Closing the Gap

When faced with a wound or the open spaces that occur normally during tissue development, epithelial cells are compelled to close those gaps, but the mechanisms driving this activity are not fully understood. Some studies have emphasized the purse-string method of closure, which involves the contraction of an actomyosin belt formed by the cells surrounding the open space, while others have proposed that lamellipodia—the leading edges or “feet” of a cell projected forward by actin filaments—guide cell migration into the open space. Benoît Ladoux at the National University of Singapore and his colleagues developed a new way to examine how epithelial cells fill in empty spaces: a gap is created by growing cell monolayers around a column, which is later removed. Previous studies have typically used wound assays that involved ablating cells with a laser or scratching through tissue, resulting in possible cell death and debris. Instead, when Ladoux’s group ...