Cell non-autonomous regulation of chromosome segregation

Chromosome segregation has been assumed to be a cell-autonomous process. We tested this assumption by comparing chromosome segregation fidelity in epithelial cells in various contexts and discovered that these cells have increased chromosome missegregation outside of their native tissue. Using organoid culture systems, we show that tissue architecture, specifically integrin function, is required for accurate chromosome segregation in epithelia. We find that tissue architecture enhances the correction of merotelic microtubule-kinetochore attachments, and this is critically important for maintaining chromosome stability in the polyploid liver. Our data lead to the surprising conclusion that chromosome segregation in epithelia is a cell non-autonomous process. We propose that disruption of tissue architecture could underlie the chromosome instability that characterizes and drives epithelial cancers. Moreover, our findings highlight the importance of context for fundamental cellular processes and caution against the exclusive reliance on cell culture systems for deciphering and manipulating mammalian biology. Three biological replicates of mammary epithelial cells were seeded on collagen-coated dishes to form monolayers or embedded in Matrigel to form spheroids and cultured for 48 or 96 hours.