Dividing cells that lack Tektin 2 fail to separate.

Like parents sending their child off to college, a dividing cell has to let its offspring go. A microtubule-organizing protein helps ensure that the daughter cell breaks free, Durcan et al. report.

When chromosomes begin to pull apart during mitosis, the microtubules in the middle of the cell bunch up into a structure known as the central spindle. As the new cell begins to pinch off, it remains connected to its parent by a tether, the midbody, which contains the central spindle and doesn't part until after division is complete. Microtubules in developing flagella and cilia are arranged with the help of a protein called Tektin 2. Durcan et al. were therefore curious whether this protein performs a similar job in the midbody tether.

To determine the protein's function, the scientists slashed its levels with siRNA. Although Tektin 2–lacking cells seemed to divide normally, they often reunited. For a closer look at what occurred in the central spindle, the team treated cells with blebbistatin, which prevents dividing cells from pinching in two. Microtubules in the central spindle normally form a bundle, but they were jumbled in blebbistatin-treated cells dosed with Tektin 2 siRNA.

The team concluded that Tektin 2 promotes cell separation by bundling the microtubules of the central spindle. How Tektin 2 achieves this feat isn't clear, but they hypothesize that it sets the length of microtubules in the central spindle, controlling how much overlap occurs between microtubules from the would-be parent and offspring cells.

Durcan, T.M., et al.
J. Cell Biol.