Konieczny S F, Emerson C P
Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907.
Mol Cell Biol. 1987 Sep;7(9):3065-75. doi: 10.1128/mcb.7.9.3065-3075.1987.
A cloned quail troponin I contractile protein gene, stably transfected into a mouse myogenic cell line, exhibits appropriate developmental activation and quantitative expression during myoblast differentiation. Deletion mutagenesis analyses reveal that the troponin I gene has two distinct cis regulatory elements required for its developmental expression, as measured by mRNA accumulation and nuclear runoff transcription assays. One element in the 5' flanking region is required for maximum quantitative expression, and a second larger regulatory element (1.5 kilobases) within the first intron is responsible for differentiation-specific transcription. The upstream region is highly sensitive to negative repression by interaction with pBR322 sequences. The larger intragenic region retains some activity when moved to the 5' and 3' flanking regions and when inverted but is maximally active in its native intragenic site. The concerted activities of these two regulatory regions produce a 100- to 200-fold transcriptional activation during myoblast differentiation. The conserved 5' exon-intron organization of troponin I and other contractile protein genes suggests a possible mechanism by which intragenic control elements coordinate contractile protein gene regulation during skeletal myogenesis.
一个克隆的鹌鹑肌钙蛋白I收缩蛋白基因，稳定转染到小鼠成肌细胞系中，在成肌细胞分化过程中表现出适当的发育激活和定量表达。缺失诱变分析表明，通过mRNA积累和核转录分析测量，肌钙蛋白I基因有两个不同的顺式调控元件，是其发育表达所必需的。5'侧翼区域的一个元件是最大定量表达所必需的，第一个内含子内的第二个更大的调控元件（1.5千碱基）负责分化特异性转录。上游区域通过与pBR322序列相互作用对负调控高度敏感。当较大的基因内区域移至5'和3'侧翼区域以及颠倒时，仍保留一些活性，但在其天然基因内位点活性最高。这两个调控区域的协同活性在成肌细胞分化过程中产生100至200倍的转录激活。肌钙蛋白I和其他收缩蛋白基因保守的5'外显子-内含子组织提示了一种可能的机制，通过该机制基因内控制元件在骨骼肌生成过程中协调收缩蛋白基因的调控。
