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Diana D, Pirone L, Russo L, D'Abrosca G, Madheswaran M, Benfante R, Di Lascio S, Caldinelli L, Fornasari D, Acconcia C, Corvino A, Ventserova N, Pollegioni L, Isernia C, Di Gaetano S, Malgieri G, Pedone EM, Fattorusso R. Structural characterization of PHOX2B and its DNA interaction shed light on the molecular basis of the +7Ala variant pathogenicity in CCHS. Chem Sci 2024; 15:8858-8872. [PMID: 38873078 PMCID: PMC11168103 DOI: 10.1039/d3sc06427a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Accepted: 04/12/2024] [Indexed: 06/15/2024] Open
Abstract
An expansion of poly-alanine up to +13 residues in the C-terminus of the transcription factor PHOX2B underlies the onset of congenital central hypoventilation syndrome (CCHS). Recent studies demonstrated that the alanine tract expansion influences PHOX2B folding and activity. Therefore, structural information on PHOX2B is an important target for obtaining clues to elucidate the insurgence of the alanine expansion-related syndrome and also for defining a viable therapy. Here we report by NMR spectroscopy the structural characterization of the homeodomain (HD) of PHOX2B and HD + C-terminus PHOX2B protein, free and in the presence of the target DNA. The obtained structural data are then exploited to obtain a structural model of the PHOX2B-DNA interaction. In addition, the variant +7Ala, responsible for one of the most frequent forms of the syndrome, was analysed, showing different conformational proprieties in solution and a strong propensity to aggregation. Our data suggest that the elongated poly-alanine tract would be related to disease onset through a loss-of-function mechanism. Overall, this study paves the way for the future rational design of therapeutic drugs, suggesting as a possible therapeutic route the use of specific anti-aggregating molecules capable of preventing variant aggregation and possibly restoring the DNA-binding activity of PHOX2B.
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Affiliation(s)
- Donatella Diana
- CNR - Institute of Biostructures and Bioimaging Via Pietro Castellino 111 80131 Naples Italy
| | - Luciano Pirone
- CNR - Institute of Biostructures and Bioimaging Via Pietro Castellino 111 80131 Naples Italy
| | - Luigi Russo
- Department of Environmental, Biological and Pharmaceutical Sciences and Technologies - University of Campania "Luigi Vanvitelli" Via Vivaldi 43 81100 Caserta Italy
| | - Gianluca D'Abrosca
- Department of Clinical and Experimental Medicine - University of Foggia Viale Luigi Pinto 71122 Foggia Italy
| | - Manoj Madheswaran
- Department of Environmental, Biological and Pharmaceutical Sciences and Technologies - University of Campania "Luigi Vanvitelli" Via Vivaldi 43 81100 Caserta Italy
| | - Roberta Benfante
- Department of Medical Biotechnology and Translational Medicine (BIOMETRA), Università degli Studi di Milano Milan Italy
- CNR - Institute of Neuroscience Vedano Al Lambro (MB) Italy
- NeuroMi - Milan Center for Neuroscience, University of Milano Bicocca Milan Italy
| | - Simona Di Lascio
- Department of Medical Biotechnology and Translational Medicine (BIOMETRA), Università degli Studi di Milano Milan Italy
| | - Laura Caldinelli
- Department of Biotechnology and Life Sciences, University of Insubria Via J.H. Dunant 3 21100 Varese Italy
| | - Diego Fornasari
- Department of Medical Biotechnology and Translational Medicine (BIOMETRA), Università degli Studi di Milano Milan Italy
| | - Clementina Acconcia
- Department of Environmental, Biological and Pharmaceutical Sciences and Technologies - University of Campania "Luigi Vanvitelli" Via Vivaldi 43 81100 Caserta Italy
| | - Andrea Corvino
- Department of Environmental, Biological and Pharmaceutical Sciences and Technologies - University of Campania "Luigi Vanvitelli" Via Vivaldi 43 81100 Caserta Italy
| | - Nataliia Ventserova
- Department of Environmental, Biological and Pharmaceutical Sciences and Technologies - University of Campania "Luigi Vanvitelli" Via Vivaldi 43 81100 Caserta Italy
| | - Loredano Pollegioni
- Department of Biotechnology and Life Sciences, University of Insubria Via J.H. Dunant 3 21100 Varese Italy
| | - Carla Isernia
- Department of Environmental, Biological and Pharmaceutical Sciences and Technologies - University of Campania "Luigi Vanvitelli" Via Vivaldi 43 81100 Caserta Italy
| | - Sonia Di Gaetano
- CNR - Institute of Biostructures and Bioimaging Via Pietro Castellino 111 80131 Naples Italy
| | - Gaetano Malgieri
- Department of Environmental, Biological and Pharmaceutical Sciences and Technologies - University of Campania "Luigi Vanvitelli" Via Vivaldi 43 81100 Caserta Italy
| | - Emilia M Pedone
- CNR - Institute of Biostructures and Bioimaging Via Pietro Castellino 111 80131 Naples Italy
| | - Roberto Fattorusso
- Department of Environmental, Biological and Pharmaceutical Sciences and Technologies - University of Campania "Luigi Vanvitelli" Via Vivaldi 43 81100 Caserta Italy
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2
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Cardani S, Janes TA, Betzner W, Pagliardini S. Knockdown of PHOX2B in the retrotrapezoid nucleus reduces the central CO 2 chemoreflex in rats. eLife 2024; 13:RP94653. [PMID: 38727716 PMCID: PMC11087052 DOI: 10.7554/elife.94653] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/12/2024] Open
Abstract
PHOX2B is a transcription factor essential for the development of different classes of neurons in the central and peripheral nervous system. Heterozygous mutations in the PHOX2B coding region are responsible for the occurrence of Congenital Central Hypoventilation Syndrome (CCHS), a rare neurological disorder characterised by inadequate chemosensitivity and life-threatening sleep-related hypoventilation. Animal studies suggest that chemoreflex defects are caused in part by the improper development or function of PHOX2B expressing neurons in the retrotrapezoid nucleus (RTN), a central hub for CO2 chemosensitivity. Although the function of PHOX2B in rodents during development is well established, its role in the adult respiratory network remains unknown. In this study, we investigated whether reduction in PHOX2B expression in chemosensitive neuromedin-B (NMB) expressing neurons in the RTN altered respiratory function. Four weeks following local RTN injection of a lentiviral vector expressing the short hairpin RNA (shRNA) targeting Phox2b mRNA, a reduction of PHOX2B expression was observed in Nmb neurons compared to both naive rats and rats injected with the non-target shRNA. PHOX2B knockdown did not affect breathing in room air or under hypoxia, but ventilation was significantly impaired during hypercapnia. PHOX2B knockdown did not alter Nmb expression but it was associated with reduced expression of both Task2 and Gpr4, two CO2/pH sensors in the RTN. We conclude that PHOX2B in the adult brain has an important role in CO2 chemoreception and reduced PHOX2B expression in CCHS beyond the developmental period may contribute to the impaired central chemoreflex function.
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Affiliation(s)
- Silvia Cardani
- Department of Physiology, Faculty of Medicine and Dentistry, University of AlbertaEdmontonCanada
- Women and Children’s Health Research Institute, University of AlbertaEdmontonCanada
| | - Tara A Janes
- Department of Physiology, Faculty of Medicine and Dentistry, University of AlbertaEdmontonCanada
- Women and Children’s Health Research Institute, University of AlbertaEdmontonCanada
| | - William Betzner
- Department of Physiology, Faculty of Medicine and Dentistry, University of AlbertaEdmontonCanada
| | - Silvia Pagliardini
- Department of Physiology, Faculty of Medicine and Dentistry, University of AlbertaEdmontonCanada
- Women and Children’s Health Research Institute, University of AlbertaEdmontonCanada
- Neuroscience and Mental Health Institute, University of AlbertaEdmontonCanada
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3
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Antón R, Treviño MÁ, Pantoja-Uceda D, Félix S, Babu M, Cabrita EJ, Zweckstetter M, Tinnefeld P, Vera AM, Oroz J. Alternative low-populated conformations prompt phase transitions in polyalanine repeat expansions. Nat Commun 2024; 15:1925. [PMID: 38431667 PMCID: PMC10908835 DOI: 10.1038/s41467-024-46236-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2023] [Accepted: 02/19/2024] [Indexed: 03/05/2024] Open
Abstract
Abnormal trinucleotide repeat expansions alter protein conformation causing malfunction and contribute to a significant number of incurable human diseases. Scarce structural insights available on disease-related homorepeat expansions hinder the design of effective therapeutics. Here, we present the dynamic structure of human PHOX2B C-terminal fragment, which contains the longest polyalanine segment known in mammals. The major α-helical conformation of the polyalanine tract is solely extended by polyalanine expansions in PHOX2B, which are responsible for most congenital central hypoventilation syndrome cases. However, polyalanine expansions in PHOX2B additionally promote nascent homorepeat conformations that trigger length-dependent phase transitions into solid condensates that capture wild-type PHOX2B. Remarkably, HSP70 and HSP90 chaperones specifically seize PHOX2B alternative conformations preventing phase transitions. The precise observation of emerging polymorphs in expanded PHOX2B postulates unbalanced phase transitions as distinct pathophysiological mechanisms in homorepeat expansion diseases, paving the way towards the search of therapeutics modulating biomolecular condensates in central hypoventilation syndrome.
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Affiliation(s)
- Rosa Antón
- Instituto de Química Física Blas Cabrera (IQF), CSIC, E-28006, Madrid, Spain
| | - Miguel Á Treviño
- Instituto de Química Física Blas Cabrera (IQF), CSIC, E-28006, Madrid, Spain
| | - David Pantoja-Uceda
- Instituto de Química Física Blas Cabrera (IQF), CSIC, E-28006, Madrid, Spain
| | - Sara Félix
- Associate Laboratory i4HB - Institute for Health and Bioeconomy, NOVA School of Science and Technology, Universidade NOVA de Lisboa, 2819-516, Caparica, Portugal
- UCIBIO, Department of Chemistry, NOVA School of Science and Technology, Universidade NOVA de Lisboa, 2819-516, Caparica, Portugal
| | - María Babu
- German Center for Neurodegenerative Diseases (DZNE), 37075, Göttingen, Germany
| | - Eurico J Cabrita
- Associate Laboratory i4HB - Institute for Health and Bioeconomy, NOVA School of Science and Technology, Universidade NOVA de Lisboa, 2819-516, Caparica, Portugal
- UCIBIO, Department of Chemistry, NOVA School of Science and Technology, Universidade NOVA de Lisboa, 2819-516, Caparica, Portugal
| | - Markus Zweckstetter
- German Center for Neurodegenerative Diseases (DZNE), 37075, Göttingen, Germany
- Department for NMR-based Structural Biology, Max Planck Institute for Multidisciplinary Sciences, 37077, Göttingen, Germany
| | - Philip Tinnefeld
- Department of Chemistry and Center for NanoScience, Ludwig-Maximilians-Universität München, München, 81377, Germany
| | - Andrés M Vera
- Department of Chemistry and Center for NanoScience, Ludwig-Maximilians-Universität München, München, 81377, Germany
| | - Javier Oroz
- Instituto de Química Física Blas Cabrera (IQF), CSIC, E-28006, Madrid, Spain.
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4
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Nakamura-Utsunomiya A, Yamaguchi K, Goshima N. Anti-ZSCAN1 Autoantibodies Are a Feasible Diagnostic Marker for ROHHAD Syndrome Not Associated with a Tumor. Int J Mol Sci 2024; 25:1794. [PMID: 38339072 PMCID: PMC10855538 DOI: 10.3390/ijms25031794] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2023] [Revised: 01/28/2024] [Accepted: 01/30/2024] [Indexed: 02/12/2024] Open
Abstract
Recent studies have reported the presence of autoantibodies against zinc finger and SCAN domain-containing protein 1 (ZSCAN1) in the sera of patients with rapid-onset obesity with hypoventilation, hypothalamic and autonomic dysregulation (ROHHAD) syndrome associated with neuroendocrine tumors, suggesting immunologic and paraneoplastic processes as the pathologic underpinnings. Moreover, several hypothalamic regions, including the subfornical organ (SFO), were reported to exhibit antibody reactivity in a patient with ROHHAD syndrome not associated with a tumor. Whether ROHHAD syndrome not associated with a tumor is associated with anti-ZSCAN1 autoantibodies remains unclear. We used a comprehensive protein array analysis to identify candidate molecules in the sera of patients with ROHHAD syndrome and identified ZSCAN1 as a target antigen. We also found that ZSCAN1 was co-expressed at the site of antibody reactivity to the IgG in the patient serum observed in mouse SFOs and an enzyme-linked immunosorbent assay showed that >85% of the patients with ROHHAD syndrome were positive for anti-ZSCAN1 autoantibodies. These results suggest anti-ZSCAN1 autoantibodies as a feasible diagnostic marker in ROHHAD syndrome regardless of the presence of a tumor.
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Affiliation(s)
- Akari Nakamura-Utsunomiya
- Department of Pediatrics/Medical Genetics, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima 734-8551, Japan
- Department of Pediatrics, Hiroshima Medical Center, Asa Citizens Hospital, Hiroshima 731-0293, Japan
- Division of Neonatal Screening, National Center for Child Health and Development, Tokyo 157-8535, Japan
| | - Kei Yamaguchi
- Molecular Profiling Research Center for Drug Discovery, National Institute of Advanced Industrial Science and Technology, Tokyo 135-0064, Japan
- ProteoBridge Corporation, Tokyo 135-0064, Japan
| | - Naoki Goshima
- Molecular Profiling Research Center for Drug Discovery, National Institute of Advanced Industrial Science and Technology, Tokyo 135-0064, Japan
- ProteoBridge Corporation, Tokyo 135-0064, Japan
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5
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Etonogestrel Administration Reduces the Expression of PHOX2B and Its Target Genes in the Solitary Tract Nucleus. Int J Mol Sci 2022; 23:ijms23094816. [PMID: 35563209 PMCID: PMC9101578 DOI: 10.3390/ijms23094816] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2022] [Revised: 04/15/2022] [Accepted: 04/20/2022] [Indexed: 11/17/2022] Open
Abstract
Heterozygous mutations of the transcription factor PHOX2B are responsible for Congenital Central Hypoventilation Syndrome, a neurological disorder characterized by inadequate respiratory response to hypercapnia and life-threatening hypoventilation during sleep. Although no cure is currently available, it was suggested that a potent progestin drug provides partial recovery of chemoreflex response. Previous in vitro data show a direct molecular link between progestins and PHOX2B expression. However, the mechanism through which these drugs ameliorate breathing in vivo remains unknown. Here, we investigated the effects of chronic administration of the potent progestin drug Etonogestrel (ETO) on respiratory function and transcriptional activity in adult female rats. We assessed respiratory function with whole-body plethysmography and measured genomic changes in brain regions important for respiratory control. Our results show that ETO reduced metabolic activity, leading to an enhanced chemoreflex response and concurrent increased breathing cycle variability at rest. Furthermore, ETO-treated brains showed reduced mRNA and protein expression of PHOX2B and its target genes selectively in the dorsal vagal complex, while other areas were unaffected. Histological analysis suggests that changes occurred in the solitary tract nucleus (NTS). Thus, we propose that the NTS, rich in both progesterone receptors and PHOX2B, is a good candidate for ETO-induced respiratory modulation.
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6
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Ceccherini I, Kurek KC, Weese-Mayer DE. Developmental disorders affecting the respiratory system: CCHS and ROHHAD. HANDBOOK OF CLINICAL NEUROLOGY 2022; 189:53-91. [PMID: 36031316 DOI: 10.1016/b978-0-323-91532-8.00005-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Rapid-onset Obesity with Hypothalamic dysfunction, Hypoventilation, and Autonomic Dysregulation (ROHHAD) and Congenital Central Hypoventilation Syndrome (CCHS) are ultra-rare distinct clinical disorders with overlapping symptoms including altered respiratory control and autonomic regulation. Although both disorders have been considered for decades to be on the same spectrum with necessity of artificial ventilation as life-support, recent acquisition of specific knowledge concerning the genetic basis of CCHS coupled with an elusive etiology for ROHHAD have definitely established that the two disorders are different. CCHS is an autosomal dominant neurocristopathy characterized by alveolar hypoventilation resulting in hypoxemia/hypercarbia and features of autonomic nervous system dysregulation (ANSD), with presentation typically in the newborn period. It is caused by paired-like homeobox 2B (PHOX2B) variants, with known genotype-phenotype correlation but pathogenic mechanism(s) are yet unknown. ROHHAD is characterized by rapid weight gain, followed by hypothalamic dysfunction, then hypoventilation followed by ANSD, in seemingly normal children ages 1.5-7 years. Postmortem neuroanatomical studies, thorough clinical characterization, pathophysiological assessment, and extensive genetic inquiry have failed to identify a cause attributable to a traditional genetic basis, somatic mosaicism, epigenetic mechanism, environmental trigger, or other. To find the key to the ROHHAD pathogenesis and to improve its clinical management, in the present chapter, we have carefully compared CCHS and ROHHAD.
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Affiliation(s)
- Isabella Ceccherini
- Laboratory of Genetics and Genomics of Rare Diseases, IRCCS Istituto Giannina Gaslini, Genova, Italy
| | - Kyle C Kurek
- Department of Pathology & Laboratory Medicine, University of Calgary, Calgary, AB, Canada
| | - Debra E Weese-Mayer
- Division of Autonomic Medicine, Department of Pediatrics, Ann & Robert H Lurie Children's Hospital of Chicago and Stanley Manne Children's Research Institute; and Department of Pediatrics, Northwestern University Feinberg School of Medicine, Chicago, IL, United States.
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7
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Perri P, Ponzoni M, Corrias MV, Ceccherini I, Candiani S, Bachetti T. A Focus on Regulatory Networks Linking MicroRNAs, Transcription Factors and Target Genes in Neuroblastoma. Cancers (Basel) 2021; 13:5528. [PMID: 34771690 PMCID: PMC8582685 DOI: 10.3390/cancers13215528] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Revised: 10/26/2021] [Accepted: 10/28/2021] [Indexed: 12/17/2022] Open
Abstract
Neuroblastoma (NB) is a tumor of the peripheral sympathetic nervous system that substantially contributes to childhood cancer mortality. NB originates from neural crest cells (NCCs) undergoing a defective sympathetic neuronal differentiation and although the starting events leading to the development of NB remain to be fully elucidated, the master role of genetic alterations in key oncogenes has been ascertained: (1) amplification and/or over-expression of MYCN, which is strongly associated with tumor progression and invasion; (2) activating mutations, amplification and/or over-expression of ALK, which is involved in tumor initiation, angiogenesis and invasion; (3) amplification and/or over-expression of LIN28B, promoting proliferation and suppression of neuroblast differentiation; (4) mutations and/or over-expression of PHOX2B, which is involved in the regulation of NB differentiation, stemness maintenance, migration and metastasis. Moreover, altered microRNA (miRNA) expression takes part in generating pathogenetic networks, in which the regulatory loops among transcription factors, miRNAs and target genes lead to complex and aberrant oncogene expression that underlies the development of a tumor. In this review, we have focused on the circuitry linking the oncogenic transcription factors MYCN and PHOX2B with their transcriptional targets ALK and LIN28B and the tumor suppressor microRNAs let-7, miR-34 and miR-204, which should act as down-regulators of their expression. We have also looked at the physiologic role of these genetic and epigenetic determinants in NC development, as well as in terminal differentiation, with their pathogenic dysregulation leading to NB oncogenesis.
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Affiliation(s)
- Patrizia Perri
- Laboratory of Experimental Therapies in Oncology, IRCCS Istituto Giannina Gaslini, 16147 Genoa, Italy; (M.P.); (M.V.C.)
| | - Mirco Ponzoni
- Laboratory of Experimental Therapies in Oncology, IRCCS Istituto Giannina Gaslini, 16147 Genoa, Italy; (M.P.); (M.V.C.)
| | - Maria Valeria Corrias
- Laboratory of Experimental Therapies in Oncology, IRCCS Istituto Giannina Gaslini, 16147 Genoa, Italy; (M.P.); (M.V.C.)
| | - Isabella Ceccherini
- Laboratory of Genetics and Genomics of Rare Diseases, IRCCS Istituto Giannina Gaslini, 16147 Genoa, Italy;
| | - Simona Candiani
- Department of Earth, Environment and Life Sciences, University of Genoa, 16132 Genoa, Italy;
| | - Tiziana Bachetti
- Laboratory of Genetics and Genomics of Rare Diseases, IRCCS Istituto Giannina Gaslini, 16147 Genoa, Italy;
- Department of Earth, Environment and Life Sciences, University of Genoa, 16132 Genoa, Italy;
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8
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Khorasanian R, Mojbafan M, Khosravi N. Genetic study of a patient with congenital central hypoventilation syndrome in Iran: a case report. Mol Biol Rep 2021; 48:8239-8243. [PMID: 34626313 DOI: 10.1007/s11033-021-06746-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2021] [Accepted: 10/01/2021] [Indexed: 11/26/2022]
Abstract
BACKGROUND Congenital central hypoventilation syndrome (CCHS) is an extremely rare genetic disorder characterized by Autonomic nervous system dysregulation caused by mutations in the PHOX2B gene. Here we introduce the first genetic analysis of a one-month-old CCHS baby girl in Iran. METHODS AND RESULTS Genetic analysis of the PHOX2B gene was performed by Sanger sequencing and interpreted using the American College of Medical Genetics and Genomics (ACMG) guideline. The results showed a heterozygous duplication in exon 3, causing a polyalanine repeat expansion mutation to 27 repeats in thePHOX2B gene (20/27 genotype).The patient's parents did not demonstrate this mutation on genetic studies. CONCLUSIONS According to the ACMG guideline, the mutation is pathogenic, and it was a denovo mutation in the family. The genetic study can help the family for prenatal diagnosis or pre-implantation diagnosis if the parents have gonadal mosaicism.
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Affiliation(s)
- Reihaneh Khorasanian
- Department of Medical Genetics and Molecular Biology, Faculty of Medicine, Iran University of Medical Sciences (IUMS), Shahid Hemmat Highway, Tehran, Iran
- Student Research Committee, Faculty of Medicine, Iran University of Medical Sciences, Tehran, Iran
| | - Marzieh Mojbafan
- Department of Medical Genetics and Molecular Biology, Faculty of Medicine, Iran University of Medical Sciences (IUMS), Shahid Hemmat Highway, Tehran, Iran.
- Department of Medical Genetics, Ali-Asghar Children's Hospital, Zafar St., Shahid Modarres Highway, Tehran, Iran.
| | - Nastaran Khosravi
- Division of Neonatology, Ali-Asghar Children Hospital, Iran University of Medical Sciences, Tehran, Iran
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9
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Chang DF, Gilliam EA, Nucho LMA, Garcia J, Shevchenko Y, Zuber SM, Squillaro AI, Maselli KM, Huang S, Spence JR, Grikscheit TC. NH 2-terminal deletion of specific phosphorylation sites on PHOX2B disrupts the formation of enteric neurons in vivo. Am J Physiol Gastrointest Liver Physiol 2021; 320:G1054-G1066. [PMID: 33881351 DOI: 10.1152/ajpgi.00073.2021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Mutations in the paired-like homeobox 2 b (PHOX2B) gene are associated with congenital central hypoventilation syndrome (CCHS), which is a rare condition in which both autonomic dysregulation with hypoventilation and an enteric neuropathy may occur. The majority of patients with CCHS have a polyalanine repeat mutation (PARM) in PHOX2B, but a minority of patients have nonpolyalanine repeat mutations (NPARMs), some of which have been localized to exon 1. A PHOX2B-Y14X nonsense mutation previously generated in a human pluripotent stem cell (hPSC) line results in an NH2-terminus truncated product missing the first 17 or 20 amino acids, possibly due to translational reinitiation at an alternate ATG start site. This NH2-terminal truncation in the PHOX2B protein results in the loss of two key phosphorylation residues. Though the deletion does not affect the potential for PHOX2BY14X/Y14X mutant hPSC to differentiate into enteric neural crest cells (ENCCs) in culture, it impedes in vivo development of neurons in an in vivo model of human aganglionic small intestine.NEW & NOTEWORTHY A mutation that affects only 17-20 NH2-terminal amino acids in the paired-like homeobox 2 b (PHOX2B) gene hinders the subsequent in vivo establishment of intestinal neuronal cells, but not the in vitro differentiation of these cells.
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Affiliation(s)
- David F Chang
- Developmental Biology and Regenerative Medicine Program, The Saban Research Institute, Children's Hospital Los Angeles, Los Angeles, California
| | - Elizabeth A Gilliam
- Developmental Biology and Regenerative Medicine Program, The Saban Research Institute, Children's Hospital Los Angeles, Los Angeles, California
| | - Laura-Marie A Nucho
- Developmental Biology and Regenerative Medicine Program, The Saban Research Institute, Children's Hospital Los Angeles, Los Angeles, California
| | - Jazmin Garcia
- Developmental Biology and Regenerative Medicine Program, The Saban Research Institute, Children's Hospital Los Angeles, Los Angeles, California
| | - Yevheniya Shevchenko
- Developmental Biology and Regenerative Medicine Program, The Saban Research Institute, Children's Hospital Los Angeles, Los Angeles, California
| | - Samuel M Zuber
- Developmental Biology and Regenerative Medicine Program, The Saban Research Institute, Children's Hospital Los Angeles, Los Angeles, California
| | - Anthony I Squillaro
- Developmental Biology and Regenerative Medicine Program, The Saban Research Institute, Children's Hospital Los Angeles, Los Angeles, California
| | - Kathryn M Maselli
- Developmental Biology and Regenerative Medicine Program, The Saban Research Institute, Children's Hospital Los Angeles, Los Angeles, California
| | - Sha Huang
- Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, Michigan.,Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, Michigan
| | - Jason R Spence
- Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, Michigan.,Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, Michigan.,Program of Cellular and Molecular Biology, University of Michigan Medical School, Ann Arbor, Michigan
| | - Tracy C Grikscheit
- Developmental Biology and Regenerative Medicine Program, The Saban Research Institute, Children's Hospital Los Angeles, Los Angeles, California.,Division of Pediatric Surgery, Department of Surgery, Children's Hospital Los Angeles, Los Angeles, California.,Keck Medical School, University of Southern California, Los Angeles, California
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10
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Zhou A, Rand CM, Hockney SM, Niewijk G, Reineke P, Speare V, Berry-Kravis EM, Zhou L, Jennings LJ, Yu M, Ceccherini I, Bachetti T, Pennock M, Yap KL, Weese-Mayer DE. Paired-like homeobox gene (PHOX2B) nonpolyalanine repeat expansion mutations (NPARMs): genotype-phenotype correlation in congenital central hypoventilation syndrome (CCHS). Genet Med 2021; 23:1656-1663. [PMID: 33958749 DOI: 10.1038/s41436-021-01178-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2020] [Revised: 04/02/2021] [Accepted: 04/02/2021] [Indexed: 11/09/2022] Open
Abstract
PURPOSE CCHS is an extremely rare congenital disorder requiring artificial ventilation as life support. Typically caused by heterozygous polyalanine repeat expansion mutations (PARMs) in the PHOX2B gene, identification of a relationship between PARM length and phenotype severity has enabled anticipatory management. However, for patients with non-PARMs in PHOX2B (NPARMs, ~10% of CCHS patients), a genotype-phenotype correlation has not been established. This comprehensive report of PHOX2B NPARMs and associated phenotypes, aims at elucidating potential genotype-phenotype correlations that will guide anticipatory management. METHODS An international collaboration (clinical, commercial, and research laboratories) was established to collect/share information on novel and previously published PHOX2B NPARM cases. Variants were categorized by type and gene location. Categorical data were analyzed with chi-square and Fisher's exact test; further pairwise comparisons were made on significant results. RESULTS Three hundred two individuals with PHOX2B NPARMs were identified, including 139 previously unreported cases. Findings demonstrate significant associations between key phenotypic manifestations of CCHS and variant type, location, and predicted effect on protein function. CONCLUSION This study presents the largest cohort of PHOX2B NPARMs and associated phenotype data to date, enabling genotype-phenotype studies that will advance personalized, anticipatory management and help elucidate pathological mechanisms. Further characterization of PHOX2B NPARMs demands longitudinal clinical follow-up through international registries.
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Affiliation(s)
- Amy Zhou
- Department of Pediatrics, Division of Autonomic Medicine, Center for Autonomic Medicine in Pediatrics (CAMP), Ann & Robert H. Lurie Children's Hospital of Chicago and Stanley Manne Children's Research Institute, Chicago, IL, USA
| | - Casey M Rand
- Department of Pediatrics, Division of Autonomic Medicine, Center for Autonomic Medicine in Pediatrics (CAMP), Ann & Robert H. Lurie Children's Hospital of Chicago and Stanley Manne Children's Research Institute, Chicago, IL, USA
| | - Sara M Hockney
- Department of Pediatrics, Division of Autonomic Medicine, Center for Autonomic Medicine in Pediatrics (CAMP), Ann & Robert H. Lurie Children's Hospital of Chicago and Stanley Manne Children's Research Institute, Chicago, IL, USA.,Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - Grace Niewijk
- Department of Pediatrics, Division of Autonomic Medicine, Center for Autonomic Medicine in Pediatrics (CAMP), Ann & Robert H. Lurie Children's Hospital of Chicago and Stanley Manne Children's Research Institute, Chicago, IL, USA
| | | | | | - Elizabeth M Berry-Kravis
- Departments of Pediatrics, Neurology, and Biochemistry, Molecular Diagnostics Laboratory, Rush University Medical Center, Chicago, IL, USA
| | - Lili Zhou
- Departments of Pediatrics, Neurology, and Biochemistry, Molecular Diagnostics Laboratory, Rush University Medical Center, Chicago, IL, USA
| | - Lawrence J Jennings
- Department of Pathology, Molecular Diagnostics Laboratory, Ann & Robert H. Lurie Children's Hospital of Chicago, Chicago, IL, USA.,Department of Pathology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - Min Yu
- Department of Pathology, Molecular Diagnostics Laboratory, Ann & Robert H. Lurie Children's Hospital of Chicago, Chicago, IL, USA
| | | | - Tiziana Bachetti
- IRCCS Istituto Giannina Gaslini, Genoa, Italy.,Lab Neurobiologia dello Sviluppo, Dip. Scienze della Terra dell'Ambiente e della Vita (DISTAV), Università di Genova, Genova, Italy
| | | | - Kai Lee Yap
- Department of Pathology, Molecular Diagnostics Laboratory, Ann & Robert H. Lurie Children's Hospital of Chicago, Chicago, IL, USA.,Department of Pathology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - Debra E Weese-Mayer
- Department of Pediatrics, Division of Autonomic Medicine, Center for Autonomic Medicine in Pediatrics (CAMP), Ann & Robert H. Lurie Children's Hospital of Chicago and Stanley Manne Children's Research Institute, Chicago, IL, USA. .,Northwestern University Feinberg School of Medicine, Chicago, IL, USA. .,Department of Pediatrics, Pediatric Autonomic Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL, USA.
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11
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Di Lascio S, Benfante R, Cardani S, Fornasari D. Research Advances on Therapeutic Approaches to Congenital Central Hypoventilation Syndrome (CCHS). Front Neurosci 2021; 14:615666. [PMID: 33510615 PMCID: PMC7835644 DOI: 10.3389/fnins.2020.615666] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2020] [Accepted: 12/17/2020] [Indexed: 12/11/2022] Open
Abstract
Congenital central hypoventilation syndrome (CCHS) is a genetic disorder of neurodevelopment, with an autosomal dominant transmission, caused by heterozygous mutations in the PHOX2B gene. CCHS is a rare disorder characterized by hypoventilation due to the failure of autonomic control of breathing. Until now no curative treatment has been found. PHOX2B is a transcription factor that plays a crucial role in the development (and maintenance) of the autonomic nervous system, and in particular the neuronal structures involved in respiratory reflexes. The underlying pathogenetic mechanism is still unclear, although studies in vivo and in CCHS patients indicate that some neuronal structures may be damaged. Moreover, in vitro experimental data suggest that transcriptional dysregulation and protein misfolding may be key pathogenic mechanisms. This review summarizes latest researches that improved the comprehension of the molecular pathogenetic mechanisms responsible for CCHS and discusses the search for therapeutic intervention in light of the current knowledge about PHOX2B function.
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Affiliation(s)
- Simona Di Lascio
- Department of Medical Biotechnology and Translational Medicine (BIOMETRA), Università degli Studi di Milano, Milan, Italy
| | - Roberta Benfante
- Department of Medical Biotechnology and Translational Medicine (BIOMETRA), Università degli Studi di Milano, Milan, Italy.,CNR-Institute of Neuroscience, Milan, Italy.,NeuroMi-Milan Center for Neuroscience, University of Milano Bicocca, Milan, Italy
| | - Silvia Cardani
- Department of Medical Biotechnology and Translational Medicine (BIOMETRA), Università degli Studi di Milano, Milan, Italy
| | - Diego Fornasari
- Department of Medical Biotechnology and Translational Medicine (BIOMETRA), Università degli Studi di Milano, Milan, Italy.,CNR-Institute of Neuroscience, Milan, Italy
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12
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Bachetti T, Ceccherini I. Causative and commonPHOX2Bvariants define a broad phenotypic spectrum. Clin Genet 2019; 97:103-113. [DOI: 10.1111/cge.13633] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Revised: 07/31/2019] [Accepted: 08/15/2019] [Indexed: 11/25/2022]
Affiliation(s)
- Tiziana Bachetti
- Laboratorio Neurobiologia dello Sviluppo, Dipartimento di Scienze della Terra dell'Ambiente e della Vita (DISTAV)Università di Genova Genova Italy
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13
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Pirone L, Caldinelli L, Di Lascio S, Di Girolamo R, Di Gaetano S, Fornasari D, Pollegioni L, Benfante R, Pedone E. Molecular insights into the role of the polyalanine region in mediating PHOX2B aggregation. FEBS J 2019; 286:2505-2521. [PMID: 30955232 DOI: 10.1111/febs.14841] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Revised: 02/27/2019] [Accepted: 04/04/2019] [Indexed: 11/26/2022]
Abstract
About 90% of congenital central hypoventilation syndrome (CCHS) patients show polyalanine triplet expansions in the coding region of transcription factor PHOX2B, which renders this protein an intriguing target to understand the insurgence of this syndrome and for the design of a novel therapeutical approach. Consistently with the role of PHOX2B as a transcriptional regulator, it is reasonable that a general transcriptional dysregulation caused by the polyalanine expansion might represent an important mechanism underlying CCHS pathogenesis. Therefore, this study focused on the biochemical characterization of different PHOX2B variants, such as a variant containing the correct C-terminal (20 alanines) stretch, one of the most frequent polyalanine expansions (+7 alanines), and a variant lacking the complete alanine stretch (0 alanines). Comparison of the different variants by a multidisciplinary approach based on different methodologies (including circular dichroism, spectrofluorimetry, light scattering, and Atomic Force Microscopy studies) highlighted the propensity to aggregate for the PHOX2B variant containing the polyalanine expansion (+7-alanines), especially in the presence of DNA, while the 0-alanines variant resembled the protein with the correct polyalanine length. Moreover, and unexpectedly, the formation of fibrils was revealed only for the pathological variant, suggesting a plausible role of such fibrils in the insurgence of CCHS.
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Affiliation(s)
- Luciano Pirone
- Institute of Biostructure and Bioimaging, CNR, Napoli, Italy
| | - Laura Caldinelli
- Dipartimento di Biotecnologie e Scienze della Vita, Università degli studi dell'Insubria, Varese, Italy
| | - Simona Di Lascio
- Department of Medical Biotechnology and Translational Medicine, Università degli Studi di Milano, Italy
| | - Rocco Di Girolamo
- Department of Chemical Sciences, University of Naples Federico II, Italy
| | | | - Diego Fornasari
- Department of Medical Biotechnology and Translational Medicine, Università degli Studi di Milano, Italy
| | - Loredano Pollegioni
- Dipartimento di Biotecnologie e Scienze della Vita, Università degli studi dell'Insubria, Varese, Italy
| | - Roberta Benfante
- Department of Medical Biotechnology and Translational Medicine, Università degli Studi di Milano, Italy
- CNR- Neuroscience Institute, Milan, Italy
| | - Emilia Pedone
- Institute of Biostructure and Bioimaging, CNR, Napoli, Italy
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14
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Ye G, Han D, Jiang Y, Wang Z, Zhou Y, Lin X, Chen W, Chen M, Xu J, Yang Y, Guo Q. A Novel c.676_677insG PHOX2B Mutation in Congenital Central Hypoventilation Syndrome. J Clin Sleep Med 2019; 15:509-513. [PMID: 30853048 DOI: 10.5664/jcsm.7688] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Accepted: 01/07/2019] [Indexed: 11/13/2022]
Abstract
ABSTRACT Paired-like homeobox (PHOX)2B is considered to be the causative gene of congenital central hypoventilation syndrome (CCHS), a dominant genetic disorder that results in abnormal central respiratory control with resulting hypoventilation during sleep. In this study, we report a novel c.676_677insG (p.Ala226fs) mutation in a patient with severe CCHS, and we evaluated the function of this mutation. The mutation reduced the translation of the mutant PHOX2B protein and impaired its ability to activate the PHOX2A promoter, due to a haploinsufficiency effect. The mutant PHOX2B was able to interact with wildtype PHOX2B, resulting in retention of PHOX2B on the nuclear membrane, which may impair the normal function of the nuclear membrane, and leading to cellular morbidity. Our study provides useful information for the functional studies of PHOX2B and understanding the pathogenesis of CCHS, and thus is beneficial for the prognosis of, genetic counseling for, and development of pharmaceuticals for PHOX2B-associated diseases.
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Affiliation(s)
- Guodong Ye
- United Diagnostic and Research Center for Clinical Genetics, School of Public Health of Xiamen University and Xiamen Maternal and Child Health Hospital, Xiamen, China.,Xiamen LifeInt Technology Co., Ltd, Xiamen, China.,School of Basic Medical Sciences, Jinan University, Guangzhou, China
| | - Daxiong Han
- School of Pharmaceutical Sciences, Xiamen University, Xiamen, China
| | - Yu Jiang
- United Diagnostic and Research Center for Clinical Genetics, School of Public Health of Xiamen University and Xiamen Maternal and Child Health Hospital, Xiamen, China
| | - Zengge Wang
- United Diagnostic and Research Center for Clinical Genetics, School of Public Health of Xiamen University and Xiamen Maternal and Child Health Hospital, Xiamen, China
| | - Yulin Zhou
- United Diagnostic and Research Center for Clinical Genetics, School of Public Health of Xiamen University and Xiamen Maternal and Child Health Hospital, Xiamen, China
| | - Xinzhu Lin
- Department of Neonatology, Xiamen Maternal and Child Health Hospital, Xiamen, China
| | - Weiwei Chen
- Xiamen LifeInt Technology Co., Ltd, Xiamen, China
| | - Maoli Chen
- Xiamen LifeInt Technology Co., Ltd, Xiamen, China
| | - Jianxiong Xu
- Xiamen LifeInt Technology Co., Ltd, Xiamen, China
| | - Yanyan Yang
- Third Institute of Oceanography, State Oceanic Administration, Xiamen, China
| | - Qiwei Guo
- United Diagnostic and Research Center for Clinical Genetics, School of Public Health of Xiamen University and Xiamen Maternal and Child Health Hospital, Xiamen, China
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15
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Bardanzellu F, Pintus MC, Fanos V, Marcialis MA. Neonatal Congenital Central Hypoventilation Syndrome: Why We Should not Sleep on it. Literature Review of Forty-two Neonatal Onset Cases. Curr Pediatr Rev 2019; 15:139-153. [PMID: 31223092 DOI: 10.2174/1573396315666190621103954] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Revised: 03/18/2019] [Accepted: 03/25/2019] [Indexed: 12/31/2022]
Abstract
Congenital Central Hypoventilation Syndrome (CCHS), also referred with the expression "Ondine's Curse", is a rare genetic life-long disease resulting from the mutation of PHOX2B gene on chromosome 4p12.3. CCHS represents an autonomic nervous system disorder; its more fearsome manifestation is central hypoventilation, due to a deficient response of chemoreceptors to hypercapnia and hypoxia. Several associated symptoms can occur, such as pupillary anomalies, arrhythmias, reduced heart rate variability, esophageal dysmotility, and structural comorbidities (Hirschsprung's Disease or neural crest tumours). CCHS typical onset is during the neonatal period, but cases of delayed diagnosis have been reported; moreover, both sporadic or familial cases can occur. In preterm newborns, asphyxia and typical prematurity-related findings may overlap CCHS clinical manifestations and make it harder to formulate a correct diagnosis. The early recognition of CCHS allows appropriate management, useful to reduce immediate and long- term consequences.
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Affiliation(s)
- Flaminia Bardanzellu
- Neonatal Intensive Care Unit, AOU and University of Cagliari, SS 554 km 4,500, 09042 Monserrato, Italy
| | - Maria Cristina Pintus
- Neonatal Intensive Care Unit, AOU and University of Cagliari, SS 554 km 4,500, 09042 Monserrato, Italy
| | - Vassilios Fanos
- Neonatal Intensive Care Unit, AOU and University of Cagliari, SS 554 km 4,500, 09042 Monserrato, Italy
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16
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Bishara J, Keens TG, Perez IA. The genetics of congenital central hypoventilation syndrome: clinical implications. APPLICATION OF CLINICAL GENETICS 2018; 11:135-144. [PMID: 30532577 PMCID: PMC6241683 DOI: 10.2147/tacg.s140629] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Congenital central hypoventilation syndrome (CCHS) is a rare genetic disorder of the autonomic nervous system (ANS) and respiratory control. This disorder, formerly referred to as Ondine’s curse, is due to a mutation in the PHOX2B gene that affects the development of the neural crest cells. CCHS has an autosomal dominant pattern of inheritance. Majority of the patients have a polyalanine repeat mutation (PARM) of the PHOX2B, while a small group has non-PARM (NPARM). Knowledge of the patient’s PHOX2B gene mutation helps predict a patient’s clinical presentation and outcome and aids in anticipatory management of the respiratory and ANS dysfunction.
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Affiliation(s)
- John Bishara
- Division of Pediatric Pulmonology and Sleep Medicine, Children's Hospital Los Angeles, Los Angeles, CA, USA,
| | - Thomas G Keens
- Division of Pediatric Pulmonology and Sleep Medicine, Children's Hospital Los Angeles, Los Angeles, CA, USA, .,Department of Pediatrics, Keck School of Medicine of USC, Los Angeles, CA, USA,
| | - Iris A Perez
- Division of Pediatric Pulmonology and Sleep Medicine, Children's Hospital Los Angeles, Los Angeles, CA, USA, .,Department of Pediatrics, Keck School of Medicine of USC, Los Angeles, CA, USA,
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17
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Di Lascio S, Benfante R, Cardani S, Fornasari D. Advances in the molecular biology and pathogenesis of congenital central hypoventilation syndrome—implications for new therapeutic targets. Expert Opin Orphan Drugs 2018. [DOI: 10.1080/21678707.2018.1540978] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Affiliation(s)
- Simona Di Lascio
- Department of Medical Biotechnology and Translational Medicine (BIOMETRA), Università degli Studi di Milano, Milan, Italy
| | - Roberta Benfante
- Department of Medical Biotechnology and Translational Medicine (BIOMETRA), Università degli Studi di Milano, Milan, Italy
- CNR- Neuroscience Institute, Milan, Italy
| | - Silvia Cardani
- Department of Medical Biotechnology and Translational Medicine (BIOMETRA), Università degli Studi di Milano, Milan, Italy
| | - Diego Fornasari
- Department of Medical Biotechnology and Translational Medicine (BIOMETRA), Università degli Studi di Milano, Milan, Italy
- CNR- Neuroscience Institute, Milan, Italy
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18
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Cardani S, Di Lascio S, Belperio D, Di Biase E, Ceccherini I, Benfante R, Fornasari D. Desogestrel down-regulates PHOX2B and its target genes in progesterone responsive neuroblastoma cells. Exp Cell Res 2018; 370:671-679. [PMID: 30036539 DOI: 10.1016/j.yexcr.2018.07.032] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2018] [Revised: 07/18/2018] [Accepted: 07/19/2018] [Indexed: 10/28/2022]
Abstract
The paired-like homeobox 2B gene (PHOX2B) encodes a key transcription factor that plays a role in the development of the autonomic nervous system and the neural structures involved in controlling breathing. In humans, PHOX2B over-expression plays a role in the pathogenesis of tumours arising from the sympathetic nervous system such as neuroblastomas, and heterozygous PHOX2B mutations cause Congenital Central Hypoventilation Syndrome (CCHS), a life-threatening neurocristopathy characterised by the defective autonomic control of breathing and involving altered CO2/H+ chemosensitivity. The recovery of CO2/H+ chemosensitivity and increased ventilation have been observed in two CCHS patients using the potent contraceptive progestin desogestrel. Given the central role of PHOX2B in the pathogenesis of CCHS, and the progesterone-mediated effects observed in the disease, we generated progesterone-responsive neuroblastoma cells, and evaluated the effects of 3-Ketodesogestrel (3-KDG), the biologically active metabolite of desogestrel, on the expression of PHOX2B and its target genes. Our findings demonstrate that, through progesterone nuclear receptor PR-B, 3-KDG down-regulates PHOX2B gene expression, by a post-transcriptional mechanism, and its target genes and open up the possibility that this mechanism may contribute to the positive effects observed in some CCHS patients.
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Affiliation(s)
- Silvia Cardani
- Dept. of Medical Biotechnology and Translational Medicine (BIOMETRA), Università degli Studi di Milano, via Vanvitelli 32, 2019 Milan, Italy
| | - Simona Di Lascio
- Dept. of Medical Biotechnology and Translational Medicine (BIOMETRA), Università degli Studi di Milano, via Vanvitelli 32, 2019 Milan, Italy
| | - Debora Belperio
- Dept. of Medical Biotechnology and Translational Medicine (BIOMETRA), Università degli Studi di Milano, via Vanvitelli 32, 2019 Milan, Italy
| | - Erika Di Biase
- Dept. of Medical Biotechnology and Translational Medicine (BIOMETRA), Università degli Studi di Milano, via Vanvitelli 32, 2019 Milan, Italy
| | - Isabella Ceccherini
- Laboratorio di Genetica Molecolare, Istituto Giannina Gaslini, Largo G. Gaslini 5, 16148 Genoa, Italy
| | - Roberta Benfante
- Dept. of Medical Biotechnology and Translational Medicine (BIOMETRA), Università degli Studi di Milano, via Vanvitelli 32, 2019 Milan, Italy; CNR -Neuroscience Institute, via Vanvitelli 32, 20129 Milan, Italy.
| | - Diego Fornasari
- Dept. of Medical Biotechnology and Translational Medicine (BIOMETRA), Università degli Studi di Milano, via Vanvitelli 32, 2019 Milan, Italy; CNR -Neuroscience Institute, via Vanvitelli 32, 20129 Milan, Italy.
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19
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Byers HM, Chen M, Gelfand AS, Ong B, Jendras M, Glass IA. Expanding the phenotype of congenital central hypoventilation syndrome impacts management decisions. Am J Med Genet A 2018; 176:1398-1404. [PMID: 29696799 DOI: 10.1002/ajmg.a.38726] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2017] [Revised: 04/01/2018] [Accepted: 04/04/2018] [Indexed: 11/10/2022]
Abstract
Congenital central hypoventilation syndrome (CCHS) is a neurocristopathy caused by pathogenic heterozygous variants in the gene paired-like homeobox 2b (PHOX2B). It is characterized by severe infantile alveolar hypoventilation. Individuals may also have diffuse autonomic nervous system dysfunction, Hirschsprung disease and neural crest tumors. We report three individuals with CCHS due to an 8-base pair duplication in PHOX2B; c.691_698dupGGCCCGGG (p.Gly234Alafs*78) with a predominant enteral and neural crest phenotype and a relatively mild respiratory phenotype. The attenuated respiratory phenotype reported here and elsewhere suggests an emergent genotype:phenotype correlation which challenges the current paradigm of invoking mechanical ventilation for all infants diagnosed with CCHS. Best treatment requires careful clinical judgment and ideally the assistance of a care team with expertise in CCHS.
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Affiliation(s)
- Heather M Byers
- Division of Medical Genetics, Department of Pediatrics, Stanford University, Palo Alto, California
| | - Maida Chen
- Department of Pediatrics, University of Washington, Seattle, Washington.,Division of Pulmonary Medicine, Seattle Children's Hospital, Seattle, Washington
| | | | - Bruce Ong
- Division of Pediatric Pulmonology, Tripler Army Medical Center, Honolulu, Hawaii
| | | | - Ian A Glass
- Department of Pediatrics, University of Washington, Seattle, Washington.,Division of Medical Genetics, Seattle Children's Hospital, Seattle, Washington
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20
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Congenital heart disease and aortic arch variants associated with mutation in PHOX2B. Genet Med 2018. [DOI: 10.1038/gim.2018.34] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
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21
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Di Lascio S, Benfante R, Di Zanni E, Cardani S, Adamo A, Fornasari D, Ceccherini I, Bachetti T. Structural and functional differences in PHOX2B frameshift mutations underlie isolated or syndromic congenital central hypoventilation syndrome. Hum Mutat 2017; 39:219-236. [PMID: 29098737 PMCID: PMC5846889 DOI: 10.1002/humu.23365] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2017] [Revised: 10/24/2017] [Accepted: 10/29/2017] [Indexed: 12/13/2022]
Abstract
Heterozygous mutations in the PHOX2B gene are causative of congenital central hypoventilation syndrome (CCHS), a neurocristopathy characterized by defective autonomic control of breathing due to the impaired differentiation of neural crest cells. Among PHOX2B mutations, polyalanine (polyAla) expansions are almost exclusively associated with isolated CCHS, whereas frameshift variants, although less frequent, are often more severe than polyAla expansions and identified in syndromic CCHS. This article provides a complete review of all the frameshift mutations identified in cases of isolated and syndromic CCHS reported in the literature as well as those identified by us and not yet published. These were considered in terms of both their structure, whether the underlying indels induced frameshifts of either 1 or 2 steps ("frame 2" and "frame 3" mutations respectively), and clinical associations. Furthermore, we evaluated the structural and functional effects of one "frame 3" mutation identified in a patient with isolated CCHS, and one "frame 2" mutation identified in a patient with syndromic CCHS, also affected with Hirschsprung's disease and neuroblastoma. The data thus obtained confirm that the type of translational frame affects the severity of the transcriptional dysfunction and the predisposition to isolated or syndromic CCHS.
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Affiliation(s)
- Simona Di Lascio
- Department of Medical Biotechnology and Translational Medicine, Università degli Studi di Milano, Milan, Italy
| | - Roberta Benfante
- Department of Medical Biotechnology and Translational Medicine, Università degli Studi di Milano, Milan, Italy.,CNR- Neuroscience Institute, Milan, Italy
| | | | - Silvia Cardani
- Department of Medical Biotechnology and Translational Medicine, Università degli Studi di Milano, Milan, Italy
| | - Annalisa Adamo
- UOC Genetica Medica, Istituto Giannina Gaslini, Genoa, Italy
| | - Diego Fornasari
- Department of Medical Biotechnology and Translational Medicine, Università degli Studi di Milano, Milan, Italy.,CNR- Neuroscience Institute, Milan, Italy
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22
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Di Zanni E, Adamo A, Belligni E, Lerone M, Martucciello G, Mattioli G, Pini Prato A, Ravazzolo R, Silengo M, Bachetti T, Ceccherini I. Common PHOX2B poly-alanine contractions impair RET gene transcription, predisposing to Hirschsprung disease. Biochim Biophys Acta Mol Basis Dis 2017; 1863:1770-1777. [PMID: 28433712 DOI: 10.1016/j.bbadis.2017.04.017] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2016] [Revised: 03/27/2017] [Accepted: 04/17/2017] [Indexed: 01/08/2023]
Abstract
HSCR is a congenital disorder of the enteric nervous system, characterized by the absence of neurons along a variable length of the gut resulting from loss-of-function RET mutations. Congenital Central Hypoventilation Syndrome (CCHS) is a rare neurocristopathy characterized by impaired response to hypercapnia and hypoxemia caused by heterozygous mutations of the PHOX2B gene, mostly polyalanine (polyA) expansions but also missense, nonsense, and frameshift mutations, while polyA contractions are common in the population and believed neutral. HSCR associated CCHS can present in patients carrying PHOX2B mutations. Indeed, RET expression is orchestrated by different transcriptional factors among which PHOX2B, thus suggesting its possible role in HSCR pathogenesis. Following the observation of HSCR patients carrying in frame trinucleotide deletions within the polyalanine stretch in exon 3 (polyA contractions), we have verified the hypothesis that these PHOX2B variants do reduce its transcriptional activity, likely resulting in a down-regulation of RET expression and, consequently, favouring the development of the HSCR phenotype. Using proper reporter constructs, we show here that the in vitro transactivation of the RET promoter by different HSCR-associated PHOX2B polyA variants has resulted significantly lower compared to the effect of PHOX2B wild type protein. In particular, polyA contractions do induce a reduced transactivation of the RET promoter, milder compared to the severe polyA expansions associated with CCHS+HSCR, and correlated with the length of the deleted trait, with a more pronounced effect when contractions are larger.
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Affiliation(s)
- Eleonora Di Zanni
- UOC Genetica Medica, Istituto Giannina Gaslini, 16148, Genova, Italy
| | - Annalisa Adamo
- UOC Genetica Medica, Istituto Giannina Gaslini, 16148, Genova, Italy
| | - Elga Belligni
- Dipartimento Scienze della Sanità Pubblica e Pediatriche, Università di Torino, Torino, Italy
| | - Margherita Lerone
- UOC Genetica Medica, Istituto Giannina Gaslini, 16148, Genova, Italy
| | - Giuseppe Martucciello
- UOC Chirurgia, Istituto Giannina Gaslini, 16148 Genova, Italy; DiNOGMI, University of Genova, Genova, Italy
| | | | | | - Roberto Ravazzolo
- UOC Genetica Medica, Istituto Giannina Gaslini, 16148, Genova, Italy; DiNOGMI, University of Genova, Genova, Italy
| | - Margherita Silengo
- Dipartimento Scienze della Sanità Pubblica e Pediatriche, Università di Torino, Torino, Italy
| | - Tiziana Bachetti
- UOC Genetica Medica, Istituto Giannina Gaslini, 16148, Genova, Italy
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23
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Cain JT, Kim DI, Quast M, Shivega WG, Patrick RJ, Moser C, Reuter S, Perez M, Myers A, Weimer JM, Roux KJ, Landsverk M. Nonsense pathogenic variants in exon 1 of PHOX2B lead to translational reinitiation in congenital central hypoventilation syndrome. Am J Med Genet A 2017; 173:1200-1207. [PMID: 28371199 DOI: 10.1002/ajmg.a.38162] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2016] [Revised: 11/15/2016] [Accepted: 01/09/2017] [Indexed: 11/06/2022]
Abstract
Pathogenic variants in PHOX2B lead to congenital central hypoventilation syndrome (CCHS), a rare disorder of the nervous system characterized by autonomic dysregulation and hypoventilation typically presenting in the neonatal period, although a milder late-onset (LO) presentation has been reported. More than 90% of cases are caused by polyalanine repeat mutations (PARMs) in the C-terminus of the protein; however non-polyalanine repeat mutations (NPARMs) have been reported. Most NPARMs are located in exon 3 of PHOX2B and result in a more severe clinical presentation including Hirschsprung disease (HSCR) and/or peripheral neuroblastic tumors (PNTs). A previously reported nonsense pathogenic variant in exon 1 of a patient with LO-CCHS and no HSCR or PNTs leads to translational reinitiation at a downstream AUG codon producing an N-terminally truncated protein. Here we report additional individuals with nonsense pathogenic variants in exon 1 of PHOX2B. In vitro analyses were used to determine if these and other reported nonsense variants in PHOX2B exon 1 produced N-terminally truncated proteins. We found that all tested nonsense variants in PHOX2B exon 1 produced a truncated protein of the same size. This truncated protein localized to the nucleus and transactivated a target promoter. These data suggest that nonsense pathogenic variants in the first exon of PHOX2B likely escape nonsense mediated decay (NMD) and produce N-terminally truncated proteins functionally distinct from those produced by the more common PARMs.
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Affiliation(s)
- Jacob T Cain
- Children's Health Research Center, Sanford Research, Sioux Falls, South Dakota
| | - Dae I Kim
- Children's Health Research Center, Sanford Research, Sioux Falls, South Dakota
| | - Megan Quast
- Children's Health Research Center, Sanford Research, Sioux Falls, South Dakota
| | - Winnie G Shivega
- Children's Health Research Center, Sanford Research, Sioux Falls, South Dakota
| | - Ryan J Patrick
- Children's Health Research Center, Sanford Research, Sioux Falls, South Dakota
| | - Chuanpit Moser
- Section of Pediatric Pulmonology, Sanford School of Medicine at the University of South Dakota, Sioux Falls, South Dakota
| | - Suzanne Reuter
- Section of Neonatal-Perinatal Medicine, Sanford School of Medicine at the University of South Dakota, Sioux Falls, South Dakota
| | - Myrza Perez
- Department of Pediatric Pulmonology, Kaiser Permanente, Roseville, California
| | - Angela Myers
- Department of Pediatrics, Sanford School of Medicine at the University of South Dakota, Sioux Falls, South Dakota
| | - Jill M Weimer
- Children's Health Research Center, Sanford Research, Sioux Falls, South Dakota.,Department of Pediatrics, Sanford School of Medicine at the University of South Dakota, Sioux Falls, South Dakota
| | - Kyle J Roux
- Children's Health Research Center, Sanford Research, Sioux Falls, South Dakota.,Department of Pediatrics, Sanford School of Medicine at the University of South Dakota, Sioux Falls, South Dakota
| | - Megan Landsverk
- Children's Health Research Center, Sanford Research, Sioux Falls, South Dakota.,Department of Pediatrics, Sanford School of Medicine at the University of South Dakota, Sioux Falls, South Dakota
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24
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Di Lascio S, Belperio D, Benfante R, Fornasari D. Alanine Expansions Associated with Congenital Central Hypoventilation Syndrome Impair PHOX2B Homeodomain-mediated Dimerization and Nuclear Import. J Biol Chem 2016; 291:13375-93. [PMID: 27129232 PMCID: PMC4933246 DOI: 10.1074/jbc.m115.679027] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2015] [Indexed: 11/30/2022] Open
Abstract
Heterozygous mutations of the human PHOX2B gene, a key regulator of autonomic nervous system development, lead to congenital central hypoventilation syndrome (CCHS), a neurodevelopmental disorder characterized by a failure in the autonomic control of breathing. Polyalanine expansions in the 20-residues region of the C terminus of PHOX2B are the major mutations responsible for CCHS. Elongation of the alanine stretch in PHOX2B leads to a protein with altered DNA binding, transcriptional activity, and nuclear localization and the possible formation of cytoplasmic aggregates; furthermore, the findings of various studies support the idea that CCHS is not due to a pure loss of function mechanism but also involves a dominant negative effect and/or toxic gain of function for PHOX2B mutations. Because PHOX2B forms homodimers and heterodimers with its paralogue PHOX2A in vitro, we tested the hypothesis that the dominant negative effects of the mutated proteins are due to non-functional interactions with the wild-type protein or PHOX2A using a co-immunoprecipitation assay and the mammalian two-hybrid system. Our findings show that PHOX2B forms homodimers and heterodimerizes weakly with mutated proteins, exclude the direct involvement of the polyalanine tract in dimer formation, and indicate that mutated proteins retain partial ability to form heterodimers with PHOX2A. Moreover, in this study, we investigated the effects of the longest polyalanine expansions on the homeodomain-mediated nuclear import, and our data clearly show that the expanded C terminus interferes with this process. These results provide novel insights into the effects of the alanine tract expansion on PHOX2B folding and activity.
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Affiliation(s)
- Simona Di Lascio
- From the Department of Medical Biotechnology and Translational Medicine, Università degli Studi di Milano, 20129 Milan, Italy and
| | - Debora Belperio
- From the Department of Medical Biotechnology and Translational Medicine, Università degli Studi di Milano, 20129 Milan, Italy and
| | - Roberta Benfante
- From the Department of Medical Biotechnology and Translational Medicine, Università degli Studi di Milano, 20129 Milan, Italy and the National Research Council (CNR) Neuroscience Institute, 20129 Milan, Italy
| | - Diego Fornasari
- From the Department of Medical Biotechnology and Translational Medicine, Università degli Studi di Milano, 20129 Milan, Italy and the National Research Council (CNR) Neuroscience Institute, 20129 Milan, Italy
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25
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Radó-Trilla N, Arató K, Pegueroles C, Raya A, de la Luna S, Albà MM. Key Role of Amino Acid Repeat Expansions in the Functional Diversification of Duplicated Transcription Factors. Mol Biol Evol 2015; 32:2263-72. [PMID: 25931513 PMCID: PMC4540963 DOI: 10.1093/molbev/msv103] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The high regulatory complexity of vertebrates has been related to two rounds of whole genome duplication (2R-WGD) that occurred before the divergence of the major vertebrate groups. Following these events, many developmental transcription factors (TFs) were retained in multiple copies and subsequently specialized in diverse functions, whereas others reverted to their singleton state. TFs are known to be generally rich in amino acid repeats or low-complexity regions (LCRs), such as polyalanine or polyglutamine runs, which can evolve rapidly and potentially influence the transcriptional activity of the protein. Here we test the hypothesis that LCRs have played a major role in the diversification of TF gene duplicates. We find that nearly half of the TF gene families originated during the 2R-WGD contains LCRs. The number of gene duplicates with LCRs is 155 out of 550 analyzed (28%), about twice as many as the number of single copy genes with LCRs (15 out of 115, 13%). In addition, duplicated TFs preferentially accumulate certain LCR types, the most prominent of which are alanine repeats. We experimentally test the role of alanine-rich LCRs in two different TF gene families, PHOX2A/PHOX2B and LHX2/LHX9. In both cases, the presence of the alanine-rich LCR in one of the copies (PHOX2B and LHX2) significantly increases the capacity of the TF to activate transcription. Taken together, the results provide strong evidence that LCRs are important driving forces of evolutionary change in duplicated genes.
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Affiliation(s)
- Núria Radó-Trilla
- Evolutionary Genomics Group, Research Programme on Biomedical Informatics (GRIB), Hospital del Mar Research Institute (IMIM), Barcelona, Spain
| | - Krisztina Arató
- Department of Experimental and Health Sciences, Universitat Pompeu Fabra (UPF), Barcelona, Spain Centre for Genomic Regulation (CRG), Barcelona, Spain Centro de Investigación Biomèdica en Red en Enfermedades Raras (CIBERER), Barcelona, Spain
| | - Cinta Pegueroles
- Evolutionary Genomics Group, Research Programme on Biomedical Informatics (GRIB), Hospital del Mar Research Institute (IMIM), Barcelona, Spain Centre for Genomic Regulation (CRG), Barcelona, Spain
| | - Alicia Raya
- Department of Experimental and Health Sciences, Universitat Pompeu Fabra (UPF), Barcelona, Spain Centre for Genomic Regulation (CRG), Barcelona, Spain Centro de Investigación Biomèdica en Red en Enfermedades Raras (CIBERER), Barcelona, Spain
| | - Susana de la Luna
- Department of Experimental and Health Sciences, Universitat Pompeu Fabra (UPF), Barcelona, Spain Centre for Genomic Regulation (CRG), Barcelona, Spain Centro de Investigación Biomèdica en Red en Enfermedades Raras (CIBERER), Barcelona, Spain Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona, Spain
| | - M Mar Albà
- Evolutionary Genomics Group, Research Programme on Biomedical Informatics (GRIB), Hospital del Mar Research Institute (IMIM), Barcelona, Spain Department of Experimental and Health Sciences, Universitat Pompeu Fabra (UPF), Barcelona, Spain Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona, Spain
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26
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Di Zanni E, Fornasari D, Ravazzolo R, Ceccherini I, Bachetti T. Identification of novel pathways and molecules able to down-regulate PHOX2B gene expression by in vitro drug screening approaches in neuroblastoma cells. Exp Cell Res 2015; 336:43-57. [PMID: 25882494 DOI: 10.1016/j.yexcr.2015.03.025] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2015] [Revised: 03/25/2015] [Accepted: 03/28/2015] [Indexed: 10/23/2022]
Abstract
PHOX2B is a transcription factor involved in the regulation of neurogenesis and in the correct differentiation of the autonomic nervous system. The pathogenetic role of PHOX2B in neuroblastoma (NB) is supported by mutations in familial, sporadic and syndromic cases of NB and overexpression of PHOX2B and its target ALK in tumor samples and NB cell lines. Starting from these observations, we have performed in vitro drug screening approaches targeting PHOX2B overexpression as a potential pharmacological means in NB. In particular, in order to identify molecules able to decrease PHOX2B expression, we have evaluated the effects of 70 compounds in IMR-32 cell line stably expressing the luciferase gene under the control of the PHOX2B promoter. Curcumin, SAHA and trichostatin A showed to down-regulate the PHOX2B promoter activity which resulted in a decrease of both protein and mRNA expressions. In addition, we have observed that curcumin acts by interfering with PBX-1/MEIS-1, NF-κB and AP-1 complexes, in this work demonstrated for the first time to regulate the transcription of the PHOX2B gene. Finally, combined drug treatments showed successful effects in down-regulating the expression of both PHOX2B and its target ALK genes, thus supporting the notion of the effectiveness of molecule combination in tumor therapy.
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Affiliation(s)
| | - Diego Fornasari
- Dipartimento di Farmacologia, Università degli Studi di Milano e CNR-Istituto di Neuroscienze, Italy
| | - Roberto Ravazzolo
- U.O.C. Genetica Medica, Istituto Giannina Gaslini, Italy; Università degli Studi di Genova, Italy
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27
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Abstract
Neuroblastoma is a developmental tumor of young children arising from the embryonic sympathoadrenal lineage of the neural crest. Neuroblastoma is the primary cause of death from pediatric cancer for children between the ages of one and five years and accounts for ∼13% of all pediatric cancer mortality. Its clinical impact and unique biology have made this aggressive malignancy the focus of a large concerted translational research effort. New insights into tumor biology are driving the development of new classification schemas. Novel targeted therapeutic approaches include small-molecule inhibitors as well as epigenetic, noncoding-RNA, and cell-based immunologic therapies. In this review, recent insights regarding the pathogenesis and biology of neuroblastoma are placed in context with the current understanding of tumor biology and tumor/host interactions. Systematic classification of patients coupled with therapeutic advances point to a future of improved clinical outcomes for this biologically distinct and highly aggressive pediatric malignancy.
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Affiliation(s)
- Chrystal U Louis
- Texas Children's Cancer Center, Baylor College of Medicine, Houston, Texas 77030; ,
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28
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Ramanantsoa N, Gallego J. Congenital central hypoventilation syndrome. Respir Physiol Neurobiol 2013; 189:272-9. [PMID: 23692929 DOI: 10.1016/j.resp.2013.05.018] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2013] [Revised: 05/03/2013] [Accepted: 05/14/2013] [Indexed: 10/26/2022]
Abstract
Congenital central hypoventilation syndrome (CCHS) is characterized by hypoventilation during sleep and impaired ventilatory responses to hypercapnia and hypoxemia. Most cases are sporadic and caused by de novo PHOX2B gene mutations, which are usually polyalanine repeat expansions. Physiological and neuroanatomical studies of genetically engineered mice and analyses of cellular responses to mutated Phox2b have shed light on the pathophysiological mechanisms of CCHS. Findings in Phox2b(27Ala/+) knock-in mice consisted of unstable breathing with apneas, absence of the ventilatory response to hypercapnia, death within a few hours after birth, and absence of the retrotrapezoid nucleus (RTN). Conditional mouse mutants in which Phox2b(27Ala) was targeted to the RTN also lacked the ventilatory response to hypercapnia at birth but survived to adulthood and developed a partial hypercapnia response. The therapeutic effects of desogestrel are being evaluated in clinical trials, and recent analyses of cellular responses to polyAla Phox2b aggregates have suggested new pharmacological approaches designed to counteract the toxic effects of mutated Phox2b.
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Affiliation(s)
- N Ramanantsoa
- INSERM, U676, Hôpital Robert Debré, 75019 Paris, France; Université Paris Diderot, Paris, France
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