Functional characterization of a novel noncoding RNA TIFm71 (711.2)

Abstract

Noncoding RNAs which do not encode proteins are involved in many crucial biological processes and are increasingly important. The transcript of a novel CXC chemokine TIF (Tumor‐Induced Factor) which was identified originally from mas‐ induced xenograft has a long 3’‐UTR containing an antisense Alu element. The Alu elements are conserved repeat sequences that belong to the SINE family of retrotransposons found abundantly in primate genomes and their functions remain elusive. Our study showed that a 71nt fragment named as TIFm71 embedded in the middle of Alu element was processed out from TIF mRNA transcript and played regulatory role independently. TIFm71 was predicted to fold into a stem loop structure which is similar to pre‐miRNAs. Using TIFm71‐overexpressing stable cell line, we found that TIFm71 overexpression induced epithelial‐mesenchymal transition (EMT) and the stable clone displayed higher cell mobility. Western protein analysis showed a higher phosphorylated ERK protein level, which suggested that TIFm71 induced EMT through ERK pathway. In addition, a GFP reporter system was used to probe the regulatory role of TIFm71 on gene expression. Comparing to the control, a significant reduction of GFP protein was noted, suggesting that TIFm71 negatively regulated the expression of the coding transcript.