Li S, Moy L, Pittman N, Shue G, Aufiero B, Neufeld E J, LeLeiko N S, Walsh M J
Department of Pediatrics, Division of Pediatric Gastroenterology and Liver Diseases, Mount Sinai School of Medicine, New York, New York 10029, USA.
J Biol Chem. 1999 Mar 19;274(12):7803-15. doi: 10.1074/jbc.274.12.7803.
Human cystic fibrosis transmembrane conductance regulator gene (CFTR) transcription is tightly regulated by nucleotide sequences upstream of the initiator sequences. Our studies of human CFTR transcription focus on identifying transcription factors bound to an inverted CCAAT consensus or "Y-box element." The human homeodomain CCAAT displacement protein/cut homolog (CDP/cut) can bind to the Y-box element through a cut repeat and homeobox. Analysis of stably transfected cell lines with wild-type and mutant human CFTR-directed reporter genes demonstrates that human histone acetyltransferase GCN5 and transcription factor ATF-1 can potentiate CFTR transcription through the Y-box element. We have found 1) that human CDP/cut acts as a repressor of CFTR transcription through the Y-box element by competing for the sites of transactivators hGCN5 and ATF-1; 2) that the ability of CDP/cut to repress activities of hGCN5 and ATF-1 activity is contingent on the amount of CDP/cut expression; 3) that histone acetylation may have a role in the regulation of gene transcription by altering the accessibility of the CFTR Y-box for sequence-specific transcription factors; 4) that trichostatin A, an inhibitor of histone deacetylase activity, activates transcription of CFTR through the Y-box element; 5) that the inhibition of histone deacetylase activity leads to an alteration of local chromatin structure requiring an intact Y-box sequence in CFTR; 6) that immunocomplexes of CDP/cut possess an associated histone deacetylase activity; 7) that the carboxyl region of CDP/cut, responsible for the transcriptional repressor function, interacts with the histone deacetylase, HDAC1. We propose that CFTR transcription may be regulated through interactions with factors directing the modification of chromatin and requires the conservation of the inverted CCAAT (Y-box) element of the CFTR promoter.
人类囊性纤维化跨膜传导调节因子基因（CFTR）的转录受到起始序列上游核苷酸序列的严格调控。我们对人类CFTR转录的研究重点是鉴定与反向CCAAT共有序列或“Y盒元件”结合的转录因子。人类同源结构域CCAAT置换蛋白/cut同源物（CDP/cut）可通过一个cut重复序列和同源异型框与Y盒元件结合。对稳定转染有野生型和突变型人类CFTR导向报告基因的细胞系进行分析表明，人类组蛋白乙酰转移酶GCN5和转录因子ATF-1可通过Y盒元件增强CFTR转录。我们发现：1）人类CDP/cut通过与转录激活因子hGCN5和ATF-1竞争位点，作为CFTR转录通过Y盒元件的抑制因子；2）CDP/cut抑制hGCN5和ATF-1活性的能力取决于CDP/cut的表达量；3）组蛋白乙酰化可能通过改变CFTR Y盒对序列特异性转录因子的可及性，在基因转录调控中发挥作用；4）组蛋白脱乙酰酶活性抑制剂曲古抑菌素A通过Y盒元件激活CFTR转录；5）组蛋白脱乙酰酶活性的抑制导致局部染色质结构改变，这需要CFTR中完整的Y盒序列；6）CDP/cut的免疫复合物具有相关的组蛋白脱乙酰酶活性；7）负责转录抑制功能的CDP/cut羧基区域与组蛋白脱乙酰酶HDAC1相互作用。我们提出，CFTR转录可能通过与指导染色质修饰的因子相互作用来调控，并且需要CFTR启动子的反向CCAAT（Y盒）元件保持保守。
