miR-146a aggravates cognitive impairment and Alzheimer disease-like pathology by triggering oxidative stress through MAPK signaling.

INTRODUCTION: Mir-146a-5p has been widely recognized as a critical regulatory element in the immune response. However, recent studies have shown that miR-146a-5p may also be involved in the development of Alzheimer disease (AD). Regrettably, the related mechanisms are poorly understood. Here, we investigated the effects of miR-146a in mice models and SH-SY5Y cells treated with amyloid ß (Aß)1-42. METHODS: To create a model of AD, SH-SY5Y cells were treated with Aß1-42 and mice received intracerebroventricular injections of Aß1-42. Then, the transcriptional levels of miR-146a were estimated by real-time PCR. We transiently transfected the miR-146a-5p mimic/inhibitor into cells and mice to study the role of miR-146a. The role of signaling pathways including p38 and reactive oxygen species (ROS) was studied by using specific inhibitors. Aß and amyloid-beta precursor protein (APP)levels were measured by immunoblotting. Furthermore, Aß expression was analyzed by immunofluorescence and histochemical examinations. RESULTS: Aß1-42-stimulated SH-SY5Y cells displayed increased transcriptional levels of miR-146a and APP. Moreover, the p38 MAPK signaling pathway and ROS production were activated upon stimulation with a miR-146a-5p mimic. However, treatment with a miR-146a-5p inhibitor decreased the levels of APP, ROS, and p-p38 MAPK. A similar phenomenon was also observed in the animals treated with Aß1-42, in which miR-146a upregulation increased the expression of Aß, p-p38, and ROS, while the inhibition of miR-146a had the opposite effect. This suggests that miR-146a increases Aß deposition and ROS accumulation via the p-p38 signaling pathway. CONCLUSIONS: Our research demonstrates that miR-146a-5pa increases Aß deposition by triggering oxidative stress through activation of MAPK signaling.

miR-146a aggravates cognitive impairment and Alzheimer disease-like pathology by triggering oxidative stress through MAPK signaling.

INTRODUCTION: Mir-146a-5p has been widely recognized as a critical regulatory element in the immune response. However, recent studies have shown that miR-146a-5p may also be involved in the development of Alzheimer disease (AD). Regrettably, the related mechanisms are poorly understood. Here, we investigated the effects of miR-146a in mice models and SH-SY5Y cells treated with amyloid ß (Aß)1-42. METHODS: To create a model of AD, SH-SY5Y cells were treated with Aß1-42 and mice received intracerebroventricular injections of Aß1-42. Then, the transcriptional levels of miR-146a were estimated by real-time PCR. We transiently transfected the miR-146a-5p mimic/inhibitor into cells and mice to study the role of miR-146a. The role of signaling pathways including p38 and reactive oxygen species (ROS) was studied by using specific inhibitors. Aß and amyloid-beta precursor protein (APP)levels were measured by immunoblotting. Furthermore, Aß expression was analyzed by immunofluorescence and histochemical examinations. RESULTS: Aß1-42-stimulated SH-SY5Y cells displayed increased transcriptional levels of miR-146a and APP. Moreover, the p38 MAPK signaling pathway and ROS production were activated upon stimulation with a miR-146a-5p mimic. However, treatment with a miR-146a-5p inhibitor decreased the levels of APP, ROS, and p-p38 MAPK. A similar phenomenon was also observed in the animals treated with Aß1-42, in which miR-146a upregulation increased the expression of Aß, p-p38, and ROS, while the inhibition of miR-146a had the opposite effect. This suggests that miR-146a increases Aß deposition and ROS accumulation via the p-p38 signaling pathway. CONCLUSIONS: Our research demonstrates that miR-146a-5pa increases Aß deposition by triggering oxidative stress through activation of MAPK signaling.