title: Stimulation of insulin signaling and inhibition of JNK-AP1 activation protect cells from amyloid-β-induced signaling dysregulation and inflammatory response.
abstract: One of the hallmarks of Alzheimer's disease (AD) is the accumulation and deposition of amyloid-β (Aβ) peptides in the brain and cerebral vasculature. Aβ evokes neuroinflammation and has been implicated in insulin signaling disruption and JNK-AP1 activation, contributing to AD neuropathologies including oxidative injury and vascular insufficiencies. In this study we aim to better understand the protective mechanisms of insulin signaling and JNK-AP1 inhibition on the adverse effects of Aβ. Four-hour treatment of hCMEC/D3, the immortalized human brain endothelial cells (iHBEC), with Aβ1-42 resulted in significant c-Jun phosphorylation, oxidative stress, and cell toxicity. Concurrent treatment with Aβ1-42 and insulin or Aβ1-42 and JNK inhibitor SP600125 significantly improved cell viability. Cytokine array on conditioned media showed that insulin and SP600125 strongly reduced all Aβ1-42-induced cytokines. ELISA confirmed the protective effect of insulin and SP600125 on Aβ-induced expression of interleukin (IL)-8 and Growth related oncogene-α (Gro-α). qRT-PCR revealed that insulin and SP600125 protected iHBEC from Aβ1-42-induced inflammatory gene expression. Transcription factor profiling showed that treatment of iHBEC with Aβ1-42, insulin, or SP600125 alone or in combination resulted in profound changes in modulating the activities of multiple transcription factors and relevant pathways, some of which were validated by western blot. Insulin treatment and JNK inhibition in vitro synergistically reduced c-Jun phosphorylation and thus JNK-AP1 signaling activation. The study suggests that activation of insulin and blocking of JNK-AP1 signaling inhibits Aβ-induced dysregulation of insulin signaling and inflammatory response.
authors.affiliation: Human Health Therapeutics Portfolio, National Research Council Canada, Ottawa, ON, Canada Faculty of Medicine, University of Ottawa, Ottawa, ON, Canada.
authors.forename: Michelle
authors.initials: M
authors.lastname: Bamji-Mirza
authors.affiliation: Human Health Therapeutics Portfolio, National Research Council Canada, Ottawa, ON, Canada.
authors.forename: Debbie
authors.initials: D
authors.lastname: Callaghan
authors.affiliation: Human Health Therapeutics Portfolio, National Research Council Canada, Ottawa, ON, Canada Faculty of Medicine, University of Ottawa, Ottawa, ON, Canada.
authors.forename: Dema
authors.initials: D
authors.lastname: Najem
authors.affiliation: Human Health Therapeutics Portfolio, National Research Council Canada, Ottawa, ON, Canada Southeast University, Nanjing, China.
authors.forename: Shanshan
authors.initials: S
authors.lastname: Shen
authors.affiliation: Human Health Therapeutics Portfolio, National Research Council Canada, Ottawa, ON, Canada Faculty of Medicine, University of Ottawa, Ottawa, ON, Canada.
authors.forename: Mohamed Shaad
authors.initials: MS
authors.lastname: Hasim
authors.affiliation: Beijing Hospital & Beijing Institute of Geriatrics, Chinese Ministry of Health, Beijing, China.
authors.forename: Ze
authors.initials: Z
authors.lastname: Yang
authors.affiliation: Human Health Therapeutics Portfolio, National Research Council Canada, Ottawa, ON, Canada Faculty of Medicine, University of Ottawa, Ottawa, ON, Canada Southeast University, Nanjing, China.
authors.forename: Wandong
authors.initials: W
authors.lastname: Zhang
mesh_terms: D016229:Amyloid beta-Peptides / Q000633:toxicity*; D000704:Analysis of Variance; D000873:Anthracenes / Q000494:pharmacology; D001921:Brain / Q000166:cytology; D002461:Cell Line, Transformed; D054426:Chemokine CXCL2 / Q000235:genetics / Q000378:metabolism; D016207:Cytokines / Q000235:genetics / Q000378:metabolism; D042783:Endothelial Cells / Q000187:drug effects / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D007328:Insulin / Q000378:metabolism*; D048670:MAP Kinase Kinase 4 / Q000378:metabolism*; D018384:Oxidative Stress / Q000187:drug effects; D010446:Peptide Fragments / Q000633:toxicity*; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
chemical_list: D016229:Amyloid beta-Peptides; D000873:Anthracenes; C499706:CXCL2 protein, human; D054426:Chemokine CXCL2; D016207:Cytokines; D004791:Enzyme Inhibitors; D007328:Insulin; D010446:Peptide Fragments; D014157:Transcription Factors; C075222:amyloid beta-protein (1-42); C432165:pyrazolanthrone; D048670:MAP Kinase Kinase 4
keywords: Alzheimer's disease; JNK-AP1 signaling; amyloid-β peptides; inflammatory response insulin signaling