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Gibaja A, Aburto MR, Pulido S, Collado M, Hurle JM, Varela-Nieto I, Magariños M. TGFβ2-induced senescence during early inner ear development. Sci Rep 2019; 9:5912. [PMID: 30976015 PMCID: PMC6459823 DOI: 10.1038/s41598-019-42040-0] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2019] [Accepted: 03/21/2019] [Indexed: 01/16/2023] Open
Abstract
Embryonic development requires the coordinated regulation of apoptosis, survival, autophagy, proliferation and differentiation programs. Senescence has recently joined the cellular processes required to master development, in addition to its well-described roles in cancer and ageing. Here, we show that senescent cells are present in a highly regulated temporal pattern in the developing vertebrate inner ear, first, surrounding the otic pore and, later, in the otocyst at the endolymphatic duct. Cellular senescence is associated with areas of increased apoptosis and reduced proliferation consistent with the induction of the process when the endolymphatic duct is being formed. Modulation of senescence disrupts otic vesicle morphology. Transforming growth factor beta (TGFβ) signaling interacts with signaling pathways elicited by insulin-like growth factor type 1 (IGF-1) to jointly coordinate cellular dynamics required for morphogenesis and differentiation. Taken together, these results show that senescence is a natural occurring process essential for early inner ear development.
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Affiliation(s)
- Alejandro Gibaja
- Instituto de Investigaciones Biomédicas "Alberto Sols" (CSIC-UAM), Madrid, Spain
| | - María R Aburto
- Instituto de Investigaciones Biomédicas "Alberto Sols" (CSIC-UAM), Madrid, Spain
| | - Sara Pulido
- Instituto de Investigaciones Biomédicas "Alberto Sols" (CSIC-UAM), Madrid, Spain.,CIBERER, Instituto de Salud Carlos III, Madrid, Spain
| | - Manuel Collado
- Instituto de Investigación Sanitaria de Santiago de Compostela, Santiago de Compostela, Spain
| | - Juan M Hurle
- Departamento de Anatomía y Biología Celular and IDIVAL, Universidad de Cantabria, Santander, Spain
| | - Isabel Varela-Nieto
- Instituto de Investigaciones Biomédicas "Alberto Sols" (CSIC-UAM), Madrid, Spain.,CIBERER, Instituto de Salud Carlos III, Madrid, Spain.,Instituto de Investigación Sanitaria del Hospital Universitario La Paz (IdiPAZ), Madrid, Spain
| | - Marta Magariños
- Instituto de Investigaciones Biomédicas "Alberto Sols" (CSIC-UAM), Madrid, Spain. .,CIBERER, Instituto de Salud Carlos III, Madrid, Spain. .,Departamento de Biología, Universidad Autónoma de Madrid, Madrid, Spain.
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2
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Varela-Nieto I, Palmero I, Magariños M. Complementary and distinct roles of autophagy, apoptosis and senescence during early inner ear development. Hear Res 2019; 376:86-96. [PMID: 30711386 DOI: 10.1016/j.heares.2019.01.014] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/30/2018] [Revised: 01/13/2019] [Accepted: 01/17/2019] [Indexed: 12/25/2022]
Abstract
The development of the inner ear complex cytoarchitecture and functional geometry requires the exquisite coordination of a variety of cellular processes in a temporal manner. At early stages of inner ear development several rounds of cell proliferation in the otocyst promote the growth of the structure. The apoptotic program is initiated in exceeding cells to adjust cell type numbers. Apoptotic cells are cleared by phagocytic cells that recognize the phosphatidylserine residues exposed in the cell membrane thanks to the energy supplied by autophagy. Specific molecular programs determine hair and supporting cell fate, these populations are responsible for the functions of the adult sensory organ: detection of sound, position and acceleration. The neurons that transmit auditory and balance information to the brain are also born at the otocyst by neurogenesis facilitated by autophagy. Cellular senescence participates in tissue repair, cancer and aging, situations in which cells enter a permanent cell cycle arrest and acquire a highly secretory phenotype that modulates their microenvironment. More recently, senescence has also been proposed to take place during vertebrate development in a limited number of transitory structures and organs; among the later, the endolymphatic duct in the inner ear. Here, we review these cellular processes during the early development of the inner ear, focusing on how the most recently described cellular senescence participates and cooperates with proliferation, apoptosis and autophagy to achieve otic morphogenesis and differentiation.
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Affiliation(s)
- Isabel Varela-Nieto
- Institute for Biomedical Research "Alberto Sols" (IIBM), Spanish National Research Council-Autonomous University of Madrid (CSIC-UAM), Madrid, Spain; Centre for Biomedical Network Research on Rare Diseases (CIBERER), Madrid, Spain; Hospital La Paz Institute for Health Research (IdiPAZ), Madrid, Spain
| | - Ignacio Palmero
- Institute for Biomedical Research "Alberto Sols" (IIBM), Spanish National Research Council-Autonomous University of Madrid (CSIC-UAM), Madrid, Spain
| | - Marta Magariños
- Institute for Biomedical Research "Alberto Sols" (IIBM), Spanish National Research Council-Autonomous University of Madrid (CSIC-UAM), Madrid, Spain; Centre for Biomedical Network Research on Rare Diseases (CIBERER), Madrid, Spain; Biology Department, Faculty of Sciences, Autonomous University of Madrid (UAM), Madrid, Spain.
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3
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Characterization of Lgr5+ progenitor cell transcriptomes in the apical and basal turns of the mouse cochlea. Oncotarget 2018; 7:41123-41141. [PMID: 27070092 PMCID: PMC5173047 DOI: 10.18632/oncotarget.8636] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Accepted: 03/28/2016] [Indexed: 12/11/2022] Open
Abstract
Lgr5+ supporting cells (SCs) are enriched hair cell (HC) progenitors in the cochlea, and several studies have shown a difference in the proliferation and HC regeneration ability of SCs between the apical and basal turns. However, the detailed differences between the transcriptomes of the apical and basal Lgr5+ SCs have not yet been investigated. We found that when isolated by FACS, Lgr5+ cells from the apex generated significantly more HCs and had significantly higher proliferation and mitotic HC regeneration ability compared to those from the base. Next, we used microarray analysis to determine the transcriptome expression profiles of Lgr5+ progenitors from the apex and the base. We first analyzed the genes that were enriched and differentially expressed in Lgr5+ progenitors from the apex and the base. Then we analyzed the cell cycle genes and the transcription factors that might regulate the proliferation and differentiation of Lgr5+ progenitors. Lastly, to further analyze the role of differentially expressed genes and to gain an overall view of the gene network in cochlear HC regeneration, we created a protein-protein interaction network. Our datasets suggest the possible genes that might regulate the proliferation and HC regeneration ability of Lgr5+ progenitors, and these genes might provide new therapeutic targets for HC regeneration in the future.
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4
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García-Alcántara F, Murillo-Cuesta S, Pulido S, Bermúdez-Muñoz JM, Martínez-Vega R, Milo M, Varela-Nieto I, Rivera T. The expression of oxidative stress response genes is modulated by a combination of resveratrol and N-acetylcysteine to ameliorate ototoxicity in the rat cochlea. Hear Res 2017; 358:10-21. [PMID: 29304389 DOI: 10.1016/j.heares.2017.12.004] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/05/2016] [Revised: 09/06/2017] [Accepted: 12/10/2017] [Indexed: 11/19/2022]
Abstract
Aminoglycoside antibiotics are used widely in medicine despite their ototoxic side-effects. Oxidative stress and inflammation are key mechanisms determining the extent and severity of the damage. Here we evaluate the protective effect of a treatment with resveratrol plus N-acetylcysteine on the ototoxic actions of kanamycin and furosemide in the rat. Resveratrol (10 mg/kg) and N-acetylcysteine (400 mg/kg) were administered together to Wistar rats on 5 consecutive days. The second day, a concentrated solution of kanamycin and furosemide was placed on the round window to induce ototoxicity. Hearing was assessed by recording auditory brainstem responses before and 5, 16 and 23 days after the beginning of the treatment. Cochlear samples were taken at day 5 (end of the treatment) and at day 23, and targeted PCR arrays or RT-qPCR were performed to analyze oxidative balance and inflammation related genes, respectively. In addition, the cytoarchitecture and the presence of apoptosis, oxidative stress and inflammation markers were evaluated in cochlear sections. Results indicate that administration of resveratrol plus N-acetylcysteine reduced the threshold shifts induced by ototoxic drugs at high frequencies (≈10 dB), although this protective effect fades after the cessation of the treatment. Gene expression analysis showed that the treatment modulated the expression of genes involved in the cellular oxidative (Gpx1, Sod1, Ccs and Noxa1) and inflammatory (Il1b, Il4, Mpo and Ncf) responses to injury. Thus, co-administration of resveratrol and NAC, routinely used individually in patients, could reduce the ototoxic secondary effects of aminoglycosides.
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Affiliation(s)
- Fernando García-Alcántara
- Príncipe de Asturias University Hospital, Universidad de Alcalá, Carretera Alcalá-Meco s/n, 28805, Alcalá de Henares, Madrid, Spain; Institute of Biomedical Research "Alberto Sols" (IIBM), Spanish National Research Council-Autonomous University of Madrid (CSIC-UAM), Arturo Duperier 4, 28029, Madrid, Spain; Centre for Biomedical Network Research in Rare Diseases (CIBERER), Institute of Health Carlos III (ISCIII), Monforte de Lemos, 3-5, 28029, Madrid, Spain.
| | - Silvia Murillo-Cuesta
- Institute of Biomedical Research "Alberto Sols" (IIBM), Spanish National Research Council-Autonomous University of Madrid (CSIC-UAM), Arturo Duperier 4, 28029, Madrid, Spain; Centre for Biomedical Network Research in Rare Diseases (CIBERER), Institute of Health Carlos III (ISCIII), Monforte de Lemos, 3-5, 28029, Madrid, Spain; Hospital La Paz Institute for Health Research (IdiPAZ), Pedro Rico 6, 28029, Madrid, Spain.
| | - Sara Pulido
- Institute of Biomedical Research "Alberto Sols" (IIBM), Spanish National Research Council-Autonomous University of Madrid (CSIC-UAM), Arturo Duperier 4, 28029, Madrid, Spain; Centre for Biomedical Network Research in Rare Diseases (CIBERER), Institute of Health Carlos III (ISCIII), Monforte de Lemos, 3-5, 28029, Madrid, Spain; Department of Biomedical Science, University of Sheffield, Western Bank, Sheffield, S3 7HF, United Kingdom.
| | - Jose M Bermúdez-Muñoz
- Institute of Biomedical Research "Alberto Sols" (IIBM), Spanish National Research Council-Autonomous University of Madrid (CSIC-UAM), Arturo Duperier 4, 28029, Madrid, Spain; Centre for Biomedical Network Research in Rare Diseases (CIBERER), Institute of Health Carlos III (ISCIII), Monforte de Lemos, 3-5, 28029, Madrid, Spain.
| | - Raquel Martínez-Vega
- Institute of Biomedical Research "Alberto Sols" (IIBM), Spanish National Research Council-Autonomous University of Madrid (CSIC-UAM), Arturo Duperier 4, 28029, Madrid, Spain.
| | - Marta Milo
- Department of Biomedical Science, University of Sheffield, Western Bank, Sheffield, S3 7HF, United Kingdom.
| | - Isabel Varela-Nieto
- Institute of Biomedical Research "Alberto Sols" (IIBM), Spanish National Research Council-Autonomous University of Madrid (CSIC-UAM), Arturo Duperier 4, 28029, Madrid, Spain; Centre for Biomedical Network Research in Rare Diseases (CIBERER), Institute of Health Carlos III (ISCIII), Monforte de Lemos, 3-5, 28029, Madrid, Spain; Hospital La Paz Institute for Health Research (IdiPAZ), Pedro Rico 6, 28029, Madrid, Spain.
| | - Teresa Rivera
- Príncipe de Asturias University Hospital, Universidad de Alcalá, Carretera Alcalá-Meco s/n, 28805, Alcalá de Henares, Madrid, Spain; Institute of Biomedical Research "Alberto Sols" (IIBM), Spanish National Research Council-Autonomous University of Madrid (CSIC-UAM), Arturo Duperier 4, 28029, Madrid, Spain; Centre for Biomedical Network Research in Rare Diseases (CIBERER), Institute of Health Carlos III (ISCIII), Monforte de Lemos, 3-5, 28029, Madrid, Spain.
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5
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Magariños M, Pulido S, Aburto MR, de Iriarte Rodríguez R, Varela-Nieto I. Autophagy in the Vertebrate Inner Ear. Front Cell Dev Biol 2017; 5:56. [PMID: 28603711 PMCID: PMC5445191 DOI: 10.3389/fcell.2017.00056] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2017] [Accepted: 05/09/2017] [Indexed: 12/13/2022] Open
Abstract
Autophagy is a conserved catabolic process that results in the lysosomal degradation of cell components. During development, autophagy is associated with tissue and organ remodeling, and under physiological conditions it is tightly regulated as it plays a housekeeping role in removing misfolded proteins and damaged organelles. The vertebrate inner ear is a complex sensory organ responsible for the perception of sound and for balance. Cell survival, death and proliferation, as well as cell fate specification and differentiation, are processes that are strictly coordinated during the development of the inner ear in order to generate the more than a dozen specialized cell types that constitute this structure. Here, we review the existing evidence that implicates autophagy in the generation of the vertebrate inner ear. At early stages of chicken otic development, inhibiting autophagy impairs neurogenesis and causes aberrant otocyst morphogenesis. Autophagy provides energy for the clearing of dying cells and it favors neuronal differentiation. Moreover, autophagy is required for proper vestibular development in the mouse inner ear. The autophagy-related genes Becn1, Atg4g, Atg5, and Atg9, are expressed in the inner ear from late developmental stages to adulthood, and Atg4b mutants show impaired vestibular behavior associated to defects in otoconial biogenesis that are also common to Atg5 mutants. Autophagic flux appears to be age-regulated, augmenting from perinatal stages to young adulthood in mice. This up-regulation is concomitant with the functional maturation of the hearing receptor. Hence, autophagy can be considered an intracellular pathway fundamental for in vertebrate inner ear development and maturation.
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Affiliation(s)
- Marta Magariños
- Department of Endocrine and Nervous Systems Pathophysiology, Instituto de Investigaciones Biomédicas "Alberto Sols," CSIC-UAMMadrid, Spain.,CIBERER, Unit 761, Instituto de Salud Carlos IIIMadrid, Spain.,Departamento de Biología, Universidad Autónoma de MadridMadrid, Spain
| | - Sara Pulido
- Department of Endocrine and Nervous Systems Pathophysiology, Instituto de Investigaciones Biomédicas "Alberto Sols," CSIC-UAMMadrid, Spain.,CIBERER, Unit 761, Instituto de Salud Carlos IIIMadrid, Spain
| | - María R Aburto
- Department of Endocrine and Nervous Systems Pathophysiology, Instituto de Investigaciones Biomédicas "Alberto Sols," CSIC-UAMMadrid, Spain
| | - Rocío de Iriarte Rodríguez
- Department of Endocrine and Nervous Systems Pathophysiology, Instituto de Investigaciones Biomédicas "Alberto Sols," CSIC-UAMMadrid, Spain
| | - Isabel Varela-Nieto
- Department of Endocrine and Nervous Systems Pathophysiology, Instituto de Investigaciones Biomédicas "Alberto Sols," CSIC-UAMMadrid, Spain.,CIBERER, Unit 761, Instituto de Salud Carlos IIIMadrid, Spain.,Instituto de Investigación Hospital Universitario La Paz (IdiPAZ)Madrid, Spain
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6
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Cheng C, Guo L, Lu L, Xu X, Zhang S, Gao J, Waqas M, Zhu C, Chen Y, Zhang X, Xuan C, Gao X, Tang M, Chen F, Shi H, Li H, Chai R. Characterization of the Transcriptomes of Lgr5+ Hair Cell Progenitors and Lgr5- Supporting Cells in the Mouse Cochlea. Front Mol Neurosci 2017; 10:122. [PMID: 28491023 PMCID: PMC5405134 DOI: 10.3389/fnmol.2017.00122] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2017] [Accepted: 04/11/2017] [Indexed: 12/27/2022] Open
Abstract
Cochlear supporting cells (SCs) have been shown to be a promising resource for hair cell (HC) regeneration in the neonatal mouse cochlea. Previous studies have reported that Lgr5+ SCs can regenerate HCs both in vitro and in vivo and thus are considered to be inner ear progenitor cells. Lgr5+ progenitors are able to regenerate more HCs than Lgr5- SCs, and it is important to understand the mechanism behind the proliferation and HC regeneration of these progenitors. Here, we isolated Lgr5+ progenitors and Lgr5- SCs from Lgr5-EGFP-CreERT2/Sox2-CreERT2/Rosa26-tdTomato mice via flow cytometry. As expected, we found that Lgr5+ progenitors had significantly higher proliferation and HC regeneration ability than Lgr5- SCs. Next, we performed RNA-Seq to determine the gene expression profiles of Lgr5+ progenitors and Lgr5- SCs. We analyzed the genes that were enriched and differentially expressed in Lgr5+ progenitors and Lgr5- SCs, and we found 8 cell cycle genes, 9 transcription factors, and 24 cell signaling pathway genes that were uniquely expressed in one population but not the other. Last, we made a protein–protein interaction network to further analyze the role of these differentially expressed genes. In conclusion, we present a set of genes that might regulate the proliferation and HC regeneration ability of Lgr5+ progenitors, and these might serve as potential new therapeutic targets for HC regeneration.
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Affiliation(s)
- Cheng Cheng
- Key Laboratory for Developmental Genes and Human Disease, Ministry of Education, Institute of Life Sciences, Southeast UniversityNanjing, China.,Research Institute of OtolaryngologyNanjing, China.,Co-innovation Center of Neuroregeneration, Nantong UniversityNantong, China
| | - Luo Guo
- Department of Otorhinolaryngology, Affiliated Eye and ENT Hospital, State Key Laboratory of Medical Neurobiology, Fudan UniversityShanghai, China.,Key Laboratory of Hearing Medicine of National Health and Family Planning CommissionShanghai, China
| | - Ling Lu
- Department of Otolaryngology-Head and Neck Surgery, Nanjing Drum Tower Hospital, Nanjing University Medical SchoolNanjing, China.,Department of Otolaryngology-Head and Neck Surgery, Drum Tower Clinical Medical College of Nanjing Medical UniversityNanjing, China
| | - Xiaochen Xu
- Key Laboratory for Developmental Genes and Human Disease, Ministry of Education, Institute of Life Sciences, Southeast UniversityNanjing, China
| | - ShaSha Zhang
- Key Laboratory for Developmental Genes and Human Disease, Ministry of Education, Institute of Life Sciences, Southeast UniversityNanjing, China
| | - Junyan Gao
- Health Management and Policy, College of Public Health, Saint Louis University, St. LouisMO, USA
| | - Muhammad Waqas
- Key Laboratory for Developmental Genes and Human Disease, Ministry of Education, Institute of Life Sciences, Southeast UniversityNanjing, China.,Department of Biotechnology, Federal Urdu University of Arts, Science and TechnologyGulshan-e-Iqbal, Pakistan
| | - Chengwen Zhu
- Department of Otolaryngology-Head and Neck Surgery, Nanjing Drum Tower Hospital, Nanjing University Medical SchoolNanjing, China
| | - Yan Chen
- Department of Otorhinolaryngology, Affiliated Eye and ENT Hospital, State Key Laboratory of Medical Neurobiology, Fudan UniversityShanghai, China.,Key Laboratory of Hearing Medicine of National Health and Family Planning CommissionShanghai, China
| | - Xiaoli Zhang
- Department of Otolaryngology-Head and Neck Surgery, Nanjing Drum Tower Hospital, Nanjing University Medical SchoolNanjing, China
| | - Chuanying Xuan
- Key Laboratory for Developmental Genes and Human Disease, Ministry of Education, Institute of Life Sciences, Southeast UniversityNanjing, China
| | - Xia Gao
- Department of Otolaryngology-Head and Neck Surgery, Nanjing Drum Tower Hospital, Nanjing University Medical SchoolNanjing, China
| | - Mingliang Tang
- Key Laboratory for Developmental Genes and Human Disease, Ministry of Education, Institute of Life Sciences, Southeast UniversityNanjing, China
| | - Fangyi Chen
- Department of Biomedical Engineering, Southern University of Science and TechnologyShenzhen, China
| | - Haibo Shi
- Department of Otorhinolaryngology Head and Neck Surgery, The Sixth People's Hospital, Shanghai Jiao Tong UniversityShanghai, China
| | - Huawei Li
- Department of Otorhinolaryngology, Affiliated Eye and ENT Hospital, State Key Laboratory of Medical Neurobiology, Fudan UniversityShanghai, China.,Key Laboratory of Hearing Medicine of National Health and Family Planning CommissionShanghai, China.,Institutes of Biomedical Sciences, Fudan UniversityShanghai, China.,Shanghai Engineering Research Centre of Cochlear ImplantShanghai, China
| | - Renjie Chai
- Key Laboratory for Developmental Genes and Human Disease, Ministry of Education, Institute of Life Sciences, Southeast UniversityNanjing, China.,Research Institute of OtolaryngologyNanjing, China.,Co-innovation Center of Neuroregeneration, Nantong UniversityNantong, China
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7
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Magariños M, Aburto MR, Sánchez-Calderón H, Muñoz-Agudo C, Rapp UR, Varela-Nieto I. RAF kinase activity regulates neuroepithelial cell proliferation and neuronal progenitor cell differentiation during early inner ear development. PLoS One 2010; 5:e14435. [PMID: 21203386 PMCID: PMC3010996 DOI: 10.1371/journal.pone.0014435] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2010] [Accepted: 11/24/2010] [Indexed: 12/21/2022] Open
Abstract
Background Early inner ear development requires the strict regulation of cell proliferation, survival, migration and differentiation, coordinated by the concerted action of extrinsic and intrinsic factors. Deregulation of these processes is associated with embryonic malformations and deafness. We have shown that insulin-like growth factor I (IGF-I) plays a key role in embryonic and postnatal otic development by triggering the activation of intracellular lipid and protein kinases. RAF kinases are serine/threonine kinases that regulate the highly conserved RAS-RAF-MEK-ERK signaling cascade involved in transducing the signals from extracellular growth factors to the nucleus. However, the regulation of RAF kinase activity by growth factors during development is complex and still not fully understood. Methodology/Principal Findings By using a combination of qRT-PCR, Western blotting, immunohistochemistry and in situ hybridization, we show that C-RAF and B-RAF are expressed during the early development of the chicken inner ear in specific spatiotemporal patterns. Moreover, later in development B-RAF expression is associated to hair cells in the sensory patches. Experiments in ex vivo cultures of otic vesicle explants demonstrate that the influence of IGF-I on proliferation but not survival depends on RAF kinase activating the MEK-ERK phosphorylation cascade. With the specific RAF inhibitor Sorafenib, we show that blocking RAF activity in organotypic cultures increases apoptosis and diminishes the rate of cell proliferation in the otic epithelia, as well as severely impairing neurogenesis of the acoustic-vestibular ganglion (AVG) and neuron maturation. Conclusions/Significance We conclude that RAF kinase activity is essential to establish the balance between cell proliferation and death in neuroepithelial otic precursors, and for otic neuron differentiation and axonal growth at the AVG.
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Affiliation(s)
- Marta Magariños
- Instituto de Investigaciones Biomédicas Alberto Sols, CSIC-UAM, Madrid, Spain.
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8
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Sanz C, Vázquez P, Blázquez C, Barrio PA, Alvarez MDM, Blázquez E. Signaling and biological effects of glucagon-like peptide 1 on the differentiation of mesenchymal stem cells from human bone marrow. Am J Physiol Endocrinol Metab 2010; 298:E634-43. [PMID: 20040695 DOI: 10.1152/ajpendo.00460.2009] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Glucagon-like peptide 1 (GLP-1) functions as an incretin hormone with antidiabetogenic properties. However, the role of GLP-1 in human bone marrow-derived mesenchymal stem cells (hMSCs), if any, remains unknown. The effects of GLP-1 on hMSCs were tested with regard to cell proliferation, cytoprotection, and cell differentiation into adipocytes. The signaling pathways involved in these processes were also analyzed. Cells were characterized with biochemical and morphological approaches before and after being induced to differentiate into adipocytes. PCNA protein levels were used as a proliferation index, whereas cell apoptosis was studied by deprivation of fetal bovine serum. Isolated hMSCs expressed stem cell markers as well as mRNA and GLP-1 receptor protein. GLP-1 increased the proliferation of hMSCs, which decreased when they were induced to differentiate into adipocytes. This process produced biochemical and morphological changes in cells expressing PPARgamma, C/EBPbeta, AP2, and LPL in a time-dependent pattern. Notably, GLP-1 significantly reduced the expression of PPARgamma, C/EBPbeta, and LPL. These effects were exerted at least through the MEK and PKC signaling pathways. In addition, GLP-1 significantly reduced cell apoptosis. Our data indicate that, in hMSCs, GLP-1 promotes cellular proliferation and cytoprotection and prevents cell differentiation into adipocytes. These latter findings underscore the potential therapeutic role of GLP-1 in preventing the adipocyte hyperplasia associated with obesity and, additionally, could bolster the maintenance of hMSC stores by promoting the proliferation and cytoprotection of undifferentiated hMSC.
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Affiliation(s)
- C Sanz
- Department of Biochemistry and Molecular Biology, Complutense University, Madrid, Spain.
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9
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Conejero L, Higaki Y, Baeza ML, Fernández M, Varela-Nieto I, Zubeldia JM. Pollen-induced airway inflammation, hyper-responsiveness and apoptosis in a murine model of allergy. Clin Exp Allergy 2007; 37:331-8. [PMID: 17359383 DOI: 10.1111/j.1365-2222.2007.02660.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
BACKGROUND Previous studies indicate that murine models are useful tools for studying the allergic diseases, including certain aspects of bronchial asthma such as cellular tissue inflammation and pulmonary function. OBJECTIVE To develop an experimental model of allergic lung inflammation based on a relevant human allergen, olive pollen, and to establish the immunological, cellular and functional airway features of the allergic response in this model. METHODS Induction of systemic allergic response was achieved by the subcutaneous administration of Olea europaea extract in BALB/c mice. Olea-specific Igs (IgG1, IgG2a and IgE) and cytokines from splenocyte cultures IL-4, IL-5 IL-10, IL-13 and IFN-gamma were measured. Allergic airway response was generated by transnasal instillation of the allergens. Airway responsiveness was monitored by non-invasive methacholine inhalation challenge. Lungs were paraffin embedded and histologically analysed. Apoptosis was studied by the TUNEL technique in the lung tissue and through cell cycle analysis by flow cytometry in splenocytes. RESULTS Our results demonstrate that Olea-sensitized mice develop a specific allergic antibody (IgG1 and IgE) and cytokine (IL-4, IL-5, IL-10 and IL-13) response. After transnasal Olea instillation, they show inflammatory infiltration of lung tissue, mucus secretion and non-specific hyper-responsiveness in the airway. Concomitantly, differences in the rate of apoptosis are observed in the lung cells as well as a significant reduction of spontaneous apoptosis in the splenocytes of allergic mice. CONCLUSION We present a novel animal model of olive pollen-allergic disease. This model presents traits associated with human allergic asthma and could be an interesting tool in the study of underlying molecular mechanisms and in exploring the therapeutic approaches to this disease.
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Affiliation(s)
- L Conejero
- Allergy Service and Experimental Medicine Unit, University General Hospital, Gregorio Marañón, Madrid, Spain
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10
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Ribera J, Ayala V, Casas C. Involvement of c-Jun-JNK pathways in the regulation of programmed cell death of developing chick embryo spinal cord motoneurons. Dev Neurosci 2006; 29:438-51. [PMID: 17119319 DOI: 10.1159/000097318] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2006] [Accepted: 08/03/2006] [Indexed: 01/24/2023] Open
Abstract
Key features of developmentally regulated programmed cell death (PCD) have been described for the first time in the chick nervous system. JNK/c-Jun pathway was involved in early events determining normal and pathological neuronal death as shown in experimental models. In the chick embryo, PCD of motoneurons (MNs) in ovo occurs within a well-defined temporal window and can be subjected to experimental manipulation. Taking advantage of this in vivo system, we explored the role of c-Jun and JNK pathway in the regulation of PCD in MNs. By using specific antibodies against phospho-c-Jun (Ser 63, 73) and JNK we demonstrated that before MNs acquire apoptotic phenotype there is an increase in c-Jun. Blockage of neuromuscular activity by the GABA agonist muscimol reduces PCD and diminishes c-Jun immunoreactivity in MNs. Extensive induction of PCD, either due to injection of beta-bungarotoxin or limb bud removal, is also preceded by an increase in c-Jun immunoreactivity that is also associated with upregulation of phospho-c-Jun and JNK. Translocation of JNK from cytoplasm to MN nuclei was also detected. After acute application of beta-bungarotoxin, which is a strong apoptotic stimulus for MNs, c-Jun phosphorylation occurs on serine 73, whereas serine 63 is the main site for c-Jun phosphorylation after limb bud removal. These results demonstrated that the JNK/c-Jun pathway is involved in the decision phase of normal and induced apoptosis in MNs. Pharmacological interventions involving this pathway should be explored as a potential therapeutic target for promoting MN survival.
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Affiliation(s)
- Joan Ribera
- Universitat de Lleida, Facultat de Medicina, Departament de Ciències Mèdiques Bàsiques, Lleida, Spain.
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Kurmasheva RT, Houghton PJ. IGF-I mediated survival pathways in normal and malignant cells. Biochim Biophys Acta Rev Cancer 2006; 1766:1-22. [PMID: 16844299 DOI: 10.1016/j.bbcan.2006.05.003] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2005] [Revised: 05/23/2006] [Accepted: 05/25/2006] [Indexed: 02/07/2023]
Abstract
The type-I and -II insulin-like growth factors (IGF-I, II) are now established as survival- or proliferation-factors in many in vitro systems. Of note IGFs provide trophic support for multiple cell types or organ cultures explanted from various species, and delay the onset of programmed cell death (apoptosis) through the mitochondrial (intrinsic pathway) or by antagonizing activation of cytotoxic cytokine signaling (extrinsic pathway). In some instances, IGFs protect against other forms of death such as necrosis or autophagy. The effect of IGFs on cell survival appears to be context specific, being determined both by the cell origin (tissue specific) and the cellular stress that induces loss of cellular viability. In many human cancers, there is a strong association with dysregulated IGF signaling, and this association has been extensively reviewed recently. IGF-regulation is also disrupted in childhood cancers as a consequence of chromosomal translocations. IGFs are implicated also in acute renal failure, traumatic injury to brain tissue, and cardiac disease. This article focuses on the role of IGFs and their cellular signaling pathways that provide survival signals in stressed cells.
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Affiliation(s)
- Raushan T Kurmasheva
- Department of Molecular Pharmacology, St. Jude Children's Research Hospital, 332 N. Lauderdale St., Memphis, TN 38105-2794, USA
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Pujades C, Kamaid A, Alsina B, Giraldez F. BMP-signaling regulates the generation of hair-cells. Dev Biol 2006; 292:55-67. [PMID: 16458882 DOI: 10.1016/j.ydbio.2006.01.001] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2005] [Revised: 12/22/2005] [Accepted: 01/03/2006] [Indexed: 11/22/2022]
Abstract
Bone morphogenetic proteins (BMPs) are diffusible molecules involved in a variety of cellular interactions during development. Bmp4 expression accompanies the development of the ear sensory organs during patterning and specification of sensory cell fates, yet there is no understanding of the role of BMP4 in this process. The present work was aimed at exploring the effects of BMP-signaling on the development of hair-cells. For this purpose, we studied gene expression, cell proliferation and cell death in isolated chick otic vesicles that were grown in vitro in the presence of recombinant BMP4 or the BMP-inhibitor Noggin. Cath1 was used as a marker for hair-cell specification. BMP4 reduced the number of Cath1-cells and, conversely, Noggin increased the size of the sensory patches and the number of Cath1-positive cells. The effect of BMP4 was irreversible and occurred before hair-cell specification. Lfng and Fgf10 were expressed in the prosensory domain before Cath1, and their expression was expanded by Noggin. At these stages, modifications of BMP activity did not respecify non-sensory epithelium of the otic vesicle. The expression of Bmp4 at sensory patches was suppressed by BMP4 and induced by Noggin suggesting an autoregulatory loop. Analysis of BrdU incorporation during 6 and 18 h indicated that the effects of BMP4 were due to its ability to reduce the number of actively proliferating progenitors and inhibit cell fate specification. BMP4 induced cell death within the prosensory domain of the otic vesicle, along with the expression of Msx1, but not Msx2. On the contrary, BMP-inhibition with Noggin favored hair-cell specification without changes in the overall cell proliferation. We propose that about the stage of terminal division, the balance between BMP and BMP-inhibitory signals regulates survival and specification of hair-cell precursors, the final number of sensory hair-cells being limited by excess levels of BMPs. The final size of sensory patches would hence depend on the balance between BMP4 and opposing signals.
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Affiliation(s)
- Cristina Pujades
- Biologia del Desenvolupament, Departament de Ciències Experimentals i de la Salut (DCEXS), Universitat Pompeu Fabra, Parc de Recerca Biomèdica de Barcelona (PRBB) c/Dr. Aiguader 80, 08003-Barcelona, Spain
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Ahn JH, Kang HH, Kim YJ, Chung JW. Anti-apoptotic role of retinoic acid in the inner ear of noise-exposed mice. Biochem Biophys Res Commun 2005; 335:485-90. [PMID: 16084493 DOI: 10.1016/j.bbrc.2005.07.114] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2005] [Accepted: 07/19/2005] [Indexed: 10/25/2022]
Abstract
Exposure to loud noise can induce temporary or permanent hearing loss, and acoustic trauma is the major cause of hearing impairment in industrial nations. However, the mechanisms underlying the death of hair cells after acoustic trauma remain unclear. In addition to its involvement in cellular stress and apoptosis, the c-Jun N-terminal kinase (JNK), a member of the mitogen-activated protein kinase family, is involved in cell survival, transformation, embryonic morphogenesis, and differentiation. JNK is primarily activated by various environmental stresses including noise, and the phenotypic result appears be to cell death. All-trans retinoic acid (ATRA) is an active metabolite of vitamin A that regulates a wide range of biological processes, including cell proliferation, differentiation, and morphogenesis. We evaluated the role of ATRA in preserving hearing in mice exposed to noise that can induce permanent hearing loss. Mice fed with ATRA before and during 3 consecutive days of noise exposure had a more preserved hearing threshold than mice fed sesame oil or saline. Histological and TUNEL staining of the cochlea showed significantly enhanced preservation of the organ of Corti, including outer hair cells and relatively low apoptotic nuclei, in mice-fed ATRA than in mice-fed sesame oil or saline. Phospho-JNK immunohistochemistry showed that ATRA inhibited the activation of JNK. These results suggest that ATRA has an anti-apoptotic effect on cochleae exposed to noise.
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Affiliation(s)
- Joong Ho Ahn
- Department of Otolaryngology, Asan Medical Center, University of Ulsan, College of Medicine, Seoul, Republic of Korea
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Diaz-Casares A, Leon Y, de la Rosa EJ, Varela-Nieto I. Regulation of Vertebrate Sensory Organ Development: A Scenario for Growth Hormone and Insulin-Like Growth Factors Action. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2005; 567:221-42. [PMID: 16370141 DOI: 10.1007/0-387-26274-1_9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Affiliation(s)
- Amelia Diaz-Casares
- Instituto de Investigaciones Biomedicas Alberto Sols, Consejo Superior de Investigaciones Cientificas-Universidad Autonoma de Madrid, Spain
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Varela-Nieto I, Morales-Garcia JA, Vigil P, Diaz-Casares A, Gorospe I, Sánchez-Galiano S, Cañon S, Camarero G, Contreras J, Cediel R, Leon Y. Trophic effects of insulin-like growth factor-I (IGF-I) in the inner ear. Hear Res 2004; 196:19-25. [PMID: 15464297 DOI: 10.1016/j.heares.2003.12.022] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/19/2003] [Accepted: 12/23/2003] [Indexed: 11/27/2022]
Abstract
Insulin-like growth factors (IGFs) have a pivotal role during nervous system development and in its functional maintenance. IGF-I and its high affinity receptor (IGF1R) are expressed in the developing inner ear and in the postnatal cochlear and vestibular ganglia. We recently showed that trophic support by IGF-I is essential for the early neurogenesis of the chick cochleovestibular ganglion (CVG). In the chicken embryo otic vesicle, IGF-I regulates developmental death dynamics by regulating the activity and/or levels of key intracellular molecules, including lipid and protein kinases such as ceramide kinase, Akt and Jun N-terminal kinase (JNK). Mice lacking IGF-I lose many auditory neurons and present increased auditory thresholds at early postnatal ages. Neuronal loss associated to IGF-I deficiency is caused by apoptosis of the auditory neurons, which presented abnormally increased levels of activated caspase-3. It is worth noting that in man, homozygous deletion of the IGF-1 gene causes sensory-neural deafness. IGF-I is thus necessary for normal development and maintenance of the inner ear. The trophic actions of IGF-I in the inner ear suggest that this factor may have therapeutic potential for the treatment of hearing loss.
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Affiliation(s)
- Isabel Varela-Nieto
- Instituto de Investigaciones Biomedicas Alberto Sols, Consejo Superior de Investigaciones Cientificas, Universidad Autónoma de Madrid, "Alberto Sols", Arturo Duperier 4, 28029 Madrid, Spain.
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Frago LM, Cañón S, de la Rosa EJ, León Y, Varela-Nieto I. Programmed cell death in the developing inner ear is balanced by nerve growth factor and insulin-like growth factor I. J Cell Sci 2003; 116:475-86. [PMID: 12508109 DOI: 10.1242/jcs.00223] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Nerve growth factor induces cell death in organotypic cultures of otic vesicle explants. This cell death has a restricted pattern that reproduces the in vivo pattern of apoptosis occurring during inner ear development. In this study, we show that binding of nerve growth factor to its low affinity p75 neurotrophin receptor is essential to achieve the apoptotic response. Blockage of binding to p75 receptor neutralized nerve-growth-factor-induced cell death, as measured by immunoassays detecting the presence of cytosolic oligonucleosomes and by TUNEL assay to visualize DNA fragmentation. Nerve growth factor also induced a number of cell-death-related intracellular events including ceramide generation, caspase activation and poly-(ADP ribose) polymerase cleavage. Again, p75 receptor blockade completely abolished all of these effects. Concerning the intracellular pathway, ceramide increase depended on initiator caspases, whereas its actions depended on both initiator and effector caspases, as shown by using site-specific caspase inhibitors. Conversely, insulin-like growth factor I, which promotes cell growth and survival in the inner ear, abolished apoptosis induced by nerve growth factor. Insulin-like growth factor cytoprotective actions were accomplished, at least in part, by decreasing endogenous ceramide levels and activating Akt. Taken together, these results strongly suggest that regulation of nerve-growth-factor-induced apoptosis in the otocysts occurs via p75 receptor binding and is strictly controlled by the interaction with survival signalling pathways.
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Affiliation(s)
- Laura M Frago
- Instituto de Investigaciones Biomédicas "Alberto Sols", Consejo Superior de Investigaciones Científicas-Universidad Autónoma de Madrid (CSIC-UAM), Arturo Duperier 4, 28029 Madrid, Spain
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Alsina B, Giraldez F, Varela-Nieto I. Growth Factors and Early Development of Otic Neurons: Interactions between Intrinsic and Extrinsic Signals. Curr Top Dev Biol 2003; 57:177-206. [PMID: 14674481 DOI: 10.1016/s0070-2153(03)57006-5] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Affiliation(s)
- Berta Alsina
- DCEXS-Universitat Pomepu Fabra, Dr Aiguader 80, 08003 Barcelona, Spain
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Li L, Liu L, Rao JN, Esmaili A, Strauch ED, Bass BL, Wang JY. JunD stabilization results in inhibition of normal intestinal epithelial cell growth through P21 after polyamine depletion. Gastroenterology 2002; 123:764-79. [PMID: 12198703 DOI: 10.1053/gast.2002.35386] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
BACKGROUND & AIMS Normal intestinal mucosal growth requires cellular polyamines that regulate expression of various genes involved in cell proliferation, growth arrest, and apoptosis. We have recently shown that growth inhibition after polyamine depletion is associated with an increase in JunD/AP-1 activity in normal intestinal epithelial cells (IEC-6 line). The current study tests the hypothesis that polyamine depletion-induced JunD/activator protein 1 (AP-1) activity results from the activation of junD gene expression and plays a critical role in regulation of intestinal epithelial cell growth. METHODS The junD gene transcription was examined by nuclear run-on assays, and messenger RNA (mRNA) stability was measured by determination of JunD mRNA half-life. Functions of JunD were investigated by using JunD antisense oligodeoxyribonucleotides and transient transfection with the junD-expressing vector. RESULTS Depletion of cellular polyamines by DL-alpha-difluoromethylornithine (DFMO) induced levels of JunD mRNA and protein, which was associated with an increase in G(1) phase growth arrest. Polyamine depletion did not increase the rate of junD gene transcription but significantly increased the stability of JunD mRNA. Decreasing JunD protein by using JunD antisense oligomers promoted cell growth in polyamine-deficient cells. Growth arrest following polyamine depletion also was accompanied by increases in both p21 expression and its promoter activity. Treatment with JunD antisense oligomers inhibited the p21 promoter and prevented the increase in p21 expression in the presence of DFMO. Ectopic expression of the wild-type junD increased p21-promoter activity and inhibited epithelial cell growth. CONCLUSIONS Polyamines negatively regulate junD gene expression posttranscriptionally, and increased JunD/AP-1 inhibits intestinal epithelial cell proliferation at least partially through the activation of p21 promoter.
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Affiliation(s)
- Li Li
- Department of Surgery, University of Maryland School of Medicine, Baltimore, USA
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Camarero G, Villar MA, Contreras J, Fernández-Moreno C, Pichel JG, Avendaño C, Varela-Nieto I. Cochlear abnormalities in insulin-like growth factor-1 mouse mutants. Hear Res 2002; 170:2-11. [PMID: 12208536 DOI: 10.1016/s0378-5955(02)00447-1] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Insulin-like growth factor 1 (IGF-1) modulates inner ear cell proliferation, differentiation and survival in culture. Its function in human hearing was first evidenced by a report of a boy with a homozygous deletion of the Igf-1 gene, who showed severe sensorineural deafness [Woods et al., New Engl. J. Med. 335 (1996) 1363-1367]. To better understand the in vivo role of IGF-1 during inner ear differentiation and maturation, we studied the cochleae of Igf-1 gene knockout mice by performing morphometric stereological analyses, immunohistochemistry and electron microscopy on postnatal days 5 (P5), P8 and P20. At P20, but not at P5, the volumes of the cochlea and cochlear ganglion were significantly reduced in mutant mice, although the reduction was less severe than whole body dwarfism. A significant decrease in the number and average size of auditory neurons was also evident at P20. IGF-1-deficient cochlear neurons showed increased apoptosis, along with altered expression of neurofilament 200 kDa and vimentin. The eighth nerve, the cochlear ganglion and the fibers innervating the sensory cells of the organ of Corti of the P20 mouse mutants presented increased expression of vimentin, whereas the expression of neurofilament was decreased. In addition, the myelin sheath was severely affected in ganglion neurons. In conclusion, IGF-1 deficit in mice severely affects postnatal survival, differentiation and maturation of the cochlear ganglion cells.
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Affiliation(s)
- Guadalupe Camarero
- Instituto de Investigaciones Biomédicas Alberto Sols, Consejo Superior de Investigaciones Científicas-Universidad Autónoma de Madrid, Arturo Duperier 4, 28029, Madrid, Spain
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Nishikawa S. Localization of transcription factor AP-1 family proteins in ameloblast nuclei of the rat incisor. J Histochem Cytochem 2000; 48:1511-20. [PMID: 11036094 DOI: 10.1177/002215540004801108] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
We examined by immunocytochemistry the localization of the AP-1 family proteins c-Jun, JunB, JunD, c-Fos, FosB, Fra-1, and Fra-2 in rat incisor ameloblasts. Most of the antibodies against AP-1 family proteins, except for c-Fos-specific antibody, labeled ameloblast nuclei. The labeling intensity of the c-Jun, JunD, and Fra-2 antibodies was stronger than that of JunB, FosB, and Fra-1. Antibody reactivities of c-Jun, JunD, and Fra-2 were greatly enhanced during or after the transition zone. Furthermore, c-Jun antibodies labeled maturation ameloblasts in a cyclic pattern, which was correlated with ameloblast modulation. Disruption of ameloblast modulation by colchicine injection resulted in greatly decreased reactivity of the c-Jun antibody in the ameloblast nuclei of the maturation zone. Phospho-specific antibodies to c-Jun labeled ameloblast nuclei only weakly throughout the secretion, transition, and maturation zones. These results suggest that the stage-specific localization of AP-1 in ameloblasts is closely related to tooth enamel formation.
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Affiliation(s)
- S Nishikawa
- Department of Biology, Tsurumi University School of Dental Medicine, Yokohama, Japan.
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