The cells that line our body cavities assemble a top and bottom with unique structures and functions. As cells polarize to develop this epithelial character, microtubules that support the cell’s structure orient top to bottom. How they become well-organized was unknown until Mika Toya and colleagues in ASCB member Masatoshi Takeichi’s lab at the RIKEN Center for Developmental Biology in Kobe, Japan, found that in intestinal cells a microtubule minus-end binding protein (CAMSAP3) tethers microtubules at the top (apical) surface to promote their longitudinal orientation. They also found this process is essential for organelle positioning. Published in PNAS.
