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Lin S, Yu X, Yan H, Xu Y, Ma K, Wang X, Liu Y, Xie A, Yu Z. E2F7 serves as a potential prognostic biomarker for lung adenocarcinoma. Medicine (Baltimore) 2024; 103:e34342. [PMID: 38241554 PMCID: PMC10798722 DOI: 10.1097/md.0000000000034342] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Accepted: 06/23/2023] [Indexed: 01/21/2024] Open
Abstract
E2F transcription factors (E2Fs) are a family of transcription factors critical regulators of the cell cycle, apoptosis, and differentiation, thus influencing tumorigenesis. However, the specific roles of E2Fs in lung adenocarcinoma (LUAD) remain unclear. Data from The Cancer Genome Atlas (TCGA) were used. R version. 4.0.3 and multiple databases (TIMER, cBioportal, gene expression profile interaction analysis [GEPIA], LinkedOmics, and CancerSEA) were utilized to investigate mRNA expression, mutational analysis, prognosis, clinical correlations, co-expressed gene, pathway and network, and single-cell analyses. Immunohistochemistry (IHC) confirmed that E2F transcription factor 7 (E2F7) correlated with LUAD. Among the E2Fs, E2F7 was identified by constructing a prognostic model most significantly associated with overall survival (OS) in LUAD patients. The univariate and multivariate Cox regression analyses showed that E2F7, p-T stage, and p-TNM stage were closely related to OS and progression-free survival (PFS) (P < .05) in LUAD. E2F 7/8 were also identified as significantly associated with tumor stage in the GEPIA database. Compared with paracancerous tissues, E2F7 was up-regulated in LUAD by IHC, and E2F7 might be positively correlated with larger tumors and higher TNM stages. E2F7 may primarily regulate DNA repair, damage, and cell cycle processes and thus affect LUAD tumorigenesis, invasion, and metastasis by LinkedOmics and CancerSEA. E2F7 serves as a potential prognostic biomarker for LUAD.
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Affiliation(s)
- Shengcheng Lin
- Department of Thoracic Surgery, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital and Shenzhen Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Shenzhen, China
| | - Xiangyang Yu
- Department of Thoracic Surgery, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital and Shenzhen Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Shenzhen, China
| | - Haojie Yan
- Translational Medicine Collaborative Innovation Center, Shenzhen People’s Hospital (The Second Clinical Medical College, Jinan University; The First Affifiliated Hospital, Southern University of Science and Technology), Shenzhen, China
- Basic Medicine Postdoctoral Research Station, Jinan University, Guangzhou, China
| | - Yafei Xu
- Department of Anesthesiology, Shunde Hospital of Southern Medical University (The First People’s Hospital of Shunde Foshan), Foshan, China
| | - Kai Ma
- Department of Thoracic Surgery, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital and Shenzhen Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Shenzhen, China
| | - Xiaoliang Wang
- Department of Pathology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital and Shenzhen Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Shenzhen, China
| | - Yeqing Liu
- Department of Thoracic Surgery, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital and Shenzhen Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Shenzhen, China
| | - Ahuan Xie
- Department of Pathology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital and Shenzhen Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Shenzhen, China
| | - Zhentao Yu
- Department of Thoracic Surgery, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital and Shenzhen Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Shenzhen, China
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SenGupta T, Lefol Y, Lirussi L, Suaste V, Luders T, Gupta S, Aman Y, Sharma K, Fang EF, Nilsen H. Krill oil protects dopaminergic neurons from age-related degeneration through temporal transcriptome rewiring and suppression of several hallmarks of aging. Aging (Albany NY) 2022; 14:8661-8687. [DOI: 10.18632/aging.204375] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Accepted: 10/27/2022] [Indexed: 11/10/2022]
Affiliation(s)
- Tanima SenGupta
- Institute of Clinical Medicine, Department of Clinical Molecular Biology, University of Oslo, Oslo N-0318, Norway
- Section of Clinical Molecular Biology, Akershus University Hospital, Nordbyhagen N-1474, Norway
- Department of Biosciences, University of Oslo, Oslo N-0318, Norway
| | - Yohan Lefol
- Institute of Clinical Medicine, Department of Clinical Molecular Biology, University of Oslo, Oslo N-0318, Norway
| | - Lisa Lirussi
- Section of Clinical Molecular Biology, Akershus University Hospital, Nordbyhagen N-1474, Norway
| | - Veronica Suaste
- Department of Microbiology, Oslo University Hospital, Oslo N-0424, Norway
- Department of Biosciences, University of Oslo, Oslo N-0318, Norway
| | - Torben Luders
- Institute of Clinical Medicine, Department of Clinical Molecular Biology, University of Oslo, Oslo N-0318, Norway
| | - Swapnil Gupta
- Section of Clinical Molecular Biology, Akershus University Hospital, Nordbyhagen N-1474, Norway
| | - Yahyah Aman
- Institute of Clinical Medicine, Department of Clinical Molecular Biology, University of Oslo, Oslo N-0318, Norway
- Section of Clinical Molecular Biology, Akershus University Hospital, Nordbyhagen N-1474, Norway
| | - Kulbhushan Sharma
- Section of Clinical Molecular Biology, Akershus University Hospital, Nordbyhagen N-1474, Norway
| | - Evandro Fei Fang
- Institute of Clinical Medicine, Department of Clinical Molecular Biology, University of Oslo, Oslo N-0318, Norway
- Section of Clinical Molecular Biology, Akershus University Hospital, Nordbyhagen N-1474, Norway
| | - Hilde Nilsen
- Institute of Clinical Medicine, Department of Clinical Molecular Biology, University of Oslo, Oslo N-0318, Norway
- Section of Clinical Molecular Biology, Akershus University Hospital, Nordbyhagen N-1474, Norway
- Department of Microbiology, Oslo University Hospital, Oslo N-0424, Norway
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Jin X, Liu J, Wang S, Shi J, Zhao C, Xie H, Kang Y. E2f4 is required for intestinal and otolith development in zebrafish. J Cell Physiol 2022; 237:2690-2702. [DOI: 10.1002/jcp.30734] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 03/06/2022] [Accepted: 03/11/2022] [Indexed: 11/06/2022]
Affiliation(s)
- Xiaolin Jin
- Institute of Evolution & Marine Biodiversity Ocean University of China Qingdao China
| | - Junjun Liu
- Institute of Evolution & Marine Biodiversity Ocean University of China Qingdao China
| | - Shuo Wang
- Institute of Evolution & Marine Biodiversity Ocean University of China Qingdao China
| | - Jiale Shi
- Institute of Evolution & Marine Biodiversity Ocean University of China Qingdao China
| | - Chengtian Zhao
- Institute of Evolution & Marine Biodiversity Ocean University of China Qingdao China
- Sars‐Fang Centre, Ministry of Education Key Laboratory of Marine Genetics and Breeding, College of Marine Life Sciences Ocean University of China Qingdao China
| | - Haibo Xie
- Institute of Evolution & Marine Biodiversity Ocean University of China Qingdao China
- Sars‐Fang Centre, Ministry of Education Key Laboratory of Marine Genetics and Breeding, College of Marine Life Sciences Ocean University of China Qingdao China
| | - Yunsi Kang
- Institute of Evolution & Marine Biodiversity Ocean University of China Qingdao China
- Sars‐Fang Centre, Ministry of Education Key Laboratory of Marine Genetics and Breeding, College of Marine Life Sciences Ocean University of China Qingdao China
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Reevaluation of the role of LIP-1 as an ERK/MPK-1 dual specificity phosphatase in the C. elegans germline. Proc Natl Acad Sci U S A 2022; 119:2113649119. [PMID: 35022236 PMCID: PMC8784128 DOI: 10.1073/pnas.2113649119] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/23/2021] [Indexed: 11/18/2022] Open
Abstract
The RAS–ERK pathway is critical for metazoan development. In development, ERK activity is regulated by a balance of phosphorylation of ERK by MEK (MAPK kinase) and dephosphorylation by DUSPs (dual specificity phosphatases). LIP-1, a DUSP6/7 family member, was previously suggested to regulate MPK-1/ERK activity by dephosphorylating MPK-1 in the Caenorhabditis elegans germline, based on LIP-1's mutant phenotype in the germline and its DUSP role in vulval development. However, our investigations demonstrate that LIP-1 does not function as an MPK-1 DUSP in the germline and likely regulates germline functions through distinct targets. Our results present a cautionary note about misinterpreting similar mutant phenotypes caused by mutations in different genes and assuming that genes function similarly in different tissues. The fidelity of a signaling pathway depends on its tight regulation in space and time. Extracellular signal-regulated kinase (ERK) controls wide-ranging cellular processes to promote organismal development and tissue homeostasis. ERK activation depends on a reversible dual phosphorylation on the TEY motif in its active site by ERK kinase (MEK) and dephosphorylation by DUSPs (dual specificity phosphatases). LIP-1, a DUSP6/7 homolog, was proposed to function as an ERK (MPK-1) DUSP in the Caenorhabditis elegans germline primarily because of its phenotype, which morphologically mimics that of a RAS/let-60 gain-of-function mutant (i.e., small oocyte phenotype). Our investigations, however, reveal that loss of lip-1 does not lead to an increase in MPK-1 activity in vivo. Instead, we show that loss of lip-1 leads to 1) a decrease in MPK-1 phosphorylation, 2) lower MPK-1 substrate phosphorylation, 3) phenocopy of mpk-1 reduction-of-function (rather than gain-of-function) allele, and 4) a failure to rescue mpk-1–dependent germline or fertility defects. Moreover, using diverse genetic mutants, we show that the small oocyte phenotype does not correlate with increased ectopic MPK-1 activity and that ectopic increase in MPK-1 phosphorylation does not necessarily result in a small oocyte phenotype. Together, these data demonstrate that LIP-1 does not function as an MPK-1 DUSP in the C. elegans germline. Our results caution against overinterpretation of the mechanistic underpinnings of orthologous phenotypes, since they may be a result of independent mechanisms, and provide a framework for characterizing the distinct molecular targets through which LIP-1 may mediate its several germline functions.
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Gal C, Carelli FN, Appert A, Cerrato C, Huang N, Dong Y, Murphy J, Frapporti A, Ahringer J. DREAM represses distinct targets by cooperating with different THAP domain proteins. Cell Rep 2021; 37:109835. [PMID: 34686342 PMCID: PMC8552245 DOI: 10.1016/j.celrep.2021.109835] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Revised: 06/03/2021] [Accepted: 09/24/2021] [Indexed: 01/09/2023] Open
Abstract
The DREAM (dimerization partner [DP], retinoblastoma [Rb]-like, E2F, and MuvB) complex controls cellular quiescence by repressing cell-cycle and other genes, but its mechanism of action is unclear. Here, we demonstrate that two C. elegans THAP domain proteins, LIN-15B and LIN-36, co-localize with DREAM and function by different mechanisms for repression of distinct sets of targets. LIN-36 represses classical cell-cycle targets by promoting DREAM binding and gene body enrichment of H2A.Z, and we find that DREAM subunit EFL-1/E2F is specific for LIN-36 targets. In contrast, LIN-15B represses germline-specific targets in the soma by facilitating H3K9me2 promoter marking. We further find that LIN-36 and LIN-15B differently regulate DREAM binding. In humans, THAP proteins have been implicated in cell-cycle regulation by poorly understood mechanisms. We propose that THAP domain proteins are key mediators of Rb/DREAM function.
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Affiliation(s)
- Csenge Gal
- Wellcome Trust/Cancer Research UK Gurdon Institute and Department of Genetics, University of Cambridge, Cambridge, UK
| | - Francesco Nicola Carelli
- Wellcome Trust/Cancer Research UK Gurdon Institute and Department of Genetics, University of Cambridge, Cambridge, UK
| | - Alex Appert
- Wellcome Trust/Cancer Research UK Gurdon Institute and Department of Genetics, University of Cambridge, Cambridge, UK
| | - Chiara Cerrato
- Wellcome Trust/Cancer Research UK Gurdon Institute and Department of Genetics, University of Cambridge, Cambridge, UK
| | - Ni Huang
- Wellcome Trust/Cancer Research UK Gurdon Institute and Department of Genetics, University of Cambridge, Cambridge, UK
| | - Yan Dong
- Wellcome Trust/Cancer Research UK Gurdon Institute and Department of Genetics, University of Cambridge, Cambridge, UK
| | - Jane Murphy
- Wellcome Trust/Cancer Research UK Gurdon Institute and Department of Genetics, University of Cambridge, Cambridge, UK
| | - Andrea Frapporti
- Wellcome Trust/Cancer Research UK Gurdon Institute and Department of Genetics, University of Cambridge, Cambridge, UK
| | - Julie Ahringer
- Wellcome Trust/Cancer Research UK Gurdon Institute and Department of Genetics, University of Cambridge, Cambridge, UK.
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MiR-35 buffers apoptosis thresholds in the C. elegans germline by antagonizing both MAPK and core apoptosis pathways. Cell Death Differ 2019; 26:2637-2651. [PMID: 30952991 PMCID: PMC7224216 DOI: 10.1038/s41418-019-0325-6] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2018] [Revised: 03/18/2019] [Accepted: 03/22/2019] [Indexed: 02/06/2023] Open
Abstract
Apoptosis is a genetically programmed cell death process with profound roles in development and disease. MicroRNAs modulate the expression of many proteins and are often deregulated in human diseases, such as cancer. C. elegans germ cells undergo apoptosis in response to genotoxic stress by the combined activities of the core apoptosis and MAPK pathways, but how their signalling thresholds are buffered is an open question. Here we show mir-35–42 miRNA family play a dual role in antagonizing both NDK-1, a positive regulator of MAPK signalling, and the BH3-only pro-apoptotic protein EGL-1 to regulate the magnitude of DNA damage-induced apoptosis in the C. elegans germline. We show that while miR-35 represses EGL-1 by promoting transcript degradation, repression of NDK-1 may be through sequestration of the transcript to inhibit translation. Importantly, dramatic increase in NDK-1 expression was observed in cells about to die. In the absence of miR-35, increased NDK-1 activity enhanced MAPK signalling that lead to significant increases in germ cell death. Our findings demonstrate that NDK-1 acts upstream of (or in parallel to) EGL-1, and that miR-35 targets both egl-1 and ndk-1 to fine-tune cell killing in response to genotoxic stress.
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Raiders SA, Eastwood MD, Bacher M, Priess JR. Binucleate germ cells in Caenorhabditis elegans are removed by physiological apoptosis. PLoS Genet 2018; 14:e1007417. [PMID: 30024879 PMCID: PMC6053125 DOI: 10.1371/journal.pgen.1007417] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2018] [Accepted: 05/15/2018] [Indexed: 12/27/2022] Open
Abstract
Cell death plays a major role during C. elegans oogenesis, where over half of the oogenic germ cells die in a process termed physiological apoptosis. How germ cells are selected for physiological apoptosis, or instead become oocytes, is not understood. Most oocytes produce viable embryos when apoptosis is blocked, suggesting that physiological apoptosis does not function to cull defective germ cells. Instead, cells targeted for apoptosis may function as nurse cells; the germline is syncytial, and all germ cells appear to contribute cytoplasm to developing oocytes. C. elegans has been a leading model for the genetics and molecular biology of apoptosis and phagocytosis, but comparatively few studies have examined the cell biology of apoptotic cells. We used live imaging to identify and examine pre-apoptotic germ cells in the adult gonad. After initiating apoptosis, germ cells selectively export their mitochondria into the shared pool of syncytial cytoplasm; this transport appears to use the microtubule motor kinesin. The apoptotic cells then shrink as they expel most of their remaining cytoplasm, and close off from the syncytium. Shortly thereafter the apoptotic cells restructure their microtubule and actin cytoskeletons, possibly to maintain cell integrity; the microtubules form a novel, cortical array of stabilized microtubules, and actin and cofilin organize into giant cofilin-actin rods. We discovered that some apoptotic germ cells are binucleate; the binucleate germ cells can develop into binucleate oocytes in apoptosis-defective strains, and appear capable of producing triploid offspring. Our results suggest that the nuclear layer of the germline syncytium becomes folded during mitosis and growth, and that binucleate cells arise as the layer unfolds or everts; all of the binucleate cells are subsequently removed by apoptosis. These results show that physiological apoptosis targets at least two distinct populations of germ cells, and that the apoptosis machinery efficiently recognizes cells with two nuclei. Many germ cells die by apoptosis during the development of animal oocytes, including more than half of all germ cells in the model system C. elegans. How individual germ cells are selected for apoptosis, or survival, is not known. Here we study the cell biology of apoptosis. The C. elegans gonad is a syncytium, with nearly 1000 germ “cells” connected to a shared, core cytoplasm. Once apoptosis is initiated, germ cells selectively transport their mitochondria into the gonad core, apparently using the microtubule motor protein kinesin. The apoptotic cells next constrict, expelling most of their remaining cytoplasm into the core, and close off from the gonad core. The microtubule and actin cytoskeletons are remodeled and stabilized, presumably to maintain the integrity of the dying cell. The apoptotic cells form giant cofilin-actin rods, similar to rods described in stressed cultured cells and in human myopathies and neuropathies such as Alzheimer’s and Huntington’s disease. We show that some germ cells are binucleate; these cells appear to form during germline morphogenesis, and are removed by apoptosis. These results demonstrate heterogeneity between oogenic germ cells, and show that the apoptosis machinery efficiently recognizes and removes cells with two nuclei.
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Affiliation(s)
- Stephan A. Raiders
- Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America
| | - Michael D. Eastwood
- Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America
| | - Meghan Bacher
- Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America
| | - James R. Priess
- Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America
- Molecular and Cellular Biology Program, University of Washington, Seattle, Washington, United States of America
- Department of Biology, University of Washington, Seattle, Washington, United States of America
- * E-mail:
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8
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Abstract
The E2F family of transcription factors is a key determinant of cell proliferation in response to extra- and intra-cellular signals. Within this family, E2F4 is a transcriptional repressor whose activity is critical to engage and maintain cell cycle arrest in G0/G1 in conjunction with members of the retinoblastoma (RB) family. However, recent observations challenge this paradigm and indicate that E2F4 has a multitude of functions in cells besides this cell cycle regulatory role, including in embryonic and adult stem cells, during regenerative processes, and in cancer. Some of these new functions are independent of the RB family and involve direct activation of target genes. Here we review the canonical functions of E2F4 and discuss recent evidence expanding the role of this transcription factor, with a focus on cell fate decisions in tissue homeostasis and regeneration.
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Affiliation(s)
- Jenny Hsu
- a Departments of Pediatrics and Genetics , Stanford University , Stanford , CA , USA
| | - Julien Sage
- a Departments of Pediatrics and Genetics , Stanford University , Stanford , CA , USA
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Li J, Chauve L, Phelps G, Brielmann RM, Morimoto RI. E2F coregulates an essential HSF developmental program that is distinct from the heat-shock response. Genes Dev 2016; 30:2062-2075. [PMID: 27688402 PMCID: PMC5066613 DOI: 10.1101/gad.283317.116] [Citation(s) in RCA: 74] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2016] [Accepted: 09/06/2016] [Indexed: 01/08/2023]
Abstract
Heat-shock factor (HSF) is the master transcriptional regulator of the heat-shock response (HSR) and is essential for stress resilience. HSF is also required for metazoan development; however, its function and regulation in this process are poorly understood. Here, we characterize the genomic distribution and transcriptional activity of Caenorhabditis elegans HSF-1 during larval development and show that the developmental HSF-1 transcriptional program is distinct from the HSR. HSF-1 developmental activation requires binding of E2F/DP to a GC-rich motif that facilitates HSF-1 binding to a heat-shock element (HSE) that is degenerate from the consensus HSE sequence and adjacent to the E2F-binding site at promoters. In contrast, induction of the HSR is independent of these promoter elements or E2F/DP and instead requires a distinct set of tandem canonical HSEs. Together, E2F and HSF-1 directly regulate a gene network, including a specific subset of chaperones, to promote protein biogenesis and anabolic metabolism, which are essential in development.
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Affiliation(s)
- Jian Li
- Department of Molecular Biosciences, Rice Institute for Biomedical Research, Northwestern University, Evanston, Illinois 60208, USA
| | - Laetitia Chauve
- Department of Molecular Biosciences, Rice Institute for Biomedical Research, Northwestern University, Evanston, Illinois 60208, USA
| | - Grace Phelps
- Department of Molecular Biosciences, Rice Institute for Biomedical Research, Northwestern University, Evanston, Illinois 60208, USA
| | - Renée M Brielmann
- Department of Molecular Biosciences, Rice Institute for Biomedical Research, Northwestern University, Evanston, Illinois 60208, USA
| | - Richard I Morimoto
- Department of Molecular Biosciences, Rice Institute for Biomedical Research, Northwestern University, Evanston, Illinois 60208, USA
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The E2F-DP1 Transcription Factor Complex Regulates Centriole Duplication in Caenorhabditis elegans. G3-GENES GENOMES GENETICS 2016; 6:709-20. [PMID: 26772748 PMCID: PMC4777132 DOI: 10.1534/g3.115.025577] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Centrioles play critical roles in the organization of microtubule-based structures, from the mitotic spindle to cilia and flagella. In order to properly execute their various functions, centrioles are subjected to stringent copy number control. Central to this control mechanism is a precise duplication event that takes place during S phase of the cell cycle and involves the assembly of a single daughter centriole in association with each mother centriole . Recent studies have revealed that posttranslational control of the master regulator Plk4/ZYG-1 kinase and its downstream effector SAS-6 is key to ensuring production of a single daughter centriole. In contrast, relatively little is known about how centriole duplication is regulated at a transcriptional level. Here we show that the transcription factor complex EFL-1-DPL-1 both positively and negatively controls centriole duplication in the Caenorhabditis elegans embryo. Specifically, we find that down regulation of EFL-1-DPL-1 can restore centriole duplication in a zyg-1 hypomorphic mutant and that suppression of the zyg-1 mutant phenotype is accompanied by an increase in SAS-6 protein levels. Further, we find evidence that EFL-1-DPL-1 promotes the transcription of zyg-1 and other centriole duplication genes. Our results provide evidence that in a single tissue type, EFL-1-DPL-1 sets the balance between positive and negative regulators of centriole assembly and thus may be part of a homeostatic mechanism that governs centriole assembly.
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Park JY, Hughes LJ, Moon UY, Park R, Kim SB, Tran K, Lee JS, Cho SH, Kim S. The apical complex protein Pals1 is required to maintain cerebellar progenitor cells in a proliferative state. Development 2015; 143:133-46. [PMID: 26657772 DOI: 10.1242/dev.124180] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2015] [Accepted: 11/25/2015] [Indexed: 12/28/2022]
Abstract
Through their biased localization and function within the cell, polarity complex proteins are necessary to establish the cellular asymmetry required for tissue organization. Well-characterized germinal zones, mitogenic signals and cell types make the cerebellum an excellent model for addressing the crucial function of polarity complex proteins in the generation and organization of neural tissues. Deletion of the apical polarity complex protein Pals1 in the developing cerebellum results in a remarkably undersized cerebellum with disrupted layers in poorly formed folia and strikingly reduced granule cell production. We demonstrate that Pals1 is not only essential for cerebellum organogenesis, but also for preventing premature differentiation and thus maintaining progenitor pools in cerebellar germinal zones, including cerebellar granule neuron precursors in the external granule layer. In the Pals1 mouse mutants, the expression of genes that regulate the cell cycle was diminished, correlating with the loss of the proliferating cell population of germinal zones. Furthermore, enhanced Shh signaling through activated Smo cannot overcome impaired cerebellar cell generation, arguing for an epistatic role of Pals1 in proliferation capacity. Our study identifies Pals1 as a novel intrinsic factor that regulates the generation of cerebellar cells and Pals1 deficiency as a potential inhibitor of overactive mitogenic signaling.
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Affiliation(s)
- Jun Young Park
- Shriners Hospitals Pediatric Research Center, Department of Anatomy and Cell Biology, Temple University School of Medicine, Philadelphia, PA 19140, USA
| | - Lucinda J Hughes
- Shriners Hospitals Pediatric Research Center, Department of Anatomy and Cell Biology, Temple University School of Medicine, Philadelphia, PA 19140, USA Graduate Program of Biomedical Sciences, Temple University School of Medicine, Philadelphia, PA 19140, USA
| | - Uk Yeol Moon
- Shriners Hospitals Pediatric Research Center, Department of Anatomy and Cell Biology, Temple University School of Medicine, Philadelphia, PA 19140, USA
| | - Raehee Park
- Shriners Hospitals Pediatric Research Center, Department of Anatomy and Cell Biology, Temple University School of Medicine, Philadelphia, PA 19140, USA
| | - Sang-Bae Kim
- Department of Systems Biology, University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Khoi Tran
- Shriners Hospitals Pediatric Research Center, Department of Anatomy and Cell Biology, Temple University School of Medicine, Philadelphia, PA 19140, USA
| | - Ju-Seog Lee
- Department of Systems Biology, University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Seo-Hee Cho
- Shriners Hospitals Pediatric Research Center, Department of Anatomy and Cell Biology, Temple University School of Medicine, Philadelphia, PA 19140, USA
| | - Seonhee Kim
- Shriners Hospitals Pediatric Research Center, Department of Anatomy and Cell Biology, Temple University School of Medicine, Philadelphia, PA 19140, USA
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Eberhard R, Stergiou L, Hofmann ER, Hofmann J, Haenni S, Teo Y, Furger A, Hengartner MO. Ribosome synthesis and MAPK activity modulate ionizing radiation-induced germ cell apoptosis in Caenorhabditis elegans. PLoS Genet 2013; 9:e1003943. [PMID: 24278030 PMCID: PMC3836707 DOI: 10.1371/journal.pgen.1003943] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2013] [Accepted: 09/25/2013] [Indexed: 01/08/2023] Open
Abstract
Synthesis of ribosomal RNA by RNA polymerase I (RNA pol I) is an elemental biological process and is key for cellular homeostasis. In a forward genetic screen in C. elegans designed to identify DNA damage-response factors, we isolated a point mutation of RNA pol I, rpoa-2(op259), that leads to altered rRNA synthesis and a concomitant resistance to ionizing radiation (IR)-induced germ cell apoptosis. This weak apoptotic IR response could be phenocopied when interfering with other factors of ribosome synthesis. Surprisingly, despite their resistance to DNA damage, rpoa-2(op259) mutants present a normal CEP-1/p53 response to IR and increased basal CEP-1 activity under normal growth conditions. In parallel, rpoa-2(op259) leads to reduced Ras/MAPK pathway activity, which is required for germ cell progression and physiological germ cell death. Ras/MAPK gain-of-function conditions could rescue the IR response defect in rpoa-2(op259), pointing to a function for Ras/MAPK in modulating DNA damage-induced apoptosis downstream of CEP-1. Our data demonstrate that a single point mutation in an RNA pol I subunit can interfere with multiple key signalling pathways. Ribosome synthesis and growth-factor signalling are perturbed in many cancer cells; such an interplay between basic cellular processes and signalling might be critical for how tumours evolve or respond to treatment.
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Affiliation(s)
- Ralf Eberhard
- Institute of Molecular Life Sciences, University of Zurich, Zurich, Switzerland
- MLS Graduate School and MD/PhD program, Zurich, Switzerland
| | - Lilli Stergiou
- Institute of Molecular Life Sciences, University of Zurich, Zurich, Switzerland
| | - E. Randal Hofmann
- Institute of Molecular Life Sciences, University of Zurich, Zurich, Switzerland
| | - Jen Hofmann
- Institute of Molecular Life Sciences, University of Zurich, Zurich, Switzerland
| | - Simon Haenni
- MLS Graduate School and MD/PhD program, Zurich, Switzerland
| | - Youjin Teo
- Institute of Molecular Life Sciences, University of Zurich, Zurich, Switzerland
| | - André Furger
- Department of Biochemistry, University of Oxford, Oxford, United Kingdom
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Oberstaller J, Joseph SJ, Kissinger JC. Genome-wide upstream motif analysis of Cryptosporidium parvum genes clustered by expression profile. BMC Genomics 2013; 14:516. [PMID: 23895416 PMCID: PMC3734150 DOI: 10.1186/1471-2164-14-516] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2013] [Accepted: 07/09/2013] [Indexed: 11/16/2022] Open
Abstract
Background There are very few molecular genetic tools available to study the apicomplexan parasite Cryptosporidium parvum. The organism is not amenable to continuous in vitro cultivation or transfection, and purification of intracellular developmental stages in sufficient numbers for most downstream molecular applications is difficult and expensive since animal hosts are required. As such, very little is known about gene regulation in C. parvum. Results We have clustered whole-genome gene expression profiles generated from a previous study of seven post-infection time points of 3,281 genes to identify genes that show similar expression patterns throughout the first 72 hours of in vitro epithelial cell culture. We used the algorithms MEME, AlignACE and FIRE to identify conserved, overrepresented DNA motifs in the upstream promoter region of genes with similar expression profiles. The most overrepresented motifs were E2F (5′-TGGCGCCA-3′); G-box (5′-G.GGGG-3′); a well-documented ApiAP2 binding motif (5′-TGCAT-3′), and an unknown motif (5′-[A/C] AACTA-3′). We generated a recombinant C. parvum DNA-binding protein domain from a putative ApiAP2 transcription factor [CryptoDB: cgd8_810] and determined its binding specificity using protein-binding microarrays. We demonstrate that cgd8_810 can putatively bind the overrepresented G-box motif, implicating this ApiAP2 in the regulation of many gene clusters. Conclusion Several DNA motifs were identified in the upstream sequences of gene clusters that might serve as potential cis-regulatory elements. These motifs, in concert with protein DNA binding site data, establish for the first time the beginnings of a global C. parvum gene regulatory map that will contribute to our understanding of the development of this zoonotic parasite.
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Affiliation(s)
- Jenna Oberstaller
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA 30602, USA
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14
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Abstract
Receptor Tyrosine Kinase (RTK)-Ras-Extracellular signal-regulated kinase (ERK) signaling pathways control many aspects of C. elegans development and behavior. Studies in C. elegans helped elucidate the basic framework of the RTK-Ras-ERK pathway and continue to provide insights into its complex regulation, its biological roles, how it elicits cell-type appropriate responses, and how it interacts with other signaling pathways to do so. C. elegans studies have also revealed biological contexts in which alternative RTK- or Ras-dependent pathways are used instead of the canonical pathway.
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Affiliation(s)
- Meera V Sundaram
- Dept. of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104-6145, USA.
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15
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Tissue-specific direct targets of Caenorhabditis elegans Rb/E2F dictate distinct somatic and germline programs. Genome Biol 2013; 14:R5. [PMID: 23347407 PMCID: PMC4053757 DOI: 10.1186/gb-2013-14-1-r5] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2012] [Accepted: 01/23/2013] [Indexed: 01/12/2023] Open
Abstract
Background The tumor suppressor Rb/E2F regulates gene expression to control differentiation in multiple tissues during development, although how it directs tissue-specific gene regulation in vivo is poorly understood. Results We determined the genome-wide binding profiles for Caenorhabditis elegans Rb/E2F-like components in the germline, in the intestine and broadly throughout the soma, and uncovered highly tissue-specific binding patterns and target genes. Chromatin association by LIN-35, the C. elegans ortholog of Rb, is impaired in the germline but robust in the soma, a characteristic that might govern differential effects on gene expression in the two cell types. In the intestine, LIN-35 and the heterochromatin protein HPL-2, the ortholog of Hp1, coordinately bind at many sites lacking E2F. Finally, selected direct target genes contribute to the soma-to-germline transformation of lin-35 mutants, including mes-4, a soma-specific target that promotes H3K36 methylation, and csr-1, a germline-specific target that functions in a 22G small RNA pathway. Conclusions In sum, identification of tissue-specific binding profiles and effector target genes reveals important insights into the mechanisms by which Rb/E2F controls distinct cell fates in vivo.
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Control of oocyte growth and meiotic maturation in Caenorhabditis elegans. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2013; 757:277-320. [PMID: 22872481 DOI: 10.1007/978-1-4614-4015-4_10] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
In sexually reproducing animals, oocytes arrest at diplotene or diakinesis and resume meiosis (meiotic maturation) in response to hormones. Chromosome segregation errors in female meiosis I are the leading cause of human birth defects, and age-related changes in the hormonal environment of the ovary are a suggested cause. Caenorhabditis elegans is emerging as a genetic paradigm for studying hormonal control of meiotic maturation. The meiotic maturation processes in C. elegans and mammals share a number of biological and molecular similarities. Major sperm protein (MSP) and luteinizing hormone (LH), though unrelated in sequence, both trigger meiotic resumption using somatic Gα(s)-adenylate cyclase pathways and soma-germline gap-junctional communication. At a molecular level, the oocyte responses apparently involve the control of conserved protein kinase pathways and post-transcriptional gene regulation in the oocyte. At a cellular level, the responses include cortical cytoskeletal rearrangement, nuclear envelope breakdown, assembly of the acentriolar meiotic spindle, chromosome segregation, and likely changes important for fertilization and the oocyte-to-embryo transition. This chapter focuses on signaling mechanisms required for oocyte growth and meiotic maturation in C. elegans and discusses how these mechanisms coordinate the completion of meiosis and the oocyte-to-embryo transition.
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17
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Abstract
The Caenorhabditis elegans pRb ortholog, LIN-35, functions in a wide range of cellular and developmental processes. This includes a role of LIN-35 in nutrient utilization by the intestine, which it carries out redundantly with SLR-2, a zinc-finger protein. This and other redundant functions of LIN-35 were identified in genetic screens for mutations that display synthetic phenotypes in conjunction with loss of lin-35. To explore the intestinal role of LIN-35, we conducted a genome-wide RNA-interference-feeding screen for suppressors of lin-35; slr-2 early larval arrest. Of the 26 suppressors identified, 17 fall into three functional classes: (1) ribosome biogenesis genes, (2) mitochondrial prohibitins, and (3) chromatin regulators. Further characterization indicates that different categories of suppressors act through distinct molecular mechanisms. We also tested lin-35; slr-2 suppressors, as well as suppressors of the synthetic multivulval phenotype, to determine the spectrum of lin-35-synthetic phenotypes that could be suppressed following inhibition of these genes. We identified 19 genes, most of which are evolutionarily conserved, that can suppress multiple unrelated lin-35-synthetic phenotypes. Our study reveals a network of genes broadly antagonistic to LIN-35 as well as genes specific to the role of LIN-35 in intestinal and vulval development. Suppressors of multiple lin-35 phenotypes may be candidate targets for anticancer therapies. Moreover, screening for suppressors of phenotypically distinct synthetic interactions, which share a common altered gene, may prove to be a novel and effective approach for identifying genes whose activities are most directly relevant to the core functions of the shared gene.
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C. elegans germ cells show temperature and age-dependent expression of Cer1, a Gypsy/Ty3-related retrotransposon. PLoS Pathog 2012; 8:e1002591. [PMID: 22479180 PMCID: PMC3315495 DOI: 10.1371/journal.ppat.1002591] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2011] [Accepted: 01/30/2012] [Indexed: 11/19/2022] Open
Abstract
Virus-like particles (VLPs) have not been observed in Caenorhabditis germ cells, although nematode genomes contain low numbers of retrotransposon and retroviral sequences. We used electron microscopy to search for VLPs in various wild strains of Caenorhabditis, and observed very rare candidate VLPs in some strains, including the standard laboratory strain of C. elegans, N2. We identified the N2 VLPs as capsids produced by Cer1, a retrotransposon in the Gypsy/Ty3 family of retroviruses/retrotransposons. Cer1 expression is age and temperature dependent, with abundant expression at 15°C and no detectable expression at 25°C, explaining how VLPs escaped detection in previous studies. Similar age and temperature-dependent expression of Cer1 retrotransposons was observed for several other wild strains, indicating that these properties are common, if not integral, features of this retroelement. Retrotransposons, in contrast to DNA transposons, have a cytoplasmic stage in replication, and those that infect non-dividing cells must pass their genomic material through nuclear pores. In most C. elegans germ cells, nuclear pores are largely covered by germline-specific organelles called P granules. Our results suggest that Cer1 capsids target meiotic germ cells exiting pachytene, when free nuclear pores are added to the nuclear envelope and existing P granules begin to be removed. In pachytene germ cells, Cer1 capsids concentrate away from nuclei on a subset of microtubules that are exceptionally resistant to microtubule inhibitors; the capsids can aggregate these stable microtubules in older adults, which exhibit a temperature-dependent decrease in egg viability. When germ cells exit pachytene, the stable microtubules disappear and capsids redistribute close to nuclei that have P granule-free nuclear pores. This redistribution is microtubule dependent, suggesting that capsids that are released from stable microtubules transfer onto new, dynamic microtubules to track toward nuclei. These studies introduce C. elegans as a model to study the interplay between retroelements and germ cell biology. Retrotransposons and retroviruses pose enormous threats to animal and plants because of their ability to insert into host genes. Retroelements that replicate in germ cells can, if left unchecked, expand exponentially in the host genome. C. elegans has proven to be an exceptional model system for studying many facets of cell and molecular biology, and the genome contains both retrotransposon and retroviral sequences. However, no virus-like particles have been observed in C. elegans germ cells. We show here that Cer1, an endogenous Gypsy/Ty3 class retrotransposon, is expressed at very high levels in C. elegans germ cells, but escaped detection in previous studies because its expression is both temperature and age dependent. These studies reveal new aspects of microtubule regulation in C. elegans that the retroelement appears to exploit to navigate the germ cell cytoplasm, and demonstrate the power of C. elegans for studying host/pathogen interactions in germ cell biology.
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Su LH, Pan YJ, Huang YC, Cho CC, Chen CW, Huang SW, Chuang SF, Sun CH. A novel E2F-like protein involved in transcriptional activation of cyst wall protein genes in Giardia lamblia. J Biol Chem 2011; 286:34101-20. [PMID: 21835923 PMCID: PMC3190776 DOI: 10.1074/jbc.m111.280206] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2011] [Revised: 08/09/2011] [Indexed: 01/01/2023] Open
Abstract
Giardia lamblia differentiates into resistant walled cysts for survival outside the host and transmission. During encystation, synthesis of cyst wall proteins is coordinately induced. The E2F family of transcription factors in higher eukaryotes is involved in cell cycle progression and cell differentiation. We asked whether Giardia has E2F-like genes and whether they influence gene expression during Giardia encystation. Blast searches of the Giardia genome database identified one gene (e2f1) encoding a putative E2F protein with two putative DNA-binding domains. We found that the e2f1 gene expression levels increased significantly during encystation. Epitope-tagged E2F1 was found to localize to nuclei. Recombinant E2F1 specifically bound to the thymidine kinase and cwp1-3 gene promoters. E2F1 contains several key residues for DNA binding, and mutation analysis revealed that its binding sequence is similar to those of the known E2F family proteins. The E2F1-binding sequences were positive cis-acting elements of the thymidine kinase and cwp1 promoters. We also found that E2F1 transactivated the thymidine kinase and cwp1 promoters through its binding sequences in vivo. Interestingly, E2F1 overexpression resulted in a significant increase of the levels of CWP1 protein, cwp1-3 gene mRNA, and cyst formation. We also found E2F1 can interact with Myb2, a transcription factor that coordinate up-regulates the cwp1-3 genes during encystation. Our results suggest that E2F family has been conserved during evolution and that E2F1 is an important transcription factor in regulation of the Giardia cwp genes, which are key to Giardia differentiation into cysts.
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Affiliation(s)
- Li-Hsin Su
- From the Department of Parasitology, College of Medicine, National Taiwan University, Taipei 100, Taiwan
| | - Yu-Jiao Pan
- From the Department of Parasitology, College of Medicine, National Taiwan University, Taipei 100, Taiwan
| | - Yu-Chang Huang
- From the Department of Parasitology, College of Medicine, National Taiwan University, Taipei 100, Taiwan
| | - Chao-Cheng Cho
- From the Department of Parasitology, College of Medicine, National Taiwan University, Taipei 100, Taiwan
| | - Chia-Wei Chen
- From the Department of Parasitology, College of Medicine, National Taiwan University, Taipei 100, Taiwan
| | - Shao-Wei Huang
- From the Department of Parasitology, College of Medicine, National Taiwan University, Taipei 100, Taiwan
| | - Sheng-Fung Chuang
- From the Department of Parasitology, College of Medicine, National Taiwan University, Taipei 100, Taiwan
| | - Chin-Hung Sun
- From the Department of Parasitology, College of Medicine, National Taiwan University, Taipei 100, Taiwan
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20
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Rutkowski R, Dickinson R, Stewart G, Craig A, Schimpl M, Keyse SM, Gartner A. Regulation of Caenorhabditis elegans p53/CEP-1-dependent germ cell apoptosis by Ras/MAPK signaling. PLoS Genet 2011; 7:e1002238. [PMID: 21901106 PMCID: PMC3161941 DOI: 10.1371/journal.pgen.1002238] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2011] [Accepted: 06/28/2011] [Indexed: 11/18/2022] Open
Abstract
Maintaining genome stability in the germline is thought to be an evolutionarily ancient role of the p53 family. The sole Caenorhabditis elegans p53 family member CEP-1 is required for apoptosis induction in meiotic, late-stage pachytene germ cells in response to DNA damage and meiotic recombination failure. In an unbiased genetic screen for negative regulators of CEP-1, we found that increased activation of the C. elegans ERK orthologue MPK-1, resulting from either loss of the lip-1 phosphatase or activation of let-60 Ras, results in enhanced cep-1-dependent DNA damage induced apoptosis. We further show that MPK-1 is required for DNA damage-induced germ cell apoptosis. We provide evidence that MPK-1 signaling regulates the apoptotic competency of germ cells by restricting CEP-1 protein expression to cells in late pachytene. Restricting CEP-1 expression to cells in late pachytene is thought to ensure that apoptosis doesn't occur in earlier-stage cells where meiotic recombination occurs. MPK-1 signaling regulates CEP-1 expression in part by regulating the levels of GLD-1, a translational repressor of CEP-1, but also via a GLD-1-independent mechanism. In addition, we show that MPK-1 is phosphorylated and activated upon ionising radiation (IR) in late pachytene germ cells and that MPK-1-dependent CEP-1 activation may be in part direct, as these two proteins interact in a yeast two-hybrid assay. In summary, we report our novel finding that MAP kinase signaling controls CEP-1-dependent apoptosis by several different pathways that converge on CEP-1. Since apoptosis is also restricted to pachytene stage cells in mammalian germlines, analogous mechanisms regulating p53 family members are likely to be conserved throughout evolution.
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Affiliation(s)
- Rachael Rutkowski
- Wellcome Trust Centre for Gene Regulation and Expression, College of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Robin Dickinson
- Cancer Research UK Stress Response Laboratory, Medical Research Institute, Ninewells Hospital and Medical School, Dundee, United Kingdom
| | - Graeme Stewart
- Cancer Research UK Stress Response Laboratory, Medical Research Institute, Ninewells Hospital and Medical School, Dundee, United Kingdom
| | - Ashley Craig
- Wellcome Trust Centre for Gene Regulation and Expression, College of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Marianne Schimpl
- Wellcome Trust Centre for Gene Regulation and Expression, College of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Stephen M. Keyse
- Cancer Research UK Stress Response Laboratory, Medical Research Institute, Ninewells Hospital and Medical School, Dundee, United Kingdom
| | - Anton Gartner
- Wellcome Trust Centre for Gene Regulation and Expression, College of Life Sciences, University of Dundee, Dundee, United Kingdom
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21
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mir-35 is involved in intestine cell G1/S transition and germ cell proliferation in C. elegans. Cell Res 2011; 21:1605-18. [PMID: 21691303 DOI: 10.1038/cr.2011.102] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
MicroRNA (miRNA) regulates gene expression in many cellular events, yet functions of only a few miRNAs are known in C. elegans. We analyzed the function of mir-35-41 unique to the worm, and show here that mir-35 regulates the G1/S transition of intestinal cells and germ cell proliferation. Loss of mir-35 leads to a decrease of nuclei numbers in intestine and distal mitotic gonad, while re-introduction of mir-35 rescues the mutant phenotypes. Genetic analysis indicates that mir-35 may act through Rb/E2F and SCF pathways. Further bioinformatic and functional analyses demonstrate that mir-35 targets evolutionally conserved lin-23 and gld-1. Together, our study reveals a novel function of mir-35 family in cell division regulation.
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22
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Tabuchi TM, Deplancke B, Osato N, Zhu LJ, Barrasa MI, Harrison MM, Horvitz HR, Walhout AJM, Hagstrom KA. Chromosome-biased binding and gene regulation by the Caenorhabditis elegans DRM complex. PLoS Genet 2011; 7:e1002074. [PMID: 21589891 PMCID: PMC3093354 DOI: 10.1371/journal.pgen.1002074] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2010] [Accepted: 03/25/2011] [Indexed: 01/28/2023] Open
Abstract
DRM is a conserved transcription factor complex that includes E2F/DP and pRB family proteins and plays important roles in development and cancer. Here we describe new aspects of DRM binding and function revealed through genome-wide analyses of the Caenorhabditis elegans DRM subunit LIN-54. We show that LIN-54 DNA-binding activity recruits DRM to promoters enriched for adjacent putative E2F/DP and LIN-54 binding sites, suggesting that these two DNA-binding moieties together direct DRM to its target genes. Chromatin immunoprecipitation and gene expression profiling reveals conserved roles for DRM in regulating genes involved in cell division, development, and reproduction. We find that LIN-54 promotes expression of reproduction genes in the germline, but prevents ectopic activation of germline-specific genes in embryonic soma. Strikingly, C. elegans DRM does not act uniformly throughout the genome: the DRM recruitment motif, DRM binding, and DRM-regulated embryonic genes are all under-represented on the X chromosome. However, germline genes down-regulated in lin-54 mutants are over-represented on the X chromosome. We discuss models for how loss of autosome-bound DRM may enhance germline X chromosome silencing. We propose that autosome-enriched binding of DRM arose in C. elegans as a consequence of germline X chromosome silencing and the evolutionary redistribution of germline-expressed and essential target genes to autosomes. Sex chromosome gene regulation may thus have profound evolutionary effects on genome organization and transcriptional regulatory networks.
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Affiliation(s)
- Tomoko M. Tabuchi
- Program in Molecular Medicine and Program in Cell Dynamics, University of
Massachusetts Medical School, Worcester, Massachusetts, United States of
America
| | - Bart Deplancke
- Program in Gene Function and Expression and Program in Molecular
Medicine, University of Massachusetts Medical School, Worcester, Massachusetts,
United States of America
| | - Naoki Osato
- Program in Gene Function and Expression and Program in Molecular
Medicine, University of Massachusetts Medical School, Worcester, Massachusetts,
United States of America
| | - Lihua J. Zhu
- Program in Gene Function and Expression and Program in Molecular
Medicine, University of Massachusetts Medical School, Worcester, Massachusetts,
United States of America
| | - M. Inmaculada Barrasa
- Program in Gene Function and Expression and Program in Molecular
Medicine, University of Massachusetts Medical School, Worcester, Massachusetts,
United States of America
| | - Melissa M. Harrison
- Howard Hughes Medical Institute, Department of Biology, Massachusetts
Institute of Technology, Cambridge, Massachusetts, United States of
America
| | - H. Robert Horvitz
- Howard Hughes Medical Institute, Department of Biology, Massachusetts
Institute of Technology, Cambridge, Massachusetts, United States of
America
| | - Albertha J. M. Walhout
- Program in Gene Function and Expression and Program in Molecular
Medicine, University of Massachusetts Medical School, Worcester, Massachusetts,
United States of America
| | - Kirsten A. Hagstrom
- Program in Molecular Medicine and Program in Cell Dynamics, University of
Massachusetts Medical School, Worcester, Massachusetts, United States of
America
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23
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Abstract
The RB1 gene is the first tumor suppressor gene identified whose mutational inactivation is the cause of a human cancer, the pediatric cancer retinoblastoma. The 25 years of research since its discovery has not only illuminated a general role for RB1 in human cancer, but also its critical importance in normal development. Understanding the molecular function of the RB1 encoded protein, pRb, is a long-standing goal that promises to inform our understanding of cancer, its relationship to normal development, and possible therapeutic strategies to combat this disease. Achieving this goal has been difficult, complicated by the complexity of pRb and related proteins. The goal of this review is to explore the hypothesis that, at its core, the molecular function of pRb is to dynamically regulate the location-specific assembly or disassembly of protein complexes on the DNA in response to the output of various signaling pathways. These protein complexes participate in a variety of molecular processes relevant to DNA including gene transcription, DNA replication, DNA repair, and mitosis. Through regulation of these processes, RB1 plays a uniquely prominent role in normal development and cancer.
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Affiliation(s)
- Meenalakshmi Chinnam
- Department of Pharmacology and Therapeutics, Roswell Park Cancer Institute, Buffalo, New York, USA
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24
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Mos in the oocyte: how to use MAPK independently of growth factors and transcription to control meiotic divisions. JOURNAL OF SIGNAL TRANSDUCTION 2010; 2011:350412. [PMID: 21637374 PMCID: PMC3101788 DOI: 10.1155/2011/350412] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/31/2010] [Accepted: 11/01/2010] [Indexed: 01/12/2023]
Abstract
In many cell types, the mitogen-activated protein kinase (MAPK) also named extracellular signal-regulated kinase (ERK) is activated in response to a variety of extracellular growth factor-receptor interactions and leads to the transcriptional activation of immediate early genes, hereby influencing a number of tissue-specific biological activities, as cell proliferation, survival and differentiation. In one specific cell type however, the female germ cell, MAPK does not follow this canonical scheme. In oocytes, MAPK is activated independently of growth factors and tyrosine kinase receptors, acts independently of transcriptional regulation, plays a crucial role in controlling meiotic divisions, and is under the control of a peculiar upstream regulator, the kinase Mos. Mos was originally identified as the transforming gene of Moloney murine sarcoma virus and its cellular homologue was the first proto-oncogene to be molecularly cloned. What could be the specific roles of Mos that render it necessary for meiosis? Which unique functions could explain the evolutionary cost to have selected one gene to only serve for few hours in one very specific cell type? This review discusses the original features of MAPK activation by Mos and the roles of this module in oocytes.
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25
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Clary LM, Okkema PG. The EGR family gene egrh-1 functions non-autonomously in the control of oocyte meiotic maturation and ovulation in C. elegans. Development 2010; 137:3129-37. [PMID: 20736289 PMCID: PMC2926961 DOI: 10.1242/dev.041616] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Oocyte production, maturation and ovulation must be coordinated with sperm availability for successful fertilization. In C. elegans this coordination involves signals from the sperm to the oocyte and somatic gonad, which stimulate maturation and ovulation. We have found that the C. elegans early growth response factor family member EGRH-1 inhibits oocyte maturation and ovulation until sperm are available. In the absence of sperm, egrh-1 mutants exhibit derepressed oocyte maturation marked by MAPK activation and ovulation. egrh-1 mutants exhibit ectopic oocyte differentiation in the distal gonadal arm and accumulate abnormal and degraded oocytes proximally. These defects result in reduced brood size and partially penetrant embryonic lethality. We have found that endogenous EGRH-1 protein and an egrh-1::gfp reporter gene are expressed in the sheath and distal tip cells of the somatic gonad, the gut and other non-gonadal tissues, as well as in sperm, but expression is not observed in oocytes. Results of tissue-specific egrh-1(RNAi) experiments and genetic mosaic analyses revealed that EGRH-1 function is necessary in the soma and, surprisingly, this function is required in both the gut and the somatic gonad. Based on transformation rescue experiments we hypothesize that EGRH-1 in the somatic gonad inhibits oocyte maturation and ovulation.
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Affiliation(s)
- Lynn M Clary
- Laboratory for Molecular Biology, Department of Biological Sciences, University of Illinois at Chicago, IL 60607, USA
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26
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Heger P, Kroiher M, Ndifon N, Schierenberg E. Conservation of MAP kinase activity and MSP genes in parthenogenetic nematodes. BMC DEVELOPMENTAL BIOLOGY 2010; 10:51. [PMID: 20478028 PMCID: PMC2893452 DOI: 10.1186/1471-213x-10-51] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/14/2009] [Accepted: 05/17/2010] [Indexed: 11/10/2022]
Abstract
Background MAP (mitogen-activated protein) kinase activation is a prerequisite for oocyte maturation, ovulation and fertilisation in many animals. In the hermaphroditic nematode Caenorhabditis elegans, an MSP (major sperm protein) dependent pathway is utilised for MAP kinase activation and successive oocyte maturation with extracellular MSP released from sperm acting as activator. How oocyte-to-embryo transition is triggered in parthenogenetic nematode species that lack sperm, is not known. Results We investigated two key elements of oocyte-to-embryo transition, MSP expression and MAP kinase signaling, in two parthenogenetic nematodes and their close hermaphroditic relatives. While activated MAP kinase is present in all analysed nematodes irrespective of the reproductive mode, MSP expression differs. In contrast to hermaphroditic or bisexual species, we do not find MSP expression at the protein level in parthenogenetic nematodes. However, genomic sequence analysis indicates that functional MSP genes are present in several parthenogenetic species. Conclusions We present three alternative interpretations to explain our findings. (1) MSP has lost its function as a trigger of MAP kinase activation and is not expressed in parthenogenetic nematodes. Activation of the MAP kinase pathway is achieved by another, unknown mechanism. Functional MSP genes are required for occasionally emerging males found in some parthenogenetic species. (2) Because of long-term disadvantages, parthenogenesis is of recent origin. MSP genes remained intact during this short intervall although they are useless. As in the first scenario, an unknown mechanism is responsible for MAP kinase activation. (3) The molecular machinery regulating oocyte-to-embryo transition in parthenogenetic nematodes is conserved with respect to C. elegans, thus requiring intact MSP genes. However, MSP expression has been shifted to non-sperm cells and is reduced below the detection limits, but is still sufficient to trigger MAP kinase activation and embryogenesis.
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Affiliation(s)
- Peter Heger
- Zoological Institute, University of Cologne, Köln, Germany.
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27
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Abstract
Although now dogma, the idea that nonvertebrate organisms such as yeast, worms, and flies could inform, and in some cases even revolutionize, our understanding of oncogenesis in humans was not immediately obvious. Aided by the conservative nature of evolution and the persistence of a cohort of devoted researchers, the role of model organisms as a key tool in solving the cancer problem has, however, become widely accepted. In this review, we focus on the nematode Caenorhabditis elegans and its diverse and sometimes surprising contributions to our understanding of the tumorigenic process. Specifically, we discuss findings in the worm that address a well-defined set of processes known to be deregulated in cancer cells including cell cycle progression, growth factor signaling, terminal differentiation, apoptosis, the maintenance of genome stability, and developmental mechanisms relevant to invasion and metastasis.
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Affiliation(s)
- Natalia V. Kirienko
- University of Wyoming, College of Agriculture, Department of Molecular Biology, Dept 3944, 1000 E. University Avenue, Laramie, WY 82071
| | - Kumaran Mani
- University of Wyoming, College of Agriculture, Department of Molecular Biology, Dept 3944, 1000 E. University Avenue, Laramie, WY 82071
| | - David S. Fay
- University of Wyoming, College of Agriculture, Department of Molecular Biology, Dept 3944, 1000 E. University Avenue, Laramie, WY 82071
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28
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Yang Y, Han SM, Miller MA. MSP hormonal control of the oocyte MAP kinase cascade and reactive oxygen species signaling. Dev Biol 2010; 342:96-107. [PMID: 20380830 DOI: 10.1016/j.ydbio.2010.03.026] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2009] [Revised: 03/12/2010] [Accepted: 03/31/2010] [Indexed: 11/28/2022]
Abstract
The MSP domain is a conserved immunoglobulin-like structure that is important for C. elegans reproduction and human motor neuron survival. C. elegans MSPs are the most abundant proteins in sperm, where they function as intracellular cytoskeletal proteins and secreted hormones. Secreted MSPs bind to multiple receptors on oocyte and ovarian sheath cell surfaces to induce oocyte maturation and sheath contraction. MSP binding stimulates oocyte MPK-1 ERK MAP Kinase (MAPK) phosphorylation, but the function and mechanism are not well understood. Here we show that the Shp class protein-tyrosine phosphatase PTP-2 acts in oocytes downstream of sheath/oocyte gap junctions to promote MSP-induced MPK-1 phosphorylation. PTP-2 functions in the oocyte cytoplasm, not at the cell surface to inhibit multiple RasGAPs, resulting in sustained Ras activation. We also provide evidence that MSP promotes production of reactive oxygen species (ROS), which act as second messengers to augment MPK-1 phosphorylation. The Cu/Zn superoxide dismutase SOD-1, an enzyme that catalyzes ROS breakdown in the cytoplasm, inhibits MPK-1 phosphorylation downstream of or in parallel to ptp-2. Our results support the model that MSP triggers PTP-2/Ras activation and ROS production to stimulate MPK-1 activity essential for oocyte maturation. We propose that secreted MSP domains and Cu/Zn superoxide dismutases function antagonistically to control ROS and MAPK signaling.
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Affiliation(s)
- Youfeng Yang
- Department of Cell Biology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
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29
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MAP kinase signaling antagonizes PAR-1 function during polarization of the early Caenorhabditis elegans embryo. Genetics 2009; 183:965-77. [PMID: 19720857 DOI: 10.1534/genetics.109.106716] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
PAR proteins (partitioning defective) are major regulators of cell polarity and asymmetric cell division. One of the par genes, par-1, encodes a Ser/Thr kinase that is conserved from yeast to mammals. In Caenorhabditis elegans, par-1 governs asymmetric cell division by ensuring the polar distribution of cell fate determinants. However the precise mechanisms by which PAR-1 regulates asymmetric cell division in C. elegans remain to be elucidated. We performed a genomewide RNAi screen and identified six genes that specifically suppress the embryonic lethal phenotype associated with mutations in par-1. One of these suppressors is mpk-1, the C. elegans homolog of the conserved mitogen activated protein (MAP) kinase ERK. Loss of function of mpk-1 restored embryonic viability, asynchronous cell divisions, the asymmetric distribution of cell fate specification markers, and the distribution of PAR-1 protein in par-1 mutant embryos, indicating that this genetic interaction is functionally relevant for embryonic development. Furthermore, disrupting the function of other components of the MAPK signaling pathway resulted in suppression of par-1 embryonic lethality. Our data therefore indicates that MAP kinase signaling antagonizes PAR-1 signaling during early C. elegans embryonic polarization.
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30
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Wu Z, Zheng S, Yu Q. The E2F family and the role of E2F1 in apoptosis. Int J Biochem Cell Biol 2009; 41:2389-97. [PMID: 19539777 DOI: 10.1016/j.biocel.2009.06.004] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2009] [Revised: 06/02/2009] [Accepted: 06/08/2009] [Indexed: 12/22/2022]
Abstract
The E2F family of transcription factors plays a pivotal role in the regulation of cellular proliferation and differentiation. Although the deregulation of E2Fs is considered an oncogenic event that predisposes immortalized cells to transformation, paradoxically, E2F1 is also equipped with an ability to induce apoptosis under certain cellular contexts. It has become evident that E2Fs, in particular E2F1, participate in many aspects of the apoptotic process, either by acting alone or in cooperation with other factors, such as p53, to protect organisms from tumor development in the face of oncogenic lesions. Given the frequent inactivation of p53 in human cancers, the E2F1-induced apoptosis pathway is rapidly gaining attention as a key mechanism to compensate the loss of p53 in human tumors. In this review, we will focus on the recent progress in our understanding of E2F1-mediated apoptosis and discuss how these discoveries can be translated into potential therapeutic intervention.
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Affiliation(s)
- Zhenlong Wu
- Cancer Biology and Pharmacology, Genome Institute of Singapore, A*Star (Agency for Science, Technology and Research), Biopolis 02-01, Singapore 138672, Singapore
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31
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Lammens T, Li J, Leone G, De Veylder L. Atypical E2Fs: new players in the E2F transcription factor family. Trends Cell Biol 2009; 19:111-8. [PMID: 19201609 DOI: 10.1016/j.tcb.2009.01.002] [Citation(s) in RCA: 168] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2008] [Revised: 12/15/2008] [Accepted: 01/06/2009] [Indexed: 10/21/2022]
Abstract
As major regulators of the cell cycle, apoptosis and differentiation, E2F transcription factors have been studied extensively in a broad range of organisms. The recent identification of atypical E2F family members further expands our structural, functional and molecular view of the cellular E2F activity. Unlike other family members, atypical E2Fs have a duplicated DNA-binding domain and control gene expression without heterodimerization with dimerization partner proteins. Recently, knockout strategies in plants and mammals have pinpointed that atypical E2Fs have a crucial role in plant cell size control, endocycle regulation, proliferation and apoptotic response upon DNA stress. Their position at the crossroads of proliferation and DNA stress response marks these novel E2F proteins as interesting study objects in the field of tumor biology.
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Affiliation(s)
- Tim Lammens
- Department of Plant Systems Biology, Flanders Institute for Biotechnology (VIB), 9052 Gent, Belgium
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32
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Chi W, Reinke V. DPL-1 (DP) acts in the germ line to coordinate ovulation and fertilization in C. elegans. Mech Dev 2009; 126:406-16. [PMID: 19368797 DOI: 10.1016/j.mod.2009.01.008] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2008] [Revised: 01/27/2009] [Accepted: 01/27/2009] [Indexed: 11/26/2022]
Abstract
Proper coordination of oogenesis, ovulation, and fertilization is essential for successful reproduction. In Caenorhabditis elegans, a strong loss-of-function mutation in dpl-1, which encodes a subunit of the E2F heterodimeric transcription factor EFL-1/DPL-1, causes severe defects during ovulation and fertilization. Here we demonstrate that the somatic gonad structure and sheath cell contraction rate appear normal in dpl-1 mutants, but that dilation of the spermatheca valve does not occur properly, causing oocytes to become trapped in the proximal gonad arm and enter endomitosis. This ovulation defect can be partially suppressed by increasing the activity of ITR-1, an inositol triphosphate receptor in the spermatheca that promotes dilation in response to IP(3) signaling. Tissue-specific rescue experiments demonstrate that expression of DPL-1 in germ cells but not the spermatheca can restore both ovulation and fertilization in dpl-1 mutants, indicating that the absence of DPL-1 likely disrupts a pro-ovulation signal originating in the oocyte that in turn stimulates the spermatheca. Moreover, we found that expression of a single EFL-1/DPL-1-responsive gene, rme-2, in the germ line of dpl-1 mutants significantly rescues ovulation, but not fertilization. Instead, other EFL-1/DPL-1-responsive genes function to promote successful fertilization. We propose that DPL-1 acts with EFL-1 in developing oocytes to directly regulate a transcriptional program that couples the critical events of ovulation and fertilization.
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Affiliation(s)
- Woo Chi
- Department of Genetics, Yale University School of Medicine, New Haven, CT 06510, USA
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33
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Capra EJ, Skrovanek SM, Kruglyak L. Comparative developmental expression profiling of two C. elegans isolates. PLoS One 2008; 3:e4055. [PMID: 19116648 PMCID: PMC2605249 DOI: 10.1371/journal.pone.0004055] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2008] [Accepted: 12/01/2008] [Indexed: 02/01/2023] Open
Abstract
Gene expression is known to change during development and to vary among genetically diverse strains. Previous studies of temporal patterns of gene expression during C. elegans development were incomplete, and little is known about how these patterns change as a function of genetic background. We used microarrays that comprehensively cover known and predicted worm genes to compare the landscape of genetic variation over developmental time between two isolates of C. elegans. We show that most genes vary in expression during development from egg to young adult, many genes vary in expression between the two isolates, and a subset of these genes exhibit isolate-specific changes during some developmental stages. This subset is strongly enriched for genes with roles in innate immunity. We identify several novel motifs that appear to play a role in regulating gene expression during development, and we propose functional annotations for many previously unannotated genes. These results improve our understanding of gene expression and function during worm development and lay the foundation for linkage studies of the genetic basis of developmental variation in gene expression in this important model organism.
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Affiliation(s)
- Emily J. Capra
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, New Jersey, United States of America
- Department of Molecular Biology, Princeton University, Princeton, New Jersey, United States of America
| | - Sonja M. Skrovanek
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, New Jersey, United States of America
- Howard Hughes Medical Institute, Princeton University, Princeton, New Jersey, United States of America
| | - Leonid Kruglyak
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, New Jersey, United States of America
- Howard Hughes Medical Institute, Princeton University, Princeton, New Jersey, United States of America
- Department of Ecology and Evolutionary Biology, Princeton University, Princeton, New Jersey, United States of America
- * E-mail:
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Abstract
Proteins that are related to the retinoblastoma tumour suppressor pRB and the E2F transcription factor are conserved in many species of plants and animals. The mammalian orthologues of pRB and E2F are best known for their roles in cell proliferation, but it has become clear that they affect many biological processes. Here we describe the functions of pRB-related proteins and E2F proteins that have emerged from genetic and biochemical experiments in Caenorhabditis elegans and Drosophila melanogaster. The similarities that have been observed between worms, flies and mammals provide insight into the core activities of pRB and E2F proteins and show how a common regulatory module can control various biological functions in different organisms.
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35
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Jud MC, Czerwinski MJ, Wood MP, Young RA, Gallo CM, Bickel JS, Petty EL, Mason JM, Little BA, Padilla PA, Schisa JA. Large P body-like RNPs form in C. elegans oocytes in response to arrested ovulation, heat shock, osmotic stress, and anoxia and are regulated by the major sperm protein pathway. Dev Biol 2008; 318:38-51. [PMID: 18439994 PMCID: PMC2442018 DOI: 10.1016/j.ydbio.2008.02.059] [Citation(s) in RCA: 88] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2007] [Revised: 02/16/2008] [Accepted: 02/29/2008] [Indexed: 11/29/2022]
Abstract
As Caenorhabditis elegans hermaphrodites age, sperm become depleted, ovulation arrests, and oocytes accumulate in the gonad arm. Large ribonucleoprotein (RNP) foci form in these arrested oocytes that contain RNA-binding proteins and translationally masked maternal mRNAs. Within 65 min of mating, the RNP foci dissociate and fertilization proceeds. The majority of arrested oocytes with foci result in viable embryos upon fertilization, suggesting that foci are not deleterious to oocyte function. We have determined that foci formation is not strictly a function of aging, and the somatic, ceh-18, branch of the major sperm protein pathway regulates the formation and dissociation of oocyte foci. Our hypothesis for the function of oocyte RNP foci is similar to the RNA-related functions of processing bodies (P bodies) and stress granules; here, we show three orthologs of P body proteins, DCP-2, CAR-1 and CGH-1, and two markers of stress granules, poly (A) binding protein (PABP) and TIA-1, appear to be present in the oocyte RNP foci. Our results are the first in vivo demonstration linking components of P bodies and stress granules in the germ line of a metazoan. Furthermore, our data demonstrate that formation of oocyte RNP foci is inducible in non-arrested oocytes by heat shock, osmotic stress, or anoxia, similar to the induction of stress granules in mammalian cells and P bodies in yeast. These data suggest commonalities between oocytes undergoing delayed fertilization and cells that are stressed environmentally, as to how they modulate mRNAs and regulate translation.
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Affiliation(s)
- Molly C. Jud
- Central Michigan University, Department of Biology, Mount Pleasant, MI 48859
| | | | - Megan P. Wood
- Central Michigan University, Department of Biology, Mount Pleasant, MI 48859
| | - Rachel A. Young
- Central Michigan University, Department of Biology, Mount Pleasant, MI 48859
| | | | - Jeremy S. Bickel
- Central Michigan University, Department of Biology, Mount Pleasant, MI 48859
| | - Emily L. Petty
- Central Michigan University, Department of Biology, Mount Pleasant, MI 48859
| | - Jennifer M. Mason
- Central Michigan University, Department of Biology, Mount Pleasant, MI 48859
| | - Brent A. Little
- University of North Texas, Department of Biological Sciences, P.O. Box 305220, Denton TX, 76203
| | - Pamela A. Padilla
- University of North Texas, Department of Biological Sciences, P.O. Box 305220, Denton TX, 76203
| | - Jennifer A. Schisa
- Central Michigan University, Department of Biology, Mount Pleasant, MI 48859
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36
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Lee MH, Hook B, Pan G, Kershner AM, Merritt C, Seydoux G, Thomson JA, Wickens M, Kimble J. Conserved regulation of MAP kinase expression by PUF RNA-binding proteins. PLoS Genet 2008; 3:e233. [PMID: 18166083 PMCID: PMC2323325 DOI: 10.1371/journal.pgen.0030233] [Citation(s) in RCA: 102] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2007] [Accepted: 11/14/2007] [Indexed: 01/06/2023] Open
Abstract
Mitogen-activated protein kinase (MAPK) and PUF (for Pumilio and FBF [fem-3 binding factor]) RNA-binding proteins control many cellular processes critical for animal development and tissue homeostasis. In the present work, we report that PUF proteins act directly on MAPK/ERK-encoding mRNAs to downregulate their expression in both the Caenorhabditis elegans germline and human embryonic stem cells. In C. elegans, FBF/PUF binds regulatory elements in the mpk-1 3′ untranslated region (3′ UTR) and coprecipitates with mpk-1 mRNA; moreover, mpk-1 expression increases dramatically in FBF mutants. In human embryonic stem cells, PUM2/PUF binds 3′UTR elements in both Erk2 and p38α mRNAs, and PUM2 represses reporter constructs carrying either Erk2 or p38α 3′ UTRs. Therefore, the PUF control of MAPK expression is conserved. Its biological function was explored in nematodes, where FBF promotes the self-renewal of germline stem cells, and MPK-1 promotes oocyte maturation and germ cell apoptosis. We found that FBF acts redundantly with LIP-1, the C. elegans homolog of MAPK phosphatase (MKP), to restrict MAPK activity and prevent apoptosis. In mammals, activated MAPK can promote apoptosis of cancer cells and restrict stem cell self-renewal, and MKP is upregulated in cancer cells. We propose that the dual negative regulation of MAPK by both PUF repression and MKP inhibition may be a conserved mechanism that influences both stem cell maintenance and tumor progression. The mitogen-activated protein (MAP) kinase (MAPK) enzyme is crucial for regulation of both stem cell maintenance and tumorigenesis. Two conserved controls of MAPK include its activation by RAS signaling and a kinase cascade as well as its inactivation by MAPK phosphatases (MKPs). We identify a third mode of conserved MAPK regulation. We demonstrate that PUF (for Pumilio and FBF [fem-3 binding factor]) RNA-binding proteins repress mRNAs encoding MAPK enzymes in both the Caenorhabditis elegans germline and human embryonic stem cells. PUF proteins have emerged as conserved regulators of germline stem cells in C. elegans, Drosophila, and probably vertebrates. Their molecular mode of action relies on binding to sequence elements in the 3′ untranslated region of target mRNAs. We report that PUF proteins bind and repress mRNAs encoding C. elegans MPK-1 as well as human ERK2 and p38α. We also report that PUF repression and MKP inactivation function redundantly in the C. elegans germline to restrict MPK-1/MAPK activity and prevent germ cell apoptosis. We suggest that this dual regulation of MAPK activity by PUF and MKP proteins may be a conserved mechanism for the control of growth and differentiation during animal development and tissue homeostasis.
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Affiliation(s)
- Myon-Hee Lee
- Howard Hughes Medical Institute, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Brad Hook
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Guangjin Pan
- Genome Centre of Wisconsin, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Aaron M Kershner
- Program in Cellular and Molecular Biology, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Christopher Merritt
- Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Geraldine Seydoux
- Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
- Howard Hughes Medical Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - James A Thomson
- Genome Centre of Wisconsin, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Marvin Wickens
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Judith Kimble
- Howard Hughes Medical Institute, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
- Program in Cellular and Molecular Biology, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
- * To whom correspondence should be addressed. E-mail:
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37
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Lin B, Reinke V. The candidate MAP kinase phosphorylation substrate DPL-1 (DP) promotes expression of the MAP kinase phosphatase LIP-1 in C. elegans germ cells. Dev Biol 2008; 316:50-61. [PMID: 18304523 DOI: 10.1016/j.ydbio.2007.12.042] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2007] [Revised: 12/21/2007] [Accepted: 12/31/2007] [Indexed: 10/22/2022]
Abstract
The highly-conserved, commonly used MAP kinase signaling cascade plays multiple integral roles in germline development in Caenorhabditis elegans. Using a functional proteomic approach, we found that the transcription factor DPL-1, a component of the LIN-35(Rb)/EFL-1(E2F)/DPL-1(DP) pathway, is a candidate phosphorylation substrate of MAP kinase. Moreover, dpl-1 genetically interacts with mpk-1(MAP kinase) to control chromosome morphology in pachytene of meiosis I, as does lin-35. However, EFL-1, the canonical DPL-1 heterodimeric partner, does not have a role in this process. Interestingly, we find that DPL-1 and EFL-1, but not LIN-35, promote the expression of a negative regulator of MPK-1, the MAP kinase phosphatase LIP-1. Two E2F consensus motifs are present upstream of the lip-1 open reading frame. Therefore, the Rb/E2F/DP pathway intersects with MAP kinase signaling at multiple points to regulate different aspects of C. elegans germ cell development. These two highly conserved pathways with major regulatory roles in proliferation and differentiation likely have multiple mechanisms for cross-talk during development across many species.
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Affiliation(s)
- Baiqing Lin
- Department of Genetics, School of Medicine, Yale University, New Haven, CT 06520, USA
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38
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Lee MH, Ohmachi M, Arur S, Nayak S, Francis R, Church D, Lambie E, Schedl T. Multiple functions and dynamic activation of MPK-1 extracellular signal-regulated kinase signaling in Caenorhabditis elegans germline development. Genetics 2007; 177:2039-62. [PMID: 18073423 PMCID: PMC2219468 DOI: 10.1534/genetics.107.081356] [Citation(s) in RCA: 151] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2007] [Accepted: 09/20/2007] [Indexed: 11/18/2022] Open
Abstract
The raison d'etre of the germline is to produce oocytes and sperm that pass genetic material and cytoplasmic constituents to the next generation. To achieve this goal, many developmental processes must be executed and coordinated. ERK, the terminal MAP kinase of a number of signaling pathways, controls many aspects of development. Here we present a comprehensive analysis of MPK-1 ERK in Caenorhabditis elegans germline development. MPK-1 functions in four developmental switches: progression through pachytene, oocyte meiotic maturation/ovulation, male germ cell fate specification, and a nonessential function of promoting the proliferative fate. MPK-1 also regulates multiple aspects of cell biology during oogenesis, including membrane organization and morphogenesis: organization of pachytene cells on the surface of the gonadal tube, oocyte organization and differentiation, oocyte growth control, and oocyte nuclear migration. MPK-1 activation is temporally/spatially dynamic and most processes appear to be controlled through sustained activation. MPK-1 thus may act not only in the control of individual processes but also in the coordination of contemporaneous processes and the integration of sequential processes. Knowledge of the dynamic activation and diverse functions of MPK-1 provides the foundation for identification of upstream signaling cascades responsible for region-specific activation and the downstream substrates that mediate the various processes.
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Affiliation(s)
- Min-Ho Lee
- Department of Genetics, Washington University School of Medicine, St. Louis, Missouri 63110, USA
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39
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Vermeirssen V, Barrasa MI, Hidalgo CA, Babon JAB, Sequerra R, Doucette-Stamm L, Barabási AL, Walhout AJ. Transcription factor modularity in a gene-centered C. elegans core neuronal protein-DNA interaction network. Genome Res 2007; 17:1061-71. [PMID: 17513831 PMCID: PMC1899117 DOI: 10.1101/gr.6148107] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Transcription regulatory networks play a pivotal role in the development, function, and pathology of metazoan organisms. Such networks are comprised of protein-DNA interactions between transcription factors (TFs) and their target genes. An important question pertains to how the architecture of such networks relates to network functionality. Here, we show that a Caenorhabditis elegans core neuronal protein-DNA interaction network is organized into two TF modules. These modules contain TFs that bind to a relatively small number of target genes and are more systems specific than the TF hubs that connect the modules. Each module relates to different functional aspects of the network. One module contains TFs involved in reproduction and target genes that are expressed in neurons as well as in other tissues. The second module is enriched for paired homeodomain TFs and connects to target genes that are often exclusively neuronal. We find that paired homeodomain TFs are specifically expressed in C. elegans and mouse neurons, indicating that the neuronal function of paired homeodomains is evolutionarily conserved. Taken together, we show that a core neuronal C. elegans protein-DNA interaction network possesses TF modules that relate to different functional aspects of the complete network.
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Affiliation(s)
- Vanessa Vermeirssen
- Program in Gene Function and Expression and Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA
| | - M. Inmaculada Barrasa
- Program in Gene Function and Expression and Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA
| | - César A. Hidalgo
- Center for Complex Network Research, Department of Physics, University of Notre Dame, Notre Dame, Indiana 46556, USA
| | - Jenny Aurielle B. Babon
- Program in Gene Function and Expression and Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA
| | | | | | - Albert-László Barabási
- Center for Complex Network Research, Department of Physics, University of Notre Dame, Notre Dame, Indiana 46556, USA
| | - Albertha J.M. Walhout
- Program in Gene Function and Expression and Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA
- Corresponding author.E-mail ; fax (508) 856-5460
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40
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Matsubara Y, Kawasaki I, Urushiyama S, Yasuda T, Shirakata M, Iino Y, Shibuya H, Yamanashi Y. The adaptor-like protein ROG-1 is required for activation of the Ras-MAP kinase pathway and meiotic cell cycle progression in Caenorhabditis elegans. Genes Cells 2007; 12:407-20. [PMID: 17352744 DOI: 10.1111/j.1365-2443.2007.01061.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The Ras-MAP kinase pathway regulates varieties of fundamental cellular events. In Caenorhabditis elegans, this pathway is required for oocyte development; however, the nature of its up-stream regulators has remained elusive. Here, we identified a C. elegans gene, rog-1, which encodes the only protein having the IRS-type phosphotyrosine-binding (PTB) domain in the worms. ROG-1 has no obvious domain structure aside from the PTB domain, suggesting that it could serve as an adaptor down-stream of protein-tyrosine kinases (PTKs). RNA interference (RNAi)-mediated down-regulation of rog-1 mRNA significantly decreased brood size. rog-1(tm1031) truncation mutants showed a severe disruption in progression of developing oocytes from pachytene to diakinesis, as was seen in worms carrying a loss-of-function mutation in the let-60 Ras or mpk-1 MAP kinase gene. Furthermore, let-60 Ras-regulated activation of MPK-1 in the gonad is undetectable in rog-1(tm1031) mutants. Conversely, a gain-of-function mutation in the let-60 Ras gene rescues the brood size reduction and germ cell abnormality in rog-1(tm1031) worms. Consistently, rog-1 is preferentially expressed in the germ cells and its expression in the gonad is essential for oocyte development. Thus, ROG-1 is a key positive regulator of the Ras-MAP kinase pathway that permits germ cells to exit from pachytene.
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Affiliation(s)
- Yosuke Matsubara
- Department of Cell Regulation, Medical Research Institute, Tokyo, Japan
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41
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The SynMuv genes of Caenorhabditis elegans in vulval development and beyond. Dev Biol 2007; 306:1-9. [PMID: 17434473 DOI: 10.1016/j.ydbio.2007.03.016] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2006] [Revised: 02/26/2007] [Accepted: 03/05/2007] [Indexed: 01/12/2023]
Abstract
For a nonessential diminutive organ comprised of only 22 nuclei, the Caenorhabditis elegans vulva has done very well for itself. The status of the vulva as an overachiever is in part due to its inherent structural simplicity as well as to the intricate regulation of its induction and development. Studies over the past twenty years have shown the vulva to be a microcosm for organogenesis and a model for the integration of complex signaling pathways. Furthermore, many of these signaling molecules are themselves associated with cancer in mammals. This review focuses on what is perhaps the most intriguing and complex story to emerge from these studies thus far, the role of the Synthetic Multivulval (SynMuv) genes in controlling vulval cell-fate adoption. Recent advances have led to a greater mechanistic understanding of how these genes function during vulval development and have also identified roles for these genes in diverse developmental processes.
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42
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Bender AM, Kirienko NV, Olson SK, Esko JD, Fay DS. lin-35/Rb and the CoREST ortholog spr-1 coordinately regulate vulval morphogenesis and gonad development in C. elegans. Dev Biol 2007; 302:448-62. [PMID: 17070797 PMCID: PMC1933485 DOI: 10.1016/j.ydbio.2006.09.051] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2006] [Revised: 08/28/2006] [Accepted: 09/30/2006] [Indexed: 11/21/2022]
Abstract
Using a genetic screen to identify genes that carry out redundant functions during development with lin-35/Rb, the C. elegans Retinoblastoma family ortholog, we have identified a mutation in spr-1. spr-1 encodes the C. elegans ortholog of human CoREST, a protein containing Myb-like SANT and ELM2 domains, which functions as part of a transcriptional regulatory complex. CoREST recruits mediators of transcriptional repression, including histone deacetylase, and demethylase, and interacts with the tumor suppression protein REST. spr-1/CoREST was previously shown in C. elegans to suppress defects associated with loss of the presenilin sel-12, which functions in the proteolytic processing of LIN-12/Notch. Here we show that lin-35 and spr-1 coordinately regulate several developmental processes in C. elegans including the ingression of vulval cells as well as germline proliferation. We also show that loss of lin-35 and spr-1 hypersensitizes animals to a reduction in LIN-12/Notch activity, leading to the generation of proximal germline tumors. This defect, which is observed in lin-35; spr-1; lin-12(RNAi) and lin-35; spr-1; hop-1(RNAi) triple mutants is likely due to a delay in the entry of germ cells into meiosis.
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Affiliation(s)
- Aaron M. Bender
- University of Wyoming, College of Agriculture, Department of Molecular Biology Dept 3944, 1000 E. University Avenue, Laramie, WY 82071
| | - Natalia V. Kirienko
- University of Wyoming, College of Agriculture, Department of Molecular Biology Dept 3944, 1000 E. University Avenue, Laramie, WY 82071
| | - Sara K. Olson
- Department of Cellular and Molecular Medicine, Glycobiology Research and Training Center, University of California, San Diego, La Jolla CA 92093
| | - Jeffery D. Esko
- Department of Cellular and Molecular Medicine, Glycobiology Research and Training Center, University of California, San Diego, La Jolla CA 92093
| | - David S Fay
- University of Wyoming, College of Agriculture, Department of Molecular Biology Dept 3944, 1000 E. University Avenue, Laramie, WY 82071
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Reddien PW, Andersen EC, Huang MC, Horvitz HR. DPL-1 DP, LIN-35 Rb and EFL-1 E2F act with the MCD-1 zinc-finger protein to promote programmed cell death in Caenorhabditis elegans. Genetics 2007; 175:1719-33. [PMID: 17237514 PMCID: PMC1855110 DOI: 10.1534/genetics.106.068148] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
The genes egl-1, ced-9, ced-4, and ced-3 play major roles in programmed cell death in Caenorhabditis elegans. To identify genes that have more subtle activities, we sought mutations that confer strong cell-death defects in a genetically sensitized mutant background. Specifically, we screened for mutations that enhance the cell-death defects caused by a partial loss-of-function allele of the ced-3 caspase gene. We identified mutations in two genes not previously known to affect cell death, dpl-1 and mcd-1 (modifier of cell death). dpl-1 encodes the C. elegans homolog of DP, the human E2F-heterodimerization partner. By testing genes known to interact with dpl-1, we identified roles in cell death for four additional genes: efl-1 E2F, lin-35 Rb, lin-37 Mip40, and lin-52 dLin52. mcd-1 encodes a novel protein that contains one zinc finger and that is synthetically required with lin-35 Rb for animal viability. dpl-1 and mcd-1 act with efl-1 E2F and lin-35 Rb to promote programmed cell death and do so by regulating the killing process rather than by affecting the decision between survival and death. We propose that the DPL-1 DP, MCD-1 zinc finger, EFL-1 E2F, LIN-35 Rb, LIN-37 Mip40, and LIN-52 dLin52 proteins act together in transcriptional regulation to promote programmed cell death.
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Affiliation(s)
- Peter W Reddien
- Department of Biology, Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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Leacock SW, Reinke V. Expression profiling of MAP kinase-mediated meiotic progression in Caenorhabditis elegans. PLoS Genet 2006; 2:e174. [PMID: 17096596 PMCID: PMC1635537 DOI: 10.1371/journal.pgen.0020174] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2006] [Accepted: 08/28/2006] [Indexed: 12/02/2022] Open
Abstract
The LET-60 (Ras)/LIN-45 (Raf)/MPK-1 (MAP kinase) signaling pathway plays a key role in the development of multiple tissues in Caenorhabditis elegans. For the most part, the identities of the downstream genes that act as the ultimate effectors of MPK-1 signaling have remained elusive. A unique allele of mpk-1, ga111, displays a reversible, temperature-sensitive, tissue-specific defect in progression through meiotic prophase I. We performed gene expression profiling on mpk-1(ga111) animals to identify candidate downstream effectors of MPK-1 signaling in the germ line. This analysis delineated a cohort of genes whose expression requires MPK-1 signaling in germ cells in the pachytene stage of meiosis I. RNA in situ hybridization analysis shows that these genes are expressed in the germ line in an MPK-1-dependent manner and have a spatial expression pattern consistent with the location of activated MPK-1. We found that one MPK-1 signaling-responsive gene encoding a C2H2 zinc finger protein plays a role in meiotic chromosome segregation downstream of MPK-1. Additionally, discovery of genes responsive to MPK-1 signaling permitted us to order MPK-1 signaling relative to several events occurring in pachytene, including EFL-1/DPL-1 gene regulation and X chromosome reactivation. This study highlights the utility of applying global gene expression methods to investigate genes downstream of commonly used signaling pathways in vivo. In many tissues in developing organisms, signaling pathways interpret extracellular cues that change how genes are expressed inside the nucleus and thus direct the appropriate developmental choice. Identification of the genes that are responsive to signaling pathways is critical for understanding how these pathways can promote the correct cell fate. Additionally, understanding the relationships between different regulatory pathways will also help to decipher the network of gene expression that underlies development. The nematode Caenorhabditis elegans has many signaling pathways that are highly similar to those acting in mammals. In particular, the Ras/Raf/MAP kinase signaling pathway acts in many tissues in C. elegans to direct a diverse set of cell fates. Here, we identify a set of genes whose expression alters in response to Ras/Raf/MAP kinase signaling in the germ line during meiosis. We show that this set of genes is primarily expressed in the germ line and that at least one of these genes is important for proper germ cell fate downstream of Ras/Raf/MAP kinase signaling. We also find that the Ras/Raf/MAP kinase signaling pathway functions independently of a second regulatory pathway, the E2F pathway, that acts at a similar time during germ cell development.
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Affiliation(s)
- Stefanie W Leacock
- Department of Genetics, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Valerie Reinke
- Department of Genetics, Yale University School of Medicine, New Haven, Connecticut, United States of America
- * To whom correspondence should be addressed. E-mail:
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45
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Harrison MM, Ceol CJ, Lu X, Horvitz HR. Some C. elegans class B synthetic multivulva proteins encode a conserved LIN-35 Rb-containing complex distinct from a NuRD-like complex. Proc Natl Acad Sci U S A 2006; 103:16782-7. [PMID: 17075059 PMCID: PMC1636532 DOI: 10.1073/pnas.0608461103] [Citation(s) in RCA: 110] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
The Caenorhabditis elegans synthetic multivulva (synMuv) genes act redundantly to antagonize the specification of vulval cell fates, which are promoted by an RTK/Ras pathway. At least 26 synMuv genes have been genetically identified, several of which encode proteins with homologs that act in chromatin remodeling or transcriptional repression. Here we report the molecular characterization of two synMuv genes, lin-37 and lin-54. We show that lin-37 and lin-54 encode proteins in a complex with at least seven synMuv proteins, including LIN-35, the only C. elegans homolog of the mammalian tumor suppressor Rb. Biochemical analyses of mutants suggest that LIN-9, LIN-53, and LIN-54 are required for the stable formation of this complex. This complex is distinct from a second complex of synMuv proteins with a composition similar to that of the mammalian Nucleosome Remodeling and Deacetylase complex. The class B synMuv complex we identified is evolutionarily conserved and likely functions in transcriptional repression and developmental regulation.
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Affiliation(s)
- Melissa M. Harrison
- Howard Hughes Medical Institute, Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - Craig J. Ceol
- Howard Hughes Medical Institute, Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - Xiaowei Lu
- Howard Hughes Medical Institute, Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - H. Robert Horvitz
- Howard Hughes Medical Institute, Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139
- To whom correspondence should be addressed. E-mail:
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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.
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Affiliation(s)
- Jennifer R Tenlen
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
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Kritikou EA, Milstein S, Vidalain PO, Lettre G, Bogan E, Doukoumetzidis K, Gray P, Chappell TG, Vidal M, Hengartner MO. C. elegans GLA-3 is a novel component of the MAP kinase MPK-1 signaling pathway required for germ cell survival. Genes Dev 2006; 20:2279-92. [PMID: 16912277 PMCID: PMC1553210 DOI: 10.1101/gad.384506] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
During oocyte development in Caenorhabditis elegans, approximately half of all developing germ cells undergo apoptosis. While this process is evolutionarily conserved from worms to humans, the regulators of germ cell death are still largely unknown. In a genetic screen for novel genes involved in germline apoptosis in Caenorhabditis elegans, we identified and cloned gla-3. Loss of gla-3 function results in increased germline apoptosis and reduced brood size due to defective pachytene exit from meiosis I. gla-3 encodes a TIS11-like zinc-finger-containing protein that is expressed in the germline, from the L4 larval stage to adulthood. Biochemical evidence and genetic epistasis analysis revealed that GLA-3 participates in the MAPK signaling cascade and directly interacts with the C. elegans MAPK MPK-1, an essential meiotic regulator. Our results show that GLA-3 is a new component of the MAPK cascade that controls meiotic progression and apoptosis in the C. elegans germline and functions as a negative regulator of the MAPK signaling pathway during vulval development and in muscle cells.
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48
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Suzuki Y, Han M. Genetic redundancy masks diverse functions of the tumor suppressor gene PTEN during C. elegans development. Genes Dev 2006; 20:423-8. [PMID: 16481471 PMCID: PMC1369044 DOI: 10.1101/gad.1378906] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Genetic redundancy is associated with a large percentage of genes. We investigated PTEN (phosphatase and tensin homolog deleted on chromosome 10) tumor suppressor gene functions that eluded single mutant analyses, using a Caenorhabditis elegans genome-wide screen. We show that at least 27 genes collaborate with the worm PTEN homolog daf-18 for various functions previously concealed by genetic redundancy, including embryogenesis, cuticle turnover, egg laying, and oocyte maturation. In one example, daf-18 appears to constitute a cell-autonomous germline signal that converges with a somatic gonad signal mediated by ceh-18 at a kinase inhibition. We provide evidence that daf-18 elicits some functions independent of the downstream gene daf-16.
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Affiliation(s)
- Yo Suzuki
- Howard Hughes Medical Institute and Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, Colorado 80309, USA
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49
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Ceol CJ, Stegmeier F, Harrison MM, Horvitz HR. Identification and classification of genes that act antagonistically to let-60 Ras signaling in Caenorhabditis elegans vulval development. Genetics 2006; 173:709-26. [PMID: 16624904 PMCID: PMC1526536 DOI: 10.1534/genetics.106.056465] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The synthetic multivulva (synMuv) genes negatively regulate Ras-mediated vulval induction in the nematode Caenorhabditis elegans. The synMuv genes define three classes, A, B, and C, such that double mutants carrying mutations in genes of any two classes are multivulva. The class B synMuv genes include lin-35, a homolog of the retinoblastoma (Rb) tumor suppressor gene, as well as homologs of genes that function with Rb in transcriptional regulation. We screened for additional synMuv mutations using a strategy different from that of previous synMuv genetic screens. Some of the mutations we recovered affect new synMuv genes. We present criteria for assigning synMuv mutations into different genetic classes. We also describe the molecular characterization of the class B synMuv gene lin-65.
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Affiliation(s)
- Craig J Ceol
- Department of Biology, Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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50
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Yamamoto I, Kosinski ME, Greenstein D. Start me up: Cell signaling and the journey from oocyte to embryo inC. elegans. Dev Dyn 2006; 235:571-85. [PMID: 16372336 DOI: 10.1002/dvdy.20662] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Intercellular communication plays a pivotal role in regulating and coordinating oocyte meiosis and fertilization, key triggers for embryonic development. The nematode Caenorhabaditis elegans has emerged as an important experimental paradigm for exploring these fundamental reproductive processes and their regulation. The oocytes of most animal species arrest during meiotic prophase and complete meiosis in response to intercellular signaling in the process of meiotic maturation. Oocyte meiotic maturation is defined by the transition between diakinesis and metaphase of meiosis I and is accompanied by nuclear envelope breakdown and meiotic spindle assembly. As such, the meiotic maturation process is essential for completing meiosis and a prerequisite for successful fertilization. In C. elegans, the processes of meiotic maturation, ovulation, and fertilization are temporally coupled: sperm utilize the major sperm protein as a hormone to trigger oocyte meiotic maturation, and, in turn, the maturing oocyte signals its own ovulation, leading to fertilization. The powerful genetic screens possible in C. elegans have led to the identification of several sperm cell surface proteins that are required for the interaction and fusion of gametes at fertilization. The study of these proteins provides fundamental insights into fertilization mechanisms, their role in speciation, and their potential conservation across phyla. Signaling processes sparked by fertilization are required for meiotic chromosome segregation and initiating the embryonic program. Here we review recent advances in understanding how signaling mechanisms contribute to the oocyte-to-embryo transition in C. elegans.
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Affiliation(s)
- Ikuko Yamamoto
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-8240, USA
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