Takahashi K, Imano R, Kibe T, Seimiya H, Muramatsu Y, Kawabata N, Tanaka G, Matsumoto Y, Hiromoto T, Koizumi Y, Nakazawa N, Yanagida M, Yukawa M, Tsuchiya E, Ueno M

Pot1 is a single-stranded telomere-binding protein that is conserved from fission yeast to mammals. Deletion of Schizosaccharomyces pombe pot1(+) causes immediate telomere loss. S. pombe Rqh1 is a homolog of the human RecQ helicase WRN, which plays essential roles in the maintenance of genomic stability. Here, we demonstrate that a ...

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pot1Δ rqh1-hd (helicase dead) double mutant maintains telomeres that are dependent on Rad51-mediated homologous recombination. Interestingly, the pot1Δ rqh1-hd double mutant displays a 'cut' (cell untimely torn) phenotype and is sensitive to the anti-microtubule drug thiabendazole. Moreover, the chromosome ends of the double mutant do not enter the pulsed-field electrophoresis gel. These results suggest that the entangled chromosome ends in the pot1Δ rqh1-hd double mutant inhibit chromosome segregation, signifying that Pot1 and Rqh1 are required for efficient chromosome segregation. We also found that POT1-knockdown, WRN-deficient human cells are sensitive to the anti-microtubule drug vinblastine, implying that some of the functions of S. pombe Pot1 and Rqh1 may be conserved in their respective human counterparts POT1 and WRN.

Date: Nov. 22, 2010

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