Mir142, also known as microRNA-142, is a microRNA that plays significant roles in multiple biological processes. It is abundant in cells of hematopoietic origin and is involved in lineage differentiation of hematopoietic cells. It can also regulate immune response. The classical stem-loop structure of Mir142 encodes two mature microRNAs, miR142-5p and miR142-3p, which are involved in various regulatory pathways [3].

In a mouse model, Mir142 loss-of-function was found to have a striking synergy with IDH2R140Q, leading to leukemia. Mir142 loss counteracts the aberrant silencing of Hoxa cluster genes by IDH2R140Q, suggesting a novel mechanism of cooperation in leukemogenesis [1]. Also, Mir142 loss-of-function mutations in acute myelogenous leukemia (AML) result in decreased miR-142-5p expression and loss of miR-142-3p function. This leads to increased ASH1L protein expression, aberrant maintenance of Hoxa gene expression in myeloid-committed hematopoietic progenitors, and enhanced disease-initiating activity of IDH2-mutant hematopoietic cells in mice [2].

In conclusion, Mir142 is crucial in hematopoietic cell differentiation and immune regulation. Loss-of-function studies in mouse models have revealed its significant role in leukemogenesis, providing insights into how different mutations cooperate to drive this disease. Understanding Mir142's functions may offer new strategies for diagnosing and treating leukemia.