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Abstract
Proneural genes encode evolutionarily conserved basic-helix-loop-helix transcription factors. In Drosophila, proneural genes are required and sufficient to confer a neural identity onto naïve ectodermal cells, inducing delamination and subsequent neuronal differentiation. In vertebrates, proneural genes are expressed in cells that already have a neural identity, but they are still required and sufficient to initiate neurogenesis. In all organisms, proneural genes control neurogenesis by regulating Notch-mediated lateral inhibition and initiating the expression of downstream differentiation genes. The general mode of proneural gene function has thus been elucidated. However, the regulatory mechanisms that spatially and temporally control proneural gene function are only beginning to be deciphered. Understanding how proneural gene function is regulated is essential, as aberrant proneural gene expression has recently been linked to a variety of human diseases-ranging from cancer to neuropsychiatric illnesses and diabetes. Recent insights into proneural gene function in development and disease are highlighted herein.
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Affiliation(s)
- Carol Huang
- Department of Pediatrics, Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta, Canada
| | - Jennifer A Chan
- Department of Pathology & Laboratory Medicine, Southern Alberta Cancer Research Institute, University of Calgary, Calgary, Alberta, Canada.
| | - Carol Schuurmans
- Department of Biochemistry and Molecular Biology, Alberta Children's Hospital Research Institute, Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada.
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Russo L, Iafusco D, Brescianini S, Nocerino V, Bizzarri C, Toni S, Cerutti F, Monciotti C, Pesavento R, Iughetti L, Bernardini L, Bonfanti R, Gargantini L, Vanelli M, Aguilar-Bryan L, Stazi MA, Grasso V, Colombo C, Barbetti F. Permanent diabetes during the first year of life: multiple gene screening in 54 patients. Diabetologia 2011; 54:1693-701. [PMID: 21544516 PMCID: PMC3110270 DOI: 10.1007/s00125-011-2094-8] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/24/2010] [Accepted: 01/25/2011] [Indexed: 11/30/2022]
Abstract
AIMS/HYPOTHESIS The aim of this study was to investigate the genetic aetiology of permanent diabetes mellitus with onset in the first 12 months of age. METHODS We studied 46 probands with permanent, insulin-requiring diabetes with onset within the first 6 months of life (permanent neonatal diabetes mellitus [PNDM]/monogenic diabetes of infancy [MDI]) (group 1) and eight participants with diabetes diagnosed between 7 and 12 months of age (group 2). KCNJ11, INS and ABCC8 genes were sequentially sequenced in all patients. For those who were negative in the initial screening, we examined ERN1, CHGA, CHGB and NKX6-1 genes and, in selected probands, CACNA1C, GCK, FOXP3, NEUROG3 and CDK4. The incidence rate for PNDM/MDI was calculated using a database of Italian patients collected from 1995 to 2009. RESULTS In group 1 we found mutations in KCNJ11, INS and ABCC8 genes in 23 (50%), 9 (19.5%) and 4 (8.6%) patients respectively, and a single homozygous mutation in GCK (2.1%). In group 2, we identified one incidence of a KCNJ11 mutation. No genetic defects were detected in other loci. The incidence rate of PNDM/MDI in Italy is estimated to be 1:210,287. CONCLUSIONS/INTERPRETATION Genetic mutations were identified in ~75% of non-consanguineous probands with PNDM/MDI, using sequential screening of KCNJ11, INS and ABCC8 genes in infants diagnosed within the first 6 months of age. This percentage decreased to 12% in those with diabetes diagnosed between 7 and 12 months. Patients belonging to the latter group may either carry mutations in genes different from those commonly found in PNDM/MDI or have developed an early-onset form of autoimmune diabetes.
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Affiliation(s)
- L. Russo
- Laboratory of Mendelian Diabetes, Ospedale Pediatrico Bambino Gesù, IRCCS, Rome, Italy
| | - D. Iafusco
- Department of Pediatrics, Second University of Naples, Naples, Italy
| | - S. Brescianini
- Department of Epidemiology, Istituto Superiore di Sanità, Rome, Italy
| | - V. Nocerino
- Laboratory of Mendelian Diabetes, Ospedale Pediatrico Bambino Gesù, IRCCS, Rome, Italy
| | - C. Bizzarri
- Endocrinology Unit, Ospedale Pediatrico Bambino Gesù, IRCCS, Rome, Italy
| | - S. Toni
- Regional Center for Juvenile Diabetes, Meyer Pediatric Hospital, Florence, Italy
| | - F. Cerutti
- Department of Pediatrics, University of Turin, Turin, Italy
| | - C. Monciotti
- Department of Pediatrics, University of Padua, Padua, Italy
| | - R. Pesavento
- Pediatric Unit, Boldrini Hospital, Thiene, Italy
| | - L. Iughetti
- Department of Pediatrics, University of Modena, Modena, Italy
| | - L. Bernardini
- Mendel Laboratory, Casa Sollievo della Sofferenza, S Giovanni, Rotondo, Italy
| | - R. Bonfanti
- Department of Pediatrics, H S Raffaele Hospital and Scientific Institute, Milan, Italy
| | - L. Gargantini
- Department of Pediatrics, Treviglio Hospital, Treviglio, Italy
| | - M. Vanelli
- Department of Pediatrics, University of Parma, Parma, Italy
| | | | - M. A. Stazi
- Department of Epidemiology, Istituto Superiore di Sanità, Rome, Italy
| | - V. Grasso
- Department of Laboratory Medicine, Tor Vergata University Hospital, Rome, Italy
| | - C. Colombo
- Laboratory of Mendelian Diabetes, Ospedale Pediatrico Bambino Gesù, IRCCS, Rome, Italy
| | - F. Barbetti
- Laboratory of Mendelian Diabetes, Ospedale Pediatrico Bambino Gesù, IRCCS, Rome, Italy
- Department of Internal Medicine, University of Tor Vergata, Via Montpellier 1, 00134 Rome, Italy
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Rubio-Cabezas O, Jensen JN, Hodgson MI, Codner E, Ellard S, Serup P, Hattersley AT. Permanent Neonatal Diabetes and Enteric Anendocrinosis Associated With Biallelic Mutations in NEUROG3. Diabetes 2011; 60:1349-53. [PMID: 21378176 PMCID: PMC3064109 DOI: 10.2337/db10-1008] [Citation(s) in RCA: 119] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
OBJECTIVE NEUROG3 plays a central role in the development of both pancreatic islets and enteroendocrine cells. Homozygous hypomorphic missense mutations in NEUROG3 have been recently associated with a rare form of congenital malabsorptive diarrhea secondary to enteroendocrine cell dysgenesis. Interestingly, the patients did not develop neonatal diabetes but childhood-onset diabetes. We hypothesized that null mutations in NEUROG3 might be responsible for the disease in a patient with permanent neonatal diabetes and severe congenital malabsorptive diarrhea. RESEARCH DESIGN AND METHODS The single coding exon of NEUROG3 was amplified and sequenced from genomic DNA. The mutant protein isoforms were functionally characterized by measuring their ability to bind to an E-box element in the NEUROD1 promoter in vitro and to induce ectopic endocrine cell formation and cell delamination after in ovo chicken endoderm electroporation. RESULTS Two different heterozygous point mutations in NEUROG3 were identified in the proband [c.82G>T (p.E28X) and c.404T>C (p.L135P)], each being inherited from an unaffected parent. Both in vitro and in vivo functional studies indicated that the mutant isoforms are biologically inactive. In keeping with this, no enteroendocrine cells were detected in intestinal biopsy samples from the patient. CONCLUSIONS Severe deficiency of neurogenin 3 causes a rare novel subtype of permanent neonatal diabetes. This finding confirms the essential role of NEUROG3 in islet development and function in humans.
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Affiliation(s)
- Oscar Rubio-Cabezas
- Institute of Biomedical and Clinical Science, Peninsula Medical School, Exeter, U.K
- Department of Endocrinology, Hospital Infantil Universitario Niño Jesús, Madrid, Spain
- CIBER Fisiopatología de la Obesidad y Nutrición, Instituto de Salud Carlos III, Madrid, Spain
| | | | - Maria I. Hodgson
- Department of Pediatrics, School of Medicine, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Ethel Codner
- Institute of Maternal and Child Research, School of Medicine, University of Chile, Santiago, Chile
| | - Sian Ellard
- Institute of Biomedical and Clinical Science, Peninsula Medical School, Exeter, U.K
| | - Palle Serup
- Hagedorn Research Institute, Gentofte, Denmark
| | - Andrew T. Hattersley
- Institute of Biomedical and Clinical Science, Peninsula Medical School, Exeter, U.K
- Corresponding author: Andrew T. Hattersley,
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