Proft Markus, Mas Glòria, de Nadal Eulàlia, Vendrell Alexandre, Noriega Núria, Struhl Kevin, Posas Francesc
Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115, USA.
Mol Cell. 2006 Jul 21;23(2):241-50. doi: 10.1016/j.molcel.2006.05.031.
Regulation of gene expression by stress-activated protein kinases (SAPKs) is essential for cell adaptation to extracellular stimuli. Exposure of yeast to high osmolarity results in activation of the SAPK Hog1, which associates with transcription factors bound at target promoters and stimulates transcriptional initiation. Unexpectedly, activated Hog1 also associates with elongating Pol II and components of the elongation complex. Hog1 is selectively recruited to the entire coding region of osmotic stress genes, but not to constitutively expressed genes. Selective association of Hog1 with the transcribed region of osmoresponsive genes is determined by the 3' untranslated region (3' UTR). Lastly, Hog1 is important for the amount of the RNA polymerase II (Pol II) elongation complex and of mRNA produced from genes containing osmoresponsive coding regions. Thus, in addition to its various functions during transcriptional initiation, Hog1 behaves as a transcriptional elongation factor that is selective for genes induced upon osmotic stress.
应激激活蛋白激酶（SAPK）对基因表达的调控对于细胞适应细胞外刺激至关重要。将酵母暴露于高渗透压环境会导致SAPK Hog1的激活，Hog1会与结合在目标启动子上的转录因子结合，并刺激转录起始。出乎意料的是，激活的Hog1还会与延伸中的Pol II以及延伸复合物的组分结合。Hog1被选择性地招募到渗透应激基因的整个编码区域，但不会被招募到组成型表达的基因。Hog1与渗透反应基因转录区域的选择性结合由3'非翻译区（3'UTR）决定。最后，Hog1对于RNA聚合酶II（Pol II）延伸复合物的数量以及含有渗透反应编码区域的基因产生的mRNA数量很重要。因此，除了在转录起始过程中的各种功能外，Hog1还作为一种转录延伸因子，对渗透应激诱导的基因具有选择性。
