Figure 1.

Molecular mechanism of ceRNAs and classification. (A) mRNAs, transcribed pseudogenes, lncRNAs and cirRNAs are able to function as competing endogenous RNAs. (B) Downregulation of ceRNAs results in increased availability of miRNA molecules to bind to mRNA, thereby repressing protein translation. (C) Overexpression of ceRNA results in a reduction in free miRNA abundance, facilitating the derepression of mRNAs that contain identical MREs, thus increasing protein expression levels. ceRNA, competing endogenous RNA; mRNA, messenger RNA; lncRNA, long non-coding RNA; cirRNA, circular RNA; miRNA, micro RNA; MRE, miRNA response element.