Abstract

© 2015 Elsevier Ltd All rights reserved.Summary Processing of microRNA primary transcripts is highly regulated and defects in the processing machinery play a key role in many human diseases. In 22q11.2 deletion syndrome, heterozygous deletion of DiGeorge critical region gene 8 causes a processing deficiency, which contributes to abnormal brain development. The DGCR8 protein is the RNA-binding partner of Drosha RNase, both essential for processing canonical pri-miRNAs. To identify an agent that can compensate reduced DGCR8 expression, we screened for metalloporphyrins that can mimic the natural DGCR8 heme cofactor. We found that Co protoporphyrin IX stably binds DGCR8 and activates it for pri-miRNA processing in vitro and in HeLa cells. Importantly, treating cultured Dgcr8+/- mouse neurons with CoPPIX can compensate the pri-miRNA processing defects. CoPPIX is effective at concentrations as low as 0.2 μM and is not degraded by heme degradation enzymes, making it useful as a research tool and a potential therapeutic.