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Korb A, Tajbakhsh S, Comai GE. Functional specialisation and coordination of myonuclei. Biol Rev Camb Philos Soc 2024. [PMID: 38477382 DOI: 10.1111/brv.13063] [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: 04/10/2023] [Revised: 01/30/2024] [Accepted: 02/02/2024] [Indexed: 03/14/2024]
Abstract
Myofibres serve as the functional unit for locomotion, with the sarcomere as fundamental subunit. Running the entire length of this structure are hundreds of myonuclei, located at the periphery of the myofibre, juxtaposed to the plasma membrane. Myonuclear specialisation and clustering at the centre and ends of the fibre are known to be essential for muscle contraction, yet the molecular basis of this regionalisation has remained unclear. While the 'myonuclear domain hypothesis' helped explain how myonuclei can independently govern large cytoplasmic territories, novel technologies have provided granularity on the diverse transcriptional programs running simultaneously within the syncytia and added a new perspective on how myonuclei communicate. Building upon this, we explore the critical cellular and molecular sources of transcriptional and functional heterogeneity within myofibres, discussing the impact of intrinsic and extrinsic factors on myonuclear programs. This knowledge provides new insights for understanding muscle development, repair, and disease, but also opens avenues for the development of novel and precise therapeutic approaches.
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Affiliation(s)
- Amaury Korb
- Institut Pasteur, Université Paris Cité, CNRS UMR 3738, Stem Cells & Development Unit, 25 rue du Dr. Roux, Institut Pasteur, Paris, F-75015, France
| | - Shahragim Tajbakhsh
- Institut Pasteur, Université Paris Cité, CNRS UMR 3738, Stem Cells & Development Unit, 25 rue du Dr. Roux, Institut Pasteur, Paris, F-75015, France
| | - Glenda E Comai
- Institut Pasteur, Université Paris Cité, CNRS UMR 3738, Stem Cells & Development Unit, 25 rue du Dr. Roux, Institut Pasteur, Paris, F-75015, France
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2
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Navarro-Martínez A, Vicente-García C, Carvajal JJ. NMJ-related diseases beyond the congenital myasthenic syndromes. Front Cell Dev Biol 2023; 11:1216726. [PMID: 37601107 PMCID: PMC10436495 DOI: 10.3389/fcell.2023.1216726] [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: 05/04/2023] [Accepted: 07/21/2023] [Indexed: 08/22/2023] Open
Abstract
Neuromuscular junctions (NMJs) are a special type of chemical synapse that transmits electrical stimuli from motor neurons (MNs) to their innervating skeletal muscle to induce a motor response. They are an ideal model for the study of synapses, given their manageable size and easy accessibility. Alterations in their morphology or function lead to neuromuscular disorders, such as the congenital myasthenic syndromes, which are caused by mutations in proteins located in the NMJ. In this review, we highlight novel potential candidate genes that may cause or modify NMJs-related pathologies in humans by exploring the phenotypes of hundreds of mouse models available in the literature. We also underscore the fact that NMJs may differ between species, muscles or even sexes. Hence the importance of choosing a good model organism for the study of NMJ-related diseases: only taking into account the specific features of the mammalian NMJ, experimental results would be efficiently translated to the clinic.
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Affiliation(s)
| | - Cristina Vicente-García
- Centro Andaluz de Biología del Desarrollo, CSIC-UPO-JA, Universidad Pablo de Olavide, Sevilla, Spain
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3
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Babal YK, Sonmez E, Aksan Kurnaz I. Nervous system-related gene regulatory networks and functional evolution of ETS proteins across species. Biosystems 2023; 227-228:104891. [PMID: 37030605 DOI: 10.1016/j.biosystems.2023.104891] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2022] [Revised: 03/21/2023] [Accepted: 04/05/2023] [Indexed: 04/10/2023]
Abstract
The ETS domain transcription factor family is one of the major transcription factor superfamilies that play regulatory roles in development, cell growth, and cancer progression. Although different functions of ETS member proteins in the nervous system have been demonstrated in various studies, their role in neuronal cell differentiation and the evolutionary conservation of its target genes have not yet been extensively studied. In this study, we focused on the regulatory role of ETS transcription factors in neuronal differentiation and their functional evolution by comparative transcriptomics. In order to investigate the regulatory role of ETS transcription factors in neuronal differentiation across species, transcriptional profiles of ETS members and their target genes were investigated by comparing differentially expressed genes and gene regulatory networks, which were analyzed using human, gorilla, mouse, fruit fly and worm transcriptomics datasets. Bioinformatics approaches to examine the evolutionary conservation of ETS transcription factors during neuronal differentiation have shown that ETS member proteins regulate genes associated with neuronal differentiation, nervous system development, axon, and synaptic regulation in different organisms. This study is a comparative transcriptomic study of ETS transcription factors in terms of neuronal differentiation using a gene regulatory network inference algorithm. Overall, a comparison of gene regulation networks revealed that ETS members are indeed evolutionarily conserved in the regulation of neuronal differentiation. Nonetheless, ETS, PEA3, and ELF subfamilies were found to be relatively more active transcription factors in the transcriptional regulation of neuronal differentiation.
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Affiliation(s)
- Yigit Koray Babal
- Gebze Technical University, Institute of Biotechnology, 41400, Gebze Kocaeli, Turkey.
| | - Ekin Sonmez
- Gebze Technical University, Institute of Biotechnology, 41400, Gebze Kocaeli, Turkey
| | - Isil Aksan Kurnaz
- Gebze Technical University, Institute of Biotechnology, 41400, Gebze Kocaeli, Turkey; Gebze Technical University, Dept Molecular Biology and Genetics, 41400, Gebze Kocaeli, Turkey
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Qi Z, Wang S, Xuan A, Gu X, Deng J, Huang C, Zhang L, Yin X. MiR-142a-3p: A novel ACh receptor transcriptional regulator in association with peripheral nerve injury. MOLECULAR THERAPY. NUCLEIC ACIDS 2022; 30:325-336. [PMID: 36381585 PMCID: PMC9633872 DOI: 10.1016/j.omtn.2022.10.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Accepted: 10/12/2022] [Indexed: 12/15/2022]
Abstract
Long-term denervation leads to the disintegration of nicotinic acetylcholine receptor (nAChR) located at the endplate structure, which translates to deficits in functional activation despite nerve repair. Because of a lack of effective measures to protect AChR expression, we explored the effect of alterations in muscular miR-142a-3p on nAChR. In this study, we constructed a model of miR-142a-3p knockdown by transfecting a miR-142a-3p inhibitor short hairpin RNA (shRNA) into C2C12 myotubes, and we injected this miR-142a-3p inhibitor shRNA into the tibialis anterior (TA) muscle in uninjured mice and in denervated mice by transecting the sciatic nerve. Our results showed that miR-142a-3p knockdown led to an increased number and area of AChR clusters in myotubes in vitro and larger neuromuscular endplates in adult mice. Furthermore, miR-142a-3p knockdown delayed the disintegration of motor endplates after denervation. Last, upon miR-142a-3p knockdown in uninjured and denervated mice, we observed an increase in the mRNA levels of five AChR subunits as well as mRNAs of genes implicated in AChR transcription and AChR clustering. Together, these results suggest that miR-142a-3p may be a potential target for therapeutic intervention to prevent motor endplate degradation following peripheral nerve injury.
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Affiliation(s)
- Zhidan Qi
- Department of Orthopedics and Trauma, Peking University People’s Hospital, Beijing, China
| | - Shen Wang
- Department of Orthopedics and Trauma, Peking University People’s Hospital, Beijing, China
| | - Ang Xuan
- Britton Chance Center for Biomedical Photonics, Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan, China,MoE Key Laboratory for Biomedical Photonics, School of Engineering Sciences, Huazhong University of Science and Technology, Wuhan, China
| | - Xinyi Gu
- Department of Orthopedics and Trauma, Peking University People’s Hospital, Beijing, China
| | - Jin Deng
- Department of Orthopedics and Trauma, Peking University People’s Hospital, Beijing, China
| | - Chen Huang
- Department of Orthopedics and Trauma, Peking University People’s Hospital, Beijing, China
| | - Lei Zhang
- Electron Microscopy Analysis Laboratory, Medical and Health Analysis Center, Peking University, Beijing, China,Department of Biophysics, School of Basic Medical Sciences, Peking University, Beijing, China
| | - Xiaofeng Yin
- Department of Orthopedics and Trauma, Peking University People’s Hospital, Beijing, China,Pizhou People’s Hospital, Jiangsu, China,Corresponding author Xiaofeng Yin, Department of Orthopedics and Trauma, Peking University People’s Hospital, Beijing, China.
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Ou-Yang H, Wu SC, Sung LY, Yang SH, Yang SH, Chong KY, Chen CM. STAT3 Is an Upstream Regulator of Granzyme G in the Maternal-To-Zygotic Transition of Mouse Embryos. Int J Mol Sci 2021; 22:ijms22010460. [PMID: 33466434 PMCID: PMC7796490 DOI: 10.3390/ijms22010460] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2020] [Revised: 12/19/2020] [Accepted: 12/31/2020] [Indexed: 12/24/2022] Open
Abstract
The maternal-to-zygotic transition (MZT), which controls maternal signaling to synthesize zygotic gene products, promotes the preimplantation development of mouse zygotes to the two-cell stage. Our previous study reported that mouse granzyme g (Gzmg), a serine-type protease, is required for the MZT. In this study, we further identified the maternal factors that regulate the Gzmg promoter activity in the zygote to the two-cell stage of mouse embryos. A full-length Gzmg promoter from mouse genomic DNA, FL-pGzmg (−1696~+28 nt), was cloned, and four deletion constructs of this Gzmg promoter, Δ1-pGzmg (−1369~+28 nt), Δ2-pGzmg (−939~+28 nt), Δ3-pGzmg (−711~+28 nt) and Δ4-pGzmg (−417~+28 nt), were subsequently generated. Different-sized Gzmg promoters were used to perform promoter assays of mouse zygotes and two-cell stage embryos. The results showed that Δ4-pGzmg promoted the highest expression level of the enhanced green fluorescent protein (EGFP) reporter in the zygotes and two-cell embryos. The data suggested that time-specific transcription factors upregulated Gzmg by binding cis-elements in the −417~+28-nt Gzmg promoter region. According to the results of the promoter assay, the transcription factor binding sites were predicted and analyzed with the JASPAR database, and two transcription factors, signal transducer and activator of transcription 3 (STAT3) and GA-binding protein alpha (GABPα), were identified. Furthermore, STAT3 and GABPα are expressed and located in zygote pronuclei and two-cell nuclei were confirmed by immunofluorescence staining; however, only STAT3 was recruited to the mouse zygote pronuclei and two-cell nuclei injected with the Δ4-pGzmg reporter construct. These data indicated that STAT3 is a maternal transcription factor and may upregulate Gzmg to promote the MZT. Furthermore, treatment with a STAT3 inhibitor, S3I-201, caused mouse embryonic arrest at the zygote and two-cell stages. These results suggest that STAT3, a maternal protein, is a critical transcription factor and regulates Gzmg transcription activity in preimplantation mouse embryos. It plays an important role in the maternal-to-zygotic transition during early embryonic development.
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Affiliation(s)
- Huan Ou-Yang
- Department of Life Sciences, and Ph.D. Program in Translational Medicine, National Chung Hsing University, Taichung 402, Taiwan; (H.O.-Y.); (S.-H.Y.)
- Department of Animal Science and Technology, National Taiwan University, Taipei 106, Taiwan;
- Institute of Biotechnology, National Taiwan University, Taipei 106, Taiwan;
| | - Shinn-Chih Wu
- Department of Animal Science and Technology, National Taiwan University, Taipei 106, Taiwan;
| | - Li-Ying Sung
- Institute of Biotechnology, National Taiwan University, Taipei 106, Taiwan;
| | - Shiao-Hsuan Yang
- Department of Life Sciences, and Ph.D. Program in Translational Medicine, National Chung Hsing University, Taichung 402, Taiwan; (H.O.-Y.); (S.-H.Y.)
- Reproductive Medicine Center, Department of Gynecology, Changhua Christian Hospital, Changhua 515, Taiwan
| | - Shang-Hsun Yang
- Department of Physiology, National Cheng Kung University, Tainan 70101, Taiwan;
- Institute of Basic Medical Sciences, National Cheng Kung University, Tainan 70101, Taiwan
| | - Kowit-Yu Chong
- Department of Medical Biotechnology and Laboratory Science, College of Medicine, Chang Gung University, Taoyuan 333, Taiwan;
- Department of Laboratory Medicine, Chang Gung Memorial Hospital, Linkou, Taoyuan 333, Taiwan
| | - Chuan-Mu Chen
- Department of Life Sciences, and Ph.D. Program in Translational Medicine, National Chung Hsing University, Taichung 402, Taiwan; (H.O.-Y.); (S.-H.Y.)
- The iEGG and Animal Biotechnology Center, and Rong-Hsing Translational Medicine Research Center, National Chung Hsing University, Taichung 402, Taiwan
- Correspondence: ; Tel.: +886-4-22856309
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Yuan X, Dai M, Xu D. TERT promoter mutations and GABP transcription factors in carcinogenesis: More foes than friends. Cancer Lett 2020; 493:1-9. [PMID: 32768523 DOI: 10.1016/j.canlet.2020.07.003] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Revised: 06/17/2020] [Accepted: 07/04/2020] [Indexed: 12/27/2022]
Abstract
The transcriptional de-repression of the telomerase reverse transcriptase (TERT) gene and subsequent activation of telomerase is a prerequisite step in malignant transformation and progression. Recently, the gain-of-function mutation of the TERT promoter was identified in many types of human malignancies, and the mutated promoter acquires de novo ETS binding motifs through which the TERT transcription is activated. The ETS family transcription factors GABPA and GABPB1 have been shown to act as master drivers for the mutant TERT promoter activity. Indeed, GABPA or GABPB1 depletion leads to the down-regulation of TERT expression in the mutant TERT promoter-bearing cancer cells, and is thus proposed as targets for cancer therapy. Surprisingly, however, despite its key role in activating the mutant TERT promoter and telomerase, GABPA may itself function as a potent tumor suppressor in several malignancies. In this review, we address the collaboration between GABPA and mutant TERT promoter in cancer development, discuss selection trade-offs among different activities of GABPA in cancer evolution, and underscore the suppressive function of GABPA in cancer progression and implications in precision oncology.
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Affiliation(s)
- Xiaotian Yuan
- Center for Reproductive Medicine, Cheeloo College of Medicine, Shandong University, Jinan, 250012, PR China.
| | - Mingkai Dai
- Central Research Laboratory, The Second Hospital, Cheeloo College of Medicine, Shandong University, Jinan, 250033, PR China; Shandong University-Karolinska Institute Collaborative Laboratory for Cancer and Stem Cell Research, Shandong University Second Hospital, Jinan, 250033, PR China.
| | - Dawei Xu
- Shandong University-Karolinska Institute Collaborative Laboratory for Cancer and Stem Cell Research, Shandong University Second Hospital, Jinan, 250033, PR China; Department of Medicine, Division of Hematology, Bioclinicum and Center for Molecular Medicine (CMM), Karolinska Institutet and Karolinska University Hospital Solna, 171 64 Solna, Sweden.
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7
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Belotti E, Schaeffer L. Regulation of Gene expression at the neuromuscular Junction. Neurosci Lett 2020; 735:135163. [PMID: 32553805 DOI: 10.1016/j.neulet.2020.135163] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2020] [Revised: 06/11/2020] [Accepted: 06/14/2020] [Indexed: 01/08/2023]
Abstract
Gene expression in skeletal muscle is profoundly changed upon innervation. 50 years of research on the neuromuscular system have greatly increased our understanding of the mechanisms underlying these changes. By controlling the expression and the activity of key transcription factors, nerve-evoked electrical activity in the muscle fiber positively and negatively regulates the expression of hundreds of genes. Innervation also compartmentalizes gene expression into synaptic and extra-synaptic regions of muscle fibers. In addition, electrically-evoked, release of several factors (e.g. Agrin, Neuregulin, Wnt ligands) induce the clustering of synaptic proteins and of a few muscle nuclei. The sub-synaptic nuclei acquire a particular chromatin organization and develop a specific gene expression program dedicated to building and maintaining a functional neuromuscular synapse. Deciphering synapse-specific, transcriptional regulation started with the identification of the N-box, a six base pair element present in the promoters of the acetylcholine δ and ε subunits. Most genes with synapse-specific expression turned out to contain at least one N-box in their promoters. The N-box is a response element for the synaptic signals Agrin and Neuregulins as well as a binding site for transcription factors of the Ets family. The Ets transcription factors GABP and Erm are implicated in the activation of post-synaptic genes via the N-box. In muscle fibers, Erm expression is restricted to the NMJ whereas GABP is expressed in all muscle nuclei but phosphorylated and activated by the JNK and ERK signaling pathways in response to Agrin and Neuregulins. Post-synaptic gene expression also correlates with chromatin modifications at the genomic level as evidenced by the strong enrichment of decondensed chromatin and acetylated histones in sub-synaptic nuclei. Here we discuss these transcriptional pathways for synaptic specialization at NMJs.
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Affiliation(s)
- Edwige Belotti
- INMG, Inserm U1217, CNRS UMR5310, Université Lyon 1, Université De Lyon, Lyon, France
| | - Laurent Schaeffer
- INMG, Inserm U1217, CNRS UMR5310, Université Lyon 1, Université De Lyon, Lyon, France; Centre De Biotechnologie Cellulaire, Hospices Civils De Lyon, Lyon, France.
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Jun H, Ma Y, Chen Y, Gong J, Liu S, Wang J, Knights AJ, Qiao X, Emont MP, Xu XZS, Kajimura S, Wu J. Adrenergic-Independent Signaling via CHRNA2 Regulates Beige Fat Activation. Dev Cell 2020; 54:106-116.e5. [PMID: 32533922 DOI: 10.1016/j.devcel.2020.05.017] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2019] [Revised: 03/17/2020] [Accepted: 05/14/2020] [Indexed: 11/28/2022]
Abstract
Maintaining energy homeostasis upon environmental challenges, such as cold or excess calorie intake, is essential to the fitness and survival of mammals. Drug discovery efforts targeting β-adrenergic signaling have not been fruitful after decades of intensive research. We recently identified a new beige fat regulatory pathway mediated via the nicotinic acetylcholine receptor subunit CHRNA2. Here, we generated fat-specific Chrna2 KO mice and observed thermogenic defects in cold and metabolic dysfunction upon dietary challenges caused by adipocyte-autonomous regulation in vivo. We found that CHRNA2 signaling is activated after acute high fat diet feeding and this effect is manifested through both UCP1- and creatine-mediated mechanisms. Furthermore, our data suggested that CHRNA2 signaling may activate glycolytic beige fat, a subpopulation of beige adipocytes mediated by GABPα emerging in the absence of β-adrenergic signaling. These findings reveal the biological significance of the CHRNA2 pathway in beige fat biogenesis and energy homeostasis.
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Affiliation(s)
- Heejin Jun
- Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA
| | - Yingxu Ma
- Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA; Department of Cardiology, the Second Xiangya Hospital, Central South University, Changsha, Hunan 410013, China
| | - Yong Chen
- UCSF Diabetes Center, San Francisco, CA, USA; Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, San Francisco, CA, USA; Department of Cell and Tissue Biology, University of California, San Francisco, San Francisco, CA, USA
| | - Jianke Gong
- Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA; International Research Center for Sensory Biology and Technology of MOST, Key Laboratory of Molecular Biophysics of MOE, and College of Life Sciences and Technology, and Huazhong University of Science and Technology, Wuhan, Hubei 430074, China
| | - Shanshan Liu
- Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA
| | - Jine Wang
- Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA
| | | | - Xiaona Qiao
- Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA; Huashan Hospital, Fudan University, Shanghai 200040, China
| | - Margo P Emont
- Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA; Department of Molecular & Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - X Z Shawn Xu
- Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA; Department of Molecular & Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Shingo Kajimura
- UCSF Diabetes Center, San Francisco, CA, USA; Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, San Francisco, CA, USA; Department of Cell and Tissue Biology, University of California, San Francisco, San Francisco, CA, USA
| | - Jun Wu
- Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA; Department of Molecular & Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI 48109, USA.
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Liu C, Dai SK, Sun Z, Wang Z, Liu PP, Du HZ, Yu S, Liu CM, Teng ZQ. GA-binding protein GABPβ1 is required for the proliferation of neural stem/progenitor cells. Stem Cell Res 2019; 39:101501. [PMID: 31344652 DOI: 10.1016/j.scr.2019.101501] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/01/2019] [Revised: 07/08/2019] [Accepted: 07/12/2019] [Indexed: 01/02/2023] Open
Abstract
GA binding protein (GABP) is a ubiquitously expressed transcription factor that regulates the development of multiple cell types, including osteoblast, hematopoietic stem cells, B cells and T cells. However, so little is known about its biological function in the development of central nervous system. In this report, we show that GABP is highly expressed in neural stem/progenitor cells (NSPCs) and down-regulated in neurons, and that GABPβ1 is required for the proper proliferation of NSPCs. Knockdown of GABPα resulted in an elevated expression level of GABPβ1, and GABPβ1 down-regulation significantly decreased the proliferation of NSPCs, whereas GABPβ2 knockdown did not result in any changes in the proliferation of NSPCs. We observed that there was nearly a 21-fold increase of the GABPβ1S mRNA level in GABPβ1L KO NSPCs compared to WT cells, and knocking down of GABPβ1S in GABPβ1L KO NSPCs could further reduce their proliferation potential. We also found that knockdown of GABPβ1 promoted neuronal and astrocytic differentiation of NSPCs. Finally, we identified dozens of downstream target genes of GABPβ1, which are closely associated with the cell proliferation and differentiation. Collectively, our results suggest that both GABPβ1L and GABPβ1S play an essential role in regulating the proper proliferation and differentiation of NSPCs.
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Affiliation(s)
- Cong Liu
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, China; Savaid Medical School, University of Chinese Academy of Sciences, Beijing 100049, China; Institute for Stem Cell and Regeneration, Chinese Academy of Sciences, Beijing 100101, China
| | - Shang-Kun Dai
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, China; Savaid Medical School, University of Chinese Academy of Sciences, Beijing 100049, China; Institute for Stem Cell and Regeneration, Chinese Academy of Sciences, Beijing 100101, China
| | - Zhen Sun
- State Key Laboratory of Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Zhuo Wang
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, China; Savaid Medical School, University of Chinese Academy of Sciences, Beijing 100049, China; Institute for Stem Cell and Regeneration, Chinese Academy of Sciences, Beijing 100101, China
| | - Pei-Pei Liu
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, China; Institute for Stem Cell and Regeneration, Chinese Academy of Sciences, Beijing 100101, China
| | - Hong-Zhen Du
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, China; Institute for Stem Cell and Regeneration, Chinese Academy of Sciences, Beijing 100101, China
| | - Shuyang Yu
- State Key Laboratory of Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing 100193, China.
| | - Chang-Mei Liu
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, China; Savaid Medical School, University of Chinese Academy of Sciences, Beijing 100049, China; Institute for Stem Cell and Regeneration, Chinese Academy of Sciences, Beijing 100101, China; State Key Laboratory of Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing 100193, China.
| | - Zhao-Qian Teng
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, China; Savaid Medical School, University of Chinese Academy of Sciences, Beijing 100049, China; Institute for Stem Cell and Regeneration, Chinese Academy of Sciences, Beijing 100101, China; State Key Laboratory of Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing 100193, China.
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10
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Tintignac LA, Brenner HR, Rüegg MA. Mechanisms Regulating Neuromuscular Junction Development and Function and Causes of Muscle Wasting. Physiol Rev 2015; 95:809-52. [DOI: 10.1152/physrev.00033.2014] [Citation(s) in RCA: 224] [Impact Index Per Article: 24.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
The neuromuscular junction is the chemical synapse between motor neurons and skeletal muscle fibers. It is designed to reliably convert the action potential from the presynaptic motor neuron into the contraction of the postsynaptic muscle fiber. Diseases that affect the neuromuscular junction may cause failure of this conversion and result in loss of ambulation and respiration. The loss of motor input also causes muscle wasting as muscle mass is constantly adapted to contractile needs by the balancing of protein synthesis and protein degradation. Finally, neuromuscular activity and muscle mass have a major impact on metabolic properties of the organisms. This review discusses the mechanisms involved in the development and maintenance of the neuromuscular junction, the consequences of and the mechanisms involved in its dysfunction, and its role in maintaining muscle mass during aging. As life expectancy is increasing, loss of muscle mass during aging, called sarcopenia, has emerged as a field of high medical need. Interestingly, aging is also accompanied by structural changes at the neuromuscular junction, suggesting that the mechanisms involved in neuromuscular junction maintenance might be disturbed during aging. In addition, there is now evidence that behavioral paradigms and signaling pathways that are involved in longevity also affect neuromuscular junction stability and sarcopenia.
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Affiliation(s)
- Lionel A. Tintignac
- Biozentrum, University of Basel, Basel, Switzerland; Department of Biomedicine, University of Basel, Basel, Switzerland; and INRA, UMR866 Dynamique Musculaire et Métabolisme, Montpellier, France
| | - Hans-Rudolf Brenner
- Biozentrum, University of Basel, Basel, Switzerland; Department of Biomedicine, University of Basel, Basel, Switzerland; and INRA, UMR866 Dynamique Musculaire et Métabolisme, Montpellier, France
| | - Markus A. Rüegg
- Biozentrum, University of Basel, Basel, Switzerland; Department of Biomedicine, University of Basel, Basel, Switzerland; and INRA, UMR866 Dynamique Musculaire et Métabolisme, Montpellier, France
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11
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Zhu W, Swaminathan G, Plowey ED. GA binding protein augments autophagy via transcriptional activation of BECN1-PIK3C3 complex genes. Autophagy 2014; 10:1622-36. [PMID: 25046113 DOI: 10.4161/auto.29454] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Macroautophagy is a vesicular catabolic trafficking pathway that is thought to protect cells from diverse stressors and to promote longevity. Recent studies have revealed that transcription factors play important roles in the regulation of autophagy. In this study, we have identified GA binding protein (GABP) as a transcriptional regulator of the combinatorial expression of BECN1-PIK3C3 complex genes involved in autophagosome initiation. We performed bioinformatics analyses that demonstrated highly conserved putative GABP sites in genes that encode BECN1/Beclin 1, several BECN1 interacting proteins, and downstream autophagy proteins including the ATG12-ATG5-ATG16L1 complex. We demonstrate that GABP binds to the promoter regions of BECN1-PIK3C3 complex genes and activates their transcriptional activities. Knockdown of GABP reduced BECN1-PIK3C3 complex transcripts, BECN1-PIK3C3 complex protein levels and autophagy in cultured cells. Conversely, overexpression of GABP increased autophagy. Nutrient starvation increased GABP-dependent transcriptional activity of BECN1-PIK3C3 complex gene promoters and increased the recruitment of GABP to the BECN1 promoter. Our data reveal a novel function of GABP in the regulation of autophagy via transcriptional activation of the BECN1-PIK3C3 complex.
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Affiliation(s)
- Wan Zhu
- Department of Pathology; Stanford University School of Medicine; Stanford, CA USA
| | - Gayathri Swaminathan
- Department of Pathology; Stanford University School of Medicine; Stanford, CA USA
| | - Edward D Plowey
- Department of Pathology; Stanford University School of Medicine; Stanford, CA USA
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12
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Findlay VJ, LaRue AC, Turner DP, Watson PM, Watson DK. Understanding the role of ETS-mediated gene regulation in complex biological processes. Adv Cancer Res 2014; 119:1-61. [PMID: 23870508 DOI: 10.1016/b978-0-12-407190-2.00001-0] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Ets factors are members of one of the largest families of evolutionarily conserved transcription factors, regulating critical functions in normal cell homeostasis, which when perturbed contribute to tumor progression. The well-documented alterations in ETS factor expression and function during cancer progression result in pleiotropic effects manifested by the downstream effect on their target genes. Multiple ETS factors bind to the same regulatory sites present on target genes, suggesting redundant or competitive functions. The anti- and prometastatic signatures obtained by examining specific ETS regulatory networks will significantly improve our ability to accurately predict tumor progression and advance our understanding of gene regulation in cancer. Coordination of multiple ETS gene functions also mediates interactions between tumor and stromal cells and thus contributes to the cancer phenotype. As such, these new insights may provide a novel view of the ETS gene family as well as a focal point for studying the complex biological control involved in tumor progression. One of the goals of molecular biology is to elucidate the mechanisms that contribute to the development and progression of cancer. Such an understanding of the molecular basis of cancer will provide new possibilities for: (1) earlier detection, as well as better diagnosis and staging of disease; (2) detection of minimal residual disease recurrences and evaluation of response to therapy; (3) prevention; and (4) novel treatment strategies. Increased understanding of ETS-regulated biological pathways will directly impact these areas.
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Affiliation(s)
- Victoria J Findlay
- Department of Pathology and Laboratory Medicine, Hollings Cancer Center, Medical University of South Carolina, Charleston, South Carolina, USA
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13
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Regulatory elements associated with paternally-expressed genes in the imprinted murine Angelman/Prader-Willi syndrome domain. PLoS One 2013; 8:e52390. [PMID: 23390487 PMCID: PMC3563663 DOI: 10.1371/journal.pone.0052390] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2012] [Accepted: 11/13/2012] [Indexed: 11/19/2022] Open
Abstract
The Angelman/Prader-Willi syndrome (AS/PWS) domain contains at least 8 imprinted genes regulated by a bipartite imprinting center (IC) associated with the SNRPN gene. One component of the IC, the PWS-IC, governs the paternal epigenotype and expression of paternal genes. The mechanisms by which imprinting and expression of paternal genes within the AS/PWS domain – such as MKRN3 and NDN – are regulated by the PWS-IC are unclear. The syntenic region in the mouse is organized and imprinted similarly to the human domain with the murine PWS-IC defined by a 6 kb interval within the Snrpn locus that includes the promoter. To identify regulatory elements that may mediate PWS-IC function, we mapped the location and allele-specificity of DNase I hypersensitive (DH) sites within the PWS-IC in brain cells, then identified transcription factor binding sites within a subset of these DH sites. Six major paternal-specific DH sites were detected in the Snrpn gene, five of which map within the 6 kb PWS-IC. We postulate these five DH sites represent functional components of the murine PWS-IC. Analysis of transcription factor binding within multiple DH sites detected nuclear respiratory factors (NRF's) and YY1 specifically on the paternal allele. NRF's and YY1 were also detected in the paternal promoter region of the murine Mrkn3 and Ndn genes. These results suggest that NRF's and YY1 may facilitate PWS-IC function and coordinately regulate expression of paternal genes. The presence of NRF's also suggests a link between transcriptional regulation within the AS/PWS domain and regulation of respiration. 3C analyses indicated Mkrn3 lies in close proximity to the PWS-IC on the paternal chromosome, evidence that the PWS-IC functions by allele-specific interaction with its distal target genes. This could occur by allele-specific co-localization of the PWS-IC and its target genes to transcription factories containing NRF's and YY1.
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14
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Molecular mechanisms underlying maturation and maintenance of the vertebrate neuromuscular junction. Trends Neurosci 2012; 35:441-53. [PMID: 22633140 DOI: 10.1016/j.tins.2012.04.005] [Citation(s) in RCA: 105] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2012] [Revised: 04/09/2012] [Accepted: 04/15/2012] [Indexed: 01/22/2023]
Abstract
The vertebrate neuromuscular junction (NMJ), a peripheral synapse formed between motoneuron and skeletal muscle, is characterized by a protracted postnatal period of maturation and life-long maintenance. In neuromuscular disorders such as congenital myasthenic syndromes (CMSs), disruptions of NMJ maturation and/or maintenance are frequently observed. In particular, defective neuromuscular transmission associated with structural and molecular abnormalities at the pre- and postsynaptic membranes, as well as at the synaptic cleft, has been reported in these patients. Here, we review recent advances in the understanding of molecular and cellular events that mediate NMJ maturation and maintenance. The underlying regulatory mechanisms, including key molecular regulators at the presynaptic nerve terminal, synaptic cleft, and postsynaptic muscle membrane, are discussed.
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15
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Molecular mechanisms for age-associated mitochondrial deficiency in skeletal muscle. J Aging Res 2012; 2012:768304. [PMID: 22548174 PMCID: PMC3324903 DOI: 10.1155/2012/768304] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2011] [Accepted: 01/23/2012] [Indexed: 01/01/2023] Open
Abstract
The abundance, morphology, and functional properties of mitochondria decay in skeletal muscle during the process of ageing. Although the precise mechanisms remain to be elucidated, these mechanisms include decreased mitochondrial DNA (mtDNA) repair and mitochondrial biogenesis. Mitochondria possess their own protection system to repair mtDNA damage, which leads to defects of mtDNA-encoded gene expression and respiratory chain complex enzymes. However, mtDNA mutations have shown to be accumulated with age in skeletal muscle. When damaged mitochondria are eliminated by autophagy, mitochondrial biogenesis plays an important role in sustaining energy production and physiological homeostasis. The capacity for mitochondrial biogenesis has shown to decrease with age in skeletal muscle, contributing to progressive mitochondrial deficiency. Understanding how these endogenous systems adapt to altered physiological conditions during the process of ageing will provide a valuable insight into the underlying mechanisms that regulate cellular homeostasis. Here we will summarize the current knowledge about the molecular mechanisms responsible for age-associated mitochondrial deficiency in skeletal muscle. In particular, recent findings on the role of mtDNA repair and mitochondrial biogenesis in maintaining mitochondrial functionality in aged skeletal muscle will be highlighted.
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16
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Ngo ST, Cole RN, Sunn N, Phillips WD, Noakes PG. Neuregulin-1 potentiates agrin-induced acetylcholine receptor clustering through muscle-specific kinase phosphorylation. J Cell Sci 2012; 125:1531-43. [PMID: 22328506 DOI: 10.1242/jcs.095109] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
At neuromuscular synapses, neural agrin (n-agrin) stabilizes embryonic postsynaptic acetylcholine receptor (AChR) clusters by signalling through the muscle-specific kinase (MuSK) complex. Live imaging of cultured myotubes showed that the formation and disassembly of primitive AChR clusters is a dynamic and reversible process favoured by n-agrin, and possibly other synaptic signals. Neuregulin-1 is a growth factor that can act through muscle ErbB receptor kinases to enhance synaptic gene transcription. Recent studies suggest that neuregulin-1-ErbB signalling can modulate n-agrin-induced AChR clustering independently of its effects on transcription. Here we report that neuregulin-1 increased the size of developing AChR clusters when injected into muscles of embryonic mice. We investigated this phenomenon using cultured myotubes, and found that in the ongoing presence of n-agrin, neuregulin-1 potentiates AChR clustering by increasing the tyrosine phosphorylation of MuSK. This potentiation could be blocked by inhibiting Shp2, a postsynaptic tyrosine phosphatase known to modulate the activity of MuSK. Our results provide new evidence that neuregulin-1 modulates the signaling activity of MuSK and hence might function as a second-order regulator of postsynaptic AChR clustering at the neuromuscular synapse. Thus two classic synaptic signalling systems (neuregulin-1 and n-agrin) converge upon MuSK to regulate postsynaptic differentiation.
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Affiliation(s)
- Shyuan T Ngo
- School of Biomedical Sciences, University of Queensland, St. Lucia, 4072, Queensland, Australia
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17
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Yu S, Zhao DM, Jothi R, Xue HH. Critical requirement of GABPalpha for normal T cell development. J Biol Chem 2010; 285:10179-88. [PMID: 20139079 DOI: 10.1074/jbc.m109.088740] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
GA binding protein (GABP) consists of GABPalpha and GABPbeta subunits. GABPalpha is a member of Ets family transcription factors and binds DNA via its conserved Ets domain, whereas GABPbeta does not bind DNA but possesses transactivation activity. In T cells, GABP has been demonstrated to regulate the gene expression of interleukin-7 receptor alpha chain (IL-7Ralpha) and postulated to be critical in T cell development. To directly investigate its function in early thymocyte development, we used GABPalpha conditional knock-out mice where the exons encoding the Ets DNA-binding domain are flanked with LoxP sites. Ablation of GABPalpha with the Lck-Cre transgene greatly diminished thymic cellularity, blocked thymocyte development at the double negative 3 (DN3) stage, and resulted in reduced expression of T cell receptor (TCR) beta chain in DN4 thymocytes. By chromatin immunoprecipitation, we demonstrated in DN thymocytes that GABPalpha is associated with transcription initiation sites of genes encoding key molecules in TCR rearrangements. Among these GABP-associated genes, knockdown of GABPalpha expression by RNA interference diminished expression of DNA ligase IV, Artemis, and Ku80 components in DNA-dependent protein kinase complex. Interestingly, forced expression of prearranged TCR but not IL-7Ralpha can alleviate the DN3 block in GABPalpha-targeted mice. Our observations collectively indicate that in addition to regulating IL-7Ralpha expression, GABP is critically required for TCR rearrangements and hence normal T cell development.
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Affiliation(s)
- Shuyang Yu
- Department of Microbiology, Carver College of Medicine, University of Iowa, Iowa City, Iowa 52242, USA
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18
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Abstract
Mitochondria play central roles in energy homeostasis, metabolism, signaling, and apoptosis. Accordingly, the abundance, morphology, and functional properties of mitochondria are finely tuned to meet cell-specific energetic, metabolic, and signaling demands. This tuning is largely achieved at the level of transcriptional regulation. A highly interconnected network of transcription factors regulates a broad set of nuclear genes encoding mitochondrial proteins, including those that control replication and transcription of the mitochondrial genome. The same transcriptional network senses cues relaying cellular energy status, nutrient availability, and the physiological state of the organism and enables short- and long-term adaptive responses, resulting in adjustments to mitochondrial function and mitochondrial biogenesis. Mitochondrial dysfunction is associated with many human diseases. Characterization of the transcriptional mechanisms that regulate mitochondrial biogenesis and function can offer insights into possible therapeutic interventions aimed at modulating mitochondrial function.
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Affiliation(s)
- M Benjamin Hock
- Department of Chemical Physiology, The Scripps Research Institute, La Jolla, California 92037, USA
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19
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Jedlicka P, Sui X, Sussel L, Gutierrez-Hartmann A. Ets transcription factors control epithelial maturation and transit and crypt-villus morphogenesis in the mammalian intestine. THE AMERICAN JOURNAL OF PATHOLOGY 2009; 174:1280-90. [PMID: 19264912 DOI: 10.2353/ajpath.2009.080409] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Members of the Ets transcription factor family are widely expressed in both the developing and mature mammalian intestine, but their biological functions remain primarily uncharacterized. We used a dominant repressor transgene approach to probe the function of epithelial Ets factors in the homeostasis of the crypt-villus unit, the functional unit of the small intestine. We show that targeted expression in small intestinal epithelium of a fusion protein composed of the Engrailed repressor domain and the Erm DNA-binding domain (En/Erm) results in marked disruption of normal crypt-villus homeostasis, including a cell-autonomous disturbance of epithelial maturation, increased epithelial transit, severe villus dysmorphogenesis, and crypt dysmorphogenesis. The epithelial maturation disturbance is independent of the regulation of TGFbetaRII levels, in contrast to Ets-mediated epithelial differentiation during development; rather, regulation of Cdx2 expression may play a role. The villus dysmorphogenesis is independent of alterations in the crypt-villus boundary and inappropriate beta-catenin activation, and thus appears to represent a new mechanism controlling villus architectural organization. An Analysis of animals mosaic for En/Erm expression suggests that crypt nonautonomous mechanisms underlie the crypt dysmorphogenesis phenotype. Our studies thus uncover novel Ets-regulated pathways of intestinal homeostasis in vivo. Interestingly, the overall En/Erm phenotype of disturbed crypt-villus homeostasis is consistent with recently identified Ets function(s) in the restriction of intestinal epithelial tumorigenesis.
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Affiliation(s)
- Paul Jedlicka
- Department of Pathology, University of Colorado Denver, Anschutz Medical Center, PO Box 6511, MS 8104, Aurora CO 80045, USA.
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20
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Jedlicka P, Gutierrez-Hartmann A. Ets transcription factors in intestinal morphogenesis, homeostasis and disease. Histol Histopathol 2008; 23:1417-24. [PMID: 18785124 DOI: 10.14670/hh-23.1417] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Ets transcription factors comprise a large family of sequence-specific regulators of gene expression with important and diverse roles in development and disease. Most Ets family members are expressed in the developing and/or mature intestine, frequently in a compartment-specific and temporally dynamic manner. However, with the exception of the highly expressed Elf3, involved in embryonic epithelial differentiation, little is known about Ets functions in intestinal development and homeostasis. Ets factors show altered expression in colon cancer, where they regulate pathways relevant to tumor progression. Ets factors also likely act as important modifiers of non-neoplastic intestinal disease by regulating pathways relevant to tissue injury and repair. Despite a large body of published work on Ets biology, much remains to be learned about the precise functions of this large and diverse gene family in intestinal morphogenesis, homeostasis, and both neoplastic and non-neoplastic pathology.
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Affiliation(s)
- Paul Jedlicka
- Department of Pathology, University of Colorado Denver, Aurora CO 80045, USA.
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21
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Jing X, Zhao DM, Waldschmidt TJ, Xue HH. GABPbeta2 is dispensible for normal lymphocyte development but moderately affects B cell responses. J Biol Chem 2008; 283:24326-33. [PMID: 18628204 DOI: 10.1074/jbc.m804487200] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
GA-binding protein (GABP) is the only Ets family transcription factor that functions as a heterodimer. The GABPalpha subunit binds to DNA, and the GABPbeta subunit possesses the ability to transactivate target genes. Inactivation of GABPalpha caused embryonic lethality and defective lymphocyte development and immune responses. There are 3 isoforms of the GABPbeta subunit, but whether they have distinct functions has not been addressed. In this study, we selectively ablated the expression of GABPbeta2 using a gene trap strategy. GABPbeta2-deficient mice were viable and had normal T and B cell development, suggesting that loss of GABPbeta2 is compensated for by other GABPbeta isoforms during these processes. GABPbeta2-deficient T cells can be activated and proliferate similarly to wild-type controls. In contrast, B cells lacking GABPbeta2 showed 2-3-fold increases in proliferation in response to B cell receptor stimulation. In addition, GABPbeta2-deficient mice exhibited moderately increased antibody production and germinal center responses when challenged with T-dependent antigens. These results indicate that albeit GABPbeta isoforms are redundant in lymphocyte development, GABPbeta2 has a distinct role in restraining B cell expansion and humoral responses.
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Affiliation(s)
- Xuefang Jing
- Department of Microbiology, Carver College of Medicine, University of Iowa, Iowa City, Iowa 52242, USA
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22
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Targeting the GA binding protein beta1L isoform does not perturb lymphocyte development and function. Mol Cell Biol 2008; 28:4300-9. [PMID: 18426908 DOI: 10.1128/mcb.01855-07] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
GA binding protein (GABP) is a ubiquitously expressed Ets family transcription factor that consists of two subunits, GABPalpha and GABPbeta. GABPalpha binds to DNA, and GABPbeta heterodimerizes with GABPalpha and possesses the ability to transactivate target genes. Our previous studies using GABPalpha-deficient mice revealed that GABPalpha is required for the development of both T and B cells. Two splice variants of GABPbeta are generated from the Gabpb1 locus and differ in their carboxy-terminal lengths and sequences. The longer isoform (GABPbeta1L) can homodimerize and thus form alpha(2)beta(2) tetramers depending on the gene context, whereas the shorter isoform (GABPbeta1S) cannot. In this study, we generated mice that are deficient in GABPbeta1L but that retain the expression of GABPbeta1S. Surprisingly, GABPbeta1L-/- mice had normal T- and B-cell development, and mature T and B cells showed normal responses to various stimuli. In contrast, targeting both GABPbeta1L and GABPbeta1S resulted in early embryonic lethality. Because of its incapability of forming homodimers, GABPbeta1S has been suspected to have a dominant negative role in regulating GABP target genes. Our findings argue against such a possibility and rather suggest that GABPbeta1S has a critical role in maintaining the transcriptional activity of the GABPalpha/beta complex.
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23
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Herndon CA, Fromm L. Neuregulin-1 induces acetylcholine receptor transcription in the absence of GABPα phosphorylation. J Neurosci Res 2008; 86:982-91. [DOI: 10.1002/jnr.21563] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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24
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Kang HS, Nelson ML, Mackereth CD, Schärpf M, Graves BJ, McIntosh LP. Identification and structural characterization of a CBP/p300-binding domain from the ETS family transcription factor GABP alpha. J Mol Biol 2008; 377:636-46. [PMID: 18295234 DOI: 10.1016/j.jmb.2008.01.054] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2007] [Revised: 01/16/2008] [Accepted: 01/17/2008] [Indexed: 12/20/2022]
Abstract
Using NMR spectroscopy, we identified and characterized a previously unrecognized structured domain near the N-terminus (residues 35-121) of the ETS family transcription factor GABP alpha. The monomeric domain folds as a five-stranded beta-sheet crossed by a distorted helix. Although globally resembling ubiquitin, the GABP alpha fragment differs in its secondary structure topology and thus appears to represent a new protein fold that we term the OST (On-SighT) domain. The surface of the GABP alpha OST domain contains two predominant clusters of negatively-charged residues suggestive of electrostatically driven interactions with positively-charged partner proteins. Following a best-candidate approach to identify such a partner, we demonstrated through NMR-monitored titrations and glutathione S-transferase pulldown assays that the OST domain binds to the CH1 and CH3 domains of the co-activator histone acetyltransferase CBP/p300. This provides a direct structural link between GABP and a central component of the transcriptional machinery.
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Affiliation(s)
- Hyun-Seo Kang
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC, Canada
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25
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Hippenmeyer S, Huber RM, Ladle DR, Murphy K, Arber S. ETS Transcription Factor Erm Controls Subsynaptic Gene Expression in Skeletal Muscles. Neuron 2007; 55:726-40. [PMID: 17785180 DOI: 10.1016/j.neuron.2007.07.028] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2007] [Revised: 06/22/2007] [Accepted: 07/24/2007] [Indexed: 11/23/2022]
Abstract
Accumulation of specific proteins at synaptic structures is essential for synapse assembly and function, but mechanisms regulating local protein enrichment remain poorly understood. At the neuromuscular junction (NMJ), subsynaptic nuclei underlie motor axon terminals within extrafusal muscle fibers and are transcriptionally distinct from neighboring nuclei. In this study, we show that expression of the ETS transcription factor Erm is highly concentrated at subsynaptic nuclei, and its mutation in mice leads to severe downregulation of many genes with normally enriched subsynaptic expression. Erm mutant mice display an expansion of the muscle central domain in which acetylcholine receptor (AChR) clusters accumulate, show gradual fragmentation of AChR clusters, and exhibit symptoms of muscle weakness mimicking congenital myasthenic syndrome (CMS). Together, our findings define Erm as an upstream regulator of a transcriptional program selective to subsynaptic nuclei at the NMJ and underscore the importance of transcriptional control of local synaptic protein accumulation.
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Affiliation(s)
- Simon Hippenmeyer
- Biozentrum, Department of Cell Biology, University of Basel, Klingelbergstrasse 70, 4056 Basel, Switzerland
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26
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Jaworski A, Smith CL, Burden SJ. GA-binding protein is dispensable for neuromuscular synapse formation and synapse-specific gene expression. Mol Cell Biol 2007; 27:5040-6. [PMID: 17485447 PMCID: PMC1951497 DOI: 10.1128/mcb.02228-06] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
The mRNAs encoding postsynaptic components at the neuromuscular junction are concentrated in the synaptic region of muscle fibers. Accumulation of these RNAs in the synaptic region is mediated, at least in part, by selective transcription of the corresponding genes in synaptic myofiber nuclei. The transcriptional mechanisms that are responsible for synapse-specific gene expression are largely unknown, but an Ets site in the promoter regions of acetylcholine receptor (AChR) subunit genes and other "synaptic" genes is required for synapse-specific transcription. The Ets domain transcription factor GA-binding protein (GABP) has been implicated to mediate synapse-specific gene expression. Inactivation of GABPalpha, the DNA-binding subunit of GABP, leads to early embryonic lethality, preventing analysis of synapse formation in gabpalpha mutant mice. To study the role of GABP at neuromuscular synapses, we conditionally inactivated gabpalpha in skeletal muscle and studied synaptic differentiation and muscle gene expression. Although expression of rb, a target of GABP, is elevated in muscle tissue deficient in GABPalpha, clustering of synaptic AChRs at synapses and synapse-specific gene expression are normal in these mice. These data indicate that GABP is dispensable for synapse-specific transcription and maintenance of normal AChR expression at synapses.
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Affiliation(s)
- Alexander Jaworski
- The Helen L. and Martin S. Kimmel Center for Biology and Medicine, Skirball Institute of Biomoledular Medicine, NYU School of Medicine, New York, NY 10016, USA
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