Shahbazi et al. describe how the adherens junction protein p120-catenin binds to the microtubule plus end–tracking protein CLASP2 to stabilize intercellular adhesions.
Microtubules are closely associated with the cadherin-based adherens junctions between neighboring epithelial cells and, depending on the precise cell type, are required for either junction assembly or turnover. But how microtubules interact with adherens junctions is not entirely clear.
Shahbazi et al. found that p120-catenin, which stabilizes cadherin molecules at the cell surface, bound to the microtubule plus end–tracking protein CLASP2 at the adherens junctions of keratinocytes. CLASP2’s recruitment to junctions was reduced in keratinocytes lacking p120, whereas knocking down CLASP2 reduced p120’s accumulation at intercellular contacts, delaying junction assembly and reducing junction dynamics and stability. Microtubules are usually stabilized when they contact junctions at the cell cortex. In the absence of CLASP2 or p120, however, fewer microtubules approached adherens junctions, and those microtubules that did grow near to adhesions weren’t stabilized. This suggests that p120 and CLASP2 link microtubules to adherens junctions, thereby stabilizing both intercellular adhesions and the cytoskeleton.
Keratinocytes form a multilayered, stratified epidermis. CLASP2 only localized to intercellular adhesions in the basal layer, which contains proliferating epidermal stem cells. The junctions between terminally differentiating suprabasal cells, in contrast, appear to be linked to microtubule minus ends by a protein called Nezha. Senior author Mirna Perez-Moreno now wants to investigate whether the p120–CLASP2 interaction has a specific role in the maintenance of basal progenitor cells.
Text by Ben Short