Wölfl S, Martinez C, Rich A, Majzoub J A
Department of Biology, Massachusetts Institute of Technology, Cambridge, 02139, USA.
Proc Natl Acad Sci U S A. 1996 Apr 16;93(8):3664-8. doi: 10.1073/pnas.93.8.3664.
The intron of the corticotropin-releasing hormone (corticoliberin; CRH) gene contains a sequence of over 100 bp of alternating purine/pyrimidine residues. We have used binding of a Z-DNA-specific antibody in metabolically active, permeabilized nuclei to study the formation of Z-DNA in this sequence at various levels of transcription. In the NPLC human primary liver carcinoma cell line, activation of cAMP-dependent pathways increased the level of transcription, while adding glucocorticoids inhibited transcription of the CRH gene. These cells respond in a manner similar to hypothalamic cells. Z-DNA formation in this sequence was detected at the basal level of transcription, as well as after stimulation with forskolin. Inhibition of transcription by dexamethasone abolished Z-DNA formation. Z-DNA formation in the WC gene (c-myc) was affected differently in the same experiment. Thus, changes in Z-DNA formation in the CRH gene are gene specific and are linked to the transcription of the gene.
促肾上腺皮质激素释放激素（促皮质素释放因子；CRH）基因的内含子包含一段超过100个碱基对的嘌呤/嘧啶交替残基序列。我们利用Z-DNA特异性抗体与代谢活跃的通透细胞核结合，研究该序列在不同转录水平下Z-DNA的形成情况。在NPLC人原发性肝癌细胞系中，cAMP依赖性途径的激活增加了转录水平，而添加糖皮质激素则抑制了CRH基因的转录。这些细胞的反应方式与下丘脑细胞相似。在基础转录水平以及用福司可林刺激后，均可检测到该序列中Z-DNA的形成。地塞米松抑制转录后，Z-DNA的形成消失。在同一实验中，WC基因（c-myc）中Z-DNA的形成受到不同影响。因此，CRH基因中Z-DNA形成的变化具有基因特异性，并与该基因的转录相关。
