Mps1 promotes poleward chromosome movements in meiotic pro-metaphase

Abstract

<jats:title>ABSTRACT</jats:title><jats:p>In prophase of meiosis I, homologous partner chromosomes pair and become connected by crossovers. Chiasmata, the connections formed between the partners enable the chromosome pair, called a bivalent to attach as a single unit to the spindle. When the meiosis I spindle forms, most bivalents are associated with a single spindle pole and go through a series of oscillations on the spindle attaching and detaching from microtubules until the partners of the bivalent are bi-oriented, that is, attached to microtubules from opposite sides of the spindle, and prepared to be segregated at anaphase I. The conserved, kinetochore-associated kinase, Mps1, is essential for the bivalents to be pulled by microtubules across the spindle. Here we explore the role of Mps1 in this process. In <jats:italic>MPS1</jats:italic> mutants, kinetochores can attach to microtubules and, when they are pulled by microtubule de-polymerization, can move at normal speeds across the spindle. In <jats:italic>MPS1</jats:italic> mutants, kinetochores often become locked-in-place on the pro-metaphase spindle and pro-metaphase kinetochore microtubules reduced turnover. Together the results suggest that Mps1 is necessary to promote depolymerization of kinetochore-microtubules during the bi-orientation process.</jats:p>