Deelman L E, Jonk L J, Henning R H
Department of Clinical Pharmacology, Groningen Institute for Drug Studies, University of Groningen, The Netherlands.
Gene. 1998 Jan 30;207(2):219-25. doi: 10.1016/s0378-1119(97)00630-6.
In humans, at least three types of inositol (1,4,5)-trisphosphate receptor (IP3R) are present. The gene encoding type 1 IP3R (IP3R-I) is expressed in all cell types, although expression predominates in Purkinje cells. To study the regulation of the human IP3R-I gene, we isolated and characterized a 2.1-kb 5' flanking region. In transient expression assays using a rat cell line, analysis of various deletion mutants demonstrated that a fragment of only 86 bp 5' of the putative tsp displayed a promoter activity similar to that of the 2.1-kb fragment. Also, we compared the sequence of the human IP3R-I promoter with the sequence of the mouse IP3R-I promoter. Considerable sequence homology is present in four distinct domains, which include several conserved putative binding sites for transcription factors. Further, we demonstrate a decrease in the activity of the isolated human IP3R-I promoter and of the endogenous IP3R-I promoter after 48 h of treatment with retinoic acid. Analysis of deletion constructs of the human promoter indicates that the decreased promoter activity in response to retinoic acid is likely to be mediated by a conserved AP-2 binding site.
在人类中，至少存在三种类型的肌醇（1,4,5）-三磷酸受体（IP3R）。编码1型IP3R（IP3R-I）的基因在所有细胞类型中均有表达，尽管在浦肯野细胞中表达占主导。为了研究人类IP3R-I基因的调控，我们分离并鉴定了一个2.1 kb的5'侧翼区域。在使用大鼠细胞系的瞬时表达分析中，对各种缺失突变体的分析表明，推定转录起始点（tsp）上游仅86 bp的片段表现出与2.1 kb片段相似的启动子活性。此外，我们比较了人类IP3R-I启动子与小鼠IP3R-I启动子的序列。在四个不同结构域中存在相当程度的序列同源性，其中包括几个保守的推定转录因子结合位点。此外，我们证明在用视黄酸处理48小时后，分离的人类IP3R-I启动子和内源性IP3R-I启动子的活性降低。对人类启动子缺失构建体的分析表明，视黄酸诱导的启动子活性降低可能是由一个保守的AP-2结合位点介导的。
