scholarly journals Phenotype of a transient neonatal diabetes point mutation (SUR1-R1183W) in mice

2020 ◽  
Vol 5 ◽  
pp. 15
Author(s):  
Gregor Sachse ◽  
Elizabeth Haythorne ◽  
Peter Proks ◽  
Michelle Stewart ◽  
Heather Cater ◽  
...  
Keyword(s):  
Insulin Secretion ◽  
Blood Glucose ◽  
Beta Cells ◽  
Glucose Homeostasis ◽  
Pancreatic Beta Cells ◽  
Constitutive Expression ◽  
Neonatal Diabetes ◽  
Gain Of Function ◽  
Human Phenotype ◽  
Transient Neonatal Diabetes

Background: The KATP channel plays a key role in glucose homeostasis by coupling metabolically generated changes in ATP to insulin secretion from pancreatic beta-cells.  Gain-of-function mutations in either the pore-forming (Kir6.2) or regulatory (SUR1) subunit of this channel are a common cause of transient neonatal diabetes mellitus (TNDM), in which diabetes presents shortly after birth but remits within the first few years of life, only to return in later life. The reasons behind this time dependence are unclear. Methods: In an attempt to understand the mechanism behind diabetes remission and relapse, we generated mice expressing the common TNDM mutation SUR1-R1183W. We employed Cre/LoxP technology for both inducible and constitutive expression of SUR1-R1183W specifically in mouse beta-cells, followed by investigation of their phenotype using glucose tolerance tests and insulin secretion from isolated islets.  Results: We found that the R1183W mutation impaired inhibition of KATP channels by ATP when heterologously expressed in human embryonic kidney cells. However, neither induced nor constitutive expression of SUR1-R1183W in mice resulted in changes in blood glucose homeostasis, compared to littermate controls. When challenged with a high fat diet, female mice expressing SUR1-R1183W showed increased weight gain, elevated blood glucose and impaired glycaemic control, but glucose-stimulated insulin secretion from pancreatic islets appeared unchanged. Conclusions: The mouse model of TNDM did not recapitulate the human phenotype. We discuss multiple potential reasons why this might be the case. Based on our findings, we recommend future TNDM mouse models employing a gain-of-function SUR1 mutation should be created using the minimally invasive CRISPR/Cas technology, which avoids many potential pitfalls associated with the Cre/LoxP system.

scholarly journals Phenotype of a transient neonatal diabetes point mutation (SUR1-R1183W) in mice

2021 ◽  
Vol 5 ◽  
pp. 15
Author(s):  
Gregor Sachse ◽  
Elizabeth Haythorne ◽  
Peter Proks ◽  
Michelle Stewart ◽  
Heather Cater ◽  
...  
Keyword(s):  
Insulin Secretion ◽  
Blood Glucose ◽  
Beta Cells ◽  
Glucose Homeostasis ◽  
Pancreatic Beta Cells ◽  
Constitutive Expression ◽  
Neonatal Diabetes ◽  
Gain Of Function ◽  
Human Phenotype ◽  
Transient Neonatal Diabetes

Background: The KATP channel plays a key role in glucose homeostasis by coupling metabolically generated changes in ATP to insulin secretion from pancreatic beta-cells.  Gain-of-function mutations in either the pore-forming (Kir6.2) or regulatory (SUR1) subunit of this channel are a common cause of transient neonatal diabetes mellitus (TNDM), in which diabetes presents shortly after birth but remits within the first few years of life, only to return in later life. The reasons behind this time dependence are unclear. Methods: In an attempt to understand the mechanism behind diabetes remission and relapse, we generated mice expressing the common TNDM mutation SUR1-R1183W. We employed Cre/LoxP technology for both inducible and constitutive expression of SUR1-R1183W specifically in mouse beta-cells, followed by investigation of their phenotype using glucose tolerance tests and insulin secretion from isolated islets.  Results: We found that the R1183W mutation impaired inhibition of KATP channels by ATP when heterologously expressed in human embryonic kidney cells. However, neither induced nor constitutive expression of SUR1-R1183W in mice resulted in changes in blood glucose homeostasis, compared to littermate controls. When challenged with a high fat diet, female mice expressing SUR1-R1183W showed increased weight gain, elevated blood glucose and impaired glycaemic control, but glucose-stimulated insulin secretion from pancreatic islets appeared unchanged. Conclusions: The mouse model of TNDM did not recapitulate the human phenotype. We discuss multiple potential reasons why this might be the case. Based on our findings, we recommend future TNDM mouse models employing a gain-of-function SUR1 mutation should be created using the minimally invasive CRISPR/Cas technology, which avoids many potential pitfalls associated with the Cre/LoxP system.

scholarly journals Clinical and Functional Characteristics of a Novel KLF11 Cys354Phe Variant Involved in Maturity-Onset Diabetes of the Young

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Yujing Sun ◽  
Jingru Qu ◽  
Jing Wang ◽  
Ruxing Zhao ◽  
Chuan Wang ◽  
...  
Keyword(s):  
Insulin Secretion ◽  
Blood Glucose ◽  
Beta Cells ◽  
Pancreatic Beta Cells ◽  
Luciferase Reporter ◽  
Maturity Onset Diabetes ◽  
Insulin Expression ◽  
Insulin Promoter ◽  
Impaired Insulin ◽  
Reporter Assays

Background. Mutations in human KLF11 may lead to the development of maturity-onset diabetes of the young 7 (MODY7). This occurs due to impaired insulin synthesis in the pancreas. To date, the clinical and functional characteristics of the novel KLF11 mutation c.1061G > T have not yet been reported. Methods. Whole-exon sequencing was used to screen the proband and family members with clinical suspicion of the KLF11 variant. Luciferase reporter assays were used to investigate whether the KLF11 variant binds to the insulin promoter. Real-time PCR, western blotting, and glucose-stimulated insulin secretion (GSIS) analysis were used to analyze the KLF11 variant that regulates insulin expression and insulin secretion activity in beta cell lines. The Freestyle Libre H (Abbott Diabetes Care Ltd) was used to dynamically monitor the proband daily blood glucose levels. Results. Mutation screening for the whole exon genes identified a heterozygous KLF11 (c.1061G > T) variant in the proband, her mother, and her maternal grandfather. Cell-based luciferase reporter assays using wild-type and mutant transgenes revealed that the KLF11 (c.1061G > T) variant had impaired insulin promoter regulation activity. Moreover, this variant was found to impair insulin expression and insulin secretion in pancreatic beta cells. The proband had better blood glucose control without staple food intake ( p < 0.05 ). Conclusions. Herein, for the first time, we report a novel KLF11 (c.1061G > T) monogenic mutation associated with MODY7. This variant has impaired insulin promoter regulation activity and impairs insulin expression and secretion in pancreatic beta cells. Therefore, administering oral antidiabetic drugs along with dietary intervention may benefit the proband.

scholarly journals Non classic presentations of a genetic mutation typically associated with transient neonatal diabetes

2020 ◽  
Vol 2020 ◽  
Author(s):  
Janani Devaraja ◽  
Charlotte Elder ◽  
Adrian Scott
Keyword(s):  
Beta Cells ◽  
Insulin Release ◽  
Pancreatic Beta Cells ◽  
Early Adulthood ◽  
Neonatal Diabetes ◽  
Later Life ◽  
Genetic Mutation ◽  
List Type ◽  
High Blood Glucose ◽  
Transient Neonatal Diabetes

Summary This case report describes a family pedigree of a mother and her children with an E227K mutation in the KCNJ11 gene. People with this particular gene mutation typically present with transient neonatal diabetes; with more than half the cohort relapsing into permanent diabetes in adolescence or early adulthood. However, the mother developed diabetes as an adolescent and thus was initially diagnosed as having Type 1 Diabetes. All her children have inherited the same genetic mutation but with differing presentations. Her second, third and fourth child presented with transient neonatal diabetes which remitted at varying times. Her first child is 16 years old but had not developed diabetes at the time of writing. The KCNJ11 gene codes for the KIR6.2 subunit of the KATP channels of the pancreatic beta cells. Mutations in this gene limit insulin release from beta cells despite high blood glucose concentrations. Most people with diabetes caused by this genetic mutation can be successfully managed with glibenclamide. Learning of the genetic mutation changed the therapeutic approach to the mother’s diabetes and enabled rapid diagnosis for her children. Through this family, we identified that an identical genetic mutation does not necessarily lead to the same diabetic phenotype. We recommend clinicians to consider screening for this gene in their patients whom MODY is suspected; especially in those presenting before the age of 25 who remain C-peptide positive. Learning points: KATP channel closure in pancreatic beta cells is a critical step in stimulating insulin release. Mutations in the KIR6.2 subunit can result in the KATP channels remaining open, limiting insulin release. People with KCNJ11 mutations may not present with neonatal diabetes as the age of presentation of diabetes can be highly variable. Most affected individuals can be treated successfully with glibenclamide, which closes the KATP channels via an independent mechanism. All first degree relatives of the index case should be offered genetic testing, including asymptomatic individuals. Offspring of affected individuals should be monitored for neonatal diabetes from birth. Affected individuals will require long-term follow-up as there is a high risk of recurrence in later life.

scholarly journals SEL BETA PANKREAS SINTESIS DAN SEKRESI INSULIN

2013 ◽  
Vol 4 (3) ◽  
Author(s):  
Eka Banjarnahor ◽  
Sunny Wangko
Keyword(s):  
Insulin Secretion ◽  
Blood Glucose ◽  
Beta Cells ◽  
Pancreatic Beta Cells ◽  
Plasma Membranes ◽  
Secretory Granules ◽  
Chromosome 11 ◽  
Insulin Synthesis ◽  
Glucose Levels ◽  
Blood Glucose Levels

Abstract: Insulin synthesis and secretion are done by pancreatic beta cells. Preceding the insulin synthesis, there is a gen translation in chromosome 11 that produces insulin, packed in secretory granules. Insulin secretion is induced by the alteration of blood glucose levels, resulting in the occurence of intracellular reactions preceded by changes of ATP/ADP ratios that trigger the depolarisation of plasma membranes. Furthermore, extracellular Ca2+ ions move inward to beta cells to activate exocytosis. There are still many unknown problems so far in either the synthesis or secretion of insulin that cause unfulfilled insulin needs in the body.Keywords: beta cells, insulin, synthesis, secretionAbstrak: Sintesis dan sekresi insulin dilakukan oleh sel beta pankreas. Sintesis insulin diawali oleh salinan gen pada kromosom 11, yang akan menghasilkan insulin, di kemas di dalam granul-granul sekretorik. Sekresi insulin diinduksi oleh perubahan kadar glukosa, yang berakibat terjadinya reaksi intrasel yang diikuti adanya perbedaan rasio ATP/ADP yang memicu reaksi depolarisasi membran plasma. Sebagai akibat lanjut Ca2+ ekstrasel akan masuk ke dalam sel beta yang berfungsi mengaktifkan eksositosis. Sampai saat ini masih banyak ditemui masalah baik dalam hal sintesis maupun sekresi insulin yang mengakibatkan kebutuhan insulin tubuh tidak terpenuhi.Kata kunci: sel beta, insulin, sintesis, sekresi

scholarly journals Pancreatic beta-cells expressing the Arg64 variant of the beta(3)-adrenergic receptor exhibit abnormal insulin secretory activity

2001 ◽  
Vol 27 (2) ◽  
pp. 133-144 ◽  
Author(s):  
R Perfetti ◽  
H Hui ◽  
K Chamie ◽  
S Binder ◽  
M Seibert ◽  
...  
Keyword(s):  
Insulin Secretion ◽  
Beta Cells ◽  
Western Blotting ◽  
Adrenergic Receptor ◽  
Pancreatic Beta Cells ◽  
Secretory Activity ◽  
Host Cells ◽  
Human Pancreas ◽  
Dependent Manner ◽  
Wild Type

The Arg64 beta(3)-adrenergic receptor (beta(3)AR) variant is associated with an earlier age of onset of diabetes and lower levels of insulin secretion in humans. The aims of this study were to investigate whether beta(3)AR is expressed by islet cells, if receptor binding affects insulin secretion and, finally, if the beta(3)AR Arg64 variant induces abnormal insulin secretory activity. Human pancreas extracts were subjected to RT-PCR, Western blotting and immunostaining analyses. DNA sequencing and Western blotting demonstrated that the beta(3)AR gene is transcribed and translated in the human pancreas; immunostaining showed that it is expressed by the islets of Langerhans. Cultured rat beta-cells responded to human beta(3)AR agonists in a dose- and time-dependent manner. Transfection of cultured rat beta-cells with the wild-type human beta(3)AR produced an increased baseline and ligand-dependent insulin secretion compared with parental cells. On the other hand, cells transfected with the Arg64 variant of the beta(3)AR secreted less insulin, both spontaneously and after exposure to human beta(3)AR agonists. Furthermore, while transfection with the wild-type beta(3)AR preserved the glucose-dependent secretion of insulin, expression of the variant receptor rendered the host cells significantly less responsive to glucose. In summary, cells express the beta(3)AR, and its activation contributes to the regulation of insulin secretion. These findings may help explain the low levels of insulin secretion in response to an i.v. glucose tolerance test observed in humans carrying the Arg64 polymorphism.

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