MicroRNA-193b is a regulator of amyloid precursor protein in the blood and cerebrospinal fluid derived exosomal microRNA-193b is a biomarker of Alzheimer's disease.

ABSTRACT

Amyloid precursor protein (APP) has an important function in the generation of Alzheimer's disease (AD). In our previous study, miR­193b was found to be downregulated in the hippocampi of 9­month­old APP/PS1 double­transgenic mice using microRNA (miR) array. In the present study, bioinformatic analyses showed that miR­193b was a miR that was predicted to potentially target the 3'­untranslated region (UTR) of APP. Subsequently, the function of miR­193b on APP was studied. The levels of miR­193b, exosomal miR­193b, Aß, tau, p­tau, HCY and APOE in samples from APP/PS1 double­transgenic mice, mild cognitive impairment (MCI) and dementia of Alzheimer­type (DAT) patients, were measured. The results indicated that overexpression of miR­193b could repress the mRNA and protein expression of APP. The miR­193b inhibitor oligonucleotide induced upregulation of APP. Binding sites of miR­193b in the 3'­UTR of APP were identified by luciferase assay. MCI and DAT patients had lower exosomal miR­193b, but not total miR­193b, in the blood as compared with the controls. DAT patients had lower exosomal miR­193b levels in blood as compared with the MCI group. A decreased exosomal miR­193b expression level was additionally observed in the cerebral spinal fluid (CSF) of DAT patients. Negative correlations were found between exosomal miR­193b and Aß42 in the CSF of DAT patients. In conclusion, these findings showed that miR­193b may function in the development of AD and exosomal miR­193b has potential as a novel, non-invasive, blood­based biomarker of MCI and DAT patients.