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Zolboot N, Xiao Y, Du JX, Ghanem MM, Choi SY, Junn MJ, Zampa F, Huang Z, MacRae IJ, Lippi G. MicroRNA mechanisms instructing Purkinje cell specification. Neuron 2025; 113:1629-1646.e15. [PMID: 40179877 DOI: 10.1016/j.neuron.2025.03.009] [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: 09/25/2024] [Revised: 01/22/2025] [Accepted: 03/04/2025] [Indexed: 04/05/2025]
Abstract
MicroRNAs (miRNAs) are critical for brain development; however, if, when, and how miRNAs drive neuronal subtype specification remains poorly understood. To address this, we engineered technologies with vastly improved spatiotemporal resolution that allow the dissection of cell-type-specific miRNA-target networks. Fast and reversible miRNA loss of function showed that miRNAs are necessary for Purkinje cell (PC) differentiation, which previously appeared to be miRNA independent, and identified distinct critical miRNA windows for dendritogenesis and climbing fiber synaptogenesis, structural features defining PC identity. Using new mouse models that enable miRNA-target network mapping in rare cell types, we uncovered PC-specific post-transcriptional programs. Manipulation of these programs revealed that the PC-enriched miR-206 and targets Shank3, Prag1, En2, and Vash1, which are uniquely repressed in PCs, are critical regulators of PC-specific dendritogenesis and synaptogenesis, with miR-206 knockdown and target overexpression partially phenocopying miRNA loss of function. Our results suggest that gene expression regulation by miRNAs, beyond transcription, is critical for neuronal subtype specification.
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Affiliation(s)
- Norjin Zolboot
- Department of Neuroscience, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Yao Xiao
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Jessica X Du
- Department of Neuroscience, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Marwan M Ghanem
- Department of Neuroscience, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Su Yeun Choi
- Department of Neuroscience, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Miranda J Junn
- Department of Neuroscience, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Federico Zampa
- Department of Neuroscience, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Zeyi Huang
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Ian J MacRae
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA 92037, USA.
| | - Giordano Lippi
- Department of Neuroscience, The Scripps Research Institute, La Jolla, CA 92037, USA.
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2
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Chen X, Sokirniy I, Wang X, Jiang M, Mseis-Jackson N, Williams C, Mayes K, Jiang N, Puls B, Du Q, Shi Y, Li H. MicroRNA-375 Is Induced during Astrocyte-to-Neuron Reprogramming and Promotes Survival of Reprogrammed Neurons when Overexpressed. Cells 2023; 12:2202. [PMID: 37681934 PMCID: PMC10486704 DOI: 10.3390/cells12172202] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2023] [Revised: 08/25/2023] [Accepted: 09/01/2023] [Indexed: 09/09/2023] Open
Abstract
While astrocyte-to-neuron (AtN) reprogramming holds great promise in regenerative medicine, the molecular mechanisms that govern this unique biological process remain elusive. To understand the function of miRNAs during the AtN reprogramming process, we performed RNA-seq of both mRNAs and miRNAs on human astrocyte (HA) cultures upon NeuroD1 overexpression. Bioinformatics analyses showed that NeuroD1 not only activated essential neuronal genes to initiate the reprogramming process but also induced miRNA changes in HA. Among the upregulated miRNAs, we identified miR-375 and its targets, neuronal ELAVL genes (nELAVLs), which encode a family of RNA-binding proteins and were also upregulated by NeuroD1. We further showed that manipulating the miR-375 level regulated nELAVLs' expression during NeuroD1-mediated reprogramming. Interestingly, miR-375/nELAVLs were also induced by the reprogramming factors Neurog2 and ASCL1 in HA, suggesting a conserved function to neuronal reprogramming, and by NeuroD1 in the mouse astrocyte culture and spinal cord. Functionally, we showed that miR-375 overexpression improved NeuroD1-mediated reprogramming efficiency by promoting cell survival at early stages in HA and did not appear to compromise the maturation of the reprogrammed neurons. Lastly, overexpression of miR-375-refractory ELAVL4 induced apoptosis and reversed the cell survival-promoting effect of miR-375 during AtN reprogramming. Together, we demonstrated a neuroprotective role of miR-375 during NeuroD1-mediated AtN reprogramming.
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Affiliation(s)
- Xuanyu Chen
- Department of Neuroscience & Regenerative Medicine, Medical College of Georgia at Augusta University, Augusta, GA 30912, USA
| | - Ivan Sokirniy
- Department of Biomedical Engineering, The Pennsylvania State University, University Park, PA 16802, USA
| | - Xin Wang
- Department of Biology, The Pennsylvania State University, University Park, PA 16802, USA
| | - Mei Jiang
- Department of Neuroscience & Regenerative Medicine, Medical College of Georgia at Augusta University, Augusta, GA 30912, USA
| | - Natalie Mseis-Jackson
- Department of Neuroscience & Regenerative Medicine, Medical College of Georgia at Augusta University, Augusta, GA 30912, USA
| | - Christine Williams
- Department of Chemistry & Biochemistry, College of Science & Mathematics, Augusta University, Augusta, GA 30912, USA
| | - Kristopher Mayes
- Department of Neuroscience & Regenerative Medicine, Medical College of Georgia at Augusta University, Augusta, GA 30912, USA
| | - Na Jiang
- Department of Neuroscience & Regenerative Medicine, Medical College of Georgia at Augusta University, Augusta, GA 30912, USA
| | - Brendan Puls
- Department of Biology, The Pennsylvania State University, University Park, PA 16802, USA
| | - Quansheng Du
- Department of Neuroscience & Regenerative Medicine, Medical College of Georgia at Augusta University, Augusta, GA 30912, USA
| | - Yang Shi
- Department of Neuroscience & Regenerative Medicine, Medical College of Georgia at Augusta University, Augusta, GA 30912, USA
- Division of Biostatistics and Data Science, Department of Population Health Sciences, Medical College of Georgia at Augusta University, Augusta, GA 30912, USA
| | - Hedong Li
- Department of Neuroscience & Regenerative Medicine, Medical College of Georgia at Augusta University, Augusta, GA 30912, USA
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3
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Chen X, Sokirniy I, Wang X, Jiang M, Mseis-Jackson N, Williams C, Mayes K, Jiang N, Puls B, Du Q, Shi Y, Li H. MicroRNA-375 is induced during astrocyte-to-neuron reprogramming and promotes survival of reprogrammed neurons when overexpressed. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.10.548401. [PMID: 37503054 PMCID: PMC10369893 DOI: 10.1101/2023.07.10.548401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/29/2023]
Abstract
While astrocyte-to-neuron (AtN) reprogramming holds great promise in regenerative medicine, the molecular mechanisms that govern this unique biological process remain elusive. MicroRNAs (miRNAs), as post-transcriptional regulators of gene expression, play crucial roles during development and under various pathological conditions. To understand the function of miRNAs during AtN reprogramming process, we performed RNA-seq of both mRNAs and miRNAs on human astrocyte (HA) cultures upon NeuroD1 overexpression. Bioinformatics analyses showed that NeuroD1 not only activates essential neuronal genes to initiate reprogramming process but also induces miRNA changes in HA. Among the upregulated miRNAs, we identified miR-375 and its targets, neuronal ELAVL genes ( nELAVLs ), which encode a family of RNA-binding proteins and are also upregulated by NeuroD1. We further showed that manipulating miR-375 level regulates nELAVLs expression during NeuroD1-mediated reprogramming. Interestingly, miR-375/ nELAVLs are also induced by reprogramming factors Neurog2 and ASCL1 in HA suggesting a conserved function to neuronal reprogramming, and by NeuroD1 in the mouse astrocyte culture and spinal cord. Functionally, we showed that miR-375 overexpression improves NeuroD1-mediated reprogramming efficiency by promoting cell survival at early stages in HA even in cultures treated with the chemotherapy drug Cisplatin. Moreover, miR-375 overexpression doesn't appear to compromise maturation of the reprogrammed neurons in long term HA cultures. Lastly, overexpression of miR-375-refractory ELAVL4 induces apoptosis and reverses the cell survival-promoting effect of miR-375 during AtN reprogramming. Together, we demonstrate a neuro-protective role of miR-375 during NeuroD1-mediated AtN reprogramming and suggest a strategy of combinatory overexpression of NeuroD1 and miR-375 for improving neuronal reprogramming efficiency.
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Laneve P, Caffarelli E. The Non-coding Side of Medulloblastoma. Front Cell Dev Biol 2020; 8:275. [PMID: 32528946 PMCID: PMC7266940 DOI: 10.3389/fcell.2020.00275] [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: 02/14/2020] [Accepted: 03/31/2020] [Indexed: 12/18/2022] Open
Abstract
Medulloblastoma (MB) is the most common pediatric brain tumor and a primary cause of cancer-related death in children. Until a few years ago, only clinical and histological features were exploited for MB pathological classification and outcome prognosis. In the past decade, the advancement of high-throughput molecular analyses that integrate genetic, epigenetic, and expression data, together with the availability of increasing wealth of patient samples, revealed the existence of four molecularly distinct MB subgroups. Their further classification into 12 subtypes not only reduced the well-characterized intertumoral heterogeneity, but also provided new opportunities for the design of targets for precision oncology. Moreover, the identification of tumorigenic and self-renewing subpopulations of cancer stem cells in MB has increased our knowledge of its biology. Despite these advancements, the origin of MB is still debated, and its molecular bases are poorly characterized. A major goal in the field is to identify the key genes that drive tumor growth and the mechanisms through which they are able to promote tumorigenesis. So far, only protein-coding genes acting as oncogenic drivers have been characterized in each MB subgroup. The contribution of the non-coding side of the genome, which produces a plethora of transcripts that control fundamental biological processes, as the cell choice between proliferation and differentiation, is still unappreciated. This review wants to fill this major gap by summarizing the recent findings on the impact of non-coding RNAs in MB initiation and progression. Furthermore, their potential role as specific MB biomarkers and novel therapeutic targets is also highlighted.
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Affiliation(s)
- Pietro Laneve
- Institute of Molecular Biology and Pathology, National Research Council, Rome, Italy
| | - Elisa Caffarelli
- Institute of Molecular Biology and Pathology, National Research Council, Rome, Italy
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5
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Liu Q, Zhang L, Li H. New Insights: MicroRNA Function in CNS Development and Psychiatric Diseases. ACTA ACUST UNITED AC 2018. [DOI: 10.1007/s40495-018-0129-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
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Abstract
Epigenetics is a growing field of knowledge that is changing our understanding of pathologic processes. For many cerebellar disorders, recent discoveries of epigenetic mechanisms help us to understand their pathophysiology. In this chapter, a short explanation of each epigenetic mechanism (including methylation, histone modification, and miRNA) is followed by references to those cerebellar disorders in which relevant epigenetic advances have been made. The importance of normal timing and distribution of methylation during neurodevelopment is explained. Abnormal methylation and altered gene expression in the developing cerebellum have been related to neurodevelopmental disorders such as autism, Rett syndrome, and fragile X syndrome. DNA packaging by histones is another important epigenetic mechanism in cerebellar functioning. Current knowledge of histone abnormalities in cerebellar diseases such as Friedreich ataxia and spinocerebellar ataxias is reviewed, including implications for new therapeutic approaches to these degenerative diseases. Finally, micro RNAs, the third mechanism to modulate DNA expression, and their role in normal cerebellar development and disease are described. Understanding how genetic and epigenetic mechanisms interact not only in normal cerebellar development but also in disease is a great challenge. However, such understanding will lead to promising new therapeutic possibilities as is already occurring in other areas of medicine.
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Affiliation(s)
- Mercedes Serrano
- Pediatric Neurology Department and Pediatric Institute for Genetic Medicine and Rare Diseases, Hospital Sant Joan de Déu; and Centre for Biomedical Research on Rare Diseases, Instituto de Salud Carlos III, Barcelona, Spain.
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7
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Penha RCC, Sepe R, De Martino M, Esposito F, Pellecchia S, Raia M, Del Vecchio L, Decaussin-Petrucci M, De Vita G, Pinto LFR, Fusco A. Role of Dicer1 in thyroid cell proliferation and differentiation. Cell Cycle 2017; 16:2282-2289. [PMID: 28933615 DOI: 10.1080/15384101.2017.1380127] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
DICER1 plays a central role in the biogenesis of microRNAs and it is important for normal development. Altered microRNA expression and DICER1 dysregulation have been described in several types of tumors, including thyroid carcinomas. Recently, our group identified a new somatic mutation (c.5438A>G; E1813G) within DICER1 gene of an unknown function. Herein, we show that DICER1 is overexpressed, at mRNA level, in a significant-relative number of papillary (70%) and anaplastic (42%) thyroid carcinoma samples, whereas is drastically downregulated in all the analyzed human thyroid carcinoma cell lines (TPC-1, BCPAP, FRO and 8505c) in comparison with normal thyroid tissue samples. Conversely, DICER1 is downregulated, at protein level, in PTC in comparison with normal thyroid tissues. Our data also reveals that DICER1 overexpression positively regulates thyroid cell proliferation, whereas its silencing impairs thyroid cell differentiation. The expression of DICER1 gene mutation (c.5438A>G; E1813G) negatively affects the microRNA machinery and cell proliferation as well as upregulates DICER1 protein levels of thyroid cells but has no impact on thyroid differentiation. In conclusion, DICER1 protein is downregulated in papillary thyroid carcinomas and affects thyroid proliferation and differentiation, while DICER1 gene mutation (c.5438A>G; E1813G) compromises the DICER1 wild-type-mediated microRNA processing and cell proliferation.
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Affiliation(s)
- Ricardo Cortez Cardoso Penha
- a Istituto per l'Endocrinologia e l'Oncologia Sperimentale (IEOS) "G. Salvatore", Consiglio Nazionale delle Ricerche (CNR), c/o Dipartimento di Medicina Molecolare e Biotecnologie Mediche, Università degli Studi di Napoli "Federico II" , Naples , Italy.,b Instituto Nacional de Câncer - INCA, Centro de Pesquisas (CPQ) , Rio de Janeiro , RJ , Brazil
| | - Romina Sepe
- a Istituto per l'Endocrinologia e l'Oncologia Sperimentale (IEOS) "G. Salvatore", Consiglio Nazionale delle Ricerche (CNR), c/o Dipartimento di Medicina Molecolare e Biotecnologie Mediche, Università degli Studi di Napoli "Federico II" , Naples , Italy
| | - Marco De Martino
- a Istituto per l'Endocrinologia e l'Oncologia Sperimentale (IEOS) "G. Salvatore", Consiglio Nazionale delle Ricerche (CNR), c/o Dipartimento di Medicina Molecolare e Biotecnologie Mediche, Università degli Studi di Napoli "Federico II" , Naples , Italy
| | - Francesco Esposito
- a Istituto per l'Endocrinologia e l'Oncologia Sperimentale (IEOS) "G. Salvatore", Consiglio Nazionale delle Ricerche (CNR), c/o Dipartimento di Medicina Molecolare e Biotecnologie Mediche, Università degli Studi di Napoli "Federico II" , Naples , Italy
| | - Simona Pellecchia
- a Istituto per l'Endocrinologia e l'Oncologia Sperimentale (IEOS) "G. Salvatore", Consiglio Nazionale delle Ricerche (CNR), c/o Dipartimento di Medicina Molecolare e Biotecnologie Mediche, Università degli Studi di Napoli "Federico II" , Naples , Italy
| | - Maddalena Raia
- c CEINGE-Biotecnologie Avanzate, Università di Napoli Federico II , Naples , Italy
| | - Luigi Del Vecchio
- c CEINGE-Biotecnologie Avanzate, Università di Napoli Federico II , Naples , Italy.,d Department of Molecular Medicine and Medical Biotechnologies , University of Naples Federico II , Naples , Italy
| | | | - Gabriella De Vita
- d Department of Molecular Medicine and Medical Biotechnologies , University of Naples Federico II , Naples , Italy
| | | | - Alfredo Fusco
- a Istituto per l'Endocrinologia e l'Oncologia Sperimentale (IEOS) "G. Salvatore", Consiglio Nazionale delle Ricerche (CNR), c/o Dipartimento di Medicina Molecolare e Biotecnologie Mediche, Università degli Studi di Napoli "Federico II" , Naples , Italy.,b Instituto Nacional de Câncer - INCA, Centro de Pesquisas (CPQ) , Rio de Janeiro , RJ , Brazil
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8
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Liu Q, Jiang M, Kuang Y, Shu X, Li J, Li MW, Li H. Dicer1 Ablation Impairs Responsiveness of Cerebellar Granule Neuron Precursors to Sonic Hedgehog and Disrupts Expression of Distinct Cell Cycle Regulator Genes. THE CEREBELLUM 2017; 16:450-461. [PMID: 27600805 DOI: 10.1007/s12311-016-0821-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Granule neuron precursors (GNPs) proliferate under the influence of Sonic hedgehog (Shh) that is secreted by Purkinje neurons during early postnatal cerebellar development. To investigate microRNA (miRNA) function in this developmental process, we conditionally deleted the Dicer1 gene under the activity of human glial fibrillary acidic protein (hGFAP) promoter. We report that Dicer1-ablated GNPs display decreased proliferation and survival at early postnatal stages and that the proliferation defect of mutant GNPs cannot be rescued by treatment of an Shh agonist in vitro as assayed by 5-bromo-2'-deoxyuridine (BrdU) pulse labeling and Shh target gene expression detection. Further analysis reveals that the expression of distinct cell cycle regulator genes including cell cycle inhibitor, CDKN1a (p21), selectively increases in Dicer1-ablated GNPs. Subsequently, we demonstrate that miR-17-5p exhibits high expression level in the developing cerebellum and that transfection of a synthetic miR-17-5p mimic downregulates p21 protein expression in GNPs and promotes proliferation of GNPs in culture. Therefore, Dicer1 ablation impairs Shh-induced GNP proliferation by disrupting the expression of distinct cell cycle regulator genes that are targets of miR-17∼92 cluster members. This study establishes a molecular link between miRNAs and cell cycle progression in the proliferating GNPs during normal cerebellar development and may facilitate miRNA application in treating medulloblastoma.
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Affiliation(s)
- Qian Liu
- West China Developmental & Stem Cell Institute, West China Second University Hospital, Sichuan University, Chengdu, 610041, People's Republic of China
| | - Mei Jiang
- West China Developmental & Stem Cell Institute, West China Second University Hospital, Sichuan University, Chengdu, 610041, People's Republic of China
| | - Yi Kuang
- West China Developmental & Stem Cell Institute, West China Second University Hospital, Sichuan University, Chengdu, 610041, People's Republic of China.,School of Life Science, Sichuan University, Chengdu, 610041, People's Republic of China
| | - Xiaoqiong Shu
- West China Developmental & Stem Cell Institute, West China Second University Hospital, Sichuan University, Chengdu, 610041, People's Republic of China
| | - Jun Li
- West China Developmental & Stem Cell Institute, West China Second University Hospital, Sichuan University, Chengdu, 610041, People's Republic of China
| | - Matthew W Li
- QSI International School of Chengdu, Chengdu, 610041, People's Republic of China
| | - Hedong Li
- West China Developmental & Stem Cell Institute, West China Second University Hospital, Sichuan University, Chengdu, 610041, People's Republic of China. .,Department of Obstetric & Gynecologic and Pediatric, West China Second University Hospital, Sichuan University, Chengdu, 610041, People's Republic of China. .,Key Laboratory of Birth Defects and Related Diseases of Women and Children (Sichuan University), Ministry of Education, Chengdu, 610041, People's Republic of China.
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9
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Constantin L. The Role of MicroRNAs in Cerebellar Development and Autism Spectrum Disorder During Embryogenesis. Mol Neurobiol 2016; 54:6944-6959. [PMID: 27774573 DOI: 10.1007/s12035-016-0220-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2016] [Accepted: 10/12/2016] [Indexed: 02/03/2023]
Abstract
MicroRNAs (miRNAs) are a class of small non-coding RNA molecules with wide-ranging and subtle effects on protein production. Their activity during the development of the cerebellum provides a valuable exemplar of how non-coding molecules may assist the development and function of the central nervous system and drive neurodevelopmental disorders. Three distinct aspects of miRNA contribution to early cerebellar development will here be reviewed. Aspects are the establishment of the cerebellar anlage, the generation and maturation of at least two principal cell types of the developing cerebellar microcircuit, and the etiology and early progression of autism spectrum disorder. It will be argued here that the autism spectrum is an adept model to explore miRNA impact on the cognitive and affective processes that descend from the developing cerebellum.
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Affiliation(s)
- Lena Constantin
- School of Biomedical Sciences, The University of Queensland, St Lucia, QLD, 4072, Australia. .,Institute for Molecular Bioscience, The University of Queensland, St Lucia, QLD, 4072, Australia.
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10
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Swahari V, Nakamura A, Deshmukh M. The paradox of dicer in cancer. Mol Cell Oncol 2016; 3:e1155006. [PMID: 27314098 PMCID: PMC4909435 DOI: 10.1080/23723556.2016.1155006] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2016] [Revised: 02/10/2016] [Accepted: 02/11/2016] [Indexed: 12/22/2022]
Abstract
Dicer has been well studied in cancer; however, deciphering its exact function in tumorigenesis continues to be a challenge. While partial suppression or truncation of Dicer promotes tumorigenesis, its complete deletion inhibits tumor growth. Here, we discuss this Dicer cancer conundrum in the context of its recently discovered role in the DNA damage response.
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Affiliation(s)
- Vijay Swahari
- Neuroscience Center, University of North Carolina at Chapel Hill , North Carolina
| | - Ayumi Nakamura
- Neuroscience Center, University of North Carolina at Chapel Hill , North Carolina
| | - Mohanish Deshmukh
- Neuroscience Center, University of North Carolina at Chapel Hill , North Carolina
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11
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MicroRNA Biogenesis and Hedgehog-Patched Signaling Cooperate to Regulate an Important Developmental Transition in Granule Cell Development. Genetics 2016; 202:1105-18. [PMID: 26773048 DOI: 10.1534/genetics.115.184176] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2015] [Accepted: 01/10/2016] [Indexed: 12/20/2022] Open
Abstract
The Dicer1, Dcr-1 homolog (Drosophila) gene encodes a type III ribonuclease required for the canonical maturation and functioning of microRNAs (miRNAs). Subsets of miRNAs are known to regulate normal cerebellar granule cell development, in addition to the growth and progression of medulloblastoma, a neoplasm that often originates from granule cell precursors. Multiple independent studies have also demonstrated that deregulation of Sonic Hedgehog (Shh)-Patched (Ptch) signaling, through miRNAs, is causative of granule cell pathologies. In the present study, we investigated the genetic interplay between miRNA biogenesis and Shh-Ptch signaling in granule cells of the cerebellum by way of the Cre/lox recombination system in genetically engineered models of Mus musculus (mouse). We demonstrate that, although the miRNA biogenesis and Shh-Ptch-signaling pathways, respectively, regulate the opposing growth processes of cerebellar hypoplasia and hyperplasia leading to medulloblastoma, their concurrent deregulation was nonadditive and did not bring the growth phenotypes toward an expected equilibrium. Instead, mice developed either hypoplasia or medulloblastoma, but of a greater severity. Furthermore, some genotypes were bistable, whereby subsets of mice developed hypoplasia or medulloblastoma. This implies that miRNAs and Shh-Ptch signaling regulate an important developmental transition in granule cells of the cerebellum. We also conclusively show that the Dicer1 gene encodes a haploinsufficient tumor suppressor gene for Ptch1-induced medulloblastoma, with the monoallielic loss of Dicer1 more severe than biallelic loss. These findings exemplify how genetic interplay between pathways may produce nonadditive effects with a substantial and unpredictable impact on biology. Furthermore, these findings suggest that the functional dosage of Dicer1 may nonadditively influence a wide range of Shh-Ptch-dependent pathologies.
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12
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Swahari V, Nakamura A, Baran-Gale J, Garcia I, Crowther AJ, Sons R, Gershon TR, Hammond S, Sethupathy P, Deshmukh M. Essential Function of Dicer in Resolving DNA Damage in the Rapidly Dividing Cells of the Developing and Malignant Cerebellum. Cell Rep 2015; 14:216-24. [PMID: 26748703 DOI: 10.1016/j.celrep.2015.12.037] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2015] [Revised: 10/23/2015] [Accepted: 12/06/2015] [Indexed: 01/09/2023] Open
Abstract
Maintenance of genomic integrity is critical during neurodevelopment, particularly in rapidly dividing cerebellar granule neuronal precursors that experience constitutive replication-associated DNA damage. As Dicer was recently recognized to have an unexpected function in the DNA damage response, we examined whether Dicer was important for preserving genomic integrity in the developing brain. We report that deletion of Dicer in the developing mouse cerebellum resulted in the accumulation of DNA damage leading to cerebellar progenitor degeneration, which was rescued with p53 deficiency; deletion of DGCR8 also resulted in similar DNA damage and cerebellar degeneration. Dicer deficiency also resulted in DNA damage and death in other rapidly dividing cells including embryonic stem cells and the malignant cerebellar progenitors in a mouse model of medulloblastoma. Together, these results identify an essential function of Dicer in resolving the spontaneous DNA damage that occurs during the rapid proliferation of developmental progenitors and malignant cells.
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Affiliation(s)
- Vijay Swahari
- Neuroscience Center, University of North Carolina, Chapel Hill, NC 27599, USA.
| | - Ayumi Nakamura
- Neuroscience Center, University of North Carolina, Chapel Hill, NC 27599, USA; Neurobiology Curriculum, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Jeanette Baran-Gale
- Curriculum in Bioinformatics and Computational Biology, University of North Carolina, Chapel Hill, NC 27599, USA; Department of Genetics, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Idoia Garcia
- Neuroscience Center, University of North Carolina, Chapel Hill, NC 27599, USA; Department of Neurology, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Andrew J Crowther
- Neuroscience Center, University of North Carolina, Chapel Hill, NC 27599, USA; Department of Neurology, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Robert Sons
- Department of Cell Biology and Physiology, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Timothy R Gershon
- Neuroscience Center, University of North Carolina, Chapel Hill, NC 27599, USA; Neurobiology Curriculum, University of North Carolina, Chapel Hill, NC 27599, USA; Department of Neurology, University of North Carolina, Chapel Hill, NC 27599, USA; Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Scott Hammond
- Department of Cell Biology and Physiology, University of North Carolina, Chapel Hill, NC 27599, USA; Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Praveen Sethupathy
- Curriculum in Bioinformatics and Computational Biology, University of North Carolina, Chapel Hill, NC 27599, USA; Department of Genetics, University of North Carolina, Chapel Hill, NC 27599, USA; Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Mohanish Deshmukh
- Neuroscience Center, University of North Carolina, Chapel Hill, NC 27599, USA; Neurobiology Curriculum, University of North Carolina, Chapel Hill, NC 27599, USA; Department of Cell Biology and Physiology, University of North Carolina, Chapel Hill, NC 27599, USA; Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599, USA.
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