ABSTRACT
MicroRNAs orchestrate brain functioning via interaction with microRNA recognition elements (MRE) on target transcripts. However, the global impact of potential competition on the microRNA pool between coding and non-coding brain transcripts that share MREs with them remains unexplored. Here we report that non-coding pseudogene transcripts carrying MREs (PSG+MRE) often show duplicated origin, evolutionary conservation and higher expression in human temporal lobe neurons than comparable duplicated MRE-deficient pseudogenes (PSG-MRE). PSG+MRE participate in neuronal RNA-induced silencing complexes (RISC), indicating functional involvement. Furthermore, downregulation cell culture experiments validated bidirectional co-regulation of PSG+MRE with MRE-sharing coding transcripts, frequently not their mother genes, and with targeted microRNAs; also, PSG+MRE single-nucleotide polymorphisms associated with schizophrenia, bipolar disorder and autism, suggesting interaction with mental diseases. Our findings indicate functional roles of duplicated PSG+MRE in brain development and cognition, supporting physiological impact of the reciprocal co-regulation of PSG+MRE with MRE-sharing coding transcripts in human brain neurons.
Subject(s)
Alzheimer Disease/metabolism , Brain/metabolism , Cognitive Dysfunction/metabolism , MicroRNAs/metabolism , Neurons/metabolism , Pseudogenes/genetics , Alzheimer Disease/genetics , Cognitive Dysfunction/genetics , Humans , MicroRNAs/genetics , RNA, Messenger/genetics , RNA, Messenger/metabolismABSTRACT
BACKGROUND: Most Alzheimer's disease (AD) cases arise sporadically and may involve innate immune activation of microglial expressed Toll-like receptors regulated through the myeloid differentiation protein 88 (MyD88) pathway. OBJECTIVE: It was the aim of this study to test the innate immune involvement in AD pathology. METHODS: We mated APPsw/PS1ΔE9 mice with MyD88-deficient mice. RESULTS: Progeny mice had similar levels of soluble amyloid-ß peptides, amyloid plaque density and neuroimmune staining patterns. However, double-transgenic mice did show a significantly reduced life expectancy. CONCLUSION: Our findings indicate that impaired innate immune responses may play a role in AD pathology.
Subject(s)
Alzheimer Disease/immunology , Alzheimer Disease/metabolism , Alzheimer Disease/pathology , Brain/pathology , Myeloid Differentiation Factor 88/deficiency , Amyloid beta-Peptides/metabolism , Animals , Brain/immunology , Brain/metabolism , Disease Models, Animal , Enzyme-Linked Immunosorbent Assay , Fluorescent Antibody Technique , Mice , Mice, Transgenic , Plaque, Amyloid/pathology , Reverse Transcriptase Polymerase Chain ReactionABSTRACT
Diverse stress stimuli induce long-lasting cognitive deficits, but the underlying molecular mechanisms are still incompletely understood. Here, we report three different stress models demonstrating that stress-inducible increases in microRNA-132 (miR-132) and consequent decreases in its acetylcholinesterase (AChE) target are causally involved. In a mild model of predator scent-induced anxiety, we demonstrate long-lasting hippocampal elevation of miR-132, accompanied by and associated with reduced AChE activity. Using lentiviral-mediated suppression of "synaptic" AChE-S mRNA, we quantified footshock stress-inducible changes in miR-132 and AChE and its corresponding cognitive damages. Stressed mice showed long-lasting impairments in the Morris water maze. In contrast, pre-stress injected AChE-suppressing lentivirus, but not a control virus, reduced hippocampal levels of both miR-132 and AChE and maintained similar cognitive performance to that of naïve, non-stressed mice. To dissociate between miR-132 and synaptic AChE-S as potential causes for stress-inducible cognitive deficits, we further used engineered TgR mice with enforced over-expression of the soluble "readthrough" AChE-R variant without the 3'-untranslated region binding site for miR-132. TgR mice displayed excess AChE-R in hippocampal neurons, enhanced c-fos labeling and correspondingly intensified reaction to the cholinergic agonist pilocarpine. They further showed excessive hippocampal expression of miR-132, accompanied by reduced host AChE-S mRNA and the GTPase activator p250GAP target of miR-132. At the behavioral level, TgR mice showed abnormal nocturnal locomotion patterns and serial maze mal-performance in spite of their reduced AChE-S levels. Our findings attribute stress-inducible cognitive impairments to cholinergic-mediated induction of miR-132 and consequently suppressed ACHE-S, opening venues for intercepting these miR-132-mediated damages.
Subject(s)
Acetylcholinesterase/metabolism , Cognition Disorders/etiology , Cognition , Hippocampus/enzymology , MicroRNAs/metabolism , Stress, Psychological/complications , 3' Untranslated Regions , Acetylcholinesterase/genetics , Animals , Binding Sites , Cells, Cultured , Cognition/drug effects , Cognition Disorders/enzymology , Cognition Disorders/genetics , Cognition Disorders/prevention & control , Cognition Disorders/psychology , Down-Regulation , Electroshock/psychology , Female , GPI-Linked Proteins/genetics , GPI-Linked Proteins/metabolism , GTPase-Activating Proteins/genetics , GTPase-Activating Proteins/metabolism , Gene Expression Regulation, Enzymologic , Hippocampus/drug effects , Male , Maze Learning , Mice , Mice, Inbred C57BL , Mice, Transgenic , Motor Activity , Muscarinic Agonists/pharmacology , Pilocarpine/pharmacology , Predatory Behavior , RNA Interference , RNA, Messenger/metabolism , Stress, Psychological/enzymology , Stress, Psychological/genetics , Stress, Psychological/psychology , Synapses/enzymology , Transfection , Up-RegulationABSTRACT
Post-traumatic anxiety notably involves inflammation, but its causes and functional significance are yet unclear. Here, we report that failure of the innate immune system Toll-like receptor 9 (TLR9) to limit inflammation is causally involved with anxiety-associated inflammation and that peripheral administration of specific oligonucleotide activators of TLR9 may prevent post-traumatic consequences in stressed mice. Suggesting involvement of NFκB-mediated enhancement of inflammatory reactions in the post-traumatic phenotype, we found association of serum interleukin-1ß increases with symptoms severity and volumetric brain changes in post-traumatic stress disorder patients. In predator scent-stressed mice, the moderate NFκB-activating oligonucleotides mEN101 and its human ortholog BL-7040, but not the canonic NFκB activator oligonucleotide ODN1826, induced anxiolytic effects. In stressed mice, peripherally administered mEN101 prevented delayed stress-inducible serum interleukin-1ß increases while limiting stress-characteristic hippocampal transcript modifications and the anxiety-induced EGR1-mediated neuronal activation. Attesting to the TLR9 specificity of this response, BL-7040 suppressed NFκB-mediated luciferase in transfected cells co-expressing TLR9, but not other TLRs. Furthermore, TLR9-/- mice were mEN101 and BL-7040 resistant and presented unprovoked anxiety-like behavior and anxiety-characteristic hippocampal transcripts. Our findings demonstrate functional relevance of TLR9 in protecting stressed mammals from overreacting to traumatic experiences and suggest using oligonucleotide-mediated peripheral TLR9 activation to potentiate the innate immune system and prevent post-traumatic inflammation and anxiety.