of Biology, Hong Kong Baptist University, Hong Kong Baptist University, Hong Kong, China
| | - Runsheng Li
- Department of Biology, Hong Kong Baptist University, Hong Kong Baptist University, Hong Kong, China
| | - Xiaoliang Ren
- Department of Biology, Hong Kong Baptist University, Hong Kong Baptist University, Hong Kong, China
| | - Zhongying Zhao
- Department of Biology, Hong Kong Baptist University, Hong Kong Baptist University, Hong Kong, China; State Key Laboratory of Environmental and Biological Analysis, Hong Kong Baptist University, Hong Kong, China.
| |
Collapse
|
9
|
Xu C, Su Z. Identification of genes driving lineage divergence from single-cell gene expression data in C. elegans. Dev Biol 2014; 393:236-244. [PMID: 25050933 DOI: 10.1016/j.ydbio.2014.07.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2013] [Revised: 07/09/2014] [Accepted: 07/11/2014] [Indexed: 11/25/2022]
Abstract
The nematode Caenorhabditis elegans (C. elegans) is an ideal model organism to study the cell fate specification mechanisms during embryogenesis. It is generally believed that cell fate specification in C. elegans is mainly mediated by lineage-based mechanisms, where the specification paths are driven forward by a succession of asymmetric cell divisions. However, little is known about how each binary decision is made by gene regulatory programs. In this study, we endeavor to obtain a global understanding of cell lineage/fate divergence processes during the early embryogenesis of C. elegans. We reanalyzed the EPIC data set, which traced the expression level of reporter genes at single-cell resolution on a nearly continuous time scale up to the 350-cell stage in C. elegans embryos. We examined the expression patterns for a total of 131 genes from 287 embryos with high quality image recordings, among which 86 genes have replicate embryos. Our results reveal that during early embryogenesis, divergence between sister lineages could be largely explained by a few genes. We predicted genes driving lineage divergence and explored their expression patterns in sister lineages. Moreover, we found that divisions leading to fate divergence are associated with a large number of genes being differentially expressed between sister lineages. Interestingly, we found that the developmental paths of lineages could be differentiated by a small set of genes. Therefore, our results support the notion that the cell fate patterns in C. elegans are achieved through stepwise binary decisions punctuated by cell divisions. Our predicted genes driving lineage divergence provide good starting points for future detailed characterization of their roles in the embryogenesis in this important model organism.
Collapse
Affiliation(s)
- Chen Xu
- Department of Bioinformatics and Genomics, The University of North Carolina at Charlotte, 351 Bioinformatics Building, 9201 University City Blvd, Charlotte, NC 28223, USA.
| | - Zhengchang Su
- Department of Bioinformatics and Genomics, The University of North Carolina at Charlotte, 351 Bioinformatics Building, 9201 University City Blvd, Charlotte, NC 28223, USA.
| |
Collapse
|
10
|
Du Z, Santella A, He F, Tiongson M, Bao Z. De novo inference of systems-level mechanistic models of development from live-imaging-based phenotype analysis. Cell 2014; 156:359-72. [PMID: 24439388 PMCID: PMC3998820 DOI: 10.1016/j.cell.2013.11.046] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2013] [Revised: 09/25/2013] [Accepted: 11/11/2013] [Indexed: 12/21/2022]
Abstract
Elucidation of complex phenotypes for mechanistic insights presents a significant challenge in systems biology. We report a strategy to automatically infer mechanistic models of cell fate differentiation based on live-imaging data. We use cell lineage tracing and combinations of tissue-specific marker expression to assay progenitor cell fate and detect fate changes upon genetic perturbation. Based on the cellular phenotypes, we further construct a model for how fate differentiation progresses in progenitor cells and predict cell-specific gene modules and cell-to-cell signaling events that regulate the series of fate choices. We validate our approach in C. elegans embryogenesis by perturbing 20 genes in over 300 embryos. The result not only recapitulates current knowledge but also provides insights into gene function and regulated fate choice, including an unexpected self-renewal. Our study provides a powerful approach for automated and quantitative interpretation of complex in vivo information.
Collapse
Affiliation(s)
- Zhuo Du
- Developmental Biology Program, Sloan-Kettering Institute, New York, NY 10065, USA
| | - Anthony Santella
- Developmental Biology Program, Sloan-Kettering Institute, New York, NY 10065, USA
| | - Fei He
- Developmental Biology Program, Sloan-Kettering Institute, New York, NY 10065, USA
| | - Michael Tiongson
- Developmental Biology Program, Sloan-Kettering Institute, New York, NY 10065, USA
| | - Zhirong Bao
- Developmental Biology Program, Sloan-Kettering Institute, New York, NY 10065, USA.
| |
Collapse
|
11
|
Par6b regulates the dynamics of apicobasal polarity during development of the stratified Xenopus epidermis. PLoS One 2013; 8:e76854. [PMID: 24204686 PMCID: PMC3800127 DOI: 10.1371/journal.pone.0076854] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2013] [Accepted: 08/28/2013] [Indexed: 11/30/2022] Open
Abstract
During early vertebrate development, epithelial cells establish and maintain apicobasal polarity, failure of which can cause developmental defects or cancer metastasis. This process has been mostly studied in simple epithelia that have only one layer of cells, but is poorly understood in stratified epithelia. In this paper we address the role of the polarity protein Partitioning defective-6 homolog beta (Par6b) in the developing stratified epidermis of Xenopus laevis. At the blastula stage, animal blastomeres divide perpendicularly to the apicobasal axis to generate partially polarized superficial cells and non-polarized deep cells. Both cell populations modify their apicobasal polarity during the gastrula stage, before differentiating into the superficial and deep layers of epidermis. Early differentiation of the epidermis is normal in Par6b-depleted embryos; however, epidermal cells dissociate and detach from embryos at the tailbud stage. Par6b-depleted epidermal cells exhibit a significant reduction in basolaterally localized E-cadherin. Examination of the apical marker Crumbs homolog 3 (Crb3) and the basolateral marker Lethal giant larvae 2 (Lgl2) after Par6b depletion reveals that Par6b cell-autonomously regulates the dynamics of apicobasal polarity in both superficial and deep epidermal layers. Par6b is required to maintain the “basolateral” state in both epidermal layers, which explains the reduction of basolateral adhesion complexes and epidermal cells shedding.
Collapse
|
12
|
|
13
|
Analysis of cell fate from single-cell gene expression profiles in C. elegans. Cell 2009; 139:623-33. [PMID: 19879847 DOI: 10.1016/j.cell.2009.08.044] [Citation(s) in RCA: 114] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2008] [Revised: 05/21/2009] [Accepted: 08/18/2009] [Indexed: 11/23/2022]
Abstract
The C. elegans cell lineage provides a unique opportunity to look at how cell lineage affects patterns of gene expression. We developed an automatic cell lineage analyzer that converts high-resolution images of worms into a data table showing fluorescence expression with single-cell resolution. We generated expression profiles of 93 genes in 363 specific cells from L1 stage larvae and found that cells with identical fates can be formed by different gene regulatory pathways. Molecular signatures identified repeating cell fate modules within the cell lineage and enabled the generation of a molecular differentiation map that reveals points in the cell lineage when developmental fates of daughter cells begin to diverge. These results demonstrate insights that become possible using computational approaches to analyze quantitative expression from many genes in parallel using a digital gene expression atlas.
Collapse
|
14
|
Hara Y, Kimura A. Cell-size-dependent spindle elongation in the Caenorhabditis elegans early embryo. Curr Biol 2009; 19:1549-54. [PMID: 19682904 DOI: 10.1016/j.cub.2009.07.050] [Citation(s) in RCA: 106] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2009] [Revised: 07/13/2009] [Accepted: 07/13/2009] [Indexed: 12/23/2022]
Abstract
Cell size is one of the critical parameters controlling the size of intracellular structures. A well-known example is the constant nuclear-to-cytoplasmic ratio (N/C ratio) [1-5]. The length of the metaphase spindle is proportional to cell size, but it has an upper limit during early embryogenesis [6]. During anaphase, the mitotic spindle elongates and delivers the centrosomes and sister chromatids near the centers of the nascent daughter cells. Here, we quantified the relationship between spindle elongation and cell size in the early embryo of Caenorhabditis elegans and propose possible models for cell-size-dependent spindle elongation. Quantitative measurements revealed that the extent and speed of spindle elongation are correlated with cell size throughout early embryogenesis. RNAi knockdown of Galpha proteins and their regulators revealed that the spindles failed to fully elongate and that the speed of spindle elongation was almost constant regardless of cell size. Our results suggest that spindle elongation is controlled by two qualitatively distinct mechanisms, i.e., Galpha-dependent and -independent modes of elongation. Simulation analyses revealed that the constant-pulling model and the force-generator-limited model reproduced the dynamics of the Galpha-independent and Galpha-dependent mechanisms, respectively. These models also explain how the set length of spindles is achieved.
Collapse
Affiliation(s)
- Yuki Hara
- Cell Architecture Laboratory, Center for Frontier Research, National Institute of Genetics, Yata 1111, Mishima, Shizuoka 411-8540, Japan
| | | |
Collapse
|
15
|
Abstract
A GAG deletion in the DYT1 gene is responsible for the autosomal dominant movement disorder, early onset primary torsion dystonia, which is characterised by involuntary sustained muscle contractions and abnormal posturing of the limbs. The mutation leads to deletion of a single glutamate residue in the C-terminus of the protein torsinA, a member of the AAA+ ATPase family of proteins with multiple functions. Since no evidence of neurodegeneration has been found in DYT1 patients, the dystonic phenotype is likely to be the result of neuronal functional defect(s), the nature of which is only partially understood. Biochemical, structural and cell biological studies have been performed in order to characterise torsinA. These studies, together with the generation of several animal models, have contributed to identify cellular compartments and pathways, including the cytoskeleton and the nuclear envelope, the secretory pathway and the synaptic vesicle machinery where torsinA function may be crucial. However, the role of torsinA and the correlation between the dysfunction caused by the mutation and the dystonic phenotype remain unclear. This review provides an overview of the findings of the last ten years of research on torsinA, a critical evaluation of the different models proposed and insights towards future avenues of research.
Collapse
Affiliation(s)
- Alessandra Granata
- Department of Clinical Neurosciences, UCL Institute of Neurology, London, UK.
| | | | | |
Collapse
|
16
|
Courchet J, Buchet-Poyau K, Potemski A, Brès A, Jariel-Encontre I, Billaud M. Interaction with 14-3-3 adaptors regulates the sorting of hMex-3B RNA-binding protein to distinct classes of RNA granules. J Biol Chem 2008; 283:32131-42. [PMID: 18779327 DOI: 10.1074/jbc.m802927200] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Stress granules (SG) and processing bodies (PBs) are cytoplasmic ribonucleoprotein particles whose assembly is induced by different stimuli. SG are the site of storage of untranslated transcripts formed in response to environmental stress, whereas PBs are involved in mRNA turnover. We recently characterized a novel family of four human proteins related to the Caenorhabditis elegans Mex-3, a RNA binding protein involved in the establishment of the anterior-posterior embryonic asymmetry and in the maintenance of germline pluripotency. We now report that the adaptor proteins 14-3-3 bind to hMex-3B but not to the three other hMex-3 family members. Serine 462, when phosphorylated, is the major 14-3-3 docking site on hMex-3B, and manipulation of this interaction reveals that 14-3-3 both stabilizes hMex-3B and modulates its ability to bind RNA. Furthermore, the complex formed between hMex-3B and Argonaute proteins is excluded from PBs when the interaction with 14-3-3 is disrupted, whereas the recruitment to SG is not affected. Thus, 14-3-3 exerts combined effects on hMex-3B and acts as a major regulator of the sorting between distinct classes of RNA granules.
Collapse
Affiliation(s)
- Julien Courchet
- CNRS UMR5201, Laboratoire de Génétique Moléculaire, Signalisation et Cancer, Lyon F-69008, France
| | | | | | | | | | | |
Collapse
|
17
|
Zhang H, Skop AR, White JG. Src and Wnt signaling regulate dynactin accumulation to the P2-EMS cell border in C. elegans embryos. J Cell Sci 2008; 121:155-61. [PMID: 18187449 DOI: 10.1242/jcs.015966] [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] [Indexed: 05/11/2024] Open
Abstract
In many organisms, the dynein-dynactin complex is required for the alignment of the mitotic spindle onto the axis of polarity of a cell undergoing asymmetric cell division. How this complex transduces polarity cues, either intrinsic or extrinsic, and rotationally aligns the spindle accordingly is not well understood. The Caenorhabditis elegans blastomere P2 polarizes the neighboring EMS blastomere, which causes the EMS spindle to rotationally align along the defined axis of polarity via two redundant signaling pathways: Wnt and Src. Here, we describe how components of the dynactin complex became locally enriched at the P2-EMS border prior to and during rotational alignment of their spindles. Wnt and Src signaling were required for both localized dynactin enrichment, and for rotational alignment of the P2 and EMS spindles. Depleting the trimeric G-protein subunit G alpha did not abolish dynactin accumulation to the P2-EMS border, yet both EMS and P2 spindles failed to rotationally align, indicating that G alpha might act to regulate dynein/dynactin motor activity. By RNAi of a weak dnc-1(ts) allele, we showed that dynactin activity was required at least for EMS spindle rotational alignment.
Collapse
Affiliation(s)
- Haining Zhang
- Laboratory of Genetics, University of Wisconsin, Madison, WI 53706, USA
| | | | | |
Collapse
|
18
|
Poole RJ, Hobert O. Early embryonic programming of neuronal left/right asymmetry in C. elegans. Curr Biol 2007; 16:2279-92. [PMID: 17141609 DOI: 10.1016/j.cub.2006.09.041] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2006] [Revised: 09/20/2006] [Accepted: 09/25/2006] [Indexed: 10/23/2022]
Abstract
BACKGROUND Nervous systems are largely bilaterally symmetric on a morphological level but often display striking degrees of functional left/right (L/R) asymmetry. How L/R asymmetric functional features are superimposed onto an essentially bilaterally symmetric structure and how nervous-system laterality relates to the L/R asymmetry of internal organs are poorly understood. We address these questions here by using the establishment of L/R asymmetry in the ASE chemosensory neurons of C. elegans as a paradigm. This bilaterally symmetric neuron pair is functionally lateralized in that it senses a distinct class of chemosensory cues and expresses a putative chemoreceptor family in a L/R asymmetric manner. RESULTS We show that the directionality of the asymmetry of the two postmitotic ASE neurons ASE left (ASEL) and ASE right (ASER) in adults is dependent on a L-/R-symmetry-breaking event at a very early embryonic stage, the six-cell stage, which also establishes the L/R asymmetric placement of internal organs. However, the L/R asymmetry of the ASE neurons per se is dependent on an even earlier anterior-posterior (A/P) Notch signal that specifies embryonic ABa/ABp blastomere identities at the four-cell stage. This Notch signal, which functions through two T box genes, acts genetically upstream of a miRNA-controlled bistable feedback loop that regulates the L/R asymmetric gene-expression program in the postmitotic ASE cells. CONCLUSIONS Our results link adult neuronal laterality to the generation of the A/P axis at the two-cell stage and raise the possibility that neural asymmetries observed across the animal kingdom are similarly established by very early embryonic interactions.
Collapse
Affiliation(s)
- Richard J Poole
- Howard Hughes Medical Institute, Department of Biochemistry and Molecular Biophysics, Columbia University Medical Center, New York, New York 10032, USA
| | | |
Collapse
|
19
|
Röttinger E, Besnardeau L, Lepage T. Expression pattern of three putative RNA-binding proteins during early development of the sea urchin Paracentrotus lividus. Gene Expr Patterns 2006; 6:864-72. [PMID: 17061352 DOI: 10.1016/j.modgep.2006.02.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
We report the expression patterns of three transcripts encoding RNA-binding proteins during early development of the Mediterranean sea urchin Paracentrotus lividus. Two of these genes encode KH-domains RNA-binding proteins closely related to the vertebrate neuro-oncological ventral antigen 1 (Nova) and RING Finger and KH-domain (RKHD). The third encodes the sea urchin ortholog of the polypyrimidine tract binding protein (PTB). Zygotic expression of nova and rkhd starts at mesenchyme blastula stage and is restricted to the presumptive endoderm territory. During gastrulation, expression of nova is restricted to the midgut and hindgut, while expression of rkhd become more complex and includes the foregut and hindgut territories as well as previously unknown territories within the ectoderm. PTB is first expressed ubiquitously but starting at the late gastrula stage, then PTB transcripts become highly enriched in the foregut and oral ectoderm. We further report that expression of nova and rkhd in the endomesoderm is under the control of the Wnt/beta-catenin pathway and occurs in a cell-autonomous manner while expression of rkhd and PTB in the oral ectoderm is regulated by Nodal signaling.
Collapse
Affiliation(s)
- Eric Röttinger
- UMR7009/CNRS, Université de Paris VI, Biologie du Développement, Observatoire Océanologique, 06230 Villefranche sur Mer, France
| | | | | |
Collapse
|
20
|
Tenlen JR, Schisa JA, Diede SJ, Page BD. Reduced dosage of pos-1 suppresses Mex mutants and reveals complex interactions among CCCH zinc-finger proteins during Caenorhabditis elegans embryogenesis. Genetics 2006; 174:1933-45. [PMID: 17028349 PMCID: PMC1698638 DOI: 10.1534/genetics.105.052621] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Cell fate specification in the early C. elegans embryo requires the activity of a family of proteins with CCCH zinc-finger motifs. Two members of the family, MEX-5 and MEX-6, are enriched in the anterior of the early embryo where they inhibit the accumulation of posterior proteins. Embryos from mex-5 single-mutant mothers are inviable due to the misexpression of SKN-1, a transcription factor that can specify mesoderm and endoderm. The aberrant expression of SKN-1 causes a loss of hypodermal and neuronal tissue and an excess of pharyngeal muscle, a Mex phenotype (muscle excess). POS-1, a third protein with CCCH motifs, is concentrated in the posterior of the embryo where it restricts the expression of at least one protein to the anterior. We discovered that reducing the dosage of pos-1(+) can suppress the Mex phenotype of mex-5(-) embryos and that POS-1 binds the 3'-UTR of mex-6. We propose that the suppression of the Mex phenotype by reducing pos-1(+) is due to decreased repression of mex-6 translation. Our detailed analyses of these protein functions reveal complex interactions among the CCCH finger proteins and suggest that their complementary expression patterns might be refined by antagonistic interactions among them.
Collapse
Affiliation(s)
- Jennifer R Tenlen
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
| | | | | | | |
Collapse
|
21
|
Zhou Y, Kaye PL, Pantaleon M. Identification of the facilitative glucose transporter 12 gene Glut12 in mouse preimplantation embryos. Gene Expr Patterns 2005; 4:621-31. [PMID: 15465484 DOI: 10.1016/j.modgep.2004.04.010] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2004] [Revised: 04/28/2004] [Accepted: 04/28/2004] [Indexed: 10/26/2022]
Abstract
In this study we report the cloning and characterisation of the mouse Glut12 gene and examine for the first time its expression pattern in the earliest stages of development. Mouse Glut12 (mGlut12) was cloned from preimplantation embryos by 5'RACE RT-PCR using primers designed from an EST clone corresponding to a human GLUT12 antigenic sequence after positive immunoreactivity was observed in mouse two-cell embryos by western immunoblotting. The mGlut12 gene contains an open reading frame of 1869 base pairs, potentially encoding a polypeptide of 622 amino acids. The predicted mGLUT12 protein bears all the hallmarks of the SLC2A family of hexose transporters and shares an 83% sequence homology to human GLUT12. Consistent with its human homolog mGlut12 mRNA is found highly expressed in skeletal and cardiac muscle and fat. Additionally, it was also found in the uterus and during early embryogenesis. During early development in the mouse, Glut12 expression is clearly apparent in ovulated oocytes and two-cell embryos but declines in day 3 morulae. With the exception of some Glut12 expression apparent in blastocysts, Glut12 mRNA remains at low to undetectable levels until E11.
Collapse
Affiliation(s)
- Yuchan Zhou
- Department of Physiology and Pharmacology, School Of Biomedical Sciences, The University of Queensland, Brisbane, Qld 4072, Australia
| | | | | |
Collapse
|
22
|
Baas AF, Kuipers J, van der Wel NN, Batlle E, Koerten HK, Peters PJ, Clevers HC. Complete polarization of single intestinal epithelial cells upon activation of LKB1 by STRAD. Cell 2004; 116:457-66. [PMID: 15016379 DOI: 10.1016/s0092-8674(04)00114-x] [Citation(s) in RCA: 389] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2003] [Revised: 12/17/2003] [Accepted: 01/12/2004] [Indexed: 12/23/2022]
Abstract
The LKB1 gene encodes a serine/threonine kinase that is mutated in the Peutz-Jeghers cancer syndrome. LKB1 is homologous to the Par-4 polarity genes in C. elegans and D. melanogaster. We have previously reported the identification and characterization of an LKB1-specific adaptor protein, STRAD, which activates LKB1 and translocates it from nucleus to cytoplasm. We have now constructed intestinal epithelial cell lines in which inducible STRAD activates LKB1. Upon LKB1 activation, single cells rapidly remodel their actin cytoskeleton to form an apical brush border. The junctional proteins ZO-1 and p120 redistribute in a dotted circle peripheral to the brush border, in the absence of cell-cell contacts. Apical and basolateral markers sort to their respective membrane domains. We conclude that LKB1 can induce complete polarity in intestinal epithelial cells. In contrast to current thinking on polarization of simple epithelia, these cells can fully polarize in the absence of junctional cell-cell contacts.
Collapse
Affiliation(s)
- Annette F Baas
- Hubrecht Laboratory, Center for Biomedical Genetics, Uppsalalaan 8, 3584 CT Utrecht, The Netherlands
| | | | | | | | | | | | | |
Collapse
|
23
|
Walker AK, Shi Y, Blackwell TK. An extensive requirement for transcription factor IID-specific TAF-1 in Caenorhabditis elegans embryonic transcription. J Biol Chem 2004; 279:15339-47. [PMID: 14726532 DOI: 10.1074/jbc.m310731200] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The general transcription factor TFIID sets the mRNA start site and consists of TATA-binding protein and associated factors (TAF(II)s), some of which are also present in SPT-ADA-GCN5 (SAGA)-related complexes. In yeast, results of multiple studies indicate that TFIID-specific TAF(II)s are not required for the transcription of most genes, implying that intact TFIID may have a surprisingly specialized role in transcription. Relatively little is known about how TAF(II)s contribute to metazoan transcription in vivo, especially at developmental and tissue-specific genes. Previously, we investigated functions of four shared TFIID/SAGA TAF(II)s in Caenorhabditis elegans. Whereas TAF-4 was required for essentially all embryonic transcription, TAF-5, TAF-9, and TAF-10 were dispensable at multiple developmental and other metazoan-specific promoters. Here we show evidence that in C. elegans embryos transcription of most genes requires TFIID-specific TAF-1. TAF-1 is not as universally required as TAF-4, but it is essential for a greater proportion of transcription than TAF-5, -9, or -10 and is important for transcription of many developmental and other metazoan-specific genes. TAF-2, which binds core promoters with TAF-1, appears to be required for a similarly substantial proportion of transcription. C. elegans TAF-1 overlaps functionally with the coactivator p300/CBP (CBP-1), and at some genes it is required along with the TBP-like protein TLF(TRF2). We conclude that during C. elegans embryogenesis TAF-1 and TFIID have broad roles in transcription and development and that TFIID and TLF may act together at certain promoters. Our findings imply that in metazoans TFIID may be of widespread importance for transcription and for expression of tissue-specific genes.
Collapse
Affiliation(s)
- Amy K Walker
- Section of Developmental and Stem Cell Biology, Joslin Diabetes Center, Harvard Medical School, Boston, Massachusetts 02115, USA
| | | | | |
Collapse
|
24
|
González-Mariscal L, Betanzos A, Nava P, Jaramillo BE. Tight junction proteins. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2003; 81:1-44. [PMID: 12475568 DOI: 10.1016/s0079-6107(02)00037-8] [Citation(s) in RCA: 807] [Impact Index Per Article: 38.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
A fundamental function of epithelia and endothelia is to separate different compartments within the organism and to regulate the exchange of substances between them. The tight junction (TJ) constitutes the barrier both to the passage of ions and molecules through the paracellular pathway and to the movement of proteins and lipids between the apical and the basolateral domains of the plasma membrane. In recent years more than 40 different proteins have been discovered to be located at the TJs of epithelia, endothelia and myelinated cells. This unprecedented expansion of information has changed our view of TJs from merely a paracellular barrier to a complex structure involved in signaling cascades that control cell growth and differentiation. Both cortical and transmembrane proteins integrate TJs. Among the former are scaffolding proteins containing PDZ domains, tumor suppressors, transcription factors and proteins involved in vesicle transport. To date two components of the TJ filaments have been identified: occludin and claudin. The latter is a protein family with more than 20 members. Both occludin and claudins are integral proteins capable of interacting adhesively with complementary molecules on adjacent cells and of co-polymerizing laterally. These advancements in the knowledge of the molecular structure of TJ support previous physiological models that exhibited TJ as dynamic structures that present distinct permeability and morphological characteristics in different tissues and in response to changing natural, pathological or experimental conditions.
Collapse
Affiliation(s)
- L González-Mariscal
- Department of Physiology, Biophysics and Neuroscience, Center for Research and Advanced Studies (CINVESTAV), Ave. Politécnico Nacional 2508, México DF, 07000, Mexico.
| | | | | | | |
Collapse
|
25
|
Lyczak R, Gomes JE, Bowerman B. Heads or tails: cell polarity and axis formation in the early Caenorhabditis elegans embryo. Dev Cell 2002; 3:157-66. [PMID: 12194847 DOI: 10.1016/s1534-5807(02)00226-5] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
In C. elegans, the first embryonic axis is established shortly after fertilization and requires both the microtubule and microfilament cytoskeleton. Cues from sperm-donated centrosomes result in a cascade of events that polarize the distribution of widely conserved PAR proteins at the cell cortex. The PAR proteins in turn polarize the cytoplasm and position mitotic spindles. Lessons learned from C. elegans should improve our understanding of how cells become polarized and divide asymmetrically during development.
Collapse
Affiliation(s)
- Rebecca Lyczak
- Institute of Molecular Biology, University of Oregon, 1370 Franklin Boulevard, Eugene 97403, USA
| | | | | |
Collapse
|
26
|
Abstract
The recent identification and characterization of the Caenorhabditis elegans gene spn-4 has shed new light on the mechanisms that link embryonic polarity to the specification of cell fates.
Collapse
Affiliation(s)
- Jean-Claude Labbé
- Department of Biology, CB3280, The University of North Carolina at Chapel Hill, 616 Fordham Hall, Chapel Hill, NC 27599, USA
| | | |
Collapse
|
27
|
Nikolaou S, Hartman D, Presidente PJA, Newton SE, Gasser RB. HcSTK, a Caenorhabditis elegans PAR-1 homologue from the parasitic nematode, Haemonchus contortus. Int J Parasitol 2002; 32:749-58. [PMID: 12062493 DOI: 10.1016/s0020-7519(02)00008-5] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
A putative serine/threonine protein kinase (HcSTK) from the parasitic nematode Haemonchus contortus was characterised at the mRNA and amino acid levels. HcSTK displays a high level of identity (85-93% in the catalytic domain) with proteins of the PAR-1/MARK serine/threonine protein kinase (STK) subfamily, which represent signal transduction molecules involved in establishing and maintaining polarity in proliferating and differentiating cells. The transcript of hcstk is expressed in different developmental stages (second-, third-, fourth-stage larvae and adults) and various organs (muscle, intestine and reproductive) of H. contortus. In addition, there are several isoforms which appear to relate to a single gene. The expression profile of hcstk is similar to that of Caenorhabditis elegans PAR-1, and the level of sequence identity among members of the PAR-1/MARK STK subfamily, representing a range of species of vertebrates (e.g. humans and rodents), invertebrates (e.g. insects and C. elegans) and yeast, suggests that HcSTK may be involved in a conserved signal transduction pathway.
Collapse
Affiliation(s)
- Sia Nikolaou
- Victorian Institute of Animal Science, Agriculture Victoria, 475 Mickleham Road, Attwood, Victoria 3049, Australia
| | | | | | | | | |
Collapse
|
28
|
Riechmann V, Gutierrez GJ, Filardo P, Nebreda AR, Ephrussi A. Par-1 regulates stability of the posterior determinant Oskar by phosphorylation. Nat Cell Biol 2002; 4:337-42. [PMID: 11951092 DOI: 10.1038/ncb782] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Par-1 kinase is critical for polarization of the Drosophila melanogaster oocyte and the one-cell Caenorhabditis elegans embryo. Although Par-1 localizes specifically to the posterior pole in both cells, neither its targets nor its function at the posterior pole have been elucidated. Here we show that Drosophila Par-1 phosphorylates the posterior determinant Oskar (Osk) and demonstrate genetically that Par-1 is required for accumulation of Osk protein. We show in cell-free extracts that Osk protein is intrinsically unstable and that it is stabilized after phosphorylation by Par-1. Our data indicate that posteriorly localized Par-1 regulates posterior patterning by stabilizing Osk.
Collapse
Affiliation(s)
- Veit Riechmann
- European Molecular Biology Laboratory, Meyerhofstrasse 1, Postfach 10.2209, D-69012 Heidelberg, Germany
| | | | | | | | | |
Collapse
|
29
|
Morton DG, Shakes DC, Nugent S, Dichoso D, Wang W, Golden A, Kemphues KJ. The Caenorhabditis elegans par-5 gene encodes a 14-3-3 protein required for cellular asymmetry in the early embryo. Dev Biol 2002; 241:47-58. [PMID: 11784094 DOI: 10.1006/dbio.2001.0489] [Citation(s) in RCA: 124] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The establishment of anterior-posterior polarity in the Caenorhabditis elegans embryo requires the activity of the maternally expressed par genes. We report the identification and analysis of a new par gene, par-5. We show that par-5 is required for asynchrony and asymmetry in the first embryonic cell divisions, normal pseudocleavage, normal cleavage spindle orientation at the two-cell stage, and localization of P granules and MEX-5 during the first and subsequent cell cycles. Furthermore, par-5 activity is required in the first cell cycle for the asymmetric cortical localization of PAR-1 and PAR-2 to the posterior, and PAR-3, PAR-6, and PKC-3 to the anterior. When PAR-5 is reduced by mutation or by RNA interference, these proteins spread around the cortex of the one-cell embryo and partially overlap. We have shown by sequence analysis of par-5 mutants and by RNA interference that the par-5 gene is the same as the ftt-1 gene, and encodes a 14-3-3 protein. The PAR-5 14-3-3 protein is present in gonads, oocytes, and early embryos, but is not asymmetrically distributed. Our analysis indicates that the par-5 14-3-3 gene plays a crucial role in the early events leading to polarization of the C. elegans zygote.
Collapse
Affiliation(s)
- Diane G Morton
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York 14853, USA
| | | | | | | | | | | | | |
Collapse
|
30
|
Maduro MF, Meneghini MD, Bowerman B, Broitman-Maduro G, Rothman JH. Restriction of mesendoderm to a single blastomere by the combined action of SKN-1 and a GSK-3beta homolog is mediated by MED-1 and -2 in C. elegans. Mol Cell 2001; 7:475-85. [PMID: 11463373 DOI: 10.1016/s1097-2765(01)00195-2] [Citation(s) in RCA: 152] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The endoderm and much of the mesoderm arise from the EMS cell in the four-cell C. elegans embryo. We report that the MED-1 and -2 GATA factors specify the entire fate of EMS, which otherwise produces two C-like mesectodermal progenitors. The meds are direct targets of the maternal SKN-1 transcription factor; however, their forced expression can direct SKN-1-independent reprogramming of non-EMS cells into mesendodermal progenitors. We find that SGG-1/GSK-3beta kinase acts both as a Wnt-dependent activator of endoderm in EMS and an apparently Wnt-independent repressor of the meds in the C lineage, indicating a dual role for this kinase in mesendoderm development. Our results suggest that a broad tissue territory, mesendoderm, in vertebrates has been confined to a single cell in nematodes through a common gene regulatory network.
Collapse
Affiliation(s)
- M F Maduro
- Department of Molecular, Cellular, and Developmental Biology and Neuroscience Research Institute, University of California, Santa Barbara 93106, USA
| | | | | | | | | |
Collapse
|
31
|
Shulman JM, Benton R, St Johnston D. The Drosophila homolog of C. elegans PAR-1 organizes the oocyte cytoskeleton and directs oskar mRNA localization to the posterior pole. Cell 2000; 101:377-88. [PMID: 10830165 DOI: 10.1016/s0092-8674(00)80848-x] [Citation(s) in RCA: 221] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
In C. elegans, the PAR-1 kinase is localized to the posterior of the zygote and is required for anterior-posterior axis formation. Here, we report that a Drosophila PAR-1 homolog localizes to the posterior of the oocyte with oskar mRNA. Furthermore, par-1 mutants show a novel polarity phenotype in which bicoid mRNA accumulates normally at the anterior, but oskar mRNA is redirected to the center of the oocyte, resulting in embryonic patterning defects. These phenotypes arise from a disorganization of the oocyte microtubule cytoskeleton, consistent with reports that mammalian PAR-1 homologs regulate microtubule dynamics. Thus, Drosophila PAR-1 may remodel the oocyte microtubule network to define the posterior as the site for oskar localization. These results identify a molecular parallel between anterior-posterior polarization in Drosophila and C. elegans.
Collapse
Affiliation(s)
- J M Shulman
- Wellcome/CRC Institute and Department of Genetics, University of Cambridge, United Kingdom
| | | | | |
Collapse
|
32
|
Watts JL, Morton DG, Bestman J, Kemphues KJ. The C. elegans par-4 gene encodes a putative serine-threonine kinase required for establishing embryonic asymmetry. Development 2000; 127:1467-75. [PMID: 10704392 DOI: 10.1242/dev.127.7.1467] [Citation(s) in RCA: 160] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
During the first cell cycle of Caenorhabditis elegans embryogenesis, asymmetries are established that are essential for determining the subsequent developmental fates of the daughter cells. The maternally expressed par genes are required for establishing this polarity. The products of several of the par genes have been found to be themselves asymmetrically distributed in the first cell cycle. We have identified the par-4 gene of C. elegans, and find that it encodes a putative serine-threonine kinase with similarity to a human kinase associated with Peutz-Jeghers Syndrome, LKB1 (STK11), and a Xenopus egg and embryo kinase, XEEK1. Several strong par-4 mutant alleles are missense mutations that alter conserved residues within the kinase domain, suggesting that kinase activity is essential for PAR-4 function. We find that the PAR-4 protein is present in the gonads, oocytes and early embryos of C. elegans, and is both cytoplasmically and cortically distributed. The cortical distribution begins at the late 1-cell stage, is more pronounced at the 2- and 4-cell stages and is reduced at late stages of embryonic development. We find no asymmetry in the distribution of PAR-4 protein in C. elegans embryos. The distribution of PAR-4 protein in early embryos is unaffected by mutations in the other par genes.
Collapse
Affiliation(s)
- J L Watts
- Section of Genetics and Development, Cornell University, Ithaca, New York 14853, USA
| | | | | | | |
Collapse
|
33
|
Schubert CM, Lin R, de Vries CJ, Plasterk RH, Priess JR. MEX-5 and MEX-6 function to establish soma/germline asymmetry in early C. elegans embryos. Mol Cell 2000; 5:671-82. [PMID: 10882103 DOI: 10.1016/s1097-2765(00)80246-4] [Citation(s) in RCA: 178] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
An asymmetrical network of cortically localized PAR proteins forms shortly after fertilization of the C. elegans egg. This network is required for subsequent asymmetries in the expression patterns of several proteins that are encoded by nonlocalized, maternally expressed mRNAs. We provide evidence that two nearly identical genes, mex-5 and mex-6, link PAR asymmetry to those subsequent protein asymmetries. MEX-5 is a novel, cytoplasmic protein that is localized through PAR activities to the anterior pole of the 1-cell stage embryo. MEX-5 localization is reciprocal to that of a group of posterior-localized proteins called germline proteins. Ectopic expression of MEX-5 is sufficient to inhibit the expression of germline proteins, suggesting that MEX-5 functions to inhibit anterior expression of the germline proteins.
Collapse
Affiliation(s)
- C M Schubert
- Zoology Department, University of Washington, Seattle 98109, USA
| | | | | | | | | |
Collapse
|
34
|
Nishida H, Morokuma J, Nishikata T. Maternal cytoplasmic factors for generation of unique cleavage patterns in animal embryos. Curr Top Dev Biol 1999; 46:1-37. [PMID: 10417875 DOI: 10.1016/s0070-2153(08)60324-5] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- H Nishida
- Department of Life Science, Tokyo Institute of Technology, Yokohama, Japan
| | | | | |
Collapse
|
35
|
Poustka AJ, Herwig R, Krause A, Hennig S, Meier-Ewert S, Lehrach H. Toward the gene catalogue of sea urchin development: the construction and analysis of an unfertilized egg cDNA library highly normalized by oligonucleotide fingerprinting. Genomics 1999; 59:122-33. [PMID: 10409423 DOI: 10.1006/geno.1999.5852] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We describe the use of oligonucleotide fingerprinting for the generation of a normalized cDNA library from unfertilized sea urchin eggs and report the preliminary analysis of this library, which resulted in the establishment of a partial gene catalogue of the sea urchin egg. In an analysis of 21,925 cDNA clones by hybridization with 217 oligonucleotide probes, we were able to identify 6291 clusters corresponding to different transcripts, ranging in size from 1 to 265 clones. This corresponds to an average 3.5-fold normalization of the starting library. The normalized library represents about one-third of all genes expressed in the sea urchin egg. To generate sequence information for the transcripts represented by the clusters, representative clones selected from 711 clusters were sequenced. The construction and preliminary analysis of the normalized library are the first steps in the assembly of an increasingly complete collection of maternal genes expressed in the sea urchin egg, which will provide a number of insights into the early development of this well-characterized model organism.
Collapse
Affiliation(s)
- A J Poustka
- Max-Planck-Institut für Molekulare Genetik, Ihnestrasse 73, Berlin, 14195, Germany.
| | | | | | | | | | | |
Collapse
|
36
|
Abstract
Studies of about 20 maternally expressed genes are providing an understanding of mechanisms of patterning and cell-fate determination in the early Caenorhabditis elegans embryo. The analyses have revealed that fates of the early blastomeres are specified by a combination of intrinsically asymmetric cell divisions and two types of cell-cell interactions: inductions and polarizing interactions. In this review we summarize the current level of understanding of the molecular mechanisms underlying these processes in the specification of cell fates in the pregastrulation embryo.
Collapse
Affiliation(s)
- L S Rose
- Section of Molecular and Cellular Biology, University of California, Davis 95616, USA.
| | | |
Collapse
|
37
|
Hung TJ, Kemphues KJ. PAR-6 is a conserved PDZ domain-containing protein that colocalizes with PAR-3 in Caenorhabditis elegans embryos. Development 1999; 126:127-35. [PMID: 9834192 DOI: 10.1242/dev.126.1.127] [Citation(s) in RCA: 209] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The par genes are required to establish polarity in the Caenorhabditis elegans embryo. Mutations in two of these genes, par-3 and par-6, exhibit similar phenotypes. A third gene, pkc-3, gives a similar phenotype when the protein is depleted by RNA interference. PAR-3 and PKC-3 protein are colocalized to the anterior periphery of asymmetrically dividing cells of the germline lineage and the peripheral localizations of both proteins depends upon the activity of par-6. Here we report the molecular cloning of par-6 and the immunolocalization of PAR-6 protein. We found that par-6 encodes a PDZ-domain-containing protein and has homologues in mammals and flies. Moreover, we discovered that PAR-6 colocalizes with PAR-3 and that par-3 and pkc-3 activity are required for the peripheral localization of PAR-6. The localization of both PAR-3 and PAR-6 proteins is affected identically by mutations in the par-2, par-4 and par-5 genes. The co-dependence of PAR-3, PAR-6 and PKC-3 for peripheral localization and the overlap in their distributions lead us to propose that they act in a protein complex.
Collapse
Affiliation(s)
- T J Hung
- Section of Genetics and Development, Cornell University, Ithaca, NY 14853, USA
| | | |
Collapse
|
38
|
Hunter CP. Caenorhabditis elegans: Embryonic Axis Formation; Signalling in Early Development. Development 1999. [DOI: 10.1007/978-3-642-59828-9_15] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
|
39
|
|
40
|
Izumi Y, Hirose T, Tamai Y, Hirai S, Nagashima Y, Fujimoto T, Tabuse Y, Kemphues KJ, Ohno S. An atypical PKC directly associates and colocalizes at the epithelial tight junction with ASIP, a mammalian homologue of Caenorhabditis elegans polarity protein PAR-3. J Cell Biol 1998; 143:95-106. [PMID: 9763423 PMCID: PMC2132825 DOI: 10.1083/jcb.143.1.95] [Citation(s) in RCA: 408] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Cell polarity is fundamental to differentiation and function of most cells. Studies in mammalian epithelial cells have revealed that the establishment and maintenance of cell polarity depends upon cell adhesion, signaling networks, the cytoskeleton, and protein transport. Atypical protein kinase C (PKC) isotypes PKCzeta and PKClambda have been implicated in signaling through lipid metabolites including phosphatidylinositol 3-phosphates, but their physiological role remains elusive. In the present study we report the identification of a protein, ASIP (atypical PKC isotype-specific interacting protein), that binds to aPKCs, and show that it colocalizes with PKClambda to the cell junctional complex in cultured epithelial MDCKII cells and rat intestinal epithelia. In addition, immunoelectron microscopy revealed that ASIP localizes to tight junctions in intestinal epithelial cells. Furthermore, ASIP shows significant sequence similarity to Caenorhabditis elegans PAR-3. PAR-3 protein is localized to the anterior periphery of the one-cell embryo, and is required for the establishment of cell polarity in early embryos. ASIP and PAR-3 share three PDZ domains, and can both bind to aPKCs. Taken together, our results suggest a role for a protein complex containing ASIP and aPKC in the establishment and/or maintenance of epithelial cell polarity. The evolutionary conservation of the protein complex and its asymmetric distribution in polarized cells from worm embryo to mammalian-differentiated cells may mean that the complex functions generally in the organization of cellular asymmetry.
Collapse
Affiliation(s)
- Y Izumi
- Department of Molecular Biology, Yokohama City University School of Medicine, Yokohama 236-0004, Japan
| | | | | | | | | | | | | | | | | |
Collapse
|
41
|
Tabuse Y, Izumi Y, Piano F, Kemphues KJ, Miwa J, Ohno S. Atypical protein kinase C cooperates with PAR-3 to establish embryonic polarity in Caenorhabditis elegans. Development 1998; 125:3607-14. [PMID: 9716526 DOI: 10.1242/dev.125.18.3607] [Citation(s) in RCA: 269] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Asymmetric cell divisions, critically important to specify cell types in the development of multicellular organisms, require polarized distribution of cytoplasmic components and the proper alignment of the mitotic apparatus. In Caenorhabditis elegans, the maternally expressed protein, PAR-3, is localized to one pole of asymmetrically dividing blastomeres and is required for these asymmetric divisions. In this paper, we report that an atypical protein kinase C (PKC-3) is essential for proper asymmetric cell divisions and co-localizes with PAR-3. Embryos depleted of PKC-3 by RNA interference die showing Par-like phenotypes including defects in early asymmetric divisions and mislocalized germline-specific granules (P granules). The defective phenotypes of PKC-3-depleted embryos are similar to those exhibited by mutants for par-3 and another par gene, par-6. Direct interaction of PKC-3 with PAR-3 is shown by in vitro binding analysis. This result is reinforced by the observation that PKC-3 and PAR-3 co-localize in vivo. Furthermore, PKC-3 and PAR-3 show mutual dependence on each other and on three of the other par genes for their localization. We conclude that PKC-3 plays an indispensable role in establishing embryonic polarity through interaction with PAR-3.
Collapse
Affiliation(s)
- Y Tabuse
- Fundamental Research Laboratories, NEC Corporation, Tsukuba, Ibaraki 305, Japan.
| | | | | | | | | | | |
Collapse
|
42
|
Tenenhaus C, Schubert C, Seydoux G. Genetic requirements for PIE-1 localization and inhibition of gene expression in the embryonic germ lineage of Caenorhabditis elegans. Dev Biol 1998; 200:212-24. [PMID: 9705228 DOI: 10.1006/dbio.1998.8940] [Citation(s) in RCA: 91] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In early Caenorhabditis elegans embryos, production of new mRNAs is inhibited in the germ lineage. This inhibition requires the germline factor PIE-1, and correlates with the absence in germline blastomeres of a phosphoepitope on RNA polymerase II (RNAPII-H5). We show that PIE-1 is uniformly distributed in oocytes and newly fertilized eggs, and becomes localized asymmetrically in the late one-cell stage. To begin to dissect the mechanisms required for PIE-1 localization and inhibition of RNAPII-H5 expression, we have examined the distribution of PIE-1 and RNAPII-H5 in maternal-effect mutants that disrupt embryonic development. We find that mutants that disrupt the asymmetric divisions of germline blastomeres mislocalize PIE-1, and activate RNAPII-H5 expression in the germ lineage. In contrast, mutants that alter somatic cell identities do not affect PIE-1 localization or RNAPII-H5 expression. Our observations suggest that PIE-1 represses mRNA transcription in each germline blastomere in a concentration-dependent manner. We also show that in wild-type, and in mutants where PIE-1 is mislocalized, the cellular and subcellular distribution of PIE-1 remarkably parallels that of the P granules, suggesting that the localizations of these two germline components are coordinately regulated.
Collapse
Affiliation(s)
- C Tenenhaus
- School of Medicine, Johns Hopkins University, Baltimore, Maryland, 21205-2185, USA
| | | | | |
Collapse
|
43
|
Abstract
Insights into the mechanisms of asymmetric cell division have recently been obtained from studies in genetically amenable systems such as Drosophila and Caenorhabditis elegans. These studies have emphasized the importance of cortically localized polarity organizing molecules, adapter molecules, and the actin cytoskeleton in controlling unequal segregation of cell-fate determinants and spindle orientation. The control of asymmetric cell divisions by Wnt signaling in C. elegans and Frizzled signaling in Drosophila reveals additional mechanisms for modulating cellular polarity and suggests that there are some similarities between the two systems.
Collapse
Affiliation(s)
- B Lu
- Howard Hughes Medical Institute, Department of Physiology, University of California, San Francisco 94143-0725, USA
| | | | | |
Collapse
|
44
|
Abstract
Genetic screens for recessive, maternal-effect, embryonic-lethal mutations have identified about 25 genes that control early steps of pattern formation in the nematode Caenorhabditis elegans. These maternal genes are discussed as belonging to one of three groups. The par group genes establish and maintain polarity in the one-cell zygote in response to sperm entry, defining an anterior/posterior body axis at least in part through interactions with the cyto-skeleton mediated by cortically localized proteins. Blastomere identity group genes act down-stream of the par group to specify the identities of individual embryonic cells, or blastomeres, using both cell autonomous and non-cell autonomous mechanisms. Requirements for the blastomere identity genes are consistent with previous studies suggesting that early asymmetric cleavages in the C. elegans embryo generate six "founder" cells that account for much of the C. elegans body plan. Intermediate group genes, most recently identified, may link the establishment of polarity in the zygote by par group genes to the localization of blastomere identity group gene functions. This review summarizes the known requirements for the members of each group, although it seems clear that additional regulatory genes controlling pattern formation in the early embryo have yet to be identified. An emerging challenge is to link the function of the genes in these three groups into interacting pathways that can account for the specification of the six founder cell identities in the early embryo, five of which produce somatic cell types and one of which produces the germline.
Collapse
Affiliation(s)
- B Bowerman
- Institute of Molecular Biology, University of Oregon, Eugene 97403, USA
| |
Collapse
|