IP3 Receptor Research Articles

A sustained calcium response mediated by IP3 receptor anchoring to the desmosome is essential for apoptotic cell elimination

Efficient elimination of apoptotic cells within epithelial cell sheets is crucial for preserving epithelial barrier integrity.1 It is well established that immediate neighbors of an apoptotic cell actively participate in its removal by enclosing it within a wall of actomyosin, pushing it out in a purse-string manner in a process called apical extrusion.2,3,4,5,6,7 Here, we found that sustained elevation of calcium ions in neighboring epithelial cells is necessary to generate the contractility required for apoptotic cell elimination. This phenomenon, which we call calcium response in effectors of apical extrusion (CaRE), highlights the disparate calcium dynamics within the epithelial sheet. Furthermore, we elucidate the essential role of desmosomes in CaRE. Specifically, we identify a subset of IP3 receptors within the endoplasmic reticulum that is recruited to the desmosome by K-Ras-induced actin-binding protein as the core component of this process. The interplay between these cellular structures heightens actomyosin contractility to drive apoptotic cell removal. Our findings underscore the physiological significance of integrating desmosomes with the endoplasmic reticulum in epithelial sheet homeostasis, shedding new light on cell-cell communication and tissue maintenance.

Protein kinase C epsilon contributes to chronic mechanoreflex sensitization in rats with heart failure.

We investigated second-messenger signalling components linked to the stimulation of Gq protein-coupled receptors (e.g. thromboxane A2 and bradykinin B2 receptors) on the sensory endings of thin fibre muscle afferents in the chronic mechanoreflex sensitization in rats with myocardial infarction-induced heart failure with reduced ejection fraction (HF-rEF). We hypothesized that injection of either the inositol 1,4,5-trisphosphate (IP3) receptor antagonist xestospongin C (5µg) or the PKCε translocation inhibitor PKCe141 (45µg) into the arterial supply of the hindlimb would reduce the increase in renal sympathetic nerve activity (RSNA) and mean arterial pressure (MAP) evoked during 30s of 1Hz dynamic hindlimb muscle stretch in decerebrate, unanaesthetized HF-rEF rats but not sham-operated controls (SHAM). Ejection fraction was significantly reduced in HF-rEF (45 (19)%) compared to SHAM (80 (9)%; P<0.001) rats. In HF-rEF rats (n=3M/2F), IP3 receptor blockade had no effect on the peak ΔRSNA (pre: 99 (74)%; post: 133 (79)%; P=0.974) or peak ΔMAP response to stretch (peak ΔMAP: pre: 32 (14) mmHg; post: 36 (21) mmHg; P=0.719). Conversely, in another group of HF-rEF rats (n=4M/3F), the PKCε translocation inhibitor reduced the peak ΔRSNA (pre: 110 (77)%; post: 62 (58)%; P=0.029) and peak ΔMAP response to stretch (pre: 30 (20) mmHg; post: 17 (16) mmHg; P=0.048). In SHAM counterparts, neither drug affected the mechanoreflex responses. Our findings highlight PKCε, but not IP3 receptors, as a significant second-messenger in the chronic mechanoreflex sensitization in HF-rEF which may play a crucial role in the exaggerated sympathetic response to exercise in this patient population. KEY POINTS: Skeletal muscle contraction results in an exaggerated reflex increase in sympathetic nerve activity in heart failure patients with reduced ejection fraction (HF-rEF) compared to healthy individuals, contributing to increased cardiovascular risk and impaired tolerance for mild exercise. The exaggerated reflex sympathetic responses in HF-rEF may be attributed to a chronic sensitization of mechanically sensitive thin fibre muscle afferents mediated, at least in part, by stimulation of Gq protein-coupled thromboxane A2 and bradykinin B2 receptors on muscle afferent sensory endings. The specific Gq protein-linked signalling mechanisms that produce the chronic mechanoreflex sensitization in HF-rEF have not been investigated but may involve inositol 1,4,5-trisphosphate (IP3) receptors and/or protein kinase C epsilon (PKCε). Here we demonstrate that PKCε, but not IP3 receptors, within the sensory endings of thin fibre muscle afferents plays a role in the sensitization of mechanically sensitive thin fibre muscle afferents in rats with HF-rEF.

A pleiotropic recurrent dominant ITPR3 variant causes a complex multisystemic disease.

Inositol 1,4,5-trisphosphate (IP3) receptor type 1 (ITPR1), 2 (ITPR2), and 3 (ITPR3) encode the IP3 receptor (IP3R), a key player in intracellular calcium release. In four unrelated patients, we report that an identical ITPR3 de novo variant-NM_002224.3:c.7570C>T, p.Arg2524Cys-causes, through a dominant-negative effect, a complex multisystemic disorder with immunodeficiency. This leads to defective calcium homeostasis, mitochondrial malfunction, CD4+ lymphopenia, a quasi-absence of naïve CD4+ and CD8+ cells, an increase in memory cells, and a distinct TCR repertoire. The calcium defect was recapitulated in Jurkat knock-in. Site-directed mutagenesis displayed the exquisite sensitivity of Arg2524 to any amino acid change. Despite the fact that all patients had severe immunodeficiency, they also displayed variable multisystemic involvements, including ectodermal dysplasia, Charcot-Marie-Tooth disease, short stature, and bone marrow failure. In conclusion, unlike previously reported ITPR1-3 deficiencies leading to narrow, mainly neurological phenotypes, a recurrent dominant ITPR3 variant leads to a multisystemic disease, defining a unique role for IP3R3 in the tetrameric IP3R complex.

High-Impact AMPAkines Elevate Calcium Levels in Cortical Astrocytes by Mobilizing Endoplasmic Reticular Calcium Stores

Ampakines—positive allosteric modulators of AMPA-type glutamate receptors (AMPARs)—are drug candidates that have shown substantial promise in pre-clinical models of various neurodegenerative and neuropsychiatric diseases. Much of the study of ampakines has focused on how these drugs modulate neuronal AMPARs to achieve certain therapeutic effects. However, astrocytes also express functional AMPARs and their physiology may be sensitive to modulation by ampakines. Herein, we investigate the effects of multiple ampakines on calcium levels in cortical astrocytes. We find that ampakines augment cytosolic calcium elevations in astrocytes to an extent far greater than that achieved by AMPA alone. This effect is amenable to competitive AMPAR blockade. Furthermore, calcium induction is sensitive to phospholipase Cβ antagonism and blockade of inositol triphosphate receptors located on the endoplasmic reticulum. Low-impact ampakines exerted weaker effects on cytosolic calcium levels in astrocytes and higher concentrations were required to observe an effect. Furthermore, high doses of the low-impact ampakine, CX717, were not toxic to cortical astrocytes at high concentrations, which may serve to differentiate low-impact ampakines from classical AMPAR positive modulators like cyclothiazide. As ampakines are further developed for clinical use, it would be prudent to determine the extent to and manner by which they affect astrocytes, as these effects may also underpin their therapeutic utility in CNS pathologies.

African swine fever virus modulates the endoplasmic reticulum stress-ATF6-calcium axis to facilitate viral replication

ABSTRACT African swine fever (ASF), caused by African swine fever virus (ASFV), is a devastating infectious disease of domestic pigs and wild boar, which threatens the global pig industry. Endoplasmic reticulum (ER) is a multifunctional signaling organelle in eukaryotic cells that is involved in protein synthesis, processing, posttranslational modification and quality control. As intracellular parasitic organisms, viruses have evolved several strategies to modulate ER functions to favor their life cycles. We have previously demonstrated that the differentially expressed genes associated with unfolded protein response (UPR), which represents a response to ER stress, are significantly enriched upon ASFV infection. However, the correlation between the ER stress or UPR and ASFV replication has not been illuminated yet. Here, we demonstrated that ASFV infection induces ER stress both in target cells and in vivo, and subsequently activates the activating transcription factor 6 (ATF6) branch of the UPR to facilitate viral replication. Mechanistically, ASFV infection disrupts intracellular calcium (Ca2+) homeostasis, while the ATF6 pathway facilitates ASFV replication by increasing the cytoplasmic Ca2+ level. More specifically, we demonstrated that ASFV infection triggers ER-dependent Ca2+ release via the inositol triphosphate receptor (IP3R) channel. Notably, we showed that the ASFV B117L protein plays crucial roles in ER stress and the downstream activation of the ATF6 branch, as well as the disruption of Ca2+ homeostasis. Taken together, our findings reveal for the first time that ASFV modulates the ER stress-ATF6-Ca2+ axis to facilitate viral replication, which provides novel insights into the development of antiviral strategies for ASFV.

Blocking IP3 Receptors with 2-APB Alters Cellular Signaling during 7-Day Soleus Unloading in Rats

Blocking IP3 Receptors with 2-APB Alters Cellular Signaling during 7-Day Soleus Unloading in Rats

Roles of metabotropic glutamate receptor 5 in low [Mg2+]o-induced interictal epileptiform activity in rat hippocampal slices.

Group I metabotropic glutamate receptors (mGluRs) modulate postsynaptic neuronal excitability and epileptogenesis. We investigated roles of group I mGluRs on low extracellular Mg2+ concentration ([Mg2+]o)-induced epileptiform activity and neuronal cell death in the CA1 regions of isolated rat hippocampal slices without the entorhinal cortex using extracellular recording and propidium iodide staining. Exposure to Mg2+-free artificial cerebrospinal fluid can induce interictal epileptiform activity in the CA1 regions of rat hippocampal slices. MPEP, a mGluR 5 antagonist, significantly inhibited the spike firing of the low [Mg2+]o-induced epileptiform activity, whereas LY367385, a mGluR1 antagonist, did not. DHPG, a group 1 mGluR agonist, significantly increased the spike firing of the epileptiform activity. U73122, a PLC inhibitor, inhibited the spike firing. Thapsigargin, an ER Ca2+-ATPase antagonist, significantly inhibited the spike firing and amplitude of the epileptiform activity. Both the IP3 receptor antagonist 2-APB and the ryanodine receptor antagonist dantrolene significantly inhibited the spike firing. The PKC inhibitors such as chelerythrine and GF109203X, significantly increased the spike firing. Flufenamic acid, a relatively specific TRPC 1, 4, 5 channel antagonist, significantly inhibited the spike firing, whereas SKF96365, a relatively non-specific TRPC channel antagonist, did not. MPEP significantly decreased low [Mg2+]o DMEM-induced neuronal cell death in the CA1 regions, but LY367385 did not. We suggest that mGluR 5 is involved in low [Mg2+]oinduced interictal epileptiform activity in the CA1 regions of rat hippocampal slices through PLC, release of Ca2+ from intracellular stores and PKC and TRPC channels, which could be involved in neuronal cell death.

Modulation of Spontaneous Action Potential Rate by Inositol Trisphosphate in Myocytes from the Rabbit Atrioventricular Node.

The atrioventricular node (AVN) is a key component of the cardiac conduction system and takes over pacemaking of the ventricles if the sinoatrial node fails. IP3 (inositol 1,4,5 trisphosphate) can modulate excitability of myocytes from other regions of the heart, but it is not known whether IP3 receptor (IP3-R) activation modulates AVN cell pacemaking. Consequently, this study investigated effects of IP3 on spontaneous action potentials (APs) from AVN cells isolated from rabbit hearts. Immunohistochemistry and confocal imaging demonstrated the presence of IP3-R2 in isolated AVN cells, with partial overlap with RyR2 ryanodine receptors seen in co-labelling experiments. In whole-cell recordings at physiological temperature, application of 10 µM membrane-permeant Bt3-(1,4,5)IP3-AM accelerated spontaneous AP rate and increased diastolic depolarization rate, without direct effects on ICa,L, IKr, If or INCX. By contrast, application via the patch pipette of 5 µM of the IP3-R inhibitor xestospongin C led to a slowing in spontaneous AP rate and prevented 10 µM Bt3-(1,4,5)IP3-AM application from increasing the AP rate. UV excitation of AVN cells loaded with caged-IP3 led to an acceleration in AP rate, the magnitude of which increased with the extent of UV excitation. 2-APB slowed spontaneous AP rate, consistent with a role for constitutive IP3-R activity; however, it was also found to inhibit ICa,L and IKr, confounding its use for studying IP3-R. Under AP voltage clamp, UV excitation of AVN cells loaded with caged IP3 activated an inward current during diastolic depolarization. Collectively, these results demonstrate that IP3 can modulate AVN cell pacemaking rate.

Prophylactic supplementation with selenium nanoparticles protects against foodborne toxin zearalenone-induced intestinal barrier dysfunction

Selenium nanoparticles (SeNPs) have been used as a potential alternative to other forms of selenium in nutritional supplements for the treatment and prevention of inflammatory and oxidative stress-related diseases. Zearalenone (ZEA) is a foodborne mycotoxin present in grains that poses a health threat. Here, we investigated the adverse impacts of ZEA on intestinal homeostasis and explored the protective effects of probiotic-synthesized SeNPs against its damage. Results showed that ZEA reduced mucin and tight junction proteins expression in jejunum, induced inflammatory process and oxidative stress which in turn increased intestinal permeability in mice. ZEA-induced intestinal toxicity was further verified in vitro. Intracellular redox imbalance triggered endoplasmic reticulum (ER) stress in intestinal epithelial cells, which caused structural damage to the ER. Remarkably, SeNPs exhibited a counteractive effect by inducing a decrease in intracellular levels of Inositol 1,4,5-trisphosphate (IP3) and Ca2+, along with a reduction in the expression level of IP3 receptor. SeNPs effectively mitigated ZEA-induced ER stress was related to the increased activity of selenium-dependent antioxidant enzymes and the expression of ER-resident selenoproteins. Furthermore, SeNPs significantly inhibited the activation of PERK/eIF2α/ATF4/CHOP pathway in vitro and in vivo. In addition, SeNPs effectively reversed ZEA-induced gut microbiota dysbiosis and increased the abundance of short-chain fatty acid-producing beneficial bacteria (Alloprevotella and Muribaculaceae). The Spearman correlation analysis suggested that the structure of gut microbiota was closely related to the SeNPs attenuation of ZEA-induced intestinal toxicity. This study provides new insights into ZEA-induced intestinal toxicity and identifies a novel potential nutrient SeNPs to overcome adverse effects.

A spatial threshold for astrocyte calcium surge.

There is a spatial threshold for the astrocyte intracellular calcium signal propagation that is determined by astrocyte intrinsic properties and controls gliotransmission.

Impacts of exposure to and subsequent discontinuation of clozapine on tripartite synaptic transmission.

Clozapine is an effective antipsychotic for treatment-resistant schizophrenia, but its discontinuation leads to discontinuation syndrome/catatonia complicated by benzodiazepine-resistance and rhabdomyolysis. This study determined time-dependent effects of exposure and subsequent discontinuation of clozapine on expression of connexin43, 5-HT receptors, intracellular L-β-aminoisobutyrate (L-BAIBA) and 2nd-messengers and signalling of AMPK, PP2A and Akt in cultured astrocytes and rat frontal cortex. Intracellular L-BAIBA levels increased during clozapine exposure but immediately recovered after discontinuation. Both exposure to clozapine and L-BAIBA increased connexin43 and signalling of AMPK/Akt time-dependently, but reduced PP2A signalling, 5-HT receptor expression and IP3 level. These changes recovered within 2 weeks after discontinuation, while 5-HT receptors and IP3 transiently increased during the recovery process. L-BAIBA activated AMPK signalling, leading to attenuated PP2A signalling. Astroglial D-serine release was increased by clozapine exposure but continued to increase within 1 week after discontinuation via activation of IP3 receptor function. Clozapine discontinuation restored PP2A signalling due to decreased L-BAIBA, increased 5-HT receptor expression via probably enhanced 5-HT receptor recycling, but increased astroglial D-serine release persisted by transiently activated IP3 receptors via transiently increased IP3 level. Decreased L-BAIBA caused by clozapine discontinuation is, at least partially, involved in the transiently increased 5-HT receptor and astroglial D-serine release.

Expression of prostacyclin receptor in chronic rhinosinusitis and its relationship with type 2 inflammation

Objective:The purpose of this study is to explore the expression of prostacyclin receptor（IP） in patients with chronic rhinosinusitis（CRS） and its possible association with type 2 inflammation. Methods:HE staining was used to observe the morphological changes of nasal mucosa, qRT-PCR was used to detect the expression of IP in polyps and nasal mucosa, and IHC was used to detect the expression of IP, IL-4, IL-5 and IL-13 in polyps and nasal mucosa. Results:Compared with the control group, the nasal mucosa of patients with various types of CRS was obviously thickened, accompanied by inflammatory cell infiltration and gland hyperplasia. The statistical results of IHC showed that the expression levels of IL-4, IL-5 and IL-13 in CRS group were significantly higher than those in control group（P<0.05）, and the IP expression in control group was significantly higher than that in ECRS group and non-ECRS group（P<0.05）. The IP expression in ECRS group was negatively correlated with IL-4, IL-5 and IL-13. The results of qRT-PCR showed that the expression of IP mRNA in control group was significantly higher than that in ECRS group and non-ECRS group（P<0.05）. Conclusion:IL-4, IL-5 and IL-13 are highly expressed in the nasal mucosa of CRS patients, while IP is poorly expressed in the nasal mucosa of CRS patients, and IP is negatively correlated with IL-4, IL-5 and IL-13, suggesting that IP is related to the occurrence and development of type 2 inflammation and may be a potential therapeutic target for CRS patients.

New and Emerging Therapeutic Drugs for the Treatment of Pulmonary Arterial Hypertension: A Systematic Review.

Pulmonary arterial hypertension (PAH) is a serious, progressive, and potentially fatal lung disease characterized by a gradual increase in mean pulmonary arterial pressure to over 20 mmHg at rest. The pathogenesis of PAH is multifactorial. It involves dynamic obstruction of the pulmonary vasculature through vasoconstriction, structural obstruction due to adverse vascular remodeling, and pathological obstruction caused by vascular fibrosis and stiffening, which reduces compliance. PAH often presents with vague initial symptoms and is frequently diagnosed at an advanced stage. The increased pulmonary arterial pressure leads to vascular remodeling, eventually resulting in right ventricular hypertrophy and failure. PAH is a rare condition with a median life expectancy of three years, underscoring the need for effective treatment alternatives. Several FDA-approved therapeutic options are available, including prostacyclin analogs (epoprostenol, iloprost, and treprostinil), the non-prostanoid IP receptor agonist selexipag, selective endothelin receptor antagonists (ERA) (ambrisentan, bosentan, and macitentan), phosphodiesterase 5 inhibitors (sildenafil and tadalafil), and the soluble guanylate cyclase (sGC) stimulator riociguat. Despite these advancements, current medications do not provide a permanent cure. This study presents an overview of current and emerging PAH therapies through a systematic literature review. It involved an analysis of nine studies and a review of 800 papers from reputable journals published between 2013 and June 2023. The research focused on drug effects on the six-minute walk distance (6-MWD) and associated side effects in randomized controlled trials. The review found that while udenafil, imatinib, racecadotril, sotatercept, anastrozole, riociguat, tacrolimus, and ralinepag were evaluated, imatinib was notably associated with adverse side effects. Conversely, udenafil, racecadotril, sotatercept, anastrozole, riociguat, tacrolimus, and ralinepag were found to be safe, well-tolerated, and effective in improving hemodynamic measures and 6-MWDs. This study aims to summarize the developing treatment options currently under clinical trials, highlighting the need for further trials before their application in clinical practice.

Dissecting the neuroprotective interaction between the BH4 domain of BCL-w and the IP3 receptor

BCL-w is a BCL-2 family protein that promotes cell survival in tissue- and disease-specific contexts. The canonical anti-apoptotic functionality of BCL-w is mediated by a surface groove that traps the BCL-2 homology 3 (BH3) α-helices of pro-apoptotic members, blocking cell death. A distinct N-terminal portion of BCL-w, termed the BCL-2 homology 4 (BH4) domain, selectively protects axons from paclitaxel-induced degeneration by modulating IP3 receptors, a noncanonical BCL-2 family target. Given the potential of BCL-w BH4 mimetics to prevent or mitigate chemotherapy-induced peripheral neuropathy, we sought to characterize the interaction between BCL-w BH4 and the IP3 receptor, combining "staple" and alanine scanning approaches with molecular dynamics simulations. We generated and identified stapled BCL-w BH4 peptides with optimized IP3 receptor binding and neuroprotective activities. Point mutagenesis further revealed the sequence determinants for BCL-w BH4 specificity, providing a blueprint for therapeutic targeting of IP3 receptors to achieve neuroprotection.

A PACAP-activated network for secretion requires coordination of Ca2+ influx and Ca2+ mobilization.

Chromaffin cells of the adrenal medulla transduce sympathetic nerve activity into stress hormone secretion. The two neurotransmitters principally responsible for coupling cell stimulation to secretion are acetylcholine and pituitary adenylate activating polypeptide (PACAP). In contrast to acetylcholine, PACAP evokes a persistent secretory response from chromaffin cells. However, the mechanisms by which PACAP acts are poorly understood. Here, it is shown that PACAP induces sustained increases in cytosolic Ca2+ which are disrupted when Ca2+ influx through L-type channels is blocked or internal Ca2+ stores are depleted. PACAP liberates stored Ca2+ via inositol trisphosphate receptors (IP3Rs) on the endoplasmic reticulum (ER), thereby functionally coupling Ca2+ mobilization to Ca2+ influx and supporting Ca2+-induced Ca2+-release. These Ca2+ influx and mobilization pathways are unified by an absolute dependence on phospholipase C epsilon (PLCε) activity. Thus, the persistent secretory response that is a defining feature of PACAP activity, in situ, is regulated by a signaling network that promotes sustained elevations in intracellular Ca2+ through multiple pathways.

Phospholipase C-β3 is dispensable for vascular constriction but indispensable for vascular hyperplasia

Angiotensin II (AngII) induces the contraction and proliferation of vascular smooth muscle cells (VSMCs). AngII activates phospholipase C-β (PLC-β), thereby inducing Ca2+ mobilization as well as the production of reactive oxygen species (ROS). Since contraction is a unique property of contractile VSMCs, signaling cascades related to the proliferation of VSMCs may differ. However, the specific molecular mechanism that controls the contraction or proliferation of VSMCs remains unclear. AngII-induced ROS production, migration, and proliferation were suppressed by inhibiting PLC-β3, inositol trisphosphate (IP3) receptor, and NOX or by silencing PLC-β3 or NOX1 but not by NOX4. However, pharmacological inhibition or silencing of PLC-β3 or NOX did not affect AngII-induced VSMC contraction. Furthermore, the AngII-dependent constriction of mesenteric arteries isolated from PLC-β3∆SMC, NOX1−/−, NOX4−/− and normal control mice was similar. AngII-induced VSMC contraction and mesenteric artery constriction were blocked by inhibiting the L-type calcium channel Rho-associated kinase 2 (ROCK2) or myosin light chain kinase (MLCK). The activation of ROCK2 and MLCK was significantly induced in PLC-β3∆SMC mice, whereas the depletion of Ca2+ in the extracellular medium suppressed the AngII-induced activation of ROCK2, MLCK, and vasoconstriction. AngII-induced hypertension was significantly induced in NOX1−/− and PLC-β3∆SMC mice, whereas LCCA ligation-induced neointima formation was significantly suppressed in NOX1−/− and PLC-β3∆SMC mice. These results suggest that PLC-β3 is essential for vascular hyperplasia through NOX1-mediated ROS production but is nonessential for vascular constriction or blood pressure regulation.

Impact of selexipag maintenance dose on persistence, adherence, and hospitalization in US patients with pulmonary arterial hypertension.

Selexipag is an oral selective agonist of the prostacyclin receptor approved to treat adults with pulmonary arterial hypertension (PAH). Selexipag is initiated at a dose of 200 μg twice daily (bid) and usually titrated up by 200 μg bid weekly (per label) or more slowly (e.g., every other week in real-world clinical practice) to the highest tolerated individualized dose (ID) ranging from 200 to 1600 µg bid. In the Phase 3 GRIPHON trial, selexipag delayed disease progression and reduced risk of PAH-related hospitalization compared with placebo; the effect was consistent across three prespecified ID groups: low (200-400 µg bid), medium (600-1000 µg bid), and high (1200-1600 µg bid). This study evaluated patient outcomes across selexipag dose ranges in real-world practice. Data were analyzed from 1186 US adult patients with PAH on selexipag from the Komodo closed-claims database (2015‒2022). Of these, 634 (53.5%) patients completed titration and reached their selexipag ID (43.8% high ID, 29.8% medium ID, 26.3% low ID). Subsequently, 72.4% of patients in the low ID group had dose adjustments compared with 61.9% (medium ID) and 34.5% (high ID; standardized mean difference 0.63). There were no significant differences in patient outcomes, i,e, persistence (time to discontinuation) and risk of all-cause and PAH-related hospitalization across ID groups. The findings in this diverse, real-world population of patients with PAH reinforced an individualized approach to the dosing scheme to maximize benefit-risk and achieve the highest tolerated dose with selexipag similar to findings from the GRIPHON trial and other studies.

NRF2-dependent regulation of the prostacyclin receptor PTGIR drives CD8 T cell exhaustion.

The progressive decline of CD8 T cell effector function-also known as terminal exhaustion-is a major contributor to immune evasion in cancer. Yet, the molecular mechanisms that drive CD8 T cell dysfunction remain poorly understood. Here, we report that the Kelch-like ECH-associated protein 1 (KEAP1)-Nuclear factor erythroid 2-related factor 2 (NRF2) signaling axis, which mediates cellular adaptations to oxidative stress, directly regulates CD8 T cell exhaustion. Transcriptional profiling of dysfunctional CD8 T cells from chronic infection and cancer reveals enrichment of NRF2 activity in terminally exhausted (Texterm) CD8 T cells. Increasing NRF2 activity in CD8 T cells (via conditional deletion of KEAP1) promotes increased glutathione production and antioxidant defense yet accelerates the development of terminally exhausted (PD-1+TIM-3+) CD8 T cells in response to chronic infection or tumor challenge. Mechanistically, we identify PTGIR, a receptor for the circulating eicosanoid prostacyclin, as an NRF2-regulated protein that promotes CD8 T cell dysfunction. Silencing PTGIR expression restores the anti-tumor function of KEAP1-deficient T cells. Moreover, lowering PTGIR expression in CD8 T cells both reduces terminal exhaustion and enhances T cell effector responses (i.e. IFN-γ and granzyme production) to chronic infection and cancer. Together, these results establish the KEAP1-NRF2 axis as a metabolic sensor linking oxidative stress to CD8 T cell dysfunction and identify the prostacyclin receptor PTGIR as an NRF2-regulated immune checkpoint that regulates CD8 T cell fate decisions between effector and exhausted states.

Expression of ITPR2 regulated by lncRNA-NONMMUT020270.2 in LPS-stimulated HT22 cells

BackgroundLong non-coding RNA (lncRNA)-NONMMUT020270.2 is downregulated and co-expressed with inositol 1,4,5-trisphosphate receptor type 2 (ITPR2) in the hippocampus of Alzheimer's disease (AD) mice. However, whether the expression of ITPR2 was regulated by lncRNA-NONMMUT020270.2 remains unclear. we aimed to investigate regulating relationship of lncRNA-NONMMUT020270.2 and ITPR2. MethodsHT22 cells were firstly transfected with the pcDNA3.1-lncRNA-NONMMUT020270.2 overexpression plasmid or with the lncRNA-NONMMUT020270.2 smart silencer, and then were stimulated with lipopolysaccharide (LPS) for 24h. The mRNA expression levels of lncRNA-NONMMUT020270.2 and ITPR2 were measured by reverse transcription-quantitative PCR. Cell viability was assessed using a Cell Counting Kit 8 assay. The expression of Aβ1-42 was detected by ELISA. The expression levels of p-tau, caspase-1, and inositol trisphosphate receptor (IP3R) proteins were detected by western-blotting. Nuclear morphological changes were detected by Hoechst staining. Flow cytometry and Fluo-3/AM were carried out to determine cell apoptosis and the intracellular Ca2+. ResultsLPS significantly decreased cell viability, and ITPR2 mRNA and IP3R protein expression levels. While it markedly enhanced the expression levels of p-tau and Aβ1-42, cell apoptosis rate, as well as intracellular Ca2+ concentration (P < 0.05). In addition, lncRNA-NONMMUT020270.2 overexpression significantly increased the expressions levels of ITPR2 mRNA and IP3R protein (P < 0.05), and inhibited expression of p-tau and Aβ1-42, cell apoptosis rate, and reduced intracellular Ca2+ concentration (P < 0.05). By contrast, lncRNA-NONMMUT020270.2 silencing notably downregulated expressions levels of ITPR2 mRNA and IP3R protein (P < 0.05), and elevated expression levels of p-tau and Aβ1-42, cell apoptosis rate, and intracellular Ca2+ concentration (P < 0.05). ConclusionlncRNA-NONMMUT020270.2 was positively correlated with ITPR2 expression in LPS-induced cell. Downregulating the lncRNA-NONMMUT020270.2 and ITPR2 may promote cell apoptosis and increase intracellular Ca2+ concentration.

Pharmacoinformational, basic and clinical studies of 7-hydroxymatairesinol in the context of searching for effective and safe therapeutic approaches to the treatment of mastopathy

7-hydroxymatairesinol (7(OH)MR) is the main lignan of spruce extracts, characterized by oncoprotective and anti-inflammatory properties. The results of chemoreactome modeling made it possible to formulate the molecular mechanisms of the pharmacological effects of 7(OH)MR for anti-inflammatory (inhibition of 5-lipoxygenase, matrix metalloproteinase MMP2, mitogen-activated kinase p38-alpha, leukotriene b4 receptor, prostacyclin receptor), oncoprotective (antioxidant effect due to inhibition heme oxygenase-2, inhibition of cyclin-dependent kinases 3 and 4, epidermal growth factor, mTOR protein). An assessment of the transcriptomic effects of 7(OH)MR in breast cancer cells showed significant dose-dependent effects on the transcription of 3468 of 12700 genes. The 7(OH)MR molecule, reducing the expression of proliferative genes (401 genes) and chronic inflammation (148 genes), while simultaneously increasing the transcription of oncoprotective immunity genes (100 genes), inhibits the proliferation of tumor cells. Experiments on solid Ehrlich carcinoma showed a significant oncoprotective effect of 7(OH)MR at doses of 60, 120 mg/day, even while taking estrogen (p = 0.007). A clinical study showed that 7(OH)MR (60 mg/day, 1 month) helps normalize estrogen metabolism and improve the clinical symptoms of mastopathy.