ABSTRACT
Background: Hyperpolarization-Activated Cyclic Nucleotide-Gated (HCN) ionic channels are known to play a key role in the control of neuron excitability and have been proposed as a molecular target of ethanol. Previous studies in rats have shown that gene-induced overexpression of the HCN2 channel in the ventral tegmental area (VTA) increases the rewarding effects of ethanol and its intake by the animals.Objective: The aim of this work was to study the effects of VTA HCN2 gene knockdown in the voluntary ethanol consumption of alcohol-preferring UChB rats.Methods: Two lentiviral vectors were generated; LV-siRNA-HCN2, coding for a siRNA that elicited >95% reduction of HCN2 protein levels in vitro, and a control vector coding for a scrambled siRNA sequence. Female UChB naïve rats (n = 14) were microinjected into the VTA with LV-siRNA-HCN2 or the scrambled control vector (n = 11). Four days after, animals were given a daily free access to 10% ethanol and water for 10 days.Results: Rats treated with the LV-siRNA-HCN2 vector showed a ~ 70% reduction (p < .001) in their ethanol preference and ethanol intake compared to control animals. No changes were observed in the total fluid intake of both groups. HCN2 levels in the VTA were measured by Western blot showing a reduction of 40% (p < .05) in the rats injected with LV-siRNA-HCN2, compared to control animals.Conclusion: These results show that knockdown of HCN2 ionic channels in the VTA of UChB rats markedly reduces their voluntary ethanol intake, supporting the idea that HCN2 channels may constitute a therapeutic target for alcohol use disorders.
Subject(s)
Alcoholism , Ventral Tegmental Area , Alcohol Drinking/genetics , Alcohol Drinking/metabolism , Alcoholism/genetics , Animals , Ethanol/pharmacology , Female , Gene Knockdown Techniques , Humans , Hyperpolarization-Activated Cyclic Nucleotide-Gated Channels/genetics , Hyperpolarization-Activated Cyclic Nucleotide-Gated Channels/metabolism , Potassium Channels/genetics , Potassium Channels/metabolism , RNA, Small Interfering/genetics , RNA, Small Interfering/metabolism , RNA, Small Interfering/pharmacology , Rats , Ventral Tegmental Area/metabolismABSTRACT
ETHNOPHARMACOLOGICAL RELEVANCE: Leonurus sibiricus L. (Lamiaceae) is a medicinal plant known in Brazil as "rubim" or "erva de macaé". It is used for various purposes, including stomach disorders. AIM OF THE STUDY: To evaluate the effect of the ethanol extract of the aerial parts of L. sibiricus (EELs) in models of gastric damage in mice. MATERIAL AND METHODS: The effect of EELs (50, 100 and 300 mg/kg, p.o., 1 h before induction) was tested on acidified ethanol (ACEt)-induced gastric ulcers. Additionally, we tested the effect of EELs (by intraduodenal administration) in the pylorus ligation (PL) model. RESULTS: Pretreatment with EELs, at 300 mg/kg, but not 50 and 100 mg/kg, reduced the relative area of gastric ulcers induced by ACEt (p < 0.01) and lipoperoxidation (p < 0.001), and increased the sulfhydryl content (p < 0.01) in the stomach in comparison with the vehicle group. Pretreatment with N-ethylmaleimide (a blocker of non-protein sulfhydryl groups, 10 mg/kg, i.p.) or glibenclamide (a KATP channel blocker, 10 mg/kg, i.p.) inhibited the gastroprotective response caused by EELs (300 mg/kg; p < 0.001), but there were no alterations due to pretreatments with inhibitors of the synthesis of prostaglandins (indomethacin, 10 mg/kg), nitric oxide (L-NAME, 70 mg/kg) or hydrogen sulfide (DL-propargylglycine, 10 mg/kg). Treatment with EELs (300 mg/kg) reduced mucus production (p < 0.001) and the volume of gastric secretion (p < 0.001) after PL without affecting gastric acidity or pH. CONCLUSIONS: These results provide evidence that EELs exerts gastroprotective action in mice, with the participation of oxidative stress and mediation of NP-SH, KATP channels and mucus production.
Subject(s)
Leonurus/chemistry , Phytotherapy , Plant Extracts/pharmacology , Stomach Ulcer/prevention & control , Animals , Enzyme Inhibitors/pharmacology , Ethanol/toxicity , Ethylmaleimide/pharmacology , Gene Expression Regulation/drug effects , Glyburide/pharmacology , Hypoglycemic Agents/pharmacology , Male , Mice , Nitric Oxide/metabolism , Plant Extracts/chemistry , Potassium Channels/genetics , Potassium Channels/metabolism , Prostaglandins/genetics , Prostaglandins/metabolism , Random Allocation , Sulfhydryl Compounds/metabolismABSTRACT
The aim of this study was to examine if the peripheral antinociception of α-bisabolol involves the participation of nitric oxide (NO) and cyclic guanosine monophosphate (cGMP) synthesis followed by K+ channel opening in the formalin test. Wistar rats were injected in the dorsal surface of the right hind paw with formalin (1%). Rats received a subcutaneous injection into the dorsal surface of the paw of vehicles or increasing doses of α-bisabolol (100-300 µg/paw). To determine whether the peripheral antinociception induced by α-bisabolol was mediated by either the opioid receptors or the NO-cGMP-K+ channels pathway, the effect of pretreatment (10 min before formalin injection) with the appropriate vehicles, naloxone, naltrexone, NG-nitro-l-arginine methyl ester (L-NAME), 1H-[1,2,4]-oxadiazolo[4,2-a]quinoxalin-1-one (ODQ), glibenclamide, glipizide, apamin, charybdotoxin, tetraethylammonium, or 4-aminopyridine on the antinociceptive effects induced by local peripheral α-bisabolol (300 µg/paw) were assessed. α-Bisabolol produced antinociception during both phases of the formalin test. α-Bisabolol antinociception was blocked by L-NAME, ODQ, and all the K+ channels blockers. The peripheral antinociceptive effect produced by α-bisabolol was not blocked by the opioid receptor inhibitors. α-Bisabolol was able to active the NO-cGMP-K+ channels pathway to produce its antinoceptive effect. The participation of opioid receptors in the peripheral local antinociception induced by α-bisabolol is excluded.
Subject(s)
Analgesics/pharmacology , Cyclic GMP/metabolism , Monocyclic Sesquiterpenes/pharmacology , Nitric Oxide/metabolism , Nociception/drug effects , Potassium Channels/metabolism , Receptors, Opioid/metabolism , Animals , Male , Potassium Channel Blockers/pharmacology , Potassium Channels/chemistry , Potassium Channels/genetics , Rats , Rats, Wistar , Receptors, Opioid/chemistry , Receptors, Opioid/geneticsABSTRACT
The meninges shield the nervous system from diverse, rather harmful stimuli and pathogens from the periphery. This tissue is composed of brain endothelial cells (BECs) that express diverse ion channels and chemical-transmitter receptors also expressed by neurons and glial cells to communicate with each other. However, information about the effects of ATP and angiotensin II on BECs is scarce, despite their essential roles in blood physiology. This work investigated in vitro if BECs from the meninges from rat forebrain respond to ATP, angiotensin II and high extracellular potassium, with intracellular calcium mobilizations and its second messenger-associated pathways. We found that in primary BEC cultures, both ATP and angiotensin II produced intracellular calcium responses linked to the activation of inositol trisphosphate receptors and ryanodine receptors, which led to calcium release from intracellular stores. We also used RT-PCR to explore what potassium channel subunits are expressed by primary BEC cultures and freshly isolated meningeal tissue, and which might be linked to the observed effects. We found that BECs mainly expressed the inward rectifier potassium channel subunits Kir1.1, Kir3.3, Kir 4.1 and Kir6.2. This study contributes to the understanding of the functions elicited by ATP and angiotensin II in BECs from rat meninges. SIGNIFICANCE OF THE STUDY: Brain endothelial cells (BECs) express diverse ion channels and membrane receptors, which they might use to communicate with neurons and glia. This work investigated in vitro, if BECs from the rat forebrain respond to angiotensin II and ATP with intracellular calcium mobilizations. We found that these cells did respond to said substances with intracellular calcium mobilizations linked to inositol trisphosphate and ryanodine receptor activation, which led to calcium release from intracellular stores. These findings are important because they might uncover routes of active communication between brain cells and endothelial cells.
Subject(s)
Adenosine Triphosphate/pharmacology , Angiotensin II/pharmacology , Calcium/metabolism , Endothelial Cells/drug effects , Potassium/pharmacology , Prosencephalon/metabolism , Animals , Cells, Cultured , Endothelial Cells/metabolism , Female , Male , Potassium Channels/genetics , Potassium Channels/metabolism , Prosencephalon/drug effects , Rats , Rats, WistarABSTRACT
The kidney controls body fluids, electrolyte and acid-base balance. Previously, we demonstrated that hyperpolarization-activated and cyclic nucleotide-gated (HCN) cation channels participate in ammonium excretion in the rat kidney. Since acid-base balance is closely linked to potassium metabolism, in the present work we aim to determine the effect of chronic metabolic acidosis (CMA) and hyperkalemia (HK) on protein abundance and localization of HCN3 in the rat kidney. CMA increased HCN3 protein level only in the outer medulla (2.74 ± 0.31) according to immunoblot analysis. However, immunofluorescence assays showed that HCN3 augmented in cortical proximal tubules (1.45 ± 0.11) and medullary thick ascending limb of Henle's loop (4.48 ± 0.45) from the inner stripe of outer medulla. HCN3 was detected in brush border membranes (BBM) and mitochondria of the proximal tubule by immunogold electron and confocal microscopy in control conditions. Acidosis did not alter HCN3 levels in BBM and mitochondria but augmented them in lysosomes. HCN3 was also immuno-detected in mitoautophagosomes. In the distal nephron, HCN3 was expressed in principal and intercalated cells from cortical to medullary collecting ducts. CMA did not change HCN3 abundance in these nephron segments. In contrast, HK doubled HCN3 level in cortical collecting ducts and favored its basolateral localization in principal cells from the inner medullary collecting ducts. These findings further support HCN channels contribution to renal acid-base and potassium balance.
Subject(s)
Acidosis/etiology , Acidosis/metabolism , Hyperkalemia/etiology , Hyperkalemia/metabolism , Hyperpolarization-Activated Cyclic Nucleotide-Gated Channels/metabolism , Nephrons/metabolism , Potassium Channels/metabolism , Animals , Biomarkers , Chronic Disease , Epithelial Cells/metabolism , Fluorescent Antibody Technique/methods , Gene Expression , Hyperpolarization-Activated Cyclic Nucleotide-Gated Channels/genetics , Kidney Tubules, Proximal/metabolism , Loop of Henle/metabolism , Nephrons/ultrastructure , Potassium Channels/genetics , RatsABSTRACT
Human induced pluripotent stem cell derived cardiomyocytes (hiPSC-CMs) resemble fetal cardiomyocytes and electrical stimulation (ES) has been explored to mature the differentiated cells. Here, we hypothesize that ES applied at the beginning of the differentiation process, triggers both differentiation of the hiPSC-CMs into a specialized conduction system (CS) phenotype and cell maturation. We applied ES for 15 days starting on day 0 of the differentiation process and found an increased expression of transcription factors and proteins associated with the development and function of CS including Irx3, Nkx2.5 and contactin 2, Hcn4 and Scn5a, respectively. We also found activation of intercalated disc proteins (Nrap and ß-catenin). We detected ES-induced CM maturation as indicated by increased Tnni1 and Tnni3 expression. Confocal micrographs showed a shift towards expression of the gap junction protein connexin 40 in ES hiPSC-CM compared to the more dominant expression of connexin 43 in controls. Finally, analysis of functional parameters revealed that ES hiPSC-CMs exhibited faster action potential (AP) depolarization, longer intracellular Ca2+ transients, and slower AP duration at 90% of repolarization, resembling fast conducting fibers. Altogether, we provided evidence that ES during the differentiation of hiPSC to cardiomyocytes lead to development of cardiac conduction-like cells with more mature cytoarchitecture. Thus, hiPSC-CMs exposed to ES during differentiation can be instrumental to develop CS cells for cardiac disease modelling, screening individual drugs on a precison medicine type platform and support the development of novel therapeutics for arrhythmias.
Subject(s)
Action Potentials/physiology , Calcium/metabolism , Induced Pluripotent Stem Cells/physiology , Myocytes, Cardiac/physiology , Biomarkers/metabolism , Cell Differentiation , Cell- and Tissue-Based Therapy/methods , Connexins/genetics , Connexins/metabolism , Contactin 2/genetics , Contactin 2/metabolism , Electric Stimulation , Gene Expression , Heart Conduction System/cytology , Heart Conduction System/physiology , Homeobox Protein Nkx-2.5/genetics , Homeobox Protein Nkx-2.5/metabolism , Homeodomain Proteins/genetics , Homeodomain Proteins/metabolism , Humans , Hyperpolarization-Activated Cyclic Nucleotide-Gated Channels/genetics , Hyperpolarization-Activated Cyclic Nucleotide-Gated Channels/metabolism , Induced Pluripotent Stem Cells/cytology , Muscle Proteins/genetics , Muscle Proteins/metabolism , Myocytes, Cardiac/cytology , NAV1.5 Voltage-Gated Sodium Channel/genetics , NAV1.5 Voltage-Gated Sodium Channel/metabolism , Potassium Channels/genetics , Potassium Channels/metabolism , Primary Cell Culture , Transcription Factors/genetics , Transcription Factors/metabolism , Troponin I/genetics , Troponin I/metabolism , beta Catenin/genetics , beta Catenin/metabolism , Gap Junction alpha-5 ProteinABSTRACT
S17 is a clonogenic bone marrow stromal (BMS) cell line derived from mouse that has been extensively used to assess both human and murine hematopoiesis support capacity. However, very little is known about the expression of potassium ion channels and their function in cell survival and migration in these cells. Thus, the present study was designed to characterize potassium ion channels using electrophysiological and molecular biological approaches in S17 BMS cells. The whole-cell configuration of the patch clamp technique has been applied to identify potassium ion currents and reverse transcription polymerase chain reaction (RT-PCR) used to determine their molecular identities. Based on gating kinetics and pharmacological modulation of the macroscopic currents we found the presence of four functional potassium ion channels in S17 BMS cells. These include a current rapidly activated and inactivated, tetraethylammonium-sensitive, (IKV ) in most (50%) cells; a fast activated and rapidly inactivating A-type K + current (IK A -like); a delayed rectifier K + current (IK DR ) and an inward rectifier potassium current (IK IR ), found in, respectively 4.5%, 26% and 24% of these cells. RT-PCR confirmed the presence of mRNA transcripts for the alpha subunit of the corresponding functional ion channels. Additionally, functional assays were performed to investigate the importance of potassium currents in cell survival and migration. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide analyses revealed a reduction in cell viability, while wound healing assays revealed reduced migration potential in cells incubated with different potassium channel blockers. In conclusion, our data suggested that potassium currents might play a role in the maintenance of overall S17 cell ionic homeostasis directly affecting cell survival and migration.
Subject(s)
Cell Movement , Mesenchymal Stem Cells/metabolism , Potassium Channels/metabolism , Potassium/metabolism , Animals , Cell Line , Cell Movement/drug effects , Cell Survival , Ion Channel Gating , Kinetics , Membrane Potentials , Mesenchymal Stem Cells/drug effects , Mice , Potassium Channel Blockers/pharmacology , Potassium Channels/drug effects , Potassium Channels/genetics , Signal TransductionABSTRACT
The Ih is a mixed depolarizing current present in neurons which, upon activation by hyperpolarization, modulates neuronal excitability in the mesocorticolimbic (MCL) system, an area which regulates emotions such as pleasure, reward, and motivation. Its biophysical properties are determined by HCN protein expression profiles, specifically HCN subunits 1-4. Previously, we reported that cocaine-induced behavioral sensitization increases HCN2 protein expression in all MCL areas with the Ventral Tegmental Area (VTA) showing the most significant increase. Recent evidence suggests that HCN4 also has an important expression in the MCL system. Although there is a significant expression of HCN channels in the MCL system their role in addictive processes is largely unknown. Thus, in this study we aim to compare HCN2 and HCN4 expression profiles and their cellular compartmental distribution in the MCL system, before and after cocaine sensitization. Surface/intracellular (S/I) ratio analysis indicates that VTA HCN2 subunits are mostly expressed in the cell surface in contrast to other areas tested. Our findings demonstrate that after cocaine sensitization, the HCN2 S/I ratio in the VTA was decreased whereas in the Prefrontal Cortex it was increased. In addition, HCN4 total expression in the VTA was decreased after cocaine sensitization, although the S/I ratio was not altered. Together, these results demonstrate differential cocaine effects on HCN2 and HCN4 protein expression profiles and therefore suggest a diverse Ih modulation of cellular activity during cocaine addictive processes.
Subject(s)
Cerebral Cortex/metabolism , Cocaine/pharmacology , Hyperpolarization-Activated Cyclic Nucleotide-Gated Channels/biosynthesis , Limbic System/metabolism , Potassium Channels/biosynthesis , Animals , Cerebral Cortex/drug effects , Gene Expression , Hyperpolarization-Activated Cyclic Nucleotide-Gated Channels/genetics , Limbic System/drug effects , Male , Potassium Channels/genetics , Protein Subunits/biosynthesis , Protein Subunits/genetics , Random Allocation , Rats , Rats, Sprague-DawleyABSTRACT
KCNT1 mutations are gain-of-function mutations in potassium channels resulting in severe infantile epilepsy. Herein we describe 3 infants with malignant migrating partial seizures with KCNT1 mutations accompanied by massive systemic to pulmonary collateral arteries with life-threatening hemoptysis and heart failure.
Subject(s)
Collateral Circulation , Epilepsies, Partial/genetics , Gain of Function Mutation , Nerve Tissue Proteins/genetics , Potassium Channels/genetics , Pulmonary Artery/physiopathology , Epilepsies, Partial/diagnosis , Epilepsies, Partial/physiopathology , Fatal Outcome , Female , Genetic Markers , Humans , Infant, Newborn , Male , Potassium Channels, Sodium-ActivatedABSTRACT
Tetrameric assembly of channel subunits in the endoplasmic reticulum (ER) is essential for surface expression and function of K+ channels, but the molecular mechanism underlying this process remains unclear. In this study, we found through genetic screening that ER-located J-domain-containing chaperone proteins (J-proteins) are critical for the biogenesis and physiological function of ether-a-go-go-related gene (ERG) K+ channels in both Caenorhabditis elegans and human cells. Human J-proteins DNAJB12 and DNAJB14 promoted tetrameric assembly of ERG (and Kv4.2) K+ channel subunits through a heat shock protein (HSP) 70-independent mechanism, whereas a mutated DNAJB12 that did not undergo oligomerization itself failed to assemble ERG channel subunits into tetramers in vitro and in C. elegans. Overexpressing DNAJB14 significantly rescued the defective function of human ether-a-go-go-related gene (hERG) mutant channels associated with long QT syndrome (LQTS), a condition that predisposes to life-threatening arrhythmia, by stabilizing the mutated proteins. Thus, chaperone proteins are required for subunit stability and assembly of K+ channels.
Subject(s)
Caenorhabditis elegans Proteins/metabolism , Caenorhabditis elegans/metabolism , ERG1 Potassium Channel/metabolism , Endoplasmic Reticulum/metabolism , HSP40 Heat-Shock Proteins/metabolism , HSP47 Heat-Shock Proteins/metabolism , Potassium Channels/metabolism , Animals , Animals, Genetically Modified , Caenorhabditis elegans/genetics , Caenorhabditis elegans Proteins/chemistry , Caenorhabditis elegans Proteins/genetics , Cell Line, Tumor , ERG1 Potassium Channel/chemistry , ERG1 Potassium Channel/genetics , HEK293 Cells , HSP40 Heat-Shock Proteins/chemistry , HSP40 Heat-Shock Proteins/genetics , HSP47 Heat-Shock Proteins/chemistry , HSP47 Heat-Shock Proteins/genetics , HSP70 Heat-Shock Proteins/metabolism , Humans , Induced Pluripotent Stem Cells/metabolism , Long QT Syndrome/genetics , Long QT Syndrome/metabolism , Membrane Potentials , Molecular Chaperones , Mutation , Myocytes, Cardiac/metabolism , Potassium Channels/chemistry , Potassium Channels/genetics , Protein Multimerization , Protein Stability , Protein Structure, Quaternary , RNA Interference , Shal Potassium Channels/genetics , Shal Potassium Channels/metabolism , Time Factors , TransfectionABSTRACT
KCNQ1 (KvLQT1) is the pore-forming a-subunit of the potassium channel. To uncover its role in electrolyte metabolism, we investigated the effects of KCNQ1 A340E, a loss-of-function mutant, on J343 mice. Compared with the normal controls (C57BL/6J mice) bearing the wild-type KCNQ1 gene, J343 mice bearing KCNQ1 A340E demonstrated a much higher 24-h intake of electrolytes (potassium, sodium, and chloride). However, they suffered from significant electrolyte loss through both the feces and urine during a period of 24 h. Unbalance in electrolyte metabolism disrupted the electrolyte homeostasis in the J343 mice, which was characterized by the comparatively lower level of serum potassium (J343 vs C57BL/6J: 12.06 ± 1.47 vs 14.44 ± 3.58 mM, P = 0.01) and higher levels of serum sodium (J343 vs C57BL/6J: 148.05 ± 4.47 vs 115.15 ± 17.25 mM, P = 4.20 x 10(-4)) and chloride (J343 vs C57BL/6J: 118.0 ± 4.47 vs 85.21 ± 11.90 mM, P = 2.47 x 10(-5)). Between the J343 and C57BL/6J mice, there was no statistically significant difference in KCNQ1 expression in the gastrointestinal tract and kidney. Normal concentrations of plasma renin, angiotensin I, and aldosterone were also detected in both lines of mice. KCNQ1, therefore, is suggested to play a central role in electrolyte metabolism. KCNQ1 A340E, with the loss-of-function phenotype, may dysregulate electrolyte homeostasis in mice independently of the activity of the renin-angiotensin-aldosterone system.
Subject(s)
KCNQ1 Potassium Channel/genetics , KCNQ1 Potassium Channel/metabolism , Renin-Angiotensin System/physiology , Aldosterone/blood , Angiotensins/blood , Animals , Electrolytes/metabolism , Homeostasis , Kidney/metabolism , Male , Mice , Mice, Inbred C57BL , Mice, Mutant Strains , Polymorphism, Single Nucleotide , Potassium Channels/genetics , Potassium Channels/metabolism , Renin/blood , Renin-Angiotensin System/genetics , Water-Electrolyte BalanceABSTRACT
OBJECTIVES: Toll-like receptors and complement are two components of the innate immunity. Complement factor B is essential for the alternative pathway of complement activation. We have recently reported that complement factor B is significantly up-regulated in the kidney and may contribute to acute tubular injury in an animal model of sepsis. This study investigates the mechanisms responsible for the complement factor B up-regulation and its role in sodium transporter expression in tubular cells during sepsis. DESIGN: Animal study. SETTING: Laboratory investigation. SUBJECTS: C57BL/6 J wild-type, complement factor B(-/-), and Nfkb1(tm1Bal) p50(-/-) mice. INTERVENTIONS: Human proximal tubular cells and mouse tubular epithelial cells were stimulated with Toll-like receptor agonists. Bay 11-7082 was used to block nuclear factor-κB pathway. Alternative pathway activation was detected by C3 zymosan deposition. Polymicrobial sepsis was created by cecal ligation and puncture. Sodium transporter gene expression was determined by quantitative reverse transcriptase-polymerase chain reaction. MEASUREMENTS AND MAIN RESULTS: The agonists for Toll-like receptor 4 (lipopolysaccharide) or Toll-like receptor 3 (polyinosinic-polycytidylic acid) induced a marked increase in complement factor B expression in human proximal tubular cells and mouse tubular epithelial cells both at gene and protein levels. The Toll-like receptor 1/2 agonist, Pam3cys, induced complement factor B production only in human proximal tubular cells, not in mouse tubular epithelial cells. The Toll-like receptor 9 ligand, CpG oligodeoxynucleotides failed to induce complement factor B production either in human proximal tubular cells or in mouse tubular epithelial cells. Lipopolysaccharide/polyinosinic-polycytidylic acid-induced complement factor B up-regulation was blocked by Bay 11-7082, a potent inhibitor of nuclear factor-κB signaling, and in mouse tubular epithelial cells deficient in p50 subunit of nuclear factor-κB. Media from the lipopolysaccharide-treated mouse tubular epithelial cell cultures contained de novo synthesized complement factor B and led to functional alternative pathway activation. In a cecal ligation and puncture model, wild-type septic mice had down-regulated expression of sodium transporters in the kidney compared with the sham. In comparison, complement factor B mice or mice treated with anti-complement factor B displayed preserved levels of Naâº/K⺠ATPase-α1 following sepsis. CONCLUSIONS: 1) Toll-like receptor 3/4 activation is sufficient to induce complement factor B production via nuclear factor-κB pathway and to enhance alternative pathway activation in the kidney tubular epithelial cells. 2) Complement factor B may contribute to the down-regulation of certain sodium transporter expression during sepsis.
Subject(s)
Complement Factor B/biosynthesis , Kidney/physiopathology , Sepsis/physiopathology , Animals , Biological Transport, Active/physiology , Disease Models, Animal , Down-Regulation , Epithelial Sodium Channels/genetics , Female , Gene Expression , Humans , Kidney Tubules, Proximal/metabolism , Male , Mice , Mice, Inbred C57BL , NF-kappa B/antagonists & inhibitors , Nitriles/pharmacology , Potassium Channels/genetics , Reverse Transcriptase Polymerase Chain Reaction , Signal Transduction/physiology , Sulfones/pharmacology , Toll-Like Receptors/agonists , Toll-Like Receptors/genetics , Up-RegulationABSTRACT
Psychostimulant addiction is associated with dysfunctions in frontal cortex. Previous data demonstrated that repeated exposure to methamphetamine (METH) can alter prefrontal cortex (PFC)-dependent functions. Here, we show that withdrawal from repetitive non-contingent METH administration (7 days, 1 mg/kg) depressed voltage-dependent calcium currents (ICa ) and increased hyperpolarization-activated cation current (IH ) amplitude and the paired-pulse ratio of evoked excitatory postsynaptic currents (EPSCs) in deep-layer pyramidal mPFC neurons. Most of these effects were blocked by systemic co-administration of the D1/D5 receptor antagonist SCH23390 (0.5 and 0.05 mg/kg). In vitroâ METH (i.e. bath-applied to slices from naïve-treated animals) was able to emulate its systemic effects on ICa and evoked EPSCs paired-pulse ratio. We also provide evidence of altered mRNA expression of (1) voltage-gated calcium channels P/Q-type Cacna1a (Cav 2.1), N-type Cacna1b (Cav 2.2), T-type Cav 3.1 Cacna1g, Cav 3.2 Cacna1h, Cav 3.3 Cacna1i and the auxiliary subunit Cacna2d1 (α2δ1); (2) hyperpolarization-activated cyclic nucleotide-gated channels Hcn1 and Hcn2; and (3) glutamate receptors subunits AMPA-type Gria1, NMDA-type Grin1 and metabotropic Grm1 in the mouse mPFC after repeated METH treatment. Moreover, we show that some of these changes in mRNA expression were sensitive D1/5 receptor blockade. Altogether, these altered mechanisms affecting synaptic physiology and transcriptional regulation may underlie PFC functional alterations that could lead to PFC impairments observed in METH-addicted individuals.
Subject(s)
Calcium/metabolism , Dopamine Uptake Inhibitors/pharmacology , Methamphetamine/pharmacology , Prefrontal Cortex/drug effects , Pyramidal Cells/drug effects , RNA, Messenger/drug effects , Receptors, Dopamine D1/metabolism , Receptors, Dopamine D5/metabolism , Synaptic Transmission/drug effects , Animals , Benzazepines/pharmacology , Calcium Channels/drug effects , Calcium Channels/genetics , Calcium Channels, N-Type/drug effects , Calcium Channels, N-Type/genetics , Calcium Channels, T-Type/drug effects , Calcium Channels, T-Type/genetics , Hyperpolarization-Activated Cyclic Nucleotide-Gated Channels/drug effects , Hyperpolarization-Activated Cyclic Nucleotide-Gated Channels/genetics , Male , Mice , Nerve Tissue Proteins/drug effects , Nerve Tissue Proteins/genetics , Potassium Channels/drug effects , Potassium Channels/genetics , Prefrontal Cortex/metabolism , Pyramidal Cells/metabolism , RNA, Messenger/metabolism , Receptors, AMPA/drug effects , Receptors, AMPA/genetics , Receptors, Dopamine D1/antagonists & inhibitors , Receptors, Dopamine D5/antagonists & inhibitors , Receptors, N-Methyl-D-Aspartate/drug effects , Receptors, N-Methyl-D-Aspartate/geneticsABSTRACT
Genome-wide association studies have reported numerous susceptibility loci for Parkinson's disease (PD). However, there have been few replication studies examining these loci in northern Chinese populations. To evaluate the relationships among 3 polymorphic markers located in the fibroblast growth factor 20 and transmembrane protein 175 genes and the genetic susceptibility to PD in northern Chinese subjects, 2 single nucleotide polymorphisms, and 1 insertion/deletion marker (rs591323 in FGF20; rs6599388 and rs142821586 in transmembrane protein 175 near the G-associated kinase/diacylglycerol kinase theta region) were investigated in 313 PD patients and 318 matched controls. Mismatched multiplex polymerase chain reaction-restriction fragment length polymorphism analysis as well as sequence-specific primer polymerase chain reaction and restriction fragment length polymorphism assays were performed. The genotypic frequency of rs591323 differed significantly between the patient and control groups; however, neither rs6599388 nor rs142821586 was associated with PD. We corrected the Hardy-Weinberg disequilibrium for rs6599388, which was previously reported to be common in 4 Asian descent populations into equilibrium status by simultaneously genotyping rs6599388 and rs142821586. In summary, we found that rs591323 was associated with PD but rs6599388 and rs142821586 were not associated with PD in a northern Chinese population.
Subject(s)
Fibroblast Growth Factors/genetics , Parkinson Disease/genetics , Polymorphism, Single Nucleotide , Potassium Channels/genetics , Aged , Alleles , Asian People/genetics , Case-Control Studies , China , Female , Genetic Association Studies , Genetic Markers , Genetic Predisposition to Disease , Genotype , Humans , INDEL Mutation , Male , Middle Aged , Odds RatioABSTRACT
Phototaxis in flagellated zoospores of the aquatic fungus Blastocladiella emersonii depends on a novel photosensor, Blastocladiella emersonii GC1 (BeGC1), comprising a type I (microbial) rhodopsin fused to a guanylyl cyclase catalytic domain, that produces the conserved second messenger cyclic GMP (cGMP). The rapid and transient increase in cGMP levels during the exposure of zoospores to green light was shown to be necessary for phototaxis and dependent on both rhodopsin function and guanylyl cyclase activity. It is noteworthy that BeGC1 was localized to the zoospore eyespot apparatus, in agreement with its role in the phototactic response. A putative cyclic nucleotide-gated channel (BeCNG1) was also identified in the genome of the fungus and was implicated in flagellar beating via the action of a specific inhibitor (l-cis-diltiazem) that compromised zoospore motility. Here we show that B. emersonii expresses a K(+) channel that is activated by cGMP. The use of specific channel inhibitors confirmed the activation of the channel by cGMP and its K(+) selectivity. These characteristics are consistent with the function of an ion channel encoded by the BeCNG1 gene. Other blastocladiomycete fungi, such as Allomyces macrogynus and Catenaria anguillulae, possess genes encoding a similar K(+) channel and the rhodopsin-guanylyl cyclase fusion protein, while the genes encoding both these proteins are absent in nonflagellated fungi. The presence of these genes as a pair seems to be an exclusive feature of blastocladiomycete fungi. Taken together, these data demonstrate that the B. emersonii cGMP-activated K(+) channel is involved in the control of zoospore motility, most probably participating in the cGMP-signaling pathway for the phototactic response of the fungus.
Subject(s)
Blastocladiomycota/metabolism , Cyclic Nucleotide-Gated Cation Channels/metabolism , Fungal Proteins/metabolism , Potassium Channels/metabolism , Blastocladiomycota/genetics , Blastocladiomycota/physiology , Cyclic GMP/metabolism , Cyclic Nucleotide-Gated Cation Channels/genetics , Fungal Proteins/genetics , Membrane Potentials , Potassium/metabolism , Potassium Channels/genetics , Spores, Fungal/metabolismABSTRACT
Diabetes mellitus is a public health problem, which affects a millions worldwide. Most diabetes cases are classified as type 2 diabetes mellitus, which is highly associated with obesity. Type 2 diabetes is considered a multifactorial disorder, with both environmental and genetic factors contributing to its development. An important issue linked with diabetes development is the failure of the insulin releasing mechanism involving abnormal activity of the ATP-dependent potassium channel, KATP. This channel is a transmembrane protein encoded by the KCNJ11 and ABCC8 genes. Furthermore, polymorphisms in these genes have been linked to type 2 diabetes because of the role of KATP in insulin release. While several genetic variations have been reported to be associated with this disease, the E23K polymorphism is most commonly associated with this pathology, as well as to obesity. Here, we review the molecular genetics of the potassium channel and discusses its most described polymorphisms and their associations with type 2 diabetes mellitus.
Subject(s)
Adenosine Triphosphate/metabolism , Diabetes Mellitus, Type 2/metabolism , Potassium Channels/metabolism , Animals , Diabetes Mellitus, Type 2/genetics , Genetic Predisposition to Disease/genetics , Humans , Polymorphism, Genetic/genetics , Potassium Channels/genetics , Potassium Channels, Inwardly Rectifying/genetics , Potassium Channels, Inwardly Rectifying/metabolism , Sulfonylurea Receptors/genetics , Sulfonylurea Receptors/metabolismABSTRACT
Introduction: Tuberculosis is a common opportunistic infection in renal transplant patients. Objective: To obtain a clinical and laboratory description of transplant patients diagnosed with tuberculosis and their response to treatment during a period ranging from 2005 to 2013 at the Pablo Tobón Uribe Hospital. Methods: Retrospective and descriptive study. Results: In 641 renal transplants, tuberculosis was confirmed in 12 cases. Of these, 25% had a history of acute rejection, and 50% had creatinine levels greater than 1.5 mg/dl prior to infection. The disease typically presented as pulmonary (50%) and disseminated (33.3%). The first phase of treatment consisted of 3 months of HZRE (isoniazid, pyrazinamide, rifampicin and ethambutol) in 75% of the cases and HZME (isoniazid, pyrazinamide, moxifloxacin and ethambutol) in 25% of the cases. During the second phase of the treatment, 75% of the cases received isoniazid and rifampicin, and 25% of the cases received isoniazid and ethambutol. The length of treatment varied between 6 and 18 months. In 41.7% of patients, hepatotoxicity was associated with the beginning of anti-tuberculosis therapy. During a year-long follow-up, renal function remained stable, and the mortality rate was 16.7%. Conclusion: Tuberculosis in the renal transplant population studied caused diverse nonspecific symptoms. Pulmonary and disseminated tuberculosis were the most frequent forms and required prolonged treatment. Antituberculosis medications had a high toxicity and mortality. This infection must be considered when patients present with a febrile syndrome of unknown origin, especially during the first year after renal transplant. .
Introdução: A tuberculose é uma infecção oportunista comum em pacientes transplantados renais. Objetivo: Oferecer uma descrição clínica e laboratorial de pacientes transplantados com diagnóstico de tuberculose e sua resposta ao tratamento durante o período entre 2005 e 2013 no Hospital Pablo Tobón Uribe. Métodos: Estudo retrospectivo descritivo. Resultados: Em 641 transplantes renais, a tuberculose foi confirmada em 12 pacientes. Destes, 25% tinham histórico de rejeição aguda e 50% apresentaram níveis de creatinina superiores a 1,5 mg/dl antes da infecção. A patologia geralmente se apresentava como pulmonar (50%) e disseminada (33,3%). A primeira fase do tratamento consistiu de três meses de HZRE (isoniazida, pirazinamida, rifampicina e etambutol) em 75% dos casos e HZME (isoniazida, pirazinamida, moxifloxacina e etambutol) em 25% dos pacientes. Durante a segunda fase do tratamento, 75% dos pacientes receberam isoniazida e rifampicina e 25% isoniazida e etambutol. A duração do tratamento variou entre seis e 18 meses. Em 41,7% dos pacientes, hepatotoxicidade foi associada ao início do tratamento da tuberculose. Durante o seguimento de um ano a função renal manteve-se estável e a taxa de mortalidade foi de 16,7%. Conclusão: A tuberculose foi responsável por diversos sintomas inespecíficos na população de transplantados renais estudada. Tuberculose pulmonar e disseminada foram as formas mais frequentes de acometimento e necessitaram de tratamento prolongado. Medicamentos contra a tuberculose apresentaram alta toxicidade e mortalidade. Esta infecção deve ser considerada quando o paciente apresenta síndrome febril de origem desconhecida, especialmente durante o primeiro ano após o transplante renal. .
Subject(s)
Animals , Female , Male , Mice , Locus Coeruleus/drug effects , Narcotics/pharmacology , Neural Inhibition/drug effects , Neurons/drug effects , Potassium Channels/metabolism , Barium/pharmacology , Calcium/metabolism , Enkephalin, Methionine/pharmacology , G Protein-Coupled Inwardly-Rectifying Potassium Channels , GTP-Binding Proteins/metabolism , Heterozygote , Homozygote , Ion Channel Gating/drug effects , Ion Channel Gating/physiology , Locus Coeruleus/cytology , Locus Coeruleus/physiology , Mice, Knockout , Membrane Potentials/drug effects , Membrane Potentials/physiology , Neural Inhibition/physiology , Neurons/physiology , Patch-Clamp Techniques , Protein Subunits , Potassium Channel Blockers/pharmacology , Potassium Channels, Inwardly Rectifying/antagonists & inhibitors , Potassium Channels, Inwardly Rectifying/deficiency , Potassium Channels, Inwardly Rectifying/genetics , Potassium Channels, Inwardly Rectifying/metabolism , Potassium Channels/deficiency , Potassium Channels/geneticsABSTRACT
Migrating partial seizures of infancy is an early onset epileptic encephalopathy syndrome that is typically resistant to treatment. The most common cause is a gain of function mutation in the potassium channel KCNT1. The antiarrhythmic drug quinidine is a partial antagonist of KCNT1 and hence may be a candidate drug for treatment of this condition. We report the case of a child with migrating partial seizures of infancy secondary to an activating mutation in KCNT1 treated with quinidine. Treatment with quinidine was correlated with a marked reduction in seizure frequency and improved psychomotor development.
Subject(s)
Anti-Arrhythmia Agents/pharmacology , Epilepsies, Partial/drug therapy , Nerve Tissue Proteins/antagonists & inhibitors , Quinidine/pharmacology , Anti-Arrhythmia Agents/administration & dosage , Child, Preschool , Dose-Response Relationship, Drug , Electroencephalography , Epilepsies, Partial/genetics , Epilepsies, Partial/physiopathology , Exons/genetics , Female , Humans , Mutation, Missense/genetics , Nerve Tissue Proteins/genetics , Potassium Channels/genetics , Potassium Channels, Sodium-Activated , Quinidine/administration & dosage , Treatment OutcomeABSTRACT
In Brazil, Tityus serrulatus (Ts) is the species responsible for most of the scorpion related accidents. Among the Ts toxins, the neurotoxins with action on potassium channels (α-KTx) present high interest, due to their effect in the envenoming process and the ion channel specificity they display. The α-KTx toxins family is the most relevant because its toxins can be used as therapeutic tools for specific target cells. The improved isolation method provided toxins with high resolution, obtaining pure Ts6 and Ts7 in two chromatographic steps. The effects of Ts6 and Ts7 toxins were evaluated in 14 different types of potassium channels using the voltage-clamp technique with two-microelectrodes. Ts6 toxin shows high affinity for Kv1.2, Kv1.3 and Shaker IR, blocking these channels in low concentrations. Moreover, Ts6 blocks the Kv1.3 channel in picomolar concentrations with an IC50 of 0.55 nM and therefore could be of valuable assistance to further designing immunosuppressive therapeutics. Ts7 toxin blocks multiple subtypes channels, showing low selectivity among the channels analyzed. This work also stands out in its attempt to elucidate the residues important for interacting with each channel and, in the near future, to model a desired drug.
Subject(s)
Neurotoxins/pharmacology , Potassium Channel Blockers/pharmacology , Potassium Channels/physiology , Scorpion Venoms/pharmacology , Amino Acid Sequence , Animals , Molecular Sequence Data , Oocytes , Potassium Channels/genetics , Scorpion Venoms/chemistry , Scorpion Venoms/isolation & purification , Scorpions , Sequence Alignment , Xenopus laevisABSTRACT
Congenital or familial short QT syndrome is a genetically heterogeneous cardiac channelopathy without structural heart disease that has a dominant autosomal or sporadic pattern of transmission affecting the electric system of the heart. Patients present clinically with a spectrum of signs and symptoms including irregular palpitations due to episodes of paroxysmal atrialfibrillation, dizziness and fainting (syncope) and/or sudden cardiac death due to polymorphic ventricular tachycardia and ventricular fibrillation. Electrocardiographic (ECG) findings include extremely short QTc intervals (QTc interval ≤330 ms) not significantly modified with heart rate changes and T waves of great voltage witha narrow base. Electrophysiologic studies are characterized by significant shortening of atrial and ventricular refractory periods and arrhythmias induced by programmed stimulation. A few families have been identified with specific genotypes: 3 with mutations in potassium channels called SQT1 (Iks), SQT2 (Ikr) and SQT3 (Ik1). These 3 potassium channel variants are the "genetic mirror image" of long QT syndrome type 2, type 1 and Andersen-Tawil syndrome respectively because they exert opposite gain-of-function effects on the potassium channels in contrast to the loss-of-function of the potassium channels in the long QT syndromes. Three new variants with overlapping phenotypes affecting the slow inward calcium channels havealso been described. Finally, another variant with mixed phenotype affecting the sodium channel was reported. This review focuses the landmarks of this newest arrhythmogenic cardiac channelopathy on the main clinical, genetic, and proposed ECG mechanisms. In addition therapeutic options and the molecular autopsy of this fascinating primary electrical heart disease are discussed.