Functional roles of poleward microtubule flux during mitosis.

Poleward microtubule flux is a conserved process during mitosis and meiosis in metazoan cells and is defined as the translocation of spindle microtubules toward spindle poles coupled to the depolymerization of their minus-ends. In some cell types, the rate of poleward microtubule flux matches that of poleward chromatid movement during anaphase A, suggesting that it pulls chromatids poleward. However, in other cell types, the rate of poleward microtubule flux is significantly slower than chromatid movement during anaphase A, suggesting that it makes little contribution to chromatid movement. This discrepancy led to speculation that flux is maintained in these cells to fulfill other functional roles aside from contributing to anaphase A chromatid movement. These roles include contributing to chromosome alignment, regulating spindle size and microtubule turnover, and correcting errors in chromosome attachment to spindle microtubules. Here, we discuss recent data that begin to pinpoint the functional roles of poleward microtubule flux during mitosis and meiosis.