Zheng Zhi-Liang
a Department of Biological Sciences, Lehman College , City University of New York , Bronx , NY , USA.
b Plant Nutrient Signaling and Fruit Quality Improvement Laboratory, Citrus Research Institute , Southwest University , Beibei , Chongqing , China.
Transcription. 2017 Aug 8;8(4):268-274. doi: 10.1080/21541264.2017.1321612. Epub 2017 May 26.
Transcriptional control is critical in relaying signals mediated by Ras and Rho family small GTPases to effect gene expression. In the classical model, signaling components such as MAP kinase target sequence-specific transcription factors, which in turn recruit RNA polymerase (Pol) II holoenzyme to the promoter and activate transcription. Findings in recent years have led to the proposal of a shortcut model in which the Mediator components of the Pol II holoenzyme are regulated by signaling pathways. A very recent finding shows that an evolutionarily conserved Rho GTPase signaling pathway can directly modulate the Pol II C-terminal domain (CTD) phosphorylation by inhibiting the CTD phosphatase in yeast and Arabidopsis. This shortcut model allows direct targeting of the Pol II CTD code and thus has an advantage over the classical model in bringing about rapid, large-scale changes in gene expression.
转录调控在将由Ras和Rho家族小GTP酶介导的信号传递以影响基因表达方面至关重要。在经典模型中，诸如丝裂原活化蛋白激酶等信号成分靶向序列特异性转录因子，这些转录因子进而将RNA聚合酶（Pol）II全酶招募至启动子并激活转录。近年来的研究结果提出了一种捷径模型，其中Pol II全酶的中介体成分受信号通路调控。一项最新研究发现表明，一条进化上保守的Rho GTP酶信号通路可通过抑制酵母和拟南芥中的CTD磷酸酶，直接调节Pol II C末端结构域（CTD）的磷酸化。这种捷径模型允许直接靶向Pol II CTD编码，因此在引起基因表达的快速、大规模变化方面比经典模型更具优势。
