scholarly journals Therapeutic Strategies for Neuropathic Pain: Potential Application of Pharmacosynthetics and Optogenetics

2016 ◽  
Vol 2016 ◽  
pp. 1-11 ◽  
Author(s):  
Gum Hwa Lee ◽  
Sang Seong Kim
Keyword(s):  
Neuropathic Pain ◽  
Sequence Analysis ◽  
Ion Channel ◽  
G Protein ◽  
Intracellular Signaling ◽  
Transient Receptor Potential ◽  
Trp Channels ◽  
Pain Treatment ◽  
Neuronal Damage ◽  
Rna Sequence

Chronic pain originating from neuronal damage remains an incurable symptom debilitating patients. Proposed molecular modalities in neuropathic pain include ion channel expressions, immune reactions, and inflammatory substrate diffusions. Recent advances in RNA sequence analysis have discovered specific ion channel expressions in nociceptors such as transient receptor potential (TRP) channels, voltage-gated potassium, and sodium channels. G protein-coupled receptors (GPCRs) also play an important role in triggering surrounding immune cells. The multiple protein expressions complicate therapeutic development for neuropathic pain. Recent progress in optogenetics and pharmacogenetics may herald the development of novel therapeutics for the incurable pain. Designer Receptors Exclusively Activated by Designer Drugs (DREADDs) facilitate the artificial manipulation of intracellular signaling through excitatory or inhibitory G protein subunits activated by biologically inert synthetic ligands. Expression of excitatory channelrhodopsins and inhibitory halorhodopsins on injured neurons or surrounding cells can attenuate neuropathic pain precisely controlled by light stimulation. To achieve the discrete treatment of injured neurons, we can exploit the transcriptome database obtained by RNA sequence analysis in specific neuropathies. This can recommend the suitable promoter information to target the injury sites circumventing intact neurons. Therefore, novel strategies benefiting from pharmacogenetics, optogenetics, and RNA sequencing might be promising for neuropathic pain treatment in future.

scholarly journals Renal Autoregulation in Health and Disease

2015 ◽  
Vol 95 (2) ◽  
pp. 405-511 ◽  
Author(s):  
Mattias Carlström ◽  
Christopher S. Wilcox ◽  
William J. Arendshorst
Keyword(s):  
Intracellular Signaling ◽  
Transient Receptor Potential ◽  
Trp Channels ◽  
Tubuloglomerular Feedback ◽  
Free Calcium ◽  
Myogenic Response ◽  
Renal Vasculature ◽  
Renal Autoregulation ◽  
Positive Balance ◽  
Health And Disease

Intrarenal autoregulatory mechanisms maintain renal blood flow (RBF) and glomerular filtration rate (GFR) independent of renal perfusion pressure (RPP) over a defined range (80–180 mmHg). Such autoregulation is mediated largely by the myogenic and the macula densa-tubuloglomerular feedback (MD-TGF) responses that regulate preglomerular vasomotor tone primarily of the afferent arteriole. Differences in response times allow separation of these mechanisms in the time and frequency domains. Mechanotransduction initiating the myogenic response requires a sensing mechanism activated by stretch of vascular smooth muscle cells (VSMCs) and coupled to intracellular signaling pathways eliciting plasma membrane depolarization and a rise in cytosolic free calcium concentration ([Ca2+]i). Proposed mechanosensors include epithelial sodium channels (ENaC), integrins, and/or transient receptor potential (TRP) channels. Increased [Ca2+]ioccurs predominantly by Ca2+influx through L-type voltage-operated Ca2+channels (VOCC). Increased [Ca2+]iactivates inositol trisphosphate receptors (IP3R) and ryanodine receptors (RyR) to mobilize Ca2+from sarcoplasmic reticular stores. Myogenic vasoconstriction is sustained by increased Ca2+sensitivity, mediated by protein kinase C and Rho/Rho-kinase that favors a positive balance between myosin light-chain kinase and phosphatase. Increased RPP activates MD-TGF by transducing a signal of epithelial MD salt reabsorption to adjust afferent arteriolar vasoconstriction. A combination of vascular and tubular mechanisms, novel to the kidney, provides for high autoregulatory efficiency that maintains RBF and GFR, stabilizes sodium excretion, and buffers transmission of RPP to sensitive glomerular capillaries, thereby protecting against hypertensive barotrauma. A unique aspect of the myogenic response in the renal vasculature is modulation of its strength and speed by the MD-TGF and by a connecting tubule glomerular feedback (CT-GF) mechanism. Reactive oxygen species and nitric oxide are modulators of myogenic and MD-TGF mechanisms. Attenuated renal autoregulation contributes to renal damage in many, but not all, models of renal, diabetic, and hypertensive diseases. This review provides a summary of our current knowledge regarding underlying mechanisms enabling renal autoregulation in health and disease and methods used for its study.

scholarly journals The nonselective cation channel TRPV4 inhibits angiotensin II receptors

2020 ◽  
Vol 295 (29) ◽  
pp. 9986-9997
Author(s):  
Nicholas W. Zaccor ◽  
Charlotte J. Sumner ◽  
Solomon H. Snyder
Keyword(s):  
Angiotensin Ii ◽  
G Protein ◽  
Transient Receptor Potential ◽  
Trp Channels ◽  
Receptor Potential ◽  
Trp Channel ◽  
Luciferase Assay ◽  
Transient Receptor Potential Vanilloid ◽  
Dependent Manner ◽  
Transient Receptor

G-protein–coupled receptors (GPCRs) are a ubiquitously expressed family of receptor proteins that regulate many physiological functions and other proteins. They act through two dissociable signaling pathways: the exchange of GDP to GTP by linked G-proteins and the recruitment of β-arrestins. GPCRs modulate several members of the transient receptor potential (TRP) channel family of nonselective cation channels. How TRP channels reciprocally regulate GPCR signaling is less well-explored. Here, using an array of biochemical approaches, including immunoprecipitation and fluorescence, calcium imaging, phosphate radiolabeling, and a β-arrestin–dependent luciferase assay, we characterize a GPCR–TRP channel pair, angiotensin II receptor type 1 (AT1R), and transient receptor potential vanilloid 4 (TRPV4), in primary murine choroid plexus epithelial cells and immortalized cell lines. We found that AT1R and TRPV4 are binding partners and that activation of AT1R by angiotensin II (ANGII) elicits β-arrestin–dependent inhibition and internalization of TRPV4. Activating TRPV4 with endogenous and synthetic agonists inhibited angiotensin II–mediated G-protein–associated second messenger accumulation, AT1R receptor phosphorylation, and β-arrestin recruitment. We also noted that TRPV4 inhibits AT1R phosphorylation by activating the calcium-activated phosphatase calcineurin in a Ca2+/calmodulin–dependent manner, preventing β-arrestin recruitment and receptor internalization. These findings suggest that when TRP channels and GPCRs are co-expressed in the same tissues, many of these channels can inhibit GPCR desensitization.

scholarly journals Common mechanisms regulating dark noise and quantum bump amplification in Drosophila photoreceptors

2013 ◽  
Vol 109 (8) ◽  
pp. 2044-2055 ◽  
Author(s):  
Brian Chu ◽  
Che-Hsiung Liu ◽  
Sukanya Sengupta ◽  
Amit Gupta ◽  
Padinjat Raghu ◽  
...  
Keyword(s):  
G Protein ◽  
Transient Receptor Potential ◽  
Trp Channels ◽  
Receptor Potential ◽  
Diacylglycerol Kinase ◽  
Scaffolding Protein ◽  
Light Responses ◽  
Α Subunit ◽  
High Quantum Efficiency ◽  
Dark Noise

Absolute visual thresholds are limited by “dark noise,” which in Drosophila photoreceptors is dominated by brief (∼10 ms), small (∼2 pA) inward current events, occurring at ∼2/s, believed to reflect spontaneous G protein activations. These dark events were increased in rate and amplitude by a point mutation in myosin III (NINAC), which disrupts its interaction with the scaffolding protein, INAD. This phenotype mimics that previously described in null mutants of ninaC (no inactivation no afterpotential; encoding myosin III) and an associated protein, retinophilin ( rtp). Dark noise was similarly increased in heterozygote mutants of diacylglycerol kinase ( rdgA/+). Dark noise in ninaC, rtp, and rdgA/+ mutants was greatly suppressed by mutations of the Gq α-subunit ( Gα q) and the major light-sensitive channel ( trp) but not rhodopsin. ninaC, rtp, and rdgA/+ mutations also all facilitated residual light responses in Gα q and PLC hypomorphs. Raising cytosolic Ca2+ in the submicromolar range increased dark noise, facilitated activation of transient receptor potential (TRP) channels by exogenous agonist, and again facilitated light responses in Gα q hypomorphs. Our results indicate that RTP, NINAC, INAD, and diacylglycerol kinase, together with a Ca2+-dependent threshold, share common roles in suppressing dark noise and regulating quantum bump generation; consequently, most spontaneous G protein activations fail to generate dark events under normal conditions. By contrast, quantum bump generation is reliable but delayed until sufficient G proteins and PLC are activated to overcome threshold, thereby ensuring generation of full-size bumps with high quantum efficiency.

scholarly journals Role of Specialized Pro-Resolving Mediators in Neuropathic Pain

2021 ◽  
Vol 12 ◽  
Author(s):  
Alessandro Leuti ◽  
Marina Fava ◽  
Niccolò Pellegrini ◽  
Mauro Maccarrone
Keyword(s):  
Neuropathic Pain ◽  
Pain Perception ◽  
Transient Receptor Potential ◽  
Trp Channels ◽  
Phase 1 ◽  
Receptor Potential ◽  
Inflammatory Cells ◽  
Experimental Models ◽  
Convincing Evidence

Inflammation and neuroinflammation are critical mechanisms in the generation of neuropathic pain that is experienced in several chronic diseases. The aberrant inflammation that triggers this pathophysiologic process can be tracked down to an exacerbated immune response, which establishes a vicious cycle and continuously recruits inflammatory cells by inducing chronic tissue damage. Recently, impairment of the cellular and molecular machinery orchestrated by specialized pro-resolving mediators (SPMs)—i.e., endogenous lipids termed resolvins, protectins, maresins, and lipoxins that confine the inflammatory cascades in space and time during the “resolution of inflammation”–has emerged as a crucial event in the derangement of the inflammatory homeostasis and the onset of chronic inflammation and pain. Indeed, a deviant inflammatory response that is not adequately controlled by the resolution network leads to the overproduction of pro-inflammatory eicosanoids that, opposite to SPMs, lead to neuropathic pain. Interestingly, in the last two decades convincing evidence has demonstrated that SPMs antagonize the in vivo activity of pro-inflammatory eicosanoids and, overall, exert potent anti-hyperalgesic effects in a number of pain-associated paradigms of disease, such as arthritis and chemotherapy-induced peripheral neuropathy, as well as in many experimental models of pain like mechanical allodynia, chemical pain, heat hypersensitivity and phase 1 and 2 inflammatory pain. Of note, accumulated evidence supports a synergy between SPMs and other signalling pathways, such as those mediated by transient receptor potential (TRP) channels and those triggered by opioid receptors, suggesting that the cascade of events where inflammation and pain perception take part might be ways more intricated than originally expected. Here, we aim at presenting a state-of-the-art view of SPMs, their metabolism and signalling, in the context of cellular and molecular pathways associated to neuropathic pain.

scholarly journals TRPV4: A Physio and Pathophysiologically Significant Ion Channel

2020 ◽  
Vol 21 (11) ◽  
pp. 3837 ◽  
Author(s):  
Tamara Rosenbaum ◽  
Miguel Benítez-Angeles ◽  
Raúl Sánchez-Hernández ◽  
Sara Luz Morales-Lázaro ◽  
Marcia Hiriart ◽  
...  
Keyword(s):  
Clinical Trials ◽  
Animal Models ◽  
Ion Channel ◽  
Therapeutic Target ◽  
Transient Receptor Potential ◽  
Trp Channels ◽  
Receptor Potential ◽  
Transient Receptor ◽  
Near Future ◽  
Lines Of Evidence

Transient Receptor Potential (TRP) channels are a family of ion channels whose members are distributed among all kinds of animals, from invertebrates to vertebrates. The importance of these molecules is exemplified by the variety of physiological roles they play. Perhaps, the most extensively studied member of this family is the TRPV1 ion channel; nonetheless, the activity of TRPV4 has been associated to several physio and pathophysiological processes, and its dysfunction can lead to severe consequences. Several lines of evidence derived from animal models and even clinical trials in humans highlight TRPV4 as a therapeutic target and as a protein that will receive even more attention in the near future, as will be reviewed here.

TRPC3-Based Protein Signaling Complex as a Therapeutic Target of Myocardial Atrophy

2020 ◽  
Vol 14 (2) ◽  
pp. 123-131
Author(s):  
Kazuhiro Nishiyama ◽  
Tomohiro Tanaka ◽  
Akiyuki Nishimura ◽  
Motohiro Nishida
Keyword(s):  
Drug Treatment ◽  
Protein Interactions ◽  
Therapeutic Target ◽  
Intracellular Signaling ◽  
Transient Receptor Potential ◽  
Trp Channels ◽  
Interstitial Fibrosis ◽  
Receptor Potential ◽  
Cancer Drug ◽  
Myocardial Atrophy

Background: Transient receptor potential (TRP) channels, especially canonical TRP channel subfamily members 3 (TRPC3) and 6 (TRPC6), have attracted attention as a putative therapeutic target of heart | 1 failure. Moreover, TRPC3 and TRPC6 channels are physiologically important for maintaining cellular homeostasis. How TRPC3/C6 channels alter intracellular signaling from adaptation to maladaptation has been discussed for many years. We recently showed that formation of a protein signal complex between TRPC3 and NADPH oxidase (Nox) 2 caused by environmental stresses (e.g., hypoxia, nutritional deficiency, and anticancer drug treatment) promotes Nox2-dependent reactive oxygen species production and cardiac stiffness, including myocardial atrophy and interstitial fibrosis, in rodents. In fact, pharmacological prevention of the TRPC3-Nox2 protein complex can maintain cardiac flexibility in mice after anti-cancer drug treatment. Conclusion: In this mini-review, we discuss the relationship between TRPC3/C6 channels and cardiovascular disease, and propose a new therapeutic strategy by focusing on pathology-specific protein– protein interactions.

scholarly journals A Transient Receptor Potential Ion Channel in Chlamydomonas Shares Key Features with Sensory Transduction-Associated TRP Channels in Mammals

2015 ◽  
Vol 27 (1) ◽  
pp. 177-188 ◽  
Author(s):  
Luis Arias-Darraz ◽  
Deny Cabezas ◽  
Charlotte K. Colenso ◽  
Melissa Alegría-Arcos ◽  
Felipe Bravo-Moraga ◽  
...  
Keyword(s):  
Ion Channel ◽  
Transient Receptor Potential ◽  
Trp Channels ◽  
Receptor Potential ◽  
Sensory Transduction ◽  
Key Features ◽  
Transient Receptor

scholarly journals The push-to-open mechanism of the tethered mechanosensitive ion channel NompC

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Yang Wang ◽  
Yifeng Guo ◽  
Guanluan Li ◽  
Chunhong Liu ◽  
Lei Wang ◽  
...  
Keyword(s):  
Ion Channel ◽  
Transient Receptor Potential ◽  
Trp Channels ◽  
Receptor Potential ◽  
Ankyrin Repeat ◽  
Gating Mechanism ◽  
Repeat Domain ◽  
Mechanosensitive Ion Channel ◽  
Transient Receptor ◽  
Dynamics Simulations

NompC is a mechanosensitive ion channel responsible for the sensation of touch and balance in Drosophila melanogaster. Based on a resolved cryo-EM structure, we performed all-atom molecular dynamics simulations and electrophysiological experiments to study the atomistic details of NompC gating. Our results showed that NompC could be opened by compression of the intracellular ankyrin repeat domain but not by a stretch, and a number of hydrogen bonds along the force convey pathway are important for the mechanosensitivity. Under intracellular compression, the bundled ankyrin repeat region acts like a spring with a spring constant of ~13 pN nm−1 by transferring forces at a rate of ~1.8 nm ps−1. The linker helix region acts as a bridge between the ankyrin repeats and the transient receptor potential (TRP) domain, which passes on the pushing force to the TRP domain to undergo a clockwise rotation, resulting in the opening of the channel. This could be the universal gating mechanism of similar tethered mechanosensitive TRP channels, which enable cells to feel compression and shrinkage.

scholarly journals The G protein-biased PZM21 and TRV130 act as partial agonists of μ-opioid receptors signaling to ion channel targets

2018 ◽  
Author(s):  
Yevgen Yudin ◽  
Tibor Rohacs
Keyword(s):  
Ion Channels ◽  
Ion Channel ◽  
G Protein ◽  
Opioid Receptors ◽  
Transient Receptor Potential ◽  
Receptor Potential ◽  
Partial Agonists ◽  
Transient Receptor Potential Melastatin ◽  
Transient Receptor ◽  
Μ Opioid Receptors

Opioids exert many of their acute effects through modulating ion channels via Gβγ subunits. Some of their side effects are attributed to β-arrestin recruitment, and several biased agonists that do not activate this pathway have been developed recently. Here we tested the effects of TRV130, PZM21 and herkinorin, three G-protein biased agonists of μ-opioid receptors (μOR), on ion channel targets. Compared to the full μOR agonist DAMGO, all three biased agonists induced smaller activation of G protein-coupled inwardly rectifying potassium channels (GIRK2), and smaller inhibition of Transient Receptor Potential Melastatin (TRPM3) channels. Furthermore, co-application of TRV130 or PZM21, but not herkinorin reduced the effects of DAMGO on both ion channels. CaV2.2 was also inhibited less by PZM21 and TRV130 than by DAMGO. TRV130, PZM21 and herkinorin were also less effective than DAMGO in inducing dissociation of the Gαi /Gβγ complex. We conclude that TRV130, PZM21 are partial agonists of μOR.

scholarly journals Transient receptor potential melastatin 3 is a phosphoinositide-dependent ion channel

2015 ◽  
Vol 146 (1) ◽  
pp. 65-77 ◽  
Author(s):  
Doreen Badheka ◽  
Istvan Borbiro ◽  
Tibor Rohacs
Keyword(s):  
Ion Channel ◽  
Transient Receptor Potential ◽  
Kinase Inhibitors ◽  
Trp Channels ◽  
Receptor Potential ◽  
Channel Activity ◽  
Intact Cells ◽  
Transient Receptor Potential Melastatin ◽  
Transient Receptor ◽  
Phosphatidylinositol 4

Phosphoinositides are emerging as general regulators of the functionally diverse transient receptor potential (TRP) ion channel family. Phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2) has been reported to positively regulate many TRP channels, but in several cases phosphoinositide regulation is controversial. TRP melastatin 3 (TRPM3) is a heat-activated ion channel that is also stimulated by chemical agonists, such as pregnenolone sulfate. Here, we used a wide array of approaches to determine the effects of phosphoinositides on TRPM3. We found that channel activity in excised inside-out patches decreased over time (rundown), an attribute of PI(4,5)P2-dependent ion channels. Channel activity could be restored by application of either synthetic dioctanoyl (diC8) or natural arachidonyl stearyl (AASt) PI(4,5)P2. The PI(4,5)P2 precursor phosphatidylinositol 4-phosphate (PI(4)P) was less effective at restoring channel activity. TRPM3 currents were also restored by MgATP, an effect which was inhibited by two different phosphatidylinositol 4-kinase inhibitors, or by pretreatment with a phosphatidylinositol-specific phospholipase C (PI-PLC) enzyme, indicating that MgATP acted by generating phosphoinositides. In intact cells, reduction of PI(4,5)P2 levels by chemically inducible phosphoinositide phosphatases or a voltage-sensitive 5′-phosphatase inhibited channel activity. Activation of PLC via muscarinic receptors also inhibited TRPM3 channel activity. Overall, our data indicate that TRPM3 is a phosphoinositide-dependent ion channel and that decreasing PI(4,5)P2 abundance limits its activity. As all other members of the TRPM family have also been shown to require PI(4,5)P2 for activity, our data establish PI(4,5)P2 as a general positive cofactor of this ion channel subfamily.

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