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Le Ribeuz H, Capuano V, Girerd B, Humbert M, Montani D, Antigny F. Implication of Potassium Channels in the Pathophysiology of Pulmonary Arterial Hypertension. Biomolecules 2020; 10:biom10091261. [PMID: 32882918 PMCID: PMC7564204 DOI: 10.3390/biom10091261] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 08/24/2020] [Accepted: 08/27/2020] [Indexed: 02/06/2023] Open
Abstract
Pulmonary arterial hypertension (PAH) is a rare and severe cardiopulmonary disease without curative treatments. PAH is a multifactorial disease that involves genetic predisposition, epigenetic factors, and environmental factors (drugs, toxins, viruses, hypoxia, and inflammation), which contribute to the initiation or development of irreversible remodeling of the pulmonary vessels. The recent identification of loss-of-function mutations in KCNK3 (KCNK3 or TASK-1) and ABCC8 (SUR1), or gain-of-function mutations in ABCC9 (SUR2), as well as polymorphisms in KCNA5 (Kv1.5), which encode two potassium (K+) channels and two K+ channel regulatory subunits, has revived the interest of ion channels in PAH. This review focuses on KCNK3, SUR1, SUR2, and Kv1.5 channels in pulmonary vasculature and discusses their pathophysiological contribution to and therapeutic potential in PAH.
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Affiliation(s)
- Hélène Le Ribeuz
- Faculté de Médecine, Université Paris-Saclay, 94270 Le Kremlin-Bicêtre, France; (H.L.R.); (V.C.); (B.G.); (M.H.); (D.M.)
- INSERM UMR_S 999, Hypertension pulmonaire, Physiopathologie et Innovation Thérapeutique, Hôpital Marie Lannelongue, 92350 Le Plessis-Robinson, France
- Assistance Publique—Hôpitaux de Paris (AP-HP), Service de Pneumologie et Soins Intensifs Respiratoires, Centre de Référence de l’Hypertension Pulmonaire, Hôpital Bicêtre, 94270 Le Kremlin-Bicêtre, France
| | - Véronique Capuano
- Faculté de Médecine, Université Paris-Saclay, 94270 Le Kremlin-Bicêtre, France; (H.L.R.); (V.C.); (B.G.); (M.H.); (D.M.)
- INSERM UMR_S 999, Hypertension pulmonaire, Physiopathologie et Innovation Thérapeutique, Hôpital Marie Lannelongue, 92350 Le Plessis-Robinson, France
- Assistance Publique—Hôpitaux de Paris (AP-HP), Service de Pneumologie et Soins Intensifs Respiratoires, Centre de Référence de l’Hypertension Pulmonaire, Hôpital Bicêtre, 94270 Le Kremlin-Bicêtre, France
| | - Barbara Girerd
- Faculté de Médecine, Université Paris-Saclay, 94270 Le Kremlin-Bicêtre, France; (H.L.R.); (V.C.); (B.G.); (M.H.); (D.M.)
- INSERM UMR_S 999, Hypertension pulmonaire, Physiopathologie et Innovation Thérapeutique, Hôpital Marie Lannelongue, 92350 Le Plessis-Robinson, France
- Assistance Publique—Hôpitaux de Paris (AP-HP), Service de Pneumologie et Soins Intensifs Respiratoires, Centre de Référence de l’Hypertension Pulmonaire, Hôpital Bicêtre, 94270 Le Kremlin-Bicêtre, France
| | - Marc Humbert
- Faculté de Médecine, Université Paris-Saclay, 94270 Le Kremlin-Bicêtre, France; (H.L.R.); (V.C.); (B.G.); (M.H.); (D.M.)
- INSERM UMR_S 999, Hypertension pulmonaire, Physiopathologie et Innovation Thérapeutique, Hôpital Marie Lannelongue, 92350 Le Plessis-Robinson, France
- Assistance Publique—Hôpitaux de Paris (AP-HP), Service de Pneumologie et Soins Intensifs Respiratoires, Centre de Référence de l’Hypertension Pulmonaire, Hôpital Bicêtre, 94270 Le Kremlin-Bicêtre, France
| | - David Montani
- Faculté de Médecine, Université Paris-Saclay, 94270 Le Kremlin-Bicêtre, France; (H.L.R.); (V.C.); (B.G.); (M.H.); (D.M.)
- INSERM UMR_S 999, Hypertension pulmonaire, Physiopathologie et Innovation Thérapeutique, Hôpital Marie Lannelongue, 92350 Le Plessis-Robinson, France
- Assistance Publique—Hôpitaux de Paris (AP-HP), Service de Pneumologie et Soins Intensifs Respiratoires, Centre de Référence de l’Hypertension Pulmonaire, Hôpital Bicêtre, 94270 Le Kremlin-Bicêtre, France
| | - Fabrice Antigny
- Faculté de Médecine, Université Paris-Saclay, 94270 Le Kremlin-Bicêtre, France; (H.L.R.); (V.C.); (B.G.); (M.H.); (D.M.)
- INSERM UMR_S 999, Hypertension pulmonaire, Physiopathologie et Innovation Thérapeutique, Hôpital Marie Lannelongue, 92350 Le Plessis-Robinson, France
- Assistance Publique—Hôpitaux de Paris (AP-HP), Service de Pneumologie et Soins Intensifs Respiratoires, Centre de Référence de l’Hypertension Pulmonaire, Hôpital Bicêtre, 94270 Le Kremlin-Bicêtre, France
- Correspondence: or ; Tel.: +33-1-40-94-22-99
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Zhang M, Yang M, Wang N, Liu Q, Wang B, Huang T, Tong Y, Ming Y, Wong CW, Liu J, Yao D, Guan M. Andrographolide modulates HNF4α activity imparting on hepatic metabolism. Mol Cell Endocrinol 2020; 513:110867. [PMID: 32422400 DOI: 10.1016/j.mce.2020.110867] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Revised: 05/09/2020] [Accepted: 05/10/2020] [Indexed: 12/28/2022]
Abstract
Hepatic nuclear factor 4 alpha (HNF4α) drives the expression of apolipoprotein B (ApoB), microsomal triglyceride transfer protein (MTP) and phospholipase A2 G12B (PLA2G12B), governing hepatic very-low-density lipoprotein (VLDL) production and secretion. Andrographolide (AP) is a major constituent isolated from Andrographis paniculata. We found that AP can disrupt the interaction between HNF4α and its coactivator peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC1α). Virtual docking and mutational analysis indicated that arginine 235 of HNF4α is essential for binding to AP. As a consequence of antagonizing the activity of HNF4α, AP suppresses the expression of ApoB, MTP and PLA2G12B and reduces the rate of hepatic VLDL secretion in vivo. AP additionally reduced gluconeogenesis via down-regulating the expression of HNF4α target genes phosphoenolpyruvate carboxykinase (Pepck) and glucose-6-phosphatase (G6pc). Collectively, our results suggest that AP affects liver function via modulating the transcriptional activity of HNF4α.
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Affiliation(s)
- Minyi Zhang
- National Engineering Research Center of Genetic Medicine, Institute of Biomedicine, Jinan University, Guangzhou, 510632, Guangdong, China; Institute of Biomedicine and Biotechnology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, Guangdong, China
| | - Meng Yang
- Institute of Biomedicine and Biotechnology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, Guangdong, China
| | - Na Wang
- Guangdong Provincial Key Laboratory of Biocomputing, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou, 510530, China
| | - Qingli Liu
- Institute of Biomedicine and Biotechnology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, Guangdong, China
| | - Binxu Wang
- Institute of Biomedicine and Biotechnology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, Guangdong, China
| | - Tongling Huang
- Institute of Biomedicine and Biotechnology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, Guangdong, China
| | - Yan Tong
- Institute of Chemical Engineering, Huaqiao University, Xiamen, Fujian, 361021, China
| | - Yanlin Ming
- Institute of Chemical Engineering, Huaqiao University, Xiamen, Fujian, 361021, China
| | - Chi-Wai Wong
- NeuMed Pharmaceuticals Limited, Yuen Long, Hong Kong, China
| | - Jinsong Liu
- Guangdong Provincial Key Laboratory of Biocomputing, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou, 510530, China
| | - Dongsheng Yao
- National Engineering Research Center of Genetic Medicine, Institute of Biomedicine, Jinan University, Guangzhou, 510632, Guangdong, China.
| | - Min Guan
- Institute of Biomedicine and Biotechnology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, Guangdong, China.
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Ros-Pérez P, Golmayo L, Cilleruelo ML, Gutiérrez C, Celaya P, Lacámara N, Martínez-Badás I, Güemes M, Argente J. Octreotide-related exocrine pancreatic insufficiency (EPI) in congenital hyperinsulinism. J Pediatr Endocrinol Metab 2020; 33:947-950. [PMID: 32634108 DOI: 10.1515/jpem-2019-0565] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/11/2020] [Accepted: 04/09/2020] [Indexed: 12/22/2022]
Abstract
Background Congenital hyperinsulinism (CH) is the most frequent cause of persistent hypoglycemia in the newborn. Octreotide, a long-acting somatostatin receptor analog (SSRA), is a second line treatment for diazoxide unresponsive CH patients. Although it has been found to be a safe and effective treatment, long-term benefits and side effects, have not been thoroughly evaluated. Case presentation Some authors have indicated that exocrine pancreatic insufficiency (EPI) is a common but under-recognized adverse reaction in adults treated with octreotide. However, no pediatric patient with SSRA-induced EPI has been reported to date. Here we report a case of an infant with diazoxide unresponsive, diffuse CH, caused by a heterozygous pathogenic paternally inherited mutation in the ABCC8 gene (NM_000352.4:c.357del), that developed exocrine pancreatic insufficiency and secondary vitamin K deficiency associated to chronic octreotide therapy. Conclusions We point out the atypical clinical onset with a cutaneous hemorrhagic syndrome, emphasizing the clinical relevance of this potential side effect.
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Affiliation(s)
- Purificación Ros-Pérez
- Department of Pediatrics, Hospital Universitario Puerta de Hierro-Majadahonda, Madrid, Spain
- Department of Pediatrics, Universidad Autónoma de Madrid, Madrid, Spain
| | - Luz Golmayo
- Department of Pediatrics, Hospital Universitario Puerta de Hierro-Majadahonda, Madrid, Spain
| | - María L Cilleruelo
- Department of Pediatrics, Hospital Universitario Puerta de Hierro-Majadahonda, Madrid, Spain
- Department of Pediatrics, Universidad Autónoma de Madrid, Madrid, Spain
| | - Carolina Gutiérrez
- Department of Pediatrics, Hospital Universitario Puerta de Hierro-Majadahonda, Madrid, Spain
- Department of Pediatrics, Universidad Autónoma de Madrid, Madrid, Spain
| | - Patricia Celaya
- Department of Pediatrics, Hospital Universitario Puerta de Hierro-Majadahonda, Madrid, Spain
| | - Nerea Lacámara
- Department of Pediatrics, Hospital Universitario Puerta de Hierro-Majadahonda, Madrid, Spain
| | - Itziar Martínez-Badás
- Department of Pediatrics, Hospital Universitario Puerta de Hierro-Majadahonda, Madrid, Spain
| | - María Güemes
- Department of Endocrinology, Hospital Infantil Universitario Niño Jesús, Madrid, Spain
- Centro de Investigación Biomédica en Red de obesidad y nutrición (CIBEROBN), Instituto de Salud Carlos III, Madrid, Spain
| | - Jesús Argente
- Department of Pediatrics, Universidad Autónoma de Madrid, Madrid, Spain
- Department of Endocrinology, Hospital Infantil Universitario Niño Jesús, Madrid, Spain
- Centro de Investigación Biomédica en Red de obesidad y nutrición (CIBEROBN), Instituto de Salud Carlos III, Madrid, Spain
- Instituto de Investigación la Princesa, Madrid, Spain
- IMDEA Food Institute, Campus of International Excellence (CEI) UAM + CSIC, Madrid, Spain
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Congenital hyperinsulinism: management and outcome, a single tertiary centre experience. Eur J Pediatr 2020; 179:947-952. [PMID: 32002613 DOI: 10.1007/s00431-020-03581-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/27/2019] [Revised: 01/09/2020] [Accepted: 01/15/2020] [Indexed: 10/25/2022]
Abstract
Hyperinsulinemic hypoglycaemia (HH) is the most frequent cause of persistent hypoglycaemia in neonates and infants. The most severe forms of HH are inherited and referred to as congenital hyperinsulinism (CHI). Diazoxide is the mainstay of treatment, with surgery being an option in appropriate cases. To describe the management and outcome of patients with CHI within our service. Children referred to or attending HH clinic between 2009 and 2017 were identified. Clinical course, genetics and interventions were documented. A total of 39 children were identified, and seven patients with secondary and syndromic HH were excluded. Most were born with an appropriate weight for gestational age (62.5%). Diazoxide was started in all patients; however, 7 did not respond and required octreotide/continuous feeding, with 6/7 requiring surgery. Genetic mutations were detected in 12/32 (37.5%). Hyperinsulinism resolved in conservatively treated patients within 12 months in 11/32 (34.3%) compared to 14/32 (43.7%) requiring more than 12 months of medication. A total of 7 patients underwent pancreatectomy.Conclusion: Although LGA and SGA are risk factors, most babies in our cohort are born AGA. A genetic mutation does not exclude medical remission; long-term conservative treatment of CHI is feasible as surgery does not guarantee complete remission.What is Known:•Congenital hyperinsulinism (CHI) is a clinically and genetically heterogeneous disorder that is the most common cause of permanent hypoglycaemia in infants and children.•Identification of genetic mutations and the use of 18F-DOPA PET scan when feasible lead to better outcomes.What is New:•The study describes clinical criteria, management and outcome of large number of patients with CHI in single tertiary centre.•Conservative treatment is feasible without the need for surgery, with HH resolving in over 30% within 12 months, irrespective of genetic mutation.
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Taylor-Miller T, Houghton J, Munyard P, Kumar Y, Puvirajasinghe C, Giri D. Congenital hyperinsulinism due to compound heterozygous mutations in ABCC8 responsive to diazoxide therapy. J Pediatr Endocrinol Metab 2020; 33:671-674. [PMID: 32267248 DOI: 10.1515/jpem-2019-0457] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Accepted: 02/18/2020] [Indexed: 11/15/2022]
Abstract
Background Congenital hyperinsulinism (CHI), a condition characterized by dysregulation of insulin secretion from the pancreatic β cells, remains one of the most common causes of hyperinsulinemic, hypoketotic hypoglycemia in the newborn period. Mutations in ABCC8 and KCNJ11 constitute the majority of genetic forms of CHI. Case presentation A term macrosomic male baby, birth weight 4.81 kg, born to non-consanguineous parents, presented on day 1 of life with severe and persistent hypoglycemia. The biochemical investigations confirmed a diagnosis of CHI. Diazoxide was started and progressively increased to 15 mg/kg/day to maintain normoglycemia. Sequence analysis identified compound heterozygous mutations in ABCC8 c.4076C>T and c.4119+1G>A inherited from the unaffected father and mother, respectively. The mutations are reported pathogenic. The patient is currently 7 months old with a sustained response to diazoxide. Conclusions Biallelic ABCC8 mutations are known to result in severe, diffuse, diazoxide-unresponsive hypoglycemia. We report a rare patient with CHI due to compound heterozygous mutations in ABCC8 responsive to diazoxide.
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Affiliation(s)
- Tashunka Taylor-Miller
- Department of Paediatric Endocrinology, Bristol Royal Hospital for Children, Bristol, UK
| | - Jayne Houghton
- Department of Molecular Genetics, University of Exeter Medical School, Exeter, UK
| | - Paul Munyard
- Department of Paediatrics, Royal Cornwall Hospitals NHS Trust, Truro, UK
| | - Yadlapalli Kumar
- Department of Paediatrics, Royal Cornwall Hospitals NHS Trust, Truro, UK
| | - Clinda Puvirajasinghe
- Great Ormond Street Hospital for Children NHS Foundation Trust, Rare and Inherited Disease Laboratory, North London Genomic Laboratory Hub, London, UK
| | - Dinesh Giri
- Consultant Paediatric Endocrinologist and Honorary Senior Lecturer, Bristol Royal Hospital for Children and University of Bristol, Bristol BS2 8BJ, UK.,Department of Paediatric Endocrinology, Department of Translational Health Sciences, University of Bristol, Bristol, UK
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Spontaneous Resolution of Congenital Hyperinsulinism With Octreotide Therapy. Indian Pediatr 2020. [DOI: 10.1007/s13312-020-1829-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Davidov AS, Elkon-Tamir E, Haham A, Shefer G, Weintrob N, Oren A, Lebenthal Y, Mandel D, Eyal O. Higher C-peptide levels and glucose requirements may identify neonates with transient hyperinsulinism hypoglycemia who will benefit from diazoxide treatment. Eur J Pediatr 2020; 179:597-602. [PMID: 31863303 DOI: 10.1007/s00431-019-03544-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/23/2019] [Revised: 12/02/2019] [Accepted: 12/04/2019] [Indexed: 02/05/2023]
Abstract
The aim of the study was to characterize factors that may serve as clinical tools to identify neonates with transient neonatal hyperinsulinism hypoglycemia (HH) who may benefit from diazoxide treatment. This retrospective study included 141 neonates with transient HH (93 males) of whom 34 (24%) were treated with diazoxide. Diazoxide treatment was started at median age of 13 days (range 5-35) and discontinued at median age of 42 days (range 14-224). The maximal dose was 7.1 ± 2.3 mg/kg/day. Diazoxide-treated neonates required a higher glucose infusion rate (GIR) compared with non-treated neonates (16.6 ± 3.4 vs. 10.4 ± 4.0 mg/kg/min, respectively, P < .01), had a longer duration of intravenous fluids (15.9 ± 9.3 vs. 7.8 ± 6.5 days, P < .01), a longer hospitalization (32.8 ± 22.7 vs. 20.4 ± 13.4 days, P < .01), a longer duration of carbohydrate supplementation (38.9 ± 40.4 vs. 17.8 ± 21.4 days, P < .01), and higher mean C-peptide levels on "critical sample" (1.4 ± 0.9 vs. 0.8 ± 0.5 ng/ml, P < .01). Their insulin levels also tended to be higher (3.5 ± 2.9 vs. 2.2 ± 3.8 μU/ml, P = .07). A stepwise logistic regression model revealed that significant predictors of prolonged HH were maximal GIRs (odds ratio (OR) 1.56, 95%; confidence interval (CI) 1.3-1.88, P < .001) and C-peptide levels (OR 3.57, 95%; CI 1.3-12.1, P = .005).Conclusion: Higher C-peptide levels and higher GIR requirements may serve as clinical tools to identify neonates with transient HH who may benefit from diazoxide treatment.What is Known:• Neonates with transient hyperinsulinism usually do not require treatment beyond glucose supplementation due to its self-limited clinical course, but some may benefit from diazoxide treatment.What is New:• Higher C-peptide levels and higher GIR requirements may serve as clinical tools to identify neonates with transient HH who may benefit from diazoxide treatment.• The incidence of prolonged neonatal HH is higher than the currently accepted figures.
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Affiliation(s)
- Anita Schachter Davidov
- Pediatric Endocrinology and Diabetes Unit, Dana-Dwek Children's Hospital, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel.,Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Erella Elkon-Tamir
- Pediatric Endocrinology and Diabetes Unit, Dana-Dwek Children's Hospital, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel.,Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Alon Haham
- Department of Neonatology, Dana-Dwek Children's Hospital, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel.,Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Gabi Shefer
- Institute of Endocrinology, Metabolism and Hypertension, Tel Aviv Sourasky Medical Center, , Tel Aviv, Israel.,Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Naomi Weintrob
- Pediatric Endocrinology and Diabetes Unit, Dana-Dwek Children's Hospital, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel.,Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Asaf Oren
- Pediatric Endocrinology and Diabetes Unit, Dana-Dwek Children's Hospital, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel.,Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Yael Lebenthal
- Pediatric Endocrinology and Diabetes Unit, Dana-Dwek Children's Hospital, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel.,Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Dror Mandel
- Department of Neonatology, Dana-Dwek Children's Hospital, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel.,Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Ori Eyal
- Pediatric Endocrinology and Diabetes Unit, Dana-Dwek Children's Hospital, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel. .,Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel.
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Luczkowska K, Stekelenburg C, Sloan-Béna F, Ranza E, Gastaldi G, Schwitzgebel V, Maechler P. Hyperinsulinism associated with GLUD1 mutation: allosteric regulation and functional characterization of p.G446V glutamate dehydrogenase. Hum Genomics 2020; 14:9. [PMID: 32143698 PMCID: PMC7060525 DOI: 10.1186/s40246-020-00262-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Accepted: 03/02/2020] [Indexed: 12/19/2022] Open
Abstract
Background Gain-of-function mutations in the GLUD1 gene, encoding for glutamate dehydrogenase (GDH), result in the hyperinsulinism/hyperammonemia HI/HA syndrome. HI/HA patients present with harmful hypoglycemia secondary to protein-induced HI and elevated plasma ammonia levels. These symptoms may be accompanied by seizures and mental retardation. GDH is a mitochondrial enzyme that catalyzes the oxidative deamination of glutamate to α-ketoglutarate, under allosteric regulations mediated by its inhibitor GTP and its activator ADP. The present study investigated the functional properties of the GDH-G446V variant (alias c.1496G > T, p.(Gly499Val) (NM_005271.4)) in patient-derived lymphoblastoid cells. Results The calculated energy barrier between the opened and closed state of the enzyme was 41% lower in GDH-G446V compared to wild-type GDH, pointing to altered allosteric regulation. Computational analysis indicated conformational changes of GDH-G446V in the antenna region that is crucial for allosteric regulators. Enzymatic activity measured in patient-derived lymphoblastoid cells showed impaired allosteric responses of GDH-G446V to both regulators GTP and ADP. In particular, as opposed to control lymphoblastoid cells, GDH-G446V cells were not responsive to GTP in the lower range of ADP concentrations. Assessment of the metabolic rate revealed higher mitochondrial respiration in response to GDH-dependent substrates in the GDH-G446V lymphoblastoid cells compared to control cells. This indicates a shift toward glutaminolysis for energy provision in cells carrying the GDH-G446V variant. Conclusions Substitution of the small amino acid glycine for the hydrophobic branched-chain valine altered the allosteric sensitivity to both inhibitory action of GTP and activation by ADP, rendering cells metabolically responsive to glutamine.
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Affiliation(s)
- Karolina Luczkowska
- Department of Cell Physiology and Metabolism, University of Geneva Medical Center, 1206, Geneva, Switzerland.,Faculty Diabetes Center, University of Geneva Medical Center, 1206, Geneva, Switzerland
| | - Caroline Stekelenburg
- Faculty Diabetes Center, University of Geneva Medical Center, 1206, Geneva, Switzerland.,Pediatric Endocrine and Diabetes Unit, Department of Pediatrics Gynecology and Obstetrics, University Hospitals of Geneva, Geneva, Switzerland
| | - Frédérique Sloan-Béna
- Department of Genetic Medicine and Development, Faculty of Medicine, University of Geneva, 1211, Geneva, Switzerland.,Department of Genetic Medicine and Laboratory, University Hospitals of Geneva, 1211, Geneva, Switzerland
| | - Emmanuelle Ranza
- Department of Genetic Medicine and Laboratory, University Hospitals of Geneva, 1211, Geneva, Switzerland
| | - Giacomo Gastaldi
- Faculty Diabetes Center, University of Geneva Medical Center, 1206, Geneva, Switzerland.,Division of Endocrinology, Diabetology, Hypertension and Nutrition, Geneva University Hospitals, 1211, Geneva, Switzerland
| | - Valérie Schwitzgebel
- Faculty Diabetes Center, University of Geneva Medical Center, 1206, Geneva, Switzerland.,Pediatric Endocrine and Diabetes Unit, Department of Pediatrics Gynecology and Obstetrics, University Hospitals of Geneva, Geneva, Switzerland
| | - Pierre Maechler
- Department of Cell Physiology and Metabolism, University of Geneva Medical Center, 1206, Geneva, Switzerland. .,Faculty Diabetes Center, University of Geneva Medical Center, 1206, Geneva, Switzerland.
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Whitticar NB, Nunemaker CS. Reducing Glucokinase Activity to Enhance Insulin Secretion: A Counterintuitive Theory to Preserve Cellular Function and Glucose Homeostasis. Front Endocrinol (Lausanne) 2020; 11:378. [PMID: 32582035 PMCID: PMC7296051 DOI: 10.3389/fendo.2020.00378] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Accepted: 05/12/2020] [Indexed: 12/21/2022] Open
Abstract
Pancreatic beta-cells are the only cells in the body that can synthesize and secrete insulin. Through the process of glucose-stimulated insulin secretion, beta-cells release insulin into circulation, stimulating GLUT4-dependent glucose uptake into peripheral tissue. Insulin is normally secreted in pulses that promote signaling at the liver. Long before type 2 diabetes is diagnosed, beta-cells become oversensitive to glucose, causing impaired pulsatility and overstimulation in fasting levels of glucose. The resulting hypersecretion of insulin can cause poor insulin signaling and clearance at the liver, leading to hyperinsulinemia and insulin resistance. Continued overactivity can eventually lead to beta-cell exhaustion and failure at which point type 2 diabetes begins. To prevent or reverse the negative effects of overstimulation, beta-cell activity can be reduced. Clinical studies have revealed the potential of beta-cell rest to reverse new cases of diabetes, but treatments lack durable benefits. In this perspective, we propose an intervention that reduces overactive glucokinase activity in the beta-cell. Glucokinase is known as the glucose sensor of the beta-cell due to its high control over insulin secretion. Therefore, glycolytic overactivity may be responsible for hyperinsulinemia early in the disease and can be reduced to restore normal stimulus-secretion coupling. We have previously reported that reducing glucokinase activity in prediabetic mouse islets can restore pulsatility and enhance insulin secretion. Building on this counterintuitive finding, we review the importance of pulsatile insulin secretion and highlight how normalizing glucose sensing in the beta cell during prediabetic hyperinsulinemia may restore pulsatility and improve glucose homeostasis.
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Affiliation(s)
- Nicholas B. Whitticar
- Translational Biomedical Sciences Program, Graduate College, Ohio University, Athens, OH, United States
- Diabetes Institute, Heritage College of Osteopathic Medicine, Ohio University, Athens OH, United States
- Department of Biomedical Sciences, Heritage College of Osteopathic Medicine, Ohio University, Athens, OH, United States
| | - Craig S. Nunemaker
- Diabetes Institute, Heritage College of Osteopathic Medicine, Ohio University, Athens OH, United States
- Department of Biomedical Sciences, Heritage College of Osteopathic Medicine, Ohio University, Athens, OH, United States
- *Correspondence: Craig S. Nunemaker
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Sikimic J, Hoffmeister T, Gresch A, Kaiser J, Barthlen W, Wolke C, Wieland I, Lendeckel U, Krippeit-Drews P, Düfer M, Drews G. Possible New Strategies for the Treatment of Congenital Hyperinsulinism. Front Endocrinol (Lausanne) 2020; 11:545638. [PMID: 33193079 PMCID: PMC7653201 DOI: 10.3389/fendo.2020.545638] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/25/2020] [Accepted: 10/02/2020] [Indexed: 01/21/2023] Open
Abstract
OBJECTIVE Congenital hyperinsulinism (CHI) is a rare disease characterized by persistent hypoglycemia as a result of inappropriate insulin secretion, which can lead to irreversible neurological defects in infants. Poor efficacy and strong adverse effects of the current medications impede successful treatment. The aim of the study was to investigate new approaches to silence β-cells and thus attenuate insulin secretion. RESEARCH DESIGN AND METHODS In the scope of our research, we tested substances more selective and more potent than the gold standard diazoxide that also interact with neuroendocrine ATP-sensitive K+ (KATP) channels. Additionally, KATP channel-independent targets as Ca2+-activated K+ channels of intermediate conductance (KCa3.1) and L-type Ca2+ channels were investigated. Experiments were performed using human islet cell clusters isolated from tissue of CHI patients (histologically classified as pathological) and islet cell clusters obtained from C57BL/6N (WT) or SUR1 knockout (SUR1-/-) mice. The cytosolic Ca2+ concentration ([Ca2+]c) was used as a parameter for the pathway regulated by electrical activity and was determined by fura-2 fluorescence. The mitochondrial membrane potential (ΔΨ) was determined by rhodamine 123 fluorescence and single channel currents were measured by the patch-clamp technique. RESULTS The selective KATP channel opener NN414 (5 µM) diminished [Ca2+]c in isolated human CHI islet cell clusters and WT mouse islet cell clusters stimulated with 10 mM glucose. In islet cell clusters lacking functional KATP channels (SUR1-/-) the drug was without effect. VU0071063 (30 µM), another KATP channel opener considered to be selective, lowered [Ca2+]c in human CHI islet cell clusters. The compound was also effective in islet cell clusters from SUR1-/- mice, showing that [Ca2+]c is influenced by additional effects besides KATP channels. Contrasting to NN414, the drug depolarized ΔΨ in murine islet cell clusters pointing to severe interference with mitochondrial metabolism. An opener of KCa3.1 channels, DCEBIO (100 µM), significantly decreased [Ca2+]c in SUR1-/- and human CHI islet cell clusters. To target L-type Ca2+ channels we tested two already approved drugs, dextromethorphan (DXM) and simvastatin. DXM (100 µM) efficiently diminished [Ca2+]c in stimulated human CHI islet cell clusters as well as in stimulated SUR1-/- islet cell clusters. Similar effects on [Ca2+]c were observed in experiments with simvastatin (7.2 µM). CONCLUSIONS NN414 seems to provide a good alternative to the currently used KATP channel opener diazoxide. Targeting KCa3.1 channels by channel openers or L-type Ca2+ channels by DXM or simvastatin might be valuable approaches for treatment of CHI caused by mutations of KATP channels not sensitive to KATP channel openers.
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Affiliation(s)
- Jelena Sikimic
- Department of Pharmacology, Institute of Pharmacy, University of Tübingen, Tübingen, Germany
| | - Theresa Hoffmeister
- Department of Pharmacology, Institute of Pharmaceutical and Medicinal Chemistry, University of Münster, Münster, Germany
| | - Anne Gresch
- Department of Pharmacology, Institute of Pharmaceutical and Medicinal Chemistry, University of Münster, Münster, Germany
| | - Julia Kaiser
- Department of Pharmacology, Institute of Pharmacy, University of Tübingen, Tübingen, Germany
| | - Winfried Barthlen
- Department of Pediatric Surgery, University Medicine Greifswald, Greifswald, Germany
| | - Carmen Wolke
- Institute of Medical Biochemistry and Molecular Biology, University Medicine Greifswald, Greifswald, Germany
| | - Ilse Wieland
- Institute of Human Genetics, University Hospital Magdeburg, Magdeburg, Germany
| | - Uwe Lendeckel
- Institute of Medical Biochemistry and Molecular Biology, University Medicine Greifswald, Greifswald, Germany
| | - Peter Krippeit-Drews
- Department of Pharmacology, Institute of Pharmacy, University of Tübingen, Tübingen, Germany
- *Correspondence: Peter Krippeit-Drews,
| | - Martina Düfer
- Department of Pharmacology, Institute of Pharmaceutical and Medicinal Chemistry, University of Münster, Münster, Germany
| | - Gisela Drews
- Department of Pharmacology, Institute of Pharmacy, University of Tübingen, Tübingen, Germany
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