library_construction_protocol: N2A cells were transfected with either APP overexpression plasmid or empty vector for 2 days. RNAs were isolated from cells using Qiagen RNeasy mini kit according to the manufacturers instructions.  Sequencing libraries were generated using NEBNext Multiplex Small RNA Library Prep Set for Illumina (NEB). The clustering of the index-coded samples was performed on a cBot Cluster Generation System using TruSeq SR Cluster Kit v3-cBot-HS (Illumia).