Yoshikai S, Sasaki H, Doh-ura K, Furuya H, Sakaki Y
Research Laboratory for Genetic Information, Faculty of Medicine, Kyushu University, Fukuoka, Japan.
Gene. 1990 Mar 15;87(2):257-63. doi: 10.1016/0378-1119(90)90310-n.
Amyloid beta-protein (BP) deposited in Alzheimer brains is a cleavage product of a larger precursor (BPP). The BPP gene encodes three types of mRNA generated by alternative splicing, two of which contain the sequence encoding Kunitz-type serine-protease inhibitor (serpin). To investigate the regulatory mechanisms of BPP synthesis at the gene level, we isolated 36 genomic DNA clones covering all the exons of the human BPP gene. This gene consists of 18 exons and spans more than 170 kb. BP is encoded by the 16th and the 17th exons and the serpin domain by the 7th exon. Sequence analysis showed that the 7th and 8th introns lack a typical branchpoint for splicing. This might relate to the alternative splicing. The promoter of the BPP gene has some characteristics of those of housekeeping genes and contains a number of possible methylation sites. The methylation status of the promoter was analyzed by Southern blotting but no alteration was observed among tissues and between control and Alzheimer brains. We also tested the roles of two possible activator protein-1-binding sites and a possible heat-shock element found within the promoter. Northern blotting showed that the transcription of the BPP gene was apparently induced by 12-O-tetradecanoylphorbol-13-acetate (phorbol derivative) in HeLa cells.
沉积在阿尔茨海默病患者大脑中的β-淀粉样蛋白（BP）是一种较大前体（BPP）的裂解产物。BPP基因通过可变剪接编码三种类型的mRNA，其中两种含有编码Kunitz型丝氨酸蛋白酶抑制剂（丝氨酸蛋白酶抑制剂）的序列。为了在基因水平上研究BPP合成的调控机制，我们分离了36个覆盖人类BPP基因所有外显子的基因组DNA克隆。该基因由18个外显子组成，跨度超过170kb。BP由第16和17外显子编码，丝氨酸蛋白酶抑制剂结构域由第7外显子编码。序列分析表明，第7和第8内含子缺乏典型的剪接分支点。这可能与可变剪接有关。BPP基因的启动子具有管家基因启动子的一些特征，并包含许多可能的甲基化位点。通过Southern印迹分析启动子的甲基化状态，但在组织之间以及对照和阿尔茨海默病大脑之间未观察到改变。我们还测试了启动子内发现的两个可能的激活蛋白-1结合位点和一个可能的热休克元件的作用。Northern印迹显示，在HeLa细胞中，12-O-十四酰佛波醇-13-乙酸酯（佛波醇衍生物）明显诱导了BPP基因的转录。
