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Lago-Docampo M, Tenorio J, Hernández-González I, Pérez-Olivares C, Escribano-Subías P, Pousada G, Baloira A, Arenas M, Lapunzina P, Valverde D. Characterization of rare ABCC8 variants identified in Spanish pulmonary arterial hypertension patients. Sci Rep 2020; 10:15135. [PMID: 32934261 PMCID: PMC7492224 DOI: 10.1038/s41598-020-72089-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Accepted: 08/25/2020] [Indexed: 02/08/2023] Open
Abstract
Pulmonary Arterial Hypertension (PAH) is a rare and fatal disease where knowledge about its genetic basis continues to increase. In this study, we used targeted panel sequencing in a cohort of 624 adult and pediatric patients from the Spanish PAH registry. We identified 11 rare variants in the ATP-binding Cassette subfamily C member 8 (ABCC8) gene, most of them with splicing alteration predictions. One patient also carried another variant in SMAD1 gene (c.27delinsGTAAAG). We performed an ABCC8 in vitro biochemical analyses using hybrid minigenes to confirm the correct mRNA processing of 3 missense variants (c.211C > T p.His71Tyr, c.298G > A p.Glu100Lys and c.1429G > A p.Val477Met) and the skipping of exon 27 in the novel splicing variant c.3394G > A. Finally, we used structural protein information to further assess the pathogenicity of the variants. The results showed 11 novel changes in ABCC8 and 1 in SMAD1 present in PAH patients. After in silico and in vitro biochemical analyses, we classified 2 as pathogenic (c.3288_3289del and c.3394G > A), 6 as likely pathogenic (c.211C > T, c.1429G > A, c.1643C > T, c.2422C > A, c.2694 + 1G > A, c.3976G > A and SMAD1 c.27delinsGTAAAG) and 3 as Variants of Uncertain Significance (c.298G > A, c.2176G > A and c.3238G > A). In all, we show that coupling in silico tools with in vitro biochemical studies can improve the classification of genetic variants.
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Affiliation(s)
- Mauro Lago-Docampo
- CINBIO, Universidade de Vigo, Vigo, Spain
- Instituto de Investigación Sanitaria Galicia Sur, Hospital Álvaro Cunqueiro, Vigo, Spain
| | - Jair Tenorio
- Instituto de Genética Médica y Molecular (INGEMM), Hospital Universitario La Paz-IdiPaz, Universidad Autónoma de Madrid, Madrid, Spain
- Centro de Investigación Biomédica en Red de enfermedades Raras (CIBERER), Instituto de Salud Carlos III, Madrid, Spain
- ITHACA, European Reference Network on Rare Congenital Malformations and Rare Intellectual Disability, Brussels, Belgium
| | - Ignacio Hernández-González
- Servicio de Cardiología, Hospital Universitario Río Hortega, Valladolid, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Cardiovasculares (CIBERCV), Instituto de Salud Carlos III, Madrid, Spain
- Unidad Multidisciplinar de Hipertensión Pulmonar, Servicio de Cardiología, Hospital Universitario, 12 de Octubre, Madrid, Spain
| | - Carmen Pérez-Olivares
- Centro de Investigación Biomédica en Red de Enfermedades Cardiovasculares (CIBERCV), Instituto de Salud Carlos III, Madrid, Spain
- Unidad Multidisciplinar de Hipertensión Pulmonar, Servicio de Cardiología, Hospital Universitario, 12 de Octubre, Madrid, Spain
- Servicio de Cardiología, Hospital 12 de Octubre, Madrid, Spain
| | - Pilar Escribano-Subías
- Centro de Investigación Biomédica en Red de Enfermedades Cardiovasculares (CIBERCV), Instituto de Salud Carlos III, Madrid, Spain
- Unidad Multidisciplinar de Hipertensión Pulmonar, Servicio de Cardiología, Hospital Universitario, 12 de Octubre, Madrid, Spain
- Servicio de Cardiología, Hospital 12 de Octubre, Madrid, Spain
| | - Guillermo Pousada
- Instituto de Investigación Sanitaria Galicia Sur, Hospital Álvaro Cunqueiro, Vigo, Spain
| | - Adolfo Baloira
- Servicio de Neumología, Complejo Hospitalario de Pontevedra, Pontevedra, Spain
| | - Miguel Arenas
- CINBIO, Universidade de Vigo, Vigo, Spain
- Instituto de Investigación Sanitaria Galicia Sur, Hospital Álvaro Cunqueiro, Vigo, Spain
| | - Pablo Lapunzina
- Instituto de Genética Médica y Molecular (INGEMM), Hospital Universitario La Paz-IdiPaz, Universidad Autónoma de Madrid, Madrid, Spain
- Centro de Investigación Biomédica en Red de enfermedades Raras (CIBERER), Instituto de Salud Carlos III, Madrid, Spain
- ITHACA, European Reference Network on Rare Congenital Malformations and Rare Intellectual Disability, Brussels, Belgium
| | - Diana Valverde
- CINBIO, Universidade de Vigo, Vigo, Spain.
- Instituto de Investigación Sanitaria Galicia Sur, Hospital Álvaro Cunqueiro, Vigo, Spain.
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Pipatpolkai T, Usher S, Stansfeld PJ, Ashcroft FM. New insights into K ATP channel gene mutations and neonatal diabetes mellitus. Nat Rev Endocrinol 2020; 16:378-393. [PMID: 32376986 DOI: 10.1038/s41574-020-0351-y] [Citation(s) in RCA: 69] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 03/17/2020] [Indexed: 12/12/2022]
Abstract
The ATP-sensitive potassium channel (KATP channel) couples blood levels of glucose to insulin secretion from pancreatic β-cells. KATP channel closure triggers a cascade of events that results in insulin release. Metabolically generated changes in the intracellular concentrations of adenosine nucleotides are integral to this regulation, with ATP and ADP closing the channel and MgATP and MgADP increasing channel activity. Activating mutations in the genes encoding either of the two types of KATP channel subunit (Kir6.2 and SUR1) result in neonatal diabetes mellitus, whereas loss-of-function mutations cause hyperinsulinaemic hypoglycaemia of infancy. Sulfonylurea and glinide drugs, which bind to SUR1, close the channel through a pathway independent of ATP and are now the primary therapy for neonatal diabetes mellitus caused by mutations in the genes encoding KATP channel subunits. Insight into the molecular details of drug and nucleotide regulation of channel activity has been illuminated by cryo-electron microscopy structures that reveal the atomic-level organization of the KATP channel complex. Here we review how these structures aid our understanding of how the various mutations in the genes encoding Kir6.2 (KCNJ11) and SUR1 (ABCC8) lead to a reduction in ATP inhibition and thereby neonatal diabetes mellitus. We also provide an update on known mutations and sulfonylurea therapy in neonatal diabetes mellitus.
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Affiliation(s)
- Tanadet Pipatpolkai
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
- Department of Biochemistry, University of Oxford, Oxford, UK
| | - Samuel Usher
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
| | - Phillip J Stansfeld
- Department of Biochemistry, University of Oxford, Oxford, UK
- School of Life Sciences, University of Warwick, Coventry, UK
- Department of Chemistry, University of Warwick, Coventry, UK
| | - Frances M Ashcroft
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK.
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Tinker A, Aziz Q, Li Y, Specterman M. ATP‐Sensitive Potassium Channels and Their Physiological and Pathophysiological Roles. Compr Physiol 2018; 8:1463-1511. [DOI: 10.1002/cphy.c170048] [Citation(s) in RCA: 72] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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Zhang K, Mu L, Ding MC, Xu R, Ding ZJ, Liang J. NFκB mediated elevation of KCNJ11 promotes tumor progression of hepatocellular carcinoma through interaction of lactate dehydrogenase A. Biochem Biophys Res Commun 2017; 495:246-253. [PMID: 29108994 DOI: 10.1016/j.bbrc.2017.11.011] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2017] [Accepted: 11/02/2017] [Indexed: 01/10/2023]
Abstract
It has been well documented that changes in ion fluxes across cellular membranes is fundamental in maintaining cellular homeostasis. Dysregulation and/or malfunction of ion channels are critical events in the pathogenesis of diverse diseases, including cancers. In this study, we focused on the study of K+ channels in hepatocellular carcinoma (HCC). By data mining TCGA cohort, the expression of 27 K+ channels was investigated and KCNJ11 was identified as a key dysregulated K+ channels in HCC. KCNJ11 was differentially expressed in HCC and predicted a poor prognosis in HCC patients. Inhibition of NFκB signaling suppressed KCNJ11 expression in HCC cells. Knockdown of KCNJ11 expression inhibited cell proliferation, promoted cell apoptosis, and reduced cell invasive capacity. Mechanistically, we found that KCNJ11 promotes tumor progression through interaction with LDHA and enhancing its enzymatic activity. Pharmacological inhibition of LDHA largely compromised the oncogenic function of KCNJ11 in cell proliferation, cell apoptosis, and cell invasion. Collectively, our data, as a proof of principle, demonstrate that KCNJ11 acts as an oncogene in HCC though forming a complex with LDHA and suggest that targeting KCNJ11 can be developed as a candidate tool to dampen HCC.
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Affiliation(s)
- Ke Zhang
- Qingdao University, Qingdao 266003, China; Institute of Oncology, Rizhao City People's Hospital, Rizhao 276800, China
| | - Ling Mu
- Medical Center, Rizhao City People's Hospital, Rizhao 276800, China
| | - Ming-Cui Ding
- Institute of Oncology, Rizhao City People's Hospital, Rizhao 276800, China
| | - Rui Xu
- Intervention Section, Rizhao City People's Hospital, Rizhao 276800, China
| | - Zhao-Jun Ding
- Institute of Oncology, Rizhao City People's Hospital, Rizhao 276800, China
| | - Jun Liang
- Institute of Oncology, Hospital Affiliated to Qingdao University, Qingdao 266003, China; Institute of Oncology, Peking University International Hospital, Beijing 102200, China.
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A three-step programmed method for the identification of causative gene mutations of maturity onset diabetes of the young (MODY). Gene 2016; 588:141-8. [DOI: 10.1016/j.gene.2016.05.021] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Revised: 05/09/2016] [Accepted: 05/12/2016] [Indexed: 01/10/2023]
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Yang Y, Chan L. Monogenic Diabetes: What It Teaches Us on the Common Forms of Type 1 and Type 2 Diabetes. Endocr Rev 2016; 37:190-222. [PMID: 27035557 PMCID: PMC4890265 DOI: 10.1210/er.2015-1116] [Citation(s) in RCA: 84] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
To date, more than 30 genes have been linked to monogenic diabetes. Candidate gene and genome-wide association studies have identified > 50 susceptibility loci for common type 1 diabetes (T1D) and approximately 100 susceptibility loci for type 2 diabetes (T2D). About 1-5% of all cases of diabetes result from single-gene mutations and are called monogenic diabetes. Here, we review the pathophysiological basis of the role of monogenic diabetes genes that have also been found to be associated with common T1D and/or T2D. Variants of approximately one-third of monogenic diabetes genes are associated with T2D, but not T1D. Two of the T2D-associated monogenic diabetes genes-potassium inward-rectifying channel, subfamily J, member 11 (KCNJ11), which controls glucose-stimulated insulin secretion in the β-cell; and peroxisome proliferator-activated receptor γ (PPARG), which impacts multiple tissue targets in relation to inflammation and insulin sensitivity-have been developed as major antidiabetic drug targets. Another monogenic diabetes gene, the preproinsulin gene (INS), is unique in that INS mutations can cause hyperinsulinemia, hyperproinsulinemia, neonatal diabetes mellitus, one type of maturity-onset diabetes of the young (MODY10), and autoantibody-negative T1D. Dominant heterozygous INS mutations are the second most common cause of permanent neonatal diabetes. Moreover, INS gene variants are strongly associated with common T1D (type 1a), but inconsistently with T2D. Variants of the monogenic diabetes gene Gli-similar 3 (GLIS3) are associated with both T1D and T2D. GLIS3 is a key transcription factor in insulin production and β-cell differentiation during embryonic development, which perturbation forms the basis of monogenic diabetes as well as its association with T1D. GLIS3 is also required for compensatory β-cell proliferation in adults; impairment of this function predisposes to T2D. Thus, monogenic forms of diabetes are invaluable "human models" that have contributed to our understanding of the pathophysiological basis of common T1D and T2D.
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Affiliation(s)
- Yisheng Yang
- Division of Endocrinology (Y.Y.), Department of Medicine, MetroHealth Medical Center, Case Western Reserve University, Cleveland, Ohio 44109; and Diabetes and Endocrinology Research Center (L.C.), Division of Diabetes, Endocrinology and Metabolism, Departments of Medicine, Molecular and Cellular Biology, Biochemistry and Molecular Biology, and Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas 77030
| | - Lawrence Chan
- Division of Endocrinology (Y.Y.), Department of Medicine, MetroHealth Medical Center, Case Western Reserve University, Cleveland, Ohio 44109; and Diabetes and Endocrinology Research Center (L.C.), Division of Diabetes, Endocrinology and Metabolism, Departments of Medicine, Molecular and Cellular Biology, Biochemistry and Molecular Biology, and Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas 77030
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Manaka K, Nakata M, Shimomura K, Rita RS, Maejima Y, Yoshida M, Dezaki K, Kakei M, Yada T. Chronic exposure to valproic acid promotes insulin release, reduces KATP channel current and does not affect Ca (2+) signaling in mouse islets. J Physiol Sci 2014; 64:77-83. [PMID: 24105600 PMCID: PMC10716979 DOI: 10.1007/s12576-013-0294-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2013] [Accepted: 09/20/2013] [Indexed: 12/25/2022]
Abstract
Hyperinsulinemia is one of the reported side effects of valproic acid (VPA), a medicine used to treat epilepsy. However, its underlying mechanism remains unknown. The present study was designed to investigate a direct effect of VPA on insulin secretion by using mouse pancreactic islets and β-cells. VPA had no acute effect on insulin secretion from islets, or on cytosolic Ca(2+) ([Ca(2+)]i) in single β-cells. However, following long-term exposure to VPA (48 h), both basal and glucose-stimulated insulin secretion were markedly elevated (5-fold), while the insulin gene expression level was unaltered. Following long-term exposure to VPA, β-cells showed a decrease in whole cell KATP channel current. However, the increase in [Ca(2+)]i in response to the sulfonylurea drug, tolbutamide was attenuated. The present study shows that VPA has no acute effects, but long-term treatment results in enhancement of both basal and glucose-stimulated insulin secretion. This long-term effect may mediate the KATP channel, while VPA can also attenuate the effect of the KATP channel blocker tolbutamide.
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Affiliation(s)
- Kazunori Manaka
- Division of Integrative Physiology, Department of Physiology, Jichi Medical University, School of Medicine, Yakushiji 3311-1, Shimotsuke, Tochigi 329-0498 Japan
- Ibaraki Prefectural Medical Center of Psychiatry, Kasama, Ibaraki Japan
| | - Masanori Nakata
- Division of Integrative Physiology, Department of Physiology, Jichi Medical University, School of Medicine, Yakushiji 3311-1, Shimotsuke, Tochigi 329-0498 Japan
| | - Kenju Shimomura
- Division of Integrative Physiology, Department of Physiology, Jichi Medical University, School of Medicine, Yakushiji 3311-1, Shimotsuke, Tochigi 329-0498 Japan
| | - Rauza S. Rita
- Division of Integrative Physiology, Department of Physiology, Jichi Medical University, School of Medicine, Yakushiji 3311-1, Shimotsuke, Tochigi 329-0498 Japan
| | - Yuko Maejima
- Division of Integrative Physiology, Department of Physiology, Jichi Medical University, School of Medicine, Yakushiji 3311-1, Shimotsuke, Tochigi 329-0498 Japan
| | - Masashi Yoshida
- Division of Complementary Medicine, First Department of General Medicine, Saitama Medical Center, Jichi Medical University School of Medicine, Saitama, Japan
| | - Katsuya Dezaki
- Division of Integrative Physiology, Department of Physiology, Jichi Medical University, School of Medicine, Yakushiji 3311-1, Shimotsuke, Tochigi 329-0498 Japan
| | - Masafumi Kakei
- Division of Complementary Medicine, First Department of General Medicine, Saitama Medical Center, Jichi Medical University School of Medicine, Saitama, Japan
| | - Toshihiko Yada
- Division of Integrative Physiology, Department of Physiology, Jichi Medical University, School of Medicine, Yakushiji 3311-1, Shimotsuke, Tochigi 329-0498 Japan
- Division of Adaptation Development, Department of Developmental Physiology, National Institute for Physiological Sciences, Okazaki, Aichi 444-8585 Japan
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Battaglia D, Lin YW, Brogna C, Crinò A, Grasso V, Mozzi AF, Russo L, Spera S, Colombo C, Ricci S, Nichols CG, Mercuri E, Barbetti F. Glyburide ameliorates motor coordination and glucose homeostasis in a child with diabetes associated with the KCNJ11/S225T, del226-232 mutation. Pediatr Diabetes 2012; 13:656-60. [PMID: 22694282 PMCID: PMC3747824 DOI: 10.1111/j.1399-5448.2012.00874.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/17/2011] [Revised: 04/02/2012] [Accepted: 04/02/2012] [Indexed: 11/29/2022] Open
Abstract
Gain-of-function mutations of KCNJ11 can cause permanent neonatal diabetes mellitus, but only rarely after 6 months of age. Specific uncommon mutations KCNJ11give rise to a syndrome defined as developmental delay, epilepsy, and neonatal diabetes (DEND), or - more frequently - to a milder sub-type lacking epilepsy, denoted as intermediate-DEND (iDEND). Our aim was to consider a possible monogenic etiology in a 12-yr-old boy with early onset diabetes and mild neurological features. We studied a subject diagnosed with diabetes at 21 months of age, and negative to type 1 diabetes autoantibodies testing. He had learning difficulties during primary school, and a single episode of seizures at the age of 10 yr. We performed direct DNA sequencing of the KCNJ11 gene with subsequent functional study of mutated channels in COSm6 cells. The patient's clinical response to oral glyburide (Glyb) was assessed. Motor coordination was evaluated before and after 6 and 12 months of Glyb therapy. Sequencing of the KCNJ11 gene detected the novel, spontaneous mutation S225T, combined with deletion of amino acids 226-232. In vitro studies revealed that the mutation results in a K(ATP) channel with reduced sensitivity to the inhibitory action of ATP. Glyb improved diabetes control (hemoglobin A1c on insulin: 52 mmol/mol/6.9%; on Glyb: 36 mmol/mol/5.4%) and also performance on motor coordination tests that were impaired before the switch of therapy. We conclude that KCNJ11/S225T, del226-232 mutation caused a mild iDEND form in our patient. KCNJ11 should be considered as the etiology of diabetes even beyond the neonatal period if present in combination with negative autoantibody testing and even mild neurological symptoms.
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Affiliation(s)
- Domenica Battaglia
- Child Neurology Unit, Department of Pediatrics, Sacro Cuore Catholic University, Rome, Italy
| | - Yu-Wen Lin
- Department of Cell Biology and Physiology and Center for the Investigation of Membrane Exitability Diseases, Washington University School of Medicine, St Louis, MO, USA
| | - Claudia Brogna
- Child Neurology Unit, Department of Pediatrics, Sacro Cuore Catholic University, Rome, Italy
| | - Antonino Crinò
- Autoimmune Endocrine Diseases Unit, Endocrinology Department, Bambino Gesù Children's Hospital, Research Institute Palidoro, Rome, Italy
| | - Valeria Grasso
- Laboratory of Mendelian Diabetes, Bambino Gesù Children's Hospital, Research Institute, University of Tor Vergata, Rome, Italy
| | - Alessia F Mozzi
- Department of Laboratory Medicine, University of Tor Vergata, Rome, Italy
| | - Lucia Russo
- Laboratory of Mendelian Diabetes, Bambino Gesù Children's Hospital, Research Institute, University of Tor Vergata, Rome, Italy
| | - Sabrina Spera
- Autoimmune Endocrine Diseases Unit, Endocrinology Department, Bambino Gesù Children's Hospital, Research Institute Palidoro, Rome, Italy
| | - Carlo Colombo
- Laboratory of Mendelian Diabetes, Bambino Gesù Children's Hospital, Research Institute, University of Tor Vergata, Rome, Italy
| | - Stefano Ricci
- Department of Neuroscience, Clinical Psychology Unit, Bambino Gesù Children's Hospital Research Institute, Rome, Italy
| | - Colin G Nichols
- Department of Cell Biology and Physiology and Center for the Investigation of Membrane Exitability Diseases, Washington University School of Medicine, St Louis, MO, USA
| | - Eugenio Mercuri
- Child Neurology Unit, Department of Pediatrics, Sacro Cuore Catholic University, Rome, Italy
| | - Fabrizio Barbetti
- Laboratory of Mendelian Diabetes, Bambino Gesù Children's Hospital, Research Institute, University of Tor Vergata, Rome, Italy, Department of Internal Medicine, University of Tor Vergata, Rome, Italy, Corresponding author Fabrizio Barbetti, MD, PhD Department of Internal Medicine University of Tor Vergata Viale Oxford 81 00134 Rome, Italy Tel: +39 06 2090-0672 fax: +39 06 2090-0674 ;
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Detection of KCNJ11 gene mutations in a family with neonatal diabetes mellitus: implications for therapeutic management of family members with long-standing disease. Mol Diagn Ther 2012; 16:109-14. [PMID: 22471336 DOI: 10.1007/bf03256435] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
BACKGROUND Activating mutations of potassium inwardly-rectifying channel, subfamily J, member 11 (KCNJ11), which encodes Kir6.2 (beta-cell adenosine triphosphate-sensitive potassium [K(ATP)] channel subunit), have been associated with neonatal diabetes mellitus (NDM) in different studies. Treatment with oral sulfonylureas in place of exogenous insulin injections results in improved glycemic control in most patients carrying these mutations. Exploration of genetic causes of NDM occurring before the age of 6 months has been proposed as an important issue in identification of monogenic forms of diabetes, which might be critical in their therapeutic management, as a consequence. METHODS Mutation screening of the KCNJ11 gene was carried out using PCR amplification followed by direct sequencing in three family members: the proband, ND1, diagnosed at 40 days of age (current age 7 years); his sibling, ND2, diagnosed at 2 years of age (current age 14 years); and their father, ND3, diagnosed at 15 years of age (current age 35 years), who had been exclusively treated with insulin. The effect of the E227K mutation was also examined in a homology model of Kir6.2. RESULTS Our results revealed the presence of the heterozygous missense mutation c. 679 G/A (E227K) in all three patients, who were all able to successfully transfer from insulin injections to an oral sulfonylurea, with improved glycemic control. CONCLUSION We found that three members of a family with highly variable age of onset of insulin-treated diabetes, diagnosed at 40 days, 2 years, and 15 years of age, all carried the E227K mutation in KCNJ11 and could switch to an oral sulfonylurea. This mutation has been previously reported in patients with permanent and transient NDM, as well as later-onset diabetes; this report adds to the variability in phenotypic presentation and further supports genetic testing in all diabetic members of any family affected by NDM.
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Lin YW, Akrouh A, Hsu Y, Hughes N, Nichols CG, De León DD. Compound heterozygous mutations in the SUR1 (ABCC 8) subunit of pancreatic K(ATP) channels cause neonatal diabetes by perturbing the coupling between Kir6.2 and SUR1 subunits. Channels (Austin) 2012; 6:133-8. [PMID: 22562119 DOI: 10.4161/chan.19980] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
KATP channels regulate insulin secretion by coupling β-cell metabolism to membrane excitability. These channels are comprised of a pore-forming Kir6.2 tetramer which is enveloped by four regulatory SUR1 subunits. ATP acts on Kir6.2 to stabilize the channel closed state while ADP (coordinated with Mg(2+)) activates channels via the SUR1 domains. Aberrations in nucleotide-binding or in coupling binding to gating can lead to hyperinsulinism or diabetes. Here, we report a case of diabetes in a 7-mo old child with compound heterozygous mutations in ABCC8 (SUR1[A30V] and SUR1[G296R]). In unison, these mutations lead to a gain of KATP channel function, which will attenuate the β-cell response to increased metabolism and will thereby decrease insulin secretion. (86)Rb(+) flux assays on COSm6 cells coexpressing the mutant subunits (to recapitulate the compound heterozygous state) show a 2-fold increase in basal rate of (86)Rb(+) efflux relative to WT channels. Experiments on excised inside-out patches also reveal a slight increase in activity, manifested as an enhancement in stimulation by MgADP in channels expressing the compound heterozygous mutations or homozygous G296R mutation. In addition, the IC 50 for ATP inhibition of homomeric A30V channels was increased ~6-fold, and was increased ~3-fold for both heteromeric A30V+WT channels or compound heterozygous (A30V +G296R) channels. Thus, each mutation makes a mechanistically distinct contribution to the channel gain-of-function that results in neonatal diabetes, and which we predict may contribute to diabetes in related carrier individuals.
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Affiliation(s)
- Yu-Wen Lin
- Department of Cell Biology and Physiology and Center for the Investigation of Membrane Excitability Diseases, Washington University School of Medicine, St Louis, MO, USA
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Quan Y, Barszczyk A, Feng ZP, Sun HS. Current understanding of K ATP channels in neonatal diseases: focus on insulin secretion disorders. Acta Pharmacol Sin 2011; 32:765-80. [PMID: 21602835 PMCID: PMC4009965 DOI: 10.1038/aps.2011.57] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2011] [Accepted: 04/13/2011] [Indexed: 12/25/2022] Open
Abstract
ATP-sensitive potassium (K(ATP)) channels are cell metabolic sensors that couple cell metabolic status to electric activity, thus regulating many cellular functions. In pancreatic beta cells, K(ATP) channels modulate insulin secretion in response to fluctuations in plasma glucose level, and play an important role in glucose homeostasis. Recent studies show that gain-of-function and loss-of-function mutations in K(ATP) channel subunits cause neonatal diabetes mellitus and congenital hyperinsulinism respectively. These findings lead to significant changes in the diagnosis and treatment for neonatal insulin secretion disorders. This review describes the physiological and pathophysiological functions of K(ATP) channels in glucose homeostasis, their specific roles in neonatal diabetes mellitus and congenital hyperinsulinism, as well as future perspectives of K(ATP) channels in neonatal diseases.
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Affiliation(s)
- Yi Quan
- Departments of Physiology, University of Toronto, 1 King's College Circle, Toronto, Ontario, Canada, M5S 1A8
| | - Andrew Barszczyk
- Departments of Physiology, University of Toronto, 1 King's College Circle, Toronto, Ontario, Canada, M5S 1A8
| | - Zhong-ping Feng
- Departments of Physiology, University of Toronto, 1 King's College Circle, Toronto, Ontario, Canada, M5S 1A8
| | - Hong-shuo Sun
- Departments of Physiology, University of Toronto, 1 King's College Circle, Toronto, Ontario, Canada, M5S 1A8
- Departments of Surgery, University of Toronto, 1 King's College Circle, Toronto, Ontario, Canada, M5S 1A8
- Departments of Pharmacology, University of Toronto, 1 King's College Circle, Toronto, Ontario, Canada, M5S 1A8
- Institute of Medical Science, Faculty of Medicine, University of Toronto, 1 King's College Circle, Toronto, Ontario, Canada, M5S 1A8
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Pearl EJ, Jarikji Z, Horb ME. Functional analysis of Rfx6 and mutant variants associated with neonatal diabetes. Dev Biol 2011; 351:135-45. [PMID: 21215266 DOI: 10.1016/j.ydbio.2010.12.043] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2010] [Revised: 12/13/2010] [Accepted: 12/23/2010] [Indexed: 11/30/2022]
Abstract
Mutations in rfx6 were recently associated with Mitchell-Riley syndrome, which involves neonatal diabetes, and other digestive system defects. To better define the function of Rfx6 in early endoderm development we cloned the Xenopus homologue. Expression of rfx6 begins early, showing broad expression throughout the anterior endoderm; at later stages rfx6 expression becomes restricted to the endocrine cells of the gut and pancreas. Morpholino knockdown of rfx6 caused a loss of pancreas marker expression, as well as other abnormalities. Co-injection of exogenous wild-type rfx6 rescued the morpholino phenotype in Xenopus tadpoles, whereas attempts to rescue the loss-of-function phenotype using mutant rfx6 based on Mitchell-Riley patients were unsuccessful. To better define the pleiotropic effects, we performed microarray analyses of gene expression in knockdown foregut tissue. In addition to pancreatic defects, the microarray analyses revealed downregulation of lung, stomach and heart markers and an upregulation of kidney markers. We verified these results using RT-PCR and in situ hybridization. Based on the different rfx6 expression patterns and our functional analyses, we propose that rfx6 has both early and late functions. In early development Rfx6 plays a broad role, being essential for development of most anterior endodermal organs. At later stages however, Rfx6 function is restricted to endocrine cells.
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Affiliation(s)
- Esther J Pearl
- Laboratory of Molecular Organogenesis, Institut de recherches cliniques de Montréal, 110 avenue des Pins Ouest, Montreal, QC H2V4K1, Canada.
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13
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Edghill EL, Flanagan SE, Ellard S. Permanent neonatal diabetes due to activating mutations in ABCC8 and KCNJ11. Rev Endocr Metab Disord 2010; 11:193-8. [PMID: 20922570 DOI: 10.1007/s11154-010-9149-x] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The ATP-sensitive potassium (K(ATP)) channel is composed of two subunits SUR1 and Kir6.2. The channel is key for glucose stimulated insulin release from the pancreatic beta cell. Activating mutations have been identified in the genes encoding these subunits, ABCC8 and KCNJ11, and account for approximately 40% of permanent neonatal diabetes cases. The majority of patients with a K(ATP) mutation present with isolated diabetes however some have presented with the Developmental delay, Epilepsy and Neonatal Diabetes syndrome. This review focuses on mutations in the K(ATP) channel which result in permanent neonatal diabetes, we review the clinical and functional effects as well as the implications for treatment.
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MESH Headings
- ATP-Binding Cassette Transporters/genetics
- ATP-Binding Cassette Transporters/metabolism
- ATP-Binding Cassette Transporters/physiology
- Diabetes Mellitus/congenital
- Diabetes Mellitus/genetics
- Diabetes Mellitus/therapy
- Genetic Association Studies
- Humans
- Infant, Newborn
- Infant, Newborn, Diseases/genetics
- Infant, Newborn, Diseases/therapy
- KATP Channels/genetics
- KATP Channels/metabolism
- KATP Channels/physiology
- Models, Biological
- Mutation/physiology
- Potassium Channels, Inwardly Rectifying/genetics
- Potassium Channels, Inwardly Rectifying/metabolism
- Potassium Channels, Inwardly Rectifying/physiology
- Receptors, Drug/genetics
- Receptors, Drug/metabolism
- Receptors, Drug/physiology
- Sulfonylurea Receptors
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Affiliation(s)
- Emma L Edghill
- Institute of Biomedical and Clinical Science, Peninsula College of Medicine and Dentistry, University of Exeter, Barrack Road, Exeter, UK
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14
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Dhanvantari S. Unfolding the mechanisms of disease progression in permanent neonatal diabetes. Am J Physiol Endocrinol Metab 2010; 298:E383-4. [PMID: 20051530 DOI: 10.1152/ajpendo.00757.2009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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15
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Huang K. A K+ channel that channels neurology to nephrology. Clin Genet 2010; 77:230-1. [DOI: 10.1111/j.1399-0004.2009.01322.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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