Transcription factor FOXM1 specifies the loading of chromatin DNA to extracellular vesicles

Extracellular vesicle DNA (evDNA) acts as a potential mechanism for intercellular communication and possesses an important diagnostic value for multiple diseases. In this study, we have provided the first example that transcription factor determines the sources of evDNA from chromatin DNA. Transcription factor FOXM1 mediates the loading of specific chromatin DNA fragments into extracellular vesicles (EVs). Specifically, certain chromatin DNA fragments are specified by FOXM1 and form LC3-FOXM1-DNA vesicles in cytoplasm. Then the cytoplasmic LC3-FOXM1-DNAs are transported to EVs through the process of an autophagosome-MVB transport. The roles of FOXM1 on loading the DNA fragments to cytoplasm and then EVs are further supported by the results of the DNA-FISH experiment, the visualization of TetR-GFP on the DNA fragments from the certain chromatin loci with a knock-in TetO array, and the transfection of a constructed DNA containing multiple FOXM1 binding sites into cells followed by the measurements of the DNA in EVs. We have proved that the LC3-FOXM1-DNAs exist on outside the lumen of EVs as a linear DNA form. Furthermore, the LC3-FOXM1-DNAs of EVs can be absorbed by recipient cells and stay in the recipient cells as long as four weeks. This discovery provides a new clue to understand the sources of evDNA and to further study the potential functions of evDNA in the future.