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Fogarty EA, Buchert EM, Ma Y, Nicely AB, Buttitta LA. Transcriptional repression and enhancer decommissioning silence cell cycle genes in postmitotic tissues. G3 (BETHESDA, MD.) 2024; 14:jkae203. [PMID: 39171889 PMCID: PMC11457063 DOI: 10.1093/g3journal/jkae203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2024] [Accepted: 08/16/2024] [Indexed: 08/23/2024]
Abstract
The mechanisms that maintain a non-cycling status in postmitotic tissues are not well understood. Many cell cycle genes have promoters and enhancers that remain accessible even when cells are terminally differentiated and in a non-cycling state, suggesting their repression must be maintained long term. In contrast, enhancer decommissioning has been observed for rate-limiting cell cycle genes in the Drosophila wing, a tissue where the cells die soon after eclosion, but it has been unclear if this also occurs in other contexts of terminal differentiation. In this study, we show that enhancer decommissioning also occurs at specific, rate-limiting cell cycle genes in the long-lived tissues of the Drosophila eye and brain, and we propose this loss of chromatin accessibility may help maintain a robust postmitotic state. We examined the decommissioned enhancers at specific rate-limiting cell cycle genes and showed that they encode for dynamic temporal and spatial expression patterns that include shared, as well as tissue-specific elements, resulting in broad gene expression with developmentally controlled temporal regulation. We extend our analysis to cell cycle gene expression and chromatin accessibility in the mammalian retina using a published dataset and find that the principles of cell cycle gene regulation identified in terminally differentiating Drosophila tissues are conserved in the differentiating mammalian retina. We propose a robust, non-cycling status is maintained in long-lived postmitotic tissues through a combination of stable repression at most cell cycle genes, alongside enhancer decommissioning at specific rate-limiting cell cycle genes.
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Affiliation(s)
- Elizabeth A Fogarty
- Molecular, Cellular and Developmental Biology, University of Michigan, 1105 N. University Ave., Ann Arbor, MI 48109, USA
| | - Elli M Buchert
- Molecular, Cellular and Developmental Biology, University of Michigan, 1105 N. University Ave., Ann Arbor, MI 48109, USA
| | - Yiqin Ma
- Molecular, Cellular and Developmental Biology, University of Michigan, 1105 N. University Ave., Ann Arbor, MI 48109, USA
| | - Ava B Nicely
- Molecular, Cellular and Developmental Biology, University of Michigan, 1105 N. University Ave., Ann Arbor, MI 48109, USA
| | - Laura A Buttitta
- Molecular, Cellular and Developmental Biology, University of Michigan, 1105 N. University Ave., Ann Arbor, MI 48109, USA
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Dou Y, Fei X, He X, Huan Y, Wei J, Wu X, Lyu W, Fei Z, Li X, Fei F. Homer1a reduces inflammatory response after retinal ischemia/reperfusion injury. Neural Regen Res 2024; 19:1608-1617. [PMID: 38051906 PMCID: PMC10883521 DOI: 10.4103/1673-5374.386490] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2023] [Accepted: 08/25/2023] [Indexed: 12/07/2023] Open
Abstract
Abstract
JOURNAL/nrgr/04.03/01300535-202407000-00042/figure1/v/2023-11-20T171125Z/r/image-tiff
Elevated intraocular pressure (IOP) is one of the causes of retinal ischemia/reperfusion injury, which results in NLRP3 inflammasome activation and leads to visual damage. Homer1a is reported to play a protective role in neuroinflammation in the cerebrum. However, the effects of Homer1a on NLRP3 inflammasomes in retinal ischemia/reperfusion injury caused by elevated IOP remain unknown. In our study, animal models were constructed using C57BL/6J and Homer1flox/
–/Homer1a+/
–/Nestin-Cre+/
– mice with elevated IOP-induced retinal ischemia/reperfusion injury. For in vitro experiments, the oxygen-glucose deprivation/reperfusion injury model was constructed with Müller cells. We found that Homer1a overexpression ameliorated the decreases in retinal thickness and Müller cell viability after ischemia/reperfusion injury. Furthermore, Homer1a knockdown promoted NF-κB P65Ser536 activation via caspase-8, NF-κB P65 nuclear translocation, NLRP3 inflammasome formation, and the production and processing of interleukin-1β and interleukin-18. The opposite results were observed with Homer1a overexpression. Finally, the combined administration of Homer1a protein and JSH-23 significantly inhibited the reduction in retinal thickness in Homer1flox/
–/Homer1a+/
–/Nestin-Cre+/
– mice and apoptosis in Müller cells after ischemia/reperfusion injury. Taken together, these studies demonstrate that Homer1a exerts protective effects on retinal tissue and Müller cells via the caspase-8/NF-κB P65/NLRP3 pathway after I/R injury.
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Affiliation(s)
- Yanan Dou
- Department of Neurosurgery, Xijing Hospital, Air Force Military Medical University, Xi'an, Shaanxi Province, China
| | - Xiaowei Fei
- Department of Neurosurgery, Xijing Hospital, Air Force Military Medical University, Xi'an, Shaanxi Province, China
| | - Xin He
- Department of Neurosurgery, Xijing Hospital, Air Force Military Medical University, Xi'an, Shaanxi Province, China
| | - Yu Huan
- Department of Neurosurgery, Xijing Hospital, Air Force Military Medical University, Xi'an, Shaanxi Province, China
| | - Jialiang Wei
- Department of Neurosurgery, Xijing Hospital, Air Force Military Medical University, Xi'an, Shaanxi Province, China
| | - Xiuquan Wu
- Department of Neurosurgery, Xijing Hospital, Air Force Military Medical University, Xi'an, Shaanxi Province, China
| | - Weihao Lyu
- Department of Neurosurgery, Xijing Hospital, Air Force Military Medical University, Xi'an, Shaanxi Province, China
| | - Zhou Fei
- Department of Neurosurgery, Xijing Hospital, Air Force Military Medical University, Xi'an, Shaanxi Province, China
| | - Xia Li
- Department of Neurosurgery, Xijing Hospital, Air Force Military Medical University, Xi'an, Shaanxi Province, China
| | - Fei Fei
- Department of Ophthalmology, Xijing Hospital, Air Force Military Medical University, Xi'an, Shaanxi Province, China
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Fogarty EA, Buchert EM, Ma Y, Nicely AB, Buttitta LA. Transcriptional repression and enhancer decommissioning silence cell cycle genes in postmitotic tissues. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.06.592773. [PMID: 38766255 PMCID: PMC11100713 DOI: 10.1101/2024.05.06.592773] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2024]
Abstract
The mechanisms that maintain a non-cycling status in postmitotic tissues are not well understood. Many cell cycle genes have promoters and enhancers that remain accessible even when cells are terminally differentiated and in a non-cycling state, suggesting their repression must be maintained long term. In contrast, enhancer decommissioning has been observed for rate-limiting cell cycle genes in the Drosophila wing, a tissue where the cells die soon after eclosion, but it has been unclear if this also occurs in other contexts of terminal differentiation. In this study, we show that enhancer decommissioning also occurs at specific, rate-limiting cell cycle genes in the long-lived tissues of the Drosophila eye and brain, and we propose this loss of chromatin accessibility may help maintain a robust postmitotic state. We examined the decommissioned enhancers at specific rate-limiting cell cycle genes and show that they encode dynamic temporal and spatial expression patterns that include shared, as well as tissue-specific elements, resulting in broad gene expression with developmentally controlled temporal regulation. We extend our analysis to cell cycle gene expression and chromatin accessibility in the mammalian retina using a published dataset, and find that the principles of cell cycle gene regulation identified in terminally differentiating Drosophila tissues are conserved in the differentiating mammalian retina. We propose a robust, non-cycling status is maintained in long-lived postmitotic tissues through a combination of stable repression at most cell cycle gens, alongside enhancer decommissioning at specific rate-limiting cell cycle genes.
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Affiliation(s)
- Elizabeth A. Fogarty
- Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor 48109
| | - Elli M. Buchert
- Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor 48109
| | - Yiqin Ma
- Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor 48109
| | - Ava B. Nicely
- Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor 48109
| | - Laura A. Buttitta
- Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor 48109
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Saadh MJ, Castillo-Acobo RY, Baher H, Narayanan J, Palacios Garay JP, Yamaguchi MNV, Arias-Gonzáles JL, Cotrina-Aliaga JC, Akram SV, Lakshmaiya N, Amin AH, Mohany M, Al-Rejaie SS, Ahsan M, Bahrami A, Akhavan-Sigari R. The protective role of sulforaphane and Homer1a in retinal ischemia-reperfusion injury: Unraveling the neuroprotective interplay. Life Sci 2023; 329:121968. [PMID: 37487941 DOI: 10.1016/j.lfs.2023.121968] [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: 05/29/2023] [Revised: 07/10/2023] [Accepted: 07/18/2023] [Indexed: 07/26/2023]
Abstract
AIMS Retinal ischemia/reperfusion (I/R) injury is a common pathological basis for various ophthalmic diseases. This study aimed to investigate the potential of sulforaphane (SFN) and Homer1a in regulating cell apoptosis induced by retinal I/R injury and to explore the underlying regulatory mechanism between them. MATERIALS AND METHODS In in vivo experiments, C57BL/6J mice and Homer1flox/-/Homer1a+/-/Nestin-Cre+/- mice were used to construct retinal I/R injury models. In vitro experiments utilized the oxygen-glucose deprivation-reperfusion (OGD/R) injury model with primary retinal ganglion cells (RGCs). The effects of Homer1a and SFN on cell apoptosis were observed through pathological analyses, flow cytometry, and visual electrophysiological assessments. KEY FINDINGS We discovered that after OGD/R injury, apoptosis of RGCs and intracellular Ca2+ activity significantly increased. However, these changes were reversed upon the addition of SFN, and similar observations were reproduced in in vivo studies. Furthermore, both in vivo and in vitro studies confirmed the upregulation of Homer1a after I/R, which could be further enhanced by the administration of SFN. Moreover, upregulation of Homer1a resulted in a reduction in cell apoptosis and pro-apoptotic proteins, while downregulation of Homer1a had the opposite effect. Flash visual evoked potential, oscillatory potentials, and escape latency measurements in mice supported these findings. Furthermore, the addition of SFN strengthened the neuroprotective effects in the OGD/R + H+ group but weakened them in Homer1flox/-/Homer1a+/-/Nestin-Cre+/- mice. SIGNIFICANCE These results indicate that Homer1a plays a significant role in the therapeutic potential of sulforaphane for retinal I/R injury, thereby providing a theoretical basis for clinical treatment.
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Affiliation(s)
- Mohamed J Saadh
- Faculty of Pharmacy, Middle East University, Amman 11831, Jordan; Applied Science Research Center, Applied Science Private University, Amman 11152, Jordan
| | | | - Hala Baher
- Department of Radiology and Ultrasonography Techniques, College of Medical Techniques, Al-Farahidi University, Baghdad, Iraq
| | | | | | | | - José Luis Arias-Gonzáles
- Department of Social Sciences, Faculty of Social Studies, University of British Columbia, BC, Canada
| | | | - Shaik Vaseem Akram
- Uttaranchal Institute of Technology, Division of research and Innovation, Uttaranchal University, Dehradun, India
| | - Natrayan Lakshmaiya
- Department of Mechanical Engineering, Saveetha School of Engineering, SRM Institute of Science and Technology, Chennai, Tamil Nadu, India
| | - Ali H Amin
- Zoology Department, Faculty of Science, Mansoura University, Mansoura 35516, Egypt
| | - Mohamed Mohany
- Department of Pharmacology and Toxicology, College of Pharmacy, King Saud University, P.O. Box 55760, Riyadh 11451, Saudi Arabia
| | - Salim S Al-Rejaie
- Department of Pharmacology and Toxicology, College of Pharmacy, King Saud University, P.O. Box 55760, Riyadh 11451, Saudi Arabia
| | - Muhammad Ahsan
- Department of Measurements and Control Systems, Silesian University of Technology, Gliwice, 44-100, Poland; Joint Doctoral School, Silesian University of Technology, Akademicka 2A, Gliwice, 44-100, Poland.
| | - Abolfazl Bahrami
- Department of Cell Biology, Tuebingen University, Tuebingen, Germany; Biomedical Center for Systems Biology Science Munich, Ludwig-Maximilians-University, Munich, Germany.
| | - Reza Akhavan-Sigari
- Department of Health Care Management and Clinical Research, Collegium Humanum Warsaw, Poland; Department of Neurosurgery, University Medical Center Tuebingen, Germany
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Collin J, Queen R, Zerti D, Steel DH, Bowen C, Parulekar M, Lako M. Dissecting the Transcriptional and Chromatin Accessibility Heterogeneity of Proliferating Cone Precursors in Human Retinoblastoma Tumors by Single Cell Sequencing-Opening Pathways to New Therapeutic Strategies? Invest Ophthalmol Vis Sci 2021; 62:18. [PMID: 34003213 PMCID: PMC8132003 DOI: 10.1167/iovs.62.6.18] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Accepted: 04/18/2021] [Indexed: 01/03/2023] Open
Abstract
Purpose Retinoblastoma (Rb) is a malignant neoplasm arising during retinal development from mutations in the RB1 gene. Loss or inactivation of both copies of RB1 results in initiation of retinoblastoma tumors; however, additional genetic changes are needed for the continued growth and spread of the tumor. Ex vivo research has shown that in humans, retinoblastoma may initiate from RB1-depleted cone precursors. Notwithstanding, it has not been possible to assess the full spectrum of clonal types within the tumor itself in vivo and the molecular changes occurring at the cells of origin, enabling their malignant conversion. To overcome these challenges, we have performed the first single cell (sc) RNA- and ATAC-Seq analyses of primary tumor tissues, enabling us to dissect the transcriptional and chromatin accessibility heterogeneity of proliferating cone precursors in human Rb tumors. Methods Two Rb tumors each characterized by two pathogenic RB1 mutations were dissociated to single cells and subjected to scRNA-Seq and scATAC-Seq using the 10× Genomics platform. In addition, nine human embryonic and fetal retina samples were dissociated to single cells and subjected to scRNA- and ATAC-Seq analyses. The scRNA- and ATAC-Seq data were embedded using Uniform Manifold Approximation and Projection and clustered with Seurat graph-based clustering. Integrated scATAC-Seq analysis of Rb tumors and human embryonic/fetal retina samples was performed to identify Rb cone enriched subclusters. Pseudo time analysis of proliferating cones in the Rb samples was performed with Monocle. Ingenuity Pathway Analysis was used to identify the signaling pathway and upstream regulators in the Rb cone-enriched subclusters. Results Our single cell analyses revealed the predominant presence of cone precursors at different stages of the cell cycle in the Rb tumors and among those identified the G2/M subset as the cell type of origin. scATAC-Seq analysis identified two Rb enriched cone subclusters, each characterized by activation of different upstream regulators and signaling pathways, enabling proliferating cone precursors to escape cell cycle arrest and/or apoptosis. Conclusions Our study provides evidence of Rb tumor heterogeneity and defines molecular pathways that can be targeted to define new treatment strategies.
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Affiliation(s)
- Joseph Collin
- Biosciences Institute, Newcastle University, Newcastle, United Kingdom
| | - Rachel Queen
- Biosciences Institute, Newcastle University, Newcastle, United Kingdom
| | - Darin Zerti
- Biosciences Institute, Newcastle University, Newcastle, United Kingdom
| | - David H Steel
- Biosciences Institute, Newcastle University, Newcastle, United Kingdom
| | - Claire Bowen
- Birmingham Women's and Children NHS Foundation Trust, Birmingham, United Kingdom
| | - Manoj Parulekar
- Birmingham Women's and Children NHS Foundation Trust, Birmingham, United Kingdom
| | - Majlinda Lako
- Biosciences Institute, Newcastle University, Newcastle, United Kingdom
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Fina ME, Wang J, Nikonov SS, Sterling S, Vardi N, Kashina A, Dong DW. Arginyltransferase (Ate1) regulates the RGS7 protein level and the sensitivity of light-evoked ON-bipolar responses. Sci Rep 2021; 11:9376. [PMID: 33931669 PMCID: PMC8087773 DOI: 10.1038/s41598-021-88628-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Accepted: 04/14/2021] [Indexed: 12/16/2022] Open
Abstract
Regulator of G-protein signaling 7 (RGS7) is predominately present in the nervous system and is essential for neuronal signaling involving G-proteins. Prior studies in cultured cells showed that RGS7 is regulated via proteasomal degradation, however no protein is known to facilitate proteasomal degradation of RGS7 and it has not been shown whether this regulation affects G-protein signaling in neurons. Here we used a knockout mouse model with conditional deletion of arginyltransferase (Ate1) in the nervous system and found that in retinal ON bipolar cells, where RGS7 modulates a G-protein to signal light increments, deletion of Ate1 raised the level of RGS7. Electroretinographs revealed that lack of Ate1 leads to increased light-evoked response sensitivities of ON-bipolar cells, as well as their downstream neurons. In cultured mouse embryonic fibroblasts (MEF), RGS7 was rapidly degraded via proteasome pathway and this degradation was abolished in Ate1 knockout MEF. Our results indicate that Ate1 regulates RGS7 protein level by facilitating proteasomal degradation of RGS7 and thus affects G-protein signaling in neurons.
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Affiliation(s)
- Marie E Fina
- Department of Biomedical Sciences, School of Veterinary Medicines, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Junling Wang
- Department of Biomedical Sciences, School of Veterinary Medicines, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Sergei S Nikonov
- Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Stephanie Sterling
- Department of Biomedical Sciences, School of Veterinary Medicines, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Noga Vardi
- Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Anna Kashina
- Department of Biomedical Sciences, School of Veterinary Medicines, University of Pennsylvania, Philadelphia, PA, 19104, USA.
| | - Dawei W Dong
- Department of Biomedical Sciences, School of Veterinary Medicines, University of Pennsylvania, Philadelphia, PA, 19104, USA.
- Institute for Biomedical Informatics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA.
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Li H, Yu H, Kim YK, Wang F, Teodoro G, Jiang Y, Nickerson JM, Kong J. Computational Model-Based Estimation of Mouse Eyeball Structure From Two-Dimensional Flatmount Microscopy Images. Transl Vis Sci Technol 2021; 10:25. [PMID: 34004004 PMCID: PMC8088229 DOI: 10.1167/tvst.10.4.25] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Accepted: 02/17/2021] [Indexed: 11/25/2022] Open
Abstract
Purpose Retinal pigment epithelial (RPE) cells serve as a supporter for the metabolism and visual function of photoreceptors and a barrier for photoreceptor protection. Morphology dynamics, spatial organization, distribution density, and growth patterns of RPE cells are important for further research on these RPE main functions. To enable such investigations within the authentic eyeball structure, a new method for estimating the three-dimensional (3D) eyeball sphere from two-dimensional tissue flatmount microscopy images was investigated. Methods An error-correction term was formulated to compensate for the reconstruction error as a result of tissue distortions. The effect of the tissue-distortion error was evaluated by excluding partial data points from the low- and high-latitude zones. The error-correction parameter was learned automatically using a set of samples with the ground truth eyeball diameters measured with noncontact light-emitting diode micrometry at submicron accuracy and precision. Results The analysis showed that the error-correction term in the reconstruction model is a valid method for modeling tissue distortions in the tissue flatmount preparation steps. With the error-correction model, the average relative error of the estimated eyeball diameter was reduced from 14% to 5%, and the absolute error was reduced from 0.22 to 0.03 mm. Conclusions A new method for enabling RPE morphometry analysis with respect to locations on an eyeball sphere was created, an important step in increasing RPE research and eye disease diagnosis. Translational Relevance This method enables one to derive RPE cell information from the 3D eyeball surface and helps characterize eyeball volume growth patterns under diseased conditions.
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Affiliation(s)
- Hongxiao Li
- Department of Mathematics and Statistics, Georgia State University, Atlanta, GA, USA
- Institute of Biomedical Engineering, Chinese Academy of Medical Sciences & Peking Union Medical College, Tianjin, China
| | - Hanyi Yu
- Department of Computer Science, Emory University, Atlanta, GA, USA
| | - Yong-Kyu Kim
- Department of Ophthalmology, Hallym University College of Medicine, Kangdong Sacred Heart Hospital, Seoul, South Korea
| | - Fusheng Wang
- Department of Computer Science, Stony Brook University, Stony Brook, NY, USA
| | - George Teodoro
- Department of Computer Science, Federal University of Minas Gerais, Belo Horizonte, Brazil
| | - Yi Jiang
- Department of Mathematics and Statistics, Georgia State University, Atlanta, GA, USA
| | | | - Jun Kong
- Department of Mathematics and Statistics, Georgia State University, Atlanta, GA, USA
- Department of Computer Science, Emory University, Atlanta, GA, USA
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ATRIP protects progenitor cells against DNA damage in vivo. Cell Death Dis 2020; 11:923. [PMID: 33110058 PMCID: PMC7591577 DOI: 10.1038/s41419-020-03090-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2020] [Revised: 07/29/2020] [Accepted: 07/30/2020] [Indexed: 12/31/2022]
Abstract
The maintenance of genomic stability during the cell cycle of progenitor cells is essential for the faithful transmission of genetic information. Mutations in genes that ensure genome stability lead to human developmental syndromes. Mutations in Ataxia Telangiectasia and Rad3-related (ATR) or in ATR-interacting protein (ATRIP) lead to Seckel syndrome, which is characterized by developmental malformations and short life expectancy. While the roles of ATR in replicative stress response and chromosomal segregation are well established, it is unknown how ATRIP contributes to maintaining genomic stability in progenitor cells in vivo. Here, we generated the first mouse model to investigate ATRIP function. Conditional inactivation of Atrip in progenitor cells of the CNS and eye led to microcephaly, microphthalmia and postnatal lethality. To understand the mechanisms underlying these malformations, we used lens progenitor cells as a model and found that ATRIP loss promotes replicative stress and TP53-dependent cell death. Trp53 inactivation in Atrip-deficient progenitor cells rescued apoptosis, but increased mitotic DNA damage and mitotic defects. Our findings demonstrate an essential role of ATRIP in preventing DNA damage accumulation during unchallenged replication.
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Rocha-Martins M, de Toledo BC, Santos-França PL, Oliveira-Valença VM, Vieira-Vieira CH, Matos-Rodrigues GE, Linden R, Norden C, Martins RAP, Silveira MS. De novo genesis of retinal ganglion cells by targeted expression of Klf4 in vivo. Development 2019; 146:dev.176586. [PMID: 31405994 DOI: 10.1242/dev.176586] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2019] [Accepted: 07/09/2019] [Indexed: 12/11/2022]
Abstract
Retinal ganglion cell (RGC) degeneration is a hallmark of glaucoma, the most prevalent cause of irreversible blindness. Thus, therapeutic strategies are needed to protect and replace these projection neurons. One innovative approach is to promote de novo genesis of RGCs via manipulation of endogenous cell sources. Here, we demonstrate that the pluripotency regulator gene Krüppel-like factor 4 (Klf4) is sufficient to change the potency of lineage-restricted retinal progenitor cells to generate RGCs in vivo Transcriptome analysis disclosed that the overexpression of Klf4 induces crucial regulators of RGC competence and specification, including Atoh7 and Eya2 In contrast, loss-of-function studies in mice and zebrafish demonstrated that Klf4 is not essential for generation or differentiation of RGCs during retinogenesis. Nevertheless, induced RGCs (iRGCs) generated upon Klf4 overexpression migrate to the proper layer and project axons aligned with endogenous fascicles that reach the optic nerve head. Notably, iRGCs survive for up to 30 days after in vivo generation. We identified Klf4 as a promising candidate for reprogramming retinal cells and regenerating RGCs in the retina.This article has an associated 'The people behind the papers' interview.
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Affiliation(s)
- Maurício Rocha-Martins
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, 21941-902 Rio de Janeiro, Brazil .,Max Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany
| | - Beatriz C de Toledo
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, 21941-902 Rio de Janeiro, Brazil
| | - Pedro L Santos-França
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, 21941-902 Rio de Janeiro, Brazil
| | - Viviane M Oliveira-Valença
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, 21941-902 Rio de Janeiro, Brazil
| | - Carlos H Vieira-Vieira
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, 21941-902 Rio de Janeiro, Brazil
| | - Gabriel E Matos-Rodrigues
- Programa de Biologia Celular e do Desenvolvimento, Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, 21941-902 Rio de Janeiro, Brazil
| | - Rafael Linden
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, 21941-902 Rio de Janeiro, Brazil
| | - Caren Norden
- Max Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany
| | - Rodrigo A P Martins
- Programa de Biologia Celular e do Desenvolvimento, Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, 21941-902 Rio de Janeiro, Brazil
| | - Mariana S Silveira
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, 21941-902 Rio de Janeiro, Brazil
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Proliferation and Survival of Embryonic Sympathetic Neuroblasts by MYCN and Activated ALK Signaling. J Neurosci 2017; 36:10425-10439. [PMID: 27707976 DOI: 10.1523/jneurosci.0183-16.2016] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2016] [Accepted: 08/23/2016] [Indexed: 01/07/2023] Open
Abstract
Neuroblastoma (NB) is a childhood tumor that arises from the sympathoadrenal lineage. MYCN amplification is the most reliable marker for poor prognosis and MYCN overexpression in embryonic mouse sympathetic ganglia results in NB-like tumors. MYCN cooperates with mutational activation of anaplastic lymphoma kinase (ALK), which promotes progression to NB, but the role of MYCN and ALK in tumorigenesis is still poorly understood. Here, we use chick sympathetic neuroblasts to examine the normal function of MYCN and MYC in the control of neuroblast proliferation, as well as effects of overexpression of MYCN, MYC, and activated ALK, alone and in combination. We demonstrate that MYC is more strongly expressed than MYCN during neurogenesis and is important for in vitro neuroblast proliferation. MYC and MYCN overexpression elicits increased proliferation but does not sustain neuroblast survival. Unexpectedly, long-term expression of activated ALKF1174L leads to cell-cycle arrest and promotes differentiation and survival of postmitotic neurons. ALKF1174L induces NEFM, RET, and VACHT and results in decreased expression of proapototic (BMF, BIM), adrenergic (TH), and cell-cycle genes (e.g., CDC25A, CDK1). In contrast, neuroblast proliferation is maintained when MYCN and ALKF1174L are coexpressed. Proliferating MYCN/ALKF1174L neuroblasts display a differentiated phenotype but differ from ALK-expressing neurons by the upregulation of SKP2, CCNA2, E2F8, and DKC1 Inhibition of the ubiquitin ligase SKP2 (S-phase kinase-associated protein 2), which targets the CDK inhibitor p27 for degradation, reduces neuroblast proliferation, implicating SKP2 in the maintained proliferation of MYCN/ALKF1174L neuroblasts. Together, our results characterize MYCN/ALK cooperation leading to neuroblast proliferation and survival that may represent initial steps toward NB development. SIGNIFICANCE STATEMENT MYCN overexpression combined with activated anaplastic lymphoma kinase (ALK) is sufficient to induce neuroblastoma (NB) in mouse sympathoadrenal cells. To address cellular and molecular effects elicited by MYCN/ALK cooperation, we used cultures of chick sympathetic neuroblasts. We demonstrate that MYCN increases proliferation but not survival, whereas long-term expression of ALKF1174L elicits cell-cycle exit, differentiation, and survival of postmitotic neurons. Combined MYCN/ALKF1174L expression allows long-term proliferation and survival of neuroblasts with differentiated characteristics. In the presence of ALKF1174L signaling, MYCN induces the expression of the ubiquitin ligase SKP2 (S-phase kinase-associated protein 2), which targets p27 for degradation and is also upregulated in high-risk NB. SKP2 inhibition supports a function for SKP2 in the maintained neuroblast proliferation downstream of MYCN/ALK, which may represent an early step toward tumorigenesis.
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Cavalheiro GR, Matos-Rodrigues GE, Zhao Y, Gomes AL, Anand D, Predes D, de Lima S, Abreu JG, Zheng D, Lachke SA, Cvekl A, Martins RAP. N-myc regulates growth and fiber cell differentiation in lens development. Dev Biol 2017; 429:105-117. [PMID: 28716713 DOI: 10.1016/j.ydbio.2017.07.002] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2017] [Revised: 06/07/2017] [Accepted: 07/05/2017] [Indexed: 11/26/2022]
Abstract
Myc proto-oncogenes regulate diverse cellular processes during development, but their roles during morphogenesis of specific tissues are not fully understood. We found that c-myc regulates cell proliferation in mouse lens development and previous genome-wide studies suggested functional roles for N-myc in developing lens. Here, we examined the role of N-myc in mouse lens development. Genetic inactivation of N-myc in the surface ectoderm or lens vesicle impaired eye and lens growth, while "late" inactivation in lens fibers had no effect. Unexpectedly, defective growth of N-myc-deficient lenses was not associated with alterations in lens progenitor cell proliferation or survival. Notably, N-myc-deficient lens exhibited a delay in degradation of DNA in terminally differentiating lens fiber cells. RNA-sequencing analysis of N-myc-deficient lenses identified a cohort of down-regulated genes associated with fiber cell differentiation that included DNaseIIβ. Further, an integrated analysis of differentially expressed genes in N-myc-deficient lens using normal lens expression patterns of iSyTE, N-myc-binding motif analysis and molecular interaction data from the String database led to the derivation of an N-myc-based gene regulatory network in the lens. Finally, analysis of N-myc and c-myc double-deficient lens demonstrated that these Myc genes cooperate to drive lens growth prior to lens vesicle stage. Together, these findings provide evidence for exclusive and cooperative functions of Myc transcription factors in mouse lens development and identify novel mechanisms by which N-myc regulates cell differentiation during eye morphogenesis.
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Affiliation(s)
- Gabriel R Cavalheiro
- Programa de Biologia Celular e do Desenvolvimento, Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - Gabriel E Matos-Rodrigues
- Programa de Biologia Celular e do Desenvolvimento, Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - Yilin Zhao
- Department of Genetics, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Anielle L Gomes
- Programa de Biologia Celular e do Desenvolvimento, Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - Deepti Anand
- Department of Biological Sciences, University of Delaware, Newark, DE, USA
| | - Danilo Predes
- Programa de Biologia Celular e do Desenvolvimento, Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - Silmara de Lima
- Programa de Biologia Celular e do Desenvolvimento, Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - Jose G Abreu
- Programa de Biologia Celular e do Desenvolvimento, Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - Deyou Zheng
- Department of Genetics, Albert Einstein College of Medicine, Bronx, NY, USA; Department of Neurology, Albert Einstein College of Medicine, Bronx, NY, USA; Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Salil A Lachke
- Department of Biological Sciences, University of Delaware, Newark, DE, USA; Center for Bioinformatics and Computational Biology, University of Delaware, Newark, DE, USA
| | - Ales Cvekl
- Department of Genetics, Albert Einstein College of Medicine, Bronx, NY, USA; Department of Ophthalmology and Visual Sciences, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Rodrigo A P Martins
- Programa de Biologia Celular e do Desenvolvimento, Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil.
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12
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Cavalheiro GR, Matos-Rodrigues GE, Gomes AL, Rodrigues PMG, Martins RAP. c-Myc regulates cell proliferation during lens development. PLoS One 2014; 9:e87182. [PMID: 24503550 PMCID: PMC3913586 DOI: 10.1371/journal.pone.0087182] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2013] [Accepted: 12/20/2013] [Indexed: 12/20/2022] Open
Abstract
Myc protooncogenes play important roles in the regulation of cell proliferation, growth, differentiation and survival during development. In various developing organs, c-myc has been shown to control the expression of cell cycle regulators and its misregulated expression is detected in many human tumors. Here, we show that c-myc gene (Myc) is highly expressed in developing mouse lens. Targeted deletion of c-myc gene from head surface ectoderm dramatically impaired ocular organogenesis, resulting in severe microphtalmia, defective anterior segment development, formation of a lens stalk and/or aphakia. In particular, lenses lacking c-myc presented thinner epithelial cell layer and growth impairment that was detectable soon after its inactivation. Defective development of c-myc-null lens was not caused by increased cell death of lens progenitor cells. Instead, c-myc loss reduced cell proliferation, what was associated with an ectopic expression of Prox1 and p27Kip1 proteins within epithelial cells. Interestingly, a sharp decrease in the expression of the forkhead box transcription factor Foxe3 was also observed following c-myc inactivation. These data represent the first description of the physiological roles played by a Myc family member in mouse lens development. Our findings support the conclusion that c-myc regulates the proliferation of lens epithelial cells in vivo and may, directly or indirectly, modulate the expression of classical cell cycle regulators in developing mouse lens.
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Affiliation(s)
- Gabriel R. Cavalheiro
- Programa de Biologia Celular e do Desenvolvimento, Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Rio de Janeiro, Brazil
| | - Gabriel E. Matos-Rodrigues
- Programa de Biologia Celular e do Desenvolvimento, Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Rio de Janeiro, Brazil
| | - Anielle L. Gomes
- Programa de Biologia Celular e do Desenvolvimento, Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Rio de Janeiro, Brazil
| | - Paulo M. G. Rodrigues
- Programa de Biologia Celular e do Desenvolvimento, Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Rio de Janeiro, Brazil
| | - Rodrigo A. P. Martins
- Programa de Biologia Celular e do Desenvolvimento, Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Rio de Janeiro, Brazil
- * E-mail:
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13
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Wittmann W, Schimmang T, Gunhaga L. Progressive effects of N-myc deficiency on proliferation, neurogenesis, and morphogenesis in the olfactory epithelium. Dev Neurobiol 2014; 74:643-56. [PMID: 24376126 PMCID: PMC4237195 DOI: 10.1002/dneu.22162] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2013] [Revised: 11/27/2013] [Accepted: 12/18/2013] [Indexed: 12/03/2022]
Abstract
N-myc belongs to the myc proto-oncogene family, which is
involved in numerous cellular processes such as proliferation, growth, apoptosis, and
differentiation. Conditional deletion of N-myc in the mouse nervous system
disrupted brain development, indicating that N-myc plays an essential role during
neural development. How the development of the olfactory epithelium and neurogenesis within are
affected by the loss of N-myc has, however, not been determined. To address these
issues, we examined an N-mycFoxg1Cre conditional mouse line, in which
N-myc is depleted in the olfactory epithelium. First changes in
N-myc mutants were detected at E11.5, with reduced proliferation and neurogenesis
in a slightly smaller olfactory epithelium. The phenotype was more pronounced at E13.5, with a
complete lack of Hes5-positive progenitor cells, decreased proliferation, and
neurogenesis. In addition, stereological analyses revealed reduced cell size of post-mitotic neurons
in the olfactory epithelium, which contributed to a smaller olfactory pit. Furthermore, we observed
diminished proliferation and neurogenesis also in the vomeronasal organ, which likewise was reduced
in size. In addition, the generation of gonadotropin-releasing hormone neurons was severely reduced
in N-myc mutants. Thus, diminished neurogenesis and proliferation in combination
with smaller neurons might explain the morphological defects in the N-myc depleted
olfactory structures. Moreover, our results suggest an important role for N-myc in
regulating ongoing neurogenesis, in part by maintaining the Hes5-positive
progenitor pool. In summary, our results provide evidence that N-myc deficiency in
the olfactory epithelium progressively diminishes proliferation and neurogenesis with negative
consequences at structural and cellular levels. © 2013 The Authors. Developmental
Neurobiology Published by Wiley Periodicals, Inc. Develop Neurobiol 74: 643–656, 2014
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Affiliation(s)
- Walter Wittmann
- Umeå Centre for Molecular Medicine, Umeå University, 901 87, Umeå, Sweden
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14
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Ma M, Zhao K, Wu W, Sun R, Fei J. Dynamic expression of N-myc in mouse embryonic development using an enhanced green fluorescent protein reporter gene in the N-myc locus. Dev Growth Differ 2014; 56:152-60. [PMID: 24397388 DOI: 10.1111/dgd.12115] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2013] [Revised: 12/01/2013] [Accepted: 12/01/2013] [Indexed: 12/20/2022]
Abstract
N-myc belongs to the Myc oncogene family and plays an essential role in mammalian embryonic development. The expression of N-myc is dynamically regulated during embryonic development; however, its expression pattern has not been well characterized due to the lack of a suitable animal model. In this paper, a genetically modified mouse model was generated in which the enhanced green fluorescent protein (EGFP) coding sequence was inserted into the N-myc locus, so that endogenous N-myc expression could be traced by the signal of EGFP. The EGFP signal in the transgenic mouse was confirmed to be consistent with the expression pattern of endogenous N-myc by fluorescence microscopy and immunohistochemical staining. Furthermore, the spatial and temporal expression of EGFP was observed in the central and peripheral nervous system, heart, lung and kidney, given the known indispensable role of N-myc in their formation. EGFP was also strongly detected in the liver, paranephros and the epithelium of the intestine. The EGFP signal can be used to trace N-myc expression in this transgenic mouse model. N-myc expression was observed in specific locations and cell lineages, and dynamically changed during embryonic development. The changing N-myc expression pattern seen in mouse embryonic development and the animal model described in this paper provide important insights and a new tool to research N-myc function.
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Affiliation(s)
- Ming Ma
- School of Life Science and Technology, Tongji University, 200092, China
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15
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Identification and characterization of FGF2-dependent mRNA: microRNA networks during lens fiber cell differentiation. G3-GENES GENOMES GENETICS 2013; 3:2239-55. [PMID: 24142921 PMCID: PMC3852386 DOI: 10.1534/g3.113.008698] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
MicroRNAs (miRNAs) and fibroblast growth factor (FGF) signaling regulate a wide range of cellular functions, including cell specification, proliferation, migration, differentiation, and survival. In lens, both these systems control lens fiber cell differentiation; however, a possible link between these processes remains to be examined. Herein, the functional requirement for miRNAs in differentiating lens fiber cells was demonstrated via conditional inactivation of Dicer1 in mouse (Mus musculus) lens. To dissect the miRNA-dependent pathways during lens differentiation, we used a rat (Rattus norvegicus) lens epithelial explant system, induced by FGF2 to differentiate, followed by mRNA and miRNA expression profiling. Transcriptome and miRNome analysis identified extensive FGF2-regulated cellular responses that were both independent and dependent on miRNAs. We identified 131 FGF2-regulated miRNAs. Seventy-six of these miRNAs had at least two in silico predicted and inversely regulated target mRNAs. Genes modulated by the greatest number of FGF-regulated miRNAs include DNA-binding transcription factors Nfib, Nfat5/OREBP, c-Maf, Ets1, and N-Myc. Activated FGF signaling influenced bone morphogenetic factor/transforming growth factor-β, Notch, and Wnt signaling cascades implicated earlier in lens differentiation. Specific miRNA:mRNA interaction networks were predicted for c-Maf, N-Myc, and Nfib (DNA-binding transcription factors); Cnot6, Cpsf6, Dicer1, and Tnrc6b (RNA to miRNA processing); and Ash1l, Med1/PBP, and Kdm5b/Jarid1b/Plu1 (chromatin remodeling). Three miRNAs, including miR-143, miR-155, and miR-301a, down-regulated expression of c-Maf in the 3′-UTR luciferase reporter assays. These present studies demonstrate for the first time global impact of activated FGF signaling in lens cell culture system and predicted novel gene regulatory networks connected by multiple miRNAs that regulate lens differentiation.
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16
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Joseph C, Quach JM, Walkley CR, Lane SW, Lo Celso C, Purton LE. Deciphering hematopoietic stem cells in their niches: a critical appraisal of genetic models, lineage tracing, and imaging strategies. Cell Stem Cell 2013; 13:520-33. [PMID: 24209759 DOI: 10.1016/j.stem.2013.10.010] [Citation(s) in RCA: 134] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
In recent years, technical developments in mouse genetics and imaging equipment have substantially advanced our understanding of hematopoietic stem cells (HSCs) and their niche. The availability of numerous Cre strains for targeting HSCs and microenvironmental cells provides extensive flexibility in experimental design, but it can also pose significant challenges due to strain-specific differences in cell specificity. Here we outline various genetic approaches for isolating, detecting, and ablating HSCs and niche components and provide a guide for advantages and caveats to consider. We also discuss opportunities and limitations presented by imaging technologies that allow investigation of HSC behavior in situ.
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Affiliation(s)
- Chacko Joseph
- Stem Cell Regulation Unit, St. Vincent's Institute of Medical Research, 9 Princes Street, Fitzroy, VIC, 3065, Australia; Department of Medicine at St. Vincent's Hospital, The University of Melbourne, Fitzroy, VIC, 3065, Australia
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17
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Wolf L, Harrison W, Huang J, Xie Q, Xiao N, Sun J, Kong L, Lachke SA, Kuracha MR, Govindarajan V, Brindle PK, Ashery-Padan R, Beebe DC, Overbeek PA, Cvekl A. Histone posttranslational modifications and cell fate determination: lens induction requires the lysine acetyltransferases CBP and p300. Nucleic Acids Res 2013; 41:10199-214. [PMID: 24038357 PMCID: PMC3905850 DOI: 10.1093/nar/gkt824] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Lens induction is a classical embryologic model to study cell fate determination. It has been proposed earlier that specific changes in core histone modifications accompany the process of cell fate specification and determination. The lysine acetyltransferases CBP and p300 function as principal enzymes that modify core histones to facilitate specific gene expression. Herein, we performed conditional inactivation of both CBP and p300 in the ectodermal cells that give rise to the lens placode. Inactivation of both CBP and p300 resulted in the dramatic discontinuation of all aspects of lens specification and organogenesis, resulting in aphakia. The CBP/p300−/− ectodermal cells are viable and not prone to apoptosis. These cells showed reduced expression of Six3 and Sox2, while expression of Pax6 was not upregulated, indicating discontinuation of lens induction. Consequently, expression of αB- and αA-crystallins was not initiated. Mutant ectoderm exhibited markedly reduced levels of histone H3 K18 and K27 acetylation, subtly increased H3 K27me3 and unaltered overall levels of H3 K9ac and H3 K4me3. Our data demonstrate that CBP and p300 are required to establish lens cell-type identity during lens induction, and suggest that posttranslational histone modifications are integral to normal cell fate determination in the mammalian lens.
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Affiliation(s)
- Louise Wolf
- Department of Ophthalmology and Visual Sciences, Albert Einstein College of Medicine, Bronx, NY10461, USA, Department of Genetics, Albert Einstein College of Medicine, Bronx, NY10461, USA, Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX 77030, USA, Departments of Ophthalmology and Visual Sciences, Washington University Saint Louis, Saint Louis, MO 63110, USA, Department of Biological Sciences, University of Delaware, Newark, DE 19716, USA, Center for Bioinformatics and Computational Biology, University of Delaware, Newark, DE 19716, USA, Department of Surgery, Creighton University, Omaha, NE 68178, USA, Department of Biochemistry, St. Jude Children's Research Hospital, Memphis, TN 38105, USA and Department of Human Molecular Genetics and Biochemistry, Sackler School of Medicine and Sagol School of Neuroscience, Tel Aviv University, Israel 69978
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18
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Rodrigues PMG, Grigaravicius P, Remus M, Cavalheiro GR, Gomes AL, Martins MR, Frappart L, Reuss D, McKinnon PJ, von Deimling A, Martins RAP, Frappart PO. Nbn and atm cooperate in a tissue and developmental stage-specific manner to prevent double strand breaks and apoptosis in developing brain and eye. PLoS One 2013; 8:e69209. [PMID: 23935957 PMCID: PMC3728324 DOI: 10.1371/journal.pone.0069209] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2013] [Accepted: 06/06/2013] [Indexed: 01/30/2023] Open
Abstract
Nibrin (NBN or NBS1) and ATM are key factors for DNA Double Strand Break (DSB) signaling and repair. Mutations in NBN or ATM result in Nijmegen Breakage Syndrome and Ataxia telangiectasia. These syndromes share common features such as radiosensitivity, neurological developmental defects and cancer predisposition. However, the functional synergy of Nbn and Atm in different tissues and developmental stages is not yet understood. Here, we show in vivo consequences of conditional inactivation of both genes in neural stem/progenitor cells using Nestin-Cre mice. Genetic inactivation of Atm in the central nervous system of Nbn-deficient mice led to reduced life span and increased DSBs, resulting in increased apoptosis during neural development. Surprisingly, the increase of DSBs and apoptosis was found only in few tissues including cerebellum, ganglionic eminences and lens. In sharp contrast, we showed that apoptosis associated with Nbn deletion was prevented by simultaneous inactivation of Atm in developing retina. Therefore, we propose that Nbn and Atm collaborate to prevent DSB accumulation and apoptosis during development in a tissue- and developmental stage-specific manner.
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Affiliation(s)
- Paulo M. G. Rodrigues
- Programa de Biologia Celular e do Desenvolvimento, Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Paulius Grigaravicius
- Clinical Cooperation Unit Neuropathology, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Martina Remus
- Clinical Cooperation Unit Neuropathology, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Gabriel R. Cavalheiro
- Programa de Biologia Celular e do Desenvolvimento, Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Anielle L. Gomes
- Programa de Biologia Celular e do Desenvolvimento, Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Mauricio R. Martins
- Programa de Pós Graduação em Biofísica, IBCCF, Universidade Federal do Rio de Janeiro, CCS, Rio de Janeiro, Brazil
| | - Lucien Frappart
- Leibniz Institute for Age Research – Fritz Lipmann Institute (FLI), Jena, Germany
| | - David Reuss
- Clinical Cooperation Unit Neuropathology, German Cancer Research Center (DKFZ), Heidelberg, Germany
- Department of Neuropathology, Institute of Pathology, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany
| | - Peter J. McKinnon
- Department of Genetics, St.Jude Children's Research Hospital, Memphis, Tennessee, United States of America
| | - Andreas von Deimling
- Clinical Cooperation Unit Neuropathology, German Cancer Research Center (DKFZ), Heidelberg, Germany
- Department of Neuropathology, Institute of Pathology, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany
| | - Rodrigo A. P. Martins
- Programa de Biologia Celular e do Desenvolvimento, Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
- * E-mail: (POF); (RAPM)
| | - Pierre-Olivier Frappart
- Clinical Cooperation Unit Neuropathology, German Cancer Research Center (DKFZ), Heidelberg, Germany
- * E-mail: (POF); (RAPM)
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Coupling the cell cycle to development and regeneration of the inner ear. Semin Cell Dev Biol 2013; 24:507-13. [PMID: 23665151 DOI: 10.1016/j.semcdb.2013.04.004] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2013] [Accepted: 04/23/2013] [Indexed: 12/19/2022]
Abstract
Cell cycle exit and acquirement of a postmitotic state is essential for the proper development of organs. In the present review, we examine the role of the cell cycle control in the sensory epithelia of the mammalian inner ear. We describe the roles of the core cell cycle regulators in the proliferation of prosensory cells and in the initiation and maintenance of terminal mitosis of the sensory epithelia. We also discuss how other intracellular signalling may influence the cell cycle. Finally, we address the question of whether manipulations of the cell cycle may have the potential to create replacement cells for the damaged inner sensory epithelia.
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20
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Xue XY, Harris WA. Using myc genes to search for stem cells in the ciliary margin of the Xenopus retina. Dev Neurobiol 2012; 72:475-90. [PMID: 21465669 DOI: 10.1002/dneu.20887] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The ciliary marginal zone (CMZ) of fish and frog retinas contains cells that proliferate throughout postembryonic development as the retina grows with increasing body size, indicating the presence of stem cells in this region. However, neither the location nor the molecular identity of retinal stem cells has been identified. Here, we show in Xenopus that c-myc and n-myc are sequentially expressed both during development and in the post-embryonic retina. The c-myc+/n-myc- cells near the extreme periphery of the CMZ cycle more slowly and preferentially retain DNA label compared to their more central cmyc+/n-myc+ neighbors which cycle rapidly and preferentially dilute DNA label. During retinal development c-myc is functionally required earlier than n-myc, and n-myc expression depends on earlier c-myc expression. The expression of c-myc but not n-myc in the CMZ depends on growth factor signaling. Our results suggest that c-myc+/n-myc- cells in the far peripheral CMZ are candidates for a niche-dependent population of retinal stem cells that give rise to more centrally located and rapidly dividing n-myc+ progenitors of more limited proliferative potential. Analysis of homologues of these genes in the zebrafish CMZ suggests that the transition from c-myc to n-myc expression might be conserved in other lower vertebrates whose retinas growth throughout life.
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Affiliation(s)
- Xiao Yan Xue
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, United Kingdom
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21
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Rocha-Martins M, Njaine B, Silveira MS. Avoiding pitfalls of internal controls: validation of reference genes for analysis by qRT-PCR and Western blot throughout rat retinal development. PLoS One 2012; 7:e43028. [PMID: 22916200 PMCID: PMC3423434 DOI: 10.1371/journal.pone.0043028] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2012] [Accepted: 07/16/2012] [Indexed: 01/29/2023] Open
Abstract
BACKGROUND Housekeeping genes have been commonly used as reference to normalize gene expression and protein content data because of its presumed constitutive expression. In this paper, we challenge the consensual idea that housekeeping genes are reliable controls for expression studies in the retina through the investigation of a panel of reference genes potentially suitable for analysis of different stages of retinal development. METHODOLOGY/PRINCIPAL FINDINGS We applied statistical tools on combinations of retinal developmental stages to assess the most stable internal controls for quantitative RT-PCR (qRT-PCR). The stability of expression of seven putative reference genes (Actb, B2m, Gapdh, Hprt1, Mapk1, Ppia and Rn18s) was analyzed using geNorm, BestKeeper and Normfinder software. In addition, several housekeeping genes were tested as loading controls for Western blot in the same sample panel, using Image J. Overall, for qRT-PCR the combination of Gapdh and Mapk1 showed the highest stability for most experimental sets. Actb was downregulated in more mature stages, while Rn18s and Hprt1 showed the highest variability. We normalized the expression of cyclin D1 using various reference genes and demonstrated that spurious results may result from blind selection of internal controls. For Western blot significant variation could be seen among four putative internal controls (β-actin, cyclophilin b, α-tubulin and lamin A/C), while MAPK1 was stably expressed. CONCLUSION Putative housekeeping genes exhibit significant variation in both mRNA and protein content during retinal development. Our results showed that distinct combinations of internal controls fit for each experimental set in the case of qRT-PCR and that MAPK1 is a reliable loading control for Western blot. The results indicate that biased study outcomes may follow the use of reference genes without prior validation for qRT-PCR and Western blot.
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Affiliation(s)
- Maurício Rocha-Martins
- Neurobiology Department, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Brian Njaine
- Cell Therapy and Bioengeneering Department, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Mariana S. Silveira
- Neurobiology Department, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
- * E-mail:
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22
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Diaz-Guerra E, Lillo MA, Santamaria S, Garcia-Sanz JA. Intrinsic cues and hormones control mouse mammary epithelial tree size. FASEB J 2012; 26:3844-53. [PMID: 22683848 DOI: 10.1096/fj.11-200782] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Organ size control is a long-standing question in biology. In mammals, using conditional cell ablation, two mutually exclusive mechanisms involving either intrinsic or extrinsic programs have been described to control organ size. The mammary gland is an ideal model for such studies, since it undergoes size and morphological changes during puberty and pregnancy. The role of stem cells in controlling mammary epithelial tree size is unclear, although mammary stem cells are able to reconstitute a functional organ on transplantation. Here, we show that mammary gland cellularity was strictly dependent on mammary stem cell number, even following a 20-fold expansion of the mammary stem cell pool at puberty and transient 3-fold expansions with each pregnancy. In addition, the expansion of the mammary stem cell pool was hormone dependent, as demonstrated by female bilateral ovariectomies during puberty and transplants of male-derived cells into female recipients. In these transplants, apart from a mammary stem cell expansion, we also observed the donor cells reconstituting functional mammary glands, developing alveolar structures, and secreting milk after the recipient's parturition. Taken together, these data suggest that in the mammary gland, there is a third organ size control mechanism, combining intrinsic cues throughout the organism's lifetime, with extrinsic hormone signals at particular developmental windows (puberty, pregnancy), where an expansion of the mammary stem cell pool occurs. This mechanism might have strong implications for the understanding of mammary tumorigenesis, since the expansion of the mammary stem cell pool precedes the generation of breast tumors.
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Affiliation(s)
- Eva Diaz-Guerra
- Department of Cellular and Molecular Medicine, Centro de Investigaciones Biologicas, Spanish National Research Council (CIB-CSIC), Madrid, Spain
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23
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Conkrite K, Sundby M, Mukai S, Thomson JM, Mu D, Hammond SM, MacPherson D. miR-17~92 cooperates with RB pathway mutations to promote retinoblastoma. Genes Dev 2011; 25:1734-45. [PMID: 21816922 DOI: 10.1101/gad.17027411] [Citation(s) in RCA: 156] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The miR-17~92 cluster is a potent microRNA-encoding oncogene. Here, we show that miR-17~92 synergizes with loss of Rb family members to promote retinoblastoma. We observed miR-17~92 genomic amplifications in murine retinoblastoma and high expression of miR-17~92 in human retinoblastoma. While miR-17~92 was dispensable for mouse retinal development, miR-17~92 overexpression, together with deletion of Rb and p107, led to rapid emergence of retinoblastoma with frequent metastasis to the brain. miR-17~92 oncogenic function in retinoblastoma was not mediated by a miR-19/PTEN axis toward apoptosis suppression, as found in lymphoma/leukemia models. Instead, miR-17~92 increased the proliferative capacity of Rb/p107-deficient retinal cells. We found that deletion of Rb family members led to compensatory up-regulation of the cyclin-dependent kinase inhibitor p21Cip1. miR-17~92 overexpression counteracted p21Cip1 up-regulation, promoted proliferation, and drove retinoblastoma formation. These results demonstrate that the oncogenic determinants of miR-17~92 are context-specific and provide new insights into miR-17~92 function as an RB-collaborating gene in cancer.
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Affiliation(s)
- Karina Conkrite
- Department of Embryology, Carnegie Institution, Baltimore, Maryland 21218, USA
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Abstract
Myc family members play crucial roles in regulating cell proliferation, size, and differentiation during organogenesis. Both N-myc and c-myc are expressed throughout inner ear development. To address their function in the mouse inner ear, we generated mice with conditional deletions in either N-myc or c-myc. Loss of c-myc in the inner ear causes no apparent defects, whereas inactivation of N-myc results in reduced growth caused by a lack of proliferation. Reciprocally, the misexpression of N-myc in the inner ear increases proliferation. Morphogenesis of the inner ear in N-myc mouse mutants is severely disturbed, including loss of the lateral canal, fusion of the cochlea with the sacculus and utriculus, and stunted outgrowth of the cochlea. Mutant cochleas are characterized by an increased number of cells exiting the cell cycle that express the cyclin-dependent kinase inhibitor p27(Kip1) and lack cyclin D1, both of which control the postmitotic state of hair cells. Analysis of different molecular markers in N-myc mutant ears reveals the development of a rudimentary organ of Corti containing hair cells and the underlying supporting cells. Differentiated cells, however, fail to form the highly ordered structure characteristic for the organ of Corti but appear as rows or clusters with an excess number of hair cells. The Kölliker's organ, a transient structure neighboring the organ of Corti and a potential source of ectopic hair cells, is absent in the mutant ears. Collectively, our data suggest that N-myc regulates growth, morphogenesis, and pattern formation during the development of the inner ear.
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Abstract
myc genes are associated with a wide variety of human cancers including most types of nervous system tumors. While the mechanisms by which myc overexpression causes tumorigenesis are multifaceted and have yet to be clearly elucidated, they are at least in part related to endogenous myc function in normal cells. Knockout (KO) of either c-myc or N-myc genes in neural stem and precursor cells (NSC) driven by nestin-cre impairs mouse brain growth and mutation of N-myc also causes microcephaly in humans in Feingold Syndrome. To further define myc function in NSC and nervous system development, we created a double KO (DKO) for c- and N-myc using nestin-cre. The DKO mice display profoundly impaired overall brain growth associated with decreased cell cycling and migration of NSC, which are strikingly decreased in number. The DKO brain also exhibits specific changes in gene expression including downregulation of genes involved in protein and nucleotide metabolism, mitosis, and chromatin structure as well as upregulation of genes associated with differentiation. Together these data support a model of nervous system tumorigenesis in which excess myc aberrantly locks in a developmentally active chromatin state characterized by overactive cell cycling, and metabolism as well as blocked differentiation.
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Bilitou A, Ohnuma SI. The role of cell cycle in retinal development: cyclin-dependent kinase inhibitors co-ordinate cell-cycle inhibition, cell-fate determination and differentiation in the developing retina. Dev Dyn 2010; 239:727-36. [PMID: 20108332 DOI: 10.1002/dvdy.22223] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
The mature retina is formed through multi-step developmental processes, including eye field specification, optic vesicle evagination, and cell-fate determination. Co-ordination of these developmental events with cell-proliferative activity is essential to achieve formation of proper retinal structure and function. In particular, the molecular and cellular dynamics of the final cell cycle significantly influence the identity that a cell acquires, since cell fate is largely determined at the final cell cycle for the production of postmitotic cells. This review summarizes our current understanding of the cellular mechanisms that underlie the co-ordination of cell-cycle and cell-fate determination, and also describes a molecular role of cyclin-dependent kinase inhibitors (CDKIs) as co-ordinators of cell-cycle arrest, cell-fate determination and differentiation.
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Affiliation(s)
- Aikaterini Bilitou
- UCL Institute of Ophthalmology, University College London, London, United Kingdom
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Potvin É, Beuret L, Cadrin-Girard JF, Carter M, Roy S, Tremblay M, Charron J. Cooperative action of multiple cis-acting elements is required for N-myc expression in branchial arches: specific contribution of GATA3. Mol Cell Biol 2010; 30:5348-63. [PMID: 20855530 PMCID: PMC2976382 DOI: 10.1128/mcb.00353-09] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2009] [Revised: 05/02/2009] [Accepted: 08/07/2010] [Indexed: 01/05/2023] Open
Abstract
The precise expression of the N-myc proto-oncogene is essential for normal mammalian development, whereas altered N-myc gene regulation is known to be a determinant factor in tumor formation. Using transgenic mouse embryos, we show that N-myc sequences from kb -8.7 to kb +7.2 are sufficient to reproduce the N-myc embryonic expression profile in developing branchial arches and limb buds. These sequences encompass several regulatory elements dispersed throughout the N-myc locus, including an upstream limb bud enhancer, a downstream somite enhancer, a branchial arch enhancer in the second intron, and a negative regulatory element in the first intron. N-myc expression in the limb buds is under the dominant control of the limb bud enhancer. The expression in the branchial arches necessitates the interplay of three regulatory domains. The branchial arch enhancer cooperates with the somite enhancer region to prevent an inhibitory activity contained in the first intron. The characterization of the branchial arch enhancer has revealed a specific role of the transcription factor GATA3 in the regulation of N-myc expression. Together, these data demonstrate that correct N-myc developmental expression is achieved via cooperation of multiple positive and negative regulatory elements.
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Affiliation(s)
- Éric Potvin
- Centre de Recherche en Cancérologie de l'Université Laval, Centre de Recherche du Centre Hospitalier Universitaire de Québec, Quebec, Canada
| | - Laurent Beuret
- Centre de Recherche en Cancérologie de l'Université Laval, Centre de Recherche du Centre Hospitalier Universitaire de Québec, Quebec, Canada
| | - Jean-François Cadrin-Girard
- Centre de Recherche en Cancérologie de l'Université Laval, Centre de Recherche du Centre Hospitalier Universitaire de Québec, Quebec, Canada
| | - Marcelle Carter
- Centre de Recherche en Cancérologie de l'Université Laval, Centre de Recherche du Centre Hospitalier Universitaire de Québec, Quebec, Canada
| | - Sophie Roy
- Centre de Recherche en Cancérologie de l'Université Laval, Centre de Recherche du Centre Hospitalier Universitaire de Québec, Quebec, Canada
| | - Michel Tremblay
- Centre de Recherche en Cancérologie de l'Université Laval, Centre de Recherche du Centre Hospitalier Universitaire de Québec, Quebec, Canada
| | - Jean Charron
- Centre de Recherche en Cancérologie de l'Université Laval, Centre de Recherche du Centre Hospitalier Universitaire de Québec, Quebec, Canada
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Uribe RA, Gross JM. Id2a influences neuron and glia formation in the zebrafish retina by modulating retinoblast cell cycle kinetics. Development 2010; 137:3763-74. [PMID: 20943708 DOI: 10.1242/dev.050484] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Inhibitor of differentiation (Id) family helix-loop-helix proteins regulate the proliferation, survival and differentiation of numerous cell types during development; however, their functions during retinal development have not been analyzed. Using loss-of-function and overexpression assays in zebrafish, we demonstrate that Id2a levels modulate retinoblast cell cycle kinetics and thereby influence neuron and glia formation in the retina. Id2a-deficient retinas possess increased numbers of cells occupying S phase, at the expense of mitotic cells, and kinetic analyses demonstrate that Id2a is required for S-phase progression and/or the transition from S to M phase. Id2a-dependent defects in retinoblast proliferation lead to microphthalmia and to an absence of nearly all differentiated inner and outer nuclear layer cell types. Overexpression of id2a has the opposite effect on retinoblast cell cycle kinetics: id2a-overexpressing retinoblasts progress from S to M phase more rapidly and they undergo mitosis more frequently, which results in macrophthalmia. Mosaic analyses reveal that Id2a function in facilitating both cell cycle progression and neuronal differentiation in the retina is non-cell-autonomous, suggesting that Id2a functions upstream of the extrinsic pathways that regulate retinogenesis.
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Affiliation(s)
- Rosa A Uribe
- Section of Molecular Cell and Developmental Biology, Institute for Cell and Molecular Biology, The University of Texas at Austin, Austin, TX 78722, USA
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Njaine B, Martins RAP, Santiago MF, Linden R, Silveira MS. Pituitary adenylyl cyclase-activating polypeptide controls the proliferation of retinal progenitor cells through downregulation of cyclin D1. Eur J Neurosci 2010; 32:311-21. [PMID: 20646049 DOI: 10.1111/j.1460-9568.2010.07286.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
During retinal development, cell proliferation and exit from the cell cycle must be precisely regulated to ensure the generation of the appropriate numbers and proportions of the various retinal cell types. Previously, we showed that pituitary adenylyl cyclase-activating polypeptide (PACAP) exerts a neuroprotective effect in the developing retina of rats, through the cAMP-cAMP-dependent protein kinase (protein kinase A) (PKA) pathway. Here, we show that PACAP also regulates the proliferation of retinal progenitor cells. PACAP, PACAP-specific receptor (PAC1), and the receptors activated by both PACAP and vasoactive intestinal peptide (VIP), VPAC1 and VPAC2, are expressed during embryonic and postnatal development of the rat retina. Treatment of retinal explants with PACAP38 reduced the incorporation of [(3)H]thymidine as well as the number of 5-bromo-2'-deoxyuridine-positive and cyclin D1-positive cells. Pharmacological experiments indicated that PACAP triggers this antiproliferative effect through the activation of both PAC1 and VPACs, and the cAMP-PKA pathway. In addition, PACAP receptor activation decreased both cyclin D1 mRNA and protein content. Altogether, the data support the hypothesis that PACAP is a cell-extrinsic regulator with multiple roles during retinal development, including the regulation of proliferation in a subpopulation of retinal progenitor cells.
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Affiliation(s)
- Brian Njaine
- Instituto de Biofisica Carlos Chagas Filho-UFRJ, Edifício do Centro de Ciencias da Saude, Ilha do Fundão, Rio de Janeiro, Brazil
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30
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Wisard J, Chrenek MA, Wright C, Dalal N, Pardue MT, Boatright JH, Nickerson JM. Non-contact measurement of linear external dimensions of the mouse eye. J Neurosci Methods 2010; 187:156-66. [PMID: 20067806 PMCID: PMC2832717 DOI: 10.1016/j.jneumeth.2010.01.006] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2009] [Revised: 01/04/2010] [Accepted: 01/05/2010] [Indexed: 11/25/2022]
Abstract
Biometric analyses of quantitative traits in eyes of mice can reveal abnormalities related to refractive or ocular development. Due to the small size of the mouse eye, highly accurate and precise measurements are needed to detect meaningful differences. We sought a non-contact measuring technique to obtain highly accurate and precise linear dimensions of the mouse eye. Laser micrometry was validated with gauge block standards. Simple procedures to measure eye dimensions on three axes were devised. Mouse eyes from C57BL/6J and rd10 on a C57BL/6J background were dissected and extraocular muscle and fat removed. External eye dimensions of axial length (anterior-posterior (A-P) axis) and equatorial diameter (superior-inferior (S-I) and nasal-temporal (N-T) axes) were obtained with a laser micrometer. Several approaches to prevent or ameliorate evaporation due to room air were employed. The resolution of the laser micrometer was less than 0.77 microm, and it provided accurate and precise non-contact measurements of eye dimensions on three axes. External dimensions of the eye strongly correlated with eye weight. The N-T and S-I dimensions of the eye correlated with each other most closely from among the 28 pair-wise combinations of the several parameters that were collected. The equatorial axis measurements correlated well from the right and left eye of each mouse. The A-P measurements did not correlate or correlated poorly in each pair of eyes. The instrument is well suited for the measurement of enucleated eyes and other structures from most commonly used species in experimental vision research and ophthalmology.
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Affiliation(s)
- Jeffrey Wisard
- Department of Ophthalmology, Emory University, Atlanta, GA
| | | | - Charles Wright
- Department of Ophthalmology, Emory University, Atlanta, GA
| | - Nupur Dalal
- Department of Ophthalmology, Emory University, Atlanta, GA
| | - Machelle T. Pardue
- Department of Ophthalmology, Emory University, Atlanta, GA
- Rehabilitation Research and Development Center of Excellence, Atlanta VA Hospital, Decatur, GA
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Chen D, Pacal M, Wenzel P, Knoepfler PS, Leone G, Bremner R. Division and apoptosis of E2f-deficient retinal progenitors. Nature 2010; 462:925-9. [PMID: 20016601 DOI: 10.1038/nature08544] [Citation(s) in RCA: 122] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2009] [Accepted: 09/25/2009] [Indexed: 12/16/2022]
Abstract
The activating E2f transcription factors (E2f1, E2f2 and E2f3) induce transcription and are widely viewed as essential positive cell cycle regulators. Indeed, they drive cells out of quiescence, and the 'cancer cell cycle' in Rb1 null cells is E2f-dependent. Absence of activating E2fs in flies or mammalian fibroblasts causes cell cycle arrest, but this block is alleviated by removing repressive E2f or the tumour suppressor p53, respectively. Thus, whether activating E2fs are indispensable for normal division is an area of debate. Activating E2fs are also well known pro-apoptotic factors, providing a defence against oncogenesis, yet E2f1 can limit irradiation-induced apoptosis. In flies this occurs through repression of hid (also called Wrinkled; Smac/Diablo in mammals). However, in mammals the mechanism is unclear because Smac/Diablo is induced, not repressed, by E2f1, and in keratinocytes survival is promoted indirectly through induction of DNA repair targets. Thus, a direct pro-survival function for E2f1-3 and/or its relevance beyond irradiation has not been established. To address E2f1-3 function in normal cells in vivo we focused on the mouse retina, which is a relatively simple central nervous system component that can be manipulated genetically without compromising viability and has provided considerable insight into development and cancer. Here we show that unlike fibroblasts, E2f1-3 null retinal progenitor cells or activated Müller glia can divide. We attribute this effect to functional interchangeability with Mycn. However, loss of activating E2fs caused downregulation of the p53 deacetylase Sirt1, p53 hyperacetylation and elevated apoptosis, establishing a novel E2f-Sirt1-p53 survival axis in vivo. Thus, activating E2fs are not universally required for normal mammalian cell division, but have an unexpected pro-survival role in development.
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Affiliation(s)
- Danian Chen
- Toronto Western Research Institute, University Health Network, Department of Ophthalmology, and Laboratory Medicine and Pathobiology, University of Toronto, Ontario M5T 2S8, Canada
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32
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Abstract
Myc proteins (c-myc, Mycn and Mycl) target proliferative and apoptotic pathways vital for progression in cancer. Amplification of the MYCN gene has emerged as one of the clearest indicators of aggressive and chemotherapy-refractory disease in children with neuroblastoma, the most common extracranial solid tumor of childhood. Phosphorylation and ubiquitin-mediated modulation of Myc protein influence stability and represent potential targets for therapeutic intervention. Phosphorylation of Myc proteins is controlled in-part by the receptor tyrosine kinase/phosphatidylinositol 3-kinase/Akt/mTOR signaling, with additional contributions from Aurora A kinase. Myc proteins regulate apoptosis in part through interactions with the p53/Mdm2/Arf signaling pathway. Mutation in p53 is commonly observed in patients with relapsed neuroblastoma, contributing to both biology and therapeutic resistance. This review examines Myc function and regulation in neuroblastoma, and discusses emerging therapies that target Mycn.
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Abstract
Neurogenesis in the retina occurs via the coordination of proliferation, cell cycle exit and differentiation of retinal progenitor cells. Until recently, it was widely assumed that once a retinal progenitor cell produced a postmitotic neuron, there was no possibility for cell-cycle re-entry. However, recent studies have shown that mature differentiated horizontal neurons with reduced Rb pathway function can re-enter the cell cycle and proliferate while maintaining their differentiated features. This chapter will explore the molecular and cellular mechanisms that help to keep differentiated retinal neurons and glia postmitotic. We propose that there are cell-type specific barriers to cell-cycle re-entry by differentiated neurons and these may include apoptosis, chromatin/epigenetics mechanisms, cellular morphology and/or metabolic demands that are distinct across cell populations. Our data suggest that differentiated neurons span a continuum of cellular properties related to their ability to re-enter the cell cycle and undergo cytokinesis while maintaining their differentiated features. A deeper understanding of these processes may allow us to begin to explain the cell type specificity of neuronal cell death and tumor susceptibility. For example, neurons that have more barriers to cell-cycle re-entry may be less likely to form tumors but more likely to undergo degeneration. Conversely, neurons that have fewer barriers to cell-cycle re-entry may be more likely to form tumors but less likely to undergo degeneration.
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Affiliation(s)
- Denise M Davis
- Department of Developmental Neurobiology, St. Jude Children's Research Hospital, Memphis, Tennessee, USA
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Abstract
Ocular involvement in muscular dystrophy ranges from structural defects to abnormal electroretinograms. While the mechanisms underlying the abnormal retinal physiology in patients are not understood, it is thought that alpha-dystroglycan extracellular interactions are critical for normal visual function. Here we show that beta-dystroglycan anchors dystrophin and the inward rectifying K(+) channel Kir4.1 at glial endfeet and that disruption of dystrophin and potassium channel clustering in dystroglycan mutant mice is associated with an attenuation of the electroretinogram b-wave. Glial-specific inactivation of dystroglycan or deletion of the cytoplasmic domain of beta-dystroglycan was sufficient to attenuate the electroretinogram b-wave. Unexpectedly, deletion of the beta-dystroglycan cytoplasmic domain did not disrupt the laminar structure of the retina. In contrast to the role of alpha-dystroglycan extracellular interactions during early development of the CNS, beta-dystroglycan intracellular interactions are important for visual function but not the laminar development of the retina.
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Agathocleous M, Harris WA. From Progenitors to Differentiated Cells in the Vertebrate Retina. Annu Rev Cell Dev Biol 2009; 25:45-69. [DOI: 10.1146/annurev.cellbio.042308.113259] [Citation(s) in RCA: 195] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Michalis Agathocleous
- Department of Physiology, Development, and Neuroscience, University of Cambridge, Cambridge CB2 3DY, United Kingdom;
- Gonville and Caius College, University of Cambridge, Cambridge CB2 1TA, United Kingdom;
| | - William A. Harris
- Department of Physiology, Development, and Neuroscience, University of Cambridge, Cambridge CB2 3DY, United Kingdom;
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Laurenti E, Wilson A, Trumpp A. Myc's other life: stem cells and beyond. Curr Opin Cell Biol 2009; 21:844-54. [PMID: 19836223 DOI: 10.1016/j.ceb.2009.09.006] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2009] [Revised: 09/15/2009] [Accepted: 09/18/2009] [Indexed: 12/17/2022]
Abstract
Over the last three decades genetic and biochemical studies have revealed the pleiotropic effects of the Myc oncoprotein. While cell line studies have defined the intracellular processes regulated by Myc such as proliferation, differentiation, and metabolic growth, in vivo studies have confirmed these functions, and revealed roles in acquisition and maintenance of stem cell properties. These roles may be partially mediated by Myc's capacity to modify the chromatin landscape on a global scale. Myc also regulates numerous protein-coding transcripts, and many noncoding RNAs (rRNAs, tRNAs, and miRNAs). As Myc activity directly correlates with protein expression, further complexity is provided by post-translational modifications that regulate Myc in normal stem cells or deregulate it in malignant stem cells.
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Affiliation(s)
- Elisa Laurenti
- Ludwig Institute for Cancer Research Ltd, Lausanne Branch, University of Lausanne, Switzerland
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Cotterman R, Knoepfler PS. N-Myc regulates expression of pluripotency genes in neuroblastoma including lif, klf2, klf4, and lin28b. PLoS One 2009; 4:e5799. [PMID: 19495417 PMCID: PMC2686170 DOI: 10.1371/journal.pone.0005799] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2009] [Accepted: 04/29/2009] [Indexed: 01/07/2023] Open
Abstract
myc genes are best known for causing tumors when overexpressed, but recent studies suggest endogenous myc regulates pluripotency and self-renewal of stem cells. For example, N-myc is associated with a number of tumors including neuroblastoma, but also plays a central role in the function of normal neural stem and precursor cells (NSC). Both c- and N-myc also enhance the production of induced pluripotent stem cells (iPSC) and are linked to neural tumor stem cells. The mechanisms by which myc regulates normal and neoplastic stem-related functions remain largely open questions. Here from a global, unbiased search for N-Myc bound genes using ChIP-chip assays in neuroblastoma, we found lif as a putative N-Myc bound gene with a number of strong N-Myc binding peaks in the promoter region enriched for E-boxes. Amongst putative N-Myc target genes in expression microarray studies in neuroblastoma we also found lif and three additional important embryonic stem cell (ESC)-related factors that are linked to production of iPSC: klf2, klf4, and lin28b. To examine the regulation of these genes by N-Myc, we measured their expression using neuroblastoma cells that contain a Tet-regulatable N-myc transgene (TET21N) as well as NSC with a nestin-cre driven N-myc knockout. N-myc levels closely correlated with the expression of all of these genes in neuroblastoma and all but lif in NSC. Direct ChIP assays also indicate that N-Myc directly binds the lif promoter. N-Myc regulates trimethylation of lysine 4 of histone H3 in the promoter of lif and possibly in the promoters of several other stem-related genes. Together these findings indicate that N-Myc regulates overlapping stem-related gene expression programs in neuroblastoma and NSC, supporting a novel model by which amplification of the N-myc gene may drive formation of neuroblastoma. They also suggest mechanisms by which Myc proteins more generally contribute to maintenance of pluripotency and self-renewal of ESC as well as to iPSC formation.
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Affiliation(s)
- Rebecca Cotterman
- Department of Cell Biology and Human Anatomy, and Stem Cell Program, University of California Davis School of Medicine, Shriners Hospital For Children Northern California, Sacramento, California, United States of America
| | - Paul S. Knoepfler
- Department of Cell Biology and Human Anatomy, and Stem Cell Program, University of California Davis School of Medicine, Shriners Hospital For Children Northern California, Sacramento, California, United States of America
- * E-mail:
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Developmental sources of conservation and variation in the evolution of the primate eye. Proc Natl Acad Sci U S A 2009; 106:8963-8. [PMID: 19451636 DOI: 10.1073/pnas.0901484106] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Conserved developmental programs, such as the order of neurogenesis in the mammalian eye, suggest the presence of useful features for evolutionary stability and variability. The owl monkey, Aotus azarae, has developed a fully nocturnal retina in recent evolution. Description and quantification of cell cycle kinetics show that embryonic cytogenesis is extended in Aotus compared with the diurnal New World monkey Cebus apella. Combined with the conserved mammalian pattern of retinal cell specification, this single change in retinal progenitor cell proliferation can produce the multiple alterations of the nocturnal retina, including coordinated reduction in cone and ganglion cell numbers, increase in rod and rod bipolar numbers, and potentially loss of the fovea.
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Abstract
Just over 25 years ago, MYC, the human homologue of a retroviral oncogene, was identified. Since that time, MYC research has been intense and the advances impressive. On reflection, it is astonishing how each incremental insight into MYC regulation and function has also had an impact on numerous biological disciplines, including our understanding of molecular oncogenesis in general. Here we chronicle the major advances in our understanding of MYC biology, and peer into the future of MYC research.
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Cyclops. Can J Ophthalmol 2008. [DOI: 10.3129/i08-054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022]
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Abstract
Novel murine models of retinoblastoma based on Rb gene deletion in concert with inactivation of Rb family members have recently been developed. These new Rb knockout models of retinoblastoma provide excellent tools for pre-clinical studies and for the exploration of the genetics of tumorigenesis driven by RB inactivation. This review focuses on the developmental consequences of Rb deletion in the retina and the genetic interactions between Rb and the two other members of the pocket protein family, p107 (Rbl1) and p130 (Rbl2). There is increasing appreciation that homozygous RB mutations are insufficient for human retinoblastoma. Identifying and understanding secondary gene alterations that cooperate with RB inactivation in tumorigenesis may be facilitated by mouse models. Recent investigation of the p53 pathway in retinoblastoma, and evidence of spatial topology to early murine retinoblastoma are also discussed in this review.
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