Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892.
University of Alabama at Birmingham Stem Cell Institute, University of Alabama at Birmingham, Birmingham, AL 35294.
Proc Natl Acad Sci U S A. 2019 Mar 26;116(13):6130-6139. doi: 10.1073/pnas.1900107116. Epub 2019 Mar 13.
We have identified regulatory mechanisms in which an RNA transcript forms a DNA duplex·RNA triple helix with a gene or one of its regulatory elements, suggesting potential auto-regulatory mechanisms in vivo. We describe an interaction at the human locus, in which an RNA segment embedded in the second intron of the gene forms a DNA·RNA triplex with the HS2 sequence within the locus control region, a major regulator of expression. We show in human K562 cells that the triplex is stable in vivo. Its formation causes displacement from HS2 of major transcription factors and RNA Polymerase II, and consequently in loss of factors and polymerase that bind to the human and promoters, which are activated by HS2 in K562 cells. This results in reduced expression of these genes. These effects are observed when a small length of triplex-forming RNA is introduced into cells, or when a full-length intron-containing human transcript is expressed. Related results are obtained in human umbilical cord blood-derived erythroid progenitor-2 cells, in which expression is similarly affected by triplex formation. These results suggest a model in which RNAs conforming to the strict sequence rules for DNA·RNA triplex formation may participate in feedback regulation of genes .
我们已经确定了一些调节机制，其中 RNA 转录本形成与基因或其调控元件之一形成 DNA 双链·RNA 三链的双链体，这表明体内可能存在自动调节机制。我们描述了人类 基因座中的一种相互作用，其中嵌入 基因第二内含子中的 RNA 片段与 基因座控制区（HS2）内的 HS2 序列形成 DNA·RNA 三链体，这是 表达的主要调控因子。我们在人类 K562 细胞中表明，该三链体在体内稳定存在。其形成导致主要转录因子和 RNA 聚合酶 II 从 HS2 上移位，从而导致与人类 和 启动子结合的因子和聚合酶丢失，这些启动子在 K562 细胞中被 HS2 激活。这导致这些基因的表达减少。当引入一小段形成三链体的 RNA 时，或者当表达全长包含内含子的人类 转录本时，会观察到这些效应。在人类脐带血衍生的红系祖细胞-2 细胞中获得了相关结果，其中三链体的形成同样影响 的表达。这些结果表明，符合 DNA·RNA 三链体形成严格序列规则的 RNA 可能参与基因的反馈调节。
