miR-191 is a family of microRNA precursors found in mammals, including humans. The ~22 nucleotide mature miRNA sequence is excised from the precursor hairpin by the enzyme Dicer.[1] This sequence then associates with RISC which effects RNA interference.[2]
miR-191 has been found to be dysregulated in many types of human tumour, including those of colorectal,[3]breast and prostate cancers.[4] Despite these cancer links, target genes of the mature miRNA have not been characterised, and it is not known which factors lead to its dysregulation in certain tumour cells.[5]
The expression profile of miR-191 could be implemented in prognosis of acute myeloid leukaemia, with higher than average levels of miR-191 suggesting a lower survival probability.[6]
miR-191 plays an important role in erythropoiesis. Downregulation of miR-191 leads to upregulation of its target genes RIOK3 and MXI1, which together regulate erythroblast chromatin condensation and enucleation.[7][8]