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 signalingmi / R-146a empeora el deterioro cognitivo y la patología tipo Alzheimer al promover el estrés oxidativo a través de la vía de señalización MAPK

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 β (Aβ)1–42. Methods: To create a model of AD, SH-SY5Y cells were treated with Aβ1–42 and mice received intracerebroventricular injections of Aβ1–42. 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. Aβ and amyloid-beta precursor protein (APP)levels were measured by immunoblotting. Furthermore, Aβ expression was analyzed by immunofluorescence and histochemical examinations. Results: Aβ1–42-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 Aβ1–42, in which miR-146a upregulation increased the expression of Aβ, p-p38, and ROS, while the inhibition of miR-146a had the opposite effect. This suggests that miR-146a increases Aβ deposition and ROS accumulation via the p-p38 signaling pathway. Conclusions: Our research demonstrates that miR-146a-5pa increases Aβ deposition by triggering oxidative stress through activation of MAPK signaling.(AU)

Introducción: miR-146a-5p es un elemento regulador clave en la respuesta inmune. Sin embargo, estudios recientes sugieren que miR-146a-5p también está involucrado en el desarrollo de la enfermedad de Alzheimer (EA), aunque aún no se conoce con exactitud el mecanismo por el que esto sucede. Analizamos los efectos de miR-146a en un modelo animal y en células SH-SY5Y expuestas a β-amiloide (Aβ)1-42. Métodos: Tratamos células SH-SY5Y con Aβ1-42 e inyectamos Aβ1-42 en los ventrículos cerebrales de ratones para generar un modelo celular y otro animal de EA. Estimamos los niveles transcripcionales de miR-146a mediante PCR en tiempo real. Al mismo tiempo, transfectamos temporalmente las células y los ratones con imitador/inhibidor de miR-146a-5p para evaluar el papel de miR-146a. Estudiamos el papel de algunas vías de señalización, como la de p38, y los niveles de especies reactivas de oxígeno (ERO) con inhibidores específicos. Los niveles de Aβ y de proteína precursora amiloidea (APP) se determinaron con inmunoblot. También se analizó la expresión de Aβ mediante inmunofluorescencia y análisis histoquímico. Resultados: Las células SH-SY5Y expuestas a Aβ1-42 mostraron altos niveles transcripcionales de miR-146a y APP. La vía de señalización p-38 MAPK y la producción de EROs se activaron al utilizar un imitador de miR-146a-5p. Sin embargo, el bloqueo de miR-146a-5p con un inhibidor redujo los niveles de APP, EROs y p-p38 MAPK. Se observó un fenómeno similar en los ratones tratados con Aβ1-42: la sobrerregulación de miR-146a aumentó la expresión de Aβ, p-p38 y EROs, mientras que la inhibición de miR-146a tuvo el efecto contrario. Esto sugiere que miR-146a está involucrado en el aumento de acumulación de Aβ y de producción de EROs por medio de la vía de señalización p-p38. Conclusiones: Nuestro estudio muestra que miR146a-5p aumenta la acumulación de Aβ al promover el estrés oxidativo a través de la activación de la vía de señalización MAPK.(AU)

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.