Sewards R, Wiseman B, Jacobs H T
Robertson Institute of Biotechnology, Department of Genetics, University of Glasgow, Scotland, UK.
Mol Gen Genet. 1994 Dec 15;245(6):760-8. doi: 10.1007/BF00297283.
We have constructed a series of reporter constructs which test the effects of sequence elements from the control region of human mitochondrial DNA on expression in the nucleus, as assayed by transient expression in cultured human cells. The mitochondrial heavy-strand promoter (HSP) was unable to function as a promoter in nuclear DNA. Neither the HSP, nor the binding region for the mitochondrial transcription factor mtTF1 from the light-strand promoter, had any significant or systematic modulatory effects upon transcription from strong or weak RNA polymerase II (pol II) promoters, in three different human cell lines. The same finding held true regardless of orientation with respect to the start site of transcription. Similar results were obtained with a rho 0 derivative of one of these lines, indicating that mitochondrial promoter sequences in the nucleus cannot modulate transcription in response to altered mtDNA copy number. These results support the view that the nuclear and mitochondrial transcription systems in human cells are functionally independent, and do not communicate through factors recognizing shared sequence elements, as suggested by studies in yeast.
我们构建了一系列报告基因构建体，通过在培养的人类细胞中进行瞬时表达来检测人类线粒体DNA控制区的序列元件对细胞核内表达的影响。线粒体重链启动子（HSP）在核DNA中无法作为启动子发挥作用。在三种不同的人类细胞系中，HSP以及轻链启动子中线粒体转录因子mtTF1的结合区域，对强或弱的RNA聚合酶II（pol II）启动子的转录均无任何显著或系统性的调节作用。无论相对于转录起始位点的方向如何，均得到相同的结果。用其中一个细胞系的rho 0衍生物也获得了类似结果，表明细胞核中的线粒体启动子序列无法响应线粒体DNA拷贝数的改变来调节转录。这些结果支持了这样一种观点，即人类细胞中的核转录系统和线粒体转录系统在功能上是独立的，并且不像酵母研究中所表明的那样，通过识别共享序列元件的因子进行交流。
