Cell Cycle Specificity of Certain Antimicrotubular Drugs in Schizosaccharomyces pombe

Abstract

Of the seven antimicrotubular drugs tested, nocodazole, mebendazole and trifluralin at saturable concentrations failed to inhibit cell division in Schizosaccharomyces pombe, while carbendazim, thiabendazole and chloropropham each at 50 micrograms ml- and amiprophos methyl at 200 micrograms ml-1 completely arrested cell division. This inhibition was associated with striking morphological changes in which carbendazim- and thiabendazole-treated cells became elongated and pseudohyphal, whereas chloropropham- and amiprophos methyl-treated cells appeared small and rounded with occasional V-shaped pairs. Lomofungin staining revealed that nuclear division was also arrested by these drugs. Suspected blockage of defined cell cycle stages was confirmed by pulse-induction experiments which revealed that cells could be synchronized into division using exposure to a drug for one generation. Further experiments with synchronous cultures prepared by size selection showed that different drugs possessed different transition points; for example, carbendazim and thiabendazole were effective in blocking a late stage of the cell cycle just prior to division, whereas amiprophos methyl affected a very early stage. The results suggest that some of the drugs used exert cell cycle specificity in S. pombe either by impairing microtubule assembly mechanisms (as with carbendazim and thiabendazole) or by inhibiting synthesis of tubulin subunits (as with amiprophos methyl). These drugs could prove useful in studies of microtubule biogenesis during the cell cycle in yeast.

Microtubules offset growth site from the cell centre in fission yeast

“…However, it does require attainment of a minimal cell size. The requirement for a minimal cell size can explain the higher branching efficiency observed in our experiments compared with those previously described (Sawin and Nurse, 1998;Toda et al, 1983;Walker, 1982), where shorter cells were examined.…”

“…Tea1 is transported on the tips of growing microtubules (Behrens and Nurse, 2002) and released at cell ends where it associates with the cell cortex (Snaith et al, 2005;Snaith and Sawin, 2003) and recruits the growth machinery (Mata and Nurse, 1997;Feierback et al, 2004). In the presence of short microtubules, such as in cells treated with the microtubule inhibitor thiabendazole (TBZ) (Sawin and Nurse, 1998;Walker, 1982), or in a tea2 kinesin mutant (Verde et al, 1995), Tea1 and the growth machinery become mislocalized, giving rise to branched cells (Sawin and Nurse, 1998;) with a new axis of symmetry. Neither Tea1 nor microtubules appear to be required for polarized growth, although it has been suggested that both are necessary for the establishment of new sites of polarized growth (Sawin and Nurse, 1998;.…”

Pharmacological activation of myosin II paralogs to correct cell mechanics defects

“…In addition, carbamate-7, the originally identified compound whose degradation leads to these two main byproducts, is part of a family of compounds that includes propham and chlorpropham. These compounds have been used widely in herbicides (46) and were previously classified as mitotic inhibitors, with demonstrated growth defects and alterations in spindle morphology (47)(48)(49)(50)(51)(52). Although we found that neither 3,4-DCA nor 4-HAP affected microtubule structure, we have previously demonstrated a link between microtubules and the RacE/14-3-3/MyoII pathway (8).…”

Fission yeast Rad26ATRIP delays spindle-pole-body separation following interphase microtubule damage

“…TBZ, a benzimadazole derivative that targets microtubules, is also known to inhibit late interphase events of the fission yeast cell cycle (Staron and Allard, 1964;Walker, 1982). Using 20 mg/ml TBZ, we also observed that TBZ caused fission yeast to delay spindle-pole-body separation (our unpublished data) and septation, and that both delays were independent of rad26 + (Baschal et al, 2006).…”

“…MBC is known to inhibit late interphase events of the fission yeast cell cycle (Walker, 1982). Recently, it was reported that 75 mg/ml MBC causes a G 2 delay in fission yeast (Balestra and Jimenezk, 2008).…”