Epigenetic Regulatory Mechanisms Distinguish Retinoic Acid-mediated Transcriptional Responses in Stem Cells and Fibroblasts
Epigenetic Regulatory Mechanisms Distinguish Retinoic Acid-mediated Transcriptional Responses in Stem Cells and Fibroblasts
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DOI：
10.1074/jbc.m110.115345
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发表时间：
2010-05-07
影响因子：
4.8
通讯作者：
Gudas, Lorraine J.
中科院分区：
文献类型：
--
作者：
Kashyap, Vasundhra;Gudas, Lorraine J.
视黄酸（RA）是维生素A的代谢产物，通过与RA受体（RAR）和类维生素A X受体（RXR）异二聚体结合来调节转录。这种转录反应是由受体与转录调节因子和染色质修饰蛋白的相互作用决定的。我们比较了三种RA靶基因（Hoxa 1，Cyp 26 a1，RAR β（2））在原代胚胎成纤维细胞（小鼠胚胎成纤维细胞），永生化成纤维细胞（Balb/c3 T3）和F9畸胎瘤干细胞中的转录反应。Hoxa 1和Cyp 26 a1转录物不表达，但RAR β（2）转录物在小鼠胚胎成纤维细胞和Balb/c3 T3细胞中被RA诱导。维甲酸受体（RAR γ，RXR α），辅激活因子（pCIP（NCOA 3，SRC 3）），p300和RNA聚合酶II仅在Balb/c3 T3中被募集到RAR β（2）RA反应元件（RARE），而这些蛋白质在F9细胞中被RA募集到所有三个基因的RARE。在F9中，RA减少了所有三个基因的RARE处的多梳（PcG）蛋白Suz 12和相关的H3 K27 me 3抑制性表观遗传修饰。相反，在+/-RA中培养的Balb/c3 T3细胞中，Suz 12与Hoxa 1、RAR β 2和Cyp 26 a1 RARE无关，而在这些RARE中观察到低水平的H3 K27 me 3标记。因此，在不存在RA的情况下，Suz 12不是基因抑制所必需的。尽管Hoxa 1 RARE和近端启动子在Balb/c3 T3中显示高水平的H3 K9、K14乙酰化，但Hoxa 1基因不被RA转录激活。在Balb/c3 T3中，CpG岛在Cyp 26 a1启动子区域中甲基化，但在Hoxa 1启动子或F9细胞中的这些启动子中不甲基化。我们已经描绘了复杂的机制，控制RA介导的转录成纤维细胞与干细胞。
Retinoic acid (RA), a vitamin A metabolite, regulates transcription by binding to RA receptor (RAR) and retinoid X receptor (RXR) heterodimers. This transcriptional response is determined by receptor interactions with transcriptional regulators and chromatin modifying proteins. We compared transcriptional responses of three RA target genes (Hoxa1, Cyp26a1, RAR beta(2)) in primary embryo fibroblasts (mouse embryonic fibroblasts), immortalized fibroblasts (Balb/c3T3), and F9 teratocarcinoma stem cells. Hoxa1 and Cyp26a1 transcripts are not expressed, but RAR beta(2) transcripts are induced by RA in mouse embryonic fibroblasts and Balb/c3T3 cells. Retinoid receptors (RAR gamma, RXR alpha), coactivators (pCIP (NCOA3, SRC3)), and p300 and RNA polymerase II are recruited only to the RAR beta(2) RA response element (RARE) in Balb/c3T3, whereas these proteins are recruited to RAREs of all three genes by RA in F9 cells. In F9, RA reduces polycomb (PcG) protein Suz12 and the associated H3K27me3 repressive epigenetic modification at the RAREs of all three genes. In contrast, in Balb/c3T3 cells cultured in the +/-RA, Suz12 is not associated with the Hoxa1, RAR beta(2), and Cyp26a1 RAREs, whereas low levels of the H3K27me3 mark are seen at these RAREs. Thus, Suz12 is not required for gene repression in the absence of RA. Even though the Hoxa1 RARE and proximal promoter show high levels of H3K9, K14 acetylation in Balb/c3T3, the Hoxa1 gene is not transcriptionally activated by RA. In Balb/c3T3, CpG islands are methylated in the Cyp26a1 promoter region but not in the Hoxa1 promoter or in these promoters in F9 cells. We have delineated the complex mechanisms that control RA-mediated transcription in fibroblasts versus stem cells.