title: Selective reduction of anaphase B in quinacrine-treated PtK1 cells.
abstract: Quinacrine, an acridine derivative which competitively binds to ATP binding sites, has previously been shown to cause the reorganization of metaphase spindle microtubules (MTs) due to changes in interactions of non-kinetochore microtubules (nkMTs) of opposite polarity (Armstrong and Snyder: Cell Motil. Cytoskeleton 7:10-19, 1987). In the study presented here, mitotic PtK1 cells were treated in early anaphase with concentrations of quinacrine ranging from 2 to 12 microM to determine energy requirements for chromosome motion. The rate and extent of chromosome-to-pole movements (anaphase A) were not affected by these quinacrine treatments. The extent of anaphase B (kinetochore-kinetochore separation) was reduced with increasing concentrations of quinacrine. Five micromolar quinacrine reduced the extent of kinetochore-kinetochore separation by 20%, and addition of 12 microM quinacrine reduced the kinetochore-kinetochore separation by 40%. To determine the role of nkMTs in anaphase spindle elongation, quinacrine-treated metaphase cells were treated with hyperosmotic sucrose concentrations, and spindle elongation was measured (Snyder et al.: Eur J. Cell Biol. 39:373-379, 1985). Metaphase cells treated with 2-10 microM concentrations of quinacrine for 2-5 min reduced spindle lengths by 10-50% prior to 0.5 M sucrose treatment for 5 min. This treatment showed a significant reduction in the ability of sucrose to induce spindle elongation in cells pretreated with quinacrine. As spindle length and birefringence was reduced by quinacrine treatment, sucrose-induced elongation was concomitantly diminished. These data suggest that quinacrine-sensitive linkages are necessary for anaphase B motions. Reduction in these linkages and/or MT length in the nkMT continuum may reduce the ability of the nkMTs to hold compression at metaphase. This form of energy is thought to drive a significant proportion of normal anaphase B in PtK1 cells and sucrose-induced metaphase spindle elongation.
authors.affiliation: Department of Biological Sciences, University of Denver, CO 80208.
authors.forename: L
authors.initials: L
authors.lastname: Armstrong
authors.forename: J A
authors.initials: JA
authors.lastname: Snyder
mesh_terms: D000705:Anaphase / Q000187:drug effects*; D000818:Animals; D002460:Cell Line; D007091:Image Processing, Computer-Assisted; D008854:Microscopy, Electron; D008870:Microtubules / Q000187:drug effects; D011796:Quinacrine / Q000494:pharmacology*; D013395:Sucrose / Q000494:pharmacology
chemical_list: D013395:Sucrose; D011796:Quinacrine