Mechanism of total flavonoids of Rhododendra simsii in alleviating ischemic brain injury / 中国中药杂志

This study explores the effect of total flavonoids of Rhododendra simsii(TFR) on middle cerebral artery occlusion(MCAO)-induced cerebral injury in rats and oxygen-glucose deprivation/reoxygenation(OGD/R) injury in PC12 cells and the underlying mechanism. The MCAO method was used to induce focal ischemic cerebral injury in rats. Male SD rats were randomized into sham group, model group, and TFR group. After MCAO, TFR(60 mg·kg~(-1)) was administered for 3 days. The content of tumor necrosis factor-α(TNF-α), interleukin-1(IL-1), and interleukin-6(IL-6) in serum was detected by enzyme-linked immunosorbent assay(ELISA). The pathological changes of brain tissue and cerebral infarction were observed based on hematoxylin and eosin(HE) staining and 2,3,5-triphenyltetrazolium chloride(TTC) staining. RT-qPCR and Western blot were used to detect the mRNA and protein levels of calcium release-activated calcium channel modulator 1(ORAI1), stromal interaction molecule 1(STIM1), stromal intera-ction molecule 2(STIM2), protein kinase B(PKB), and cysteinyl aspartate specific proteinase 3(caspase-3) in brain tissues. The OGD/R method was employed to induce injury in PC12 cells. Cells were randomized into the normal group, model group, gene silencing group, TFR(30 μg·mL~(-1)) group, and TFR(30 μg·mL~(-1))+gene overexpression plasmid group. Intracellular Ca~(2+) concentration and apoptosis rate of PC12 cells were measured by laser scanning confocal microscopy and flow cytometry. The effect of STIM-ORAI-regulated store-operated calcium entry(SOCE) pathway on TFR was explored based on gene silencing and gene overexpression techniques. The results showed that TFR significantly alleviated the histopathological damage of brains in MCAO rats after 3 days of admini-stration, reduced the contents of TNF-α, IL-1, and IL-6 in the serum, down-regulated the expression of ORAI1, STIM1, STIM2, and caspase-3 genes, and up-regulated the expression of PKB gene in brain tissues of MCAO rats. TFR significantly decreased OGD/R induced Ca~(2+) overload and apoptosis in PC12 cells. However, it induced TFR-like effect by ORAI1, STIM1 and STIM2 genes silencing. However, overexpression of these genes significantly blocked the effect of TFR in reducing Ca~(2+) overload and apoptosis in PC12 cells. In summary, in the early stage of focal cerebral ischemia-reperfusion injury and OGD/R-induced injury in PC12 cells TFR attenuates ischemic brain injury by inhibiting the STIM-ORAI-regulated SOCE pathway and reducing Ca~(2+) overload and inflammatory factor expression, and apoptosis.

Expression and function of Orai1-BK Ca complex in high glucose treatment rat glomerular mesangial cells / 中国药理学通报

Aim To investigate whether Orai1 and BKCa form a physical and functional signal complex in glomerular mesangial cells ( GMCs) and reveal the role of high glucose treatment on Orai1-BKCa complex and SOCE-induced hyperpolarization. Methods The in-teraction of Orai1 and BKCa was evaluated by co-immu-noprecipitation ( co-IP ) . Western blot method was used to detect the expression levels of Orai1 and BKCa . SOCE was activated by Ca2+ depletion evoked by TG in normal glucose and high glucose. The DiBAC4(3) was employed as fluorescence indicator to measure the potential change of membrane. . Results The co-IP experiment results showed that Orai1 interacted with BKCa in GMCs. SOCE induced the hyperpolarization of GMCs. SOCE and SOCE-induced membrane hyperpol-orizaiton were enhanced by high glucose treatment for three days. In addition, the expression levels of Orai1 and BKCa were enhanced significantly in the high glu-cose-cultured cells. Conclusions Orai1 can form a signaling complex with BKCa , which participates in the regulation of hyperpolarization in GMCs and may be in-volved in the hyperpolarization in high glucose cultured GMCs.

Orai1 and Orai3 in Combination with Stim1 Mediate the Majority of Store-operated Calcium Entry in Astrocytes

Astrocytes are non-excitable cells in the brain and their activity largely depends on the intracellular calcium (Ca²⁺) level. Therefore, maintaining the intracellular Ca²⁺ homeostasis is critical for proper functioning of astrocytes. One of the key regulatory mechanisms of Ca²⁺ homeostasis in astrocytes is the store-operated Ca²⁺ entry (SOCE). This process is mediated by a combination of the Ca²⁺-store-depletion-sensor, Stim, and the store-operated Ca²⁺-channels, Orai and TrpC families. Despite the existence of all those families in astrocytes, previous studies have provided conflicting results on the molecular identification of astrocytic SOCE. Here, using the shRNA-based gene-silencing approach and Ca²⁺-imaging from cultured mouse astrocytes, we report that Stim1 in combination with Orai1 and Orai3 contribute to the major portion of astrocytic SOCE. Gene-silencing of Stim1 showed a 79.2% reduction of SOCE, indicating that Stim1 is the major Ca²⁺-store-depletion-sensor. Further gene-silencing showed that Orai1, Orai2, Orai3, and TrpC1 contribute to SOCE by 35.7%, 20.3%, 26.8% and 12.2%, respectively. Simultaneous gene-silencing of all three Orai subtypes exhibited a 67.6% reduction of SOCE. Based on the detailed population analysis, we predict that Orai1 and Orai3 are expressed in astrocytes with a large SOCE, whereas TrpC1 is exclusively expressed in astrocytes with a small SOCE. This analytical approach allows us to identify the store operated channel (SOC) subtype in each cell by the degree of SOCE. Our results propose that Stim1 in combination with Orai1 and Orai3 are the major molecular components of astrocytic SOCE under various physiological and pathological conditions.

Inhibition of Store-Operated Calcium Entry Protects Endothelial Progenitor Cells from H₂O₂-Induced Apoptosis

Store-operated calcium entry (SOCE), a major mode of extracellular calcium entry, plays roles in a variety of cell activities. Accumulating evidence indicates that the intracellular calcium ion concentration and calcium signaling are critical for the responses induced by oxidative stress. The present study was designed to investigate the potential effect of SOCE inhibition on H₂O₂-induced apoptosis in endothelial progenitor cells (EPCs), which are the predominant cells involved in endothelial repair. The results showed that H₂O₂-induced EPC apoptosis was reversed by SOCE inhibition induced either using the SOCE antagonist ML-9 or via silencing of stromal interaction molecule 1 (STIM1), a component of SOCE. Furthermore, SOCE inhibition repressed the increases in intracellular reactive oxygen species (ROS) levels and endoplasmic reticulum (ER) stress and ameliorated the mitochondrial dysfunction caused by H₂O₂. Our findings provide evidence that SOCE inhibition exerts a protective effect on EPCs in response to oxidative stress induced by H₂O₂ and may serve as a potential therapeutic strategy against vascular endothelial injury.

Calcium release-activated calcium channel modulator 1 promotes the migration and invasion of SW480 colon cancer cell line / 中国肿瘤临床

Objective:To explore the effect of calcium release-activated calcium channel modulator 1 (ORAI1) on the migration and invasion of colon cancer cell line SW480 and its mechanism. Methods:The SW480 cells were infected with ORAI interference lentivirus. The expression of ORAI1 mRNA and protein was confirmed by quantitative real-time polymerase chain reaction and Western blot. Transwell chamber, adhesion, angiogenesis, and vasculogenic mimicry experiments were conducted to detect the ability of cell invasion, migration, and angiogenesis and the intercellular adhesion of homogeneous and heterogeneous cells among each group. Confocal microscopy was employed to detect the difference of store-operated Ca2+entry (SOCE) in each group. Western blott was used to detect the expression of ERK1/2, p-ERK1/2, MMP-2, VEGF, and E-cadherin protein. Results:After the infection of SW480 with the ORAI1 interference lentivirus for 72 h, significant fluorescence expression was observed. Compared with the empty vector group and control group, the expression of ORAI1 was lower in the interference group (P<0.01). Invasion and migration ability decreased (P<0.01); the intercellular adhesion ability of homogeneous cells increased (P<0.05); the intercellular adhesion ability of heterogeneous cells decreased (P<0.05);the angiogenesi and vasculogenic mimicry were enhanced (P<0.01);the internal flow peak of SOCE was low (P<0.05); the expression of p-ERK1/2, MMP-2, and VEGF proteins decreased (P<0.01); and the expression of E-cadherin protein increased (P<0.01). Conclusion:ORAI1 may promote the migration and invasion of SW480. This mechanism may be associated with the increase of SOCE.

Methacholine and PDGF activate store-operated calcium entry in neuronal precursor cells via distinct calcium entry channels

Neurons are a diverse cell type exhibiting hugely different morphologies and neurotransmitter specifications. Their distinctive phenotypes are established during differentiation from pluripotent precursor cells. The signalling pathways that specify the lineage down which neuronal precursor cells differentiate remain to be fully elucidated. Among the many signáis that impinge on the differentiation of neuronal cells, cytosolic calcium (Ca2+) has an important role. However, little is known about the nature of the Ca2+ signáis involved in fate choice in neuronal precursor cells, or their sources. In this study, we show that activation of either muscarinic or platelet-derived growth factor (PDGF) receptors induces a biphasic increase in cytosolic Ca2+ that consists of reléase from intracellular stores followed by sustained entry across the plasma membrane. For both agonists, the prolonged Ca2+ entry occurred via a store-operated pathway that was pharmacologically indistinguishable from Ca2+ entry initiated by thapsigargin. However, muscarinic receptor-activated Ca2+ entry was inhibited by siRNA-mediated knockdown of TRPC6, whereas Ca2+ entry evoked by PDGF was not. These data provide evidence for agonist-specific activation of molecularly distinct store-operated Ca2+ entry pathways, and raise the possibility of privileged communication between these Ca2+ entry pathways and downstream processes.