Kuhn A, Vente A, Dorée M, Grummt I
German Cancer Research Center, Heidelberg, D-69120, Germany.
J Mol Biol. 1998 Nov 20;284(1):1-5. doi: 10.1006/jmbi.1998.2164.
Entry into mitosis is accompanied by a global repression of transcription. To investigate the molecular mechanisms which shut-down rRNA synthesis during mitosis, we have compared RNA polymerase I (Pol I) transcription in extracts from asynchronous and mitotic HeLa cells. We show by several experimental approaches that phosphorylation by cdc2/cyclin B inactivates the TBP-containing factor SL1 and thus abrogates Pol I transcription during mitosis. This finding links the cell's cycle with the transcriptional activity of Pol I and suggests a common mechanism for mitotic silencing of all three classes of nuclear RNA polymerases, i.e. reversible inactivation of the respective TBP-TAF complexes by (a) mitotic kinase(s).
进入有丝分裂伴随着转录的全面抑制。为了研究在有丝分裂期间关闭rRNA合成的分子机制，我们比较了来自异步和有丝分裂期HeLa细胞提取物中的RNA聚合酶I（Pol I）转录。我们通过几种实验方法表明，cdc2/细胞周期蛋白B介导的磷酸化使含TBP的因子SL1失活，从而在有丝分裂期间消除Pol I转录。这一发现将细胞周期与Pol I的转录活性联系起来，并提示了所有三类核RNA聚合酶有丝分裂沉默的共同机制，即通过一种（或多种）有丝分裂激酶使各自的TBP-TAF复合物可逆失活。
