LINKIN-associated proteins necessary for tissue integrity during collective cell migration

Cell adhesion plays essential roles in almost every aspect of metazoan biology. LINKIN (Human: ITFG1,Caenorhabditis elegans:lnkn-1) is a conserved transmembrane protein that has been identified to be necessary for tissue integrity during migration. InC. elegans, loss oflnkn-1results in the detachment of the lead migratory cell from the rest of the developing male gonad. Previously, three interactors of ITFG1/lnkn-1– RUVBL1/ruvb-1, RUVBL2/ruvb-2, and alpha-tubulin – were identified by immunoprecipitation-mass spectrometry (IP-MS) analysis using human HEK293T cells and then validated in the nematode male gonad. The ITFG1-RUVBL1 interaction has since been independently validated in a breast cancer cell line model that also implicates the involvement of the pair in metastasis. Here, we showed that epitope-tagged ITFG1 localized to the cell surface of MDA-MB-231 breast cancer cells. Using IP-MS analysis, we identified a new list of potential interactors of ITFG1.Loss-of-functionanalysis of theirC. elegansorthologs found that three of the interactors – ATP9A/tat-5, NME1/ndk-1, and ANAPC2/apc-2– displayed migratory detachment phenotypes similar to that oflnkn-1. Taken together with the other genes whose reduction-of-function phenotype is similar to that oflnkn-1(notably cohesion and condensin), suggests the involvement of membrane remodeling and chromosome biology in LINKIN-dependent cell adhesion and supports the hypothesis for a structural role of chromosomes in post-mitotic cells.