Characterization of the 5'-flanking region of the rat thyrotropin receptor gene.
Characterization of the 5'-flanking region of the rat thyrotropin receptor gene.
复制标题
大鼠促甲状腺素受体基因 5-侧翼区域的特征。
作者：
S. Ikuyama;H. Niller;H. Shimura;Takashi Akamizu;L. D. Kohn
从ATG起始密码子[1个碱基(BP)]到第一内含子起始(170个碱基)的编码序列，包含了大鼠促甲状腺激素受体(TSHR)5‘侧翼区1.7kb碱基的基因组克隆。RNA酶保护、引物延伸和锚定聚合酶链式反应克隆的cDNA序列确定了多个转录起始点，主要的转录起始点聚集在-89到-68个碱基之间。这部分5‘-侧翼区既没有TATA，也没有CCAAT盒，富含GC，但没有GC盒基序，并且具有在“家务”基因中看到的启动子的特征。含有1.7kb(-1707~-2bp)5‘侧翼区或其缺失的嵌合体和细菌氯霉素乙酰转移酶(CAT)基因，在转染大鼠甲状腺细胞系FRTL-5和FRT时表现出显著的CAT活性，但不能导入BRL大鼠肝脏和HeLa细胞。TSH可降低稳定转染TSHR-CAT嵌合载体的FRTL-5甲状腺细胞的CAT活性。在不表达TSHR mRNA的FRT甲状腺细胞中，10微米Forsklin复制了TSH对启动子活性的负调控。缺失分析表明，一个具有启动子活性、组织特异性和TSH负调控作用的“最小”区域位于-195到-39个碱基之间；该区域在大鼠和人类TSHR基因中高度保守。MspI和HpaII对基因组DNA的差异消化表明，TSHR启动子在FRT细胞中发生甲基化，而在FRTL-5细胞中不发生甲基化；启动子甲基化可能与FRT细胞内源性TSHR基因表达的缺失有关。
Genomic clones containing 1.7 kilobases of the 5'-flanking region of the rat TSH receptor (TSHR) plus coding sequence from the ATG initiation codon [1 basepair (bp)] to the start of the first intron (170 bp) have been isolated and characterized. RNAase protection, primer extension, and cDNA sequences cloned by the anchored polymerase chain reaction identified multiple transcriptional start sites, the major ones clustered between -89 to -68 bp. This portion of the 5'-flanking region has neither a TATA nor a CCAAT box, is GC rich but has no GC box motif, and has features of promoters seen in "housekeeping" genes. Chimeras containing 1.7 kilobases (-1707 to -2 bp) of the 5'-flanking region, or deletions thereof, and the bacterial chloramphenicol acetyltransferase (CAT) gene expressed significant CAT activity when transfected into rat thyroid cell lines, FRTL-5 and FRT, but not BRL rat liver or HeLa cells. TSH decreased CAT activity in the FRTL-5 thyroid cells that had been stably transfected with the TSHR-CAT chimeric constructs. Negative regulation of promoter activity by TSH was duplicated by 10 microM forskolin in FRT thyroid cells, which express no TSHR mRNA. Deletion analyses indicated that a "minimal" region, exhibiting promoter activity, tissue specificity, and negative regulation by TSH, is located between -195 and -39 bp; this region is highly conserved in rat and human TSHR genes. Differential digestion of genomic DNA by MspI and HpaII revealed that the TSHR promoter is methylated in FRT, but not FRTL-5, cells; methylation of the promoter may be associated with loss of endogenous TSHR gene expression in FRT cells.
登录
查看更多内容
促黄体激素/绒毛膜促性腺激素通过受体介导的内吞作用和受体 mRNA 的 cAMP 依赖性减少来下调其受体。
DOI：
--
发表时间：
1991
期刊：
The Journal of biological chemistry
影响因子：
--
作者：
Wang,H;Segaloff,DL;Ascoli,M
通讯作者：
Ascoli,M
DOI：
10.1073/pnas.83.18.6682
发表时间：
1986-09-01
影响因子：
11.1
作者：
MONTMINY, MR;SEVARINO, KA;GOODMAN, RH
通讯作者：
GOODMAN, RH
DOI：
10.1073/pnas.85.23.8998
发表时间：
1988-12-01
影响因子：
11.1
作者：
FROHMAN, MA;DUSH, MK;MARTIN, GR
通讯作者：
MARTIN, GR
组成型启动子指导神经生长因子受体基因的表达。
影响因子：
5.3
作者：
Sehgal,A;Patil,N;Chao,M
通讯作者：
Chao,M
影响因子：
--
作者：
L. Heckert;I J Daley;M. D. Griswold
通讯作者：
L. Heckert;I J Daley;M. D. Griswold