STIM1 Research Articles

Water in peripheral TM-interfaces of Orai1-channels triggers pore opening.

The activation of the Ca2+-channel Orai1 via the physiological activator stromal interaction molecule 1 (STIM1) requires structural rearrangements within the entire channel complex involving a series of gating checkpoints. Focusing on the gating mechanism operating along the peripheral transmembrane domain (TM) 3/TM4-interface, we report here that some charged substitutions close to the center of TM3 or TM4 lead to constitutively active Orai1 variants triggering nuclear factor of activated T-cell (NFAT) translocation into the nucleus. Molecular dynamics simulations unveil that this gain-of-function correlates with enhanced hydration at peripheral TM-interfaces, leading to increased local structural flexibility of the channel periphery and global conformational changes permitting pore opening. Our findings indicate that efficient dehydration of the peripheral TM-interfaces driven by the hydrophobic effect is critical for maintaining the closed state of Orai1. We conclude that a charge close to the center of TM3 or TM4 facilitates concomitant hydration and widening of peripheral TM interfaces to trigger constitutive Orai1 pore opening to a level comparable to or exceeding that of native activated Orai1.

Hydrogen peroxide disrupts the regulatory pathway of saliva secretion in two salivary acinar rat cell lines

BackgroundSecretion of saliva is controlled by autonomic nerve signals via regulation of Ca2+-dependent ion transport across acinar cell membranes. Oxidative stress may affect this process, leading to a decrease in saliva production. This study investigates elements of the Ca2+ regulatory pathway and their vulnerability to hydrogen peroxide-induced oxidative stress.MethodsRat parotid and submandibular salivary gland acinar cell lines were exposed to different hydrogen peroxide concentrations to simulate oxidative stress. Cell viability and intracellular reactive oxygen species were measured, mRNA levels were assessed via RT-qPCR, and protein expression was studied using western blot and immunofluorescence microscopy.ResultsElevated concentrations of hydrogen peroxide reduced cell viability and increased intracellular levels of reactive oxygen species and led to a decrease in cholinergic receptor muscarinic 3 and adrenoreceptor alpha 1A mRNA and protein levels in both cell lines. In parotid gland cells, both mRNA and protein levels of stromal interaction molecule 1 and Orai1 decreased with increasing concentrations of hydrogen peroxide. In contrast, in submandibular gland cells stromal interaction molecule 1 and Orai1 displayed differential mRNA and protein expression levels.ConclusionOur study revealed that hydrogen peroxide exposure alters rat parotid and submandibular acinar cells, increasing reactive oxygen species and reducing autonomic receptor expression. Differential mRNA and protein expression of stromal interaction molecule 1 and Orai1 highlight complex oxidative stress effects on Ca2⁺ signaling. Most likely these effects will be deleterious to salivary secretion, but some effects may be protective.

SLC35G1 is a highly chloride-sensitive transporter responsible for the basolateral membrane transport in intestinal citrate absorption.

The intestinal absorption of essential nutrients, especially those not readily biosynthesized, is a critical physiological process for maintaining homeostasis. Numerous studies have indicated that intestinal absorption is mediated by various membrane transporters. Citrate, a crucial bioactive compound produced as an intermediate in the Krebs cycle, is absorbed in the small intestine through carrier-mediated systems because of its high hydrophilicity. While the luminal absorption of citrate is mediated by Na+-dicarboxylate cotransporter 1 (NaDC1/SLC13A2), the mechanism governing the release of the transported citrate into the bloodstream remains unknown. Here, we explored the transporters responsible for intestinal citrate absorption at the basolateral membrane, focusing on highly expressed orphan transporters in the small intestine as candidates. Consequently, SLC35G1, originally identified as a partner of stromal interaction molecule 1, a cell surface transmembrane glycoprotein, was found to play a role in the intestinal absorption of citrate at the basolateral membrane. Furthermore, our results revealed that SLC35G1-mediated citrate transport was diminished by chloride ions at physiologically relevant extracellular concentrations. This suggests that SLC35G1, to our best knowledge, is the first transporter identified to be extremely sensitive to chloride ions among those functioning on the basolateral membrane of intestinal epithelial cells. This study provides valuable insights into the intestinal absorption of citrate and significantly contributes to elucidating the poorly understood molecular basis of the intestinal absorption system.

Rap1A Modulates Store-Operated Calcium Entry in the Lung Endothelium: A Novel Mechanism Controlling NFAT-Mediated Vascular Inflammation and Permeability.

Store-operated calcium entry mediated by STIM (stromal interaction molecule)-1-Orai1 is essential in endothelial cell (EC) functions, affecting signaling, NFAT (nuclear factor for activated T cells)-induced transcription, and metabolic programs. While the small GTPase Rap1 isoforms, including the predominant Rap1B, are known for their role in cadherin-mediated adhesion, EC deletion of Rap1A after birth uniquely disrupts lung endothelial barrier function. Here, we elucidate the specific mechanisms by which Rap1A modulates lung vascular integrity and inflammation. The role of EC Rap1A in lung inflammation and permeability was examined using in vitro and in vivo approaches. We explored Ca2+ signaling in human ECs following siRNA-mediated knockdown of Rap1A or Rap1B. Rap1A knockdown, unlike Rap1B, significantly increased store-operated calcium entry in response to a GPCR (G-protein-coupled receptor) agonist, ATP (500 µmol/L), or thapsigargin (250 nmol/L). This enhancement was attenuated by Orai1 channel blockers 10 μmol/L BTP2, 10 μmol/L GSK-7975A, and 5 μmol/L Gd3+. Whole-cell patch clamp measurements revealed enhanced Ca2+ release-activated Ca2+ current density in siRap1A ECs. Rap1A depletion in ECs led to increased NFAT1 nuclear translocation and activity and elevated levels of proinflammatory cytokines (CXCL1, CXCL11, CCL5 [chemokine (C-C motif) ligand 5], and IL-6 [interleukin-6]). Notably, reducing Orai1 expression in siRap1A ECs normalized store-operated calcium entry, NFAT activity, and endothelial hyperpermeability in vitro. EC-specific Rap1A knockout (Rap1AiΔEC) mice displayed an inflammatory lung phenotype with increased lung permeability and inflammation markers, along with higher Orai1 expression. Delivery of siRNA against Orai1 to lung endothelium using lipid nanoparticles effectively normalized Orai1 levels in lung ECs, consequently reducing hyperpermeability and inflammation in Rap1AiΔEC mice. Our findings uncover a novel role of Rap1A in regulating Orai1-mediated Ca2+ entry and expression, crucial for NFAT-mediated transcription and endothelial inflammation. This study distinguishes the unique function of Rap1A from that of the predominant Rap1B isoform and highlights the importance of normalizing Orai1 expression in maintaining lung vascular integrity and modulating endothelial functions.

EGF/EGFR-YAP1/TEAD2 signaling upregulates STIM1 in vemurafenib resistant melanoma cells.

Stromal interaction molecule 1 (STIM1) is the endoplasmic reticulum Ca2+ sensor for store-operated calcium entry and is closely associated with carcinogenesis and tumor progression. Previously, we found that STIM1 is upregulated in melanoma cells resistant to the serine/threonine-protein kinase B-raf inhibitor vemurafenib, although the mechanism underlying this upregulation is unknown. Here, we show that vemurafenib resistance upregulates STIM1 through an epidermal growth factor (EGF)/epidermal growth factor receptor (EGFR)-Yes-associated protein 1 (YAP1)/TEA domain transcription factor 2 (TEAD2) signaling axis. Vemurafenib resistance can lead to an increase in EGF and EGFR levels, causing activation of the EGFR signaling pathway, which promotes YAP1 nuclear localization to increase the expression of STIM1. Our findings not only reveal the mechanism by which vemurafenib resistance promotes STIM1 upregulation, but also provide a rationale for combined targeting of the EGF/EGFR-YAP1/TEAD2-STIM1 axis to improve the therapeutic efficacy of BRAF inhibitor in melanoma patients.

The p53 target DRAM1 modulates calcium homeostasis and ER stress by promoting contact between lysosomes and the ER through STIM1

It is well established that DNA Damage Regulated Autophagy Modulator 1 (DRAM1), a lysosomal protein and a target of p53, participates in autophagy. The cellular functions of DRAM1 beyond autophagy remain elusive. Here, we show p53-dependent upregulation of DRAM1 in mitochondrial damage-induced Parkinson's disease (PD) models and exacerbation of disease phenotypes by DRAM1. We find that the lysosomal location of DRAM1 relies on its intact structure including the cytosol-facing C-terminal domain. Excess DRAM1 disrupts endoplasmic reticulum (ER) structure, triggers ER stress, and induces protective ER-phagy. Mechanistically, DRAM1 interacts with stromal interacting molecule 1 (STIM1) to tether lysosomes to the ER and perturb STIM1 function in maintaining intracellular calcium homeostasis. STIM1 overexpression promotes cellular health by restoring calcium homeostasis, ER stress response, ER-phagy, and AMP-activated protein kinase (AMPK)-Unc-51 like autophagy activating kinase 1 (ULK1) signaling in cells with excess DRAM1. Thus, by promoting organelle contact between lysosomes and the ER, DRAM1 modulates ER structure and function and cell survival under stress. Our results suggest that DRAM1 as a lysosomal protein performs diverse roles in cellular homeostasis and stress response. These findings may have significant implications for our understanding of the role of the p53/DRAM1 axis in human diseases, from cancer to neurodegenerative diseases.

Computational Model of Complex Calcium Dynamics: Store Operated Ca2+ Channels and Mitochondrial Associated Membranes in Pancreatic Acinar Cells.

This proposed model explores the intricate Ca2+ dynamics within the pancreatic acinar cells (PACs) by emphasizing the role of store-operated Ca2+ entry (SOCE) and the mitochondrial-associated membranes (MAMs) in the secretory region (apical) of the PACs. Traditionally, Ca2+ releases from the endoplasmic reticulum (ER) via calcium-induced calcium release (CICR). It has been shown to be important in regulating functions such as secretion of digestive enzymes in PACs. However, this model posits that upon the depletion of Ca2+ in the ER, the signaling protein stromal interaction molecule (STIM1) is activated. Activated STIM1, then facilitates the opening of Orai channels, allowing Ca2+ influx through the store-operated calcium channels (SOCCs). The model highlights the complexity of the Ca2+ dynamics, and the importance of SOCE and MAMs in the PACs Ca2+ homeostasis. The numerical and bifurcation analysis illustrate how changes in agonist concentrations can lead to the diverse Ca2+ oscillation patterns, such as thin to broader oscillations, sinusoidal patterns, and baseline fluctuations, driven by the feedback mechanisms involving Ca2+ and inositol 1,4,5 trisphosphate (IP3). This understanding could have broader implications for cellular physiology and the development of therapies targeting Ca2+ signaling pathways.

STIM Proteins: The Gas and Brake of Calcium Entry in Neurons.

Stromal interaction molecules (STIM)s are Ca2+ sensors in internal Ca2+ stores of the endoplasmic reticulum. They activate the store-operated Ca2+ channels, which are the main source of Ca2+ entry in non-excitable cells. Moreover, STIM proteins interact with other Ca2+ channel subunits and active transporters, making STIMs an important intermediate molecule in orchestrating a wide variety of Ca2+ influxes into excitable cells. Nevertheless, little is known about the role of STIM proteins in brain functioning. Being involved in many signaling pathways, STIMs replenish internal Ca2+ stores in neurons and mediate synaptic transmission and neuronal excitability. Ca2+ dyshomeostasis is a signature of many pathological conditions of the brain, including neurodegenerative diseases, injuries, stroke, and epilepsy. STIMs play a role in these disturbances not only by supporting abnormal store-operated Ca2+ entry but also by regulating Ca2+ influx through other channels. Here, we review the present knowledge of STIMs in neurons and their involvement in brain pathology.

Identification of Noncoding Functional Regulatory Variants of STIM1 Gene in Idiopathic Pulmonary Arterial Hypertension.

STIM1 (stromal interaction molecule 1) regulates store-operated calcium entry and is involved in pulmonary artery vasoconstriction and pulmonary artery smooth muscle cell proliferation, leading to pulmonary arterial hypertension (PAH). Bioinformatics analysis and a 2-stage matched case-control study were conducted to screen for noncoding variants that may potentially affect STIM1 transcriptional regulation in 242 patients with idiopathic PAH and 414 healthy controls. Luciferase reporter assay, real-time quantitative polymerase chain reaction, western blot, 5-ethynyl-2'-deoxyuridine (EdU) assay, and intracellular Ca2+ measurement were performed to study the mechanistic roles of those STIM1 noncoding variants in PAH. Five noncoding variants (rs3794050, rs7934581, rs3750996, rs1561876, and rs3750994) were identified and genotyped using Sanger sequencing. Rs3794050, rs7934581, and rs1561876 were associated with idiopathic PAH (recessive model, all P<0.05). Bioinformatics analysis showed that these 3 noncoding variants possibly affect the enhancer function of STIM1 or the microRNA (miRNA) binding to STIM1. Functional validation performed in HEK293 and pulmonary artery smooth muscle cells demonstrated that the noncoding variant rs1561876-G (STIM1 mutant) had significantly stronger transcriptional activity than the wild-type counterpart, rs1561876-A, by affecting the transcriptional regulatory function of both hsa-miRNA-3140-5p and hsa-miRNA-4766-5p. rs1561876-G enhanced intracellular Ca2+ signaling in human pulmonary artery smooth muscle cells secondary to calcium-sensing receptor activation and promoted proliferation of pulmonary artery smooth muscle cells under both normoxia and hypoxia conditions, suggesting a possible contribution to PAH development. The potential clinical implications of the 3 noncoding variants of STIM1, rs3794050, rs7934581, and rs1561876, are 2-fold, as they may help predict the risk and prognosis of idiopathic PAH and guide investigations on novel therapeutic pathway(s).

Discovery of selective Orai channel blockers bearing an indazole or a pyrazole scaffold

The calcium release activated calcium (CRAC) channel is highly expressed in T lymphocytes and plays a critical role in regulating T cell proliferation and functions including activation of the transcription factor nuclear factor of activated T cells (NFAT), cytokine production and cytotoxicity. The CRAC channel consists of the Orai pore subunit and STIM (stromal interacting molecule) endoplasmic reticulum calcium sensor. Loss of CRAC channel mediated calcium signaling has been identified as an underlying cause of severe combined immunodeficiency (SCID), leading to drastically weakened immunity against infections. Gain-of-function mutations in Orai and STIM have been associated with tubular aggregated myopathy (TAM), a skeletal muscle disease. While a number of small molecules have shown activity in inhibiting the CRAC signaling pathway, the usefulness of those tool compounds is limited by their off-target activity against TRPM4 and TRPM7 ion channels, high lipophilicity, and a lack of understanding of their mechanism of action. We report structure-activity relationship (SAR) studies that resulted in the characterization of compound 4k [1-(cyclopropylmethyl)-N-(3-fluoropyridin-4-yl)-1H-indazole-3-carboxamie] as a fast onset, reversible, and selective CRAC channel blocker. 4k fully blocked the CRAC current (IC50: 4.9 μM) and the nuclear translocation of NFAT at 30 and 10 μM, respectively, without affecting the electrophysiological function of TRPM4 and TRPM7 channels. Computational modeling appears to support its direction binding to Orai proteins that form the transmembrane CRACchannel.

L-type Ca2+ channel activation of STIM1–Orai1 signaling remodels the dendritic spine ER to maintain long-term structural plasticity

Learning and memory require coordinated structural and functional plasticity at neuronal glutamatergic synapses located on dendritic spines. Here, we investigated how the endoplasmic reticulum (ER) controls postsynaptic Ca2+ signaling and long-term potentiation of dendritic spine size, i.e., sLTP that accompanies functional strengthening of glutamatergic synaptic transmission. In most ER-containing (ER+) spines, high-frequency optical glutamate uncaging (HFGU) induced long-lasting sLTP that was accompanied by a persistent increase in spine ER content downstream of a signaling cascade engaged by N-methyl-D-aspartate receptors (NMDARs), L-type Ca2+ channels (LTCCs), and Orai1 channels, the latter being activated by stromal interaction molecule 1 (STIM1) in response to ER Ca2+ release. In contrast, HFGU stimulation of ER-lacking (ER-) spines expressed only transient sLTP and exhibited weaker Ca2+ signals noticeably lacking Orai1 and ER contributions. Consistent with spine ER regulating structural metaplasticity, delivery of a second stimulus to ER- spines induced ER recruitment along with persistent sLTP, whereas ER+ spines showed no additional increases in size or ER content in response to sequential stimulation. Surprisingly, the physical interaction between STIM1 and Orai1 induced by ER Ca2+ release, but not the resulting Ca2+ entry through Orai1 channels, proved necessary for the persistent increases in both spine size and ER content required for expression of long-lasting late sLTP.

Sodium butyrate prevents cytokine-induced β-cell dysfunction through restoration of stromal interaction molecule 1 expression and activation of store-operated calcium entry.

Sodium butyrate (NaB) improves β-cell function in preclinical models of diabetes; however, the mechanisms underlying these beneficial effects have not been fully elucidated. In this study, we investigated the impact of NaB on β-cell function and calcium (Ca2+) signaling using exvivo and invitro models of diabetes. Our results show that NaB significantly improved glucose-stimulated insulin secretion in islets from human organ donors with type 2 diabetes and in cytokine-treated INS-1 β cells. Consistently, NaB improved glucose-stimulated Ca2+ oscillations in mouse islets treated with proinflammatory cytokines. Because the oscillatory phenotype of Ca2+ in the β cell is governed by changes in endoplasmic reticulum (ER) Ca2+ levels, we explored the relationship between NaB and store-operated calcium entry (SOCE), a rescue mechanism that acts to refill ER Ca2+ levels through STIM1-mediated gating of plasmalemmal Orai channels. We found that NaB treatment preserved basal ER Ca2+ levels and restored SOCE in IL-1β-treated INS-1 cells. Furthermore, we linked these changes with the restoration of STIM1 levels in cytokine-treated INS-1 cells and mouse islets, and we found that NaB treatment was sufficient to prevent β-cell death in response to IL-1β treatment. Mechanistic experiments revealed that NaB mediated these beneficial effects in the β-cell through histone deacetylase (HDAC) inhibition, iNOS suppression, and modulation of AKT-GSK-3 signaling. Taken together, these data support a model whereby NaB treatment promotes β-cell function and Ca2+ homeostasis under proinflammatory conditions through pleiotropic effects that are linked with maintenance of SOCE. These results also suggest a relationship between β-cell SOCE and gut microbiome-derived butyrate that may be relevant in the treatment and prevention of diabetes.

Generalised Neuronal Calcium Dynamics of Membrane and ER in the Polar Dimension.

Calcium ions are the second messenger playing as regulators for various cellular activities. Its spatiotemporal control is critical for various brain functions, including neuroplasticity, apoptosis, and cell death. The Endoplasmic Reticulum (ER) plays an important role in determining these spatiotemporal calcium dynamics. Stromal interaction molecule (STIM) - Orai channel on the membrane generates additional calcium flow, whereas other membrane fluxes contribute to cytosolic flux. Due to their anomalous character, we used the Caputo fractional differential operator to mimic these interactions in polar coordinates. Solutions were generated using hybrid integral transform methods to control the analytical approach. Using Green's function yielded a closed-form solution for Mittag-Leffler-type functions. This work emphasizes the significant relationship between calcium and various buffer levels in neurons. The differential transition simulation of a time derivative with space across different parameters indicated a decrease in calcium concentration. Anomalously low buffer levels exhibited the impact of Alzheimer's disease on calcium higher concentration, leading to the death of neurons. Additionally, the research introduces a method involving S100B, BAPTA, and calmodulin buffers to uphold optimal calcium levels within the neuronal cytosol. The applicability of this model with different buffer properties and parameters and memory impacts the calcium concentration with the neurological disorder.

Downregulation of stromal interaction molecule-1 is implicated in the age-associated vasoconstriction dysfunction of aorta, intrarenal, and coronary arteries

The contractile function of vascular smooth muscle cells (VSMCs) typically undergoes significant changes with advancing age, leading to severe vascular aging-related diseases. The precise role and mechanism of stromal interaction molecule-1 (STIM1) in age-mediated Ca2+ signaling and vasocontraction remain unclear. The connection between STIM1 and age-related vascular dysfunction was investigated using a multi-myograph system, immunohistochemical analysis, protein blotting, and SA-β-gal staining. Results showed that vasoconstrictor responses in the thoracic aorta, intrarenal artery, and coronary artery decreased with age. STIM1 knockdown in the intrarenal and coronary arteries reduced vascular tone in young mice, while no change was observed in the thoracic aorta. A significant reduction in vascular tone occurred in the STIM1 knockout group with nifedipine. In the thoracic aorta, vasoconstriction significantly decreased with age following the use of nifedipine and thapsigargin and almost disappeared after STIM1 knockdown. The proportion of senescent VSMCs increased significantly in aged mice and further increased in sm-STIM1 KO aged mice. Moreover, the expression of senescence markers p21, p16, and IL-6 significantly increased with age, with p21 expression further increased in the STIM1 knockdown aged group, but not p16 or IL-6. These findings indicate that different arteries exhibit distinct organ-specific features and that STIM1 downregulation may contribute to age-related vasoconstrictive dysfunction through activation of the p21 pathway.

Loss of Calpain 3 dysregulates store-operated calcium entry and its exercise response in mice.

Limb-Girdle Muscular Dystrophy R1/2A (LGMD R1/2A) is caused by mutations in the CAPN3 gene encoding Calpain 3, a skeletal-muscle specific, Ca2+-dependent protease. Localization of Calpain 3 within the triad suggests it contributes to Ca2+ homeostasis. Through live-cell Ca2+ measurements, muscle mechanics, immunofluorescence, and electron microscopy (EM) in Capn3 deficient (C3KO) and wild-type (WT) mice, we determined whether loss of Calpain 3 altered Store-Operated Calcium Entry (SOCE) activity. Direct Ca2+ influx measurements revealed loss of Capn3 elicits elevated resting SOCE and increased resting cytosolic Ca2+, supported by high incidence of calcium entry units (CEUs) observed by EM. C3KO and WT mice were subjected to a single bout of treadmill running to elicit SOCE. Within 1HR post-treadmill running, C3KO mice exhibited diminished force production in extensor digitorum longus muscles and a greater decay of Ca2+ transients in flexor digitorum brevis muscle fibers during repetitive stimulation. Striking evidence for impaired exercise-induced SOCE activation in C3KO mice included poor colocalization of key SOCE proteins, stromal-interacting molecule 1 (STIM1) and ORAI1, combined with disappearance of CEUs in C3KO muscles. These results demonstrate that Calpain 3 is a key regulator of SOCE in skeletal muscle and identify SOCE dysregulation as a contributing factor to LGMD R1/2A pathology.

Store-operated calcium entry dysfunction in CRAC channelopathy: Insights from a novel STIM1 mutation

Store-operated calcium entry (SOCE) plays a crucial role in maintaining cellular calcium homeostasis. This mechanism involves proteins, such as stromal interaction molecule 1 (STIM1) and ORAI1. Mutations in the genes encoding these proteins, especially STIM1, can lead to various diseases, including CRAC channelopathies associated with severe combined immunodeficiency. Herein, we describe a novel homozygous mutation, NM_003156 c.792-3C > G, in STIM1 in a patient with a clinical profile of CRAC channelopathy, including immune system deficiencies and muscle weakness. Functional analyses revealed three distinct spliced forms in the patient cells: wild-type, exon 7 skipping, and intronic retention. Calcium influx analysis revealed impaired SOCE in the patient cells, indicating a loss of STIM1 function. We developed an antisense oligonucleotide treatment that improves STIM1 splicing and highlighted its potential as a therapeutic approach. Our findings provide insights into the complex effects of STIM1 mutations and shed light on the multifaceted clinical presentation of the patient.

Novel insights into STIM1's role in store-operated calcium entry and its implications for T-cell mediated inflammation in trigeminal neuralgia.

This investigation aims to elucidate the novel role of Stromal Interaction Molecule 1 (STIM1) in modulating store-operated calcium entry (SOCE) and its subsequent impact on inflammatory cytokine release in T lymphocytes, thereby advancing our understanding of trigeminal neuralgia (TN) pathogenesis. Employing the Gene Expression Omnibus (GEO) database, we extracted microarray data pertinent to TN to identify differentially expressed genes (DEGs). A subsequent comparison with SOCE-related genes from the Genecards database helped pinpoint potential target genes. The STRING database facilitated protein-protein interaction (PPI) analysis to spotlight STIM1 as a gene of interest in TN. Through histological staining, transmission electron microscopy (TEM), and behavioral assessments, we probed STIM1's pathological effects on TN in rat models. Additionally, we examined STIM1's influence on the SOCE pathway in trigeminal ganglion cells using techniques like calcium content measurement, patch clamp electrophysiology, and STIM1- ORAI1 co-localization studies. Changes in the expression of inflammatory markers (TNF-α, IL-1β, IL-6) in T cells were quantified using Western blot (WB) and enzyme-linked immunosorbent assay (ELISA) in vitro, while immunohistochemistry and flow cytometry were applied in vivo to assess these cytokines and T cell count alterations. Our bioinformatic approach highlighted STIM1's significant overexpression in TN patients, underscoring its pivotal role in TN's etiology and progression. Experimental findings from both in vitro and in vivo studies corroborated STIM1's regulatory influence on the SOCE pathway. Furthermore, STIM1 was shown to mediate SOCE-induced inflammatory cytokine release in T lymphocytes, a critical factor in TN development. Supportive evidence from histological, ultrastructural, and behavioral analyses reinforced the link between STIM1-mediated SOCE and T lymphocyte-driven inflammation in TN pathogenesis. This study presents novel evidence that STIM1 is a key regulator of SOCE and inflammatory cytokine release in T lymphocytes, contributing significantly to the pathogenesis of trigeminal neuralgia. Our findings not only deepen the understanding of TN's molecular underpinnings but also potentially open new avenues for targeted therapeutic strategies.

STIM1 mediates methamphetamine-induced neuronal autophagy and apoptosis

Methamphetamine (METH) is a widely abused amphetamine-type psychoactive drug that causes serious health problems. Previous studies have demonstrated that METH can induce neuron autophagy and apoptosis in vivo and in vitro. However, the molecular mechanisms underlying METH-induced neuron autophagy and apoptosis remain poorly understood. Stromal interacting molecule 1 (STIM1) was hypothesized to be involved in METH-induced neuron autophagy and apoptosis. Therefore, the expression of STIM1 protein was measured and the effect of blocking STIM1 expression with siRNA was investigated in cultured neuronal cells, and the hippocampus and striatum of mice exposed to METH. Furthermore, intracellular calcium concentration and endoplasmic reticulum (ER) stress-related proteins were determined in vitro and in vivo in cells treated with METH. The results suggested that STIM1 mediates METH-induced neuron autophagy by activating the p-Akt/p-mTOR pathway. METH exposure also resulted in increased expression of Orai1, which was reversed after STIM1 silencing. Moreover, the disruption of intracellular calcium homeostasis induced ER stress and up-regulated the expression of pro-apoptotic protein CCAAT/enhancer-binding protein homologous protein (CHOP), resulting in classic mitochondria apoptosis. METH exposure can cause neuronal autophagy and apoptosis by increasing the expression of STIM1 protein; thus, STIM1 may be a potential gene target for therapeutics in METH-caused neurotoxicity.

STING orchestrates the neuronal inflammatory stress response in multiple sclerosis

Inflammation-induced neurodegeneration is a defining feature of multiple sclerosis (MS), yet the underlying mechanisms remain unclear. By dissecting the neuronal inflammatory stress response, we discovered that neurons in MS and its mouse model induce the stimulator of interferon genes (STING). However, activation of neuronal STING requires its detachment from the stromal interaction molecule 1 (STIM1), a process triggered by glutamate excitotoxicity. This detachment initiates non-canonical STING signaling, which leads to autophagic degradation of glutathione peroxidase 4 (GPX4), essential for neuronal redox homeostasis and thereby inducing ferroptosis. Both genetic and pharmacological interventions that target STING in neurons protect against inflammation-induced neurodegeneration. Our findings position STING as a central regulator of the detrimental neuronal inflammatory stress response, integrating inflammation with glutamate signaling to cause neuronal cell death, and present it as a tractable target for treating neurodegeneration in MS.

Proteomic insights into myopia development: Differential protein expression and the role of calcium signaling in form deprivation myopia in Guinea pigs

This study aims to explore the changes in the vitreous proteomics of form deprivation myopia (FDM) in guinea pigs, in order to reveal the molecular mechanisms involved in the onset and development of myopia. The myopia model in guinea pigs was successfully established by covering one eye of the guinea pigs with a latex bead sac for 4 weeks. This study used 4D data-independent acquisition proteomics technology to analyze vitreous body samples from both the FDM group and the control group. The goal of the proteomics analysis was to identify differences in protein expression within the vitreous body of FDM guinea pigs. Myopia was successfully induced in the FDM group after 4 weeks of modeling. A total of 6298 proteins were identified, among which 348 were differentially expressed proteins (DEPs), with 81 upregulated and 267 downregulated. These DEPs were subjected to in-depth bioinformatics analyses, including Gene Ontology, the Eukaryotic Orthologous Groups, and the Kyoto Encyclopedia of Genes and Genomes. These analyses revealed significant involvement in cellular processes, metabolic pathways, biological regulation, cytoskeletal organization, and cell movement. Our results indicate that calcium signaling plays a critical role in mediating eye changes associated with form deprivation, which may bear similarities to mechanisms observed in neurodegenerative diseases. A total of 348 DEPs related to the development and progression of myopia were identified. These changes involve key biological processes, including protein degradation, cell adhesion, and transport, especially alterations in calcium signaling pathways. Stromal interaction molecule 1 (STIM1) is an important biological marker of FDM, which was confirmed by Western blot, immunohistochemistry and ELISA. Our study found clear differences in the expression of proteins in the vitreous during the development of myopic guinea pigs, especially those related to calcium signaling pathway. Our study offers new insights into the pathogenesis of myopia, particularly changes related to protein metabolism pathways.