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Siri H Opdal, Åshild Vege, Arne Stray-Pedersen, Torleiv O Rognum
AIM: Disturbances in brain function and development may play a role in sudden infant death syndrome (SIDS). This Norwegian study aimed to test the hypothesis that specific variants of genes involved in water transport and potassium homeostasis would be predisposing factors for SIDS. METHODS: Genetic variation in the genes encoding aquaporin-4 (AQP4), Kir4.1 (KCNJ10) and α-syntrophin were analysed in 171 SIDS cases (62.6% male) with a median age of 15.5 (2-52) weeks and 398 adult controls (70...
May 18, 2017: Acta Paediatrica
Miquel Navas-Madroñal, Ana Valero-Mut, María José Martínez-Zapata, Manuel Javier Simón-Talero, Sebastián Figueroa, Nuria Vidal-Fernández, Mariana López-Góngora, Antonio Escartín, Luis Querol
INTRODUCTION: Antibodies targeting the inward-rectifying potassium channel KIR4.1 have been associated with multiple sclerosis (MS) but studies using diverse techniques have failed to replicate this association. The detection of these antibodies is challenging; KIR4.1 glycosylation patterns and the use of diverse technical approaches may account for the disparity of results. We aimed to replicate the association using three different approaches to overcome the technical limitations of a single technique...
2017: PloS One
Rong Zhong, Junyan Liang, Ailin Tao, Linzhan Wu, Xinguang Yang, Huiming Xu, Qingmei Huang, Shunzhi Zhuang, Youming Long, Cong Gao
OBJECTIVES: The aim of this study was to explore the frequency of KIR4.1 antibodies in patients with multiple sclerosis (MS) and in control groups using a cell-based assay. MATERIALS AND METHODS: A transfected HEK-293A cell line expressing KIR4.1 was established to test for the presence of KIR4.1 antibodies in blood serum. We tested 904 subjects, including 188 patients with MS, 264 patients with neuromyelitis optica spectrum disorders (NMOSD), 209 patients with other inflammatory neurologic disease (OIND), 203 patients with other noninflammatory neurological disease (OND), and 40 healthy controls...
2016: Neuroimmunomodulation
Alberto Pérez-Samartín, Edith Garay, Juan Pablo H Moctezuma, Abraham Cisneros-Mejorado, María Victoria Sánchez-Gómez, Guadalupe Martel-Gallegos, Leticia Robles-Martínez, Manuel Canedo-Antelo, Carlos Matute, Rogelio O Arellano
Inwardly rectifying K(+) (Kir) channel expression signals at an advanced stage of maturation during oligodendroglial differentiation. Knocking down their expression halts the generation of myelin and produces severe abnormalities in the central nervous system. Kir4.1 is the main subunit involved in the tetrameric structure of Kir channels in glial cells; however, the precise composition of Kir channels expressed in oligodendrocytes (OLs) remains partially unknown, as participation of other subunits has been proposed...
March 27, 2017: Neurochemical Research
Leticia G Marmolejo-Murillo, Iván A Aréchiga-Figueroa, Eloy G Moreno-Galindo, Ricardo A Navarro-Polanco, Aldo A Rodríguez-Menchaca, Meng Cui, José A Sánchez-Chapula, Tania Ferrer
Kir4.1 channels have been implicated in various physiological processes, mainly in the K(+) homeostasis of the central nervous system and in the control of glial function and neuronal excitability. Even though, pharmacological research of these channels is very limited. Chloroquine (CQ) is an amino quinolone derivative known to inhibit Kir2.1 and Kir6.2 channels with different action mechanism and binding site. Here, we employed patch-clamp methods, mutagenesis analysis, and molecular modeling to characterize the molecular pharmacology of Kir4...
April 5, 2017: European Journal of Pharmacology
Y H Gerald Chaban, Ye Chen, Elna Hertz, Leif Hertz
The Jimpy mouse illustrates the importance of interactions between astrocytes and oligodendrocytes. It has a mutation in Plp coding for proteolipid protein and DM20. Its behavior is normal at birth but from the age of ~2 weeks it shows severe convulsions associated with oligodendrocyte/myelination deficits and early death. A normally occurring increase in oxygen consumption by highly elevated K(+) concentrations is absent in Jimpy brain slices and cultured astrocytes, reflecting that Plp at early embryonic stages affects common precursors as also shown by the ability of conditioned medium from normal astrocytes to counteract histological abnormalities...
February 18, 2017: Neurochemical Research
Gerald Seifert, Christian Henneberger, Christian Steinhäuser
Astrocyte K(+) channels and the K(+) currents they mediate dwarf all other transmembrane conductances in these cells. This defining feature of astrocytes and its functional implications have been investigated intensely over the past decades. Nonetheless, many aspects of astrocyte K(+) handling and signaling remain incompletely understood. In this review, we provide an update on the diversity of K(+) channels expressed by astrocytes and new functional implications. We focus on inwardly-rectifying K(+) channels (particularly Kir4...
December 11, 2016: Brain Research Bulletin
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...
December 2016: Neuroscience and Biobehavioral Reviews
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...
December 1, 2016: Brain Research
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
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
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
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
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
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
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
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...
March 22, 2016: Molecular Brain
Ken-Ichi Nakajima, Min Zhao
No abstract text is available yet for this article.
July 3, 2016: Channels
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
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
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