Characterization of promoter 1B in the human glucocorticoid receptor gene
Characterization of promoter 1B in the human glucocorticoid receptor gene
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DOI：
10.1016/s0303-7207(01)00676-1
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发表时间：
2002-03-28
影响因子：
4.1
通讯作者：
Vedeckis, WV
中科院分区：
文献类型：
--
作者：
Nunez, BS;Vedeckis, WV
至少三个不同的启动子区（1A、1B和1C）参与人GR基因的表达。启动子1B和1C位于紧邻Oxon 1C转录起始位点上游的2800 bp DNA区域中。含有外显子1B或1C的转录物在多种人类组织和培养细胞中表达。创建了含有启动子1B加1C（-2738至+19）、单独的启动子1B（-2738至-1046）或单独的启动子1C（-1045至+19）的荧光素酶报告基因构建体。所有三种构建体在驱动HeLa（人宫颈癌）细胞中的荧光素酶表达中同样有效。在Jurkat（人T细胞急性淋巴细胞白血病）细胞中，含有启动子113加1C或启动子1B的构建体具有相同的活性，但启动子1B加1C构建体比启动子1C构建体具有更高的活性。然而，在HepG 2（人肝癌）细胞中。启动子1C构建体与启动子1B加1C一样有效，并且是启动子1B的两倍以上。位于Oxon 1B转录起始位点附近的序列包括三个Sp1（FP 2-FP 4）位点。另一个位点（FP 1）含有序列TGATAG，其非常类似于转录因子的加塔家族的共有结合序列。然而，FP 1的寡核苷酸竞争和超位移分析表明，该位点不是加塔蛋白的结合位点。这四个位点是除了三个YY 1和一个Sp1的网站先前报道的启动子1B。在HeLa细胞中，三个YY 1位点的缺失仅导致30%的活性损失，并且仅在所有四个Sp1位点缺失后才发生活性的实质性损失。表明Sp1在这些细胞中GR表达中的关键重要性。相比之下，消除三个YY 1位点导致HepG 2和Jurkat细胞中启动子强度显著降低（分别为64%和77%）。而随后启动子元件的缺失不会导致这些细胞系中启动子活性的实质性变化。本研究表明，启动子1B和1C对于人GR基因的普遍表达都是重要的。这些启动子在不同细胞类型中利用的差异可能反映了细胞中不同的启动子可用性和/或特异性转录因子的水平。这可能有助于不同细胞类型中GR水平的组织特异性表达。(C)2002爱思唯尔科学爱尔兰有限公司保留所有权利。
At least three different promoter regions (1A, 1B, and 1C) are involved in the expression of the human GR gene. Promoters 1B and 1C are found in a 2800 bp region of DNA immediately upstream of the Oxon 1C transcriptional initiation site. Transcripts containing either exon 1B or 1C are expressed in a wide variety of human tissues arid cultured cells. Luciferase reporter constructs were created containing promoter 1B Plus 1C (-2738 to +19), promoter 1B ( -2738 to -1046) alone, or promoter 1C (-1045 to +19) alone. All three constructs were equally effective in driving luciferase expression in HeLa (human cervical carcinoma) cells. In Jurkat (human T-cell acute lymphoblastic leukemia) cells, constructs containing promoters 113 plus 1C or promoter 1B were equally active, but the promoters 1B plus 1C construct vas 351,1;, more active than the promoter 1C construct. However, in HepG2 (human hepatoma) cells. the promoter 1C construct was as effective as promoters 1B Plus 1C and more than twice as effective as promoter 1B. Sequences that reside proximal to the Oxon 1B transcriptional start site included three Sp1 (FP2-FP4) sites. Another site (FP1) contains the sequence TGATAG, which strongly resembles the consensus binding sequence for the GATA family of transcription factors. However, oligonucleotide competition and supershift analysis of FP1 indicates that this site is not a binding site for GATA proteins. These four sites are in addition to three YY1 and one Sp1 sites previously reported in promoter 1B. In HeLa cells, deletion of the three YY1 sites results in only a 30% loss of activity and substantial loss of activity occurs only after deletion of all four Sp1 sites. indicating the critical importance of Sp1 in GR expression in these cells. In contrast, the elimination of the three YY1 sites results in a dramatic decrease in promoter strength in both HepG2 and Jurkat cells (64 and 77%, respectively). while subsequent deletions of promoter elements do not result in Substantial changes in promoter activity in these cell lines. This study shows that both promoters 1B and 1C are important For the ubiquitous expression of the human GR gene. Differences in the utilization of these promoters in various cell types are likely a reflection of different promoter availability arid or the levels of specific transcription factors in the cell. This Could contribute to tissue-Specific expression of GR levels in different cell types. (C) 2002 Elsevier Science Ireland Ltd. All rights reserved.