miR-155 indicates the fate of CD4 T cells.

MicroRNAs (miRNAs) are a class of short noncoding RNAs that regulate the translation of target messenger RNA (mRNA) and consequently participate in a variety of biological processes at the posttranscriptional level. miR-155, encoded within a region known as the B cell integration cluster (BIC), plays multifunctional roles in shaping lymphocytes ranging from biological development to adaptive immunity. It has been revealed that miR-155 plays a key role in fine-tuning the regulation of lymphocyte subsets, including dendritic cells (DCs), macrophages, B cells, and CD8 and CD4 T cells. Antigen-specific CD4 T lymphocytes are critical for host defense against pathogens and prevention of damage resulting from excessive inflammation. Over the past years, various studies have shown that miR-155 plays a critical role in CD4 T cells function. Therefore, we summarize multiple target genes of miR-155 that regulate aspects of CD4 T cells immunity, particularly CD4 T cells differentiation, in this review. In addition, we also focus on the role of miR-155 in the regulation of immunological diseases, suggesting it as a potential disease biomarker and therapeutic target.