Muller S R, Huff S Y, Goode B L, Marschall L, Chang J, Feinstein S C
Neuroscience Research Institute, University of California, Santa Barbara 93106.
J Neurosci Res. 1993 Feb 15;34(3):304-14. doi: 10.1002/jnr.490340307.
In an effort to understand molecular mechanisms by which nerve growth factor (NGF) regulates gene expression, we have isolated a full-length rat cDNA clone encoding ornithine decarboxylase (ODC) and utilized this probe to identify and examine the transcriptionally active, NGF inducible ODC gene in rat PC12 cells. This same gene is also responsive to epidermal growth factor, basic fibroblasts growth factor, and dibutyryl cAMP. Primer extension analysis demonstrates that both basal and NGF induced transcription of the ODC gene utilize the same major transcriptional start site, demonstrating that NGF acts to increase transcriptional activity at the basal start site as opposed to unmasking an alternative, stronger start site. Functional promoter analysis reveals the presence of a constitutive core promoter residing between positions -201 and +390, relative to the start site of transcription. Additional analyses reveal that sequences in the region -7800 to +2257 are insufficient to mediate NGF induced transcriptional activation, demonstrating that at least some of the regulatory sequences necessary for NGF mediated transcriptional induction of the ODC gene must reside at relatively enormous distances from the transcriptional start site. Such a long distance transcriptional regulatory mechanism is unique when compared with other NGF responsive genes that have been similarly analyzed.
为了了解神经生长因子（NGF）调节基因表达的分子机制，我们分离出了一个编码鸟氨酸脱羧酶（ODC）的大鼠全长cDNA克隆，并利用该探针在大鼠PC12细胞中鉴定和检测转录活性的、NGF诱导的ODC基因。同一个基因也对表皮生长因子、碱性成纤维细胞生长因子和二丁酰环磷腺苷作出反应。引物延伸分析表明，ODC基因的基础转录和NGF诱导转录都利用相同的主要转录起始位点，这表明NGF的作用是增加基础起始位点的转录活性，而不是揭示另一个更强的起始位点。功能性启动子分析揭示，相对于转录起始位点，在-201至+390位之间存在一个组成型核心启动子。进一步分析表明，-7800至+2257区域的序列不足以介导NGF诱导的转录激活，这表明ODC基因的NGF介导转录诱导所需的至少一些调控序列必定位于距转录起始位点相对较远的位置。与其他经过类似分析的NGF反应基因相比，这种长距离转录调控机制是独特的。
