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Griffith EC, West AE, Greenberg ME. Neuronal enhancers fine-tune adaptive circuit plasticity. Neuron 2024; 112:3043-3057. [PMID: 39208805 DOI: 10.1016/j.neuron.2024.08.002] [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: 05/01/2023] [Revised: 07/22/2024] [Accepted: 08/06/2024] [Indexed: 09/04/2024]
Abstract
Neuronal activity-regulated gene expression plays a crucial role in sculpting neural circuits that underpin adaptive brain function. Transcriptional enhancers are now recognized as key components of gene regulation that orchestrate spatiotemporally precise patterns of gene transcription. We propose that the dynamics of enhancer activation uniquely position these genomic elements to finely tune activity-dependent cellular plasticity. Enhancer specificity and modularity can be exploited to gain selective genetic access to specific cell states, and the precise modulation of target gene expression within restricted cellular contexts enabled by targeted enhancer manipulation allows for fine-grained evaluation of gene function. Mounting evidence also suggests that enduring stimulus-induced changes in enhancer states can modify target gene activation upon restimulation, thereby contributing to a form of cell-wide metaplasticity. We advocate for focused exploration of activity-dependent enhancer function to gain new insight into the mechanisms underlying brain plasticity and cognitive dysfunction.
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Affiliation(s)
- Eric C Griffith
- Department of Neurobiology, Harvard Medical School, Boston, MA, USA
| | - Anne E West
- Department of Neurobiology, Duke University Medical Center, Durham, NC, USA.
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2
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Avarlaid A, Falkenberg K, Lehe K, Mudò G, Belluardo N, Di Liberto V, Frinchi M, Tuvikene J, Timmusk T. An upstream enhancer and MEF2 transcription factors fine-tune the regulation of the Bdnf gene in cortical and hippocampal neurons. J Biol Chem 2024; 300:107411. [PMID: 38796067 PMCID: PMC11234010 DOI: 10.1016/j.jbc.2024.107411] [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: 01/15/2024] [Revised: 04/30/2024] [Accepted: 05/20/2024] [Indexed: 05/28/2024] Open
Abstract
The myocyte enhancer factor (MEF2) family of transcription factors, originally discovered for its pivotal role in muscle development and function, has emerged as an essential regulator in various aspects of brain development and neuronal plasticity. The MEF2 transcription factors are known to regulate numerous important genes in the nervous system, including brain-derived neurotrophic factor (BDNF), a small secreted neurotrophin responsible for promoting the survival, growth, and differentiation of neurons. The expression of the Bdnf gene is spatiotemporally controlled by various transcription factors binding to both its proximal and distal regulatory regions. While previous studies have investigated the connection between MEF2 transcription factors and Bdnf, the endogenous function of MEF2 factors in the transcriptional regulation of Bdnf remains largely unknown. Here, we aimed to deepen the knowledge of MEF2 transcription factors and their role in the regulation of Bdnf comparatively in rat cortical and hippocampal neurons. As a result, we demonstrate that the MEF2 transcription factor-dependent enhancer located at -4.8 kb from the Bdnf gene regulates the endogenous expression of Bdnf in hippocampal neurons. In addition, we confirm neuronal activity-dependent activation of the -4.8 kb enhancer in vivo. Finally, we show that specific MEF2 family transcription factors have unique roles in the regulation of Bdnf, with the specific function varying based on the particular brain region and stimuli. Altogether, we present MEF2 family transcription factors as crucial regulators of Bdnf expression, fine-tuning Bdnf expression through both distal and proximal regulatory regions.
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Affiliation(s)
- Annela Avarlaid
- Department of Chemistry and Biotechnology, Tallinn University of Technology, Tallinn, Estonia.
| | - Kaisa Falkenberg
- Department of Chemistry and Biotechnology, Tallinn University of Technology, Tallinn, Estonia
| | - Karin Lehe
- Department of Chemistry and Biotechnology, Tallinn University of Technology, Tallinn, Estonia
| | - Giuseppa Mudò
- Department of Biomedicine, Neuroscience and Advanced Diagnostic, University of Palermo, Palermo, Italy
| | - Natale Belluardo
- Department of Biomedicine, Neuroscience and Advanced Diagnostic, University of Palermo, Palermo, Italy
| | - Valentina Di Liberto
- Department of Biomedicine, Neuroscience and Advanced Diagnostic, University of Palermo, Palermo, Italy
| | - Monica Frinchi
- Department of Biomedicine, Neuroscience and Advanced Diagnostic, University of Palermo, Palermo, Italy
| | - Jürgen Tuvikene
- Department of Chemistry and Biotechnology, Tallinn University of Technology, Tallinn, Estonia; Protobios LLC, Tallinn, Estonia
| | - Tõnis Timmusk
- Department of Chemistry and Biotechnology, Tallinn University of Technology, Tallinn, Estonia; Protobios LLC, Tallinn, Estonia.
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3
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Becker S, L'Ecuyer Z, Jones BW, Zouache MA, McDonnell FS, Vinberg F. Modeling complex age-related eye disease. Prog Retin Eye Res 2024; 100:101247. [PMID: 38365085 PMCID: PMC11268458 DOI: 10.1016/j.preteyeres.2024.101247] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2023] [Revised: 01/31/2024] [Accepted: 02/02/2024] [Indexed: 02/18/2024]
Abstract
Modeling complex eye diseases like age-related macular degeneration (AMD) and glaucoma poses significant challenges, since these conditions depend highly on age-related changes that occur over several decades, with many contributing factors remaining unknown. Although both diseases exhibit a relatively high heritability of >50%, a large proportion of individuals carrying AMD- or glaucoma-associated genetic risk variants will never develop these diseases. Furthermore, several environmental and lifestyle factors contribute to and modulate the pathogenesis and progression of AMD and glaucoma. Several strategies replicate the impact of genetic risk variants, pathobiological pathways and environmental and lifestyle factors in AMD and glaucoma in mice and other species. In this review we will primarily discuss the most commonly available mouse models, which have and will likely continue to improve our understanding of the pathobiology of age-related eye diseases. Uncertainties persist whether small animal models can truly recapitulate disease progression and vision loss in patients, raising doubts regarding their usefulness when testing novel gene or drug therapies. We will elaborate on concerns that relate to shorter lifespan, body size and allometries, lack of macula and a true lamina cribrosa, as well as absence and sequence disparities of certain genes and differences in their chromosomal location in mice. Since biological, rather than chronological, age likely predisposes an organism for both glaucoma and AMD, more rapidly aging organisms like small rodents may open up possibilities that will make research of these diseases more timely and financially feasible. On the other hand, due to the above-mentioned anatomical and physiological features, as well as pharmacokinetic and -dynamic differences small animal models are not ideal to study the natural progression of vision loss or the efficacy and safety of novel therapies. In this context, we will also discuss the advantages and pitfalls of alternative models that include larger species, such as non-human primates and rabbits, patient-derived retinal organoids, and human organ donor eyes.
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Affiliation(s)
- Silke Becker
- John A. Moran Eye Center, University of Utah, Salt Lake City, UT, USA
| | - Zia L'Ecuyer
- John A. Moran Eye Center, University of Utah, Salt Lake City, UT, USA
| | - Bryan W Jones
- John A. Moran Eye Center, University of Utah, Salt Lake City, UT, USA
| | - Moussa A Zouache
- John A. Moran Eye Center, University of Utah, Salt Lake City, UT, USA
| | - Fiona S McDonnell
- John A. Moran Eye Center, University of Utah, Salt Lake City, UT, USA; Biomedical Engineering, University of Utah, Salt Lake City, UT, USA
| | - Frans Vinberg
- John A. Moran Eye Center, University of Utah, Salt Lake City, UT, USA; Biomedical Engineering, University of Utah, Salt Lake City, UT, USA.
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4
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Zheng Y, Chen S. Transcriptional precision in photoreceptor development and diseases - Lessons from 25 years of CRX research. Front Cell Neurosci 2024; 18:1347436. [PMID: 38414750 PMCID: PMC10896975 DOI: 10.3389/fncel.2024.1347436] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Accepted: 01/19/2024] [Indexed: 02/29/2024] Open
Abstract
The vertebrate retina is made up of six specialized neuronal cell types and one glia that are generated from a common retinal progenitor. The development of these distinct cell types is programmed by transcription factors that regulate the expression of specific genes essential for cell fate specification and differentiation. Because of the complex nature of transcriptional regulation, understanding transcription factor functions in development and disease is challenging. Research on the Cone-rod homeobox transcription factor CRX provides an excellent model to address these challenges. In this review, we reflect on 25 years of mammalian CRX research and discuss recent progress in elucidating the distinct pathogenic mechanisms of four CRX coding variant classes. We highlight how in vitro biochemical studies of CRX protein functions facilitate understanding CRX regulatory principles in animal models. We conclude with a brief discussion of the emerging systems biology approaches that could accelerate precision medicine for CRX-linked diseases and beyond.
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Affiliation(s)
- Yiqiao Zheng
- Molecular Genetics and Genomics Graduate Program, Division of Biological and Biomedical Sciences, Saint Louis, MO, United States
- Department of Ophthalmology and Visual Sciences, Saint Louis, MO, United States
| | - Shiming Chen
- Molecular Genetics and Genomics Graduate Program, Division of Biological and Biomedical Sciences, Saint Louis, MO, United States
- Department of Ophthalmology and Visual Sciences, Saint Louis, MO, United States
- Department of Developmental Biology, Washington University in St. Louis, Saint Louis, MO, United States
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5
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Pan D, Zhang X, Jin K, Jin ZB. CRX haploinsufficiency compromises photoreceptor precursor translocation and differentiation in human retinal organoids. Stem Cell Res Ther 2023; 14:346. [PMID: 38049871 PMCID: PMC10696917 DOI: 10.1186/s13287-023-03590-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2023] [Accepted: 11/28/2023] [Indexed: 12/06/2023] Open
Abstract
BACKGROUND The CRX-associated autosomal dominant retinopathies suggest a possible pathogenic mechanism of gene haploinsufficiency. However, based on reported human patient cases and studies with mouse models, it is hard to confirm the specific weight of haploinsufficiency in pathogenesis due to the interspecies gaps between gene expression and function. METHODS We created monoallelic CRX by replacing one allele with tdTomato in human embryonic stem cells (hESCs) and subsequently dissect pathogenesis in hESCs-derived retinal organoids. We used transcriptome and immunofluorescence analyses to dissect phenotypic differences between CRX-monoallelic knockout and control wildtype organoids. For location analysis of CRX+ cells, a CRX-expression-tracing system was constructed in control hESCs. We implemented long-term live-cell imaging to describe the translocation of CRX+ cells between two groups in early organoid differentiation. The expression pattern of these dynamic differences was validated using RNA-seq and immunofluorescence assays. RESULTS We identified delayed differentiation of outer nuclear layer (ONL) stratification along with thinner ONL, serious loss of photoreceptor outer segments, as well as downregulated expression of gene for phototransduction and inner/outer segment formation. By live-cell imaging and immunostaining, we observed the overtension of actomyosin network and the arrested translocation of monoallelic CRX+ cells in the early stage of retinal differentiation. CONCLUSIONS We confirmed that gene haploinsufficiency is the mechanism for the dominant pathogenicity of CRX and discovered that CRX regulated postmitotic photoreceptor precursor translocation in addition to its specification of photoreceptor cell fates during human retinal development. These findings revealed a new underlying mechanism of CRX dominant pathogenesis and provided a new clue for the treatment of CRX-associated human retinopathies.
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Affiliation(s)
- Deng Pan
- Beijing Institute of Ophthalmology, Beijing Tongren Hospital, Capital Medical University, Beijing, 100730, China.
| | - Xiao Zhang
- Beijing Institute of Ophthalmology, Beijing Tongren Hospital, Capital Medical University, Beijing, 100730, China
| | - Kangxin Jin
- Beijing Institute of Ophthalmology, Beijing Tongren Hospital, Capital Medical University, Beijing, 100730, China
| | - Zi-Bing Jin
- Beijing Institute of Ophthalmology, Beijing Tongren Hospital, Capital Medical University, Beijing, 100730, China.
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6
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Wang J, Cheng X, Liang Q, Owen LA, Lu J, Zheng Y, Wang M, Chen S, DeAngelis MM, Li Y, Chen R. Single-cell multiomics of the human retina reveals hierarchical transcription factor collaboration in mediating cell type-specific effects of genetic variants on gene regulation. Genome Biol 2023; 24:269. [PMID: 38012720 PMCID: PMC10680294 DOI: 10.1186/s13059-023-03111-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2022] [Accepted: 11/15/2023] [Indexed: 11/29/2023] Open
Abstract
BACKGROUND Systematic characterization of how genetic variation modulates gene regulation in a cell type-specific context is essential for understanding complex traits. To address this question, we profile gene expression and chromatin accessibility in cells from healthy retinae of 20 human donors through single-cell multiomics and genomic sequencing. RESULTS We map eQTL, caQTL, allelic-specific expression, and allelic-specific chromatin accessibility in major retinal cell types. By integrating these results, we identify and characterize regulatory elements and genetic variants effective on gene regulation in individual cell types. The majority of identified sc-eQTLs and sc-caQTLs display cell type-specific effects, while the cis-elements containing genetic variants with cell type-specific effects are often accessible in multiple cell types. Furthermore, the transcription factors whose binding sites are perturbed by genetic variants tend to have higher expression levels in the cell types where the variants exert their effects, compared to the cell types where the variants have no impact. We further validate our findings with high-throughput reporter assays. Lastly, we identify the enriched cell types, candidate causal variants and genes, and cell type-specific regulatory mechanism underlying GWAS loci. CONCLUSIONS Overall, genetic effects on gene regulation are highly context dependent. Our results suggest that cell type-dependent genetic effect is driven by precise modulation of both trans-factor expression and chromatin accessibility of cis-elements. Our findings indicate hierarchical collaboration among transcription factors plays a crucial role in mediating cell type-specific effects of genetic variants on gene regulation.
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Affiliation(s)
- Jun Wang
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX, USA
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Xuesen Cheng
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX, USA
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Qingnan Liang
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX, USA
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX, USA
| | - Leah A Owen
- Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center, University of Utah, Salt Lake City, UT, USA
| | - Jiaxiong Lu
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX, USA
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX, USA
| | - Yiqiao Zheng
- Department of Ophthalmology and Visual Sciences, Washington University in St Louis, Saint Louis, MO, USA
| | - Meng Wang
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX, USA
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Shiming Chen
- Department of Ophthalmology and Visual Sciences, Washington University in St Louis, Saint Louis, MO, USA
- Department of Developmental Biology, Washington University in St Louis, Saint Louis, MO, USA
| | - Margaret M DeAngelis
- Department of Ophthalmology, University at Buffalo the State University of New York, Buffalo, NY, USA
| | - Yumei Li
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX, USA
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Rui Chen
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX, USA.
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA.
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7
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Yin H, Wang J, Tan Y, Jiang M, Zhang H, Meng G. Transcription factor abnormalities in B-ALL leukemogenesis and treatment. Trends Cancer 2023; 9:855-870. [PMID: 37407363 DOI: 10.1016/j.trecan.2023.06.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2022] [Revised: 05/29/2023] [Accepted: 06/06/2023] [Indexed: 07/07/2023]
Abstract
The biological regulation of transcription factors (TFs) and repressor proteins is an important mechanism for maintaining cell homeostasis. In B cell acute lymphoblastic leukemia (B-ALL) TF abnormalities occur at high frequency and are often recognized as the major driving factor in carcinogenesis. We provide an in-depth review of molecular mechanisms of six major TF rearrangements in B-ALL, including DUX4-rearranged (DUX4-R), MEF2D-R, ZNF384-R, ETV6-RUNX1 and TCF3-PBX1 fusions, and KMT2A-R. In addition, the therapeutic options and prognoses for patients who harbor these TF abnormalities are discussed. This review aims to provide an up-to-date panoramic view of how TF-based oncogenic fusions might drive carcinogenesis and impact on potential therapeutic exploration of B-ALL treatments.
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Affiliation(s)
- Hongxin Yin
- Shanghai Institute of Hematology, State Key Laboratory of Medical Genomics, National Research Center for Translational Medicine, Rui-Jin Hospital, School of Medicine and School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200025, China
| | - Junfei Wang
- Shanghai Institute of Hematology, State Key Laboratory of Medical Genomics, National Research Center for Translational Medicine, Rui-Jin Hospital, School of Medicine and School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200025, China
| | - Yangxia Tan
- Shanghai Institute of Hematology, State Key Laboratory of Medical Genomics, National Research Center for Translational Medicine, Rui-Jin Hospital, School of Medicine and School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200025, China
| | - Minghao Jiang
- Shanghai Institute of Hematology, State Key Laboratory of Medical Genomics, National Research Center for Translational Medicine, Rui-Jin Hospital, School of Medicine and School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200025, China
| | - Hao Zhang
- Institute for Translational Brain Research, Ministry of Education (MOE) Frontiers Center for Brain Science, Fudan University, 200032 Shanghai, China.
| | - Guoyu Meng
- Shanghai Institute of Hematology, State Key Laboratory of Medical Genomics, National Research Center for Translational Medicine, Rui-Jin Hospital, School of Medicine and School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200025, China.
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8
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The Role of MEF2 Transcription Factor Family in Neuronal Survival and Degeneration. Int J Mol Sci 2023; 24:ijms24043120. [PMID: 36834528 PMCID: PMC9963821 DOI: 10.3390/ijms24043120] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2022] [Revised: 01/15/2023] [Accepted: 02/01/2023] [Indexed: 02/09/2023] Open
Abstract
The family of myocyte enhancer factor 2 (MEF2) transcription factors comprises four highly conserved members that play an important role in the nervous system. They appear in precisely defined time frames in the developing brain to turn on and turn off genes affecting growth, pruning and survival of neurons. MEF2s are known to dictate neuronal development, synaptic plasticity and restrict the number of synapses in the hippocampus, thus affecting learning and memory formation. In primary neurons, negative regulation of MEF2 activity by external stimuli or stress conditions is known to induce apoptosis, albeit the pro or antiapoptotic action of MEF2 depends on the neuronal maturation stage. By contrast, enhancement of MEF2 transcriptional activity protects neurons from apoptotic death both in vitro and in preclinical models of neurodegenerative diseases. A growing body of evidence places this transcription factor in the center of many neuropathologies associated with age-dependent neuronal dysfunctions or gradual but irreversible neuron loss. In this work, we discuss how the altered function of MEF2s during development and in adulthood affecting neuronal survival may be linked to neuropsychiatric disorders.
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9
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Zhang M, Zhang H, Li Z, Bai L, Wang Q, Li J, Jiang M, Xue Q, Cheng N, Zhang W, Mao D, Chen Z, Huang J, Meng G, Chen Z, Chen SJ. Functional, structural, and molecular characterizations of the leukemogenic driver MEF2D-HNRNPUL1 fusion. Blood 2022; 140:1390-1407. [PMID: 35544603 PMCID: PMC9507012 DOI: 10.1182/blood.2022016241] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2022] [Accepted: 05/03/2022] [Indexed: 12/02/2022] Open
Abstract
Recurrent MEF2D fusions with poor prognosis have been identified in B-cell precursor ALL (BCP-ALL). The molecular mechanisms underlying the pathogenic function of MEF2D fusions are poorly understood. Here, we show that MEF2D-HNRNPUL1 (MH) knock-in mice developed a progressive disease from impaired B-cell development at the pre-pro-B stage to pre-leukemia over 10 to 12 months. When cooperating with NRASG12D, MH drove an outbreak of BCP-ALL, with a more aggressive phenotype than the NRASG12D-induced leukemia. RNA-sequencing identified key networks involved in disease mechanisms. In chromatin immunoprecipitation-sequencing experiments, MH acquired increased chromatin-binding ability, mostly through MEF2D-responsive element (MRE) motifs in target genes, compared with wild-type MEF2D. Using X-ray crystallography, the MEF2D-MRE complex was characterized in atomic resolution, whereas disrupting the MH-DNA interaction alleviated the aberrant target gene expression and the B-cell differentiation arrest. The C-terminal moiety (HNRNPUL1 part) of MH was proven to contribute to the fusion protein's trans-regulatory activity, cofactor recruitment, and homodimerization. Furthermore, targeting MH-driven transactivation of the HDAC family by using the histone deacetylase inhibitor panobinostat in combination with chemotherapy improved the overall survival of MH/NRASG12D BCP-ALL mice. Altogether, these results not only highlight MH as an important driver in leukemogenesis but also provoke targeted intervention against BCP-ALL with MEF2D fusions.
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Affiliation(s)
- Ming Zhang
- Shanghai Institute of Hematology, State Key Laboratory of Medical Genomics, National Research Center for Translational Medicine at Shanghai, Ruijin Hospital, Shanghai JiaoTong University School of Medicine and School of Life Sciences and Biotechnology, Shanghai JiaoTong University, Shanghai, China
| | - Hao Zhang
- Shanghai Institute of Hematology, State Key Laboratory of Medical Genomics, National Research Center for Translational Medicine at Shanghai, Ruijin Hospital, Shanghai JiaoTong University School of Medicine and School of Life Sciences and Biotechnology, Shanghai JiaoTong University, Shanghai, China
| | - Zhihui Li
- Shanghai Institute of Hematology, State Key Laboratory of Medical Genomics, National Research Center for Translational Medicine at Shanghai, Ruijin Hospital, Shanghai JiaoTong University School of Medicine and School of Life Sciences and Biotechnology, Shanghai JiaoTong University, Shanghai, China
| | - Ling Bai
- Shanghai Institute of Hematology, State Key Laboratory of Medical Genomics, National Research Center for Translational Medicine at Shanghai, Ruijin Hospital, Shanghai JiaoTong University School of Medicine and School of Life Sciences and Biotechnology, Shanghai JiaoTong University, Shanghai, China
| | - Qianqian Wang
- Shanghai Institute of Hematology, State Key Laboratory of Medical Genomics, National Research Center for Translational Medicine at Shanghai, Ruijin Hospital, Shanghai JiaoTong University School of Medicine and School of Life Sciences and Biotechnology, Shanghai JiaoTong University, Shanghai, China
| | - Jianfeng Li
- Shanghai Institute of Hematology, State Key Laboratory of Medical Genomics, National Research Center for Translational Medicine at Shanghai, Ruijin Hospital, Shanghai JiaoTong University School of Medicine and School of Life Sciences and Biotechnology, Shanghai JiaoTong University, Shanghai, China
| | - Minghao Jiang
- Shanghai Institute of Hematology, State Key Laboratory of Medical Genomics, National Research Center for Translational Medicine at Shanghai, Ruijin Hospital, Shanghai JiaoTong University School of Medicine and School of Life Sciences and Biotechnology, Shanghai JiaoTong University, Shanghai, China
| | - Qing Xue
- Shanghai Institute of Hematology, State Key Laboratory of Medical Genomics, National Research Center for Translational Medicine at Shanghai, Ruijin Hospital, Shanghai JiaoTong University School of Medicine and School of Life Sciences and Biotechnology, Shanghai JiaoTong University, Shanghai, China
| | - Nuo Cheng
- Shanghai Institute of Hematology, State Key Laboratory of Medical Genomics, National Research Center for Translational Medicine at Shanghai, Ruijin Hospital, Shanghai JiaoTong University School of Medicine and School of Life Sciences and Biotechnology, Shanghai JiaoTong University, Shanghai, China
| | - Weina Zhang
- Shanghai Institute of Hematology, State Key Laboratory of Medical Genomics, National Research Center for Translational Medicine at Shanghai, Ruijin Hospital, Shanghai JiaoTong University School of Medicine and School of Life Sciences and Biotechnology, Shanghai JiaoTong University, Shanghai, China
| | - Dongdong Mao
- Shanghai Institute of Hematology, State Key Laboratory of Medical Genomics, National Research Center for Translational Medicine at Shanghai, Ruijin Hospital, Shanghai JiaoTong University School of Medicine and School of Life Sciences and Biotechnology, Shanghai JiaoTong University, Shanghai, China
| | - Zhiming Chen
- Shanghai Institute of Hematology, State Key Laboratory of Medical Genomics, National Research Center for Translational Medicine at Shanghai, Ruijin Hospital, Shanghai JiaoTong University School of Medicine and School of Life Sciences and Biotechnology, Shanghai JiaoTong University, Shanghai, China
| | - Jinyan Huang
- Shanghai Institute of Hematology, State Key Laboratory of Medical Genomics, National Research Center for Translational Medicine at Shanghai, Ruijin Hospital, Shanghai JiaoTong University School of Medicine and School of Life Sciences and Biotechnology, Shanghai JiaoTong University, Shanghai, China
| | - Guoyu Meng
- Shanghai Institute of Hematology, State Key Laboratory of Medical Genomics, National Research Center for Translational Medicine at Shanghai, Ruijin Hospital, Shanghai JiaoTong University School of Medicine and School of Life Sciences and Biotechnology, Shanghai JiaoTong University, Shanghai, China
| | - Zhu Chen
- Shanghai Institute of Hematology, State Key Laboratory of Medical Genomics, National Research Center for Translational Medicine at Shanghai, Ruijin Hospital, Shanghai JiaoTong University School of Medicine and School of Life Sciences and Biotechnology, Shanghai JiaoTong University, Shanghai, China
| | - Sai-Juan Chen
- Shanghai Institute of Hematology, State Key Laboratory of Medical Genomics, National Research Center for Translational Medicine at Shanghai, Ruijin Hospital, Shanghai JiaoTong University School of Medicine and School of Life Sciences and Biotechnology, Shanghai JiaoTong University, Shanghai, China
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10
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Lu Z, Mao W, Yang H, Santiago-O'Farrill JM, Rask PJ, Mondal J, Chen H, Ivan C, Liu X, Liu CG, Xi Y, Masuda K, Carrami EM, Chen M, Tang Y, Pang L, Lakomy DS, Calin GA, Liang H, Ahmed AA, Vankayalapati H, Bast RC. SIK2 inhibition enhances PARP inhibitor activity synergistically in ovarian and triple-negative breast cancers. J Clin Invest 2022; 132:146471. [PMID: 35642638 PMCID: PMC9151707 DOI: 10.1172/jci146471] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Accepted: 04/19/2022] [Indexed: 12/21/2022] Open
Abstract
Poly(ADP-ribose) polymerase inhibitors (PARP inhibitors) have had an increasing role in the treatment of ovarian and breast cancers. PARP inhibitors are selectively active in cells with homologous recombination DNA repair deficiency caused by mutations in BRCA1/2 and other DNA repair pathway genes. Cancers with homologous recombination DNA repair proficiency respond poorly to PARP inhibitors. Cancers that initially respond to PARP inhibitors eventually develop drug resistance. We have identified salt-inducible kinase 2 (SIK2) inhibitors, ARN3236 and ARN3261, which decreased DNA double-strand break (DSB) repair functions and produced synthetic lethality with multiple PARP inhibitors in both homologous recombination DNA repair deficiency and proficiency cancer cells. SIK2 is required for centrosome splitting and PI3K activation and regulates cancer cell proliferation, metastasis, and sensitivity to chemotherapy. Here, we showed that SIK2 inhibitors sensitized ovarian and triple-negative breast cancer (TNBC) cells and xenografts to PARP inhibitors. SIK2 inhibitors decreased PARP enzyme activity and phosphorylation of class-IIa histone deacetylases (HDAC4/5/7). Furthermore, SIK2 inhibitors abolished class-IIa HDAC4/5/7-associated transcriptional activity of myocyte enhancer factor-2D (MEF2D), decreasing MEF2D binding to regulatory regions with high chromatin accessibility in FANCD2, EXO1, and XRCC4 genes, resulting in repression of their functions in the DNA DSB repair pathway. The combination of PARP inhibitors and SIK2 inhibitors provides a therapeutic strategy to enhance PARP inhibitor sensitivity for ovarian cancer and TNBC.
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Affiliation(s)
- Zhen Lu
- Department of Experimental Therapeutics
| | | | | | | | | | | | - Hu Chen
- Department of Bioinformatics & Computational Biology, and
| | - Cristina Ivan
- Department of Experimental Therapeutics.,Department of Translational Molecular Pathology, University of Texas MD Anderson Cancer Center, Houston, Texas, USA
| | | | | | - Yuanxin Xi
- Department of Bioinformatics & Computational Biology, and
| | - Kenta Masuda
- The University of Texas MD Anderson UTHealth Graduate School of Biomedical Sciences, Houston, Texas, USA.,Ovarian Cancer Cell Laboratory, Weatherall Institute of Molecular Medicine, University of Oxford, Headington, Oxford, United Kingdom
| | - Eli M Carrami
- The University of Texas MD Anderson UTHealth Graduate School of Biomedical Sciences, Houston, Texas, USA.,Ovarian Cancer Cell Laboratory, Weatherall Institute of Molecular Medicine, University of Oxford, Headington, Oxford, United Kingdom
| | - Meng Chen
- Department of Translational Molecular Pathology, University of Texas MD Anderson Cancer Center, Houston, Texas, USA
| | - Yitao Tang
- Department of Bioinformatics & Computational Biology, and.,The University of Texas MD Anderson UTHealth Graduate School of Biomedical Sciences, Houston, Texas, USA
| | - Lan Pang
- Department of Translational Molecular Pathology, University of Texas MD Anderson Cancer Center, Houston, Texas, USA
| | | | - George A Calin
- Department of Translational Molecular Pathology, University of Texas MD Anderson Cancer Center, Houston, Texas, USA
| | - Han Liang
- Department of Bioinformatics & Computational Biology, and.,Department of Systems Biology, University of Texas MD Anderson Cancer Center, Houston, Texas, USA
| | - Ahmed A Ahmed
- Ovarian Cancer Cell Laboratory, Weatherall Institute of Molecular Medicine, University of Oxford, Headington, Oxford, United Kingdom.,Nuffield Department of Women's & Reproductive Health, University of Oxford, Women's Centre, John Radcliffe Hospital, Oxford, United Kingdom.,Oxford NIHR Biomedical Research Centre, Oxford, United Kingdom
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11
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Pumo GM, Kitazawa T, Rijli FM. Epigenetic and Transcriptional Regulation of Spontaneous and Sensory Activity Dependent Programs During Neuronal Circuit Development. Front Neural Circuits 2022; 16:911023. [PMID: 35664458 PMCID: PMC9158562 DOI: 10.3389/fncir.2022.911023] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Accepted: 04/28/2022] [Indexed: 11/13/2022] Open
Abstract
Spontaneous activity generated before the onset of sensory transduction has a key role in wiring developing sensory circuits. From axonal targeting, to synapse formation and elimination, to the balanced integration of neurons into developing circuits, this type of activity is implicated in a variety of cellular processes. However, little is known about its molecular mechanisms of action, especially at the level of genome regulation. Conversely, sensory experience-dependent activity implements well-characterized transcriptional and epigenetic chromatin programs that underlie heterogeneous but specific genomic responses that shape both postnatal circuit development and neuroplasticity in the adult. In this review, we focus on our knowledge of the developmental processes regulated by spontaneous activity and the underlying transcriptional mechanisms. We also review novel findings on how chromatin regulates the specificity and developmental induction of the experience-dependent program, and speculate their relevance for our understanding of how spontaneous activity may act at the genomic level to instruct circuit assembly and prepare developing neurons for sensory-dependent connectivity refinement and processing.
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Affiliation(s)
- Gabriele M. Pumo
- Laboratory of Neurodevelopmental Epigenetics, Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
- Department Biozentrum, University of Basel, Basel, Switzerland
| | - Taro Kitazawa
- Laboratory of Neurodevelopmental Epigenetics, Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
| | - Filippo M. Rijli
- Laboratory of Neurodevelopmental Epigenetics, Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
- Department Biozentrum, University of Basel, Basel, Switzerland
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12
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Thomas ED, Timms AE, Giles S, Harkins-Perry S, Lyu P, Hoang T, Qian J, Jackson VE, Bahlo M, Blackshaw S, Friedlander M, Eade K, Cherry TJ. Cell-specific cis-regulatory elements and mechanisms of non-coding genetic disease in human retina and retinal organoids. Dev Cell 2022; 57:820-836.e6. [PMID: 35303433 PMCID: PMC9126240 DOI: 10.1016/j.devcel.2022.02.018] [Citation(s) in RCA: 31] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Revised: 12/06/2021] [Accepted: 02/18/2022] [Indexed: 01/05/2023]
Abstract
Cis-regulatory elements (CREs) play a critical role in the development and disease-states of all human cell types. In the retina, CREs have been implicated in several inherited disorders. To better characterize human retinal CREs, we performed single-nucleus assay for transposase-accessible chromatin sequencing (snATAC-seq) and single-nucleus RNA sequencing (snRNA-seq) on the developing and adult human retina and on induced pluripotent stem cell (iPSC)-derived retinal organoids. These analyses identified developmentally dynamic, cell-class-specific CREs, enriched transcription-factor-binding motifs, and putative target genes. CREs in the retina and organoids are highly correlated at the single-cell level, and this supports the use of organoids as a model for studying disease-associated CREs. As a proof of concept, we disrupted a disease-associated CRE at 5q14.3, confirming its principal target gene as the miR-9-2 primary transcript and demonstrating its role in neurogenesis and gene regulation in mature glia. This study provides a resource for characterizing human retinal CREs and showcases organoids as a model to study the function of CREs that influence development and disease.
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Affiliation(s)
- Eric D Thomas
- Center for Developmental Biology and Regenerative Medicine, Seattle Children's Research Institute, Seattle, WA 98101, USA
| | - Andrew E Timms
- Center for Developmental Biology and Regenerative Medicine, Seattle Children's Research Institute, Seattle, WA 98101, USA
| | - Sarah Giles
- Lowy Medical Research Institute, La Jolla, CA 92037, USA; Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Sarah Harkins-Perry
- Lowy Medical Research Institute, La Jolla, CA 92037, USA; Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Pin Lyu
- Department of Ophthalmology, Wilmer Eye Institute Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Thanh Hoang
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Jiang Qian
- Department of Ophthalmology, Wilmer Eye Institute Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Victoria E Jackson
- Population Health and Immunity Division, The Walter and Eliza Hall Institute of Medical Research, Parkville 3052, VIC, Australia; Department of Medical Biology, The University of Melbourne, Parkville 3052, VIC, Australia
| | - Melanie Bahlo
- Population Health and Immunity Division, The Walter and Eliza Hall Institute of Medical Research, Parkville 3052, VIC, Australia; Department of Medical Biology, The University of Melbourne, Parkville 3052, VIC, Australia
| | - Seth Blackshaw
- Department of Ophthalmology, Wilmer Eye Institute Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; Kavli Neuroscience Discovery Institute, Johns Hopkins University, Baltimore, MD 21218, USA; Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Martin Friedlander
- Lowy Medical Research Institute, La Jolla, CA 92037, USA; Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Kevin Eade
- Lowy Medical Research Institute, La Jolla, CA 92037, USA; Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA 92037, USA.
| | - Timothy J Cherry
- Center for Developmental Biology and Regenerative Medicine, Seattle Children's Research Institute, Seattle, WA 98101, USA; Department of Pediatrics, University of Washington School of Medicine, Seattle, WA 98195, USA; Department of Biological Structure, University of Washington School of Medicine, Seattle, WA 98195, USA; Department of Ophthalmology, University of Washington School of Medicine, Seattle, WA 98195, USA; Brotman Baty Institute, Seattle, WA 98195, USA.
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13
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Mustafi D, Hisama FM, Huey J, Chao JR. The current state of genetic testing platforms for inherited retinal diseases. Ophthalmol Retina 2022; 6:702-710. [PMID: 35307606 PMCID: PMC9356993 DOI: 10.1016/j.oret.2022.03.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Revised: 03/08/2022] [Accepted: 03/14/2022] [Indexed: 11/30/2022]
Abstract
PURPOSE To evaluate genetic testing platforms used to aid in the diagnosis of inherited retinal degenerations (IRDs). DESIGN Evaluation of diagnostic test or technology SUBJECTS: Targeted genetic panel testing for IRDs METHODS, INTERVENTION, OR TESTING: Data collected regarding targeted genetic panel testing for IRDs offered by different labs were investigated for inclusion of coding and non-coding variants in disease genes. Both large IRD panels and smaller, more focused disease specific panels were included in the analysis. MAIN OUTCOME MEASURES Number of disease genes tested as well as the commonality and uniqueness across testing platforms in both coding and non-coding variants of disease. RESULTS Across the three IRD panel tests investigated, 409 unique genes are represented, of which 269 genes are tested by all three panels. The top 20 genes known to cause over 70% of all IRDs are represented in the 269 common genes tested by all three panels. In addition, 138 non-coding variants are assayed across the three platforms in 50 unique genes. Focused disease specific panels exhibited significant variability across 5 testing platforms that were studied. CONCLUSIONS Ordering genetic testing for IRDs is not straightforward, as evidenced by the multitude of panels available to providers. It is important that there is coverage of both coding and non-coding regions in IRD genes to offer a diagnosis in these patients. This paper details the diversity of testing platforms currently available to clinicians and provides a thorough explanation of genes tested in the different IRD panels. In a time of increased importance for clinical genetic testing of IRD patients, knowledge of the proper test to order is paramount.
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Affiliation(s)
- Debarshi Mustafi
- Department of Ophthalmology, University of Washington, Seattle, Washington; Department of Ophthalmology, Seattle Children's Hospital, Seattle, Washington.
| | - Fuki M Hisama
- Division of Medical Genetics, Department of Medicine, University of Washington, Seattle, Washington
| | - Jennifer Huey
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, Washington
| | - Jennifer R Chao
- Department of Ophthalmology, University of Washington, Seattle, Washington
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14
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Zibetti C. Deciphering the Retinal Epigenome during Development, Disease and Reprogramming: Advancements, Challenges and Perspectives. Cells 2022; 11:cells11050806. [PMID: 35269428 PMCID: PMC8908986 DOI: 10.3390/cells11050806] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2022] [Revised: 02/15/2022] [Accepted: 02/18/2022] [Indexed: 02/01/2023] Open
Abstract
Retinal neurogenesis is driven by concerted actions of transcription factors, some of which are expressed in a continuum and across several cell subtypes throughout development. While seemingly redundant, many factors diversify their regulatory outcome on gene expression, by coordinating variations in chromatin landscapes to drive divergent retinal specification programs. Recent studies have furthered the understanding of the epigenetic contribution to the progression of age-related macular degeneration, a leading cause of blindness in the elderly. The knowledge of the epigenomic mechanisms that control the acquisition and stabilization of retinal cell fates and are evoked upon damage, holds the potential for the treatment of retinal degeneration. Herein, this review presents the state-of-the-art approaches to investigate the retinal epigenome during development, disease, and reprogramming. A pipeline is then reviewed to functionally interrogate the epigenetic and transcriptional networks underlying cell fate specification, relying on a truly unbiased screening of open chromatin states. The related work proposes an inferential model to identify gene regulatory networks, features the first footprinting analysis and the first tentative, systematic query of candidate pioneer factors in the retina ever conducted in any model organism, leading to the identification of previously uncharacterized master regulators of retinal cell identity, such as the nuclear factor I, NFI. This pipeline is virtually applicable to the study of genetic programs and candidate pioneer factors in any developmental context. Finally, challenges and limitations intrinsic to the current next-generation sequencing techniques are discussed, as well as recent advances in super-resolution imaging, enabling spatio-temporal resolution of the genome.
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Affiliation(s)
- Cristina Zibetti
- Department of Ophthalmology, Institute of Clinical Medicine, University of Oslo, Kirkeveien 166, Building 36, 0455 Oslo, Norway
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15
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Patasova K, Haarman AEG, Musolf AM, Mahroo OA, Rahi JS, Falchi M, Verhoeven VJM, Bailey-Wilson JE, Klaver CCW, Duggal P, Klein A, Guggenheim JA, Hammond CJ, Hysi PG. Association analyses of rare variants identify two genes associated with refractive error. PLoS One 2022; 17:e0272379. [PMID: 36137074 PMCID: PMC9499304 DOI: 10.1371/journal.pone.0272379] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Accepted: 07/18/2022] [Indexed: 11/19/2022] Open
Abstract
PURPOSE Genetic variants identified through population-based genome-wide studies are generally of high frequency, exerting their action in the central part of the refractive error spectrum. However, the power to identify associations with variants of lower minor allele frequency is greatly reduced, requiring considerable sample sizes. Here we aim to assess the impact of rare variants on genetic variation of refractive errors in a very large general population cohort. METHODS Genetic association analyses of non-cyclopaedic autorefraction calculated as mean spherical equivalent (SPHE) used whole-exome sequence genotypic information from 50,893 unrelated participants in the UK Biobank of European ancestry. Gene-based analyses tested for association with SPHE using an optimised SNP-set kernel association test (SKAT-O) restricted to rare variants (minor allele frequency < 1%) within protein-coding regions of the genome. All models were adjusted for age, sex and common lead variants within the same locus reported by previous genome-wide association studies. Potentially causal markers driving association at significant loci were elucidated using sensitivity analyses by sequentially dropping the most associated variants from gene-based analyses. RESULTS We found strong statistical evidence for association of SPHE with the SIX6 (p-value = 2.15 x 10-10, or Bonferroni-Corrected p = 4.41x10-06) and the CRX gene (p-value = 6.65 x 10-08, or Bonferroni-Corrected p = 0.001). The SIX6 gene codes for a transcription factor believed to be critical to the eye, retina and optic disc development and morphology, while CRX regulates photoreceptor specification and expression of over 700 genes in the retina. These novel associations suggest an important role of genes involved in eye morphogenesis in refractive error. CONCLUSION The results of our study support previous research highlighting the importance of rare variants to the genetic risk of refractive error. We explain some of the origins of the genetic signals seen in GWAS but also report for the first time a completely novel association with the CRX gene.
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Affiliation(s)
- Karina Patasova
- Department of Ophthalmology, King’s College London, London, United Kingdom
- Department of Twins Research and Genetic Epidemiology, King’s College London, London, United Kingdom
| | - Annechien E. G. Haarman
- Department of Ophthalmology, Erasmus Medical Center, Rotterdam, The Netherlands
- Department of Epidemiology, Erasmus MC, Rotterdam, The Netherlands
| | - Anthony M. Musolf
- Computational and Statistical Genomics Branch, National Human Genome Research Institute, National Institutes of Health, Baltimore, Maryland, United States of America
| | - Omar A. Mahroo
- Department of Ophthalmology, King’s College London, London, United Kingdom
- Department of Twins Research and Genetic Epidemiology, King’s College London, London, United Kingdom
- NIHR Biomedical Research Centre at Moorfields Eye Hospital NHS Foundation Trust and the UCL Institute of Ophthalmology, London, United Kingdom
- Department of Ophthalmology, St Thomas’ Hospital, Guys and St ’Thomas’ NHS Foundation Trust, London, United Kingdom
- Institute of Ophthalmology, University College London, London, United Kingdom
| | - Jugnoo S. Rahi
- UCL Great Ormond Street Hospital Institute of Child Health, London, United Kingdom
- Ulverscroft Vision Research Group, University College London, London, United Kingdom
| | - Mario Falchi
- Department of Twins Research and Genetic Epidemiology, King’s College London, London, United Kingdom
| | - Virginie J. M. Verhoeven
- Department of Ophthalmology, Erasmus Medical Center, Rotterdam, The Netherlands
- Department of Epidemiology, Erasmus MC, Rotterdam, The Netherlands
| | - Joan E. Bailey-Wilson
- Computational and Statistical Genomics Branch, National Human Genome Research Institute, National Institutes of Health, Baltimore, Maryland, United States of America
| | - Caroline C. W. Klaver
- Department of Ophthalmology, Erasmus Medical Center, Rotterdam, The Netherlands
- Department of Epidemiology, Erasmus MC, Rotterdam, The Netherlands
- Department of Ophthalmology, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Priya Duggal
- Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, United States of America
| | - Alison Klein
- Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, United States of America
- Department of Oncology, Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins, Johns Hopkins University, Baltimore, Maryland, United States of America
- Department of Pathology, Johns Hopkins School of Medicine, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Jeremy A. Guggenheim
- School of Optometry & Vision Sciences, Cardiff University, Cardiff, United Kingdom
| | - Chris J. Hammond
- Department of Ophthalmology, King’s College London, London, United Kingdom
- Department of Twins Research and Genetic Epidemiology, King’s College London, London, United Kingdom
| | - Pirro G. Hysi
- Department of Ophthalmology, King’s College London, London, United Kingdom
- Department of Twins Research and Genetic Epidemiology, King’s College London, London, United Kingdom
- UCL Great Ormond Street Hospital Institute of Child Health, London, United Kingdom
- * E-mail:
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16
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Daghsni M, Aldiri I. Building a Mammalian Retina: An Eye on Chromatin Structure. Front Genet 2021; 12:775205. [PMID: 34764989 PMCID: PMC8576187 DOI: 10.3389/fgene.2021.775205] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Accepted: 10/08/2021] [Indexed: 11/13/2022] Open
Abstract
Regulation of gene expression by chromatin structure has been under intensive investigation, establishing nuclear organization and genome architecture as a potent and effective means of regulating developmental processes. The substantial growth in our knowledge of the molecular mechanisms underlying retinogenesis has been powered by several genome-wide based tools that mapped chromatin organization at multiple cellular and biochemical levels. Studies profiling the retinal epigenome and transcriptome have allowed the systematic annotation of putative cis-regulatory elements associated with transcriptional programs that drive retinal neural differentiation, laying the groundwork to understand spatiotemporal retinal gene regulation at a mechanistic level. In this review, we outline recent advances in our understanding of the chromatin architecture in the mammalian retina during development and disease. We focus on the emerging roles of non-coding regulatory elements in controlling retinal cell-type specific transcriptional programs, and discuss potential implications in untangling the etiology of eye-related disorders.
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Affiliation(s)
- Marwa Daghsni
- Department of Ophthalmology, School of Medicine, University of Pittsburgh, Pittsburgh, PA, United States
| | - Issam Aldiri
- Department of Ophthalmology, School of Medicine, University of Pittsburgh, Pittsburgh, PA, United States.,Department of Developmental Biology, School of Medicine, University of Pittsburgh, Pittsburgh, PA, United States.,Louis J. Fox Center for Vision Restoration, University of Pittsburgh, Pittsburgh, PA, United States
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17
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Friedman RZ, Granas DM, Myers CA, Corbo JC, Cohen BA, White MA. Information content differentiates enhancers from silencers in mouse photoreceptors. eLife 2021; 10:67403. [PMID: 34486522 PMCID: PMC8492058 DOI: 10.7554/elife.67403] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Accepted: 09/03/2021] [Indexed: 12/12/2022] Open
Abstract
Enhancers and silencers often depend on the same transcription factors (TFs) and are conflated in genomic assays of TF binding or chromatin state. To identify sequence features that distinguish enhancers and silencers, we assayed massively parallel reporter libraries of genomic sequences targeted by the photoreceptor TF cone-rod homeobox (CRX) in mouse retinas. Both enhancers and silencers contain more TF motifs than inactive sequences, but relative to silencers, enhancers contain motifs from a more diverse collection of TFs. We developed a measure of information content that describes the number and diversity of motifs in a sequence and found that, while both enhancers and silencers depend on CRX motifs, enhancers have higher information content. The ability of information content to distinguish enhancers and silencers targeted by the same TF illustrates how motif context determines the activity of cis-regulatory sequences. Different cell types are established by activating and repressing the activity of specific sets of genes, a process controlled by proteins called transcription factors. Transcription factors work by recognizing and binding short stretches of DNA in parts of the genome called cis-regulatory sequences. A cis-regulatory sequence that increases the activity of a gene when bound by transcription factors is called an enhancer, while a sequence that causes a decrease in gene activity is called a silencer. To establish a cell type, a particular transcription factor will act on both enhancers and silencers that control the activity of different genes. For example, the transcription factor cone-rod homeobox (CRX) is critical for specifying different types of cells in the retina, and it acts on both enhancers and silencers. In rod photoreceptors, CRX activates rod genes by binding their enhancers, while repressing cone photoreceptor genes by binding their silencers. However, CRX always recognizes and binds to the same DNA sequence, known as its binding site, making it unclear why some cis-regulatory sequences bound to CRX act as silencers, while others act as enhancers. Friedman et al. sought to understand how enhancers and silencers, both bound by CRX, can have different effects on the genes they control. Since both enhancers and silencers contain CRX binding sites, the difference between the two must lie in the sequence of the DNA surrounding these binding sites. Using retinas that have been explanted from mice and kept alive in the laboratory, Friedman et al. tested the activity of thousands of CRX-binding sequences from the mouse genome. This showed that both enhancers and silencers have more copies of CRX-binding sites than sequences of the genome that are inactive. Additionally, the results revealed that enhancers have a diverse collection of binding sites for other transcription factors, while silencers do not. Friedman et al. developed a new metric they called information content, which captures the diverse combinations of different transcription binding sites that cis-regulatory sequences can have. Using this metric, Friedman et al. showed that it is possible to distinguish enhancers from silencers based on their information content. It is critical to understand how the DNA sequences of cis-regulatory regions determine their activity, because mutations in these regions of the genome can cause disease. However, since every person has thousands of benign mutations in cis-regulatory sequences, it is a challenge to identify specific disease-causing mutations, which are relatively rare. One long-term goal of models of enhancers and silencers, such as Friedman et al.’s information content model, is to understand how mutations can affect cis-regulatory sequences, and, in some cases, lead to disease.
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Affiliation(s)
- Ryan Z Friedman
- Edison Family Center for Genome Sciences and Systems Biology, Washington University School of Medicine, St. Louis, United States.,Department of Genetics, Washington University School of Medicine, St. Louis, United States
| | - David M Granas
- Edison Family Center for Genome Sciences and Systems Biology, Washington University School of Medicine, St. Louis, United States.,Department of Genetics, Washington University School of Medicine, St. Louis, United States
| | - Connie A Myers
- Department of Pathology and Immunology, Washington University School of Medicine, St Louis, United States
| | - Joseph C Corbo
- Department of Pathology and Immunology, Washington University School of Medicine, St Louis, United States
| | - Barak A Cohen
- Edison Family Center for Genome Sciences and Systems Biology, Washington University School of Medicine, St. Louis, United States.,Department of Genetics, Washington University School of Medicine, St. Louis, United States
| | - Michael A White
- Edison Family Center for Genome Sciences and Systems Biology, Washington University School of Medicine, St. Louis, United States.,Department of Genetics, Washington University School of Medicine, St. Louis, United States
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18
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Ogawa Y, Corbo JC. Partitioning of gene expression among zebrafish photoreceptor subtypes. Sci Rep 2021; 11:17340. [PMID: 34462505 PMCID: PMC8405809 DOI: 10.1038/s41598-021-96837-z] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Accepted: 08/17/2021] [Indexed: 02/07/2023] Open
Abstract
Vertebrate photoreceptors are categorized into two broad classes, rods and cones, responsible for dim- and bright-light vision, respectively. While many molecular features that distinguish rods and cones are known, gene expression differences among cone subtypes remain poorly understood. Teleost fishes are renowned for the diversity of their photoreceptor systems. Here, we used single-cell RNA-seq to profile adult photoreceptors in zebrafish, a teleost. We found that in addition to the four canonical zebrafish cone types, there exist subpopulations of green and red cones (previously shown to be located in the ventral retina) that express red-shifted opsin paralogs (opn1mw4 or opn1lw1) as well as a unique combination of cone phototransduction genes. Furthermore, the expression of many paralogous phototransduction genes is partitioned among cone subtypes, analogous to the partitioning of the phototransduction paralogs between rods and cones seen across vertebrates. The partitioned cone-gene pairs arose via the teleost-specific whole-genome duplication or later clade-specific gene duplications. We also discovered that cone subtypes express distinct transcriptional regulators, including many factors not previously implicated in photoreceptor development or differentiation. Overall, our work suggests that partitioning of paralogous gene expression via the action of differentially expressed transcriptional regulators enables diversification of cone subtypes in teleosts.
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Affiliation(s)
- Yohey Ogawa
- Department of Pathology and Immunology, Washington University School of Medicine, 660 South Euclid Avenue, St. Louis, MO, 63110-1093, USA
| | - Joseph C Corbo
- Department of Pathology and Immunology, Washington University School of Medicine, 660 South Euclid Avenue, St. Louis, MO, 63110-1093, USA.
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19
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Chaudhary R, Agarwal V, Kaushik AS, Rehman M. Involvement of myocyte enhancer factor 2c in the pathogenesis of autism spectrum disorder. Heliyon 2021; 7:e06854. [PMID: 33981903 PMCID: PMC8082549 DOI: 10.1016/j.heliyon.2021.e06854] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Revised: 12/09/2020] [Accepted: 04/15/2021] [Indexed: 12/29/2022] Open
Abstract
Myocyte enhancer factor 2 (MEF2), a family of transcription factor of MADS (minichromosome maintenance 1, agamous, deficiens and serum response factor)-box family needed in the growth and differentiation of a variety of human cells, such as neural, immune, endothelial, and muscles. As per existing literature, MEF2 transcription factors have also been associated with synaptic plasticity, the developmental mechanisms governing memory and learning, and several neurologic conditions, like autism spectrum disorders (ASDs). Recent genomic findings have ascertained a link between MEF2 defects, particularly in the MEF2C isoform and the ASD. In this review, we summarized a concise overview of the general regulation, structure and functional roles of the MEF2C transcription factor. We further outlined the potential role of MEF2C as a risk factor for various neurodevelopmental disorders, such as ASD, MEF2C Haploinsufficiency Syndrome and Fragile X syndrome.
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Affiliation(s)
- Rishabh Chaudhary
- Department of Pharmaceutical Sciences, School of Biosciences and Biotechnology, Babasaheb Bhimrao Ambedkar University, Lucknow, India
| | - Vipul Agarwal
- Department of Pharmaceutical Sciences, School of Biosciences and Biotechnology, Babasaheb Bhimrao Ambedkar University, Lucknow, India
| | - Arjun Singh Kaushik
- Department of Pharmaceutical Sciences, School of Biosciences and Biotechnology, Babasaheb Bhimrao Ambedkar University, Lucknow, India
| | - Mujeeba Rehman
- Department of Pharmaceutical Sciences, School of Biosciences and Biotechnology, Babasaheb Bhimrao Ambedkar University, Lucknow, India
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20
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Loss of Mef2D function enhances TLR induced IL-10 production in macrophages. Biosci Rep 2021; 40:225925. [PMID: 32725155 PMCID: PMC7442974 DOI: 10.1042/bsr20201859] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Revised: 07/27/2020] [Accepted: 07/29/2020] [Indexed: 12/24/2022] Open
Abstract
Mef2 transcription factors comprise a family of four different isoforms that regulate a number of processes including neuronal and muscle development. While roles for Mef2C and Mef2D have been described in B-cell development their role in immunity has not been extensively studied. In innate immune cells such as macrophages, TLRs drive the production of both pro- and anti-inflammatory cytokines. IL-10 is an important anti-inflammatory cytokine produced by macrophages and it establishes an autocrine feedback loop to inhibit pro-inflammatory cytokine production. We show here that macrophages from Mef2D knockout mice have elevated levels of IL-10 mRNA induction compared with wild-type cells following LPS stimulation. The secretion of IL-10 was also higher from Mef2D knockout macrophages and this correlated to a reduction in the secretion of TNF, IL-6 and IL-12p40. The use of an IL-10 neutralising antibody showed that this reduction in pro-inflammatory cytokine production in the Mef2D knockouts was IL-10 dependent. As the IL-10 promoter has previously been reported to contain a potential binding site for Mef2D, it is possible that the binding of other Mef2 isoforms in the absence of Mef2D may result in a higher activation of the IL-10 gene. Further studies with compound Mef2 isoforms would be required to address this. We also show that Mef2D is highly expressed in the thymus, but that loss of Mef2D does not affect thymic T-cell development or the production of IFNγ from CD8 T cells.
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21
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Yamamoto H, Kon T, Omori Y, Furukawa T. Functional and Evolutionary Diversification of Otx2 and Crx in Vertebrate Retinal Photoreceptor and Bipolar Cell Development. Cell Rep 2021; 30:658-671.e5. [PMID: 31968244 DOI: 10.1016/j.celrep.2019.12.072] [Citation(s) in RCA: 41] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2019] [Revised: 11/06/2019] [Accepted: 12/18/2019] [Indexed: 11/26/2022] Open
Abstract
Otx family homeoproteins Otx2 and Crx are expressed in photoreceptor precursor cells and bind to the common DNA-binding consensus sequence, but these two proteins have distinct functions in retinal development. To examine the functional substitutability of Otx2 and Crx, we generate knockin mouse lines in which Crx is replaced by Otx2 and vice versa. We find that Otx2 and Crx cannot be substituted in photoreceptor development. Subsequently, we investigate the function of Otx2 in photoreceptor and bipolar cell development. High Otx2 levels induce photoreceptor cell fate but not bipolar cell fate, whereas reduced Otx2 expression impairs bipolar cell maturation and survival. Furthermore, we identify Otx2 and Crx in the lamprey genome by using synteny analysis, suggesting that the last common ancestor of vertebrates possesses both Otx2 and Crx. We find that the retinal Otx2 expression pattern is different between lampreys and mice, suggesting that neofunctionalization of Otx2 occurred in the jawed vertebrate lineage.
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Affiliation(s)
- Haruka Yamamoto
- Laboratory for Molecular and Developmental Biology, Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Tetsuo Kon
- Laboratory for Molecular and Developmental Biology, Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Yoshihiro Omori
- Laboratory for Molecular and Developmental Biology, Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Takahisa Furukawa
- Laboratory for Molecular and Developmental Biology, Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita, Osaka 565-0871, Japan.
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22
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Di Giorgio E, Wang L, Xiong Y, Akimova T, Christensen LM, Han R, Samanta A, Trevisanut M, Bhatti TR, Beier UH, Hancock WW. MEF2D sustains activation of effector Foxp3+ Tregs during transplant survival and anticancer immunity. J Clin Invest 2021; 130:6242-6260. [PMID: 32790649 DOI: 10.1172/jci135486] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Accepted: 08/06/2020] [Indexed: 12/11/2022] Open
Abstract
The transcription factor MEF2D is important in the regulation of differentiation and adaptive responses in many cell types. We found that among T cells, MEF2D gained new functions in Foxp3+ T regulatory (Treg) cells due to its interactions with the transcription factor Foxp3 and its release from canonical partners, like histone/protein deacetylases. Though not necessary for the generation and maintenance of Tregs, MEF2D was required for the expression of IL-10, CTLA4, and Icos, and for the acquisition of an effector Treg phenotype. At these loci, MEF2D acted both synergistically and additively to Foxp3, and downstream of Blimp1. Mice with the conditional deletion in Tregs of the gene encoding MEF2D were unable to maintain long-term allograft survival despite costimulation blockade, had enhanced antitumor immunity in syngeneic models, but displayed only minor evidence of autoimmunity when maintained under normal conditions. The role played by MEF2D in sustaining effector Foxp3+ Treg functions without abrogating their basal actions suggests its suitability for drug discovery efforts in cancer therapy.
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Affiliation(s)
- Eros Di Giorgio
- Division of Transplant Immunology, Department of Pathology and Laboratory Medicine, Children's Hospital of Philadelphia and Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA.,Department of Medicine, Università degli Studi di Udine, Udine, Italy
| | - Liqing Wang
- Division of Transplant Immunology, Department of Pathology and Laboratory Medicine, Children's Hospital of Philadelphia and Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Yan Xiong
- Division of Transplant Immunology, Department of Pathology and Laboratory Medicine, Children's Hospital of Philadelphia and Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA.,Institute of Hepatobiliary Diseases of Wuhan University, Transplant Centre of Wuhan University, Zhongnan Hospital of Wuhan University, Wuhan University, Wuhan, China
| | - Tatiana Akimova
- Division of Transplant Immunology, Department of Pathology and Laboratory Medicine, Children's Hospital of Philadelphia and Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Lanette M Christensen
- Division of Transplant Immunology, Department of Pathology and Laboratory Medicine, Children's Hospital of Philadelphia and Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Rongxiang Han
- Division of Transplant Immunology, Department of Pathology and Laboratory Medicine, Children's Hospital of Philadelphia and Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Arabinda Samanta
- Division of Transplant Immunology, Department of Pathology and Laboratory Medicine, Children's Hospital of Philadelphia and Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Matteo Trevisanut
- Division of Transplant Immunology, Department of Pathology and Laboratory Medicine, Children's Hospital of Philadelphia and Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA.,Department of Medicine, Università degli Studi di Udine, Udine, Italy
| | - Tricia R Bhatti
- Division of Anatomical Pathology, Department of Pathology and Laboratory Medicine, Children's Hospital of Philadelphia and Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Ulf H Beier
- Division of Nephrology, Department of Pediatrics, Children's Hospital of Philadelphia and Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Wayne W Hancock
- Division of Transplant Immunology, Department of Pathology and Laboratory Medicine, Children's Hospital of Philadelphia and Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
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23
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Lu YW, Martino N, Gerlach BD, Lamar JM, Vincent PA, Adam AP, Schwarz JJ. MEF2 (Myocyte Enhancer Factor 2) Is Essential for Endothelial Homeostasis and the Atheroprotective Gene Expression Program. Arterioscler Thromb Vasc Biol 2021; 41:1105-1123. [PMID: 33406884 DOI: 10.1161/atvbaha.120.314978] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
OBJECTIVE Atherosclerosis predominantly forms in regions of oscillatory shear stress while regions of laminar shear stress are protected. This protection is partly through the endothelium in laminar flow regions expressing an anti-inflammatory and antithrombotic gene expression program. Several molecular pathways transmitting these distinct flow patterns to the endothelium have been defined. Our objective is to define the role of the MEF2 (myocyte enhancer factor 2) family of transcription factors in promoting an atheroprotective endothelium. Approach and Results: Here, we show through endothelial-specific deletion of the 3 MEF2 factors in the endothelium, Mef2a, -c, and -d, that MEF2 is a critical regulator of vascular homeostasis. MEF2 deficiency results in systemic inflammation, hemorrhage, thrombocytopenia, leukocytosis, and rapid lethality. Transcriptome analysis reveals that MEF2 is required for normal regulation of 3 pathways implicated in determining the flow responsiveness of the endothelium. Specifically, MEF2 is required for expression of Klf2 and Klf4, 2 partially redundant factors essential for promoting an anti-inflammatory and antithrombotic endothelium. This critical requirement results in phenotypic similarities between endothelial-specific deletions of Mef2a/c/d and Klf2/4. In addition, MEF2 regulates the expression of Notch family genes, Notch1, Dll1, and Jag1, which also promote an atheroprotective endothelium. In contrast to these atheroprotective pathways, MEF2 deficiency upregulates an atherosclerosis promoting pathway through increasing the amount of TAZ (transcriptional coactivator with PDZ-binding motif). CONCLUSIONS Our results implicate MEF2 as a critical upstream regulator of several transcription factors responsible for gene expression programs that affect development of atherosclerosis and promote an anti-inflammatory and antithrombotic endothelium. Graphic Abstract: A graphic abstract is available for this article.
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Affiliation(s)
- Yao Wei Lu
- Department of Molecular and Cellular Physiology (Y.W.L., N.M., B.D.G., J.M.L., P.A.V., A.P.A., J.J.S.), Albany Medical College, NY
| | - Nina Martino
- Department of Molecular and Cellular Physiology (Y.W.L., N.M., B.D.G., J.M.L., P.A.V., A.P.A., J.J.S.), Albany Medical College, NY
| | - Brennan D Gerlach
- Department of Molecular and Cellular Physiology (Y.W.L., N.M., B.D.G., J.M.L., P.A.V., A.P.A., J.J.S.), Albany Medical College, NY
| | - John M Lamar
- Department of Molecular and Cellular Physiology (Y.W.L., N.M., B.D.G., J.M.L., P.A.V., A.P.A., J.J.S.), Albany Medical College, NY
| | - Peter A Vincent
- Department of Molecular and Cellular Physiology (Y.W.L., N.M., B.D.G., J.M.L., P.A.V., A.P.A., J.J.S.), Albany Medical College, NY
| | - Alejandro P Adam
- Department of Molecular and Cellular Physiology (Y.W.L., N.M., B.D.G., J.M.L., P.A.V., A.P.A., J.J.S.), Albany Medical College, NY.,Department of Ophthalmology (A.P.A.), Albany Medical College, NY
| | - John J Schwarz
- Department of Molecular and Cellular Physiology (Y.W.L., N.M., B.D.G., J.M.L., P.A.V., A.P.A., J.J.S.), Albany Medical College, NY
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24
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Xia X, Yu CY, Bian M, Sun CB, Tanasa B, Chang KC, Bruffett DM, Thakur H, Shah SH, Knasel C, Cameron EG, Kapiloff MS, Goldberg JL. MEF2 transcription factors differentially contribute to retinal ganglion cell loss after optic nerve injury. PLoS One 2020; 15:e0242884. [PMID: 33315889 PMCID: PMC7735573 DOI: 10.1371/journal.pone.0242884] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2020] [Accepted: 11/10/2020] [Indexed: 02/07/2023] Open
Abstract
Loss of retinal ganglion cells (RGCs) in optic neuropathies results in permanent partial or complete blindness. Myocyte enhancer factor 2 (MEF2) transcription factors have been shown to play a pivotal role in neuronal systems, and in particular MEF2A knockout was shown to enhance RGC survival after optic nerve crush injury. Here we expanded these prior data to study bi-allelic, tri-allelic and heterozygous allele deletion. We observed that deletion of all MEF2A, MEF2C, and MEF2D alleles had no effect on RGC survival during development. Our extended experiments suggest that the majority of the neuroprotective effect was conferred by complete deletion of MEF2A but that MEF2D knockout, although not sufficient to increase RGC survival on its own, increased the positive effect of MEF2A knockout. Conversely, MEF2A over-expression in wildtype mice worsened RGC survival after optic nerve crush. Interestingly, MEF2 transcription factors are regulated by post-translational modification, including by calcineurin-catalyzed dephosphorylation of MEF2A Ser-408 known to increase MEF2A-dependent transactivation in neurons. However, neither phospho-mimetic nor phospho-ablative mutation of MEF2A Ser-408 affected the ability of MEF2A to promote RGC death in vivo after optic nerve injury. Together these findings demonstrate that MEF2 gene expression opposes RGC survival following axon injury in a complex hierarchy, and further support the hypothesis that loss of or interference with MEF2A expression might be beneficial for RGC neuroprotection in diseases such as glaucoma and other optic neuropathies.
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Affiliation(s)
- Xin Xia
- Mary M. and Sash A. Spencer Center for Vision Research, Department of Ophthalmology, Byers Eye Institute, Stanford University School of Medicine, Palo Alto, CA, United States of America
| | - Caroline Y. Yu
- Mary M. and Sash A. Spencer Center for Vision Research, Department of Ophthalmology, Byers Eye Institute, Stanford University School of Medicine, Palo Alto, CA, United States of America
| | - Minjuan Bian
- Mary M. and Sash A. Spencer Center for Vision Research, Department of Ophthalmology, Byers Eye Institute, Stanford University School of Medicine, Palo Alto, CA, United States of America
| | - Catalina B. Sun
- Mary M. and Sash A. Spencer Center for Vision Research, Department of Ophthalmology, Byers Eye Institute, Stanford University School of Medicine, Palo Alto, CA, United States of America
| | - Bogdan Tanasa
- Mary M. and Sash A. Spencer Center for Vision Research, Department of Ophthalmology, Byers Eye Institute, Stanford University School of Medicine, Palo Alto, CA, United States of America
| | - Kun-Che Chang
- Mary M. and Sash A. Spencer Center for Vision Research, Department of Ophthalmology, Byers Eye Institute, Stanford University School of Medicine, Palo Alto, CA, United States of America
| | - Dawn M. Bruffett
- Mary M. and Sash A. Spencer Center for Vision Research, Department of Ophthalmology, Byers Eye Institute, Stanford University School of Medicine, Palo Alto, CA, United States of America
| | - Hrishikesh Thakur
- Mary M. and Sash A. Spencer Center for Vision Research, Department of Ophthalmology, Byers Eye Institute, Stanford University School of Medicine, Palo Alto, CA, United States of America
| | - Sahil H. Shah
- Mary M. and Sash A. Spencer Center for Vision Research, Department of Ophthalmology, Byers Eye Institute, Stanford University School of Medicine, Palo Alto, CA, United States of America
| | - Cara Knasel
- Mary M. and Sash A. Spencer Center for Vision Research, Department of Ophthalmology, Byers Eye Institute, Stanford University School of Medicine, Palo Alto, CA, United States of America
| | - Evan G. Cameron
- Mary M. and Sash A. Spencer Center for Vision Research, Department of Ophthalmology, Byers Eye Institute, Stanford University School of Medicine, Palo Alto, CA, United States of America
| | - Michael S. Kapiloff
- Mary M. and Sash A. Spencer Center for Vision Research, Department of Ophthalmology, Byers Eye Institute, Stanford University School of Medicine, Palo Alto, CA, United States of America
- Department of Medicine and Stanford Cardiovascular Institute, Stanford University School of Medicine, Palo Alto, CA, United States of America
- * E-mail: (MSK); (JLG)
| | - Jeffrey L. Goldberg
- Mary M. and Sash A. Spencer Center for Vision Research, Department of Ophthalmology, Byers Eye Institute, Stanford University School of Medicine, Palo Alto, CA, United States of America
- * E-mail: (MSK); (JLG)
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25
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Majidi SP, Reddy NC, Moore MJ, Chen H, Yamada T, Andzelm MM, Cherry TJ, Hu LS, Greenberg ME, Bonni A. Chromatin Environment and Cellular Context Specify Compensatory Activity of Paralogous MEF2 Transcription Factors. Cell Rep 2020; 29:2001-2015.e5. [PMID: 31722213 PMCID: PMC6874310 DOI: 10.1016/j.celrep.2019.10.033] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Revised: 09/04/2019] [Accepted: 10/09/2019] [Indexed: 12/16/2022] Open
Abstract
Compensation among paralogous transcription factors (TFs) confers genetic robustness of cellular processes, but how TFs dynamically respond to paralog depletion on a genome-wide scale in vivo remains incompletely understood. Using single and double conditional knockout of myocyte enhancer factor 2 (MEF2) family TFs in granule neurons of the mouse cerebellum, we find that MEF2A and MEF2D play functionally redundant roles in cerebellar-dependent motor learning. Although both TFs are highly expressed in granule neurons, transcriptomic analyses show MEF2D is the predominant genomic regulator of gene expression in vivo. Strikingly, genome-wide occupancy analyses reveal upon depletion of MEF2D, MEF2A occupancy robustly increases at a subset of sites normally bound to MEF2D. Importantly, sites experiencing compensatory MEF2A occupancy are concentrated within open chromatin and undergo functional compensation for genomic activation and gene expression. Finally, motor activity induces a switch from non-compensatory to compensatory MEF2-dependent gene regulation. These studies uncover genome-wide functional interdependency between paralogous TFs in the brain. Majidi et al. study how transcription factors respond to paralog depletion by conditionally depleting MEF2A and MEF2D in mouse cerebellum. Depletion of MEF2D induces functionally compensatory genomic occupancy by MEF2A. Compensation occurs within accessible chromatin in a context-dependent manner. This study explores the interdependency between paralogous transcription factors.
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Affiliation(s)
- Shahriyar P Majidi
- Department of Neuroscience, Washington University School of Medicine, St. Louis, MO 63110, USA; MD-PhD Program, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Naveen C Reddy
- Department of Neuroscience, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Michael J Moore
- Department of Neuroscience, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Hao Chen
- Department of Neuroscience, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Tomoko Yamada
- Department of Neuroscience, Washington University School of Medicine, St. Louis, MO 63110, USA; Faculty of Medicine, University of Tsukuba, Tsukuba, Ibaraki 305-8575, Japan
| | - Milena M Andzelm
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Timothy J Cherry
- Department of Pediatrics, University of Washington School of Medicine, Seattle, WA 98101, USA; Center for Developmental Biology and Regenerative Medicine, Seattle Children's Research Institute, 1900 9(th) Ave., Seattle, WA 98101, USA; Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Linda S Hu
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | | | - Azad Bonni
- Department of Neuroscience, Washington University School of Medicine, St. Louis, MO 63110, USA.
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26
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Blixt N, Norton A, Zhang A, Aparicio C, Prasad H, Gopalakrishnan R, Jensen ED, Mansky KC. Loss of myocyte enhancer factor 2 expression in osteoclasts leads to opposing skeletal phenotypes. Bone 2020; 138:115466. [PMID: 32512162 PMCID: PMC7443313 DOI: 10.1016/j.bone.2020.115466] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/24/2019] [Revised: 05/04/2020] [Accepted: 06/01/2020] [Indexed: 01/08/2023]
Abstract
Osteoclasts are multinuclear cells that resorb bone. Osteoclast differentiation is regulated by multiple transcription factors which may be acting in a single or multiple factor complex to regulate gene expression. Myocyte enhancer factor 2 (MEF2) is a family of transcription factors whose role during osteoclast differentiation has not been well characterized. Because MEF2A and MEF2D are the family members most highly expressed during osteoclast differentiation, we created conditional knockout mice models for MEF2A and/or MEF2D. In vitro cultures of A- and D-KO osteoclasts were smaller and less numerous than wild type cultures, while AD-KO osteoclasts were almost completely devoid of TRAP positive mononuclear cells. Female A-KO mice are osteopetrotic while male A- and D-KO mice of either sex had no significant in vivo skeletal phenotype, suggesting a sex-specific regulation of osteoclasts by MEF2A. Lastly, in vivo male AD-KO mice are osteopenic, indicating while MEF2 is required for M-CSF and RANKL-stimulated osteoclastogenesis in vitro, osteoclasts can form in the absence of MEF2 in vivo via a RANKL-alternative pathway.
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Affiliation(s)
- Nicholas Blixt
- Departmment of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, Minnesota USA 55455
| | - Andrew Norton
- Department of Developmental and Surgical Sciences, University of Minnesota, Minneapolis, Minnesota USA 55455
| | - Anqi Zhang
- Department of Restorative Sciences, MDRCBB-Minnesota Dental Research Center for Biomaterials and Biomechanics University of Minnesota, Minneapolis, Minnesota USA 55455
| | - Conrado Aparicio
- Department of Restorative Sciences, MDRCBB-Minnesota Dental Research Center for Biomaterials and Biomechanics University of Minnesota, Minneapolis, Minnesota USA 55455
| | - Hari Prasad
- Department of Diagnostic and Biological Sciences, University of Minnesota, Minneapolis, Minnesota USA 55455
| | - Rajaram Gopalakrishnan
- Department of Diagnostic and Biological Sciences, University of Minnesota, Minneapolis, Minnesota USA 55455
| | - Eric D. Jensen
- Department of Diagnostic and Biological Sciences, University of Minnesota, Minneapolis, Minnesota USA 55455
- Co-corresponding authors : To whom correspondence should be addressed:, Kim Mansky, PhD, Tel.: (612) 626-5582,
| | - Kim C. Mansky
- Department of Developmental and Surgical Sciences, University of Minnesota, Minneapolis, Minnesota USA 55455
- Co-corresponding authors : To whom correspondence should be addressed:, Kim Mansky, PhD, Tel.: (612) 626-5582,
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27
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Cherry TJ, Yang MG, Harmin DA, Tao P, Timms AE, Bauwens M, Allikmets R, Jones EM, Chen R, De Baere E, Greenberg ME. Mapping the cis-regulatory architecture of the human retina reveals noncoding genetic variation in disease. Proc Natl Acad Sci U S A 2020; 117:9001-9012. [PMID: 32265282 PMCID: PMC7183164 DOI: 10.1073/pnas.1922501117] [Citation(s) in RCA: 57] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
The interplay of transcription factors and cis-regulatory elements (CREs) orchestrates the dynamic and diverse genetic programs that assemble the human central nervous system (CNS) during development and maintain its function throughout life. Genetic variation within CREs plays a central role in phenotypic variation in complex traits including the risk of developing disease. We took advantage of the retina, a well-characterized region of the CNS known to be affected by pathogenic variants in CREs, to establish a roadmap for characterizing regulatory variation in the human CNS. This comprehensive analysis of tissue-specific regulatory elements, transcription factor binding, and gene expression programs in three regions of the human visual system (retina, macula, and retinal pigment epithelium/choroid) reveals features of regulatory element evolution that shape tissue-specific gene expression programs and defines regulatory elements with the potential to contribute to Mendelian and complex disorders of human vision.
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Affiliation(s)
- Timothy J Cherry
- Department of Pediatrics, University of Washington School of Medicine, Seattle, WA 98101;
- Department of Ophthalmology, University of Washington School of Medicine, Seattle, WA 98101
- Department of Biological Structure, University of Washington School of Medicine, Seattle, WA 98101
- Center for Developmental Biology and Regenerative Medicine, Seattle Children's Research Institute, Seattle, WA 98101
| | - Marty G Yang
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115
- Program in Neuroscience, Harvard Medical School, Boston, MA 02115
| | - David A Harmin
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115
| | - Peter Tao
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115
| | - Andrew E Timms
- Center for Developmental Biology and Regenerative Medicine, Seattle Children's Research Institute, Seattle, WA 98101
| | - Miriam Bauwens
- Center for Medical Genetics, Ghent University and Ghent University Hospital, 9000 Ghent, Belgium
| | - Rando Allikmets
- Department of Ophthalmology, Columbia University, New York, NY 10032
- Department of Pathology and Cell Biology, Columbia University, New York, NY 10032
| | - Evan M Jones
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX 77030-3411
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030-3411
| | - Rui Chen
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX 77030-3411
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030-3411
| | - Elfride De Baere
- Center for Medical Genetics, Ghent University and Ghent University Hospital, 9000 Ghent, Belgium
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28
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Phuycharoen M, Zarrineh P, Bridoux L, Amin S, Losa M, Chen K, Bobola N, Rattray M. Uncovering tissue-specific binding features from differential deep learning. Nucleic Acids Res 2020; 48:e27. [PMID: 31974574 PMCID: PMC7049686 DOI: 10.1093/nar/gkaa009] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2019] [Revised: 11/04/2019] [Accepted: 01/07/2020] [Indexed: 01/24/2023] Open
Abstract
Transcription factors (TFs) can bind DNA in a cooperative manner, enabling a mutual increase in occupancy. Through this type of interaction, alternative binding sites can be preferentially bound in different tissues to regulate tissue-specific expression programmes. Recently, deep learning models have become state-of-the-art in various pattern analysis tasks, including applications in the field of genomics. We therefore investigate the application of convolutional neural network (CNN) models to the discovery of sequence features determining cooperative and differential TF binding across tissues. We analyse ChIP-seq data from MEIS, TFs which are broadly expressed across mouse branchial arches, and HOXA2, which is expressed in the second and more posterior branchial arches. By developing models predictive of MEIS differential binding in all three tissues, we are able to accurately predict HOXA2 co-binding sites. We evaluate transfer-like and multitask approaches to regularizing the high-dimensional classification task with a larger regression dataset, allowing for the creation of deeper and more accurate models. We test the performance of perturbation and gradient-based attribution methods in identifying the HOXA2 sites from differential MEIS data. Our results show that deep regularized models significantly outperform shallow CNNs as well as k-mer methods in the discovery of tissue-specific sites bound in vivo.
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Affiliation(s)
- Mike Phuycharoen
- Department of Computer Science, The University of Manchester, Oxford Rd, Manchester M13 9PL, UK
| | - Peyman Zarrineh
- School of Health Sciences, The University of Manchester, Oxford Rd, Manchester M13 9PL, UK
| | - Laure Bridoux
- School of Medical Sciences, The University of Manchester, Oxford Rd, Manchester M13 9PL, UK
| | - Shilu Amin
- School of Medical Sciences, The University of Manchester, Oxford Rd, Manchester M13 9PL, UK
| | - Marta Losa
- Department of Orofacial Sciences and Department of Anatomy, University of California San Francisco, 513 Parnassus Avenue, HSW 740, San Francisco, CA 94143, USA
| | - Ke Chen
- Department of Computer Science, The University of Manchester, Oxford Rd, Manchester M13 9PL, UK
| | - Nicoletta Bobola
- School of Medical Sciences, The University of Manchester, Oxford Rd, Manchester M13 9PL, UK
| | - Magnus Rattray
- School of Health Sciences, The University of Manchester, Oxford Rd, Manchester M13 9PL, UK
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29
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Perez-Cervantes C, Smith LA, Nadadur RD, Hughes AEO, Wang S, Corbo JC, Cepko C, Lonfat N, Moskowitz IP. Enhancer transcription identifies cis-regulatory elements for photoreceptor cell types. Development 2020; 147:dev184432. [PMID: 31915147 PMCID: PMC7033740 DOI: 10.1242/dev.184432] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2019] [Accepted: 12/13/2019] [Indexed: 12/30/2022]
Abstract
Identification of cell type-specific cis-regulatory elements (CREs) is crucial for understanding development and disease, although identification of functional regulatory elements remains challenging. We hypothesized that context-specific CREs could be identified by context-specific non-coding RNA (ncRNA) profiling, based on the observation that active CREs produce ncRNAs. We applied ncRNA profiling to identify rod and cone photoreceptor CREs from wild-type and mutant mouse retinas, defined by presence or absence, respectively, of the rod-specific transcription factor (TF) NrlNrl-dependent ncRNA expression strongly correlated with epigenetic profiles of rod and cone photoreceptors, identified thousands of candidate rod- and cone-specific CREs, and identified motifs for rod- and cone-specific TFs. Colocalization of NRL and the retinal TF CRX correlated with rod-specific ncRNA expression, whereas CRX alone favored cone-specific ncRNA expression, providing quantitative evidence that heterotypic TF interactions distinguish cell type-specific CRE activity. We validated the activity of novel Nrl-dependent ncRNA-defined CREs in developing cones. This work supports differential ncRNA profiling as a platform for the identification of cell type-specific CREs and the discovery of molecular mechanisms underlying TF-dependent CRE activity.
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Affiliation(s)
- Carlos Perez-Cervantes
- Departments of Pediatrics, Pathology, and Human Genetics, University of Chicago, Chicago, IL 60637, USA
| | - Linsin A Smith
- Departments of Pediatrics, Pathology, and Human Genetics, University of Chicago, Chicago, IL 60637, USA
| | - Rangarajan D Nadadur
- Departments of Pediatrics, Pathology, and Human Genetics, University of Chicago, Chicago, IL 60637, USA
| | - Andrew E O Hughes
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Sui Wang
- Departments of Genetics and Ophthalmology, Howard Hughes Medical Institute, Blavatnik Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Joseph C Corbo
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Constance Cepko
- Departments of Genetics and Ophthalmology, Howard Hughes Medical Institute, Blavatnik Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Nicolas Lonfat
- Departments of Genetics and Ophthalmology, Howard Hughes Medical Institute, Blavatnik Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Ivan P Moskowitz
- Departments of Pediatrics, Pathology, and Human Genetics, University of Chicago, Chicago, IL 60637, USA
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Shimizu J, Suzuki T, Hirotsu C, Ueno H, Takada E, Arimitsu N, Ueda Y, Wakisaka S, Suzuki N. Interaction between SDF1 and CXCR4 Promotes Photoreceptor Differentiation via Upregulation of NFκB Pathway Signaling Activity in Pax6 Gene-Transfected Photoreceptor Precursors. Ophthalmic Res 2020; 63:392-403. [PMID: 31935734 DOI: 10.1159/000503929] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Accepted: 10/06/2019] [Indexed: 02/02/2023]
Abstract
BACKGROUND CCL2 (also known as monocyte chemoattractant protein 1) and CX3CR1 (also known as Fractalkine receptor)-deficient mice have damaged photoreceptors. OBJECTIVES We examined the interaction of SDF1 and CXCR4 on the differentiation of retinal progenitors into rhodopsin-positive photoreceptors. METHODS Cloned retinal progenitors were obtained by Pax6 gene transfection of mouse iPS cells followed by serial dilution. Clones were selected by expression of nestin, Musashi1, Six3, and Chx10 mRNA. Cell surface protein expression was analyzed by flow cytometry. The levels of mRNA and intracellular protein were examined by real-time PCR and immunochemistry, respectively. Transient transfection experiments of retinal progenitors were conducted using a human rhodopsin promoter luciferase plasmid. RESULTS We selected 10 clones that expressed Six3, Chx10, Crx, Rx1, Nrl, CD73, and rhodopsin mRNA, which, except for rhodopsin, are photoreceptor precursor markers. Clones expressed both CD73 and CXCR4 on the cell surface and differentiated into rhodopsin-positive photoreceptors, which was reinforced by the addition of exogenous SDF1. A CXCR4 inhibitor AMD3100 blocked SDF1-mediated differentiation of progenitors into photoreceptors. SDF1 enhanced human rhodopsin promoter transcription activity, possibly via the NFκB pathway. Addition of SDF1 to the cell culture induced nuclear translocation of NFκB on retinal progenitor cell clones. Neonatal and newborn mouse retinas expressed SDF1 and CXCR4. Cells in the outer nuclear layer where photoreceptors are located expressed CXCR4 at P14 and P56. Cells in the inner nuclear layer expressed SDF1. CONCLUSIONS These findings suggest that retinal progenitor cell differentiation was at least partly regulated by SDF1 and CXCR4 via upregulation of NFκB activity.
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Affiliation(s)
- Jun Shimizu
- Departments of Immunology and Medicine, St. Marianna University Graduate School of Medicine, Kawasaki, Japan
| | - Tomoko Suzuki
- Departments of Immunology and Medicine, St. Marianna University Graduate School of Medicine, Kawasaki, Japan
| | - Chieko Hirotsu
- Departments of Immunology and Medicine, St. Marianna University Graduate School of Medicine, Kawasaki, Japan
| | - Hiroki Ueno
- Departments of Immunology and Medicine, St. Marianna University Graduate School of Medicine, Kawasaki, Japan
| | - Erika Takada
- Departments of Immunology and Medicine, St. Marianna University Graduate School of Medicine, Kawasaki, Japan
| | - Nagisa Arimitsu
- Departments of Immunology and Medicine, St. Marianna University Graduate School of Medicine, Kawasaki, Japan
| | - Yuji Ueda
- Departments of Immunology and Medicine, St. Marianna University Graduate School of Medicine, Kawasaki, Japan
| | - Sueshige Wakisaka
- Departments of Immunology and Medicine, St. Marianna University Graduate School of Medicine, Kawasaki, Japan
| | - Noboru Suzuki
- Departments of Immunology and Medicine, St. Marianna University Graduate School of Medicine, Kawasaki, Japan, .,Department of Regenerative Medicine, St. Marianna University Graduate School of Medicine, Kawasaki, Japan,
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31
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Feng W, Li Y, Dao P, Aburas J, Islam P, Elbaz B, Kolarzyk A, Brown AE, Kratsios P. A terminal selector prevents a Hox transcriptional switch to safeguard motor neuron identity throughout life. eLife 2020; 9:50065. [PMID: 31902393 PMCID: PMC6944445 DOI: 10.7554/elife.50065] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2019] [Accepted: 12/08/2019] [Indexed: 01/01/2023] Open
Abstract
To become and remain functional, individual neuron types must select during development and maintain throughout life their distinct terminal identity features, such as expression of specific neurotransmitter receptors, ion channels and neuropeptides. Here, we report a molecular mechanism that enables cholinergic motor neurons (MNs) in the C. elegans ventral nerve cord to select and maintain their unique terminal identity. This mechanism relies on the dual function of the conserved terminal selector UNC-3 (Collier/Ebf). UNC-3 synergizes with LIN-39 (Scr/Dfd/Hox4-5) to directly co-activate multiple terminal identity traits specific to cholinergic MNs, but also antagonizes LIN-39’s ability to activate terminal features of alternative neuronal identities. Loss of unc-3 causes a switch in the transcriptional targets of LIN-39, thereby alternative, not cholinergic MN-specific, terminal features become activated and locomotion defects occur. The strategy of a terminal selector preventing a transcriptional switch may constitute a general principle for safeguarding neuronal identity throughout life.
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Affiliation(s)
- Weidong Feng
- Department of Neurobiology, University of Chicago, Chicago, United States.,Committee on Development, Regeneration and Stem Cell Biology, University of Chicago, Chicago, United States
| | - Yinan Li
- Department of Neurobiology, University of Chicago, Chicago, United States.,Committee on Neurobiology, University of Chicago, Chicago, United States
| | - Pauline Dao
- Department of Neurobiology, University of Chicago, Chicago, United States
| | - Jihad Aburas
- Department of Neurobiology, University of Chicago, Chicago, United States
| | - Priota Islam
- MRC London Institute of Medical Sciences, London, United Kingdom.,Institute of Clinical Sciences, Imperial College London, London, United Kingdom
| | - Benayahu Elbaz
- Department of Neurology, Center for Peripheral Neuropathy, University of Chicago, Chicago, United States
| | - Anna Kolarzyk
- Department of Neurology, Center for Peripheral Neuropathy, University of Chicago, Chicago, United States
| | - André Ex Brown
- MRC London Institute of Medical Sciences, London, United Kingdom.,Institute of Clinical Sciences, Imperial College London, London, United Kingdom
| | - Paschalis Kratsios
- Department of Neurobiology, University of Chicago, Chicago, United States.,Committee on Development, Regeneration and Stem Cell Biology, University of Chicago, Chicago, United States.,Committee on Neurobiology, University of Chicago, Chicago, United States.,The Grossman Institute for Neuroscience, Quantitative Biology, and Human Behavior, University of Chicago, Chicago, United States
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32
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Neuronal Myocyte-Specific Enhancer Factor 2D (MEF2D) Is Required for Normal Circadian and Sleep Behavior in Mice. J Neurosci 2019; 39:7958-7967. [PMID: 31420455 DOI: 10.1523/jneurosci.0411-19.2019] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2019] [Revised: 07/08/2019] [Accepted: 08/10/2019] [Indexed: 11/21/2022] Open
Abstract
The transcription factor, myocyte enhancer factor-2 (MEF2), is required for normal circadian behavior in Drosophila; however, its role in the mammalian circadian system has not been established. Of the four mammalian Mef2 genes, Mef2d is highly expressed in the suprachiasmatic nucleus (SCN) of the hypothalamus, a region critical for coordinating peripheral circadian clocks. Using both conventional and brain-specific Mef2d KO (Mef2d -/-) mouse lines, we demonstrate that MEF2D is essential for maintaining the length of the circadian free-running period of locomotor activity and normal sleep patterns in male mice. Crossing Mef2d -/- with Per2::luc reporter mice, we show that these behavioral changes are achieved without altering the endogenous period of the master circadian oscillator in the SCN. Together, our data suggest that alterations in behavior in Mef2d -/- mice may be the result of an effect on SCN output, rather than an effect on timekeeping within the SCN itself. These findings add to the growing body of evidence that MEF2 proteins play important roles in the brain.SIGNIFICANCE STATEMENT These studies are the first to show a role for MEF2 proteins in the brain outside of the hippocampus, and our findings suggest that these proteins may play diverse roles in the CNS. It is important to continue to build on our understanding of the roles of proteins acting in the SCN because SCN dysfunction underlies jet lag in humans and influences the response to shift work schedules, which are now known as risk factors for the development of cancer. Our work on MEF2D could be the basis for opening new lines of research in the development and regulation of circadian rhythms.
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33
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Royall AH, Frankenberg S, Pask AJ, Holland PWH. Of eyes and embryos: subfunctionalization of the CRX homeobox gene in mammalian evolution. Proc Biol Sci 2019; 286:20190830. [PMID: 31337308 PMCID: PMC6661347 DOI: 10.1098/rspb.2019.0830] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2019] [Accepted: 06/28/2019] [Indexed: 11/12/2022] Open
Abstract
ETCHbox genes are fast-evolving homeobox genes present only in eutherian (placental) mammals which originated by duplication and divergence from a conserved homeobox gene, Cone-rod homeobox (CRX). While expression and function of CRX are restricted to the retina in eutherian mammals, ETCHbox gene expression is specific to preimplantation embryos. This dramatic difference could reflect the acquisition of new functions by duplicated genes or subfunctionalization of pleiotropic roles between CRX and ETCHbox genes. To resolve between these hypotheses, we compared expression, sequence and inferred function between CRX of metatherian (marsupial) mammals and ETCHbox genes of eutherians. We find the metatherian CRX homeobox gene is expressed in early embryos and in eyes, unlike eutherian CRX, and distinct amino acid substitutions were fixed in the metatherian and eutherian evolutionary lineages consistent with altered transcription factor specificity. We find that metatherian CRX is capable of regulating embryonically expressed genes in cultured cells in a comparable way to eutherian ETCHbox. The data are consistent with CRX having a dual role in eyes and embryos of metatherians, providing an early embryonic function comparable to that of eutherian ETCHbox genes; we propose that subfunctionalization of pleiotropic functions occurred after gene duplication along the placental lineage, followed by functional elaboration.
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Affiliation(s)
- Amy H. Royall
- Department of Zoology, University of Oxford, 11a Mansfield Road, Oxford OX1 3SZ, UK
| | - Stephen Frankenberg
- School of BioSciences, University of Melbourne, Melbourne, 3010 Victoria, Australia
| | - Andrew J. Pask
- School of BioSciences, University of Melbourne, Melbourne, 3010 Victoria, Australia
| | - Peter W. H. Holland
- Department of Zoology, University of Oxford, 11a Mansfield Road, Oxford OX1 3SZ, UK
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34
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Stone NR, Gifford CA, Thomas R, Pratt KJB, Samse-Knapp K, Mohamed TMA, Radzinsky EM, Schricker A, Ye L, Yu P, van Bemmel JG, Ivey KN, Pollard KS, Srivastava D. Context-Specific Transcription Factor Functions Regulate Epigenomic and Transcriptional Dynamics during Cardiac Reprogramming. Cell Stem Cell 2019; 25:87-102.e9. [PMID: 31271750 PMCID: PMC6632093 DOI: 10.1016/j.stem.2019.06.012] [Citation(s) in RCA: 79] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Revised: 06/13/2019] [Accepted: 06/17/2019] [Indexed: 12/12/2022]
Abstract
Ectopic expression of combinations of transcription factors (TFs) can drive direct lineage conversion, thereby reprogramming a somatic cell's identity. To determine the molecular mechanisms by which Gata4, Mef2c, and Tbx5 (GMT) induce conversion from a cardiac fibroblast toward an induced cardiomyocyte, we performed comprehensive transcriptomic, DNA-occupancy, and epigenomic interrogation throughout the reprogramming process. Integration of these datasets identified new TFs involved in cardiac reprogramming and revealed context-specific roles for GMT, including the ability of Mef2c and Tbx5 to independently promote chromatin remodeling at previously inaccessible sites. We also find evidence for cooperative facilitation and refinement of each TF's binding profile in a combinatorial setting. A reporter assay employing newly defined regulatory elements confirmed that binding of a single TF can be sufficient for gene activation, suggesting that co-binding events do not necessarily reflect synergy. These results shed light on fundamental mechanisms by which combinations of TFs direct lineage conversion.
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Affiliation(s)
- Nicole R Stone
- Gladstone Institutes, San Francisco, CA 94158, USA; Departments of Pediatrics and Biochemistry & Biophysics, University of California, San Francisco, CA 94143, USA
| | - Casey A Gifford
- Gladstone Institutes, San Francisco, CA 94158, USA; Roddenberry Center for Stem Cell Biology and Medicine at Gladstone, San Francisco, CA 94158, USA
| | | | | | | | - Tamer M A Mohamed
- Gladstone Institutes, San Francisco, CA 94158, USA; Roddenberry Center for Stem Cell Biology and Medicine at Gladstone, San Francisco, CA 94158, USA
| | | | | | - Lin Ye
- Gladstone Institutes, San Francisco, CA 94158, USA
| | - Pengzhi Yu
- Gladstone Institutes, San Francisco, CA 94158, USA; Roddenberry Center for Stem Cell Biology and Medicine at Gladstone, San Francisco, CA 94158, USA
| | | | - Kathryn N Ivey
- Gladstone Institutes, San Francisco, CA 94158, USA; Departments of Pediatrics and Biochemistry & Biophysics, University of California, San Francisco, CA 94143, USA; Roddenberry Center for Stem Cell Biology and Medicine at Gladstone, San Francisco, CA 94158, USA
| | - Katherine S Pollard
- Gladstone Institutes, San Francisco, CA 94158, USA; Department of Epidemiology & Biostatistics, University of California, San Francisco, CA 94143, USA; Chan-Zuckerberg Biohub, San Francisco, CA 94158, USA.
| | - Deepak Srivastava
- Gladstone Institutes, San Francisco, CA 94158, USA; Departments of Pediatrics and Biochemistry & Biophysics, University of California, San Francisco, CA 94143, USA; Roddenberry Center for Stem Cell Biology and Medicine at Gladstone, San Francisco, CA 94158, USA.
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35
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MEF-2 isoforms' (A-D) roles in development and tumorigenesis. Oncotarget 2019; 10:2755-2787. [PMID: 31105874 PMCID: PMC6505634 DOI: 10.18632/oncotarget.26763] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2018] [Accepted: 02/01/2019] [Indexed: 12/29/2022] Open
Abstract
Myocyte enhancer factor (MEF)-2 plays a critical role in proliferation, differentiation, and development of various cell types in a tissue specific manner. Four isoforms of MEF-2 (A-D) differentially participate in controlling the cell fate during the developmental phases of cardiac, muscle, vascular, immune and skeletal systems. Through their associations with various cellular factors MEF-2 isoforms can trigger alterations in complex protein networks and modulate various stages of cellular differentiation, proliferation, survival and apoptosis. The role of the MEF-2 family of transcription factors in the development has been investigated in various cell types, and the evolving alterations in this family of transcription factors have resulted in a diverse and wide spectrum of disease phenotypes, ranging from cancer to infection. This review provides a comprehensive account on MEF-2 isoforms (A-D) from their respective localization, signaling, role in development and tumorigenesis as well as their association with histone deacetylases (HDACs), which can be exploited for therapeutic intervention.
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36
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Andzelm MM, Vanness D, Greenberg ME, Linden DJ. A Late Phase of Long-Term Synaptic Depression in Cerebellar Purkinje Cells Requires Activation of MEF2. Cell Rep 2019; 26:1089-1097.e3. [PMID: 30699340 PMCID: PMC6433166 DOI: 10.1016/j.celrep.2019.01.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2016] [Revised: 09/06/2018] [Accepted: 12/28/2018] [Indexed: 12/18/2022] Open
Abstract
The MEF2 family of transcription factors restricts excitatory synapse number in an activity-dependent fashion during development, yet MEF2 has not been implicated in long-term synaptic depression (LTD), which is thought to initiate synapse elimination. Mutations in MEF2 pathways are implicated in autism spectrum disorders, which include cerebellar dysfunction. Here, we test the hypothesis that cerebellar LTD requires postsynaptic activation of MEF2. Knockdown of MEF2D produces suppression of the transcription-dependent late phase of LTD in cultured Purkinje cells. The late phase of LTD is also completely blocked in Purkinje cells derived from MEF2A+MEF2D null mice and rescued with plasmids that drive expression of MEF2D but not phosphatase-resistant mutant MEF2D S444D. Wild-type Purkinje cells transfected with a constitutively active form of MEF2 show no alterations of synaptic strength. Thus, postsynaptic activation of MEF2 by S444 dephosphorylation is necessary, but not sufficient, for the late phase of cerebellar LTD.
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Affiliation(s)
- Milena M Andzelm
- Department of Neurobiology, Harvard Medical School, 220 Longwood Avenue, Boston, MA 02115, USA
| | - Devorah Vanness
- The Solomon H. Snyder Department of Neuroscience, The Johns Hopkins University School of Medicine, 725 N. Wolfe Street, Baltimore, MD 21205, USA
| | - Michael E Greenberg
- Department of Neurobiology, Harvard Medical School, 220 Longwood Avenue, Boston, MA 02115, USA
| | - David J Linden
- The Solomon H. Snyder Department of Neuroscience, The Johns Hopkins University School of Medicine, 725 N. Wolfe Street, Baltimore, MD 21205, USA.
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37
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Gray JM, Spiegel I. Cell-type-specific programs for activity-regulated gene expression. Curr Opin Neurobiol 2018; 56:33-39. [PMID: 30529822 DOI: 10.1016/j.conb.2018.11.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2018] [Revised: 11/04/2018] [Accepted: 11/05/2018] [Indexed: 12/20/2022]
Abstract
Experience leaves a lasting mark on neural circuit function in part through activity-regulated gene (ARG) expression. New genome wide approaches have revealed that ARG programs are highly cell-type-specific, raising the possibility that they mediate different forms of experience-dependent plasticity in different cell types. The cell-type specificity of these gene programs is achieved by a combination of cell-intrinsic mechanisms that determine the transcriptional response of each neuronal subtype to a given stimulus and by cell-extrinsic mechanisms that influence the nature of the stimulus a cell receives. A better understanding of these mechanisms could usher in an era of molecular systems neuroscience in which genetic perturbations of cell-type-specific plasticities are assessed using electrophysiology and in vivo imaging to reveal the neural basis of adaptive behaviors.
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Affiliation(s)
- Jesse M Gray
- Department of Genetics, Harvard Medical School, Boston, United States.
| | - Ivo Spiegel
- Department of Neurobiology, Weizmann Institute of Science, 76100 Rehovot, Israel.
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38
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Crittenden JR, Skoulakis EMC, Goldstein ES, Davis RL. Drosophila mef2 is essential for normal mushroom body and wing development. Biol Open 2018; 7:bio.035618. [PMID: 30115617 PMCID: PMC6176937 DOI: 10.1242/bio.035618] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
MEF2 (myocyte enhancer factor 2) transcription factors are found in the brain and muscle of insects and vertebrates and are essential for the differentiation of multiple cell types. We show that in the fruit fly Drosophila, MEF2 is essential for the formation of mushroom bodies in the embryonic brain and for the normal development of wings in the adult. In embryos mutant for mef2, there is a striking reduction in the number of mushroom body neurons and their axon bundles are not detectable. The onset of MEF2 expression in neurons of the mushroom bodies coincides with their formation in the embryo and, in larvae, expression is restricted to post-mitotic neurons. In flies with a mef2 point mutation that disrupts nuclear localization, we find that MEF2 is restricted to a subset of Kenyon cells that project to the α/β, and γ axonal lobes of the mushroom bodies, but not to those forming the α’/β’ lobes. Summary:Drosophila mef2 expression is restricted to subsets of mushroom body neurons, from the time of their differentiation to adulthood, and is essential for mushroom body formation.
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Affiliation(s)
- Jill R Crittenden
- McGovern Institute for Brain Research, Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Efthimios M C Skoulakis
- Division of Neuroscience, Biomedical Sciences Research Centre 'Alexander Fleming', Vari, 16672, Greece
| | - Elliott S Goldstein
- School of Life Science, Cellular, Molecular and Bioscience Program, Arizona State University, Tempe, AZ, 85287, USA
| | - Ronald L Davis
- Department of Neuroscience, The Scripps Research Institute Florida, Jupiter, FL 33458, USA
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39
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Abstract
Eukaryotic cells depend on precise genome organization within the nucleus to maintain an appropriate gene-expression profile. Critical to this process is the packaging of functional domains of open and closed chromatin to specific regions of the nucleus, but how this is regulated remains unclear. In this study, we show that the zinc finger protein Casz1 regulates higher-order nuclear organization of rod photoreceptors in the mouse retina by repressing nuclear lamina function, which leads to central localization of heterochromatin. Loss of Casz1 in rods leads to an abnormal transcriptional profile followed by degeneration. These results identify Casz1 as a regulator of higher-order genome organization. Genome organization plays a fundamental role in the gene-expression programs of numerous cell types, but determinants of higher-order genome organization are poorly understood. In the developing mouse retina, rod photoreceptors represent a good model to study this question. They undergo a process called “chromatin inversion” during differentiation, in which, as opposed to classic nuclear organization, heterochromatin becomes localized to the center of the nucleus and euchromatin is restricted to the periphery. While previous studies showed that the lamin B receptor participates in this process, the molecular mechanisms regulating lamina function during differentiation remain elusive. Here, using conditional genetics, we show that the zinc finger transcription factor Casz1 is required to establish and maintain the inverted chromatin organization of rod photoreceptors and to safeguard their gene-expression profile and long-term survival. At the mechanistic level, we show that Casz1 interacts with the polycomb repressor complex in a splice variant-specific manner and that both are required to suppress the expression of the nuclear envelope intermediate filament lamin A/C in rods. Lamin A is in turn sufficient to regulate heterochromatin organization and nuclear position. Furthermore, we show that Casz1 is sufficient to expand and centralize the heterochromatin of fibroblasts, suggesting a general role for Casz1 in nuclear organization. Together, these data support a model in which Casz1 cooperates with polycomb to control rod genome organization, in part by silencing lamin A/C.
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40
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Ruzycki PA, Zhang X, Chen S. CRX directs photoreceptor differentiation by accelerating chromatin remodeling at specific target sites. Epigenetics Chromatin 2018; 11:42. [PMID: 30068366 PMCID: PMC6069558 DOI: 10.1186/s13072-018-0212-2] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2018] [Accepted: 07/22/2018] [Indexed: 12/24/2022] Open
Abstract
Background Recent technological advances have delivered the genome-wide targets of many important transcription factors (TFs). However, increasing evidence suggests that not all target sites mediate regulatory function, raising the questions of how to determine which sites are active, what are the epigenetic consequences of TF binding at these sites, and how the specificity is coded. To address these questions, we focused on CRX, a disease-associated homeodomain TF required for photoreceptor gene expression and development. Since CRX binds more than 6000 sites across the genome in the retina, we profiled chromatin landscape changes at each binding site during normal development and in the absence of CRX and interpreted the results by thorough investigation of other epigenomic datasets and sequence features. Results CRX is required for chromatin remodeling at only a subset of its binding sites, which undergo retina or neuronal specific activation during photoreceptor differentiation. Genes near these “CRX Dependent” sites code for proteins important for photoreceptor physiology and function, and their transcription is significantly reduced in Crx deficient retinas. In addition, the nucleotide and motif content distinguish these CRX Dependent sites from other CRX-bound sites. Conclusions Together, our results suggest that CRX acts only at select, uniquely-coded binding sites to accelerate chromatin remodeling during photoreceptor differentiation. This study emphasizes the importance of connecting TF binding with its functional consequences and provides a framework for making such a connection using comparative analyses of available genomic datasets. Finally, this study prioritizes sets of non-coding DNA sites for future functional interrogation and identification of mutations associated with retinal disease. Electronic supplementary material The online version of this article (10.1186/s13072-018-0212-2) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Philip A Ruzycki
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, MO, USA.,Molecular Genetics and Genomics Graduate Program, Division of Biology and Biomedical Sciences, Washington University School of Medicine, St. Louis, MO, USA
| | - Xiaodong Zhang
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, MO, USA
| | - Shiming Chen
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, MO, USA. .,Department of Developmental Biology, Washington University School of Medicine, St. Louis, MO, USA. .,Molecular Genetics and Genomics Graduate Program, Division of Biology and Biomedical Sciences, Washington University School of Medicine, St. Louis, MO, USA.
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41
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Corso-Díaz X, Jaeger C, Chaitankar V, Swaroop A. Epigenetic control of gene regulation during development and disease: A view from the retina. Prog Retin Eye Res 2018; 65:1-27. [PMID: 29544768 PMCID: PMC6054546 DOI: 10.1016/j.preteyeres.2018.03.002] [Citation(s) in RCA: 82] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2017] [Revised: 02/01/2018] [Accepted: 03/08/2018] [Indexed: 12/20/2022]
Abstract
Complex biological processes, such as organogenesis and homeostasis, are stringently regulated by genetic programs that are fine-tuned by epigenetic factors to establish cell fates and/or to respond to the microenvironment. Gene regulatory networks that guide cell differentiation and function are modulated and stabilized by modifications to DNA, RNA and proteins. In this review, we focus on two key epigenetic changes - DNA methylation and histone modifications - and discuss their contribution to retinal development, aging and disease, especially in the context of age-related macular degeneration (AMD) and diabetic retinopathy. We highlight less-studied roles of DNA methylation and provide the RNA expression profiles of epigenetic enzymes in human and mouse retina in comparison to other tissues. We also review computational tools and emergent technologies to profile, analyze and integrate epigenetic information. We suggest implementation of editing tools and single-cell technologies to trace and perturb the epigenome for delineating its role in transcriptional regulation. Finally, we present our thoughts on exciting avenues for exploring epigenome in retinal metabolism, disease modeling, and regeneration.
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Affiliation(s)
- Ximena Corso-Díaz
- Neurobiology-Neurodegeneration & Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Catherine Jaeger
- Neurobiology-Neurodegeneration & Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Vijender Chaitankar
- Neurobiology-Neurodegeneration & Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Anand Swaroop
- Neurobiology-Neurodegeneration & Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, MD, 20892, USA.
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42
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Di Giorgio E, Hancock WW, Brancolini C. MEF2 and the tumorigenic process, hic sunt leones. Biochim Biophys Acta Rev Cancer 2018; 1870:261-273. [PMID: 29879430 DOI: 10.1016/j.bbcan.2018.05.007] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2018] [Revised: 05/25/2018] [Accepted: 05/26/2018] [Indexed: 12/14/2022]
Abstract
While MEF2 transcription factors are well known to cooperate in orchestrating cell fate and adaptive responses during development and adult life, additional studies over the last decade have identified a wide spectrum of genetic alterations of MEF2 in different cancers. The consequences of these alterations, including triggering and maintaining the tumorigenic process, are not entirely clear. A deeper knowledge of the molecular pathways that regulate MEF2 expression and function, as well as the nature and consequences of MEF2 mutations are necessary to fully understand the many roles of MEF2 in malignant cells. This review discusses the current knowledge of MEF2 transcription factors in cancer.
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Affiliation(s)
- Eros Di Giorgio
- Department of Medicine, Università degli Studi di Udine, P.le Kolbe 4, 33100 Udine, Italy
| | - Wayne W Hancock
- Division of Transplant Immunology, Department of Pathology and Laboratory Medicine, Biesecker Center for Pediatric Liver Diseases, Children's Hospital of Philadelphia and Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Claudio Brancolini
- Department of Medicine, Università degli Studi di Udine, P.le Kolbe 4, 33100 Udine, Italy.
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Budak G, Dash S, Srivastava R, Lachke SA, Janga SC. Express: A database of transcriptome profiles encompassing known and novel transcripts across multiple development stages in eye tissues. Exp Eye Res 2018; 168:57-68. [PMID: 29337142 DOI: 10.1016/j.exer.2018.01.009] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2016] [Revised: 01/08/2018] [Accepted: 01/11/2018] [Indexed: 01/23/2023]
Abstract
Advances in sequencing have facilitated nucleotide-resolution genome-wide transcriptomic profiles across multiple mouse eye tissues. However, these RNA sequencing (RNA-seq) based eye developmental transcriptomes are not organized for easy public access, making any further analysis challenging. Here, we present a new database "Express" (http://www.iupui.edu/∼sysbio/express/) that unifies various mouse lens and retina RNA-seq data and provides user-friendly visualization of the transcriptome to facilitate gene discovery in the eye. We obtained RNA-seq data encompassing 7 developmental stages of lens in addition to that on isolated lens epithelial and fibers, as well as on 11 developmental stages of retina/isolated retinal rod photoreceptor cells from publicly available wild-type mouse datasets. These datasets were pre-processed, aligned, quantified and normalized for expression levels of known and novel transcripts using a unified expression quantification framework. Express provides heatmap and browser view allowing easy navigation of the genomic organization of transcripts or gene loci. Further, it allows users to search candidate genes and export both the visualizations and the embedded data to facilitate downstream analysis. We identified total of >81,000 transcripts in the lens and >178,000 transcripts in the retina across all the included developmental stages. This analysis revealed that a significant number of the retina-expressed transcripts are novel. Expression of several transcripts in the lens and retina across multiple developmental stages was independently validated by RT-qPCR for established genes such as Pax6 and Lhx2 as well as for new candidates such as Elavl4, Rbm5, Pabpc1, Tia1 and Tubb2b. Thus, Express serves as an effective portal for analyzing pruned RNA-seq expression datasets presently collected for the lens and retina. It will allow a wild-type context for the detailed analysis of targeted gene-knockout mouse ocular defect models and facilitate the prioritization of candidate genes from Exome-seq data of eye disease patients.
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Affiliation(s)
- Gungor Budak
- Department of BioHealth Informatics, School of Informatics and Computing, Indiana University Purdue University, 719 Indiana Ave Ste 319, Walker Plaza Building, Indianapolis, IN 46202, United States
| | - Soma Dash
- Department of Biological Sciences, University of Delaware, Newark, DE 19716, United States
| | - Rajneesh Srivastava
- Department of BioHealth Informatics, School of Informatics and Computing, Indiana University Purdue University, 719 Indiana Ave Ste 319, Walker Plaza Building, Indianapolis, IN 46202, United States
| | - Salil A Lachke
- Department of Biological Sciences, University of Delaware, Newark, DE 19716, United States; Center for Bioinformatics and Computational Biology, University of Delaware, Newark, DE 19716, United States
| | - Sarath Chandra Janga
- Department of BioHealth Informatics, School of Informatics and Computing, Indiana University Purdue University, 719 Indiana Ave Ste 319, Walker Plaza Building, Indianapolis, IN 46202, United States; Center for Computational Biology and Bioinformatics, Indiana University School of Medicine, 5021 Health Information and Translational Sciences (HITS), 410 West 10th Street, Indianapolis, IN, 46202, United States; Department of Medical and Molecular Genetics, Indiana University School of Medicine, Medical Research and Library Building, 975 West Walnut Street, Indianapolis, IN, 46202, United States.
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Yesudhas D, Batool M, Anwar MA, Panneerselvam S, Choi S. Proteins Recognizing DNA: Structural Uniqueness and Versatility of DNA-Binding Domains in Stem Cell Transcription Factors. Genes (Basel) 2017; 8:genes8080192. [PMID: 28763006 PMCID: PMC5575656 DOI: 10.3390/genes8080192] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2017] [Revised: 07/22/2017] [Accepted: 07/25/2017] [Indexed: 12/17/2022] Open
Abstract
Proteins in the form of transcription factors (TFs) bind to specific DNA sites that regulate cell growth, differentiation, and cell development. The interactions between proteins and DNA are important toward maintaining and expressing genetic information. Without knowing TFs structures and DNA-binding properties, it is difficult to completely understand the mechanisms by which genetic information is transferred between DNA and proteins. The increasing availability of structural data on protein-DNA complexes and recognition mechanisms provides deeper insights into the nature of protein-DNA interactions and therefore, allows their manipulation. TFs utilize different mechanisms to recognize their cognate DNA (direct and indirect readouts). In this review, we focus on these recognition mechanisms as well as on the analysis of the DNA-binding domains of stem cell TFs, discussing the relative role of various amino acids toward facilitating such interactions. Unveiling such mechanisms will improve our understanding of the molecular pathways through which TFs are involved in repressing and activating gene expression.
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Affiliation(s)
- Dhanusha Yesudhas
- Department of Molecular Science and Technology, Ajou University, Suwon 443-749, Korea.
| | - Maria Batool
- Department of Molecular Science and Technology, Ajou University, Suwon 443-749, Korea.
| | - Muhammad Ayaz Anwar
- Department of Molecular Science and Technology, Ajou University, Suwon 443-749, Korea.
| | - Suresh Panneerselvam
- Department of Molecular Science and Technology, Ajou University, Suwon 443-749, Korea.
| | - Sangdun Choi
- Department of Molecular Science and Technology, Ajou University, Suwon 443-749, Korea.
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Nagar S, Trudler D, McKercher SR, Piña-Crespo J, Nakanishi N, Okamoto SI, Lipton SA. Molecular Pathway to Protection From Age-Dependent Photoreceptor Degeneration in Mef2 Deficiency. Invest Ophthalmol Vis Sci 2017; 58:3741-3749. [PMID: 28738418 PMCID: PMC5525556 DOI: 10.1167/iovs.17-21767] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Purpose Photoreceptor degeneration in the retina is a major cause of blindness in humans. Elucidating mechanisms of degenerative and neuroprotective pathways in photoreceptors should afford identification and development of therapeutic strategies. Methods We used mouse genetic models and improved methods for retinal explant cultures. Retinas were enucleated from Mef2d+/+ and Mef2d−/− mice, stained for MEF2 proteins and outer nuclear layer thickness, and assayed for apoptotic cells. Chromatin immunoprecipitation (ChIP) assays revealed MEF2 binding, and RT-qPCR showed levels of transcription factors. We used AAV2 and electroporation to express genes in retinal explants and electroretinograms to assess photoreceptor functionality. Results We identify a prosurvival MEF2D-PGC1α pathway that plays a neuroprotective role in photoreceptors. We demonstrate that Mef2d−/− mouse retinas manifest decreased expression of PGC1α and increased photoreceptor cell loss, resulting in the absence of light responses. Molecular repletion of PGC1α protects Mef2d−/− photoreceptors and preserves light responsivity. Conclusions These results suggest that the MEF2-PGC1α cascade may represent a new therapeutic target for drugs designed to protect photoreceptors from developmental- and age-dependent loss.
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Affiliation(s)
- Saumya Nagar
- Neuroscience and Aging Research Center and Graduate School of Biomedical Sciences, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California, United States
| | - Dorit Trudler
- Neurodegenerative Disease Center, Scintillon Institute, San Diego, California, United States
| | - Scott R McKercher
- Neurodegenerative Disease Center, Scintillon Institute, San Diego, California, United States
| | - Juan Piña-Crespo
- Neuroscience and Aging Research Center and Graduate School of Biomedical Sciences, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California, United States
| | - Nobuki Nakanishi
- Neurodegenerative Disease Center, Scintillon Institute, San Diego, California, United States
| | - Shu-Ichi Okamoto
- Neurodegenerative Disease Center, Scintillon Institute, San Diego, California, United States
| | - Stuart A Lipton
- Neuroscience and Aging Research Center and Graduate School of Biomedical Sciences, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California, United States 2Neurodegenerative Disease Center, Scintillon Institute, San Diego, California, United States 3Department of Neurosciences, University of California, San Diego, School of Medicine, La Jolla, California, United States 4Department of Molecular Medicine, The Scripps Research Institute, La Jolla, California, United States
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Van Schil K, Naessens S, Van de Sompele S, Carron M, Aslanidis A, Van Cauwenbergh C, Kathrin Mayer A, Van Heetvelde M, Bauwens M, Verdin H, Coppieters F, Greenberg ME, Yang MG, Karlstetter M, Langmann T, De Preter K, Kohl S, Cherry TJ, Leroy BP, De Baere E. Mapping the genomic landscape of inherited retinal disease genes prioritizes genes prone to coding and noncoding copy-number variations. Genet Med 2017; 20:202-213. [PMID: 28749477 PMCID: PMC5787040 DOI: 10.1038/gim.2017.97] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2017] [Accepted: 05/19/2017] [Indexed: 01/08/2023] Open
Abstract
PurposePart of the hidden genetic variation in heterogeneous genetic conditions such as inherited retinal diseases (IRDs) can be explained by copy-number variations (CNVs). Here, we explored the genomic landscape of IRD genes listed in RetNet to identify and prioritize those genes susceptible to CNV formation.MethodsRetNet genes underwent an assessment of genomic features and of CNV occurrence in the Database of Genomic Variants and literature. CNVs identified in an IRD cohort were characterized using targeted locus amplification (TLA) on extracted genomic DNA.ResultsExhaustive literature mining revealed 1,345 reported CNVs in 81 different IRD genes. Correlation analysis between rankings of genomic features and CNV occurrence demonstrated the strongest correlation between gene size and CNV occurrence of IRD genes. Moreover, we identified and delineated 30 new CNVs in IRD cases, 13 of which are novel and three of which affect noncoding, putative cis-regulatory regions. Finally, the breakpoints of six complex CNVs were determined using TLA in a hypothesis-neutral manner.ConclusionWe propose a ranking of CNV-prone IRD genes and demonstrate the efficacy of TLA for the characterization of CNVs on extracted DNA. Finally, this IRD-oriented CNV study can serve as a paradigm for other genetically heterogeneous Mendelian diseases with hidden genetic variation.
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Affiliation(s)
- Kristof Van Schil
- Center for Medical Genetics, Ghent University and Ghent University Hospital, Ghent, Belgium
| | - Sarah Naessens
- Center for Medical Genetics, Ghent University and Ghent University Hospital, Ghent, Belgium
| | - Stijn Van de Sompele
- Center for Medical Genetics, Ghent University and Ghent University Hospital, Ghent, Belgium
| | - Marjolein Carron
- Center for Medical Genetics, Ghent University and Ghent University Hospital, Ghent, Belgium
| | - Alexander Aslanidis
- Laboratory for Experimental Immunology of the Eye, Department of Ophthalmology, University of Cologne, Cologne, Germany
| | | | - Anja Kathrin Mayer
- Molecular Genetics Laboratory, Institute for Ophthalmic Research, Centre for Ophthalmology, University of Tuebingen, Tuebingen, Germany
| | - Mattias Van Heetvelde
- Center for Medical Genetics, Ghent University and Ghent University Hospital, Ghent, Belgium
| | - Miriam Bauwens
- Center for Medical Genetics, Ghent University and Ghent University Hospital, Ghent, Belgium
| | - Hannah Verdin
- Center for Medical Genetics, Ghent University and Ghent University Hospital, Ghent, Belgium
| | - Frauke Coppieters
- Center for Medical Genetics, Ghent University and Ghent University Hospital, Ghent, Belgium
| | - Michael E Greenberg
- Department of Neurobiology, Harvard Medical School, Boston, Massachusetts, USA
| | - Marty G Yang
- Department of Neurobiology, Harvard Medical School, Boston, Massachusetts, USA
| | - Marcus Karlstetter
- Laboratory for Experimental Immunology of the Eye, Department of Ophthalmology, University of Cologne, Cologne, Germany
| | - Thomas Langmann
- Laboratory for Experimental Immunology of the Eye, Department of Ophthalmology, University of Cologne, Cologne, Germany
| | - Katleen De Preter
- Center for Medical Genetics, Ghent University and Ghent University Hospital, Ghent, Belgium
| | - Susanne Kohl
- Molecular Genetics Laboratory, Institute for Ophthalmic Research, Centre for Ophthalmology, University of Tuebingen, Tuebingen, Germany
| | - Timothy J Cherry
- Department of Pediatrics, University of Washington School of Medicine, Seattle, Washington, USA.,Center for Developmental Biology and Regenerative Medicine, Seattle Children's Research Institute, Seattle, Washington, USA
| | - Bart P Leroy
- Center for Medical Genetics, Ghent University and Ghent University Hospital, Ghent, Belgium.,Department of Ophthalmology, Ghent University and Ghent University Hospital, Ghent, Belgium.,Division of Ophthalmology, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
| | | | - Elfride De Baere
- Center for Medical Genetics, Ghent University and Ghent University Hospital, Ghent, Belgium
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MEF2D haploinsufficiency downregulates the NRF2 pathway and renders photoreceptors susceptible to light-induced oxidative stress. Proc Natl Acad Sci U S A 2017; 114:E4048-E4056. [PMID: 28461502 DOI: 10.1073/pnas.1613067114] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Gaining mechanistic insight into interaction between causative factors of complex multifactorial diseases involving photoreceptor damage might aid in devising effective therapies. Oxidative stress is one of the potential unifying mechanisms for interplay between genetic and environmental factors that contribute to photoreceptor pathology. Interestingly, the transcription factor myocyte enhancer factor 2d (MEF2D) is known to be important in photoreceptor survival, as knockout of this transcription factor results in loss of photoreceptors in mice. Here, using a mild light-induced retinal degeneration model, we show that the diminished MEF2D transcriptional activity in Mef2d+/- retina is further reduced under photostimulation-induced oxidative stress. Reactive oxygen species cause an aberrant redox modification on MEF2D, consequently inhibiting transcription of its downstream target, nuclear factor (erythroid-derived 2)-like 2 (NRF2). NRF2 is a master regulator of phase II antiinflammatory and antioxidant gene expression. In the Mef2d heterozygous mouse retina, NRF2 is not up-regulated to a normal degree in the face of light-induced oxidative stress, contributing to accelerated photoreceptor cell death. Furthermore, to combat this injury, we found that activation of the endogenous NRF2 pathway using proelectrophilic drugs rescues photoreceptors from photo-induced oxidative stress and may therefore represent a viable treatment for oxidative stress-induced photoreceptor degeneration, which is thought to contribute to some forms of retinitis pigmentosa and age-related macular degeneration.
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Di Giorgio E, Franforte E, Cefalù S, Rossi S, Dei Tos AP, Brenca M, Polano M, Maestro R, Paluvai H, Picco R, Brancolini C. The co-existence of transcriptional activator and transcriptional repressor MEF2 complexes influences tumor aggressiveness. PLoS Genet 2017; 13:e1006752. [PMID: 28419090 PMCID: PMC5413110 DOI: 10.1371/journal.pgen.1006752] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2017] [Revised: 05/02/2017] [Accepted: 04/10/2017] [Indexed: 12/18/2022] Open
Abstract
The contribution of MEF2 TFs to the tumorigenic process is still mysterious. Here we clarify that MEF2 can support both pro-oncogenic or tumor suppressive activities depending on the interaction with co-activators or co-repressors partners. Through these interactions MEF2 supervise histone modifications associated with gene activation/repression, such as H3K4 methylation and H3K27 acetylation. Critical switches for the generation of a MEF2 repressive environment are class IIa HDACs. In leiomyosarcomas (LMS), this two-faced trait of MEF2 is relevant for tumor aggressiveness. Class IIa HDACs are overexpressed in 22% of LMS, where high levels of MEF2, HDAC4 and HDAC9 inversely correlate with overall survival. The knock out of HDAC9 suppresses the transformed phenotype of LMS cells, by restoring the transcriptional proficiency of some MEF2-target loci. HDAC9 coordinates also the demethylation of H3K4me3 at the promoters of MEF2-target genes. Moreover, we show that class IIa HDACs do not bind all the regulative elements bound by MEF2. Hence, in a cell MEF2-target genes actively transcribed and strongly repressed can coexist. However, these repressed MEF2-targets are poised in terms of chromatin signature. Overall our results candidate class IIa HDACs and HDAC9 in particular, as druggable targets for a therapeutic intervention in LMS. The tumorigenic process is characterized by profound alterations of the transcriptional landscape, aimed to sustain uncontrolled cell growth, resistance to apoptosis and metastasis. The contribution of MEF2, a pleiotropic family of transcription factors, to these changes is controversial, since both pro-oncogenic and tumor-suppressive activities have been reported. To clarify this paradox, we studied the role of MEF2 in an aggressive type of soft-tissue sarcomas, the leiomyosarcomas (LMS). We found that in LMS cells MEF2 become oncogenes when in complex with class IIa HDACs. We have identified different sub-classes of MEF2-target genes and observed that HDAC9 converts MEF2 into transcriptional repressors on some, but not all, MEF2-regulated loci. This conversion correlates with the acquisition by MEF2 of oncogenic properties. We have also elucidated some epigenetic re-arrangements supervised by MEF2. In summary, our studies suggest that the paradoxical actions of MEF2 in cancer can be explained by their dual role as activators/repressors of transcription and open new possibilities for therapeutic interventions.
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Affiliation(s)
- Eros Di Giorgio
- Department of Medical and Biological Sciences, Università degli Studi di Udine. P.le Kolbe 4-Udine Italy
| | - Elisa Franforte
- Department of Medical and Biological Sciences, Università degli Studi di Udine. P.le Kolbe 4-Udine Italy
| | - Sebastiano Cefalù
- Department of Medical and Biological Sciences, Università degli Studi di Udine. P.le Kolbe 4-Udine Italy
| | - Sabrina Rossi
- Department of Anatomical Pathology, Treviso General Hospital, Treviso, Italy
| | - Angelo Paolo Dei Tos
- Department of Anatomical Pathology, Treviso General Hospital, Treviso, Italy.,Department of Medicine, University of Padua, Padua, Italy
| | - Monica Brenca
- Experimental Oncology 1, CRO National Cancer Institute, Aviano, Italy
| | - Maurizio Polano
- Experimental Oncology 1, CRO National Cancer Institute, Aviano, Italy
| | - Roberta Maestro
- Experimental Oncology 1, CRO National Cancer Institute, Aviano, Italy
| | - Harikrishnareddy Paluvai
- Department of Medical and Biological Sciences, Università degli Studi di Udine. P.le Kolbe 4-Udine Italy
| | - Raffaella Picco
- Department of Medical and Biological Sciences, Università degli Studi di Udine. P.le Kolbe 4-Udine Italy
| | - Claudio Brancolini
- Department of Medical and Biological Sciences, Università degli Studi di Udine. P.le Kolbe 4-Udine Italy
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Cell Type-Specific Epigenomic Analysis Reveals a Uniquely Closed Chromatin Architecture in Mouse Rod Photoreceptors. Sci Rep 2017; 7:43184. [PMID: 28256534 PMCID: PMC5335693 DOI: 10.1038/srep43184] [Citation(s) in RCA: 56] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2016] [Accepted: 01/19/2017] [Indexed: 12/24/2022] Open
Abstract
Rod photoreceptors are specialized neurons that mediate vision in dim light and are the predominant photoreceptor type in nocturnal mammals. The rods of nocturnal mammals are unique among vertebrate cell types in having an ‘inverted’ nuclear architecture, with a dense mass of heterochromatin in the center of the nucleus rather than dispersed clumps at the periphery. To test if this unique nuclear architecture is correlated with a unique epigenomic landscape, we performed ATAC-seq on mouse rods and their most closely related cell type, cone photoreceptors. We find that thousands of loci are selectively closed in rods relative to cones as well as >60 additional cell types. Furthermore, we find that the open chromatin profile of photoreceptors lacking the rod master regulator Nrl is nearly indistinguishable from that of native cones, indicating that Nrl is required for selective chromatin closure in rods. Finally, we identified distinct enrichments of transcription factor binding sites in rods and cones, revealing key differences in the cis-regulatory grammar of these cell types. Taken together, these data provide insight into the development and maintenance of photoreceptor identity, and highlight rods as an attractive system for studying the relationship between nuclear organization and local changes in gene regulation.
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Wolf A, Aslanidis A, Langmann T. Retinal expression and localization of Mef2c support its important role in photoreceptor gene expression. Biochem Biophys Res Commun 2016; 483:346-351. [PMID: 28017720 DOI: 10.1016/j.bbrc.2016.12.141] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2016] [Accepted: 12/21/2016] [Indexed: 11/17/2022]
Abstract
Photoreceptor-specific gene expression is controlled by a hierarchical network of transcription factors, including the master regulators cone-rod homeobox (Crx) and neural retina leucine zipper (Nrl). Myocyte-enhancer factor 2c (Mef2c) is an ubiquitously expressed transcription factor with important functions in the cardiovascular system. Here, we performed a detailed analysis of Mef2c expression, localization and function in the retina to further elucidate its potential role for photoreceptor gene regulation. We showed that murine retinal Mef2c mRNA expression was high at birth and peaked at late postnatal developmental stages. Using immunohistochemistry and Western blot, Mef2c protein was detected in the outer nuclear layer of adult mouse and human retinas and localized to the nucleus of 661W photoreceptor-like cells. Mef2c knock-down in 661W cells reduced the expression of arrestin 3 (Arr3) and medium-wave-sensitive cone opsin (Opn1mw) but increased transcript levels of mitogen-activated protein kinase 15 (Mapk15) and phosphodiesterase 6h (Pde6h). In conclusion, Mef2c is highly expressed in the retina where it modulates photoreceptor-specific gene expression.
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Affiliation(s)
- Anne Wolf
- Laboratory for Experimental Immunology of the Eye, Department of Ophthalmology, University of Cologne, Cologne, Germany
| | - Alexander Aslanidis
- Laboratory for Experimental Immunology of the Eye, Department of Ophthalmology, University of Cologne, Cologne, Germany
| | - Thomas Langmann
- Laboratory for Experimental Immunology of the Eye, Department of Ophthalmology, University of Cologne, Cologne, Germany.
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