Human dipeptidyl peptidase IV gene promoter: tissue-specific regulation from a TATA-less GC-rich sequence characteristic of a housekeeping gene promoter.
Human dipeptidyl peptidase IV gene promoter: tissue-specific regulation from a TATA-less GC-rich sequence characteristic of a housekeeping gene promoter.
复制标题
人二肽基肽酶 IV 基因启动子：来自管家基因启动子特征的无 TATA 富含 GC 的序列的组织特异性调节。
DOI：
10.1042/bj3110835
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发表时间：
1995
期刊：
影响因子：
--
通讯作者：
Kim,YS
中科院分区：
文献类型：
--
作者：
Böhm,SK;GumJr,JR;Erickson,RH;Hicks,JW;Kim,YS
二肽基肽酶IV基因编码一种在小肠、肺和肾中高度表达的质膜外肽酶。为了更好地了解这种组织特异性表达的机制，我们克隆了人二肽基肽酶IV基因的5 ' -侧翼区域，对其进行了测序和功能表征。5 '侧序列的前500个碱基构成一个未甲基化的CpG岛，包含多个sp1结合位点，缺乏一致的TATA box，所有基因启动子的特征都缺乏组织特异性表达。使用小肠和Caco2细胞RNA进行的rnase保护分析表明，二肽基肽酶IV转录物的起始位点不少于6个主要位点和12个次要位点。在瞬时转染实验中，5 ' -侧翼序列也表现出功能性启动子活性。在这里，不同长度的序列被克隆到荧光素酶基因的上游，并使用脂质体导入培养细胞。在caco和HepG2细胞中，位于-150和-109碱基之间的区域对于高水平启动子活性非常重要。此外，表达高水平二肽基肽酶IV活性的ccao2细胞和HepG2细胞在转染后表现出比酶水平低的3T3、Jurkat或COS-7细胞更高的标准化荧光素酶活性。发现丁酸钠增加了HepG2细胞的酶活性和标准化荧光素酶。因此，尽管二肽基肽酶IV启动子具有内务基因启动子的序列特征，但它具有以组织特异性方式启动转录的能力。
The dipeptidyl peptidase IV gene encodes a plasma-membrane exopeptidase that is highly expressed in small intestine, lung and kidney. In order to better understand the mechanisms responsible for this tissue-specific expression we cloned, sequenced and functionally characterized the 5′-flanking region of the human dipeptidyl peptidase IV gene. The first 500 bases of the 5′-flanking sequence constituted an unmethylated CpG island, contained several Sp1-binding sites and lacked a consensus TATA box, all characteristics of gene promoters lacking tissue-specific expression. RNase-protection analysis using both small intestinal and Caco2 cell RNA indicated that the dipeptidyl peptidase IV transcript was initiated from no fewer than six major and 12 minor start sites. The 5′-flanking sequence also exhibited functional promoter activity in transient transfection experiments. Here, various lengths of the sequence were cloned upstream of a luciferase gene and introduced into cultured cells using lipofectin. A region located between bases -150 and -109 relative to the start of translation was found to be important for high-level promoter activity in both Caco2 and HepG2 cells. Moreover, Caco2 cells and HepG2 cells, which express high levels of dipeptidyl peptidase IV activity, exhibited much higher normalized luciferase activity after transfection than did 3T3, Jurkat or COS-7 cells, which have low enzyme levels. Sodium butyrate was found to increase both enzyme activity and normalized luciferase in HepG2 cells. Thus the dipeptidyl peptidase IV promoter possesses the ability to initiate transcription in a tissue-specific fashion in spite of having the sequence characteristics of a housekeeping gene promoter.