The Functional Mechanism of MicroRNA in Oral Lichen Planus

Abstract

Non-coding RNAs (ncRNAs) are transcribed from the genomes of mammals and other complex organisms, and many of them are alternately spliced and processed into smaller products. Types of ncRNAs include microRNAs (miRNAs), circular RNAs, and long ncRNAs. miRNAs are about 21 nucleotides long and form a broad class of post-transcriptional regulators of gene expression that affect numerous developmental and physiological processes in eukaryotes. They usually act as negative regulators of mRNA expression through complementary binding sequences in the 3'-UTR of the target mRNA, leading to translation inhibition and target degradation. In recent years, the importance of ncRNA in oral lichen planus (OLP), particularly miRNA, has attracted extensive attention. However, the biological functions of miRNAs and their mechanisms in OLP are still unclear. In this review, we discuss the role and function of miRNAs in OLP, and we also describe their potential functional roles as biomarkers for the diagnosis of OLP. MiRNAs are promising new therapeutic targets, but more work is needed to understand their biological functions.

Keywords: biomarker; miRNA; oral lichen planus; therapy.

Figure 1

Biogenesis of microRNA. (A) MiRNA is transcribed by RNA polymerase (Pol) II or III into primary (pri)‐miRNA, which is then (B) processed by Drosha into precursor (pre)‐miRNA. (C) The pre‐miRNA is transported from the nucleus into the cytoplasm by exportin 5, where it is then (D) processed by Dicer into a miRNA duplex. (E) The unwinding of the duplex results in the degradation of the passenger strand, and the (F) incorporation of the mature strand into RNA‐induced silencing complex (RISC). The RISC then suppresses the gene expression of a target messenger RNA (mRNA) by either (G) mRNA degradation or (H) translational repression, resulting in the regulation of the cellular function. (I) Furthermore, miRNAs can also be packaged into exosomes, which are then (J) compartmentalized into a multivesicular body (MVB). (K) The MVB fuses with the plasma membrane, resulting in the transfer of miRNA‐containing exosomes to recipient cells and mediating intercellular gene regulation.

Figure 2

MiRNAs participate in the regulation of oral lichen planus through multiple signaling pathways.