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Prostaglandin E2 (PGE2), one of the arachidonic acid metabolites synthetized from arachidonic acid through cyclooxygenase (COX) catalysis, demonstrates multiple physiological and pathological actions through different subtypes of EP receptors., Purpose: The present study was designed to explore the effects of PGE2 on cardiac fibrosis and the involved mechanism., Methods: We used western blot analysis, real-time quantitative PCR and immunostaining etc. to testify the mechanism., Results: Our data showed that in cultured adult rat cardiac fibroblasts (CFs), PGE2 effectively promoted the expression of α-smooth muscle actin (α-SMA), connective tissue growth factor (CTGF)，fibronectin (FN), Collagen I and induced [Ca2+]i increase. Besides, calcium increase evoked by PGE2 is mediated by virtue of EP1 activation. Instead of EP3 or EP4, inhibition of EP1 attenuated PGE2-stimulated upregulation of α-SMA，CTGF, FN, collagen I and [Ca2+]i, as well as the nuclear factor of activated T cell cytoplasmic 4 protein (NFATc4) translocation., Conclusions: PGE2 may promote cardiac fibrosis via EP1 receptor and calcium signal pathway.

Store-operated Ca 2+ entry (SOCE) is an important mechanism of extracellular Ca 2+ entry into cells. It has been proved that SOCE is involved in many pathologic and physiological processes. Two key participants of SOCE, stromal interaction molecule1 (STIM1) and Orai1, have been identified. But their function in cardiac fibroblasts remains elusive. In present study, our findings suggested the expression of STIM1 and Orai1 were increased followed by angiotensin II (Ang II) stimulation in vivo and in vitro. In cultured adult rat cardiac fibroblasts, Ang II led to STIM1 interact with Orai1 and Ca 2+ release from intracellular calcium store. In addition, the upregulation of fibronectin (FN), connective tissue growth factor (CTGF) and smooth muscle α-actin (α-SMA) induced by Ang II were attenuated by SOCE inhibitor SKF-96365, similar results were observed by knocking down STIM1 and Orai1. Furthermore, we found that silencing Orai1 by RNA interference also suppressed the translocation of Nuclear Factor of Activated T-cells (NFAT) Isoforms NFATc4 and decreased the phosphorylation of Smad2 and Smad3 induced by Ang II. These results unraveled a novel role of SOCE as a key modulator in the Ang II-induced cardiac fibrosis by mediating Ca 2+ influx., (Copyright © 2016 The Authors. Production and hosting by Elsevier B.V. All rights reserved.)

Na(+)/Mg(2+) exchanger plays an important role in cardiovascular system, but the molecular mechanisms still largely remain unknown. The Solute Carrier family 41A1 (SLC41A1), a novel Mg(2+) transporter, recently was found to function as Na(+)/Mg(2+) exchanger, which mainly regulates the intracellular Mg(2+) ([Mg(2+)]i) homeostasis. Our present studies were designed to investigate whether SLC41A1 impacts on the fibrogenesis of cardiac fibroblasts under Ang II stimulation. Our results showed that quinidine, a prototypical inhibitor of Na(+)/Mg(2+) exchanger, inhibited Ang II-induced cardiac fibrosis via attenuating the overexpression of vital biomarkers of fibrosis, including connective tissue growth factor (CTGF), fibronectin (FN) and α-smooth muscle actin (α-SMA). In addition, quinidine also decreased the Ang II-mediated elevation of concentration of intracellular Ca(2+) ([Ca(2+)]i) and extrusion of intracellular Mg(2+). Meanwhile, silencing SLC41A1 by RNA interference also impaired the elevation of [Ca(2+)]i, [Mg(2+)]i efflux and the upregulation of CTGF, FN and α-SMA provoked by Ang II. Furthermore, we found that Ang II-mediated activation of NFATc4 translocation decreased in SLC41A1-siRNA cells. These results support the notion that rapid extrusion of intracellular Mg(2+) is mediated by SLC41A1 and provide the evidence that the intracellular free Ca(2+) concentration is influenced by extrusion of intracellular Mg(2+) which facilitates fibrosis reaction in cardiac fibroblasts., (Copyright © 2014 Elsevier Inc. All rights reserved.)

Cardiac fibrosis is involved in a lot of cardiovascular pathological processes. Cardiac fibrosis can block conduction, cause hypoxia, strengthen myocardial stiffness, create electrical heterogeneity, and hamper systolic ejection, which is associated with the development of arrhythmia, heart failure and sudden cardiac death. Besides the initial stimulating factors, the cardiac fibroblasts (CFs) are the principal responsible cells in the fibrogenesis cascade of events. TRPM7, a member of the TRPM (Melastatin) subfamily, is a non-selective cation channel, which permeates both Ca(2+) and Mg(2+). Here we demonstrated TRPM7 expression in CFs, and 2-APB (TRPM7 inhibitor), inhibited Ang II-induced CTGF, α-SMA expression and CFs proliferation. Besides, knocking down TRPM7 by shRNA, we proved that TRPM7 mediated both calcium and magnesium changes in cardiac fibroblasts which contribute to fibrosis progress. This study suggested that TRPM7 should play a pivotal role in cardiac fibroblast functions associated to cardiac fibrosis development., (Crown Copyright © 2014. Published by Elsevier Ltd. All rights reserved.)

Abstract: Aim: We have previously proved that oxidized low-density lipoprotein (oxLDL), a proatherogenic lipoprotein, plays a pivotal role in the development of atherosclerotic calcification (AC). The present study was performed to investigate whether tanshinone II A (TS II A), an anti-oxidant which has been shown to inhibit in vitro oxidation of LDL, has the effects to inhibit AC in rat model and by which, if any, mechanisms. Methods: Rat AC model was induced by excessive vitamin D2 (VD) and high cholesterol diet (HCD), which was proven to be successful histopathologically and biochemically. Results: Administration of AC rats with TS II A (35, 70 mg/kg) dose-dependently attenuated the AC pathological changes, meanwhile reduced the vessel contents of lipid and calcium. However, TS II A had no effects on serum levels of lipids, calcium and 25-OH VD. Further studies revealed that TS II A decreased serum concentration of oxLDL, reduced the superoxide anion production and malondialdehyde (MDA) in vessel. In addition, TS II A increased vessel Cu/Zn SOD activity, upregulated vessel mRNA and protein expression of Cu/Zn SOD. Conclusion: The results suggested that TS II A significantly attenuated the AC in rat model, which might be attributed to its inhibition of oxLDL production independent of the serum levels of lipids, calcium and 25-OH VD, and that increasing of Cu/Zn SOD activity as well as mRNA and protein expression by TS II A might protect LDL against oxidation induced by superoxide anion in vessel. [Copyright &y& Elsevier]