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Peng Wu, Zhong-Xiuzi Gao, Xin-Peng Duan, Xiao-Tong Su, Ming-Xiao Wang, Dao-Hong Lin, Ruimin Gu, Wen-Hui Wang
AT2R (AngII [angiotensin II] type 2 receptor) is expressed in the distal nephrons. The aim of the present study is to examine whether AT2R regulates NCC (Na-Cl cotransporter) and Kir4.1 of the distal convoluted tubule. AngII inhibited the basolateral 40 pS K channel (a Kir4.1/5.1 heterotetramer) in the distal convoluted tubule treated with losartan but not with PD123319. AT2R agonist also inhibits the K channel, indicating that AT2R was involved in tonic regulation of Kir4.1. The infusion of PD123319 stimulated the expression of tNCC (total NCC) and pNCC (phosphorylated NCC; Thr53 ) by a time-dependent way with the peak at 4 days...
February 26, 2018: Hypertension
Uri Kahanovitch, Vishnu A Cuddapah, Natasha L Pacheco, Leanne M Holt, Daniel K Mulkey, Alan K Percy, Michelle L Olsen
Rett syndrome (RTT) is an X-linked neurodevelopmental disorder usually caused by mutations in methyl-CpG-binding protein 2 (MeCP2). RTT is typified by apparently normal development until 6-18 mo of age, when motor and communicative skills regress and hand stereotypies, autonomic symptoms, and seizures present. Restoration of MeCP2 function selectively to astrocytes reversed several deficits in a murine model of RTT, but the mechanism of this rescue is unknown. Astrocytes carry out many essential functions required for normal brain functioning, including extracellular K+ buffering...
January 2018: ENeuro
Wei Wu, Hang Yao, Helen W Zhao, Juan Wang, Gabriel G Haddad
Chronic mountain sickness (CMS) or Monge's disease is a disease in highlanders. These patients have a variety of neurologic symptoms such as migraine, mental fatigue, confusion, dizziness, loss of appetite, memory loss and neuronal degeneration. The cellular and molecular mechanisms underlying CMS neuropathology is not understood. In the previous study, we demonstrated that neurons derived from CMS patients' fibroblasts have a decreased expression and altered gating properties of voltage-gated sodium channel...
January 17, 2018: Neuroscience
Saeed Fadal Alrashdi, Devy Deliyanti, Dean Michael Talia, Jennifer Louise Wilkinson-Berka
Although increasing evidence indicates that endothelin-2 (Edn2) has distinct roles in tissue pathology including inflammation, glial cell dysfunction, and angiogenesis, its role in the retina and the factors that regulate its actions are not fully understood. We hypothesized that Edn2 damages the blood-retinal barrier (BRB) and this is mediated by interactions with the renin-angiotensin aldosterone system and reactive oxygen species derived from NADPH oxidase (Nox). C57BL/6J mice received an intravitreal injection of Edn2 or control vehicle to examine the blood pressure-independent effects of Edn2...
December 14, 2017: American Journal of Pathology
Shao-Ping Zhang, Man Zhang, Hong Tao, Yan Luo, Tao He, Chun-Hui Wang, Xiao-Cheng Li, Ling Chen, Lin-Na Zhang, Tao Sun, Qi-Kuan Hu
Potassium channels can be affected by epileptic seizures and serve a crucial role in the pathophysiology of epilepsy. Dimethylation of histone 3 lysine 9 (H3K9me2) and its enzyme euchromatic histone‑lysine N‑methyltransferase 2 (G9a) are the major epigenetic modulators and are associated with gene silencing. Insight into whether H3K9me2 and G9a can respond to epileptic seizures and regulate expression of genes encoding potassium channels is the main purpose of the present study. A total of 16 subtypes of potassium channel genes in pilocarpine‑modelled epileptic rats were screened by reverse transcription‑quantitative polymerase chain reaction, and it was determined that the expression ATP‑sensitive inward rectifier potassium channel 10 (Kcnj10) increased in hippocampus and insular cortex, while the expression of most of the other subtypes decreased...
January 2018: Molecular Medicine Reports
Sonia Hasan, Ameera Balobaid, Alessandro Grottesi, Omar Dabbagh, Marta Cenciarini, Rifaat Rawashdeh, Afaf Al-Sagheir, Cecilia Bove, Lara Macchioni, Mauro Pessia, Mohammed Al-Owain, Maria Cristina D'Adamo
A 2-yr-old boy presented profound developmental delay, failure to thrive, ataxia, hypotonia, and tonic-clonic seizures that caused the death of the patient. Targeted and whole exome sequencing revealed two heterozygous missense variants: a novel mutation in the KCNJ10 gene that encodes for the inward-rectifying K + channel Kir4.1 and another previously characterized mutation in KCNT1 that encodes for the Na + -activated K + channel known as Slo2.2 or SLACK. The objectives of this study were to perform the clinical and genetic characterization of the proband and his family and to examine the functional consequence of the Kir4...
October 1, 2017: Journal of Neurophysiology
Cleyton R Sobrinho, Christopher M Gonçalves, Ana C Takakura, Daniel K Mulkey, Thiago S Moreira
Evidence indicates that CO2/H(+)-evoked ATP released from retrotrapezoid nucleus (RTN) astrocytes modulates the activity of CO2-sensitive neurons. RTN astrocytes also sense H(+) by inhibition of Kir4.1 channels; however, the relevance of this pH-sensitive current remains unclear since ATP release appears to involve CO2-dependent gating of connexin 26 hemichannels. Considering that depolarization mediated by H(+) inhibition of Kir4.1 channels is expected to increase sodium bicarbonate cotransporter (NBC) conductance and favor Ca(2+) influx via the sodium calcium exchanger (NCX), we hypothesize that depolarization in the presence of CO2 is sufficient to facilitate ATP release and enhance respiratory output...
September 1, 2017: Journal of Neurophysiology
Jiaman Dai, Yan Fu, Yuxiao Zeng, Shiying Li, Zheng Qin Yin
Müller cells maintain retinal synaptic homeostasis by taking up glutamate from the synaptic cleft and transporting glutamine back to the neurons. To study the interaction between Müller cells and photoreceptors, we injected either DL-α-aminoadipate or L-methionine sulfoximine-both inhibitors of glutamine synthetase-subretinally in rats. Following injection, the a-wave of the electroretinogram (ERG) was attenuated, and metabotropic glutamate receptor 5 (mGluR5) was activated. Selective antagonism of mGluR5 by 2-methyl-6-(phenylethynyl)-pyridine increased the ERG a-wave amplitude and also increased rhodopsin expression...
June 14, 2017: Scientific Reports
Zuzanna Setkowicz, Emilia Kosonowska, Krzysztof Janeczko
Astrocytes participate in neuronal development and excitability, and produce factors enhancing or suppressing inflammatory processes occurring due to neurodegenerative diseases, such as epilepsy. Seizures, in turn, trigger the release of inflammatory mediators, causing structural and functional changes in the brain. Therefore, it appears reasonable to determine whether generalized inflammation at developmental periods can affect astrocyte reactivity to epileptic seizures occurring in the adult brain. Lipopolysaccharide (LPS) was injected in 6- or 30-day-old rats (P6 or P30, respectively)...
June 9, 2017: Journal of Anatomy
Andreas Kompatscher, Jeroen H F de Baaij, Karam Aboudehen, Anke P W M Hoefnagels, Peter Igarashi, René J M Bindels, Gertjan J C Veenstra, Joost G J Hoenderop
Hepatocyte nuclear factor 1 homeobox B (HNF1β) is an essential transcription factor for the development and functioning of the kidney. Mutations in HNF1β cause autosomal dominant tubulointerstitial kidney disease characterized by renal cysts and maturity-onset diabetes of the young (MODY). Moreover, these patients suffer from a severe electrolyte phenotype consisting of hypomagnesemia and hypokalemia. Until now, genes that are regulated by HNF1β are only partially known and do not fully explain the phenotype of the patients...
November 2017: Kidney International
Mark A Charlton-Perkins, Edward D Sendler, Elke K Buschbeck, Tiffany A Cook
Glial cells play structural and functional roles central to the formation, activity and integrity of neurons throughout the nervous system. In the retina of vertebrates, the high energetic demand of photoreceptors is sustained in part by Müller glia, an intrinsic, atypical radial glia with features common to many glial subtypes. Accessory and support glial cells also exist in invertebrates, but which cells play this function in the insect retina is largely undefined. Using cell-restricted transcriptome analysis, here we show that the ommatidial cone cells (aka Semper cells) in the Drosophila compound eye are enriched for glial regulators and effectors, including signature characteristics of the vertebrate visual system...
May 2017: PLoS Genetics
Mariapaola Marino, Giovanni Frisullo, Gabriele Di Sante, Daniela Maria Samengo, Carlo Provenzano, Massimiliano Mirabella, Giovambattista Pani, Francesco Ria, Emanuela Bartoccioni
BACKGROUND: Multiple sclerosis (MS) is an autoimmune disease for which auto-antibodies fully validated as diagnostic and prognostic biomarkers are widely desired. Recently, an immunoreactivity against the inward rectifying potassium channel 4.1 (KIR4.1) has been reported in a large proportion of a group of MS patients, with amino acids 83-120 being the major epitope. Moreover, a strong correlation between anti-KIR4.183-120 and anti-full-length-protein auto-antibodies titer was reported...
May 1, 2017: Multiple Sclerosis: Clinical and Laboratory Research
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 was 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...
September 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...
June 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
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