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McEntagart M, Williamson KA, Rainger JK, Wheeler A, Seawright A, De Baere E, Verdin H, Bergendahl LT, Quigley A, Rainger J, Dixit A, Sarkar A, López Laso E, Sanchez-Carpintero R, Barrio J, Bitoun P, Prescott T, Riise R, McKee S, Cook J, McKie L, Ceulemans B, Meire F, Temple IK, Prieur F, Williams J, Clouston P, Németh AH, Banka S, Bengani H, Handley M, Freyer E, Ross A, van Heyningen V, Marsh JA, Elmslie F, FitzPatrick DR. A Restricted Repertoire of De Novo Mutations in ITPR1 Cause Gillespie Syndrome with Evidence for Dominant-Negative Effect. Am J Hum Genet 2016; 98:981-992. [PMID: 27108798 PMCID: PMC4863663 DOI: 10.1016/j.ajhg.2016.03.018] [Citation(s) in RCA: 66] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2015] [Accepted: 03/16/2016] [Indexed: 12/19/2022] Open
Abstract
Gillespie syndrome (GS) is characterized by bilateral iris hypoplasia, congenital hypotonia, non-progressive ataxia, and progressive cerebellar atrophy. Trio-based exome sequencing identified de novo mutations in ITPR1 in three unrelated individuals with GS recruited to the Deciphering Developmental Disorders study. Whole-exome or targeted sequence analysis identified plausible disease-causing ITPR1 mutations in 10/10 additional GS-affected individuals. These ultra-rare protein-altering variants affected only three residues in ITPR1: Glu2094 missense (one de novo, one co-segregating), Gly2539 missense (five de novo, one inheritance uncertain), and Lys2596 in-frame deletion (four de novo). No clinical or radiological differences were evident between individuals with different mutations. ITPR1 encodes an inositol 1,4,5-triphosphate-responsive calcium channel. The homo-tetrameric structure has been solved by cryoelectron microscopy. Using estimations of the degree of structural change induced by known recessive- and dominant-negative mutations in other disease-associated multimeric channels, we developed a generalizable computational approach to indicate the likely mutational mechanism. This analysis supports a dominant-negative mechanism for GS variants in ITPR1. In GS-derived lymphoblastoid cell lines (LCLs), the proportion of ITPR1-positive cells using immunofluorescence was significantly higher in mutant than control LCLs, consistent with an abnormality of nuclear calcium signaling feedback control. Super-resolution imaging supports the existence of an ITPR1-lined nucleoplasmic reticulum. Mice with Itpr1 heterozygous null mutations showed no major iris defects. Purkinje cells of the cerebellum appear to be the most sensitive to impaired ITPR1 function in humans. Iris hypoplasia is likely to result from either complete loss of ITPR1 activity or structure-specific disruption of multimeric interactions.
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Affiliation(s)
- Meriel McEntagart
- Medical Genetics, St George's University Hospitals NHS Foundation Trust, Cranmer Terrace, London SW17 0RE, UK
| | - Kathleen A Williamson
- MRC Human Genetics Unit, IGMM, University of Edinburgh, Western General Hospital, Edinburgh EH4 2XU, UK
| | - Jacqueline K Rainger
- MRC Human Genetics Unit, IGMM, University of Edinburgh, Western General Hospital, Edinburgh EH4 2XU, UK
| | - Ann Wheeler
- MRC Human Genetics Unit, IGMM, University of Edinburgh, Western General Hospital, Edinburgh EH4 2XU, UK
| | - Anne Seawright
- MRC Human Genetics Unit, IGMM, University of Edinburgh, Western General Hospital, Edinburgh EH4 2XU, UK
| | - Elfride De Baere
- Center for Medical Genetics Ghent (CMGG), Ghent University Hospital, Medical Research Building (MRB), 1st Floor, Room 110.029, De Pintelaan 185, 9000 Ghent, Belgium
| | - Hannah Verdin
- Center for Medical Genetics Ghent (CMGG), Ghent University Hospital, Medical Research Building (MRB), 1st Floor, Room 110.029, De Pintelaan 185, 9000 Ghent, Belgium
| | - L Therese Bergendahl
- MRC Human Genetics Unit, IGMM, University of Edinburgh, Western General Hospital, Edinburgh EH4 2XU, UK
| | - Alan Quigley
- Department of Radiology, Royal Hospital for Sick Children, Edinburgh EH9 1LF, UK
| | - Joe Rainger
- MRC Human Genetics Unit, IGMM, University of Edinburgh, Western General Hospital, Edinburgh EH4 2XU, UK; Roslin Institute, University of Edinburgh, Easter Bush, Midlothian EH25 9RG, UK
| | - Abhijit Dixit
- Clinical Genetics, Nottingham City Hospital, Hucknall Road, Nottingham NG5 1PB, UK
| | - Ajoy Sarkar
- Clinical Genetics, Nottingham City Hospital, Hucknall Road, Nottingham NG5 1PB, UK
| | - Eduardo López Laso
- Pediatric Neurology Unit, Department of Pediatrics, Reina Sofia University Hospital, Av. Menéndez Pidal s/n, 14004 Córdoba, Spain
| | - Rocio Sanchez-Carpintero
- Paediatric Neurology Unit, Department of Paediatrics, Clinica Universidad de Navarra, 31008 Pamplona, Spain
| | - Jesus Barrio
- Department of Ophthalmology, Clinica Universidad de Navarra, 31008 Pamplona, Spain
| | - Pierre Bitoun
- Service de pédiatrie, CHU Paris Seine-Saint-Denis - Hôpital Jean Verdier Avenue du 14 juillet, 93140 Bondy, France
| | - Trine Prescott
- Department of Medical Genetics, Oslo University Hospital, 0424 Oslo, Norway
| | - Ruth Riise
- Department of Ophthalmology, Innland Hospital, 2418 Elverum, Norway
| | - Shane McKee
- Northern Ireland Regional Genetics Service, Belfast City Hospital, Belfast BT9 7AB, UK
| | - Jackie Cook
- Sheffield Clinical Genetics Service, Sheffield Children's Hospital, Western Bank, Sheffield S10 2TH, UK
| | - Lisa McKie
- MRC Human Genetics Unit, IGMM, University of Edinburgh, Western General Hospital, Edinburgh EH4 2XU, UK
| | - Berten Ceulemans
- Department of Neurology-Pediatric Neurology, University and University Hospital Antwerp, Antwerp 2650, Belgium
| | - Françoise Meire
- Department of Ophthalmology, Queen Fabiola Children's University Hospital, 1020 Brussels, Belgium
| | - I Karen Temple
- Human Development and Health Academic Unit, University Hospital Southampton, Tremona Road, University of Southampton, Southampton SO16 6YD, UK
| | - Fabienne Prieur
- Service Génétique, Plateau de biologie, CHU Saint Etienne, 42055 Saint Etienne cedex 2, France
| | - Jonathan Williams
- Oxford University Hospitals NHS Trust, Oxford Medical Genetics Laboratories, The Churchill Hospital, Old Road, Headington, Oxford OX3 7LE, UK
| | - Penny Clouston
- Oxford University Hospitals NHS Trust, Oxford Medical Genetics Laboratories, The Churchill Hospital, Old Road, Headington, Oxford OX3 7LE, UK
| | - Andrea H Németh
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford OX3 7LJ, UK
| | - Siddharth Banka
- Manchester Centre for Genomic Medicine, University of Manchester, St. Mary's Hospital, Oxford Road, Manchester M13 9WL, UK
| | - Hemant Bengani
- MRC Human Genetics Unit, IGMM, University of Edinburgh, Western General Hospital, Edinburgh EH4 2XU, UK
| | - Mark Handley
- MRC Human Genetics Unit, IGMM, University of Edinburgh, Western General Hospital, Edinburgh EH4 2XU, UK
| | - Elisabeth Freyer
- MRC Human Genetics Unit, IGMM, University of Edinburgh, Western General Hospital, Edinburgh EH4 2XU, UK
| | - Allyson Ross
- MRC Human Genetics Unit, IGMM, University of Edinburgh, Western General Hospital, Edinburgh EH4 2XU, UK
| | - Veronica van Heyningen
- MRC Human Genetics Unit, IGMM, University of Edinburgh, Western General Hospital, Edinburgh EH4 2XU, UK
| | - Joseph A Marsh
- MRC Human Genetics Unit, IGMM, University of Edinburgh, Western General Hospital, Edinburgh EH4 2XU, UK
| | - Frances Elmslie
- Medical Genetics, St George's University Hospitals NHS Foundation Trust, Cranmer Terrace, London SW17 0RE, UK
| | - David R FitzPatrick
- MRC Human Genetics Unit, IGMM, University of Edinburgh, Western General Hospital, Edinburgh EH4 2XU, UK.
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Hirata M, Takeuchi H, Riley AM, Mills SJ, Watanabe Y, Potter BV. Inositol 1,4,5-trisphosphate receptor subtypes differentially recognize regioisomers of D-myo-inositol 1,4,5-trisphosphate. Biochem J 1997; 328 ( Pt 1):93-8. [PMID: 9359838 PMCID: PMC1218891 DOI: 10.1042/bj3280093] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The Ins(1,4,5)P3 regioisomers, Ins(1,4,6)P3 and Ins(1,3,6)P3, which can mimic the 1,4,5-arrangement on the inositol ring of Ins(1,4,5)P3, were examined for Ca2+ release by using four types of saponin-permeabilized cell possessing various abundances of receptor subtypes, with special reference to the relation of potency to receptor subtype. Ins(1,4,6)P3 and Ins(1,3,6)P3 were weak agonists in rat basophilic leukaemic cells (RBL cells), which possess predominantly subtype II receptors, with respective potencies of 1/200 and less than 1/500 that of Ins(1,4,5)P3 [the EC50 values were 0.2, 45 and more than 100 microM for Ins(1,4,5)P3, Ins(1,4,6)P3 and Ins(1,3,6)P3 respectively]. Similar rank order potencies were also evaluated for the displacement of [3H]Ins(1,4,5)P3 bound to RBL cell membranes by these regioisomers. However, they caused Ca2+ release from GH3 rat pituitary cells possessing predominantly subtype I receptors more potently; Ins(1,4,6)P3 and Ins(1,3,6)P3 evoked release at respective concentrations of only one-third and one-twentieth that of Ins(1,4,5)P3 (the EC50 values were 0.4, 1.2 and 8 microM for Ins(1,4,5)P3, Ins(1,4,6)P3 and Ins(1,3,6)P3 respectively). In COS-1 African green-monkey kidney cells, with the relative abundances of 37% of the subtype II and of 62% of the subtype III receptor, potencies of 1/40 and approx. 1/200 for Ins(1, 4,6)P3 and Ins(1,3,6)P3 respectively were exhibited relative to Ins(1,4,5)P3 (the EC50 values were 0.4, 15 and approx. 80 microM for Ins(1,4,5)P3, Ins(1,4,6)P3 and Ins(1,3,6)P3 respectively). In HL-60 human leukaemic cells, in spite of the dominant presence of subtype I receptors (71%), similar respective potencies to those seen with COS-1 cells were exhibited (the EC50 values were 0.3, 15 and approx. 100 microM for Ins(1,4,5)P3, Ins(1,4,6)P3 and Ins(1,3,6)P3 respectively). These results indicate that these regioisomers are the first ligands that distinguish between receptor subtypes; the present observations are of significance for the future design of molecules with enhanced selectivity.
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MESH Headings
- Animals
- COS Cells
- Calcium/metabolism
- Calcium Channels/chemistry
- Calcium Channels/metabolism
- HL-60 Cells
- Humans
- Inositol 1,4,5-Trisphosphate/chemistry
- Inositol 1,4,5-Trisphosphate/metabolism
- Inositol 1,4,5-Trisphosphate Receptors
- Leukemia, Basophilic, Acute
- Molecular Conformation
- Pituitary Neoplasms
- Rats
- Receptors, Cytoplasmic and Nuclear/chemistry
- Receptors, Cytoplasmic and Nuclear/metabolism
- Stereoisomerism
- Tumor Cells, Cultured
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Affiliation(s)
- M Hirata
- Department of Biochemistry, Faculty of Dentistry, Kyushu University, Fukuoka, Japan
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