Using a cell line with a single Lac operator array on chromosome 1, Josh demonstrated that locally enriching just the PST-repeat region fuses to the Lac inhibitor at this site was sufficient to trigger chromosome missegregation. 4/n

But why does MDC1 have to be globally removed from chromatin in mitosis? To address this question Josh expressed non-phosphorylatable variants of MDC1, which led to dramatic chromosome missegregation. Essentially, chromosomes were “glued” together. 3/n

In previous work, Josh demonstrated that MDC1 is constitutively chromatin associated using single-molecule imaging. Interestingly, he observed rare cells in which MDC1 was highly mobile, which turned out to be in mitosis. 2/n

Here is a fun little teaser! What DNA repair factor does this to mitotic chromosomes? Pre-print should be up any time now! Exciting work by @heyzajr.bsky.social!