MKRN2 physically interacts with GLE1 to regulate mRNA export and zebrafish retinal development (RNA-Seq)

The canonical mammalian mRNA export process is thought to terminate at the cytoplasmic face of the nuclear pore complex through mRNP remodeling. We conducted a stringent affinity-purification mass-spectrometry-based screen of the physical interactions of human RNA-binding E3 ubiquitin ligases. The resulting protein-interaction network revealed unexpected interactions between the RNA-binding E3 ubiquitin ligase MKRN2 and GLE1, a DEAD-box helicase activator implicated in mRNA export termination. We assessed MKRN2 epistasis with GLE1 in a genetically tractable zebrafish model. Strikingly, morpholino-mediated knockdown or CRISPR/Cas9-based knockout of MKRN2 partially rescued retinal developmental defects seen upon GLE1 depletion. Next, using iCLIP, we showed that MKRN2 binds preferentially to the 3'UTR of a diverse subset of mRNAs. Next-generation sequencing of fractionated cell extracts revealed that nuclear export of MKRN2-associated mRNAs is enhanced upon knockdown of MKRN2. Taken together, these results indicate that MKRN2 selectively interacts with GLE1 to regulate mRNA nuclear export and retinal development. Overall design: Examination of nucleocytoplasmic transcript distribution upon MKRN2 knockdown in HEK293 cells