GSE163391
The ZSWIM8 ubiquitin ligase mediates target-directed microRNA degradation [dataset 6]
MicroRNAs (miRNAs) associate with Argonaute (AGO) proteins to direct widespread post-transcriptional gene repression.  Although association with AGO typically protects miRNAs from nucleases, extensive pairing to some unusual target RNAs can trigger miRNA degradation.  Here we found that this target-directed miRNA degradation (TDMD) required the ZSWIM8 Cullin-RING E3 ubiquitin ligase.  This and other findings suggested and supported a mechanistic model of TDMD in which target-directed proteolysis of AGO by the ubiquitin–proteasome pathway exposes the miRNA for degradation.  Moreover, loss-of-function studies indicated that the ZSWIM8 Cullin-RING ligase accelerates degradation of numerous miRNAs in cells of mammals, flies, and nematodes, thereby specifying the half-lives of most short-lived miRNAs.  These results elucidate the mechanism of TDMD and expand the inferred role of TDMD in shaping miRNA levels in bilaterian animals. Overall design: Profiling of gRNA cassettes from K562 cells expressing a miR-7 fluorescent reporter and the human CRISPRi v2 library.  Cells were sorted by mCherry:GFP ratio, and those in the top 5% and bottom 5% of this metric were collected. This study consists of libraries generated from these populations.