酵母基因组分析表明,从有丝分裂向形成配子的减数分裂的转化与基因表达谱所发生的一个骤变有关。只在减数分裂过程中表达的一种蛋白是细胞周期蛋白Rem1,该蛋白增强减数分裂前的基因内重组,保证减数分裂的顺利进行。
现在,Moldon等人发现,Rem1在裂殖酵母Saccharomyces pombe中的表达不仅在转录层面上受控,而且也被接合控制。在有丝分裂细胞中,Fkh2转录因子与Rem1启动子的结合会产生一个能留住其内含子(introns)的转录,从而只会有一个短蛋白产生,该蛋白影响重组水平。在减数分裂细胞中,一个减数分裂特定的转录因子Mei4与Rem1启动子的结合会导致Rem1的接合,并产生活性细胞周期蛋白。所以,两个转录因子可对同一基因的接合进行不同的修饰。(生物谷Bioon.com)
生物谷推荐原始出处:
Nature 455, 997-1000 (16 October 2008) | doi:10.1038/nature07325; Received 28 May 2008; Accepted 6 August 2008; Published online 24 September 2008
Promoter-driven splicing regulation in fission yeast
Alberto Moldón1, Jordi Malapeira1, Natalia Gabrielli1, Madelaine Gogol2, Blanca Gómez-Escoda1, Tsvetomira Ivanova1, Chris Seidel2 & José Ayté1
1 Oxidative Stress and Cell Cycle Group, Universitat Pompeu Fabra, C/Doctor Aiguader 88, Barcelona 08003, Spain
2 Stowers Institute, Kansas City, Missouri 64110, USA
The meiotic cell cycle is modified from the mitotic cell cycle by having a pre-meiotic S phase that leads to high levels of recombination, two rounds of nuclear division with no intervening DNA synthesis and a reductional pattern of chromosome segregation. Rem1 is a cyclin that is only expressed during meiosis in the fission yeast Schizosaccharomyces pombe. Cells in which rem1 has been deleted show decreased intragenic meiotic recombination and a delay at the onset of meiosis I (ref. 1). When ectopically expressed in mitotically growing cells, Rem1 induces a G1 arrest followed by severe mitotic catastrophes. Here we show that rem1 expression is regulated at the level of both transcription and splicing, encoding two proteins with different functions depending on the intron retention. We have determined that the regulation of rem1 splicing is not dependent on any transcribed region of the gene. Furthermore, when the rem1 promoter is fused to other intron-containing genes, the chimaeras show a meiotic-specific regulation of splicing, exactly the same as endogenous rem1. This regulation is dependent on two transcription factors of the forkhead family, Mei4 (ref. 2) and Fkh2 (ref. 3). Whereas Mei4 induces both transcription and splicing of rem1, Fkh2 is responsible for the intron retention of the transcript during vegetative growth and the pre-meiotic S phase.