Fission yeast meu14+ is required for proper nuclear division and accurate forespore membrane formation during meiosis II.

Abstract

Using a meiosis-specific subtracted cDNA library of Schizosaccharomyces pombe, we identified meu14+ as a gene whose expression is upregulated during meiosis. Transcription of meu14+ is induced abruptly after the cell enters meiosis. Its transcription is dependent on the meiosis-specific transcription factor Mei4. In meu14Delta cells, the segregation and modification of the SPBs (spindle pole bodies) and microtubule elongation during meiosis II were aberrant. Meiotic meu14Delta cells consequently produced a high frequency of abnormal tetranucleate cells harboring aberrant forespore membranes and failed to produce asci. In wild-type cells harboring the integrated meu14+-gfp fusion gene, Meu14-GFP first appeared inside the nuclear region at prophase II, after which it accumulated beside the two SPBs at metaphase II. Thereafter, it formed two ring-shaped structures that surrounded the nucleus at early anaphase II. At post-anaphase II, it disappeared. Meu14-GFP appears to localize at the border of the forespore membrane that later develops into spore walls at the end of sporulation. This was confirmed by coexpressing Spo3-HA, a component of the forespore membrane, with Meu14-GFP. Taken together, we conclude that meu14+ is crucial in meiosis in that it participates in both the nuclear division during meiosis II and the accurate formation of the forespore membrane.