KIF5B modulates central spindle organization in late-stage cytokinesis in chondrocytes

The growth plate is a special region of the cartilage that drives longitudinal growth of long bones. Proliferating chondrocytes in the growth plate, arranged in columns, divide perpendicular to the long axis of the growth plate then intercalate to re-align with parental columns. Which molecular partners maintain growth plate columnar structures and chondrocyte cytokinesis has not been fully revealed. It is reported that kinesin family member 3A (KIF3A), a subunit of kinesin-2, plays an important role in maintaining columnar organization in growth plates via controlling primary cilia formation and cell proliferation.

Here we identify kinesin family member 5B (KIF5B), the heavy chain of kinesin-1, a ubiquitously expressed motor protein for anterograde intracellular transport along the microtubule network, as a key modulator of cytokinesis in chondrocytes via maintenance of central spindle organization. We show that KIF5B is concentrated in the central spindle during cytokinesis in both primary chondrocytes and chondrogenic ATDC5 cells.

The failure of cytokinesis in KIF5B null chondrocytes leads to incomplete cell rotation, disrupting proliferation and differentiation, and results in a disorganized growth plate.