Effects of subchronic fluoride exposure through drinking water on renal toxicity and the expressions of STIM1 and ORAI1 in renal tissues in mice / 环境与职业医学

Background It has been found that fluoride may cause cell damage by inducing intracellular calcium overload. Store-operated calcium entry (SOCE) plays an important role in maintaining intracellular calcium homeostasis, but the effect of fluoride on renal SOCE is unknown. Objective To explore the renal toxicity and the expression levels of the key proteins of SOCE, stromal interaction molecule 1 (STIM1) and calcium release-activated calcium modulator 1 (ORAI1) in the kidney tissues of mice exposed to fluoride subchronically. Methods Twenty male ICR mice were randomly divided into four groups with five mice in each group, including 0 (control group), 0.3, 3, and 30 mg·L−1 fluoride groups. The mice were given drinking water containing designed fluoride for 12 weeks. Body weight and liver and kidney organ coefficients of the mice were measured after the exposure; histopathological changes of the mouse kidney were observed; 24 h urine was collected at the end of 12 weeks of exposure to determine the levels of urine creatinine (UCr), urine calcium (UCa), albumin (ALB), and β2-microglobulin (β2-MG); the protein expression levels of STIM1 and ORAI1 in the kidney were detected by Western blotting; the fluorescence co-localization of STIM1 and ORAI1 was used to further verify the expression levels of STIM1 and ORAI1. Results After the exposure, there were no differences in body weight as well as liver and kidney organ coefficients among the groups (P > 0.05). Under optical microscope, the renal tubular cell showed degeneration, apical protrusion, shedding, and dilation in the 3 and 30 mg·L−1 fluoride groups. There was no statistical difference in UCr among the mice in each group (P > 0.05). Compared with the control group, the levels of UCa adjusted by UCr in the 3 and 30 mg·L−1 fluoride groups were (0.075±0.014) and (0.081±0.012) mol·mol−1 (represent by UCr per mol), which had a rising trend but showed no statistical difference. No difference was identified in the level of ALB among the groups (P > 0.05). The levels of β2-MG showed difference in different exposure groups, and the level of urine β2-MG in the 30 mg·L−1 fluoride group was (0.077±0.014) g·mol−1, higher than that in the control group (P<0.05). Based on the results of Western blotting, the protein expression levels of STIM1 and ORAI1 showed significant differences among the groups (F=18.411, 6.853; P=0.001, 0.013); compared with the control group, the expression levels of STIM1 protein increased in the 3 and 30 mg·L−1 fluoride groups (P < 0.05), and the protein expression level of ORAI1 in the 30 mg·L−1 fluoride group was increased (P < 0.05). The fluorescence co-localization results of STIM1 and ORAI1 showed that the expressions of STIM1 and ORAI1 were up-regulated in the 3 and 30 mg·L−1 fluoride groups. Conclusion Subchronic exposure to fluoride through drinking water can up-regulate the expression levels of STIM1 and ORAI1 in renal tissues and induce renal injury.

The effect of store-operated calcium entry inhibitor on liver and kidney injury induced by paraquat / 中华急诊医学杂志

Objective:To investigate the effect of SKF96365, store-operated calcium entry (SOCE) inhibitor, on liver and kidney injury induced by paraquat (PQ).Methods:A549 cells were cultured in vitro and divided into the control group (DMSO group, SKF 2 μmol/L group, and SKF 10 μmol/L group) and PQ group (PQ+DMSO group, PQ+SKF 2 μmol/L group, and PQ+SKF 10 μmol/L group). The nuclear factor of activated T cells (NFAT) in A549 cells was detected by luciferase reporter gene technique. The mouse model of PQ poisoning was constructed and divided into the control group, SKF group, PQ group and PQ+SKF group. In the PQ group, mice were injected with 50 mg/kg PQ intraperitoneally; in the SKF group, mice were injected intraperitoneally with 10 mg/kg SKF96365 for 3 days. Mice in the PQ+SKF group received 50 mg/kg intraperitoneal injection of PQ once and 10 mg/kg intraperitoneal injection of SKF96365 daily for 3 days. On the fourth day, the mice were sacrificed, and the liver and kidney tissues were taken. The histopathological changes of liver and kidney tissues were observed by hematoxylin-eosin (H&E) staining, and the apoptosis of liver and kidney tissues was observed by TUNEL staining. One-way analysis of variance was used to compare the mean values of normally distributed measurement data between groups. Comparisons between groups were performed using the least significant difference t-test. Results:The luciferase reporter gene technology showed that NFAT was significantly activated in the PQ group. After pretreatment with SKF96365, NFAT activation decreased sharply in a dose-dependent manner. HE staining showed that the outline structure of liver and kidney tissues in the PQ groups were unclear, cells swelled and a large number of inflammatory cells infiltrated; in the PQ+SKF group, liver cell swelling and inflammatory cell infiltration decreased significantly. TUNEL staining showed that the apoptotic cells in liver and kidney tissues increased in the PQ groups, and the apoptosis decreased remarkably in the PQ+SKF group.Conclusions:SOCE inhibitor SKF96365 can significantly reduce the liver and kidney injury caused by PQ.

Effects of total flavonoids of Rhododendra simsii on ameliorating brain injury via G protein-coupled SOCE pathway mediated by STIM and Orai in subacute phase of ischemia/reperfusion / 中国药理学与毒理学杂志

OBJECTIVE To explore the effect of total flavonoids of Rhododendra simsii (TFR) on improving cerebral ischemia/reperfusion injury (CIRI) and its relationship with STIM/Orai-regulated operational Ca2+influx (SOCE) pathway. METHODS Oxygen-glucose deprivation/reoxygenation (OGD/R) PC12 cells were used to simulate CIRI in vitro, and the intracellular Ca2+ concentration and apoptosis rate of PC12 cells were detected by laser confocal microscope and flow cytometry, respectively. The regulation of STIM/Orai on SOCE was analyzed by STIM/Orai gene silencing and STIM/Orai gene overexpression. The CIRI model was established by MCAO in SD rats. The activities of inflammatory cyto?kines IL-1, IL-6 and TNF-αin serum were detected by ELISA. The pathological changes of ischemic brain tissue and the infarction of rat brain tissue were detected by HE staining and TTC staining. The protein and mRNA expression levels of STIM1, STIM2, Orai1, caspase-3 and PKB in brain tissue were detected by Western blotting and RT-qPCR, respectively. RESULTS The results of in vitro experiment showed that the fluorescence intensity of Ca2+ and apoptosis rate in PC12 cells treated with TFR were significantly lower than those in OGD/R group, and this trend was enhanced by SOCE antagonist 2-APB. STIM1/STIM2/Orai1 gene silencing significantly reduced apoptosis and Ca2+overload in OGD/R model, while TFR combined with overexpression of STIM1/STIM2/Orai1 aggravated apoptosis and Ca2+overload. In the in vivo experiment, TFR significantly reduced the brain histopathological damage, infarction of brain tissue, the contents of IL-1, IL-6 and TNF-α in the serum in MCAO rats and down-regulated the expression of STIM1, STIM2, Orai1 and caspase-3 protein and mRNA in the brain tissue, and up-regulated the expression of PKB. The above effects were enhanced by the addition of 2-APB. CONCLUSION The above results indicate that TFR may reduce the contents of inflammatory factors and apoptosis, decrease Ca2+ overload and ameliorate brain injury by inhibiting SOCE pathway mediated by STIM and Orai, suggesting that it has a protective effect against subacute CIRI.

Resveratrol reduces store-operated Ca2+ entry and enhances the apoptosis of fibroblast-like synoviocytes in adjuvant arthritis rats model via targeting ORAI1-STIM1 complex

BACKGROUND: Resveratrol was reported to trigger the apoptosis of fibroblast-like synoviocytes In adjuvant arthritis rats but the subcellular mechanism remains unclear. Since ER stress, mitochondrial dysfunction and oxidative stress were involved in the effects of resveratrol with imbalance of calcium bio-transmission, store operated calcium entry (SOCE), a novel intracellular calcium regulatory pathway, may also participate in this process. RESULTS: In the present study, Resveratrol was found to suppress ORAI1 expression of a dose dependent manner while have no evident effects on STIM1 expressive level. Besides, resveratrol had no effects on ATP or TG induced calcium depletion but present partly dose-dependent suppression of SOCE. On the one hand, microinjection of ORAI1 overexpressed vector in sick toe partly counteracted the therapeutic effects of resveratrol on adjuvant arthritis and serum inflammatory cytokine including IL-1, IL-6, IL-8, IL-10 and TNF-α. On the other hand, ORAI1 SiRNA injection provided slight relief to adjuvant arthritis in rats. In addition, ORAI1 overexpression partly diminished the alleviation of hemogram abnormality induced by adjuvant arthritis after resveratrol treatment while ORAI1 knockdown presented mild resveratrol-like effect on hemogram in rats model. CONCLUSION: These results indicated that resveratrol reduced store-operated Ca2+ entry and enhanced the apoptosis of fibroblast-like synoviocytes in adjuvant arthritis rats model via targeting ORAI1-STIM1 complex, providing a theoretical basis for ORAI1 targeted therapy in future treatment with resveratrol on rheumatoid arthritis.

Regulation of Intracellular Calcium by Endoplasmic Reticulum Proteins in Small Intestinal Interstitial Cells of Cajal

BACKGROUND/AIMS: We investigated the role of representative endoplasmic reticulum proteins, stromal interaction molecule 1 (STIM1), and store-operated calcium entry-associated regulatory factor (SARAF) in pacemaker activity in cultured interstitial cells of Cajal (ICCs) isolated from mouse small intestine. METHODS: The whole-cell patch clamp technique applied for intracellular calcium ions ([Ca²+]i) analysis with STIM1 or SARAF overexpressed cultured ICCs from mouse small intestine. RESULTS: In the current-clamping mode, cultured ICCs displayed spontaneous pacemaker potentials. External carbachol exposure produced tonic membrane depolarization in the current-clamp mode, which recovered within a few seconds into normal pacemaker potentials. In STIM1-overexpressing cultured ICCs pacemaker potential frequency was increased, and in SARAF-overexpressing ICCs pacemaker potential frequency was strongly inhibited. The application of gadolinium (a non-selective cation channel inhibitor) or a Ca2+-free solution to understand Orai channel involvement abolished the generation of pacemaker potentials. When recording intracellular Ca²+ concentration with Fluo 3-AM, STIM1-overexpressing ICCs showed an increased number of spontaneous intracellular Ca²+ oscillations. However, SARAF-overexpressing ICCs showed fewer spontaneous intracellular Ca2+ oscillations. CONCLUSION: Endoplasmic reticulum proteins modulated the frequency of pacemaker activity in ICCs, and levels of STIM1 and SARAF may determine slow wave patterns in the gastrointestinal tract.

Research progress of STIM1 in tumor development and clinical application / 天津医药

Studies have shown that stromal interaction molecule 1(STIM1) is closely related to the development of tumors, and which is involved in the regulation of apoptosis, proliferation, migration and invasion in many human cancers. Blocking or knockdown of STIM1 can significantly inhibit the proliferation and migration of cancer cells. Elucidation of the regulatory mechanism of STIM1 in cancer cells will be helpful for the identification of new therapeutic targets. This paper reviews the mechanism of STIM1 molecule in different tumors and its clinical application.

Relationship of time-course curve between the expression of TRPC1 and vascular tone of pulmonary arteries in chronic hypoxia pulmonary hypertension rats / 中国药理学通报

Aim To evaluate the time-course curve of expression of TRPC1 and vascular tone of pulmonary arteries(PAs)mediated by SOCE in chronic hypoxia pulmonary hyperte-nsion rats.Methods Both tension of PA rings and expression of TRPC1 were tested in CH exposure (1 0.0 % ±0.5 %partialpressure ofoxygen ) induced pulmonary hypertensive (PH)rats,and the time-course curve(detected respectively in CH 1 ,3,5, 7,1 4,21 d)was traced.Results ①CH could up-regulate the mean right ventricular pressure(mRVSP) ,which was increased significantly on 1 d,and reached the maximum on 7d;right ventricular weight index (RV-MI)began increase on 3d,and kept rising;②semi-quantitative reverse transcription polyme-rase chain reaction (RT-PCR)was performed to detect the expression of TRPC1 in PAs.The expression of TRPC1 increased significantly on 1 d,and reached the maxi-mum on 3d;③CH could up-regulate the vascular tone of PAs mediated by SOCE,which was increased signif-icantly on 3d,and reached the maximum on 7d.Con-clusions TRPC1 /SOCE increases significantly in the early days of CH,and the time-course curve of the two has correlation,which reflects the important role of the upregulation of TRPC1 /SOCE in the process of chronic hypoxia pulmonary hypertension.