Electronic Polarizability Tunes the Function of the Human Bestrophin 1 Cl Channel.

Mechanisms of anion permeation within ion channels and nanopores remain poorly understood. Recent cryo-electron microscopy structures of the human bestrophin 1 Cl channel (hBest1) provide an opportunity to evaluate ion interactions predicted by molecular dynamics (MD) simulations against experimental observations. Here, we implement the fully polarizable force field AMOEBA in MD simulations on different conformations of hBest1.

Structures of TASK-1 and TASK-3 K2P channels provide insight into their gating and dysfunction in disease.

TASK-1 and TASK-3 are pH-sensitive two-pore domain (K2P/KCNK) K channels. Their functional roles make them promising targets for treatment of multiple disorders including sleep apnea, pain, and atrial fibrillation. Mutations in these channels are also associated with neurodevelopmental and hypertensive disorders.

Extracellular modulation of TREK-2 activity with nanobodies provides insight into the mechanisms of K2P channel regulation.

Potassium channels of the Two-Pore Domain (K2P) subfamily, KCNK1-KCNK18, play crucial roles in controlling the electrical activity of many different cell types and represent attractive therapeutic targets. However, the identification of highly selective small molecule drugs against these channels has been challenging due to the high degree of structural and functional conservation that exists not only between K2P channels, but across the whole K channel superfamily. To address the issue of selectivity, here we generate camelid antibody fragments (nanobodies) against the TREK-2 (KCNK10) K2P K channel and identify selective binders including several that directly modulate channel activity.

Temporal changes in toe-brachial index results in haemodialysis patients.

Introduction: Toe brachial index (TBI), the ratio of toe pressure to systolic blood pressure (SBP), helps predict peripheral arterial disease. In patients with kidney failure this may be performed during haemodialysis for convenience. Until recently there has been little evaluation of the impact of haemodialysis in limb and systemic perfusion on these values.

ATI-1777, a Topical Jak1/3 Inhibitor, May Benefit Atopic Dermatitis without Systemic Drug Exposure: Results from Preclinical Development and Phase 2a Randomized Control Study ATI-1777-AD-201.

Introduction: Atopic dermatitis, a chronic, pruritic skin disease, affects 10-30% of children and up to 14% of adults in developed countries. ATI-1777, a potent and selective Jak1/3 inhibitor, was designed with multiple sites of metabolism to deliver local efficacy in the skin and limit systemic exposure. In preclinical studies, ATI-1777 selectively inhibited Jak1/3 with limited systemic exposure and without any adverse effects.

Electronic Polarizability Tunes the Function of the Human Bestrophin 1 Cl Channel.

Mechanisms of anion permeation within ion channels and nanopores remain poorly understood. Recent cryo-electron microscopy structures of the human bestrophin 1 Cl- channel (hBest1) provide an opportunity to evaluate ion interactions predicted by molecular dynamics (MD) simulations against experimental observations. Here, we implement the fully polarizable forcefield AMOEBA in MD simulations on different conformations of hBest1.

Transcending Markov: non-Markovian rate processes of thermosensitive TRP ion channels.

The Markov state model (MSM) is a popular theoretical tool for describing the hierarchy of time scales involved in the function of many proteins especially ion channel gating. An MSM is a particular case of the general non-Markovian model, where the rate of transition from one state to another does not depend on the history of state occupancy within the system, i.e.

Correction: Limitations of non-polarizable force fields in describing anion binding poses in non-polar synthetic hosts.

Correction for 'Limitations of non-polarizable force fields in describing anion binding poses in non-polar synthetic hosts' by David Seiferth , , 2023, , 17596-17608, https://doi.org/10.1039/D3CP00479A.

Optical coherence tomography-based design for a real-time motion corrected scanning microscope.

While two-photon fluorescence microscopy is a powerful platform for the study of functional dynamics in living cells and tissues, the bulk motion inherent to these applications causes distortions. We have designed a motion tracking module based on spectral domain optical coherence tomography which compliments a laser scanning two-photon microscope with real-time corrective feedback. The module can be added to fluorescent imaging microscopes using a single dichroic and without additional contrast agents.

Limitations of non-polarizable force fields in describing anion binding poses in non-polar synthetic hosts.

Transmembrane anion transport by synthetic ionophores has received increasing interest not only because of its relevance for understanding endogenous anion transport, but also because of potential implications for therapeutic routes in disease states where chloride transport is impaired. Computational studies can shed light on the binding recognition process and can deepen our mechanistic understanding of them. However, the ability of molecular mechanics methods to properly capture solvation and binding properties of anions is known to be challenging.

Introduction to the shared near infrared spectroscopy format.

Significance: Functional near-infrared spectroscopy (fNIRS) is a popular neuroimaging technique with proliferating hardware platforms, analysis approaches, and software tools. There has not been a standardized file format for storing fNIRS data, which has hindered the sharing of data as well as the adoption and development of software tools.

Aim: We endeavored to design a file format to facilitate the analysis and sharing of fNIRS data that is flexible enough to meet the community's needs and sufficiently defined to be implemented consistently across various hardware and software platforms.

When is a hydrophobic gate not a hydrophobic gate?

The flux of ions through a channel is most commonly regulated by changes that result in steric occlusion of its pore. However, ion permeation can also be prevented by formation of a desolvation barrier created by hydrophobic residues that line the pore. As a result of relatively minor structural changes, confined hydrophobic regions in channels may undergo transitions between wet and dry states to gate the pore closed without physical constriction of the permeation pathway.

Gain-of-function mutations in KCNK3 cause a developmental disorder with sleep apnea.

Sleep apnea is a common disorder that represents a global public health burden. KCNK3 encodes TASK-1, a K channel implicated in the control of breathing, but its link with sleep apnea remains poorly understood. Here we describe a new developmental disorder with associated sleep apnea (developmental delay with sleep apnea, or DDSA) caused by rare de novo gain-of-function mutations in KCNK3.

Structural basis for proton coupled cystine transport by cystinosin.

Amino acid transporters play a key role controlling the flow of nutrients across the lysosomal membrane and regulating metabolism in the cell. Mutations in the gene encoding the transporter cystinosin result in cystinosis, an autosomal recessive metabolic disorder characterised by the accumulation of cystine crystals in the lysosome. Cystinosin is a member of the PQ-loop family of solute carrier (SLC) transporters and uses the proton gradient to drive cystine export into the cytoplasm.

Transition between conformational states of the TREK-1 K2P channel promoted by interaction with PIP.

Members of the TREK family of two-pore domain potassium channels are highly sensitive to regulation by membrane lipids, including phosphatidylinositol-4,5-bisphosphate (PIP). Previous studies have demonstrated that PIP increases TREK-1 channel activity; however, the mechanistic understanding of the conformational transitions induced by PIP remain unclear. Here, we used coarse-grained molecular dynamics and atomistic molecular dynamics simulations to model the PIP-binding site on both the up and down state conformations of TREK-1.

Influence of effective polarization on ion and water interactions within a biomimetic nanopore.

Interactions between ions and water at hydrophobic interfaces within ion channels and nanopores are suggested to play a key role in the movement of ions across biological membranes. Previous molecular-dynamics simulations have shown that anion affinity for aqueous/hydrophobic interfaces can be markedly influenced by including polarization effects through an electronic continuum correction. Here, we designed a model biomimetic nanopore to imitate the polar pore openings and hydrophobic gating regions found in pentameric ligand-gated ion channels.

Water Nanoconfined in a Hydrophobic Pore: Molecular Dynamics Simulations of Transmembrane Protein 175 and the Influence of Water Models.

Water molecules within biological ion channels are in a nanoconfined environment and therefore exhibit behaviors which differ from that of bulk water. Here, we investigate the phenomenon of hydrophobic gating, the process by which a nanopore may spontaneously dewet to form a "vapor lock" if the pore is sufficiently hydrophobic and/or narrow. This occurs without steric occlusion of the pore.

Effects of ionic strength on gating and permeation of TREK-2 K2P channels.

In addition to the classical voltage-dependent behavior mediated by the voltage-sensing-domains (VSD) of ion channels, a growing number of voltage-dependent gating behaviors are being described in channels that lack canonical VSDs. A common thread in their mechanism of action is the contribution of the permeating ion to this voltage sensing process. The polymodal K2P K+ channel, TREK2 responds to membrane voltage through a gating process mediated by the interaction of K+ with its selectivity filter.

Ion channels as convergence points in the pathology of pulmonary arterial hypertension.

Pulmonary arterial hypertension (PAH) is a fatal disease of the cardiopulmonary system that lacks curative treatments. The main pathological event in PAH is elevated vascular resistance in the pulmonary circulation, caused by abnormal vasoconstriction and vascular remodelling. Ion channels are key determinants of vascular smooth muscle tone and homeostasis, and four PAH channelopathies (KCNK3, ABCC8, KCNA5, TRPC6) have been identified so far.

Biallelic Variants Associated with Intellectual Disability and Neurodevelopmental Disorders Alter TRESK Channel Activity.

The TWIK-related spinal cord potassium channel (TRESK) is encoded by , and variants in this gene have previously been associated with susceptibility to familial migraine with aura (MIM #613656). A single amino acid substitution in the same protein, p.Trp101Arg, has also been associated with intellectual disability (ID), opening the possibility that variants in this gene might be involved in different disorders.

Norfluoxetine inhibits TREK-2 K2P channels by multiple mechanisms including state-independent effects on the selectivity filter gate.

The TREK subfamily of two-pore domain K+ (K2P) channels are inhibited by fluoxetine and its metabolite, norfluoxetine (NFx). Although not the principal targets of this antidepressant, TREK channel inhibition by NFx has provided important insights into the conformational changes associated with channel gating and highlighted the role of the selectivity filter in this process. However, despite the availability of TREK-2 crystal structures with NFx bound, the precise mechanisms underlying NFx inhibition remain elusive.

The Gene Variant Hastens Diabetes Progression by Impairing Glucose-Induced Insulin Secretion.

The ATP-sensitive K (K) channel controls blood glucose levels by coupling glucose metabolism to insulin secretion in pancreatic β-cells. E23K, a common polymorphism in the pore-forming K channel subunit () gene, has been linked to increased risk of type 2 diabetes. Understanding the risk-allele-specific pathogenesis has the potential to improve personalized diabetes treatment, but the underlying mechanism has remained elusive.

Molecular Simulations of Hydrophobic Gating of Pentameric Ligand Gated Ion Channels: Insights into Water and Ions.

Ion channels are proteins which form gated nanopores in biological membranes. Many channels exhibit hydrophobic gating, whereby functional closure of a pore occurs by local dewetting. The pentameric ligand gated ion channels (pLGICs) provide a biologically important example of hydrophobic gating.