MAP Kinase-Dependent RUNX2 Phosphorylation Is Necessary for Epigenetic Modification of Chromatin During Osteoblast Differentiation.
MAP Kinase-Dependent RUNX2 Phosphorylation Is Necessary for Epigenetic Modification of Chromatin During Osteoblast Differentiation.
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DOI：
10.1002/jcp.25517
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发表时间：
2017-09
影响因子：
5.6
通讯作者：
Franceschi RT
中科院分区：
文献类型：
--
作者：
Li Y;Ge C;Franceschi RT
RUNX2 是成骨细胞分化和骨形成的重要转录因子，由 ERK/MAP 激酶依赖性磷酸化激活。然而，这些早期事件与成骨细胞分化过程中染色质的特定表观遗传修饰之间的关系尚未得到研究。在这里，我们使用染色质免疫沉淀 (ChIP) 来探索这些关系，以检测 Bglap2 和 Ibsp 的 RUNX2 结合区域中的染色质修饰。 MC3T3-E1c4 前成骨细胞在分化条件下的生长快速诱导 Bglap2 和 lbsp mRNA。对于这两个基因，成骨刺激增加了染色质结合的 P-ERK、P-RUNX2、p300 和 RNA 聚合酶 II 以及组蛋白 H3K9 和 H4K5 乙酰化。 H3K4 二甲基化（另一种基因激活相关组蛋白标记）的水平也增加。相比之下，同一区域的基因抑制标记（H3K9 单甲基化、二甲基化和三甲基化）水平降低。抑制 MAP 激酶信号传导可阻断分化依赖性染色质修饰以及 Bglap2 和 Ibsp 表达。为了评估 RUNX2 磷酸化在这些反应中的作用，用编码野生型或磷酸化位点突变体 RUNX2 (RUNX2 S301A/S319A) 的腺病毒转导 RUNX2 缺陷的 C3H10T1/2 细胞。野生型 RUNX2（而非非磷酸化突变体）增加了 H3K9 和 H4K5 乙酰化以及染色质相关的 P-ERK、p300 和聚合酶 II。因此，RUNX2 磷酸化对于成骨细胞基因表达所需的后续表观遗传变化是必要的。总而言之，这项研究揭示了一种分子机制，通过该机制，成骨基因受到 MAPK 和 P-RUNX2 依赖过程的控制，该过程涉及特定启动子区域的表观遗传修饰。
RUNX2, an essential transcription factor for osteoblast differentiation and bone formation, is activated by ERK/MAP kinase-dependent phosphorylation. However, relationship between these early events and specific epigenetic modifications of chromatin during osteoblast differentiation have not been previously examined. Here, we explore these relationships using chromatin immunoprecipitation (ChIP) to detect chromatin modifications in RUNX2-binding regions of Bglap2 and Ibsp. Growth of MC3T3-E1c4 preosteoblast cells in differentiation conditions rapidly induced Bglap2 and lbsp mRNAs. For both genes, osteogenic stimulation increased chromatin-bound P-ERK, P-RUNX2, p300 and RNA polymerase II as well as histone H3K9 and H4K5 acetylation. The level of H3K4 di-methylation, another gene activation-associated histone mark, also increased. In contrast, levels of the gene repressive marks, H3K9 mono-, di-, and tri-methylation, in the same regions were reduced. Inhibition of MAP kinase signaling blocked differentiation-dependent chromatin modifications and Bglap2 and Ibsp expression. To evaluate the role of RUNX2 phosphorylation in these responses, RUNX2-deficient C3H10T1/2 cells were transduced with adenovirus encoding wild type or phosphorylation site mutant RUNX2 (RUNX2 S301A/S319A). Wild type RUNX2, but not the non-phosphorylated mutant, increased H3K9 and H4K5 acetylation as well as chromatin-associated P-ERK, p300 and polymerase II. Thus, RUNX2 phosphorylation is necessary for subsequent epigenetic changes required for osteoblast gene expression. Taken together, this study reveals a molecular mechanism through which osteogenic genes are controlled by a MAPK and P-RUNX2-dependent process involving epigenetic modifications of specific promoter regions.