Characterization of three different elements in the 5'-flanking region of the fibronectin gene which mediate a transcriptional response to cAMP.
Characterization of three different elements in the 5'-flanking region of the fibronectin gene which mediate a transcriptional response to cAMP.
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发表时间：
1991-01
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通讯作者：
Christopher L. Bowlus;J. McQuillan;D. C. Dean
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作者：
Christopher L. Bowlus;J. McQuillan;D. C. Dean
先前对纤连蛋白基因的核苷酸位置-170处的cAMP调节元件(CRE)进行了表征(Dean, D. C.、Blakeley, M. S.、Newby, R. F.、Ghazal, P.、Hennighausen, L.和Bourgeois, S. (1989) Mol. Cell. Biol. 9, 1498-1506)。在这里，我们在核苷酸位置-260和-415处鉴定了两个额外的低亲和力CRE，其序列相差1个碱基对。有趣的是，这些 CRE 在凝胶阻滞测定中不会竞争与核蛋白的结合，并且蛋白质-DNA 复合物的部分胰蛋白酶消化产生与每个 CRE 不同的模式，表明它们结合不同的蛋白质。 CRE (-170) 竞争蛋白质与两个 CRE 的结合，表明它可能代表两种元素的复合体。 CRE (-415) 有效竞争核蛋白与生长抑素基因 CRE 的结合，这表明，与生长抑素 CRE 一样，它也与核蛋白 CREB 结合。另一方面，CRE (-260) 似乎与核蛋白 PEA-2 结合，PEA-2 也与多瘤病毒增强子中的一个位点结合。总之，CRE 3' 区域二元对称性的破坏（如 CRE (-260) 和 CRE (-415) 中发生的情况）会导致亲和力位点降低，并且还可能改变不同核蛋白的特异性。
A cAMP regulatory element (CRE) at nucleotide position -170 of the fibronectin gene was characterized previously (Dean, D. C., Blakeley, M. S., Newby, R. F., Ghazal, P., Hennighausen, L., and Bourgeois, S. (1989) Mol. Cell. Biol. 9, 1498-1506). Here we identify two additional low affinity CREs at nucleotide positions -260 and -415 which differ in sequence by 1 base pair. Interestingly, these CREs did not compete for binding of nuclear proteins in gel retardation assays and partial tryptic digestion of protein-DNA complexes produced a different pattern with each CRE, indicating that they bind different proteins. CRE (-170) competed for binding of proteins to both CREs, suggesting that it may represent a composite of the two elements. CRE (-415) competed effectively for binding of nuclear proteins to the somatostatin gene CRE, suggesting that, like the somatostatin CRE, it binds the nuclear protein CREB. On the other hand, CRE (-260) appears to bind the nuclear protein PEA-2, which also binds a site in the polyoma virus enhancer. In summary, disruption of dyad symmetry in the 3' region of the CRE, as occurs with CRE (-260) and CRE (-415), results in a lower affinity site and may also change the specificity for different nuclear proteins.