Suppression of ANP gene transcription by liganded vitamin D receptor - Involvement of specific receptor domains
Suppression of ANP gene transcription by liganded vitamin D receptor - Involvement of specific receptor domains
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DOI：
10.1161/01.hyp.31.6.1338
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发表时间：
1998-06-01
期刊：
影响因子：
8.3
通讯作者：
Gardner, DG
中科院分区：
文献类型：
--
作者：
Chen, SC;Wu, JM;Gardner, DG
我们以前发现，配体维生素D受体（VDR）的影响抑制人心钠素（hANP）基因启动子活性在培养的新生大鼠心房肌细胞。在本研究中，我们试图确定参与介导这种抑制的VDR结构域。我们研究了一系列VDR突变体对共转染hANP启动子驱动的氯霉素乙酰转移酶（CAT）报告基因的影响。在不存在1，25-二羟基维生素D-3（VD 3）配体的情况下，天然VDR和任何测试的突变体都不显示抑制活性。Delta 134（一种仅含有VDR DNA结合区的缺失体）和L254 G（一种在其他系统中显示类维生素A X受体（RXR）异源二聚体形成缺陷的突变体）在降低启动子活性方面与天然VDR一样有效。HBD，一个只含有VDR的酶结合结构域的缺失体，和K246 G，一个在受体的激活功能中有缺陷的点突变体，没有减弱报告活性。当在这些细胞中检查含有直接重复维生素D响应元件（DR 3-CAT）的正调控启动子时，显示出类似的活性特征。配体VDR、Delta 134突变体和配体L254 G分别使DR 3-CAT活性增加2.5倍、2倍和4倍。VD 3的两种非高钙类似物（RO 23-7553和RO 25-6760）显示出与VD 3相同的抑制活性。这些研究表明，hANP启动子活性的抑制需要受体的DNA结合和激活功能，但似乎不需要形成经典的RXR α-VDR异二聚体。
We showed previously that liganded vitamin D receptor (VDR) effects a suppression of human atrial natriuretic peptide (hANP) gene-promoter activity in cultured neonatal rat atrial myocytes. In the present study, we have attempted to identify the structural domains of the VDR that are involved in mediating this suppression. We examined the effects of a series of VDR mutants on a cotransfected hANP promoter-driven chloramphenicol acetyltransferase (CAT) reporter. Neither the native VDR nor any of the mutants tested displayed inhibitory activity in the absence of the 1,25-dihydroxyvitamin D-3 (VD3) ligand. Delta 134, a deletant harboring solely the DNA binding region of the VDR, and L254G, a mutant shown to be defective in retinoid X receptor (RXR) heterodimer formation in other systems, were as effective as the native VDR in reducing promoter activity. HBD, a deletant containing only the hormone-binding domain of the VDR, and K246G, a point mutant that is defective in the activation function of the receptor, did not attenuate reporter activity. A similar activity profile was displayed when a positively regulated promoter containing a direct-repeat vitamin D responsive element (DR3-CAT) was examined in these cells. Liganded VDR, the Delta 134 mutant, and liganded L254G effected increases in DR3-CAT activity of 2.5-, 2-, and 4-fold, respectively. Two nonhypercalcemic analogues of VD3 (RO 23-7553 and RO 25-6760) displayed the same inhibitory activity as VD3. These studies suggest that the inhibition of hANP promoter activity requires both the DNA binding and activation functions of the receptor but does not appear to require formation of a classic RXR alpha-VDR heterodimer.