Jehan F, DeLuca H F
Department of Biochemistry, College of Agricultural and Life Sciences, University of Wisconsin-Madison, Madison, WI 53706, USA.
Proc Natl Acad Sci U S A. 1997 Sep 16;94(19):10138-43. doi: 10.1073/pnas.94.19.10138.
The gene encoding the mouse vitamin D receptor has been cloned. A new exon 1 has been found that changes the numbering established for the human VDR gene. Exons 2 and 3 in the human VDR gene (coding for the zinc fingers 1 and 2, respectively) are named exons 3 and 4 in the mouse vitamin D receptor. The 1.5-kb 5'-flanking region of the new exon 1 was analyzed and revealed the presence of putative cis-acting elements. Despite the absence of a TATA box, this 5'-flanking region contains several characteristics of a GC-rich promoter including four Sp1 sites present in tandem and two CCAAT boxes. Interestingly, the Sp1 site that is the most proximal to the new exon 1 overlaps a perfect site for Krox-20/24. Krox-20 is a transcription factor involved in brain development, and also in bone remodeling. In luciferase reporter gene expression assays, we showed that sequences from this 5'-flanking region elicit high transactivation activity. Furthermore, in the NIH 3T3 cell line, a 3- to 5-fold increase in response to forskolin treatment (an activator of adenylate cyclase and in turn of protein kinase A pathway) was observed.
编码小鼠维生素D受体的基因已被克隆。发现了一个新的外显子1，它改变了人类维生素D受体（VDR）基因已确定的编号。人类VDR基因中的外显子2和3（分别编码锌指1和2）在小鼠维生素D受体中被命名为外显子3和4。对新外显子1的1.5kb 5'侧翼区域进行了分析，发现了推定的顺式作用元件。尽管没有TATA框，但该5'侧翼区域具有富含GC的启动子的几个特征，包括串联存在的四个Sp1位点和两个CCAAT框。有趣的是，最靠近新外显子1的Sp1位点与Krox-20/24的完美位点重叠。Krox-20是一种参与脑发育以及骨重塑的转录因子。在荧光素酶报告基因表达分析中，我们表明该5'侧翼区域的序列引发了高反式激活活性。此外，在NIH 3T3细胞系中，观察到对福斯可林处理（腺苷酸环化酶激活剂，进而激活蛋白激酶A途径）的反应增加了3至5倍。
