MicroRNA-155: A Master Regulator of Inflammation

Abstract

MicroRNAs (miRNAs) are naturally occurring, highly conserved families of transcripts (∼22 nucleotides in length) that are processed from larger hairpin precursors. miRNAs primarily regulate gene expression by promoting messenger RNA (mRNA) degradation or repressing mRNA translation. miRNAs have been shown to be important regulators of a variety of cellular processes involving development, differentiation, and signaling. Moreover, various human diseases, including cancer and immune dysfunction, are associated with aberrant expression of miRNAs. This review will focus on how the multifunctional miRNA, miR-155, regulates inflammatory diseases, including cancer and pulmonary disorders, and also how miR-155 expression and biogenesis are regulated. We will also provide examples of miR-155-regulated networks in coordination with other noncoding RNAs, including long noncoding RNAs as well as coding mRNAs acting as competing endogenous RNAs.

Keywords: inflammation; miR-155; microRNA; noncoding RNAs; regulation.

FIG. 1.

Schematic representation of miR-155 biogenesis: many RNA-binding proteins including KSRP regulate the processing of pri-miR-155 to pre-miR-155 and the mature form.

FIG. 2.

Regulation of miR-155 function by lncRNAs: lncRNAs can act as sponges and regulate the availability of miR-155 for target genes. lncRNA, long noncoding RNAs.

FIG. 3.

Regulation of miR-155 function by mRNAs: mRNAs that harbor multiple MREs for miR-155 can instead bind preferentially to another miRNAs (viz. miR-16) in disease states. MREs, miRNA response elements.