Inhibition of the H1 voltage-gated proton channel compromises the viability of human polarized macrophages in a polarization- and ceramide-dependent manner.

The human voltage-gated proton channel (H1) provides an efficient proton extrusion pathway from the cytoplasm contributing to the intracellular pH regulation and the oxidative burst. Although its pharmacological inhibition was previously shown to induce cell death in various cell types, no such effects have been examined in polarized macrophages albeit H1 was suggested to play important roles in these cells. This study highlights that 5-chloro-2-guanidinobenzimidazole (ClGBI), the most widely applied H1 inhibitor, reduces the viability of human THP-1-derived polarized macrophages at biologically relevant doses with M1 macrophages being the most, and M2 cells the least sensitive to this compound.

Inhibition of K Channels Affects the Target Cell Killing Potential of CAR T Cells.

Ion channels of T cells (Kv1.3, KCa3.1, and CRAC) participate in the regulation of activation and effector functions via modulation of the Ca-dependent pathway.

Structure and functional studies of Avt1, a novel peptide from the sea anemone Aulactinia veratra.

Sea anemones are a rich source of peptide toxins spanning a diverse range of biological activities, typically targeting proteins such as ion channels, receptors and transporters. These peptide toxins and their analogues are usually highly stable and selective for their molecular targets, rendering them of interest as molecular tools, insecticides and therapeutics. Recent transcriptomic and proteomic analyses of the sea anemone Aulactinia veratra identified a novel 28-residue peptide, designated Avt1.

Novel insights into the modulation of the voltage-gated potassium channel K1.3 activation gating by membrane ceramides.

Membrane lipids extensively modulate the activation gating of voltage-gated potassium channels (K), however, much less is known about the mechanisms of ceramide and glucosylceramide actions including which structural element is the main intramolecular target and whether there is any contribution of indirect, membrane biophysics-related mechanisms to their actions. We used two-electrode voltage-clamp fluorometry capable of recording currents and fluorescence signals to simultaneously monitor movements of the pore domain (PD) and the voltage sensor domain (VSD) of the K1.3 ion channel after attaching an MTS-TAMRA fluorophore to a cysteine introduced into the extracellular S3-S4 loop of the VSD.

Intracellular acidity impedes KCa3.1 activation by Riluzole and SKA-31.

Background: The unique microenvironment in tumors inhibits the normal functioning of tumor-infiltrating lymphocytes, leading to immune evasion and cancer progression. Over-activation of KCa3.1 using positive modulators has been proposed to rescue the anti-tumor response.

KcsA-Kv1.x chimeras with complete ligand-binding sites provide improved predictivity for screening selective Kv1.x blockers.

Despite significant advances in the development of therapeutic interventions targeting autoimmune diseases and chronic inflammatory conditions, lack of effective treatment still poses a high unmet need. Modulating chronically activated T cells through the blockade of the Kv1.3 potassium channel is a promising therapeutic approach; however, developing selective Kv1.

A synthetic flavonoid derivate in the plasma membrane transforms the voltage-clamp fluorometry signal of CiHv1.

Voltage-clamp fluorometry (VCF) enables the study of voltage-sensitive proteins through fluorescent labeling accompanied by ionic current measurements for voltage-gated ion channels. The heterogeneity of the fluorescent signal represents a significant challenge in VCF. The VCF signal depends on where the cysteine mutation is incorporated, making it difficult to compare data among different mutations and different studies and standardize their interpretation.

Activity of Potassium Channels in CD8 T Lymphocytes: Diagnostic and Prognostic Biomarker in Ovarian Cancer?

CD8 T cells play a role in the suppression of tumor growth and immunotherapy. Ion channels control the Ca-dependent function of CD8 lymphocytes such as cytokine/granzyme production and tumor killing. Kv1.

Structure-function relationships in ShKT domain peptides: ShKT-Ts1 from the sea anemone Telmatactis stephensoni.

Diverse structural scaffolds have been described in peptides from sea anemones, with the ShKT domain being a common scaffold first identified in ShK toxin from Stichodactyla helianthus. ShK is a potent blocker of voltage-gated potassium channels (K 1.x), and an analog, ShK-186 (dalazatide), has completed Phase 1 clinical trials in plaque psoriasis.

Structural and functional characterisation of Tst2, a novel TRPV1 inhibitory peptide from the Australian sea anemone Telmatactis stephensoni.

Sea anemone venoms are complex mixtures of biologically active compounds, including disulfide-rich peptides, some of which have found applications as research tools, and others as therapeutic leads. Our recent transcriptomic and proteomic studies of the Australian sea anemone Telmatactis stephensoni identified a transcript for a peptide designated Tst2. Tst2 is a 38-residue peptide showing sequence similarity to peptide toxins known to interact with a range of ion channels (Na, TRPV1, K and Ca).

Of Seven New K Channel Inhibitor Peptides of , α-KTx 2.24 Has a Picomolar Affinity for Kv1.2.

Seven new peptides denominated CboK1 to CboK7 were isolated from the venom of the Mexican scorpion and their primary structures were determined. The molecular weights ranged between 3760.4 Da and 4357.

Effect of the Lipid Landscape on the Efficacy of Cell-Penetrating Peptides.

Every cell biological textbook teaches us that the main role of the plasma membrane is to separate cells from their neighborhood to allow for a controlled composition of the intracellular space. The mostly hydrophobic nature of the cell membrane presents an impenetrable barrier for most hydrophilic molecules larger than 1 kDa. On the other hand, cell-penetrating peptides (CPPs) are capable of traversing this barrier without compromising membrane integrity, and they can do so on their own or coupled to cargos.

5-Chloro-2-Guanidinobenzimidazole (ClGBI) Is a Non-Selective Inhibitor of the Human H1 Channel.

5-chloro-2-guanidinobenzimidazole (ClGBI), a small-molecule guanidine derivative, is a known effective inhibitor of the voltage-gated proton (H) channel (H1, ≈ 26 μM) and is widely used both in ion channel research and functional biological assays. However, a comprehensive study of its ion channel selectivity determined by electrophysiological methods has not been published yet. The lack of selectivity may lead to incorrect conclusions regarding the role of hHv1 in physiological or pathophysiological responses in vitro and in vivo.

Molecular rearrangements in S6 during slow inactivation in Shaker-IR potassium channels.

Voltage-gated K+ channels have distinct gates that regulate ion flux: the activation gate (A-gate) formed by the bundle crossing of the S6 transmembrane helices and the slow inactivation gate in the selectivity filter. These two gates are bidirectionally coupled. If coupling involves the rearrangement of the S6 transmembrane segment, then we predict state-dependent changes in the accessibility of S6 residues from the water-filled cavity of the channel with gating.

The Voltage-Gated Hv1 H Channel Is Expressed in Tumor-Infiltrating Myeloid-Derived Suppressor Cells.

Myeloid-derived suppressor cells (MDSCs) are key determinants of the immunosuppressive microenvironment in tumors. As ion channels play key roles in the physiology/pathophysiology of immune cells, we aimed at studying the ion channel repertoire in tumor-derived polymorphonuclear (PMN-MDSC) and monocytic (Mo-MDSC) MDSCs. Subcutaneous tumors in mice were induced by the Lewis lung carcinoma cell line (LLC).

Veklury® (remdesivir) formulations inhibit initial membrane-coupled events of SARS-CoV-2 infection due to their sulfobutylether-β-cyclodextrin content.

Background And Purpose: Despite its contradictory clinical performance, remdesivir (Veklury®) has a pivotal role in COVID-19 therapy. Possible contributions of the vehicle, sulfobutylether-β-cyclodextrin (SBECD) to Veklury® effects have been overlooked. The powder and solution formulations of Veklury® are treated equivalently despite their different vehicle content.

Characterization and Chemical Synthesis of Cm39 (α-KTx 4.8): A Scorpion Toxin That Inhibits Voltage-Gated K Channel K1.2 and Small- and Intermediate-Conductance Ca-Activated K Channels K2.2 and K3.1.

A novel peptide, Cm39, was identified in the venom of the scorpion . Its primary structure was determined. It consists of 37 amino acid residues with a MW of 3980.

Cyclodextrins: Only Pharmaceutical Excipients or Full-Fledged Drug Candidates?

Cyclodextrins, representing a versatile family of cyclic oligosaccharides, have extensive pharmaceutical applications due to their unique truncated cone-shaped structure with a hydrophilic outer surface and a hydrophobic cavity, which enables them to form non-covalent host-guest inclusion complexes in pharmaceutical formulations to enhance the solubility, stability and bioavailability of numerous drug molecules. As a result, cyclodextrins are mostly considered as inert carriers during their medical application, while their ability to interact not only with small molecules but also with lipids and proteins is largely neglected. By forming inclusion complexes with cholesterol, cyclodextrins deplete cholesterol from cellular membranes and thereby influence protein function indirectly through alterations in biophysical properties and lateral heterogeneity of bilayers.

Venom composition and pain-causing toxins of the Australian great carpenter bee Xylocopa aruana.

Most species of bee are capable of delivering a defensive sting which is often painful. A solitary lifestyle is the ancestral state of bees and most extant species are solitary, but information on bee venoms comes predominantly from studies on eusocial species. In this study we investigated the venom composition of the Australian great carpenter bee, Xylocopa aruana Ritsema, 1876.

Mapping the functional expression of auxiliary subunits of K1.1 in glioblastoma.

Glioblastoma (GBM) is the most aggressive glial tumor, where ion channels, including K1.1, are candidates for new therapeutic options. Since the auxiliary subunits linked to K1.

A Biodistribution Study of the Radiolabeled Kv1.3-Blocking Peptide DOTA-HsTX1[R14A] Demonstrates Brain Uptake in a Mouse Model of Neuroinflammation.

The voltage-gated potassium channel Kv1.3 regulates the pro-inflammatory function of microglia and is highly expressed in the post-mortem brains of individuals with Alzheimer's and Parkinson's diseases. HsTX1[R14A] is a selective and potent peptide inhibitor of the Kv1.

A Fluorescent Peptide Toxin for Selective Visualization of the Voltage-Gated Potassium Channel K1.3.

Upregulation of the voltage-gated potassium channel K1.3 is implicated in a range of autoimmune and neuroinflammatory diseases, including rheumatoid arthritis, psoriasis, multiple sclerosis, and type I diabetes. Understanding the expression, localization, and trafficking of K1.