The mammalian midbody and midbody remnant are assembly sites for RNA and localized translation

Long ignored as a vestigial remnant of cytokinesis, the mammalian midbody (MB) is released post-abscission inside large extracellular vesicles called MB remnants (MBRs). Recent evidence suggests that MBRs can modulate cell proliferation and cell fate decisions. Here, we demonstrate that the MB matrix is the site of ribonucleoprotein assembly and is enriched in mRNAs that encode proteins involved in cell fate, oncogenesis, and pluripotency, which we are calling the MB granule. Both MBs and post-abscission MBRs are sites of spatiotemporally regulated translation, which is initiated when nascent daughter cells re-enter G1 and continues after extracellular release. MKLP1 and ARC are necessary for the localization and translation of RNA in the MB dark zone, whereas ESCRT-III is necessary to maintain translation levels in the MB. Our work reveals a unique translation event that occurs during abscission and within a large extracellular vesicle. [Display omitted] •The midbody is the assembly site of an RNP granule which we call the MB granule•Distinct oncogenic and pluripotent transcription factor RNAs are packaged in MBs and MBRs•The MB and MBR are sites of active translation•Multiple cell types including cancer, stem, and neural stem have actively translating MBRs Midbodies (MBs) are released post-abscission as large extracellular vesicles called MB remnants (MBRs). Here, we demonstrate that the MB matrix is the site of ribonucleoprotein assembly and is enriched in mRNAs that encode proteins involved in cell fate, oncogenesis, and pluripotency, which we are calling the MB granule, which is unique in that it is translationally active.