First published online July 30, 2004
Journal of Cell Science 117, 1703e (2004)
© The Company of Biologists Limited
Meiosis mei way
In the fission yeast Schizo-saccharomyces pombe, meiosis usually occurs only in diploid zygotes. Upon nitrogen starvation, a mating pheromone signal is transduced through a MAP kinase cascade, and haploid cells with opposite mating types conjugate to form a diploid cell. Zygotic expression of Mei3 is then induced, which inactivates the Pat1 kinase, allowing activation of Mei2, which drives meiosis. On p. 3875, Yasushi Hiraoka and colleagues show that activation of Spk1, the pheromone-responsive MAP kinase, can drive haploid cells to undergo meiosis with normal chromosome behaviour. The authors achieve this through ectopic expression of a constitutively active form of the MAP kinase kinase Byr1 and show that, in this situation, induction of meiosis requires Mei2 but not Mei3. Furthermore, telomeres cluster at the spindle pole body to form a bouquet, as happens in normal meiosis, and the chromosomes separate normally. The authors conclude that Spk1 activation by constitutively active Byr1 can activate Mei2 sufficiently to drive meiosis in S. pombe, even in the absence of Mei3, and propose a new model for the genetic regulation of both meiosis and telomere clustering.
Related articles in JCS:
- Activation of the pheromone-responsive MAP kinase drives haploid cells to undergo ectopic meiosis with normal telomere clustering and sister chromatid segregation in fission yeast
- Takaharu G. Yamamoto, Yuji Chikashige, Fumiyo Ozoe, Makoto Kawamukai, and Yasushi Hiraoka
JCS 2004 117: 3875-3886.
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