scholarly journals TLR4 activation of TRPC6-dependent calcium signaling mediates endotoxin-induced lung vascular permeability and inflammation

2012 ◽  
Vol 209 (11) ◽  
pp. 1953-1968 ◽  
Author(s):  
Mohammad Tauseef ◽  
Nebojsa Knezevic ◽  
Koteswara R. Chava ◽  
Monica Smith ◽  
Sukriti Sukriti ◽  
...  
Keyword(s):  
Vascular Permeability ◽  
Transient Receptor Potential ◽  
Endothelial Permeability ◽  
Receptor Potential ◽  
Trpc Channels ◽  
Dependent Manner ◽  
Barrier Dysfunction ◽  
Barrier Disruption ◽  
Transient Receptor ◽  
Lung Vascular Permeability

Lung vascular endothelial barrier disruption and the accompanying inflammation are primary pathogenic features of acute lung injury (ALI); however, the basis for the development of both remains unclear. Studies have shown that activation of transient receptor potential canonical (TRPC) channels induces Ca2+ entry, which is essential for increased endothelial permeability. Here, we addressed the role of Toll-like receptor 4 (TLR4) intersection with TRPC6-dependent Ca2+ signaling in endothelial cells (ECs) in mediating lung vascular leakage and inflammation. We find that the endotoxin (lipopolysaccharide; LPS) induces Ca2+ entry in ECs in a TLR4-dependent manner. Moreover, deletion of TRPC6 renders mice resistant to endotoxin-induced barrier dysfunction and inflammation, and protects against sepsis-induced lethality. TRPC6 induces Ca2+ entry in ECs, which is secondary to the generation of diacylglycerol (DAG) induced by LPS. Ca2+ entry mediated by TRPC6, in turn, activates the nonmuscle myosin light chain kinase (MYLK), which not only increases lung vascular permeability but also serves as a scaffold to promote the interaction of myeloid differentiation factor 88 and IL-1R–associated kinase 4, which are required for NF-κB activation and lung inflammation. Our findings suggest that TRPC6-dependent Ca2+ entry into ECs, secondary to TLR4-induced DAG generation, participates in mediating both lung vascular barrier disruption and inflammation induced by endotoxin.

scholarly journals The Na+/Ca2+ Exchanger Inhibitor, KB-R7943, Blocks a Nonselective Cation Channel Implicated in Chemosensory Transduction

2009 ◽  
Vol 101 (3) ◽  
pp. 1151-1159 ◽  
Author(s):  
A. Pezier ◽  
Y. V. Bobkov ◽  
B. W. Ache
Keyword(s):  
Transient Receptor Potential ◽  
Single Channel ◽  
Receptor Potential ◽  
Trpc Channels ◽  
Dependent Manner ◽  
Open Probability ◽  
Olfactory Transduction ◽  
Voltage Dependent ◽  
Chemosensory Transduction ◽  
Transient Receptor

The mechanism(s) of olfactory transduction in invertebrates remains to be fully understood. In lobster olfactory receptor neurons (ORNs), a nonselective sodium-gated cation (SGC) channel, a presumptive transient receptor potential (TRP)C channel homolog, plays a crucial role in olfactory transduction, at least in part by amplifying the primary transduction current. To better determine the functional role of the channel, it is important to selectively block the channel independently of other elements of the transduction cascade, causing us to search for specific pharmacological blockers of the SGC channel. Given evidence that the Na+/Ca2+ exchange inhibitor, KB-R7943, blocks mammalian TRPC channels, we studied this probe as a potential blocker of the lobster SGC channel. KB-R7943 reversibly blocked the SGC current in both inside- and outside-out patch recordings in a dose- and voltage-dependent manner. KB-R7943 decreased the channel open probability without changing single channel amplitude. KB-R7943 also reversibly and in a dose-dependent manner inhibited both the odorant-evoked discharge of lobster ORNs and the odorant-evoked whole cell current. Our findings strongly imply that KB-R7943 potently blocks the lobster SGC channel and likely does so directly and not through its ability to block the Na+/Ca2+ exchanger.

scholarly journals Transient Receptor Potential Canonical (TRPC) Channels: Then and Now

Cells ◽  
2020 ◽  
Vol 9 (9) ◽  
pp. 1983
Author(s):  
Xingjuan Chen ◽  
Gagandeep Sooch ◽  
Isaac S. Demaree ◽  
Fletcher A. White ◽  
Alexander G. Obukhov
Keyword(s):  
Molecular Mechanisms ◽  
Transient Receptor Potential ◽  
Trp Channels ◽  
Receptor Potential ◽  
Hereditary Diseases ◽  
Trpc Channels ◽  
Dependent Manner ◽  
Transient Receptor Potential Canonical ◽  
Cell Functions ◽  
Transient Receptor

Twenty-five years ago, the first mammalian Transient Receptor Potential Canonical (TRPC) channel was cloned, opening the vast horizon of the TRPC field. Today, we know that there are seven TRPC channels (TRPC1–7). TRPCs exhibit the highest protein sequence similarity to the Drosophila melanogaster TRP channels. Similar to Drosophila TRPs, TRPCs are localized to the plasma membrane and are activated in a G-protein-coupled receptor-phospholipase C-dependent manner. TRPCs may also be stimulated in a store-operated manner, via receptor tyrosine kinases, or by lysophospholipids, hypoosmotic solutions, and mechanical stimuli. Activated TRPCs allow the influx of Ca2+ and monovalent alkali cations into the cytosol of cells, leading to cell depolarization and rising intracellular Ca2+ concentration. TRPCs are involved in the continually growing number of cell functions. Furthermore, mutations in the TRPC6 gene are associated with hereditary diseases, such as focal segmental glomerulosclerosis. The most important recent breakthrough in TRPC research was the solving of cryo-EM structures of TRPC3, TRPC4, TRPC5, and TRPC6. These structural data shed light on the molecular mechanisms underlying TRPCs’ functional properties and propelled the development of new modulators of the channels. This review provides a historical overview of the major advances in the TRPC field focusing on the role of gene knockouts and pharmacological tools.

scholarly journals Transient Receptor Potential Cation Channels and Calcium Dyshomeostasis in a Mouse Model Relevant to Malignant Hyperthermia

2020 ◽  
Vol 133 (2) ◽  
pp. 364-376 ◽  
Author(s):  
Jose Rafael Lopez ◽  
Vikas Kaura ◽  
Phillip Hopkins ◽  
Xiaochen Liu ◽  
Arkady Uryach ◽  
...  
Keyword(s):  
Mouse Model ◽  
Malignant Hyperthermia ◽  
Transient Receptor Potential ◽  
Receptor Potential ◽  
Muscle Cells ◽  
Cation Channels ◽  
Trpc Channels ◽  
Dependent Manner ◽  
Wild Type ◽  
Transient Receptor

Background Until recently, the mechanism for the malignant hyperthermia crisis has been attributed solely to sustained massive Ca2+ release from the sarcoplasmic reticulum on exposure to triggering agents. This study tested the hypothesis that transient receptor potential cation (TRPC) channels are important contributors to the Ca2+ dyshomeostasis in a mouse model relevant to malignant hyperthermia. Methods This study examined the mechanisms responsible for Ca2+ dyshomeostasis in RYR1-p.G2435R mouse muscles and muscle cells using calcium and sodium ion selective microelectrodes, manganese quench of Fura2 fluorescence, and Western blots. Results RYR1-p.G2435R mouse muscle cells have chronically elevated intracellular resting calcium and sodium and rate of manganese quench (homozygous greater than heterozygous) compared with wild-type muscles. After exposure to 1-oleoyl-2-acetyl-sn-glycerol, a TRPC3/6 activator, increases in intracellular resting calcium/sodium were significantly greater in RYR1-p.G2435R muscles (from 153 ± 11 nM/10 ± 0.5 mM to 304 ± 45 nM/14.2 ± 0.7 mM in heterozygotes P < 0.001] and from 251 ± 25 nM/13.9 ± 0.5 mM to 534 ± 64 nM/20.9 ± 1.5 mM in homozygotes [P < 0.001] compared with 123 ± 3 nM/8 ± 0.1 mM to 196 ± 27 nM/9.4 ± 0.7 mM in wild type). These increases were inhibited both by simply removing extracellular Ca2+ and by exposure to either a nonspecific (gadolinium) or a newly available, more specific pharmacologic agent (SAR7334) to block TRPC6- and TRPC3-mediated cation influx into cells. Furthermore, local pretreatment with SAR7334 partially decreased the elevation of intracellular resting calcium that is seen in RYR1-p.G2435R muscles during exposure to halothane. Western blot analysis showed that expression of TRPC3 and TRPC6 were significantly increased in RYR1-p.G2435R muscles in a gene–dose–dependent manner, supporting their being a primary molecular basis for increased sarcolemmal cation influx. Conclusions Muscle cells in knock-in mice expressing the RYR1-p.G2435R mutation are hypersensitive to TRPC3/6 activators. This hypersensitivity can be negated with pharmacologic agents that block TRPC3/6 activity. This reinforces the working hypothesis that transient receptor potential cation channels play a critical role in causing intracellular calcium and sodium overload in malignant hyperthermia–susceptible muscle, both at rest and during the malignant hyperthermia crisis. Editor’s Perspective What We Already Know about This Topic What This Article Tells Us That Is New

scholarly journals Potentiation of TRPC5 by Protons

2007 ◽  
Vol 282 (46) ◽  
pp. 33868-33878 ◽  
Author(s):  
Marcus Semtner ◽  
Michael Schaefer ◽  
Olaf Pinkenburg ◽  
Tim D. Plant
Keyword(s):  
Phospholipase C ◽  
Transient Receptor Potential ◽  
Single Channel ◽  
Receptor Potential ◽  
High Sensitivity ◽  
Transient Receptor Potential Channel ◽  
Extracellular Ph ◽  
Dependent Manner ◽  
Open Probability ◽  
Transient Receptor

Mammalian members of the classical transient receptor potential channel subfamily (TRPC) are Ca2+-permeable cation channels involved in receptor-mediated increases in intracellular Ca2+. TRPC4 and TRPC5 form a group within the TRPC subfamily and are activated in a phospholipase C-dependent manner by an unidentified messenger. Unlike most other Ca2+-permeable channels, TRPC4 and -5 are potentiated by micromolar concentrations of La3+ and Gd3+. This effect results from an action of the cations at two glutamate residues accessible from the extracellular solution. Here, we show that TRPC4 and -5 respond to changes in extracellular pH. Lowering the pH increased both G protein-activated and spontaneous TRPC5 currents. Both effects were already observed with small reductions in pH (from 7.4 to 7.0) and increased up to pH 6.5. TRPC4 was also potentiated by decreases in pH, whereas TRPC6 was only inhibited, with a pIC50 of 5.7. Mutation of the glutamate residues responsible for lanthanoid sensitivity of TRPC5 (E543Q and E595Q) modified the potentiation of TRPC5 by acid. Further evidence for a similarity in the actions of lanthanoids and H+ on TRPC5 is the reduction in single channel conductance and dramatic increase in channel open probability in the presence of either H+ or Gd3+ that leads to larger integral currents. In conclusion, the high sensitivity of TRPC5 to H+ indicates that, in addition to regulation by phospholipase C and other factors, the channel may act as a sensor of pH that links decreases in extracellular pH to Ca2+ entry and depolarization.

scholarly journals The G protein βγ subunit mediates reannealing of adherens junctions to reverse endothelial permeability increase by thrombin

2009 ◽  
Vol 206 (12) ◽  
pp. 2761-2777 ◽  
Author(s):  
Nebojsa Knezevic ◽  
Mohammad Tauseef ◽  
Tracy Thennes ◽  
Dolly Mehta
Keyword(s):  
Vascular Permeability ◽  
Focal Adhesion ◽  
Inflammatory Mediator ◽  
Adherens Junctions ◽  
Endothelial Permeability ◽  
Endothelial Barrier ◽  
Dependent Manner ◽  
Permeability Increase ◽  
Lung Vascular Permeability

The inflammatory mediator thrombin proteolytically activates protease-activated receptor (PAR1) eliciting a transient, but reversible increase in vascular permeability. PAR1-induced dissociation of Gα subunit from heterotrimeric Gq and G12/G13 proteins is known to signal the increase in endothelial permeability. However, the role of released Gβγ is unknown. We now show that impairment of Gβγ function does not affect the permeability increase induced by PAR1, but prevents reannealing of adherens junctions (AJ), thereby persistently elevating endothelial permeability. We observed that in the naive endothelium Gβ1, the predominant Gβ isoform is sequestered by receptor for activated C kinase 1 (RACK1). Thrombin induced dissociation of Gβ1 from RACK1, resulting in Gβ1 interaction with Fyn and focal adhesion kinase (FAK) required for FAK activation. RACK1 depletion triggered Gβ1 activation of FAK and endothelial barrier recovery, whereas Fyn knockdown interrupted with Gβ1-induced barrier recovery indicating RACK1 negatively regulates Gβ1-Fyn signaling. Activated FAK associated with AJ and stimulated AJ reassembly in a Fyn-dependent manner. Fyn deletion prevented FAK activation and augmented lung vascular permeability increase induced by PAR1 agonist. Rescuing FAK activation in fyn−/− mice attenuated the rise in lung vascular permeability. Our results demonstrate that Gβ1-mediated Fyn activation integrates FAK with AJ, preventing persistent endothelial barrier leakiness.

scholarly journals Cutaneous Neuroimmune Interactions of TSLP and TRPV4 Play Pivotal Roles in Dry Skin-Induced Pruritus

2021 ◽  
Vol 12 ◽  
Author(s):  
Wook-Joo Lee ◽  
Won-Sik Shim
Keyword(s):  
Mast Cells ◽  
Dorsal Root ◽  
Transient Receptor Potential ◽  
Skin Barrier ◽  
Receptor Potential ◽  
Barrier Dysfunction ◽  
Dry Skin ◽  
Neuroimmune Interactions ◽  
Skin Conditions ◽  
Transient Receptor

Dry skin is a symptom of skin barrier dysfunction that evokes pruritus; however, the cutaneous neuroimmune interactions underlying dry skin-induced pruritus remain unclear. Therefore, we aimed to elucidate the mechanisms underlying dry skin-induced pruritus. To this end, an acetone/ethanol/water (AEW)-induced mouse model of dry skin was used in this study. We observed that the production of thymic stromal lymphopoietin (TSLP) significantly increased in the keratinocytes of AEW mice. Importantly, treatment with an antagonist of transient receptor potential cation channel subfamily V member 4 (TRPV4), HC067047, ameliorated dry skin conditions in AEW mice. The symptoms of dry skin were significantly reduced in Trpv4 knockout (KO) mice following treatment with AEW. The increase in the intracellular calcium levels by TSLP in the dorsal root ganglia (DRG) of Trpv4 KO mice was also significantly attenuated. The spontaneous scratching bouts were significantly decreased in both the HC067047-treated and Trpv4 KO AEW mice. Importantly, the TSLP-dependent release of tryptase from the mast cells was significantly reduced in both the HC067047-treated mice and Trpv4 KO AEW mice. Notably, inhibition of the TSLP-induced signaling pathway in DRG selectively reduced the spontaneous scratching bouts in AEW mice. Overall, the results demonstrated that the cutaneous neuroimmune interactions of TSLP and TRPV4 play pivotal roles in dry skin-induced pruritus.

Regulation of Transient Receptor Potential Canonical 4 Activity by Phospholipase C-δ1

2020 ◽  
Author(s):  
Juyeon Ko ◽  
Jongyun Myeong ◽  
Misun Kwak ◽  
Insuk So
Keyword(s):  
Phospholipase C ◽  
Transient Receptor Potential ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Receptor Potential ◽  
Regulation Mechanism ◽  
Trpc Channels ◽  
Transient Receptor Potential Canonical ◽  
Cell Current ◽  
Transient Receptor

Abstract Transient receptor potential canonical (TRPC) channels are non-selective calcium-permeable cation channels. It is suggested that TRPC4β and TRPC5 channels are regulated by phospholipase C (PLC) signaling, and are especially maintained by phosphatidylinositol 4,5-bisphosphate (PIP2). The PLCδ subtype is the most Ca2+-sensitive form among the isozymes which cleaves phospholipids to respond to the calcium rise. In this study, we investigated the regulation mechanism of TRPC channel by Ca2+, PLCδ1 and PIP2 signaling cascades. The interaction between TRPC4β and PLCδ1 was identified through the Fӧster resonance energy transfer (FRET) and co-immunoprecipitation (Co-IP). With the electrophysiological experiments, we found that TRPC4β-bound PLCδ1 reduces the overall whole-cell current of channel. The Ca2+-via opened channel promotes the activation of PLCδ1, which subsequently decreases PIP2 level. By comparison TRPC4β activity with or without PLCδ1 using differently [Ca2+]i buffered solution, we demonstrated that PLCδ1 functions in normal condition with physiological calcium range. The negative regulation effect of PLCδ1 on TRPC4β helps to elucidate the roles of each PIP2 binding residues whether they are concerned in channel maintenance or inhibition of channel activity.

scholarly journals Canonical Transient Receptor Potential (TRPC) Channels in Nociception and Pathological Pain

2020 ◽  
Vol 2020 ◽  
pp. 1-13 ◽  
Author(s):  
Zhi-Chuan Sun ◽  
Sui-Bin Ma ◽  
Wen-Guang Chu ◽  
Dong Jia ◽  
Ceng Luo
Keyword(s):  
Chronic Pain ◽  
Molecular Mechanisms ◽  
Transient Receptor Potential ◽  
Receptor Potential ◽  
Trpc Channels ◽  
Canonical Transient Receptor Potential ◽  
Abnormal Increase ◽  
Pathological Pain ◽  
Transient Receptor ◽  
Underlying Mechanisms

Chronic pathological pain is one of the most intractable clinical problems faced by clinicians and can be devastating for patients. Despite much progress we have made in understanding chronic pain in the last decades, its underlying mechanisms remain elusive. It is assumed that abnormal increase of calcium levels in the cells is a key determinant in the transition from acute to chronic pain. Exploring molecular players mediating Ca2+ entry into cells and molecular mechanisms underlying activity-dependent changes in Ca2+ signaling in the somatosensory pain pathway is therefore helpful towards understanding the development of chronic, pathological pain. Canonical transient receptor potential (TRPC) channels form a subfamily of nonselective cation channels, which permit the permeability of Ca2+ and Na+ into the cells. Initiation of Ca2+ entry pathways by these channels triggers the development of many physiological and pathological functions. In this review, we will focus on the functional implication of TRPC channels in nociception with the elucidation of their role in the detection of external stimuli and nociceptive hypersensitivity.

scholarly journals Structure–Function Relationship and Physiological Roles of Transient Receptor Potential Canonical (TRPC) 4 and 5 Channels

Cells ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 73
Author(s):  
Jinsung Kim ◽  
Juyeon Ko ◽  
Chansik Hong ◽  
Insuk So
Keyword(s):  
Ion Channels ◽  
Structure Function ◽  
Transient Receptor Potential ◽  
Receptor Potential ◽  
Trpc Channels ◽  
Transient Receptor Potential Canonical ◽  
Structure Function Relationship ◽  
Transient Receptor ◽  
Function Relationship ◽  
Relationship Of

The study of the structure–function relationship of ion channels has been one of the most challenging goals in contemporary physiology. Revelation of the three-dimensional (3D) structure of ion channels has facilitated our understanding of many of the submolecular mechanisms inside ion channels, such as selective permeability, voltage dependency, agonist binding, and inter-subunit multimerization. Identifying the structure–function relationship of the ion channels is clinically important as well since only such knowledge can imbue potential therapeutics with practical possibilities. In a sense, recent advances in the understanding of the structure–relationship of transient receptor potential canonical (TRPC) channels look promising since human TRPC channels are calcium-permeable, non-selective cation channels expressed in many tissues such as the gastrointestinal (GI) tract, kidney, heart, vasculature, and brain. TRPC channels are known to regulate GI contractility and motility, pulmonary hypertension, right ventricular hypertrophy, podocyte injury, seizure, fear, anxiety-like behavior, and many others. In this article, we tried to elaborate recent findings of Cryo-EM (cryogenic-electron microscopy) based structural information of TRPC 4 and 5 channels and domain-specific functions of the channel, such as G-protein mediated activation mechanism, extracellular modification of the channel, homo/hetero-tetramerization, and pharmacological gating mechanisms.

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