Down-regulation of Homer1 attenuates t-BHP-induced oxidative stress through regulating calcium homeostasis and ER stress in brain endothelial cells

• Published in: Biochemical and biophysical research communications Vol. 477; no. 4; pp. 970 - 976
• Main Authors: Guo, Zhen-Yu, Zhang, Ya-Hong, Xie, Guo-Qiang, Liu, Chong-Xiao, Zhou, Ren, Shi, Wei
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 02.09.2016
• Subjects: adenosine triphosphate; animal models; Animals; apoptosis; brain; Brain - cytology; Brain - drug effects; Brain - physiology; calcium; Calcium - physiology; Calcium homeostasis; Calcium Signaling - drug effects; Calcium Signaling - physiology; cell viability; Cells, Cultured; dose response; Down-Regulation - drug effects; Down-Regulation - physiology; edema; endoplasmic reticulum; Endoplasmic Reticulum Stress - drug effects; Endoplasmic Reticulum Stress - physiology; endothelial cells; ER stress; Gene Expression Regulation - drug effects; Gene Expression Regulation - physiology; genes; homeostasis; Homeostasis - drug effects; Homeostasis - physiology; Homer Scaffolding Proteins - metabolism; Homer1; image analysis; inositols; lactate dehydrogenase; lipid peroxidation; membrane potential; Mice; Mice, Inbred C57BL; mitochondrial membrane; mortality; nervous system diseases; Oxidative stress; Oxidative Stress - drug effects; Oxidative Stress - physiology; receptors; small interfering RNA; tert-Butylhydroperoxide - pharmacokinetics; tert-Butylhydroperoxide - pharmacology; toxicity; ER stress; Oxidative stress; Homer1; Calcium homeostasis
• ISSN: 0006-291X; 1090-2104
• DOI: 10.1016/j.bbrc.2016.07.012

Endothelial dysfunction in brain endothelial cells contributes to vasogenic cerebral edema and increased mortality after various neurological diseases. The postsynaptic density protein Homer1 plays an important role in neuronal synaptic activity and is extensively involved in neurological disorders. The present study investigated the role of Homer1 in modulating cell survival using an in vitro endothelial dysfunction model in murine brain endothelial cells (mBECs). Treatment with tert-butyl hydroperoxide (t-BHP) induced a dose-dependent toxicity in mBECs, with no effects on Homer1 expression and distribution. Knockdown of Homer1 using specific siRNA significantly alleviated lactate dehydrogenase (LDH) release, increased cell viability, and ultimately decreased apoptosis after t-BHP treatment. Moreover, Homer1 knockdown attenuated t-BHP-induced ROS generation, lipid peroxidation and mitochondrial dysfunction, as evidenced by loss of mitochondrial membrane potential (MMP), ATP synthesis collapse and mitochondrial swelling. The results of Ca2+ imaging showed that Homer1 was involved in inositol trisphosphate receptors (IP3R)- and ryanodine receptor (RyR)-mediated intracellular Ca2+ release, and also mediated t-BHP-induced Ca2+ release from the endoplasmic reticulum (ER). In addition, knockdown of Homer1 significantly prevented activation of ER stress markers induced by t-BHP exposure. All these results showed that Homer1 is involved in t-BHP-induced endothelial dysfunction in mBECs, and may be an ideal candidate for searching gene intervention strategy for preventing endothelial oxidative stress in vitro. •Down-regulation of Homer1 protects against t-BHP-induced endothelial injury.•Down-regulation of Homer1 reduces t-BHP-induced oxidative stress.•Down-regulation of Homer1 preserves Ca2+ homeostasis in mBECs.•Down-regulation of Homer1 attenuates t-BHP-induced ER stress.