期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2010
卷号：107
期号：34
页码：15157-15162
DOI：10.1073/pnas.1003822107
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Surprisingly few pathways signal between cells, raising questions about mechanisms for tissue-specific responses. In particular, Wnt ligands signal in many mammalian tissues, including the intestinal epithelium, where constitutive signaling causes cancer. Genome-wide analysis of DNA cis-regulatory regions bound by the intestine-restricted transcription factor CDX2 in colonic cells uncovered highly significant overrepresentation of sequences that bind TCF4, a transcriptional effector of intestinal Wnt signaling. Chromatin immunoprecipitation confirmed TCF4 occupancy at most such sites and co-occupancy of CDX2 and TCF4 across short distances. A region spanning the single nucleotide polymorphism rs6983267, which lies within a MYC enhancer and confers colorectal cancer risk in humans, represented one of many co-occupied sites. Co-occupancy correlated with intestine-specific gene expression and CDX2 loss reduced TCF4 binding. These results implicate CDX2 in directing TCF4 binding in intestinal cells. Co-occupancy of regulatory regions by signal-effector and tissue-restricted transcription factors may represent a general mechanism for ubiquitous signaling pathways to achieve tissue-specific outcomes.
关键词：context specificity of signaling ; genome-wide chromatin immunoprecipitation ; signaling ; Wnt signaling in intestine ; tissue-specific gene regulation
