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Schiano C, Luongo L, Maione S, Napoli C. Mediator complex in neurological disease. Life Sci 2023; 329:121986. [PMID: 37516429 DOI: 10.1016/j.lfs.2023.121986] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2023] [Revised: 07/18/2023] [Accepted: 07/26/2023] [Indexed: 07/31/2023]
Abstract
Neurological diseases, including traumatic brain injuries, stroke (haemorrhagic and ischemic), and inherent neurodegenerative diseases cause acquired disability in humans, representing a leading cause of death worldwide. The Mediator complex (MED) is a large, evolutionarily conserved multiprotein that facilities the interaction between transcription factors and RNA Polymerase II in eukaryotes. Some MED subunits have been found altered in the brain, although their specific functions in neurodegenerative diseases are not fully understood. Mutations in MED subunits were associated with a wide range of genetic diseases for MED12, MED13, MED13L, MED20, MED23, MED25, and CDK8 genes. In addition, MED12 and MED23 were deregulated in the Alzheimer's Disease. Interestingly, most of the genomic mutations have been found in the subunits of the kinase module. To date, there is only one evidence on MED1 involvement in post-stroke cognitive deficits. Although the underlying neurodegenerative disorders may be different, we are confident that the signal cascades of the biological-cognitive mechanisms of brain adaptation, which begin after brain deterioration, may also differ. Here, we analysed relevant studies in English published up to June 2023. They were identified through a search of electronic databases including PubMed, Medline, EMBASE and Scopus, including search terms such as "Mediator complex", "neurological disease", "brains". Thematic content analysis was conducted to collect and summarize all studies demonstrating MED alteration to understand the role of this central transcriptional regulatory complex in the brain. Improved and deeper knowledge of the regulatory mechanisms in neurological diseases can increase the ability of physicians to predict onset and progression, thereby improving diagnostic care and providing appropriate treatment decisions.
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Affiliation(s)
- Concetta Schiano
- Department of Advanced Medical and Surgical Sciences (DAMSS), University of Campania "Luigi Vanvitelli", Italy.
| | - Livio Luongo
- Department of Experimental Medicine, University of Campania "Luigi Vanvitelli", Italy; IRCSS, Neuromed, Pozzilli, Italy
| | - Sabatino Maione
- Department of Experimental Medicine, University of Campania "Luigi Vanvitelli", Italy; IRCSS, Neuromed, Pozzilli, Italy
| | - Claudio Napoli
- Department of Advanced Medical and Surgical Sciences (DAMSS), University of Campania "Luigi Vanvitelli", Italy; Clinical Department of Internal Medicine and Specialistic Units, Division of Clinical Immunology and Immunohematology, Transfusion Medicine, and Transplant Immunology (SIMT), Regional Reference Laboratory of Transplant Immunology (LIT), Azienda Universitaria Policlinico (AOU), Italy
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Athanasouli M, Rödelsperger C. Analysis of repeat elements in the Pristionchus pacificus genome reveals an ancient invasion by horizontally transferred transposons. BMC Genomics 2022; 23:523. [PMID: 35854227 PMCID: PMC9297572 DOI: 10.1186/s12864-022-08731-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2022] [Accepted: 07/01/2022] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Repetitive sequences and mobile elements make up considerable fractions of individual genomes. While transposition events can be detrimental for organismal fitness, repetitive sequences form an enormous reservoir for molecular innovation. In this study, we aim to add repetitive elements to the annotation of the Pristionchus pacificus genome and assess their impact on novel gene formation. RESULTS Different computational approaches define up to 24% of the P. pacificus genome as repetitive sequences. While retroelements are more frequently found at the chromosome arms, DNA transposons are distributed more evenly. We found multiple DNA transposons, as well as LTR and LINE elements with abundant evidence of expression as single-exon transcripts. When testing whether transposons disproportionately contribute towards new gene formation, we found that roughly 10-20% of genes across all age classes overlap transposable elements with the strongest trend being an enrichment of low complexity regions among the oldest genes. Finally, we characterized a horizontal gene transfer of Zisupton elements into diplogastrid nematodes. These DNA transposons invaded nematodes from eukaryotic donor species and experienced a recent burst of activity in the P. pacificus lineage. CONCLUSIONS The comprehensive annotation of repetitive elements in the P. pacificus genome builds a resource for future functional genomic analyses as well as for more detailed investigations of molecular innovations.
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Affiliation(s)
- Marina Athanasouli
- Max Planck Institute for Biology, Department for Integrative Evolutionary Biology, Max-Planck-Ring 9, 72076, Tübingen, Germany
| | - Christian Rödelsperger
- Max Planck Institute for Biology, Department for Integrative Evolutionary Biology, Max-Planck-Ring 9, 72076, Tübingen, Germany.
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Fergin A, Boesch G, Greter NR, Berger S, Hajnal A. Tissue-specific inhibition of protein sumoylation uncovers diverse SUMO functions during C. elegans vulval development. PLoS Genet 2022; 18:e1009978. [PMID: 35666766 PMCID: PMC9203017 DOI: 10.1371/journal.pgen.1009978] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Revised: 06/16/2022] [Accepted: 05/13/2022] [Indexed: 11/18/2022] Open
Abstract
The sumoylation (SUMO) pathway is involved in a variety of processes during C. elegans development, such as gonadal and vulval fate specification, cell cycle progression and maintenance of chromosome structure. The ubiquitous expression and pleiotropic effects have made it difficult to dissect the tissue-specific functions of the SUMO pathway and identify its target proteins. To overcome these challenges, we have established tools to block protein sumoylation and degrade sumoylated target proteins in a tissue-specific and temporally controlled manner. We employed the auxin-inducible protein degradation system (AID) to down-regulate the SUMO E3 ligase GEI-17 or the SUMO ortholog SMO-1, either in the vulval precursor cells (VPCs) or in the gonadal anchor cell (AC). Our results indicate that the SUMO pathway acts in multiple tissues to control different aspects of vulval development, such as AC positioning, basement membrane (BM) breaching, VPC fate specification and morphogenesis. Inhibition of protein sumoylation in the VPCs resulted in abnormal toroid formation and ectopic cell fusions during vulval morphogenesis. In particular, sumoylation of the ETS transcription factor LIN-1 at K169 is necessary for the proper contraction of the ventral vulA toroids. Thus, the SUMO pathway plays several distinct roles throughout vulval development. Many proteins are chemically modified after they have been synthesized. In particular, conjugation with the Small Ubiquitin-like Modifier (SUMO) regulates the functions and activities of a large number of proteins in animal and plant cells. Here, we have used the Nematode Caenorhabditis elegans to study the various effects of SUMO protein modification on organ development. By applying a tissue-specific protein degradation system, we could selectively block the SUMO pathway in different tissues of the animals. We focused on the development of the egg-laying organ as a model, and found that the SUMO pathway acts in multiple tissues to regulate distinct cellular functions. Finally, we show that SUMO modification of one transcription factor, called LIN-1, is necessary for the proper morphogenesis of the organ. Our results indicate that the manifold effects of the SUMO pathway can be attributed to the combined action of a distinct number of SUMO modified proteins acting in different cell types.
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Affiliation(s)
- Aleksandra Fergin
- Department of Molecular Life Sciences, University of Zürich, Zürich, Switzerland
- Molecular Life Science PhD Program, University and ETH Zürich, Zürich, Switzerland
| | - Gabriel Boesch
- Department of Molecular Life Sciences, University of Zürich, Zürich, Switzerland
- Molecular Life Science PhD Program, University and ETH Zürich, Zürich, Switzerland
| | - Nadja R. Greter
- Department of Molecular Life Sciences, University of Zürich, Zürich, Switzerland
- Molecular Life Science PhD Program, University and ETH Zürich, Zürich, Switzerland
| | - Simon Berger
- Department of Molecular Life Sciences, University of Zürich, Zürich, Switzerland
- Molecular Life Science PhD Program, University and ETH Zürich, Zürich, Switzerland
| | - Alex Hajnal
- Department of Molecular Life Sciences, University of Zürich, Zürich, Switzerland
- * E-mail:
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Srivastava S, Kulshreshtha R. Insights into the regulatory role and clinical relevance of mediator subunit, MED12, in human diseases. J Cell Physiol 2020; 236:3163-3177. [PMID: 33174211 DOI: 10.1002/jcp.30099] [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: 05/26/2020] [Revised: 09/15/2020] [Accepted: 09/28/2020] [Indexed: 12/13/2022]
Abstract
Transcriptional dysregulation is central to many diseases including cancer. Mutation or deregulated expression of proteins involved in transcriptional machinery leads to aberrant gene expression that disturbs intricate cellular processes of division and differentiation. The subunits of the mediator complex are master regulators of stimuli-derived transcription and are essential for transcription by RNA polymerase II. MED12 is a part of the CDK8 kinase module of the mediator complex and is essential for kinase assembly and function. Other than its function in activation of the kinase activity of CDK8 mediator, it also brings about transcription repression or activation, in response to several signalling pathways, a function that is independent of its role as a part of kinase assembly. Accumulating evidence suggests that MED12 controls complex transcription programs that are defining in cell fate determination, differentiation, and carcinogenesis. Mutations or differential expression of MED12 manifest in several human disorders and diseases. For instance, MED12 mutations are the gold standard for the diagnosis of several X-linked intellectual disability syndromes. Further, certain MED12 mutations are categorised as driver mutations in carcinogenesis as well. This is a timely review that provides for the first time a wholesome view on the critical roles and pathways regulated by MED12, its interactions along with the implications of MED12 alterations/mutations in various cancers and nonneoplastic disorders. Based on the preclinical studies, MED12 indeed emerges as an attractive novel therapeutic target for various diseases and intellectual disorders.
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Affiliation(s)
- Srishti Srivastava
- Department of Biochemical Engineering and Biotechnology, Indian Institute of Technology Delhi, New Delhi, India
| | - Ritu Kulshreshtha
- Department of Biochemical Engineering and Biotechnology, Indian Institute of Technology Delhi, New Delhi, India
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The cross-talk between DDR1 and STAT3 promotes the development of hepatocellular carcinoma. Aging (Albany NY) 2020; 12:14391-14405. [PMID: 32716315 PMCID: PMC7425490 DOI: 10.18632/aging.103482] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Accepted: 05/27/2020] [Indexed: 12/16/2022]
Abstract
Objective: To investigate the function of discoidin domain receptor 1 (DDR1) in hepatocellular carcinoma (HCC) and to further clarify the underlying mechanism. Results: DDR1 was significantly increased in HCC tissues and cells, which was related to clinical staging and prognosis of HCC. Upregulation of DDR1 promoted EMT and glutamine metabolism in HCC cells, while loss of DDR1 showed the opposite effects. STAT3 bound with the promoter of DDR1, and facilitated the phosphorylation of STAT3. In turn, activation of STAT3 increased the expression of DDR1. Silencing of STAT3 removed the promoting effect of DDR1 on proliferation, migration and invasion of HCC cells. The in vivo tumor growth assay showed that the cross-talk between DDR1 and STAT3 promoted HCC tumorigenesis. Conclusions: Our research revealed the positive feedback of DDR1 and STAT3 promoted EMT and glutamine metabolism in HCC, which provided some experimental basis for clinical treatment or prevention of HCC. Materials and methods: The mRNA expression of DDR1 was detected by qRT-PCR. CCK8 assay, wound healing assay and transwell assay were used to detect the DDR1/ STAT3 function on proliferation, migration and invasion in HCC cells. Western blot was used to calculate protein level of DDR1, STAT3, epithelial-mesenchymal transition (EMT) related proteins.
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Angeles-Albores D, Sternberg PW. Using Transcriptomes as Mutant Phenotypes Reveals Functional Regions of a Mediator Subunit in Caenorhabditis elegans. Genetics 2018; 210:15-24. [PMID: 30030292 PMCID: PMC6116950 DOI: 10.1534/genetics.118.301133] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2018] [Accepted: 07/05/2018] [Indexed: 11/18/2022] Open
Abstract
Although transcriptomes have recently been used as phenotypes with which to perform epistasis analyses, they are not yet used to study intragenic function/structure relationships. We developed a theoretical framework to study allelic series using transcriptomic phenotypes. As a proof-of-concept, we apply our methods to an allelic series of dpy-22, a highly pleiotropic Caenorhabditis elegans gene orthologous to the human gene MED12, which encodes a subunit of the Mediator complex. Our methods identify functional units within dpy-22 that modulate Mediator activity upon various genetic programs, including the Wnt and Ras modules.
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Affiliation(s)
| | - Paul W Sternberg
- Division of Biology and Biological Engineering, Caltech, Pasadena, California 91125
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Jamaluddin MFB, Nahar P, Tanwar PS. Proteomic Characterization of the Extracellular Matrix of Human Uterine Fibroids. Endocrinology 2018; 159:2656-2669. [PMID: 29788081 DOI: 10.1210/en.2018-00151] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/08/2018] [Accepted: 05/08/2018] [Indexed: 01/04/2023]
Abstract
Uterine leiomyomas (fibroids) are the most common benign tumors that are associated with increased production of extracellular matrix (ECM). Excessive ECM deposition plays a major role in the enlargement and stiffness of these tumors and contributes to clinical symptoms, such as abnormal bleeding and abdominal pain. However, no study so far has explored the global composition of the ECM of fibroids and normal myometrium. In this study, we performed a systematic ECM enrichment procedure and comparative proteomic analyses to profile the ECM composition of genetically annotated different-sized fibroids (small, medium, and large) and adjacent normal myometrium (ANM). Our matrisome analysis identified a combined total of 108, 126, 126, and 130 unique ECM and ECM-associated proteins with a confidence corresponding to a false discovery rate <1% in ANM and in small, medium, and large fibroids, respectively. The majority of fibroid ECM proteins belong to the core matrisome that includes glycoproteins, collagens, and proteoglycans. Considering that the small-sized fibroids represent the initial stages of leiomyogenesis, we highlighted some of the most abundant and important upregulated ECM proteins in small fibroids (i.e., POSTN, TNC, COL3A1, COL24A1, and ASPN). Furthermore, we revealed 30 unique ECM proteins that exist only in fibroids but that are not present in ANM regardless of MED12 mutation. We propose that some of the proteins identified represent potential novel ECM drug targets that may change the paradigm of fibroid treatment.
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Affiliation(s)
- M Fairuz B Jamaluddin
- School of Biomedical Sciences and Pharmacy, University of Newcastle, Callaghan, New South Wales, Australia
| | - Pravin Nahar
- School of Medicine and Public Health, University of Newcastle, Callaghan, New South Wales, Australia
- Department of Maternity and Gynecology, John Hunter Hospital, New Lambton Heights, New South Wales, Australia
| | - Pradeep S Tanwar
- School of Biomedical Sciences and Pharmacy, University of Newcastle, Callaghan, New South Wales, Australia
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8
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Donnio LM, Bidon B, Hashimoto S, May M, Epanchintsev A, Ryan C, Allen W, Hackett A, Gecz J, Skinner C, Stevenson RE, de Brouwer APM, Coutton C, Francannet C, Jouk PS, Schwartz CE, Egly JM. MED12-related XLID disorders are dose-dependent of immediate early genes (IEGs) expression. Hum Mol Genet 2017; 26:2062-2075. [PMID: 28369444 DOI: 10.1093/hmg/ddx099] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2017] [Accepted: 03/08/2017] [Indexed: 11/13/2022] Open
Abstract
Mediator occupies a key role in protein coding genes expression in mediating the contacts between gene specific factors and the basal transcription machinery but little is known regarding the role of each Mediator subunits. Mutations in MED12 are linked with a broad spectrum of genetic disorders with X-linked intellectual disability that are difficult to range as Lujan, Opitz-Kaveggia or Ohdo syndromes. Here, we investigated several MED12 patients mutations (p.R206Q, p.N898D, p.R961W, p.N1007S, p.R1148H, p.S1165P and p.R1295H) and show that each MED12 mutations cause specific expression patterns of JUN, FOS and EGR1 immediate early genes (IEGs), reflected by the presence or absence of MED12 containing complex at their respective promoters. Moreover, the effect of MED12 mutations has cell-type specificity on IEG expression. As a consequence, the expression of late responsive genes such as the matrix metalloproteinase-3 and the RE1 silencing transcription factor implicated respectively in neural plasticity and the specific expression of neuronal genes is disturbed as documented for MED12/p.R1295H mutation. In such case, JUN and FOS failed to be properly recruited at their AP1-binding site. Our results suggest that the differences between MED12-related phenotypes are essentially the result of distinct IEGs expression patterns, the later ones depending on the accurate formation of the transcription initiation complex. This might challenge clinicians to rethink the traditional syndromes boundaries and to include genetic criterion in patients' diagnostic.
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Affiliation(s)
- Lise-Marie Donnio
- Department of Functional Genomics and Cancer biology, IGBMC, CNRS/INSERM/Université de Strasbourg, 67404 Illkirch-Graffenstaden, France
| | - Baptiste Bidon
- Department of Functional Genomics and Cancer biology, IGBMC, CNRS/INSERM/Université de Strasbourg, 67404 Illkirch-Graffenstaden, France
| | - Satoru Hashimoto
- Department of Functional Genomics and Cancer biology, IGBMC, CNRS/INSERM/Université de Strasbourg, 67404 Illkirch-Graffenstaden, France.,Department of Clinical Pharmacology and Therapeutics Oita University Faculty of Medicine, Yufu city, Oita 879-5593, Japan
| | - Melanie May
- Greenwood Genetic Center, Greenwood, SC 29649, USA
| | - Alexey Epanchintsev
- Department of Functional Genomics and Cancer biology, IGBMC, CNRS/INSERM/Université de Strasbourg, 67404 Illkirch-Graffenstaden, France
| | - Colm Ryan
- Department of Functional Genomics and Cancer biology, IGBMC, CNRS/INSERM/Université de Strasbourg, 67404 Illkirch-Graffenstaden, France
| | | | | | - Jozef Gecz
- School of Medicine, and the Robinson Research Institute, The University of Adelaide, and South Australian Health and Medical Research Institute, Adelaide, SA 5000, Australia
| | | | | | - Arjan P M de Brouwer
- Department of Human Genetics, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, 6525?HP, The Netherlands
| | - Charles Coutton
- Département de Génétique et Procréation, Centre Hospitalier-Universitaire, Institut Albert Bonniot, CNRS/INSERM/Université Grenoble Alpes, 38000 Grenoble, France
| | - Christine Francannet
- Service de Génétique Médicale, Centre Hospitalier-Universitaire, 63003 Clermont-Ferrand, France
| | - Pierre-Simon Jouk
- Département de Génétique et Procréation, Centre Hospitalier-Universitaire, Institut Albert Bonniot, CNRS/INSERM/Université Grenoble Alpes, 38000 Grenoble, France
| | | | - Jean-Marc Egly
- Department of Functional Genomics and Cancer biology, IGBMC, CNRS/INSERM/Université de Strasbourg, 67404 Illkirch-Graffenstaden, France
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9
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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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Flibotte S, Kim BR, Van de Laar E, Brown L, Moghal N. The SWI/SNF chromatin remodeling complex exerts both negative and positive control over LET-23/EGFR-dependent vulval induction in Caenorhabditis elegans. Dev Biol 2016; 415:46-63. [PMID: 27207389 DOI: 10.1016/j.ydbio.2016.05.009] [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: 10/14/2015] [Revised: 05/05/2016] [Accepted: 05/09/2016] [Indexed: 11/19/2022]
Abstract
Signaling by the epidermal growth factor receptor (EGFR) generates diverse developmental patterns. This requires precise control over the location and intensity of signaling. Elucidation of these regulatory mechanisms is important for understanding development and disease pathogenesis. In Caenorhabditis elegans, LIN-3/EGF induces vulval formation in the mid-body, which requires LET-23/EGFR activation only in P6.p, the vulval progenitor nearest the LIN-3 source. To identify mechanisms regulating this signaling pattern, we screened for mutations that cooperate with a let-23 gain-of-function allele to cause ectopic vulval induction. Here, we describe a dominant gain-of-function mutation in swsn-4, a component of SWI/SNF chromatin remodeling complexes. Loss-of-function mutations in multiple SWI/SNF components reveal that weak reduction in SWI/SNF activity causes ectopic vulval induction, while stronger reduction prevents adoption of vulval fates, a phenomenon also observed with increasing loss of LET-23 activity. High levels of LET-23 expression in P6.p are thought to locally sequester LIN-3, thereby preventing ectopic vulval induction, with slight reductions in its expression interfering with LIN-3 sequestration, but not vulval fate signaling. We find that SWI/SNF positively regulates LET-23 expression in P6.p descendants, providing an explanation for the similarities between let-23 and SWI/SNF mutant phenotypes. However, SWI/SNF regulation of LET-23 expression is cell-specific, with SWI/SNF repressing its expression in the ALA neuron. The swsn-4 gain-of-function mutation affects the PTH domain, and provides the first evidence that its auto-inhibitory function in yeast Sth1p is conserved in metazoan chromatin remodelers. Finally, our work supports broad use of SWI/SNF in regulating EGFR signaling during development, and suggests that dominant SWI/SNF mutations in certain human congenital anomaly syndromes may be gain-of-functions.
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Affiliation(s)
- Stephane Flibotte
- Department of Zoology, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4.
| | - Bo Ram Kim
- Princess Margaret Cancer Centre/University Health Network, Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada M5G 1L7.
| | - Emily Van de Laar
- Princess Margaret Cancer Centre/University Health Network, Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada M5G 1L7.
| | - Louise Brown
- Samuel Lunenfeld Research Institute of Mount Sinai Hospital, Toronto, Ontario, Canada M5G 1X5.
| | - Nadeem Moghal
- Princess Margaret Cancer Centre/University Health Network, Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada M5G 1L7.
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Kim NH, Livi CB, Yew PR, Boyer TG. Mediator subunit Med12 contributes to the maintenance of neural stem cell identity. BMC DEVELOPMENTAL BIOLOGY 2016; 16:17. [PMID: 27188461 PMCID: PMC4869265 DOI: 10.1186/s12861-016-0114-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/06/2016] [Accepted: 05/08/2016] [Indexed: 12/22/2022]
Abstract
BACKGROUND The RNA polymerase II transcriptional Mediator subunit Med12 is broadly implicated in vertebrate brain development, and genetic variation in human MED12 is associated with X-linked intellectual disability and neuropsychiatric disorders. Although prior studies have begun to elaborate the functional contribution of Med12 within key neurodevelopmental pathways, a more complete description of Med12 function in the developing nervous system, including the specific biological networks and cellular processes under its regulatory influence, remains to be established. Herein, we sought to clarify the global contribution of Med12 to neural stem cell (NSC) biology through unbiased transcriptome profiling of mouse embryonic stem (ES) cell-derived NSCs following RNAi-mediated Med12 depletion. RESULTS A total of 240 genes (177 up, 73 down) were differentially expressed in Med12-knockdown versus control mouse NS-5 (mNS-5) NSCs. Gene set enrichment analysis revealed Med12 to be prominently linked with "cell-to-cell interaction" and "cell cycle" networks, and subsequent functional studies confirmed these associations. Targeted depletion of Med12 led to enhanced NSC adhesion and upregulation of cell adhesion genes, including Syndecan 2 (Sdc2). Concomitant depletion of both Sdc2 and Med12 reversed enhanced cell adhesion triggered by Med12 knockdown alone, confirming that Med12 negatively regulates NSC cell adhesion by suppressing the expression of cell adhesion molecules. Med12-mediated suppression of NSC adhesion is a dynamically regulated process in vitro, enforced in self-renewing NSCs and alleviated during the course of neuronal differentiation. Accordingly, Med12 depletion enhanced adhesion and prolonged survival of mNS-5 NSCs induced to differentiate on gelatin, effects that were bypassed completely by growth on laminin. On the other hand, Med12 depletion in mNS-5 NSCs led to reduced expression of G1/S phase cell cycle regulators and a concordant G1/S phase cell cycle block without evidence of apoptosis, resulting in a severe proliferation defect. CONCLUSIONS Med12 contributes to the maintenance of NSC identity through a functionally bipartite role in suppression and activation of gene expression programs dedicated to cell adhesion and G1/S phase cell cycle progression, respectively. Med12 may thus contribute to the regulatory apparatus that controls the balance between NSC self-renewal and differentiation, with important implications for MED12-linked neurodevelopmental disorders.
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Affiliation(s)
- Nam Hee Kim
- Department of Molecular Medicine and Institute of Biotechnology, The University of Texas Health Science Center at San Antonio, San Antonio, TX, 78229-3900, USA
| | - Carolina B Livi
- Department of Molecular Medicine and Institute of Biotechnology, The University of Texas Health Science Center at San Antonio, San Antonio, TX, 78229-3900, USA
- Agilent Technologies, Portland, OR, 97224-7154, USA
| | - P Renee Yew
- Department of Molecular Medicine and Institute of Biotechnology, The University of Texas Health Science Center at San Antonio, San Antonio, TX, 78229-3900, USA
| | - Thomas G Boyer
- Department of Molecular Medicine and Institute of Biotechnology, The University of Texas Health Science Center at San Antonio, San Antonio, TX, 78229-3900, USA.
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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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Clark AD, Oldenbroek M, Boyer TG. Mediator kinase module and human tumorigenesis. Crit Rev Biochem Mol Biol 2015; 50:393-426. [PMID: 26182352 DOI: 10.3109/10409238.2015.1064854] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Mediator is a conserved multi-subunit signal processor through which regulatory informatiosn conveyed by gene-specific transcription factors is transduced to RNA Polymerase II (Pol II). In humans, MED13, MED12, CDK8 and Cyclin C (CycC) comprise a four-subunit "kinase" module that exists in variable association with a 26-subunit Mediator core. Genetic and biochemical studies have established the Mediator kinase module as a major ingress of developmental and oncogenic signaling through Mediator, and much of its function in signal-dependent gene regulation derives from its resident CDK8 kinase activity. For example, CDK8-targeted substrate phosphorylation impacts transcription factor half-life, Pol II activity and chromatin chemistry and functional status. Recent structural and biochemical studies have revealed a precise network of physical and functional subunit interactions required for proper kinase module activity. Accordingly, pathologic change in this activity through altered expression or mutation of constituent kinase module subunits can have profound consequences for altered signaling and tumor formation. Herein, we review the structural organization, biological function and oncogenic potential of the Mediator kinase module. We focus principally on tumor-associated alterations in kinase module subunits for which mechanistic relationships as opposed to strictly correlative associations are established. These considerations point to an emerging picture of the Mediator kinase module as an oncogenic unit, one in which pathogenic activation/deactivation through component change drives tumor formation through perturbation of signal-dependent gene regulation. It follows that therapeutic strategies to combat CDK8-driven tumors will involve targeted modulation of CDK8 activity or pharmacologic manipulation of dysregulated CDK8-dependent signaling pathways.
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Affiliation(s)
- Alison D Clark
- a Department of Molecular Medicine , Institute of Biotechnology, University of Texas Health Science Center at San Antonio , San Antonio , TX , USA
| | - Marieke Oldenbroek
- a Department of Molecular Medicine , Institute of Biotechnology, University of Texas Health Science Center at San Antonio , San Antonio , TX , USA
| | - Thomas G Boyer
- a Department of Molecular Medicine , Institute of Biotechnology, University of Texas Health Science Center at San Antonio , San Antonio , TX , USA
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Wang H, Ye J, Qian H, Zhou R, Jiang J, Ye L. High-resolution melting analysis of MED12 mutations in uterine leiomyomas in Chinese patients. Genet Test Mol Biomarkers 2015; 19:162-6. [PMID: 25615570 PMCID: PMC4361005 DOI: 10.1089/gtmb.2014.0273] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
OBJECTIVES Somatic mutations in mediator complex subunit 12 (MED12) have emerged as a critical genetic change in the development of uterine leiomyomas. Studies, however, have focused largely on cohorts consisting of Caucasian patients. In this study, uterine leiomyomas from Chinese patients were examined for MED12 mutations. In addition, polymerase chain reaction (PCR)-based high-resolution melting analysis (HRMA) was compared with direct sequencing as a potentially more sensitive method for the detection of MED12 mutations. METHODS Tissue samples with the pathologies of uterine leiomyoma (n=181) and other endometrial diseases (n=157) were collected from Chinese patients at the Taizhou People's Hospital and Taizhou Polytechnic College (Taizhou City, China). Genomic DNA was prepared from all samples. Both PCR-based HRMA and PCR-based direct sequencing were used to detect MED12 mutations. RESULTS PCR-based HRMA and direct sequencing revealed MED12 mutations in 95/181 (52.5%) and 93/181 (51.4%) uterine leiomyomas, respectively. Nearly half of these mutations (46/93) were found in a single codon, codon 131. The coincidence rate between the two methods was 98.9% (179/181) so that no statistically significant difference was evident in the application of the methodologies (χ(2)=0.011, p=0.916). In addition, MED12 mutations were identified in 1/157 (4.17%) case of other endometrial pathologies by both methods. CONCLUSIONS MED12 mutations were closely associated with the development of uterine leiomyomas, as opposed to other uterine pathologies in Chinese patients, and PCR-based HRMA was found to be a reliable method for the detection of MED12 mutations.
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Affiliation(s)
- Hua Wang
- Department of Laboratory Medicine, Taizhou People's Hospital, Taizhou City, China
| | - Jun Ye
- Department of Laboratory Medicine, Taizhou People's Hospital, Taizhou City, China
| | - Hua Qian
- Department of Laboratory Medicine, Taizhou People's Hospital, Taizhou City, China
| | - Ruifang Zhou
- Taizhou Polytechnic College, Taizhou City, China
| | - Jun Jiang
- Taizhou Polytechnic College, Taizhou City, China
| | - Lihua Ye
- Department of Laboratory Medicine, Taizhou People's Hospital, Taizhou City, China
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15
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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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16
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Ackley BD. Wnt-signaling and planar cell polarity genes regulate axon guidance along the anteroposterior axis in C. elegans. Dev Neurobiol 2014; 74:781-96. [PMID: 24214205 PMCID: PMC4167394 DOI: 10.1002/dneu.22146] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2013] [Revised: 09/18/2013] [Accepted: 11/02/2013] [Indexed: 11/10/2022]
Abstract
During the development of the nervous system, neurons encounter signals that inform their outgrowth and polarization. Understanding how these signals combinatorially function to pattern the nervous system is of considerable interest to developmental neurobiologists. The Wnt ligands and their receptors have been well characterized in polarizing cells during asymmetric cell division. The planar cell polarity (PCP) pathway is also critical for cell polarization in the plane of an epithelium. The core set of PCP genes include members of the conserved Wnt-signaling pathway, such as Frizzled and Disheveled, but also the cadherin-domain protein Flamingo. In Drosophila, the Fat and Dachsous cadherins also function in PCP, but in parallel to the core PCP components. C. elegans also have two Fat-like and one Dachsous-like cadherins, at least one of which, cdh-4, contributes to neural development. In C. elegans Wnt ligands and the conserved PCP genes have been shown to regulate a number of different events, including embryonic cell polarity, vulval morphogenesis, and cell migration. As is also observed in vertebrates, the Wnt and PCP genes appear to function to primarily provide information about the anterior to posterior axis of development. Here, we review the recent work describing how mutations in the Wnt and core PCP genes affect axon guidance and synaptogenesis in C. elegans.
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Affiliation(s)
- Brian D Ackley
- Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas, 66045
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17
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Yin JW, Wang G. The Mediator complex: a master coordinator of transcription and cell lineage development. Development 2014; 141:977-87. [PMID: 24550107 DOI: 10.1242/dev.098392] [Citation(s) in RCA: 146] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Mediator is a multiprotein complex that is required for gene transcription by RNA polymerase II. Multiple subunits of the complex show specificity in relaying information from signals and transcription factors to the RNA polymerase II machinery, thus enabling control of the expression of specific genes. Recent studies have also provided novel mechanistic insights into the roles of Mediator in epigenetic regulation, transcriptional elongation, termination, mRNA processing, noncoding RNA activation and super enhancer formation. Based on these specific roles in gene regulation, Mediator has emerged as a master coordinator of development and cell lineage determination. Here, we describe the most recent advances in understanding the mechanisms of Mediator function, with an emphasis on its role during development and disease.
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Affiliation(s)
- Jing-wen Yin
- State Key Laboratory of Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
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18
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Abstract
The Mediator complex is a multi-subunit assembly that appears to be required for regulating expression of most RNA polymerase II (pol II) transcripts, which include protein-coding and most non-coding RNA genes. Mediator and pol II function within the pre-initiation complex (PIC), which consists of Mediator, pol II, TFIIA, TFIIB, TFIID, TFIIE, TFIIF and TFIIH and is approximately 4.0 MDa in size. Mediator serves as a central scaffold within the PIC and helps regulate pol II activity in ways that remain poorly understood. Mediator is also generally targeted by sequence-specific, DNA-binding transcription factors (TFs) that work to control gene expression programs in response to developmental or environmental cues. At a basic level, Mediator functions by relaying signals from TFs directly to the pol II enzyme, thereby facilitating TF-dependent regulation of gene expression. Thus, Mediator is essential for converting biological inputs (communicated by TFs) to physiological responses (via changes in gene expression). In this review, we summarize an expansive body of research on the Mediator complex, with an emphasis on yeast and mammalian complexes. We focus on the basics that underlie Mediator function, such as its structure and subunit composition, and describe its broad regulatory influence on gene expression, ranging from chromatin architecture to transcription initiation and elongation, to mRNA processing. We also describe factors that influence Mediator structure and activity, including TFs, non-coding RNAs and the CDK8 module.
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Affiliation(s)
- Zachary C Poss
- Department of Chemistry and Biochemistry, University of Colorado , Boulder, CO , USA
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19
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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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20
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Steimel A, Suh J, Hussainkhel A, Deheshi S, Grants JM, Zapf R, Moerman DG, Taubert S, Hutter H. The C. elegans CDK8 Mediator module regulates axon guidance decisions in the ventral nerve cord and during dorsal axon navigation. Dev Biol 2013; 377:385-98. [PMID: 23458898 DOI: 10.1016/j.ydbio.2013.02.009] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2012] [Revised: 01/21/2013] [Accepted: 02/14/2013] [Indexed: 11/30/2022]
Abstract
Receptors expressed on the growth cone of outgrowing axons detect cues required for proper navigation. The pathway choices available to an axon are in part defined by the set of guidance receptors present on the growth cone. Regulated expression of receptors and genes controlling the localization and activity of receptors ensures that axons respond only to guidance cues relevant for reaching their targets. In genetic screens for axon guidance mutants, we isolated an allele of let-19/mdt-13, a component of the Mediator, a large ~30 subunit protein complex essential for gene transcription by RNA polymerase II. LET-19/MDT-13 is part of the CDK8 module of the Mediator. By testing other Mediator components, we found that all subunits of the CDK8 module as well as some other Mediator components are required for specific axon navigation decisions in a subset of neurons. Expression profiling demonstrated that let-19/mdt-13 regulates the expression of a large number of genes in interneurons. A mutation in the sax-3 gene, encoding a receptor for the repulsive guidance cue SLT-1, suppresses the commissure navigation defects found in cdk-8 mutants. This suggests that the CDK8 module specifically represses the SAX-3/ROBO pathway to ensure proper commissure navigation.
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Affiliation(s)
- Andreas Steimel
- Department of Biological Sciences, Simon Fraser University, Burnaby, BC, Canada
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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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22
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Imura Y, Kobayashi Y, Yamamoto S, Furutani M, Tasaka M, Abe M, Araki T. CRYPTIC PRECOCIOUS/MED12 is a novel flowering regulator with multiple target steps in Arabidopsis. PLANT & CELL PHYSIOLOGY 2012; 53:287-303. [PMID: 22247249 PMCID: PMC3278046 DOI: 10.1093/pcp/pcs002] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2011] [Accepted: 01/05/2012] [Indexed: 05/22/2023]
Abstract
The proper timing of flowering is of crucial importance for reproductive success of plants. Regulation of flowering is orchestrated by inputs from both environmental and endogenous signals such as daylength, light quality, temperature and hormones, and key flowering regulators construct several parallel and interactive genetic pathways. This integrative regulatory network has been proposed to create robustness as well as plasticity of the regulation. Although knowledge of key genes and their regulation has been accumulated, there still remains much to learn about how they are organized into an integrative regulatory network. Here, we have analyzed the CRYPTIC PRECOCIOUS (CRP) gene for the Arabidopsis counterpart of the MED12 subunit of the Mediator. A novel dominant mutant, crp-1D, which causes up-regulation of SUPPRESSOR OF OVEREXPRESSION OF CONSTANS 1 (SOC1), FRUITFULL (FUL) and APETALA1 (AP1) expression in a FLOWERING LOCUS T (FT)-dependent manner, was identified in an enhancer screen of the early-flowering phenotype of 35S::FT. Genetic and molecular analysis of both crp-1D and crp loss-of-function alleles showed that MED12/CRP is required not only for proper regulation of SOC1, FUL and AP1, but also for up-regulation of FT, TWIN SISTER OF FT (TSF) and FD, and down-regulation of FLOWERING LOCUS C (FLC). These observations suggest that MED12/CRP is a novel flowering regulator with multiple regulatory target steps both upstream and downstream of the key flowering regulators including FT florigen. Our work, taken together with recent studies of other Mediator subunit genes, supports an emerging view that the Mediator plays multiple roles in the regulation of flowering.
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Affiliation(s)
- Yuri Imura
- Graduate School of Biostudies, Kyoto University, Kyoto, 606-8501 Japan
| | - Yasushi Kobayashi
- Graduate School of Science, Kyoto University, Kyoto, 606-8502 Japan
- Department of Molecular Biology, Max Planck Institute for Developmental Biology, D-72076 Tübingen, Germany
| | - Sumiko Yamamoto
- Graduate School of Science, Kyoto University, Kyoto, 606-8502 Japan
- Genome Informatics Laboratory, CIB-DDBJ, National Institute of Genetics, ROIS, Shizuoka, 411-8540 Japan
| | - Masahiko Furutani
- Graduate School of Biological Sciences, Nara Institute of Science and Technology, Nara, 630-0101 Japan
| | - Masao Tasaka
- Graduate School of Biological Sciences, Nara Institute of Science and Technology, Nara, 630-0101 Japan
| | - Mitsutomo Abe
- Graduate School of Biostudies, Kyoto University, Kyoto, 606-8501 Japan
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo, 113-0033 Japan
| | - Takashi Araki
- Graduate School of Biostudies, Kyoto University, Kyoto, 606-8501 Japan
- *Corresponding author: E-mail, ; Fax, +81-75-753-6470.
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Hentges KE. Mediator complex proteins are required for diverse developmental processes. Semin Cell Dev Biol 2011; 22:769-75. [PMID: 21854862 DOI: 10.1016/j.semcdb.2011.07.025] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2011] [Revised: 07/19/2011] [Accepted: 07/20/2011] [Indexed: 12/14/2022]
Abstract
The Mediator complex serves a crucial function in gene regulation, forming a link between gene-specific transcription factors and RNA polymerase II. Most protein-coding genes therefore require Mediator complex activity for transcriptional regulation. Given the essential functions performed by Mediator complex proteins in gene regulation, it is not surprising that mutations in Mediator complex genes disrupt animal and plant development. What is more intriguing is that the phenotypes of individual Mediator complex mutants are distinct from each other, demonstrating that certain developmental processes have a greater requirement for specific Mediator complex genes. Additionally, the range of developmental processes that are altered in Mediator complex mutants is broad, affecting a variety of cell types and physiological systems. Gene expression defects in Mediator complex mutants reveal distinct roles for individual Mediator proteins in transcriptional regulation, suggesting that the deletion of one Mediator complex protein does not interfere with transcription in general, but instead alters the expression of specific target genes. Mediator complex proteins may have diverse roles in different organisms as well, as mutants in the same Mediator gene in different species can display dissimilar phenotypes.
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Affiliation(s)
- Kathryn E Hentges
- Faculty of Life Sciences, University of Manchester, Michael Smith Building, Oxford Road, Manchester M13 9PT, UK.
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24
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Mediator and human disease. Semin Cell Dev Biol 2011; 22:776-87. [PMID: 21840410 DOI: 10.1016/j.semcdb.2011.07.024] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2011] [Revised: 07/25/2011] [Accepted: 07/28/2011] [Indexed: 01/21/2023]
Abstract
Since the identification of a metazoan counterpart to yeast Mediator nearly 15 years ago, a convergent body of biochemical and molecular genetic studies have confirmed their structural and functional relationship as an integrative hub through which regulatory information conveyed by signal activated transcription factors is transduced to RNA polymerase II. Nonetheless, metazoan Mediator complexes have been shaped during evolution by substantive diversification and expansion in both the number and sequence of their constituent subunits, with important implications for the development of multicellular organisms. The appearance of unique interaction surfaces within metazoan Mediator complexes for transcription factors of diverse species-specific origins extended the role of Mediator to include an essential function in coupling developmentally coded signals with precise gene expression output sufficient to specify cell fate and function. The biological significance of Mediator in human development, suggested by genetic studies in lower metazoans, is emphatically illustrated by an expanding list of human pathologies linked to genetic variation or aberrant expression of its individual subunits. Here, we review our current body of knowledge concerning associations between individual Mediator subunits and specific pathological disorders. When established, molecular etiologies underlying genotype-phenotype correlations are addressed, and we anticipate that future progress in this critical area will help identify therapeutic targets across a range of human pathologies.
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25
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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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26
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Heterozygous germline mutations in the CBL tumor-suppressor gene cause a Noonan syndrome-like phenotype. Am J Hum Genet 2010; 87:250-7. [PMID: 20619386 DOI: 10.1016/j.ajhg.2010.06.015] [Citation(s) in RCA: 183] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2010] [Revised: 06/10/2010] [Accepted: 06/16/2010] [Indexed: 02/06/2023] Open
Abstract
RAS signaling plays a key role in controlling appropriate cell responses to extracellular stimuli and participates in early and late developmental processes. Although enhanced flow through this pathway has been established as a major contributor to oncogenesis, recent discoveries have revealed that aberrant RAS activation causes a group of clinically related developmental disorders characterized by facial dysmorphism, a wide spectrum of cardiac disease, reduced growth, variable cognitive deficits, ectodermal and musculoskeletal anomalies, and increased risk for certain malignancies. Here, we report that heterozygous germline mutations in CBL, a tumor-suppressor gene that is mutated in myeloid malignancies and encodes a multivalent adaptor protein with E3 ubiquitin ligase activity, can underlie a phenotype with clinical features fitting or partially overlapping Noonan syndrome (NS), the most common condition of this disease family. Independent CBL mutations were identified in two sporadic cases and two families from among 365 unrelated subjects who had NS or suggestive features and were negative for mutations in previously identified disease genes. Phenotypic heterogeneity and variable expressivity were documented. Mutations were missense changes altering evolutionarily conserved residues located in the RING finger domain or the linker connecting this domain to the N-terminal tyrosine kinase binding domain, a known mutational hot spot in myeloid malignancies. Mutations were shown to affect CBL-mediated receptor ubiquitylation and dysregulate signal flow through RAS. These findings document that germline mutations in CBL alter development to cause a clinically variable condition that resembles NS and that possibly predisposes to malignancies.
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27
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Komatsu H, Chao MY, Larkins-Ford J, Corkins ME, Somers GA, Tucey T, Dionne HM, White JQ, Wani K, Boxem M, Hart AC. OSM-11 facilitates LIN-12 Notch signaling during Caenorhabditis elegans vulval development. PLoS Biol 2008; 6:e196. [PMID: 18700817 PMCID: PMC2504490 DOI: 10.1371/journal.pbio.0060196] [Citation(s) in RCA: 100] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2008] [Accepted: 06/26/2008] [Indexed: 01/06/2023] Open
Abstract
Notch signaling is critical for cell fate decisions during development. Caenorhabditis elegans and vertebrate Notch ligands are more diverse than classical Drosophila Notch ligands, suggesting possible functional complexities. Here, we describe a developmental role in Notch signaling for OSM-11, which has been previously implicated in defecation and osmotic resistance in C. elegans. We find that complete loss of OSM-11 causes defects in vulval precursor cell (VPC) fate specification during vulval development consistent with decreased Notch signaling. OSM-11 is a secreted, diffusible protein that, like previously described C. elegans Delta, Serrate, and LAG-2 (DSL) ligands, can interact with the lineage defective-12 (LIN-12) Notch receptor extracellular domain. Additionally, OSM-11 and similar C. elegans proteins share a common motif with Notch ligands from other species in a sequence defined here as the Delta and OSM-11 (DOS) motif. osm-11 loss-of-function defects in vulval development are exacerbated by loss of other DOS-motif genes or by loss of the Notch ligand DSL-1, suggesting that DOS-motif and DSL proteins act together to activate Notch signaling in vivo. The mammalian DOS-motif protein Deltalike1 (DLK1) can substitute for OSM-11 in C. elegans development, suggesting that DOS-motif function is conserved across species. We hypothesize that C. elegans OSM-11 and homologous proteins act as coactivators for Notch receptors, allowing precise regulation of Notch receptor signaling in developmental programs in both vertebrates and invertebrates.
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Affiliation(s)
- Hidetoshi Komatsu
- Massachusetts General Hospital, Center for Cancer Research, Charlestown, Massachusetts, United States of America
- Department of Pathology, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Michael Y Chao
- Department of Biology, California State University San Bernardino, San Bernardino, California, United States of America
| | - Jonah Larkins-Ford
- Massachusetts General Hospital, Center for Cancer Research, Charlestown, Massachusetts, United States of America
| | - Mark E Corkins
- Massachusetts General Hospital, Center for Cancer Research, Charlestown, Massachusetts, United States of America
| | - Gerard A Somers
- Massachusetts General Hospital, Center for Cancer Research, Charlestown, Massachusetts, United States of America
| | - Tim Tucey
- Massachusetts General Hospital, Center for Cancer Research, Charlestown, Massachusetts, United States of America
| | - Heather M Dionne
- Massachusetts General Hospital, Center for Cancer Research, Charlestown, Massachusetts, United States of America
| | - Jamie Q White
- Massachusetts General Hospital, Center for Cancer Research, Charlestown, Massachusetts, United States of America
- Department of Pathology, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Khursheed Wani
- Massachusetts General Hospital, Center for Cancer Research, Charlestown, Massachusetts, United States of America
| | - Mike Boxem
- Center for Cancer Systems Biology (CCSB) and Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, Massachusetts, United States of America
- Department of Genetics, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Anne C Hart
- Massachusetts General Hospital, Center for Cancer Research, Charlestown, Massachusetts, United States of America
- Department of Pathology, Harvard Medical School, Boston, Massachusetts, United States of America
- * To whom correspondence should be addressed. E-mail:
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Ding N, Zhou H, Esteve PO, Chin HG, Kim S, Xu X, Joseph SM, Friez MJ, Schwartz CE, Pradhan S, Boyer TG. Mediator links epigenetic silencing of neuronal gene expression with x-linked mental retardation. Mol Cell 2008; 31:347-59. [PMID: 18691967 DOI: 10.1016/j.molcel.2008.05.023] [Citation(s) in RCA: 183] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2007] [Revised: 04/20/2008] [Accepted: 05/29/2008] [Indexed: 11/18/2022]
Abstract
Mediator occupies a central role in RNA polymerase II transcription as a sensor, integrator, and processor of regulatory signals that converge on protein-coding gene promoters. Compared to its role in gene activation, little is known regarding the molecular mechanisms and biological implications of Mediator as a transducer of repressive signals. Here we describe a protein interaction network required for extraneuronal gene silencing comprising Mediator, G9a histone methyltransferase, and the RE1 silencing transcription factor (REST; also known as neuron restrictive silencer factor, NRSF). We show that the MED12 interface in Mediator links REST with G9a-dependent histone H3K9 dimethylation to suppress neuronal genes in nonneuronal cells. Notably, missense mutations in MED12 causing the X-linked mental retardation (XLMR) disorders FG syndrome and Lujan syndrome disrupt its REST corepressor function. These findings implicate Mediator in epigenetic restriction of neuronal gene expression to the nervous system and suggest a pathologic basis for MED12-associated XLMR involving impaired REST-dependent neuronal gene regulation.
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Affiliation(s)
- Ning Ding
- Department of Molecular Medicine, University of Texas Health Science Center at San Antonio, San Antonio, TX 78245, USA
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Taubert S, Hansen M, Van Gilst MR, Cooper SB, Yamamoto KR. The Mediator subunit MDT-15 confers metabolic adaptation to ingested material. PLoS Genet 2008; 4:e1000021. [PMID: 18454197 PMCID: PMC2265483 DOI: 10.1371/journal.pgen.1000021] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2007] [Accepted: 01/10/2008] [Indexed: 12/12/2022] Open
Abstract
In eukaryotes, RNA polymerase II (PolII) dependent gene expression requires accessory factors termed transcriptional coregulators. One coregulator that universally contributes to PolII-dependent transcription is the Mediator, a multisubunit complex that is targeted by many transcriptional regulatory factors. For example, the Caenorhabditis elegans Mediator subunit MDT-15 confers the regulatory actions of the sterol response element binding protein SBP-1 and the nuclear hormone receptor NHR-49 on fatty acid metabolism. Here, we demonstrate that MDT-15 displays a broader spectrum of activities, and that it integrates metabolic responses to materials ingested by C. elegans. Depletion of MDT-15 protein or mutation of the mdt-15 gene abrogated induction of specific detoxification genes in response to certain xenobiotics or heavy metals, rendering these animals hypersensitive to toxin exposure. Intriguingly, MDT-15 appeared to selectively affect stress responses related to ingestion, as MDT-15 functional defects did not abrogate other stress responses, e.g., thermotolerance. Together with our previous finding that MDT-15:NHR-49 regulatory complexes coordinate a sector of the fasting response, we propose a model whereby MDT-15 integrates several transcriptional regulatory pathways to monitor both the availability and quality of ingested materials, including nutrients and xenobiotic compounds. All organisms adapt their physiology to external input, such as altered food availability or toxic challenges. Many of these responses are driven by changes in gene transcription. In general, sequence specific DNA-binding regulatory factors are considered the specificity determinants of the transcriptional output. Here, we show that, in the roundworm Caenorhabditis elegans, one subunit of a >20 subunit, evolutionarily conserved, non-DNA binding co-factor termed Mediator, specifies a portion of the metabolic responses to a mixture of ingested material. This protein, MDT-15, is required for appropriate expression of genes that protect worms from the effects of toxic compounds and heavy metals. Our previous findings showed that the same protein also cooperates with other regulators to coordinate lipid metabolism. We suggest that MDT-15 may “route” transcriptional responses appropriate to the ingested material. This physiological scope appears broader and more sophisticated than that of any individual regulatory factor, thus coordinating systemic metabolic adaptation with ingestion. Given the evolutionary conservation of MDT-15 and the Mediator, a similar regulatory pathway may ensure health and longevity in mammals.
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Affiliation(s)
- Stefan Taubert
- Department of Cellular and Molecular Pharmacology, University of California San Francisco, San Francisco, California, United States of America
| | - Malene Hansen
- Department of Biochemistry and Biophysics, University of California San Francisco, San Francisco, California, United States of America
| | - Marc R. Van Gilst
- Fred Hutchinson Cancer Research Center, Basic Sciences Division, Seattle, Washington, United States of America
| | - Samantha B. Cooper
- Department of Cellular and Molecular Pharmacology, University of California San Francisco, San Francisco, California, United States of America
- Graduate Program of Biological and Medical Informatics, University of California San Francisco, San Francisco, California, United States of America
| | - Keith R. Yamamoto
- Department of Cellular and Molecular Pharmacology, University of California San Francisco, San Francisco, California, United States of America
- * E-mail:
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Abstract
The Mediator complex is a fluid assemblage of approximately 25 proteins that is essential for eukaryotic transcriptional regulation. Mediator of RNA polymerase II transcription (MED)12 (HOPA) is a 25-kb Xq13 member of the Mediator complex that plays a key role in the complex and directly moderates receptor tyrosine kinase, nuclear receptor and Wnt pathway signaling. Sequence variation in two MED12 protein domains has been linked to neuropsychiatric illness. First, variants in the Leu-Ser domain have been linked to Opitz-Kaveggia and Lujan syndromes, which are forms of X-linked mental retardation. Second, a balanced polymorphism in the C terminus opposite-paired domain, a key motif in the MED12-mediated transcriptional repression of Wnt signaling, has been associated with increased risk for psychosis. We conclude that variation of MED12 is associated with a wide variety of clinical presentations whose severity is dependent on the location and nature of the variation, and that a thorough understanding of MED12's role in transcriptional regulation could have significant benefits for human healthcare.
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Affiliation(s)
- Robert A Philibert
- The University of Iowa, Department of Psychiatry, Neuroscience Program, Room 2-126 MEB, Iowa City, IA 52242-1000, USA.
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Van Hoffelen S, Herman MA. Analysis of Wnt signaling during Caenorhabditis elegans postembryonic development. Methods Mol Biol 2008; 469:87-102. [PMID: 19109705 DOI: 10.1007/978-1-60327-469-2_8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
Abstract
Wnts play a central role in the development of many cells and tissue types in all species studied to date. Like many other extracellular signaling pathways, secreted Wnt proteins are involved in many different processes; in C. elegans these include: cell proliferation, differentiation, cell migration, control of cell polarity, axon outgrowth and control of the stem cell niche. Perturbations in Wnt signaling are also key factors in cancer formation, and therefore of interest to oncobiologists. Wnts are secreted glycoproteins, which bind to Frizzled transmembrane receptors and signal either through, or independently of beta-catenin. Both beta-catenin-dependant (Wnt/beta-catenin) and -independent pathways function during postembryonic development in C. elegans and allow Wnt researchers to explore aspects of Wnt signaling both in common with other organisms and unique to the nematode. Chapter 9 in Volume 2 discusses various processes controlled by Wnt signaling during C. elegans embryonic development; this chapter discusses Wnt controlled processes that occur during postembryonic development, including an overview of methods used to observe their function.
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Philibert RA, Bohle P, Secrest D, Deaderick J, Sandhu H, Crowe R, Black DW. The association of the HOPA(12bp) polymorphism with schizophrenia in the NIMH Genetics Initiative for Schizophrenia sample. Am J Med Genet B Neuropsychiatr Genet 2007; 144B:743-7. [PMID: 17299734 DOI: 10.1002/ajmg.b.30489] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
HOPA (MED12) is an X-chromosome gene that codes for a critical member of the Mediator Complex, a group of proteins that regulates transcription via the nuclear receptor, Wnt and Receptor Tyrosine Kinase pathways. In prior association and meta-analyses, we have shown that the presence of an evolutionarily conserved, 12 bp (4 amino acid) insertional polymorphism in exon 43 of this gene is associated with increased risk for an endophenotype of schizophrenia. In this communication, we describe the results of our work with subjects and data from the National Institutes of Mental Health (NIMH) Genetics Initiative for Schizophrenia. We report that the presence of the HOPA(12bp) polymorphism is associated with increased risk for schizophrenia in subjects of European ancestry. In the light of this new study and the prior wealth of clinical and basic science data, we conclude that the HOPA(12bp) allele is a risk factor for schizophrenia in subjects of European ancestry and suggest that further studies to define the endophenotype and mechanisms of illness associated with this polymorphism are indicated.
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Affiliation(s)
- Robert A Philibert
- Department of Psychiatry, The University of Iowa, Iowa City, Iowa 52242-1000, USA.
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33
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Parker DS, Blauwkamp T, Cadigan KM. Wnt/β‐catenin‐mediated transcriptional regulation. WNT SIGNALING IN EMBRYONIC DEVELOPMENT 2007. [DOI: 10.1016/s1574-3349(06)17001-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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Wang X, Yang N, Uno E, Roeder RG, Guo S. A subunit of the mediator complex regulates vertebrate neuronal development. Proc Natl Acad Sci U S A 2006; 103:17284-9. [PMID: 17088561 PMCID: PMC1859923 DOI: 10.1073/pnas.0605414103] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The unique profiles of gene expression dictate distinct cellular identity. How these profiles are established during development is not clear. Here we report that the mutant motionless (mot), identified in a genetic screen for mutations that affect neuronal development in zebrafish, displays deficits of monoaminergic neurons and cranial sensory ganglia, whereas expression of the pan-neuronal marker Hu is largely unperturbed; GABAergic and subsets of cranial motor neurons do not appear to be deficient. Positional cloning reveals that mot encodes Med12, a component of the evolutionarily conserved Mediator complex, whose in vivo function is not well understood in vertebrates. mot/med12 transcripts are enriched in the embryonic brain and appear distinct from two other Mediator components Med17 and Med21. Delivery of human med12 RNA into zebrafish restores normality to the mot mutant and, strikingly, leads to premature neuronal differentiation and an increased production of monoaminergic neuronal subtypes in WT. Further investigation reveals that mot/med12 is necessary to regulate, and when overexpressed is capable of increasing, the expression of distinct neuronal determination genes, including zash1a and lim1, and serves as an in vivo cofactor for Sox9 in this process. Together, our analyses reveal a regulatory role of Mot/Med12 in vertebrate neuronal development.
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Affiliation(s)
- Xiaoqun Wang
- *Programs in Genetics, Neuroscience, and Developmental Biology, Department of Biopharmaceutical Sciences, and Center for Human Genetics, University of California, San Francisco, CA 94143; and
| | - Nan Yang
- *Programs in Genetics, Neuroscience, and Developmental Biology, Department of Biopharmaceutical Sciences, and Center for Human Genetics, University of California, San Francisco, CA 94143; and
| | - Etsuko Uno
- Laboratory of Biochemistry and Molecular Biology, The Rockefeller University, 1230 York Avenue, New York, NY 10021
| | - Robert G. Roeder
- Laboratory of Biochemistry and Molecular Biology, The Rockefeller University, 1230 York Avenue, New York, NY 10021
| | - Su Guo
- *Programs in Genetics, Neuroscience, and Developmental Biology, Department of Biopharmaceutical Sciences, and Center for Human Genetics, University of California, San Francisco, CA 94143; and
- To whom correspondence should be addressed. E-mail:
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35
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Gupta BP, Liu J, Hwang BJ, Moghal N, Sternberg PW. sli-3 negatively regulates the LET-23/epidermal growth factor receptor-mediated vulval induction pathway in Caenorhabditis elegans. Genetics 2006; 174:1315-26. [PMID: 16980384 PMCID: PMC1667086 DOI: 10.1534/genetics.106.063990] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2006] [Accepted: 08/21/2006] [Indexed: 11/18/2022] Open
Abstract
The LIN-3-LET-23-mediated inductive signaling pathway plays a major role during vulval development in C. elegans. Studies on the components of this pathway have revealed positive as well as negative regulators that function to modulate the strength and specificity of the signal transduction cascade. We have carried out genetic screens to identify new regulators of this pathway by screening for suppressors of lin-3 vulvaless phenotype. The screens recovered three loci including alleles of gap-1 and a new gene represented by sli-3. Our genetic epistasis experiments suggest that sli-3 functions either downstream or in parallel to nuclear factors lin-1 and sur-2. sli-3 synergistically interacts with the previously identified negative regulators of the let-23 signaling pathway and causes excessive cell proliferation. However, in the absence of any other mutation sli-3 mutant animals display wild-type vulval induction and morphology. We propose that sli-3 functions as a negative regulator of vulval induction and defines a branch of the inductive signaling pathway. We provide evidence that sli-3 interacts with the EGF signaling pathway components during vulval induction but not during viability and ovulation processes. Thus, sli-3 helps define specificity of the EGF signaling to induce the vulva.
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Affiliation(s)
- Bhagwati P Gupta
- Department of Biology, McMaster University, Hamilton, Ontario, Canada.
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36
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Lehner B, Crombie C, Tischler J, Fortunato A, Fraser AG. Systematic mapping of genetic interactions in Caenorhabditis elegans identifies common modifiers of diverse signaling pathways. Nat Genet 2006; 38:896-903. [PMID: 16845399 DOI: 10.1038/ng1844] [Citation(s) in RCA: 369] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2006] [Accepted: 06/12/2006] [Indexed: 01/19/2023]
Abstract
Most heritable traits, including disease susceptibility, are affected by interactions between multiple genes. However, we understand little about how genes interact because very few possible genetic interactions have been explored experimentally. We have used RNA interference in Caenorhabditis elegans to systematically test approximately 65,000 pairs of genes for their ability to interact genetically. We identify approximately 350 genetic interactions between genes functioning in signaling pathways that are mutated in human diseases, including components of the EGF/Ras, Notch and Wnt pathways. Most notably, we identify a class of highly connected 'hub' genes: inactivation of these genes can enhance the phenotypic consequences of mutation of many different genes. These hub genes all encode chromatin regulators, and their activity as genetic hubs seems to be conserved across animals. We propose that these genes function as general buffers of genetic variation and that these hub genes may act as modifier genes in multiple, mechanistically unrelated genetic diseases in humans.
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Affiliation(s)
- Ben Lehner
- The Wellcome Trust Sanger Institute, Hinxton, Cambridge CB10 1HH, UK
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37
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Belakavadi M, Fondell JD. Role of the mediator complex in nuclear hormone receptor signaling. Rev Physiol Biochem Pharmacol 2006; 156:23-43. [PMID: 16634145 DOI: 10.1007/s10254-005-0002-0] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Mediator is an evolutionarily conserved multisubunit protein complex that plays a key role in regulating transcription by RNA polymerase II. The complex functions by serving as a molecular bridge between DNA-bound transcriptional activators and the basal transcription apparatus. In humans, Mediator was first characterized as a thyroid hormone receptor (TR)-associated protein (TRAP) complex that facilitates ligand-dependent transcriptional activation by TR. More recently, Mediator has been established as an essential coactivator for a broad range of nuclear hormone receptors (NRs) as well as several other types of gene-specific transcriptional activators. A single subunit of the complex, MED1/TRAP220, is required for direct ligand-dependent interactions with NRs. Mediator coactivates NR-regulated gene expression by facilitating the recruitment and activation of the RNA polymerase II-associated basal transcription apparatus. Importantly, Mediator acts in concert with other NR coactivators involved in chromatin remodeling to initiate transcription of NR target genes in a multistep manner. In this review, we summarize the functional role of Mediator in NR signaling pathways with an emphasis on the underlying molecular mechanisms by which the complex interacts with NRs and subsequently facilitates their action. We also focus on recent advances in our understanding of TRAP/Mediator's pathophysiological role in mammalian disease and development.
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Affiliation(s)
- M Belakavadi
- Department of Physiology and Biophysics, Robert Wood Johnson Medical School, UMDNJ, Piscataway, NJ 08854, USA
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38
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Abstract
Uncommon polymorphisms, particularly balanced uncommon polymorphisms, present a significant challenge to our understanding of their role in behavior. We have recently demonstrated that an uncommon candidate gene polymorphism for schizophrenia, known as HOPA12bp, is the defining polymorphism for a large X-chromosome haplotype in population disequilibrium and that it is associated with a positive syndrome of psychosis. Not all studies, however, have shown this effect. In this report, we reviewed prior studies and conducted meta-analysis of studies using probands of northern European extraction. We found that the presence of the HOPA12bp is a significant risk factor for psychosis for both men and women and suggest that differences in the case definition of schizophrenia may affect the strength of the association.
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Affiliation(s)
- Robert A Philibert
- Department of Psychiatry, Neuroscience Program, The University of Iowa, Iowa City, IA 52242-1000, USA.
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Chesney MA, Kidd AR, Kimble J. gon-14 functions with class B and class C synthetic multivulva genes to control larval growth in Caenorhabditis elegans. Genetics 2006; 172:915-28. [PMID: 16322520 PMCID: PMC1383727 DOI: 10.1534/genetics.105.048751] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2005] [Accepted: 11/09/2005] [Indexed: 12/11/2022] Open
Abstract
Previous work showed that C. elegans gon-14 is required for gonadogenesis. Here we report that gon-14 encodes a protein with similarity to LIN-15B, a class B synMuv protein. An extensive region of GON-14 contains blocks of sequence similarity to transposases of the hAT superfamily, but key residues are not conserved, suggesting a distant relationship. GON-14 also contains a putative THAP DNA-binding domain. A rescuing gon-14::GON-14::VENUS reporter is broadly expressed during development and localizes to the nucleus. Strong loss-of-function and predicted null gon-14 alleles have pleiotropic defects, including multivulval (Muv) defects and temperature-sensitive larval arrest. Although the gon-14 Muv defect is not enhanced by synMuv mutations, gon-14 interacts genetically with class B and class C synMuv genes, including lin-35/Rb, let-418/Mi-2beta, and trr-1/TRRAP. The gon-14; synMuv double mutants arrest as larvae when grown under conditions supporting development to adulthood for the respective single mutants. The gon-14 larval arrest is suppressed by loss of mes-2/E(Z), mes-6/ESC, or mes-4, which encodes a SET domain protein. Additionally, gon-14 affects expression of pgl-1 and lag-2, two genes regulated by the synMuv genes. We suggest that gon-14 functions with class B and class C synMuv genes to promote larval growth, in part by antagonizing MES-2,3,6/ESC-E(z) and MES-4.
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Affiliation(s)
- Michael A Chesney
- Department of Biochemistry, University of Wisconsin, Madison, Wisconsin 53706-1544, USA
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40
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Lehner B, Calixto A, Crombie C, Tischler J, Fortunato A, Chalfie M, Fraser AG. Loss of LIN-35, the Caenorhabditis elegans ortholog of the tumor suppressor p105Rb, results in enhanced RNA interference. Genome Biol 2006; 7:R4. [PMID: 16507136 PMCID: PMC1431716 DOI: 10.1186/gb-2006-7-1-r4] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2005] [Revised: 10/27/2005] [Accepted: 12/16/2005] [Indexed: 11/26/2022] Open
Abstract
Mutations in lin-35, the worm ortholog of a mammalian tumor suppressor gene, and other synMuv B genes result in an increased sensitivity to RNAi and enhanced somatic transgene silencing. Background Genome-wide RNA interference (RNAi) screening is a very powerful tool for analyzing gene function in vivo in Caenorhabditis elegans. The effectiveness of RNAi varies from gene to gene, however, and neuronally expressed genes are largely refractive to RNAi in wild-type worms. Results We found that C. elegans strains carrying mutations in lin-35, the worm ortholog of the tumor suppressor gene p105Rb, or a subset of the genetically related synMuv B family of chromatin-modifying genes, show increased strength and penetrance for many germline, embryonic, and post-embryonic RNAi phenotypes, including neuronal RNAi phenotypes. Mutations in these same genes also enhance somatic transgene silencing via an RNAi-dependent mechanism. Two genes, mes-4 and zfp-1, are required both for the vulval lineage defects resulting from mutations in synMuv B genes and for RNAi, suggesting a common mechanism for the function of synMuv B genes in vulval development and in regulating RNAi. Enhanced RNAi in the germline of lin-35 worms suggests that misexpression of germline genes in somatic cells cannot alone account for the enhanced RNAi observed in this strain. Conclusion A worm strain with a null mutation in lin-35 is more sensitive to RNAi than any other previously described single mutant strain, and so will prove very useful for future genome-wide RNAi screens, particularly for identifying genes with neuronal functions. As lin-35 is the worm ortholog of the mammalian tumor suppressor gene p105Rb, misregulation of RNAi may be important during human oncogenesis.
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Affiliation(s)
- Ben Lehner
- The Wellcome Trust Sanger Institute, Hinxton, Cambridge CB10 1SA, UK
| | - Andrea Calixto
- Department of Biological Sciences, Columbia University, New York, NY 10027, USA
| | - Catriona Crombie
- The Wellcome Trust Sanger Institute, Hinxton, Cambridge CB10 1SA, UK
| | - Julia Tischler
- The Wellcome Trust Sanger Institute, Hinxton, Cambridge CB10 1SA, UK
| | - Angelo Fortunato
- The Wellcome Trust Sanger Institute, Hinxton, Cambridge CB10 1SA, UK
| | - Martin Chalfie
- Department of Biological Sciences, Columbia University, New York, NY 10027, USA
| | - Andrew G Fraser
- The Wellcome Trust Sanger Institute, Hinxton, Cambridge CB10 1SA, UK
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41
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Hong SK, Haldin CE, Lawson ND, Weinstein BM, Dawid IB, Hukriede NA. The zebrafish kohtalo/trap230 gene is required for the development of the brain, neural crest, and pronephric kidney. Proc Natl Acad Sci U S A 2005; 102:18473-8. [PMID: 16344459 PMCID: PMC1311743 DOI: 10.1073/pnas.0509457102] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Mutation of the gene encoding the Mediator component thyroid hormone receptor-associated protein (TRAP)230/MED12 affects the development of multiple systems in zebrafish embryogenesis. We isolated two ethylnitrosourea-induced alleles in the gene encoding this protein and named the locus kohtalo (kto) after the homologous locus in Drosophila. Homozygous kto mutant zebrafish embryos show defects in brain, neural crest, and kidney development and die at approximately 6 days postfertilization. In the affected tissues, differentiation is initiated and many cell type-specific genes are expressed, but there is a failure of morphogenesis and failure to complete differentiation. These results suggest that critical targets of TRAP230 function may include proteins important for cell mobility, cell sorting, and tissue assembly.
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Affiliation(s)
- Sung-Kook Hong
- Laboratory of Molecular Genetics, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
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42
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Poulin G, Dong Y, Fraser AG, Hopper NA, Ahringer J. Chromatin regulation and sumoylation in the inhibition of Ras-induced vulval development in Caenorhabditis elegans. EMBO J 2005; 24:2613-23. [PMID: 15990876 PMCID: PMC1176455 DOI: 10.1038/sj.emboj.7600726] [Citation(s) in RCA: 105] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2004] [Accepted: 06/03/2005] [Indexed: 12/30/2022] Open
Abstract
In Caenorhabditis elegans, numerous 'synMuv' (synthetic multivulval) genes encode for chromatin-associated proteins involved in transcriptional repression, including an orthologue of Rb and components of the NuRD histone deacetylase complex. These genes antagonize Ras signalling to prevent erroneous adoption of vulval fate. To identify new components of this mechanism, we performed a genome-wide RNA interference (RNAi) screen. After RNAi of 16 757 genes, we found nine new synMuv genes. Based on predicted functions and genetic epistasis experiments, we propose that at least four post-translational modifications converge to inhibit Ras-stimulated vulval development: sumoylation, histone tail deacetylation, methylation, and acetylation. In addition, we demonstrate a novel role for sumoylation in inhibiting LIN-12/Notch signalling in the vulva. We further show that many of the synMuv genes are involved in gene regulation outside the vulva, negatively regulating the expression of the Delta homologue lag-2. As most of the genes identified in this screen are conserved in humans, we suggest that similar interactions may be relevant in mammals for control of Ras and Notch signalling, crosstalk between these pathways, and cell proliferation.
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Affiliation(s)
- Gino Poulin
- Wellcome Trust/Cancer Research UK Gurdon Institute, University of Cambridge, Cambridge, UK
- Department of Genetics, University of Cambridge, Cambridge, UK
| | - Yan Dong
- Wellcome Trust/Cancer Research UK Gurdon Institute, University of Cambridge, Cambridge, UK
- Department of Genetics, University of Cambridge, Cambridge, UK
| | - Andrew G Fraser
- Wellcome Trust/Cancer Research UK Gurdon Institute, University of Cambridge, Cambridge, UK
| | - Neil A Hopper
- School of Biological Sciences, University of Southampton, Southampton, UK
| | - Julie Ahringer
- Wellcome Trust/Cancer Research UK Gurdon Institute, University of Cambridge, Cambridge, UK
- Department of Genetics, University of Cambridge, Cambridge, UK
- Wellcome Trust/Cancer Research UK Gurdon Institute, University of Cambridge, Tennis Court Road, Cambridge CB2 1QR, UK. Tel.: +44 1223 334088; Fax: +44 1223 334089; E-mail:
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Abstract
Mediator was first identified because of its activity in activator-stimulated transcription in vivo and in vitro. Later, biochemical fractionation led to the co-purification of the multi-subunit Mediator complex and RNA polymerase II (pol II). Results of these studies suggested a model whereby transcription-activator proteins, which bind to specific gene regulatory sequences, recruit both Mediator and pol II as a holoenzyme in a one-step mechanism. More recent studies of Drosophila Mediator and additional studies in yeast have demonstrated that different transcription activators can bind and recruit Mediator to promoters in vivo in a step that is independent of pol II recruitment. Moreover, the different activators in Drosophila bind and recruit Mediator via physical interactions with specific subsets of proteins. These features of Mediator function seem to be broadly conserved.
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Affiliation(s)
- Young-Joon Kim
- Department of Biochemistry, Yonsei University, 134 Sinchon-dong, Seodaemoon-gu, Seoul 120-749, Republic of Korea
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Kenning C, Kipping I, Sommer RJ. Isolation of mutations with dumpy-like phenotypes and of collagen genes in the nematode Pristionchus pacificus. Genesis 2005; 40:176-83. [PMID: 15493014 DOI: 10.1002/gene.20084] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The nematode Pristionchus pacificus was developed as a satellite system in evolutionary developmental biology and forward and reverse genetic approaches allow a detailed comparison of various developmental processes between P. pacificus and Caenorhabditis elegans. To facilitate map-based cloning in P. pacificus, a genome map was generated including a genetic linkage map of approximately 300 molecular markers and a physical map of 10,000 BAC clones. Here, we describe the isolation and characterization of more than 40 morphological mutations that can be used as genetic markers. These mutations fall into 12 Dumpy genes and one Roller gene that represent morphological markers for all six P. pacificus chromosomes. Using an in silico approach, we identified approximately 150 hits of P. pacificus collagen genes in the available EST, BAC-end, and fosmid-end sequences. However, 1:1 orthologs could only be identified for fewer than 20 collagen genes.
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Affiliation(s)
- Charlotte Kenning
- Max-Planck-Institut für Entwicklungsbiologie, Abteilung Evolutionsbiologie, Spermannstrasse 37-39, D-72076 Tübingen, Germany
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Yoda A, Kouike H, Okano H, Sawa H. Components of the transcriptional Mediator complex are required for asymmetric cell division inC. elegans. Development 2005; 132:1885-93. [PMID: 15790964 DOI: 10.1242/dev.01776] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Asymmetric cell division is a fundamental process that produces cellular diversity during development. In C. elegans, the Wnt signaling pathway regulates the asymmetric divisions of a number of cells including the T blast cell. We found that the let-19 and dpy-22 mutants have defects in their T-cell lineage, and lineage analyses showed that the defects were caused by disruption in the asymmetry of the T-cell division. We found that let-19 and dpy-22 encode homologs of the human proteins MED13/TRAP240 and MED12/TRAP230, respectively, which are components of the Mediator complex. Mediator is a multi-component complex that can regulate transcription by transducing the signals between activators and RNA polymerase in vitro. We also showed that LET-19 and DPY-22 form a complex in vivo with other components of Mediator, SUR-2/MED23 and LET-425/MED6. In the let-19 and dpy-22 mutants, tlp-1, which is normally expressed asymmetrically between the T-cell daughters through the function of the Wnt pathway, was expressed symmetrically in both daughter cells. Furthermore, we found that the let-19 and dpy-22 mutants were defective in the fusion of the Pn.p cell, a process that is regulated by bar-1/β-catenin. Ectopic cell fusion in bar-1 mutants was suppressed by the let-19 or dpy-22 mutations, while defective cell fusion in let-19 mutants was suppressed by lin-39/Hox mutations, suggesting that let-19 and dpy-22 repress the transcription of lin-39. These results suggest that LET-19 and DPY-22 in the Mediator complex repress the transcription of Wnt target genes.
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Affiliation(s)
- Akinori Yoda
- Division of Neuroanatomy, Osaka University Graduate School of Medicine, Kobe University, Kobe 650-0017, Japan
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Sandhu HK, Hollenbeck N, Wassink TH, Philibert RA. An association study of PCQAP polymorphisms and schizophrenia. Psychiatr Genet 2005; 14:169-72. [PMID: 15318033 DOI: 10.1097/00041444-200409000-00010] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
INTRODUCTION PCQAP is a member of the mediator family of transcription co-activators that is found in the region of 22q11, which is consistently deleted in DiGeorges/velocranialfacial (VCF) syndrome. As such, it is a gene of interest to behavioral geneticists because VCF is also associated with a high rate of psychosis and because defects in other mediator genes have been linked to psychosis and abnormal neurodevelopmental abnormalities. Recently, DeLuca and colleagues reported that polymorphisms in a trinucleotide repeat in exon 7 of PCQAP were associated with schizophrenia in a case-control study of Italian schizophrenics. OBJECTIVE AND METHODS To confirm and extend the prior findings, we conducted a case-control association analysis using DNA from 233 schizophrenics and 371 random controls. RESULTS Unfortunately, we did not find any significant differences in the distribution of CAG repeat alleles between subjects and controls. CONCLUSIONS These findings limit the role of exon 7 PCQAP polymorphisms in the pathogenesis of schizophrenia.
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Affiliation(s)
- Harinder K Sandhu
- Department of Psychiatry, The University of Iowa, Iowa City, Iowa 52242-1000, USA
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Spinks R, Sandhu HK, Andreasen NC, Philibert RA. Association of the HOPA12bp allele with a large X-chromosome haplotype and positive symptom schizophrenia. Am J Med Genet B Neuropsychiatr Genet 2004; 127B:20-7. [PMID: 15108174 DOI: 10.1002/ajmg.b.20175] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
HOPA is a X-chromosome gene that encodes an essential nuclear receptor co-activator. Previously, we have demonstrated that an exonic polymorphism, termed HOPA(12bp), in the Opa (Opposite Paired) domain of this gene that is critical for neuronal growth and differentiation is associated with a low risk for schizophrenia. But curiously, we have also noted that all HOPA(12bp) probands have the same haplotype immediately surrounding the HOPA(12bp), and other investigators have found evidence of population stratification with the HOPA(12bp) allele. Since deleterious alleles are weeded from the population, and the HOPA(12bp) allele is not rare, these prior findings suggest the possibility that positive selection may be occurring with respect to the HOPA(12bp) allele and that unique phenotypic features may be associated with this allele. To test these hypotheses, we analyzed symptom data collected from schizophrenic probands and conducted haplotyping studies around the HOPA(12bp) polymorphism. Consistent with our hypotheses, genotyping studies of 43 unrelated HOPA(12bp) males and 137 HOPA(wild) males demonstrated that the HOPA(12bp) allele is associated with a large conserved DNA haplotype that extends over several genes known to be critical for human survival. Furthermore, ANOVA analysis of symptom data demonstrated that HOPA(12bp) schizophrenic probands (n = 14) have significantly lower severity of negative symptoms (P < 0.002) and better attention (P < 0.002) than matched controls (n = 30). Taken together, these findings further refine the behavioral endophenotype associated with the HOPA(12bp) allele and suggest that the sequence surrounding HOPA may need to be considered to fully understand the molecular basis of the phenotype associated with the HOPA(12bp) allele.
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Affiliation(s)
- Ruth Spinks
- Department of Psychiatry, The University of Iowa, Psychiatry Research/MEB, Iowa City, USA
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Moghal N, Garcia LR, Khan LA, Iwasaki K, Sternberg PW. Modulation of EGF receptor-mediated vulva development by the heterotrimeric G-protein Galphaq and excitable cells in C. elegans. Development 2003; 130:4553-66. [PMID: 12925583 DOI: 10.1242/dev.00670] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The extent to which excitable cells and behavior modulate animal development has not been examined in detail. Here, we demonstrate the existence of a novel pathway for promoting vulval fates in C. elegans that involves activation of the heterotrimeric Galphaq protein, EGL-30. EGL-30 acts with muscle-expressed EGL-19 L-type voltage-gated calcium channels to promote vulva development, and acts downstream or parallel to LET-60 (RAS). This pathway is not essential for vulval induction on standard Petri plates, but can be stimulated by expression of activated EGL-30 in neurons, or by an EGL-30-dependent change in behavior that occurs in a liquid environment. Our results indicate that excitable cells and animal behavior can provide modulatory inputs into the effects of growth factor signaling on cell fates, and suggest that communication between these cell populations is important for normal development to occur under certain environmental conditions.
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Affiliation(s)
- Nadeem Moghal
- Howard Hughes Medical Institute and Division of Biology, California Institute of Technology, Pasadena, CA 91125, USA.
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Senbon S, Hirao Y, Miyano T. Interactions between the Oocyte and Surrounding Somatic Cells in Follicular Development: Lessons from In Vitro Culture. J Reprod Dev 2003; 49:259-69. [PMID: 14967918 DOI: 10.1262/jrd.49.259] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Mammalian oogenesis occurs concomitantly with folliculogenesis in a coordinated manner in the ovaries. In vitro growth (IVG) culture systems of the oocytes have been developed as a new technology for utilizing incompetent oocytes in the ovary as a source of mature oocytes as well as for studying oogenesis, folliculogenesis, and oocyte-somatic cell interactions. The results of IVG experiments have suggested that direct association of oocytes and surrounding granulosa cells supports oocyte viability and growth through the gap junctions, which are efficient conduits for low molecular weight substances. It has been revealed that granulosa cells metabolize some molecules which are in turn transported into the oocytes. IVG systems have also provided evidence that FSH promotes the development of follicles at secondary or later stages by its stimulation of proliferation and differentiation of granulosa cells, and perhaps by its anti-apoptotic effects. In addition, interactions between granulosa cell-derived KIT ligands and oocyte KIT receptors have been suggested as initiating oocyte growth and follicular development. Furthermore, recent findings suggest there are growth factors derived from oocytes such as GDF-9 and BMP-15. With such factors, oocytes participate in follicular development by regulating the differentiation of surrounding somatic cells. These bidirectional communications between oocytes and somatic cells are important for oocyte growth and follicular development. IVG systems should provide further information regarding oogenesis and folliculogenesis in the ovary.
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Affiliation(s)
- Shoichiro Senbon
- Graduate School of Science and Technology, Faculty of Agriculture, Kobe University, Kobe 657-8501, Japan
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