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Martinez MAQ, Zhao CZ, Moore FEQ, Yee C, Zhang W, Shen K, Martin BL, Matus DQ. Cell cycle perturbation uncouples mitotic progression and invasive behavior in a post-mitotic cell. Differentiation 2024; 137:100765. [PMID: 38522217 PMCID: PMC11196158 DOI: 10.1016/j.diff.2024.100765] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2024] [Revised: 03/05/2024] [Accepted: 03/09/2024] [Indexed: 03/26/2024]
Abstract
The acquisition of the post-mitotic state is crucial for the execution of many terminally differentiated cell behaviors during organismal development. However, the mechanisms that maintain the post-mitotic state in this context remain poorly understood. To gain insight into these mechanisms, we used the genetically and visually accessible model of C. elegans anchor cell (AC) invasion into the vulval epithelium. The AC is a terminally differentiated uterine cell that normally exits the cell cycle and enters a post-mitotic state before initiating contact between the uterus and vulva through a cell invasion event. Here, we set out to identify the set of negative cell cycle regulators that maintain the AC in this post-mitotic, invasive state. Our findings revealed a critical role for CKI-1 (p21CIP1/p27KIP1) in redundantly maintaining the post-mitotic state of the AC, as loss of CKI-1 in combination with other negative cell cycle regulators-including CKI-2 (p21CIP1/p27KIP1), LIN-35 (pRb/p107/p130), FZR-1 (Cdh1/Hct1), and LIN-23 (β-TrCP)-resulted in proliferating ACs. Remarkably, time-lapse imaging revealed that these ACs retain their ability to invade. Upon examination of a node in the gene regulatory network controlling AC invasion, we determined that proliferating, invasive ACs do so by maintaining aspects of pro-invasive gene expression. We therefore report that the requirement for a post-mitotic state for invasive cell behavior can be bypassed following direct cell cycle perturbation.
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Affiliation(s)
- Michael A Q Martinez
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY, 11794, USA
| | - Chris Z Zhao
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY, 11794, USA
| | - Frances E Q Moore
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY, 11794, USA
| | - Callista Yee
- Howard Hughes Medical Institute, Department of Biology, Stanford University, Stanford, CA, 94305, USA
| | - Wan Zhang
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY, 11794, USA
| | - Kang Shen
- Howard Hughes Medical Institute, Department of Biology, Stanford University, Stanford, CA, 94305, USA
| | - Benjamin L Martin
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY, 11794, USA
| | - David Q Matus
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY, 11794, USA.
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Martinez MAQ, Zhao CZ, Moore FEQ, Yee C, Zhang W, Shen K, Martin BL, Matus DQ. Cell cycle perturbation uncouples mitotic progression and invasive behavior in a post-mitotic cell. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.03.16.533034. [PMID: 38370624 PMCID: PMC10871222 DOI: 10.1101/2023.03.16.533034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/20/2024]
Abstract
The acquisition of the post-mitotic state is crucial for the execution of many terminally differentiated cell behaviors during organismal development. However, the mechanisms that maintain the post-mitotic state in this context remain poorly understood. To gain insight into these mechanisms, we used the genetically and visually accessible model of C. elegans anchor cell (AC) invasion into the vulval epithelium. The AC is a terminally differentiated uterine cell that normally exits the cell cycle and enters a post-mitotic state, initiating contact between the uterus and vulva through a cell invasion event. Here, we set out to identify the set of negative cell cycle regulators that maintain the AC in this post-mitotic, invasive state. Our findings revealed a critical role for CKI-1 (p21CIP1/p27KIP1) in redundantly maintaining the post-mitotic state of the AC, as loss of CKI-1 in combination with other negative cell cycle regulators-including CKI-2 (p21CIP1/p27KIP1), LIN-35 (pRb/p107/p130), FZR-1 (Cdh1/Hct1), and LIN-23 (β-TrCP)-resulted in proliferating ACs. Remarkably, time-lapse imaging revealed that these ACs retain their ability to invade. Upon examination of a node in the gene regulatory network controlling AC invasion, we determined that proliferating, invasive ACs do so by maintaining aspects of pro-invasive gene expression. We therefore report that the requirement for a post-mitotic state for invasive cell behavior can be bypassed following direct cell cycle perturbation.
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Affiliation(s)
- Michael A Q Martinez
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794, USA
| | - Chris Z Zhao
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794, USA
| | - Frances E Q Moore
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794, USA
| | - Callista Yee
- Howard Hughes Medical Institute, Department of Biology, Stanford University, Stanford, CA 94305, USA
| | - Wan Zhang
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794, USA
| | - Kang Shen
- Howard Hughes Medical Institute, Department of Biology, Stanford University, Stanford, CA 94305, USA
| | - Benjamin L Martin
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794, USA
| | - David Q Matus
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794, USA
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3
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Pluta AJ, Studniarek C, Murphy S, Norbury CJ. Cyclin-dependent kinases: Masters of the eukaryotic universe. WILEY INTERDISCIPLINARY REVIEWS. RNA 2023; 15:e1816. [PMID: 37718413 PMCID: PMC10909489 DOI: 10.1002/wrna.1816] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2023] [Revised: 07/21/2023] [Accepted: 08/03/2023] [Indexed: 09/19/2023]
Abstract
A family of structurally related cyclin-dependent protein kinases (CDKs) drives many aspects of eukaryotic cell function. Much of the literature in this area has considered individual members of this family to act primarily either as regulators of the cell cycle, the context in which CDKs were first discovered, or as regulators of transcription. Until recently, CDK7 was the only clear example of a CDK that functions in both processes. However, new data points to several "cell-cycle" CDKs having important roles in transcription and some "transcriptional" CDKs having cell cycle-related targets. For example, novel functions in transcription have been demonstrated for the archetypal cell cycle regulator CDK1. The increasing evidence of the overlap between these two CDK types suggests that they might play a critical role in coordinating the two processes. Here we review the canonical functions of cell-cycle and transcriptional CDKs, and provide an update on how these kinases collaborate to perform important cellular functions. We also provide a brief overview of how dysregulation of CDKs contributes to carcinogenesis, and possible treatment avenues. This article is categorized under: RNA Interactions with Proteins and Other Molecules > RNA-Protein Complexes RNA Processing > 3' End Processing RNA Processing > Splicing Regulation/Alternative Splicing.
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Affiliation(s)
| | | | - Shona Murphy
- Sir William Dunn School of PathologyUniversity of OxfordOxfordUK
| | - Chris J. Norbury
- Sir William Dunn School of PathologyUniversity of OxfordOxfordUK
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de la Cova CC, Townley R, Greenwald I. Negative feedback by conserved kinases patterns the degradation of Caenorhabditis elegans Raf in vulval fate patterning. Development 2020; 147:226094. [PMID: 33144396 DOI: 10.1242/dev.195941] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2020] [Accepted: 10/27/2020] [Indexed: 11/20/2022]
Abstract
Activation of a canonical EGFR-Ras-Raf-ERK cascade initiates patterning of multipotent vulval precursor cells (VPCs) of Caenorhabditis elegans We have previously shown that this pathway includes a negative-feedback component in which MPK-1/ERK activity targets the upstream kinase LIN-45/Raf for degradation by the SEL-10/FBXW7 E3 ubiquitin ligase. This regulation requires a Cdc4 phosphodegron (CPD) in LIN-45 that is conserved in BRAF. Here, we identify and characterize the minimal degron that encompasses the CPD and is sufficient for SEL-10-mediated, MPK-1-dependent protein degradation. A targeted screen of conserved protein kinase-encoding genes yielded gsk-3 (an ortholog of human GSK3B) and cdk-2 (a CDK2-related kinase) as required for LIN-45 degron-mediated turnover. Genetic analysis revealed that LIN-45 degradation is blocked at the second larval stage due to cell cycle quiescence, and that relief of this block during the third larval stage relies on activation of CDKs. Additionally, activation of MPK-1 provides spatial pattern to LIN-45 degradation but does not bypass the requirement for gsk-3 and cdk-2 This analysis supports a model whereby MPK-1/ERK, GSK-3/GSK3 and CDK-2/CDK2, along with SEL-10/FBXW7, constitute a regulatory network that exerts spatial and temporal control of LIN-45/Raf degradation during VPC patterning.
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Affiliation(s)
- Claire C de la Cova
- Department of Biological Sciences, Columbia University, New York, NY 10027, USA.,Department of Biological Sciences, University of Wisconsin Milwaukee, Milwaukee, WI 53201, USA
| | - Robert Townley
- Department of Biological Sciences, Columbia University, New York, NY 10027, USA.,Department of Biological Sciences, University of Wisconsin Milwaukee, Milwaukee, WI 53201, USA
| | - Iva Greenwald
- Department of Biological Sciences, Columbia University, New York, NY 10027, USA
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5
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CDK8 Regulates Insulin Secretion and Mediates Postnatal and Stress-Induced Expression of Neuropeptides in Pancreatic β Cells. Cell Rep 2020; 28:2892-2904.e7. [PMID: 31509750 DOI: 10.1016/j.celrep.2019.08.025] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Revised: 06/26/2019] [Accepted: 08/05/2019] [Indexed: 12/13/2022] Open
Abstract
Cyclin-dependent kinases (CDKs) contribute to vital cellular processes including cell cycle regulation. Loss of CDKs is associated with impaired insulin secretion and β cell survival; however, the function of CDK8 in β cells remains elusive. Here, we report that genetic ablation of Cdk8 improves glucose tolerance by increasing insulin secretion. We identify OSBPL3 as a CDK8-dependent phosphoprotein, which acts as a negative regulator of insulin secretion in response to glucose. We also show that embryonic gene silencing of neuropeptide Y in β cells is compromised in Cdk8-null mice, leading to continued expression into adulthood. Cdk8 ablation in β cells aggravates apoptosis and induces de novo expression of neuropeptides upon oxidative stress. Moreover, pancreatic islets exposed to stress display augmented apoptosis in the presence of these same neuropeptides. Our results reveal critical roles for CDK8 in β cell function and survival during metabolic stress that are in part mediated through de novo expression of neuropeptides.
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Besnard F, Picao-Osorio J, Dubois C, Félix MA. A broad mutational target explains a fast rate of phenotypic evolution. eLife 2020; 9:54928. [PMID: 32851977 PMCID: PMC7556874 DOI: 10.7554/elife.54928] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2020] [Accepted: 08/27/2020] [Indexed: 12/30/2022] Open
Abstract
The rapid evolution of a trait in a clade of organisms can be explained by the sustained action of natural selection or by a high mutational variance, that is the propensity to change under spontaneous mutation. The causes for a high mutational variance are still elusive. In some cases, fast evolution depends on the high mutation rate of one or few loci with short tandem repeats. Here, we report on the fastest evolving cell fate among vulva precursor cells in Caenorhabditis nematodes, that of P3.p. We identify and validate causal mutations underlying P3.p's high mutational variance. We find that these positions do not present any characteristics of a high mutation rate, are scattered across the genome and the corresponding genes belong to distinct biological pathways. Our data indicate that a broad mutational target size is the cause of the high mutational variance and of the corresponding fast phenotypic evolutionary rate. Heritable characteristics or traits of a group of organisms, for example the large brain size of primates or the hooves of a horse, are determined by genes, the environment, and by the interactions between them. Traits can change over time and generations when enough mutations in these genes have spread in a species to result in visible differences. However, some traits, such as the large brain of primates, evolve faster than others, but why this is the case has been unclear. It could be that a few specific genes important for that trait in question mutate at a high rate, or, that many genes affect the trait, creating a lot of variation for natural selection to choose from. Here, Besnard, Picao-Osorio et al. studied the roundworm Caenorhabditis elegans to better understand the causes underlying the different rates of trait evolution. These worms have a short life cycle and evolve quickly over many generations, making them an ideal candidate for studying mutation rates in different traits. Previous studies have shown that one of C. elegans’ six cells of the reproductive system evolves faster than the others. To investigate this further, Besnard, Picao-Osorio et al. analysed the genetic mutations driving change in this cell in 250 worm generations. The results showed that five mutations in five different genes – all responsible for different processes in the cells – were behind the supercharged evolution of this particular cell. This suggests that fast evolution results from natural selection acting upon a collection of genes, rather than one gene, and that many genes and pathways shape this trait. In conclusion, these results demonstrate that how traits are coded at the molecular level, in one gene or many, can influence the rate at which they evolve.
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Affiliation(s)
- Fabrice Besnard
- Institut de Biologie de l'École Normale Supérieure, CNRS, Inserm, Paris, France.,Laboratoire Reproduction et Développement des Plantes, Univ Lyon, ENS de Lyon, UCB Lyon 1, CNRS, INRAE, Inria, Lyon, France
| | - Joao Picao-Osorio
- Institut de Biologie de l'École Normale Supérieure, CNRS, Inserm, Paris, France
| | - Clément Dubois
- Institut de Biologie de l'École Normale Supérieure, CNRS, Inserm, Paris, France
| | - Marie-Anne Félix
- Institut de Biologie de l'École Normale Supérieure, CNRS, Inserm, Paris, France
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7
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Developmental Control of the Cell Cycle: Insights from Caenorhabditis elegans. Genetics 2019; 211:797-829. [PMID: 30846544 PMCID: PMC6404260 DOI: 10.1534/genetics.118.301643] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2018] [Accepted: 10/10/2018] [Indexed: 12/11/2022] Open
Abstract
During animal development, a single fertilized egg forms a complete organism with tens to trillions of cells that encompass a large variety of cell types. Cell cycle regulation is therefore at the center of development and needs to be carried out in close coordination with cell differentiation, migration, and death, as well as tissue formation, morphogenesis, and homeostasis. The timing and frequency of cell divisions are controlled by complex combinations of external and cell-intrinsic signals that vary throughout development. Insight into how such controls determine in vivo cell division patterns has come from studies in various genetic model systems. The nematode Caenorhabditis elegans has only about 1000 somatic cells and approximately twice as many germ cells in the adult hermaphrodite. Despite the relatively small number of cells, C. elegans has diverse tissues, including intestine, nerves, striated and smooth muscle, and skin. C. elegans is unique as a model organism for studies of the cell cycle because the somatic cell lineage is invariant. Somatic cells divide at set times during development to produce daughter cells that adopt reproducible developmental fates. Studies in C. elegans have allowed the identification of conserved cell cycle regulators and provided insights into how cell cycle regulation varies between tissues. In this review, we focus on the regulation of the cell cycle in the context of C. elegans development, with reference to other systems, with the goal of better understanding how cell cycle regulation is linked to animal development in general.
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Abstract
The extracellular signal-regulated kinase (ERK) pathway leads to activation of the effector molecule ERK, which controls downstream responses by phosphorylating a variety of substrates, including transcription factors. Crucial insights into the regulation and function of this pathway came from studying embryos in which specific phenotypes arise from aberrant ERK activation. Despite decades of research, several important questions remain to be addressed for deeper understanding of this highly conserved signaling system and its function. Answering these questions will require quantifying the first steps of pathway activation, elucidating the mechanisms of transcriptional interpretation and measuring the quantitative limits of ERK signaling within which the system must operate to avoid developmental defects.
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Affiliation(s)
- Aleena L Patel
- Lewis Sigler Institute for Integrative Genomics, Department of Chemical Engineering, Princeton University, Princeton, NJ 08544, USA
| | - Stanislav Y Shvartsman
- Lewis Sigler Institute for Integrative Genomics, Department of Chemical Engineering, Princeton University, Princeton, NJ 08544, USA
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9
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CDK8/19 inhibition induces premature G1/S transition and ATR-dependent cell death in prostate cancer cells. Oncotarget 2018; 9:13474-13487. [PMID: 29568371 PMCID: PMC5862592 DOI: 10.18632/oncotarget.24414] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2017] [Accepted: 02/01/2018] [Indexed: 12/13/2022] Open
Abstract
The CDK8/19 kinase module comprises a subcomplex that interacts with the Mediator complex and regulates gene expression through phosphorylation of transcription factors and Mediator subunits. Mediator complex subunits have been increasingly implicated in cancer and other diseases. Although high expression of CDK8/19 has been demonstrated in prostate cancer, its function has not been thoroughly examined. Here we report that CDK8/19 modulates the gene expression of cell cycle regulators and thereby maintains the proper G1/S transition in prostate cancer cells. We show that highly selective CDK8/19 inhibitors exerted anti-proliferative activity in prostate cancer cells both in vitro and in vivo. In CDK8/19 inhibitor-sensitive prostate cancer cells, the compounds reduced the population of G1 phase cells and elevated that of S phase cells through the modulation of G1/S transition regulators at the level of mRNA expression. Furthermore, the premature G1/S transition induced a DNA damage response that was followed by ATR-dependent and caspase-independent cell death. These findings suggest a novel role of CDK8/19 in transcription-mediated cell cycle control, albeit with possible contribution of other proteins inhibited by the compounds. Our data provide a rationale for further investigation of CDK8/19 inhibitors as a new therapeutic approach to prostate cancer.
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Integration of EGFR and LIN-12/Notch Signaling by LIN-1/Elk1, the Cdk8 Kinase Module, and SUR-2/Med23 in Vulval Precursor Cell Fate Patterning in Caenorhabditis elegans. Genetics 2017; 207:1473-1488. [PMID: 28954762 DOI: 10.1534/genetics.117.300192] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2017] [Accepted: 09/26/2017] [Indexed: 01/25/2023] Open
Abstract
Six initially equivalent, multipotential Vulval Precursor Cells (VPCs) in Caenorhabditis elegans adopt distinct cell fates in a precise spatial pattern, with each fate associated with transcription of different target genes. The pattern is centered on a cell that adopts the "1°" fate through Epidermal Growth Factor Receptor (EGFR) activity, and produces a lateral signal composed of ligands that activate LIN-12/Notch in the two flanking VPCs to cause them to adopt "2°" fate. Here, we investigate orthologs of a transcription complex that acts in mammalian EGFR signaling-lin-1/Elk1, sur-2/Med23, and the Cdk8 Kinase module (CKM)-previously implicated in aspects of 1° fate in C. elegans and show they act in different combinations for different processes for 2° fate. When EGFR is inactive, the CKM, but not SUR-2, helps to set a threshold for LIN-12/Notch activity in all VPCs. When EGFR is active, all three factors act to resist LIN-12/Notch, as revealed by the reduced ability of ectopically-activated LIN-12/Notch to activate target gene reporters. We show that overcoming this resistance in the 1° VPC leads to repression of lateral signal gene reporters, suggesting that resistance to LIN-12/Notch helps ensure that P6.p becomes a robust source of the lateral signal. In addition, we show that sur-2/Med23 and lin-1/Elk1, and not the CKM, are required to promote endocytic downregulation of LIN-12-GFP in the 1° VPC. Finally, our analysis using cell fate reporters reveals that both EGFR and LIN-12/Notch signal transduction pathways are active in all VPCs in lin-1/Elk1 mutants, and that lin-1/Elk1 is important for integrating EGFR and lin-12/Notch signaling inputs in the VPCs so that the proper gene complement is transcribed.
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11
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The C. elegans hox gene lin-39 controls cell cycle progression during vulval development. Dev Biol 2016; 418:124-134. [DOI: 10.1016/j.ydbio.2016.07.018] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2016] [Revised: 07/12/2016] [Accepted: 07/19/2016] [Indexed: 12/17/2022]
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12
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The Mediator Kinase Module Restrains Epidermal Growth Factor Receptor Signaling and Represses Vulval Cell Fate Specification in Caenorhabditis elegans. Genetics 2015; 202:583-99. [PMID: 26715664 DOI: 10.1534/genetics.115.180265] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2015] [Accepted: 12/18/2015] [Indexed: 12/27/2022] Open
Abstract
Cell signaling pathways that control proliferation and determine cell fates are tightly regulated to prevent developmental anomalies and cancer. Transcription factors and coregulators are important effectors of signaling pathway output, as they regulate downstream gene programs. In Caenorhabditis elegans, several subunits of the Mediator transcriptional coregulator complex promote or inhibit vulva development, but pertinent mechanisms are poorly defined. Here, we show that Mediator's dissociable cyclin dependent kinase 8 (CDK8) module (CKM), consisting of cdk-8, cic-1/Cyclin C, mdt-12/dpy-22, and mdt-13/let-19, is required to inhibit ectopic vulval cell fates downstream of the epidermal growth factor receptor (EGFR)-Ras-extracellular signal-regulated kinase (ERK) pathway. cdk-8 inhibits ectopic vulva formation by acting downstream of mpk-1/ERK, cell autonomously in vulval cells, and in a kinase-dependent manner. We also provide evidence that the CKM acts as a corepressor for the Ets-family transcription factor LIN-1, as cdk-8 promotes transcriptional repression by LIN-1. In addition, we find that CKM mutation alters Mediator subunit requirements in vulva development: the mdt-23/sur-2 subunit, which is required for vulva development in wild-type worms, is dispensable for ectopic vulva formation in CKM mutants, which instead display hallmarks of unrestrained Mediator tail module activity. We propose a model whereby the CKM controls EGFR-Ras-ERK transcriptional output by corepressing LIN-1 and by fine tuning Mediator specificity, thus balancing transcriptional repression vs. activation in a critical developmental signaling pathway. Collectively, these data offer an explanation for CKM repression of EGFR signaling output and ectopic vulva formation and provide the first evidence of Mediator CKM-tail module subunit crosstalk in animals.
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Gorrepati L, Krause MW, Chen W, Brodigan TM, Correa-Mendez M, Eisenmann DM. Identification of Wnt Pathway Target Genes Regulating the Division and Differentiation of Larval Seam Cells and Vulval Precursor Cells in Caenorhabditis elegans. G3 (BETHESDA, MD.) 2015; 5:1551-66. [PMID: 26048561 PMCID: PMC4528312 DOI: 10.1534/g3.115.017715] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/27/2015] [Accepted: 05/18/2015] [Indexed: 12/29/2022]
Abstract
The evolutionarily conserved Wnt/β-catenin signaling pathway plays a fundamental role during metazoan development, regulating numerous processes including cell fate specification, cell migration, and stem cell renewal. Wnt ligand binding leads to stabilization of the transcriptional effector β-catenin and upregulation of target gene expression to mediate a cellular response. During larval development of the nematode Caenorhabditis elegans, Wnt/β-catenin pathways act in fate specification of two hypodermal cell types, the ventral vulval precursor cells (VPCs) and the lateral seam cells. Because little is known about targets of the Wnt signaling pathways acting during larval VPC and seam cell differentiation, we sought to identify genes regulated by Wnt signaling in these two hypodermal cell types. We conditionally activated Wnt signaling in larval animals and performed cell type-specific "mRNA tagging" to enrich for VPC and seam cell-specific mRNAs, and then used microarray analysis to examine gene expression compared to control animals. Two hundred thirty-nine genes activated in response to Wnt signaling were identified, and we characterized 50 genes further. The majority of these genes are expressed in seam and/or vulval lineages during normal development, and reduction of function for nine genes caused defects in the proper division, fate specification, fate execution, or differentiation of seam cells and vulval cells. Therefore, the combination of these techniques was successful at identifying potential cell type-specific Wnt pathway target genes from a small number of cells and at increasing our knowledge of the specification and behavior of these C. elegans larval hypodermal cells.
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Affiliation(s)
- Lakshmi Gorrepati
- Department of Biological Sciences, University of Maryland Baltimore County, Baltimore, Maryland 21250
| | | | - Weiping Chen
- Intramural Research Program, NIDDK, Bethesda, Maryland 20814
| | | | - Margarita Correa-Mendez
- Department of Biological Sciences, University of Maryland Baltimore County, Baltimore, Maryland 21250
| | - David M Eisenmann
- Department of Biological Sciences, University of Maryland Baltimore County, Baltimore, Maryland 21250
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14
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Schmid T, Hajnal A. Signal transduction during C. elegans vulval development: a NeverEnding story. Curr Opin Genet Dev 2015; 32:1-9. [DOI: 10.1016/j.gde.2015.01.006] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2014] [Revised: 01/19/2015] [Accepted: 01/21/2015] [Indexed: 11/16/2022]
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15
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Bai H, Zhang W, Qin XJ, Zhang T, Wu H, Liu JZ, Hai CX. Hydrogen peroxide modulates the proliferation/quiescence switch in the liver during embryonic development and posthepatectomy regeneration. Antioxid Redox Signal 2015; 22:921-37. [PMID: 25621814 DOI: 10.1089/ars.2014.5960] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
AIMS The liver undergoes marked changes in the rate of proliferation during normal development and regeneration through the coordinated activity of numerous signaling pathways. Little is known, however, about the events that act upstream of these signaling pathways. Here, we explore the modulatory effects of hydrogen peroxide (H2O2) on these pathways in the context of liver development and regeneration. RESULTS We show that H2O2 production during liver development and after partial hepatectomy is tightly regulated in time by specific H2O2-producing and scavenging proteins and dose dependently triggers two distinct pathways. Sustained elevated H2O2 levels are required for the activation of ERK signaling and trigger a shift from quiescence to proliferation. Contrastingly, sustained decreased H2O2 levels are required for the activation of p38 signaling and trigger a shift from proliferation to quiescence. Both events impact the cyclin D and Rb pathways and are involved in liver development and regeneration. Pharmacological lowering of H2O2 levels reduces the extent of fetal hepatocyte proliferation and delays the onset of liver regeneration. Chemical augmentation of H2O2 levels in adult hepatocytes triggers proliferation and delays the termination of liver regeneration. INNOVATION Our results challenge the traditional view of H2O2 as a deleterious stressor in response to liver damage and identify a novel role of endogenous H2O2 in liver development and regeneration. CONCLUSIONS Endogenous H2O2 production is tightly regulated during liver development and regeneration. H2O2 constitutes an important trigger for the proliferation and quiescence transition in hepatocytes via the concentration-dependent activation of the ERK or p38 pathway.
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Affiliation(s)
- Hua Bai
- Department of Toxicology, Shaanxi Provincial Key Laboratory of Free Radical Biology and Medicine, The Ministry of Education Key Laboratory of Hazard Assessment and Control in Special Operational Environment, School of Public Health, Fourth Military Medical University , Xi'an, China
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Weinstein N, Ortiz-Gutiérrez E, Muñoz S, Rosenblueth DA, Álvarez-Buylla ER, Mendoza L. A model of the regulatory network involved in the control of the cell cycle and cell differentiation in the Caenorhabditis elegans vulva. BMC Bioinformatics 2015; 16:81. [PMID: 25884811 PMCID: PMC4367908 DOI: 10.1186/s12859-015-0498-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2014] [Accepted: 02/16/2015] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND There are recent experimental reports on the cross-regulation between molecules involved in the control of the cell cycle and the differentiation of the vulval precursor cells (VPCs) of Caenorhabditis elegans. Such discoveries provide novel clues on how the molecular mechanisms involved in the cell cycle and cell differentiation processes are coordinated during vulval development. Dynamic computational models are helpful to understand the integrated regulatory mechanisms affecting these cellular processes. RESULTS Here we propose a simplified model of the regulatory network that includes sufficient molecules involved in the control of both the cell cycle and cell differentiation in the C. elegans vulva to recover their dynamic behavior. We first infer both the topology and the update rules of the cell cycle module from an expected time series. Next, we use a symbolic algorithmic approach to find which interactions must be included in the regulatory network. Finally, we use a continuous-time version of the update rules for the cell cycle module to validate the cyclic behavior of the network, as well as to rule out the presence of potential artifacts due to the synchronous updating of the discrete model. We analyze the dynamical behavior of the model for the wild type and several mutants, finding that most of the results are consistent with published experimental results. CONCLUSIONS Our model shows that the regulation of Notch signaling by the cell cycle preserves the potential of the VPCs and the three vulval fates to differentiate and de-differentiate, allowing them to remain completely responsive to the concentration of LIN-3 and lateral signal in the extracellular microenvironment.
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Affiliation(s)
- Nathan Weinstein
- Programa de Doctorado en Ciencias Biomédicas, Universidad Nacional Autónoma de, México, DF, México.
- Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, México, DF, México.
- Centro de Ciencias de la Complejidad, Universidad Nacional Autónoma de México, México, DF, México.
| | - Elizabeth Ortiz-Gutiérrez
- Programa de Doctorado en Ciencias Biomédicas, Universidad Nacional Autónoma de, México, DF, México.
- Instituto de Ecología, Universidad Nacional Autónoma de México, México, DF, México.
- Centro de Ciencias de la Complejidad, Universidad Nacional Autónoma de México, México, DF, México.
| | - Stalin Muñoz
- Instituto de Investigaciones en Matemáticas Aplicadas y en Sistemas, Universidad, Nacional Autónoma de México, México, DF, México.
| | - David A Rosenblueth
- Instituto de Investigaciones en Matemáticas Aplicadas y en Sistemas, Universidad, Nacional Autónoma de México, México, DF, México.
- Centro de Ciencias de la Complejidad, Universidad Nacional Autónoma de México, México, DF, México.
| | - Elena R Álvarez-Buylla
- Instituto de Ecología, Universidad Nacional Autónoma de México, México, DF, México.
- Centro de Ciencias de la Complejidad, Universidad Nacional Autónoma de México, México, DF, México.
| | - Luis Mendoza
- Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, México, DF, México.
- Centro de Ciencias de la Complejidad, Universidad Nacional Autónoma de México, México, DF, México.
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Grants JM, Goh GYS, Taubert S. The Mediator complex of Caenorhabditis elegans: insights into the developmental and physiological roles of a conserved transcriptional coregulator. Nucleic Acids Res 2015; 43:2442-53. [PMID: 25634893 PMCID: PMC4344494 DOI: 10.1093/nar/gkv037] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The Mediator multiprotein complex (‘Mediator’) is an important transcriptional coregulator that is evolutionarily conserved throughout eukaryotes. Although some Mediator subunits are essential for the transcription of all protein-coding genes, others influence the expression of only subsets of genes and participate selectively in cellular signaling pathways. Here, we review the current knowledge of Mediator subunit function in the nematode Caenorhabditis elegans, a metazoan in which established and emerging genetic technologies facilitate the study of developmental and physiological regulation in vivo. In this nematode, unbiased genetic screens have revealed critical roles for Mediator components in core developmental pathways such as epidermal growth factor (EGF) and Wnt/β-catenin signaling. More recently, important roles for C. elegans Mediator subunits have emerged in the regulation of lipid metabolism and of systemic stress responses, engaging conserved transcription factors such as nuclear hormone receptors (NHRs). We emphasize instances where similar functions for individual Mediator subunits exist in mammals, highlighting parallels between Mediator subunit action in nematode development and in human cancer biology. We also discuss a parallel between the association of the Mediator subunit MED12 with several human disorders and the role of its C. elegans ortholog mdt-12 as a regulatory hub that interacts with numerous signaling pathways.
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Affiliation(s)
- Jennifer M Grants
- Department of Medical Genetics, University of British Columbia, Vancouver, BC V5Z 4H4, Canada Centre for Molecular Medicine and Therapeutics, Child & Family Research Institute, University of British Columbia, Vancouver, BC V5Z 4H4, Canada
| | - Grace Y S Goh
- Centre for Molecular Medicine and Therapeutics, Child & Family Research Institute, University of British Columbia, Vancouver, BC V5Z 4H4, Canada Graduate Program in Cell and Developmental Biology, University of British Columbia, Vancouver, BC V5Z 4H4, Canada
| | - Stefan Taubert
- Department of Medical Genetics, University of British Columbia, Vancouver, BC V5Z 4H4, Canada Centre for Molecular Medicine and Therapeutics, Child & Family Research Institute, University of British Columbia, Vancouver, BC V5Z 4H4, Canada Graduate Program in Cell and Developmental Biology, University of British Columbia, Vancouver, BC V5Z 4H4, Canada
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18
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Yamada A, Nishida H. Control of the number of cell division rounds in distinct tissues during ascidian embryogenesis. Dev Growth Differ 2014; 56:376-86. [DOI: 10.1111/dgd.12141] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2014] [Revised: 03/30/2014] [Accepted: 04/07/2014] [Indexed: 01/13/2023]
Affiliation(s)
- Atsuko Yamada
- Department of Biological Sciences; Graduate School of Science; Osaka University; Toyonaka Osaka Japan
- International College; Osaka University; Toyonaka Osaka Japan
| | - Hiroki Nishida
- Department of Biological Sciences; Graduate School of Science; Osaka University; Toyonaka Osaka Japan
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19
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Kuwajima M, Kumano G, Nishida H. Regulation of the number of cell division rounds by tissue-specific transcription factors and Cdk inhibitor during ascidian embryogenesis. PLoS One 2014; 9:e90188. [PMID: 24608898 PMCID: PMC3946487 DOI: 10.1371/journal.pone.0090188] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2013] [Accepted: 01/31/2014] [Indexed: 02/06/2023] Open
Abstract
Mechanisms that regulate the number of cell division rounds during embryogenesis have remained largely elusive. To investigate this issue, we used the ascidian, which develops into a tadpole larva with a small number of cells. The embryonic cells divide 11.45 times on average from fertilization to hatching. The number of cell division rounds varies depending on embryonic lineages. Notochord and muscle consist of large postmitotic cells and stop dividing early in developing embryos. Here we show that conversion of mesenchyme to muscle cell fates by inhibition of inductive FGF signaling or mis-expression of a muscle-specific key transcription factor for muscle differentiation, Tbx6, changed the number of cell divisions in accordance with the altered fate. Tbx6 likely activates a putative mechanism to halt cell division at a specific stage. However, precocious expression of Tbx6 has no effect on progression of the developmental clock itself. Zygotic expression of a cyclin-dependent kinase inhibitor, CKI-b, is initiated in muscle and then in notochord precursors. CKI-b is possibly downstream of tissue-specific key transcription factors of notochord and muscle. In the two distinct muscle lineages, postmitotic muscle cells are generated after 9 and 8 rounds of cell division depending on lineage, but the final cell divisions occur at a similar developmental stage. CKI-b gene expression starts simultaneously in both muscle lineages at the 110-cell stage, suggesting that CKI-b protein accumulation halts cell division at a similar stage. The difference in the number of cell divisions would be due to the cumulative difference in cell cycle length. These results suggest that muscle cells do not count the number of cell division rounds, and that accumulation of CKI-b protein triggered by tissue-specific key transcription factors after cell fate determination might act as a kind of timer that measures elapsed time before cell division termination.
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Affiliation(s)
- Mami Kuwajima
- Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Osaka, Japan
| | - Gaku Kumano
- Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Osaka, Japan
| | - Hiroki Nishida
- Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Osaka, Japan
- * E-mail:
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20
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Roy SH, Tobin DV, Memar N, Beltz E, Holmen J, Clayton JE, Chiu DJ, Young LD, Green TH, Lubin I, Liu Y, Conradt B, Saito RM. A complex regulatory network coordinating cell cycles during C. elegans development is revealed by a genome-wide RNAi screen. G3 (BETHESDA, MD.) 2014; 4:795-804. [PMID: 24584095 PMCID: PMC4025478 DOI: 10.1534/g3.114.010546] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/30/2014] [Accepted: 02/25/2014] [Indexed: 12/11/2022]
Abstract
The development and homeostasis of multicellular animals requires precise coordination of cell division and differentiation. We performed a genome-wide RNA interference screen in Caenorhabditis elegans to reveal the components of a regulatory network that promotes developmentally programmed cell-cycle quiescence. The 107 identified genes are predicted to constitute regulatory networks that are conserved among higher animals because almost half of the genes are represented by clear human orthologs. Using a series of mutant backgrounds to assess their genetic activities, the RNA interference clones displaying similar properties were clustered to establish potential regulatory relationships within the network. This approach uncovered four distinct genetic pathways controlling cell-cycle entry during intestinal organogenesis. The enhanced phenotypes observed for animals carrying compound mutations attest to the collaboration between distinct mechanisms to ensure strict developmental regulation of cell cycles. Moreover, we characterized ubc-25, a gene encoding an E2 ubiquitin-conjugating enzyme whose human ortholog, UBE2Q2, is deregulated in several cancers. Our genetic analyses suggested that ubc-25 acts in a linear pathway with cul-1/Cul1, in parallel to pathways employing cki-1/p27 and lin-35/pRb to promote cell-cycle quiescence. Further investigation of the potential regulatory mechanism demonstrated that ubc-25 activity negatively regulates CYE-1/cyclin E protein abundance in vivo. Together, our results show that the ubc-25-mediated pathway acts within a complex network that integrates the actions of multiple molecular mechanisms to control cell cycles during development.
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Affiliation(s)
- Sarah H Roy
- Department of Genetics, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire 03755
| | - David V Tobin
- Department of Genetics, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire 03755
| | - Nadin Memar
- Center for Integrated Protein Science Munich (CiPSM), Biocenter, LMU Munich, 82152 Planegg-Martinsried, Germany
| | - Eleanor Beltz
- Department of Genetics, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire 03755
| | - Jenna Holmen
- Department of Genetics, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire 03755
| | - Joseph E Clayton
- Department of Genetics, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire 03755
| | - Daniel J Chiu
- Department of Genetics, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire 03755
| | - Laura D Young
- Department of Genetics, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire 03755
| | - Travis H Green
- Department of Genetics, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire 03755
| | - Isabella Lubin
- Department of Genetics, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire 03755
| | - Yuying Liu
- Department of Genetics, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire 03755
| | - Barbara Conradt
- Center for Integrated Protein Science Munich (CiPSM), Biocenter, LMU Munich, 82152 Planegg-Martinsried, Germany
| | - R Mako Saito
- Department of Genetics, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire 03755 Norris Cotton Cancer Center, Lebanon, New Hampshire 03756
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21
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Schindler AJ, Sherwood DR. Morphogenesis of the caenorhabditis elegans vulva. WILEY INTERDISCIPLINARY REVIEWS-DEVELOPMENTAL BIOLOGY 2014; 2:75-95. [PMID: 23418408 DOI: 10.1002/wdev.87] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Understanding how cells move, change shape, and alter cellular behaviors to form organs, a process termed morphogenesis, is one of the great challenges of developmental biology. Formation of the Caenorhabditis elegans vulva is a powerful, simple, and experimentally accessible model for elucidating how morphogenetic processes produce an organ. In the first step of vulval development, three epithelial precursor cells divide and differentiate to generate 22 cells of 7 different vulval subtypes. The 22 vulval cells then rearrange from a linear array into a tube, with each of the seven cell types undergoing characteristic morphogenetic behaviors that construct the vulva. Vulval morphogenesis entails many of the same cellular activities that underlie organogenesis and tissue formation across species, including invagination, lumen formation, oriented cell divisions, cell–cell adhesion, cell migration, cell fusion, extracellular matrix remodeling, and cell invasion. Studies of vulval development have led to pioneering discoveries in a number of these processes and are beginning to bridge the gap between the pathways that specify cells and their connections to morphogenetic behaviors. The simplicity of the vulva and the experimental tools available in C. elegans will continue to make vulval morphogenesis a powerful paradigm to further our understanding of the largely mysterious mechanisms that build tissues and organs.
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22
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Emerging roles of Cdk8 in cell cycle control. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2013; 1829:916-20. [DOI: 10.1016/j.bbagrm.2013.04.010] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2013] [Revised: 04/22/2013] [Accepted: 04/24/2013] [Indexed: 12/12/2022]
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23
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Abstract
Cells decide to proliferate or remain quiescent using signaling pathways that link information about the cellular environment to the G1 phase of the cell cycle. Progression through G1 phase is controlled by pRB proteins, which function to repress the activity of E2F transcription factors in cells exiting mitosis and in quiescent cells. Phosphorylation of pRB proteins by the G1 cyclin-dependent kinases (CDKs) releases E2F factors, promoting the transition to S phase. CDK activity is primarily regulated by the binding of CDK catalytic subunits to cyclin partners and CDK inhibitors. Consequently, both mitogenic and antiproliferative signals exert their effects on cell proliferation through the transcriptional regulation and ubiquitin-dependent degradation of cyclins and CDK inhibitors.
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Affiliation(s)
- Robert J Duronio
- Department of Biology and Genetics, University of North Carolina, Chapel Hill, North Carolina 27599, USA.
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24
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Nusser-Stein S, Beyer A, Rimann I, Adamczyk M, Piterman N, Hajnal A, Fisher J. Cell-cycle regulation of NOTCH signaling during C. elegans vulval development. Mol Syst Biol 2013; 8:618. [PMID: 23047528 PMCID: PMC3501274 DOI: 10.1038/msb.2012.51] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2012] [Accepted: 09/04/2012] [Indexed: 01/05/2023] Open
Abstract
C. elegans vulval development is one of the best-characterized systems to study cell fate specification during organogenesis. The detailed knowledge of the signaling pathways determining vulval precursor cell (VPC) fates permitted us to create a computational model based on the antagonistic interactions between the epidermal growth factor receptor (EGFR)/RAS/MAPK and the NOTCH pathways that specify the primary and secondary fates, respectively. A key notion of our model is called bounded asynchrony, which predicts that a limited degree of asynchrony in the progression of the VPCs is necessary to break their equivalence. While searching for a molecular mechanism underlying bounded asynchrony, we discovered that the termination of NOTCH signaling is tightly linked to cell-cycle progression. When single VPCs were arrested in the G1 phase, intracellular NOTCH failed to be degraded, resulting in a mixed primary/secondary cell fate. Moreover, the G1 cyclins CYD-1 and CYE-1 stabilize NOTCH, while the G2 cyclin CYB-3 promotes NOTCH degradation. Our findings reveal a synchronization mechanism that coordinates NOTCH signaling with cell-cycle progression and thus permits the formation of a stable cell fate pattern.
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25
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Chen Y, Dong Y, Sandiford S, Dimopoulos G. Transcriptional mediators Kto and Skd are involved in the regulation of the IMD pathway and anti-Plasmodium defense in Anopheles gambiae. PLoS One 2012; 7:e45580. [PMID: 23049816 PMCID: PMC3458077 DOI: 10.1371/journal.pone.0045580] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2012] [Accepted: 08/22/2012] [Indexed: 01/30/2023] Open
Abstract
The malarial parasite Plasmodium must complete a complex lifecycle in its Anopheles mosquito host, the main vector for Plasmodium. The mosquito resists infection with the human malarial parasite P. falciparum by engaging the NF-κB immune signaling pathway, IMD. Here we show that the conserved transcriptional mediators Kto and Skd are involved in the regulation of the mosquito IMD pathway. RNAi-mediated depletion of Kto and Skd in the Anopheles gambiae cell line L5-3 resulted in a decrease in the transcript abundance of Cec1, which is controlled by the IMD pathway. Silencing the two genes also resulted in an increased susceptibility of the mosquito to bacterial and Plasmodium falciparum infection, but not to infection with the rodent malaria parasite P. berghei. We also showed that Kto and Skd are not transcriptional co-activators of Rel2 or other key factors of the IMD pathway; however, they participate in the regulation of the IMD pathway, which is crucial for the mosquito’s defense against P. falciparum.
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Affiliation(s)
- Yang Chen
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Yuemei Dong
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Simone Sandiford
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - George Dimopoulos
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland, United States of America
- * E-mail:
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26
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Verdoodt F, Willems M, Mouton S, De Mulder K, Bert W, Houthoofd W, Smith J, Ladurner P. Stem cells propagate their DNA by random segregation in the flatworm Macrostomum lignano. PLoS One 2012; 7:e30227. [PMID: 22276162 PMCID: PMC3261893 DOI: 10.1371/journal.pone.0030227] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2010] [Accepted: 12/14/2011] [Indexed: 01/17/2023] Open
Abstract
Adult stem cells are proposed to have acquired special features to prevent an accumulation of DNA-replication errors. Two such mechanisms, frequently suggested to serve this goal are cellular quiescence, and non-random segregation of DNA strands during stem cell division, a theory designated as the immortal strand hypothesis. To date, it has been difficult to test the in vivo relevance of both mechanisms in stem cell systems. It has been shown that in the flatworm Macrostomum lignano pluripotent stem cells (neoblasts) are present in adult animals. We sought to address by which means M. lignano neoblasts protect themselves against the accumulation of genomic errors, by studying the exact mode of DNA-segregation during their division. In this study, we demonstrated four lines of in vivo evidence in favor of cellular quiescence. Firstly, performing BrdU pulse-chase experiments, we localized 'Label-Retaining Cells' (LRCs). Secondly, EDU pulse-chase combined with Vasa labeling demonstrated the presence of neoblasts among the LRCs, while the majority of LRCs were differentiated cells. We showed that stem cells lose their label at a slow rate, indicating cellular quiescence. Thirdly, CldU/IdU- double labeling studies confirmed that label-retaining stem cells showed low proliferative activity. Finally, the use of the actin inhibitor, cytochalasin D, unequivocally demonstrated random segregation of DNA-strands in LRCs. Altogether, our data unambiguously demonstrated that the majority of neoblasts in M. lignano distribute their DNA randomly during cell division, and that label-retention is a direct result of cellular quiescence, rather than a sign of co-segregation of labeled strands.
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Affiliation(s)
- Freija Verdoodt
- Nematology Unit, Department of Biology, Ghent University, Ghent, Belgium
| | - Maxime Willems
- Laboratory of Pharmaceutical Technology, Department of Pharmaceutics, Ghent University, Ghent, Belgium
| | - Stijn Mouton
- Hubrecht Institute, Royal Netherlands Academy of Arts and Sciences and University Medical Center Utrecht, Utrecht, The Netherlands
| | - Katrien De Mulder
- Department of Clinical Chemistry, Microbiology, and Immunology, Ghent University, Ghent, Belgium
| | - Wim Bert
- Nematology Unit, Department of Biology, Ghent University, Ghent, Belgium
| | - Wouter Houthoofd
- Nematology Unit, Department of Biology, Ghent University, Ghent, Belgium
| | - Julian Smith
- Department of Biology, Winthrop University, Rock Hill, South Carolina, United States of America
| | - Peter Ladurner
- Institute of Zoology and CMBI, University of Innsbruck, Innsbruck, Austria
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27
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Roy SH, Clayton JE, Holmen J, Beltz E, Saito RM. Control of Cdc14 activity coordinates cell cycle and development in Caenorhabditis elegans. Mech Dev 2011; 128:317-26. [PMID: 21723944 PMCID: PMC3199030 DOI: 10.1016/j.mod.2011.06.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2011] [Revised: 06/15/2011] [Accepted: 06/16/2011] [Indexed: 02/08/2023]
Abstract
Much of our understanding of the function and regulation of the Cdc14 family of dual-specificity phosphatases originates from studies in yeasts. In these unicellular organisms Cdc14 is an important regulator of M-phase events. In contrast, the Caenorhabditis elegans homolog, cdc-14, is not necessary for mitosis, rather it is crucial for G(1)/S regulation to establish developmental cell-cycle quiescence. Despite the importance of integrating cdc-14 regulation with development, the mechanisms by which this coordination occurs are largely unknown. Here, we demonstrate that several processes conspire to focus the activity of cdc-14. First, the cdc-14 locus can produce at least six protein variants through alternative splicing. We find that a single form, CDC-14C, is the key variant acting during vulva development. Second, CDC-14C expression is limited to a subset of cells, including vulva precursors, through post-transcriptional regulation. Lastly, the CDC-14C subcellular location, and thus its potential interactions with other regulatory proteins, is regulated by nucleocytoplasmic shuttling. We find that the active export of CDC-14C from the nucleus during interphase is dependent on members of the Cyclin D and Crm1 families. We propose that these mechanisms collaborate to restrict the activity of cdc-14 as central components of an evolutionarily conserved regulatory network to coordinate cell-cycle progression with development.
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Affiliation(s)
| | | | - Jenna Holmen
- Department of Genetics, Dartmouth Medical School, Hanover, NH 03755
| | - Eleanor Beltz
- Department of Genetics, Dartmouth Medical School, Hanover, NH 03755
| | - R. Mako Saito
- Corresponding author. Tel.: (603) 650-1110; fax: (603) 650-1188, (R.M. Saito)
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28
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Hashimoto H, Enomoto T, Kumano G, Nishida H. The transcription factor FoxB mediates temporal loss of cellular competence for notochord induction in ascidian embryos. Development 2011; 138:2591-600. [DOI: 10.1242/dev.053082] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
In embryos of the ascidian Halocynthia roretzi, the competence of isolated presumptive notochord blastomeres to respond to fibroblast growth factor (FGF) for induction of the primary notochord decays by 1 hour after cleavage from the 32- to 64-cell stage. This study analyzes the molecular mechanisms responsible for this loss of competence and provides evidence for a novel mechanism. A forkhead family transcription factor, FoxB, plays a role in competence decay by preventing the induction of notochord-specific Brachyury (Bra) gene expression by the FGF/MAPK signaling pathway. Unlike the mechanisms reported previously in other animals, no component in the FGF signal transduction cascade appeared to be lost or inactivated at the time of competence loss. Knockdown of FoxB functions allowed the isolated cells to retain their competence for a longer period, and to respond to FGF with expression of Bra beyond the stage at which competence was normally lost. FoxB acts as a transcription repressor by directly binding to the cis-regulatory element of the Bra gene. Our results suggest that FoxB prevents ectopic induction of the notochord fate within the cells that assume a default nerve cord fate, after the stage when notochord induction has been completed. The merit of this system is that embryos can use the same FGF signaling cascade again for another purpose in the same cell lineage at later stages by keeping the signaling cascade itself available. Temporally and spatially regulated FoxB expression in nerve cord cells was promoted by the ZicN transcription factor and absence of FGF/MAPK signaling.
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Affiliation(s)
- Hidehiko Hashimoto
- Department of Biological Sciences, Graduate School of Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka 560-0043, Osaka, Japan
| | - Takashi Enomoto
- Department of Biological Sciences, Graduate School of Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka 560-0043, Osaka, Japan
| | - Gaku Kumano
- Department of Biological Sciences, Graduate School of Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka 560-0043, Osaka, Japan
| | - Hiroki Nishida
- Department of Biological Sciences, Graduate School of Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka 560-0043, Osaka, Japan
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29
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Fujikawa T, Takatori N, Kuwajima M, Kim GJ, Nishida H. Tissue-specific regulation of the number of cell division rounds by inductive cell interaction and transcription factors during ascidian embryogenesis. Dev Biol 2011; 355:313-23. [PMID: 21575623 DOI: 10.1016/j.ydbio.2011.04.033] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2010] [Revised: 04/06/2011] [Accepted: 04/28/2011] [Indexed: 11/16/2022]
Abstract
Mechanisms that regulate the number of cells constituting the body have remained largely elusive. We approached this issue in the ascidian, Halocynthia roretzi, which develops into a tadpole larva with a small number of cells. The embryonic cells divide 11 times on average from fertilization to hatching. The number of cell division rounds varies among tissue types. For example, notochord cells divide 9 times and give rise to large postmitotic cells in the tadpole. The number of cell division rounds in partial embryos derived from tissue-precursor blastomeres isolated at the 64-cell stage also varied between tissues and coincided with their counterparts in the intact whole embryos to some extent, suggesting tissue-autonomous regulation of cell division. Manipulation of cell fates in notochord, nerve cord, muscle, and mesenchyme lineage cells by inhibition or ectopic activation of the inductive FGF signal changed the number of cell divisions according to the altered fate. Knockdown and missexpression of Brachyury (Bra), an FGF-induced notochord-specific key transcription factor for notochord differentiation, indicated that Bra is also responsible for regulation of the number of cell division rounds, suggesting that Bra activates a putative mechanism to halt cell division at a specific stage. The outcome of precocious expression of Bra suggests that the mechanism involves a putative developmental clock that is likely shared in blastomeres other than those of notochord and functions to terminate cell division at three rounds after the 64-cell stage. Precocious expression of Bra has no effect on progression of the developmental clock itself.
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Affiliation(s)
- Tetsuya Fujikawa
- Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan
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30
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Ito J, Sono T, Tasaka M, Furutani M. MACCHI-BOU 2 is required for early embryo patterning and cotyledon organogenesis in Arabidopsis. PLANT & CELL PHYSIOLOGY 2011; 52:539-552. [PMID: 21257604 DOI: 10.1093/pcp/pcr013] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The phytohormone auxin is a key regulator of organogenesis in plants and is distributed asymmetrically via polar transport. However, the precise mechanisms underlying auxin-mediated organogenesis remain elusive. Here, we have analyzed the macchi-bou 2 (mab2) mutant identified in a pinoid (pid) enhancer mutant screen. Seedlings homozygous for either mab2 or pid showed only mild phenotypic effects on cotyledon positions and/or numbers. In contrast, mab2 pid double mutant seedlings completely lacked cotyledons, indicating a synergistic interaction. We found that mab2 homozygous embryos had defective patterns of cell division and showed aberrant cotyledon organogenesis. Further analysis revealed that the mab2 mutation affected auxin response but not auxin transport in the embryos, suggesting the involvement of MAB2 in auxin response during embryogenesis. MAB2 encodes an Arabidopsis ortholog of MED13, a putative regulatory module component of the Mediator complex. Mediator is a multicomponent complex that is evolutionarily conserved in eukaryotes and its regulatory module associates with Mediator to control the interaction of Mediator and RNA polymerase II. MAB2 interacts with a regulatory module component in yeast cells. Taken together, our data suggest that MAB2 plays a crucial role in embryo patterning and cotyledon organogenesis, possibly through modulating expression of specific genes such as auxin-responsive genes.
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Affiliation(s)
- Jun Ito
- Graduate School of Biological Sciences, Nara Institute of Science and Technology, 8916-5, Takayama, Ikoma, Nara, 630-0101 Japan
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31
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Gaudet J, McGhee JD. Recent advances in understanding the molecular mechanisms regulating C. elegans transcription. Dev Dyn 2010; 239:1388-404. [PMID: 20175193 DOI: 10.1002/dvdy.22246] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
We review recent studies that have advanced our understanding of the molecular mechanisms regulating transcription in the nematode C. elegans. Topics covered include: (i) general properties of C. elegans promoters; (ii) transcription factors and transcription factor combinations involved in cell fate specification and cell differentiation; (iii) new roles for general transcription factors; (iv) nucleosome positioning in C. elegans "chromatin"; and (v) some characteristics of histone variants and histone modifications and their possible roles in controlling C. elegans transcription.
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Affiliation(s)
- Jeb Gaudet
- Department of Biochemistry and Molecular Biology, Alberta Children's Hospital Research Institute for Child and Maternal Health, University of Calgary, Calgary, Alberta, Canada
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32
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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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33
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Lant B, Storey KB. An overview of stress response and hypometabolic strategies in Caenorhabditis elegans: conserved and contrasting signals with the mammalian system. Int J Biol Sci 2010; 6:9-50. [PMID: 20087441 PMCID: PMC2808051 DOI: 10.7150/ijbs.6.9] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2009] [Accepted: 11/25/2009] [Indexed: 12/21/2022] Open
Abstract
Studies of the molecular mechanisms that are involved in stress responses (environmental or physiological) have long been used to make links to disease states in humans. The nematode model organism, Caenorhabditis elegans, undergoes a state of hypometabolism called the 'dauer' stage. This period of developmental arrest is characterized by a significant reduction in metabolic rate, triggered by ambient temperature increase and restricted oxygen/ nutrients. C. elegans employs a number of signal transduction cascades in order to adapt to these unfavourable conditions and survive for long times with severely reduced energy production. The suppression of cellular metabolism, providing energetic homeostasis, is critical to the survival of nematodes through the dauer period. This transition displays molecular mechanisms that are fundamental to control of hypometabolism across the animal kingdom. In general, mammalian systems are highly inelastic to environmental stresses (such as extreme temperatures and low oxygen), however, there is a great deal of conservation between the signal transduction pathways of nematodes and mammals. Along with conserving many of the protein targets in the stress response, many of the critical regulatory mechanisms are maintained, and often differ only in their level of expression. Hence, the C. elegans model outlines a framework of critical molecular mechanisms that may be employed in the future as therapeutic targets for addressing disease states.
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Affiliation(s)
| | - Kenneth B. Storey
- Institute of Biochemistry, Carleton University, Ottawa, Ont., Canada
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34
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Buck SH, Chiu D, Saito RM. The cyclin-dependent kinase inhibitors, cki-1 and cki-2, act in overlapping but distinct pathways to control cell cycle quiescence during C. elegans development. Cell Cycle 2009; 8:2613-20. [PMID: 19597327 DOI: 10.4161/cc.8.16.9354] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Cyclin-dependent kinase inhibitors (CKIs) are major contributors to the decision to enter or exit the cell cycle. The Caenorhabditis elegans genome encodes two CKIs belonging to the Cip/Kip family, cki-1 and cki-2. cki-1 has been shown to act as a canonical negative regulator of cell cycle entry, while the role of cki-2 remains unclear. We identified cki-2 in a genome-wide RNAi screen to reveal genes essential for developmental cell cycle quiescence. Examination of cki-2 knockout animals revealed extra rounds of cell divisions, verifying a role in establishing or maintaining the temporary cell cycle arrest. Despite the overlapping defects, the pathways mediated by cki-1 and cki-2 are discrete since the extra cell phenotype conferred by a putative cki-2(null) mutation is enhanced upon additional loss of cki-1 activity. Moreover, the extra cell division defect of cki-2 is not increased with the additional loss of lin-35 Rb, as is seen with cki-1. Thus, both cki-1 and cki-2 mediate cell cycle quiescence, but our genetic and phenotypic analyses demonstrate that they act within distinct pathways to exert control over the cell cycle machinery.
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Affiliation(s)
- Sarah H Buck
- Department of Genetics, Dartmouth Medical School, Hanover, NH 03755, USA
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35
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Pygopus activates Wingless target gene transcription through the mediator complex subunits Med12 and Med13. Proc Natl Acad Sci U S A 2008; 105:6644-9. [PMID: 18451032 DOI: 10.1073/pnas.0709749105] [Citation(s) in RCA: 113] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Wnt target gene transcription is mediated by nuclear translocation of stabilized beta-catenin, which binds to TCF and recruits Pygopus, a cofactor with an unknown mechanism of action. The mediator complex is essential for the transcription of RNA polymerase II-dependent genes; it associates with an accessory subcomplex consisting of the Med12, Med13, Cdk8, and Cyclin C subunits. We show here that the Med12 and Med13 subunits of the Drosophila mediator complex, encoded by kohtalo and skuld, are essential for the transcription of Wingless target genes. kohtalo and skuld act downstream of beta-catenin stabilization both in vivo and in cell culture. They are required for transcriptional activation by the N-terminal domain of Pygopus, and their physical interaction with Pygopus depends on this domain. We propose that Pygopus promotes Wnt target gene transcription by recruiting the mediator complex through interactions with Med12 and Med13.
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