New Roles for Old Holes: Ion Channel Function in Aquaporin-1

Physiology ◽  
2002 ◽  
Vol 17 (2) ◽  
pp. 68-72 ◽  
Author(s):  
Andrea J. Yool ◽  
Alan M. Weinstein
Keyword(s):  
Ion Channels ◽  
Ion Channel ◽  
Functional Properties ◽  
Major Intrinsic Protein ◽  
Aquaporin 1 ◽  
Intrinsic Protein ◽  
Channel Proteins ◽  
Channel Function ◽  
Transmembrane Channel ◽  
Structural And Functional Properties

Mammalian aquaporins are part of the diverse major intrinsic protein family of water and solute channels. Intriguing links exist in structural and functional properties between aquaporins and ion channels. A novel role for aquaporin-1 as a gated ion channel reshapes our current views of this ancient family of transmembrane channel proteins.

Ion channels and disease

2020 ◽  
pp. 246-255
Author(s):  
Frances Ashcroft ◽  
Paolo Tammaro
Keyword(s):  
Ion Channels ◽  
Ion Channel ◽  
Single Channel ◽  
Cell Types ◽  
Channel Structure ◽  
Channel Proteins ◽  
Channel Function ◽  
Ion Channel Proteins ◽  
Single Channel Currents ◽  
Channel Currents

Ion channels are membrane proteins that act as gated pathways for the movement of ions across cell membranes. They are found in both surface and intracellular membranes and play essential roles in the physiology of all cell types. An ever-increasing number of human diseases are now known to be caused by defects in ion channel function. To understand how ion channel defects give rise to disease, it is helpful to understand how the ion channel proteins work. This chapter therefore considers what is known of ion channel structure, explains the properties of the single ion channel, and shows how single-channel currents give rise to action potentials and synaptic potentials.

WHAT CAUSES ION CHANNEL PROTEINS TO FLUCTUATE OPEN AND CLOSED?

1996 ◽  
Vol 07 (04) ◽  
pp. 321-331 ◽  
Author(s):  
LARRY S. LIEBOVITCH ◽  
ANGELO T. TODOROV
Keyword(s):  
Ion Channels ◽  
Patch Clamp ◽  
Ion Channel ◽  
Patch Clamp Technique ◽  
Sodium Potassium ◽  
Random Event ◽  
Channel Protein ◽  
Channel Proteins ◽  
Ion Channel Proteins ◽  
Open States

Ion channels in the cell membrane spontaneously switch from states that are closed to the flow of ions such as sodium, potassium, and chloride to states that are open to the flow of these ions. The durations of times that an individual ion channel protein spends in the closed and open states can be measured by the patch clamp technique. We explore two basic issues about the molecular properties of ion channels: 1) If the switching between the closed and open state is an inherently random event, what does the patch clamp data tell us about the structure or motions in the ion channel protein? 2) Is this switching random?

scholarly journals Role of lysophosphatidic acid in ion channel function and disease

2018 ◽  
Vol 120 (3) ◽  
pp. 1198-1211 ◽  
Author(s):  
Ileana Hernández-Araiza ◽  
Sara L. Morales-Lázaro ◽  
Jesús Aldair Canul-Sánchez ◽  
León D. Islas ◽  
Tamara Rosenbaum
Keyword(s):  
Ion Channels ◽  
Ion Channel ◽  
Lysophosphatidic Acid ◽  
Protein Interactions ◽  
Molecular Mechanisms ◽  
Transient Receptor Potential ◽  
Receptor Potential ◽  
Channel Function ◽  
Transient Receptor ◽  
Lipid Protein Interactions

Lysophosphatidic acid (LPA) is a bioactive phospholipid that exhibits a wide array of functions that include regulation of protein synthesis and adequate development of organisms. LPA is present in the membranes of cells and in the serum of several mammals and has also been shown to participate importantly in pathophysiological conditions. For several decades it was known that LPA produces some of its effects in cells through its interaction with specific G protein-coupled receptors, which in turn are responsible for signaling pathways that regulate cellular function. Among the target proteins for LPA receptors are ion channels that modulate diverse aspects of the physiology of cells and organs where they are expressed. However, recent studies have begun to unveil direct effects of LPA on ion channels, highlighting this phospholipid as a direct agonist and adding to the knowledge of the field of lipid-protein interactions. Moreover, the roles of LPA in pathophysiological conditions associated with the function of some ion channels have also begun to be clarified, and molecular mechanisms have been identified. This review focuses on the effects of LPA on ion channel function under normal and pathological conditions and highlights our present knowledge of the mechanisms by which it regulates the function and expression of N- and T-type Ca++ channels; M-type K+ channel and inward rectifier K+ channel subunit 2.1; transient receptor potential (TRP) melastatin 2, TRP vanilloid 1, and TRP ankyrin 1 channels; and TWIK-related K+ channel 1 (TREK-1), TREK-2, TWIK-related spinal cord K+ channel (TRESK), and TWIK-related arachidonic acid-stimulated K+ channel (TRAAK).

scholarly journals Fluorescence Microscopy of Piezo1 in Droplet Hydrogel Bilayers

2018 ◽  
Author(s):  
Oskar B. Jaggers ◽  
Pietro Ridone ◽  
Boris Martinac ◽  
Matthew A. B. Baker
Keyword(s):  
Ion Channels ◽  
Ion Channel ◽  
Simultaneous Recording ◽  
Mechanical Stimuli ◽  
Channel Activity ◽  
Channel Proteins ◽  
Mechanosensitive Ion Channel ◽  
Lymphatic Dysplasia ◽  
Hydrogel Bilayer

AbstractMechanosensitive ion channels are membrane gated pores which are activated by mechanical stimuli. The focus of this study is on Piezo1, a newly discovered, large, mammalian, mechanosensitive ion channel, which has been linked to diseases such as dehydrated hereditary stomatocytosis (Xerocytosis) and lymphatic dysplasia. Here we utilize an established in-vitro artificial bilayer system to interrogate single Piezo1 channel activity. The droplet-hydrogel bilayer (DHB) system uniquely allows the simultaneous recording of electrical activity and fluorescence imaging of labelled protein. We successfully reconstituted fluorescently labelled Piezo1 ion channels in DHBs and verified activity using electrophysiology in the same system. We demonstrate successful insertion and activation of hPiezo1-GFP in bilayers of varying composition. Furthermore, we compare the Piezo1 bilayer reconstitution with measurements of insertion and activation of KcsA channels to reproduce the channel conductances reported in the literature. Together, our results showcase the use of DHBs for future experiments allowing simultaneous measurements of ion channel gating while visualising the channel proteins using fluorescence.

scholarly journals Ion channel regulation by protein S-acylation

2014 ◽  
Vol 143 (6) ◽  
pp. 659-678 ◽  
Author(s):  
Michael J. Shipston
Keyword(s):  
Life Cycle ◽  
Ion Channels ◽  
Ion Channel ◽  
Physiological Function ◽  
Protein S ◽  
Cysteine Residues ◽  
Acid Modification ◽  
Ion Channel Regulation ◽  
Channel Function ◽  
Voltage Gated Ion Channels

Protein S-acylation, the reversible covalent fatty-acid modification of cysteine residues, has emerged as a dynamic posttranslational modification (PTM) that controls the diversity, life cycle, and physiological function of numerous ligand- and voltage-gated ion channels. S-acylation is enzymatically mediated by a diverse family of acyltransferases (zDHHCs) and is reversed by acylthioesterases. However, for most ion channels, the dynamics and subcellular localization at which S-acylation and deacylation cycles occur are not known. S-acylation can control the two fundamental determinants of ion channel function: (1) the number of channels resident in a membrane and (2) the activity of the channel at the membrane. It controls the former by regulating channel trafficking and the latter by controlling channel kinetics and modulation by other PTMs. Ion channel function may be modulated by S-acylation of both pore-forming and regulatory subunits as well as through control of adapter, signaling, and scaffolding proteins in ion channel complexes. Importantly, cross-talk of S-acylation with other PTMs of both cysteine residues by themselves and neighboring sites of phosphorylation is an emerging concept in the control of ion channel physiology. In this review, I discuss the fundamentals of protein S-acylation and the tools available to investigate ion channel S-acylation. The mechanisms and role of S-acylation in controlling diverse stages of the ion channel life cycle and its effect on ion channel function are highlighted. Finally, I discuss future goals and challenges for the field to understand both the mechanistic basis for S-acylation control of ion channels and the functional consequence and implications for understanding the physiological function of ion channel S-acylation in health and disease.

scholarly journals Precise control of ion channel and gap junction expression is required for patterning of the regenerating axolotl limb

2020 ◽  
Vol 64 (10-11-12) ◽  
pp. 485-494
Author(s):  
Konstantinos Sousounis ◽  
Burcu Erdogan ◽  
Michael Levin ◽  
Jessica L. Whited
Keyword(s):  
Ion Channels ◽  
Gap Junctions ◽  
Ion Channel ◽  
Gap Junction ◽  
Regulation Of Gene Expression ◽  
Transcriptional Networks ◽  
Channel Proteins ◽  
Junction Protein ◽  
Ion Channel Proteins ◽  
Voltage Gradients

Axolotls and other salamanders have the capacity to regenerate lost tissue after an amputation or injury. Growth and morphogenesis are coordinated within cell groups in many contexts by the interplay of transcriptional networks and biophysical properties such as ion flows and voltage gradients. It is not, however, known whether regulators of a cell’s ionic state are involved in limb patterning at later stages of regeneration. Here we manipulated expression and activities of ion channels and gap junctions in vivo, in axolotl limb blastema cells. Limb amputations followed by retroviral infections were performed to drive expression of a human gap junction protein Connexin 26 (Cx26), potassium (Kir2.1-Y242F and Kv1.5) and sodium (NeoNav1.5) ion channel proteins along with EGFP control. Skeletal preparation revealed that overexpressing Cx26 caused syndactyly, while overexpression of ion channel proteins resulted in digit loss and structural abnormalities compared to EGFP expressing control limbs. Additionally, we showed that exposing limbs to the gap junction inhibitor lindane during the regeneration process caused digit loss. Our data reveal that manipulating native ion channel and gap junction function in blastema cells results in patterning defects involving the number and structure of the regenerated digits. Gap junctions and ion channels have been shown to mediate ion flows that control the endogenous voltage gradients which are tightly associated with the regulation of gene expression, cell cycle progression, migration, and other cellular behaviors. Therefore, we postulate that mis-expression of these channels may have disturbed this regulation causing uncoordinated cell behavior which results in morphological defects.

scholarly journals Ion Channel Function of Aquaporin-1 Natively Expressed in Choroid Plexus

2006 ◽  
Vol 26 (30) ◽  
pp. 7811-7819 ◽  
Author(s):  
D. Boassa ◽  
W. D. Stamer ◽  
A. J. Yool
Keyword(s):  
Ion Channel ◽  
Choroid Plexus ◽  
Aquaporin 1 ◽  
Channel Function

Regulation of ion channel structure and function by reactive oxygen-nitrogen species

2003 ◽  
Vol 285 (6) ◽  
pp. L1184-L1189 ◽  
Author(s):  
Sadis Matalon ◽  
Karin M. Hardiman ◽  
Lucky Jain ◽  
Douglas C. Eaton ◽  
Michael Kotlikoff ◽  
...  
Keyword(s):  
Gene Expression ◽  
Ion Channels ◽  
Ion Channel ◽  
Posttranslational Modifications ◽  
Regulation Of Gene Expression ◽  
Reactive Oxygen ◽  
Cellular Level ◽  
Channel Structure ◽  
Nitrogen Species ◽  
Channel Proteins

Ion channels subserve diverse cellular functions. Reactive oxygen and nitrogen species modulate ion channel function by a number of mechanisms including 1) transcriptional regulation of gene expression, 2) posttranslational modifications of channel proteins, i.e. nitrosylation, nitration, and oxidation of key amino acid residues, 3) by altering the gain in other signaling pathways that may in turn lead to changes in channel activity or channel gene expression, and 4) by modulating trafficking or turnover of channel proteins, as typified by oxygen radical activation of NF-kB, with subsequent changes in proteasomal degradation of channel degradation. Regardless of the mechanism, as was discussed in a symposium at the 2003 Experimental Biology Meeting in San Diego, CA, changes in the cellular level of reactive oxygen and nitrogen species can have profound effects on the activity of ion channels and cellular function.

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