RESUMO
Background: Neurotoxicity induced by the amyloid beta (Aß) peptide is one of the most important pathological mechanisms of Alzheimer's disease (AD). Activation of the adaptive IRE1α-XBP1 pathway contributes to the pathogenesis of AD, making it a potential target for AD therapeutics. However, the mechanism of IRE1α-XBP1 pathway involvement in AD is unclear. We, therefore, investigated the effect of the IRE1α-XBP1 axis in an in vitro AD model and explored its potential mechanism. Methods: The human neuroblastoma cell line, SH-SY5Y, was used. Cells were treated with Aß25-35, with or without 4µ8c, an inhibitor of IRE1α. Cells were collected and analyzed by Western blotting, quantitative real-time PCR, electron microscopy, fluorescence microscopy, calcium imaging, and other biochemical assays. Results: Aß-exposed SH-SY5Y cells showed an increased expression of XBP1s and p-IRE1α. 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and calcium imaging analysis showed that the IRE1α inhibitor, 4µ8c, reduced Aß-induced cytotoxicity. Increased levels of ATP, restoration of mitochondrial membrane potential, and decreased production of mitochondrial reactive oxygen species after Aß treatment in the presence of 4µ8c showed that inhibiting the IRE1α-XBP1 axis effectively mitigated Aß-induced mitochondrial dysfunction in SH-SY5Y cells. Furthermore, Aß treatment increased the expression and interaction of IP3R, Grp75, and vdac1 and led to an increased endoplasmic reticulum (ER)-mitochondria association, malfunction of mitochondria-associated ER-membranes (MAMs), and mitochondrial dysfunction. These deficits were rescued by inhibiting the IRE1α-XBP1 axis. Conclusion: These findings demonstrate that Aß peptide induces the activation of the IRE1α-XBP1 axis, which may aggravate cytotoxicity and mitochondrial impairment in SH-SY5Y cells by targeting MAMs. Inhibition of the IRE1α-XBP1 axis provides the protection against Aß-induced injury in SH-SY5Y cells and may, therefore, be a new treatment strategy.
RESUMO
The room-temperature ionic liquids (RTILs) have potential in realizing the ethylene (C(2)H(4)) and acetylene (C(2)H(2)) separation and avoiding solvent loss and environmental pollution compared with traditional solvents. The interaction mechanisms between gases and RTILs are important for the exploration of new RTILs for gas separation; thus, they were studied by quantum chemical calculation and molecular dynamics simulation in this work. The optimized geometries were obtained for the complexes of C(2)H(4)/C(2)H(2) with anions (Tf(2)N(-), BF(4)(-), and OAc(-)), cation (bmim(+)), and their ion pairs, and the analysis for geometry, interaction energy, natural bond orbital (NBO), and atoms in molecules (AIM) was performed. The quantum chemical calculation results show that the hydrogen-bonding interaction between the gas molecule and anion is the dominant factor in determining the solubility of C(2)H(2) in RTILs. However, the hydrogen-bonding interaction, the p-π interaction in C(2)H(4)-anion, and the π-π interaction in C(2)H(4)-cation are weak and comparable, which all affect the solubility of C(2)H(4) in RTILs with comparable contribution. The calculated results for the distance of H(gas)···X (X = O or F in anions), the BSSE-corrected interaction energy, the electron density of H(gas)···X at the bond critical point (ρ(BCP)), and the relative second-order perturbation stabilization energy (E(2)) are consistent with the experimental data that C(2)H(2) is more soluble than C(2)H(4) in the same RTILs and the solubility of C(2)H(4) in RTILs has the following order: [bmim][Tf(2)N] > [bmim][OAc] > [bmim][BF(4)]. The calculated results also agree with the order of C(2)H(2) solubility in different RTILs that [bmim][OAc] > [bmim][BF(4)] > [bmim][Tf(2)N]. Furthermore, the calculation results indicate that there is strong C(2)H(2)-RTIL interaction, which cannot be negligible compared to the RTIL-RTIL interaction; thus, the regular solution theory is probably not suitable to correlate C(2)H(2) solubility in RTILs. The molecular dynamics simulation results show that the hydrogen bond between the H in C2 of the imidazolium cation and the anion will weaken the hydrogen-bonding interaction of the gas molecule and anion in a realistic solution condition, especially in the C(2)H(4)-RTIL system.