TRP Channels in Excitotoxicity.

Glutamate excitotoxicity is a central mechanism contributing to cellular dysfunction and death in various neurological disorders and diseases, such as stroke, traumatic brain injury, epilepsy, schizophrenia, addiction, mood disorders, Huntington's disease, Alzheimer's disease, Parkinson's disease, multiple sclerosis, pathologic pain, and even normal aging-related changes. This detrimental effect emerges from glutamate binding to glutamate receptors, including α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors, N-methyl-d-aspartate receptors, kainate receptors, and GluD receptors. Thus, excitotoxicity could be prevented by targeting glutamate receptors and their downstream signaling pathways. However, almost all the glutamate receptor antagonists failed to attenuate excitotoxicity in human patients, mainly due to the limited understanding of the underlying mechanisms regulating excitotoxicity. Transient receptor potential (TRP) channels serve as ancient cellular sensors capable of detecting and responding to both external and internal stimuli. The study of human TRP channels has flourished in recent decades since the initial discovery of mammalian TRP in 1995. These channels have been found to play pivotal roles in numerous pathologic conditions, including excitotoxicity. In this review, our focus centers on exploring the intricate interactions between TRP channels and glutamate receptors in excitotoxicity.

TRPM2 enhances ischemic excitotoxicity by associating with PKCγ.

N-methyl-D-aspartate receptor (NMDAR)-mediated glutamate excitotoxicity significantly contributes to ischemic neuronal death and post-recanalization infarction expansion. Despite tremendous efforts, targeting NMDARs has proven unsuccessful in clinical trials for mitigating brain injury. Here, we show the discovery of an interaction motif for transient receptor potential melastatin 2 (TRPM2) and protein kinase Cγ (PKCγ) association and demonstrate that TRPM2-PKCγ uncoupling is an effective therapeutic strategy for attenuating NMDAR-mediated excitotoxicity in ischemic stroke. We demonstrate that the TRPM2-PKCγ interaction allows TRPM2-mediated Ca2+ influx to promote PKCγ activation, which subsequently enhances TRPM2-induced potentiation of extrasynaptic NMDAR (esNMDAR) activity. By identifying the PKCγ binding motif on TRPM2 (M2PBM), which directly associates with the C2 domain of PKCγ, an interfering peptide (TAT-M2PBM) is developed to disrupt TRPM2-PKCγ interaction without compromising PKCγ function. M2PBM deletion or TRPM2-PKCγ dissociation abolishes both TRPM2-PKCγ and TRPM2-esNMDAR couplings, resulting in reduced excitotoxic neuronal death and attenuated ischemic brain injury.

Activation of endothelial TRPM2 exacerbates blood-brain barrier degradation in ischemic stroke.

AIMS: Damage of the blood-brain barrier (BBB) is a hallmark of brain injury during the early stages of ischemic stroke. The subsequent endothelial hyperpermeability drives the initial pathological changes and aggravates neuronal death. Transient receptor potential melastatin 2 (TRPM2) is a Ca2+-permeable nonselective cation channel activated by oxidative stress. However, whether TRPM2 is involved in BBB degradation during ischemic stroke remains unknown. We aimed to investigate the role of TRPM2 in BBB degradation during ischemic stroke and the underlying molecular mechanisms. METHODS AND RESULTS: Specific deletion of Trpm2 in endothelial cells using Cdh5 Cre produces a potent protective effect against brain injury in mice subjected to middle cerebral artery occlusion (MCAO), which is characterized by reduced infarction size, mitigated plasma extravasation, suppressed immune cell invasion, and inhibited oxidative stress. In vitro experiments using cultured cerebral endothelial cells (CECs) demonstrated that either Trpm2 deletion or inhibition of TRPM2 activation attenuates oxidative stress, Ca2+ overload, and endothelial hyperpermeability induced by oxygen-glucose deprivation (OGD) and CD36 ligand thrombospondin-1 (TSP1). In transfected HEK293T cells, OGD and TSP1 activate TRPM2 in a CD36-dependent manner. Noticeably, in cultured CECs, deleting Trpm2 or inhibiting TRPM2 activation also suppresses the activation of CD36 and cellular dysfunction induced by OGD or TSP1. CONCLUSIONS: In conclusion, our data reveal a novel molecular mechanism in which TRPM2 and CD36 promote the activation of each other, which exacerbates endothelial dysfunction during ischemic stroke. Our study suggests that TRPM2 in endothelial cells is a promising target for developing more effective and safer therapies for ischemic stroke.

TRP Channels in Stroke.

Ischemic stroke is a devastating disease that affects millions of patients worldwide. Unfortunately, there are no effective medications for mitigating brain injury after ischemic stroke. TRP channels are evolutionally ancient biosensors that detect external stimuli as well as tissue or cellular injury. To date, many members of the TRP superfamily have been reported to contribute to ischemic brain injury, including the TRPC subfamily (1, 3, 4, 5, 6, 7), TRPV subfamily (1, 2, 3, 4) and TRPM subfamily (2, 4, 7). These TRP channels share structural similarities but have distinct channel functions and properties. Their activation during ischemic stroke can be beneficial, detrimental, or even both. In this review, we focus on discussing the interesting features of stroke-related TRP channels and summarizing the underlying cellular and molecular mechanisms responsible for their involvement in ischemic brain injury.

Regulation of Presynaptic Calcium Channels.

Voltage-gated calcium channels (VGCCs), especially Cav2.1 and Cav2.2, are the major mediators of Ca2+ influx at the presynaptic membrane in response to neuron excitation, thereby exerting a predominant control on synaptic transmission. To guarantee the timely and precise release of neurotransmitters at synapses, the activity of presynaptic VGCCs is tightly regulated by a variety of factors, including auxiliary subunits, membrane potential, G protein-coupled receptors (GPCRs), calmodulin (CaM), Ca2+-binding proteins (CaBP), protein kinases, various interacting proteins, alternative splicing events, and genetic variations.

Review on Processing Methods of Toxic Chinese Materia Medica and the Related Mechanisms of Action.

Toxic Chinese materia medica (CMM) has both pharmacological activities and toxic effects. Based on thousands of years of experience in the application of CMMs, people have explored many practical processing methods of CMMs, also known as "Pao Zhi", to reduce/control toxicity and preserve/enhance efficacy. Toxic CMMs have been used throughout China's hospitals. Yet, the production and use of toxic CMM should be carried out in accordance with the Chinese pharmacopoeia (ChP) and the processing regulations formulated by the health administrative departments of provinces, autonomous regions, and municipalities directly under the Central Government. This paper summarizes the current understanding and awareness of toxicity and 45 toxic CMMs, the commonly used processing methods of toxic CMMs recorded in the 2020 edition of ChP, and the changes in the chemical component, toxicity, or efficacy profiles after processing. This review may provide useful information for the processing methods of toxic CMMs worldwide. We believe that with an in-depth study and understanding of toxic CMMs combined with a standardized application, the toxicity of CMMs will be predictable and controllable in the future.

Structural insights into regulation of CNNM-TRPM7 divalent cation uptake by the small GTPase ARL15.

Cystathionine-ß-synthase (CBS)-pair domain divalent metal cation transport mediators (CNNMs) are an evolutionarily conserved family of magnesium transporters. They promote efflux of Mg2+ ions on their own and influx of divalent cations when expressed with the transient receptor potential ion channel subfamily M member 7 (TRPM7). Recently, ADP-ribosylation factor-like GTPase 15 (ARL15) has been identified as CNNM-binding partner and an inhibitor of divalent cation influx by TRPM7. Here, we characterize ARL15 as a GTP and CNNM-binding protein and demonstrate that ARL15 also inhibits CNNM2 Mg2+ efflux. The crystal structure of a complex between ARL15 and CNNM2 CBS-pair domain reveals the molecular basis for binding and allowed the identification of mutations that specifically block binding. A binding deficient ARL15 mutant, R95A, failed to inhibit CNNM and TRPM7 transport of Mg2+ and Zn2+ ions. Structural analysis and binding experiments with phosphatase of regenerating liver 2 (PRL2 or PTP4A2) showed that ARL15 and PRLs compete for binding CNNM to coordinate regulation of ion transport by CNNM and TRPM7.

Structural insights into regulation of TRPM7 divalent cation uptake by the small GTPase ARL15.

Cystathionine-ß-synthase (CBS)-pair domain divalent metal cation transport mediators (CNNMs) are an evolutionarily conserved family of magnesium transporters. They promote efflux of Mg 2+ ions on their own or uptake of divalent cations when coupled to the transient receptor potential ion channel subfamily M member 7 (TRPM7). Recently, ADP-ribosylation factor-like GTPase 15 (ARL15) has been identified as CNNM binding partner and an inhibitor of divalent cation influx by TRPM7. Here, we characterize ARL15 as a GTP-binding protein and demonstrate that it binds the CNNM CBS-pair domain with low micromolar affinity. The crystal structure of the complex between ARL15 GTPase domain and CNNM2 CBS-pair domain reveals the molecular determinants of the interaction and allowed the identification of mutations in ARL15 and CNNM2 mutations that abrogate binding. Loss of CNNM binding prevented ARL15 suppression of TRPM7 channel activity in support of previous reports that the proteins function as a ternary complex. Binding experiments with phosphatase of regenerating liver 2 (PRL2 or PTP4A2) revealed that ARL15 and PRLs compete for binding CNNM, suggesting antagonistic regulation of divalent cation transport by the two proteins.

Effects of methylprednisolone combined with advanced antibiotics and antiviral drugs on serum immunoglobulin and inflammatory factor levels in patients with viral pneumonia.

Viral pneumonia (VP) is known for its wide transmission and severe pathological damage. ninety cases of VP patients were rolled into an experimental group (group E, methylprednisolone + advanced antibiotics + antiviral drugs) and a control group (group C, methylprednisolone), with 45 cases in each group. General information about the patients, inflammatory factors, serum immunoglobulins, T lymphocyte subsets, and treatment outcomes (efficiency rate, conversion rate to negative) were compared. In group E, interleukin-6 (IL-6) (0.18±0.07) ng/L was inferior to in group C (0.33±0.09) ng/L, p<0.05; tumor necrosis factor-alpha (TNF-α) (17.22±4.13) ng/L was inferior to group C (26.07±4.08) ng/L, p<0.05; lgA (0.81±0.22) g/L was superior to in group C (0.68±0.17) g/L, P<0.05; lgM (1.62±0.13) g/L was superior to group C (1.09±0.03) g/L, p<0.05; lgE (0.19±0.02) g/L was inferior to group C (0.23±0.03) g/L, p<0.05; CD4+/CD8+ ratio (1.71±0.33) was superior to group C (1.24±0.43), p<0.05; the total efficiency rate in group C (77.78%) was inferior to group E (97.78%), p<0.05; the conversion rate to negative of viral antigens in group E (91.11%) was superior to in group C (64.44%), p<0.05. methylprednisolone in combination with advanced antibiotics and antiviral drugs is an effective treatment approach for VP.

[Application of quality function deployment technology in extracorporeal membrane oxygenation treatment of patients with critical cardiopulmonary disease].

OBJECTIVE: To accurately and effectively identify the most critical needs of extracorporeal membrane oxygenation (ECMO) treatment for patients with severe cardiopulmonary diseases, and to better carry out continuous improvement of medical service quality an patients' satisfaction. METHODS: Patients who underwent ECMO and transferred from 56 medical institutions in the Henan Provincial People's Hospital Critical Care Medicine Specialist Alliance [the patients who were transported before applying quality function deployment (QFD) from June 2017 to May 2018 were enrolled as the control group, and patients who were transported after applying QFD from June 2018 to May 2019 were the observation group], medical staff in the alliance hospitals, ECMO transfer teams and transfer driver teams were enrolled as the subjects of the survey. QFD was applied to convert the collected requirements into quality improvement elements for targeted improvement measures. RESULTS: A total of 125 questionnaires were distributed in this survey, and 116 valid questionnaires were collected, including 91 from patients (including 27 from the control group and 64 from the observation group), 10 from the medical staff of the alliance hospitals, 10 from the ECMO transport teams and 5 from the transport driver teams. The questionnaire recovery rate was 92.8%. The improvement elements of ECMO treatment for patients with critical cardiopulmonary diseases were ranked according to the importance, and the top five were as follows: the accuracy of the first diagnosis, the specialization of ECMO team, the guarantee of vehicle safety, the seamless responses, and the smooth coordinated rescue protocol. CONCLUSIONS: The top five improvement elements should be prioritized in ECMO treatment of patients with critical cardiopulmonary disease in all hospitals of the Alliance to ensure more accurate and timely treatment.

Cardiac ultrastructure inspired matrix induces advanced metabolic and functional maturation of differentiated human cardiomyocytes.

The vast potential of human induced pluripotent stem-cell-derived cardiomyocytes (hiPSC-CMs) in preclinical models of cardiac pathologies, precision medicine, and drug screening remains to be fully realized because hiPSC-CMs are immature without adult-like characteristics. Here, we present a method to accelerate hiPSC-CM maturation on a substrate, cardiac mimetic matrix (CMM), mimicking adult human heart matrix ligand chemistry, rigidity, and submicron ultrastructure, which synergistically mature hiPSC-CMs rapidly within 30 days. hiPSC-CMs matured on CMM exhibit systemic transcriptomic maturation toward an adult heart state, are aligned with high strain energy, metabolically rely on oxidative phosphorylation and fatty acid oxidation, and display enhanced redox handling capability, efficient calcium handling, and electrophysiological features of ventricular myocytes. Endothelin-1-induced pathological hypertrophy is mitigated on CMM, highlighting the role of a native cardiac microenvironment in withstanding hypertrophy progression. CMM is a convenient model for accelerated development of ventricular myocytes manifesting highly specialized cardiac-specific functions.

PLCß2 Promotes VEGF-Induced Vascular Permeability.

BACKGROUND: Regulation of vascular permeability is critical to maintaining tissue metabolic homeostasis. VEGF (vascular endothelial growth factor) is a key stimulus of vascular permeability in acute and chronic diseases including ischemia reperfusion injury, sepsis, and cancer. Identification of novel regulators of vascular permeability would allow for the development of effective targeted therapeutics for patients with unmet medical need. METHODS: In vitro and in vivo models of VEGFA-induced vascular permeability, pathological permeability, quantitation of intracellular calcium release and cell entry, and phosphatidylinositol 4,5-bisphosphate levels were evaluated with and without modulation of PLC (phospholipase C) ß2. RESULTS: Global knock-out of PLCß2 in mice resulted in blockade of VEGFA-induced vascular permeability in vivo and transendothelial permeability in primary lung endothelial cells. Further work in an immortalized human microvascular cell line modulated with stable knockdown of PLCß2 recapitulated the observations in the mouse model and primary cell assays. Additionally, loss of PLCß2 limited both intracellular release and extracellular entry of calcium following VEGF stimulation as well as reduced basal and VEGFA-stimulated levels of phosphatidylinositol 4,5-bisphosphate compared to control cells. Finally, loss of PLCß2 in both a hyperoxia-induced lung permeability model and a cardiac ischemia:reperfusion model resulted in improved animal outcomes when compared with wild-type controls. CONCLUSIONS: The results implicate PLCß2 as a key positive regulator of VEGF-induced vascular permeability through regulation of both calcium flux and phosphatidylinositol 4,5-bisphosphate levels at the cellular level. Targeting of PLCß2 in a therapeutic setting may provide a novel approach to regulating vascular permeability in patients.

TRPM2 deficiency in mice protects against atherosclerosis by inhibiting TRPM2-CD36 inflammatory axis in macrophages.

Atherosclerosis is the major cause of ischemic heart disease and stroke, the leading causes of mortality worldwide. The central pathological features of atherosclerosis include macrophage infiltration and foam cell formation. However, the detailed mechanisms regulating these two processes remain unclear. Here we show that oxidative stress-activated Ca2+-permeable transient receptor potential melastatin 2 (TRPM2) plays a critical role in atherogenesis. Both global and macrophage-specific Trpm2 deletion protect Apoe -/- mice against atherosclerosis. Trpm2 deficiency reduces oxidized low-density lipoprotein (oxLDL) uptake by macrophages, thereby minimizing macrophage infiltration, foam cell formation and inflammatory responses. Activation of the oxLDL receptor CD36 induces TRPM2 activity, and vice versa. In cultured macrophages, TRPM2 is activated by CD36 ligands oxLDL and thrombospondin-1 (TSP1), and deleting Trpm2 or inhibiting TRPM2 activity suppresses the activation of CD36 signaling cascade induced by oxLDL and TSP1. Our findings establish the TRPM2-CD36 axis as a molecular mechanism underlying atherogenesis, and suggest TRPM2 as a potential therapeutic target for atherosclerosis.

Functional coupling of TRPM2 and extrasynaptic NMDARs exacerbates excitotoxicity in ischemic brain injury.

Excitotoxicity induced by NMDA receptor (NMDAR) activation is a major cause of neuronal death in ischemic stroke. However, past efforts of directly targeting NMDARs have unfortunately failed in clinical trials. Here, we reveal an unexpected mechanism underlying NMDAR-mediated neurotoxicity, which leads to the identification of a novel target and development of an effective therapeutic peptide for ischemic stroke. We show that NMDAR-induced excitotoxicity is enhanced by physical and functional coupling of NMDAR to an ion channel TRPM2 upon ischemic insults. TRPM2-NMDAR association promotes the surface expression of extrasynaptic NMDARs, leading to enhanced NMDAR activity and increased neuronal death. We identified a specific NMDAR-interacting motif on TRPM2 and designed a membrane-permeable peptide to uncouple the TRPM2-NMDAR interaction. This disrupting peptide protects neurons against ischemic injury in vitro and protects mice against ischemic stroke in vivo. These findings provide an unconventional strategy to mitigate excitotoxic neuronal death without directly targeting NMDARs.

A Systemic Review of the Integral Role of TRPM2 in Ischemic Stroke: From Upstream Risk Factors to Ultimate Neuronal Death.

Ischemic stroke causes a heavy health burden worldwide, with over 10 million new cases every year. Despite the high prevalence and mortality rate of ischemic stroke, the underlying molecular mechanisms for the common etiological factors of ischemic stroke and ischemic stroke itself remain unclear, which results in insufficient preventive strategies and ineffective treatments for this devastating disease. In this review, we demonstrate that transient receptor potential cation channel, subfamily M, member 2 (TRPM2), a non-selective ion channel activated by oxidative stress, is actively involved in all the important steps in the etiology and pathology of ischemic stroke. TRPM2 could be a promising target in screening more effective prophylactic strategies and therapeutic medications for ischemic stroke.

CNNM proteins selectively bind to the TRPM7 channel to stimulate divalent cation entry into cells.

Magnesium is essential for cellular life, but how it is homeostatically controlled still remains poorly understood. Here, we report that members of CNNM family, which have been controversially implicated in both cellular Mg2+ influx and efflux, selectively bind to the TRPM7 channel to stimulate divalent cation entry into cells. Coexpression of CNNMs with the channel markedly increased uptake of divalent cations, which is prevented by an inactivating mutation to the channel's pore. Knockout (KO) of TRPM7 in cells or application of the TRPM7 channel inhibitor NS8593 also interfered with CNNM-stimulated divalent cation uptake. Conversely, KO of CNNM3 and CNNM4 in HEK-293 cells significantly reduced TRPM7-mediated divalent cation entry, without affecting TRPM7 protein expression or its cell surface levels. Furthermore, we found that cellular overexpression of phosphatases of regenerating liver (PRLs), known CNNMs binding partners, stimulated TRPM7-dependent divalent cation entry and that CNNMs were required for this activity. Whole-cell electrophysiological recordings demonstrated that deletion of CNNM3 and CNNM4 from HEK-293 cells interfered with heterologously expressed and native TRPM7 channel function. We conclude that CNNMs employ the TRPM7 channel to mediate divalent cation influx and that CNNMs also possess separate TRPM7-independent Mg2+ efflux activities that contribute to CNNMs' control of cellular Mg2+ homeostasis.

TRP channels in health and disease at a glance.

The transient receptor potential (TRP) channel superfamily consists of a large group of non-selective cation channels that serve as cellular sensors for a wide spectrum of physical and environmental stimuli. The 28 mammalian TRPs, categorized into six subfamilies, including TRPC (canonical), TRPV (vanilloid), TRPM (melastatin), TRPA (ankyrin), TRPML (mucolipin) and TRPP (polycystin), are widely expressed in different cells and tissues. TRPs exhibit a variety of unique features that not only distinguish them from other superfamilies of ion channels, but also confer diverse physiological functions. Located at the plasma membrane or in the membranes of intracellular organelles, TRPs are the cellular safeguards that sense various cell stresses and environmental stimuli and translate this information into responses at the organismal level. Loss- or gain-of-function mutations of TRPs cause inherited diseases and pathologies in different physiological systems, whereas up- or down-regulation of TRPs is associated with acquired human disorders. In this Cell Science at a Glance article and the accompanying poster, we briefly summarize the history of the discovery of TRPs, their unique features, recent advances in the understanding of TRP activation mechanisms, the structural basis of TRP Ca2+ selectivity and ligand binding, as well as potential roles in mammalian physiology and pathology.

[Application of extracorporeal membrane oxygenation regional treatment pattern in patients with severe cardiopulmonary diseases].

OBJECTIVE: To assess the application of extracorporeal membrane oxygenation (ECMO) regional treatment pattern in patients with severe cardiopulmonary diseases. METHODS: A retrospective analysis was conducted. Patients with severe cardiopulmonary disease who were transferred to Henan Provincial People's Hospital after ECMO treatment in cooperative hospitals were selected. The patients who received regular ECMO treatment from June 2017 to May 2018 were enrolled as the control group, and the patients who received ECMO regional treatment from June 2018 to May 2019 were selected as the observation group. The ECMO regional treatment pattern referred to implement a referral program for critical patients in primary hospitals, which mainly included the establishment of ECMO regional cooperative treatment network and ECMO referral team, the formulation of ECMO referral management standards, and the promotion of the merging of high-quality medical resources. Time of establishment of ECMO, ECMO regional treatment satisfaction, and the incidence of adverse events were also compared. RESULTS: There were 27 patients enrolled in the control group and 64 patients in the observation group. There were no significant differences in gender, age, body mass index (BMI), ECMO mode, hypertension or coronary heart disease history between the two groups. Compared with the control group, the time for establishment of ECMO in the observation group was significantly shorter (minutes: 38.10±17.19 vs. 54.67±41.30, t = 2.715, P = 0.008), the ECMO treatment satisfaction of the observation group was also significantly higher than that of the control group (98.4% vs. 88.9%, χ2 = 4.120, P = 0.042), and the incidence of ECMO referral adverse events was significantly lower than that of the control group (6.25% vs. 25.93%, χ2 = 6.918, P = 0.009). CONCLUSIONS: The ECMO regional collaborative pattern in patients with severe cardiopulmonary diseases can shorten the time for establishment of ECMO, improve the satisfaction of ECMO treatment, and reduce the incidence of adverse events in ECMO referral.