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1.
Cells ; 11(6)2022 03 08.
Article in English | MEDLINE | ID: covidwho-1760407

ABSTRACT

A distinct set of channels and transporters regulates the ion fluxes across the lysosomal membrane. Malfunctioning of these transport proteins and the resulting ionic imbalance is involved in various human diseases, such as lysosomal storage disorders, cancer, as well as metabolic and neurodegenerative diseases. As a consequence, these proteins have stimulated strong interest for their suitability as possible drug targets. A detailed functional characterization of many lysosomal channels and transporters is lacking, mainly due to technical difficulties in applying the standard patch-clamp technique to these small intracellular compartments. In this review, we focus on current methods used to unravel the functional properties of lysosomal ion channels and transporters, stressing their advantages and disadvantages and evaluating their fields of applicability.


Subject(s)
Ion Channels , Lysosomal Storage Diseases , Humans , Intracellular Membranes/metabolism , Ion Channels/metabolism , Ions/metabolism , Lysosomal Storage Diseases/metabolism , Lysosomes/metabolism , Patch-Clamp Techniques
2.
Cells ; 11(1)2021 12 24.
Article in English | MEDLINE | ID: covidwho-1580995

ABSTRACT

The lamellar body (LB) of the alveolar type II (ATII) cell is a lysosome-related organelle (LRO) that contains surfactant, a complex mix of mainly lipids and specific surfactant proteins. The major function of surfactant in the lung is the reduction of surface tension and stabilization of alveoli during respiration. Its lack or deficiency may cause various forms of respiratory distress syndrome (RDS). Surfactant is also part of the innate immune system in the lung, defending the organism against air-borne pathogens. The limiting (organelle) membrane that encloses the LB contains various transporters that are in part responsible for translocating lipids and other organic material into the LB. On the other hand, this membrane contains ion transporters and channels that maintain a specific internal ion composition including the acidic pH of about 5. Furthermore, P2X4 receptors, ligand gated ion channels of the danger signal ATP, are expressed in the limiting LB membrane. They play a role in boosting surfactant secretion and fluid clearance. In this review, we discuss the functions of these transporting pathways of the LB, including possible roles in disease and as therapeutic targets, including viral infections such as SARS-CoV-2.


Subject(s)
COVID-19/metabolism , Ion Channels/metabolism , Lung/metabolism , Membrane Transport Proteins/metabolism , Pulmonary Surfactants/metabolism , COVID-19/virology , Humans , Lung/virology , Organelles/metabolism , Organelles/virology , Pulmonary Alveoli/metabolism , Pulmonary Alveoli/virology , SARS-CoV-2/physiology
3.
Front Immunol ; 12: 767319, 2021.
Article in English | MEDLINE | ID: covidwho-1538373

ABSTRACT

The importance of innate immune cells to sense and respond to their physical environment is becoming increasingly recognized. Innate immune cells (e.g. macrophages and neutrophils) are able to receive mechanical signals through several mechanisms. In this review, we discuss the role of mechanosensitive ion channels, such as Piezo1 and transient receptor potential vanilloid 4 (TRPV4), and cell adhesion molecules, such as integrins, selectins, and cadherins in biology and human disease. Furthermore, we explain that these mechanical stimuli activate intracellular signaling pathways, such as MAPK (p38, JNK), YAP/TAZ, EDN1, NF-kB, and HIF-1α, to induce protein conformation changes and modulate gene expression to drive cellular function. Understanding the mechanisms by which immune cells interpret mechanosensitive information presents potential targets to treat human disease. Important areas of future study in this area include autoimmune, allergic, infectious, and malignant conditions.


Subject(s)
Immunity, Innate/immunology , Macrophages/immunology , Mechanotransduction, Cellular/immunology , Neutrophils/immunology , Signal Transduction/immunology , Animals , Cytokines/immunology , Cytokines/metabolism , Humans , Ion Channels/immunology , Ion Channels/metabolism , Macrophages/metabolism , Neutrophils/metabolism , TRPV Cation Channels/immunology , TRPV Cation Channels/metabolism
4.
J Cell Physiol ; 237(2): 1521-1531, 2022 02.
Article in English | MEDLINE | ID: covidwho-1490820

ABSTRACT

Mechanical forces can modulate the immune response, mostly described as promoting the activation of immune cells, but the role and mechanism of pathological levels of mechanical stress in lymphocyte activation have not been focused on before. By an ex vivo experimental approach, we observed that mechanical stressing of murine spleen lymphocytes with 50 mmHg for 3 h induced the nuclear localization of NFAT1, increased C-Jun, and increased the expression of early activation marker CD69 in resting CD8+ cells. Interestingly, 50 mmHg mechanical stressing induced the nuclear localization of NFAT1; but conversely decreased C-Jun and inhibited the expression of CD69 in lymphocytes under lipopolysaccharide or phorbol 12-myristate 13-acetate/ionomycin stimulation. Additionally, we observed similar changes trends when comparing RNA-seq data of hypertensive and normotensive COVID-19 patients. Our results indicate a biphasic effect of mechanical stress on lymphocyte activation, which provides insight into the variety of immune responses in pathologies involving elevated mechanical stress.


Subject(s)
Lymphocyte Activation/immunology , Stress, Mechanical , Animals , Antigens, CD/metabolism , Antigens, Differentiation, T-Lymphocyte/metabolism , Biomarkers/metabolism , CD8-Positive T-Lymphocytes/drug effects , CD8-Positive T-Lymphocytes/immunology , COVID-19/complications , Cell Nucleus/drug effects , Cell Nucleus/metabolism , Comorbidity , Gene Expression Regulation/drug effects , Humans , Hypertension/complications , Hypoxia-Inducible Factor 1, alpha Subunit/metabolism , Ion Channels/metabolism , Lectins, C-Type/metabolism , Lipopolysaccharides/pharmacology , Lymphocyte Activation/drug effects , Lymphocyte Activation/genetics , Male , Mice, Inbred C57BL , NFATC Transcription Factors/metabolism , Protein Transport/drug effects , Proto-Oncogene Proteins c-jun/metabolism , Signal Transduction/drug effects , Tetradecanoylphorbol Acetate/pharmacology
5.
Viruses ; 13(11)2021 10 27.
Article in English | MEDLINE | ID: covidwho-1488757

ABSTRACT

The current COVID-19 pandemic has highlighted the need for the research community to develop a better understanding of viruses, in particular their modes of infection and replicative lifecycles, to aid in the development of novel vaccines and much needed anti-viral therapeutics. Several viruses express proteins capable of forming pores in host cellular membranes, termed "Viroporins". They are a family of small hydrophobic proteins, with at least one amphipathic domain, which characteristically form oligomeric structures with central hydrophilic domains. Consequently, they can facilitate the transport of ions through the hydrophilic core. Viroporins localise to host membranes such as the endoplasmic reticulum and regulate ion homeostasis creating a favourable environment for viral infection. Viroporins also contribute to viral immune evasion via several mechanisms. Given that viroporins are often essential for virion assembly and egress, and as their structural features tend to be evolutionarily conserved, they are attractive targets for anti-viral therapeutics. This review discusses the current knowledge of several viroporins, namely Influenza A virus (IAV) M2, Human Immunodeficiency Virus (HIV)-1 Viral protein U (Vpu), Hepatitis C Virus (HCV) p7, Human Papillomavirus (HPV)-16 E5, Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV) Open Reading Frame (ORF)3a and Polyomavirus agnoprotein. We highlight the intricate but broad immunomodulatory effects of these viroporins and discuss the current antiviral therapies that target them; continually highlighting the need for future investigations to focus on novel therapeutics in the treatment of existing and future emergent viruses.


Subject(s)
Immunomodulation , Ion Channels/metabolism , Viroporin Proteins/metabolism , Virus Diseases/drug therapy , Viruses/metabolism , Antiviral Agents/pharmacology , Antiviral Agents/therapeutic use , Autophagy , Host-Pathogen Interactions , Human Immunodeficiency Virus Proteins/chemistry , Human Immunodeficiency Virus Proteins/metabolism , Immune Evasion , Inflammasomes/immunology , Oncogene Proteins, Viral/chemistry , Oncogene Proteins, Viral/metabolism , Viral Matrix Proteins/chemistry , Viral Matrix Proteins/metabolism , Viral Proteins/chemistry , Viral Proteins/metabolism , Viral Regulatory and Accessory Proteins/chemistry , Viral Regulatory and Accessory Proteins/metabolism , Viral Structural Proteins/chemistry , Viral Structural Proteins/metabolism , Viroporin Proteins/chemistry , Virus Diseases/immunology , Virus Diseases/virology , Viruses/drug effects , Viruses/immunology , Viruses/pathogenicity
6.
PLoS Pathog ; 17(5): e1009519, 2021 05.
Article in English | MEDLINE | ID: covidwho-1232468

ABSTRACT

SARS-CoV-2 is the novel coronavirus that is the causative agent of COVID-19, a sometimes-lethal respiratory infection responsible for a world-wide pandemic. The envelope (E) protein, one of four structural proteins encoded in the viral genome, is a 75-residue integral membrane protein whose transmembrane domain exhibits ion channel activity and whose cytoplasmic domain participates in protein-protein interactions. These activities contribute to several aspects of the viral replication-cycle, including virion assembly, budding, release, and pathogenesis. Here, we describe the structure and dynamics of full-length SARS-CoV-2 E protein in hexadecylphosphocholine micelles by NMR spectroscopy. We also characterized its interactions with four putative ion channel inhibitors. The chemical shift index and dipolar wave plots establish that E protein consists of a long transmembrane helix (residues 8-43) and a short cytoplasmic helix (residues 53-60) connected by a complex linker that exhibits some internal mobility. The conformations of the N-terminal transmembrane domain and the C-terminal cytoplasmic domain are unaffected by truncation from the intact protein. The chemical shift perturbations of E protein spectra induced by the addition of the inhibitors demonstrate that the N-terminal region (residues 6-18) is the principal binding site. The binding affinity of the inhibitors to E protein in micelles correlates with their antiviral potency in Vero E6 cells: HMA ≈ EIPA > DMA >> Amiloride, suggesting that bulky hydrophobic groups in the 5' position of the amiloride pyrazine ring play essential roles in binding to E protein and in antiviral activity. An N15A mutation increased the production of virus-like particles, induced significant chemical shift changes from residues in the inhibitor binding site, and abolished HMA binding, suggesting that Asn15 plays a key role in maintaining the protein conformation near the binding site. These studies provide the foundation for complete structure determination of E protein and for structure-based drug discovery targeting this protein.


Subject(s)
Amiloride/pharmacology , COVID-19/drug therapy , Coronavirus Envelope Proteins/metabolism , SARS-CoV-2/drug effects , SARS-CoV-2/metabolism , Amiloride/pharmacokinetics , Animals , Antiviral Agents/pharmacology , Binding Sites/drug effects , COVID-19/virology , Chlorocebus aethiops , Coronavirus Envelope Proteins/chemistry , Humans , Ion Channels/metabolism , Nuclear Magnetic Resonance, Biomolecular , Protein Binding/drug effects , Protein Conformation/drug effects , Protein Domains , Vero Cells , Virus Assembly/drug effects
8.
Nature ; 589(7843): 630-632, 2021 01.
Article in English | MEDLINE | ID: covidwho-1049956
9.
Front Immunol ; 11: 573339, 2020.
Article in English | MEDLINE | ID: covidwho-902400

ABSTRACT

Coronavirus (CoV) outbreaks have recently emerged as a global public health threat due to their exceptional zoonotic potential - a feature arising from their ability to infect a diverse range of potential hosts combined with their high capacity for mutation and recombination. After Severe Acute Respiratory Syndrome (SARS) CoV-1 in 2003 and Middle East Respiratory Syndrome (MERS) CoV in 2012, with the current SARS-CoV-2 pandemic we are now in the midst of the third deadly international CoV outbreak in less than 20 years. Coronavirus outbreaks present a critical threat to global public health and an urgent necessity for therapeutic options. Here, we critically examine the current evidence for ion channel activity in CoV proteins and the potential for modulation as a therapeutic approach.


Subject(s)
Ion Channels/metabolism , SARS Virus/metabolism , Severe Acute Respiratory Syndrome/virology , Viral Proteins/metabolism , Viroporin Proteins/metabolism , Animals , Humans , Ion Channels/genetics , SARS Virus/genetics , Viral Envelope Proteins/genetics , Viral Envelope Proteins/metabolism , Viral Proteins/genetics , Viroporin Proteins/genetics
10.
Channels (Austin) ; 14(1): 403-412, 2020 12.
Article in English | MEDLINE | ID: covidwho-889445

ABSTRACT

The COVID-19 pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has prompted an urgent need to identify effective medicines for the prevention and treatment of the disease. A comparative analysis between SARS-CoV-2 and Hepatitis C Virus (HCV) can expand the available knowledge regarding the virology and potential drug targets against these viruses. Interestingly, comparing HCV with SARS-CoV-2 reveals major similarities between them, ranging from the ion channels that are utilized, to the symptoms that are exhibited by patients. Via this comparative analysis, and from what is known about HCV, the most promising treatments for COVID-19 can focus on the reduction of viral load, treatment of pulmonary system damages, and reduction of inflammation. In particular, the drugs that show most potential in this regard include ritonavir, a combination of peg-IFN, and lumacaftor-ivacaftor. This review anaylses SARS-CoV-2 from the perspective of the role of ion homeostasis and channels in viral pathomechanism. We also highlight other novel treatment approaches that can be used for both treatment and prevention of COVID-19. The relevance of this review is to offer high-quality evidence that can be used as the basis for the identification of potential solutions to the COVID-19 pandemic.


Subject(s)
Betacoronavirus/metabolism , Coronavirus Infections/metabolism , Hepacivirus/metabolism , Ion Channels/metabolism , Pneumonia, Viral/metabolism , Animals , Betacoronavirus/pathogenicity , COVID-19 , Coronavirus Infections/pathology , Coronavirus Infections/virology , Hepacivirus/pathogenicity , Hepatitis C/metabolism , Hepatitis C/virology , Humans , Pandemics , Pneumonia, Viral/pathology , Pneumonia, Viral/virology , SARS-CoV-2
11.
Biochem Biophys Res Commun ; 530(1): 10-14, 2020 09 10.
Article in English | MEDLINE | ID: covidwho-609834

ABSTRACT

COVID-19 is one of the most impactful pandemics in recorded history. As such, the identification of inhibitory drugs against its etiological agent, SARS-CoV-2, is of utmost importance, and in particular, repurposing may provide the fastest route to curb the disease. As the first step in this route, we sought to identify an attractive and viable target in the virus for pharmaceutical inhibition. Using three bacteria-based assays that were tested on known viroporins, we demonstrate that one of its essential components, the E protein, is a potential ion channel and, therefore, is an excellent drug target. Channel activity was demonstrated for E proteins in other coronaviruses, providing further emphasis on the importance of this functionally to the virus' pathogenicity. The results of a screening effort involving a repurposing drug library of ion channel blockers yielded two compounds that inhibit the E protein: Gliclazide and Memantine. In conclusion, as a route to curb viral virulence and abate COVID-19, we point to the E protein of SARS-CoV-2 as an attractive drug target and identify off-label compounds that inhibit it.


Subject(s)
Antiviral Agents/pharmacology , Betacoronavirus/drug effects , Gliclazide/pharmacology , Ion Channels/antagonists & inhibitors , Memantine/pharmacology , Viral Envelope Proteins/antagonists & inhibitors , Betacoronavirus/metabolism , COVID-19 , Coronavirus Envelope Proteins , Coronavirus Infections/drug therapy , Coronavirus Infections/virology , Drug Discovery , Drug Repositioning , Humans , Ion Channels/metabolism , Pandemics , Pneumonia, Viral/drug therapy , Pneumonia, Viral/virology , SARS-CoV-2 , Viral Envelope Proteins/metabolism
12.
Eur J Pharmacol ; 882: 173237, 2020 Sep 05.
Article in English | MEDLINE | ID: covidwho-548751

ABSTRACT

Pirfenidone (PFD), a pyridone compound, is well recognized as an antifibrotic agent tailored for the treatment of idiopathic pulmonary fibrosis. Recently, through its anti-inflammatory and anti-oxidant effects, PFD based clinical trial has also been launched for the treatment of coronavirus disease (COVID-19). To what extent this drug can perturb membrane ion currents remains largely unknown. Herein, the exposure to PFD was observed to depress the amplitude of hyperpolarization-activated cation current (Ih) in combination with a considerable slowing in the activation time of the current in pituitary GH3 cells. In the continued presence of ivabradine or zatebradine, subsequent application of PFD decreased Ih amplitude further. The presence of PFD resulted in a leftward shift in Ih activation curve without changes in the gating charge. The addition of this compound also led to a reduction in area of voltage-dependent hysteresis evoked by long-lasting inverted triangular (downsloping and upsloping) ramp pulse. Neither the amplitude of M-type nor erg-mediated K+ current was altered by its presence. In whole-cell potential recordings, addition of PFD reduced the firing frequency, and this effect was accompanied by the depression in the amplitude of sag voltage elicited by hyperpolarizing current stimulus. Overall, this study highlights evidence that PFD is capable of perturbing specific ionic currents, revealing a potential additional impact on functional activities of different excitable cells.


Subject(s)
Cell Membrane/drug effects , Coronavirus Infections/drug therapy , Pneumonia, Viral/drug therapy , Pyridones/pharmacology , Animals , Betacoronavirus/metabolism , COVID-19 , Cations/metabolism , Cell Line, Tumor , Cell Membrane/metabolism , Coronavirus Infections/virology , Humans , Ion Channels/drug effects , Ion Channels/metabolism , Ion Transport/drug effects , Membrane Potentials/drug effects , Pandemics , Pneumonia, Viral/virology , Potassium/metabolism , Pyridones/therapeutic use , Rats , SARS-CoV-2 , Sodium/metabolism
13.
Cell Calcium ; 88: 102212, 2020 06.
Article in English | MEDLINE | ID: covidwho-186635
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