Oxygen sensing by ion channels

2007 ◽  
Vol 43 ◽  
pp. 77-90 ◽  
Author(s):  
Paul J. Kemp ◽  
Chris Peers
Keyword(s):  
Ion Channels ◽  
Heterologous Expression ◽  
Sodium Channel ◽  
Recombinant Proteins ◽  
Molecular Mechanisms ◽  
Oxygen Sensing ◽  
Life Forms ◽  
Dynamic Modulation ◽  
Oxygen Sensitive ◽  
Acute Oxygen Sensing

The ability to sense and react to changes in environmental oxygen levels is crucial to the survival of all aerobic life forms. In mammals, specialized tissues have evolved which can sense and rapidly respond to an acute reduction in oxygen and central to this ability in many is dynamic modulation of ion channels by hypoxia. The most widely studied oxygen-sensitive ion channels are potassium channels but oxygen sensing by members of both the calcium and sodium channel families has also been demonstrated. This chapter will focus on mechanisms of physiological oxygen sensing by ion channels, with particular emphasis on potassium channel function, and will highlight some of the consensuses and controversies within the field. Where data are available, this chapter will also make use of information gleaned from heterologous expression of recombinant proteins in an attempt to consolidate what we know currently about the molecular mechanisms of acute oxygen sensing by ion channels.

scholarly journals Acute oxygen sensing by the carotid body: a rattlebag of molecular mechanisms

2017 ◽  
Vol 596 (15) ◽  
pp. 2969-2976 ◽  
Author(s):  
Ryan J. Rakoczy ◽  
Christopher N. Wyatt
Keyword(s):  
Carotid Body ◽  
Molecular Mechanisms ◽  
Oxygen Sensing ◽  
Acute Oxygen Sensing

Ligand-gated ion channels as targets of neuroactive insecticides

2021 ◽  
Author(s):  
Makoto Ihara
Keyword(s):  
Ion Channels ◽  
Molecular Mechanisms ◽  
Functional Expression ◽  
X Ray ◽  
Acetylcholine Binding Protein ◽  
Site Selectivity ◽  
Future Drug ◽  
Cl Channels ◽  
Gated Ion Channels ◽  
Ligand Gated Ion Channels

Abstract The Cys-loop superfamily of ligand-gated ion channels (Cys-loop receptors) is one of the most ubiquitous ion channel families in vertebrates and invertebrates. Despite their ubiquity, they are targeted by several classes of pesticides, including neonicotinoids, phenylpyrazols, and macrolides such as ivermectins. The current commercialized compounds have high target site selectivity, which contributes to the safety of insecticide use. Structural analyses have accelerated progress in this field; notably, the X-ray crystal structures of acetylcholine binding protein and glutamate-gated Cl channels revealed the details of the molecular interactions between insecticides and their targets. Recently, the functional expression of the insect nicotinic acetylcholine receptor (nAChR) has been described, and detailed evaluations using the insect nAChR have emerged. This review discusses the basic concepts and the current insights into the molecular mechanisms of neuroactive insecticides targeting the ligand-gated ion channels, particularly Cys-loop receptors, and presents insights into target-based selectivity, resistance, and future drug design.

scholarly journals Molecular mechanisms of taste transduction

2002 ◽  
Vol 74 (7) ◽  
pp. 1125-1133 ◽  
Author(s):  
Robert F. Margolskee
Keyword(s):  
Ion Channels ◽  
Molecular Cloning ◽  
G Proteins ◽  
Molecular Mechanisms ◽  
Transmembrane Helix ◽  
Taste Receptor ◽  
Sweet Taste ◽  
Chemical Diversity ◽  
Chemical Information ◽  
Taste Transduction

Taste transduction is a specialized form of signal transduction by which taste receptor cells (TRCs) encode at the cellular level information about chemical substances encountered in the oral environment (so-called tastants). Bitter and sweet taste transduction pathways convert chemical information into a cellular second messenger code utilizing cyclic nucleotides, inositol trisphosphate, and/or diacyl glycerol. These messengers are components of signaling cascades that lead to TRC depolarization and Ca++ release. Bitter and sweet taste transduction pathways typically utilize taste-specific or taste-selective seven transmembrane-helix receptors, G proteins, effector enzymes, second messengers, and ion channels. The structural and chemical diversity of tastants has led to the need for multiple transduction mechanisms. Through molecular cloning and data mining, many of the receptors, G proteins, and effector enzymes involved in transducing responses to bitter and sweet compounds are now known. New insights into taste transduction and taste coding underlying sweet and bitter taste qualities have been gained from molecular cloning of the transduction elements, biochemical elucidation of the transduction pathways, electrophysiological analysis of the function of taste cell ion channels, and behavioral analysis of transgenic and knockout models.

scholarly journals LPHN2 inhibits vascular permeability by differential control of endothelial cell adhesion

2021 ◽  
Vol 220 (11) ◽  
Author(s):  
Chiara Camillo ◽  
Nicola Facchinello ◽  
Giulia Villari ◽  
Giulia Mana ◽  
Noemi Gioelli ◽  
...  
Keyword(s):  
Endothelial Cell ◽  
Focal Adhesion ◽  
Nuclear Localization ◽  
Molecular Mechanisms ◽  
Transcriptional Regulators ◽  
Dependent Manner ◽  
Knock Out ◽  
Dynamic Modulation ◽  
Differential Control ◽  
G Protein Coupled

Dynamic modulation of endothelial cell-to-cell and cell–to–extracellular matrix (ECM) adhesion is essential for blood vessel patterning and functioning. Yet the molecular mechanisms involved in this process have not been completely deciphered. We identify the adhesion G protein–coupled receptor (ADGR) Latrophilin 2 (LPHN2) as a novel determinant of endothelial cell (EC) adhesion and barrier function. In cultured ECs, endogenous LPHN2 localizes at ECM contacts, signals through cAMP/Rap1, and inhibits focal adhesion (FA) formation and nuclear localization of YAP/TAZ transcriptional regulators, while promoting tight junction (TJ) assembly. ECs also express an endogenous LPHN2 ligand, fibronectin leucine-rich transmembrane 2 (FLRT2), that prevents ECM-elicited EC behaviors in an LPHN2-dependent manner. Vascular ECs of lphn2a knock-out zebrafish embryos become abnormally stretched, display a hyperactive YAP/TAZ pathway, and lack proper intercellular TJs. Consistently, blood vessels are hyperpermeable, and intravascularly injected cancer cells extravasate more easily in lphn2a null animals. Thus, LPHN2 ligands, such as FLRT2, may be therapeutically exploited to interfere with cancer metastatic dissemination.

scholarly journals Hydrogen, Bicarbonate, and Their Associated Exchangers in Cell Volume Regulation

2021 ◽  
Vol 9 ◽  
Author(s):  
Yizeng Li ◽  
Xiaohan Zhou ◽  
Sean X. Sun
Keyword(s):  
Ion Channels ◽  
Cell Volume ◽  
Volume Regulation ◽  
Mammalian Cells ◽  
Molecular Mechanisms ◽  
Cell Function ◽  
Water Flux ◽  
Cell Volume Regulation ◽  
Sodium Potassium ◽  
Before And After

Cells lacking a stiff cell wall, e.g., mammalian cells, must actively regulate their volume to maintain proper cell function. On the time scale that protein production is negligible, water flow in and out of the cell determines the cell volume variation. Water flux follows hydraulic and osmotic gradients; the latter is generated by various ion channels, transporters, and pumps in the cell membrane. Compared to the widely studied roles of sodium, potassium, and chloride in cell volume regulation, the effects of proton and bicarbonate are less understood. In this work, we use mathematical models to analyze how proton and bicarbonate, combined with sodium, potassium, chloride, and buffer species, regulate cell volume upon inhibition of ion channels, transporters, and pumps. The model includes several common, widely expressed ion transporters and focuses on obtaining generic outcomes. Results show that the intracellular osmolarity remains almost constant before and after cell volume change. The steady-state cell volume does not depend on water permeability. In addition, to ensure the stability of cell volume and ion concentrations, cells need to develop redundant mechanisms to maintain homeostasis, i.e., multiple ion channels or transporters are involved in the flux of the same ion species. These results provide insights for molecular mechanisms of cell volume regulation with additional implications for water-driven cell migration.

scholarly journals TACAN is an essential component of the mechanosensitive ion channel responsible for pain sensing

2018 ◽  
Author(s):  
L. Beaulieu-Laroche ◽  
M. Christin ◽  
AM Donoghue ◽  
F. Agosti ◽  
N. Yousefpour ◽  
...  
Keyword(s):  
Ion Channels ◽  
Heterologous Expression ◽  
Ion Channel ◽  
Behavioral Responses ◽  
Mechanical Stimuli ◽  
Thermal Pain ◽  
Fundamental Process ◽  
Mechanosensitive Ion Channel ◽  
Pain Stimuli ◽  
Essential Subunit

SummaryMechanotransduction, the conversion of mechanical stimuli into electrical signals, is a fundamental process underlying several physiological functions such as touch and pain sensing, hearing and proprioception. This process is carried out by specialized mechanosensitive ion channels whose identities have been discovered for most functions except pain sensing. Here we report the identification of TACAN (Tmem120A), an essential subunit of the mechanosensitive ion channel responsible for sensing mechanical pain. TACAN is expressed in a subset of nociceptors, and its heterologous expression increases mechanically-evoked currents in cell lines. Purification and reconstitution of TACAN in synthetic lipids generates a functional ion channel. Finally, knocking down TACAN decreases the mechanosensitivity of nociceptors and reduces behavioral responses to mechanical but not to thermal pain stimuli, without affecting the sensitivity to touch stimuli. We propose that TACAN is a pore-forming subunit of the mechanosensitive ion channel responsible for sensing mechanical pain.

Cave Canalem: How endogenous ion channels may interfere with heterologous expression in Xenopus oocytes

Methods ◽  
2010 ◽  
Vol 51 (1) ◽  
pp. 66-74 ◽  
Author(s):  
Jan Terhag ◽  
Nora A. Cavara ◽  
Michael Hollmann
Keyword(s):  
Ion Channels ◽  
Heterologous Expression ◽  
Xenopus Oocytes
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