Secreted midbody remnants are a class of extracellular vesicles molecularly distinct from exosomes and microparticles

Alin Rai,Rong Xu,Maoshan Chen,Richard J Simpson,David W Greening,Wittaya Suwakulsiri

doi:10.1038/s42003-021-01882-z

Alin Rai, Rong Xu + Show 4 more

Open Access

https://doi.org/10.1038/s42003-021-01882-z

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Abstract

During the final stages of cell division, newly-formed daughter cells remain connected by a thin intercellular bridge containing the midbody (MB), a microtubule-rich organelle responsible for cytokinetic abscission. Following cell division the MB is asymmetrically inherited by one daughter cell where it persists as a midbody remnant (MB-R). Accumulating evidence shows MB-Rs are secreted (sMB-Rs) into the extracellular medium and engulfed by neighbouring non-sister cells. While much is known about intracellular MB-Rs, sMB-Rs are poorly understood. Here, we report the large-scale purification and biochemical characterisation of sMB-Rs released from colon cancer cells, including profiling of their proteome using mass spectrometry. We show sMB-Rs are an abundant class of membrane-encapsulated extracellular vesicle (200-600 nm) enriched in core cytokinetic proteins and molecularly distinct from exosomes and microparticles. Functional dissection of sMB-Rs demonstrated that they are engulfed by, and accumulate in, quiescent fibroblasts where they promote cellular transformation and an invasive phenotype.

Highlights

During the final stages of cell division, newly-formed daughter cells remain connected by a thin intercellular bridge containing the midbody (MB), a microtubule-rich organelle responsible for cytokinetic abscission
The focus of this paper is directed at the large-scale preparation of shows MB-Rs are secreted (sMB-Rs) that would allow us to undertake their biophysical and functional characterisation, to ask whether in vitro release of MKLP1 from LIM1863 colorectal cancer (CRC) cells is a general phenomenon or a cancer-cell specific process, and whether MKLP1 is an indicative marker of sMB-Rs
To determine whether sMB-Rs are secreted into the extracellular space, we first investigated whether MKLP1 could be used as a reliable marker for MB/midbody remnant (MB-R) detection

Summary

Introduction

During the final stages of cell division, newly-formed daughter cells remain connected by a thin intercellular bridge containing the midbody (MB), a microtubule-rich organelle responsible for cytokinetic abscission. To determine whether sMB-Rs could be detected in human colon cancer tissues, we analysed MKLP1-or RACGAP1-antibody based immunohistochemical images of human colon cancer tissues publicly available from the Human Protein Atlas (http://www.proteinatlas.org/) This finding is comparable to particle size determinations obtained using nanoparticle-tracking analysis (Supplementary Fig. 13) and sMB-Rs (~300 nm) based on conventional electron microscopy[9].

Results

Conclusion