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Park J, Shin YK, Kim U, Seol GH. Ginsenoside Rb 1 Reduces Hyper-Vasoconstriction Induced by High Glucose and Endothelial Dysfunction in Rat Aorta. Pharmaceuticals (Basel) 2023; 16:1238. [PMID: 37765046 PMCID: PMC10536350 DOI: 10.3390/ph16091238] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2023] [Revised: 08/31/2023] [Accepted: 08/31/2023] [Indexed: 09/29/2023] Open
Abstract
Acute hyperglycemia induces oxidative damage and inflammation, leading to vascular dysfunction. Ginsenoside Rb1 (Rb1) is a major component of red ginseng with anti-diabetic, anti-oxidant and anti-inflammatory properties. Here, we investigated the beneficial effects and the underlying mechanisms of Rb1 on hypercontraction induced by high glucose (HG) and endothelial dysfunction (ED). The isometric tension of aortic rings was measured by myography. The rings were treated with NG-nitro-L-arginine methyl ester (L-NAME) to induce chemical destruction of the endothelium, and Rb1 was added after HG induction. The agonist-induced vasoconstriction was significantly higher in the aortic rings treated with L-NAME + HG50 than in those treated with HG50 or L-NAME (p = 0.011) alone. Rb1 significantly reduced the hypercontraction in the aortic rings treated with L-NAME + HG50 (p = 0.004). The ATP-sensitive K+ channel (KATP) blocker glibenclamide tended to increase the Rb1-associated reduction in the agonist-induced vasoconstriction in the rings treated with L-NAME + HG50. The effect of Rb1 in the aortic rings treated with L-NAME + HG50 resulted from a decrease in extracellular Ca2+ influx through the receptor-operated Ca2+ channel (ROCC, 10-6-10-4 M CaCl2, p < 0.001; 10-3-2.5 × 10-3 M CaCl2, p = 0.001) and the voltage-gated Ca2+ channel (VGCC, 10-6 M CaCl2, p = 0.003; 10-5-10-2 M CaCl2, p < 0.001), whereas Rb1 did not interfere with Ca2+ release from the sarcoplasmic reticulum. In conclusion, we found that Rb1 reduced hyper-vasoconstriction induced by HG and ED by inhibiting the ROCC and the VGCC, and possibly by activating the KATP in rat aorta. This study provides further evidence that Rb1 could be developed as a therapeutic target for ED in diabetes.
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Affiliation(s)
- Jubin Park
- Department of Basic Nursing Science, College of Nursing, Korea University, Seoul 02841, Republic of Korea (U.K.)
- BK21 FOUR Program of Transdisciplinary Major in Learning Health Systems, Graduate School, Korea University, Seoul 02841, Republic of Korea
| | - You Kyoung Shin
- Department of Basic Nursing Science, College of Nursing, Korea University, Seoul 02841, Republic of Korea (U.K.)
| | - Uihwan Kim
- Department of Basic Nursing Science, College of Nursing, Korea University, Seoul 02841, Republic of Korea (U.K.)
- BK21 FOUR Program of Transdisciplinary Major in Learning Health Systems, Graduate School, Korea University, Seoul 02841, Republic of Korea
| | - Geun Hee Seol
- Department of Basic Nursing Science, College of Nursing, Korea University, Seoul 02841, Republic of Korea (U.K.)
- BK21 FOUR Program of Transdisciplinary Major in Learning Health Systems, Graduate School, Korea University, Seoul 02841, Republic of Korea
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Dual-hairpin ligation amplification enabled ultra-sensitive and selective ATP detection for cancer monitor. Biosens Bioelectron 2022; 212:114402. [PMID: 35653851 DOI: 10.1016/j.bios.2022.114402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Accepted: 05/16/2022] [Indexed: 11/20/2022]
Abstract
Abnormal concentration of ATP is related to many diseases such as Parkinson's disease, hypoglycaemia, inflammation and cancer. However, most of the reported strategies exhibit moderate sensitivity with ∼nM level detection limit and few of them can distinguish ATP from its analogues, such as GTP, CTP, UTP and adenosine. Herein, we report an ultra-sensitive and selective ATP detection strategy that combines dual hairpin ligation-induced isothermal amplification (DHLA) with ATP-dependent enzymatic reaction. A good linear relationship between Cq value and ATP concentration in the range from 16 fM to 160 nM is acquired. Meanwhile, the strategy can distinguish ATP from its analogues with high selectivity. Furthermore, our proposed strategy has been successfully utilized to detect ATP from colon cell line and cell culture media with great potential applications in cell metabolism and cancer diagnosis.
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Iafusco D, Zanfardino A, Bonfanti R, Rabbone I, Tinto N, Iafusco F, Meola S, Gicchino MF, Ozen G, Casaburo F, Piscopo A, Miraglia Del Giudice E, Barbetti F. Congenital diabetes mellitus. Minerva Pediatr 2020; 72:240-249. [PMID: 32274916 DOI: 10.23736/s0026-4946.20.05838-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Congenital diabetes mellitus is a rare disorder characterized by hyperglycemia that occurs shortly after birth. We define "Diabetes of Infancy" if hyperglycemia onset before 6 months of life. From the clinical point of view, we distinguish two main types of diabetes of infancy: transient (TNDM), which remits spontaneously, and permanent (PNDM), which requires lifelong treatment. TNDM may relapse later in life. About 50% of cases are transient (TNDM) and 50% permanent. Clinical manifestations include severe intrauterine growth retardation, hyperglycemia and dehydration. A wide range of different associated clinical signs including facial dysmorphism, deafness and neurological, cardiac, kidney or urinary tract anomalies are reported. Developmental delay and learning difficulties may also be observed. In this paper we review all the causes of congenital diabetes and all genes and syndromes involved in this pathology. The discovery of the pathogenesis of most forms of congenital diabetes has made it possible to adapt the therapy to the diagnosis and in the forms of alteration of the potassium channels of the pancreatic Beta cells the switch from insulin to glibenclamide per os has greatly improved the quality of life. Congenital diabetes, although it is a very rare form, has been at the must of research in recent years especially for pathogenesis and pharmacogenetics. The most striking difference compared to the more frequent autoimmune diabetes in children (type 1 diabetes) is the possibility of treatment with hypoglycemic agents and the apparent lower frequency of chronic complications.
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Affiliation(s)
- Dario Iafusco
- Department of Pediatrics, University of Campania "Luigi Vanvitelli", Naples, Italy -
| | - Angela Zanfardino
- Department of Pediatrics, University of Campania "Luigi Vanvitelli", Naples, Italy
| | - Riccardo Bonfanti
- Unit of Pediatric Diabetology, Department of Pediatrics, Diabetes Research Institute, San Raffaele Scientific Institute, Milan, Italy
| | - Ivana Rabbone
- Hub Regional Center of Pediatric Diabetology, Department of Science of Health, Maggiore della Carità University Hospital, University of Eastern Piedmont, Novara, Italy
| | - Nadia Tinto
- CEINGE Advanced Biotechnologies, Department of Molecular Medicine and Medical Biotechnology, Federico II University of Naples, Naples, Italy
| | - Fernanda Iafusco
- CEINGE Advanced Biotechnologies, Department of Molecular Medicine and Medical Biotechnology, Federico II University of Naples, Naples, Italy
| | - Serena Meola
- CEINGE Advanced Biotechnologies, Department of Molecular Medicine and Medical Biotechnology, Federico II University of Naples, Naples, Italy
| | - Maria F Gicchino
- Department of Pediatrics, University of Campania "Luigi Vanvitelli", Naples, Italy
| | - Gulsum Ozen
- Department of Pediatrics, University of Health Science, Ankara Training and Research Hospital, Ankara, Turkey
| | - Francesca Casaburo
- Department of Pediatrics, University of Campania "Luigi Vanvitelli", Naples, Italy
| | - Alessia Piscopo
- Department of Pediatrics, University of Campania "Luigi Vanvitelli", Naples, Italy
| | | | - Fabrizio Barbetti
- Department of Experimental Medicine, Tor Vergata University, Rome, Italy
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Mele A, Calzolaro S, Cannone G, Cetrone M, Conte D, Tricarico D. Database search of spontaneous reports and pharmacological investigations on the sulfonylureas and glinides-induced atrophy in skeletal muscle. Pharmacol Res Perspect 2014; 2:e00028. [PMID: 25505577 PMCID: PMC4186404 DOI: 10.1002/prp2.28] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2013] [Revised: 01/09/2014] [Accepted: 01/11/2014] [Indexed: 12/14/2022] Open
Abstract
The ATP-sensitive K(+) (KATP) channel is an emerging pathway in the skeletal muscle atrophy which is a comorbidity condition in diabetes. The "in vitro" effects of the sulfonylureas and glinides were evaluated on the protein content/muscle weight, fibers viability, mitochondrial succinic dehydrogenases (SDH) activity, and channel currents in oxidative soleus (SOL), glycolitic/oxidative flexor digitorum brevis (FDB), and glycolitic extensor digitorum longus (EDL) muscle fibers of mice using biochemical and cell-counting Kit-8 assay, image analysis, and patch-clamp techniques. The sulfonylureas were: tolbutamide, glibenclamide, and glimepiride; the glinides were: repaglinide and nateglinide. Food and Drug Administration-Adverse Effects Reporting System (FDA-AERS) database searching of atrophy-related signals associated with the use of these drugs in humans has been performed. The drugs after 24 h of incubation time reduced the protein content/muscle weight and fibers viability more effectively in FDB and SOL than in the EDL. The order of efficacy of the drugs in reducing the protein content in FDB was: repaglinide (EC50 = 5.21 × 10(-6)) ≥ glibenclamide(EC50 = 8.84 × 10(-6)) > glimepiride(EC50 = 2.93 × 10(-5)) > tolbutamide(EC50 = 1.07 × 10(-4)) > nateglinide(EC50 = 1.61 × 10(-4)) and it was: repaglinide(7.15 × 10(-5)) ≥ glibenclamide(EC50 = 9.10 × 10(-5)) > nateglinide(EC50 = 1.80 × 10(-4)) ≥ tolbutamide(EC50 = 2.19 × 10(-4)) > glimepiride(EC50=-) in SOL. The drug-induced atrophy can be explained by the KATP channel block and by the enhancement of the mitochondrial SDH activity. In an 8-month period, muscle atrophy was found in 0.27% of the glibenclamide reports in humans and in 0.022% of the other not sulfonylureas and glinides drugs. No reports of atrophy were found for the other sulfonylureas and glinides in the FDA-AERS. Glibenclamide induces atrophy in animal experiments and in human patients. Glimepiride shows less potential for inducing atrophy.
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Affiliation(s)
- Antonietta Mele
- Departments of Pharmacy-Drug Science, University of Bari Bari, Italy
| | - Sara Calzolaro
- Departments of Pharmacy-Drug Science, University of Bari Bari, Italy
| | - Gianluigi Cannone
- Departments of Pharmacy-Drug Science, University of Bari Bari, Italy
| | - Michela Cetrone
- Departments of Pharmacovigilance, University-Hospital Policlinico, Ministry of Health Bari, Italy
| | - Diana Conte
- Departments of Pharmacy-Drug Science, University of Bari Bari, Italy
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Hicks KA, Kushner JA, Heptulla R, Ham JN. Permanent neonatal diabetes mellitus in monozygotic twins achieving low-dose sulfonylurea therapy. J Pediatr Endocrinol Metab 2014; 27:135-8. [PMID: 23959658 DOI: 10.1515/jpem-2013-0171] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/04/2013] [Accepted: 07/22/2013] [Indexed: 11/15/2022]
Abstract
Although KCNJ11 mutations of the KATP channel within the β cell are known to prevent insulin secretion and cause permanent neonatal diabetes mellitus, the genotype-phenotype correlation continues to be of clinical interest. We report the clinical outcomes in monozygotic twins with neonatal diabetes due to heterozygous mutations in KCNJ11 at R201H. The twins demonstrated concordant clinical outcomes after transitioning from insulin to oral sulfonylurea therapy at 4 months of age. Both twins remained on sulfonylurea therapy while achieving similar growth, development, and metabolic goals. They exhibit marked sensitivity to sulfonylurea therapy with current dosing at 0.05 and 0.06 mg/kg per day at age 5 years which deviates from the approximate maintenance dose of 0.4 mg/kg per day at the time of transition and subsequent follow-up. Metabolic control provided by low-dose sulfonylurea therapy is likely due to early age at transition from insulin to sulfonylurea therapy and possible preservation of endogenous insulin secretion.
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Personalized medicine switching from insulin to sulfonylurea in permanent neonatal diabetes mellitus dictated by a novel activating ABCC8 mutation. ACTA ACUST UNITED AC 2012; 21:56-9. [PMID: 22306677 DOI: 10.1097/pdm.0b013e318220bb0e] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND Neonatal diabetes mellitus (NDM) is a rare but important condition affecting approximately 1 in 100,000 newborns. Permanent form requires life-long treatment with difficulties in long-term compliance and metabolic complications. Exact genetic diagnosis can enable improved outcome and patient satisfaction by switching insulin injection to oral sulfonylureas. Successful cases have been reported with most experience on the KCNJ11-mutated permanent form. Here we report a successful experience in an ABCC8-mutated infant with permanent NDM. PATIENT AND METHODS A 4-month-old Chinese girl was incidentally found to have hyperglycemia with baseline C-peptide of 0.05 nmol/L requiring insulin injection of 0.2 IU/kg/d. Genetic analysis of KCNJ11 and ABCC8 was performed by polymerase chain reaction and direct DNA sequencing at the age of 3 years. Sulfonylurea transition was conducted after the ABCC8 mutation detection. RESULTS A novel homozygous ABCC8 NM_000352.3: c.3068 A>G; NP_000343.2: p.H1023R mutation was detected. C-peptide level increased to 0.14 nmol/L and HbA1c was normalized to 5.8% from 8.0% after 8 months of oral glibenclamide treatment with a maintenance dosage of 0.65 mg/kg/d. CONCLUSIONS In this patient with ABCC8-mutated permanent NDM, oral sulfonylurea is also effective in achieving satisfactory diabetic control. Our study adds information to the personalized medicine practice of ABCC8-mutated permanent NDM.
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Abstract
PURPOSE OF REVIEW Disease states characterized by abnormal cellular function or proliferation frequently reflect aberrant genetic information. By revealing disease-specific DNA mutations, we gain insight into normal physiology, pathophysiology, potential therapeutic targets and are better equipped to evaluate an individual's disease risks. This review examines recent advances in our understanding of the genetic basis of adrenal cortical disease. RECENT FINDINGS Important advances made in the past year have included identification of KCNJ5 potassium channel mutations in the pathogenesis of both aldosterone-producing adenomas and familial hyperaldosteronism type III; characterization of phosphodiesterase 11A as a modifier of phenotype in Carney complex caused by protein kinase, cAMP-dependent, regulatory subunit, type-I mutations; the finding of 11β-hydroxysteroid dehydrogenase type I mutations as a novel mechanism for cortisone reductase deficiency; and demonstration of potential mortality benefit in pursuing comprehensive presymptomatic screening for patients with Li-Fraumeni syndrome, including possible reduction in risks associated with adrenocortical carcinoma. SUMMARY This research review provides a framework for the endocrinologist to maintain an up-to-date understanding of adrenal cortical disease genetics.
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Affiliation(s)
- Adi Bar-Lev
- Division of Endocrinology, Diabetes and Hypertension, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA
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Tricarico D, Rolland JF, Cannone G, Mele A, Cippone V, Laghezza A, Carbonara G, Fracchiolla G, Tortorella P, Loiodice F, Conte Camerino D. Structural nucleotide analogs are potent activators/inhibitors of pancreatic β cell KATP channels: an emerging mechanism supporting their use as antidiabetic drugs. J Pharmacol Exp Ther 2011; 340:266-76. [PMID: 22028392 DOI: 10.1124/jpet.111.185835] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
The 2H-1,4-benzoxazine derivatives are novel drugs structurally similar to nucleotides; however, their actions on the pancreatic β cell ATP-sensitive K+ (KATP) channel and on glucose disposal are unknown. Therefore, the effects of the linear/branched alkyl substituents and the aliphatic/aromatic rings at position 2 of the 2H-1,4-benzoxazine nucleus on the activity of these molecules against the pancreatic β cell KATP channel and the Kir6.2ΔC36 subunit were investigated using a patch-clamp technique. The effects of these compounds on glucose disposal that followed glucose loading by intraperitoneal glucose tolerance test and on fasting glycemia were investigated in normal mice. The 2-n-hexyl analog blocked the KATP (IC₅₀ = 10.1 × 10⁻⁹ M) and Kir6.2ΔC36 (IC₅₀ = 9.6 × 10⁻⁹ M) channels, which induced depolarization. In contrast, the 2-phenyl analog was a potent opener (drug concentration needed to enhance the current by 50% = 0.04 × 10⁻⁹ M), which induced hyperpolarization. The ranked order of the potency/efficacy of the analog openers was 2-phenyl > 2-benzyl > 2-cyclohexylmethyl. The 2-phenylethyl and 2-isopropyl analogs were not effective as blockers/openers. The 2-n-hexyl (2-10 mg/kg) and 2-phenyl analogs (2-30 mg/kg) reduced and enhanced the glucose areas under the curves, respectively, after glucose loading in mice. These compounds did not affect the fasting glycemia as is observed with glibenclamide. The linear alkyl chain and the aromatic ring at position 2 of the 1,4-benzoxazine nucleus are the determinants, which confer the KATP channel blocking action with glucose-lowering effects and the opening action with increased glucose levels, respectively. The opening/blocking actions of these compounds mimic those that were observed with ATP and ADP. The results support the use of these compounds as novel antidiabetic drugs.
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Affiliation(s)
- Domenico Tricarico
- Department of Pharmacobiology, Faculty of Pharmacy, University of Bari, Via Orabona No. 4, I-70126 Bari, Italy.
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9
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Abstract
The study of genetic variation has the potential to aid understanding of the mechanisms underlying the observed inter-individual variation in drug response and by which idiosyncratic adverse effects occur. In this review, we outline current progress in pharmacogenetics using examples to highlight both mechanisms of influence of polymorphisms and research strategies for their detection. In the final sections we discuss contemporary challenges for both researchers and clinicians.
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Affiliation(s)
- John D Blakey
- Respiratory Biomedical Research Unit, City Hospital Campus, Nottingham, UK.
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Drews G, Krippeit-Drews P, Düfer M. Electrophysiology of islet cells. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2010; 654:115-63. [PMID: 20217497 DOI: 10.1007/978-90-481-3271-3_7] [Citation(s) in RCA: 100] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Stimulus-Secretion Coupling (SSC) of pancreatic islet cells comprises electrical activity. Changes of the membrane potential (V(m)) are regulated by metabolism-dependent alterations in ion channel activity. This coupling is best explored in beta-cells. The effect of glucose is directly linked to mitochondrial metabolism as the ATP/ADP ratio determines the open probability of ATP-sensitive K(+) channels (K(ATP) channels). Nucleotide sensitivity and concentration in the direct vicinity of the channels are controlled by several factors including phospholipids, fatty acids, and kinases, e.g., creatine and adenylate kinase. Closure of K(ATP) channels leads to depolarization of beta-cells via a yet unknown depolarizing current. Ca(2+) influx during action potentials (APs) results in an increase of the cytosolic Ca(2+) concentration ([Ca(2+)](c)) that triggers exocytosis. APs are elicited by the opening of voltage-dependent Na(+) and/or Ca(2+) channels and repolarized by voltage- and/or Ca(2+)-dependent K(+) channels. At a constant stimulatory glucose concentration APs are clustered in bursts that are interrupted by hyperpolarized interburst phases. Bursting electrical activity induces parallel fluctuations in [Ca(2+)](c) and insulin secretion. Bursts are terminated by I(Kslow) consisting of currents through Ca(2+)-dependent K(+) channels and K(ATP) channels. This review focuses on structure, characteristics, physiological function, and regulation of ion channels in beta-cells. Information about pharmacological drugs acting on K(ATP) channels, K(ATP) channelopathies, and influence of oxidative stress on K(ATP) channel function is provided. One focus is the outstanding significance of L-type Ca(2+) channels for insulin secretion. The role of less well characterized beta-cell channels including voltage-dependent Na(+) channels, volume sensitive anion channels (VSACs), transient receptor potential (TRP)-related channels, and hyperpolarization-activated cyclic nucleotide-gated (HCN) channels is discussed. A model of beta-cell oscillations provides insight in the interplay of the different channels to induce and maintain electrical activity. Regulation of beta-cell electrical activity by hormones and the autonomous nervous system is discussed. alpha- and delta-cells are also equipped with K(ATP) channels, voltage-dependent Na(+), K(+), and Ca(2+) channels. Yet the SSC of these cells is less clear and is not necessarily dependent on K(ATP) channel closure. Different ion channels of alpha- and delta-cells are introduced and SSC in alpha-cells is described in special respect of paracrine effects of insulin and GABA secreted from beta-cells.
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Affiliation(s)
- Gisela Drews
- Institute of Pharmacy, Department of Pharmacology and Clinical Pharmacy, University of Tübingen, 72076 Tübingen, Germany.
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Liu Z, Habener JF. Wnt signaling in pancreatic islets. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2010; 654:391-419. [PMID: 20217507 DOI: 10.1007/978-90-481-3271-3_17] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The Wnt signaling pathway is critically important not only for stem cell amplification, differentiation, and migration, but also is important for organogenesis and the development of the body plan. Beta-catenin/TCF7L2-dependent Wnt signaling (the canonical pathway) is involved in pancreas development, islet function, and insulin production and secretion. The glucoincretin hormone glucagon-like peptide-1 and the chemokine stromal cell-derived factor-1 modulate canonical Wnt signaling in beta-cells which is obligatory for their mitogenic and cytoprotective actions. Genome-wide association studies have uncovered 19 gene loci that confer susceptibility for the development of type 2 diabetes. At least 14 of these diabetes risk alleles encode proteins that are implicated in islet growth and functioning. Seven of them are either components of, or known target genes for, Wnt signaling. The transcription factor TCF7L2 is particularly strongly associated with risk for diabetes and appears to be fundamentally important in both canonical Wnt signaling and beta-cell functioning. Experimental loss of TCF7L2 function in islets and polymorphisms in TCF7L2 alleles in humans impair glucose-stimulated insulin secretion, suggesting that perturbations in the Wnt signaling pathway may contribute substantially to the susceptibility for, and pathogenesis of, type 2 diabetes. This review focuses on considerations of the hormonal regulation of Wnt signaling in islets and implications for mutations in components of the Wnt signaling pathway as a source for risk-associated alleles for type 2 diabetes.
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Affiliation(s)
- Zhengyu Liu
- Laboratory of Molecular Endocrinology, Massachusetts General Hospital, Boston, MA 02114, USA.
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12
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Medeiros-Domingo A, Tan BH, Crotti L, Tester DJ, Eckhardt L, Cuoretti A, Kroboth SL, Song C, Zhou Q, Kopp D, Schwartz PJ, Makielski JC, Ackerman MJ. Gain-of-function mutation S422L in the KCNJ8-encoded cardiac K(ATP) channel Kir6.1 as a pathogenic substrate for J-wave syndromes. Heart Rhythm 2010; 7:1466-71. [PMID: 20558321 DOI: 10.1016/j.hrthm.2010.06.016] [Citation(s) in RCA: 190] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/07/2010] [Accepted: 06/09/2010] [Indexed: 02/07/2023]
Abstract
BACKGROUND J-wave syndromes have emerged conceptually to encompass the pleiotropic expression of J-point abnormalities including Brugada syndrome (BrS) and early repolarization syndrome (ERS). KCNJ8, which encodes the cardiac K(ATP) Kir6.1 channel, recently has been implicated in ERS following identification of the functionally uncharacterized missense mutation S422L. OBJECTIVE The purpose of this study was to further explore KCNJ8 as a novel susceptibility gene for J-wave syndromes. METHODS Using polymerase chain reaction, denaturing high-performance liquid chromatography, and direct DNA sequencing, comprehensive open reading frame/splice site mutational analysis of KCNJ8 was performed in 101 unrelated patients with J-wave syndromes, including 87 with BrS and 14 with ERS. Six hundred healthy individuals were examined to assess the allelic frequency for all variants detected. KCNJ8 mutation(s) was engineered by site-directed mutagenesis and coexpressed heterologously with SUR2A in COS-1 cells. Ion currents were recorded using whole-cell configuration of the patch-clamp technique. RESULTS One BrS case and one ERS case hosted the identical missense mutation S422L, which was reported previously. KCNJ8-S422L involves a highly conserved residue and was absent in 1,200 reference alleles. Both cases were negative for mutations in all known BrS and ERS susceptibility genes. K(ATP) current of the Kir6.1-S422L mutation was increased significantly over the voltage range from 0 to 40 mV compared to Kir6.1-WT channels (n = 16-21; P <.05). CONCLUSION These findings further implicate KCNJ8 as a novel J-wave syndrome susceptibility gene and a marked gain of function in the cardiac K(ATP) Kir6.1 channel secondary to KCNJ8-S422L as a novel pathogenic mechanism for the phenotypic expression of both BrS and ERS.
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Affiliation(s)
- Argelia Medeiros-Domingo
- Department of Medicine (Division of Cardiovascular Diseases), Windland Smith Rice Sudden Death Genomics Laboratory, Mayo Clinic, Rochester, Minnesota 55905, USA
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Abstract
To date, most of the major types of Kir channels, Kir2s, Kir3s, Kir4s, and Kir6s, have been found to partition into cholesterol-rich membrane domains and/or to be regulated by changes in the level of membrane cholesterol. Surprisingly, however, in spite of the structural similarities between different Kirs, effects of cholesterol on different types of Kir channels vary from cholesterol-induced decrease in the current density (Kir2 channels) to the loss of channel activity by cholesterol depletion (Kir4 channels) and loss of channel coupling by different mediators (Kir3 and Kir6 channels). Recently, we have gained initial insights into the mechanisms responsible for cholesterol-induced suppression Kir2 channels, but mechanisms underlying cholesterol sensitivity of other Kir channels are mostly unknown. The goal of this review is to present a summary of the current knowledge of the distinct effects of cholesterol on different types of Kir channels in vitro and in vivo.
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Affiliation(s)
- Irena Levitan
- Department of Medicine, Pulmonary Section, University of Illinois at Chicago, Chicago, IL 60612, USA.
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14
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Campos MG, Oropeza M, Torres-Sosa C, Jiménez-Estrada M, Reyes-Chilpa R. Sesquiterpenoids from antidiabetic Psacalium decompositum block ATP sensitive potassium channels. JOURNAL OF ETHNOPHARMACOLOGY 2009; 123:489-493. [PMID: 19501281 DOI: 10.1016/j.jep.2009.03.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2008] [Revised: 02/13/2009] [Accepted: 03/04/2009] [Indexed: 05/27/2023]
Abstract
ETHNOPHARMACOLOGICAL RELEVANCE The hypoglycemic effect of root and rhizome aqueous decoction of Psacalium decompositum (Asteraceae), a medicinal herb from Mexico, has been experimentally demonstrated, leading to the identification of several hypoglycemic sesquiterpenoids, such as cacalol, and the mixture of 3-hydroxycacalolide, and epi-3-hydroxycacalolide; however, the mechanism of action of these compounds is unknown. AIM OF THE STUDY To establish whether cacalol, cacalone epimer mixture and cacalol acetate may block adenosine triphosphate-sensitive potassium channels (K(ATP) channels) in a similar way to the antidiabetic drug glibenclamide. MATERIALS AND METHODS Cacalol, cacalone epimer mixture, and cacalol acetate were tested on the diazoxide-induced relaxation of male rat aortic rings precontracted with phenylephrine (3.2x10(-6)M). RESULTS Cacalol (10(-5)M), cacalol acetate and the cacalone epimer mixture (10(-4)M) inhibited the diazoxide effect, in a similar manner and concentration as glibenclamide (10(-5)M). Cacalone epimer mixture exerted this effect in a concentration-dependent manner (P<0.01). Cacalol (10(-4)M), irreversibly inhibited the diazoxide-induced relaxation, and displayed activity at a lower concentration (10(-5)M) than cacalone epimer mixture and cacalol acetate. CONCLUSIONS These results suggest that the studied compounds block K(ATP) channels in a similar way to glibenclamide in rat aorta. However, controversial data indicate that Psacalium decompositum sesquiterpenoids are less effective than glibenclamide in lowering plasma glucose levels, suggesting that cacalol and cacalone epimer mixture, as well as cacalol acetate, may display a higher affinity to SUR2 subunit of K(ATP) channels in aortic smooth muscle than to SUR1 subunit in pancreatic beta-cells.
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Affiliation(s)
- Maria G Campos
- Unit of Medical Research in Pharmacology, National Medical Center SXXI, IMSS, México, Mexico
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Tricarico D, Mele A, Camerino GM, Laghezza A, Carbonara G, Fracchiolla G, Tortorella P, Loiodice F, Camerino DC. Molecular determinants for the activating/blocking actions of the 2H-1,4-benzoxazine derivatives, a class of potassium channel modulators targeting the skeletal muscle KATP channels. Mol Pharmacol 2008; 74:50-8. [PMID: 18403717 DOI: 10.1124/mol.108.046615] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The 2H-1,4-benzoxazine derivatives are modulators of the skeletal muscle ATP-sensitive-K(+) channels (K(ATP)), activating it in the presence of ATP but inhibiting it in the absence of nucleotide. To investigate the molecular determinants for the activating/blocking actions of these compounds, novel molecules with different alkyl or aryl-alkyl substitutes at position 2 of the 1,4-benzoxazine ring were prepared. The effects of the lengthening of the alkyl chain and of branched substitutes, as well as of the introduction of aliphatic/aromatic rings on the activity of the molecules, were investigated on the skeletal muscle K(ATP) channels of the rat, in excised-patch experiments, in the presence or absence of internal ATP (10(-4) M). In the presence of ATP, the 2-n-hexyl analog was the most potent activator (DE(50) = 1.08 x 10(-10) M), whereas the 2-phenylethyl was not effective. The rank order of efficacy of the openers was 2-n-hexyl > or =2-cyclohexylmethyl >2-isopropyl = 2-n-butyl > or = 2-phenyl > or = 2-benzyl = 2-isobutyl analogs. In the absence of ATP, the 2-phenyl analog was the most potent inhibitor (IC(50) = 2.5 x 10(-11) M); the rank order of efficacy of the blockers was 2-phenyl > or = 2-n-hexyl > 2-n-butyl > 2-cyclohexylmethyl, whereas the 2-phenylethyl, 2-benzyl, and 2-isobutyl 1,4-benzoxazine analogs were not effective; the 2-isopropyl analog activated the K(ATP) channel even in the absence of nucleotide. Therefore, distinct molecular determinants for the activating or blocking actions for these compounds can be found. For example, the replacement of the linear with the branched alkyl substitutes at the position 2 of the 1,4-benzoxazine nucleus determines the molecular switch from blockers to openers. These compounds were 100-fold more potent and effective as openers than other KCO against the muscle K(ATP) channels.
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Affiliation(s)
- Domenico Tricarico
- Department of Pharmacobiology, Faculty of Pharmacy, via Orabona no. 4, Bari, Italy
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Slingerland AS, Hurkx W, Noordam K, Flanagan SE, Jukema JW, Meiners LC, Bruining GJ, Hattersley AT, Hadders-Algra M. Sulphonylurea therapy improves cognition in a patient with the V59M KCNJ11 mutation. Diabet Med 2008; 25:277-81. [PMID: 18307455 DOI: 10.1111/j.1464-5491.2007.02373.x] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
BACKGROUND KCNJ11 mutations are a common cause of diabetes diagnosed in the first 6 months of life, and approximately 25% of patients have neurological features. Sulphonylureas have been shown to improve glycaemic control and also motor function, but the impact on cognitive function has not been extensively addressed previously. METHODS The patient had a low birth weight and was found to have diabetes at the age of 2 days. The patient was treated with insulin from diagnosis. The child also had marked developmental delay so that his average functional age was 2.5 years when he was 12 years old. A V59M mutation in KCNJ11 was found on sequencing, resulting in a diagnosis of intermediate developmental delay, epilepsy, neonatal diabetes (DEND) syndrome. Identification of a Kir6.2 mutation allowed insulin injections to be replaced by glibenclamide tablets. RESULTS This resulted not only in improved glycaemic control (HbA(1c) fell from 8.1 to 6.5%), but also an impressive improvement in many aspects of cognitive function, with the functional age increasing to 4 years within 6 months of treatment change. CONCLUSIONS This is the first clear report of cognitive function improving in a patient with the neurological features associated with a K(ATP) channel mutation following transfer to sulphonylureas. The finding of cognitive improvement suggests that glibenclamide is likely to be acting directly on the brain and not just on nerve and muscle, improving muscle strength.
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Affiliation(s)
- A S Slingerland
- Institute of Biomedical and Clinical Sciences, Peninsula Medical School, Exeter, UK.
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