TPGS1 regulates central spindle microtubule glutamylation and remodeling during telophase and abscission

Microtubules perform a variety of cellular functions, including regulation of mitotic cell division, cilia formation, and neurite extension. Post-translational modifications controlled by the TTLL-family of enzymes confer a host of properties that affect microtubule dynamics and function. Specifically, polyglutamylation of tubulin C-terminal tails plays an important role in regulating microtubule dynamics and function within specific cellular contexts. In this study, we examined contributions from and potential regulators of polyglutamylation during mitosis, focusing on the microtubule remodeling that occurs in telophase once the mitotic spindle has completed chromosome separation. We demonstrate that the anaphase-to-telophase transition is accompanied by an increase in short-chain polyglutamylation of central spindle microtubules. We also show that TTLL1 and TPGS1, subunits of the tubulin polyglutamylation complex, are targeted to the intracellular bridge and midbody during cell progression through telophase. Finally, we demonstrate that loss of TPGS1 leads to defects in remodeling of the central spindle during telophase and impacts the cell's ability to complete mitotic cell division.