Localized TRPA1 channel Ca2+ signals stimulated by reactive oxygen species promote cerebral artery dilation

Role of transient receptor potential channels in the regulation of vascular tone

Vascular tone is a major element in the control of hemodynamics. Transient receptor potential (TRP) channels conducting monovalent and/or divalent cations (e.g. Na+ and Ca2+) are expressed in the vasculature. Accumulating evidence suggests that TRP channels participate in regulating vascular tone by regulating intracellular Ca2+ signaling in both vascular smooth muscle cells (VSMCs) and endothelial cells (ECs). Aberrant expression/function of TRP channels in the vasculature is associated with vascular dysfunction in systemic/pulmonary hypertension and metabolic syndromes. This review intends to summarize our current knowledge of TRP-mediated regulation of vascular tone in both physiological and pathophysiological conditions and to discuss potential therapeutic approaches to tackle abnormal vascular tone due to TRP dysfunction.

Ion Channel Dysregulation Following Intracerebral Hemorrhage

Injury to the brain after intracerebral hemorrhage (ICH) results from numerous complex cellular mechanisms. At present, effective therapy for ICH is limited and a better understanding of the mechanisms of brain injury is necessary to improve prognosis. There is increasing evidence that ion channel dysregulation occurs at multiple stages in primary and secondary brain injury following ICH. Ion channels such as TWIK-related K+ channel 1, sulfonylurea 1 transient receptor potential melastatin 4 and glutamate-gated channels affect ion homeostasis in ICH. They in turn participate in the formation of brain edema, disruption of the blood-brain barrier, and the generation of neurotoxicity. In this review, we summarize the interaction between ions and ion channels, the effects of ion channel dysregulation, and we discuss some therapeutics based on ion-channel modulation following ICH.

Mechanosensing by Vascular Endothelium

Mechanical forces influence different cell types in our bodies. Among the earliest forces experienced in mammals is blood movement in the vascular system. Blood flow starts at the embryonic stage and ceases when the heart stops. Blood flow exposes endothelial cells (ECs) that line all blood vessels to hemodynamic forces. ECs detect these mechanical forces (mechanosensing) through mechanosensors, thus triggering physiological responses such as changes in vascular diameter. In this review, we focus on endothelial mechanosensing and on how different ion channels, receptors, and membrane structures detect forces and mediate intricate mechanotransduction responses. We further highlight that these responses often reflect collaborative efforts involving several mechanosensors and mechanotransducers. We close with a consideration of current knowledge regarding the dysregulation of endothelial mechanosensing during disease. Because hemodynamic disruptions are hallmarks of cardiovascular disease, studying endothelial mechanosensing holds great promise for advancing our understanding of vascular physiology and pathophysiology.

Electro-metabolic signaling

Precise matching of energy substrate delivery to local metabolic needs is essential for the health and function of all tissues. Here, we outline a mechanistic framework for understanding this critical process, which we refer to as electro-metabolic signaling (EMS). All tissues exhibit changes in metabolism over varying spatiotemporal scales and have widely varying energetic needs and reserves. We propose that across tissues, common signatures of elevated metabolism or increases in energy substrate usage that exceed key local thresholds rapidly engage mechanisms that generate hyperpolarizing electrical signals in capillaries that then relax contractile elements throughout the vasculature to quickly adjust blood flow to meet changing needs. The attendant increase in energy substrate delivery serves to meet local metabolic requirements and thus avoids a mismatch in supply and demand and prevents metabolic stress. We discuss in detail key examples of EMS that our laboratories have discovered in the brain and the heart, and we outline potential further EMS mechanisms operating in tissues such as skeletal muscle, pancreas, and kidney. We suggest that the energy imbalance evoked by EMS uncoupling may be central to cellular dysfunction from which the hallmarks of aging and metabolic diseases emerge and may lead to generalized organ failure states-such as diverse flavors of heart failure and dementia. Understanding and manipulating EMS may be key to preventing or reversing these dysfunctions.

Different Aspects of Aging in Migraine

Migraine is a common neurological disease displaying an unusual dependence on age. For most patients, the peak intensity of migraine headaches occurs in 20s and lasts until 40s, but then headache attacks become less intense, occur less frequently and the disease is more responsive to therapy. This relationship is valid in both females and males, although the prevalence of migraine in the former is 2-4 times greater than the latter. Recent concepts present migraine not only as a pathological event, but rather as a part of evolutionary adaptive response to protect organism against consequences of stress-induced brain energy deficit. However, these concepts do not fully explain that unusual dependence of migraine prevalence on age. Many aspects of aging, both molecular/cellular and social/cognitive, are interwound in migraine pathogenesis, but they neither explain why only some persons are affected by migraine, nor suggest any causal relationship. In this narrative/hypothesis review we present information on associations of migraine with chronological aging, brain aging, cellular senescence, stem cell exhaustion as well as social, cognitive, epigenetic, and metabolic aging. We also underline the role of oxidative stress in these associations. We hypothesize that migraine affects only individuals who have inborn, genetic/epigenetic, or acquired (traumas, shocks or complexes) migraine predispositions. These predispositions weakly depend on age and affected individuals are more prone to migraine triggers than others. Although the triggers can be related to many aspects of aging, social aging may play a particularly important role as the prevalence of its associated stress has a similar age-dependence as the prevalence of migraine. Moreover, social aging was shown to be associated with oxidative stress, important in many aspects of aging. In perspective, molecular mechanisms underlying social aging should be further explored and related to migraine with a closer association with migraine predisposition and difference in prevalence by sex.

Cracking the Endothelial Calcium (Ca2+) Code: A Matter of Timing and Spacing

A monolayer of endothelial cells lines the innermost surface of all blood vessels, thereby coming into close contact with every region of the body and perceiving signals deriving from both the bloodstream and parenchymal tissues. An increase in intracellular Ca2+ concentration ([Ca2+]i) is the main mechanism whereby vascular endothelial cells integrate the information conveyed by local and circulating cues. Herein, we describe the dynamics and spatial distribution of endothelial Ca2+ signals to understand how an array of spatially restricted (at both the subcellular and cellular levels) Ca2+ signals is exploited by the vascular intima to fulfill this complex task. We then illustrate how local endothelial Ca2+ signals affect the most appropriate vascular function and are integrated to transmit this information to more distant sites to maintain cardiovascular homeostasis. Vasorelaxation and sprouting angiogenesis were selected as an example of functions that are finely tuned by the variable spatio-temporal profile endothelial Ca2+ signals. We further highlighted how distinct Ca2+ signatures regulate the different phases of vasculogenesis, i.e., proliferation and migration, in circulating endothelial precursors.

TRPA1: A promising target for pulmonary fibrosis?

Pulmonary fibrosis is a disease characterized by progressive scar formation and the ultimate manifestation of numerous lung diseases. It is known as "cancer that is not cancer" and has attracted widespread attention. However, its formation process is very complex, and the mechanism of occurrence has not been fully elucidated. Current research has found that TRPA1 may be a promising target in the pathogenesis of pulmonary fibrosis. The TRPA1 channel was first successfully isolated in human lung fibroblasts, and it was found to have a relatively concentrated distribution in the lungs and respiratory tract. It is also involved in various acute and chronic inflammatory processes of lung diseases and may even play a core role in the progression and/or prevention of pulmonary fibrosis. Natural ligands targeting TRPA1 could offer a promising alternative treatment for pulmonary diseases. Therefore, this review delves into the current understanding of pulmonary fibrogenesis, analyzes TRPA1 biological properties and regulation of lung disease with a focus on pulmonary fibrosis, summarizes the TRPA1 molecular structure and its biological function, and summarizes TRPA1 natural ligand sources, anti-pulmonary fibrosis activity and potential mechanisms. The aim is to decipher the exact role of TRPA1 channels in the pathophysiology of pulmonary fibrosis and to consider their potential in the development of new therapeutic strategies.

Vasodilators activate the anion channel TMEM16A in endothelial cells to reduce blood pressure

Systemic blood pressure is acutely controlled by total peripheral resistance as determined by the diameter of small arteries and arterioles, the contractility of which is regulated by endothelial cells lining the lumen of blood vessels. We investigated the physiological functions of the chloride (Cl-) channel TMEM16A in endothelial cells. TMEM16A channels generated calcium (Ca2+)-activated Cl- currents in endothelial cells from control (TMEM16Afl/fl) mice that were absent in those from mice with tamoxifen-inducible, endothelial cell-specific knockout of TMEM16A (TMEM16A ecKO). TMEM16A currents in endothelial cells were activated by the muscarinic receptor agonist acetylcholine and an agonist of the Ca2+ channel TRPV4, which localized in nanoscale proximity with TMEM16A as assessed by single-molecule localization imaging of endothelial cells. Acetylcholine stimulated TMEM16A currents by activating Ca2+ influx through surface TRPV4 channels without altering the nanoscale properties of TMEM16A and TRPV4 surface clusters or their colocalization. In pressurized arteries, activation of TMEM16A channels in endothelial cells induced by acetylcholine; TRPV4 channel stimulation; or intraluminal ATP, another vasodilator, produced hyperpolarization and dilation. Furthermore, deficiency of TMEM16A channels in endothelial cells resulted in increased systemic blood pressure in conscious mice. These data indicate that vasodilators stimulate TRPV4 channels, leading to Ca2+-dependent activation of nearby TMEM16A channels in endothelial cells to produce arterial hyperpolarization, vasodilation, and reduced blood pressure. Thus, TMEM16A is an anion channel in endothelial cells that regulates arterial contractility and blood pressure.

Targeting temperature-sensitive transient receptor potential channels in hypertension: far beyond the perception of hot and cold

Transient receptor potential (TRP) channels are nonselective cation channels and participate in various physiological roles. Thus, changes in TRP channel function or expression have been linked to several disorders. Among the many TRP channel subtypes, the TRP ankyrin type 1 (TRPA1), TRP melastatin type 8 (TRPM8), and TRP vanilloid type 1 (TRPV1) channels are temperature-sensitive and recognized as thermo-TRPs, which are expressed in the primary afferent nerve. Thermal stimuli are converted into neuronal activity. Several studies have described the expression of TRPA1, TRPM8, and TRPV1 in the cardiovascular system, where these channels can modulate physiological and pathological conditions, including hypertension. This review provides a complete understanding of the functional role of the opposing thermo-receptors TRPA1/TRPM8/TRPV1 in hypertension and a more comprehensive appreciation of TRPA1/TRPM8/TRPV1-dependent mechanisms involved in hypertension. These channels varied activation and inactivation have revealed a signaling pathway that may lead to innovative future treatment options for hypertension and correlated vascular diseases.

Therapeutic potential of NOX inhibitors in neuropsychiatric disorders

RATIONALE

Neuropsychiatric disorders encompass a broad category of medical conditions that include both neurology as well as psychiatry such as major depressive disorder, autism spectrum disorder, bipolar disorder, schizophrenia as well as psychosis.

OBJECTIVE

NADPH-oxidase (NOX), which is the free radical generator, plays a substantial part in oxidative stress in neuropsychiatric disorders. It is thought that elevated oxidative stress as well as neuroinflammation plays a part in the emergence of neuropsychiatric disorders. Including two linked with membranes and four with subunits of cytosol, NOX is a complex of multiple subunits. NOX has been linked to a significant source of reactive oxygen species in the brain. NOX has been shown to control memory processing and neural signaling. However, excessive NOX production has been linked to cardiovascular disorders, CNS degeneration, and neurotoxicity. The increase in NOX leads to the progression of neuropsychiatric disorders.

RESULT

Our review mainly emphasized the characteristics of NOX and its various mechanisms, the modulation of NOX in various neuropsychiatric disorders, and various studies supporting the fact that NOX might be the potential therapeutic target for neuropsychiatric disorders.

CONCLUSION

Here, we summarizes various pharmacological studies involving NOX inhibitors in neuropsychiatric disorders.

Vasodilators mobilize SK3 channels in endothelial cells to produce arterial relaxation

Endothelial cells (ECs) line the lumen of all blood vessels and regulate functions, including contractility. Physiological stimuli, such as acetylcholine (ACh) and intravascular flow, activate transient receptor potential vanilloid 4 (TRPV4) channels, which stimulate small (SK3)- and intermediate (IK)-conductance Ca2+-activated potassium channels in ECs to produce vasodilation. Whether physiological vasodilators also modulate the surface abundance of these ion channels in ECs to elicit functional responses is unclear. Here, we show that ACh and intravascular flow stimulate rapid anterograde trafficking of an intracellular pool of SK3 channels in ECs of resistance-size arteries, which increases surface SK3 protein more than two-fold. In contrast, ACh and flow do not alter the surface abundance of IK or TRPV4 channels. ACh triggers SK3 channel trafficking by activating TRPV4-mediated Ca2+ influx, which stimulates Rab11A, a Rab GTPase associated with recycling endosomes. Superresolution microscopy data demonstrate that SK3 trafficking specifically increases the size of surface SK3 clusters which overlap with TRPV4 clusters. We also show that Rab11A-dependent trafficking of SK3 channels is an essential contributor to vasodilator-induced SK current activation in ECs and vasorelaxation. In summary, our data demonstrate that vasodilators activate Rab11A, which rapidly delivers an intracellular pool of SK3 channels to the vicinity of surface TRPV4 channels in ECs. This trafficking mechanism increases surface SK3 cluster size, elevates SK3 current density, and produces vasodilation. These data also demonstrate that SK3 and IK channels are differentially regulated by trafficking-dependent and -independent signaling mechanisms in endothelial cells.

The astrocytic TRPA1 channel mediates an intrinsic protective response to vascular cognitive impairment via LIF production

Vascular cognitive impairment (VCI) refers to cognitive alterations caused by vascular disease, which is associated with various types of dementia. Because chronic cerebral hypoperfusion (CCH) induces VCI, we used bilateral common carotid artery stenosis (BCAS) mice as a CCH-induced VCI model. Transient receptor potential ankyrin 1 (TRPA1), the most redox-sensitive TRP channel, is functionally expressed in the brain. Here, we investigated the pathophysiological role of TRPA1 in CCH-induced VCI. During early-stage CCH, cognitive impairment and white matter injury were induced by BCAS in TRPA1-knockout but not wild-type mice. TRPA1 stimulation with cinnamaldehyde ameliorated BCAS-induced outcomes. RNA sequencing analysis revealed that BCAS increased leukemia inhibitory factor (LIF) in astrocytes. Moreover, hydrogen peroxide-treated TRPA1-stimulated primary astrocyte cultures expressed LIF, and culture medium derived from these cells promoted oligodendrocyte precursor cell myelination. Overall, TRPA1 in astrocytes prevents CCH-induced VCI through LIF production. Therefore, TRPA1 stimulation may be a promising therapeutic approach for VCI.

Transient receptor potential ankyrin 1 (TRPA1) mediates reactive oxygen species-induced Ca2+ entry, mitochondrial dysfunction, and caspase-3/7 activation in primary cultures of metastatic colorectal carcinoma cells

Colorectal carcinoma (CRC) represents the fourth most common cancer worldwide and is the third most common cause of malignancy-associated mortality. Distant metastases to the liver and lungs are the main drivers of CRC-dependent death. Pro-oxidant therapies, which halt disease progression by exacerbating oxidative stress, represent an antitumour strategy that is currently exploited by chemotherapy and ionizing radiation. A more selective strategy to therapeutically exploit reactive oxygen species (ROS) signaling would consist in targeting a redox sensor that is up-regulated in metastatic cells and is tightly coupled to the stimulation of cancer cell death programs. The non-selective cation channel, Transient Receptor Potential Ankyrin 1 (TRPA1), serves as a sensor of the cellular redox state, being activated to promote extracellular Ca²⁺ entry by an increase in oxidative stress. Recent work demonstrated that TRPA1 channel protein is up-regulated in several cancer types and that TRPA1-mediated Ca²⁺ signals can either engage an antiapoptotic pro-survival signaling pathway or to promote mitochondrial Ca²⁺ dysfunction and apoptosis. Herein, we sought to assess for the first time the outcome of TRPA1 activation by ROS on primary cultures of metastatic colorectal carcinoma (mCRC cells). We found that TRPA1 channel protein is up-regulated and mediates enhanced hydrogen peroxide (H₂O₂)-induced Ca²⁺ entry in mCRC cells as compared to non-neoplastic control cells. The lipid peroxidation product 4-hydroxynonenal (4-HNE) is the main ROS responsible for TRPA1 activation upon mCRC cell exposure to oxidative stress. TRPA1-mediated Ca²⁺ entry in response to H₂O₂ and 4-HNE results in mitochondrial Ca²⁺ overload, followed by mitochondrial depolarization and caspase-3/7 activation. Therefore, targeting TRPA1 could represent an alternative strategy to eradicate metastatic CRC by enhancing its sensitivity to oxidative stress.

Allyl Isothiocianate Induces Ca2+ Signals and Nitric Oxide Release by Inducing Reactive Oxygen Species Production in the Human Cerebrovascular Endothelial Cell Line hCMEC/D3

Nitric oxide (NO) represents a crucial mediator to regulate cerebral blood flow (CBF) in the human brain both under basal conditions and in response to somatosensory stimulation. An increase in intracellular Ca2+ concentrations ([Ca2+]i) stimulates the endothelial NO synthase to produce NO in human cerebrovascular endothelial cells. Therefore, targeting the endothelial ion channel machinery could represent a promising strategy to rescue endothelial NO signalling in traumatic brain injury and neurodegenerative disorders. Allyl isothiocyanate (AITC), a major active constituent of cruciferous vegetables, was found to increase CBF in non-human preclinical models, but it is still unknown whether it stimulates NO release in human brain capillary endothelial cells. In the present investigation, we showed that AITC evoked a Ca2+-dependent NO release in the human cerebrovascular endothelial cell line, hCMEC/D3. The Ca2+ response to AITC was shaped by both intra- and extracellular Ca2+ sources, although it was insensitive to the pharmacological blockade of transient receptor potential ankyrin 1, which is regarded to be among the main molecular targets of AITC. In accord, AITC failed to induce transmembrane currents or to elicit membrane hyperpolarization, although NS309, a selective opener of the small- and intermediate-conductance Ca2+-activated K+ channels, induced a significant membrane hyperpolarization. The AITC-evoked Ca2+ signal was triggered by the production of cytosolic, but not mitochondrial, reactive oxygen species (ROS), and was supported by store-operated Ca2+ entry (SOCE). Conversely, the Ca2+ response to AITC did not require Ca2+ mobilization from the endoplasmic reticulum, lysosomes or mitochondria. However, pharmacological manipulation revealed that AITC-dependent ROS generation inhibited plasma membrane Ca2+-ATPase (PMCA) activity, thereby attenuating Ca2+ removal across the plasma membrane and resulting in a sustained increase in [Ca2+]i. In accord, the AITC-evoked NO release was driven by ROS generation and required ROS-dependent inhibition of PMCA activity. These data suggest that AITC could be exploited to restore NO signalling and restore CBF in brain disorders that feature neurovascular dysfunction.

Vasodilators activate TMEM16A channels in endothelial cells to reduce blood pressure

Endothelial cells (ECs) regulate vascular contractility to control regional organ blood flow and systemic blood pressure. Several cation channels are expressed in ECs which regulate arterial contractility. In contrast, the molecular identity and physiological functions of anion channels in ECs is unclear. Here, we generated tamoxifen-inducible, EC-specific TMEM16A knockout ( TMEM16A ecKO) mice to investigate the functional significance of this chloride (Cl - ) channel in the resistance vasculature. Our data demonstrate that TMEM16A channels generate calcium-activated Cl - currents in ECs of control ( TMEM16A fl/fl ) mice that are absent in ECs of TMEM16A ecKO mice. Acetylcholine (ACh), a muscarinic receptor agonist, and GSK101, a TRPV4 agonist, activate TMEM16A currents in ECs. Single molecule localization microscopy data indicate that surface TMEM16A and TRPV4 clusters locate in very close nanoscale proximity, with ∼18% exhibiting overlap in ECs. ACh stimulates TMEM16A currents by activating Ca 2+ influx through surface TRPV4 channels without altering the size or density of TMEM16A or TRPV4 surface clusters, their spatial proximity or colocalization. ACh-induced activation of TMEM16A channels in ECs produces hyperpolarization in pressurized arteries. ACh, GSK101 and intraluminal ATP, another vasodilator, all dilate pressurized arteries through TMEM16A channel activation in ECs. Furthermore, EC-specific knockout of TMEM16A channels elevates systemic blood pressure in conscious mice. In summary, these data indicate that vasodilators stimulate TRPV4 channels, leading to Ca 2+ -dependent activation of nearby TMEM16A channels in ECs to produce arterial hyperpolarization, vasodilation and a reduction in blood pressure. We identify TMEM16A as an anion channel present in ECs that regulates arterial contractility and blood pressure.

One sentence summary

Vasodilators stimulate TRPV4 channels, leading to calcium-dependent activation of nearby TMEM16A channels in ECs to produce arterial hyperpolarization, vasodilation and a reduction in blood pressure.

Transient receptor potential Ankyrin-1 (TRPA1) agonists suppress myelination and induce demyelination in organotypic cortical slices

Oligodendrocytes are highly specialized glial cells characterized by their production of multilayer myelin sheaths that wrap axons to speed up action potential propagation. It is due to their specific role in supporting axons that impairment of myelin structure and function leads to debilitating symptoms in a wide range of degenerative diseases, including Multiple Sclerosis and Leukodystrophies. It is known that myelin damage can be receptor-mediated and recently oligodendrocytes have been shown to express Ca2+ -permeable Transient Receptor Potential Ankyrin-1 (TRPA1) channels, whose activation can result in myelin damage in ischemia. Here, we show, using organotypic cortical slice cultures, that TRPA1 activation, by TRPA1 agonists JT010 and Carvacrol for varying lengths of time, induces myelin damage. Although TRPA1 activation does not appear to affect oligodendrocyte progenitor cell number or proliferation, it prevents myelin formation and after myelination causes internodal shrinking and significant myelin degradation. This does not occur when the TRPA1 antagonist, A967079, is also applied. Of note is that when TRPA1 agonists are applied for either 24 h, 3 days or 7 days, axon integrity appears to be preserved while mature myelinated oligodendrocytes remain but with significantly shortened internodes. These results provide further evidence that TRPA1 inhibition could be protective in demyelination diseases and a promising therapy to prevent demyelination and promote remyelination.

Calcium signaling in chemotherapy-induced neuropathy

Alterations in calcium (Ca²⁺) signaling is a major mechanism in the development of chemotherapy-induced peripheral neuropathy (CIPN), a side effect caused by multiple chemotherapy regimens. CIPN is associated with numbness and incessant tingling in hands and feet which diminishes quality of life during treatment. In up to 50% of survivors, CIPN is essentially irreversible. There are no approved, disease-modifying treatments for CIPN. The only recourse for oncologists is to modify the chemotherapy dose, a situation that can compromise optimal chemotherapy and impact patient outcomes. Here we focus on taxanes and other chemotherapeutic agents that work by altering microtubule assemblies to kill cancer cells, but also have off-target toxicities. There have been many molecular mechanisms proposed to explain the effects of microtubule-disrupting drugs. In neurons, an initiating step in the off-target effects of treatment by taxane is binding to neuronal calcium sensor 1 (NCS1), a sensitive Ca²⁺ sensor protein that maintains the resting Ca²⁺ concentration and dynamically enhances responses to cellular stimuli. The taxane/NCS1 interaction causes a Ca²⁺ surge that starts a pathophysiological cascade of consequences. This same mechanism contributes to other conditions including chemotherapy-induced cognitive impairment. Strategies to prevent the Ca²⁺ surge are the foundation of current work.

Transient Receptor Potential Ankyrin 1 (TRPA1) Channel as a Sensor of Oxidative Stress in Cancer Cells

Moderate levels of reactive oxygen species (ROS), such as hydrogen peroxide (H₂O₂), fuel tumor metastasis and invasion in a variety of cancer types. Conversely, excessive ROS levels can impair tumor growth and metastasis by triggering cancer cell death. In order to cope with the oxidative stress imposed by the tumor microenvironment, malignant cells exploit a sophisticated network of antioxidant defense mechanisms. Targeting the antioxidant capacity of cancer cells or enhancing their sensitivity to ROS-dependent cell death represent a promising strategy for alternative anticancer treatments. Transient Receptor Potential Ankyrin 1 (TRPA1) is a redox-sensitive non-selective cation channel that mediates extracellular Ca²⁺ entry upon an increase in intracellular ROS levels. The ensuing increase in intracellular Ca²⁺ concentration can in turn engage a non-canonical antioxidant defense program or induce mitochondrial Ca²⁺ dysfunction and apoptotic cell death depending on the cancer type. Herein, we sought to describe the opposing effects of ROS-dependent TRPA1 activation on cancer cell fate and propose the pharmacological manipulation of TRPA1 as an alternative therapeutic strategy to enhance cancer cell sensitivity to oxidative stress.

Vascular mechanotransduction

This review aims to survey the current state of mechanotransduction in vascular smooth muscle cells (VSMCs) and endothelial cells (ECs), including their sensing of mechanical stimuli and transduction of mechanical signals that result in the acute functional modulation and longer-term transcriptomic and epigenetic regulation of blood vessels. The mechanosensors discussed include ion channels, plasma membrane-associated structures and receptors, and junction proteins. The mechanosignaling pathways presented include the cytoskeleton, integrins, extracellular matrix, and intracellular signaling molecules. These are followed by discussions on mechanical regulation of transcriptome and epigenetics, relevance of mechanotransduction to health and disease, and interactions between VSMCs and ECs. Throughout this review, we offer suggestions for specific topics that require further understanding. In the closing section on conclusions and perspectives, we summarize what is known and point out the need to treat the vasculature as a system, including not only VSMCs and ECs but also the extracellular matrix and other types of cells such as resident macrophages and pericytes, so that we can fully understand the physiology and pathophysiology of the blood vessel as a whole, thus enhancing the comprehension, diagnosis, treatment, and prevention of vascular diseases.

TRPA1 as a O2 sensor detects microenvironmental hypoxia in the mice anterior cingulate cortex

Transient receptor potential ankyrin 1 (TRPA1) is a member of the TRP channel family and is expressed in peripheral and central nervous systems. In the periphery, TRPA1 senses cold and pain. However, the functions of TRPA1 in the CNS are unclear. Here, we examined the roles of TRPA1 on neural activity and synaptic transmission in layer II/III pyramidal neurons from mice anterior cingulate cortex (ACC) by whole-cell patch-clamp recordings. The activation of Cinnamaldehyde (CA), which is TRPA1 agonist produced inward currents and these were blocked by the TRPA1 antagonists. Furthermore, activating TRPA1 changed the properties of action potentials such as the firing rate, rise time and decay time. In contrast, stimulating TRPA1 did not alter the spontaneous synaptic transmission. Finally, we examined the functional role of TRPA1 on neurons in a hypoxic environment. We induced an acute hypoxia by substituting nitrogen (N₂) gas for oxygen (O₂) in the external solution. N₂ produced biphasic effects that consisting of inward currents in the early phase and outward currents in the late phase. Importantly, blocking TRPA1 reduced inward currents, but not outward currents. In contrast, a K_ATP channel blocker completely inhibited outward currents. These results suggest that TRPA1 acts on postsynaptic neurons in the ACC as an acute O₂ sensor.

Flipping Off and On the Redox Switch in the Microcirculation

Resistance arteries and arterioles evolved as specialized blood vessels serving two important functions: (a) regulating peripheral vascular resistance and blood pressure and (b) matching oxygen and nutrient delivery to metabolic demands of organs. These functions require control of vessel lumen cross-sectional area (vascular tone) via coordinated vascular cell responses governed by precise spatial-temporal communication between intracellular signaling pathways. Herein, we provide a contemporary overview of the significant roles that redox switches play in calcium signaling for orchestrated endothelial, smooth muscle, and red blood cell control of arterial vascular tone. Three interrelated themes are the focus: (a) smooth muscle to endothelial communication for vasoconstriction, (b) endothelial to smooth muscle cell cross talk for vasodilation, and (c) oxygen and red blood cell interregulation of vascular tone and blood flow. We intend for this thematic framework to highlight gaps in our current knowledge and potentially spark interest for cross-disciplinary studies moving forward.

Endothelial cell TRPA1 activity exacerbates cerebral hemorrhage during severe hypertension

Introduction: Hypoxia-induced dilation of cerebral arteries orchestrated by Ca2+-permeable transient receptor potential ankyrin 1 (TRPA1) cation channels on endothelial cells is neuroprotective during ischemic stroke, but it is unknown if the channel has a similar impact during hemorrhagic stroke. TRPA1 channels are endogenously activated by lipid peroxide metabolites generated by reactive oxygen species (ROS). Uncontrolled hypertension, a primary risk factor for the development of hemorrhagic stroke, is associated with increased ROS production and oxidative stress. Therefore, we hypothesized that TRPA1 channel activity is increased during hemorrhagic stroke. Methods: Severe, chronic hypertension was induced in control (Trpa1 fl/fl) and endothelial cell-specific TRPA1 knockout (Trpa1-ecKO) mice using a combination of chronic angiotensin II administration, a high-salt diet, and the addition of a nitric oxide synthase inhibitor to drinking water. Blood pressure was measured in awake, freely-moving mice using surgically placed radiotelemetry transmitters. TRPA1-dependent cerebral artery dilation was evaluated with pressure myography, and expression of TRPA1 and NADPH oxidase (NOX) isoforms in arteries from both groups was determined using PCR and Western blotting techniques. In addition, ROS generation capacity was evaluated using a lucigenin assay. Histology was performed to examine intracerebral hemorrhage lesion size and location. Results: All animals became hypertensive, and a majority developed intracerebral hemorrhages or died of unknown causes. Baseline blood pressure and responses to the hypertensive stimulus did not differ between groups. Expression of TRPA1 in cerebral arteries from control mice was not altered after 28 days of treatment, but expression of three NOX isoforms and the capacity for ROS generation was increased in hypertensive animals. NOX-dependent activation of TRPA1 channels dilated cerebral arteries from hypertensive animals to a greater extent compared with controls. The number of intracerebral hemorrhage lesions in hypertensive animals did not differ between control and Trpa1-ecKO animals but were significantly smaller in Trpa1-ecKO mice. Morbidity and mortality did not differ between groups. Discussion: We conclude that endothelial cell TRPA1 channel activity increases cerebral blood flow during hypertension resulting in increased extravasation of blood during intracerebral hemorrhage events; however, this effect does not impact overall survival. Our data suggest that blocking TRPA1 channels may not be helpful for treating hypertension-associated hemorrhagic stroke in a clinical setting.

Endothelial IK and SK channel activation decreases pulmonary arterial pressure and vascular remodeling in pulmonary hypertension

Endothelial cells (ECs) from small pulmonary arteries (PAs) release nitric oxide (NO) and prostacyclin, which lower pulmonary arterial pressure (PAP). In pulmonary hypertension (PH), the levels of endothelium-derived NO and prostacyclin are reduced, contributing to elevated PAP. Small-and intermediate-conductance Ca²⁺-activated K⁺ channels (IK and SK)-additional crucial endothelial mediators of vasodilation-are also present in small PAs, but their function has not been investigated in PH. We hypothesized that endothelial IK and SK channels can be targeted to lower PAP in PH. Whole-cell patch-clamp experiments showed functional IK and SK channels in ECs, but not smooth muscle cells, from small PAs. Using a SU5416 plus chronic hypoxia (Su + CH) mouse model of PH, we found that currents through EC IK and SK channels were unchanged compared with those from normal mice. Moreover, IK/SK channel-mediated dilation of small PAs was preserved in Su + CH mice. Consistent with previous reports, endothelial NO levels and NO-mediated dilation were reduced in small PAs from Su + CH mice. Notably, acute treatment with IK/SK channel activators decreased PAP in Su + CH mice but not in normal mice. Further, chronic activation of IK/SK channels decreased PA remodeling and right ventricular hypertrophy, which are pathological hallmarks of PH, in Su + CH mice. Collectively, our data provide the first evidence that, unlike endothelial NO release, IK/SK channel activity is not altered in PH. Our results also demonstrate proof of principle that IK/SK channel activation can be used as a strategy for lowering PAP in PH.

The role of endothelial TRP channels in age-related vascular cognitive impairment and dementia

Transient receptor potential (TRP) proteins are part of a superfamily of polymodal cation channels that can be activated by mechanical, physical, and chemical stimuli. In the vascular endothelium, TRP channels regulate two fundamental parameters: the membrane potential and the intracellular Ca²⁺ concentration [(Ca²⁺)_i]. TRP channels are widely expressed in the cerebrovascular endothelium, and are emerging as important mediators of several brain microvascular functions (e.g., neurovascular coupling, endothelial function, and blood-brain barrier permeability), which become impaired with aging. Aging is the most significant risk factor for vascular cognitive impairment (VCI), and the number of individuals affected by VCI is expected to exponentially increase in the coming decades. Yet, there are currently no preventative or therapeutic treatments available against the development and progression of VCI. In this review, we discuss the involvement of endothelial TRP channels in diverse physiological processes in the brain as well as in the pathogenesis of age-related VCI to explore future potential neuroprotective strategies.

Paclitaxel Regulates TRPA1 Function and Expression Through PKA and PKC

Paclitaxel (PTX) is a frequently used anticancer drug that causes peripheral neuropathy. Transient receptor potential ankyrin 1 (TRPA1), a plasma membrane calcium channel, has been associated with PTX toxicity and with other chemotherapy agents such as oxaliplatin and vincristine. However, the effect of PTX on the functional expression and calcium currents of TRPA1 has not been determined. The present study shows the effect of PTX on TRPA1 activity in a neuronal cell line (SH-SY5Y). The effect of PTX on the expression of TRPA1 was assessed through quantitative PCR and Western blot analyses to determine the relative mRNA and protein expression levels. To assess the effect on calcium flux and currents, cells were exposed to PTX; simultaneously, a specific agonist and antagonist of TRPA1 were added to evaluate the differential response in exposed versus control cells. To assess the effect of PKA, PKC and PI3K on PTX-induced TRPA1 increased activity, selective inhibitors were added to these previous experiments. PTX increased the mRNA and protein expression of TRPA1 as well as the TRPA1-mediated Ca2+ currents and intracellular Ca2+ concentrations. This effect was dependent on AITC (a selective specific agonist) and was abolished with HC-030031 (a selective specific antagonist). The inhibition of PKA and PKC reduced the effect of PTX on the functional expression of TRPA1, whereas the inhibition of PI3K had no effects. PTX-induced neuropathy involves TRPA1 activity through an increase in functional expression and is regulated by PKA and PKC signaling. These findings support the role of the TRPA1 channel in the mechanisms altered by PTX, which can be involved in the process that lead to chemotherapy-induced neuropathy.

Inflammation-the role of TRPA1 channel

Recently, increasing numbers of studies have demonstrated that transient receptor potential ankyrin 1 (TRPA1) can be used as a potential target for the treatment of inflammatory diseases. TRPA1 is expressed in both neuronal and non-neuronal cells and is involved in diverse physiological activities, such as stabilizing of cell membrane potential, maintaining cellular humoral balance, and regulating intercellular signal transduction. TRPA1 is a multi-modal cell membrane receptor that can sense different stimuli, and generate action potential signals after activation via osmotic pressure, temperature, and inflammatory factors. In this study, we introduced the latest research progress on TRPA1 in inflammatory diseases from three different aspects. First, the inflammatory factors released after inflammation interacts with TRPA1 to promote inflammatory response; second, TRPA1 regulates the function of immune cells such as macrophages and T cells, In addition, it has anti-inflammatory and antioxidant effects in some inflammatory diseases. Third, we have summarized the application of antagonists and agonists targeting TRPA1 in the treatment of some inflammatory diseases.

TRPA1 Polymorphisms Modify the Hypotensive Responses to Propofol with No Change in Nitrite or Nitrate Levels

Anesthesia with propofol is frequently associated with hypotension. The TRPA1 gene contributes to the vasodilator effect of propofol. Hypotension is crucial for anesthesiologists because it is deleterious in the perioperative period. We tested whether the TRPA1 gene polymorphisms or haplotypes interfere with the hypotensive responses to propofol. PCR-determined genotypes and haplotype frequencies were estimated. Nitrite, nitrates, and NOx levels were measured. Propofol induced a more expressive lowering of the blood pressure (BP) without changing nitrite or nitrate levels in patients carrying CG+GG genotypes for the rs16937976 TRPA1 polymorphism and AG+AA genotypes for the rs13218757 TRPA1 polymorphism. The CGA haplotype presented the most remarkable drop in BP. Heart rate values were not impacted. The present exploratory analysis suggests that TRPA1 genotypes and haplotypes influence the hypotensive responses to propofol. The mechanisms involved are probably other than those related to NO bioavailability. With better genetic knowledge, planning anesthesia with fewer side effects may be possible.

ThermoTRP channels in pain sexual dimorphism: new insights for drug intervention

Chronic pain is a major burden for the society and remains more prevalent and severe in females. The presence of chronic pain is linked to persistent alterations in the peripheral and the central nervous system. One of the main types of peripheral pain transducers are the transient receptor potential channels (TRP), also known as thermoTRP channels, which intervene in the perception of hot and cold external stimuli. These channels, and especially TRPV1, TRPA1 and TRPM8, have been subjected to profound investigation because of their role as thermosensors and also because of their implication in acute and chronic pain. Surprisingly, their sensitivity to endogenous signaling has been far less studied. Cumulative evidence suggests that the function of these channels may be differently modulated in males and females, in part through sexual hormones, and this could constitute a significant contributor to the sex differences in chronic pain. Here, we review the exciting advances in thermoTRP pharmacology for males and females in two paradigmatic types of chronic pain with a strong peripheral component: chronic migraine and chemotherapy-induced peripheral neuropathy (CIPN). The possibilities of peripheral druggability offered by these channels and the differential exploitation for men and women represent a development opportunity that will lead to a significant increment of the armamentarium of analgesic medicines for personalized chronic pain treatment.

Cell-To-Cell Communication in the Resistance Vasculature

The arterial vasculature can be divided into large conduit arteries, intermediate contractile arteries, resistance arteries, arterioles, and capillaries. Resistance arteries and arterioles primarily function to control systemic blood pressure. The resistance arteries are composed of a layer of endothelial cells oriented parallel to the direction of blood flow, which are separated by a matrix layer termed the internal elastic lamina from several layers of smooth muscle cells oriented perpendicular to the direction of blood flow. Cells within the vessel walls communicate in a homocellular and heterocellular fashion to govern luminal diameter, arterial resistance, and blood pressure. At rest, potassium currents govern the basal state of endothelial and smooth muscle cells. Multiple stimuli can elicit rises in intracellular calcium levels in either endothelial cells or smooth muscle cells, sourced from intracellular stores such as the endoplasmic reticulum or the extracellular space. In general, activation of endothelial cells results in the production of a vasodilatory signal, usually in the form of nitric oxide or endothelial-derived hyperpolarization. Conversely, activation of smooth muscle cells results in a vasoconstriction response through smooth muscle cell contraction. © 2022 American Physiological Society. Compr Physiol 12: 1-35, 2022.

Endothelial Cells and the Cerebral Circulation

Endothelial cells form the innermost layer of all blood vessels and are the only vascular component that remains throughout all vascular segments. The cerebral vasculature has several unique properties not found in the peripheral circulation; this requires that the cerebral endothelium be considered as a unique entity. Cerebral endothelial cells perform several functions vital for brain health. The cerebral vasculature is responsible for protecting the brain from external threats carried in the blood. The endothelial cells are central to this requirement as they form the basis of the blood-brain barrier. The endothelium also regulates fibrinolysis, thrombosis, platelet activation, vascular permeability, metabolism, catabolism, inflammation, and white cell trafficking. Endothelial cells regulate the changes in vascular structure caused by angiogenesis and artery remodeling. Further, the endothelium contributes to vascular tone, allowing proper perfusion of the brain which has high energy demands and no energy stores. In this article, we discuss the basic anatomy and physiology of the cerebral endothelium. Where appropriate, we discuss the detrimental effects of high blood pressure on the cerebral endothelium and the contribution of cerebrovascular disease endothelial dysfunction and dementia. © 2022 American Physiological Society. Compr Physiol 12:3449-3508, 2022.

GCN5 contributes to intracellular lipid accumulation in human primary cardiac stromal cells from patients affected by Arrhythmogenic cardiomyopathy

Arrhythmogenic cardiomyopathy (ACM) is a genetic disease associated with sudden cardiac death and cardiac fibro‐fatty replacement. Over the last years, several works have demonstrated that different epigenetic enzymes can affect not only gene expression changes in cardiac diseases but also cellular metabolism. Specifically, the histone acetyltransferase GCN5 is known to facilitate adipogenesis and modulate cardiac metabolism in heart failure. Our group previously demonstrated that human primary cardiac stromal cells (CStCs) contribute to adipogenesis in the ACM pathology. Thus, this study aims to evaluate the role of GCN5 in ACM intracellular lipid accumulation. To do so, CStCs were obtained from right ventricle biopsies of ACM patients and from samples of healthy cadaveric donors (CTR). GCN5 expression was increased both in ex vivo and in vitro ACM samples compared to CTR. When GCN5 expression was silenced or pharmacologically inhibited by the administration of MB‐3, we observed a reduction in lipid accumulation and a mitigation of reactive oxygen species (ROS) production in ACM CStCs. In agreement, transcriptome analysis revealed that the presence of MB‐3 modified the expression of pathways related to cellular redox balance. Altogether, our findings suggest that GCN5 inhibition reduces fat accumulation in ACM CStCs, partially by modulating intracellular redox balance pathways.

TRPA1 Role in Inflammatory Disorders: What Is Known So Far?

The transient receptor potential ankyrin 1 (TRPA1), a member of the TRP superfamily of channels, is primarily localized in a subpopulation of primary sensory neurons of the trigeminal, vagal, and dorsal root ganglia, where its activation mediates neurogenic inflammatory responses. TRPA1 expression in resident tissue cells, inflammatory, and immune cells, through the indirect modulation of a large series of intracellular pathways, orchestrates a range of cellular processes, such as cytokine production, cell differentiation, and cytotoxicity. Therefore, the TRPA1 pathway has been proposed as a protective mechanism to detect and respond to harmful agents in various pathological conditions, including several inflammatory diseases. Specific attention has been paid to TRPA1 contribution to the transition of inflammation and immune responses from an early defensive response to a chronic pathological condition. In this view, TRPA1 antagonists may be regarded as beneficial tools for the treatment of inflammatory conditions.

An Overview of the TRP-Oxidative Stress Axis in Metabolic Syndrome: Insights for Novel Therapeutic Approaches

Metabolic syndrome (MS) is a complex pathology characterized by visceral adiposity, insulin resistance, arterial hypertension, and dyslipidaemia. It has become a global epidemic associated with increased consumption of high-calorie, low-fibre food and sedentary habits. Some of its underlying mechanisms have been identified, with hypoadiponectinemia, inflammation and oxidative stress as important factors for MS establishment and progression. Alterations in adipokine levels may favour glucotoxicity and lipotoxicity which, in turn, contribute to inflammation and cellular stress responses within the adipose, pancreatic and liver tissues, in addition to hepatic steatosis. The multiple mechanisms of MS make its clinical management difficult, involving both non-pharmacological and pharmacological interventions. Transient receptor potential (TRP) channels are non-selective calcium channels involved in a plethora of physiological events, including energy balance, inflammation and oxidative stress. Evidence from animal models of disease has contributed to identify their specific contributions to MS and may help to tailor clinical trials for the disease. In this context, the oxidative stress sensors TRPV1, TRPA1 and TRPC5, play major roles in regulating inflammatory responses, thermogenesis and energy expenditure. Here, the interplay between these TRP channels and oxidative stress in MS is discussed in the light of novel therapies to treat this syndrome.

Photothermal Conjugated Polymer Nanoparticles for Suppressing Breast Tumor Growth by Regulating TRPA1 Ion Channels

Cancer cells survive by relying on oxidative stress defense against the accumulation of reactive oxygen species (ROS) during tumor formation. ROS-sensitive TRPA1 ion channels are overexpressed in breast cancer cells and induce a large influx of Ca²⁺ which upregulates the anti-apoptotic pathway to lead breast cancer cells to produce oxidative stress defense and enhance the resistance to ROS related chemotherapy. Targeting and inhibiting the TRPA1 ion channels are critical for breaking down the oxidative stress defense system and overcoming cellular resistance. Here, near-infrared (NIR) light-responsive conjugated polymer nanoparticles are designed and prepared to promote apoptosis of breast cancer cells, reduce cell drug resistance and suppress tumor growth through the remote and precise regulation of TRPA1 ion channels. Upon 808 nm laser irradiation, the nanoparticles block the formation of Ca²⁺ /CaM complex and regulate the content of MCL-1 protein. Especially, the nanoparticles overcome drug resistance of cancer cells, therefore accelerating apoptosis of cancer cells and suppressing tumor growth in mice. Compared with carboplatin, the volume of tumor induced by NPs-H decreases by 54.1%. This work provides a strategy to disrupt the oxidative stress defense system and downregulate the antiapoptotic signaling pathway in cancer cells.

Endothelial Ion Channels and Cell-Cell Communication in the Microcirculation

Endothelial cells in resistance arteries, arterioles, and capillaries express a diverse array of ion channels that contribute to Cell-Cell communication in the microcirculation. Endothelial cells are tightly electrically coupled to their neighboring endothelial cells by gap junctions allowing ion channel-induced changes in membrane potential to be conducted for considerable distances along the endothelial cell tube that lines arterioles and forms capillaries. In addition, endothelial cells may be electrically coupled to overlying smooth muscle cells in arterioles and to pericytes in capillaries via heterocellular gap junctions allowing electrical signals generated by endothelial cell ion channels to be transmitted to overlying mural cells to affect smooth muscle or pericyte contractile activity. Arteriolar endothelial cells express inositol 1,4,5 trisphosphate receptors (IP₃Rs) and transient receptor vanilloid family member 4 (TRPV4) channels that contribute to agonist-induced endothelial Ca²⁺ signals. These Ca²⁺ signals then activate intermediate and small conductance Ca²⁺-activated K⁺ (IK_Ca and SK_Ca) channels causing vasodilator-induced endothelial hyperpolarization. This hyperpolarization can be conducted along the endothelium via homocellular gap junctions and transmitted to overlying smooth muscle cells through heterocellular gap junctions to control the activity of voltage-gated Ca²⁺ channels and smooth muscle or pericyte contraction. The IK_Ca- and SK_Ca-induced hyperpolarization may be amplified by activation of inward rectifier K⁺ (K_IR) channels. Endothelial cell IP₃R- and TRPV4-mediated Ca²⁺ signals also control the production of endothelial cell vasodilator autacoids, such as NO, PGI₂, and epoxides of arachidonic acid contributing to control of overlying vascular smooth muscle contractile activity. Cerebral capillary endothelial cells lack IK_Ca and SK_Ca but express K_IR channels, IP₃R, TRPV4, and other Ca²⁺ permeable channels allowing capillary-to-arteriole signaling via hyperpolarization and Ca²⁺. This allows parenchymal cell signals to be detected in capillaries and signaled to upstream arterioles to control blood flow to capillaries by active parenchymal cells. Thus, endothelial cell ion channels importantly participate in several forms of Cell-Cell communication in the microcirculation that contribute to microcirculatory function and homeostasis.

Amyloid-β disrupts unitary calcium entry through endothelial NMDA receptors in mouse cerebral arteries

Transient increases in intracellular Ca2+ activate endothelium-dependent vasodilatory pathways. This process is impaired in cerebral amyloid angiopathy, where amyloid-β(1-40) accumulates around blood vessels. In neurons, amyloid-β impairs the Ca2+-permeable N-methyl-D-aspartate receptor (NMDAR), a mediator of endothelium-dependent dilation in arteries. We hypothesized that amyloid-β(1-40) reduces NMDAR-elicited Ca2+ signals in mouse cerebral artery endothelial cells, blunting dilation. Cerebral arteries isolated from 4-5 months-old, male and female cdh5:Gcamp8 mice were used for imaging of unitary Ca2+ influx through NMDAR (NMDAR sparklets) and intracellular Ca2+ transients. The NMDAR agonist NMDA (10 µmol/L) increased frequency of NMDAR sparklets and intracellular Ca2+ transients in endothelial cells; these effects were prevented by NMDAR antagonists D-AP5 and MK-801. Next, we tested if amyloid-β(1-40) impairs NMDAR-elicited Ca2+ transients. Cerebral arteries incubated with amyloid-β(1-40) (5 µmol/L) exhibited reduced NMDAR sparklets and intracellular Ca2+ transients. Lastly, we observed that NMDA-induced dilation of pial arteries is reduced by acute intraluminal amyloid-β(1-40), as well as in a mouse model of Alzheimer's disease, the 5x-FAD, linked to downregulation of Grin1 mRNA compared to wild-type littermates. These data suggest that endothelial NMDAR mediate dilation via Ca2+-dependent pathways, a process disrupted by amyloid-β(1-40) and impaired in 5x-FAD mice.

Mechanisms and Physiological Implications of Cooperative Gating of Ion Channels Clusters

Ion channels play a central role in the regulation of nearly every cellular process. Dating back to the classic 1952 Hodgkin-Huxley model of the generation of the action potential, ion channels have always been thought of as independent agents. A myriad of recent experimental findings exploiting advances in electrophysiology, structural biology, and imaging techniques, however, have posed a serious challenge to this long-held axiom as several classes of ion channels appear to open and close in a coordinated, cooperative manner. Ion channel cooperativity ranges from variable-sized oligomeric cooperative gating in voltage-gated, dihydropyridine-sensitive Ca_v1.2 and Ca_v1.3 channels to obligatory dimeric assembly and gating of voltage-gated Na_v1.5 channels. Potassium channels, transient receptor potential channels, hyperpolarization cyclic nucleotide-activated channels, ryanodine receptors (RyRs), and inositol trisphosphate receptors (IP₃Rs) have also been shown to gate cooperatively. The implications of cooperative gating of these ion channels range from fine tuning excitation-contraction coupling in muscle cells to regulating cardiac function and vascular tone, to modulation of action potential and conduction velocity in neurons and cardiac cells, and to control of pace-making activity in the heart. In this review, we discuss the mechanisms leading to cooperative gating of ion channels, their physiological consequences and how alterations in cooperative gating of ion channels may induce a range of clinically significant pathologies.

TRPA1 channel activation with cinnamaldehyde induces cutaneous vasodilation through NOS, but not COX and KCa channel, mechanisms in humans

ABSTRACT

Transient receptor potential ankyrin 1 (TRPA1) channel activation induces cutaneous vasodilation in humans in vivo. However, the mechanisms underlying this response remains equivocal. We hypothesized that nitric oxide (NO) synthase (NOS) and Ca2+ activated K+ (KCa) channels contribute to the TRPA1 channel-induced cutaneous vasodilation with no involvement of cyclooxygenase (COX). Cutaneous vascular conductance (CVC) in 9 healthy young adults was assessed at four dorsal forearm skin sites treated by intradermal microdialysis with either: 1) vehicle control (98% propylene glycol + 1.985% dimethyl sulfoxide + 0.015% lactated Ringer solution), 2) 10 mM L-NAME, a non-selective NOS inhibitor, 3) 10 mM ketorolac, a non-selective COX inhibitor, or 4) 50 mM tetraethylammonium, a non-selective KCa channel blocker. Cinnamaldehyde, a TRPA1 channel activator, was administered to each skin site in a dose-dependent manner (2.9, 8.8, 26 and 80 %, each lasting ≥30min). Administration of ≥8.8% cinnamaldehyde increased CVC from baseline at the vehicle control site by as much as 27.4% [95 % confidence interval of 5.3] (P<0.001). NOS inhibitor attenuated the cinnamaldehyde induced-increases in CVC at the 8.8, 26.0, and 80.0% concentrations relative to the vehicle control site (all P≤0.05). In contrast, both the COX inhibitor and KCa channel blockers did not attenuate the cinnamaldehyde induced-increases in CVC relative to the vehicle control site for all concentrations (all P≥0.130). We conclude that in human skin in vivo, NOS plays a role in modulating the regulation of cutaneous vasodilation in response to TRPA1 channel activation with no detectable contributions of COX and KCa channels.

Role of TRP ion channels in cerebral circulation and neurovascular communication

The dynamic regulation of blood flow is essential for meeting the high metabolic demands of the brain and maintaining brain function. Cerebral blood flow is regulated primarily by 1) the intrinsic mechanisms that determine vascular contractility and 2) signals from neurons and astrocytes that alter vascular contractility. Stimuli from neurons and astrocytes can also initiate a signaling cascade in the brain capillary endothelium to increase regional blood flow. Recent studies provide evidence that TRP channels in endothelial cells, smooth muscle cells, neurons, astrocytes, and perivascular nerves control cerebrovascular contractility and cerebral blood flow. TRP channels exert their functional effects either through cell membrane depolarization or by serving as a Ca2+ influx pathway. Endothelial cells and astrocytes also maintain the integrity of the blood-brain barrier. Both endothelial cells and astrocytes express TRP channels, and an increase in endothelial TRP channel activity has been linked with a disrupted endothelial barrier function. Therefore, TRP channels can play a potentially important role in regulating blood-brain barrier integrity. Here, we review the regulation of cerebrovascular contractility by TRP channels under healthy and disease conditions and their potential roles in maintaining blood-brain barrier function.

Conjugated polymers mediate intracellular Ca2+ signals in circulating endothelial colony forming cells through the reactive oxygen species-dependent activation of Transient Receptor Potential Vanilloid 1 (TRPV1)

Endothelial colony forming cells (ECFCs) represent the most suitable cellular substrate to induce revascularization of ischemic tissues. Recently, optical excitation of the light-sensitive conjugated polymer, regioregular Poly (3-hexyl-thiophene), rr-P3HT, was found to stimulate ECFC proliferation and tube formation by activating the non-selective cation channel, Transient Receptor Potential Vanilloid 1 (TRPV1). Herein, we adopted a multidisciplinary approach, ranging from intracellular Ca²⁺ imaging to pharmacological manipulation and genetic suppression of TRPV1 expression, to investigate the effects of photoexcitation on intracellular Ca²⁺ concentration ([Ca²⁺]_i) in circulating ECFCs plated on rr-P3HT thin films. Polymer-mediated optical excitation induced a long-lasting increase in [Ca²⁺]_i that could display an oscillatory pattern at shorter light stimuli. Pharmacological and genetic manipulation revealed that the Ca²⁺ response to light was triggered by extracellular Ca²⁺ entry through TRPV1, whose activation required the production of reactive oxygen species at the interface between rr-P3HT and the cell membrane. Light-induced TRPV1-mediated Ca²⁺ entry was able to evoke intracellular Ca²⁺ release from the endoplasmic reticulum through inositol-1,4,5-trisphosphate receptors, followed by store-operated Ca²⁺ entry on the plasma membrane. These data show that TRPV1 may serve as a decoder at the interface between rr-P3HT thin films and ECFCs to translate optical excitation in pro-angiogenic Ca²⁺ signals.

Transient receptor potential ankyrin 1 and calcium: Interactions and association with disease (Review)

Calcium (Ca²⁺) is an essential signaling molecule in all cells. It is involved in numerous fundamental functions, including cell life and death. Abnormal regulation of Ca²⁺ homeostasis may cause human diseases. Usually known as a member of the transient receptor potential (TRP) family, TRP ankyrin 1 (TRPA1) is the only member of the ankyrin subfamily identified in mammals so far and widely expressed in cells and tissues. As it is involved in numerous sensory disorders such as pain and pruritus, TRPA1 is a potential target for the treatment of neuropathy. The functions of TRP family members are closely related to Ca²⁺. TRPA1 has a high permeability to Ca²⁺, sodium and potassium ions as a non-selective cation channel and the Ca²⁺ influx mediated by TRPA1 is involved in a variety of biological processes. In the present review, research on the relationship between the TRPA1 channel and Ca²⁺ ions and their interaction in disease-associated processes was summarised. The therapeutic potential of the TRPA1 channel is highlighted, which is expected to become a novel direction for the prevention and treatment of health conditions such as cancer and neurodegenerative diseases.

Reactive Oxygen Species and Endothelial Ca2+ Signaling: Brothers in Arms or Partners in Crime?

An increase in intracellular Ca²⁺ concentration ([Ca²⁺]_i) controls virtually all endothelial cell functions and is, therefore, crucial to maintain cardiovascular homeostasis. An aberrant elevation in endothelial can indeed lead to severe cardiovascular disorders. Likewise, moderate amounts of reactive oxygen species (ROS) induce intracellular Ca²⁺ signals to regulate vascular functions, while excessive ROS production may exploit dysregulated Ca²⁺ dynamics to induce endothelial injury. Herein, we survey how ROS induce endothelial Ca²⁺ signals to regulate vascular functions and, vice versa, how aberrant ROS generation may exploit the Ca²⁺ handling machinery to promote endothelial dysfunction. ROS elicit endothelial Ca²⁺ signals by regulating inositol-1,4,5-trisphosphate receptors, sarco-endoplasmic reticulum Ca²⁺-ATPase 2B, two-pore channels, store-operated Ca²⁺ entry (SOCE), and multiple isoforms of transient receptor potential (TRP) channels. ROS-induced endothelial Ca²⁺ signals regulate endothelial permeability, angiogenesis, and generation of vasorelaxing mediators and can be exploited to induce therapeutic angiogenesis, rescue neurovascular coupling, and induce cancer regression. However, an increase in endothelial [Ca²⁺]_i induced by aberrant ROS formation may result in endothelial dysfunction, inflammatory diseases, metabolic disorders, and pulmonary artery hypertension. This information could pave the way to design alternative treatments to interfere with the life-threatening interconnection between endothelial ROS and Ca²⁺ signaling under multiple pathological conditions.

Transient Receptor Potential Ankyrin-1 (TRPA1) Block Protects against Loss of White Matter Function during Ischaemia in the Mouse Optic Nerve

Oligodendrocytes produce myelin, which provides insulation to axons and speeds up neuronal transmission. In ischaemic conditions, myelin is damaged, resulting in mental and physical disabilities. Recent evidence suggests that oligodendrocyte damage during ischaemia can be mediated by Transient Receptor Potential Ankyrin-1 (TRPA1), whose activation raises intracellular Ca²⁺ concentrations and damages compact myelin. Here, we show that TRPA1 is constitutively active in oligodendrocytes and the optic nerve, as the specific TRPA1 antagonist, A-967079, decreases basal oligodendrocyte Ca²⁺ concentrations and increases the size of the compound action potential (CAP). Conversely, TRPA1 agonists reduce the size of the optic nerve CAP in an A-967079-sensitive manner. These results indicate that glial TRPA1 regulates neuronal excitability in the white matter under physiological as well as pathological conditions. Importantly, we find that inhibition of TRPA1 prevents loss of CAPs during oxygen and glucose deprivation (OGD) and improves the recovery. TRPA1 block was effective when applied before, during, or after OGD, indicating that the TRPA1-mediated damage is occurring during both ischaemia and recovery, but importantly, that therapeutic intervention is possible after the ischaemic insult. These results indicate that TRPA1 has an important role in the brain, and that its block may be effective in treating many white matter diseases.

Satellite glial cells in sensory ganglia express functional transient receptor potential ankyrin 1 that is sensitized in neuropathic and inflammatory pain

Transient receptor potential ankyrin 1 (TRPA1) is well documented as an important molecule in pain hypersensitivity following inflammation and nerve injury and in many other cellular biological processes. Here, we show that TRPA1 is expressed not only by sensory neurons of the dorsal root ganglia (DRG) but also in their adjacent satellite glial cells (SGCs), as well as nonmyelinating Schwann cells. TRPA1 immunoreactivity is also detected in various cutaneous structures of sensory neuronal terminals, including small and large caliber cutaneous sensory fibers and endings. The SGC-expressed TRPA1 is functional. Like DRG neurons, dissociated SGCs exhibit a robust response to the TRPA1-selective agonist allyl isothiocyanate (AITC) by an increase of intracellular Ca²⁺ concentration ([Ca²⁺]_i). These responses are abolished by the TRPA1 antagonist HC030031 and are absent in SGCs and neurons from global TRPA1 null mice. SGCs and neurons harvested from DRG proximal to painful tissue inflammation induced by plantar injection of complete Freund’s adjuvant show greater AITC-evoked elevation of [Ca²⁺]_i and slower recovery compared to sham controls. Similar TRPA1 sensitization occurs in both SGCs and neurons during neuropathic pain induced by spared nerve injury. Together, these results show that functional TRPA1 is expressed by sensory ganglia SGCs, and TRPA1 function in SGCs is enhanced after both peripheral inflammation and nerve injury, and suggest that TRPA1 in SGCs may contribute to inflammatory and neuropathic pain.

Assigning transcriptomic class in the trigeminal ganglion using multiplex in situ hybridization and machine learning

ABSTRACT

Single cell sequencing has provided unprecedented information about the transcriptomic diversity of somatosensory systems. Here, we describe a simple and versatile in situ hybridization (ISH)-based approach for mapping this information back to the tissue. We illustrate the power of this approach by demonstrating that ISH localization with just 8 probes is sufficient to distinguish all major classes of neurons in sections of the trigeminal ganglion. To further simplify the approach and make transcriptomic class assignment and cell segmentation automatic, we developed a machine learning approach for analyzing images from multiprobe ISH experiments. We demonstrate the power of in situ class assignment by examining the expression patterns of voltage-gated sodium channels that play roles in distinct somatosensory processes and pain. Specifically, this analysis resolves intrinsic problems with single cell sequencing related to the sparseness of data leading to ambiguity about gene expression patterns. We also used the multiplex in situ approach to study the projection fields of the different neuronal classes. Our results demonstrate that the surface of the eye and meninges are targeted by broad arrays of neural classes despite their very different sensory properties but exhibit idiotypic patterns of innervation at a quantitative level. Very surprisingly, itch-related neurons extensively innervated the meninges, indicating that these transcriptomic cell classes are not simply labeled lines for triggering itch. Together, these results substantiate the importance of a sensory neuron's peripheral and central connections as well as its transcriptomic class in determining its role in sensation.

Transient Receptor Potential Channel Ankyrin 1: A Unique Regulator of Vascular Function

TRPA1 (transient receptor potential ankyrin 1), the lone member of the mammalian ankyrin TRP subfamily, is a Ca²⁺-permeable, non-selective cation channel. TRPA1 channels are localized to the plasma membranes of various cells types, including sensory neurons and vascular endothelial cells. The channel is endogenously activated by byproducts of reactive oxygen species, such as 4-hydroxy-2-noneal, as well as aromatic, dietary molecules including allyl isothiocyanate, a derivative of mustard oil. Several studies have implicated TRPA1 as a regulator of vascular tone that acts through distinct mechanisms. First, TRPA1 on adventitial sensory nerve fibers mediates neurogenic vasodilation by stimulating the release of the vasodilator, calcitonin gene-related peptide. Second, TRPA1 is expressed in the endothelium of the cerebral vasculature, but not in other vascular beds, and its activation results in localized Ca²⁺ signals that drive endothelium-dependent vasodilation. Finally, TRPA1 is functionally present on brain capillary endothelial cells, where its activation orchestrates a unique biphasic propagation mechanism that dilates upstream arterioles. This response is vital for neurovascular coupling and functional hyperemia in the brain. This review provides a brief overview of the biophysical and pharmacological properties of TRPA1 and discusses the importance of the channel in vascular control and pathophysiology.

TRP Channels in Brain Tumors

Malignant glioma including glioblastoma (GBM) is the most common group of primary brain tumors. Despite standard optimized treatment consisting of extensive resection followed by radiotherapy/concomitant and adjuvant therapy, GBM remains one of the most aggressive human cancers. GBM is a typical example of intra-heterogeneity modeled by different micro-environmental situations, one of the main causes of resistance to conventional treatments. The resistance to treatment is associated with angiogenesis, hypoxic and necrotic tumor areas while heterogeneity would accumulate during glioma cell invasion, supporting recurrence. These complex mechanisms require a focus on potential new molecular actors to consider new treatment options for gliomas. Among emerging and underexplored targets, transient receptor potential (TRP) channels belonging to a superfamily of non-selective cation channels which play critical roles in the responses to a number of external stimuli from the external environment were found to be related to cancer development, including glioma. Here, we discuss the potential as biological markers of diagnosis and prognosis of TRPC6, TRPM8, TRPV4, or TRPV1/V2 being associated with glioma patient overall survival. TRPs-inducing common or distinct mechanisms associated with their Ca²⁺-channel permeability and/or kinase function were detailed as involving miRNA or secondary effector signaling cascades in turn controlling proliferation, cell cycle, apoptotic pathways, DNA repair, resistance to treatment as well as migration/invasion. These recent observations of the key role played by TRPs such as TRPC6 in GBM growth and invasiveness, TRPV2 in proliferation and glioma-stem cell differentiation and TRPM2 as channel carriers of cytotoxic chemotherapy within glioma cells, should offer new directions for innovation in treatment strategies of high-grade glioma as GBM to overcome high resistance and recurrence.

TRPA1 channel: New kid in the 'neurovascular coupling' town

The just-in time delivery of oxygen and nutrients to active brain regions to support function (functional hyperemia; FH) is mediated by not yet fully understood mechanisms collectively referred to as 'neurovascular coupling' (NVC). In a recent publication (eLife 2021) Thakore et al. provide profound mechanistic insight how the capillary endothelial transient receptor potential ankyrin 1 (TRPA1) channel contribute to blood flow control and functional hyperemia in the brain.

The Calcium Signaling Mechanisms in Arterial Smooth Muscle and Endothelial Cells

The contractile state of resistance arteries and arterioles is a crucial determinant of blood pressure and blood flow. Physiological regulation of arterial contractility requires constant communication between endothelial and smooth muscle cells. Various Ca²⁺ signals and Ca²⁺ -sensitive targets ensure dynamic control of intercellular communications in the vascular wall. The functional effect of a Ca²⁺ signal on arterial contractility depends on the type of Ca²⁺ -sensitive target engaged by that signal. Recent studies using advanced imaging methods have identified the spatiotemporal signatures of individual Ca²⁺ signals that control arterial and arteriolar contractility. Broadly speaking, intracellular Ca²⁺ is increased by ion channels and transporters on the plasma membrane and endoplasmic reticular membrane. Physiological roles for many vascular Ca²⁺ signals have already been confirmed, while further investigation is needed for other Ca²⁺ signals. This article focuses on endothelial and smooth muscle Ca²⁺ signaling mechanisms in resistance arteries and arterioles. We discuss the Ca²⁺ entry pathways at the plasma membrane, Ca²⁺ release signals from the intracellular stores, the functional and physiological relevance of Ca²⁺ signals, and their regulatory mechanisms. Finally, we describe the contribution of abnormal endothelial and smooth muscle Ca²⁺ signals to the pathogenesis of vascular disorders. © 2021 American Physiological Society. Compr Physiol 11:1831-1869, 2021.

Role of TRPA1 in Tissue Damage and Kidney Disease

TRPA1, a nonselective cation channel, is expressed in sensory afferent that innervates peripheral targets. Neuronal TRPA1 can promote tissue repair, remove harmful stimuli and induce protective responses via the release of neuropeptides after the activation of the channel by chemical, exogenous, or endogenous irritants in the injured tissue. However, chronic inflammation after repeated noxious stimuli may result in the development of several diseases. In addition to sensory neurons, TRPA1, activated by inflammatory agents from some non-neuronal cells in the injured area or disease, might promote or protect disease progression. Therefore, TRPA1 works as a molecular sentinel of tissue damage or as an inflammation gatekeeper. Most kidney damage cases are associated with inflammation. In this review, we summarised the role of TRPA1 in neurogenic or non-neurogenic inflammation and in kidney disease, especially the non-neuronal TRPA1. In in vivo animal studies, TRPA1 prevented sepsis-induced or Ang-II-induced and ischemia-reperfusion renal injury by maintaining mitochondrial haemostasis or via the downregulation of macrophage-mediated inflammation, respectively. Renal tubular epithelial TRPA1 acts as an oxidative stress sensor to mediate hypoxia-reoxygenation injury in vitro and ischaemia-reperfusion-induced kidney injury in vivo through MAPKs/NF-kB signalling. Acute kidney injury (AKI) patients with high renal tubular TRPA1 expression had low complete renal function recovery. In renal disease, TPRA1 plays different roles in different cell types accordingly. These findings depict the important role of TRPA1 and warrant further investigation.