Photochemical tools for remote control of ion channels in excitable cells

2005 ◽  
Vol 1 (7) ◽  
pp. 360-365 ◽  
Author(s):  
Richard H Kramer ◽  
James J Chambers ◽  
Dirk Trauner
2019 ◽  
Author(s):  
Danijela Gregurec ◽  
Alexander W. Senko ◽  
Andrey Chuvilin ◽  
Pooja Reddy ◽  
Ashwin Sankararaman ◽  
...  

In this work, we demonstrate the application of anisotropic magnetite nanodiscs (MNDs) as transducers of torque to mechanosensory cells under weak, slowly varying magnetic fields (MFs). These MNDs possess a ground state vortex configuration of magnetic spins which affords greater colloidal stability due to eliminated dipole-dipole interactions characteristic of isotropic magnetic particles of similar size. We first predict vortex magnetization using micromagnetic stimulations in sub-micron anisotropic magnetite particles and then use electron holography to experimentally investigate the magnetization of MNDs 98–226 nm in diameter. When MNDs are coupled to MFs, they transition between vortex and in-plane magnetization allowing for the exertion of the torque on the pN scale, which is sufficient to activate mechanosensitive ion channels in cell membranes.<br>


2021 ◽  
Vol 10 (6) ◽  
pp. 1239
Author(s):  
Alexandru Cojocaru ◽  
Emilia Burada ◽  
Adrian-Tudor Bălșeanu ◽  
Alexandru-Florian Deftu ◽  
Bogdan Cătălin ◽  
...  

As the average age and life expectancy increases, the incidence of both acute and chronic central nervous system (CNS) pathologies will increase. Understanding mechanisms underlying neuroinflammation as the common feature of any neurodegenerative pathology, we can exploit the pharmacology of cell specific ion channels to improve the outcome of many CNS diseases. As the main cellular player of neuroinflammation, microglia play a central role in this process. Although microglia are considered non-excitable cells, they express a variety of ion channels under both physiological and pathological conditions that seem to be involved in a plethora of cellular processes. Here, we discuss the impact of modulating microglia voltage-gated, potential transient receptor, chloride and proton channels on microglial proliferation, migration, and phagocytosis in neurodegenerative diseases.


2018 ◽  
Vol 150 (8) ◽  
pp. 1059-1061
Author(s):  
Jonathan T. Pierce

The role of ion channels in cell excitability was first revealed in a series of voltage clamp experiments by Hodgkin and Huxley in the 1950s. However, it was not until the 1970s that patch-clamp recording ushered in a revolution that allowed physiologists to witness how ion channels flicker open and closed at angstrom scale and with microsecond resolution. The unexpectedly tight seal made by the patch pipette in the whole-cell configuration later allowed molecular biologists to suck up the insides of identified cells to unveil their unique molecular contents. By refining these techniques, researchers have scrutinized the surface and contents of excitable cells in detail over the past few decades. However, these powerful approaches do not discern which molecules are responsible for the dynamic control of the genesis, abundance, and subcellular localization of ion channels. In this dark territory, teams of unknown and poorly understood molecules guide specific ion channels through translation, folding, and modification, and then they shuttle them toward and away from distinct membrane domains via different subcellular routes. A central challenge in understanding these processes is the likelihood that these diverse regulatory molecules may be specific to ion channel subtypes, cell types, and circumstance. In work described in this issue, Bai et al. (2018. J. Gen. Physiol. https://doi.org/10.1085/jgp.201812025) begin to shed light on the biogenesis of UNC-103, a K+ channel found in Caenorhabditis elegans.


Channels ◽  
2011 ◽  
Vol 5 (1) ◽  
pp. 79-88 ◽  
Author(s):  
Daria Bongiorno ◽  
Friderike Schuetz ◽  
Philip Poronnik ◽  
David J. Adams

2012 ◽  
Vol 17 (9) ◽  
pp. 1264-1272 ◽  
Author(s):  
Alison Haythornthwaite ◽  
Sonja Stoelzle ◽  
Alexander Hasler ◽  
Andrea Kiss ◽  
Johannes Mosbacher ◽  
...  

Neurons derived from human-induced pluripotent stem cells were characterized using manual and automated patch-clamp recordings. These cells expressed voltage-gated Na+ (Nav), Ca2+ (Cav), and K+ (Kv) channels as expected from excitable cells. The Nav current was TTX sensitive, IC50 = 12 ± 6 nM ( n = 5). About 50% of the Cav current was blocked by 10 µM of the L-type channel blocker nifedipine. Two populations of the Kv channel were present in different proportions: an inactivating (A-type) and a noninactivating type. The A-type current was sensitive to 4-AP and TEA (IC50 = 163 ± 93 µM; n = 3). Application of γ-aminobutyric acid (GABA) activated a current sensitive to the GABAA receptor antagonist bicuculline, IC50 = 632 ± 149 nM ( n = 5). In both devices, comparable action potentials were generated in the current clamp. With unbiased, automated patch clamp, about 40% of the cells expressed Nav currents, whereas visual guidance in manual patch clamp provided almost a 100% success rate of patching “excitable cells.” These results show high potential for pluripotent stem cell–derived neurons as a useful model for drug discovery, in combination with automated patch-clamp recordings for high-throughput and high-quality drug assessments at human neuronal ion channels in their correct cellular background.


2018 ◽  
Author(s):  
Lige Tonggu ◽  
Liguo Wang

ABSTRACTVoltage-gated and ligand-modulated ion channels play critical roles in excitable cells. To understand the interplay among voltage-sensing, ligand-binding and channel opening, the structures of ion channels in various functional states need to be determined. Here, the “random spherically constrained” (RSC) single-particle cryo-EM method was employed to study the human large conductance voltage- and calcium-activated potassium (hBK or hSlo1) channels reconstituted into liposomes. The hBK structure has been determined at 3.5 Å resolution in the absence of Ca2+. Instead of the common four-fold symmetry observed in ligand-modulated ion channels, a two-fold symmetry was observed in hBK. Two opposing subunits in the Ca2+ sensing gating ring rotate around the center of each subunit, which results in the movement of the assembly and flexible interfaces and Ca2+ binding sites. Despite the significant movement, the local conformation of the assembly interfaces and Ca2+ binding sites remains the same among the four subunits.


Circulation ◽  
2007 ◽  
Vol 116 (suppl_16) ◽  
Author(s):  
John S Lowe ◽  
Oleg Palygin ◽  
Patrick Wright ◽  
Erwin Shibata ◽  
Peter Mohler

Membrane localization of ion channels is very important for normal function in excitable cells. In heart, voltage-gated Na + channels are necessary for the rapid upstroke of the cardiomyocyte action potential, and variants in SCN5A (encodes Na v 1.5) are associated with fatal arrhythmias. We have identified ankyrin family proteins as critical components for normal ion channel and transporter targeting in cardiomyocytes. Humans with ANK2 (encodes ankyrin-B) loss of function variants display abnormal cardiac phenotypes and risk for sudden cardiac death. Mice that lack ankyrin-B expression display a similar phenotype. Our most recent results demonstrate that a second ankyrin gene product, ankyrin-G (encoded by ANK 3) is critical for targeting Na v 1.5 to specific cardiomyocyte membrane domains. We assessed the hypothesis that Na v 1.5 membrane expression and localization is controlled by an ankyrin-G-dependent pathway and disruption of ankyrin-G/Na v 1.5 interactions lead to human cardiac disease in this study. We used a combination of techniques including biochemistry, confocal microscopy, lentiviral expression, and electrophysiology to evaluate the functional relationship between ankyrin-G and Na v 1.5. We defined the structural elements on ankyrin-G and Na v 1.5 for their interaction using site-directed mutagenesis and in vitro binding assays. Lentiviral expression of shRNA targeted to rat 190 kD ankyrin-G effectively reduced the expression of ankyrin-G with a concomitant reduction of Na v 1.5 in immunofluorescence and immunoblot assays. Further-more, primary cardiomyocytes with reduced ankyrin-G expression have a significant reduction in Na + current density with no evident biophysical effects on Ca 2+ current or inactivation-gating of Na v 1.5 These results confirm the importance of ankyrin polypeptides for normal cardiac function and shed new light on the importance of intracellular trafficking pathways for the delivery and stability of critical ion channels and transporters in excitable cells.


Author(s):  
Elena A. Morachevskaya ◽  
Anastasia V. Sudarikova

Ion channels in plasma membrane play a principal role in different physiological processes, including cell volume regulation, signal transduction and modulation of membrane potential in living cells. Actin-based cytoskeleton, which exists in a dynamic balance between monomeric and polymeric forms (globular and fibrillar actin), can be directly or indirectly involved in various cellular responses including modulation of ion channel activity. In this mini-review, we present an overview of the role of submembranous actin dynamics in the regulation of ion channels in excitable and non-excitable cells. Special attention is focused on the important data about the involvement of actin assembly/disassembly and some actin-binding proteins in the control of the Epithelial Na+ Channel (ENaC) and mechanosensitive Piezo channels whose integral activity has potential impact on membrane transport and multiple coupled cellular reactions. Growing evidence suggests that actin elements of the cytoskeleton can represent a "converging point" of various signaling pathways modulating the activity of ion transport proteins in cell membranes.


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