1
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Casazza A, Van Helleputte L, Van Renterghem B, Pokreisz P, De Geest N, De Petrini M, Janssens T, Pellens M, Diricx M, Riera-Domingo C, Wozniak A, Mazzone M, Schöffski P, Defert O, Reyns G, Kindt N. PhAc-ALGP-Dox, a Novel Anticancer Prodrug with Targeted Activation and Improved Therapeutic Index. Mol Cancer Ther 2022; 21:568-581. [PMID: 35149549 PMCID: PMC9377749 DOI: 10.1158/1535-7163.mct-21-0518] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2021] [Revised: 11/13/2021] [Accepted: 02/08/2022] [Indexed: 01/07/2023]
Abstract
Clinical use of doxorubicin (Dox) is limited by cumulative myelo- and cardiotoxicity. This research focuses on the detailed characterization of PhAc-ALGP-Dox, a targeted tetrapeptide prodrug with a unique dual-step activation mechanism, designed to circumvent Dox-related toxicities and is ready for upcoming clinical investigation. Coupling Dox to a phosphonoacetyl (PhAc)-capped tetrapeptide forms the cell-impermeable, inactive compound, PhAc-ALGP-Dox. After extracellular cleavage by tumor-enriched thimet oligopeptidase-1 (THOP1), a cell-permeable but still biologically inactive dipeptide-conjugate is formed (GP-Dox), which is further processed intracellularly to Dox by fibroblast activation protein-alpha (FAPα) and/or dipeptidyl peptidase-4 (DPP4). In vitro, PhAc-ALGP-Dox is effective in various 2D- and 3D-cancer models, while showing improved safety toward normal epithelium, hematopoietic progenitors, and cardiomyocytes. In vivo, these results translate into a 10-fold higher tolerability and 5-fold greater retention of Dox in the tumor microenvironment compared with the parental drug. PhAc-ALGP-Dox demonstrates 63% to 96% tumor growth inhibition in preclinical models, an 8-fold improvement in efficacy in patient-derived xenograft (PDX) models, and reduced metastatic burden in a murine model of experimental lung metastasis, improving survival by 30%. The current findings highlight the potential clinical benefit of PhAc-ALGP-Dox, a targeted drug-conjugate with broad applicability, favorable tissue biodistribution, significantly improved tolerability, and tumor growth inhibition at primary and metastatic sites in numerous solid tumor models.
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Affiliation(s)
- Andrea Casazza
- CoBioRes NV, Campus Gasthuisberg University of Leuven, Leuven, Belgium
| | | | - Britt Van Renterghem
- Laboratory of Experimental Oncology, Department of Oncology, KU Leuven, Leuven, Belgium
| | - Peter Pokreisz
- CoBioRes NV, Campus Gasthuisberg University of Leuven, Leuven, Belgium
| | - Natalie De Geest
- CoBioRes NV, Campus Gasthuisberg University of Leuven, Leuven, Belgium
| | - Marzia De Petrini
- CoBioRes NV, Campus Gasthuisberg University of Leuven, Leuven, Belgium
| | - Tom Janssens
- CoBioRes NV, Campus Gasthuisberg University of Leuven, Leuven, Belgium
| | - Marijke Pellens
- CoBioRes NV, Campus Gasthuisberg University of Leuven, Leuven, Belgium
| | - Marjan Diricx
- CoBioRes NV, Campus Gasthuisberg University of Leuven, Leuven, Belgium
| | - Carla Riera-Domingo
- Laboratory of Tumor Inflammation and Angiogenesis, Vesalius Research Center, VIB, Leuven, Belgium.,Laboratory of Tumor Inflammation and Angiogenesis, Department of Oncology, KU Leuven, Leuven, Belgium
| | - Agnieszka Wozniak
- Laboratory of Experimental Oncology, Department of Oncology, KU Leuven, Leuven, Belgium
| | - Massimiliano Mazzone
- Laboratory of Tumor Inflammation and Angiogenesis, Vesalius Research Center, VIB, Leuven, Belgium.,Laboratory of Tumor Inflammation and Angiogenesis, Department of Oncology, KU Leuven, Leuven, Belgium
| | - Patrick Schöffski
- Laboratory of Experimental Oncology, Department of Oncology, KU Leuven, Leuven, Belgium.,Department of General Medical Oncology, University Hospitals Leuven, Leuven Cancer Institute, Leuven, Belgium
| | - Olivier Defert
- CoBioRes NV, Campus Gasthuisberg University of Leuven, Leuven, Belgium
| | - Geert Reyns
- CoBioRes NV, Campus Gasthuisberg University of Leuven, Leuven, Belgium
| | - Nele Kindt
- CoBioRes NV, Campus Gasthuisberg University of Leuven, Leuven, Belgium.,Corresponding Author: Nele Kindt, CoBioRes NV, Campus Gasthuisberg, CDG, bus 913 Herestraat 49, Leuven, Flanders B-3000, Belgium. E-mail:
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2
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Talon I, Janiszewski A, Theeuwes B, Lefevre T, Song J, Bervoets G, Vanheer L, De Geest N, Poovathingal S, Allsop R, Marine JC, Rambow F, Voet T, Pasque V. Enhanced chromatin accessibility contributes to X chromosome dosage compensation in mammals. Genome Biol 2021; 22:302. [PMID: 34724962 PMCID: PMC8558763 DOI: 10.1186/s13059-021-02518-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2021] [Accepted: 10/13/2021] [Indexed: 01/21/2023] Open
Abstract
BACKGROUND Precise gene dosage of the X chromosomes is critical for normal development and cellular function. In mice, XX female somatic cells show transcriptional X chromosome upregulation of their single active X chromosome, while the other X chromosome is inactive. Moreover, the inactive X chromosome is reactivated during development in the inner cell mass and in germ cells through X chromosome reactivation, which can be studied in vitro by reprogramming of somatic cells to pluripotency. How chromatin processes and gene regulatory networks evolved to regulate X chromosome dosage in the somatic state and during X chromosome reactivation remains unclear. RESULTS Using genome-wide approaches, allele-specific ATAC-seq and single-cell RNA-seq, in female embryonic fibroblasts and during reprogramming to pluripotency, we show that chromatin accessibility on the upregulated mammalian active X chromosome is increased compared to autosomes. We further show that increased accessibility on the active X chromosome is erased by reprogramming, accompanied by erasure of transcriptional X chromosome upregulation and the loss of increased transcriptional burst frequency. In addition, we characterize gene regulatory networks during reprogramming and X chromosome reactivation, revealing changes in regulatory states. Our data show that ZFP42/REX1, a pluripotency-associated gene that evolved specifically in placental mammals, targets multiple X-linked genes, suggesting an evolutionary link between ZFP42/REX1, X chromosome reactivation, and pluripotency. CONCLUSIONS Our data reveal the existence of intrinsic compensatory mechanisms that involve modulation of chromatin accessibility to counteract X-to-Autosome gene dosage imbalances caused by evolutionary or in vitro X chromosome loss and X chromosome inactivation in mammalian cells.
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Affiliation(s)
- Irene Talon
- Department of Development and Regeneration, Laboratory of Cellular Reprogramming and Epigenetic Regulation, KU Leuven – University of Leuven, Herestraat 49, 3000 Leuven, Belgium
- KU Leuven Institute for Single Cell Omics (LISCO), 3000 Leuven, Belgium
- Leuven Stem Cell Institute (SCIL), 3000 Leuven, Belgium
| | - Adrian Janiszewski
- Department of Development and Regeneration, Laboratory of Cellular Reprogramming and Epigenetic Regulation, KU Leuven – University of Leuven, Herestraat 49, 3000 Leuven, Belgium
- KU Leuven Institute for Single Cell Omics (LISCO), 3000 Leuven, Belgium
- Leuven Stem Cell Institute (SCIL), 3000 Leuven, Belgium
| | - Bart Theeuwes
- Department of Development and Regeneration, Laboratory of Cellular Reprogramming and Epigenetic Regulation, KU Leuven – University of Leuven, Herestraat 49, 3000 Leuven, Belgium
- Leuven Stem Cell Institute (SCIL), 3000 Leuven, Belgium
| | - Thomas Lefevre
- Laboratory of Reproductive Genomics, Centre for Human Genetics, KU Leuven, 3000 Leuven, Belgium
| | - Juan Song
- Department of Development and Regeneration, Laboratory of Cellular Reprogramming and Epigenetic Regulation, KU Leuven – University of Leuven, Herestraat 49, 3000 Leuven, Belgium
- Leuven Stem Cell Institute (SCIL), 3000 Leuven, Belgium
| | - Greet Bervoets
- Laboratory for Molecular Cancer Biology, VIB Center for Cancer Biology, VIB, 3000 Leuven, Belgium
- Department of Oncology, Laboratory for Molecular Cancer Biology, KU Leuven, 3000 Leuven, Belgium
| | - Lotte Vanheer
- Department of Development and Regeneration, Laboratory of Cellular Reprogramming and Epigenetic Regulation, KU Leuven – University of Leuven, Herestraat 49, 3000 Leuven, Belgium
- KU Leuven Institute for Single Cell Omics (LISCO), 3000 Leuven, Belgium
- Leuven Stem Cell Institute (SCIL), 3000 Leuven, Belgium
| | - Natalie De Geest
- Department of Development and Regeneration, Laboratory of Cellular Reprogramming and Epigenetic Regulation, KU Leuven – University of Leuven, Herestraat 49, 3000 Leuven, Belgium
- Leuven Stem Cell Institute (SCIL), 3000 Leuven, Belgium
| | - Suresh Poovathingal
- KU Leuven Institute for Single Cell Omics (LISCO), 3000 Leuven, Belgium
- VIB-KU Leuven Center for Brain & Disease Research, 3000 Leuven, Belgium
| | - Ryan Allsop
- Department of Development and Regeneration, Laboratory of Cellular Reprogramming and Epigenetic Regulation, KU Leuven – University of Leuven, Herestraat 49, 3000 Leuven, Belgium
- KU Leuven Institute for Single Cell Omics (LISCO), 3000 Leuven, Belgium
- Leuven Stem Cell Institute (SCIL), 3000 Leuven, Belgium
| | - Jean-Christophe Marine
- KU Leuven Institute for Single Cell Omics (LISCO), 3000 Leuven, Belgium
- Laboratory for Molecular Cancer Biology, VIB Center for Cancer Biology, VIB, 3000 Leuven, Belgium
- Department of Oncology, Laboratory for Molecular Cancer Biology, KU Leuven, 3000 Leuven, Belgium
| | - Florian Rambow
- KU Leuven Institute for Single Cell Omics (LISCO), 3000 Leuven, Belgium
- Laboratory for Molecular Cancer Biology, VIB Center for Cancer Biology, VIB, 3000 Leuven, Belgium
| | - Thierry Voet
- KU Leuven Institute for Single Cell Omics (LISCO), 3000 Leuven, Belgium
- Laboratory of Reproductive Genomics, Centre for Human Genetics, KU Leuven, 3000 Leuven, Belgium
| | - Vincent Pasque
- Department of Development and Regeneration, Laboratory of Cellular Reprogramming and Epigenetic Regulation, KU Leuven – University of Leuven, Herestraat 49, 3000 Leuven, Belgium
- KU Leuven Institute for Single Cell Omics (LISCO), 3000 Leuven, Belgium
- Leuven Stem Cell Institute (SCIL), 3000 Leuven, Belgium
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3
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Posfai E, Schell JP, Janiszewski A, Rovic I, Murray A, Bradshaw B, Yamakawa T, Pardon T, El Bakkali M, Talon I, De Geest N, Kumar P, To SK, Petropoulos S, Jurisicova A, Pasque V, Lanner F, Rossant J. Evaluating totipotency using criteria of increasing stringency. Nat Cell Biol 2021. [PMID: 33420491 DOI: 10.1101/2020.1103.1102.972893] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/15/2023]
Abstract
Totipotency is the ability of a single cell to give rise to all of the differentiated cell types that build the conceptus, yet how to capture this property in vitro remains incompletely understood. Defining totipotency relies on a variety of assays of variable stringency. Here, we describe criteria to define totipotency. We explain how distinct criteria of increasing stringency can be used to judge totipotency by evaluating candidate totipotent cell types in mice, including early blastomeres and expanded or extended pluripotent stem cells. Our data challenge the notion that expanded or extended pluripotent states harbour increased totipotent potential relative to conventional embryonic stem cells under in vitro and in vivo conditions.
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Affiliation(s)
- Eszter Posfai
- Program in Developmental and Stem Cell Biology, Hospital for Sick Children, Toronto, Ontario, Canada.
- Department of Molecular Biology, Princeton University, Princeton, NJ, USA.
| | - John Paul Schell
- Department of Clinical Sciences, Intervention and Technology, Karolinska Institutet, Stockholm, Sweden
- Division of Obstetrics and Gynecology, Karolinska Universitetssjukhuset, Stockholm, Sweden
| | - Adrian Janiszewski
- Department of Development and Regeneration, Leuven Stem Cell Institute, KU Leuven, Leuven, Belgium
| | - Isidora Rovic
- Lunenfeld Tanenbaum Research Institute, Sinai Health System, Toronto, Ontario, Canada
| | - Alexander Murray
- Program in Developmental and Stem Cell Biology, Hospital for Sick Children, Toronto, Ontario, Canada
| | - Brian Bradshaw
- Program in Developmental and Stem Cell Biology, Hospital for Sick Children, Toronto, Ontario, Canada
| | - Tatsuya Yamakawa
- Program in Developmental and Stem Cell Biology, Hospital for Sick Children, Toronto, Ontario, Canada
| | - Tine Pardon
- Department of Development and Regeneration, Leuven Stem Cell Institute, KU Leuven, Leuven, Belgium
| | - Mouna El Bakkali
- Department of Development and Regeneration, Leuven Stem Cell Institute, KU Leuven, Leuven, Belgium
| | - Irene Talon
- Department of Development and Regeneration, Leuven Stem Cell Institute, KU Leuven, Leuven, Belgium
| | - Natalie De Geest
- Department of Development and Regeneration, Leuven Stem Cell Institute, KU Leuven, Leuven, Belgium
| | - Pankaj Kumar
- Department of Clinical Sciences, Intervention and Technology, Karolinska Institutet, Stockholm, Sweden
- Division of Obstetrics and Gynecology, Karolinska Universitetssjukhuset, Stockholm, Sweden
| | - San Kit To
- Department of Development and Regeneration, Leuven Stem Cell Institute, KU Leuven, Leuven, Belgium
| | - Sophie Petropoulos
- Department of Clinical Sciences, Intervention and Technology, Karolinska Institutet, Stockholm, Sweden
- Division of Obstetrics and Gynecology, Karolinska Universitetssjukhuset, Stockholm, Sweden
- Centre de Recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), Department of Medicine, University of Montreal, Montreal, Quebec, Canada
| | - Andrea Jurisicova
- Lunenfeld Tanenbaum Research Institute, Sinai Health System, Toronto, Ontario, Canada
- Departments of Obstetrics and Gynecology and Department of Physiology, University of Toronto, Toronto, Ontario, Canada
| | - Vincent Pasque
- Department of Development and Regeneration, Leuven Stem Cell Institute, KU Leuven, Leuven, Belgium.
| | - Fredrik Lanner
- Department of Clinical Sciences, Intervention and Technology, Karolinska Institutet, Stockholm, Sweden.
- Division of Obstetrics and Gynecology, Karolinska Universitetssjukhuset, Stockholm, Sweden.
- Ming Wai Lau Center for Reparative Medicine, Stockholm Node, Karolinska Institutet, Stockholm, Sweden.
| | - Janet Rossant
- Program in Developmental and Stem Cell Biology, Hospital for Sick Children, Toronto, Ontario, Canada.
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4
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Posfai E, Schell JP, Janiszewski A, Rovic I, Murray A, Bradshaw B, Yamakawa T, Pardon T, El Bakkali M, Talon I, De Geest N, Kumar P, To SK, Petropoulos S, Jurisicova A, Pasque V, Lanner F, Rossant J. Evaluating totipotency using criteria of increasing stringency. Nat Cell Biol 2021; 23:49-60. [PMID: 33420491 DOI: 10.1038/s41556-020-00609-2] [Citation(s) in RCA: 97] [Impact Index Per Article: 32.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Accepted: 11/17/2020] [Indexed: 01/28/2023]
Abstract
Totipotency is the ability of a single cell to give rise to all of the differentiated cell types that build the conceptus, yet how to capture this property in vitro remains incompletely understood. Defining totipotency relies on a variety of assays of variable stringency. Here, we describe criteria to define totipotency. We explain how distinct criteria of increasing stringency can be used to judge totipotency by evaluating candidate totipotent cell types in mice, including early blastomeres and expanded or extended pluripotent stem cells. Our data challenge the notion that expanded or extended pluripotent states harbour increased totipotent potential relative to conventional embryonic stem cells under in vitro and in vivo conditions.
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Affiliation(s)
- Eszter Posfai
- Program in Developmental and Stem Cell Biology, Hospital for Sick Children, Toronto, Ontario, Canada.
- Department of Molecular Biology, Princeton University, Princeton, NJ, USA.
| | - John Paul Schell
- Department of Clinical Sciences, Intervention and Technology, Karolinska Institutet, Stockholm, Sweden
- Division of Obstetrics and Gynecology, Karolinska Universitetssjukhuset, Stockholm, Sweden
| | - Adrian Janiszewski
- Department of Development and Regeneration, Leuven Stem Cell Institute, KU Leuven, Leuven, Belgium
| | - Isidora Rovic
- Lunenfeld Tanenbaum Research Institute, Sinai Health System, Toronto, Ontario, Canada
| | - Alexander Murray
- Program in Developmental and Stem Cell Biology, Hospital for Sick Children, Toronto, Ontario, Canada
| | - Brian Bradshaw
- Program in Developmental and Stem Cell Biology, Hospital for Sick Children, Toronto, Ontario, Canada
| | - Tatsuya Yamakawa
- Program in Developmental and Stem Cell Biology, Hospital for Sick Children, Toronto, Ontario, Canada
| | - Tine Pardon
- Department of Development and Regeneration, Leuven Stem Cell Institute, KU Leuven, Leuven, Belgium
| | - Mouna El Bakkali
- Department of Development and Regeneration, Leuven Stem Cell Institute, KU Leuven, Leuven, Belgium
| | - Irene Talon
- Department of Development and Regeneration, Leuven Stem Cell Institute, KU Leuven, Leuven, Belgium
| | - Natalie De Geest
- Department of Development and Regeneration, Leuven Stem Cell Institute, KU Leuven, Leuven, Belgium
| | - Pankaj Kumar
- Department of Clinical Sciences, Intervention and Technology, Karolinska Institutet, Stockholm, Sweden
- Division of Obstetrics and Gynecology, Karolinska Universitetssjukhuset, Stockholm, Sweden
| | - San Kit To
- Department of Development and Regeneration, Leuven Stem Cell Institute, KU Leuven, Leuven, Belgium
| | - Sophie Petropoulos
- Department of Clinical Sciences, Intervention and Technology, Karolinska Institutet, Stockholm, Sweden
- Division of Obstetrics and Gynecology, Karolinska Universitetssjukhuset, Stockholm, Sweden
- Centre de Recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), Department of Medicine, University of Montreal, Montreal, Quebec, Canada
| | - Andrea Jurisicova
- Lunenfeld Tanenbaum Research Institute, Sinai Health System, Toronto, Ontario, Canada
- Departments of Obstetrics and Gynecology and Department of Physiology, University of Toronto, Toronto, Ontario, Canada
| | - Vincent Pasque
- Department of Development and Regeneration, Leuven Stem Cell Institute, KU Leuven, Leuven, Belgium.
| | - Fredrik Lanner
- Department of Clinical Sciences, Intervention and Technology, Karolinska Institutet, Stockholm, Sweden.
- Division of Obstetrics and Gynecology, Karolinska Universitetssjukhuset, Stockholm, Sweden.
- Ming Wai Lau Center for Reparative Medicine, Stockholm Node, Karolinska Institutet, Stockholm, Sweden.
| | - Janet Rossant
- Program in Developmental and Stem Cell Biology, Hospital for Sick Children, Toronto, Ontario, Canada.
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5
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Vanheer L, Song J, De Geest N, Janiszewski A, Talon I, Provenzano C, Oh T, Chappell J, Pasque V. Tox4 modulates cell fate reprogramming. J Cell Sci 2019; 132:jcs.232223. [PMID: 31519808 PMCID: PMC6826012 DOI: 10.1242/jcs.232223] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2019] [Accepted: 09/06/2019] [Indexed: 01/05/2023] Open
Abstract
Reprogramming to induced pluripotency induces the switch of somatic cell identity to induced pluripotent stem cells (iPSCs). However, the mediators and mechanisms of reprogramming remain largely unclear. To elucidate the mediators and mechanisms of reprogramming, we used a siRNA-mediated knockdown approach for selected candidate genes during the conversion of somatic cells into iPSCs. We identified Tox4 as a novel factor that modulates cell fate through an assay that determined the efficiency of iPSC reprogramming. We found that Tox4 is needed early in reprogramming to efficiently generate early reprogramming intermediates, irrespective of the reprogramming conditions used. Tox4 enables proper exogenous reprogramming factor expression, and the closing and opening of putative somatic and pluripotency enhancers early during reprogramming, respectively. We show that the TOX4 protein assembles into a high molecular form. Moreover, Tox4 is also required for the efficient conversion of fibroblasts towards the neuronal fate, suggesting a broader role of Tox4 in modulating cell fate. Our study reveals Tox4 as a novel transcriptional modulator of cell fate that mediates reprogramming from the somatic state to the pluripotent and neuronal fate.This article has an associated First Person interview with the first author of the paper.
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Affiliation(s)
- Lotte Vanheer
- KU Leuven - University of Leuven, Department of Development and Regeneration, Herestraat 49, B-3000 Leuven, Belgium
| | - Juan Song
- KU Leuven - University of Leuven, Department of Development and Regeneration, Herestraat 49, B-3000 Leuven, Belgium
| | - Natalie De Geest
- KU Leuven - University of Leuven, Department of Development and Regeneration, Herestraat 49, B-3000 Leuven, Belgium
| | - Adrian Janiszewski
- KU Leuven - University of Leuven, Department of Development and Regeneration, Herestraat 49, B-3000 Leuven, Belgium
| | - Irene Talon
- KU Leuven - University of Leuven, Department of Development and Regeneration, Herestraat 49, B-3000 Leuven, Belgium
| | - Caterina Provenzano
- KU Leuven - University of Leuven, Department of Development and Regeneration, Herestraat 49, B-3000 Leuven, Belgium
| | - Taeho Oh
- KU Leuven - University of Leuven, Department of Development and Regeneration, Herestraat 49, B-3000 Leuven, Belgium
| | - Joel Chappell
- KU Leuven - University of Leuven, Department of Development and Regeneration, Herestraat 49, B-3000 Leuven, Belgium
| | - Vincent Pasque
- KU Leuven - University of Leuven, Department of Development and Regeneration, Herestraat 49, B-3000 Leuven, Belgium
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6
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Janiszewski A, Talon I, Chappell J, Collombet S, Song J, De Geest N, To SK, Bervoets G, Marin-Bejar O, Provenzano C, Vanheer L, Marine JC, Rambow F, Pasque V. Dynamic reversal of random X-Chromosome inactivation during iPSC reprogramming. Genome Res 2019; 29:1659-1672. [PMID: 31515287 PMCID: PMC6771397 DOI: 10.1101/gr.249706.119] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Accepted: 08/07/2019] [Indexed: 12/13/2022]
Abstract
Induction and reversal of chromatin silencing is critical for successful development, tissue homeostasis, and the derivation of induced pluripotent stem cells (iPSCs). X-Chromosome inactivation (XCI) and reactivation (XCR) in female cells represent chromosome-wide transitions between active and inactive chromatin states. Although XCI has long been studied, providing important insights into gene regulation, the dynamics and mechanisms underlying the reversal of stable chromatin silencing of X-linked genes are much less understood. Here, we use allele-specific transcriptomics to study XCR during mouse iPSC reprogramming in order to elucidate the timing and mechanisms of chromosome-wide reversal of gene silencing. We show that XCR is hierarchical, with subsets of genes reactivating early, late, and very late during reprogramming. Early genes are activated before the onset of late pluripotency genes activation. Early genes are located genomically closer to genes that escape XCI, unlike genes reactivating late. Early genes also show increased pluripotency transcription factor (TF) binding. We also reveal that histone deacetylases (HDACs) restrict XCR in reprogramming intermediates and that the severe hypoacetylation state of the inactive X Chromosome (Xi) persists until late reprogramming stages. Altogether, these results reveal the timing of transcriptional activation of monoallelically repressed genes during iPSC reprogramming, and suggest that allelic activation involves the combined action of chromatin topology, pluripotency TFs, and chromatin regulators. These findings are important for our understanding of gene silencing, maintenance of cell identity, reprogramming, and disease.
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Affiliation(s)
- Adrian Janiszewski
- KU Leuven-University of Leuven, Department of Development and Regeneration, Leuven Stem Cell Institute, B-3000 Leuven, Belgium
| | - Irene Talon
- KU Leuven-University of Leuven, Department of Development and Regeneration, Leuven Stem Cell Institute, B-3000 Leuven, Belgium
| | - Joel Chappell
- KU Leuven-University of Leuven, Department of Development and Regeneration, Leuven Stem Cell Institute, B-3000 Leuven, Belgium
| | - Samuel Collombet
- European Molecular Biology Laboratory (EMBL), 69117 Heidelberg, Germany
| | - Juan Song
- KU Leuven-University of Leuven, Department of Development and Regeneration, Leuven Stem Cell Institute, B-3000 Leuven, Belgium
| | - Natalie De Geest
- KU Leuven-University of Leuven, Department of Development and Regeneration, Leuven Stem Cell Institute, B-3000 Leuven, Belgium
| | - San Kit To
- KU Leuven-University of Leuven, Department of Development and Regeneration, Leuven Stem Cell Institute, B-3000 Leuven, Belgium
| | - Greet Bervoets
- Laboratory for Molecular Cancer Biology, VIB Center for Cancer Biology, KU Leuven, 3000 Leuven, Belgium.,Department of Oncology, KU Leuven, 3000 Leuven, Belgium
| | - Oskar Marin-Bejar
- Laboratory for Molecular Cancer Biology, VIB Center for Cancer Biology, KU Leuven, 3000 Leuven, Belgium.,Department of Oncology, KU Leuven, 3000 Leuven, Belgium
| | - Caterina Provenzano
- KU Leuven-University of Leuven, Department of Development and Regeneration, Leuven Stem Cell Institute, B-3000 Leuven, Belgium
| | - Lotte Vanheer
- KU Leuven-University of Leuven, Department of Development and Regeneration, Leuven Stem Cell Institute, B-3000 Leuven, Belgium
| | - Jean-Christophe Marine
- Laboratory for Molecular Cancer Biology, VIB Center for Cancer Biology, KU Leuven, 3000 Leuven, Belgium.,Department of Oncology, KU Leuven, 3000 Leuven, Belgium
| | - Florian Rambow
- Laboratory for Molecular Cancer Biology, VIB Center for Cancer Biology, KU Leuven, 3000 Leuven, Belgium.,Department of Oncology, KU Leuven, 3000 Leuven, Belgium
| | - Vincent Pasque
- KU Leuven-University of Leuven, Department of Development and Regeneration, Leuven Stem Cell Institute, B-3000 Leuven, Belgium
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7
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Song J, Janiszewski A, De Geest N, Vanheer L, Talon I, El Bakkali M, Oh T, Pasque V. X-Chromosome Dosage Modulates Multiple Molecular and Cellular Properties of Mouse Pluripotent Stem Cells Independently of Global DNA Methylation Levels. Stem Cell Reports 2019; 12:333-350. [PMID: 30639215 PMCID: PMC6372905 DOI: 10.1016/j.stemcr.2018.12.004] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2018] [Revised: 12/07/2018] [Accepted: 12/10/2018] [Indexed: 01/05/2023] Open
Abstract
Reprogramming female mouse somatic cells into induced pluripotent stem cells (iPSCs) leads to X-chromosome reactivation. The extent to which increased X-chromosome dosage (X-dosage) in female iPSCs compared with male iPSCs leads to differences in the properties of iPSCs is still unclear. We show that chromatin accessibility in mouse iPSCs is modulated by X-dosage. Specific sets of transcriptional regulator motifs are enriched in chromatin with increased accessibility in XX or XY iPSCs. The transcriptome, growth and pluripotency exit are also modulated by X-dosage in iPSCs. To understand how increased X-dosage modulates the properties of mouse pluripotent stem cells, we used heterozygous deletions of the X-linked gene Dusp9. We show that X-dosage regulates the transcriptome, open chromatin landscape, growth, and pluripotency exit largely independently of global DNA methylation. Our results provide insights into how gene dosage modulates the epigenetic and genetic mechanisms that regulate cell identity. X-chromosome dosage modulates the pluripotent chromatin accessibility landscape Increased X-chromosome dosage slows down growth Dusp9 heterozygous female ESCs display pluripotency exit delay
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Affiliation(s)
- Juan Song
- KU Leuven - University of Leuven, Department of Development and Regeneration, Leuven Stem Cell Institute, Leuven Cancer Institute, Herestraat 49, 3000 Leuven, Belgium.
| | - Adrian Janiszewski
- KU Leuven - University of Leuven, Department of Development and Regeneration, Leuven Stem Cell Institute, Leuven Cancer Institute, Herestraat 49, 3000 Leuven, Belgium
| | - Natalie De Geest
- KU Leuven - University of Leuven, Department of Development and Regeneration, Leuven Stem Cell Institute, Leuven Cancer Institute, Herestraat 49, 3000 Leuven, Belgium
| | - Lotte Vanheer
- KU Leuven - University of Leuven, Department of Development and Regeneration, Leuven Stem Cell Institute, Leuven Cancer Institute, Herestraat 49, 3000 Leuven, Belgium
| | - Irene Talon
- KU Leuven - University of Leuven, Department of Development and Regeneration, Leuven Stem Cell Institute, Leuven Cancer Institute, Herestraat 49, 3000 Leuven, Belgium
| | - Mouna El Bakkali
- KU Leuven - University of Leuven, Department of Development and Regeneration, Leuven Stem Cell Institute, Leuven Cancer Institute, Herestraat 49, 3000 Leuven, Belgium
| | - Taeho Oh
- KU Leuven - University of Leuven, Department of Development and Regeneration, Leuven Stem Cell Institute, Leuven Cancer Institute, Herestraat 49, 3000 Leuven, Belgium
| | - Vincent Pasque
- KU Leuven - University of Leuven, Department of Development and Regeneration, Leuven Stem Cell Institute, Leuven Cancer Institute, Herestraat 49, 3000 Leuven, Belgium.
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8
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Janiszewski A, Song J, Vanheer L, De Geest N, Pasque V. Dynamics of DNA Methylation Reprogramming Influenced by X Chromosome Dosage in Induced Pluripotent Stem Cells. Epigenet Insights 2018; 11:2516865718802931. [PMID: 30443643 PMCID: PMC6233964 DOI: 10.1177/2516865718802931] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Accepted: 09/03/2018] [Indexed: 11/16/2022] Open
Abstract
How the epigenome of one cell type is remodeled during reprogramming into another unrelated type of cell remains unclear. Overexpression of transcription factors in somatic cells enables the induction of induced pluripotent stem cells (iPSCs). This process entails genome-wide remodeling of DNA methylation, chromatin, and transcription. Recent work suggests that the number of active X chromosomes present in a cell influences remodeling of DNA methylation during somatic cell reprogramming to mouse iPSCs. Female iPSCs with 2 active X chromosomes display global DNA hypomethylation, whereas male XY iPSCs show DNA methylation levels similar to the somatic cells they are derived from. Global DNA methylation erasure in female iPSCs takes place genome-wide and involves repression of DNA methyltransferases. However, on loss of one X chromosome, female iPSCs acquire a DNA methylation landscape resembling that of XY iPSCs. Therefore, it is the X chromosome dosage that dictates global DNA methylation levels in iPSCs. Here, we discuss the evidence that links X chromosome dosage with the regulation of DNA methylation in pluripotent stem cells. We focus on iPSCs reprogramming studies, where X chromosome status is a novel factor impacting our understanding of epigenetic remodeling.
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Affiliation(s)
- Adrian Janiszewski
- Leuven Stem Cell Institute, Leuven Cancer Institute, Department of Development and Regeneration, KU Leuven - University of Leuven, Leuven, Belgium
| | - Juan Song
- Leuven Stem Cell Institute, Leuven Cancer Institute, Department of Development and Regeneration, KU Leuven - University of Leuven, Leuven, Belgium
| | - Lotte Vanheer
- Leuven Stem Cell Institute, Leuven Cancer Institute, Department of Development and Regeneration, KU Leuven - University of Leuven, Leuven, Belgium
| | - Natalie De Geest
- Leuven Stem Cell Institute, Leuven Cancer Institute, Department of Development and Regeneration, KU Leuven - University of Leuven, Leuven, Belgium
| | - Vincent Pasque
- Leuven Stem Cell Institute, Leuven Cancer Institute, Department of Development and Regeneration, KU Leuven - University of Leuven, Leuven, Belgium
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9
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Mora N, Oliva C, Fiers M, Ejsmont R, Soldano A, Zhang TT, Yan J, Claeys A, De Geest N, Hassan BA. A Temporal Transcriptional Switch Governs Stem Cell Division, Neuronal Numbers, and Maintenance of Differentiation. Dev Cell 2018; 45:53-66.e5. [DOI: 10.1016/j.devcel.2018.02.023] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2017] [Revised: 02/12/2018] [Accepted: 02/26/2018] [Indexed: 01/06/2023]
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10
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Weinberger S, Topping MP, Yan J, Claeys A, Geest ND, Ozbay D, Hassan T, He X, Albert JT, Hassan BA, Ramaekers A. Evolutionary changes in transcription factor coding sequence quantitatively alter sensory organ development and function. eLife 2017; 6. [PMID: 28406397 PMCID: PMC5432213 DOI: 10.7554/elife.26402] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Accepted: 03/27/2017] [Indexed: 11/16/2022] Open
Abstract
Animals are characterized by a set of highly conserved developmental regulators. Changes in the cis-regulatory elements of these regulators are thought to constitute the major driver of morphological evolution. However, the role of coding sequence evolution remains unresolved. To address this question, we used the Atonal family of proneural transcription factors as a model. Drosophila atonal coding sequence was endogenously replaced with that of atonal homologues (ATHs) at key phylogenetic positions, non-ATH proneural genes, and the closest homologue to ancestral proneural genes. ATHs and the ancestral-like coding sequences rescued sensory organ fate in atonal mutants, in contrast to non-ATHs. Surprisingly, different ATH factors displayed different levels of proneural activity as reflected by the number and functionality of sense organs. This proneural potency gradient correlated directly with ATH protein stability, including in response to Notch signaling, independently of mRNA levels or codon usage. This establishes a distinct and ancient function for ATHs and demonstrates that coding sequence evolution can underlie quantitative variation in sensory development and function. DOI:http://dx.doi.org/10.7554/eLife.26402.001
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Affiliation(s)
- Simon Weinberger
- VIB Center for the Biology of Disease, VIB, Leuven, Belgium.,Center for Human Genetics, University of Leuven School of Medicine, Leuven, Belgium.,Program in Molecular and Developmental Genetics, Doctoral School for Biomedical Sciences, University of Leuven School Group Biomedicine, Leuven, Belgium
| | - Matthew P Topping
- Ear Institute, University College London, London, United Kingdom.,Centre for Mathematics and Physics in the Life Sciences and Experimental Biology (CoMPLEX), University College London, London, United Kingdom
| | - Jiekun Yan
- VIB Center for the Biology of Disease, VIB, Leuven, Belgium.,Center for Human Genetics, University of Leuven School of Medicine, Leuven, Belgium
| | - Annelies Claeys
- VIB Center for the Biology of Disease, VIB, Leuven, Belgium.,Center for Human Genetics, University of Leuven School of Medicine, Leuven, Belgium
| | - Natalie De Geest
- VIB Center for the Biology of Disease, VIB, Leuven, Belgium.,Center for Human Genetics, University of Leuven School of Medicine, Leuven, Belgium
| | - Duru Ozbay
- VIB Center for the Biology of Disease, VIB, Leuven, Belgium.,Center for Human Genetics, University of Leuven School of Medicine, Leuven, Belgium
| | - Talah Hassan
- Ear Institute, University College London, London, United Kingdom
| | - Xiaoli He
- Ear Institute, University College London, London, United Kingdom
| | - Joerg T Albert
- Ear Institute, University College London, London, United Kingdom.,Centre for Mathematics and Physics in the Life Sciences and Experimental Biology (CoMPLEX), University College London, London, United Kingdom.,Department of Cell and Developmental Biology, University College London, London, United Kingdom
| | - Bassem A Hassan
- VIB Center for the Biology of Disease, VIB, Leuven, Belgium.,Center for Human Genetics, University of Leuven School of Medicine, Leuven, Belgium.,Program in Molecular and Developmental Genetics, Doctoral School for Biomedical Sciences, University of Leuven School Group Biomedicine, Leuven, Belgium.,Institut du Cerveau et de la Moelle Epinière (ICM) - Hôpital Pitié-Salpêtrière, UPMC, Sorbonne Universités, Inserm, CNRS, Paris, France
| | - Ariane Ramaekers
- VIB Center for the Biology of Disease, VIB, Leuven, Belgium.,Center for Human Genetics, University of Leuven School of Medicine, Leuven, Belgium.,Institut du Cerveau et de la Moelle Epinière (ICM) - Hôpital Pitié-Salpêtrière, UPMC, Sorbonne Universités, Inserm, CNRS, Paris, France
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11
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Yuan L, Hu S, Okray Z, Ren X, De Geest N, Claeys A, Yan J, Bellefroid E, Hassan BA, Quan XJ. The Drosophila neurogenin Tap functionally interacts with the Wnt-PCP pathway to regulate neuronal extension and guidance. Development 2016; 143:2760-6. [PMID: 27385016 PMCID: PMC5004907 DOI: 10.1242/dev.134155] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2015] [Accepted: 06/27/2016] [Indexed: 11/20/2022]
Abstract
The neurogenin (Ngn) transcription factors control early neurogenesis and neurite outgrowth in mammalian cortex. In contrast to their proneural activity, their function in neurite growth is poorly understood. Drosophila has a single predicted Ngn homolog, Tap, of unknown function. Here we show that Tap is not a proneural protein in Drosophila but is required for proper axonal growth and guidance of neurons of the mushroom body, a neuropile required for associative learning and memory. Genetic and expression analyses suggest that Tap inhibits excessive axonal growth by fine regulation of the levels of the Wnt signaling adaptor protein Dishevelled. Summary: Mammalian neurogenins are proneural factors, but the Drosophila homolog Tap is not, instead acting to prevent axonal outgrowth, likely by regulating the planar cell polarity pathway via Dishevelled.
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Affiliation(s)
- Liqun Yuan
- VIB Center for the Biology of Disease, VIB, Leuven 3000, Belgium Center for Human Genetics, University of Leuven School of Medicine, Leuven 3000, Belgium Program in Molecular and Developmental Genetics, Doctoral School for Biomedical Sciences, University of Leuven School of Medicine, Leuven 3000, Belgium
| | - Shu Hu
- VIB Center for the Biology of Disease, VIB, Leuven 3000, Belgium Center for Human Genetics, University of Leuven School of Medicine, Leuven 3000, Belgium Program in Molecular and Developmental Genetics, Doctoral School for Biomedical Sciences, University of Leuven School of Medicine, Leuven 3000, Belgium Medical College, Henan University of Science and Technology, Luoyang, Henan Province 471003, China
| | - Zeynep Okray
- VIB Center for the Biology of Disease, VIB, Leuven 3000, Belgium Center for Human Genetics, University of Leuven School of Medicine, Leuven 3000, Belgium Program in Molecular and Developmental Genetics, Doctoral School for Biomedical Sciences, University of Leuven School of Medicine, Leuven 3000, Belgium
| | - Xi Ren
- Laboratoire de Génétique du Développement, Université Libre de Bruxelles, Institut de Biologie et de Médecine Moléculaires (IBMM), Gosselies 6041, Belgium
| | - Natalie De Geest
- VIB Center for the Biology of Disease, VIB, Leuven 3000, Belgium Center for Human Genetics, University of Leuven School of Medicine, Leuven 3000, Belgium
| | - Annelies Claeys
- VIB Center for the Biology of Disease, VIB, Leuven 3000, Belgium Center for Human Genetics, University of Leuven School of Medicine, Leuven 3000, Belgium
| | - Jiekun Yan
- VIB Center for the Biology of Disease, VIB, Leuven 3000, Belgium Center for Human Genetics, University of Leuven School of Medicine, Leuven 3000, Belgium
| | - Eric Bellefroid
- Laboratoire de Génétique du Développement, Université Libre de Bruxelles, Institut de Biologie et de Médecine Moléculaires (IBMM), Gosselies 6041, Belgium
| | - Bassem A Hassan
- VIB Center for the Biology of Disease, VIB, Leuven 3000, Belgium Center for Human Genetics, University of Leuven School of Medicine, Leuven 3000, Belgium Program in Molecular and Developmental Genetics, Doctoral School for Biomedical Sciences, University of Leuven School of Medicine, Leuven 3000, Belgium
| | - Xiao-Jiang Quan
- VIB Center for the Biology of Disease, VIB, Leuven 3000, Belgium Center for Human Genetics, University of Leuven School of Medicine, Leuven 3000, Belgium
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12
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Zschätzsch M, Oliva C, Langen M, De Geest N, Ozel MN, Williamson WR, Lemon WC, Soldano A, Munck S, Hiesinger PR, Sanchez-Soriano N, Hassan BA. Regulation of branching dynamics by axon-intrinsic asymmetries in Tyrosine Kinase Receptor signaling. eLife 2014; 3:e01699. [PMID: 24755286 PMCID: PMC3990184 DOI: 10.7554/elife.01699] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Axonal branching allows a neuron to connect to several targets, increasing neuronal circuit complexity. While axonal branching is well described, the mechanisms that control it remain largely unknown. We find that in the Drosophila CNS branches develop through a process of excessive growth followed by pruning. In vivo high-resolution live imaging of developing brains as well as loss and gain of function experiments show that activation of Epidermal Growth Factor Receptor (EGFR) is necessary for branch dynamics and the final branching pattern. Live imaging also reveals that intrinsic asymmetry in EGFR localization regulates the balance between dynamic and static filopodia. Elimination of signaling asymmetry by either loss or gain of EGFR function results in reduced dynamics leading to excessive branch formation. In summary, we propose that the dynamic process of axon branch development is mediated by differential local distribution of signaling receptors. DOI:http://dx.doi.org/10.7554/eLife.01699.001 In the human brain, 100 billion neurons form 100 trillion connections. Each neuron consists of a cell body with numerous small branch-like projections known as dendrites (from the Greek word for ‘tree’), plus a long cable-like structure called the axon. Neurons receive electrical inputs from neighboring cells via their dendrites, and then relay these signals onto other cells in their network via their axons. The development of the brain relies on new neurons integrating successfully into existing networks. Axon branching helps with this by enabling a single neuron to establish connections with several cells, but it is unclear how individual neurons decide when and where to form branches. Now, Zschätzsch et al. have revealed the mechanism behind this process in the fruit fly, Drosophila. Mutant flies that lack a protein called EGFR produce abnormal numbers of axon branches, suggesting that this molecule regulates branch formation. Indeed in fruit flies, just as in mammals, the developing brain initially produces excessive numbers of branches, which are subsequently pruned to leave only those that have formed appropriate connections. In Drosophila, an uneven distribution of EGFR between branches belonging to the same axon acts as a signal to regulate this pruning process. To examine this mechanism in more detail, high-resolution four-dimensional imaging was used to study brains that had been removed from Drosophila pupae and kept alive in special culture chambers. Axon branching and loss could now be followed in real time, and were found to occur more slowly in brains that lacked EGFR. The receptor controlled the branching of axons by influencing the distribution of another protein called actin, which is a key component of the internal skeleton that gives cells their structure. In addition to providing new insights into a fundamental aspect of brain development, the work of Zschätzsch et al. also highlights the importance of stochastic events in shaping the network of connections within the developing brain. These findings may well be relevant to ongoing efforts to map the human brain ‘connectome’. DOI:http://dx.doi.org/10.7554/eLife.01699.002
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Affiliation(s)
- Marlen Zschätzsch
- Center for the Biology of Disease, Vlaams Instituut voor Biotechnologie, Leuven, Belgium
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13
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Oliva C, Choi CM, Nicolai LJJ, Mora N, De Geest N, Hassan BA. Proper connectivity of Drosophila motion detector neurons requires Atonal function in progenitor cells. Neural Dev 2014; 9:4. [PMID: 24571981 PMCID: PMC3941608 DOI: 10.1186/1749-8104-9-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2013] [Accepted: 02/13/2014] [Indexed: 01/15/2023] Open
Abstract
Background Vertebrates and invertebrates obtain visual motion information by channeling moving visual cues perceived by the retina through specific motion sensitive synaptic relays in the brain. In Drosophila, the series of synaptic relays forming the optic lobe are known as the lamina, medulla, lobula and lobula plate neuropiles. The fly’s motion detection output neurons, called the T4 and T5 cells, reside in the lobula plate. Adult optic lobe neurons are derived from larval neural progenitors in two proliferating compartments known as the outer and inner proliferation centers (OPC and IPC). Important insight has been gained into molecular mechanisms involved in the development of the lamina and medulla from the OPC, though less is known about the development of the lobula and lobula plate. Results Here we show that the proneural gene Atonal is expressed in a subset of IPC progenitors that give rise to the higher order motion detection neurons, T4 and T5, of the lobula plate. We also show that Atonal does not act as a proneural gene in this context. Rather, it is required specifically in IPC neural progenitors to regulate neurite outgrowth in the neuronal progeny. Conclusions Our findings reveal that a proneural gene is expressed in progenitors but is required for neurite development of their progeny neurons. This suggests that transcriptional programs initiated specifically in progenitors are necessary for subsequent neuronal morphogenesis.
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Affiliation(s)
| | | | | | | | | | - Bassem A Hassan
- VIB Center for Biology of Disease, VIB, 3000 Leuven, Belgium.
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14
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Langen M, Koch M, Yan J, De Geest N, Erfurth ML, Pfeiffer BD, Schmucker D, Moreau Y, Hassan BA. Mutual inhibition among postmitotic neurons regulates robustness of brain wiring in Drosophila. eLife 2013; 2:e00337. [PMID: 23471010 PMCID: PMC3589824 DOI: 10.7554/elife.00337] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2012] [Accepted: 01/22/2013] [Indexed: 11/13/2022] Open
Abstract
Brain connectivity maps display a delicate balance between individual variation and stereotypy, suggesting the existence of dedicated mechanisms that simultaneously permit and limit individual variation. We show that during the development of the Drosophila central nervous system, mutual inhibition among groups of neighboring postmitotic neurons during development regulates the robustness of axon target choice in a nondeterministic neuronal circuit. Specifically, neighboring postmitotic neurons communicate through Notch signaling during axonal targeting, to ensure balanced alternative axon target choices without a corresponding change in cell fate. Loss of Notch in postmitotic neurons modulates an axon's target choice. However, because neighboring axons respond by choosing the complementary target, the stereotyped connectivity pattern is preserved. In contrast, loss of Notch in clones of neighboring postmitotic neurons results in erroneous coinnervation by multiple axons. Our observations establish mutual inhibition of axonal target choice as a robustness mechanism for brain wiring and unveil a novel cell fate independent function for canonical Notch signaling. DOI:http://dx.doi.org/10.7554/eLife.00337.001.
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Affiliation(s)
- Marion Langen
- Center for the Biology of Disease , VIB , Leuven , Belgium ; Center for Human Genetics , University of Leuven School of Medicine , Leuven , Belgium ; Doctoral Program in Molecular and Cognitive Neuroscience, Doctoral School of Biomedical Sciences , University of Leuven , Leuven , Belgium
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15
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Van Keymeulen A, Mascre G, Youseff KK, Harel I, Michaux C, De Geest N, Szpalski C, Achouri Y, Bloch W, Hassan BA, Blanpain C. Epidermal progenitors give rise to Merkel cells during embryonic development and adult homeostasis. J Exp Med 2009. [DOI: 10.1084/jem20611oia26] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
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16
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Van Keymeulen A, Mascre G, Youseff KK, Harel I, Michaux C, De Geest N, Szpalski C, Achouri Y, Bloch W, Hassan BA, Blanpain C. Epidermal progenitors give rise to Merkel cells during embryonic development and adult homeostasis. ACTA ACUST UNITED AC 2009; 187:91-100. [PMID: 19786578 PMCID: PMC2762088 DOI: 10.1083/jcb.200907080] [Citation(s) in RCA: 187] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Lineage-tracing experiments show that the origin of specialized mechanosensory Merkel cells in the skin is epidermal progenitors, not the neural crest. Merkel cells (MCs) are located in the touch-sensitive area of the epidermis and mediate mechanotransduction in the skin. Whether MCs originate from embryonic epidermal or neural crest progenitors has been a matter of intense controversy since their discovery >130 yr ago. In addition, how MCs are maintained during adulthood is currently unknown. In this study, using lineage-tracing experiments, we show that MCs arise through the differentiation of epidermal progenitors during embryonic development. In adults, MCs undergo slow turnover and are replaced by cells originating from epidermal stem cells, not through the proliferation of differentiated MCs. Conditional deletion of the Atoh1/Math1 transcription factor in epidermal progenitors results in the absence of MCs in all body locations, including the whisker region. Our study demonstrates that MCs arise from the epidermis by an Atoh1-dependent mechanism and opens new avenues for study of MC functions in sensory perception, neuroendocrine signaling, and MC carcinoma.
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Affiliation(s)
- Alexandra Van Keymeulen
- Institut de Recherche Interdisciplinaire en Biologie Humaine et Moléculaire, Université Libre de Bruxelles, Brussels B-1070, Belgium
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17
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Abstract
Most genes function at multiple stages of metazoan development, in dividing and nondividing cells. Generating mouse conditional knock-outs (cKO), where a gene can be eliminated in a temporally and spatially controlled manner, is a valuable technique because it allows study of gene function at any stage of life. In contrast and despite the development of many other powerful genetic tools, cKO has thus far been lacking in Drosophila. We combined several recent molecular and genetic technical advances in an approach termed integrase-mediated approach for gene knock-out (IMAGO). IMAGO allows the replacement of any genomic sequence, such as a gene, with another desired sequence, including cKO alleles that can be used to create positively marked mutant cells. IMAGO should also be applicable to other genetic model organisms.
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Affiliation(s)
- Ching Man Choi
- Department of Molecular and Developmental Genetics, VIB 3000 Leuven, Belgium
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18
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Bury FJ, Moers V, Yan J, Souopgui J, Quan XJ, De Geest N, Kricha S, Hassan BA, Bellefroid EJ. Xenopus BTBD6 and its Drosophila homologue lute are required for neuronal development. Dev Dyn 2009; 237:3352-60. [PMID: 18855900 DOI: 10.1002/dvdy.21748] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
BBP proteins constitute a subclass of CUL3 interacting BTB proteins whose in vivo function remains unknown. Here, we show that the Xenopus BBP gene BTBD6 and the single Drosophila homologue of mammalian BBP genes lute are strongly expressed in the developing nervous system. In Xenopus, BTBD6 expression responds positively to proneural and negatively to neurogenic gene overexpression. Knockdown of BTBD6 in Xenopus or loss of Drosophila lute result in embryos with strong defects in late neuronal markers and strongly reduced and disorganized axons while early neural development is unaffected. XBTBD6 knockdown in Xenopus also affects muscle development. Together, these data indicate that BTBD6/lute is required for proper embryogenesis and plays an essential evolutionary conserved role during neuronal development.
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Affiliation(s)
- Frédéric J Bury
- Laboratoire d'Embryologie Moléculaire, IBMM, Université Libre de Bruxelles, Gosselies, Belgium
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19
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D'Hulst C, Heulens I, Brouwer JR, Willemsen R, De Geest N, Reeve SP, De Deyn PP, Hassan BA, Kooy RF. Expression of the GABAergic system in animal models for fragile X syndrome and fragile X associated tremor/ataxia syndrome (FXTAS). Brain Res 2008; 1253:176-83. [PMID: 19070606 DOI: 10.1016/j.brainres.2008.11.075] [Citation(s) in RCA: 134] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2008] [Revised: 11/13/2008] [Accepted: 11/18/2008] [Indexed: 11/20/2022]
Abstract
After our initial discovery of reduced expression of several subunits of the GABA(A) receptor in two different animal models for fragile X syndrome, a frequent form of inherited mental retardation, we analyzed further components of the GABAergic pathway. Interestingly, we found a down regulation of many additional elements of the GABA signalling system, strengthening our hypothesis of involvement of the GABAergic pathway in the pathophysiology of fragile X syndrome. This is of special interest with regard to new therapeutic opportunities for treatment of this disorder. Remarkably, under expression was predominantly observed in cortex, although some elements of the GABAergic system that are expressed presynaptically or in the glial cells were also down regulated in the cerebellum. Additionally, we assessed the GABAergic system in expanded CGG-repeat mice, a model for fragile X associated tremor/ataxia syndrome (FXTAS). This late onset neurodegenerative disorder occurs in carriers of the fragile X premutation (55-200 CGG repeats) and is completely distinct (from both clinical and molecular pathogenic perspectives) from the neurodevelopmental disorder fragile X syndrome. Here we found upregulation of many components of the GABAergic system in cerebellum, but not in cortex. This finding is consistent with the cerebellar phenotype of FXTAS patients and has implications for the mechanism causative of differential gene expression.
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Affiliation(s)
- Charlotte D'Hulst
- Department of Medical Genetics, University of Antwerp, Universiteitsplein 1, Antwerp, Belgium
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D'Hulst C, De Geest N, Reeve SP, Van Dam D, De Deyn PP, Hassan BA, Kooy RF. Decreased expression of the GABAA receptor in fragile X syndrome. Brain Res 2006; 1121:238-45. [PMID: 17046729 DOI: 10.1016/j.brainres.2006.08.115] [Citation(s) in RCA: 255] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2006] [Revised: 08/28/2006] [Accepted: 08/28/2006] [Indexed: 11/23/2022]
Abstract
After our initial discovery of under expression of the GABA(A) receptor delta subunit in a genome wide screening for differentially expressed mRNAs in brain of fragile X mice, a validated model for fragile X mental retardation syndrome, we analyzed expression of the 17 remaining subunits of the GABA(A) receptor using real-time PCR. We confirmed nearly 50% under expression of the delta subunit and found a significant 35%-50% reduction in expression of 7 additional subunit mRNAs, namely alpha(1), alpha(3), and alpha(4), beta(1) and beta(2) and gamma(1) and gamma(2), in fragile X mice compared to wild-type littermates. In concordance with previous results, under expression was found in cortex, but not in cerebellum. Moreover, decreased expression of specific GABA(A) receptor subunits in fragile X syndrome seems to be an evolutionary conserved hallmark since in the fragile X fly (Drosophila melanogaster) model we also found almost 50% under expression of all 3 subunits which make up the invertebrate GABA receptor, namely Grd, Rdl and Lcch3. In addition, we demonstrated a direct correlation between the amount of dFmrp and the expression of the GABA receptor subunits Rdl and Grd. Our results add evidence to previous observations of an altered GABAergic system in fragile X syndrome. Because GABA(A) receptors are the major inhibitory receptors in brain, involved in anxiety, depression, insomnia, learning and memory and epilepsy, processes also disturbed in fragile X patients, the well described GABA(A) receptor pharmacology might open new powerful opportunities for treatment of the behavioral and epileptic phenotype associated with fragile X syndrome.
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Affiliation(s)
- Charlotte D'Hulst
- Department of Medical Genetics, University of Antwerp, Universiteitsplein 1, 2610 Antwerp, Belgium
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Abstract
Glycopeptides were isolated from functional units of two molluscan hemocyanins (Hcs). They were analyzed and localized in the sequences. A comparison with potential N-glycosylation sites of two other molluscan Hcs was made. An immunological cross-reactivity was observed between the beta-Hc and the alpha-macroglobulin of Helix pomotia. ELISA experiments with glycopeptide fractions indicated a competition.
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Affiliation(s)
- Constant Gielens
- Laboratory of Biochemistry, Department of Chemistry, Katholieke Universiteit Leuven, B-3001 Leuven, Belgium.
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