Sp1-dependent Activation of HDAC7 Is Required for Platelet-derived Growth Factor-BB-induced Smooth Muscle Cell Differentiation from Stem Cells
Sp1-dependent Activation of HDAC7 Is Required for Platelet-derived Growth Factor-BB-induced Smooth Muscle Cell Differentiation from Stem Cells
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血小板衍生生长因子-BB 诱导平滑肌细胞从干细胞分化需要 Sp1 依赖性 HDAC7 激活
DOI：
10.1074/jbc.m110.153999
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发表时间：
2010-12-03
影响因子：
4.8
通讯作者：
Xiao, Qingzhong
中科院分区：
文献类型：
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作者：
Zhang, Li;Jin, Min;Xiao, Qingzhong
我们之前已经证明组蛋白脱乙酰酶7（HDAC7）表达和剪接在平滑肌细胞（SMC）从胚胎干（ES）细胞分化中发挥重要作用，但SMC分化过程中HDAC7表达增加的分子机制目前尚不清楚。在这项研究中，我们发现血小板衍生生长因子-BB (PDGF-BB) 诱导分化 ES 细胞中 HDAC7 转录本增加 3 倍。重要的是，我们的数据还表明，PDGF-BB 不是通过 HDAC7 磷酸化，而是通过转录激活来调节 HDAC7 表达。通过逐步删除分析其启动子，我们鉴定出Hdac7基因启动子5`侧翼区域-343和-292 bp之间的序列为最小的PDGF-BB响应元件，其中包含一个转录因子特异性蛋白1（Sp1）的结合位点。该 PDGF-BB 响应元件内 Sp1 位点的突变消除了 PDGF-BB 诱导的 HDAC7 活性。染色质免疫沉淀测定表明，PDGF-BB 处理增强了体内分化 SMC 中 Sp1 与 Hdac7 启动子的结合。此外，我们还证明，敲低 Sp1 消除了 PDGF-BB 诱导的 HDAC7 上调和分化 ES 细胞中 SMC 分化基因表达，尽管单独强制表达 Sp1 足以增加 Hdac7 启动子的活性和 SMC 分化基因的表达水平。重要的是，我们进一步证明HDAC7是Sp1诱导的SMC基因表达分化所必需的。我们的数据表明，在 ES 细胞向 SMC 分化的过程中，Sp1 在调节 Hdac7 基因表达中发挥着重要作用。这些发现为 HDAC7 的调节提供了新的分子见解，并增强了我们对胚胎发育过程中 SMC 分化和血管形成的了解。
We have previously demonstrated that histone deacetylase 7 (HDAC7) expression and splicing play an important role in smooth muscle cell (SMC) differentiation from embryonic stem (ES) cells, but the molecular mechanisms of increased HDAC7 expression during SMC differentiation are currently unknown. In this study, we found that platelet-derived growth factor-BB (PDGF-BB) induced a 3-fold increase in the transcripts of HDAC7 in differentiating ES cells. Importantly, our data also revealed that PDGF-BB regulated HDAC7 expression not through phosphorylation of HDAC7 but through transcriptional activation. By dissecting its promoters with progressive deletion analysis, we identified the sequence between -343 and -292 bp in the 5`-flanking region of the Hdac7 gene promoter as the minimal PDGF-BB-responsive element, which contains one binding site for the transcription factor, specificity protein 1 (Sp1). Mutation of the Sp1 site within this PDGF-BB-responsive element abolished PDGF-BB-induced HDAC7 activity. PDGF-BB treatment enhanced Sp1 binding to the Hdac7 promoter in differentiated SMCs in vivo as demonstrated by the chromatin immunoprecipitation assay. Moreover, we also demonstrated that knockdown of Sp1 abrogated PDGF-BB-induced HDAC7 up-regulation and SMC differentiation gene expression in differentiating ES cells, although enforced expression of Sp1 alone was sufficient to increase the activity of the Hdac7 promoter and expression levels of SMC differentiation genes. Importantly, we further demonstrated that HDAC7 was required for Sp1-induced SMC differentiation of gene expression. Our data suggest that Sp1 plays an important role in the regulation of Hdac7 gene expression in SMC differentiation from ES cells. These findings provide novel molecular insights into the regulation of HDAC7 and enhance our knowledge in SMC differentiation and vessel formation during embryonic development.