Background Alzheimer`s disease (AD) is a progressive neurodegenerative disease worldwide. Accumulation of amyloid-β (Aβ), neurofibrillary tangles and neuroinflammation play the important neuro-pathology in patients with AD. miRNA is multifunctional and involved in physiological and pathological processes. Recently, microRNAs have been linked to neurodegenerative diseases. However, it is little known whether miRNA dysregulation contributes to AD pathology progression such as Aβ processing, phagocytosis and neuroinflammation. Here, we identify miR485-3p as a novel modulator of AD pathology in 5XFAD mice.
Methods To study the role of miR485-3p in AD, we used in control or miR485-3p antisense oligonucleotides (miR485-3p ASO) injected 5XFAD mouse model. Changes of Aβ processing and clearance and inflammation were analyzed by biochemical method in vitro and in vivo.
Result This study suggests that miR485-3p, a novel miRNA targeting SIRT1 may contribute to pathogenesis in an AD mouse. We found SIRT1 is significantly reduced in the precentral gyrus of Alzheimer patient`s and in 5XFAD mice. To determine whether the inhibition of miRNA 485-3p would affect AD pathology, we studied the effect of the antisense oligo in the brain of 5XFAD mice through direct intracerebral ventricular injection with miR485-3p ASO. We demonstrated that miR485-3p ASO significantly reduced Aβ plaque and amyloid biosynthetic enzyme. Importantly, the attenuation of Aβ plaques through miR485-3p ASO was mediated through Aβ phagocytic activity of glial cells, by which it can directly target CD36. MiR485-3p ASO also decreased inflammatory responses. Collectively, these responses inhibited neuronal loss caused by Aβ lead to improvements of cognitive impairment.
Conclusion Our data provide evidence for the molecular mechanisms which underlie the miR485-3p ASO responses in an AD mouse model. These results suggest that attenuating miRNA 485-3p levels might represent a novel therapeutic approach in AD.