基因轉(zhuǎn)錄在細(xì)胞分裂期間會停止，人們知道這一事實已超過40年了,。對這一點的解釋一直是：染色體凝縮限制了RNA聚合酶的活性,，但對芽殖酵母所做的一項研究表明，事實并不是這樣的,。
真實情況是,，保守磷酸酶CDC14（核仁分離和有絲分裂退出所需的一種有絲分裂調(diào)控因子）通過阻止RNA聚合酶-I（Pol-I）在分裂后期向核糖體DNA定位而引起基因沉默。如果核糖體轉(zhuǎn)錄不關(guān)閉,，那么轉(zhuǎn)錄體的存在將會阻止凝縮蛋白的加載和阻斷染色體凝縮及分離,。（生物谷Bioon.com）
生物谷推薦原始出處：
Nature 458, 219-222 (12 March 2009) | doi:10.1038/nature07652
Cdc14 inhibits transcription by RNA polymerase I during anaphase
Andrés Clemente-Blanco1, María Mayán-Santos1, David A. Schneider2, Félix Machín1,4, Adam Jarmuz1, Herbert Tschochner3 & Luis Aragón1
1 Cell Cycle Group, MRC Clinical Sciences Centre, Imperial College, Du Cane Road, London W12 0NN, UK
2 Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, 442 Kaul Human Genetics Building, 720 20th Street South, Birmingham, Alabama 35294, USA
3 Institut für Biochemie, Mikrobiologie und Genetik, Universit?t Regensburg, Munich, Germany
4 Present address: Unidad de Investigación, Hospital Universitario Candelaria, Carretera del Rosario, 38010 Tenerife, Spain.
Chromosome condensation and the global repression of gene transcription1 are features of mitosis in most eukaryotes. The logic behind this phenomenon is that chromosome condensation prevents the activity of RNA polymerases. In budding yeast, however, transcription was proposed to be continuous during mitosis2. Here we show that Cdc14, a protein phosphatase required for nucleolar segregation3 and mitotic exit4, inhibits transcription of yeast ribosomal genes (rDNA) during anaphase. The phosphatase activity of Cdc14 is required for RNA polymerase I (Pol I) inhibition in vitro and in vivo. Moreover Cdc14-dependent inhibition involves nucleolar exclusion of Pol I subunits. We demonstrate that transcription inhibition is necessary for complete chromosome disjunction, because ribosomal RNA (rRNA) transcripts block condensin binding to rDNA, and show that bypassing the role of Cdc14 in nucleolar segregation requires in vivo degradation of nascent transcripts. Our results show that transcription interferes with chromosome condensation, not the reverse. We conclude that budding yeast, like most eukaryotes, inhibit Pol I transcription before segregation as a prerequisite for chromosome condensation and faithful genome separation.
