Lindberg C, Wunderlich M, Ratliff J, Dinsmore J, Jacoby D B
Diacrin, Building 96, 13th Street, Charlestown, MA 02129, USA.
Brain Res Dev Brain Res. 1998 Oct 1;110(2):215-26. doi: 10.1016/s0165-3806(98)00110-2.
Using degenerate primers designed to amplify genes containing homeodomains, we have used reverse transcription and polymerase chain reaction to amplify and clone a rat homeobox gene. Based on the nucleotide and predicted amino acid sequences, the rat cDNA clone contains a high degree of sequence similarity to murine genes which are members of the paired-like class of homeobox genes (Ptx2, Otlx2, solurshin and Ptx1). Considering the high degree of sequence similarity and similar restricted expression patterns, we have named the cloned rat gene rPtx2 (rat Ptx2 homolog). Northern analysis revealed two rPtx2 transcripts expressed in the developing rat brain. Yet, only a single gene was detected by Southern blot hybridization, suggesting that multiple messages are the result of alternative transcriptional initiation, splicing or processing of a common message. The expression pattern of rPtx2 was further delineated by in situ hybridization to rat embryos. Within the brain, tissue specific expression was observed in the differentiating neural cells of the posterior hypothalamus, tegmentum, and rhombomere r1. Expression was also observed in the developing pituitary, maxilla, mandible, tongue and umbilical cord. To further study the control of Ptx2 gene expression, we used an in vitro model for neural differentiation by treating mouse embryonic stem cells with retinoic acid. Within 24 h and prior to detection of a neural phenotype in the culture, murine Ptx transcripts were induced and remained elevated for at least 6 days. This suggests that retinoic acid may be an important inductive signal which regulates the developmental and tissue-specific expression of Ptx2.
我们使用简并引物来扩增含有同源结构域的基因，通过逆转录和聚合酶链反应扩增并克隆了一个大鼠同源框基因。根据核苷酸和预测的氨基酸序列，该大鼠cDNA克隆与小鼠基因具有高度的序列相似性，这些小鼠基因是同源框基因配对样类（Ptx2、Otlx2、solurshin和Ptx1）的成员。考虑到高度的序列相似性和相似的受限表达模式，我们将克隆的大鼠基因命名为rPtx2（大鼠Ptx2同源物）。Northern分析显示，在发育中的大鼠脑中表达了两种rPtx2转录本。然而，Southern印迹杂交仅检测到一个基因，这表明多个信息是共同信息的可变转录起始、剪接或加工的结果。通过对大鼠胚胎进行原位杂交进一步描绘了rPtx2的表达模式。在脑内，在下丘脑后部、被盖和菱脑节r1的分化神经细胞中观察到组织特异性表达。在发育中的垂体、上颌骨、下颌骨、舌和脐带中也观察到表达。为了进一步研究Ptx2基因表达的调控，我们使用了一种体外神经分化模型，用视黄酸处理小鼠胚胎干细胞。在24小时内且在培养物中检测到神经表型之前，小鼠Ptx转录本被诱导并至少持续升高6天。这表明视黄酸可能是调节Ptx2发育和组织特异性表达的重要诱导信号。
