SINEUP long non-coding RNA acts via PTBP1 and HNRNPK to promote translational initiation assemblies

SINEUPs are long non-coding RNAs (lncRNAs) that contain a SINE element, which up-regulate the translation of target mRNA and have been studied in a wide range of applications for biological and therapeutic tools, although the molecular mechanism is unclear. Here, we focused on the kinetic distribution of target mRNAs and SINEUP RNAs by performing co-transfection of expression vectors for these transcripts into human embryonic normal kidney cells (HEK293T/17) to investigate the network of translational regulation. The results showed that co-localization of target mRNAs and SINEUP RNAs in the cytoplasm was one of the key phenomena. We identified PTBP1 and HNRNPK as essential RNA binding proteins. These proteins contributed to SINEUP RNA sub-cellular distribution and to assembly of translational initiation complexes, leading to enhanced target mRNA translation. These findings will promote a better understanding of the mechanisms on the fate of regulatory RNAs implicated in efficient protein translation.