APP and Alzheimer disease: Successive work reported that the significantly decreased level of miR-124, a representative member of miRNA family, in the brain of AD patients, greatly improved the expression of its corresponding target molecule polypyrimidine tract-binding protein1 (PTBP1), which was critical splicing factor to interrupt the splicing process of APP exons 7 and 8 and subsequently accelerate Aβ generation and AD progression (17).