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Barbara Piccini, Caterina Coviello, Livia Drovandi, Artuso Rosangela, Francesca Monzali, Emilio Casalini, Sabrina Giglio, Sonia Toni, Carlo Dani
Neonatal diabetes mellitus (NDM) is a monogenic form of diabetes occurring within 6 months from birth. NDM can be permanent or transient (TNDM). We report the case of a preterm infant with TNDM due to an ABCC8 mutation identified by next-generation sequencing. The pancreatic adenosine triphosphate (ATP)-sensitive K+ (K-ATP) channel is a key regulator of insulin secretion. Gain-of-function mutations in the genes encoding the Kir6.2 (KCNJ11) and SUR1 (ABCC8) subunits of the channel cause neonatal diabetes. The patient was successfully managed with insulin lispro at a 1:100 dilution, drawn up in an insulin pen injector with a 4-mm needle...
January 2018: American Journal of Perinatology Reports
Carolina I Ghanem, Jose E Manautou
Liver transporters play an important role in the pharmacokinetics and disposition of pharmaceuticals, environmental contaminants, and endogenous compounds. Among them, the family of ATP-Binding Cassette (ABC) transporters is the most important due to its role in the transport of endo- and xenobiotics. The ABCC sub-family is the largest one, consisting of 13 members that include the cystic fibrosis conductance regulator (CFTR/ABCC7); the sulfonylurea receptors (SUR1/ABCC8 and SUR2/ABCC9) and the multidrug resistance-associated proteins (MRPs)...
February 21, 2018: Current Medicinal Chemistry
Atsumi Saito, Kazuya Miyagawa, Hiroko Miyagishi, Kazuhiro Kurokawa, Akira Umeda, Yasumasa Okada, Minoru Tsuji, Hiroshi Takeda
ATP-sensitive potassium (KATP ) channels consist of two structurally different subunits: a pore-forming subunit of the Kir6.0-family (Kir6.1 or Kir6.2) and a regulatory sulfonylurea receptor subunit (SUR1, SUR2A or SUR2B). Although Kir6.2 is widely distributed in the brain, the mechanisms that underlie the impact of Kir6.2 on emotional behavior are not yet fully understood. To clarify the role of Kir6.2 in emotional behavior, in the present study, we investigated the behavioral characteristics of Kir6.2-knockout (Kir6...
February 10, 2018: Physiology & Behavior
Hong-Fang Mei, Neha Poonit, Yi-Chun Zhang, Chu-Yuan Ye, Hui-Lin Cai, Chen-Yi Yu, Yong-Hai Zhou, Bei-Bei Wu, Jun Cai, Xiao-Hong Cai
Obstructive sleep apnea hypopnea syndrome (OSAHS) is associated with the neurocognitive deficits as a result of the neuronal cell injury. Previous studies have shown that adenosine A1 receptor (ADORA1) played an important role against hypoxia exposure, such as controlling the metabolic recovery in rat hippocampal slices and increasing the resistance in the combined effects of hypoxia and hypercapnia. However, little is known about whether ADORA1 takes part in the course of neuronal cell injury after intermittent hypoxia exposure which was the main pathological characteristic of OSAHS...
January 29, 2018: Molecular and Cellular Biochemistry
Ramazan Bal, Gurkan Ozturk, Ebru Onalan Etem, Aydin Him, Nurattin Cengiz, Tuncay Kuloglu, Mehmet Tuzcu, Caner Yildirim, Ahmet Tektemur
Major voltage-activated ionic channels of stellate cells in the ventral part of cochlear nucleus (CN) were largely characterized previously. However, it is not known if these cells are equipped with other ion channels apart from the voltage-sensitive ones. In the current study, it was aimed to study subunit composition and function of ATP-sensitive potassium channels (KATP) in stellate cells of the ventral cochlear nucleus. Subunits of KATP channels, Kir6.1, Kir6.2, SUR1, and SUR2, were expressed at the mRNA level and at the protein level in the mouse VCN tissue...
January 29, 2018: Journal of Membrane Biology
Ryo Iwaoka, Kohsuke Kataoka
Insulin mRNA expression in pancreatic islet β-cells is upregulated by extracellular glucose concentration, but the underlying mechanism remains incompletely understood. MafA is a transcriptional activator specifically enriched in β-cells that binds to the insulin gene promoter. Its expression is transcriptionally and post-transcriptionally regulated by glucose. Moreover, AMP-activated protein kinase (AMPK), a regulator of cellular energy homeostasis, is inhibited by high glucose, and this inhibition is essential for the up-regulation of insulin gene expression and glucose-stimulated insulin secretion (GSIS)...
January 18, 2018: Journal of Biological Chemistry
Kenneth Pak Kin Lee, Jue Chen, Roderick MacKinnon
In many excitable cells KATP channels respond to intracellular adenosine nucleotides: ATP inhibits while ADP activates. We present two structures of the human pancreatic KATP channel, containing the ABC transporter SUR1 and the inward-rectifier K+ channel Kir6.2, in the presence of Mg2+ and nucleotides. These structures, referred to as quatrefoil and propeller forms, were determined by single-particle cryo-EM at 3.9 Å and 5.6 Å, respectively. In both forms ATP occupies the inhibitory site in Kir6.2. The nucleotide-binding domains of SUR1 are dimerized with Mg2+-ATP in the degenerate site and Mg2+-ADP in the consensus site...
December 29, 2017: ELife
Morgana Barroso Oquendo, Nikolas Layer, Rebecca Wagner, Peter Krippeit-Drews, Gisela Drews
We have shown previously that genetic or pharmacological deletion of KATP channels protect against beta cell dysfunction induced by reactive oxygen species (ROS). Since it is assumed that glucolipotoxicity (GLTx) causes ROS production, we aimed to evaluate whether suppression of KATP channel activity can also prevent beta cell damage evoked by GLTx. We used an in vitro model of GLTx and measured distinct parameters of stimulus-secretion coupling. GLTx gradually induced disturbances of Ca2+ oscillations over 3 days...
March 2018: Pflügers Archiv: European Journal of Physiology
Mengyin Cai, Pradeep Bompada, Albert Salehi, Juan R Acosta, Rashmi B Prasad, David Atac, Markku Laakso, Leif Groop, Yang De Marinis
Osteopontin (OPN) is involved in various physiological processes and also implicated in multiple pathological states. It has been suggested that OPN may have a role in type 2 diabetes (T2D) by protecting pancreatic islets and interaction with incretins. However, the regulation and function of OPN in islets, especially in humans, remains largely unexplored. In this study, we performed our investigations on both diabetic mouse model SUR1-E1506K+/+ and islets from human donors. We demonstrated that OPN protein, secretion and gene expression was elevated in the diabetic SUR1-E1506K+/+ islets...
January 1, 2018: Biochemical and Biophysical Research Communications
Shin Nakayama, Noriko Taguchi, Yumi Isaka, Takako Nakamura, Makoto Tanaka
BACKGROUND: Cerebral edema is one of the major causes of mortality following cardiac arrest (CA) and cardiopulmonary resuscitation (CPR). A subunit of the sulfonylurea receptor 1-transient receptor potential M4 (Sur1-TRPM4) channel has been implicated in the pathogenesis of ischemia-evoked cerebral edema. In this study, we examined whether glibenclamide (GBC), a Sur1-TRPM4 channel inhibitor, attenuates cerebral edema following CA/CPR and further examined the efficacy of GBC combined with therapeutic hypothermia...
November 17, 2017: Neurocritical Care
Balamurugan Kandasamy, Show-Ling Shyng
The ATP-sensitive potassium (KATP) channel formed by the inwardly rectifying potassium channel Kir6.2 and the sulfonylurea receptor 1 (SUR1) plays a key role in regulating insulin secretion. Genetic mutations in KCNJ11 or ABCC8 which encode Kir6.2 and SUR1 respectively are major causes of insulin secretion disorders: those causing loss of channel function lead to congenital hyperinsulinism, whereas those causing gain of channel function result in neonatal diabetes and in some cases developmental delay, epilepsy, and neonatal diabetes, referred to as the DEND syndrome...
2018: Methods in Molecular Biology
Hui-Jie Hu, Mingke Song
BACKGROUND: Stroke is a leading cause of long-term disability. All neuroprotectants targeting excitotoxicity have failed to become stroke medications. In order to explore and identify new therapeutic targets for stroke, we here reviewed present studies of ionic transporters and channels that are involved in ischemic brain damage. METHOD: We surveyed recent literature from animal experiments and clinical reports in the databases of PubMed and Elsevier ScienceDirect to analyze ionic mechanisms underlying ischemic cell damage and suggest promising ideas for stroke therapy...
December 2017: Journal of Stroke and Cerebrovascular Diseases: the Official Journal of National Stroke Association
Jee Y Lee, Hae Y Choi, Chan S Park, Bong G Ju, Tae Y Yune
After spinal cord injury (SCI), blood-spinal cord barrier (BSCB) disruption and progressive hemorrhage lead to secondary injury, subsequent apoptosis and/or necrosis of neurons and glia, causing permanent neurological deficits. Growing evidence indicates that mithramycin A (MA), an anti-cancer drug, has neuroprotective effects in ischemic brain injury and Huntington's disease (HD). However, the precise mechanism underlying its protective effects is largely unknown. Here, we examined the effect of MA on BSCB breakdown and hemorrhage as well as subsequent inflammation after SCI...
November 17, 2017: Journal of Neurotrauma
Gregory M Martin, Balamurugan Kandasamy, Frank DiMaio, Craig Yoshioka, Show-Ling Shyng
Sulfonylureas are anti-diabetic medications that act by inhibiting pancreatic KATP channels composed of SUR1 and Kir6.2. The mechanism by which these drugs interact with and inhibit the channel has been extensively investigated, yet it remains unclear where the drug binding pocket resides. Here, we present a cryo-EM structure of a hamster SUR1/rat Kir6.2 channel bound to a high-affinity sulfonylurea drug glibenclamide and ATP at 3.63 Å resolution, which reveals unprecedented details of the ATP and glibenclamide binding sites...
October 24, 2017: ELife
Zhihua Du, Vladimir N Uversky
Type 2 diabetes mellitus (T2DM) is a chronic and progressive disease that is strongly associated with hyperglycemia (high blood sugar) related to either insulin resistance or insufficient insulin production. Among the various molecular events and players implicated in the manifestation and development of diabetes mellitus, proteins play several important roles. The Kyoto Encyclopedia of Genes and Genomes (KEGG) database has information on 34 human proteins experimentally shown to be related to the T2DM pathogenesis...
September 21, 2017: International Journal of Molecular Sciences
Jesse A Stokum, Min S Kwon, Seung K Woo, Orest Tsymbalyuk, Rudi Vennekens, Volodymyr Gerzanich, J Marc Simard
Astrocyte swelling occurs after central nervous system injury and contributes to brain swelling, which can increase mortality. Mechanisms proffered to explain astrocyte swelling emphasize the importance of either aquaporin-4 (AQP4), an astrocyte water channel, or of Na(+) -permeable channels, which mediate cellular osmolyte influx. However, the spatio-temporal functional interactions between AQP4 and Na(+) -permeable channels that drive swelling are poorly understood. We hypothesized that astrocyte swelling after injury is linked to an interaction between AQP4 and Na(+) -permeable channels that are newly upregulated...
January 2018: Glia
Hiroshi Hashiguchi, Zhenyu Sheng, Vanessa Routh, Volodymyr Gerzanich, J Marc Simard, Joseph Bryan
OBJECTIVES: Assess direct versus indirect action(s) of ghrelin on hypothalamic NPY neurons. MATERIALS AND METHODS: Electrophysiology was used to measure ion channel activity in NPY-GFP neurons in slice preparations. Ca2+ imaging was used to monitor ghrelin activation of isolated NPY GFP-labeled neurons. Immunohistochemistry was used to localize Trpm4, SUR1 and Kir6.2 in the hypothalamus. RESULTS: Acylated ghrelin depolarized the membrane potential (MP) of NPY-GFP neurons in brain slices...
2017: PloS One
Volodymyr Gerzanich, Tapas K Makar, Poornachander Reddy Guda, Min Seong Kwon, Jesse A Stokum, Seung Kyoon Woo, Svetlana Ivanova, Alexander Ivanov, Rupal I Mehta, Alexandra Brooke Morris, Joseph Bryan, Christopher T Bever, J Marc Simard
BACKGROUND: In multiple sclerosis (MS) and experimental autoimmune encephalomyelitis (EAE), inflammation is perpetuated by both infiltrating leukocytes and astrocytes. Recent work implicated SUR1-TRPM4 channels, expressed mostly by astrocytes, in murine EAE. We tested the hypothesis that pharmacological inhibition of SUR1 during the chronic phase of EAE would be beneficial. METHODS: EAE was induced in mice using myelin oligodendrocyte glycoprotein (MOG) 35-55. Glibenclamide (10 μg/day) was administered beginning 12 or 24 days later...
September 2, 2017: Journal of Neuroinflammation
Sabrina Undank, Julia Kaiser, Jelena Sikimic, Martina Düfer, Peter Krippeit-Drews, Gisela Drews
Atrial natriuretic peptide (ANP) influences glucose homeostasis and possibly acts as a link between the cardiovascular system and metabolism, especially in metabolic disorders like diabetes. The current study evaluated effects of ANP on β-cell function by the use of a β-cell-specific knockout of the ANP receptor with guanylate cyclase activity (βGC-A-KO). ANP augmented insulin secretion at the threshold glucose concentration of 6 mmol/L and decreased KATP single-channel activity in β-cells of control mice but not of βGC-A-KO mice...
November 2017: Diabetes
Vehpi Yildirim, Suryakiran Vadrevu, Benjamin Thompson, Leslie S Satin, Richard Bertram
Plasma insulin oscillations are known to have physiological importance in the regulation of blood glucose. In insulin-secreting β-cells of pancreatic islets, K(ATP) channels play a key role in regulating glucose-dependent insulin secretion. In addition, they convey oscillations in cellular metabolism to the membrane by sensing adenine nucleotides, and are thus instrumental in mediating pulsatile insulin secretion. Blocking K(ATP) channels pharmacologically depolarizes the β-cell plasma membrane and terminates islet oscillations...
July 2017: PLoS Computational Biology
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