Guerra-Calderas Lissania, González-Barrios Rodrigo, Patiño Carlos César, Alcaraz Nicolás, Salgado-Albarrán Marisol, de León David Cantú, Hernández Clementina Castro, Sánchez-Pérez Yesennia, Maldonado-Martínez Héctor Aquiles, De la Rosa-Velazquez Inti A, Vargas-Romero Fernanda, Herrera Luis A, García-Carrancá Alejandro, Soto-Reyes Ernesto
Cancer Biomedical Research Unit, Instituto Nacional de Cancerología (INCan), Mexico City, Mexico.
The Bioinformatics Centre, Section for RNA and Computational Biology, Department of Biology, University of Copenhagen, Copenhagen, Denmark.
Oncotarget. 2018 Mar 30;9(24):17028-17042. doi: 10.18632/oncotarget.24798.
Histone demethylase KDM4A is involved in H3K9me3 and H3K36me3 demethylation, which are epigenetic modifications associated with gene silencing and RNA Polymerase II elongation, respectively. is abnormally expressed in cancer, affecting the expression of multiple targets, such as the gene. This enzyme localizes at the first intron of , and the dissociation of KDM4A increases gene expression. assays showed that KDM4A-mediated demethylation is enhanced in the presence of CTCF, suggesting that CTCF could increase its enzymatic activity however the specific mechanism by which and might be involved in the gene repression is poorly understood. Here, we show that CTCF and KDM4A form a protein complex, which is recruited into the first intron of . This is related to a decrease in H3K36me3/2 histone marks and is associated with its transcriptional downregulation. Depletion of or KDM4A by siRNA, triggered the reactivation of expression, suggesting that both proteins are involved in the negative regulation of this gene. Furthermore, the knockout of restored the expression and H3K36me3 and H3K36me2 histone marks. Such mechanism acts independently of promoter DNA methylation. Our findings support a novel mechanism of epigenetic repression at the gene body that does not involve promoter silencing.
组蛋白去甲基化酶KDM4A参与H3K9me3和H3K36me3的去甲基化过程，这两种表观遗传修饰分别与基因沉默和RNA聚合酶II延伸相关。KDM4A在癌症中异常表达，影响多个靶点的表达，如 基因。该酶定位于 基因的第一个内含子处，KDM4A的解离会增加基因表达。实验表明，在CTCF存在的情况下，KDM4A介导的去甲基化作用增强，这表明CTCF可能会增加其酶活性，然而，CTCF和KDM4A可能参与 基因抑制的具体机制尚不清楚。在这里，我们发现CTCF和KDM4A形成一种蛋白质复合物，该复合物被招募到 基因的第一个内含子中。这与H3K36me3/2组蛋白标记的减少有关，并与其转录下调相关。通过小干扰RNA（siRNA）耗尽CTCF或KDM4A会触发 基因表达的重新激活，这表明这两种蛋白质都参与了该基因的负调控。此外，敲除CTCF可恢复 基因的表达以及H3K36me3和H3K36me2组蛋白标记。这种机制独立于 基因启动子的DNA甲基化起作用。我们的研究结果支持了一种新的基因本体表观遗传抑制机制，该机制不涉及启动子沉默。
