肿瘤坏死因子 α 诱导的低氧诱导因子 1α-β-连环蛋白轴通过染色质重塑调节主要组织相容性复合体 I 类基因的激活。
Tumor necrosis factor α-induced hypoxia-inducible factor 1α-β-catenin axis regulates major histocompatibility complex class I gene activation through chromatin remodeling.
机构信息
National Brain Research Centre, Manesar, Haryana, India.
出版信息
Mol Cell Biol. 2013 Jul;33(14):2718-31. doi: 10.1128/MCB.01254-12. Epub 2013 May 13.
Hypoxia-inducible factor 1α (HIF-1α) plays a crucial role in the progression of glioblastoma multiforme tumors, which are characterized by their effective immune escape mechanisms. As major histocompatibility complex class I (MHC-I) is involved in glioma immune evasion and since HIF-1α is a pivotal link between inflammation and glioma progression, the role of tumor necrosis factor alpha (TNF-α)-induced inflammation in MHC-I gene regulation was investigated. A TNF-α-induced increase in MHC-I expression and transcriptional activation was concurrent with increased HIF-1α, ΝF-κΒ, and β-catenin activities. While knockdown of HIF-1α and β-catenin abrogated TNF-α-induced MHC-I activation, NF-κB had no effect. β-Catenin inhibition abrogated HIF-1α activation and vice versa, and this HIF-1α-β-catenin axis positively regulated CREB phosphorylation. Increased CREB activation was accompanied by its increased association with β-catenin and CBP. Chromatin immunoprecipitation revealed increased CREB enrichment at CRE/site α on the MHC-I promoter in a β-catenin-dependent manner. β-Catenin replaced human Brahma (hBrm) with Brg1 as the binding partner for CREB at the CRE site. The hBrm-to-Brg1 switch is crucial for MHC-I regulation, as ATPase-deficient Brg1 abolished TNF-α-induced MHC-I expression. β-Catenin also increased the association of MHC-I enhanceosome components RFX5 and NF-YB at the SXY module. CREB acts as a platform for assembling coactivators and chromatin remodelers required for MHC-I activation in a HIF-1α/β-catenin-dependent manner.
缺氧诱导因子 1α(HIF-1α)在多形性胶质母细胞瘤肿瘤的进展中起着至关重要的作用,这些肿瘤的特征是其具有有效的免疫逃逸机制。主要组织相容性复合体 I 类(MHC-I)参与胶质瘤的免疫逃逸,并且由于 HIF-1α是炎症和胶质瘤进展之间的关键联系,因此研究了肿瘤坏死因子α(TNF-α)诱导的炎症在 MHC-I 基因调节中的作用。TNF-α诱导的 MHC-I 表达增加和转录激活与 HIF-1α、NF-κB 和 β-catenin 活性的增加同时发生。虽然 HIF-1α 和 β-catenin 的敲低消除了 TNF-α诱导的 MHC-I 激活,但 NF-κB 没有影响。β-catenin 抑制消除了 HIF-1α的激活,反之亦然,并且该 HIF-1α-β-catenin 轴正向调节 CREB 磷酸化。增加的 CREB 激活伴随着其与 β-catenin 和 CBP 的增加的关联。染色质免疫沉淀显示,在 β-catenin 依赖性方式下,在 MHC-I 启动子上的 CRE/site α 处增加了 CREB 的富集。β-catenin 用 Brg1 代替人 Brm(hBrm)作为 CRE 位点处 CREB 的结合伴侣。hBrm-to-Brg1 转换对于 MHC-I 调节至关重要,因为 ATPase 缺陷的 Brg1 消除了 TNF-α诱导的 MHC-I 表达。β-catenin 还增加了 MHC-I 增强子组件 RFX5 和 NF-YB 在 SXY 模块中的关联。CREB 作为一个平台,用于组装 MHC-I 激活所需的共激活因子和染色质重塑因子,这是一种依赖于 HIF-1α/β-catenin 的方式。