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Kir4.2

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https://www.readbyqxmd.com/read/27693230/importance-of-astrocytes-for-potassium-ion-k-homeostasis-in-brain-and-glial-effects-of-k-and-its-transporters-on-learning
#1
REVIEW
Leif Hertz, Ye Chen
Initial clearance of extracellular K(+) ([K(+)]o) following neuronal excitation occurs by astrocytic uptake, because elevated [K(+)]o activates astrocytic but not neuronal Na(+),K(+)-ATPases. Subsequently, astrocytic K(+) is re-released via Kir4.1 channels after distribution in the astrocytic functional syncytium via gap junctions. The dispersal ensures widespread release, preventing renewed [K(+)]o increase and allowing neuronal Na(+),K(+)-ATPase-mediated re-uptake. Na(+),K(+)-ATPase operation creates extracellular hypertonicity and cell shrinkage which is reversed by the astrocytic cotransporter NKCC1...
September 28, 2016: Neuroscience and Biobehavioral Reviews
https://www.readbyqxmd.com/read/27671501/hmg-coa-synthase-isoenzymes-1-and-2-localize-to-satellite-glial-cells-in-dorsal-root-ganglia-and-are-differentially-regulated-by-peripheral-nerve-injury
#2
Fei Wang, Hongfei Xiang, Gregory Fischer, Zhen Liu, Matthew J Dupont, Quinn H Hogan, Hongwei Yu
In dorsal root ganglia (DRG), satellite glial cells (SGCs) tightly ensheathe the somata of primary sensory neurons to form functional sensory units. SGCs are identified by their flattened and irregular morphology and expression of a variety of specific marker proteins. In this report, we present evidence that the 3-hydroxy-3-methylglutaryl coenzyme A synthase isoenzymes 1 and 2 (HMGCS1 and HMGCS2) are abundantly expressed in SGCs. Immunolabeling with the validated antibodies revealed that both HMGCS1 and HMGCS2 are highly colabeled with a selection of SGC markers, including GS, GFAP, Kir4...
September 23, 2016: Brain Research
https://www.readbyqxmd.com/read/27489866/lack-of-kir4-1-autoantibodies-in-japanese-patients-with-ms-and-nmo
#3
Osamu Higuchi, Shunya Nakane, Waka Sakai, Yasuhiro Maeda, Masaaki Niino, Toshiyuki Takahashi, Toshiyuki Fukazawa, Seiji Kikuchi, Kazuo Fujihara, Hidenori Matsuo
OBJECTIVES: To examine anti-KIR4.1 antibodies by 2 different assays in Japanese patients with multiple sclerosis (MS) or neuromyelitis optica (NMO). METHODS: One hundred sixty serum samples from 57 patients with MS, 40 patients with NMO/NMO spectrum disorder (NMOSD), and 50 healthy controls (all were Japanese) were tested with ELISA using a synthetic peptide of the first extracellular portion of human KIR4.1. In addition, we attempted to detect anti-KIR4.1 immunoglobulin G in the serum by the luciferase immunoprecipitation systems (LIPS) with the full length of human KIR4...
October 2016: Neurology® Neuroimmunology & Neuroinflammation
https://www.readbyqxmd.com/read/27191611/changes-in-aquaporin-4-and-kir4-1-expression-in-rats-with-inherited-retinal-dystrophy
#4
S Lassiale, F Valamanesh, C Klein, D Hicks, M Abitbol, C Versaux-Botteri
Muller glial cells (MGC) are essential for normal functioning of retina. They are especially involved in potassium (K+) and water homeostasis, via inwardly rectifying K+ (Kir 4.1) and aquaporin-4 (AQP4) channels respectively. Because MGC appear morphologically and functionally altered in most retinal pathologies, we studied the expression of AQP 4 and Kir 4.1 during the time course of progressive retinal degeneration in Royal College of Surgeons (RCS) rats, an animal model for the hereditary human retinal degenerative disease Retinitis pigmentosa...
July 2016: Experimental Eye Research
https://www.readbyqxmd.com/read/27184474/ml418-the-first-selective-sub-micromolar-pore-blocker-of-kir7-1-potassium-channels
#5
Daniel R Swale, Haruto Kurata, Sujay V Kharade, Jonathan Sheehan, Rene Raphemot, Karl R Voigtritter, Eric E Figueroa, Jens Meiler, Anna L Blobaum, Craig W Lindsley, Corey R Hopkins, Jerod S Denton
The inward rectifier potassium (Kir) channel Kir7.1 (KCNJ13) has recently emerged as a key regulator of melanocortin signaling in the brain, electrolyte homeostasis in the eye, and uterine muscle contractility during pregnancy. The pharmacological tools available for exploring the physiology and therapeutic potential of Kir7.1 have been limited to relatively weak and nonselective small-molecule inhibitors. Here, we report the discovery in a fluorescence-based high-throughput screen of a novel Kir7.1 channel inhibitor, VU714...
July 20, 2016: ACS Chemical Neuroscience
https://www.readbyqxmd.com/read/27161034/myelinating-satellite-oligodendrocytes-are-integrated-in-a-glial-syncytium-constraining-neuronal-high-frequency-activity
#6
Arne Battefeld, Jan Klooster, Maarten H P Kole
Satellite oligodendrocytes (s-OLs) are closely apposed to the soma of neocortical layer 5 pyramidal neurons but their properties and functional roles remain unresolved. Here we show that s-OLs form compact myelin and action potentials of the host neuron evoke precisely timed Ba(2+)-sensitive K(+) inward rectifying (Kir) currents in the s-OL. Unexpectedly, the glial K(+) inward current does not require oligodendrocytic Kir4.1. Action potential-evoked Kir currents are in part mediated by gap-junction coupling with neighbouring OLs and astrocytes that form a syncytium around the pyramidal cell body...
2016: Nature Communications
https://www.readbyqxmd.com/read/27147650/functional-indicators-of-glutamate-transport-in-single-striatal-astrocytes-and-the-influence-of-kir4-1-in-normal-and-huntington-mice
#7
Anton Dvorzhak, Tatyana Vagner, Knut Kirmse, Rosemarie Grantyn
UNLABELLED: This study evaluates single-cell indicators of glutamate transport in sulforhodamine 101-positive astrocytes of Q175 mice, a knock-in model of Huntington's disease (HD). Transport-related fluorescent ratio signals obtained with sodium-binding benzofuran isophtalate (SBFI) AM from unperturbed or voltage-clamped astrocytes and respective glutamate transporter currents (GTCs) were induced by photolytic or synaptic glutamate release and isolated pharmacologically. The HD-induced deficit ranged from -27% (GTC maximum at -100 mV in Ba(2+)) to -41% (sodium transients in astrocytes after loading SBFI-AM)...
May 4, 2016: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/27122158/caveolin-1-regulates-corneal-wound-healing-by-modulating-kir4-1-activity
#8
Chengbiao Zhang, Xiaotong Su, Lars Bellner, Dao-Hong Lin
The expression of caveolin-1 (Cav1) in corneal epithelium is associated with regeneration potency. We used Cav1(-/-) mice to study the role of Cav1 in modulating corneal wound healing. Western blot and whole cell patch clamp were employed to study the effect of Cav1 deletion on Kir4.1 current density in corneas. We found that Ba(2+)-sensitive K(+) currents in primary cultured murine corneal epithelial cells (pMCE) from Cav1(-/-) were dramatically reduced (602 pA) compared with those from wild type (WT; 1,300 pA)...
June 1, 2016: American Journal of Physiology. Cell Physiology
https://www.readbyqxmd.com/read/27013675/dysfunctional-calcium-and-glutamate-signaling-in-striatal-astrocytes-from-huntington-s-disease-model-mice
#9
Ruotian Jiang, Blanca Diaz-Castro, Loren L Looger, Baljit S Khakh
UNLABELLED: Astrocytes tile the entire CNS, but their functions within neural circuits in health and disease remain incompletely understood. We used genetically encoded Ca(2+)and glutamate indicators to explore the rules for astrocyte engagement in the corticostriatal circuit of adult wild-type (WT) and Huntington's disease (HD) model mice at ages not accompanied by overt astrogliosis (at approximately postnatal days 70-80). WT striatal astrocytes displayed extensive spontaneous Ca(2+)signals, but did not respond to cortical stimulation, implying that astrocytes were largely disengaged from cortical input in healthy tissue...
March 23, 2016: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/27004553/electrophysiological-behavior-of-neonatal-astrocytes-in-hippocampal-stratum-radiatum
#10
Shiying Zhong, Yixing Du, Conrad M Kiyoshi, Baofeng Ma, Catherine C Alford, Qi Wang, Yongjie Yang, Xueyuan Liu, Min Zhou
BACKGROUND: Neonatal astrocytes are diverse in origin, and undergo dramatic change in gene expression, morphological differentiation and  syncytial networking throughout development. Neonatal astrocytes also play multifaceted roles in neuronal circuitry establishment. However, the extent to which neonatal astrocytes differ from their counterparts in the adult brain remains unknown. RESULTS: Based on ALDH1L1-eGFP expression or sulforhodamine 101 staining, neonatal astrocytes at postnatal day 1-3 can be reliably identified in hippocampal stratum radiatum...
2016: Molecular Brain
https://www.readbyqxmd.com/read/26983902/concerted-action-of-kcnj15-kir4-2-and-intracellular-polyamines-in-sensing-physiological-electric-fields-for-galvanotaxis
#11
Ken-Ichi Nakajima, Min Zhao
No abstract text is available yet for this article.
July 3, 2016: Channels
https://www.readbyqxmd.com/read/26887833/disruption-of-kcnj10-kir4-1-stimulates-the-expression-of-enac-in-the-collecting-duct
#12
Xiao-Tong Su, Chengbiao Zhang, Lijun Wang, Ruimin Gu, Dao-Hong Lin, Wen-Hui Wang
Kcnj10 encodes the inwardly rectifying K(+) channel 4.1 (Kir4.1) and is expressed in the basolateral membrane of late thick ascending limb, distal convoluted tubule (DCT), connecting tubule (CNT), and cortical collecting duct (CCD). In the present study, we perform experiments in postneonatal day 9 Kcnj10(-/-) or wild-type mice to examine the role of Kir.4.1 in contributing to the basolateral K(+) conductance in the CNT and CCD, and to investigate whether the disruption of Kir4.1 upregulates the expression of the epithelial Na(+) channel (ENaC)...
May 1, 2016: American Journal of Physiology. Renal Physiology
https://www.readbyqxmd.com/read/26869883/genetic-deletion-of-trek-1-or-twik-1-trek-1-potassium-channels-does-not-alter-the-basic-electrophysiological-properties-of-mature-hippocampal-astrocytes-in-situ
#13
Yixing Du, Conrad M Kiyoshi, Qi Wang, Wei Wang, Baofeng Ma, Catherine C Alford, Shiying Zhong, Qi Wan, Haijun Chen, Eric E Lloyd, Robert M Bryan, Min Zhou
We have recently shown that a linear current-to-voltage (I-V) relationship of membrane conductance (passive conductance) reflects the intrinsic property of K(+) channels in mature astrocytes. While passive conductance is known to underpin a highly negative and stable membrane potential (V M) essential for the basic homeostatic function of astrocytes, a complete repertoire of the involved K(+) channels remains elusive. TREK-1 two-pore domain K(+) channel (K2P) is highly expressed in astrocytes, and covalent association of TREK-1 with TWIK-1, another highly expressed astrocytic K2P, has been reported as a mechanism underlying the trafficking of heterodimer TWIK-1/TREK-1 channel to the membrane and contributing to astrocyte passive conductance...
2016: Frontiers in Cellular Neuroscience
https://www.readbyqxmd.com/read/26607807/m%C3%A3-ller-glia-activation-by-vegf-antagonizing-drugs-an-in%C3%A2-vitro-study-on-rat-primary-retinal-cultures
#14
Lucia Gaddini, Monica Varano, Andrea Matteucci, Cinzia Mallozzi, Marika Villa, Flavia Pricci, Fiorella Malchiodi-Albedi
The effects of the anti-Vascular Endothelial Growth Factor (VEGF) drugs ranibizumab and aflibercept were studied in Müller glia in primary mixed cultures from rat neonatal retina. Treatment with both agents induced activation of Müller glia, demonstrated by increased levels of Glial Fibrillary Acidic Protein. In addition, phosphorylated Extracellular-Regulated Kinase 1/2 (ERK 1/2) showed enhanced immunoreactivity in activated Müller glia. Treatment with aflibercept induced an increase in K(+) channel (Kir) 4...
April 2016: Experimental Eye Research
https://www.readbyqxmd.com/read/26475857/p2y1-receptor-activation-of-the-trpv4-ion-channel-enhances-purinergic-signaling-in-satellite-glial-cells
#15
Pradeep Rajasekhar, Daniel P Poole, Wolfgang Liedtke, Nigel W Bunnett, Nicholas A Veldhuis
Transient receptor potential (TRP) ion channels of peripheral sensory pathways are important mediators of pain, itch, and neurogenic inflammation. They are expressed by primary sensory neurons and by glial cells in the central nervous system, but their expression and function in satellite glial cells (SGCs) of sensory ganglia have not been explored. SGCs tightly ensheath neurons of sensory ganglia and can regulate neuronal excitability in pain and inflammatory states. Using a modified dissociation protocol, we isolated neurons with attached SGCs from dorsal root ganglia of mice...
November 27, 2015: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/26449415/kcnj15-kir4-2-couples-with-polyamines-to-sense-weak-extracellular-electric-fields-in-galvanotaxis
#16
Ken-ichi Nakajima, Kan Zhu, Yao-Hui Sun, Bence Hegyi, Qunli Zeng, Christopher J Murphy, J Victor Small, Ye Chen-Izu, Yoshihiro Izumiya, Josef M Penninger, Min Zhao
Weak electric fields guide cell migration, known as galvanotaxis/electrotaxis. The sensor(s) cells use to detect the fields remain elusive. Here we perform a large-scale screen using an RNAi library targeting ion transporters in human cells. We identify 18 genes that show either defective or increased galvanotaxis after knockdown. Knockdown of the KCNJ15 gene (encoding inwardly rectifying K(+) channel Kir4.2) specifically abolishes galvanotaxis, without affecting basal motility and directional migration in a monolayer scratch assay...
October 9, 2015: Nature Communications
https://www.readbyqxmd.com/read/26427731/developmental-expression-of-kir4-1-in-astrocytes-and-oligodendrocytes-of-rat-somatosensory-cortex-and-hippocampus
#17
Ramona Frida Moroni, Francesca Inverardi, Maria Cristina Regondi, Paolo Pennacchio, Carolina Frassoni
Kir4.1 is the principal K(+) channel expressed in glial cells. It has been shown that it plays a fundamental role in K(+)-spatial buffering, an astrocyte-specific process where excess extracellular concentration of K(+) ions, generated by synaptic activity, is spatially redistributed to distant sites via astrocytic syncytia. Experimental and clinical evidence suggested that abnormality of Kir4.1 function in the brain is involved in different neurological diseases such as epilepsy, dysmyelination, and Huntington's disease...
December 2015: International Journal of Developmental Neuroscience
https://www.readbyqxmd.com/read/26424896/trpv4-and-aqp4-channels-synergistically-regulate-cell-volume-and-calcium-homeostasis-in-retinal-m%C3%A3-ller-glia
#18
Andrew O Jo, Daniel A Ryskamp, Tam T T Phuong, Alan S Verkman, Oleg Yarishkin, Nanna MacAulay, David Križaj
Brain edema formation occurs after dysfunctional control of extracellular volume partly through impaired astrocytic ion and water transport. Here, we show that such processes might involve synergistic cooperation between the glial water channel aquaporin 4 (AQP4) and the transient receptor potential isoform 4 (TRPV4), a polymodal swelling-sensitive cation channel. In mouse retinas, TRPV4 colocalized with AQP4 in the end feet and radial processes of Müller astroglia. Genetic ablation of TRPV4 did not affect the distribution of AQP4 and vice versa...
September 30, 2015: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/26319417/vasopressin-induced-stimulation-of-the-na-activated-k-channels-is-responsible-for-maintaining-the-basolateral-k-conductance-of-the-thick-ascending-limb-tal-in-east-sesame-syndrome
#19
Lili Fan, Xiaoyan Wang, Dandan Zhang, Xinpeng Duan, Chunlei Zhao, Mingxue Zu, Xinxin Meng, Chengbiao Zhang, Xiao-Tong Su, Ming-Xiao Wang, Wen-Hui Wang, Ruimin Gu
The renal phenotype of EAST syndrome, a disease caused by the loss-of-function-mutations of Kcnj10 (Kir4.1), is a reminiscence of Gitelman's syndrome characterized by the defective function in the distal convoluted tubule (DCT). The aim of the present study is to test whether antidiuretic hormone (vasopressin)-induced stimulation of the Na(+)-activated 80-150pS K(+) channel is responsible for compensating the lost function of Kcnj10 in the thick ascending limb (TAL) of subjects with EAST syndrome. Immunostaining and western blot showed that the expression of aquaporin 2 (AQP2) was significantly higher in Kcnj10(-/-) mice than those of WT littermates, suggesting that the disruption of Kcnj10 stimulates vasopressin response in the kidney...
November 2015: Biochimica et Biophysica Acta
https://www.readbyqxmd.com/read/26283925/inner-retinal-change-in-a-novel-rd1-ftl-mouse-model-of-retinal-degeneration
#20
Ursula Greferath, Emily E Anderson, Andrew I Jobling, Kirstan A Vessey, Gemma Martinez, Robb U de Iongh, Michael Kalloniatis, Erica L Fletcher
While photoreceptor loss is the most devastating result of inherited retinal degenerations such as retinitis pigmentosa, inner retinal neurons also undergo significant alteration. Detailing these changes has become important as many vision restorative therapies target the remaining neurons. In this study, the rd1-Fos-Tau-LacZ (rd1-FTL) mouse model was used to explore inner retinal change at a late stage of retinal degeneration, after the loss of photoreceptor nuclei. The rd1-FTL model carries a mutation in the phosphodiesterase gene, Pde6b, and an axonally targeted transgenic beta galactosidase reporter system under the control of the c-fos promoter...
2015: Frontiers in Cellular Neuroscience
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