Step by step one goes very far
Project context and summary :
The central part of the intercellular bridge connecting the two daughter cells during cytokinesis is a highly dense structure named the Midbody first described by Flemming in 1891. Work in the past ten years revealed that the midbody is a platform that concentrates essential proteins involved in cytokinetic abscission. After abscission, the midbody is cut on both sides, thus generating a midbody remnant (named MBR). The MBR usually interacts with the cell surface of one of the two daughter cells, before being engulfed in a phagocytic-like manner. We also found that the MBR can be easily released from cells before their engulfment by calcium chelation. Of note, MBRs at the cell surface might act as pro-proliferative, signalling entities but the proteins involved and the mechanisms of MBR anchoring are unknown. A previous proteomic study of the midbody conducted by Skop purified intercellular bridges from cell lysates recovered after cell synchronization, microtubule stabilization and detergent treatment. This pioneer proteomic study, although informative, did not allow the recovery of many key known proteins of the midbody. Here, we set up an experimental protocol to purify intact, detergent-free MBRs in order to have the full proteome of this organelle. Quantitative, label-free proteomics enabled us to identify 529 proteins enriched at least 2 times as compared to whole cell lysates, that we named the “Flemmingsome”. Besides known and well-established proteins of the midbody (MKLP1, MgcRacGAP, AuroraB, INCENP, MKLP2, Rab8, Rab11, Rab35, Citron Kinase, ESCRTs…), we identified new and promising candidates potentially involved in cytokinetic abscission. In addition, we identified 27 transmembrane proteins that are excellent candidates for mediating interactions between the MBR and the receiving daughter cells after cytokinetic abscission. We are also currently exploring whether newly identified candidates could participate in the signalling mediated by the MBRs. We would thus like to create a website that recapitulates the findings of our screen. The proteins discovered represent new candidates for the understanding of cytokinesis and tumorigenesis. This should be instrumental in the field as the previous websites are not updated (Microkits, Uniprot) and do not focus on this particular step of cytokinesis.Related team publications :
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