Human SIDT1 mediates dsRNA uptake via its phospholipase activity

Dear Editor, Systemic RNA interference(RNAi)refers to post-transcriptional gene silencing that spreads throughout the organism and its progeny,which could be triggered by double-stranded(ds)RNA.1,2 Hunter and colleagues identified that a ubiquitously expressed putative transmembrane protein SID-1(systemic RNAi defective-1)in Caenorhabditis elegans is required for systemic RNAi,3 via acting as a channel to passively transport extracellular dsRNA into cells.4,5 SIDT1(SID-1 transmembrane family member 1)is a SID-1 homolog in humans.Previous reports showed that it could facilitate the cellular uptake of both short interfering RNAs and microRNAs(miRNA).6-8 Given a sequence identity of～24％,SIDT1 might function in a way similar to nematode SID-1.